# detailed presentation on geometry inspection (RG)

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```Reconfigurable Inspection Machine
(RIM)
Overview
•
•
•
•
The RIM and the inspection methodology
What can the RIM measure and how?
Comparison of measurement results
Conclusion and future work
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
2
Reconfigurable Inspection
Machine (RIM)
Engine cylinder head
Vision
system
Laser
probes
Slide system
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
3
General Measurement Capabilities of
the RIM
• Dimensional:
Distance between edges, between surfaces or between holes
Dimensions of holes and inclination angles of chamfers
• Geometrical:
Flatness of surfaces
Parallelism between surfaces
• Surface Texture:
Porosity defects on a surface
Surface roughness (ongoing research)
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
4
RIM and Conventional CMM
Measurements Differ. Why?
• Different measurements due to contact
probe radius.
• Different point densities.
• Different flatness calculation algorithms.
• Device dependant characteristics.
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
5
Interpretation Is Required for
Contact Probe. Why?
x*j
o( x*j )
R
P
e*j
*
j
z( x )
Actual
surface
point
z*j
Interpreted
measurement
point
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
6
The “Virtual Ball” Algorithm
x*j
xi
o( x*j ) 
max
x*j  R  xi  x*j  R
H ( x , x )
i
*
j
R
H ( xi , x )  R  ( xi  x )  zi
*
j
2
* 2
j
Interpreted height: o( x*j )  R
x*j  R  xi  x*j  R
Ball
contact
point
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
7
Measurement example with
Virtual Ball interpretation
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
8
Flatness Calculation by RIM
“Virtual ball” interpreted points
2 planes
Parallel to best fit plane
That confine the
Measured points
Flatness
LSQ fit plane to
Measured points
Laser measured points
Filter outliers outside 3 zone
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
9
Width and Parallelism
Calculation by RIM
“Virtual ball” interpreted points
joint &amp; cover faces
Point confining planes
parallel to datum
+
Parallelism
- Width
Best fit plane of cover face
parallel to datum
Daturm, LSQ fit plane to
joint face measured points
Laser measurements cover face
Laser measurements joint Filter
face outliers outside 3 zone
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
10
Measurement Results
• Parts were measured by Inspec using a CMM.
• Results compared RIM measurements:
–
–
–
–
–
Distance between joint and cover face
Parallelism between joint and cover face
Flatness of joint and cover face
Hole diameter
Distance between holes centers
• Manual measurements serve as additional
reference
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
11
Result Comparison
Manual
Inspection
Inspec
Part
RIM
RIM
Laser
measurements
reference
measurements
CMM
measurements
Comparison
Vision
measurements
Interpretation
using the
Simulated
contact probe
measurements
“Virtual ball”
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
12
Inspec Measurements
• Measurements were obtained in two methods:
• Point on 3 lines (yellow)
• Point spread (yellow + blue)
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
13
Manual Measurements
• Parts width was measured manually with 25&micro;m
accuracy.
• Part width was measured in 8 points and
parallelism was deduced.
• Hole diameters were measured twice.

NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan

14
Part Width
Inspec
(mm)
RIM
(mm)
Difference
(mm)
Part 1
119.550
119.531
0.019
Part 3
118.975
119.106
-0.131
Part 4
118.332
119.011
-0.679
Part 5
119.140
119.132
0.008
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 119 0.2
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
15
Part Width - Detailed
Inspec
(mm)
RIM
mean
(mm)
RIM Plus
tolerance
(mm)
RIM Minus
tolerance
(mm)
Manual
(mm)
Part 1
119.550
119.531
0.060
-0.092
Part 3
118.975
119.106
0.038
-0.038
119.115
Part 4
118.332
119.011
0.630
-0.635
118.934
Part 5
119.140
119.132
0.407
-0.396
119.095
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 119 0.2
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
16
Parallelism Between Joint
and Cover Faces
Inspec
(mm)
RIM
(mm)
Difference
(mm)
Manual
(mm)
Part 1
0.063
0.116
-0.053
Part 3
0.975
0.035
0.940
0.030
Part 4
0.306
1.229
-0.923
0.870
Part 5
0.653
0.758
-0.105
0.480
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 0.100
//
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
17
Flatness of Joint Face
Inspec
(&micro;m)
RIM
(&micro;m)
Difference
(&micro;m)
Part 1
22
35
-13
Part 3
37
41
-4
Part 4
65
37
28
Part 5
48
46
2
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 100 &micro;m
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
18
Flatness of Cover Face
Inspec
(&micro;m)
RIM
(&micro;m)
Difference
(&micro;m)
Part 1
20
74
-54
Part 3
40
22
18
Part 4
27
44
-17
Part 5
22
22
0
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Allowed Tolerance : 100 &micro;m
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
19
Hole Diameter
Inspec
(mm)
RIM
(mm)
Difference
(mm)
Manual
(mm)
Part 1 - 1
16.032
16.128
-0.096
15.964
Part 4 - 1
16.103
15.966
0.137
16.027
Part 5 - 1
16.304
16.138
0.166
16.147
Part 1 - 2
16.022
16.036
-0.014
15.976
Part 4 - 2
16.031
16.043
-0.012
16.147
Part 5 - 2
16.248
16.193
0.055
16.147
2
Allowed Tolerance : 16.2  0.2 mm
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
20
1
Distance Between Holes
Inspec
(mm)
RIM
(mm)
Difference
(mm)
Part 1
305.991
305.768
0.223
Part 4
305.981
305.752
0.229
Part 5
305.984
305.803
0.181
Allowed Tolerance : 306  0.1 mm
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
21
Different number of probes
RIM
3 scan lines
(&micro;m)
RIM
2 scan lines
(&micro;m)
Difference
(&micro;m)
Part 1
35
31
4
Part 3
41
39
-2
Part 4
37
31
6
Part 5
46
46
0
values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)
Maximum deviation : 6 &micro;m
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
22
Conclusions
• Overall, laser measurements are in the same range
• The RIM may be used for process monitoring with a backup CMM.
• Differences may result from:
–
–
–
–
–
Different measurement methods
Different measurement environment
Different algorithms
Measurement uncertainties (imperfect calibration)
Human error (further testing required)
• Different number of probes per face (2 or 3) had negligible effect on
the results
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
23
Future Work
• Further result analysis.
• Repeating CMM measurements for
additional reference.
• Testing for repeatability and reliability.
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
24
Acknowledgements
• This research was supported in part by the NSF
Engineering Research Center for
Reconfigurable Machining Systems under the
grant EEC95-92125.
• The RIM project team.
• Dr. G. Sirat from Optimet.
• Cummins metrology department.
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
25
RIM Team
Project Team:
ERC:
Dr. Reuven Katz
Dr. Jacob Barhak
Students: Anuj Gupta
Glenny Tjahjadi
ERC
ERC
EECS
EECS
Dr. Steve Segall
Avinash Kalyanaraman
Yoou-Soon Kim
ERC
EECS
ME
Industrial partners:
Ashish Kachru
Robert J. Hogarth
Tim Lock
Cummins
GM
Vision Solutions, Inc.
NFS Engineering Research Center for Reconfigurable Manufacturing Systems
College of engineering, University of Michigan
26
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