Fixtures are used to position and hold parts for a series of assembly operations. In automotive body assembly, these fixtures conventionally have been dedicated, therefore they must be replaced whenever there are model changes in an auto body assembly plant. In recent years, however, the automotive industry has been changing from high volume to small-to-medium volume production per model with an increasing number of models because customer tastes are diversifying. To cope with this change, auto companies need to be capable of producing a variety of models in small-to-medium volume, and they rely on flexible assembly lines and flexible fixtures. These flexible fixtures use robots as programmable fixture elements so that they can be reprogrammed for different stamped sheet metal parts. When designing flexible fixtures, fixture designers need to be concerned with fixture workspaces for a set of different stampings. However, existing fixture design methods address the fixturing of one stamping only. This paper presents a system that fixture designers can use to synthesize flexible fixture workspaces for a set of different stampings. Based on circular workspaces for flexible fixture robots, this system finds optimal workspace sizes and centers on a fixture base plate with a graphical display for visual checking. This system is simple to use and produces results quickly.

Issue Section:
Research Papers
Topics:
Fixturing, Manufacturing, Robots, Assembly lines, Automotive industry, Design, Design methodology, Metal stamping, Sheet metal
1.
Abe, K., Hayashi, A., and Sakaino, M., 1995, “An Update on Nissan Intelligent Body Assembly System,” Body Assembly & Manufacturing, Vol. 15, International Body Engineering Conference, Oct. 31–Nov. 2, Detroit, Michigan, M. Nasim Uddin, ed.
2.
Bausch, J. J., and Youcef-Toumi, K., 1990a, “Kinematic Methods for Automated Fixture Reconfiguration Planning,” IEEE International Conference on Robotics & Automation, pp. 1396–1401.
3.
Cai
W. J.
,
Hu
S. J.
, and
Yuan
J.
,
1996
, “
Deformable Sheet Metal Fixturing: Principles, Algorithms and Simulations
,”
ASME JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING
, Vol.
118
, pp.
318
–
324
, August.
4.
Campbell, P., 1994, Basic Fixture Design, Industrial Press Inc., New York, NY.
5.
Davis, L., 1991, Handbook of Genetic Algorithms, New York, Van Nostrand Reinhold.
6.
Drake, A., 1984, “Fixture Design: Working with Modules,” Manufacturing Engineering, January, pp. 35–38.
7.
Eary, F., and Reed, E., 1974, Techniques of Pressworking Sheet Metal, 2nd Ed., Prentice Hall.
8.
Fanuc Robotics, 1995, “A Brochure of FLEXTOOL™ Body Shop Manufacturing Solutions,” FANUC Robotics North America, 2000 South Adams Road, Auburn Hills, MI 48326-2800.
9.
Goldberg, David E., 1989, Genetic Algorithms in Search, Optimization and Machine Learning, Reading, Massachusetts, Addison-Wesley.
10.
Grefenstette, J., 1991, GENESIS, TSP P.O. Box 991, Melrose, MA 02176 (Computer Program in C and User Manual—Public Domain for Research Purpose).
11.
Jain
P.
,
Fenyes
P.
, and
Richter
R.
,
1992
, “
Optimal Blank Nesting Using Simulated Annealing
,”
ASME Journal of Mechanical Design
, Vol.
114
, March 1992, pp.
160
–
165
.
12.
Lee, Jinkoo, 1996, Set-based Design Systems for Stampings and Flexible Fixture Workspaces, PhD Thesis, The University of Michigan, Ann Arbor, MI.
13.
Menassa
R. J.
, and
DeVries
W. R.
,
1991
, “
Optimization Methods Applied to Selecting Support Positions in Fixture Design
,”
ASME JOURNAL OF ENGINEERING FOR INDUSTRY
, Vol.
113
, pp.
412
–
418
.
14.
Nee
A. Y. C.
,
Bhattacharyya
N.
, and
Poo
A. N.
,
1987
, “
Applying AI in Jigs and Fixtures Design
,”
Robotics & Computer-Integrated Manufacturing
, Vol.
3
, No.
2
, pp.
195
–
200
.
15.
O’Connor, Leo, 1994, “Agile Manufacturing in a Responsive Factory,” Mechanical Engineering, pp. 54–57, July.
16.
O’Rourke, Joseph, 1995, Computational Geometry in C, Cambridge University Press.
17.
Preparata, Franco P., and Shamos, Michael Ian, 1988, Computational Geometry, Springer-Verlag.
18.
Press, W. H., Teukolsky, S. A., Vetterling, W. T., and Flannery, B. P., 1992, Numerical Recipes in C, 2nd Ed., Cambridge University Press.
19.
Rearick, M. R., Hu, S. J., and Wu, S. M., 1993, “Optimal Fixture Design for Deformable Sheet Metal Workpieces,” Transactions of NAMRI/SME, pp. 407–412.
20.
Sekine, Y., Koyama, S., and Imazu, H., 1991, “Nissan’s New Production System: Intelligent Body Assembly System,” SAE Papers 910816.
21.
van Laarhoven, P., and Aarts, E., 1987, Simulated Annealing: Theory and Applications, D. Reidel Publishing Co.
22.
Ward
A.
,
Liker
J.
,
Sobek
D.
, and
Cristiano
J.
,
1995
, “
The Second Toyota Paradox: How Delaying Decisions Can Make Better Cars Faster
,”
Sloan Management Review
, Spring, Vol.
36
, No.
3
, pp.
43
–
61
.
23.
Youcef-Toumi
K.
,
Bausch
J. J.
, and
Blacker
S. J.
,
1989
, “
Automated Setup and Reconfiguration for Modular Fixturing
,”
Robotics & Computer-Integrated Manufacturing
, Vol.
5
, No.
4
, pp.
357
–
370
.
24.
Youcef-Toumi
K.
,
Liu
W. S.
, and
Asada
H.
,
1988
, “
Computer-Aided Analysis of Reconfigurable Fixtures and Sheet Metal Parts for Robotic Drilling
,”
Robotics & Computer-Integrated Manufacturing
, Vol.
4
, No.
3/4
, pp.
387
–
393
.
25.
Zhang
X.
, and
Roy
U.
,
1993
, “
Criteria for Establishing Datums in Manufactured Parts
,”
Journal of Manufacturing Systems
, Vol.
12
, No.
1
, pp.
36
–
50
.
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