- Email: [email protected]
Cutting Force Measurement of a Rotating Tool by Means of Optical Data Transmission
Cutting Force Measurement of a Rotating Tool by Means of Optical Data Transmission Y. Ikezaki, Y. Takeuchi and M. Sakamoto, Kyushu Institute of Technology of Tokyo
- Submitted by T. Sata (1). The University
Sumnary : The study proposes a new way t o a c c u r a t e l y measure t r a n s i e n t c u t t i n g forces o f a r o t a t i n g t o o l such as a m i l l i n g c u t t e r from t h e s i d e o f t o o l . The transmission o f c u t t i n g forces through a s l i p r i n g o r a FM telemeter i s l i a b l e t o be a f f e c t e d by noises. Therefore, a device t o o b t a i n r e l i a b l e c u t t i n g data has been r e q u i r e d t o analyze t h e c u t t i n g phenomena. I n t h e measurement system developed, a m p l i f i e d output s i g n a l s from s t r a i n gauge bridges a r e d i g i t i z e d using an A0 converter and then converted t o continuous s e r i a l data streams t o o p t i c a l l y t r a n s m i t them o u t s i d e a machine t o o l by use o f LEO. Received s e r i a l data streams by a photo sensor a r e conversely r e s t o r e d t o p a r a l l e l data, which a r e inmediately processed by a personal computer. The t r a n s i e n t c u t t i n g forces can be measured w i t h o u t any trouble. As a r e s u l t , t h i s method was found t o be very p r a c t i c a l and a l s o a p p l i c a b l e t o a v a r i e t y o f measuring f i e l d s r e q u i s i t e f o r non-contacting data transmission,
1.
Introduction 2.1
The accurate measurement o f c u t t i n g forces i s e s s e n t i a l t o analyze c u t t i n g phenomena. The way o f c u t t i n g f o r c e measurement can be d i v i d e d i n t o two groups. One i s t o measure t h e c u t t i n g f o r c e s a c t i n g on a t o o l through a d e t e c t o r attached t o t h e t o o l , and t h e o t h e r through the d e t e c t o r attached t o a workpiece o r a workpiece holder. The former i s p a r t i c u l a r l y important i n t h e l i g h t o f d i r e c t measurement o f c u t t i n g forces e x e r t i n g an e f f e c t on t o o l . I n case o f a f i x e d t o o l such as a l a t h e , measuring methods from t h e t o o l s i d e have been established, and various devices a r e on t h e market [l] Compared t o a f i x e d t o o l , most measurements o f a r o t a t i n g t o o l , such as m i l l i n g o r d r i l l i n g t o o l . a r e performed on t h e s i d e o f a workpiece, since t h e r o t a t i o n of a t o o l d i s t r e s s e s t h e transmission o f measured data. Up u n t i l now, measured data o f r o t a t i n g t o o l s have been t r a n s m i t t e d u t i l i z i n g special c o n t a c t mechanism such as s l i p r i n g and mercury contact, however, i t i s d i f f i c u l t t o d i s t i n g u i s h t h e change o f c u t t i n g forces from t h a t o f contact resistance, e s p e c i a l l y i n i n t e r m i t t e n t c u t t i n g . The higher a s p i n d l e r o t a t e s , the l a r g e r t h e c o n t a c t r e s i s t a n c e changes, which r e s u l t s i n t h e i m p o s s i b i l i t y o f measurement. Another p o s s i b i l i t y o f data transmission i s concerned w i t h non-contacting way, f o r examples, FM telemeter, l i g h t beam 121 and magnetic c o i l [31 The study aims a t c o n t r i v i n g and developing a new device t o a c c u r a t e l y t r a n s m i t d i g i t i z e d measured data w i t h o u t being affected by noises and d i s t o r t i o n d u r i n g trasmission, making use o f l i g h t signals. L i g h t s i g n a l s as transmission means have n o t p r e v i o u s l y been r e p o r t e d except f o r an example applied t o torque I n a d d i t i o n , the data transmission i n an adaptive c o n t r o l [4] device i s e a s i l y d e a l t with, since measured data a r e t r a n s m i t t e d i n a s i n g l e d i r e c t i o n by l i g h t as s e r i a l data streams. The device w i t h s t r a i n gauges f i x e d on t h e t o o l as a c u t t i n g f o r c e transducer i s planned and applied t o the cutting force measurement on a v e r t i c a l m i l l i n g machine. Consequently, i t i s proved t h a t c u t t i n g f o r c e data a r e r e l i a b l y t r a n s m i t t e d and received
.
.
.
.
2.
Detection and Transmission o f C u t t i n g Forces
The block diagram o f transmission section, which corresponds t o t h e f i r s t h a l f o f t h e measurement system, i s i n d i c a t e d i n Fig. 2. The c u t t i n g forces a c t i n g on a t o o l a r e replaced w i t h an e l e c t r i c r e s i s t a n c e change by use o f s t r a i n gauge bridges. whose o u t p u t v o l t a g e i s several mV. Therefore, t h e output v o l t a g e from s t r a i n gauge b r i d g e s must be a m p l i f i e d t o have enough voltage t o an A0 converter. The a m p l i f i e r c o n s i s t s o f f i v e OP a m p l i f i e r s t o form a h i g h impedance d i f f e r e n t i a l a m p l i f i e r c i r c u i t , whose a m p l i f i c a t i o n f a c t o r depends on t h e p r e d i c t e d maximum c u t t i n g force. Next, an a m p l i f i e d sampled voltage i s converted i n t o d i g i t a l form by AOC ( AOC-EH8b. OATEL ). It has an & b i t r e s o l u t i o n capacity, t h e f u l l - s c a l e range o f t h e incoming analog signal i s 0 t o 10 V i n u n i p o l a r i t y use and -5 t o +5 V i n b i p o l a r i t y use, and t h e conversion time i s 4 vsec. The d i g i t i z e d s i g n a l s can be o u t p u t e i t h e r i n s e r i a l fonn o r i n p a r a l l e l form. Although s e r i a l o u t p u t form i s convenient t o t r a n s m i t s e r i a l l i g h t s i g n a l s i n t h e outside, t h e p a r a l l e l o u t p u t form, however, i s selected, t a k i n g account o f t h e response o f e l e c t r i c p a r t s used i n t h e transmission and r e c e i v e r c i r c u i t . To t r a n s m i t d i g i t i z e d s i g n a l s from t h e center o f t h e r o t a t i n g s p i n d l e o f a m i l l i n g machine, d i g i t i z e d s i g n a l s i n p a r a l l e l form must be converted i n t o s e r i a l form by use o f a p a r a l l e l - t o - s e r i a l converter ( PSC ). The l e a d i n g s e c t i o n o f t h e PSC consists of Parallel t h r e e 4 - b i t s h i f t r e g i s t e r s i n t h e cascade connection. s i g n a l s being o u t p u t from ADC a r e i n t u r n converted i n t o s e r i a l signals, synchronizing t h e frequency o f a pulse generator f o r s h i f t . The conversion r a t e i s a d j u s t a b l e by use o f t h e generator. The frequency of t h e p u l s e generator used i n t h e study i s 100 KHz, t a k i n g t h e response time o f a photo sensor i n t o account. As a r e s u l t , s e r i a l s i g n a l s a r e obtained w i t h t h e time i n t e r v a l of 10 vsec. I n t h e s e r i a l data, i t i s impossible t o recognize t h e s t a r t p o i n t and end p o i n t o f data. Thus, i t i s necessary t o n o t i f y t h e r e c e i v e r s e c t i o n o f t h e s t a r t p o i n t f o r every data. As a countermeasure t o t h e s i t u a t i o n , a modified synchronous communication procedure i s used, which provides t h e proper data by adding a s t a r t b i t and an end b i t f o r each data. I n t h e study, o n l y t h e s t a r t b i t i s added t o each data w i t h 8 - b i t .
