| This study is funded by China National Natural Science Foundation Committee through Grant 51075269, and co-funded by National Key Specific Science & Technology Program from Ministry of Industry and Information Technology of China through Grant 2010ZX04014-072 and 2011ZX04016-051. In this paper, the fracture edge qualities of DP780 sheets have been investigated in order to analyze the wear resistance performances of different tool materials during AHSS blanking process.An experimental tool setup with inserts assembled in parallel was developed to blank DP780 with thickness 1.4mm, in which the edge qualities of DP780 sheets blanked by six different tool materials (CALDIE,M2,SKD11,XW-10,Cr12MoV and RM2) respectively were analyzed statistically to compare the wear resistance performances of the experimental tool materials. It was pointed out that the burr height can report the wear resistance performance and the clearance between punch and die has an influence on edge quality. The fracture edge quality of the sheets corresponding to Cr12MoV is the best, which means that the wear resistance performance of Cr12MoV is the best among the selected tool materials. For CALDIE and XW-10, their respectively corresponding edge qualities are similar, and their wear resistance performances are worse than Cr12MoV. The wear resistance performances of M2 and RM2 are worse than those of CALDIE and XW-10, while the wear resistance performance of SKD11 is the worst among the selected tool materials.The ABAQUS/Explicit FEM code coupled with ductile fracture criterion model has been used to analyze the blanking process. For verification, the computed results have been compared with those of experimental results. It is found that Cockcroft-Latham damage model, McClintock damage model and Rice-Tracy damage model can predict the rollover depth and burnish length of the sheets in DP780 blanking process more accurately. A new method has been used to fit the wear profile of the tools in FEM model, and the computed results show good agreement with experimental results. It was found through simulation that the increase of tool wear leads to the increase of punch penetration corresponding to the crack initiation in the sheet materials, as well as the increase of the rollover depth, burnish length and burr height. But tool wear has no significant influence on maximum punch force. |
