Experimental approach to measure the restraining force in deep drawing by means of a versatile draw bead simulator

The extreme personalization of the sports car industry requires the development of reliable and affordable techniques for the in-house set-up and control of processing conditions in deep drawing of body-in-white parts. In order to cope with this urgent need, a handy draw bead simulator (DBS) is proposed to measure the restraining force exerted on a sheet metal by the draw bead during deep drawing. The apparatus can be integrated into a common tensile testing machine and the male-female parts of the DBS are variable to account for different geometries of the draw bead and for different thicknesses of the sheet metal. For validation, the DBS is operated to reproduce the effect of a draw bead working on an Al6014-T4 strip according to assigned industrial conditions. Tensile tests repeated on the metal strip after drawing open the way to quantify work hardening effects. The new DBS can be applied to measure the restraining force and investigate the specific role of the draw bead in deep drawing, but it may also be used to verify the predictivity of computational models, thus supporting the development of simulations for feasibility studies and tool design optimization.