Hydromechanical Deep Drawing of Tailor Welded Blanks

Abstract

This paper investigates the conventional and hydromechanical deep drawing of circular tailor welded blanks (TWBs) with a linear weld line. TWBs offer the possibility to combine different materials, different thicknesses and different coatings within one part, as to optimally fit the applied loads with the lowest possible weight. By combining the hydromechanical deep drawing process with TWBs, a new range of applications can be offered. For the investigations experimental trials are carried out, as well as finite-element simulations. The material parameters of the parent materials and of the weld line are determined and included in the modelling of the TWB. A tool die is designed allowing the hydromechanical deep drawing of TWBs while taking into account the sealing of the TWB and the gap in thickness created by blanks of different thickness. In this way a different blank holder pressure can be applied on each side of the TWB, using a segmented blank holder and a multi-point cushion system. The goal of this study is to investigate the influence of the counter pressure on the deep drawing process of TWBs with particular interest given to the weld line movement during the forming process. It is found that the deep drawing process can be simulated accurately by the finite-element analysis and that the weld line movement plays a crucial role in the deep drawing of a sound part.