EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

In recent years, numerical simulations have become indispensable for designing and optimizing sheet metal forming processes. Simplifying “real” processes in numerical models aims for reducing the computational expenses; however, simplifications may considerably influence the quality of the numerical results. For this reason, the present work investigates and compares different simplified models of an industrial deep-drawing process of thin-walled steel cups. The axisymmetric models were build using the DEFORM 2D finite element (FE) software package. The tools (punch and die) were modeled as rigid or elastic, whereas the blank was modeled as plastic or elastoplastic. The variation of the drawing gap, which depends on the manufacturing tolerances of the tools, was also considered. The wall thicknesses calculated using the different models were compared with the actual wall thickness of a deep-drawn cup captured using an optical 3D measuring system. Based on this comparison the influence of the model simplifications and of the drawing gap on the results of the simulations was determined. Significant improvement of the numerical results, i.e., best agreement with the experimental results, was obtained if elastic tools were considered. In particular, the deformation of the die was identified as key factor influencing the wall thickness of the cup. Modeling the blank either as plastic or as elastoplastic did not show any considerable difference in the wall thickness profiles; however, both measured and calculated cup geometries agreed better when modeling the blank as elastoplastic. Moreover, the influence of the drawing gap decreased when the tools were considered as elastic and the blank as elastoplastic.