S t r u c t u r e o f Wasurement System
Figure 1 shows a schematic diagram o f t h e s t r u c t u r e o f measurement system. As a machine t o o l w i t h a r o t a t i n g t o o l , a A transmission s e c t i o n o f v e r t i c a l m i l l i n g machine i s used. c u t t i n g forces i s b u i l t w i t h i n t h e main s p i n d l e o f machine, and t h e r e c e i v e r o f l i g h t s i g n a l s and t h e r e s t o r a t i o n s e c t i o n a r e provided o u t s i d e t h e m i l l i n g machine. Restored measured data a r e t e m p o r a r i l y stored i n t h e m m r y area o f a personal computer, and then converted t o c u t t i n g forces.
M
STRAIN_GAUGES
S/H:SAMPLE AND HOLD ADC:ANALOG TO D I G I T A L CONVERTER PSC:PARALLEL TO SERIAL CONVERTER
Fig. 2
S c h e m t i c diagram o f t r a n s m i t t i n g c u t t i n g f o r c e s o u t s i d e t h e machine t o o l by use o f LEO
Figure 3 represents a time c h a r t o f ADC and PSC i? the transmission section, where two o s c i l l a t o r s a r e provided, 1 .e., f o r A0 conversion pulse @ and l f o r s h i f t pulse $2. They a r e no sooner generated than t h e power source i s switched on. A conversion pulse i n d i c a t e d i n time c h a r t (a). r e s e t s and s t a r t s t h e conversion. Time c h a r t ( b ) shows t h e conversion end signal, which r a i n s h i g h d u r i n g conversion and becomes low a t t h e end o f conversion. Both time c h a r t ( c ) and ( d ) PSC i n p u t s p a r a l l e l data and outputs i n d i c a t e those o f PSC. s e r i a l data, as shown i n time c h a r t ( c ) . I n t h e study. t o s i m p l i f y t h e c i r c u i t , t h e i n v e r t e d s i g n a l of t h e conversion end s i g n a l i s used as a c o n t r o l mode s e l e c t i o n signal. Namely, a t t h e time when p a r a l l e l data a r e o u t p u t a f t e r conversion. s i g n a l ( c ) a t a h i g h l e v e l enables t h e s h i f t r e g i s t e r t o accept p a r a l l e l i n p u t data, and t h e s i g n a l a t a low l e v e l t o output s e r i a l data, synchronizing 9 1 as shown i n time c h a r t (d).
el,
Fig. 1
Block diagram o f t h e c u t t i n g f o r c e measurement system o f rotating tool
Annals of the CIRP Vol. 33/1/1984
61
The s e r i a l data a r e emitted o u t s i d e by a LED, which has sharp d i r e c t i o n a l c h a r a c t e r i s t i c s w i t h peak wave l e n g t h o f 9400 A.
-
i n p u t i f t h e c u r r e n t memory address i s greater than the end address o f data. I f n o t s o , t h e program increases the c u r r e n t memory address by one, outputs a set signal, and r e t u r n s t h e r o u t i n e t o send a s e t pulse. The minimum sampling time i n t e r v a l by t h i s program i s 45 psec, a s was already mentioned.
LATCHED AND V A L I D
( b,
tUD
OF
COWtRSION
I
1
:...-
I CONYERSIOS T 1 M E : I u S
PARALLEL UOllli SHIFT MODE
I
S T A R 1 PULSE
0
I
ALLOCATE I/O CONTROL MODE ENTRY ADDRESS g THRESHOLD
DATA READY
Fig. 3 2.2
INPUT DATA FROM SPC
Timing diagram o f ADC and PSC
I
Emitted s e r i a l data a r e detected by a photo t r a n s i s t e r attached over the coaxial center o f LED a s seen i n Fig. 4. The photo t r a n s i s t e r w i t h a maximum s e n s i t i v i t y o f 8000 i s selected i n order t h a t i t s wave l e n g t h i s as near t o t h a t o f LED as possible. Detected s e r i a l data a r e a m p l i f i e d enough w i t h i n t h e range t o be d i g i t a l l y processed. A zenar diode i s i n s e r t e d t o p r o t e c t e l e c t r i c p a r t s from being destroyed when t h e l e v e l o f a s i g n a l becomes higher than t h a t o f TTL. Signals, which pass through a wave r e c t i f i c a t i o n c i r c u i t , then come t o a s e r i a l - t o - p a r a l l e l converter ( SPC ) which performs an inverse a c t i o n a g a i n s t PSC. The SPC consists o f a s t a r t b i t search f u n c t i o n o f s e r i a l data, a s h i f t r e g i s t e r and a s h i f t pulse generator. The s t a r t b i t search i s t o d e t e c t a s t a r t assigned a t t h e t o p o f every coming s e r i a l data. The s t a r t s i g n a l being found, SPC keeps t h e gate o f the search c i r c u i t closed d u r i n g t h e time t o take i n a s e t o f data t o avoid t h e overlap o f measured data and, a t t h e same time, outputs a pulse generation s t a r t s i g n a l t o t h e s h i f t pulse generator. The s h i f t pulse generator generates n o t o n l y pulse t r a i n s necessary f o r t h e s h i f t a c t i o n , but a l s o l a t c h signal r e q u i s i t e f o r m a i n t a i n i n g r e s t o r e d data i n t h e l a t c h c i r c u i t a f t e r s h i f t . The s h i f t r e g i s t e r i s t h e same one as i s used i n t h e PSC. Restored data i n t h e l a t c h c i r c u i t w a i t f o r being taken by t h e personal computer PC8001mk.
