microprocessor control system for the injection...
TRANSCRIPT
MICROPROCESSOR CONTROL SYSTEM
FOR THE INJECTION MOLDING PROCESS
by
@ Andrew Haber
A Thesis Submitted to the Fa~ulty of Graduate Studies
and Researeh in Partial Fulfillment of the
Requirements for the Degree of
Master of Engineering
Department of Chemieal Enqineeri~q MeGill university Montreal, Canada February l 9 8 2
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ABSTRACT ,j
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<;; J;njection molding' economics an~ ithe quality of injection----
mo.l~~ products are signifj.can~ly et~anced b~ the utilization
of hticroprocessor or ,computer contr systems. ,,~
A Danson Metalmec' SR-60 injecti il molding machine was
redesiqned ând modified for operat' 0 using a 'micI'oprOcessor
based serve dontrôl system. The v r~atili ~y of th~ micro
processor system was demon'strat:d s~ng beth open loop and 1
clo~ed lo.op programs utilizing ca vi tr' nozz~e and hydraulic , !
pressure, and .ram displacement as th/e feedback elements. , 1
The process variabi~ity ·was shown tq be reduced usin9 the 1 •
9pen loop control program as a cQ.ns+que~ce of incorporating
a servovalve based' hydraulic systemL Fin~lly, the versa
tility of the microprocessor system was dernonstrated using
various types ,of s'et point profiles to obtain pressure-time
and veloci ty-time closed loop control •
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1!) i RESUME ,,1
La qUalit~' d~s produits ainsi que le renderltent du
procédé de moulage par injection, peuvent être
à des améliorés grâce (à l'utilisation de mièroprç>cess "
fin de contrô.le.~ Une machine\l à injection" Danson Metalmec 60, a
été modifi~ pour fonctionner à l'aidefl d'un syst,ê e de ~ '\ l ...
contrôle par micrbprocesseur. La' versatili té du \ système -"' \
de contrôle a été demontrée à l'aide de programme\s de
- ! contrôle en boucle ouverte et fermée. La pressïon a
l'intérieur de la cavité, dans le ne~ \ de la vis et du ~ ()
Isystème hydraulique, ainsi que la position de ra vis ont 1 • \
été utilisée~ comme information de retour de la part du
système.
Une diminution des fluctuations lors du procéd a été
enregistrée en mode de contrôle en boucle ouverte .
\ conséquemment a l~ modification du système hydraulique.
Finalement, l'éventai). des possibilités du systême de ' -, , ' .
contrôle avec microprocesSeur a été démontré al' aide de
différepts modes d'opération pour v~rifier la qualité du
contrôle en boucle fermé sur les profils de pression vs. ,. temps et vitesse vs timps.
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ACKNOWLEDGEMEN,!,S
l wish ta express my gratitude to al! the people
who contributed tQ the present study.
In partJ:cuIar, l am especially indebted to my
Research Direc or, P~ofessar Musa R. Kamal, for his .
guidance and en ouragement throucgho~t the duration
of this work. ~ In addition .~ould like ta thank:
- Profess,or I. pat erson, for his advice, \comments
discussions thrO~ghout the course of thiJ\ '~tudYi \
Mrs. Lynda P i lkin~ton for her persever ance\ and
cansci entiaus effo'hs in, t yping this manus1r ipt ;
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" TABLE OF CONTENTS'
ABSTRACT
ACKNOWLEDGEMENTS
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
1.' INTRODUCTION,
2. TECHNICAL BACKGROUND
2.1 ' Process Variables 2.2 Product Characteristics 2.3 Process Variabi1ity
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2.4 Therrnoplastic Inje'ction Moldinq Mode1s 2.5 Available Control Schemes
3.. PROJECT OBJECTIVES r: 1_
4. SYSTEM DESCRIPTION 61
5.
6.
7.
1 4.1 Danson Metqlmec SR-60 Injection Moldinq
4.2 4.3'
Machine" , . Microprqcessor Control System KPH Control'Syst~m
CONTROL STRATEGY
5.1 Control Backqround
"
5.2 Digital Forrn of the Proportional Controller 5.3 CIQsed Loop Control Reaiization
MOLD~NG EXPERIMENTS
EquiPment ) \,~./------: !
Control Scheme Evaluation Experimental Procedure
~ULTS AND DISCUSSIONS
7 ~ Cavity Pres'sure Control 7 . 2 Veloci ty Control 7.3 Nozz1e Pressure Control 7.4 Hydraulic Pres~ure Control
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6 11 14 20 26
31
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46 51
63
63 65 68
72
'72 73 74
84
84 93
101 112
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.. ) 8. SUMMARY ~D CONCLUSIONS
'Ç
9. BIBLIOGRAPHY
APPENDIX l COMPUTER HARDWARE
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MOOG AO-76-l03 SERVOVALVE OPTO 22 ~/O Modules .
. AI.I Al. 2 Al. ~ AI.4
Ana10g to Digital Converter (ADC) Digi ta~ to Ana10g Converter (DAC)'
APPENDIX 2 INSTRUf1,ENTATION
-A2.1 A2.2 A2.3 A2.4
Transducer System Linear Disp1acement Transducer Rectangular Cavity I~jection Nozzlè Design
AP~ENDIX 3 COMPUTER PROGRAMS
/ A 3,. 1 'A3.2-à3.3 ~~: 4. A3. 5'
Seque~ce Subroutine Listings Remaining Sequencing Subroutines Music Translator program ' Clased Loop' Control Program Open Loop Control Prog7am
APPENDIX 4 RECOMMENDATIONS
APPENDIX 5
A4. 1 Software A4 • 2 Hardware
DATA ., '\
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123
123 12'3 127 127
132
132 134 134 138
140
140 143 150 157 169
172
172 174
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Figure
1.1
2.1
2.2
2.3
2.5
2.6
2.7
2.8
2.9
2.10
2.11
; 2.12
2.13
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, LIST OF FIGURES -<
Çaption
Cavity Pressure Variation During an Injection Cycle'
. Hydrau1ic Pressure, Nozz~e 'Pressure, and Ram Oi~lacement Profiles' During an 'II Injection Moldin'q Cycle, Oanson MetaJmec
, SR-60 Injection MoldiJ:)q Machin,e
Pressure Distribution at the End of Filling, Doan (2)
. Progression of the Melt Front During the Filling Stage ion a Rectangular Mold , Dqan (2)
--------EUee-t--of "Process-Variables on.-Shrinkage (High Impact p. s. )
" Effect of Injection Pressure on Volumetrie Shrinkage (37) \
Effect of Injection Cylinder Temperature on Volumetrie Shrinkage (37)
Relationship Between Cavity Pressure and Shot weights (15) .
Relationship Betwèen Sl10t Weignt and Nozzle Pressure (15)
Effeet of Moldinq Variables on Tensile StrEmgth of Injection Mo1dJd High' Impact· Polystyrene
Effect of Molding Conditions on Frozen Stresses in Injection Mo1ded Polypropylene
Variations of Melt Pressure in the Nozzle (15) \. '
, Pressure Variations in Three Consecutive Moldings (15)
Hydraulic Ram Pressure Profiles for Three Screw Type Injection HOlding Machines
8
9
10
12
12
1,2
13
.13
15
15
11
,17
18
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2.14
2.15
4.8
4.9
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" LIST OF FIGt'1RES'
Caption _ '. il ,
Hydrau1ic Ram Pressure After an Overhaùl. o~ the Hydrauli.c:, System
T~e Interaction of Hydraulic Pressur~ -Fluctuati.ons wi t;h Other Process Variable!; (17 )
Swnmary of the Relationships Ob~ined' by Peter (22)
, 18
19
Functiohal MOdel of the Computer Control.led "24 System of Ma (24)
Danson Meta1mec SR-60 Injection Moldi~g Machine .
Hydrau1ic Syst9!ll __ ~~h!!~atic Dans~n Metal~ec 'SR-60 Injection Molding Machine.
, -
Sequencing of the ,Hydra\llic System Sol.enoids '
Electrical. Diagrarn for the Danson Metalmec SR-60 tnjecHon M01ding Machine
E1ectI'ical System Sequencing Flowcha~t. ,
Cavi ty Pressure Profiles, High-Lighting t:he Variation in Peak Pressures '
Error Histogram for the Distribution, of Peak Pressures . ,
'Pressure vs Time Profile During an Injection
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39
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42 43
45 '
4'8 . 'Cycl.e ~
RPH 'Hydrauliê'°System Schematic 53
Electrical' and Hydraulic Sequencing of the 56 RPH System ~
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4. II KPH Computer System 57
Simpl'ified .Logic DtagJ;'am of ,the E1ectrical System
KPH \
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4.13
4.14
5.1 0
5.2
5.3
5.4
6.1
6.2
JI 6.3 r"I
6.4
6.5
, , 6.6
7.1
7.2
7.3
7.4
7. SA
7.5B
7.6
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LI-ST OF FIGURES
Caption
SEQUE Prograrn F10wchart
Memory Map RPH System
Simple Clo$ed Loop Block Diagram
KPH Controller Block Diagram
Closed Possibilities KPH System
• Closed Loop Cont:ol Program Flowchart
The Technique for Estimating the Cavity Pressure Set Point Profile
Cavity Pressure vs T~me Set Point Profile
Nozzle Pressure vs Time Set Point Profile
Linear Disp1acement vs Time Set Point Profile
Hydraulic Pr~ssure vs Time Set Point Profile
Flowchart of the Closed Loop Control Experimental Procedure
Open Loop Responseof the Cavity Pressure at Various Valve Openi'ngs
Peak Cavity Pressure Error Histogram
Cavity Pressure "vs Time Re~se - Closed Loop Run Using a 62% Open Loop\Set Point Profile
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62
64
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67
70
75
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79
81
85
87
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Cavity 'Pressure vs Time Close~ Loop 91 Response Using Set Point Profile B
Linear Disp1acement vs Time Open Loop Data ,,', 94
Velocity vs Valve Position Open Loop Data (
,Linear Disp1acement vs Time Closed Loop Response for a 62% Open Loop Set Point 'Profile
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Figure
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7.8
7.9
7.10
7.11
7.12
7.13
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LIST OF FIGURES
Caption
Closed.Loop Linear Displacement vs Tirne Response for a Run Using Set Point Profile B
Closed Loop Linear Displacement vs T1me Response for a Step Change Set Point Prof ile
Closed Loop Veloci ty-Time Response for the Step Change Profile
The Variation of the Nozzle and Hydraulic P~es sure for the C10sed Loop Linear Disp'lacement Response to a Step Change Pro fil e 1 G = 16 a
Open Loop Nozzle Pressure vs Time Response
Peak NozzJ.e Pressure Error Histogram
Hydraulic Pressure vs Time Profiles; Illustrating the Variability of the Hydraulic P~essure Response for a Closed Loop Nozzle Pr~ssure Test Using a 62% Open"'Loop Set Point Profile 1 G = 16
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98
99
100
102
103
106
7.14 Process Variable Responses for a Closed 107 Loop Nozzle Pressure Test Using a 62%
7.15
7.16
7.17
7.18
7.19
'1 Sèt Point Profile, G = 96
Closed Loop Nozz1e Pressure vs Time Response for a 62% Open Loop Set Po in t Profile
Closed Loop Nozzle Pressure vs Time Response for a Set Point Profile A
Closed LOQp Nozzle Pressure vs Time Response for a Set Point Profile B
. Closed Loop Response for Set Point , Prof~le B, G = 48
Open Loop Hydraulic Pressure-Tirne Data
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110
III
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7.22
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2A2
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LIST OF, FIGURES
Caption
Closed Laop Hydraulic Pressure Data for a 62% Open Laop Set Point Profile
Closed Loop Hydraulic Pressure Responses for a Step Change Set Point Profile
Nozzle Pressure and Linear Displacement Responses for a Test Using the Hydraulic Pressure Step Change Profile, G = 160
Change in Ra ted Flow wi th Pressure
Step Response
Servo Amplifier Circuit ()
Signal Conditioner Circuit for the Linear Displacement Transducer
ADC Operation Flowcaart
Analog to Diqital Convert~ Schematic
Digital to Analog Converter Schematic
Linear Displacement Transducer Calibration Curve, Excitation 6 V f
Cavity and Back-Up Plate Showing Transducer and Thermocouple Locations
Cross-Section of Mqld
Cross-Section throuqh Instrumental Nozz1e
Music Translator program Flowchart
Control Equation Program Flowchart
Open Loop Program Flowchart
Hydraulic System Modifications
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125
128
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130
131'
135
136
137
139
151
158
171
176
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2.2
4.1
4.2
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6.2
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LIST OF' TABLES J Title
Re1ationships for a Computer Contro11ed System, Ma (24)
Cornrnon Co~trol Strateqies
Hydraulic System Solenoid Description
Control Variables
Open Loop Operatin~ Conditions for the Experimental Mo1dinq Studies
Closed Loop Oneratinq Conditions for the Experimental Study
Regression Coefficients for the Transducer Calibration Equations
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28
38
50
82
83
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CHAPTER l
INTRODUCTION
Injection mGlding is the process in which a thermo-
plastic resin is melted and then injected under pressure
into a cold mold where it solidifies. ~1odern injection
mold1ng ,machines are of the reciprocatinq scre~type. The
main components of an injection molding machine are the~elt
injection unit and the mold clamping unit. The injection j
unit melts the plastic with the aid of external heaters and
the heat generated by the shearing and compressing action of
the screw. The molten plastic is then injec~ed into the mo1d
which is he1d closed by the clampinq unit.
The molding cycle consists of three staqes as shown in
the qraph of cavity pressure versus time (Fiqure 1.1).
During the fillinq stage, the polymer melt flows into the
cold mold under relatively low pressure. When the cavity
is filled, a high packing pressure is employed to force
additional polymer into the mold. The purpose of this step,
n9rmally referred to as the packing stage, is to introduce
sufficient polymer into the cavity in order to compensate for
shrinkage during the third stage, i.e. the cooling stage.
Cooling is continued until the solidified plastic is suffi-
ciently rigim to he removed from the mold without damage.
Simultaneously dUFing coolincr, polymer is plas~icated for
the next cycle.
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FIGURE 1.1 Cavity Pressure Variation During an Injection Molding Cycle
<; TIME
1. Filling ...
2. Packing
3. Cooling
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The injection molding of thermoplast·ic materials is
Characterized by complex 'interactions between the material,
machine and mold desiqn, and mOlding conditions. Thes,~
interactions ultimately determine the moldability of the
material, the economics of the process and the properties
of the molded article. , '
As a result df the increasinq cost of polymerie resins
and the d~indling hydrocarbon energy supplies, closed loop
cofttrol of the injection molding process i5 becominq an
1mportant field Qf, concentration. The optimization and control ~.) ,
of parameters as injection pressure, velocity and shot-size
durinq the mOlding cycle could reduce both the cycle time and
material wastage while producing parts with the de5ired "
physical and m'icrostructural properties.
Traditionally, \n;ection moldinq machines have been
equipped with either manual or solid state autornatic control.
In recen~ y~ais, a number of computer or microprocessor based
control systems have been introduced in'conjunction with ~
inj ection molding machines.' However, practically aIl of the
latter systems employ basically the same strategies that have
been employed in earlier control systems. There is a need to
develop new control strategies in order to make better use
of the substantially better capabilities of the microprocessor
systems and in order to achieve better control and optimization
of the molding conditions.
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The present work deals with the design, construction
and operation of a versatile microprocessor system for
achievinq improved control of the thermoplastic injectiàn
moldinq process. As part of a larqer continuing research
project, this thesis reports on the first staqe of the effort
which ~als with the modification of the injection molding
machine and the installat~on and testing of the hardware
and software components qi the microprocessor system.
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CHAPTER 2
TECHNICAL BACKGROUND
Sorne of the important characteristics of the inject~on
molding process are outlined below:
- injectio~ mOlding is a ~yclic process.
- injection moldinq is an unsteady state process:
its variables chanqe with time.
injection moldinq is a conversion process in which
phase changes occur that influence process behavior
and product properties.
The important process, machine and product quality
variables are as follows:
Process Variables
Cavity pressure
Nozzle pressure
Rarn velocity
Part ternperature
Melt ternperature
Cushion size
Part Qualities
Surface finish
Part density . . ( Part dl.rnensl.ons
Orientation
Tensile strength "
Machine Variables
Barrel temperature
Mold Temperature
Hydraulic pressure
Injection ram back pressure
Screw rotational speed
Shot size
In;ection and holding times
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Part Oualities (Con't)
Impact strenqth
Opticai properties
Crystailinity
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; . '" . Generally, it is desirable to man~pulate process var~-
ables 50 as to minimize production costs while meeting and
mainta\~inq product quality specifications. Due consideration
Should~e aIra qiven to factorr' li*e ~roduct reproduc~bility
and the .life1and maintenance costs of the machine, tools and
aux±llary 'equipment. Sorne of the relevant aspects associated .. .
w~th process variables, product quality, and process ~epro-1
ducibility are discussed below.
2~1 Process Variables
The main process variables beyond the plasticating stage
are: the' injection temperature, pressure and speed and the
distributions of temperature, pressure and velocity in the
mold cavity. The time ~eh4ance of the above variables is
aiso important.
Thlê injeçtion ternperature 'is deterrnined by the barrel
temperature setti~qs ~crew speed durinq plastication.
Injection pressure and speed de pend mainly on the hydraulic
pressure applied to the back end of ~he ~crew. Obviously, L \
the dimensions of the screw, and barrel play an important part . in deterrnining the above variables. In the present.study,
no effort has bjen made to apply micro~roc~ssor control ta
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nozzle temperature since the conventional (unmodified machine ,
control system) was employed to control this temperature.
However, microprocessor control has been employed to control
the nozz1e pressure and injection speed. A typical combin-
ation of profiles ref1ectinq the variations of hydraulic
pressure, nozzle pressure, and injection speed i~ an
1njection moldinq cycle is shown id Figure 2.1.
Conditions in the cavity depend on the conditions pre-
vailing at the nozzle (i.e. melt temperat~re, injection
pressure, injection speed, etc.), nozzle dimensions, the
dimensions and prevai1ing thermal conditions ,in the sprue,
runner and qate, and mold tempera'ture and dimensions. The
nature of the space-time distribution of pressure, ternperature
and velocity in the mold during the filling, packing and \
coo1ing stages is complex. Since it is difficult to make ,
measurements of most of these variables, computer models
have been employed to obtain sorne estimates (l, 2, 3, 4).
Sorne success has been encountered with such models, as shown
in Figure 2.2 for the pressure distribution in a rectangular
cavity and Figure 2.J for the proqreg~i~n of the melt front
during the fillinq stage.
Control of process variables is important to in sure
hiah production rates and to avoid prqblerns like short shots
(due to solidification before complete filling), flash (due
to high pressure build-up in the cavity), thermal degradation "'-
(due to excessive heating) and ether undesirable effects.
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FIGURE 2.1 Hydraulic Pressure, Nozzle pressu{e and Raro Displacernent Profiles During an I~ection Mold~ng Cycle, Danson Metalmec SR-GO Injection Moldinq Machine
1. FlpoING
2. l'ACJr:ING
3. COOLDIG
4. Pt..ASTlCATIOH 3 2
4 LIHEAJt OISPLACKJŒNT
0,
2
NOULE PRESSlIR!
r 1 u
2.2
e..l5
r ... ., Q.
176
J --------~--------~~------------------==~------------~o
4 i
:3
HYDRAULIC PlI&SSlIRE
120
'l'1MB, SZC:.. .. ____ ...... ____ _
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FIGURE 2.2 Pressure Distribution at the End of Fil1ina Dean (2) PE . 2 511 C~ se 5
THEORETICAL
+ EXPERIMENTAL .8
.6
.4
.2
~
0 2 4 6 8 9
Il
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DISTANCE R(iNCH)
1
1
1
l
1
J l
f. ", K ... )'
, FIGURE 2.3
9 g
8
7
6
".... 5 ~ .s ..... t3 4
~ ~ ln l S
l
.0 .2 .4
. -(
, ......... ~----........... , "'" .- .. " ..... _ .............. -'"
1 "
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Progressiop of the Melt Front During the Filling Stage. in .. a Rectangular MOld, . ~·h. Doan (2) ,
.6 .8
+ E~ERlMENTAL TRANS"DUCER
- --. EXPERIMENTAL PHOTOGRAPHY
_. - TIlEORETlCAL TO
= 240°F
........... THEORETICAL H = 100
1. 2 1. 4 1.6 1. 8 2. 0 2 .2" 2 • 4 2 • 6
'UME (SEC)
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Moreover, the control of process var~ables determines the
thermo-mechanical history experienced by the material, which
ultimately controls the microstructure and final propert~es
of the product (5, 6, 7).
2.2 Product Characteristics
The first importa~t specifications associated with the
injection molded parts relate te the dimensions and the
weight of the art~cle. Since the process involves the
exposure of the material to a broad range of thermal and /
pressure conditions, the ~imensions of the f~nal article w~ll
not qenerally conform to the dimensions of the mold cav~ty.
Usually this is manifested in shrinkaqe, i.e. the dimensions
of the molded article, or its volume, will be smaller than
those of the mold. A variety of molding conditions influence
part shrinkage, as shown in Figures 2.4 and 2.5. Conditions
in the plasticating section have little effect on shrinkage ,
as shown in Figure 2.6.
The final weight of the molded article is profoundly
influenced by the melt pressure in the nozzle or the cavity
as indicated in Fiqures 2.7 and 2.8.
Product quality involves other factors beyond t~ose .
associated with part weight ~d dime~sions. The mechanical
and optical properties must meet desired specifications for
the application under consideration. In qeneral, both mechan-
ical and opti~al properties are closely related to the
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FIGURE 2.4 Effect of ProeeS8 Variable. on Shrinkage (Hlogh Impact p. 5.)
.. ,
III t..:I 0« :0; z .... c:: :r: III
U ... c:: ... III X
:3 0 >
3 9
M02 .003 .004 SHRINKAGE, lon/in
12
8 ~GE
4 - -CALCULATED SHRINKAGE
200 600 800 PRESSURE
FIGURE 2.5 Effect of Injection Pressure on Volumetrie Shrinkaqe (37)
.. 8
6
2
MOLD TEMPERA'l'ÙRE, oF 190
12a = 55.
350 ~ 460 CYLINDER TEMPERATURE, °F-
FIGURE 2.6 Eff.ct of Injection Cylinder Temperature on Volumetrie Shrinkage (37)
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... N
40 ~ ~ 3~ ",' ::l en 30 == <J) t!)
to:I H œ 25 ~ ns c. .. >0 11120 ~ ~Il. H ffi 22. :>0 0<0 u ....
40 80 shot no 280 380
FIGURE 2.7 Relationship Batwean Ca "1 ty PreSsure and Shot Weignts (15)
~ .. .. o :z
36.1 o:r-ïër~-'---'---:.~",-~-~ .hot no '"" 50
FIGURE 2.8 Relationahip Between Shot Weiqht and ~ozzle pre •• ure (151
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mlcrostructure of the part (5, 6, 7, R, 9).
F 19ures 2.9 and 2.10 demonstrate the effects of the
melt temperature, iniection pressure, mold temperature and
veloclty on the tensile strenqth and frozen stresses in
typical injection molded materials.
Numerous studies have been carried out (10, Il, 12) to
evaluate the dependance of microstructure on moldinq conditions.
Kantz (13) observed that the thickness of the oriented skin
is related to the p~ymer melt temperature. The thickness
of the intermediate layers varies with injectlon pressure.
These microstructural factors have a profound effect on
mechanical properties like tensile strenqth and impact
strenqth. Also shrinkaqe increases with increasinq combined
thicknesses of the two layers. Clark (14), in his study of
morphoIoqy and properties of crystalline molded articles
observed that the rate of heat transfer, which is a function
of both the malt temperature and mold temperature, aiso
nffects the thickness of these layers.
2.3 Process Variability
Whisson and Scott (15) studied the reproducibility of
the moldinq process by monitorinq the cavity and nozzle
pressure from cycle to cycle. They used shot-to-shot weiqht
variations to measure reproducibility. variations in the
pressure-time profiles from a cycle ~o thè next were associ-. ,~
ated with fluctuations in the final part weight. These
, .
j
(
/ -15-
3 9 2 4 / .. - 460'"
130
6
~
'" a '" 3 50 158 72
TENSILE 100 pu
FIGURE 2.9 Ettect ot Moldinq Variables on Ten111.
u o
Str.nqth ot Injection Molded Hiqh Impact Po1Yltyrene
30
220
10
INJECTION PRESSURE
50
~~----------~10~0~--------~~30
STRESS FORCE KN/m
FIGURE 2.10 Ett.ct of Holding Conditions on Froz.n Str ••••• in Injection Mo1ded Polypropylene
{
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-16-
var~ations (Figures 2.11 and 2.12) were ascribed to pressure
variations in the hydrau1ic system and the pressure trans
mission through the process.
Jordan et al. (16), using a special instrumen ted
injection mol'd1ng machine found that pressure aberations
ln the hydraulic system (Figures 2.13 and 2.14) marked1y
affected the quality of molded parts. The abnormal behavior
resulted from the hydrau1ic system imposing random injection
pressure variations that were found to be a result of oil
contamination, valve undersizing, valve wear and blockage.
Operatlon under stable hydraulic pressure was shown to reduce
the part size variability by as much as a factor Qf four.
Paulson (17) using hydraulic, gate and cavity pressure
time measurements has il1ustrated the interdependence of the
process variables at various parts during the injection cyèle
(Figure 2.15). By proper control of the machine, he shows
that the effects of hydraulic ~ariations are not refleGted in
similar variations in the cavity pressure, nozzle pressure
and ram displacement profiles. In fact, Paulson (18)
demonstrates that using a closed loop controller, with direct
feedback of the cavity pressure aids in obtaining molded
parts with a high dimensional tolerance of ± .0004 in/in,
while reducing the waste. Moreover, Sneller (19) has shown
that usinq a programmable control system leads to a reduct~on
of rejects and an increase in production.
·-
.. ' . "
--
t..
