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TRANSCRIPT
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Study on Improvement Methods of CMM (Coordinate Measuring Machine) in Workshop Environment – Correction of Squareness Error –
Tohru OHNISHI, Shotoku TAKASE and Kiyoshi TAKAMASU
In recent years, the CMM (Coordinate Measuring Machine) quickly has been spreading in the manufacturing industry. With this phenomenon, the environmental condition and installation site of CMMs has been changed from the temperature control room to the workshop environment and the production line without air conditioning. However, even in severe environment the demand to high accuracy measurements by CMM has been enhancing still more. Therefore, the methods to evaluate and realize the high accuracy measurements by CMM in workshop environment have been investigated. In this paper, we propose the evaluation and correction method of squareness errors using MCG (Machine Checking Gauge). Additionally the performances of CMM in workshop environment and temperature-controlled room are tested and corrected experimentally. From these results, we confirmed the availability of the proposed methods.
Key words: CMM, coordinate measuring machine, workshop environment, squareness error correction
1.
Coordinate Measuring MachineCMM
CMM
CMM
1) 2)
CMMCMM
CMM
CMM
CMM
1
2 CMM
3
1)
CMM 21
CMM
3)~6)
CMM CMMX Y Z
* 18 12 14 **
1-1-12*** 7-3-1
精密工学会誌,73(7),2007,818-822
4)~6)
Double Ball BarDBB
7)~10) DBB
DBB CMMMachine
Checking Gauge MCG6)
MCG CMMCMM
CMM CMMMCG
2. MCG CMM
2.1 MCG1 MCG MCG 4 mm
3
1.0 × 10-6/ 11
CMM
R x, y,z R 101 mm 151 mm 226 mm 380 mm 532 mm 685 mm
2 45 845 45 8 24
3 72R
CMM
CMM1 20
2.2 MCG72 xi, yi, zi
x0, y0, z0 txy, tzx, tzy
1 Sc
CMM 3 3CMM x, y, z
X, Y, Z X xxy XY y
Y txy z Z X
tzx z Z Y tzy 3
2 3 Sqr
n
iiiic rzzyyxxS
1
220
20
20 )()()( (1)
zttzttzZ
ztytztyYztytxtztyxX
zyzxzyzx
zyzyxy
zxxyzxxy
coscostantan1
sincossinsin
22
(2)
222
1
2 rztzytztyxS izyii
n
izxixyiiq (3)
2.3 MCG 100 mm 3
Fig. 1 Construction and set up of Machine Checking Gauge (MCG), R is length between centers of pivot ball and stylus ball 11)
Fig. 2 Location of measuring positions by MCG; 8 positions on 3 difference Z levels (+45º, 0º, -45º) 11)
Y
Z
plane
Fig. 3 Coordinate systems and squareness errors by 3 angle error parameters txy, tzx and tzy; XYZ is coordinate system without squareness errors and xyz is machine coordinate system with squareness errors.
R
probe
stylus ball
pivot ball
Kinematic pivot location
精密工学会誌,73(7),2007,818-822
0 4545 XY
4 4 a b45 txy
4 a c e 45 45X tzy 4 c d
e 45 45 Ytzx
3 SqMCG
3. CMM MCG
3.1CMM-1 CMM-2
MCG 1CMM CMM-1 CMM
CMM-2 CMM
5 CMM-1 CMM-2 MCG 101 mm 151 mm 226 mm 380 mm
CMM-2 380 mm CMM-1
tzx 101 mm 380 mm 3 sec
CMM-2 txy tzy tzxtzx 5 sec
CMM 1.5 sec 3.26 CMM-1 1
7 1
(µm
02468
10+Y
+X
-Y
-X
0°+45°-45°
(µm
02468
10+Y
+X
-Y
-X
0°+45°-45°
(µm
02468
10+Y
+X
-Y
-X
0°+45°-45°
(a) txy = 10 sec, tzy = 0 sec, tzx = 0 sec (b) txy = 10 sec, tzy = 1 sec, tzx = 2 sec (c) txy = 0 sec, tzy = 10 sec, tzx = 0 sec
(µm
02468
10+Y
+X
-Y
-X
0°+45°-45°
(µm
02468
10+Y
+X
-Y
-X
0°+45°-45°
(µm
02468
10+Y
+X
-Y
-X
0°+45°-45°
(d) txy = 0 sec, tzy = 0 sec, tzx = 10 sec (e) txy = 10 sec, tzy = 10 sec, tzx = 0 sec (f) txy = 10 sec, tzy = 10 sec, tzx = 5 sec
Fig. 4 Simulations of output geometrical errors from MCG measurements on different squareness errors
-8.0
-6.0
-4.0-2.0
0.02.0
4.06.0
8.0
101 151 226 380length of arm mm
txytzytzx
(a) CMM-1: normal accuracy and moving bridge type CMM
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
101 151 226 380length of arm mm
txytzytzx
(b) CMM-2: high accuracy and fixed bridge type CMM
Fig. 5 Relationship of length of MCG arm and squareness errors for 2 types of CMM (CMM-1 and CMM-2)
精密工学会誌,73(7),2007,818-822
1 0.6 sec 1
txy 1.1 sec tzy 2.5 sec tzx 0.5 sec
8
txy 0.07 sec/ tzy0.20 sec/ tzx 0.03 sec/
tzy 9CMM-1 tzy Z
X Y-bridge
tzy tzxZ X Z
CMM 1 sec 10 µmCMM
3 10
4 1 sec
2 1
4.