NO
d
1
Receiving o f Emitted Data and Processing
I
1
-
7
,1
YES
STORE DATA TO MEMORY I
STOP
OUTPUT RESET FLAGS
I Fig. 5
2.4
Flowchart f o r s t o r i n g measured data t o a personal computer
I n s t a l l a t i o n o f Measuring Devices
A c o n f i g u r a t i o n o f the main s p i n d l e o f a v e r t i c a l m i l l i n g machine w i t h t h e measuring device i s i l l u s t r a t e d i n Fig. 6. A sensor, ADC, PSC, two pulse generators, LED and power source a r e mounted on t h e disc, which i s f i x e d on the t o p o f t h e s p i n d l e by a draw-in b o l t and a nut, dnd r o t a t e d together w i t h t h e r o t a t i o n o f t h e s p i n d l e as seen i n Fig. 7. The i n f l u e n c e o f c e n t r i f u g a l f o r c e counts f o r nothing i n t h e range o f low r o t a t i o n , however, i n the range o f h i g h r o t a t i o n i t may cause t h e a b e r r a t i o n o f beam a x i s due t o t h e i r unbalanced layout. To d r i v e t h e device, two kinds o f voltage, i.e., i 1 5 V and 5 V, a r e required, which a r e provided by a DC-DC converter from a lead storage b a t t e r y ( 12 Y , 6 A, 22 N ). Therefore, t h e heavy b a t t e r y i s arranged i n t h e center o f t h e disc, and the remaining p a r t s a r e l a i d o u t
(MV\SURLHGI EQUI PMENT
, Fig. 4
STORAGE DC-DC BATTERY CONVERT'ER
Schematic diagram o f r e c e i v i n g s e r i a l data by use o f a photo t r a n s i s t e r
2.3
Data A c q u i s i t i o n Program
A f l o w c h a r t o f t h e data a c q u i s i t i o n i s presented i n Fig. 5. A t f i r s t , an i n p u t / o u t p u t c o n t r o l signal, a data i n p u t form, an assignment o f t h e s t a r t and end address f o r measured data t o be stored, and a t h r e s h o l d value a r e input. A r e s e t pulse i s output a t t h e r e s e t terminal o f t h e l a t c h c i r c u i t t o i n i t i a l i z e , then a s e t pulse i s sent t o search f o r t h e i n p u t o f measured data. I f t h e r e i s no data i n t h e l a t c h c i r c u i t , t h e program once more goes back t o t h e r o u t i n e t o send a s e t pulse. I f t h e r e i s an i n p u t , i t i s taken i n as a set o f data, and compared w i t h t h e t h r e s h o l d value. I f i t i s g r e a t e r than the threshold value, i t i s stored i n t h e memory area as a s e t o f measured data. The threshold value i s s e t up t o prevent data from noises i n case o f t h e h i g h a m p l i c a t i o n f a c t o r . Comparing t h e c u r r e n t memory address w i t h t h e end address f o r data t o be stored, t h e program f i n i s h e s t h e data
62
A-A
SECTION
GAUGES
Fig. 6
Set-up o f transmission apparatus mounted on the t o p o f t h e main s p i n d l e o f a v e r t i c a l m i l l i n g machine
The overhang o f t h e t o o l holder i s 33.3 mn long. Two semiconductor s t r a i n gauges and two r e s i s t a n c e s t r a i n gauges a r e niounted 23 mm away from t h e top o f t h e t o o l t o c o n s t r u c t a b r i d g e c i r c u i t as a sensor. The dynamic c h a r a c t e r i s t i c s o f a measurement system i S of importance i n i n t e r m i t t e n t c u t t i n g such as m i l l i n g . Thus, the compliance i s measured, i n f l i c t i n g an impulse i n t h e c i r c u m f e r e n t i a l d i r e c t i o n upon t h e t o o l w i t h an a c c e l e r a t i o n pickup. An experimental r e s u l t i s shown i n Fig. 9, together w i t h a power spectrum o f t h e c u t t i n g force. Dominant components o f t h e power spectrum o f t h e c u t t i n g f o r c e g e n e r a l l y l i e w i t h i n the range o f 50 Hz. On t h e o t h e r hand, t h e compliance o f t h e measurement system has a f i r s t n a t u r a l frequency near 1000 Hz. The dynamic c h a r a c t e r i s t i c s , thus, a r e o f no concern i n t h i s measurement system. The r e l a t i o n between a p p l i e d l o a d and output signal from sensor i n d i c t e s a good l i n e a r i t y up t o 784 N
.
Fig. 7
View o f t h e s p i n d l e head w i t h transmission appratus and t h e toGl w i t h s t r a i n gauges
on b o t h sides o f t h e b a t t e r y . The cables t o supply power t o s t r a i n gauges bridges and t o take i n i t s o u t p u t s i g n a l a r e spread through a groove along t h e draw-in b o l t . A f t e r being adjusted t o p u t i t s beam a x i s r i g h t l y on t h e s p i n d l e axis, LEO i s f i x e d by a screw. As f o r t h e r e c e i v e r section, a photo t r a n s i s t e r i s c o r r e c t l y s e t over the c e n t e r of LEO. A whole view o f t h e measurement system i s shown i n Fig. 8. 3.
Weasurement o f C u t t i n g Forces
3.1
I n s p e c t i o n o f Measuring Device
I n o r d e r t o i n s p e c t t h e measuring device developed i n t h e study, c u t t i n g forces i n t h e c i r c u m f e r e n t i a l d i r e c t i o n , i.e., p r i n c i p l e c u t t i n g force, a r e measured, using a v e r t i c a l m i l l i n g machine. The m i l l i n g machine, t o o l and c u t t i n g c o n d i t i o n used i n t h e experiments a r e as f o l l o w s : M i l l i n g machine: N i i g a t a Tekko Co. Ltd. Tool: c a r b i d e i n s e r t P20 ( -5,5,-6,6,15,15,0.8 ) WorkDiece m a t e r i a l : D l a i n carbon s t e e l S55C ( C = 0.55 Z ) and c a s t i r o n ( FC25 ) C u t t i n g speed: 218 m/min ( S55C ), 154 m/min ( FC25 ) Feed r a t e : 0.13 n / t o o t h ( 555C ), 0.12 mn/tooth ( FC25 ) Depth o f c u t : 1 n
-
Fig. 9
Dynamic c h a r a c t e r i s t i c s o f the m i l l i n g c u t t e r against power spectrum o f c u t t i n g f o r c e measured i n face m i l l i n g
The cross s e n s i t i v i t y f o r t h e c i r c u m f e r e n t i a l d i r e c t i o n by load, b o t h i n the t h r u s t f o r c e d i r e c t i o n and i n t h e feed force direction, does n o t appear a t a l l up t o 294 N I t seems t o be r e p o n s i b l e f o r d e t e c t i n g t h e s t r a i n o n l y due t o bending by t h e p r i n c i p l e force. I n addition, attention i s paid t o the s t a b i l i t y , by s e r i a l l y i n s e r t i n g a resistance f o r balance adjustment o f b r i d g e c i r c u i t and by compensating t h e s h i f t of I t i s f a i r l y w e l l confirmed zero p o i n t due t o temperature r i s e . t h a t t h i s measuring device meets t h e requirements o f t h e fundamental p r o p e r t y as a t o o l dynamometer. This device i s a l s o a v a i l a b l e f o r measurement o f t h r u s t and feed forces by changing t h e place o f gauges.