~ (II
t! '"
a III III
t! 110
l normal
abnorm8'jtles
TI ME
l 1\
•
FIGURE 2.11 Variations of Melt Pressure in the Nozzle (15 )
1. Hydraulic Pressure
2. Cavity Pressure
FIGURE 2.12 Pressure Variation in Three Consecutive Holdings (15)
..
~
1-'
" ,
11
.:... ;:-
(.
1"
•
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\
./
.. '
...
-18-
iii 1
l,~ , l lun Il'.1
nlll. 1
_II. A
Nonwot
_1 Uae_l .. a
Normll
U.âl .. c ,....,..1
A-..I
r -: i
FIGURE 2.14 Bydraulic Ram Pressure After an OVerhaul of the Hydraull.c System
FIGURE 2,1 J Hyc1r-aulic RaID Pre liure ProUl •• tor Thre. Screw Type InJection Moldinq Hac:nin ••
.'
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(
.... III CI.
Q (,)0 ........ >-1-::> ~~ ~~ :ail.
t! ::> t/l-t/l .... rai CD II: CI.
'" Q rai 0 ...l .... ~-~ 0 Z
2 e-II: !ill-e ... zo .... -...l >-U
-19-
23 4
0
20
0
20
10 3 45 2
0
450
400 123 45
350
01 3 7 li 11 Iim. •
P'IGURE 2.15 The Interaction ot Hydrllulic pre •• ure Fluctuations Io/ith Other l'roc ... Variable. {l 7\
Note: Points 1-8 Show th. Tranlllittance ot the Bydraulic: Pr ••• ur. Pluctu&t.ionl Durinq • Cycle to the Othe:r ProclIIII l'ar&llleter.
(
-20-
, 2.4 Thermoplastic Injectlon MOldinq Models
Ideally, process control must be based on a detailed
model describinq the process and the interactlon between the
various opera tinq variables and product character istics. A
number of mathematical J1lodels have been proposed to describe
the thermoplastics injection molding process.
Kamal and Reniq (1) have proposed a complete simulation
to describe the moldinq behavior of thermoplastics in a simple
semi-circular cavity. The model solves the equations of
continuity, motion and enerqy for the system during each of
the stages (fillinq, packinq and coolinq) toqether with the
approprlate boundary conditions. The model correctly predicts
the proqression of the melt front, and the temperature
pressure and velocity distributions as functions of time and
position. Other workers have proposed similar models of ,the
thermoplastic injectlon moldinq process (2, 3, 4, 20, 21).
In qeneral, models of the tY'!=le discussed above are too
complex for application in control strateqies. Processinq ~
of data according to the model requires both excessive time
and memory. Simple relationships involvinq a smaller number
of dependent and independent variables would be desirable.
SOJlle empirical relationships have bee,n proposed for this
purpose.
Peters (22) conducted an investigation of the injection
mOlding proce!l's to determine the relationships between the
process variables neéded to desiqn a closed loop control
{I
I~
1 f
(
"
(
-21-
system. He found th~ fol1owinq relationships based on
experimental data (Figure 2.1").
Pmold = mP HYd + b + ~rr (2. 1)
Tmelt = a(Tbarrel + b) + mP Hyd + err (2. 2)
X t ~ = N- (rnPHyd + b) + err pIast (2. 3 )
where Prnold = peak packinq pres~ure
a, b, m :;:; constants
err ::;:; error
Tmelt = meit temperature
T :::: barrel temoerature barrel
t :::: plastication time pIast
x ;;: shot size
N = screw speed
Menges et al. (23) stat~d the purpose of optimizinq the
control of the injection process as the' productio~ of rnoidings \
of sufficient quality under conditions of minimum moldinq
time, energy and material. The process model shou1d not be
based totally on the physical considerations of the process
but on the utilization of the p-v-t diagram of the processed
plastic material. These values can be transformed into
signaIs for the injection moldinq machine by the process
computer.
; .. i 1
(
(
~~
PRESSURE DATA
MELT TEMPERATURE DATA
.. ~ ::> Ul Ul
-~ 0..
C,!) Z H ~tJ'I CJ -ri .:t: !Jl 0..0.
PLASTICATION TlME DATA
. , -22-
12000
aOOO
4000
r... o
':
BARREL
400
HYDRAULIC
PRESSURE
800 1200
PACKING PRESSURE , psig
400~ __ ~ ____ ~ __ ~~ __ ~ ____ ~ __ __
100 200 300 ,HYDRAULIC BACK PRESSURE, psig
100rpm
150 rpm
100 200 300
HYDRAULIC BACK PRESSURE, psig
FIGURE 2.16 Summary of the Relationships Obtained by Peter (22)
..
}
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-23-
,: Ma (24) similarly describes an approach develqpinq a
desiqn ta control the_moldinq process. He identifies the
functional relationships ·that exist between the inputs and
outputs and proposes a flQwchart of the computer controlled
system. (Figure 2.17 and Table 2.1)'
Baranano ~25), usinq control theofj1 describes a method
for deriving a~ntrol model which describes the injection
mOldinq process. He defines the qiven state of the system
s ~' in terms of the sta te' variable tl l , to 2 etc. which in turn
are functions of tempe rature , T, pressure, P, and the
posi tion co-ordinates: X, y, z and time, t:
T = fl
(p, X, y, z, t)
P = f 2 (T, x, y, _z, t \.
Thus,
S. = f (T., P., ~ ~ ~ Yi' Z i' t i )
The relationships between sta te variables and operating
variables are employed throuqh the appropriate transformations
to obtain the system transfer function. However, Baranano
(25) as well as Menges (23), and Ma (24) does not propose a
specifie process model which could he used for control
purposes. The r~lationships derived by Peter (22) are of "
the appropriate form, but he emphasizes process variables that
are not -of prime importance.
•
,)
.'
l kT
ti-- --j 1',I'u T
"Ul :~I'_l Ak
. 1<' t ---'J~ 1
~ l~AL} ~~lkJLLlf
1- -J IJ Il r hl r MULrtf-L'k
J
..
-~4-
PARAL L.( L TEL[lYPl
OISK HlMUIlY
( XT( RI' Al INHRJ{UVn
1I0'UU~ _
1'~IOI< 1 TJ. IIITERRUI'T iI:ll [ Il f ACE
A TO U COilVlRTl Il !lnTlM
l1 r L RI~ Al
U TU A GONVlRl[ll ~y:,TlM
•••• INTERRUPTS
CORE Mf MO RV
RI A l TI ME flOU ,1'.. 1l M
MANIJAl
~ - -~J Mi/li (JI, --- "II (Jkl)1 k .--- Iii r l fil A II
l~~-Arl il. L !.J" ~I lUR~,
FIGURE 2.:1. 7 FunctiOI'lal Model of the Computer Contro11fid " System of Ma (24)
, '\
r ,
(
-25-
TABLE 2.1
Relationships for a Computer Controlled Svstem
Ma (24)
(Prn 2 + a) (vs - ,b) = cTm 2
where:
N rotational screw speed
PmI - mel t pressure
Tb - barr'el tempera ture
Tmd - mold temperature
Vj - injection speed
0 - melt flow rate
Tml - barrel melt temperature
V - plastica ted volume
Tp plast~cati9n time -<
Vs specifie volume
pm2 - cavity pressure*
Tm 2 - melt temperature*
a, b, c - constants
Ô, ô 2 , ô 3 - random disturbances
* process state variables
"
1
\
ft
(
(
form:
-26-
Ultimately, what ~s needed are simnle models of the
Pcavlty ~ f(hydraulic pressure, time, melt
temperature, res~n properties etc.)
~ nozzle f(hydraulic pressure, time, melt
temperature, resin propert~es etc.)
Ram linear displacement = f(hydraulic pressure,
melt temperature,
resin properties etc.)
Simple emplr~cal or theoretically based equations which
do not ~nvolv~ complex numerical manipulations would be very
helpful for control purnoses. Such models could serve as
the basis for the design and operation Qf a simple control - , -i
system at the start. As more experieq~ ~s gained with the
models and controller, more elaborate modgls and control tL systems may be devised .
• 2.5 Available Control Schemes
Until the acceptance of solid state component technoloqy,
injection moldinq machines equipped with relays operated
usinq open loop control. Variables such as temperàture,
injection pressure, holdinq pr7ssure, injection time and
holding time were manually set and adjusted. None of the
process variables were directly measured and controlled
during the process.
(
o
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Closed loop control implies that the controlled var~ables
are measured and the results of these measurements are used
to man~pulate one or more process variables (26). An
essential element of the. 'closed loop system is the measure-
ment of the process variables. Moreover, to obtain closed
loop control modificat~ons in the deslqn of the hydraullc
systems have involved the addition of servovalves and
var~able 90sltion valves that enhance quick response to
slgnals from the process controller.
The advent of solid state relays and c~osed loop control
systems enab1ed the molder to choose from a variety of control
schemes and strateqies. The inability ta develop suitable
transfer functions describinq the process has hindered the
deve10pment of an optimum control strateqy to control the
process. Table 2.2 surnmarizes the three most common control
strateqies (26).
The most cornmon control schemes employed commercially
are: cavity pressure, injection velocity and adaptive
control strateqies.
l' Cavity pressure control (19, 27-31) i.e. controlling
the peak cavity pressure, enables the molder to reproduce
th~ peak packing pres~ure in the mold. It is c1aimed that
cavity pressure control leads to reproducing bath the micro
and macroscopic part properties (28, 30). Variations in
the peak pressure are corrected for and outputted durinq the
subsequent cycle. The contro1ler ernp10ys an inputted set-
(
(
'-28-
TABLE 2.2
COMMON'CONTROL STRATEGIES
Proportional Control
M (s) KcE (s)
Proportional Integral ~r~l
M(s) = KcE(S) + ~~ J E{s)dt
Proportional Integral Derivative Control
M(s)
where
= KcE(s) + Kc Td dE(s) dt
M(s) - controller output
E(s) - system error (feedback value set point)
Kc - ,controller~
Ti reset time
Td - derivative time
2.4
2.5
2.6
1
" .1:
(
-29-
• \ po~nt correspondinq to the des~red cavity pressure (19, 29,
31,32).
Velocity control (29, 32, 33) enables the molder to
set a.velocity profile as a function of time or ram
displacement. The controller varies the injection speed,
and thus it can be used to minimize cycle time and reduce
enerqy requ1rements durinq the fillinq staqe (29). Variations
in the velocity profile are recorded and corrected in the
subsequent cycle in a similar 'manner as with cavity pressure
control. Since the velocity of the melt at the end of fillinq
is neqligible the molder needs to combine control schemes
to ensure adequate control durinq both the fillinq and packing
staqes.
The other process variables, mel t temperature, Sho,:,size,
back pressure, and cushion size are also controlled using
solid state controllers, relay circuitry and requlatinq valves.
~1tive control techniques are employed in controlling the /~ 1
sh size and cushion (32, 34). 'Dependinq on the peak
pr ssure response during packinq, the shot size and/or cushion
for the next cycle is ad;usted accordinqly. Adaptive control
irrvolves varying the shot size to compensate for variations
that occur durinq the process in order to maintain the final
shot weight constant.
The advantage of microprocessor based control systems
is their capacity to be proqrammed to suit specifie objectives.
These systems coupled with instruments that monitor the system
(
(
-30-
process variations offer an effective approach to control
and sequence the injection molding process. However, the
first generation of microprocessor based commercial ~ystems ~ ,
have not been used to execute complex control alqori thms,\ / \
'-./
but instead to simulate the action of the timers, relays
and other controls that are found with existing machinery.
Microprocessor based controllers offer an opportunity
for upgrading injection rnoldinq control capabilities. The
increased memory capacity and the data processinq capability
of microprocessors permits the simultaneous monitoring of
many variabl~ike temperature~ pressure and velocity during
the cycle. Furthermore, the microprocessor can be used in
coniunction with simple models and alqorithms to control the
various variables accordinq to a desired set-point pattern
continuously durinq a given injection cycle.
(
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CHAPTER 3
PROJECT OBJECTIVES
In view of the above discussion, the present study was
p1anned with the fo11owinq objectives in min~
A. To design, construct and operate a microprocessor based
control system for the thermoplastic injection molding
process.
B. To demonstrate the effectiveness of the control system
for the production of therrnoplastic articles, utilizing
the Danson Meta1mec SR-60 injection moldinq machine.
C. To demonstrate the feasibility of obtaining with the
system injection velocity-time and pressure-time control.
The emphasis in the present work is on the seqment of
the injection moldinq system which deals with the filling 1
stage and melt*behavior between the nozzle and the extreme
end of the cavity. Temperature control and control of the '\
plasticating segment of the process have been left for
another study. Moreover, control of the packinq and cooling
> staqes has not been emphasized in the present work.
It should be emphasized that, since the present work
represents th~ first attempt in our laboratory (and probably
elsewhere) to\achieve the indicated types of control schemes,
the main objectives of this work have been ta design, con-
struct and operate the system and to demonstrate its feasibility.
v "
-32-
c Althouqh substantial effort has been directed towards obtaininq
"qood" control over the desired variables, optim:+'-zation of .'
the soft and hardware and the achievement of a hiqh degree
of agreement between set-point and measured variables have
not been emphasized and will be the subject of other studies
in this laboratory.
( ..
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CP~PTER 4
SYST~ DESCRIPTION
The present injection molding control study was carried
out in conjunction with a Danson Metalmec (Model SR-60,
2 1/3 ounce, 68 ton) reciprocatinq screw ~njection molding
machine. This machine was modified to interface with a micro
processor control system (hereafter referred to as the KPH
controller) to control various process parameters. The
~mportant characteristics Gf the Danson Metalmec injection·
molding machine and the modifications implemented for the
purposes of the present study are detai1ed in the fo11owing
sect~ons.
4.1 Danson Metalmec SR-60 Injection Molding Machine
The Danson Metalmec SR-60 injection molding machine
(Figure 4.1) is equipped for operation in the automatic,
serni-automatic and manual modes. The injection stroke of
the machine is divided into two distinct pressure stages.
The first is an injection pressure, which sets the pressure
for the fil1ing and packing steps. The second staqe, a
holding pressure, is used during the final phase, coo1ing,
to apply a pressure to counteract any backflow that might
occur while the material is solidifyinq in the mold. Each
of the above pressures is controlled by ad;usting the
appropriate manual valves. The screw rotationa~ speed is
-,//
/
~
d
FIGURE 4.1 Danson Meta1mec SR-60 InJection Mold1nq Machine
1-2.
~: 5·
HOPPER SCREW BARREL CLAMP 1 NG UN IT SHOT SIZE SWITCHES INJECTION SPEED VALVE
.,..l
6. INJECT ION PRESSURE VALVE 7. HOLD PRESSURE VALVE 8. TEMPERATURE CONTROL 9· AUTOMATIC TIMERS 10. MANUAL INJECTION $WITCHES
-
~ 1
(
(
\ \
-35-
adjustable by means of a handwheel located on the screw
speed valve, which controls the rate of plastlcation. The
number of screw revolutions per minute i5 indicated on the
screw tachometer. The shot size is controlled by a limit
swit~h. An adjustable cam opera tes this limit switch to
control the deqree of screw retractlon, hence the amount of
material plasticized durinq each cycle. The barrel is
divided into two heatinq zones, which ~re controlled within
±3 Oc with respect to the set temperature usinq two GuIton
Model JPC temperature controllers.
Hydraulic System
The hydraulic system (Figure 4.2) consists of a con-
stant delivery, two-vane pump driven by an electric motor,
WhlCh supplies oil at 10 gpm at 1100 psi. The two vanes of
the pump deliver oil to the hydraulic motor to turn the
screw on one line and supply oil for the injection on the
other line. The sequencinq of the mechanical parts of the
injection molding machine are controlled by solenoids and
transfer valves according to Table 4.1.
The valves and solenoids requlate the oil flow tQrough
the system, which affects the system pressure and controls
the injection pressure. The settinqs for the injection and
holding pressures are made by means of manual valves. The
durations of the injection and holding sequences are set by
the appropria te timers. An example of the hydraulic system
sequencing is shown in Figure 4.3.
-- -j
/
FIGURE 4.2 Hydraulic System Schematic Danson Metalmec SR-60 Injection Moldin~ Mach~ne
.- --- ----. ------.. --- . -. - -- - - --. : 5
rhyd •
,J.'_*_
• l _____ •
hydl
~IM 1
~j '!J.I
CfiTXl 8015
m.nari 21
-, •
- -. .....!.....J
&.---- --- ----- .. ~ 7 fèl. 1 , ,.!..,
4
8012 r:>:I;"'4It11S0I8 ',. --:., 1 l ' f-----~ L -~~Wf~~~·_:~
~._'
18 SOI7~ ;
~.I •
.... _ ....... ~ .-,.. ....
. &.......1
,-.
L.:..J
1 w 0"1 1
....
(
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-37-
F~URE 4.2 Hydraulic System Schematic Danson Metalmec SR-60 Injection Molding Machine
~~ 1. Hydraulic motor
2. Injection cylinder
3. C~age cylinder
4. Injection speed and back pressure regulatin~valve
5. Main pressure re~ief valve
6. Clamp cylinder
7. Injection relief valve
8. Safety valve
9. Main pressure distributor valve
10. Pressure gauge
11. Manual valve
12. Electric motor
13. 2 vane pump
14. Manual valve
15. Sump fil ter
16. Heat exchanger
17. Check valve
18. Screw speed valve
19. Qarriage position valve
l
-38-
TABLE 4 :1
Hydraulic Sy~tem Solenoicl Description
" r
SOLENOID FT:JNCTION
2 closes the rnold
3 advances the carriaqe -~oi~rd -
5 'in,j ection of pol ymer into the
" m61dcavity -
6 , regulates system pressure .-
7 screw drive ~ "
8 opens the rnold ~,
- -. 9 - ,
carriage c retracts the
JI
or
\
( J
-39-
FIGURE 4.3 Sequencin~ of the Hydraulic System Solenoids
Start Cycle-
." No
tJ
.-
Cycle Complete
(
-40-
Electrical System
Relay circuitry is used to control the sequenc~nq of
the var~ous injection moldinq machine activities (Figure 4.4).
The limit switches, cams and timers toqether with the three
main control relays actuate and control the sequencinq of
the various hydraulic valves. The two timers determ~ne the
durations of the inject~on and holdinq cycles, while the
pos~tion of the limit switch cams controls the amount of
polymer plasticated for the next cycle.
• ,
for the system are as follows.
Electr~c Motor ln hp 550 V
Electric Heaters 220 V
Solenoid Valves 115 V
The power requirements ~
An example of the electric system sequencing is shown
in Figure 4.5.
e Control Capability
The Danson Metal~c injection moldinq machine has the
capability of varying the injection and holdinq pressures,
the injection and holding times, the screw 6peed and the
ram velocity. These variables are set by manually adjustinq g
the appropria te valves. The injection moldin~ system has no
provisions to automatically requlate and/or chanqe the settings
of any of the process variables during a specifie injection
cycle or from one cycle to the next.
Figure 4.6 illustrates ten successive cavity pressure
FIGURE 4.4
---
Elect~ical Oiaqram for the Oanson Metalmec SR-60 Inject~on Moldinq Machine
~
,
l55
c:'
-42-
(
(
FIGURE 4.5 Electr1.cal System Sequencinq Flowchart
close the ':lold and inJection carr1age
l'.CThATf. T?E !N.IT.~ICN T!:·œR
lnJect material
ACTrlATES T:!! 'iOé.DINQ '!'!!'ERS
::OLD J<:m r:iJECTIO:: Ci\.~:t!:J<G'E ".E'!'F.A~S P~STICJ<TE :'!\o/ S::ryr
"CTI'lIlTE !ŒLd "3 !'TI-œP ~
no
\ \
\
4;:.~~~·2.l.'''');'') ~ .,.~ ~ .........
;.
FIGURE 4.6 Cavity Pressure Prof11es, Hiah-liqhtinq the Variation in Peak Pressures .
. ( -, , ,~
\ 2717
,
1941
..
..... - 1165
1
388
V t ( / 1 / ........ -
.. III p.,
t! 0 III III
t! p..
~ H
:> 6
i
1 ~
w 1
.... 1
\ -' v'
'l
T
-44-
( profiles run at the same operatinq candi tians. The vari-
ations that exist in the profiles from cycle to cycle can
mainly be attributed to varlations of the pressure in the
--hydraulic system of the molding machine. These variations
are related ta hydraulic system ail temperature variations,
ail contamination, valve and hydraulic cvlinder, leakaqe and - 1
valve blockaqe. 1
Kalyon (7) and Moy (5) both noted, in their experimental
analyses, the variations from shot to shot in the inj ection
molding behavior of each resin. The variations of the
maximum cavity pressure for the two studies and for the data
presented in Figure 4.6 are illustrated in Figure 4.7.
It lS eviden t, tha t the manual control valves determine
the hydraulic pressure of the ail delivererl to the hack of
the injection ram and do not directly control the,actual
injection and holding pressures and the injection speed.
Minimizing the variations in the hydraulic system subsequently
would lead to minimizinq variations in the rest of the process.
The Danson Metalrnec i~jection moldinq machine may he \-iIJI
operated in three modes as stated in Section 4.1. The semi-
automatic and automatic modes refer to continuous operation
of the machine sequencinq and injection cycle during a cycle
and from a cycle ta the next, respectively, under the control
of the relay circuitry (Figure 4.4). The manual, mode of
operation is distinquished by the manual actuation of the
various steps in the rnolding cycle. In subsequent discussion,
(
[
1
~
-
~
--=---
-n
FIGURE 4.7 Error alsto~rarn for the Distrlbutlon of Peak Pressures
"
MOY DATA (5)
KALYON DATA (1)
NORMAL MODE OF OPERATION
--
~ ~ o
s 1
1 1:':/ / . . - 1 Il 1-1 :1
• i;' . , . . 1: . .: \ · ,J l ,L!" ,,-::. -; ,:1 il i \ - 8 -6 -4 -2 0 2 4 6 8 )
FROM TRE MEAN PEAK CAVITY PRESSURE /
A VI 1
(
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-46-
the opera tion of the unmod i f ied Danson Metalmec inj ection
molding machine accordinq to procedures thus far outlined
ln Chapter 4 will be referred to as the "Normal Mode of
Operatlon Il of the inj ection molding machine. Opera tion 0 f
the injection moldinq machine under microprocessor control
W1.11 be referred to as operation under "computer control".
In thls mode the injection molding machine can be programmed .,.;
for automatic, semi-automatic and manual operation, similar
to opera ting the inj ection molding machine in the unmodif ied
or normal mode of operation.
4.2 Microprocessor Control System
There are three basic variables in the moldinq process,
temperature, pressure and melt flowrate.
Tempera ture
The polymer melt temperature affects both the physical
and microstructural properties of the fini shed article. The
melt temperature is controlled by heaters which are placed
on the barrel of the injection molding machine (Figure 4. l) .
The barrel temperature is controlled by a closed loop scheme
to maintain th~ barrel temperature constant throuqhout the
cycle. In this study the melt temperature will be controlled
using the existing barrel temperature controller. The control
system, however, is flexible enough te monitor and record mel t
temper a tut;&, da ta.
The mold temperature, which was shawn ta influence the
(
(
-47-
shr~nkaqe, surface finish and orientation is another process ,
variabl e. The microproces sor system was not employed to
control the mold temoerature in this .study. The molq.
temperature was determined by the water temperature <pf the
utility water system (:::50 OF).
Flowra te (MM Veloci ty)
Ram velocity is obtal.ned by measuril\g the linear dis-
placement of the injection ram and differentiating the
resul ting curve wi th respect to time. The in j ection rate
~s contro1led by the flowrate of oil to the back of the
injection ram. The stroke of the ram is requlated by ad-
justing the flow of oil and the velocity is monitored by a
ll.near displacement transducer (LDT). A variable position
val ve or servoval ve can be installed in the hydIraull.c
1ine feedinq to the ram, resultinq in requlatl.ng the oil
flow to the ram, in order to vary the ve1ocity.
Pressure
The three pressure stages of the molding cycle (Figures
1. land 4.8) are controlled through the supply of oil that
" is fed to the ba::- k of the injection ram. Controlling the
pressure variati n during each stage may be aehieved by the
use of a servova ve to control the oil flow, similar to
velocity control Consequently injection pressure and
injection ve10ei y are interdependent. The pressure measure-
ments are made u~inq pressure transducers loeated in the
nozzle, eavity and hydraulie system. The other process
)
(
-..
(
-48-;
r----- 1 HYDRAULIC 1 PRESSURE
r CAVITY
, PRESSURE
1 , RAM
POSITION
~------~~~--~--~--~------~~---
1 PACKING
TIME
FIGURE 4. B Pressure vs Tirne Profile During an Injection Cycle
, ,
, 1 • 1
, ,
1
l
-49-
( var~ables of importance are screw speed and shot size.
Screw speed is controlled by a manually adjusted valve
that regulates the oil flow from the pump to the hydraulic
motor. In this study no chanqes were made to the screw speed
control system.
In order to regulate the shot size, 'the sc~ displace-
ment and back pressure have to be controlled. The LDT
measures the screw displacement and can be used as a sensor
to control the shot size. The back pressure is monitored by
the hydraulic pressure transducer and is controlled by the
servovalve. The variables controlled or monitored by the
microprocessor control system are shown in Table 4.2.
Microprocessor Software Constraints
Two important constraints in controllinq a process with
a microprocessor-based controiler are the proqram time and
the measurement time. Under typical injection molding
conditions of r~levance to the present study, the overall
injection cycle has a duration of approxirnately 30 seconds
with the combined fi1linq and packing times beinq in the
range of )-9 seconds. During the packinq stage (Figure 4.8),
the pressure increases rapidly over a period of 0.5-1 seconds. -,
To control the process, it is necessary for the control
system to obtain measurernents and execute the control proqram
between 30-50 times/second to ensure adequate control. Hence,
the maximum response time of the sensirlg manipulated element,
i.e. the servovalve hac ta be ~ 20 ms. Moreover, the time
(
, , l , ., t li ,j
~ -~
'.
TABLE 4.2
CONTROL VARIABLES
o
"
VARIABLE
temperature
velocity
pressure
shotsize
where
MEASUREMENT
barrel ternperature mold temperature
ram velocity
cavity pressure
back pressure/ hydraulic pressure rarn position
..
mv - millivolt signal 0-20 rnv
v volt siqnal 0-10 volts
trans. - transducer
1 IIW1ftd ne ...- ... ~-""""" - - ~~ ~ ~-~~~ ~
SENSOR
thermocouple thermocouple
LDT
pressure trans.
pressure trans.
