Experimental and Numerical Analysis of Blanking for Thin Sheet Metal Parts

摘要

Blanking is one of the most used processes to obtain small and thin components in electronic and mechanical industries. Currently, the designing and manufacturing of these components are mainly based on know-how and empirical rules. The quality of the component is mainly determined by examination of the shape of the cut edge. That shape is related to the process parameters and the material behaviour. The industrial requirements need to produce smaller components with high controlled geometry. In many cases, the practical approach is not yet sufficient. During last years, a large number of publications about blanking have been proposed. Experiments were carried out and most of them are associated with numerical simulations [MAI 91], [TAU 96], [GOI 00]. These experiments are focussed on the influence of the process parameters, such as the geometry of the punch and die, or the punch-die clearance [GOL 99], [TAU 96]. Some investigations also concern the analysis of the deformation through the thickness in situ using a CCD camera [GOI 00], [TAK 96], [YOS 99]. These works are limited to sheet metal parts with a thickness greater than 1 mm. Presently the industrial knowledge concerning the metal blanking process is still empirical. Therefore, scientific approaches have been proposed to model blanking. Most of them use the finite element formulation [GOO 00], [KOM 99], [SAA 99]. The blanking process implies localized high plastic strains as in other sheet metal forming processes, stamping or bending. On the other hand, in blanking the plastic strain is used to initiate the fracture mechanism that must be avoided in other processes. So the main mechanical problem is related to the prediction of the initiation of the crack and the propagation across the sheet thickness.