22 mm 25 83 mm 5 5
Retter
113 forward
13 1backward 12)~14) 1 30
XY YZ XZ5
CMM-1CMM-2 XZ MCG
52
CMM-1 4.4 sec 0.5 sec
10 CMM-1 XY CMM-2XZ
CMM-1 7.3 µm
Table 1 Specifications of CMM-1 and CMM-2
CMM-1 CMM-2 Modes of operation CNN CNN
Type of CMM Moving bridge Fixed bridge Measurement range (XYZ mm) 850 1000 600 700 550 400
Indicating digit (µm) 0.1 0.1 Type of probing system Touch trigger Parallel twin
Error of indication E (µm) 3.9 + 5L/1000 0.8 + L/800 Type of room ( ) Workshop 20±0.5
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
9:40 11:00 12:20 13:40 15:00time
14
16
18
20
22
24
26
28
30
txy tzytzx room
Fig. 6 Variation of squareness errors and room temperature in a day on CMM-1
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
Feb-04 Apr-04 Jun-04 Aug-04 Oct-04 Dec-04 Feb-05month
14
16
18
20
22
24
26
28
30
txy tzytzx room
Fig. 7 Variation of squareness errors and room temperature in a year on CMM-1
-8.0
-6.0
-4.0
-2.0
0.0
2.0
4.0
6.0
8.0
15 18 21 24 27 30
room temperture C
txytzytzx
Fig. 8 Relationship between room temperature and squareness errors
Fig. 9 Position of supporting air-bearings of CMM-1 (moving bridge type CMM)
X
Y
Z
Y-bridge
(X-column and Z-column) supporting air-bearingZ-column
精密工学会誌,73(7),2007,818-822
2.2 µm CMM-2 8.2 µm 2.8 µm
CMMCMM MCG
5.
CMMMCG
CMM MCG
1 MCG CMM
2 CMM CMM
3 MCG
CMM
1)1
73 2 2007 270. 2) 40 11 2001
801. 3) M. Abbe K. Takamasu S. Ozono Reliability on calibration of CMM
Measurement 33 2003 359. 4) W. Knapp, U. Tschudi, A. Bucher: Comparison of different artefacts
for interim coordinate-measuring machine checking, Precision
Engineering, 13, 4 1991 277. 5) P.C. Miguel, T. King, J. Davisc: CMM verification: a survey,
Measurement 17, 1 1996 1. 6) P.C. Miguel, T. King: Co-ordinate measuring machines Concept,
classification and comparison of performance tests, International Journal of Quality & Reliability Management, 12, 8 1995 48.
7) NC1 DBB
52 7 1986 1193. 8) NC
2 DBB52 10 1986 1739.
9)3 DBB
51 6 1986 1244. 10) Emmett Curran et al. Quick check error verification of coordinate
measuring machines, Journal of Materials Processing Technology, 155-156 2004 1207.
11) RENISHAW Catalog: The Machine Checking Gauge. 12) E. Trapet et al. Traceability of Coordinate Measurements According
to the Method of the Virtual Measuring Machine, PTB, 1998 .13)
67 2 2001 256. 14)
8 2005 .
Table 2 Result of squareness errors before and after squareness errors correction
type of CMM CMM-1 CMM-2plane XY YZ XZ XZ
before correction 4.4 4.1 -1.0 -4.9 winter after correction -0.2 -0.3 -0.3 -0.1 before correction 3.6 2.6 -0.8 - summer after correction -0.3 -0.5 0.2 -
before correction after correction
before correction after correction
(a) XY plane on CMM-1 in winter
before correction after correction
(b) XZ plane on CMM-2
Fig. 10 Positional errors of 25 sphere centers of ball plate before and after squareness errors correction
1div=10µm 1div=10µm
1div=10µm 1div=10µm
精密工学会誌,73(7),2007,818-822