LOT
"'
SIGNAL TYPE
rnv rnv
volts
mv
'1
v
._-'-""........." ... ~ .. "',-~ ~--.-~
CONTROL HARDWARE
servo valve
servo valve
servo valve
-
1 VI o 1
-']
(
(
(
-51-
required '>.by the system to execute, monitor, convert, record,
calculate and output the data should be < 20 ms. Depending
on the complexity of the control strategy, the execution time
of the main control program will vary depending on the
computer language employed. Generally, the proqramming r
language used in real time control is "Assembly language'" .
The execution time of an Assembly language program is less
than tha t of other, higher l--evél programming languages s1,ilch
as B,A!'ic, PLM and Fortran. A disadvantage of using Assembler
is that due to its structure, when proqramming complictted
mathematical equations, it becomes difficult to follo\l( the '" , ' \1, sequencing of thé various steps. For this study all the
"', programs )'Iere written in Assembly languag-e and were assembled ~
op the McGill MUSIC System Z-80 version compilet. The McGill
Universi ty, MUSIC System supports the operation of other
higher level language complilers such as the PLM vers~n 4
compiler. Investigation of interfacing the microprocessor
system to the McGill MUSIC System was unde,r:taken in order to
• use higher level programminq languages in the future. The \ --,
results of this ~tudy are presented in Appendix 3.3. '. ,
4 . 3 KPH Control System
The Danson Metalmec SR-60 injection molding machine was
modified for operation in conjunction with a microprocessor-
based servovalve control system.
referred ta as the KPH s~stem.
The control system- will be 'P
"
~.
-52-
Hydraulic System
In arder to control the preS'sure and velocity a servo-
val ve was incorporated in the hydraulic system. A Mooq , '
model A076-103 servovalve (ApPe'ndix 1) rate for 10 gpm and
a maximum pressure of 3000 psi was selected for use i~ the .....
KPH control system. The response time to achieve full flow
was 10 ms. Placement of the valve in the hydraulic system
was after valve 4 (see Figure 4.2) .
Certain system specifications had to be met in order to
assure successful operation. They were as follows:
- system filtration required: 10}lm nominal
- system line pressure should be stable
- pilot pressure should be constant
- oil temperature should be between 60 and 200 oF
The filtration system (Fiqure 4.9) ensures complete
sys-tem filtration « 10 ).lm). A high pressure .5).1m fil'ter
is located before the servovalve, while a 30 j"un low pressure
fil ter has beeri plac~d before the ~oil reservoir which con-
tains a sump fil ter as the preliminary filte~riq medium.
To assure operation at a constant pressure, an unloadinq
val ve was placed before the servoval ve . A 20 hp electric •
motor was installed to su.pply oil at 2000 psi at 8 9'pm to
overcome the larqe pressu.re drop of the servovalve.
Addi tional features of the KPH hydraulic system included
a series of bypass valves and relief valves. A constraint-
in desiqning the KPH system was ta retain the old hydraulic
.... 1 ,1
,.
, .
[)
----
FIGURE 4.9 KPH Hydraulic System Schematic
~
r<4
t....:.....J .-~ [Y'pu I1lhyd ", . .a::R ,6 , '. -_. -.. -., ". -' -.1'
\ aoUi 51111aol8
.. f~21~1 _.- , • ~
" ~hyd"., Il''-
8 ••.•••... """-·-1 i ~~I~~SOIQ . ~
-----.J
9 10
man -r
. -- --... M
~1"
... _~~ r~-' •• _~
.-...
'- ~
,
1 U'l w 1
-54-
( 1
FIGURE 4.9 KPH Hydraulic System Schematic
1. Injection cylinder
2. Carriage cylinder
3. Hydraulic motor "
4. Servovalve
5. Clamp cylinder
6. Mold position valve
7. Check valve ,~ • J
8. Carriage position valve
9. Main relief valve
10. Screw speed valve
Il. Heat exchahger
12. Low pressure filter
13. High pressure filter
14. Reservoir
15. Sump fil ter
16. 2 va~è pump
17. Electric motor
l •
"
(
(
-55-
system confiquration and wirinq in arder ta assure operation
in the "Normal Mode" as weIl as usinq "Computer Control".
An example of the KPH hydraulic system sequencinq is shawn
in Figure 4.10.
Microprocessor System
The development of the KPH control system described
herein is based on the use of a Cromenco Sinqle Card Computer
(SCC). The complete system has available l3k random access
memory (RAM), l2k read only memory (ROM), 7 parallel input
and output ports, 4 RS232 seriaI ports and monitor
and control basic proqr:4L~s~' Peripherals used are: a model
1400 Hazeltine CRT t~rminal, UP ta 22 input and output
modules, a Burr Brown model SDN 856 analoa ta diqital con-~~
verter and an 8 bit diqital ta analog converter (Figure 4.11).
Electrical System
Figure 4.12 is a diaqram of the revised electrical
sequencing system of the Danson Metalmec mOldinq machine .
• The OPTO 22 rio modules, electrical relays, and limi t swi tches
3, 4 and 7 make it possible ta control the sequencinq and
positioning of the various valves and hydraulic parts.
Machine Sequencinq
The KPH control system was designed and programmed for
operation in the semi-automatic mode. rnitialization of the
process is done by activating the start relay button. The
KPH control system monitors limit switches 3 and 4 using the
OPTO 22 lACS rio modules to indicate the position of the \ ,
1: .'
( i
"
/.
.... 56-
FIGURE 4.10
Start Cycle l ,
press Start Button
tfl Electrical and Hydraulic Seouencing of the KPH System
Initiate. Machine Cycle and Computer PGM
Solenoid. 2.3. Enarglzed
Moni to r !.S], LS4 No
y, ..
Activate Maln Control Reley: Di.conn.ct. Relay Timera trom the Exiating Blectrical Wiring. SWltche. Control to the Computer
Act1vate SOL 5.2, Inject10n Ua1ng OPTO 22 1/0 Module.
Injection Pha •• Controlled by Microproce.aor and Servo Valve
Holding Pha •• De-!nerq1ze SOL 5.2, Micro Time. the Holdinq Sequence
7.5.2, for Pla.tication ot Material
9.8, open the Hold/Carriaqe
Monitor LB7
No
Sviteh oH MOt. a.turn~to Macbine Circuitry
1
EndJCycle
Micro - ~~croproc ••• or MeR - Main Control Relay
1
,.-....
8-)(
MEMORY
BOARD
.-....
8-100 BUS
, CROMENCO
sec
r- '1SERIAL PORT PORT
FIGURE 4.11 KPH Computer System
,.
__ ....... ___ - _ .......... .>0.0. '",-____ - •
LOr
18H
liliiii- ~ P ARALLEL
03H '3H
PORTS
C ~ SWITCHBOARD r/o BOARD .... ----1-.
ARALLEL
°NH 8
SERIAL PORT
PARALL~r PORT
H
LS3 l84
ls7
ACC.OUSTIC
aJUFUR
McGllJ.
MUSIC
SYSTEM
t""J'.
'"
1 U1 -...J 1
'"
~':~"" ~~ ~
/"
"
,,-,
ls3 ~-
01
02 ~OR1l 1 CR1
5
0ClS
03
~--------------------------------------~f~t~----4
01-04 OPTO 22 1;0 MODULES; NORMALLY OPEN UNTIL COMPUTER 1S ACTIVATED
INJECTION PHASE .;
1----11 1 d'Ir- 1 PLASTICATION
?
~
.. ... ,... -~_..--.........--- ... _.---
• JUMP BACK Ta MACHINE CIRCUITRY SEQUENCING TO OPEN THE MOLD
FIGURE 4.12 Simp1ified Logic Diagram of the KPH E1ectrical System
. .)
\
-
~.
1 U'l CO 1
,' ..... I~~ ...... _';_ ....
(
,.
(
-59-
FIGURE 4.12 Simplified Logic Diagram of the KPH Electrical System
Key
CR Control r,alay
MCR Maln control relay
VR Valve relay
SOL Solenoid
LS Limit switch~
1 t De-energize
Il, 0 Energize, energized
-
'. _1
\J
(
c
-,60-
mold plates and carriaqe. With the mold and carriage
closed, the control system transfers control from the
machine circuitry to the microprocessor. Upon completion
of the injection cycle, the mode of operation switches back
to the relay circuitry of the Danson Metalmec machine at
which time the mold and carriaqe retract to end the cycle.'
Regardless of the control strategy, the sequencing of the
machine parts prior to injection of the polyrner melt into
the cavity and subsequent to coolinq is unchanaed. The
sequencing program "SEOUE" was written in Assembly language
and stored in EPROM on the SCC. The SEOUE proqram includes
a collection of subroutines, each controllinq an individual
action. Fi~ure 4.13 is a flowchart of the SE0UE routine.
A complete listing of the proqram is ~iven in Appendix 3.
Software
The system was proqrammed with the subroutines for the
sequencing and control schemes on EPROM. The RAM was used
to store the main control proqram and the real time data
recorded durinq a cycle. Figure 4.14 i5 a memory map of
the system. This arrangement allowéd for simple modifications
of the main control program to run the injection machine
using the various modes available. The microprocessor system
could also be proqrammed for data acquistion of the process
variables during a cycle. Appendix 3 contains a listing of
the programs stored on EFROM.
-61-
FIGURE 4.13 SEQUE Proqram Flowchart
..'\.:: C",:;~ -=- , ... : -,:: ~JoI.",,;-
c
(
1
(
r
( 1
(
-62-
FIGURE 4.14 Memory Map KPH Syétem
ADDRESS
0000-0422
0423-0FFF
1000-lOFF
1100-17FF
1800-IFFF
2000-20FF
2100-21FF
2200-22FF
2300-23FF
2400-4FFF
SOOO-S74F
5750-584F
S8S0-SAFF
SBOQ-SeOO
seOl-SDSO
SOSl-SFFF
6000-FFFF
c
FUNeTION
see Monitor Program
sec Control Basic Program
Interrupt Vector Addresses
MUSIC Translato~ Program
SEQUE and Remaining Subroutines
Real Time Value Memory File
MEMORY TYPE
ROM
ROM
ROM
ROM
ROM
RAM
Control Basic Stack /~ RAM
Error Memory File
Set Po~nt Profile Memory File RAM
Not Used
Control Subroutines and Programs RAM
Error Sign Memory File
Control Subroutine and Programs
Mi Memory File~ - _/ ~
RAM
MM
MM
Control Subroutines and Programs RAM
Stack for see Monitor .RAM
Not Used
-63-
(
CONTROL STRATEGY
As a starting point, a simple proportional controller
(Equatiôn 2.4) was used in this study to control the injection
mold1ng process dur1nq the filling and packina staqes.
5.1 Control Background
Figure 5.1 shows a simple closed loop control system.
It consists of a process and a control 1er that manipulates
one of the inputs to the process in response t0 a signal
fedback from the process outputs. The simplest possible
control strategy, proportional control, fnvolves chanqinq
the manipulated input to the process proportionally to the ~
error siqnal which is the difference between the set point
value and the measured variable. A proportional controller
can be represented by the following equation:
m = G * E: + b (5.1)
where
G = qain 1
E: = error
b = constant
m = controller output
The control 1er qain can be expressed as the fractional
',1 ~'
l
SET
"...., (
,
FIGURE 5.1 Simple Clpsed Loop Block Diagrarn
CONTROLLER
•
CONTROLLER
OUTPUT
.1.
FEEDBACK MEASUREMENT
PROCESS
~.r
-
PROCESS
OUTPUT
FEEDBACK
MEASUREMENT
1 0'1 01> 1
;)
,,-
~,
(
-65-
chan<je ~n input, while the constant "b" as the controller
output at zero error. \
In order to achieve reproducible parts, one is inter-
ested in molding the article at the sarne processinq, conditions ,
from cycle to cycle. Reproducing the pressure time and/or
velqcity time profiles is consi~ered as an important
.' criterion in reproducinq conditions from cycle to cycle.
Figure 5.2 is the block diagram illustratinq the KPH
controller. The control proqram has been designed sudh that
reqardless of the set point profile, it is possible to obtain
closed loop control, as long as> the appropriate feedback
sensor i5 connected to channel one of the analog digital .t""'-
converter. Figure 5.3 show~ the various control schemes
that'are possible usinq the KPH system.
5.2 Digital Form of the Proportional Controller
The proportional controller Equation 5.1 is useful for
a continuous measurement Process. Accounting for discrete
measurements and for abrupt fini te chanqes that can enter
into the analysis, Equation S"f has to be rewritten in the
form of Equation 5.2. Rewritinq Equation 5.1 in discrete
forro at a time = i is: •
(5.2)
where m. and E. are the controller output and system error l. ,l. '
at a time i respectively (E. = set po1nt va~ue, time i -1.
i
f t ; f
\ -. - ~ ... -- .-1
SET ~OINT PROFILE
Ht:X capE
• 1
Il ~
"
~jrnièf,.î!:ff .. UIF7x[tris't' ~
FIGURE 5.2 KPH Control 1er Block Diagram
•• ______________ ~HYDRAULIC (J
PRESSURE PROCESS Mi+l CONTROLLER .
SERVOVALVE
,. (HEX CODE) (MILLIVOLT)
• .FEEDBACK MEASUREMENT
- PRESSURE TRANSDUCER
- LINEAR DISPLACEMENT TRANSDUCER ~--"" . ...J
--- ---- _ \_" - .. -'"'-"'-_.""'-..... ....:,k;: ~ ... .JoIojo.t._\.-...._.... ''S''
"
OUTPUT
1 en en 1
- CAVITY' ~
PRESSURE
- NOZZLE PRESSURE
- RAM 015-PLACEMENT
~-~ ...... ~"" .... ~" t<tJir"'r;!
(
(
b
-67-
FIGURE 5.3 Control Possibilities KPH System
CAVITY PRESSURE
SET POINT PROPILE
NOZZLE P RES SORE
SET POINT PROFILE
SET POINT PROFILE
SERVO PROCESS
-----..,0 .SERVO PROCESS
SERVO PROCESS
LOT
REAL TIME
NOZZLE PRESSURE PROFILE
REAL 'rIME !!AM
LINEAR o ISPLACEMENT PR9PILE
.'
,
\
(
t
c'
( /
-68-
real time value, time i).
Rewritinq for a time i-1
= E. l • G + b ~-
Subtracting mi - mi _l
Ei * G + b - Ei _1 * G - b
where (
(5. 3)
(5.4)
(5.4a) ,.
Equation 4a can be used to calculate values for the valve
opening for the time increment i(m.l based on data obtained 1
at times i-l and i.
5.3 Closed Loop Control Realization
The proportional controller equa~ion tlsed in this
study was
rc;_(S&d:, pointi - set point i _1 ) -' CreaI timei - real time. -1)1 l' value value h '1
(5. Sa)
which can be rewritten as
(5. Sb)
The minimum tirne increment between the data samplings,
,
l
l 1
\ \, \ \ \
-69-
as mentioned in Chapter 4 is 20 ms. Thè control proqram
utilizes timers 2 and 3 on the Cromenco SCC to set the delay
between the data readinqs. The maximum time delay achievable
usinq the closed loop control prograrn i9 32.64 ms. Figure 5.4
outlines the sequencinq ot the closed loop control prograrn.
Starting at time equal to zero, the maçhine èycle~and control
program are activated. Th& control proqram monitors the \ 1 \Position of t'he mold and carri~e, until they are in the
~losed positions. The control.~rarn, through de-energizinq
t~e main control relay (MeR), jumps to the control subroutine
to control the injection phase of the process. Timers 2 and
3 then are activated in series. Precedinq the tirne out of
timer 3, the feedback measurement is made and stored in the
memory. Subsequently, the output of the control equation
(4a) is calculated and forwarded to the servovalve. Timers
2 and 3 are re-enabled and the cycle repeats until the timer
counter equals the control program counter at which point pt
the proqram jumps to the holdinq routine. Timer 5 on the
SCC, 'measures the duration' of the holdinq phase. After
timer 5 i8 out, the control program executes the -plasticating
subroutine, where the system's back pressure is contralled
Via the valve openinq on the servovalve. After plastication
starts, the system switches back to the "Normal Mode" of ,
operation by energizing the main control relay. This action
causes the machine ta continue the injection cycle using the
relay circuitry by open~nq the mold and retracting the
( ,
FIGURE 5.4
î ,j
J -70- \
~_nl~-"~ •
s,,_ :. 2 _
-:3::T .......
uo
;:0
•
Closed LOOp Coptrol Program Flowchart
<
1
\ l-I , \ .
-71-
( injection carriage. The recorded data can then be printed
and the cycle re-initiated. Appendix 3 contains the open
loop proqram used to obtain the open 100p data in this study.
Appendix 3 contains the c10sed loop control proqram as weIl
as documentation concerning the timers and interrupts ,; available on the sec.
'-"""'"
'1
J
J
i'
l
(
, .
1
-72-
CHAPTER 6
MOLDING EXPERIMENTS
The molding experiments were carried out with the
purpose of studyinq the dynamic characteristics of the
lnjection moldinq orocess and to test.the microprocessor
based control ° system.
6 .. 1 Eguipment
Three Dynisco pressure transducers were employed
(Appendix 2). Model TPT 432A, seriaI no. 104235, pressure
transducer was located in the hydraulic system before the
injection ram. A similar transducer, s~rial no. 116978, was
mounted in the injection nozzle, and the third transducer,
seriaI no. was located in the mold ad;acent to the
gate. Details of the pressure transducer system and its
calibration are presented in Appendix 2. \
A linear displacement transducer, Model 4709, manufactured
by Markite, was installed on the injection moldinq machine
to monitor the ram displacement. Details are qiven in
Appendix 2. A Hewlett Packard two channel recorder model
7l00B was used in conjunction with the microprocessor con-
troller to,record either pressure or injection"speed.
(
-73-
6.2 Control Schema Evaluation
The followinq tests were performed to evaluate the
effectiveness of the KPH system:
A. The open loop response and open loop variability of the
system were recorded and analyzed us inq the open loop
proqram (Section 5.3)
B. The closed loop response and -variability were recorded
and analyzed usinq the closed loop proqram (Section 5.3)
for various types of set point profiles and ~in values.
The set point profiles represent the reference pressure
time or velocity-time profiles on which the controller action
is based. Ultimately the set point profiles represent the
desirable pressure-velocity-time profiles for a qood quality
part.
Two types of set point profiles were used to test the
flexibility of the closed loop programs. Firstly, the closed
loop program was run usinq open loop generated profiles as
the set points. The objective was to de termine if the system
variability tan be reduced by usinq closed loop control instead
of running th~ system in the "Normal Mode" (open loop). The
second type of set point profiles were obtained by combining
parts of open loop profiles which were obtained using different
valve openings. These types of set point profiles could not
be achieved using open loop techniques under the "Normal Mode"
of operation because of the necessi ty to vary the valve
.. ~- -.
-74-
..,. opening ta comoensate for the jump from one profile to the
next.
Figure 6.1 is an example of the technique used. Open'
loop profile A for this study, refers to a 13% constant
valve openinq, while open loop profile B refers to a 62%
constant valve openinq response. Fiqures 6.2 and 6.3 are
the set point profiles used for the cavity and nozzle pressure
schemes, respectively. For the linear disPlacemett and hy-
draulic schemes, a step change set point profile (Figures ,
6.4 and 6.5 respectively) was used to test the flexibility
of the system. In aIl cases, the step change set point
profiles are unachievable using the "Normal Mode" of operation
of the Danson Metal~ec SR-60 injection mOldinq ~chine.
In arder to evaluate the response to a specif,ic set ."
point under a set of conditions, the sum of the squares of
the errors was calculated at each tLme increment. The sum
of the errors squared indicated the quality of the response
of the system and gave measure of the ~ffectiveness of the
controller. The best system behavior was determined by the
smallest error sum for a specifie set point profile.
6.3 Ex erimental Procedur
After turning the po er ort and settinq the desired
barrel temperatura, __ ,the injection rnoldinq machine was allowed
to wapn up for at least 45 \rninutes. Cold water was circulated
in the mold. The pressure and displacement 1:>ransducers,
1
~
)
-l
FIGURE 6.1 The Technique for Estimating the Cavity Pressure Set Point Profile
f li! ~ a co.
t
'1' 1 S'l'AR'l' JUMP
OPEN LOOP 62' VALVE OPENING CAVITY PRESSURE P.ROFILE
11 1'2
'1'2 TRANSITION 15 COMPLÉ'l'E
OPENING
'1'IME •
o SET POINT PROFILE
- ,
--.J U1 1
-'A
---~--~- - -----.... ----~-------- - ............. , ... ~r...,.,...;..
r
-,
)t
/- 1Il00
(
"Pi • • CI. ..........----.-t! ~ 1200-0. lA
t! '"
800
400
"w "iIA'Iit'hlawC'f!S" t·ffl,.t\l.' ............... "'~...-..-.... ·_--
•
-FIGURE 6.2 Cavity Pressure vs Time Set Point Profile
62' PROFILE
1.0
TlME, sec
1.5
-- .~, ...... .....,._ ..... ~""" ... """J> ....... - -
o SET POINT PROFILE B
13'1 PROFILE
~
---
1 -..J 0"1 1
.............. ~'L>o"'ot' ... "'"""'~
--
(' ,-
.r
vi •
5000
4000
Cl. ~
1 CO
tl' ,.. 2000
1000 -.
FIGURE 6.3 Nozzle Pressure vs Time Set Point Profile
#
.75 2 3
TIME, sec
~
4
~E-r POINT el. o SET POINT
B
PROFILE-
-~_ .. ,- .... ----..,.-~ .. ,~->.--_ ........... ~-------___ ....... _~ __ ,""" .. ~_~.,..._--OO'''-''_~'
-.
r
..
1 -..1
1'
.,~-..",...~
. 1
"""
:JY
,~ 1
2.5
~ 3.3 -~
1 u Pt co H
i'~ .~ 5.7
FIGURE 6.4 Linear Displacement vs Time Set Point Profile
Do\
/ÔAô Ô4
• 2 3 TlME, sec
~
/ t
e. STEP CHANGE _ PROFILE
~2' PROFILE
1
1
\ 1
1
\
____ 13\ PROFILE
4
•
-..
.!
~
1 -.J 00 1
.-
} < 1
t
t· !
_ ...... 11~.,. "'t~'l'l-II'-'"'''''''~
ç
--.... • Il. . 1 !
4,
FIGURE 6.5 _Hydraulic Pressùre vs Time Set Point Profi~e
TINE
"
PEAK 62' PROFILE
2
S'l'EP CHANGE PROFILE
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excitation power süpplies and the recorders were turned ~ , '>. The inj~ction pressure, holdinq pressure, shot si~ and the
c
injection and hal,ding times were t'hen set at the desired
values. . ..,.
The moMr wa.s turned on and mater~al was contin-o
uously purged inta the open air ~or"thê first few i!ljections.
Then, usinq the by-pa,ss valves and switches, the necessary
ad;ustments were made in t;he hydraulic and electrical systems
ta switch over to the servo control system.
wi th the help of the open laop injection computer proe
gram operated in conjunction wi th a specifiedlcombination of j ./ , - ,.. ..
settings for valve openin9, injection time and holding time,
the polymer melt was in;ected intô 1;,he mQld cavity and. c0!l
tinuous record.:i,ngs were made of the hydraulic, 'cavi ty and 1
. nozzle pressures and linear displacement. Fivê samples at
each qonditiGI\ were molded for analysis of the system r#!spanse
to the s~t point. The moldinq cycle was repeated usinq a
different set of conditions. 0'
"
After the open ~oop experiments, the closed lqop control
program was loaded into the control memory. With the d~sired"
set point profile loaded into memory, the program was exe~uted.
The gain and "Mo".' (the valve opening for the first time
incrernent) of the c~nt.t~~,}ler (Equation 4b) were varied to mold ) ... / " ,
\ . ",-
at least 3 parts at eacn set condition. '.Chrs experimental' . /
procedure was repeated for variou"fo-sét point profiles.
Figure 6.6 illustratis the sequencing of act'ivi,ties durj.ng
the clos~d lO~st runs • Tab1es 6.1 and 6.2 summarize the - ,- (
operatin5l.~6ndi tions that were emp,loyed in this. molding study •.
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FIGURE 6.6 Flowchart of the Closed Loop Çontro1 ,Experimental Procedure
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TABLE 6.1: '0
0een Loop Operating Conditions for Experimental Mol'dinq IStudies
F"IXED PARAMETERS
" Mold Temperature
Barrel Temperature
, ",
Holdinq Pressure
Screw Speed "
Samplinq Time
Holding Time : . \ ,
Injection Pr.oqram 'i
Counter 200 Samplinq Increments
VARIED PARruMETERS
Val ve Openings 13% +-+ 100%.
o RESIN
• ' ... High Dens~ty Polyethylene
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- • - • - - _____ .(_ .L_ • __
.83-
TABLE 6.2
Closed LooE Operatinq Conditions ~ for Experimental Molding Studies
FIXED PARAMETERS
... Mold Temperatdre 50 oF
Barrel Temperature Zone 1 400
Zone 2 350
HOlding Pressure 500 psi
Screw Speed . 70 rpm
Sampling Tirne :..
32.64 ms
Holding Time 20 seconds
Sampling Interval . 16.32 ms
VÀRIED PARAMETERS
Gain 05 - 160
Mo (Initial Valve 13% ~~ 62%
Openinq)
Set Point Profiles
High Density . .,.
, Polyethylene
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CHAPTER 7
'RESULTS AND DISCUSSION
This chapter presents the result~ of the various • 1 (
experin'leI).tal 'runs,- made ïn the pr~sent stud~. r"urt.herrtlore,
the ~esults of the control study are compared, to previous , .
" resülts to obtain qualitative information regarding th~ ,
process.
