Effect of Punch Speed on Amount of Springback in U-bending Process of Auto-body Steel Sheets

Abstract

This paper deals with the experimental and numerical investigation of the effect of the punch speed on the amount of springback in U-bending of auto-body steel sheets. U-bending tests and finite element analysis of SPCC and DP780 steel sheets were conducted for springback evaluation at different punch speeds with the geometry adopted from the NUMISHEET '93 benchmark problem. For the U-bending test, INSTRON8801 dynamic materials testing machine and a newly designed U-bending jig were used to conduct U-bending tests at different punch speeds. Experimental results show that the amount of springback of SPCC decreases but that of DP780 increases as the punch speed increases. For the finite element analysis, mechanical properties of SPCC and DP780 steel sheets considering the strain rate were obtained and the results of the analysis are presented in comparison to experimental measurements and to investigate the effect of punch speed on the amount of springback.