.
3.2
Experimental Results
Figure 10 i n d i c a t e s measured c u t t i n g forces o f p l a i n carbon s t e e l i n t h e c i r c u m f e r e n t i a l d i r e c t i o n : Fig. lO(a) t h e case o f up m i l l i n g , Fig. 10(b) down m i l l i n g and Fig. l O ( c ) up it is and down m i l l i n g . I n t h e case o f up m i l l i n g . c l e a r l y seen t h a t t h e c u t t i n g f o r c e g r a d u a l l y increases w i t h As t h e t o o l breaks away from i n c r e a s i n g c u t t i n g thickness. workpiece a t t h e maximum c u t t i n g force, t h e v i b r a t i o n o f t o o l takes place as c l e a r l y seen i n t h e f i g u r e . It i s marked t h a t t h e c u t t i n g f o r c e a c t i n g t o t o o l becomes negative i n a moment. I n t h e case o f down m i l l i n g , t h e maximum c u t t i n g f o r c e appears, i n c o n t r u s t w i t h up m i l l i n g , a t t h e beginning o f cutting, and decreases w i t h decreased c u t t i n g thickness. Figure 1O(c) corresponds t o a combination o f Fig. lO(a) and (b), i.e., t h e c u t t i n g f o r c e increases, presents i t s maximum value on t h e way, and then decreases.
I
0
20
CU'TING Fig. 8
A whole view o f c u t t i n g f o r c e measurement system
(a)
40
TIME
50
80
(msecl
Up m i l l i n g o f p l a i n carbon s t e e l
63
-
Cutting speed : 218 mlrnLn
Feed
:
Depth of c u t
:
Z
0.13 w l t o o t h 1 w
I
: 200
Cuttin6 #peed Feed Depth of cut
: 218 m / d n : 0.13 m l t o o c h : 1 rn
E Q
" I y 100..
II-
lp~"
3
0.
!
-2
-50 0
20
CUTTING (b)
40 TIME
60
60
40
20
0
80
CUTTING TIME
[msec)
Down m i l l i n g o f cast i r o n
(b)
Down m i l l i n g o f p l a i n carbon s t e e l
-
C u t t i n g speed : 218 m l m i n Feed : 0.13 m n l t o o t h Depth of c u t : 1 mn
154 m l r n i n
C u t t i n g speed Feed Depth
I
80
(rnsecl
:
of
0.12 m l t o o t h I m
cut
-1
g 100
U
,I
I-c
I-
+ 3
u
-501
0
20
(c) Fig. 10
60
40
CUTTING TIME
(c)
Up and down m i l l i n g o f p l a i n carbon s t e e l
Example o f t r a n s i e n t c u t t i n g forces measured by use o f t h e measurement system carbon s t e e l a r e fluctuate during
The new method i s proposed t o measure c u t t i n g forces o f a r o t a t i n g t o o l from t h e t o o l side w i t h o u t contact, making use o f o p t i c a l data transmission, and a measuring device has been developed, based on t h e method proposed. C u t t i n g experiments by use o f t h e measuring device l e d t o t h e f o l l o w i n g conclusions: ( 1 ) I t i s experimentally proved t h a t t h e method has advantage t o take c u t t i n g forces o u t o f a machine t o o l w i t h r o t a t i n g t o o l w i t h o u t contact.
(2) The device has t h e p o t e n t i a l o f high speed data sampling a t maximum 22000 s e t s o f data per second, which i s v a l i d
I
]
:200
K
D
I
Up and down m i l l i n g o f c a s t i r o n
Example o f t r a n s i e n t c u t t i n g f o r c e measurement o f cast i m n
enough t o analyze t r a n s i e n t c u t t i n g intermittent cutting.
phenomena such
as an
( 4 ) The device developed i s a p p l i c a b l e t o analyze a v a r i e t y o f t r a n s i e n t phenomena o f r o t a t i n g body such as temperature, torque, etc., as w e l l as c u t t i n g f o r c e by exchanging a sensor.
References [l]G.H.Gautschi : C u t t i n g Force i n Maching and t h e i r Routine Measurement with Mu1ti-Component P i e z o - E l e c t r i c Force transducers, Proc. of 12nd I n t . MTDR Conf. (1971) 113
[Z] S. Kato e t a1 : C h a r a c t e r i s t i c s o f C u t t i n g Force i n P l a i n M i l l i n g Operation Using a H e l i c a l Cutter, Pmc. o f 1 7 t h I n t . MTDR Conf. (1976) 117
Cutting speed : 154 r n l m i n : 0.12 m l t o o t h 2;;h of c u t : 1 om
[3] K. Nakazawa : Improvement o f AdaDtive Control o f M i l l i n a Machine by Non-Contact C u t t i n g Force Detector, Proc. 0; 1 6 t h I n t . MTDR Conf. (1975) 109 [4] A. B r a n d s t z t t e r : E i n Adaptive-Control-Optimization System fiir das FrBsen, Springer-Verlag, B e r l i n , (1981) 47
20
0
40
CUTTING TIME (a)
64
Fig. 11
80
60 [msecl
(3) Measured c u t t i n g forces by use o f t h e device c l e a r l y present t h e t r a n s i e n t s t a t e , and t h e p r a t i c a l use o f t h e device i s confirmed,
Conclusions
-
40
CUTTING TIME
(msecl
As regards cast iron, s i m i l a r r e s u l t s t o obtained except t h a t c u t t i n g forces l a r g e l y c u t t i n g as i s seen Fig. l l ( a ) , ( b ) and ( c ) . 4.
