0
TECHNICAL PAPERS

A Finite Element Based Die Design Algorithm for Sheet-Metal Forming on Reconfigurable Tools

[+] Author and Article Information
Simona Socrate, Mary C. Boyce

Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139

J. Eng. Mater. Technol 123(4), 489-495 (Jul 24, 2000) (7 pages) doi:10.1115/1.1395576 History: Received July 24, 2000
Copyright © 2001 by ASME
Your Session has timed out. Please sign back in to continue.

References

Hardt, D. E., Boyce, M. C., Ousterhout, K. B., Karafillis, A., and Eigen, G. M., 1993, “A CAD Driven Flexible Forming System for Three-Dimensional Sheet Metal Parts,” Sheet Metal and Stamping Symposium, Int. Cong. and Exp., Detroit, MI, SAE Technical Paper Series 930282, pp. 69–76.
Valjavec, M. 1999, “A Closed-loop Shape Control Methodology for Flexible Stretch Forming over a Reconfigurable Tool,” Ph.D. thesis, MIT.
Karafillis,  A. P., and Boyce,  M. C., 1992, “Tooling Design in Sheet Metal Forming using Springback Calculations.” Int. J. Mech. Sci., 34, pp. 113–131.
Karafillis,  A. P., and Boyce,  M. C., 1996, “Tooling and Binder Design for Sheet Metal Forming Processes Compensating Springback Error,” Int. J. Mach. Tools Manuf., 36, pp. 503–526.
Cao,  J., and Boyce,  M. C., 1997, “A Predictive Tool for Delaying Wrinkling and Tearing Failures in Sheet Metal Forming,” ASME J. Eng. Mater. Technol., 119, pp. 354–365.
Grodzinsky M. S., 1996, ‘Testing a Closed-loop Forming Algorithm on a Part Created by Discrete Die Stretch Forming,’ MEEE thesis, MIT.
Webb,  R. D. and Hardt,  D. E., 1991, “A Transfer Function Description of Sheet Metal Forming for Process Control.” ASME J. Eng. Ind., 113, pp. 44–54.

Figures

Grahic Jump Location
(a) The full scale tool measures 4ft×6 ft in plan area with 2688 1.25 in square pins. (b) Sheet metal part formed on reconfigurable die. Note the interpolating polymer layer (white) inserted between the workpiece and the die to prevent dimpling of the part.
Grahic Jump Location
Models of individual pins with different choices for the smoothing parameter
Grahic Jump Location
Stretch forming on discrete die without an interpolating layer. (a) Pressure on the workpiece (1/4 symmetry). Note that the individual pins are not part of the model, and are only shown to help visualize the die geometry. (b) Pattern of residual plastic strain in the workpiece (dimpling). (c) Deformed configuration of the workpiece at the end of the wrapping stage (1/4 symmetry). The deformation is magnified by a factor of 30.
Grahic Jump Location
(a) Finite element model for stretch forming over a discrete die with an interpolator. (b) Distribution of pressure in the interpolator at the end of the wrapping stage.
Grahic Jump Location
Geometry of the die used in the validation of the detailed numerical model
Grahic Jump Location
Detailed model representing conditions in the central region of the die
Grahic Jump Location
Comparison between predictions of unloaded sheet configurations obtained by the detailed model for two different levels of friction, and experimental measurements 6
Grahic Jump Location
Geometry of the simplified equivalent die model in relation to pin positions. The offset between the pin surface and the equivalent die surface is equal to the interpolator thickness.
Grahic Jump Location
Compression stress in the interpolator for a 3×3 pin array indentation test (double symmetry conditions are used to reduce the model to 1/4 of the actual geometry)
Grahic Jump Location
Equivalent die model for an asymmetric die. The corresponding discrete die comprises 23×24 1/2 in. pins with a 1/2 in. interpolator. The finite element mesh for the blank is also shown.
Grahic Jump Location
Comparison between equivalent model predictions and experimental part shape
Grahic Jump Location
Double curvature die. Surface through the centers of the pin caps.
Grahic Jump Location
Double curvature die. (a) Finite element mesh (1/4 symmetry). (b) Contact pressure between the sheet and the equivalent die at the end of the wrapping stage.
Grahic Jump Location
Springback deflection of the workpiece upon unloading [in]. Numerical predictions of the equivalent die model. (a) view from (−1 −1 1); (b) view from (001); (c) view from (−1, 0, 0). Stretching direction is (1,0,0).
Grahic Jump Location
Springback deflection of the workpiece upon unloading [in]. Experimental measurements. (a) view from (−1 −1 1); (b) view from (001); (c) view from (−1, 0, 0). Stretching direction is (1,0,0).
Grahic Jump Location
A schematic representation of the spring-forward algorithm. (a) unloading from reference die. (b) Unloading from spring-forward die. (c) load reference shape to obtain spring-forward die shape. The loading conditions, M′ , are not known a priori and must be determined iteratively.
Grahic Jump Location
Comparison of experimental part shapes formed on the “reference die” and on the “spring-forward die.” The solid line indicates the reference/desired part shape.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In