reconfigurable inspection machine (rim). nfs engineering research center for reconfigurable...

Reconfigurable Inspection Machine(RIM)

NFS Engineering Research Center for Reconfigurable Manufacturing SystemsCollege of engineering, University of Michigan

2

Overview

• The RIM and the inspection methodology

• What can the RIM measure and how?

• Comparison of measurement results

• Conclusion and future work


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Reconfigurable Inspection Machine (RIM)

Laser probes

Slide system

Engine cylinder headVision system


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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)


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• Different measurements due to contact probe radius.

• Different point densities.

• Different flatness calculation algorithms.

• Device dependant characteristics.

RIM and Conventional CMM Measurements Differ. Why?


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Interpretation Is Required for Contact Probe. Why?

P

)( *jxo

*jx

*jz

R

)( *jxz

Interpreted measurement point

Actual surface point

*je


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The “Virtual Ball” Algorithm

*jx

ix

RxxRx *ji

*j

),(max)( **

** jiRxxRx

j xxHxojij

Ball contact point

i*ji

*ji zxxRxxH 22 )(),(

Rxo j )( *Interpreted height:

R


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Measurement example with Virtual Ball interpretation


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Flatness Calculation by RIM

Flatness

2 planesParallel to best fit planeThat confine the Measured points

LSQ fit plane toMeasured points

Filter outliers outside 3 zoneLaser measured points

“Virtual ball” interpreted points


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Width and Parallelism Calculation by RIM

Width

Point confining planesparallel to datum

Daturm, LSQ fit plane tojoint face measured points

Filter outliers outside 3 zoneLaser measurements joint face

“Virtual ball” interpreted pointsjoint & cover faces

Laser measurements cover face

Best fit plane of cover faceparallel to datum

-

+Parallelism


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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


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Result Comparison

Laser measurements

Simulated contact probe

measurements

RIM

Interpretation using the

“Virtual ball”

CMM measurements

Inspec

reference measurements

Manual Inspection

Vision measurements

ComparisonPart

RIM


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• Measurements were obtained in two methods:• Point on 3 lines (yellow)• Point spread (yellow + blue)

Inspec Measurements


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• Parts width was measured manually with 25µm accuracy.

• Part width was measured in 8 points and parallelism was deduced.

• Hole diameters were measured twice.

Manual Measurements


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values for filtered data (outliers outside 3 zone removed after virtual ball interpretation)

Allowed Tolerance : 119 0.2

Part WidthInspec(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


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Allowed Tolerance : 119 0.2

Part Width - DetailedInspec

(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


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Allowed Tolerance : 0.100

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

//


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Allowed Tolerance : 100 µm

Flatness of Joint FaceInspec(µm)

RIM (µm)

Difference (µm)

Part 1 22 35 -13

Part 3 37 41 -4

Part 4 65 37 28

Part 5 48 46 2


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Allowed Tolerance : 100 µm

Flatness of Cover FaceInspec(µm)

RIM (µm)

Difference (µm)

Part 1 20 74 -54

Part 3 40 22 18

Part 4 27 44 -17

Part 5 22 22 0


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Allowed Tolerance : 16.2 0.2 mm

Hole DiameterInspec(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

12


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Allowed Tolerance : 306 0.1 mm

Distance Between HolesInspec(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


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Maximum deviation : 6 µm

Different number of probesRIM

3 scan lines(µm)

RIM 2 scan lines

(µm)

Difference (µm)

Part 1 35 31 4

Part 3 41 39 -2

Part 4 37 31 6

Part 5 46 46 0


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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


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Future Work

• Further result analysis.

• Repeating CMM measurements for additional reference.

• Testing for repeatability and reliability.


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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.


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RIM Team

Project Team:

ERC: Dr. Reuven Katz ERC Dr. Steve Segall ERCDr. Jacob Barhak ERC

Students: Anuj Gupta EECS Avinash Kalyanaraman EECSGlenny Tjahjadi EECS Yoou-Soon Kim ME

Industrial partners:

Ashish Kachru Cummins Robert J. Hogarth GM Tim Lock Vision Solutions, Inc.

reconfigurable inspection machine (rim). nfs engineering research center for reconfigurable...

Documents

university of michigan

rim measurements

rim flatness

cover face flatness

points joint cover

datum parallelism slide

cover face parallelism

actual surface point