Study on flanged shapes in fineblanked-hole flanging process (FB-hole flanging process) using finite element method (FEM)

Nowadays, hole flanging is one of the most important processes in the sheet metal forming widely used in the automotive industry. However, the conventional punching process, in which cracks usually form on the cut surface, is normally applied as the first step in the hole flanging process. Therefore, there is the problem that the cut surfaces with cracks lead to reduce flangeability and also affect the geometry of the flanged shapes, such as the effective flanged height. In this study, the fineblanked-hole flanging process (FB-hole flanging process) was proposed in order to solve this problem. Namely, the deformations occurring during the FB-hole flanging process were predicted by the finite element method (FEM). The FEM simulation results were compared with experimental results and were found to be in strong agreement with each other. The results of this study verify that the FB-hole flanging process resulted in better-flanged shapes and flangeability than those obtained by the conventional-hole flanging process (C-hole flanging process). The relationship between the FB-hole flanging conditions and the flanged shapes was also clarified.