Investigation of springback during electromagnetic-assisted bending of aluminium alloy sheet

Abstract

Electromagnetic-assisted forming (EMAF) combining quasi-static stamping and electromagnetic forming (EMF) is a potential method for controlling the springback of aluminium alloy materials. In this study, to further promote the application of EMAF in the high-precision forming of aluminium alloy sheet parts, the springback during electromagnetic-assisted bending of aluminium alloy sheet was investigated using a custom-designed U-shaped bending tool with the optimised curved spiral coils. Two types of conditions to control springback were designed: gapless and gap conditions, and the springback under these conditions was studied both experimentally and using numerical simulations. In addition, the effects of the discharge parameters on springback were analysed. Finally, the mechanism for controlling springback under different forming conditions was revealed. The results showed that the efficiency of springback control was significantly higher under gap conditions compared with gapless condition. With increasing gap, the springback angle decreased, but negative springback easily occurred when using excessively wide gaps. As the discharge voltage or number of discharges increased, the tangential stress of the fillet area decreased, thereby reducing the springback angle. Stress oscillations under the gapless condition reduced the tangential stress of the fillet area to a certain extent, while inertial motions under gap conditions greatly reduced the tangential stress, which were the essential mechanism for the observed springback reduction.