7.1 Cavity Pr~ssure Control
Fi<;J'ure 7. l shows the typical\cavi ty pressur~-time pro:-, . . files 'near the mold gate for various valve Qpenings. The
" . v
cavi ty pressure data we~e obtained using the open 'loop control , I!
proqram. The delays in the pressure response for the valve
'openings (13%, 3l%r, 44%) represE}nt 1:'he addit{onal times
nece~sary for the polyrnerl melt ,"to flo~ through the sprue , t
from the nozzle to thé gate. Figure 7.5 i11us~rates the
differencès in ram velocity as a functionjof the valve ,open
, ings., wi th, the 13% settingc being t.h~ slowest.
The servova1ve setting to achieve maximum system
pI;es~ure as seen from Fi:ure 7.,,1 is ::(2%. For val've
openings qreater than 65% there is no nbticible difference
~n,t~e pressure profile~ obtained. This can be attribu~ed
to lim~tations.of the hydraulic system and the servovalve , . characteristias. The servovalve is designed for flowrates
up to 10 gpm wh!le the maximum system flowrate i5 o~ly 8 gpm.
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'!'wo otp.er characteristics are evident from Figure 7·.1. One ~ 1
is that the slope of the pr,essure-time~ response i5, e9s,entially , '
inde pendent of the valve opening in the i'acking stB!;1e. This , ; ~ ~ fit Q .,
i5 not unexpeêted sinc:é ràm flisplacement, and hence .hydraulic ê . ' fluid flow ;throug):1 the serv0valve is smàll •. The' rate of rise
Il
of Pfessure in the., packing phase, about 5"7'00 psi/sec, is
\' contro~led, by the system elastiéity and polymer compress-. , .. '" ,
abili ty. t A more unexpected respon::;e is the independence
from va~ve opening d,uring the filling stage of the rate of
rise of pressure (~bout 290 psi/sec). This occurs despi te
the difference in flowrates a's evidenced .D'y the different
• times to fill· the mold. 'l'he ,delay in pressure developmefit CIl
in the mold i8 due to varying times required to fill the ~
~ runners as mentioneQ. previo8sly. Il
The cavity pressure variations for 62% valve opening ar-e •
presènted in Figure 7.2. Cornparirig tt:le open loop variations
of the \fH control system, ,(Fig~re 7.2) to "those of ,~he original Danson Metalmeç system ~ (Figure 4. 7), i t cari 'be seen
. that the peak I?ressure variations of the original system are . . slightly lower th.an those of the KPH system. The maximum
• open loop variak.ion for a 62% valve opening is 8.5% (when
basing the cornparison on calculating the percentage error a~\
% err = (Peak pressure ... average peak preSsuL"e) average peak pressure
while those cited by Moy (5) and Kalyon (7)' range between
7 and St' for the unmodified Metalmec system. The possible
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FlCURE 7.2
~ 25 o ~ ra.
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Peak Cavity Pressu~e Èrror Histoqram •
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62\ ~ALVE OPENING OPEN LOOP DATA
62\ VALVE OPENING SE'l' POINT PROFfLE'/.- -g ~ 16 DATA,
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reasons for'these differenëes are as follows:
'-' The pressure transducer used by J(alyon (1) and Moy ( ~
, ~
(5) 'had a qmge of 0 - 10'; 000 psi. The cavi ty trans-.
ducer employed in the present' study had a range of , ,
o - 15,,000 psi. The decrease in the sensitivity of Il
the, pressure transducer can lead to a la~ger error in -- \ . ' the output signal.
, , ...
The addi ti'on of the servovaJ,ve, the 20' hp motor and .\
the various by-pass valves, unloading valves, piping , ,
~ • ;: • 1.to
. and relief, valves to th~ original\ system has increas~d' .... ;:- l ,
th.e source of possible system pressure variations.~
• 0
ThE6 closed l<3op responses, us~ng an open loop pressure ,[,.;'1-~(\
profile as the ,set point is Plti~ented irv Figure 7.3.
Depending onv.the value of the gain, closed loop control • ~"'- ,~ ,J ~~ ... :: \,
reduc~s' the pressure va'tiations in compari~on C'to open loop
operation. The maximF pe:r;;centC'error using, the ,closed' }.oop
,program for 62 % ~alve opening is 5% in compa~ison to 8.5%
for the open loop cases (Fiqure 7.2). This value i5 aiso
....
lower than the errors encountered by Kalyon and Moy (Figure 4.7). 1
It has been found t.rat ~ower gains using open loop data ,.s the set point pro~ilè yield the smallest error. The result
can best be explained by observing the vkve o;ening as a_
function of ti~e (Figure 7.3). The servovalve openings at
lower gains tend to fluctua te' at-ound the open loop or constan~
V~lV~ position used to generate the set point profile. On'
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1200
. , rilOP 100
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e, FIGURE '7.3 Cavity Pressure vs) Time-Response . - Closed
'Loop Run 'Using a 62% Op~n Loop Set Point Profile
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,75 TI,ME
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eG = 96 ÂG = 05
,.- SET POINT PROFILE , ,
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Note: The' minimum sampling time ois 1/30th of a second. \ re data presented is every 8th data poJnt. Inbetweed these point~, the pressure and valve positiop fl.uc tuate as a consequence of the process and contraller action, resp~ctively. This is the reason for G = 96 thÇl.t the presence ~s shown constantly abo~~ the set poin~. Inbetween the data points the prés.;;ure fluctuates above and below ;the set l?oint valve. ,
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.. " the other hand, as expected a t higher <:!a:ins" t}:le valve
positions tend to fluctuate,more than at lower gains. ..
.)
g = 96 g = 16 g = 05
E(err)2, 93.3 7 6
. where (err = percent error) ç
~h~ pressure-time profiles odiscussed thus far could
!lave been obtained using e~ther the unmodified Danson injec
tion system or the KPH control system. The complex set point
.",.. pt."of.i;1e Figure 6.2' was used to test the KPH control system '\~ A. '~. , .
"' Il ~nd. to demonstrate its power in achieving a range of pressure
1 p~files not obtainable by\'other available schemes.
•
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Figure 7.4 shows the closed 10012 rOesponse at various'
gains for the set point profile B. The 'best response was
'" ob~ained at h~gher 'ga~n values. The set point profil'e B
(Figure 6.2) invQlves a j ump from the .. 13% open loop ,profile
to the 62% open loop profil_e at a time = • 5' secQn~s. l'deally,
-\ 0 the s'ystem valve response sho&ld show' a j uf!lP from the 12%
valve opening to the '62 %. valve opening at .5 seconds. ~In
fa~t, the se;v~valve opéning variations' sho~ in Figure 7.4
reflect~ the desired (response: Prior to .5 seconds t,he
valve position is 13% at ~ll gains. At 0.5 seconds, the
jump aCj:ually taKes place •
• The ~ror needed to completely clOpe or open the se:r;vo
va~e i~ in~ersely proportional to the gain.
255 = ---.--ga~n
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The maximum error at high gains is less th an that for ' . smaÙer igain values., For this reasoI), a't large gains, a
small error (set point value - real time value), can cause
the valve to open to 100% immediately (error > err ") as , , max
compared to the response at lowei gains. Although the valve , '
position changes promptly at .5 seconds" the pressure reso
, ponse, at both gain values. is delayed by almost one Second.
The observed t.ime delay can be attributecI to the time needed
to cbmpensate for the differepce in the ram speed, momentum
az{èl inertia from one valve o~ing setting t9 the next.
During the initial stage of the cycl~, due to the small ram
veloci ty (Figure 7.5), the amount of polymer in the mold
cavity and sprue system is less th an the amount of material
found at the same point in time using a 62% open loop profile.
At the transition period t = .5 s,ec the system ~as to compen~ .
sate for this difference causing the controller to Decorne
saturated (valve 100% open) in an at,tempt to follow the
~ransition jump between the two open loop pressure profiles.
In fact, if one looks at Figure 7.4 i t is noticed that the
system response is very similar to the set point profile
except that the response is delayed by a time "factor t. This
factor corresponds to the 'time i t takes the system te respond
to the sudden change in valve position as mentioned above.
The set point profile B represents the transition profile
between two limiting cavity pressure profiles.. The 62%
valve position represents almost the maximum system response i • l
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-93-
./" . ,.
while the 13% profile ,represents the minilllUIn valve position i$
to 'achieve a good sample. , . , . . ... ,
Utlhz1ng this profile enables
us to study the maximum variations. that can occur using the ~
KPH control system thu"s helping' to determine the limitations
and capabilities of the operating system . .
During the packing stage, it is even more difficult to
obtain ~xact -control of the process because the flow of' oil
through the servovalve to the back of the injection ram is
small. Changes in the valve opening, at, such, small flowrates
have only a small effect on the ram pressure, thp.s liiniting o \
the action of the controller. This can' aiso be the reason Q t
for the time lag and large variati?ns-Ehat exist ,during the
packing stage.
7.2 Velocity Control
Figure 7. SA illustrates the open loop response for various
val ve settings. The rarn velocity at the' various valve , , positions lis given by the slope of the displacement vs time
G \
curve. The open loop response of-thé system is limited to
"constant velocity profiles during the injection process.
The velocity versus servovalve ope~ing is shown in Fïgure
7. SB and is seen to be only slightly nonlinear for openings
between 60% 'and 100%. Valve openings above 62% do not giv'e
significantly higher velocities and a velocity of 3.5 crnls
repre'sents the machine limi t for operation wi th this mold and
resin (barrel ternperature). \ \ \
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FIGURE 7.5A . Linear Displaëèment vs Time Open Loop Data!,--
TI~, sec:
v • velooity
FIGURE 7.5B Velocity,vs Valv~ Position Open ~oop Da,ta
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Figure 7.6 illustrates the closed loop response using
a 62% open loop profile with ~he linear displacement as the ~.
feedback element. Sirnilarly as with cavity pressure control,
t~e best response is attained at lower gains. The [/error/ 2
are as follows:
62% 0pen loop set point profile
'g = 05 E\errl 2 = 62.76 .
g = 16 , 2
E/err.l = 64.22
g = 96 2 E 1 err / = 105. 73
(err = pe~cent,error) "
" . Regardless of the èontro1ler actionF, the rarn position is
constrained by the amount' of stroke available and the reduced
oil flow through the servoval~e. The packing stage starts
at t = 1.75 sec as indicated by the nozzle pressure response
~Figure 7.iO) and noting the displacement ib Figure 7.6 -, The remain,ing inj ection stroke is .7 cm as compared to 3.5 cm
at the beginning of the filling stag~. Thus, linear dis
~lacement control (velocity) is best sui~~d for the filling } _ 0 •
stage because of the large stroke available.
As with cavity pressure, it can be' seen that for. set
poi~t profiles invo1ving a change in valve position, better .
response is obtained at higher gains (Figures 7.7 to 7.10).
Figure 7.8 showsPthe response using a step change prOfile
which best illustrates this point. Whenever' there is a
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Linear Displacement vs Time Closed LOOP Response for a 62% Open Loop Set Point Profile '
• G = 16
• G = 96
") _ Set. Point ,. Profile
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Noter
..
reversed scale and where only one data point Is shown indicates that the response at both gains ia
.the same
~4 ~ .5 1. ,.
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, . Closed Loop Linear Displacement vs Time Response for a -Run Using Set Point Profile B À
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 • SET POINT
~ G li 96
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-98-
FIGURE 1.8 Closed Loop 'Linear Displacement vs Time Response for a Ste~ Chan~é. Set Point Profile
o 0 0 0 •••• ..
o o· •
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o G • 16
• G • 160
- SET POINT
~ ~ 6.5~~ ____________________ ~~~~~ ________________ ___
j ..... 110 «Il t-I Q
0:
:i i5 100 ..:1
10
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Step Change Profile
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o G = 16
• G = 160
SET POINT
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The Variation of the Nozzle and Hydraulic Pressure for the C10sed Laop Linear DisPlacem~nt,Response to a Step Change Profile G =,160
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N6ZZLE
;:::::== PRESSURE psi
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• RYDRAU~:tC
4 3 2 , 0 PRESSURE pd
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.1
sudden change in the set point profile, a time lag ~s
enéo~ntered as shown in the system-response. This time lag
-can be attributed partially to the proce~s dynamics, control •
strategy and machine lirnitat~ons. The control strâtegy used ~
in this study, is not based on anticipating 'futu~e valuei
of the set point profile. This leads to press~re or dis
placement (~ifferentfating tb give, velocityJ. overshoot and
at times to large variations'between the set point and the
real time.. values: Section A-4 con tains recomme'ndations fdr
changes of the control strategy using a fQrecasting method
of control., Also~ Appendix-A4 contains suggestions to modify , , (( \ 1
the hydr~u1ic system to allow for better control~uri~g the
packing ~~. However, fram Figures 7.7 to 7.9 it is eviden~ -that' the KPH system can~~e programmed to cause step changes
and other types of profiles previously unobtainab1e~ 'This l,~ ,
ability cou1d be used in fut;ure studies to determine the
transfer functions between valve'position and 1inear dis
placement as weIl as for ~he.othet\process variables. This ..,.
could then be used in testing and d~termining which control
strategy~is-beststiiÙ;(:rfë)rthe -TnJe-ctio'n mo1ding process.
, (
7.3 Nozzle Pressure ControL .
Nozzle pressure variations using th~KPH open loop . , system are sma1ler thafi those obtained with·the unmodified " . system. Typical results are shown in Figures 7.11 and 7.12.
In Figure 7.11, the three profiles are similar, each having
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FIGpRE 7.11 Open Loop Nozz1e Pressure vs Tim~ Response """"
./
62\ VALVE OPENING llt ~ ~ i t <
1-' o ""' ... 1
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"", 0 0 0 r-f
tl 2 p fi
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~ ., '\ .~.- ~_._ .. ----~
.---.. -"'---~ ... -~-"""-'" ------~ ... -
_..1..- .... ,.,.~""' __ ~~-- -~ -" __ .-- .......... c"r~ ....... "- ,,,, ___ ..:;~~ ... ~1<f.zt&r~~ __ ""'-~.\.<..o .- .... .. -~ --.---
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40-
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10
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.. FIGURE 7.12 Peak Nozz1e Pressure Error Histograrni
•
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1.' '1 -3 -2 -1 0
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. NORMAL MOD,E RESPO~SE
/
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62% VALVE OPENING OPEN LOOP pESPONSE
62% OPEN-LOOP SET POINT RESPONSE, C40SED LOOP G ~ 05
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an initial rapid increase of pr~ssure during which the
runner is being'filled, followed by a period of less rapid
increase corresponding to filling of the mold cavity.
Finally there is a second,high,~lope indicating'the packing
phase. Unlike the cavity pressure, these slopes,depend
strongly on the valve ~pening and hence raM velocity.
Nozzle pressure variability is lower than cavity pressure
variabili ty in the open loop mode of ope.ration. ,Figure 7,.12 . ~
illustrates the error histogram for closed lbop,results
using an open loop profile. Contrary to cavity pressure Q
resul ts, ·ther~ i5 no improvement in ,reducing the_system
variability under closed loop control. t'
The above findings rnay be explained,in terms of the Q
re1ationship between nozzle pressure and hydrau1ic pressure.' • • 1
The noz~le pressure may be expres~ed as follows:
(nozzle pressure~t=i = K*(hydraulic pressure)t=f_~
where K = constant .. L =" time 1ag z .03 sec
t = tirne
The pressure ratios (P)hydraulic : (P)nozzle : {P)cavity =
= 1: 7.5: 5. These are comparable to reported literature
values (35). Both the valve position and the hydraulic
pressure fluctuate during closed loop control. Changes, in
vaive position translate to fluctuations in hydraulic pressure.
, 1
l,
i ,i
"
1 ~ \
, ,
-105-
Figure 7.13 demonstrates hydraulic pressure variability
under closed loop control, employing an open loop profiïe at
vary~g gain values. The variability of the closed loop
hY~li~ pressure profiles increases at higher gain levels.
This variability of hydraulic pressure is magnified ~hen
translated to nozzle pressur~, as shown in Figure 7.14. 'At
very largè gains, the variability increasés to a point where
oscillations take place., ~his\;ffect is demonstrated at
G = 48 in Figure 7.16.
Figures 7.16, 7:17 and 7.18 illustrate the closed loo~
response for various set point profiles. As'can be see~ from
these figures oscillations occur ,far- ga~ns larger than' 48."
The maximum g~ins for the linear displacement scheme can be
as large as 160 as shawn in Fig-ure 7.8, .and for cavity pressure
control equal to 96 (Figure 7.4). With the nozzle pressure
response to the set point profiles A and B, using closed loop
control as shown in Figures 7.16 to 7.18 it is difficult tb , 0 ~
obtain smooth ~ofiles because of the relationship between .
the hydr~ulic a1d nozzle pres~ure. It isosuggested here that
by inputting a smooth hydraulic profil~o the servovalve and
using a feed forward strategy, i t rnight be pd'ssible ta obtain ,
profites that do not exhibit the large variations encountered
with the present closed loop feedback system. The missing \
link that needs to be incorporated before. such a' strategy
can be put into action is the operating relationship between
hydraulic pressure and servovalve input .and nozzle pressure.
, , f , i 1
(
-106-
FIGURE 7.13 Hydraulic Pressure vs Time Profiles: Illustrating the Variability of.the Hydraulic'Pressure Response for a Closed Loop Nozzle Pressur~ Test Using a 62% Open Loop Set Point Profile, G = 16
1 2
TlME TIME
3 4
•
)
TlME TIME
o
1 •
1 1
\
, ,
,
~
0
... ..-'
-107-
FIGURE 7.14 Process Variable Responses for a C10sed Loop .Nozz1e Pressure Test Usin~ a 62% Set Point Profile, G = 96 "
J!
645
~----~--------~22 LINEAR DISPLACEMENT, cm
- J. j,:
-
IS 4
0
TIME,
...
""
776
'" 118
2 0 sec
do
or; ~Ul 0.
.. ~ ::> U) U)
I%:l ~ Il<
I%:l H N N 0 Z
. r; lQ. 0-
I%:l ~ ::> U) U)
~ Il<
(J t-I ~ ::> ~ Cl >t ::=
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l
11'$,
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.......
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1
1
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;. ---Il,
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4
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t! ~ a 2
\ 110
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1
.-
;>
~-) ... ... ,
r'lGÙRE
.'
...
7.15·- C~osed LoQP Nozzle Pressure vs Tirne Response 1 for a ~t%' Open, ~op Set poil~t Profilé
4
Y'" ~ ..
0'
-,
5 1 1.5 'l'IMB, sec
o
• G - 05
• G .. 96
, SET POINT PROFILE,.
,~
...
-,
. '..,p
"
t~
"
.... al __ .""'t""- ,,,-.II~ Çfeaq"",hf"!I~~~"-~~~
.. ..
.. ~ 1 ....
0 r. 00,
o ,-
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--- a
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~ 1
'F
... :
~-
J
, _____ "". __ ' __ "'" f· . , ~ , __ .~ __ ~"""~A le ;4M;4!RW4$iiQtl'(""iiiitC"!.~ .. ~~~'OjOiN,,~...,.,., ... ~ ...... -~:::,~ ... -'" .,.,..',..~~~'-:- ~"-"""'~----~""", .. .,....,,..~ • .---.
f1 .... ;
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'7
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-ri • o.. . ! CIl a 3045, Po
1827
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,
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FIGURE 7.16
, ~
5
~
-\;. ..
'Il. l "
:.l' G
#II
...... \
Closed Loop Nozzle Pres syre vs T1me Response for a Set Poi~ Profile A
/
... 1
--
. '
'1
15 "ime, sec
• •
ft
Sft POINT G .. 48,
G = Hi
, .. :::,.
2
TI
.---_~ ........ :'l..o~_.~"".....:!!L_= ... ......,._ .... _______ .._-
""
.e:J •
<> \ .
-"~'_._-~-' ." 't'j ,~ ...._,
>-.J
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, ~
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1 ..... o \0 1
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• 1 ~
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4
... al a. -. :! ~ ::l ,(4 1/1
fi! 2 "
At
1
.. '100 l?
,j!l
! 0 50 III
~' 0
-110-
~
FIGURE 7.17
' .. Â Â •
• .. • • • • •
"
, '-- .
"
Closed LOop Nozzle Pressure vs Time Response for a Set Point Profile B
Â
• G • 48
6 {.~~~
G-l ,~,J ,
SET POINT
 .. • • Â
• • .' • ,~ u'
t'
~
,f 1
'l':uœ:~ •• c 2
~! ,
J
, ~ - .. ~
_.---~ ."'_ ......... '- -..... - ~~~ .. ~ ",,,,~._~,-- ................... -......~--- ~""'~~-""""''''''''''''''''~''''-''-.... ~'-: _ ..... ,
!
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r
., 1
1
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1"
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1 t , .-
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t . ,
;,
-1:11-
, . FIGURE 7.18 Closed Loop Response for Set
Point Profile B, G = 48
1 _
,TRANSITION 8:45 ,POlNT
El ()
13% ..Ji _______ -.,;:~---...... 2.2
LINEAR DISPLACEMENT , .
1 •
"
Note: Linear di splacement profile is a jump from the 13% profile to the 62% one at t = .5 sec.
___ .. _,~ "' ... ...tr ........ 4"',,~
1
\
4 'r~ 0
1 ! i ~ cl 1 • :! j î 1 1
l,,' ,
. i· l
\ • 1
.,.; \ III a. ,
f;l ::l fil Ul
net! p..
r.l ..:l N N 0 Z
(
.,.; III CIo ,
t! 0 III (Il
~ II::
\ 18 p..
CJ ~ 04 0
~ Q >-
i :r::
. i !
'\
\ (
-112-
)
Noting the lînear displaceme!lt profile '(Figure 7.18) for
the set point profile B, we notice that the response is a
smooth curve with a transition occuring.from the 13% to 62% , -
profile at the tirne ; .5 se~. This is the desired response " ..
using the set point prof~le B. Cornparing the differences
in the variability of the nozzle pressure and linear dis-
p~acernent responses, it is evident that the rarn displacement ,.
is srnaller. ,This further high-liq~ts ,sorne of the previous
results indicating that ram displa"cement appears to be the
easiest variable to control. However, before any definate ,JI)
conclusions can be made, the inter-relationships between the
procesS" variables will have to be 'deterrnined as weIl as
deterrnining whièh process variable is the most significant 6
in order to control and give a part with the desired fin'al J properties.
7.4 Hydraulic Pressure Cont;:rol . The open loop response of the hydraulic Rressure as a
function of the valve position is illustrated in Pigure 1.19.
:As in the case of the nozzle pressure strategy, the closed
'loop results at higher gains (> 48) caus~ the system to
~=- oscillate (Figures 7.20 and 7.21). The closed loop response
usjng an open loop profile is stable for srnal1 gains « 16).
This is pQssible because the valve opening remains fairly
co~stant. At higher gains (G ,= 48), valve position fluctuates
to compensate for the error difference, and in turn, increases
Il ,
. .
\. :
, , " 1
1
! , i
_~. J~
'\ (
, ",
"
" ,
,
...
- ------~-- ---~--- -- - --- -e---
. ,
-113-
FIGURE 7.19 Open Loop- Hydrau1ic Pressure-Time Data
13~
6 4 SECONDS
2 o
PSI
708
590
472
354
236
118
.. o -..
, , J
\
\ ! , "
J !
i
1
1 1
1
.
~
1
J
~-~ .. -
-
G
t
)~
~
60
tl ~ cn- 3 tJ Ilot
o
,r
FIGURE 7.20 Closed Loop Hydraulic Pressure Data for a 62% Open Loop Set Point Profile
~
~ • G = 16 .. G ~ 48
SET POINT
A ~ .} PROFILE
, .
-----
7
1 2
TIME
\ ".
" ..:.. ......... .-....~~~~i_!.:: .... -'-"-~~ ... 4t.~~~~~,».'".t .. _ ... ""'-'~.....t<...-- "_~A_-'~ - .' ,-
,.
...
~
,/"
-
"
~.
,"
1 ...... ..... ~ 1
.. ~ ... ~ ..... -_ ...... '-"'----~~-...~--~~
1 ~--
~
-- o'
il
..... lle>'
•
.... • Il.
~
t1 p III III
m
600
~
~
.. FIGURE 7.21
~
~,
.&
.. ~;·r"""'_"",~J<.s1"~~"""""""~'<:",~ "''',''~ •• _ ~_,~ ..
C10sed Loop Hydraulic Pressure Response for a Step Chanqe Set Pofnt Profile
~
.&
.. Â
1 2 TIME, sec
 G = 96 SET POINT PROFILE
Â
Â
... '-" ~ -~----""~-"""""""-- "'-'" "-"'- ~--- ... -_ ....... .- - ... "'''-..., .... _ ... ~ff4''''"'''''''-I~, ......... _;...,.\4.0~..........-. .. _~:!''- ~-
-.
~
1 1-' 1-' Ut 1
~
..J,
' ......... _ ..... _"1 ___ J"" .......... ~....,.. -------...~"'J...~~
f"
•
,. ,
1 1
)-
the system variability.
-116-'
Figure 7.21 shows the response of the hydraulic pressure
to a step change profile. The response for a gain of 96
illustrates the "instability encountered at higher gains.
Figure 7.22 shows the effect of this instabili ty on the
nozzle pressur~ and linear displacement. The' nozzle pressl,lre
fluctua;tes in a fashion sirnilar t'o the hydraulic pressure,
while the linear displacernent is relative1y smooth. The
cause of the instabiliby is ~s discussed above.
The maximum gain for stable operation of the system is
below G = 48, as with the "nozzle pressure. To obtain srnoother
hydraulic profiles a feed forward system shouid be used as
discussed above. ,
q.
"
-
1
,
1
1 l J i • !
( ,
\ FIGURE 7.22
\
'(J
~, ,
.... .
-117-
Nozz1e Pressure "and Linear. lDisplacernent Responses for a Test Using\the Hydrau1ic Pressure Step Change Profile, G = 160
TIME
TlME
5000 .~ 0.. .. ~ ::J t1) t1)
2500 ~ 114
~ H ~ ~ o z
6.45
2.2
•
\
.. E-i Z §! ~ u ..x: H' Il< tIl H Cl
~ ..x: , ~ z H S' HO
1 ! i l
1
1. i 1
-, IC
\
..
