2111 Study on Effect of Blank Holder Gap on Cylindrical Cup Deep Drawing Process

Abstract

This research is aimed to study on effects of Blank Holder Gap (BHG) on deep drawability, that has been investigated for a cylindrical cup deep drawing process from square blank shape. The BHG is an effective way to control material flow into the die cavity during forming process. The effects of BHG on deep drawing of circular cup are studied by using numerical simulation method with commercial code named LS-DYNA. The BHG is defined as a distance between die and blank holder surface (clearance). In this study the BHG is ranging from 1.05 to 1.60 mm when initial blank thickness is 1.00 mm. For failure (wrinkling and tearing) detection of deep drawing process Forming Limit Diagram (FLD) under Swift and Hill's criterion and Wrinkling Limit Diagram (WLD) are used. In order to find out an optimum BHG, and objective function of this research is defined as risk of tearing. From numerical simulation results, the BHG has a great effect on the forming quality of formed product. As ranging of BHG from 1.05 to 1.60 mm, a suitable BHG for deep drawing of circular cup for given tooling and material is tried to design. Moreover, a simple closed-loop algorithm had been developed in order to determine the variable BHF trajectory for constraint BHG during forming process.