Electromagnetic attractive forming of sheet metals by means of a dual-frequency discharge current: design and implementation

The ability to generate an attractive force for electromagnetic forming is an interesting and challenging issue, compared with conventional electromagnetic repulsion processes. This work presents a discharge system with two sets of power supplies and a timing control system for the production of a dual-frequency discharge current in a single coil. The discharge current can be employed to generate an attractive force between the coil and the workpiece in the forming process. The effectiveness of the system was verified both by numerical simulations and by a series of experiments of sheet metal forming. Our results show that an AA 1060 aluminum alloy sheet with a thickness of 1 mm, at a distance of 9 mm from the coil bottom, can be attracted towards the coil with a maximum deformation of about 4.7 mm. We also demonstrate that there is an optimum value for deformation depth, which is related to the initial discharge voltage of the fast discharge system. The presented method and results can be helpful in designing electromagnetic forming systems and widening their applications.