-118-
CHAPTER 8
SUMMARY AND .cONCLUSIONS
The main objective of thë present pro;ect was to design,
construct and operate a mic~opr6cessor based injéction
mOlding control system. -This has been accomplisheü by
modifyinq the Danson Metalmec SR-60 in;ection mOldinq
machine, as outlined in Sections 3 and 4, for operation in
,,'- con;u,nction 'wi th a microprocessor based' servocontrol
system. The resultinq KPH contrp.l system has the following ...:;)
capabili ties:
1. Operatinq in the nor~al mode or in the computer con-
trolled mode of operation
2. Controlling the machine sequencinq
3. Programmability ~or open loop or closed loop control
4. 'Interactinq with othercomputer systems
5. Continuously monitoring and/or controllinq cavity"
pressure, nozzle pressure, linear displacement, or
hydraulic pressure.
It has been shown that the utilization of an open loop
control program in conjunction with the servovalve based ,
hydraulic system leads to reduced process variability ~henr
compared to the behavior of the unrnodified injection mOlding -
machiné.
- As outlined in Section 7,,'i t is possib'le to employ the
KPH control system in order to achieve cavity pressure,
~ .. -'" ~~ ....... ~:--J"->f
,'.
J
J !
, 1 J
1 j il 1 j
1
( , .
\
,
(
(
-119
-nozzle pressure, llnear di~placernent, and hydTaulic pressure
profiles as a function of tirne whiqh are unobtainable by ,
ernploying the unmodified injection moldinq system.
" Although the quality of the response obtained with the ,
KPH system was not as oood as would be desired in commercial r
applications, substantial irnprovement should be obtainable
by employing different control strategies sirnilar to the
one outlined in Section·A4. For this purpose, it would be
necessary to carry out a study of the dynamics of the process
1J. •
"and the ~'ilteractwns arnong the various key variables. . Such
a .study, which has been enhanced by the control and data •
acquisi tion capabili ties of the 'KPH system, is currently in
progress in the Chemical Engineering Lab8ratories at McGill
University.
, .
.-
• r
J 1 ,
\ !
1 ! } Î 1
------------i-f
,
1
(
-120-
CHAPTER 9
BIBLIOGRAPHY
1. S. Kenig, "Injection Moldinq of Therrnoplasties", Ph.D. Thesis, MeGill University, Montreal (1972).
2. P.H. Doan, "Injection Molding of Thermoplastics in 'Reetangular Angular-Cavities", M.Eng. Thesis, McGill University, Montreal (1974).
3. G. Williams and H.A. Lord, Polym. Enq. Sei., !,1, 553 (1975).
4. J.F. Stevenson, Polym. Enq. SeL, 18,577 (1978).
5. F. Moy, "Microstrueturè and the Distribut.ion of Tensile Properties in Inj ection Nolded Polyet.hylene", Ph. D. Thesis, McGill University, tiontrp.al (BaD).
6." Z. Bakerdj ian and M.R. Kamal, POly. Eng. Sei., 17, 96 ' (1977) •
7. D. Kalyon, "An Integrated Experimental Study of the Injection Moldinq BehavioI' of Polyethylene Resins", M.Eng. Thesis, McGill University, Montreal (1977).
8. G. Menges and G. Wubken 1 SPE Antee, !i, 519 , Montreal (1973) •
1
9. T.W. Owen and D. Hull, Plastics and Po-lymers, ~, 19, (1974) •
10. -M.R,.. Kamal and V. Tan, J. Appl. Polyrn. Sei., 22,2341 (1978) •
11. E. Boehme, Kunst.stoffe, §.Q, 273 (1970).
12. W. Woebcken and B. Heise, Kunst.stoffe, §!~ 99 (1978).
13. _M.R. Kantz" H.D., Newman Jr., and F.H. Stipale, J. App1. Polym. Sei., 16, 1249 (1972).
14. E.S. Clark, Polymer Preprint.s, 14 (l), 268 (1973).
15. R. R. Whisson and K .A. Scott, Plast.ics and Polyrners, !, 251 (1970).
"
1 'j f ,
~.
j. i 1 l
. ~
(,-- .
..
-121-
16. T.J. Jordan, F.L. Laezko,. R.T. Maher and H.T. Plant, Modern Plastics., ~, 96 (1.972).
17. D.C. Paulson, SPE Journal, ll, 37 (1971).
18. D.C. Paulson, Modern Plastics, ~~ 60 (1979). "
19. cT. Sne11er, Modern Plastics, 1,42 (l97Q). - Q.
20. P. Thiene1 and G. Menqes, Po1ym. Enq. Sei., 18, 314 "(1978) • ./
21. K.K. Wang, S.F. Shen, C. Cohen,.C.A. Hieber; A.I. Isayev, S. '.\'anhanmir and A. Taylor, Pri vate Report, Cornell University (1979).
22. J .N. Peter, SPE Antee, ""r8..1 J~47 (1972). -fi \
23. G. Menges, S. Stitz and J. Varqe1,·S~..E ANTEC Papers, IR, 843 (1972). ~ ,-
( 24. C.y.t'l. Ma" Polym. Enq. Sei., 14, 768
, .,.
(1974) •
25. • C .M. Baranapo, SPE ANTEC Papers, 21, 154 (1975).
26.
27.
28.
29.
30.
31.
32.
33.
34 .
35.
R. H. Perry and C. H. Chil ton, "Handbook of ChemicaJ. Engineerinq", McGraw Hill (1973).
D.H. Harry, SPE ANTEC Paoers, 20,.53 (1974).
R.S. IJal1as, Plastics Enqineerinq, :z., 22 (1975).
D. Smith, SPE ANTEC Papers, 21, 225 (1975).
H.O. Hel1meyer, H.n. Lixfeld and r,. Menqes, Kunststoffe, §.l, 184 (1977).
N.H. Gold~n and N.R. Schott, SPE ANTEC Papers, 21, 158 (1975) .'.
J.W. Mann, Plastics Enainee~ing, l, 25, (1974).
W.J. Thay,er, Plastics World, l, 45 (1975). ,
M. Takizawa, S. Tanaka, S. Fujuta and K. Kayanuma, SPE ANTEC Papers, 31., 165 (1975).
I.r. Rubin, "IniectionMo1dinq Theory and Practice", Wi1ey-Interseienee, New York (1972).
36. S. Sidi, "The Dynamics of Thermoset Iniection Moldinq and the Anisotropies of Mo1ded Parts", M. Enq. Thesis, McGil1 University, Montreal (1980). '
, ,
. ~---- ~---- ---
__ L-_
" /
J'"
1 . ,
1 • 1 •
1 l
! 1 r J 1
l ,
1 J 1 ,
1 ~ l , j
j '" Î 1
1
!
--,1
'\ i 1
• b
t . ~), -. J ,.-.
1 .!
- \
, -'i
\'
.~ \
,
..
1
(
. ,
'.
, '
-:122-
37. R.F. Williams and L.H. Pancoast Jr-.';-Modern Pl.astics, ~, 185 (1967).
-?. '" Q
38.' R. R. Whisson, P1as.~ics, and Polymers; ~.' 280 (1970.
39. G.P. Box and G.M. Jenkins, "Time Series Analysis, Forecast.ing and ;,ontrol", Holden-'înly (1976).
. 40,,~J.F. MacGregor, The Canadian Journal of Chemica1
Engineering, 51, 9 (1973). ,- '
i '
.' . '.
\.
o
)
\
-\
~.
" ..
,~~,. , ~ _ ~",-E..~ __ ",_"' _ ___ .... ~_~, • __ ~~ ...... ~~~ ______ .,... __ .. _~_ ... ~..,>_ ....... , __ "",:,\<",~- w~ -
, ... ~- li , _
, .
,
1 t , ,
i .," II"
1 .1
,1
'.
"
APPENDIX 1
"COMPUTER HARDWARE
Al.I MOèG AO-76-l03 Servovalve J .
The servovalve control system incorporatès the.~o11owing
COIitpo~ents :
- servovalve
mounting manifol&
servo amplifier
Figures lAI and lA2 illustrate the response characteristièS
of the servovalve. Figure lA3 is a schematic of the servo
amplifier used in the KPH control system. '
Al.2 OPTO 22 IIO Modules , ,
Th~ OPTO 22 I/O system provides an optically isolated
interface between the,microprocessor and the injeétion
molding machine. The system consists of a mounting rack-'
and p1ug in modules. The modules provide for 117 vac ou~-
put and for 115 vac input. The output modules control 'the
hydraulic solenoid valves with the control system, while ".
the input modules interface the limit switches. •
I/O Port Specification: ' Para11èl Ports 1716 .and 1416 on the Swi tchboard
"
Port ~16 = output (~onnected to OPTO 22 I/O Modules OACS)
Bit Function
o solenàids 5, 8: 0; closes mold and supplies ail to the pressure port of the servovalve
~ , ............. y'_ ... y .......... _ .. _ .. _ ... l -,'iI"'_ ......... "~ ,~ ... ~~ .. __ r "_. ___ 4 , ... , -""'''"j ~ -~ ...... . ' ,
, . l 1 1 '
1 ,1
t ".-~'-'-"-"'~-" ',' '
1:
f () r f • ' , t ,~ . ~
l' J" , , . ' ,. ,
, ;
) ". \
, . . .-
',.,. '. , .. ~'
. ,
, '
"
"
, ' ,} .... ---~;;~---~;---_ .... -
. ,' -124-
." ' • f ..... ) 1
" . " .
.. "
. . .
. " • ............ ~""~,.,...~~.,~4~r-...... _"""' __ w.,.,...~Pf~_ ~
r " 'FIGURE' lA! èhange, in Rated Flow
, i
.. ~ ..:l' ~
Q ~ S, 1. o '.7
with. P:ressure
" , ' .
" ,
z ,S~~--~--~--~ ____ __ 200 300 500 'ÔOO 2000
VALVE PRESSU~ DROP, psi
- 1 • ( .... _~_ ......... < .... ~-,~-;;,~, ........... ,.. ... ~ .- ... .. ~ ............ ..,.."'wI-4_ ... i~'~ ... ~,N ____ .........,::..~_"
",
" f .
. j. l' ~ ! , 1 f ' ,
" .
c "
" "
l
tH
/ ! ,
'1' .' .
.,-- _~ .. ~ ~_...., .... ~- .. r"l-... , .. ~.~~.~~~tl/'O<,~~~~-"'r~~ .. .:t"".f':'~~"""~"'-~""~~7"~~~P1="t1ti ,J!:!I''''M_ 4).P9~U_'" ~"t-_'I"- .. ""_~,,'_"""_ 1 - -,
~ • . ; & 1
."
~ . t . Ii
~ } t ~~ ;
i • . 1
" i ,
! , \
,: l' t
1.
~
snPlnl
r ""t-'m::""'
FROM DAC
"
''ft ,
---- " -.
FIGURE 'lA3- ,Servo Amplifier Ci-rcuit
·r
---------~-------~--------------~------~-~---, , .", . ' 1
~I un"',
• 1 - 1
.... "'.'1 R.. t .tn Il
1 1
~ ... I un 1
1
~OO -~,c.& ll20
IGOMO ~
1 1 1
~.I RI.
t ... Q~'"
"ul '0
'" a 1 Il fUlllflOlmllClW.ÎIDoac;MCI "1111 Il f(lOI~I('''lAIlONfI[MCMlll C4 ---~
A rUJQlftllll&IINAU. -1 KIIIl __ ~ , CI 1
oE • 1· H"'" 13 • , -, '1, '.=:j ----~---~--~----------------~---------------
lDOKn 4"1(0
~
,
OUTPU~ (ma) 15 ma 2.55 V~lts .* Input Voltage =
'.1" ---~
" l~_
"
r"~-- - •
" '
. .....
- ................. -...... ~ .. ~~'--'.,~-,--... ""'.----
I~
~"""""_~':'----~"--':"""'~~.'-~""""""''''''''; __ -.........
'--
. ,
", - . . '
! I-
i
1· 1
l l
\ '. '\L t . ,
l
1 i" \ i
1 SERVOVAlVE
OUTPUT 1
1 1-' - - i· I\J '1
YI t . 1 ' 1
! '. J . . l'
" t ·t'
-1 " , 1 ; !
" ~ \
"
..
. ' ~
-_ .. _ .. ,.~~.,.,... ... 't""""'-.. "7''''''''-'''_. -_. ~""'--~.
,Bit
o
1
" , 2
3
4
5
6
7
Port
Bit
/~ i"
3
4
5
6
7
-126-
• Function
i /
'/
,solenoids 5, 8: 1: no action
MCI\.:
Restart Btu:
Solenoid '7:
Solenoid 3,' 2 :
n/u
0; connects the solenoids and timers/ " normal operation of the machine
1: disconnects the solenoïds and timersl microprocessor cont~ol
n/u
0: reinitiates cycle 1; no action
0; reciprocating screw turns; allowing, for plastication of the resin
1: no action
n/u
0; opens the mo1d and retracts the ' carriaqe'
1; no actIon
1416 ;= input (connected to OPTO 22 I/O Modules IA~
Function
n/u
n/u
n/u
rt/u
monitor LS4 mo1d/carriage closed
monitor LS3 mold/earriage closed 0
n/u
monitor LS7 mold/carriage closed
' .. c:II'
)
;. i
f
i ! 1
1
1
J
1
1 .p
1
1
.1 -127-, '
,
, 1 !
1
Ah 3 Analog to Digital Converter (AOC)
The model SDM 856 Analog to Digital Converter (AOC)
was designed for random channel selection (F,igure lA6).
The ADC instrumentation ampli,fier ~as specified for
~nalog signaIs in the range of 0-20 mv. Fiqure lA4 is a
schematic of the signal conditioner used for the linear
displacement transducer. Figure lAS illustrates the sequence
9f-activities for an,ADC cycle. The computer prograrn to
access a channel on the AOC is shown in Appendix A3,
subroutine "Data".
Al.4 Digital to Analoq Converter (DAC)
An 8 bit, MCl408L8 Digital to Analog CO,nverter (I?AC)
was used to provide a signal from the microprocessor in'
" , voltage forro output (Figure lA 7). The DAC was connected
to the servo amplifier to drive the servovalve. The DAC
was regulated such that a digital value'of 25510 on ~arallel
port OBHEX
of the SCC gave a value of 2.55 volts at the
DAC output.
, i
j-1
1 1
, 1 ,
Il , .
i i-
i ! 1
1 1
1
" ,
<
"
". ,
'.
..,
~
""
r " ,,,4
+,() ~
LINEAR 'OISPLACEMENT TRANSDUCER
~
.'
10K..Jl...
"1 ,
"
-12V
TL081 . 310 VOLTAGE fOL(OWER
\~
~
()
ADC
'1
FIGURE lA4 Signal Condi~oner Circuit for the Linear Displacement Transducer
~,
---
+
1 ..... I\J
"'0) .
•
. ;
k~ _____ .... _ ....... ",~ __ "",," d'lAt Si) 't; rSm ;"t --------~~~~- -....-.----. __ :....~...,,...~~--:"'w f.'I;""W tMZS't
"
"
• G
f -(
i .~
î f r ~ !
'" }'
o i "
"<
t li } ~: @ . J, , r
-129-
FIGURE lAS
'.
"
AOC Operation Flowchart
t
\ -
n;s
~
•
1 ! 1
j
'f 1
i Î l
1 1 l
l ! J i
1
1 l' 1 1
i
~,
(
FIGURE lA6 Analog to Digital Converter Schematic
!
____ !!'!!!!t.... ... ..... - ........... .,. ... Mt.
., \1 !W:: : · - .. rrw"': co:' -az ": , l , , -, -L _____ J T -- .. . liillfl .
ft' .,. a GI iiiitl Il • os GI
.. .. ~ /d - , .j ,
t l i
~ '" ~
~
'" ~ ~' ,~,
" ~ •
'r \ '
'l'
flOURE 1. SDMU6/m Block Diapam. i J 1 l
SIrbI IMI SDIII .. c..
liIQIIII
....... r:----- iiii ..... ~c!:. .... : ... &J ..... : 1 1 1 1 1 + 1 1 U. : 1111 : 1 • ..,_ 1
'- _____ .-J lIoqioII
" "
.... ~,' ,
. 1
l t "
--~- .. ----~~
/
~
Vec
"SV'
, ;><..
, 1 .... ~ -, --- .... '~ -~ ....,. ~ ~~, ..... .., .".,.. "'... - ....
2.6V
VREF
....
MSBk 1 13 1 ~ 1· 1 5 14 ~ .. sv 6 15
~ __ ~HC ~~ ...... , ,-
" . '
~
1 D a :8 1 m, .... -=- ....L. 78L26AWC
9 ~
n , lK~
LSB , 2 ~ 2:J . 0 ~. 10 ~ 11 - fV 1 1
,/ 1 16 3 4 - ~1' ~VOUT (O-2.55)vOLTS ~
~
;.4, -sv va.
Y2' TLOS2.Cp
..
FIGURE lA? Digital tO.Analog Converter-Schematic 1
Note: AlI resistors are i, 5%
c'
-
-- ... _~ SM"' .. r be "-~- -------~ '*.... (OlIM
"
"
L
i ~ i·
t j
" '; \ 1
t ! ·f ~
~ t ~ .-' ,I
CJ~ t 1. f '<. 1. 1
r
1.
1
.:
j
-132-
J
APPENDIX 2
INSTRUMENTATION
./
A2.1 Transducer System
Three pressure transducers manufactured'by Dynisco,
*odel PT435A, wer~sed for pressure measureme~. One
transducer, range 0 - 20,000 psi, was located in the nozzl~i
while a second transducer was mounted at the gate, range
o - 15,000 psi. ,The third pressure tranêd~cer, range
o 1,000 psi, was located behind the injection ram of the
hydraulic system. When not in use the hole in the cavity
was filled with dimensional1y similar plugs replacing the
transducer. Each transducer was calibrated prior to install-
ation by applying a known pressure and noting the transducerJs
millivolt output (36).
Pressure Transducer Calibration Data
;> Area of, the plunger::o .779·in2
Tral}sducer Transducer # 116374 # 432A Excitation 6.48 V Excitation 6 V
Force MV Force MV (kg)
• r
173 .3 56.14 .6 410 .7 84.1 .7 52;1. .73 140.35 l.
1500 1.5 168 . 1. 25 2692 2.85 224 1. 82 3505 4. 336 3.7 4010 5.4 .. 392 5.6 6169 0 8.2 449 6.15 7011 8.4 9955 12.4
Transducer # 116978 Excitation 6.01 V
Force MV·
200 .56 300- .85 400 1.13 500 1.41 700 1.99
1000 2.85 1300 3.72 1600 4.58 1800 5.15
., .' •.
.fi. ...
1 j i
1 j 1 f
r 1
,
f l 1 j
. 1
i , l ,
__ J
,.
".,.....
1
'>-
"
0,
Transducer
116978
116374
432A
",..,. ..... , ..
" '.
TABLE 2A1
REGRESSION COErFICIENTS FOR THE TRANSDUCER CALIBRATION EOUATION~
510pe Intercept psig-rnv psiq
985.25 18.08
776.7 95.9 -
59.7 66.2
1
Regression Coefficient
0.999
0.999
0.999
Location
cavit.y
nozz1e
hydrau1ic system
-
1 1-' w w 1
. ~-
1"
--- 1 psi = 6.9 x 103 N/rn2
..
\. i,' ~ .'
~ .1
l' ~-~---- -~~-_._g~-_<~_.ol~~~~_"''''_~ __ ''''_~'_'-'''--- - ------ , .... _-- ......... ....,.,.~ ................ ~,..,.....-..:-~,. ......... -.......:..~...s.~
..
(
-134-
~ A2. 2 Lineal!' Displacement Transducer "l.. ~ ~
A linear displacement trànsducer was used to monitor
'. the movement of thec:treciprocating screw.
;\~ The transducer was calibrated·br1~~ to installation
(5). The calibration curve is shown in Figure 2Al. The
règression equation obtained for an excitation of 6 volts
was: D = 18.38 - 3.12 *V, (regression coeffic!en~ .9~9) , -2
where D· is the distance in cm (10 m) and V the output in
volts.
Linear Displacement Calibration Data
Excitation 6 V
Distance Out12ut . (cm) (vo1t~)
3 4.925 4 4.625 5 ' 4.275 6 3.975 7 3.635 8 3.325
L = 18.38 - 3.12 *V
L = cm
V =' volts
A2 •. ~ 'Rectangu1ar Cavi ty
The rectang~lar mold with the geometry shown in
Figures 2A2 and 2A3 was employed to mold aIl the test .
specimens in this ·study. The cavity used was 4 inches
long, 2-5 inches wide and .15 inches deep.
-.
J !
l , !
" 1
1
1
1 1 1
1
1
, Il
• R
~
'~ E-4 l-l 0 :> E-4 ::J Pot E-4 ::J 0
< •
5
4
3
2
1
-135-
'li
1 r J 1 J
1 b
! l'
'0,
6
FLGURE 2A1 Linear Displacement Transducèr Calibration Curve. Excitation 6 V
"" ç"
tf
~ ",~. - 5
DISPLACEMENT, cm
.'
,r-
o •
..::>-
'0l (!
7 9
'\.
• . .
.--' -. '.
, . )
o
\'
1 l J l 1
t , 1 1
. 1 ,1 j
!
1 ,1 i' 1
1
J
1 1
1 J
--~-- , ..... 1 \ ,
t"""" ... ~~ .. -
"
",
4
. , Q
_0
'::, __ -;--10 __ _
" .-_ ..• - --.-, --Ji ,- -~~-...,....-~._--, , ,
• ~.
"
-" " ~.: ~',
.,"6 ....
r .5"
1
~ ,-) '.
e
CAV ITY PLA TE
A
1
1 1
. · ,
- 1
1 ,
1
: ~ . \ 1 ,
1
• 1 • 1
Àr
~ -jF"
1 ) \_,
12'
e
r-- - r- - - ...... - -- 1----1
, .. ~ 1 . ,-) .8 • 1 • .. ~ s~
~ ~
~ 5 ~
BACK-UP PLATE Il lOS" li
A lJ
4>-." 1 • ,.'
l ri 1. OB
1
1 t T ~
~2 4 :"'1- ....
! ---3.
,1 1 :-)
~ ~..;é_ ,,- ')
.t-,
T 1
l'
~I
6
Tl 0 ~ Pl
..." if_
-$-,., 1 • . "
~
1 2
i 'r ---p1. ~6--IP3 T3 ••
T401p4 •. '
.A~ .
Figure 2A2 Cavity and Back-Up Plate Showing Transducer and Thermocouple Locations
;.""
~
~
~ ~ .... ~"-- -~-..... ----,,----
-- o
...
, '1 1t
\.,"
"" • !
,~ t:: :
(, , .
, 1 1 ~ W 0'1 1
.....
l 'k l
l 'j , 1
1 '. 1
, t~ !
·i 1
................. ~"'--............ _ .. ~~~ 1iI"fI"!'fi"t'" >rh sN Ë t~"~fQ id!'; • f1d.""".eb :f!::ttt.1i:.,t l,",~-- • ~---~ ~-,." ..... _~ '~lGf il' il/ôlli. 'H';'S t~ 1 ....
1 r -. "
~ \ 1
(
1 l' l
1
,
! • ,
<
l'
, .....
"
,. ,
)
-137-
, "
FrG~RE 2A3, Cross-Section of Mo1d
SECTION THROUGH C-C
c:avity plate
clamp pla te
insulation
spare bu_hingo --""-.L
'. /
\
back,,:up plate
paraUel
c:llUllp pla te
'"" ejector return
plon
sprue puller
st .. m l:i.ne "lJ,r,.."",-+-- spacer
quide pin
~ . r ~,,~ ~ ... _ .. < '" ,. ..... Rt' ~ _ _~.
knocJcout pin plate
1
1 l
,
1
,\ l
1
1
t
(.
< ,
1 •
- ,~ ,- - ----- .. --- p -v - ___ ~ ______ --.~~ __ ~ ~ ___ ~ __ ... _ L
-138- -
The mold was cooled with water at 50 oF. Pressure
transducers could Qe mounted ante the' back-up plate 50 ,
that the transducer tip remained flush with the surface of
tpe cavity. The details of the transducers are given in
an earlier section (A2.l). Figure 2A2 shows the four
" positions possihle __ for mounting the transducers, with the
iriitial one right at the entrance to the cavity. A therrno
éouple can also be rnounted beside each transducer to monitor , Il .. ___
the ternperature variations in the cycle.
A2.4 Injrection Nozzle Desi2n
The'nozzle was fabricated from high carbon steel. ~he
design specifications are given in Figure 2A4.
The mel~ ternperature in the nozzle can also be rneasured
using a thermocouple as shown in Figu~e 2A4. The mounting ,
of the pressure transducer and thermocouple are illustrated
in the sarne figure.
'--
)
! 1 ! 1
, , 1
i . !
1
"
\ .. ~
...
.:--
ct •
..
Pressure Transducer
,0.203"
1.. T
Thermocouple
Figure 2A4
.~ _ --"""'J t~
t. , 1
1.372n2 . 0"
c:::"~~~~~~-~-~'~--~-<~~<~I < < < < :>H:«c 1 External Threadinq
----.". /.
j'f=
Cross-Section through Instrumented Nozzle
" Ji
- -~--.. ------------- -- ........ -_""'~ .. ;;' .. >.,. ..,."Y"'t:!t:bbr « H+ ~"'''''''''''"'_''''~~~~~1:''.AM:o~~,~"""""""",,-_,":: __ ~_A-__ -
-
l''<~
po
1 ..... W \0 1
t-
1
"
~
- !
, \
~-- - - __ L_) ........ ~.-!"'.-;,.; .... !~ __ ~~)!:$)* ',S"s._&ii '0
,(
fi'
(
-140-
'APPENDJ:X 3
COMPUTER PROGRAMS
, A3.l _, Sesuence Subroutine Listin~s
Input/output subroutines used to control the sequenping
of the various parts of the molding rpachine.
sec's parallel PORT 1416 = OPTO 22 IÎo module: INPUT Ae
sec's para11el PORT 1716 = OPTO 22 IIO module: OUTPUT AC
sec's parallel PORT OB16 = Servova1ve DAC Outp~t Port i '
Subrout~ne SOL30N: Energizes solenoids 9 and 8 wh~ch open,
\ the mold and retract the carriage.
