Novel piercing punch design for realizing clean cutting surface of aluminum alloy and its application to enhancing hole flanging ability

Abstract The effects of piercing parameters such as clearance, cutting distance, surface roughness on the sheared surface, and the delay-cracking mechanism in the hole-piercing process are investigated in this study. The characteristics of the piercing hole cross-section are compared based on a statistical analysis and finite element simulation results to realize a new punch design concept. The statistical analysis revealed that the differences in the mean sheared surface between the new and conventional punch designs were statistically significant under all the conditions. The experimental results for all the piercing clearances demonstrate that the new punch design can significantly reduce the die roll size and generate a smooth sheared surface. The use of an accurate finite element simulation allows us to understand the process parameters before fabricating the die. An advantage of the new piercing punch design in terms of hole-flanging ability is observed through an increased hole-expansion ratio. The new design can also produce high-quality, cutting-edge aluminum and advanced high-strength steel sheets.