80
I
20
0
Up m i l l i n g o f c a s t i r o n
60 (rnsec)
80
- Submitted by T. Sata (1). The University
Sumnary : The study proposes a new way t o a c c u r a t e l y measure t r a n s i e n t c u t t i n g forces o f a r o t a t i n g t o o l such as a m i l l i n g c u t t e r from t h e s i d e o f t o o l . The transmission o f c u t t i n g forces through a s l i p r i n g o r a FM telemeter i s l i a b l e t o be a f f e c t e d by noises. Therefore, a device t o o b t a i n r e l i a b l e c u t t i n g data has been r e q u i r e d t o analyze t h e c u t t i n g phenomena. I n t h e measurement system developed, a m p l i f i e d output s i g n a l s from s t r a i n gauge bridges a r e d i g i t i z e d using an A0 converter and then converted t o continuous s e r i a l data streams t o o p t i c a l l y t r a n s m i t them o u t s i d e a machine t o o l by use o f LEO. Received s e r i a l data streams by a photo sensor a r e conversely r e s t o r e d t o p a r a l l e l data, which a r e inmediately processed by a personal computer. The t r a n s i e n t c u t t i n g forces can be measured w i t h o u t any trouble. As a r e s u l t , t h i s method was found t o be very p r a c t i c a l and a l s o a p p l i c a b l e t o a v a r i e t y o f measuring f i e l d s r e q u i s i t e f o r non-contacting data transmission,
1.
Introduction 2.1
The accurate measurement o f c u t t i n g forces i s e s s e n t i a l t o analyze c u t t i n g phenomena. The way o f c u t t i n g f o r c e measurement can be d i v i d e d i n t o two groups. One i s t o measure t h e c u t t i n g f o r c e s a c t i n g on a t o o l through a d e t e c t o r attached t o t h e t o o l , and t h e o t h e r through the d e t e c t o r attached t o a workpiece o r a workpiece holder. The former i s p a r t i c u l a r l y important i n t h e l i g h t o f d i r e c t measurement o f c u t t i n g forces e x e r t i n g an e f f e c t on t o o l . I n case o f a f i x e d t o o l such as a l a t h e , measuring methods from t h e t o o l s i d e have been established, and various devices a r e on t h e market [l] Compared t o a f i x e d t o o l , most measurements o f a r o t a t i n g t o o l , such as m i l l i n g o r d r i l l i n g t o o l . a r e performed on t h e s i d e o f a workpiece, since t h e r o t a t i o n of a t o o l d i s t r e s s e s t h e transmission o f measured data. Up u n t i l now, measured data o f r o t a t i n g t o o l s have been t r a n s m i t t e d u t i l i z i n g special c o n t a c t mechanism such as s l i p r i n g and mercury contact, however, i t i s d i f f i c u l t t o d i s t i n g u i s h t h e change o f c u t t i n g forces from t h a t o f contact resistance, e s p e c i a l l y i n i n t e r m i t t e n t c u t t i n g . The higher a s p i n d l e r o t a t e s , the l a r g e r t h e c o n t a c t r e s i s t a n c e changes, which r e s u l t s i n t h e i m p o s s i b i l i t y o f measurement. Another p o s s i b i l i t y o f data transmission i s concerned w i t h non-contacting way, f o r examples, FM telemeter, l i g h t beam 121 and magnetic c o i l [31 The study aims a t c o n t r i v i n g and developing a new device t o a c c u r a t e l y t r a n s m i t d i g i t i z e d measured data w i t h o u t being affected by noises and d i s t o r t i o n d u r i n g trasmission, making use o f l i g h t signals. L i g h t s i g n a l s as transmission means have n o t p r e v i o u s l y been r e p o r t e d except f o r an example applied t o torque I n a d d i t i o n , the data transmission i n an adaptive c o n t r o l [4] device i s e a s i l y d e a l t with, since measured data a r e t r a n s m i t t e d i n a s i n g l e d i r e c t i o n by l i g h t as s e r i a l data streams. The device w i t h s t r a i n gauges f i x e d on t h e t o o l as a c u t t i n g f o r c e transducer i s planned and applied t o the cutting force measurement on a v e r t i c a l m i l l i n g machine. Consequently, i t i s proved t h a t c u t t i n g f o r c e data a r e r e l i a b l y t r a n s m i t t e d and received
.
.
.
.
2.
Detection and Transmission o f C u t t i n g Forces
The block diagram o f transmission section, which corresponds t o t h e f i r s t h a l f o f t h e measurement system, i s i n d i c a t e d i n Fig. 2. The c u t t i n g forces a c t i n g on a t o o l a r e replaced w i t h an e l e c t r i c r e s i s t a n c e change by use o f s t r a i n gauge bridges. whose o u t p u t v o l t a g e i s several mV. Therefore, t h e output v o l t a g e from s t r a i n gauge b r i d g e s must be a m p l i f i e d t o have enough voltage t o an A0 converter. The a m p l i f i e r c o n s i s t s o f f i v e OP a m p l i f i e r s t o form a h i g h impedance d i f f e r e n t i a l a m p l i f i e r c i r c u i t , whose a m p l i f i c a t i o n f a c t o r depends on t h e p r e d i c t e d maximum c u t t i n g force. Next, an a m p l i f i e d sampled voltage i s converted i n t o d i g i t a l form by AOC ( AOC-EH8b. OATEL ). It has an & b i t r e s o l u t i o n capacity, t h e f u l l - s c a l e range o f t h e incoming analog signal i s 0 t o 10 V i n u n i p o l a r i t y use and -5 t o +5 V i n b i p o l a r i t y use, and t h e conversion time i s 4 vsec. The d i g i t i z e d s i g n a l s can be o u t p u t e i t h e r i n s e r i a l fonn o r i n p a r a l l e l form. Although s e r i a l o u t p u t form i s convenient t o t r a n s m i t s e r i a l l i g h t s i g n a l s i n t h e outside, t h e p a r a l l e l o u t p u t form, however, i s selected, t a k i n g account o f t h e response o f e l e c t r i c p a r t s used i n t h e transmission and r e c e i v e r c i r c u i t . To t r a n s m i t d i g i t i z e d s i g n a l s from t h e center o f t h e r o t a t i n g s p i n d l e o f a m i l l i n g machine, d i g i t i z e d s i g n a l s i n p a r a l l e l form must be converted i n t o s e r i a l form by use o f a p a r a l l e l - t o - s e r i a l converter ( PSC ). The l e a d i n g s e c t i o n o f t h e PSC consists of Parallel t h r e e 4 - b i t s h i f t r e g i s t e r s i n t h e cascade connection. s i g n a l s being o u t p u t from ADC a r e i n t u r n converted i n t o s e r i a l signals, synchronizing t h e frequency o f a pulse generator f o r s h i f t . The conversion r a t e i s a d j u s t a b l e by use o f t h e generator. The frequency of t h e p u l s e generator used i n t h e study i s 100 KHz, t a k i n g t h e response time o f a photo sensor i n t o account. As a r e s u l t , s e r i a l s i g n a l s a r e obtained w i t h t h e time i n t e r v a l of 10 vsec. I n t h e s e r i a l data, i t i s impossible t o recognize t h e s t a r t p o i n t and end p o i n t o f data. Thus, i t i s necessary t o n o t i f y t h e r e c e i v e r s e c t i o n o f t h e s t a r t p o i n t f o r every data. As a countermeasure t o t h e s i t u a t i o n , a modified synchronous communication procedure i s used, which provides t h e proper data by adding a s t a r t b i t and an end b i t f o r each data. I n t h e study, o n l y t h e s t a r t b i t i s added t o each data w i t h 8 - b i t .
