(C)2001 Manufacturing Engineering Laboratory, Toyota Technological Institute

UR

L: h

ttp://

ww

w.to

yota

-ti.a

c.jp

/Lab

/Kik

ai/5

k60/

12-1

, His

akat

a 2-

chom

e, T

empa

ku-k

u, N

agoy

a 46

8-85

11 JA

PAN

In-process Measurement of Wear of Grinding Wheel

by Using Hydrodynamic PressureBackground and problem• Monitoring of grinding wheel wear for precision grinding

• Disturbance of light by working fluid

Solution• Gap sensing by using hydrodynamic pressure with pressure sensor arranged with small gap

Advantages• Simple sensing device• In-process measurement of radius and topography of grinding wheel

• Dependence of only geometry of grinding wheel

Results• Relationship among pressure, gap and speed• Enable to run-out by arranging several sensors• Standard deviation of 1 m in measured radii• Enable to detect loading, shedding and dulling

Applicable field• Plunge grinding• Creep-feed grinding• High precision grinding such as ELID• Grinding expensive material• Small-amount products

W o r k in gf lu id

P re s s u res e n s o r

R o ta t io n

G rin d in gw h e e l

In it ia l g a p

W e a r

W o rk p ie c e

渦 電 流 式 変 位 セ ン サ

軸

カ ッ プ リ ン グ

モ ー タ タ コ ジ ェ ネ レ ー タ

円 盤

圧 力 セ ン サ

DiskEddy current sensorShaftCoupling

TachometerPressure sensors DC motor

Principle of measurement by using hydrodynamic pressure

Experimental apparatus

0 20 40 60 80

Time ms

Hyd

rody

nam

ic p

ress

ure

50

kPa/

div

Gap

50

m/d

iv

Pressure

Gap

1 10 100 1000

Frequency Hz

Pres

sure

kPa

Gap

m

Pressure

Gap

102

100

10-2

10-4

103

101

10-1

Examples of outputs of sensors

0

5

10

15

0 50 100 150 200 250

Minmum gap m

Pres

sure

kPa

3rd cut

2nd cut

1st cut

Initial

0 50 200 250Gap m

Pres

sure

kPa

0

15

Initial

1st cut

2nd cut

3rd cut

10

5

150100

Trajectory of pressure to gap

5

6

7

100 110 120 130 140Gap m

Pres

sure

kPa

Initial1st cut 2nd cut

3rd cut

Average pressure vs. gap

0

10

20

30

40

0 20 40 60 80 100Minimum gap m

Pres

sure

kPa

D#400

WA#800

WA#46

x=+1.5 mmPeripheral speed 28.7 m/s

Influence of grain size

0

20

40

60

0 20 40 60 80 100

Minimum gap m

Pres

sure

kPa

0

0.5

1

1.5

P max

-Pm

in k

Pa

Measured pressure

Pmax-Pmin

Dispersion of measured pressureDetection of loading of grinding wheel

1 10 100 1000 10000Frequency Ｈｚ

Pres

sure　×

10 k

Pa/d

iv

Just after dressing

After initial wear with SUJ2

Grinding 5 m

Grinding 10 m

Grinding 15 m

Grinding 20 mGap: 10 mFluid: 5.0 l/minWorkpiece: Aluminium

Prog

ress

of

load

ing

(C)2001 Manufacturing Engineering Laboratory, Toyota Technological Institute

UR

L: h

ttp://

ww

w.to

yota

-ti.a

c.jp

/Lab

/Kik

ai/5

k60/

12-1

, His

akat

a 2-

chom

e, T

empa

ku-k

u, N

agoy

a 46

8-85

11 JA

PAN

Three-dimensional Form Generationby Dot-matrix Electrical Discharge Machining

Background and problem• Needs for rapid production system for metals• Difficulty in production of tool electrode to mach

ine small shape

Solution• Shaping profile of bundled electrodes by controll

ing their length and scanning them as one electrode

Advantages• Enable to skip making process of electrode• Mechanical strength of electrode• Enable to compensate electrodes for heavy wear

by feeding them• Use of thin wire for electrodes

Results• Machining 3D shape with 6 thin electrodes• Less cracks by divided power because of dischar

ge dispersion

Applicable fields• Micromachining• Micromold fabrication• Rapid prototyping for metals

