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KNURLING ON CNCLATHES

___________________ 275

Depth and Feadrate

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274 8 Man-MacliincInterface

() (3) (4)

Machine

Auto Prog.//I

EmergencyStop ON

Current Coordinate

V 246.000z 000.000U 000.000w -40.100

W \V 10 100(5) (7)

Fie. 8-2 Typical machine status and NC parameters display area

Machine

Program

Panmeter

Tool

Service

2. Rapid Override button, by using this button, rapid Iced can beadjusted in scale to 10%,509r,aiullOO%.

3. Feed override switch: by using this switch, the commandedfeedrate can be adjusted from 10% to 150%.

4. Spindle speed override switch: using this switch, the commandedspindle speed can be adjusted from 50% lo 150* J&.

5. Spindle handling buttons: these buttons consist of the spindle start button, the spindle stop button, rotation direction selection button,and the spindle orientation button, inverse. These buttons are usedin MD1 mode.

6. Cycle Start button: This button is used for starting (he auto-execution or resuming the execution of a part program during feedhold stale.

7. Feed Hold button: This button is used for temporarily stopping theaxis movement in automatic machining. When (he button is

pushed, the spindle continues to rotate. If any axis of the machinetool is moving, that axis is stopped after deceleration.

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ControlFeatures

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I :- ::..[':,..-.l:ii;.'.r-.i.\- |..i., -i:-r,'i::-:' thslyricalspMificalitinsi.l a CSC Veiliral W.ijiria'jijHorinrau] tarin; null i-. |i:--i11........her C"NC" nmdiiiie.li (",...,,I ;1r.VfV/.ifi'r.-'WalMurtminjfCfr aFr TtKspcc-closcly resemble a CNChoriAxila] machining ccnlcr,but iftcacions arc sidebv side in Iwo columnsmictly far can-it .kv li.i.e trs .mildillLl^lLLCS. titriL"I.Ll l>. allun/i'llla! Iti1icn: r HLH NT liny ami[.jn..in ill"'.:..-.Ilicc .-. rv.nIhe m.i.liirie ^ih' lvn^|.|ini;iiy ]'UI]>.^ivtHi(nii' ..|vr. Ii.'n*. mainlyknirtjiy hnreh. f-.u lluirciK.nl . lhe rcii^h " lhe.j'iiiJk :- LViunkJ Ka .|vuiully J LMIMIL'I]IJUIII. An mire: [>| IILM]iL'iiciits n an JUS [uiiJk-i in rlw/. siih, L-alk-Jv.-iiii;il.L- ii.iiu. mainlytechnical in

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8.2 Sinicturc of ihcMMI System

277

2. Communications interface: This carries out communication anddata exchange with the NCK and PLC. It manages the services for sending the data required hy tile user to the MMI for display.

3. File management: This provides the services for managing foldersand files, such as copying, saving, deleting, and changing part programs and PLC programs.

4. Alarm: This displays alarm and error messages from the machine,PLC. and MMC in the alarm window. It manages the history anddisplays die help information.

5. Key input: This transmits the key input from soft keys, keyboard,and dialog boxes to the applications and the CNC system.

6. Screen Display: This handles the horizontal or vertical functionkey window that is shared by all applications and connects thefunction keys with particular applications. In addition, il providesthe interface for handling MMI soft keys.

7. Task manager: This executes the programs registered in the

application layer and provides the function for calling andswitching them. It registers the applications as a program list in atext Hie format mid executes the applications sequentially whenthe task manager begins. When die task manager is terminated, itterminates the applications in reverse order. The basic functionscan be summarized as follows.

Registering/terminating applications Delining the execution sequence for applications and initializing

them while booting up. Switching applications while they are executing. Monitoring system resources.

An MMI system based on PC hart!ware typically uses a PCoperating system as OS. MS Windows or Linux have both been used(recently, Windows embedded XP mid Windows CE have becomewidely used) However, these operating systems cannot provide thereal-lime capabilities required by a CNC system. Generally, an MMIsystem requires a non-real-time em 'iron men t, whereas an NCK system needs a real-time environment. Therefore, when the overallarchitecture of the CNC system is designed, techniques to overcomedie non-real-time capabilities of the PC operating system must beconsidered. One simple solution is lo use two operating systems,using a PC operating system (non-real-time OS) and a hard real timeOS lor the MMI and NCK systems, respectively. In Uiis case, it isvery important lo regard the execution of the MMI system as onespecific (ask in the NCK system.

