Sheet Metal Forming: Springback Control

I. SPRING BACK CONTROL AND ACTIVE CONTROLS OF SPRINGBACK

Abstract

The forming of sheet metal requires an understanding of a wide range of technical knowledge, the manufacturing application criterion and the interaction of processing and the material's properties. One of the major causes of inconsistent parts is springback, which Hu, Marciniack and Duncan define as the elastic strain recovery in the material after the tooling is removed (2002). This paper delineates an experiment carried out by Vikram Viswanathan (Northwestern University), Brad Kinsey (University of New Hampshire) and Jian Cao (Northwestern University) titled "Experimental Implementation of Neural Network Springback Control for Sheet Metal Forming." This experiment used punch trajectory as the primary factor in the experiment and examined the resulting variations of material properties, thickness and friction coefficients as responses. Once this particular approach to springback control is illustrated, this paper will divulge on a few techniques used to control springback.

Overview: Experimental Implementation of Neural Network Springback Control for Sheet Metal Forming

The problem of springback in a bending process within sheet metal forming, identified by Viswanathan, Kinsey and Cao, includes the region around the neutral plane which the material undergoes both elastic and plastic deformation. Once the final draw depth is achieved and the punch is removed, the part recovers its elastic strain. Due to the non-uniform stress that is distributed in the sheet, the part's final shape is different that the what it's shape was under load. This is best illustrated in figure 1.

Figure 1: Springback angle in drawing process.

Note: Springback an...

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...w.cs.stir.ac.uk/~lss/NNIntro/InvSlides.html, September 10th, 2005.

Sturges, R.H., 1999, "Springback Analysis and Control in Small Radius Air Bending," J. Manufacturing Scientific Engineering., pp. 679-688.

Sunseri, M., Cao, J., Karafillis,, A. P., and Boyce, M. C., 1996, "Accommodation of Springback Error in Channel Forming Using Active Binder Force Control: Numerical Simulations and Results," Journal of Engineering Material Technology., pp. 426-35.

Viswanathan, Vikram., Kinsey, Brad., & Cao, Jian. (April, 2003) "Experimental Implementaion of Neural Network Springback Control for Sheet Metal Forming." Journal of Engineering Material Technology. Volume 125. pp. 141 - 147. Retrieved from: http://www.mech.northwestern.edu/ampl/papers_pdf/vv_jc_jemt00.pdf, September 10th, 2005.