S t r u c t u r e o f Wasurement System
Figure 1 shows a schematic diagram o f t h e s t r u c t u r e o f measurement system. As a machine t o o l w i t h a r o t a t i n g t o o l , a A transmission s e c t i o n o f v e r t i c a l m i l l i n g machine i s used. c u t t i n g forces i s b u i l t w i t h i n t h e main s p i n d l e o f machine, and t h e r e c e i v e r o f l i g h t s i g n a l s and t h e r e s t o r a t i o n s e c t i o n a r e provided o u t s i d e t h e m i l l i n g machine. Restored measured data a r e t e m p o r a r i l y stored i n t h e m m r y area o f a personal computer, and then converted t o c u t t i n g forces.
M
STRAIN_GAUGES
S/H:SAMPLE AND HOLD ADC:ANALOG TO D I G I T A L CONVERTER PSC:PARALLEL TO SERIAL CONVERTER
Fig. 2
S c h e m t i c diagram o f t r a n s m i t t i n g c u t t i n g f o r c e s o u t s i d e t h e machine t o o l by use o f LEO
Figure 3 represents a time c h a r t o f ADC and PSC i? the transmission section, where two o s c i l l a t o r s a r e provided, 1 .e., f o r A0 conversion pulse @ and l f o r s h i f t pulse $2. They a r e no sooner generated than t h e power source i s switched on. A conversion pulse i n d i c a t e d i n time c h a r t (a). r e s e t s and s t a r t s t h e conversion. Time c h a r t ( b ) shows t h e conversion end signal, which r a i n s h i g h d u r i n g conversion and becomes low a t t h e end o f conversion. Both time c h a r t ( c ) and ( d ) PSC i n p u t s p a r a l l e l data and outputs i n d i c a t e those o f PSC. s e r i a l data, as shown i n time c h a r t ( c ) . I n t h e study. t o s i m p l i f y t h e c i r c u i t , t h e i n v e r t e d s i g n a l of t h e conversion end s i g n a l i s used as a c o n t r o l mode s e l e c t i o n signal. Namely, a t t h e time when p a r a l l e l data a r e o u t p u t a f t e r conversion. s i g n a l ( c ) a t a h i g h l e v e l enables t h e s h i f t r e g i s t e r t o accept p a r a l l e l i n p u t data, and t h e s i g n a l a t a low l e v e l t o output s e r i a l data, synchronizing 9 1 as shown i n time c h a r t (d).
el,
Fig. 1
Block diagram o f t h e c u t t i n g f o r c e measurement system o f rotating tool
Annals of the CIRP Vol. 33/1/1984
61
The s e r i a l data a r e emitted o u t s i d e by a LED, which has sharp d i r e c t i o n a l c h a r a c t e r i s t i c s w i t h peak wave l e n g t h o f 9400 A.
-
i n p u t i f t h e c u r r e n t memory address i s greater than the end address o f data. I f n o t s o , t h e program increases the c u r r e n t memory address by one, outputs a set signal, and r e t u r n s t h e r o u t i n e t o send a s e t pulse. The minimum sampling time i n t e r v a l by t h i s program i s 45 psec, a s was already mentioned.
LATCHED AND V A L I D
( b,
tUD
OF
COWtRSION
I
1
:...-
I CONYERSIOS T 1 M E : I u S
PARALLEL UOllli SHIFT MODE
I
S T A R 1 PULSE
0
I
ALLOCATE I/O CONTROL MODE ENTRY ADDRESS g THRESHOLD
DATA READY
Fig. 3 2.2
INPUT DATA FROM SPC
Timing diagram o f ADC and PSC
I
Emitted s e r i a l data a r e detected by a photo t r a n s i s t e r attached over the coaxial center o f LED a s seen i n Fig. 4. The photo t r a n s i s t e r w i t h a maximum s e n s i t i v i t y o f 8000 i s selected i n order t h a t i t s wave l e n g t h i s as near t o t h a t o f LED as possible. Detected s e r i a l data a r e a m p l i f i e d enough w i t h i n t h e range t o be d i g i t a l l y processed. A zenar diode i s i n s e r t e d t o p r o t e c t e l e c t r i c p a r t s from being destroyed when t h e l e v e l o f a s i g n a l becomes higher than t h a t o f TTL. Signals, which pass through a wave r e c t i f i c a t i o n c i r c u i t , then come t o a s e r i a l - t o - p a r a l l e l converter ( SPC ) which performs an inverse a c t i o n a g a i n s t PSC. The SPC consists o f a s t a r t b i t search f u n c t i o n o f s e r i a l data, a s h i f t r e g i s t e r and a s h i f t pulse generator. The s t a r t b i t search i s t o d e t e c t a s t a r t assigned a t t h e t o p o f every coming s e r i a l data. The s t a r t s i g n a l being found, SPC keeps t h e gate o f the search c i r c u i t closed d u r i n g t h e time t o take i n a s e t o f data t o avoid t h e overlap o f measured data and, a t t h e same time, outputs a pulse generation s t a r t s i g n a l t o t h e s h i f t pulse generator. The s h i f t pulse generator generates n o t o n l y pulse t r a i n s necessary f o r t h e s h i f t a c t i o n , but a l s o l a t c h signal r e q u i s i t e f o r m a i n t a i n i n g r e s t o r e d data i n t h e l a t c h c i r c u i t a f t e r s h i f t . The s h i f t r e g i s t e r i s t h e same one as i s used i n t h e PSC. Restored data i n t h e l a t c h c i r c u i t w a i t f o r being taken by t h e personal computer PC8001mk.