In the MMI, various applications are executed based on the kerneland die user interface for editing a part program, which is one of thekey applications in MMI. In general, ihe muchine tool operator spends a lot of lime learning how lo generate a part program. So,from Ihe MMI designer's point of view, ihc MMI should be designedfor the MM I lo be able to provide die most efficient method for generating a part program. In the following sections. Ihc advantagesand disadvantages of various programming mediods will bediscussed. The design of mi efficient programming system will also

be addressed.

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TuiiLiii!:- nnjCjiiiiiliiie-MinliineMotions l&S

Operations

External CylindricalSubroutines

PLUNGE GRINDSTRAIGHT Axis: Q ( ) ( ) F_____; A six-step cycleliial moves ihe wheelinlo I he workpiece in2- or 3-axisdirections, each sep-arately: AirGrinding: Kuujjlmiji:a Suess-Relicl baekiilt':Rnc-t'inish Pass: FinalSr/ing and ZeroResell anil RapidRi'linn u, I lie initial position or nextprogrammedposition. See Figure7.21.PLUNGE GRINDANGULAR Ais: ( ) .( ) ( ) F :Pl unges thewheel mlo a \inrkpieee SLI.LILL- inlersecli iiii in amn-asis din-el ion.~:iulu:-
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Turning- and Grinding-MachincMotions

167

.'] .GRINDING LJ FINE

-------FINISHING

X T X

0.ROUGHING

> FINALSIZE &ZERORESET,

!i STRESSRELIEF-

S RAPIDRETUR

N4 Ik X

PLUNGE GRINDANGULAR

RETURN TOINITIALPOSITION OR TO

NEXTPROGRAMMED

POSITIONAXIS ( )__.___( )__..

FdRt.._ ( )_____

This Command init ia te s a subroutine thatachieves the specified dimensions

by causing the Grinding-Machinc Axesto sequence through the above Motions

Figure 7.22 Plunge Grind Angular Cycle Command

include: Air Grind; Roughing; Slress Relief; Fine Finishing; FinalSizing and Zero Reset; and Rapid Return. See Figure 7.24.

TAPER GRINDCONTOUR CONTROL Axis: Q____ (J ___________________ (J_F__ SPasses

___________________________: The six-siep cycle includes 3-axis selection that moves in the chosen # of

passes. Passes step-feed in or out at the beginning and end of eachgrind. Final Sizing and Reset with a Rapid Retraction rounds out this

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cycle. See Figure 7.25.CONTOUR GRIND Rad I_Rad 2____Rad 3____ CONTOUR CONTROL Axis: ( ) . ( ) . ( ) . F__________WPasscs

______________________________________: Art eight-step cycle that includes the Radii specified for the Contour and theRadiusground into the wheel corner. See Figure 7.26.

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r^ ifr

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Turning- and Grinding-MachincMotions

167

.'] .GRINDING LJ FINE

-------FINISHING

X T X

0.ROUGHING

> FINALSIZE &ZERORESET,

!i STRESSRELIEF-

S RAPIDRETUR

N4 Ik X

PLUNGE GRINDANGULAR

RETURN TOINITIALPOSITION OR TO

NEXTPROGRAMMED

POSITIONAXIS ( )__.___( )__..

FdRt.._ ( )_____

This Command init ia te s a subroutine thatachieves the specified dimensions

by causing the Grinding-Machinc Axesto sequence through the above Motions

Figure 7.22 Plunge Grind Angular Cycle Command

include: Air Grind; Roughing; Slress Relief; Fine Finishing; FinalSizing and Zero Reset; and Rapid Return. See Figure 7.24.

TAPER GRINDCONTOUR CONTROL Axis: Q____ (J ___________________ (J_F__ SPasses

___________________________: The six-siep cycle includes 3-axis selection that moves in the chosen # of

passes. Passes step-feed in or out at the beginning and end of eachgrind. Final Sizing and Reset with a Rapid Retraction rounds out this

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cycle. See Figure 7.25.CONTOUR GRIND Rad I_Rad 2____Rad 3____ CONTOUR CONTROL Axis: ( ) . ( ) . ( ) . F__________WPasscs

______________________________________: Art eight-step cycle that includes the Radii specified for the Contour and theRadiusground into the wheel corner. See Figure 7.26.

