A numerical investigation on the use of drawbeads to minimize ear formation in deep drawing

In the deep drawing of cups, the earing defect is caused by planar anisotropy in the sheet and friction between the blank and punch/die. In the past, several research efforts have been directed toward developing strategies for eliminating or mitigating the formation of ears. In this paper, we consider the concept of using drawbeads to minimize ear formation, thus overcoming the effects of anisotropy and friction. The study conducted and described here is entirely numerical. The object is to establish a numerical algorithm that will lead to an optimal drawbead contour that minimizes the earing defect in deep drawing. The algorithm is iterative in nature and involves performing simulations of the deep drawing process using finite element analysis, constructing an error metric at the end of each iteration, and utilizing the error metric to adjust the drawbead contour at the end of each iteration. The cycle is repeated until the error metric satisfies a preset convergence criterion. This iterative design process leads to an optimal drawbead contour. Several different test problems are considered, including the drawing of circular and square cups. Simulation results are very encouraging with reasonable number of iterations to arrive at the optimal drawbead contour.