Effect of the Duration of Electromagnetic Pulse Force on the Rebound Suppression in V-Bending Experiment

Abstract

Electromagnetic Forming (EMF) is one of the high speed forming technologies. The spatial distribution and temporal evolution of electromagnetic body force and the constraint imposed by the die on the sheet metal, are key factors which influence the dynamic deformation behaviour of sheet metal. The great force induced by the collision at high speed of the sheet and the die causes the rebound of the sheet off the die. The rebound has a significant influence on the final shape of the part. On the basis of the comparison of time relationship between the displacement of the sheet metal and the amplitude of electromagnetic force, the study about the rebound phenomenon in an electromagnetic V-bending experiment and its numerical simulation model is carried out in this paper. Collision promotes deformation process, resulting in a drastic change of sheet geometry in which a new distribution of electromagnetic force helps the part to fit the die. The attenuation of force caused by distance increase is comparatively weak when forming into a shallow die, so that the electromagnetic force maintains enough intensity which can effectively suppress the rebound and help to calibrate the V-Shape of the part. Increasing the duration of coil current pulse helps to suppress rebound effect of sheet metal when forming into a shallow die.