Optimum blanking clearance choice method by an approach coupling experimental trials and simulations

Abstract

Blanking process of sheet metal is accomplished by a shearing action on a thin plate placed between two sharp cutting edges, known as “punch” and “die”. The main problem of this sheet metal cutting technology, that causes major shutdowns of the press machine, is the punch wear. Among all blanking parameters, the clearance set between the punch and the die has the major influence on tool wear. In this context, our study focuses on identifying the optimum blanking clearance that guarantees a maximum abrasion and chipping wear reduction for different sheet metal materials and different blanking operations. The developed approach combines experimental blanking tests and numerical simulation of blanking processes. Based on assumptions made in this paper, links are established between the stripping force and the abrasive wear behaviour of punching tools and also between the maximum pressure on the face of the punch and the risk of chipping. Using these links, criteria have been developed allowing to propose an optimum blanking clearance for all the configurations tested in this paper. A next step of this study consists on applying the optimum punch-die clearances in a variable way along a complex blanking shape and realizing experimental tests to compare the results (tool life and edge quality) with a constant blanking clearance.