Study of Earing Defect during Deep Drawing Process with Finite Element Simulation

Abstract

Deep drawing is one of widely used sheet metal working process in industries to produce cup shaped components at a very high rate. In deep drawing process, a sheet metal blank form cylindrical components by process in which central portion of sheet is pressed into die opening to draw the metal into desired shape without folding the corners. Earing is one of the major defects observed during deep drawing process due to anisotropic nature of sheet metal. Earing is defined as formation of waviness on uppermost portion of deep drawn cup. Knowledge about ear formation in deep drawing process allows a prior modification of process which can result in defect free final product with financial saving and time. The initial blank shape used in present study is circular in nature.The objective of present study aims to produce parts which are earing defect free. Earing can be reduced by modifying the initial blank shape such as use of non circular blank as in present study. Efforts have been made to study the earing problem in deep drawing of cylindrical cups by finite element modeling software HYPERWORK-12 and Incremental RADIOSS as solver. The blank material selected for study is EN10130FeP06 mild steel sheet of 1mm thickness as it has wide application in fabricating automobile parts. Mechanical parameters of mild steel are incorporated in finite element simulation of deep drawing process. Significant earing was observed at rolling and transverse direction on deformed cup form circular blank. Modification of initial blank is done to reduce the earing defect. The results show significant reduction of % earing height and drawing load as well as improvement in maximum thickness variations.