A generic closed-loop strategy for error compensation is presented which extracts and mathematically models the geometry of sculptured artifacts, and compensates for cumulative error build-up during replication. Experimental results using this strategy demonstrate that a considerable improvement in the accuracy of the end product can be achieved. The replication process involves scanning, CAD solid model creation, rapid prototyping utilizing the stereolithography process, the production of room temperature vulcanized (RTV) molds, the casting of polyurethane parts from the RTV mold, abrasive finishing processes associated with these prototyping processes, and the CNC machining of production molds and dies. At each stage in the replication process, the surface errors (caused primarily by material shrinkage, layer curling, internal stresses, chemical curing phenomena, and material removal during mechanical surface finishing) are tracked and used in subsequent production, through an iterative process of surface fitting and surface compensation.

Issue Section:
Technical Papers
Topics:
Error compensation, Rapid prototyping, Errors, Casting, Computer numerical control machine tools, Computer-aided design, Finishing, Geometry, Hardening (Curing), Machining, Shrinkage (Materials), Solid models, Stereolithography, Structural mechanics, Surface finishing, Surface fitting, Temperature, Urethane elastomers
1.
Rekoff, M. G., 1985, “On Reverse Engineering,” IEEE Transactions Systems, Man, and Cybernetics, pp. 244–252.
2.
Ashley
S.
,
1993
, “
Rapid Prototyping for Artificial Body Parts
,”
ASME Mechanical Engineering
, Vol.
145
, pp.
50
–
53
.
3.
Scuria
F. C.
,
1993
, “
Fitting and Regulating Artificial Limbs
,”
ASME Mechanical Engineering
, Vol.
145
, pp.
55
–
56
.
4.
Puttre´
M.
,
1993
, “
Replacing Parts on Nature’s Machines
,”
ASME Mechanical Engineering
, Vol.
145
, pp.
58
–
61
.
5.
Gargiulo, E. P., 1991, “Stereolithography Process Accuracy: Users Experience,” 2nd International Conference of Rapid Prototyping, University of Dayton Ohio, Proceedings, June 23–26, pp. 311–326.
6.
Diodo, L. K., 1993, “Epoxy Resins, Improved Part Accuracy & Investment Casting,” Conference Proceedings, Rapid Prototyping and Manufacturing ’93, May 11–13, Dearborn MI., Sect 18, pp. 120–126.
7.
VanPutte, D., 1991, “A Study of Stereolithography Uniformity and Repeatability,” 2nd Int. Conf. on Rapid Prototyping, pp. 295–309.
8.
Green, P. A., 1994, “An Integrated Reverse Engineering System for Error Modeling and Compensation of Sculptured Surfaces,” M.S. Thesis, University of Illinois at Urbana-Champaign.
9.
Jensen, K. L., and Hovton, R., 1992, “Making Electrodes for EDM with Rapid Prototyping,” 3rd International Conference of Rapid Prototyping, University of Dayton Ohio, Proceedings, June 7–10, pp. 295–301.
10.
Green, P. A., and Philpott, M. L., 1994, “Error Modeling of Reverse Engineered Free Form Surfaces,” NAMRC-XX II Transactions, pp. 259–266.
11.
Kruth, J. P., 1991, “Material Incress Manufacturing,” Cirp Keynote Paper, Annals of the CIRP, Vol. 40, No. 1.
12.
Deitz, D., 1990, “Stereolithography Automates Prototyping,” ASME Mechanical Engineering, Feb., pp. 34–39.
13.
Mueller, T., and Medler, D., 1990, “Stereolithography—A Technology Update,” Roundup ’90, Dallas, TX, October 8.
14.
Duffie, N. A., Kronenberg, M., Feng, S. C., Halldin, G. W., and Bollinger, J. G., 1984, “Error Compensation of CAD/CAM Data Bases By Comparison with Measured Data Bases for Increased Part Accuracy Capability,” NAMRC-XII, Houghton, MI, May 30–3.
15.
Faux, I., and Pratt, M., 1979, “Computational Geometry for Design and Manufacturing,” Ellis Horwood Ltd, England.
16.
Ralston, A., 1965, A First Course in Numerical Analysis, McGraw-Hill.
17.
Forrest
A.
,
1972
, “
On Coons and other Methods for the Representation of Curved Surfaces
,”
Computer Graphics and Image processing
, Vol.
1
, No.
4
, Dec, pp.
341
–
354
.
18.
Schumaker, L. L., 1976, “Fitting Surfaces through Scattered Data,” Approximation Theory II, Academic Press, New York.
19.
Feng, S. C., and Duffie, N. A., 1985, “Modification of Bicubic Surface Patches Using Least-squares Fitting Techniques,” Computers in Mechanical Engineering, Sept., pp. 57–65.
20.
Chivate
P. N.
, and
Jablokow
A. G.
,
1993
, “
Solid Model Generation from Measured Point Data
,”
Journal of Computer Aided Design
, Vol.
25
, No.
9
, pp.
587
–
600
.
21.
Fang, M., Chen, S., and Wang, X., 1993, “Surface Fitting from Digitized Data Points,” Proceedings of the IEEE International Conference on Robotics and Automation, Vol. 3, Atlanta, Georgia.
22.
Ferguson
J. C.
,
1964
, “
Multivariate Curve Interpolation
,”
Journal of ACM
, Vol.
11
, No.
2
, pp.
221
–
228
.
23.
Piegl
L.
,
1991
, “
On NURBS: A Survey
,”
IEEE Computer Graphics and Applications
, Vol.
11
, Issue
1
, Jan., pp.
55
–
71
.
24.
Philpott, M. L., and Modi, S., 1995, “Two Polishing Models for the Single-Setup Machinng of Free Form Mold and Die Surfaces,” Transactions of NAMRI, XXIII.
25.
Dinauer, W. R., 1990, “An Automated Mold Finishing System and Control Algorithms for Surface Finishing,” M.S. Thesis, University of Wisconsin-Madison.
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