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iS Onailalhm of a CMC Turning Cm

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CNC Systems

7machine tool's drive motor and worktable correspond to thecomponents of the hard disk itself. The feedback circuit and the field of

electronics have perhaps made the most significant contribution to thesuccessful development of Numerical Control, and recent strides incomputer speed and storage have tied everything together in the

process, making possible the high rate of information exchangerequired.

Figure 1.1 illustrates the basic components of one common and popular electronic Closed-Loop Control System. The codedinformation contained on (he storage medium (disk, tape) is convertedin the Control to electronic pulses, where it is evaluated by thecomputer and the instructions are ultimately translated to electrical

pulses that are sent directly to the machine-movement element. Each pulse is measured, controlled, and equivalent to a small incremental

movement of the machine element (i.e., equaling revolution incrementsof

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MACHI

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Figure 1.1 CNC Closed-lux>p Control System

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11) CNC MachiningHandbook

Figure 1.3 Vertical Milling Machine CNC Axis Orientation

the viewer), respectively. The motion of the table or head up or down(change in depth or Z level) is designated as along, or parallel, to the Zaxis.

A typical configuration of axes for a CNC Turning Machine, or lathe,is shown in Figure 1.4. The X axis moves in a direction perpendicular tothe "spindle plane." The X* (positive) direction normally moves thecross-slide away from the operator/programmer's viewpoint, and the X-(negative) direction moves the cross-slide back toward the viewer. The

Z* (positive) direction of movement causes the carriage/turrct/cross-slide to move away from the hcadstock spindle or workpiccc. and the Z-(negative) direction in toward the workpiccc.

Typically, spindle rotation is determined from a viewpoint centeredfrom the X 0.0000 (Zero) position toward the center of the spindle. AClockwise rotation is the C+ (positive) direction. A Counterclockwiserotation is the C- (negative) direction. Many new CNC TurningMachines arc designed using a "Slant X Axis" feeding the cross-slideinto the workpiece from a reverse position, requiring C+ and C- spindlerotation commands to be used in the program.

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CHRPTER 2

THE PRECISION

MEASURING RND

POSITIONING OF CNC

COMPONENTS of a CNC SYSTEMIn general, CNC systems can offer many advantages over conventional

Numerical Control systems (traditionally built with hard-wire logic),including the elimination of (punched-) tape handling, the capability for on-line program revision, automatic correction of machineinaccuracies, the control of several machines from a single controlcenter, and the capability for integration into a sophisticated totalmanufacturing control system.

Operating PrinciplesMany Closed-Loop Controls use velocity feedback as well as position

feedback for two reasons: (1) to permit precise control of cuttingfeedratcs and 12) to permit use of low-grain servos thai reduce end-

point overshoot, hunting, and other undesirable effects of high-gainservos.

The main components of a system are the Control, the Positioningmechanisms/devices, and the mechanical drive elements. The Control isresponsible for managing the program data, reading them from media,computing any mathematical requirements of the processed commands,and sending output to the Positioning devices while reading and cross-checking feedback for accuracy. The Positioning devices areresponsible for processing the signals sent from the Control, measuringthe machine's movement to correspond to the


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280 S Man-MacliincInterface

with other CNC systems, although the EIA/ISO standard for programming instructions exists. This makes it difficult for a programmer to use a variety of CNC systems. Also, for die manual

programming method, the efficiency and productivity of the part program depends on Ihe programmer's ability. Therefore, knowledgeabout process planning, machining theory, G-code, and complexcomputations for lool-piilli generation are necessary for a good

programmer and a long (raining lime and much effort are alsorequired. Further, because of the lack of compatibility between

programming instructions (G-code), n programmer has to learn new programming instructions if die CNC system is changed. In addition,it is almost impossible to create a part program for machining 2.5D or 3D shape using die manual programming mcdiod. However, in Uiccase of simple machining and repeated machining tasks, die manual

programming mcdiod makes quick programming possible. It alsomakes it possible to generate a pari program quickly by modifying an

existing program and using macro programming. Moreover,depending on the programmer's ability, it is possible to generate a part program for unusual and specific shapes.

Tile automatic programming method, where a computer is used,was developed to overcome Ihe nbove-menlioned problems with themanual programming method. The automatic programming methodmakes ii easy to machine parts wilh complicated or 3D shapes. It alsomakes it possible to generate die large part programs in a short time.In addition, with computer simulation, it makes it possible to detectand modify machining errors before actual machining begins.

