Investigation of springback during electromagnetic-assisted bending of aluminium alloy sheet
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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.
KeywordsAluminium alloy Electromagnetic-assisted bending Springback Coil design Forming gap
This work was supported by the National Natural Science Foundation of China (grant numbers 51575206 and 51705169); the Innovation Funds for Aerospace Science and Technology from China Aerospace Science and Technology Corporation (grant number CASC150704); the Science Fund of State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body (grant number 31615006); and the Fundamental Research Funds for the Central University (grant number 2016YXZD055).
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