Simple Springback Cause Analysis Using Measured Shapes of Dies and Pressed Part

Abstract

A new springback cause analysis method was developed for sheet press forming with measured 3-dimentional shapes of dies and a formed part. In conventional springback cause analysis, a stress distribution is calculated by elasto-plastic FEM analysis of press forming. The newly developed method can be directly applied to a press formed part and its forming dies: an elastic FEM analysis of press forming is conducted using measured shapes of both a pressed part and forming dies, and a stress distribution which causes springback is obtained; and then a springback cause analysis is carried out based on the stress distribution. This calculation method is easier than that of conventional press forming simulation because plastic material properties and friction parameters are not required in its procedure. The philosophy of the new method and an example of application to an automotive part are described in this paper.

Development of a numerical compensation framework for geometrical deviations in bulk metal forming exploiting a surrogate model and computed compatible stresses

“…The superior convergence behaviour of such technique has been proved by Lingbeeck [15], while Birkert [16] investigated the impact of the compensation direction. The definition of the springback driving stress as the difference between residual and forming stresses is the core of the springback cause analysis method by Hiramoto [17]. Some preliminary investigations involving sheet metal tests have been performed by Lee [5], who proposed the Displacement-Compatible Spring-Forward (DC-SF) method.…”