Die wear prediction by defining three-stage coefficient K for AHSS sheet metal forming process

摘要

The use of advanced high-strength steel (AHSS) has been steadily increasing in vehicle body constructions to enable improved fuel economy and vehicle safety performance. However, the high press loads required for stamping AHSS sheets causes severe chipping and adhesive wear on stamping/blanking die materials. In this study, wear coefficient K is defined for three stages of wearing process, and approximated by pin-on-disc wear experimental results of JIS SKD11 tooling material. The die wear severity index (WSI) is adopted and calculated as an integral of stress and slide speed over time duration. Die wear is then calculated as a multiple of the wear coefficient and WSI. In 2D state, the ABAQUS/UMESHMOTION code has been developed to integrate WSI. Numerical simulation of DP780 flanging predicts that the maximum wear loss occurs at the position where the straight line connects to the circular arc on the 2D die surface. The experimental results for die wear loss demonstrate good agreement with the simulation results.