An experiment and simulation study of the rebound effect in electromagnetic forming process

Abstract

Electromagnetic forming (EMF) has been proved to be a useful method to form the aluminium alloy sheet as it has so many advantages. As a high-speed forming process, it can suppress crack, reduce springback, and improve the formability of material at room temperature. But in the process of EMF, the rebound effect caused by high velocity impact has an important effect on the flatness of the formed part. Then a spring damper system has been added under the female stop block to eliminate this effect. The results of formed shape, thickness distribution and stress and strain state are investigated by comparing with free-forming process. On the other hand, the influence of spring stiffness and damping coefficient is analysed by using of ANSYS loose-coupled method. The results shows that it helps to improve the flatness of formed parts with a spring damper system used. Beside of the changing of formed shape, the difference of stress strain state results in difference of thickness distribution. And crack happened at the bottom is supressed, and this does favour for further processing. Furthermore, the results also shows that low spring stiffness and right damping coefficient are benefit for reducing the rebound effect.