Determination of the minimum possible damage due to shear cutting using a multi-stage shear cutting process

Abstract

Residual formability and edge crack sensitivity of shear cut edges depend largely on the manufacturing technique of the edges. In previous experiments, two-stage shear cutting processes have proven to reduce negative effects on the shear affected zone, which increased the forming capacity and thus also improved edge crack sensitivity significantly. The aim of this study was to determine the optimal settings for the parameters die clearance and cutting offset in order to maximize the forming capacity of pre-milled edges in a single-stage punching process. The performance of milled reference samples without additional punching determined the optimal outcome. In general, an open cutting line achieves a better residual formability in shear cutting processes than a closed cutting line. But by choosing a closed cutting line with specific punching parameters, the resulting edge conditions can achieve the ones of a process with an open cutting line closely. The geometry of the shear cut edge, the depth and degree of work hardening in the shear affected zone, as well as the surface roughness can be adjusted by varying the shear cutting parameters die clearance and cutting offset. The use of the collar forming test not only enabled an evaluation of the sample's edge crack sensitivity, but also resulted in the identification of the optimal combination of those shear cutting parameters. These findings allowed for an assessment of the significance of the influencing factors geometry, work hardening, and surface roughness on edge crack sensitivity and residual formability of the high-strength multi-phase steel CP-W 800. The results of this research presented a basis for another research project at the utg regarding a multistage shear cutting process for high-strength steels.