NO
d
1
Receiving o f Emitted Data and Processing
I
1
-
7
,1
YES
STORE DATA TO MEMORY I
STOP
OUTPUT RESET FLAGS
I Fig. 5
2.4
Flowchart f o r s t o r i n g measured data t o a personal computer
I n s t a l l a t i o n o f Measuring Devices
A c o n f i g u r a t i o n o f the main s p i n d l e o f a v e r t i c a l m i l l i n g machine w i t h t h e measuring device i s i l l u s t r a t e d i n Fig. 6. A sensor, ADC, PSC, two pulse generators, LED and power source a r e mounted on t h e disc, which i s f i x e d on the t o p o f t h e s p i n d l e by a draw-in b o l t and a nut, dnd r o t a t e d together w i t h t h e r o t a t i o n o f t h e s p i n d l e as seen i n Fig. 7. The i n f l u e n c e o f c e n t r i f u g a l f o r c e counts f o r nothing i n t h e range o f low r o t a t i o n , however, i n the range o f h i g h r o t a t i o n i t may cause t h e a b e r r a t i o n o f beam a x i s due t o t h e i r unbalanced layout. To d r i v e t h e device, two kinds o f voltage, i.e., i 1 5 V and 5 V, a r e required, which a r e provided by a DC-DC converter from a lead storage b a t t e r y ( 12 Y , 6 A, 22 N ). Therefore, t h e heavy b a t t e r y i s arranged i n t h e center o f t h e disc, and the remaining p a r t s a r e l a i d o u t
(MV\SURLHGI EQUI PMENT
, Fig. 4
STORAGE DC-DC BATTERY CONVERT'ER
Schematic diagram o f r e c e i v i n g s e r i a l data by use o f a photo t r a n s i s t e r
2.3
Data A c q u i s i t i o n Program
A f l o w c h a r t o f t h e data a c q u i s i t i o n i s presented i n Fig. 5. A t f i r s t , an i n p u t / o u t p u t c o n t r o l signal, a data i n p u t form, an assignment o f t h e s t a r t and end address f o r measured data t o be stored, and a t h r e s h o l d value a r e input. A r e s e t pulse i s output a t t h e r e s e t terminal o f t h e l a t c h c i r c u i t t o i n i t i a l i z e , then a s e t pulse i s sent t o search f o r t h e i n p u t o f measured data. I f t h e r e i s no data i n t h e l a t c h c i r c u i t , t h e program once more goes back t o t h e r o u t i n e t o send a s e t pulse. I f t h e r e i s an i n p u t , i t i s taken i n as a set o f data, and compared w i t h t h e t h r e s h o l d value. I f i t i s g r e a t e r than the threshold value, i t i s stored i n t h e memory area as a s e t o f measured data. The threshold value i s s e t up t o prevent data from noises i n case o f t h e h i g h a m p l i c a t i o n f a c t o r . Comparing t h e c u r r e n t memory address w i t h t h e end address f o r data t o be stored, t h e program f i n i s h e s t h e data
62
A-A
SECTION
GAUGES
Fig. 6
Set-up o f transmission apparatus mounted on the t o p o f t h e main s p i n d l e o f a v e r t i c a l m i l l i n g machine
The overhang o f t h e t o o l holder i s 33.3 mn long. Two semiconductor s t r a i n gauges and two r e s i s t a n c e s t r a i n gauges a r e niounted 23 mm away from t h e top o f t h e t o o l t o c o n s t r u c t a b r i d g e c i r c u i t as a sensor. The dynamic c h a r a c t e r i s t i c s o f a measurement system i S of importance i n i n t e r m i t t e n t c u t t i n g such as m i l l i n g . Thus, the compliance i s measured, i n f l i c t i n g an impulse i n t h e c i r c u m f e r e n t i a l d i r e c t i o n upon t h e t o o l w i t h an a c c e l e r a t i o n pickup. An experimental r e s u l t i s shown i n Fig. 9, together w i t h a power spectrum o f t h e c u t t i n g force. Dominant components o f t h e power spectrum o f t h e c u t t i n g f o r c e g e n e r a l l y l i e w i t h i n the range o f 50 Hz. On t h e o t h e r hand, t h e compliance o f t h e measurement system has a f i r s t n a t u r a l frequency near 1000 Hz. The dynamic c h a r a c t e r i s t i c s , thus, a r e o f no concern i n t h i s measurement system. The r e l a t i o n between a p p l i e d l o a d and output signal from sensor i n d i c t e s a good l i n e a r i t y up t o 784 N
.
Fig. 7
View o f t h e s p i n d l e head w i t h transmission appratus and t h e toGl w i t h s t r a i n gauges
on b o t h sides o f t h e b a t t e r y . The cables t o supply power t o s t r a i n gauges bridges and t o take i n i t s o u t p u t s i g n a l a r e spread through a groove along t h e draw-in b o l t . A f t e r being adjusted t o p u t i t s beam a x i s r i g h t l y on t h e s p i n d l e axis, LEO i s f i x e d by a screw. As f o r t h e r e c e i v e r section, a photo t r a n s i s t e r i s c o r r e c t l y s e t over the c e n t e r of LEO. A whole view o f t h e measurement system i s shown i n Fig. 8. 3.
Weasurement o f C u t t i n g Forces
3.1
I n s p e c t i o n o f Measuring Device
I n o r d e r t o i n s p e c t t h e measuring device developed i n t h e study, c u t t i n g forces i n t h e c i r c u m f e r e n t i a l d i r e c t i o n , i.e., p r i n c i p l e c u t t i n g force, a r e measured, using a v e r t i c a l m i l l i n g machine. The m i l l i n g machine, t o o l and c u t t i n g c o n d i t i o n used i n t h e experiments a r e as f o l l o w s : M i l l i n g machine: N i i g a t a Tekko Co. Ltd. Tool: c a r b i d e i n s e r t P20 ( -5,5,-6,6,15,15,0.8 ) WorkDiece m a t e r i a l : D l a i n carbon s t e e l S55C ( C = 0.55 Z ) and c a s t i r o n ( FC25 ) C u t t i n g speed: 218 m/min ( S55C ), 154 m/min ( FC25 ) Feed r a t e : 0.13 n / t o o t h ( 555C ), 0.12 mn/tooth ( FC25 ) Depth o f c u t : 1 n
-
Fig. 9
Dynamic c h a r a c t e r i s t i c s o f the m i l l i n g c u t t e r against power spectrum o f c u t t i n g f o r c e measured i n face m i l l i n g
The cross s e n s i t i v i t y f o r t h e c i r c u m f e r e n t i a l d i r e c t i o n by load, b o t h i n the t h r u s t f o r c e d i r e c t i o n and i n t h e feed force direction, does n o t appear a t a l l up t o 294 N I t seems t o be r e p o n s i b l e f o r d e t e c t i n g t h e s t r a i n o n l y due t o bending by t h e p r i n c i p l e force. I n addition, attention i s paid t o the s t a b i l i t y , by s e r i a l l y i n s e r t i n g a resistance f o r balance adjustment o f b r i d g e c i r c u i t and by compensating t h e s h i f t of I t i s f a i r l y w e l l confirmed zero p o i n t due t o temperature r i s e . t h a t t h i s measuring device meets t h e requirements o f t h e fundamental p r o p e r t y as a t o o l dynamometer. This device i s a l s o a v a i l a b l e f o r measurement o f t h r u s t and feed forces by changing t h e place o f gauges.