8.3.3 Automatic Part Programming

The automatic programming method can be classitied into dielanguage-type programming method and the conversational

programming mediod. In die language-type programming method,the machining sequence, part shape, and tools arc defined in alanguage that can be understood by humans. The human-understandable language is then converted into a series of CNC-understaiidablc instructions. In the conversational programmingmethod, die programmer inputs die data for the part shapeinteractively using a GUI (Graphical User Interface), selectsmachining sequences, and inputs the technology data for Ihemachining operation. Finally, Ihe CNC system generates the part

program based on the programmer's input. Typically conversational programming can be carried out by an external CAM system and asymbolic conversational system that is located cither inside ihe CNCsystem or in (he exienial computer. In this book, the implementationof symbolic conversational programming systems embedded in IheCNC will be .uldressed in detail.

8.3.3.1 Lnngunge-type Programming

Language-type programming is die mediod in which a programmer edils a part program using langungc-typc instructions thai the user can easily understand. As ihe

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REARTURRET

FRONTTURRET

Ihc fromlurrct.The CO

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REARTURRET

FRONTTURRET

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TuiiLiii!:- nnjCjiiiiiliiie-MinliineMotions l&S

Operations

External CylindricalSubroutines

PLUNGE GRINDSTRAIGHT Axis: Q ( ) ( ) F_____; A six-step cycleliial moves ihe wheelinlo I he workpiece in2- or 3-axisdirections, each sep-arately: AirGrinding: Kuujjlmiji:a Suess-Relicl baekiilt':Rnc-t'inish Pass: FinalSr/ing and ZeroResell anil RapidRi'linn u, I lie initial position or nextprogrammedposition. See Figure7.21.PLUNGE GRINDANGULAR Ais: ( ) .( ) ( ) F :Pl unges thewheel mlo a \inrkpieee SLI.LILL- inlersecli iiii in amn-asis din-el ion.~:iulu:-
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280 S Man-MacliincInterface

with other CNC systems, although the EIA/ISO standard for programming instructions exists. This makes it difficult for a programmer to use a variety of CNC systems. Also, for die manual

programming method, the efficiency and productivity of the part program depends on Ihe programmer's ability. Therefore, knowledgeabout process planning, machining theory, G-code, and complexcomputations for lool-piilli generation are necessary for a good

programmer and a long (raining lime and much effort are alsorequired. Further, because of the lack of compatibility between

programming instructions (G-code), n programmer has to learn new programming instructions if die CNC system is changed. In addition,it is almost impossible to create a part program for machining 2.5D or 3D shape using die manual programming mcdiod. However, in Uiccase of simple machining and repeated machining tasks, die manual

programming mcdiod makes quick programming possible. It alsomakes it possible to generate a pari program quickly by modifying an

existing program and using macro programming. Moreover,depending on the programmer's ability, it is possible to generate a part program for unusual and specific shapes.

Tile automatic programming method, where a computer is used,was developed to overcome Ihe nbove-menlioned problems with themanual programming method. The automatic programming methodmakes ii easy to machine parts wilh complicated or 3D shapes. It alsomakes it possible to generate die large part programs in a short time.In addition, with computer simulation, it makes it possible to detectand modify machining errors before actual machining begins.

8.3.3 Automatic Part Programming

The automatic programming method can be classitied into dielanguage-type programming method and the conversational

programming mediod. In die language-type programming method,the machining sequence, part shape, and tools arc defined in alanguage that can be understood by humans. The human-understandable language is then converted into a series of CNC-understaiidablc instructions. In the conversational programmingmethod, die programmer inputs die data for the part shapeinteractively using a GUI (Graphical User Interface), selectsmachining sequences, and inputs the technology data for Ihemachining operation. Finally, Ihe CNC system generates the part

program based on the programmer's input. Typically conversational programming can be carried out by an external CAM system and asymbolic conversational system that is located cither inside ihe CNCsystem or in (he exienial computer. In this book, the implementationof symbolic conversational programming systems embedded in IheCNC will be .uldressed in detail.

8.3.3.1 Lnngunge-type Programming

Language-type programming is die mediod in which a programmer edils a part program using langungc-typc instructions thai the user can easily understand. As ihe

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_ a S Maii-MiicliincInterface

Status displayarea

Dala inputarea

0 0 0 0 0 0 0 0 0 0

a a

SB H/H EHE Q &

Machine operation

area F IR . 8.1 Typical

operation panel

0 MPGoperationarea

2. Operation Mode: Displaying Ihc operation modes of machinetools, such as zero position return mode, JOG mode. Automaticmode and MDI mode.