SOL30N: LDA, 7FH OUT (17H), A RET
~output to 17 16
SUBROUTINE SOL30F: De-activates solenoids 8 and 9 thus
halting the rnovement of the mold and
SOL30F:
SUBROUTINE S70FF:
870FF:
carriage.
LD A, FFH OUT (17H), A RET
De-energizes solenoid 7, stopping the rotation of the screw
LD A, FFH OUT (17H), A . 'RET
115
115
SUBROUTINE RESTRT: Initiates the injection cycle (sirnu!ates
the start button,)
RESTRT: LD A, EFH OUT (17H), A RET
1 \ \
1 l' .. 1 , f J
i , 1 1 ! 1 1 l 1
1
l' J ,
L l
1 1
1
1
, 1
ç -141-:-
8UBROUTINE SOL70N: Activates solenoids 7, 5, 2,used for
plastication of the polymer.
SOL 7 = screw rota.tion activation cr
5, 8 = mold/carriage + closed
SOL70N: LO A, FFH OUT (OBH), A LO A, DEH OUT (17H), A RET
iset backpr~ssure
SU~ROUTlNE SOL70F: De-energizes solenoids 7, 5, 2 and
SOL70F: c
SUBROUTINE MCRON:
MCRON:
"'SUBROUTINE SSON:
SSON:
--SUBROUTlNE LS3:
."
, )
closes the servo valve.
LO A, OOH OUT (OB), A CALL S70FF RET
;null servo valve
:de-energize solenoids
Returns control of the machine sequencing
.to the relay circuitry from computer
control.
LD A, FBH OUT (17H), A RET
Activates solenoids 5, 2 which are used
for injecting material and keeping the..,.
mold closed.
LO A, FER OUT (17H), A ' RET •
Monitors 1imit switches 3 and 4 which are
used ta indicate the position of the mold
and inj ection carriage. Routine L83"
jumps ta subroutine MCROF, which switches
î J 1 J
J
~ 1
Î j
f
1 ! ~
(
LS):
LS4~
MCROF:
SUBROUTINE OPEN:
OPEN:
LS7:
LS:
SÛBROUTINE DELAY:
o
-142-
control from the machine seguencing to
cOmputer control, only when the carriage f
and mold are closed.
IN A, (l4H) AND 20H JP NZ, L53
IN A, (l4H) AND lOH JP Z, L84 CALL DELAY
LD A, FFH fOUT ( l 7H), A RET
imonitor mold positions i if not élosed j urnp to LS 3
imonitor carriage position i if not closed j urnp to LS 4 itime delay to qet good contact ~
; switch to computer control
Monitors L57, ,carriage position, and opens
the mold and retracts the carriage by
acti va ting soleno ids 9, 8.
LO A, 7FH OUT· (17H), A
IN A, l4H AND BOH JP NZ, L57
IN A, (14H) - AND 80H
JP Z, L8
LO A, FFH
OUT (17H), A RET
;energize selenoids 9, 8
;check mold position ; if not open j urnp to L57
;check carriage position ; if not retracted j urnp to L8
ide-energize solenoids 8, 9
DELAY of ;:s .5 sec te ensure good contact
between the injection nozzle and the
sprue used in Routine LS3
A = 55 Hex
B == 55 Hex
r 1
1 1
1 J
1
1 j
1 1
1
1 1
l a
r f·
, • ï , { ,
(
\ .
(
@>~ . ... .. ,. ..... -. - -
-143-
DELAY: LD B, 0 ; load B counter = 0
LP: LD A,O i load ,A counter = 0
LPI: ADD A, I CP 55 JP NZ, LPI
. INC, B CP B JP NZ, LP RET
iA = A + l ; compare A to 55 i if A f:. 55 continue looping
;B = B + l ; compare B 'ta 55 iir B ~ 55 jurnp to LP
A3.2 Remaining Sequencing Subroutines
PORT 0 = seriaI status port on the see board
PORT 0 l = CRT seriaI port
PORT OBH = servo-DAC paraI leI port
PORT 14H = OPTO 22 input AC paraI leI 'port
PORT 17H = OPTa 22 output parallel port
SUBROUTINE
READ
WAIT
DATA
SHOT
PCAV
PNOZ
PHYD
AUX
HOLD
TIME80
TIME2
TIME3
CONST
FUNCTION
prints a string of cha:r:act~rs in mernory
reads in'a character from CRT
DELAY ROUTINE
ADC subroutine
read in LDT Data Point
read in a cavity pressure value
'read in a nozzle pressure value
read in a hydraulic pressure value
auxillary ADC channel Data Input
times-but holding stage of the process
initiates timer 5 holding sequence
.. initiates timer 2 injection sequence
initiates timer 3 injection sequence
reads in 2 values from the CRT and stores
them in Hexidecirnal forrn in memory
, J 1
-1 l ! J
1
1
1
l 1 1 !
l , i 1 _
1 1 ' ]
f 1
! 1
1 :
1. 1
1
1
'1
..
';'144-
SUBROUTI.NE (Con' t) FUNCTION
CALC
CLEAR
PLAST
RETRIV
RETRIV2
STORE
INC
ERR
DELAY
multiplication subroutine
clear interrupt request lines
plasticate polymer routine
L
retrieve address from memory location§
retrieve address from memory locations
store value on channel l ADC in rnernory
-increment addresses
division subroutine to calculate Error--max . DELAY ROUTINE
SUBROUTINE PRINT: Prints a string of ASCII characters, to
PRINT:
Cl:
SUBROUTINE READ:
\
Port 01 ('CRT) stored in RAM = Starting
address = HL, until the control character
"OF Il is encountered. 16 1
register HL ~ starting string address
~egister A - changes - contains ASCII
character.
IN A, (0) AND 80H ..
•
JP Z, PRINT
LD A, (HL) OUT (1), A INC HL CP OFH
JP Z, Cl JP PRINT RET
--icheck status- port icheck output buffer i if not empty jump ta PRINT .
iLoad ASCII character ioutput to CRT port = l iget next character address ; check for control character ;if ~ OF continue printing
Reads in a character from Port land
stores the value in the accumulator "A"
register A ~ contains ASCII char acter
.. , f l
. ' l )
i
f
( ;
READ
SUBROUTINE WAI'!':
WAIT:
SpBROUTINE DATA:
l,
\
o
-14.5-
. -li,N A, (O) ;check status port AND 40H JP ·z, READ ;jump if not ready to
receive ta read IN A, (1) ;read in value RET -/
Is a time delay routine. The pro gram
will not continue until the control
character "Y" is inputted on the CRT.
Register A changes::: 59 Hex = "y" ASCII
conversion value.
CALL READ CP 59H JP NZ, WAIT RET
, ;qet ASCII value :t;rom CRT ;Y ASCII value = 59 Hex ;jump if not Y to wait
ls the subroutine that cont~ols the
operation of the ana log to digital
converter. The accumulator contains
the sensor channel address. Register
DE con tains the address of the rnemory
location for storing the value of the
converted analog,signal.
register A starting channel address
DE memory address for the
converted value
~ register A - changes to the digital\value
of the input
B - changes values to the channel
address
. )
. :
i
1 l 1 1
, c ,
DATA:
DI:
, ...
SUBROUTINE HOLO: .,
-.
aOtD:
HOLD2:
\
-146-
LD B, A IN A, (15H)
LD A, FOH ADD A, B OUT (l6H)
LD A, 03H OUT (13H), A
IN A, (13H)
AND 02H
JP Z, DI
LD A, 20H ADD A, B OUT (16H), A IN A, (15H) LD (DE), A RET
<€>
1
; load B with channel! a'ddress iclear the attention\ address port \
iA = FOHex ' iA = A + B ;output channel address + FO
;load strobe address ;actlvate strobe
icheck the Fatus of the'AOC
;check if conversion i5 finished
i jump if not fini shed conversion
;A = 20 + channel address
iread in converted value istore the value in rnemory
Controls the holding stage of the
injection process. Timer 5 on the sec
is used to time the holding sta~~ Memory
5705 Hex contains the timer counter.'
register A, C, 0 change values
register HL = 5705 Hex
LD C, 0 - CALL S50FF
LD A, 0 OUT (OB), A
LO HL, 5705H
LO A, (HL)
CP C JP Z, Hl INC C CALL HOL JP HOL02
; zero counter C ;de-energize solenoids 5, 8
inull the servovalve
; load HL wi th the mernory counter address
;load the'accurnulator wi th the coun ter
; compare the counter to C ijump if C = colinter value ; increment C 'iactivate timer 5 irepeat the comparison" process
G:;l' ~"5A. ~ ••• ___ .... " ••• 1. ...... '-~~,, __ ...
1
1 j 1 ! ~
: 1 l, i i , '
, î j
i 1 1 , l 1 i
1
(
-147-
Hl: RET
SUBROUTINE HOL and TIHE 80:
TlME 80:
HOL:
LP4 :
are used ta initiate tirner 5 on the SCC.
LD A, 80H
OUT (03H), A LD A, 08H
OUT (02H), A El LD A, FFH OUT (09H), A RET.
CALL TlME 80 LD D,O
LD A, 0 CP ODH JP NZ, LP4 RET
; load l.'nterrupt Mask adqress
~ load command register value
; enable timer ; load timeout value ~ output count to timer
; initalize tirner"5 ; load D = 0 (counter)
; A = 0 time delay routine. ; compare A value ta DD Hex ~ if A ''1 DD Hex loop
Routines TlME 2, TlME 3 are ,the subroutines used ta ir'\i tiate
timers 2 and 3 on the SCC.
TlME 2: .
;TlME 3:
INIT 3:
INIT 4: •
INIT 2:
SUBROUTINE CALC:
7
CA!.L INIT 2 LD A, (5703H) OUT (06H), A RET
CAtL INIT 3 LO A, (5704H) OUT (07H), A RET
LD A, 08H
OUT (03H), A LD A, 08H OUT (02H) 1 A RET
LD A, O·2H JP INIT 4
; load t irne coun t i output count to timer
; load time count ; output count to tirner
; set mask reqister ,~
i set cornrnand register
Multiplies the values in locations 570116
and 5702 16 together and stores the result
1 \
. ,
1
,-t 1
!
! \ l,
(
..
\
.r-
0
( ,
CALe:
MULT,: '
CHCNT:
-148-
in location 5712 16 -
,registers HL, DE, A and- B change .. -
LD HL, 5701
LD E, (HL)
LD D, 0 INC, HL
LD A, (HL) LD HL, 0 LD B,' 8
ADD HL, HL RLA JR NC, CHCNT ADD HZ, DE
DJ NZ, MULT LD ( 5 7 12), HL RET
: load the address of the first value
; load E wi th the first value,
; zero D ; load HL with the address of the 2nd value
; load A wi th the' 2nd value
,."
; store the re"sult ,.,J
" ,"
SUBROUTINE C~~~ Clears the interh1pt request 1ines. ,
register A changes to zero
CLEAR: LD A, 1 ; c1ear command r~gister . OUT (02) , A
'"' LD A, 0 1
OUT (03) , A ; c1ear INTRP mask RET
~'t"'~ '.,
SUBROUTINE RETRIEVE: Accesses the 16 bit address located
RETRV;
in locations 570816 , 5709 16 and puts it
in the regis1;e,r
, HL = the error sign f~le address . ,
PUSH AF
LD A, (5708) LD H, A c
LD A, (5709) LD L, A 'POP AF RET
; store A value in the stack ,
; load A wi th the MSB ; load H wi th the MSB" i load A wi th the LSB ; load L wi th the LSB iPOP the A value
J
.'
f ; J 1
" ,
j
, j ,1
1 .. 1 j . l ·1 h !
!
" :
(
.. '.f
, -
Po , -149-
SUBROUTINE RETRIEVE 2: Accesses the 16 bit aàdress located ~
RETR~ 2:
SUBROUTINE
INC: 0
in locations 570A, __ 510Bl6 and puts
it in the HL register.
I{L register points to the Mi+l file
~ddress • ,
PUSH AF ;store A value in the stack
LD A, (570A) ; load A wi th the MSB LD H, A ;load H with A LD A, (570B) ; load A wi th the LSB LD L, A jload L with A ,
-"' ,~- POP AF ; pOP' the Aval ue from the stack
RET
It:lCREMENT: Increments the address pointed te ,by
v
subro~tines.RETRV and RETRV2 and re.,..
loads the addresses into the prope~
memory location.
registers HZ,
CALL RETRV
INC _HL EX DE, HL
LD H~, 5708 LD (HL), D
INC HL LD (HL), E
CALL RETRV4.·
INC HL EX DE, HL LD HL, -S70A
\- -
DE change
;retri~ve the file address pointer Il'
iincrement the counter ;'exchange HL arid QE values
; load the - memo,ry ~ddress i reload the incremented file pd'inter
, i incremen t HL i reload the incremen,ted file pointer
iretrieve the M'+l fïle address pointer
.' ; increment the counter iexchange HL and DE values ; load the rnemory address
(1(
J.,
~ ...
l !
'Ij 1 7
J! ~
~-
~, c
{
1 ! 1 l ,
~
[. i , 1 ,
(
o ()
... -150-
-LO (HL), D
INC HL
rreload the incremented file addr,ess pointer
;increment HL LO (HL), E
RET '
ireload the incremented ;file address pointer
.-
0' 1
SUBROUTINE :e:RROI REF: Ca1d~lates FF16~~~in which is the
ERR:
DIV:
maximum error bound.
regi'sters A, C, HL and B chanqe.
LD HL, (5 715) LD A, (5714) LD C, A LD B, 8
ADD HL, HL LO A, H SUB C JR C, CNT LO H, A INC L
; load address
; load counter
CNT: ' DJ NZ, DIV LD (5710), HL RET
A3.3 MUSIC Translator Prograrn
The MUSIC translator program is used to control the
microprocessor system while connected to the McGiil MUSIC ,
\
\ \ . , ,
J
System. The ~t~rface is a seriaI port (Port No. 1116 ) to an
accoustic couPler w~ich transmlts and receives data through . ,
a telephone line. ~gEam offers th~ following options.
Transparent-MOde: USi~~~ mode of operation, the I.
operator can communicate with the MUSIC System via the micro-
processor without altering the rnemory of the control system.
• 0
Th~s allows fo~ easy sign-on and program modification.
.,.. ~_ ~_~'._ .... " ~ ...... " ..... ~_ .. ~_.,~ ... , .... ~ ......... ...,.. ... ~ ............ ~ ... ,. ............. _ ... _ ... __ , .,... ~_~ ...................... "'_~ __ .., , ...... -....-.... ... _~"'_1" .
1 r j
1 1 (
î i 1 1
: (
-151-
FIGURE 3A1 Music Translator program Flowchart
(') -,
"'-,
\
y
t{'
.. 1 l 1
i ".. ....,
" 1
t
1 -11 .
~:o
, -,
1 c ~ !
j-
, ...
/
NO
"
1
. \.. 1
.~
. '
, ,
f \
(
~. ""-'~~M',,, ..... ....,- "" ~1, ~~ ~,~ ~ ~.~ ,,> .. , ...... ( ~ 1
-152- r
1 II. E-mode: This mode allows the operator to store the
specifie file on MUS~C ~irectly into the memory of the
control system. The control characters bounding t~e data
file are thosé used when compiling a PLM-4 program to
supply the HEXIDECI~L op-code. Figure 3A-I is a f'lowchart
demonstrating the 'flexibi1:ity of the MUSIC translator
program.
MUSIC TRANSLATOR PROGRAM: (Stored on EPROM)
J4IN:
..
JIIN:
. ,
ORG 1100H LD C, 0 LD D, 0 LD B, 0
~->.. ~N' A , ( b )
~D 40H
JP. Z, JIIN
IN A, (1) CP 2lH
JP Z, END CP 28H
JP Z, Er·iODE CP 26H
JP Z, TMODE
OUT (1IH), A
JP J4IN
IN A, (l2H)
AND 40H
JP Z, J4IN
• r 'f
izero registers B, C, D
; check. the seria.1 status port on the SCC
icheck ta see if CRT is transrnitting Dqtg_
; jump if no dafâ' {s'sent ta JIIN
:read in value from CRT ;check for the end transmission tontrol character
;jump if zero ta end routine ichèck for E-mode operation control character
; jump if zero te E-mode routine :check fQr t-mode control character
i jump if zero ta T-mode l:O\ltine _ (transparent mode) ioutput the value from the
CRT tOI Music ;jump to J4IN'and check for another character
icheck the status port on the switchboard-connected to Music
; check to see if Data is being received from Music
rif no data is coming jump to ù4IN
""
i'
. 1
1 1
!
TMODE:
• EMODE:
END:
FIN:
(
·1 .'
r
-153.10.'
IN A, (llH)
OUT (1), .A
PUSH AF
LD A, B
AND ,OlH
JP NZ, STORE POP AF JP JlIN
PUSH AF
~D HL, l300H
CALL PRINT
POP AF RES, 0, B RES, l, B JP J4IN
PUSH AF LD HL, 13l0H
CALL~fINT , ;"! V
POP'/AF'/: " , . SET 0,' B JP JIIN
PUSH AF LD HL, 1320H
CALL'PRINT
POP AF JP 003BH J
PUSH AF PUSH HL
~input character from Music ~echo the value on the CRT
.1; store the val,ue ~on the stack ~load the accumulator with
B = control register ;check bit Di l = E-mode operation, 0 = T-mode operation ~jump if bit 0 = 1 = E-mode ; pop A f rom the s tack icontinue transparent mode loop
;push the A value on the stack
; loaÇl HL with the address pointer ta print T-mode character
iprint the file pointed to by HL
; zero bit 0 i zero bit 1 ireturn to check~ng the
CRT line
; load HL wi th the address pointer ta print E-mode
iprint'the string pointed to by HL
;set bit n = 1 ;return to checking the Music line
; load HL wi th the address pointer ta print the end
;print the file pointed~ to by HL
;JP to the sec monitor program
istore HL value on th~ , , stack 0 .~
1 1 i j J J
i , ! , ,
~ , l ' l ,
-,~. '
1
1 ~
\ ( 1 ; l
l J , i 1
( --
(
-)
SUBROUTINE PRI~T:
PRINT:
-154-
LD HL, 1330H
CALL PRINT
POP HL POP AF JP SORT
:load HL with the address pointer to print'finished
iprint the file pointed ta by HL
'! :reset HL .1,
J\j,urnp to the" sort sub,routine
Prints the strinJ of characters pointed
to by the HL register
IN A, (0)
AND BOH JP Z, PRINT
LD A, (HL) OUT (i), A INC HL CP OFH
JP Z, Cl JP PRINT
icheck the seriaI status port
icheck output buffer i j urnp if not ready to print
:load A with a charaèter : output on the CRT ;increment the pointer icompare the output valu~ to OF the en~ of file control character
:jurnp if OF is encountered
Cl: RET
SÙBROUTINE STORES: Stores the inputted values from ~usic in
STORE:
, "
the Memory of the KPH control system
LD A, B
AND lOH JP NZ, BUF LD A, B
AND 08H JP NZ, BUF1 LD A, B
AND 02H JP NZ, LOC2 POP AB , CP 23H JP Z, INC
JP JlIN
iload A with the control register B
icheck bit 4 ijurnp if bit 4-= l i10ad A with the control register
;check bit 3 ;jurnp if bit 3 = l " ;1oad A with the control register
icheck bit l ;jurnp if bit 1,= 1, iretrieve reda-in value from Music
;compare to 23 Hex (*ASCII rep) 1 j urnp if A = 23 Hex = file boundary control charûcters to increment
:read in next character
, 1
i i , 1 l .1
II l
( , LOCl:
LOC2:
INC:,
INC2':
SORT:
SORT:
( \
-155-
SET l, B LD HL, SOOOJ<t
JP JlIN
POP AF PUSH AF PUSH AF CP 23H
JP z, INC2 POP AF CP l3H JP Z, BUF3 POP AF LD (HL), -A INC HL JP JlIN
PÜSR AF LD A, C
CP 5H
,JP Z, LOCl INC C POP AF JP JlIN
LI) A, D
CP 5
JP Z, FIN INC D POP AF POP AF JP JlIN
\
;set bit n ; load HL wi th the memory storage location address
i jump to JIIN', read in the nèxt character
;store read in value ;store read in value ; compare read in value to the control character (file boundary characters)
;jump if A = 23 Hex to INC2 ; pop the 'read in value ; compare to 13 Hex
;load ASCII value in memory ; increment pointer
;load À with the boundary co~rol character counter
i compare to S, (need 5 chaxacters in a rmV' before storing'; the data) <
; jump if have 5 characters ; incremerit the counter
; return to reading in from Music
i10ad A w1th the end of file control character counter
;nèed 5 end of file characters before terminating storage
; jurnp if have 5 to finis,p }\~ ; _~ncremen t the coun ter -\! i)' , ~
: ' , .
icontinue reading in value from Music
."
'Routine which sorts back the ASCII pairs !
in memory to give the Hex op code
LD (HL), FFH ; load FF wi th the end of -:--~file control character
".
\ l
" \
1 \ \ . l
1
f
i j " 1
r
1 1 f
,.
STRTl:
STRT:
. .;
NUM:
STRT2.i
, STRT3:
NUM1:
. .
1 -.
.. "
'.
1 !
-156-
LO DE, 5000H
LO DE, 5000
LO B, lOH LO A, 0
LO C, (HL)
PUSH AF LO A, C CP FF
. -
--JP Z, EN02 AND lO~ JP NZ, NUM LO A, C SUB 37 LD Ci A POP AF JP STRT2
CALL STRTS POP AF AOD AC OEC B PUSH AF LO 1\-,-~V~ __
-JP Z, ST~3" POP AF JP STRT2
POP AF, INe HL LO C, (HL) pusa AF LO A, C CP FFH JP Z, END2 AND lOH JP NZ, NUM LO A, C SUB 37H LO C, A POP AF JP STRT4
CALL STRTS POP AF
• U
,/
;reload the address character poin ter
; 10ad ,the addres's pointer
;load C with the first ASCII: l/~ ,
~, Of . ' ~
.---=,; check for -the end of ", .fi).e char acter
\
~',1t;lmp, to END2 if encountered , ; ~heck if is between 0 - 9 '
; jump if' it is between 0 ... ~ ;load A with ASCII value ; subtyact 37 ;reload
_ f.:..\ 1
.J
.; OP code val ue is between-A-F
;routine to mu1t~ply 1a1ue 16 times
. , ... ," . >' " ... ~
~
,7' '4. ,)
" " ./> ~
.' J- o
.'
-
, .1
",!,
, .
~
"
r 1 ! ': , ,
1 -
"} .
1 . ! i.
-"
6~ _ ... _ ... ~~-,.'" .-, ... -'''',"~i ............. ~_~ .... ;...~';1.~ .. """, ......
; 1
1
1
'f 1 'l
F
l ,
-151-
.STRT4 : ADD A, C LO (DE): INC HL
A :add first ~ ta second ~ ;store va1ue~ m~ory
INC DE JP STRTI
STRTS: LO A, C SUB 30H LO C, A RET
. END2: POP AF JP TMOOE
BUF3: SET 3, B POP AF JP JIIN
BUF1: SET 4, B JP JIIN , "
BUF: RES 3, B RES 4, B JP JIIN
~ A.3.4 Closed Loop Control Program
The closed loop control program, is based on using. a
proportional controller. Figure 3A2 presents a detailed .
flowchart illustrating the sequence of calculations used in
c~lculating Mi+l. Subroutines which ap~ear in previous -
appendices, are not re-listed in this section wh'en referreç1 to.
sec Timers
, Interrupts are inputs that the CPU examines at the
start of the execution of each instruction. These inputs
allow the CPU to react to asynchronous even ts in a more
efficïent manner than polling~ each device.
1 1 ! 1
j , 1 1
, ,1
1
! 1 , \
1 f j
,
Î' , 1
'1
1 J \ 1 1
i
! '1
1
\.
( FIGURE 3A2
l-
L;)
-158-
Control Equation Pro~ram Flowchart r3"""ct
~ c5D 1
~, ....
..
..
\ a
1
1 j
1 ~
1
l 1 l
1 • i
1
1 J ! :
. j l 1 !
1·
1 1
c
(
(
1
-159-
{,
Interrupts allow events such as alarms, power failures,
the passage of a certain amount of time and peripheral
devices to get the immediate attention of the ~PU.
The" Z'-80 checks the status of the INTRP system at the
end of each instruction cycle. If an interrupt i5 active 1
and enabled, then the response is as follow5
1. The CPU disables the interrupt system by clearing
lFFl, lFFf;
2. The CPU executes a special ,interrupt acknowledge cycle,
so that the interrupt response ~9~~r can be placed on
the DATA bus. /
The SCC provides 5 independent interval timerR. The
timers are selectively eriabled for use or dipabled by bits • 1
'of the interrupt mask port 03H.
E'ach timer is ass'igned a SCC output port whlch may
be loaded w~th a one byte delay count. After initial \ 1
loading, tHe delay coun t (i-!:L/derremen ted once every 64 l.I l '. ))
seconds.
MAIN PROGRAM SEQUENCE:
SEQUE: '
, ,
\.
Controls the sequencing of the injection'
molding process phases.
ORG 5200
LD HL, 5708 LD (HL), 57
INC HL
. ~.
i** initialization of pro gram area
iload pointer location ; load the RETRV address
sign file pointer ; increment HL
1 1 J
. i 1
i
!
1 1-
1 i
, . , , ,
"
lI
( "
<-
"
.,
I-I
-160-
LO (HL), 51
'INC HL LO (HL), SB
INC HL LO (HL) 1 00
INC HL INC HL INC HL INC HL INC (HL) LO HL, 5116
LO (HL), 0 LO HL, 5715 LO (HL), FF LO HL, 5750 LO (HL), 0
LO HL, 5BOO LO A, (5717)
LD (HL), A
LD HL, 2000
LO OE, 2200 LD BC, 2300
LD (HL)
LD A, 0 LD (OE), A
LO (BC), A
INC HL INC OE INC BC EXX
LO A, 0 OUT (OB), A CALL ERRREF IMO CALL CLE~
i load the RETRV addres s ' . sign file pointer
iload the RETRV2 address Mi +l file pointer
iload the RETRV2 address Mi+l.file pointer ~
;zero program counter iset values for the ERR ref subroutine
; load E sign = + ve o
iload A with Mo value
i load M val ue in memory o 1
; load" REAL value file pointer
;load Error file pointer ;load set'point file pointer
; set REAL valueo = 0
i set Error = 0 o ; set set point = 0
o ;increment ,file pointers ;increment file pointers iincrement file point~rs istore pointer values in the prime register~
;null the servovalve icalculate ERR max iset mode 0 of operation iclear the interrupt request l;ines
\
....
