Considering the stiffness of the forming tools in the numerical analysis of the ironing process

Abstract

Ironing can occur in cylindrical cup drawing whenever the thickness of the drawn flange is larger than the gap between the punch and the die. This is particularly relevant for materials that present r-values lower than 1.0, such as the aluminium alloys, since they tend to present more thickening of the flange. The aim of this study is to evaluate numerically the impact of the elastic deformation of the forming tools on the final cup geometry, i.e., the earing profile and the evolution of thickness along the circumferential direction, at different heights. Different contact conditions are also analysed since they strongly affect both the thickness strain and the earing profile. The process conditions considered are the ones from EXACT, the ESAFORM Benchmark 2021, enabling the comparison with experimental results. Considering the deformation of the forming tools mainly impacts the ironing stage, enabling predicting wall thickness values larger than the gap between the punch and the die.