Research of Drawing Process on Variable Blank Holder Force for Elliptic Pieces Based on Finite Element Analysis

Aiming at the shape character of an elliptic piece,two schemes were put forward about the study of variable blank holder force(VBHF).By changing the blank hold-down pad partition and variable blank holder force manner,sheet formability was simulated with finite element analysis software Dynaform.By observing forming limit diagram(FLD) under different VBHF curves,the preferable VBHF curve was ultimately confirmed.Form the of view of the simulation results,VBHF curve of increasing type should be applied on a larger radius of curvature area,and VBHF curve of first decreased and then increased type should be applied on a smaller radius of curvature area.These can significantly improve the forming limit of drawing parts and can also reduce or avoid the wrinkling and cracking of drawing parts.