L 1 1 ! ! '
, 1 1
1 J
1 , ~
l
1 1
1 1
, 1
_J
(
""
CALL MeRON
'CALL LS3
1 1
1
SUBROUTINE CONTROL~
CALL S50N
Lo HL, 5717 '
Lo A, (HL) -
CAtL SERVO
CALL CONTROJ.,
CALL CLEAR
Lo C, D CALL HOLO
CALL CLEAR
LO A, FF OUT (OB), A CALL MCRON
JP r-tONITOR
: set machine to the normal mode
:monitor mold, carriage position,returns when both are closed
jswitch to computer control, energize solenoids 5, 8 ,
joutput M values to the serv8valve 0
joutput M values to the serv8v-alve 0
;output M values ta the serv8va 1 ve
; jump to the CONTROLl subrQutine to control the injection phase of the process
iclear the interrupt request lïnes
itimes the holding phase of the process
iclear the interrupt ' request lines
i set the back pre-ss-u-re----
i j ump back ta the machine circuitry .
i j ump to the moni tor program on the sec
' ...... p
Controis the injection phase of the
CONTROLl:
LP:
molding process.
CALL CLEAR
CALL T2 El
Lo A, AO
Lo HL, 570F lj CP (HL)
JP NZ, LP Dl RET
jclears the interrupt request Unes ;activ~te timer 2 ienable the timer (
: load A wi th timer loop counter
;load timer counter address jcompare tirner counter ta program counter = AD
j jump if not equal:disable the timer
Q ,
1 1 1 l ,
.1
1
l
1 1 j.
j 1
J .. j 1 J
l
"
C,'
'.
/f
/ 1
)
..
..
SERVloC'E ROUTINE.T5:
T5:
~ .' .. - 1" r1 ~ ~ .., *",'("' "
-162-
@
Is the s~rvice routine for timer 5
whi~h i6 ~sed during the HOLO portion
of the process. Works in conjunction
with subroutine Time, 80 + HOL'
INC 0 CALL TIME 80
RET!'
~increment counter ~acttvate T5 time = 16.32 ms
SERVICE ROUT.INE T2:, Is the s,ervice routine for timer 2 o~.
SBRVT2:
LP:
. ,
the'SCC •. This service routine when
cjlled initiates an additional time delay
of 16.32 Sec using timer '3 on the SCC
titner system.
Dl PUSH AF
PUSH HL
CALL T3 LO B, 1
LO A, B CP 0 JP NZ, Lp
Dl LO HL, 570F LO ,C, (HL) INC C ~O (HL), C
. ~XX
CALL STORE
CALL CONTROL
EXX CALL Tt' POP HL
~disabl~ the interrupts istote pointers and.
, counters , , i store pointers and
counters iactivate timer 3 ~set control register
~continue looping while B = l
idisable interrupts
;C = timer counter iincrement timer counter ireload counter in 570F ~load HL, B, C, DE with their appropriate file
, .. pointers iget the REAL time value and store in HL file
icalculate ~€ and ~i+l
istore pointers BC, HL, DE iinitialize timer 2 ireset pointer and program counters
,
, { '1 , ) ) ,
1 " ,
, .
1
Î
1
-- ~- ... ~ - ~, ~" . - - - .. -~ ~- -- " - , ~ ... ,1 . . -\
~ , J.
" ~ 1 -
~ l ( '"
.j , 1 ,
pOP AF , !
~l- :el'iable in terrupts~ RETI 1
* SUBROUTINE CONTROL EQUl\TION:
Calculates 1::.8 ::: e: i+1 - e. where ~ 1- ' -
8 = s~t point - real-tirne value 0.
J:;ONTROL: CALL ERROR :calçulate e: i +l . ' 1
0' ,
t PUSH HL '; store real, value pointer ,
PUSH BC 4 istore set point pointer . ' PUSH DE i s,tore error po~nter , POP DE iPOp the e'rror poinj:er li
Ll\' A, '(DE) iload A with Ei+l j
, '" l PUSH AF " sto'rè' 1
~
e: i +1 i ' 1
DEC DE
L LD A, (DE) ; lqjâd A'with e:.c value ~ \
LD HL, 5700 LD (HL) , A ;"5700 containg' E. valùe 1
~ t POP AF ireload e:'+l
.; .. ~ o'J ~ ..
AND A iclear carry SUB (HL>' i1::.E = Ei+l -, €.
~
LD (5701), A i store 6.E value in'5701 .'
JP C, NEG iJump if E. > Ei +1 ~ " • !.. LD A, 0 i€i+1'> E . 1::.€ is positive
~'
LD (5704) , A iload sign fJ 1 . l JP CHOICE !
! 1
NEG: LD A;' 1 i1::.E is -ve " 1 l
LD (5i04), A ~ i load sign ./' 1 1 1
CHOICE: INC DE iDE points to ,Ei+1 PUSH DE ; store E i+'''l b
" -jl pointer
\ P~BC PUSH HL ,. CALL RETRV iload HL with e: i sign'file
LD D, (HL) iload Ë i +1 sign in 0
DEC HL LD E, (HL) :load e:. sign in E
~
POP HL ireset register ~ POP BC tI'
.- LD A, E iA = sign E. ( ------ ~ ,
____________________ 1.
-~ -- -- -------
1 __ ~ ____ J
· ... ,' -"1/ '
Î'~ 1ft ,..,,1, ... ' .... ~«~~\4tt.~~~ .1"Ui,~'f~~!1;;'1 .... ..,. <I,!<,.~.I' ~---~..(.:;P''X~~';.~.~~1\r..'"';;..!'~.I~''lI.J;U~f .. ~f*~V'Ir'' ... I.''l''lt'-".~-l~'11 ........ rr~\y "::1' ! _," r -{ ..... ~~,'~.,.~J:'(;.~., ~ ',:,"-'l'-"'f'r-tr7-<·I7f!' "'h, ~ .... ~~J';~ ..
""c
,
t t i 1 !
,~. '
/
~.
o"~
SAME:
, '
CHANGEl:
-164-
~DD JP N.2 -" SAME
LO A, E
~p 01
JP NZ, OIFFI \.". -
LO, A D
AND 01
JP NZ, OIFF2
LD A (5704) AND 01 ' JP Z, OUT
LD A, (5701 ) CPL INC A LD (5?{)}J , A
(l'''~_
LD A, 1 LD (5704) , A JP OUT
LD A, (5}O4)
AND 01 .. I.j,-
JP NZ, CHANGE
,LD A, 1
" \.
LD (5704) , A JP OUT
LD A, (570.1)
CPL INC A
l "
;jump if both ~, + E'+l are neqative ~ 1
;reload~A with €. sign ~
;check it if E. is - ve J.
ivj ump ,i f E i i s :"'ve + E: i + l
is + ve iload A with Ëi+l sign icheck if E: i +1 is - ve
;jurnp if E: i +l is - ve E: i + ve
i10ad A with the ~€ sigh ;check if DE result was - ve ;jurnp if it'was + ve, here both €'+l' Ë. are + ve
J. ' J.
iload A with ~€ value T
;take 2's complement ;increment A ; re1,oad the 0 correct br:. value knowinq Ë.+
1, Ë. are + ve , -.). J.
but E: i i~ greater than Ei+l
result"'is - ve
;load the correct sign
,,0
i€i+l = Ei = both - ve, load J
~€ sign icheck if Ë, > Ë, 1 ). ~+
;E i +1 > E. ; but since both ). r
are - ve adjust' sign to - ve
; store the, ,sign
;E i > Ei+l both are - ve load A with ÂE
itake 2's complement ;inèreriient A .
.,~
. \ ~: ..
1 1 1
1
Î
DIFFl:
NEG2: ,
"
DIFF2 :
NEG3:
... •
OUT:
-165-:
LD ( 570 1) 1 ~ 1_.
LD A, 00 LD (570.4) 1 A JP OUT
LD A, (5704)
AND 01 JP NZ~ NEG
LD A, 0
LD (5704) 1 A JP OgT
LD A, '(5701)
CPL / ,j'.> $J;
INC A LD (5701) 1 A
LD A, 0 LD (5704) 1 A ïjp OUT
LD A, (5704)
AND 01 '
JP NZ, NEG3
LD A,l,
LD (5704), A JP OUT
LD A,' (5 701 )
CPL INC A LD (5701) 1 A LD A, 0 LD (5704) 1 A
CALL MPLT OUT (OB), A
,1
CALL INCREMENT
POP DE POP BC
\ "
;re1oad adjusted 6€ ;fix-the sign to + ve i store the sign ~
<
1 ,
;E i is - ve , €i+1 is + ~e i check 6 E: sign ijump if t:, > E:'+'1"
~\ ~
; E i +1 > E i i resul~ is + ve ;reload sign + ve
; E, > ~
E'+1 , ~
1
E i +1, Ei - ve, + ve
itake 2's complement iincrement A iieload the adj~sted !::.E: value
isiqn is + ve ;reload sign
, 1.
iE'+1 is - ve, E. i5 + ve ~ . -' ~
i check if E, --;.v E, +1 ,l. ~
; j urnp if E, -> E, + 1 ~ ~ 1 -
; E , < Ei4:1 siqn i5 - ve of .. ~
t.E
;19ad the correct sign
,+- -i E , >' E" l' V'e 1 ~ - 1.+
E; + ve ~
."
;reload the ad~ted !::.e ; load sign + ve
;ca1culates Mi+1 ioutput Mi +l to the servo-
valve ;increment the fUt pointers
1
.'
1
~ - ' .. -r --.~ _ ~ _ .... ~ __ ..... __ ~_ ... ~ .f'~ _~ _ ~~ _...........-..... _ .... _ ...... ->.._ ......... _ .... __ ~ .... ! ..... ~ ____ -...< _____ ... ~ ~ ____ .. _\. .. _ ~ ~ ..... _ .......... ______ ............... . ,
-\ 1
~
! '
! 1
1 ~.-i
1
.1 (
SUBO~E MULT; , ----
MULT:
)
NEGA: )
(
-166-.,
_POP HL INC H~
INC BC
, INC DE
RET
o
b iincrement REAL tirne file "pointer ,>
iincrement the set point' file pointer
iincrement the error·file poiI1:ter
Calculates th~ ,output of the controiler
to the s~rvovalve, Mi +1 d ~E * .G + ~i
AND A LD, A, (5710)'
L~ HL, 5707 ,. ,
SUB' (HL) , -. JP C, BIGGER
LD A, (5701)
LD HL, 5701 SUB (HL)
JP C, BIGG3
CALL CALC LD A, (5704) AND 01 , JP NZ', 'NEGA AND A ~
CALL RETRV2 LD A, (HL)
LD HL,' ~712 ADD ,(HL)
JP C, BIG2
JP LP2
INC HL'
LD (HL), A
RET
AND A CALL RETRV2
LD A, (HL)
;c~ear the carry flag iloa~ the rnaximufu error value
iload the address of error i+l
icalculate Emax - Ei +1 ;jurnp·if Ei +1 is greater
than Errmax ;reload the E.f:lr . max ;load the ~E address ;calculate E - ~E max ; jump i f ~ E > E
max ;calculate àE * G ; load M:. sign ;check if 6E is - ve'
';jump if negative ;clear the carry flag iload HL with the M, pointer,
1. iload M,
1. ;load ~E * G result address ; add M. + M:. * G
~
;jump if'result is greater than FF
,
iincrement M. pointer ~
istore the Mi +l valu~'
iclear carry iload HL with
;load Mi
,
M. pointer 1.
"
,
!
-1 ~ .~
1 Î
- i
J .. 1
1
\ 1
• j l ' , i
i
1 \
1
, .' .. , •
" .
' .. - -
•
~
, . ~.
'.
c'
LP2: 4 .. '
~IGGER:
'. <\1
LPl: . -
NEG4;
~
. ,-167-
LD HL, 5712 SUB' (HL) ';
JP NC, LP2
LD A, O'
CALL RETRV2 JP LP
LD A, (5706)
AND {l1 JP NZ, NEG LD A, FF
CALL RETRV2 'INe HL • ~D (HL)., A
RET
'LD A, 0
.~P LP,l .. , LD A, ;PF 1
J1? LP2
• LD"A, (57.(N) " AND 01 ,JP NZ, NEG'4
,.LD A', FF
JP LP2
Lr5;., 00
,.jp LP2
_ t ~ _,- __ ~ •
iMi - /jE
• G~ ijump if M, > tH:. * G
, :M i < /jE *~G ( esult
- ve, output zero)
i 10,ad. E i+l sign. ;che'C~ if - va
is
; j ump if - ve' iM i +
1 = open value 10'0%
;increm~nt pointer ;store Mi +1 value
:Mi +l =.zero close value
; 10ad M:. sian icheèl<. if _ove
. : j ump , if - ve iM, +'1 = 1.00% open
~ ..
;Mi +l = 0 closed
SUBROUTINE E~ROR ca!9ulates the val~e ~f-Ei+ll and stores the . value and sign of ~E in memory.
ERROR: AND A , . ," Lb A, (BC)
SUB (HL)
JP'C, NEG • PUSH BÇ.~
PUSH HL
, .,
;,clear the 'carry ~load A with'-the set point -value at i+l
-~~~'+l = set point i+1 -• ~ d
re'!l! value i+l ;jump if real > set p0int istore pointer istore pointer
. "
) .
1
\ -1
!
, j
1 '1 ..;
"
* ,
(
. ,
v
\
".
.,...
LP:
~ ~'-":r
NEG:
Q
SUBROUTINE STORE:
STORE:
'.
• l,
"
-168-
CALL RETRV
LD (HL) , 0
LD HL, 5706
LD (Ht),'OO
LD (DE), A
LD (5707) ,
POP HL POP BC
RET
CPL
INC A
PUSH BC PUSH HL CALL RETRV LD -<HL), l LD HL, 5706 LD (HL) , l JP LP
A
; load HL wi th error s~gn pointer address
;Ei+l is + ve, load a zero
i load in dununy location, 5706
istore Ei+l in memory
istore Ëi+l ~lso,in 5?07
;points to real value file 1Points to the set point file
..... , i E. is ... ::;"ve
~
; adjust E, ~
;store the ~ointer
istore sign = - ve
istore sign in 5706 = - ve
Stores the ADC converted value from
channel 2 infthe rnemory r~gister, HL
points to the real time' data file.
PUSH DE
PUSH BC
LD A, 2 LD DE, 5700
"CALL DATA POP Be . POP DE LD (HI;.) , A RET
istore E. file pointer 1~
istore set point file pointer
;load the channel address :load the dummy memory location
iread in real time value (
istore digital valu~
SERVICE ROUTINE T3: Is the service routine for timer 3 on
the sec interrupt system~
1
1 t
t- , •
, ,
,.. <-' ---- .
-169-
T3: LD B, 0 ;load flag
~ B - 0, set control
RETI
SUBROUTINE T2 INIT: Initializes timer '2 'on the SCC and sets
the time counter to 16.32 ms.
! -':' "
1
LD A, i 0 'OUT (02), A LD A, 12 OUT (d3), A LD A, FF
OUT (0.6), A RET
A3.5 Open LOOE Côntrol Program •
iset command register
;set mask register
iload timer counter = 16.32 ms 0
ioutput count
The open loop control program, Figure 3A3 was use~ to
~ record the data necessary to der ive th~ set point profiles
used for the closed loop study. Settipg the/ initial valve
openi~g, the prograrn monitors/stores the feedback sensor
signal (Channel 1 ADC) as the valve position remains
constant. To run the open loop program, the only change
that has to be made using the closed loop control program 1
is in the timer 2 service routine. Instead of 1ine "CALL •
CONTROL" the, subroutine OPEN would be called. ' The subroutine
OPEN records and increments the appropriate registers
during the cycle.
SUBROUTINE OPEN:
OPEN:
Is used to record open loop data and
increments the HL, BC and DE file
pointers.
LD A, (HL) iload A with the real time\ v~lue
..
V r~ -
1
1 1 ~
1 1 l 1 1
- .- ~ .. ~ ... _ ....... ___ ."l<~ ... ~~ ..... ..,_ .... __ ~._ .... __ ~_ ~ ____ .... __ ... __ ........ _~~~_,.~.,...... __ Jo ......... ~ .. " ......... _ ..... r --. ... ..-......... -......~ p "'~_ ........ _ .... ,-.,-, _ .. __ _,_~? .... ,...-., t .. , ................. ,,-tr~..,. ... ~ ""'-t-, .. '''".. __ ~.t.,t .1 n'~lf"""\"""""~""~lv! -'i"'" ~ .. ~
l'
t ! \,
1 f
1
1
1
1
! f ~ f
i-f ,
-170-
LD (BC) " A'
INC BC
INC HL
RET
o'
<"
istore the value in the set 'point profile file
i increment set point pointers
i increment pointer
real value •
1. . , \
,----------
, )
/, ,
i ,
1 1
l-
I '{
\ \ 1 i 1
1 ! 1 t
1 1 r
1
- - - _~ __ ~, ____ ~ .......... , p.,,,,_
-171-
,FIGURE! 3A3 !
,f
, .
•
- __ . ___ ------, --- 1-- ---
Open Loop PrQgram Flowchart
T2 SERVICE
1
.J
~;3S~~:CR
SET -~
,"'",,1: .
T5 serv1elt rout1nlt
, i i 1 1 , J
\ 1
, 1
1 J !
l
. \ -,
",
" ,
..,
,,'
.. -172-
APPENDIX 4
RECOMMENBAT-IONS
A4.1, Software
T,he softwar~ capabili ties of the KPH microprocessor
system can be upqra~ed in two ways, firstly by modifyinq t
~,
'the control strategy outlined in Section 5 and secondly,
.fby ~tilizing 'the MUSIC Translator Program developed in'
Appendix 3.
MUSIC Translator program
rhe computer proqram described in Appendix 3 can be
used 'to transfer i~formation from a file stored in the
McGill MUSIC System's memory to the KPH microprocessor
mj:mlory. PLM, a high level lanquaqe, allows, the user to
program complex mathematical relationships which could be
used 1n executing elaborate control schemes. A program,
written on the McGill MUSIC PLM compiler can be executed
on the McGill MUSIC system,to qenerate'a block of machine ''-.
code,-compatible with the Z-80 CPU based micr0processor
system. The MUSIC translator program controls the transfer
of a file from MUSIC ta the KPH memory. Similarly the same
o progr.am can be used ta transmit blocks of information or
data, in ~~xideçirnal representation from the KPH memory
ta a file stored in the MUSIC System. This would allow for .'
data processing, and manipulation using the facilities of a
more complex system. To initiate a system of this sort
o
1 f j
, 1
r'
" )
(
1.' 5
woula involve modifyihq' t~e proqram presented in Appendix' 3, l;J
• which was designed to receive a block of data and store it
" in a specifie a~ea-~ memory.
éontrol Strateqy
The control strategy~used 'in this study is based on a
simple proportional controller. The error signal calculated
is based on data from the present time i and pa st time i - l
points It has been shown that the set point profiles can
~<be non~ar i;; nature, with sharp changes in the slope
). . o~n". As outlined in Section 7 a predictive control
, strategy would lead to better control of the system. A
forcasting scheme would incorpora te data based on the past,
present and future trends of the set point profile. This
would allow the controller to a~just better for changes," in
the set point profile. Prior to undertaking any
modifications to the control strateqy, the,various transfer
functions relating the valve position ta the key process , ,
outputs have to be determined. Once this is done, only • 1
then could advances be made to de termine the optimal control
strategy. The methods outlined by Box and Jenkins (39)
and'MacG~egor (40) can be used aS,startinq points for
"developing more elaborate control strategies.
The simplest modification to the present control
strategy would be to use 12 bit resolution instead of 8 bit
which was used in recording and monitoring the feedb~ck ,... ,
ensor measurements. ?his would invol ve modifyi~q_ the
r "
,
~
1 J l 1
1 1 1
il
1 i -
o
-174-
con,trol programs to work in 12 bit mathematics. This would
mainly be us~ful for velocity control, where the ranqe of h r
the output signal' from the linear displacement transducer is
narrow. Thus, incr'easing the resolution (accuracy) could lead
to imp!oving the quality of control.
A. 4 . 2 Hardware
The system described in Section 4 for the modifi~tion
of the Danson Metalmec Injection MOlding machine can be 1
further upgraded. These suqgestions are made after testing
the machine and analyzing its response and performance.
1. ~ hydraulic accumulator can be incorporated into the
hydraulic system of the machine, before the servovalve.
This would further minimize any hydraulic line pressure
variations that occur while the material is being
injected.
2. The electronic circuit for conditioninq the signal from
3.
the linear displacement transducer, should be redesignéd
to provide an output ~ignal in the ranqe of 0 - 10 volts, :'l
l
thus increasinq the system resoluti9n.
To ~btain better control dUr~q the
the process, the proposed hYd}auli~ packing phase of
scheme in Fiqure 4A-I
might be used.' This system allows attemptinq to control
the flow of oit through the valve durinq packing., By
controlling the bypass valve, one can reduce the oil flow
throuqh the valve, and thus be able to manipulate the
<>
, 1 , .
-i75-
hydraulic rarn pressure and improve the qua-li tv of control ." tiI •
durinq the packing phase.
\
... Y, 1 !~
~
"
~
~
-.
~ .r
~ . r'_~_~ ___ "'.~~
A
1
i j
i 1 \ 1 1
1 t, ! 1 i 1
i ,1 i i i
1 - 1-,
1
1
' 1
1
!. ~
r--
?'
\ (
~ /
FIGURE 4Al Hydraulic System Modifications
4,'/ . ] Il (!
'0
i SERVOVALVE ..... ...
'"
/ &.!J
SOLENOID VALVE >,
.... b L..J c
ACCUMULATOR
1 • ./
HIGH PRESSURE LINE
".
INJECTI,ON RAM
\r.
,,-.....
,
~
-, ~--,,~ ...... ~ ...... ---~
1 ..... -.J 0'1 1
;.
i , ,
1 . ,
<, -177- 1 .: \ î ~
( 7
, j
t ) ., ~
APPENDIX ,
5 . j O' ,.
DATA 1
.rI ,p
'\
\ , .. 1 ,(-, . 1 >,
\
" , " , : .... ~~ r
i_) -"
~ 1 ~ "l- i '
,
1 l 1
1 ... .;,
, 0
0" 1 1 r-I
~ 1
l '( 1. 1
1
• .J', ~
t. ... .. é
• 1
1
~ ! 0
0
\ l' '0 "
" 0, (~ . ,
( 1 -10
• 1 " ,,'
r .. o.
• . -
_. ~ - ..;, ~ --~ ..... - - .. - ',> --~-~ ......... ~ . .. <\"';'
/ _. a
-< CO ~ --'--
• "
\L .. \ ~ ,
.. -: ·~t!\~t ,,!:!'"'l', ...... "'~ ~""""""",""L,v41"~~~"'",U~"l'M...,,..... r--'Y '1:Y~...., ~ , .' -<"~.. • *. ,.. ,-, ~ --.~. '"_ .. ;~~~'" ~-, --'-,-.,- .,.. ..... ~ - ..... ., ,-. -, '. ' "'~"", ~ - -, " " " "'-,' ~ , /
-179- i 1
! JI 1 ( • ,
, -Tirne [00Een LOOE 1 Cavit::i Pressure vs Data
,4 1
0 psi Tirne Valve 13% <14% 56% 100% 31% 62% Sec Openinq:
0 0 0 0 ,0 0 0 0
( l .125 0 0 52 52 0 52 \
2 .250 0 156 ,260 208 0 260 "
3 .375 0 ,260 416 700 52 676
4 .500 0, 260 1404 2236 104 2132 1 • 1 \
5 .625 0 1560 2132 1976 '260 1716 ~
6 .150 104 258'0 2132 1716 - 468 1508
7 .875 260 2392' ,1768 1456 2132 1508
B 1.000 312 2444 1612 1352 2184 1456 '~f'
9 312 1924 1404 ' 1348, 2184 1300
10 468 130q 1196 1092 2:340 988
Il 572 1092 1144 780 1820 676
12 676 1040 1092 468 161'2 520 1:
13 676 978 884 468 1456 468
14 1300 780 624 312 1092 468 /'
15 1820 468 416 104 988 260
16 2184 260 312 0 832 0
17 2704 260 156 0 780 0 J
"-18 2704 156
~ 52 0 468 , 0
19 2600 ;6 0 0 156 0 '. 1
J •
\ ( l
i
(
,-180-
f
Cavity Pressure vs Time, Set Point Profiles
Time Sec
0 0
1 .125
2 -:-250
3 .375
4 . ~5
5
6
7
8
9
1,0 ,
Il
12-
13 +
. .
'psi
Set Point 62%
0
60.9
243.6
365.5 Il"'
487.3
609
2132
2375
207.2
..
•
Set Point 13%
0
0
0
0
0
0
0
0
0
0
0
0
6p~9
60.9
• _ ..... • r_ ~ ...... "H ~""""'",E~ ...... '-h~~" """
" . 1\
Set Point B
0
0
0
0
0
609
1132
2375,
2071 .. ,
"
..
i
~
! , !
1 " 1 •
J
, . '
1
1
1 ,
1
1 1
1· i i ! 1 1 1
~.
1 1 "
1
'ir r ''::' .. ~ 0 . , ' "~
.. " .
~ ~ • 1/1' 1 . -, ,
1 ' - , li
-181-" "
( Open Loop Cavity Pressure vs .T ime ~ -' 62% Valve Opening ,
'" -. Reproducibi'ii ty trials, psi "
.Time Trial: 1 2, 3 4 5 Sec
, '" \.
