Improvement of shear cutting process by stress superposition via cross-elastic partholder

Abstract

High quality requirements for shear-cut workpieces made of advanced sheet metal materials nowadays pose highest demands on cutting technologies. In this context, stress super-position in shear zones represents a common approach to adjust cutting surface quality or reduce trim load, but usually requires sophisticated process technologies. For example, fine blanking technology allows to increase clean-cut portion, but requires advanced tool and press technology. Given this background, the present paper deals with a novel, low-cost and straightforward approach of stress superposition in conventional shear cutting processes and tools. For this purpose, the partholder was geometrically modified to achieve vertical and horizontal force transmission into the blank. Presented investigations with implemented Z-shaped partholder and its cross-elasticity show a significant impact on cutting surface quality. The results were obtained by a numerical study using the FEA-Software DEFORM 2D, wherein geometry and process parameters were varied. By superposing compressive stresses, clean-cut portion could be increased up to 43 % compared to conventional shear cutting of DP600 having a sheet thickness of 1 mm. Additionally, rollover height was significantly reduced by up to 50 % due to the transversal forces of the cross-elastic partholder, while burr height could be kept constant.