Numerical Identification of Optimum Process Parameters for Combined Deep Drawing and Electromagnetic Forming

Abstract

In this paper, a method is presented for the virtual process design of combinations of deep drawing and electromagnetic forming. With suitably chosen parameters, such process combinations of a quasi-static and an impulse forming process extend forming limits of classical, purely quasi-static forming. To determine parameters leading to the desired forming result, a numerical optimization algorithm is employed. The parameters to be adjusted comprise parameters of the triggering current, such as frequency, amplitude, damping, etc., geometric parameters of the tool coil and parameters of the deep drawing process, as, e.g., drawing radii or tribological parameters. To reduce the required number of evaluations of the target function, a gradient based numerical optimization scheme is employed following directions of decent in the parameter space. The quality of a given parameter set is determined by computing the distance of the simulated forming result to the prescribed ideal shape via a finite element simulation. Forming limits are incorporated by so called forming limit surfaces as constraints to the optimization process, considering rate dependence and prestrain in the second impulse forming step.