.... , ('
0 . 0 , 0 o " - . 0 0 ,(/) Q 1
.;..' 1 .125 60.9 < '60.9" 60.9 60.9' .'
60.9
2 .250 182.7 182.7 182.7 182.7 182~7 , - " <
3 .375 304.6 30,4 :6 304 '.6 304.6 304.60 ,
,
4 .500 426.4' 426.4 426.4 426.4 426.4 -5 548.2 791. 9 548.2 852.8 548
2132.1 ' 1
" 6 -21<82.1 2071. 2 2071.2 2071.2 i
2132 ... 1 2375 1
7 ., 2132.! 2193 2314.8 l 8 1644.7 1705.7
1 2010:\ 1583.8 ,201.0 1 1
, . l '" " i r
rf - -~~J Reproducibi~~ty-tr~als, psi
Time Trial: o 6 7 8 9 ,,10 ~ l Sec- , 1
-, 1 Q , 0 0 , 0 0 0, 0 0 1
!
l .125 60.9 6'0.9 60.9 60:9 60.9 ~ j
J
2 .250 18-2.7 182. :'] 243.7 ;L82.7 182.7 i i , 1
'304.6 ~ 3 .375 304'. G 304.6· '365.5 304.6 . 487.3":' 4 .500 '426.4 426.4 , 426.4 426.4 ..
5 548 548 548 54'8 791.9 , . -6 2071. 2 2010 1949.4 2071.2 2071. 2
,
7 2314 2253 2 07J.. 2 ~71.2 1888~ , 8 2910 2,010 1644.7
1 , . ~522.,9 'j
l
1- 1
~ ~ 1 ! 1 l 1 j 1
( f "
0
~ \
\ ,l> 1
\ -.
(
\
..
1
,-182-
,[ , , Open Loop Cavity Pre~sure vs Tirne, 62% Valve Openin9 (Con't)
----------------------~--------------~-----------------~ Reproducibility trials, psi
Tirne Trial: Il 12 13 14 15· Sec . ,
-:; ,
0 0 0 0 Q o '(/ 0 , l
, .125 '60.9 60.9 60.9 60.9 ~ 60.9
2 .250 182.7 o"A
182.7, 182.7 1'82.7 182.'7 3 ' .37.5 304.6 304.6 304.6 304.6 304.6
4 .500 365.5 426.4 426.4 426.4 (J "l f
426.4·, T •
5 487.3 548.3 670.1 791. 9 1548
6 ' 2071.2 2010.3 2132.1 ~ 2132.1 2132
7 2314.8 2071. 2 \ 1888.4 1888.~ 2253
,8 1888.4 f58~. ,8 d 1827
li 1
: '
.'
. ~ ~'; .
Q
• ,
,
~1 1 .~, '~_'~l~' .-'\1 ... '1,
... -183-
...
p&en Lecp Ca.gity· Pre'ssure vs Time, 62% Valve Opening (Con't) - ~ ~
o 1
2,
3 ..
4
5d'
6
7
8
. ,
"
Tim~ "l'rial: Sec
o .125
, .
'.
, ,
o ,
Reproducibilit-y trials, 'psi '''' , ~
21' 22 23 , 24 25
o '52 '
104"
312
468
676
2028
'1664
u
J'0-
o 6 •
52
, 168
365 .1
468 1
634
213>2
.r 2235
1612
,
"
o 52
260
312
374
676
2132
1612
/
o 52'
260
o 52
260
312 <> 312
468 446
634 572
2132 ,1924
1716. 2340
Il
1 i
" -1
- ,
\ .. i 1
-,1
"
Q
, !
1.
.. <:,.. ~
i • " ( ) . .' 0
. -184-
, ,1
( .. Open Loop Cavity Pressure-rime Data, 62% Valve Opening
r: 'Trial PeaJé Pressur~[ 2si <;> ..:.
'1. 2132 .--. . 2 ,2193 $1 1
3 e 2314
• 4 ' ' 2132
5 2375, l ' 0
6 2314
~ .-7 J, 2340
B 2132 ,
.. 9 2132
10 2235'
~28 . .
Il .~ 12 2132
13, . 2253
14 2071
15 2,071 " 16 2071
17 2314
18. 2071 , 19 2132'
20 2132 . 21 2253
~" 22 2314
23 2314 ) , . , 24 " . 2375
25 r 2375
Average: 2215.4
.\.
" ,
/ (
".
,
1),
...
r:.
".
.j
/' "/
/
J
...
•
~ l 1
~ ~
!
J ,
1 1 • • 1 1
1
, l , 1
"j
,
, ï l~ \
1 . l 1 J
i 1
d, '1 \:
1 ..
i
• '-, ~ . ,~ , .'
.- < , ' .. SI., ""l' , ... ' • i ~."'f,I.," • "''',~ >-' v . ' - ~ , ,. ~
-f , • 1 ... "\. ......... ~ .... f
-185- " 1 _' f<-
I .. ,
.'1 . ~ Il '\ "-
~ ~osed ,
( 1 , !' 1 . , l LOOE Cav.i ty Pressure-Time bata, 6'"2% °Een LooE ,
G ,
Set Point ProfJ:.le G = 16
/ ,
Trial Peak Pressure, psi
;L 2375 "
~ 2253 . 2314
0'
3 ';é • ,
~~ ,
-----, . 2253
5 , .' 2314 1 , - ." l.
6 .23J.4 /'1 , 7 237~ !
a a 2436 1
9 ,2375 ;
j ,.. 10 2436 .. II 2253 -,~
1
12 231.5, j 0
,tif'''t 13 2436 • ' ; ;';iJ ,
t'ji:.Ç~
2436 ",-,jY •
~ 1 14 T
15 2436 " {i~: 1 . l' . " cf
1 1:6 2436
, .. ' . A (
17 2253 1 1 l
d 1 ,
18 ?497 l < d
4
19 '24.36
20 2436 \
l
21 2436 l,
1 ,
i ,
Average: 2375 .. • 1 -, 1 ,. l
j 1
" l:- 11 1 1
1 i
" ) ~
. '\ (-"
\ 1
Il \'0 - (], . f.
'" , , ,
./
~
,t>
-- \ l' ,
/"
f"
,,~. '. ~
Closed Locp ,Cavity,p~essure vs Tirne Data, 62% Open,Loop Set Point Profile
, .
~r
l
2
3
4
, ..... 5
6
7
8
. Time Sec
0
.125
Set Point Profile
0
60.9
.750 ~ 243.6
.375 365.5
.5 487.3
.625 609.
.75 2132
Peak 2375 Press
1.0 20712
~
" ,
G = 16' G = OS
0 .. 0 1
60.9 60.9
182.7 182.7
365 365
487 487
670 609 t'
2132 2132
2132 2375
1644 2010'
L Err2 (p~i2): ,until the peak
psi
Err16
0
0
60.9
0
0
60.9
0
0 ,
\ b 243.6
\ r 7417
"
percent Err: ' .07
"";y ..
Erros
0
.. 60.9
0
- a
0
0
0'
60.9
.. M, at G~= os
'AO
·AO "
AS
AO
:1\0 ''1
AO
AA
AA
AP.
AF
3.?X'10 3 .... ,
li)
.06
G = 96
,'0
60:.9 j
3Jf4·.5
426
54.8
E~r96
0 .. o It
6~. 9
60.g.
60.9'
~
M, ~96
AO·
AO
40
40 ..
40
1157,~D 2314 ~ 182 0
2436 60.9 CO
, 22'S3 i82 60
3"4x10 S'
.933
...
--~
.. ,.- ~,
..,.
. ,
' . .. .
, 1 1-' ID 0'1 1
"
~ .c
0
'Ir
, . "
-- ....... ::-'~ ...,. '-~ "'" ~~
, ' "
, . ( "
.t:I
1
.j o
.P
~--' _.--~--~------------~<----------------.. ------..
-,
VL
"',
~
( . .
'\
î Closed Loop Linèar Set Point Profile
\
Time Set Sec Point
0 -0 0
1 .125 6.45
2 .250 6.1~
3 .375 5.4
4 .5 5,_ 01
5 4.37
6 3.97
7 3.5
8 3.17
9 2.69
10 2.37
Il 2.05
12 2.2
13 2.13
-188-
. Disp1acement Time Data, 62% Open Loop
cm
G = 96
0
6.53
5.8
5.17
4.77
4.3
3.97
3.6
3.17
2.69 . 2.37
2.13
2.13
G = 96 o
G = 16
D-
6.6
6.13
5.33
4.77
4.3 ~
3.97
3.6
3.17
2)91
.2.37
2.13
2.05
..
G = 16
r--",\
~ 1 , ;
l
.1 ~,
l !
-'
J1 .J
" ~ , ..
-189-
r "" ,Closed LooE Linear Displacement vs Time Data, Set Point
1 Profile B
,.-----
cm
Time Set G = 96 G = 16 Err96 E'rr 16
Sec Point B
a
0 0 0 0 o : 0 0
1 .125 6.45 6.4 6.4 .05 .05 ':0
2 .2"50 6.13 5.5 5.5 .63 .63
" 3 .375 5.4 5.2 5.3 .2 .1
4 .5 5.1 4.85 4.85 .25, .25
:5 t
5· 4.85 4.5 .15 .5
6 4.9 4.7 4.4 .2 .5 ------J
<--. 7 4.7 4.5 4.3 ~2 .4
8 4.6 4.4 4.1 .2 1.5 ~
9 3.2 4.1 3.9 .9 .7 "lJ 10 ,2.4. 3.3 3.4 .90 1.0
~ l: Err2: 2.26 2.86 cm 2
•
( : ".
" .. 1-
-190-,
\ .~
( Closed Loop Profile
Linear DisR,lacement vs
r '
cm , 1 Tirne Set G = 16 M. G =
Sec Point l.lf?
0 0 0 20
1 .125 6.45 6.45 20 6.29
2 .250 6.3 5.57 0 5.49
. 3 .. 37'5 5.41 5.25 50 5.25
4 .5 P '.09 4.85 40 4.93
5 .625 5.09 4.69 20 4.93 <> --
6 .75 5.09 ,4.61 10 4.93
7 '5.09 4.61 10 4. 9~
8 5.09 4.61 10 4.85 6
9 3.25 4.37 FF 4.45
10 2.37 3.89 FF 4.05 .-
11 2.29 ,
3.49 3.57
\. 12 2.29 3.01 3.17
" 13 2.13 2.69 2.69 , 14 2.13 2.5 2.37
0"
~ .
TLme[
160,
, l:
'\ " l'"
'l
SteE Chan9:e
..
M.-~160
20
0
0
0
0
0
0
0
0 .
FF
FF
FF
FF
, " 2
Err:
Err16
0
.56
.16
.24
.4
.48
.48
.48
1 .. 12
1.52
·5.0
\ \
\
, " ' 1
"j l
r ! 1 , , 1 ,
~;
,,' \ " ~ . .,
1 ,
Err160
.6
.64
.16
.16 .1
.16
.16
.16
.24
.8
1.68
.) . . '. -, 1
4.4 cm2
(
1 {
f
(
, l' ~ 1
J
\
~
p
, . _._~. _---.~~ .,... .. I~~~"'IM .. _ t-'" ... ,."'-~'" 'f<"' # """1" .... ,_ -x ..... ,..."o.: ___ -~j f~ ~ ~-. ~.. _ .. .,...~"...'f -V',. ...... '" " .... "· .... " ... ~_,,.r .... · ....... 'l"~....,I"""' ... _·...,...,-,.-S~·_ ~'" .~ ....
't
Close'd Loop Velocity vs Tirne, Step Change" Prqfile
Tirne Sec
0 0
1 .125
2 .250
3 . .375
4 .5
5
6
7
8
9 (J
10
11
12 . . :t\3
. '.
"
" .
.' •
J'
• ........ __ ~ _ .. -1 .. _.:'_,..;.....,.... __ .... -....--., .. l'''''' ...... _'''~~''O ..... ~,!i;:::..~---_.- ...... -_,._ ....... _~ __ ~ ......... __________ ...... _ .... -!--- ~ _l1li fI' 1I~,".''t;"
- - ~ -. - -- ~ -- - -- -- -~- --~~~ . "._-- -- ~~ - ---- ----~ - - -- __ ...... __ '1'_~ __________ ... ~
.~r "'1~"'" ,1< ....... t<'~-~ .... r "l~ ," , "'.- ....... ~J'-' 1"" • H_ 'fi r "'" .~ 1>.1 -1.. 4 ~ "/ ~_ ::.~ ~~ ..... y" ...... ~ ....... "'_ ........... ".._ ............ ~.-._.,....,.,.._W<" ".t .. ~~~"oM:""""-r",s'"" .. """".I>-'"
',';~ , ~
:' "
~ '---r j f -192- ,>
.' f ~ 1 >,-- .. .\I~ < / A
( ;, 1 "
~~ r
lI1ozz1e Pressure vs Time, 0:een LOOE Data
~ , '1 '7
~,/ ~. ·,ft P
Pressure, psi ç
l Time Valve 62% 13% 31% ~ Sec Opening:
1 1 i
0 .125 1692, 141 1'269 ·1 ..... , l
2679 •
1 .250 3807 846
J 2 .375 4230 1551 3102-,
" , 3 .500 4512 1833 3243
i 4 5922 1833 352'5
5 3948 2256 394?
) 6 , 2397 2535 4089
7" 2256 2679 5499 "
~ 0
2256 2679 5640 /
9 2115 2820 4512
1 10 1692 2820 3384
. "
Il 1269 3102 2961 " i E l t 1
r 12 987 3102 2820 r r . /-._-t 13 846 , 4230 2535 ..-'
~ 14 "'" 282 4794 2256 1 ... j
1
IS l' 0 5217 2115 1 \
16 JI 0 6063 1833 1 ./
j ;
'J. 1-, 17 ,j - 0 3666 1410
" 18 0 987 ,
19 <P 0 705
" , l \ -'
1_ . . "
. . \
~
'1 "
,
r 1
. 1 f ;, 1 1 f
~ ~
f' (. r ! i
f. î
)
,,, ... ~~' ·- ... ~!:!':t"';''''\~~''~~~''''''~.''''''''''f-'''''''7r~''''-.""~~",,,~''''''>'''''''~'P"''''-'''~''' ~~-J""'" "~"::''''~'<'<'''"'.''''''''''''''~<l'''''''t"~~''''~~'''''_''.'''''-'')''' • .,j.''''''"'''''' "''''''---'''~'''-I'''~''''''\f~~~~'''''''~ ''!:,."I , .... '\ .... ,:r", .... ~1~V ............... ::" .... 'fA ... r''"' '1'\" .......
-193-
Cf Nozz1,e Pressure Time, Maximum Settings - Normal Mode vs OperatfCm 1
\
Trial Peak Pressure (Reproducibi1ity trials) \ . 1 4423
2 4384 tt:l . 3 4423
4 0
4423
5 4384 . t ., 6 ~345
7 4384
8 4384
9 4345 . . 10 4340 , Il 426~ ~2, 4340
13 4345
14 :~ 43'40 ". 15 ,4423 '" 16 4423
17 4345 v
18 4268 "
i9 v
4306 '1' \ 20 4268
21 4268
22 4229
23 4306 ,'-
24 4268
25 4268
26 4229
l' 27 "
4229 r
~
_Average: 4328
(.' ,
,~ '1 'J
1 ~
1 l
'1
.f· !
1
1 l'
! , 1 !
1 ,1 , 1 1
~ 1
1 , r
" 1 ! .
(V';~):;4!·'~;'";;'~f~~~~)1~("+:;~~ .. ~, "'''!F~Y.~'' ';.1;1 1""'1Ift:'<"'J"~~~JIIM"'llf'tPrIPT"" .. "!"'~~1,.rw~~~"< ,..,& ... ~ 'l'o'tlllf\"J _-; .. "[.~'101<' ...... Y..~,,\ • ...,.l',,~ .. ~~_ ..,...,l>.J."'tI .... ~V'~\ ~- .... "J<~ 1-" ! --'.',; : r.t~""'" 1l~J-<l.r.'''': ,:,.-...ù t/~':.rV'.~,"I V ~"'rr '\.\..,.~~; : T)Jl"'" . ,t ....... >!-~ r
0
L194- ." '" , ,
Nozzle Pressure vs Time, 62% Valve °Eeninq ooen'L~~ "
Trial " (ReEroducibility trials) Peak Pressure
1 5543
....2 ... 5482 .;r, 1 • ... 3 " ~482
0
4 5482
5 " 5482 a-6 li 5482
7 5421 0 .. 8 5421
... ..
9 5482 \.
10 5482 . . ,
. Il .\ 5482
<
12 5421 f ,.
.. 13 5482
~
....... 14 .\
5421
15. 5543
16 5482
17 ,5482 . ~ C) 18 5482
19 5482
20 ·5482
21 .. 5482
22 5421
23 5604
24 5421 ;\ .. ~ -- 1 4 • ,25 5604
26 5604 '. :
27 5421 f ·f
\ 28 5421
Average: 5482 d
'--
( ~
0' P' .
• 0 ..
. ' ~~
-~- --~- - - - --~
\
, ,
11 -1 ,1
J , f
J
1 t 1 l,
1
j J ~ , j
~
1
1 j
1 1 , l 1 1 1 l 1
!
1
t
. ,~ , , -1' ~ ~.,."
. .__ _ ... ~ ~_ • ~ ....... ~_ '"" ~ .,",~ .,.. 7 ~ .. -,~,.,~ -~~ .. ~......... .- -- ~" ... , ..... , ,. ,
" -195- , \ 1
( : C10sed LooE Nozile Pressure <
t .
" . " l -62% Open Loop Set Point Profile , 1
L, î. 1" " ,
Trial Peak Pressure (G = 05) 1 1,
1 5482 • 1
\ 2 5482- • . 3 55'43
4 5482 .5 5543
.Jo. ,
6 5543 ~ \ "-
·7 5360
8 5543 0') 9 5421
• 10 5482 6
"11 5482 • ~
,12 5543 'j
13 5482
14 5482
15 5482
- '- . ') 16 5482 , c ,
17 -5543 \ . 18 5482 ....
J>- i 19 50182 1
1
" 20 5482 .- 1 21 5543 t 22
, 5238 "" ~
23 5360 , 24 5543
0
25 5543 {J
S543 ,
26
27 5482 \ •
AveJ:;age: 5486 . , ' ..... ' ,
\ ,
(- " Q Ij • •
1 1
~
1 " '"' ~ "' ~ -~
_. ~ ... ~ -< .- --_ .. ........, ~-.. ~ .................. ~ -~ ... ~ ~ -
"'"' ("
, i •
1 1 1
(J~ . ~ -196- l , 1 1
1 1
<.. .......
CIQsed Loop Nozzle Pressure vs Time Data! 62% ~alve" .. , 'Oeenin2 Set Point Profile ,. 7
"
Pressure, psi
Tirne Set Point G =' OS Err05 Mi at G = 96 Err
96 "" sec Profile G = 05
a 0' ' ,
0 a 0 0 AO 0
1 .125 609 609 0 AO 609 1'()
2 :250 23,75 1827 548 foio.l
BE 2436 60.9 , ,)
3 .375 3350 3472 122 AS 31r06 ,. 0
• 4 .5 3898 3959 61 AA 3959 852
" 5 ,- 40.&1 4081 0 AA 3898 ~_c!~ '-6-09 ,
1
6 4203 4203 0 AS 4142 852 1.
/
7 4325 4264 61 AA 3411 121 ,
• 8 4446 4386 60 AS 3167 60.9, , J
9 4568 5117 o 549 AS 4568 60.9 l J
"-j
10 5360 5238 122 4629 1035 l
0/ l
Il - 5604 5421 182 5482 60.9 j ..... l 12 310f\ 3533 i
1 ,1 , , L , '. i
" 1
Err < ~.rrg Il 1
g = 05 = 96
t)<
\ 1 l
\ '1' ,
... ,
( , --_//".
• iii
1 J '
_J .,.
v" .... '"t' \ . , - .. ' " ..... .. , . ~ -198-
,]
1 , ,1 1
'" C1'Osed LOO;e Nozzle Pressure vs Time Data, Set Point Profile B - • ~ •
t?
t
Time Set G = 48 Err48 M.' G = 16 Err lii M. Sec Point 148 1 16
B
O' 0 0 0 0 20' 0 0 '20
1 .125 243 0 243 8~% O' 243 • 60 ~ 2 .250 1340 1096 243 \ 75%- 974 365 30
\. "
ç.. 2071 ; j
3 .375 1279 791 0 9,13 365 30 , i
'{ ; 1
4 .5 1S83 2558 974 a 1218 365 30 \ \.
5 1705 1949 ..
243 10~ 1401 3,04 20
6 1705 1705 0 100 1522 ,182 3~
~6 ~
/. 7 1766 0 100 1888 121 60 . ,
l!\ " 8 1827 1827 0' 't 100 2071 243 80
"" , , . J
9 3898 4~~4 365 0 3533 365 60 ~-, -. i
10 4690 3533 1157 100' ,3,837 852 9F -; , v,'
j b
Il 5360 3533 1827 100 4446 913 CF
12 5604 4751- 852 100 .- 475\ 974 FF
13 4568 4873 0 4446
~ ; . , ------------- . ~ '1
Err2 .. 2, 7.2xl0 6 3.3x10 6 I: (pSl. : , 1 J ,
l, 1
-, ·1 . , 0
,
. ." i ,
-,
---- .. . .'
"
--- -- - -.., .- -
Il ~ _ A ~ ':~.; .~ ~ t._ 1,.." ; .\"~!,:;.' - p ", ~ ,-, ~,
'"-
J () " , ,il
/ .,
t ;f
, 1 -199- ,~
a Hydraulic Time,
, Pressure vs Qpen Loop Delti'\
"" " a
.; psi \> Time Valve 13% 62% 02% 62% 62% 152%
Se~ Openin9': . •
0 0 /) 1) 0 () , 0 0 .. 1 .12\ 37.4 65.52 46.8
, 37.4 '42.12 51.48
\ 2 .250 1 121 2q9.52 160 112 34h 355 \ ,
3 .375 159 449 .182 /1'-160 4fHi >, 482
" 't
11
J> 1 :
f' 4 .5 182 552.,2 552 lR~ 547 547 "
·5 191 570'.'96 1)06.2 472.fi 571) 561 '-.
" 6 248 580 580' 580 580 575 fT
7 ~ 2R5 585 5R9 589 590 585 <li>
8 299 599 599 59/) 599 599 '" .... ~, 9 304 613 6 :11,7 fi13
, ,. ro ·30,8 659 622.4
~ Il 332 739 ~.' ! ' . '0 • , ,12 346 790 10 . ~
l
1~ ; .
'351 847 _f
,9 1 i .. 1
14 356 1 " j I!'
'" , .. 1
15 . \ 356 1 ,. j
16- 361 î 17 ' 365 ~
/ , 1
t y ~'" '4
t ( 1
" .~.
( - t . ). ~ t ï l
~ .. . J ~
~
~ ~~, ..... -....~~ ~-.....!_ ... \o ...
. ( ..
"
. - o#'
- j
\
\
•
f .... '
l, , ~ " "
1 :
-200- 1.
,("~
LOOE H~drau~:I~ C10sed Pressure vs Tiniè Data l 62 %' °Een LOOE Set poin"t Prof:i:le . '
. Tirne Set G = 96
P~ G = .a G = 16 Err96 Err 48 Err16 Seo ... Point
~-
0 0 o Ilf • • 0
,l, .125 42.12 42.12 1
"\2 , .250 3 4,6_;~ ~~ . -tr- 285 "~·l1-' ." ..
/3 .375 4-8~~ ..• ~' 38)' 1.11 ...
-, 4 .5 5~ 7.56 421 '\ 5 570 510
6 580 636
7 590 496
8 "
600 542
9 617 664
10 636 533
Il 72~ 687 J li
12 748 739
13 823
.
'\ 0" 0 .. 46.8 46.8'
365 341
486 435
5fiO 599
613 599'
472 617
500 627
491 608
505 636
547 711
673 720
767 8'33
~ 2 ( , .2)1 "Err pSl.!:
)
0
o .
60 •. 8,
_112 , "_
126
60.8
56
94
58
46
93
28
9.3
159 .."
6.25xl0 4
0 0
4.68 4.68
18c.72 4.6?
0 46.8
23.4 50
42.12 28 ~)
107 37
93.6 32
42.12 , 9.3.6
112 18.72
719 84.24
46 0
18.72 84.24
4.6xl0 4 2 3 10 4 . ~ .
~rrg = 10 < Errg = 48 < Errg = 96
1-J 1 1 i i
)'~ / , '
1
; <l,
1
t ' . ,
1 fi l 1 , , ~ \ "
l 1
r
- - - - -- ~ -- _._----
, " . '1 ~ ... ' - .. ~ ~ ~~ -... ~ ."..~~ - '<""""'. ~~ ..,.... _\>' .. - .. 'llIr'>:.. 'rI" ~.'<'tI "~ -,
1 ~ . . , ,
() ; - 0
-201-,
.. .,
1 {
'\.. . • C10sed LooE H::::drau1ic Pressure Time'Data t 62% Valve vs Opening, Set Point P,rofi1e C10'sed Loop ,
~ ~
. , \ 1 l , .
psi
1 ./
Time' Set Point G = 96 , Sec Profile .~ 1 ,
& 1 , '",-- 0 ". 0 r) 0 l
1 1 .125 46.8 42.12 '1
l' 2 .~50 126 126 1 ~ 'v Ir 3 .375 168 215 , , 4 .5 196 266 ~ 1 5 " 224 294 0 -~
6 , 224 379 ~ ~I
.P '\" "
7 224 425 Î "
8 / 224 25f '~
.' \. /- J 9
~~ 266 355 CI -;: -, 322'
j
_ 10 374 ~7 1.
Il 374 369 ,,~1
12 393 491" j 13 450 463 C>"
/
14 _ 486 524
15 528 533 ~ 16 594 585 .. 0 , (\ 17 600 533 .~
,:j .' 18 600 542 t~ .. ~
19 600 \617 ',!
Il 't , .~ '20 600 590 -li
21 600 57.0 .. l ..
. 1 1 22 600 59U , 23 636 823
24 692 790
( ... ' \ 0"
1
\ -