Main axis of electrical discharge machine

Wire electrode

Electrode feeding device

Electrode guide

NC table

Workpiece

Machining unit

Concept of dot-matrix electrical discharge machining

System configuration

Equi-potential power Divided power

Types of power supply for dot-matrix EDM

Machining sequence

Positioning sequence of electrodes

-5.1mm0

0-0

.5m

m

0

-0 5.1mm

0-0

.5m

m

-300

-250

-200

-150

0 2000 4000 6000

x m

Dep

th

m

-300

-250

-200

-150

0 2000 4000 6000x m

Dep

th

m

Example of machiningImprovement of wavinessEquii-potential power Divided power

0 10 20 30Time ms

Dis

char

ge c

urre

nt

EL5

EL2

EL6

EL4

EL3

EL1 0.5

A

0 10 20 30Time ms

Dis

char

ge c

urre

nt

EL6

EL5

EL4

EL3

EL2

EL1

0.5

A

Discharge dispersion

Designed shape

Result of machining

Appearance of machining unit

Quill of electrical discharge machine

(C)2001 Manufacturing Engineering Laboratory, Toyota Technological Institute

UR

L: h

ttp://

ww

w.to

yota

-ti.a

c.jp

/Lab

/Kik

ai/5

k60/

12-1

, His

akat

a 2-

chom

e, T

empa

ku-k

u, N

agoy

a 46

8-85

11 JA

PAN

Precision Positioning Table Employing Parallel Mechanism

for Scanning Probe Microscope

C a n tile v e r

S e m ic o n d u c to r la se r(5 m W ,6 3 5 n m )Q u a d ra n t

p h o to d e te c to r

S p e c im e n

T a b le

B a s e p la tfo rm

L in kP a ra l le llin k

V ib ra t io n is o la t in g ta b le

P ro b e

75

I n v e rs ek in e m a tic s

P ie z oL P F

S e n s o r

K PG iv e np o s tu r eo f t a b le

L in kle n g thfo r g iv e np o s tu r e ,

R i

L 1R 1

P ie z oL P F

S e n s o r

K P

P ie z oL P F

S e n s o r

K P

L 2

R 2

L 6

R 6

B a se p late T ab le

E d d y cu rre n td isp lac em en tse n so rs

L ev er m ec h an ismw ith fle xu re h in g es

F le xu re jo in ts

E lectro d efo r d e tec tio n

S tac ke d p iez o

X

YZ

E le c tr o d e s f o rd e te c tio n

T a b le

F le x u rejo in ts

E d d y c u rr e n ts e n so r

S ta c k e dp ie z o

L e v e r m a c h a n ismw ith fle x u r e h in g e s

B a sep la te

1 6 0

6 °

(a) Open loop control

-0.1

0.0

0.1

0.2

-1.0 -0.5 0.0 0.5Displacement of table m

Out

put o

f P.D

. V

① ②③

④⑤⑥⑦

(b) Displacement feedback control

-0.1

0.0

0.1

0.2

-1.0 -0.5 0.0 0.5Displacement of table m

Out

put o

f P.D

. V

① ②③

④⑤⑥⑦

(c) Induced charge feedback control

-0.1

0.0

0.1

0.2

-1.0 -0.5 0.0 0.5Displacement of table m

Out

put o

f P.D

. V

① ②③ ④

⑤⑦ ⑥

Background and Problem• Cutting machine for nanometer depth of cut• unavoidable tilt of tube type piezoelectric actuato

r in general scanning probe microscope (SPM)

Solution• Stewart platform type parallel mechanism control

led by induced charge feedback method

Advantages• 6 degrees of freedom• High resolution in z because of small elevation an

gle• Flexible tool path• Enable to use in vacuum because of no slipping el

ement

Results• Smaller tilt (1/10 to tube type)• High positioning accuracy (16 nm in z)• Linearity within 20×20 m by semi-closed loop c

ontrol

Applicable fields• Ductile mode cutting of brittle materials• Micromachininig• Fine motion stage for SPM

Appearance of device

Sectional view

Setup for atomic force microscope

AFM image of diffraction gratings Force curve on Silicon

SpecificationsSize: 16016085 mmMass of table: 24 gMovable range:

100 m in xy, 20 m in zResonance frequency:

100 Hz in xy, 75 Hz in zDegrees of freedom: 6Actuators: Piezoelectric actuatorsMagnification: 12.5

Block diagram of control system

Cross talk ratio %Feedback x/y z/yPitching error

radNone 19.6 8.2 12

Displacement 11.7 3.9 17Induced charge 3.5 4.7 17

Cross-talk ratio