.
3.2
Experimental Results
Figure 10 i n d i c a t e s measured c u t t i n g forces o f p l a i n carbon s t e e l i n t h e c i r c u m f e r e n t i a l d i r e c t i o n : Fig. lO(a) t h e case o f up m i l l i n g , Fig. 10(b) down m i l l i n g and Fig. l O ( c ) up it is and down m i l l i n g . I n t h e case o f up m i l l i n g . c l e a r l y seen t h a t t h e c u t t i n g f o r c e g r a d u a l l y increases w i t h As t h e t o o l breaks away from i n c r e a s i n g c u t t i n g thickness. workpiece a t t h e maximum c u t t i n g force, t h e v i b r a t i o n o f t o o l takes place as c l e a r l y seen i n t h e f i g u r e . It i s marked t h a t t h e c u t t i n g f o r c e a c t i n g t o t o o l becomes negative i n a moment. I n t h e case o f down m i l l i n g , t h e maximum c u t t i n g f o r c e appears, i n c o n t r u s t w i t h up m i l l i n g , a t t h e beginning o f cutting, and decreases w i t h decreased c u t t i n g thickness. Figure 1O(c) corresponds t o a combination o f Fig. lO(a) and (b), i.e., t h e c u t t i n g f o r c e increases, presents i t s maximum value on t h e way, and then decreases.
I
0
20
CU'TING Fig. 8
A whole view o f c u t t i n g f o r c e measurement system
(a)
40
TIME
50
80
(msecl
Up m i l l i n g o f p l a i n carbon s t e e l
63
-
Cutting speed : 218 mlrnLn
Feed
:
Depth of c u t
:
Z
0.13 w l t o o t h 1 w
I
: 200
Cuttin6 #peed Feed Depth of cut
: 218 m / d n : 0.13 m l t o o c h : 1 rn
E Q
" I y 100..
II-
lp~"
3
0.
!
-2
-50 0
20
CUTTING (b)
40 TIME
60
60
40
20
0
80
CUTTING TIME
[msec)
Down m i l l i n g o f cast i r o n
(b)
Down m i l l i n g o f p l a i n carbon s t e e l
-
C u t t i n g speed : 218 m l m i n Feed : 0.13 m n l t o o t h Depth of c u t : 1 mn
154 m l r n i n
C u t t i n g speed Feed Depth
I
80
(rnsecl
:
of
0.12 m l t o o t h I m
cut
-1
g 100
U
,I
I-c
I-
+ 3
u
-501
0
20
(c) Fig. 10
60
40
CUTTING TIME
(c)
Up and down m i l l i n g o f p l a i n carbon s t e e l
Example o f t r a n s i e n t c u t t i n g forces measured by use o f t h e measurement system carbon s t e e l a r e fluctuate during
The new method i s proposed t o measure c u t t i n g forces o f a r o t a t i n g t o o l from t h e t o o l side w i t h o u t contact, making use o f o p t i c a l data transmission, and a measuring device has been developed, based on t h e method proposed. C u t t i n g experiments by use o f t h e measuring device l e d t o t h e f o l l o w i n g conclusions: ( 1 ) I t i s experimentally proved t h a t t h e method has advantage t o take c u t t i n g forces o u t o f a machine t o o l w i t h r o t a t i n g t o o l w i t h o u t contact.
(2) The device has t h e p o t e n t i a l o f high speed data sampling a t maximum 22000 s e t s o f data per second, which i s v a l i d
I
]
:200
K
D
I
Up and down m i l l i n g o f c a s t i r o n
Example o f t r a n s i e n t c u t t i n g f o r c e measurement o f cast i m n
enough t o analyze t r a n s i e n t c u t t i n g intermittent cutting.
phenomena such
as an
( 4 ) The device developed i s a p p l i c a b l e t o analyze a v a r i e t y o f t r a n s i e n t phenomena o f r o t a t i n g body such as temperature, torque, etc., as w e l l as c u t t i n g f o r c e by exchanging a sensor.
References [l]G.H.Gautschi : C u t t i n g Force i n Maching and t h e i r Routine Measurement with Mu1ti-Component P i e z o - E l e c t r i c Force transducers, Proc. of 12nd I n t . MTDR Conf. (1971) 113
[Z] S. Kato e t a1 : C h a r a c t e r i s t i c s o f C u t t i n g Force i n P l a i n M i l l i n g Operation Using a H e l i c a l Cutter, Pmc. o f 1 7 t h I n t . MTDR Conf. (1976) 117
Cutting speed : 154 r n l m i n : 0.12 m l t o o t h 2;;h of c u t : 1 om
[3] K. Nakazawa : Improvement o f AdaDtive Control o f M i l l i n a Machine by Non-Contact C u t t i n g Force Detector, Proc. 0; 1 6 t h I n t . MTDR Conf. (1975) 109 [4] A. B r a n d s t z t t e r : E i n Adaptive-Control-Optimization System fiir das FrBsen, Springer-Verlag, B e r l i n , (1981) 47
20
0
40
CUTTING TIME (a)
64
Fig. 11
80
60 [msecl
(3) Measured c u t t i n g forces by use o f t h e device c l e a r l y present t h e t r a n s i e n t s t a t e , and t h e p r a t i c a l use o f t h e device i s confirmed,
Conclusions
-
40
CUTTING TIME
(msecl
As regards cast iron, s i m i l a r r e s u l t s t o obtained except t h a t c u t t i n g forces l a r g e l y c u t t i n g as i s seen Fig. l l ( a ) , ( b ) and ( c ) . 4.
80
I
20
0
Up m i l l i n g o f c a s t i r o n
60 (rnsec)
80