Coil-less electromagnetic forming process with uniform-pressure characteristics for shaping sheet metals

Abstract

Abstract Electromagnetic forming is a high-speed processing technology that uses Lorentz forces to achieve plastic forming. In existing research, electromagnetic induction coupling between the coil and the metallic workpiece is generally required to produce the Lorentz forces. This brings an inevitable challenge to the practical application, that is, the limited coil life due to both mechanical and thermal loads. In addition, in most cases, the Lorentz force acting on the workpiece is non-uniform, which limits its application to a certain extent. In this work, a coil-less electromagnetic sheet metal forming system is developed to solve these issues. A three-dimensional circuit-electromagnetic-mechanical coupling numerical model is established, and a series of simulations and experiments are carried out to reveal the dynamic forming process with uniform-pressure characteristics. Furthermore, we introduce a pulsed current transformer with a current rise coefficient of about 8 to improve the coil-less forming system, which can generate a large current in the workpiece using a small current in the primary circuit. On this basis, we compare the forming process with and without the pulsed current transformer, and discuss the corresponding mechanism. The numerical and experimental results can be useful for understanding the coil-less forming process, as well as promoting the advancement of electromagnetic forming.