3. Program name: Displaying the name of the program thai iscurrently loaded in the memory for machining.

4. Alarm window. Displaying the wanting and alarm messages.5. Key input window: Displaying the strings thai are typed by a user 6. Window for displaying user interface relevant lo operation modeand function:

Machining status (POS): operation slatus such as axis position,spindle speed, feedrale, modal G-codes, and tool number is

displayed by this function. Program (PROG): die GUI for editing a part program,managing Ihe program folders, graphical simulation, and CAPSis provided by this function.

Tool management: the GUI for managing tool compensation,tool life, and tool offset is provided by this function.

Parameter and system: the GUI for managing (he NC parameters, sysleni parameters for servo and spindle is provided.

Auxiliary application: the GUI for monitoring PLC, displayingalarms, performing DNC, and compensating pitch error is

provided.

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^

- -::';..:.:! ::iy:::incifilcs airnvlly.TIICM,' arc IS,designed tn control jiLtivil} . I .'.:. IiIjrru:. particularlywhirn it comes 10S1UI11. Iii'l'liilt ;LCILViiy

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FOUR-AX ISLATHES

:S^W3K5Sr""""""""

... N-. i.i! ;i'kiI.J iU-.i._- !'[;:-::.>:: :l:ir .;,: .i;ipli:.lI.' I..'.]; :.'K I. IIJ IC^;ITC called Ihc.Ij'fim. CNC j^co^r:i.ai--| 1--Tn:;:'.- >::';..:.:! ::iy:::incifilcs airnvlly.TIICM,' arc IS,designed tn control jiLtivil} . I .'.:. IiIjrru:. particularlywhirn it comes 10S1UI11. Iii'l'liilt ;LCILViiy

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Flexlble CNCGrindingMachines for ID.ID/Face, and 00OperationsConventional CNC Formal Some CNC Grindingmachines allow lheversatility of using acertain axis lo;JI ilil! Ul>- M'l ill.L-L.i.!]:i!:'.K;H I'.ll...IlLTVJl- .l\i.. I'.I.MlI'ill Und^l ;ii"ALS.LI I III \lwU face and grind IDsusing Ihc same j\is.See [ :igurc 7.20.

controlled for machining (Figure7.20(a)).While X- and Z-Axesare readv for grinding. Lhe W-Axishas been rotaled 90'CW and now can beinstated as lhe U-Aiisfor Tangenlialgrinding. Beth lhe U-and W-A

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8.3 CNCProgramming

281

manual programming method is similar lo assembly language programming, so (he language-lype programming is similar to programming in BASIC or FORTRAN. For language-type

programming, APT. EXAPT. FAPT. KAPT, and COMPACT II have been widely used.

APT (Automatically Pmgrammcti Tool}APT, which was developed in die USA in die 1960s, is die mostfamous system for the language-type programming tool and hasthe greatest number of functions. APT allows representation of various geometries, such as line, circle, ellipse, sphere, cylinder,cone, tabulated cylinder, and general two-dimensional surfaces. Byusing APT, it is possible to generate programs for 3-axis, 4-axis,and 5-axis machining, including rotation control for spindles andmachining tables. Figure 8.5 shows the structure of a pari programin APT. The part program consists basically of four parts; 1) theshape definition pari where the shape lor the machined pari isspecified, 2) the motion definition pari where the lool paths arespecified, 3) the post processor part where cutting conditions andihe characteristics of Ihe CNC system are specified, and 4) dieAuxiliary pari where auxiliary data such as tool size, workpiecenumber, and so on is specified.

EXAPT EXAPT was developed in Germany. There arc three kinds of EXAPT; EXAPT I for position control and linear machining,EXAPT II for turning, and EXAPT III for milling such as two-dimensional contour machining and one-Dimensional linear machining. EXAPT is very similar lo APT but without workshoptechnology. EXAPT decides automatically how many lools areneeded by considering the material of the workpiece, requiredsurface roughness, and Ihe shape of the hole specified by the programmer. It calculates automatically the spindle speed andfeedrate. In EXAPT II. with user specification of die shape of the

blank material and machined pari, all machining operationsincluding ihe machining allowances are generated automatically.On die other hand, it is necessary to register the pre-specified data

because appropriate spindle speed, feedrale, and culling depth canhe varied according lo ihe machine and lools. Because EXAPTgenerates automatically not only ihe lool path but also machiningoperations and culling conditions, il is easier to use than APT.However, the kinds of maehineable part shape thai can be handledare more limited than with APT.

FAPT

FAPT was developed by FANUC and is similar to APT. FAPT can be used in carry-on exclusive programming equipment. By using particular programming software such as FAPT Turn. FAPT Mill,and FAPT DIE-II, part programs for luming, milling, and die andmold machining can be generated easily. The FAPT Turn/Millsystem has die following characteristics.FAPT turn is a software library for turning. For part programming,the coordinate sysleni of the rotation axis of the workpiece isdefined as die Z-axis and Ihe radius direction of the workpiece isdefined as ihe X-axis, f l is possible to program based on bothdiameter and radius values of the X-axis. FAPT lura provides f)roughing. 2) finishing, 3> grooving, and 4) threading as metal-removal operations. The

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CMC Systems9

^ ^ t ^ , v...........

Z-Axls

"sza " c"~ '"*"*" *"" "" "" *

t.'r.jr.v.'^'oii hihlr. Ii.r to-.v con'. L-i'ion ol all.. IILI'J- inline IL\I. IS shown on page 239.

Designation of theMachine Axis

The designation of ihe machine axis for each individualizedtype or machinetool is based on arectangular coordinate systemassociated with themachine. Tht- dit it!ion* of motionindicated in Figure1.3 are typical of thenormal motions illmilling machinetravel. The longestmotion that themachine axis isL;IP;;I>'L: . I] travelingis generallydesignated asalong, or parallel lo,tlit- .\ axis. Mine incutof I he cutting toolin a single dim-lion(rumiuilK lo the rightfrom a frontalviewpoint) isconsidered as"positive X" (+X),and movement inthe oppositedirection (lefl| isconsidered as-negative X" (-X).Lying horizontallyfrom Ihc point onIhc X axis [X = 0).and at an angle or exactly 90 to the Xaxis, is the V axiswith it- positive andnegalki- diiivlions -il motion in relation lothe culling tool, (+Y|(away from I hefrontal viewpoint)and (-Y) (backtoward

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282 8 Man-Macliinc Interface

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FOUR-AXIS LATHES

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282

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Chapter 20

(T03 - FINISH TURNING - 55-DEG TOOL) N21 T0300 (TOOL CHANGE) N22 GOO G41 X6.1 ZO. 1 T0303 MOB (STMT POINT FOR G70) N23 G70 P9 Q17 (FINISHING CYCLE - EXTERNAL) N24 GOO G40 X10.0 23.0 T0300 (TOOL CHANGE POSITION) N25 M01 (OPTIONAL STOP) N26 H102 (* SYNCHRONIZATION M102 ***) N27 M30 (PRQCRAH END - FRONT TURRET)%

Study the program carefully. It follows the structure presented earlier. There arc three toolsfor the rear turret, and two tools for the front turret. The program starts with only the drillworking on the rear turret, while the front turret is idle. When the drilling is completed,the waiting code M100 forces both turrets to start machining at the same time (rough

boring and rough turning). There is a good chance that one of these operations completesearlier than the other. Waiting code MI01 guarantees that no finishing takes place, until bothroughing operations arc completed. Finally, both finishing operations will be completed

before program ends (waiting code M102 before M30).Spindle speeds are programmed for only one turret in mis case, at the programmer's

discretion. G96 is an option, and so is programming die spindle speed for either turret.From the example, it is apparent that the programming process for four-axis CNC is no

different from UK process for two-axis lathes. There are some additions and severalconsiderations, but the main focus expected from the programmer is the most efficient useof both turrets.

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FOUR-AXIS LATHES

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8.1 MMI Function

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273

7. Function keys: these keys are horizontally placed in the bottom or vertically on the right-hand side of the display and are mapped tothe particular functions. There-lore, to effectively design the menustructure, it is important to classify die functions into theappropriate group and enable the necessary keys to be displayed inone display. It is necessary to consider that the number of hierarchical layers increases if CNC functions are grouped and aredesigned its a hierarchical structure. Therefore, if the user wants toselect a particular menu at the bottom of die hierarchical structure,the user has to select a sequence of menus from die lop menu tothe bottom menu. Also, the user has to remember the hierarchicalstructure and die menus located in each layer. This problem makesdie user interface inefficient.

To overcome this problem, it is necessary to design a ring menustructure of menu trees where, by selecting (he displayed menutree, the user can carry out the desired task from the function keysdisplayed on one screen as much as possible i!in! each functionkeys is connected with die various modes. In this type of menustructure it is not necessary to remember the menu structure.However, die menu structure may be inconsistent and m;uiyfunction keys may be required.

8.1.2 Area for Data Input

As this area is the keyboard for inputting user data to the CNC system,it consists of ulplianumerical input buttons and hot keys for executingthe functions of CNC.

8.1.3 Area for MPG Handling

This area consists of the MPG (Manual Pulse Generator), the MPGhandle ON/OFF switch and the iced ratio selection key that arc usedfor the user to move each servo axis manually. In addition, the Chuck CLAMP/UNCLAMP key for manually loading and unloading toolsto lite spindle and the emergency stop button are located in this area.

8.1.4 Area for Machine OperationThis area consists of many kinds of switch and lamp that providevarious functions as follows.

1. Moth- selection switch: for selecting Auto mode, MDI mode.Teach-in mode. Return mode, JOG mode. Handle mode.Incremental Moving mode, and Rapid Moving mode.

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278 8 Man-MachineInterface

8.3 CNC Programming

In order lo machine the part in a drawing by using CNC machinetools, it is necessary to generate a scries of instructions for activatingthose CNC machine tools. This task is called CNC programming.

8.3.1 The Sequence of Part Programming

Roughly, CNC programming is composed of the generation of a process plan from a part drawing and the generation of the part program. The detailed processes are as follows.

1. To analyze the part drawing.2. To decide on the removal volume and lo select die machine.

3. To decide on the jig and chuck.4. To decide on the setups, machining sequences, cut start points, cutdepths for roughing and finishing allowance.

5. To select tools and tool holders and to decide on the tool position.6. To decide on the technology data such as spindle speed, feedrale,mid coolant

on/off,7. To generate the part program (including post-

processing).3. To verify die part program.9. To machine.

The tusks from stage 1 to stage 6 are included in the preparationstage where the part drawing is analyzed and the machining strategyis decided for creating a part program. These tasks are called "process

planning". Process planning is done hy a programmer or a machineoperator. Extensive knowledge about the machine tools, CNCequipment, tools, and cutting theory is required to generate fine

process planning. However, in practice it is very difficult to findexperts for these. Therefore, many studies on CAPP (Computer Aided Process Planning) for automatically executing process

planning have been carried out.After process planning, a part program (stage 7) for controlling

CNC machine tools is generated. The generation of this part programcan be done by the manual programming method or the automatic

programming method. In the manual programming method, a programmer directly edits the part program in CNC-readableE1A/ISO code. In Uie Automatic programming method, a

programmer edits the program in terms of graphical symbols or ahigh-level language via a computer. The CNC system then convertsthis program into machine-readable instructions and executes thoseinstructions.

The automatic programming method can be classified into twotypes in terms of the editing method; the first is the language-type

programming method where a high-level language is used for programming. The second type is the conversational

4

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Figure 7.23 TraverseGriwl-Cycle Command

Multlaxls CNC InternalGrinding Cycles

INSIDE DIAMETER Axis: () ( ) . t ). F(Passes___________:Grind IDs

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282 8 Man-Macliinc Interface

CLPRNTL182 =LlNE/6.25.-1.0,2.0.0.25.-1.0,2.0 LI83-UNE/O.25.-I.O.2.0.2.0.3.5.2.OLI84 LINE'2.0.3.5.2.0.6.7525.1.1319.2.0CI58 -ClRCl-E/6.2507,0.125,2.0,1.125 LI85-UNE/6.2507,-1.0,2.0,6.25,-1.0,2.0

CUTTER/0.25.0.05.0.075.0.05,0.0.0.0,4.0COOLNT/ONSPINDL/1200PEDRAT/I.OourroL. o.oo5TLAXIS/0.0,0.0

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Programmable CNCGrinding CyclesMost Mulliaxis CNCGrinders wilhcontouringControls haveallowed signifi-L-.itii ^iil'.-.iiiLvii'^iii^-in :h'.' r.Kllin.f-ill ;'iin-.lii:i- kvlni.ilui'yI\.LV

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