Optimization design and experimental verification of magnetic pulse spot welding system of dissimilar metal sheets based on a field shaper

Magnetic pulse welding based on a field shaper using a single-turn multi-layer flat coil and enhancing the magnetic field in local areas with the field shaper can achieve point welding of metal sheets, with broad application prospects in dissimilar metal welding. By reasonably optimizing the structural parameters of the flat coil and the field shaper, the magnetic field strength and eddy current density in the local area can be effectively improved, thereby increasing the Lorentz force to improve the collision speed of the sheet, and ultimately improving the welding quality of the sheets. In view of this, the goal of this work was to maximize magnetic pressure, optimize the structural parameters of the flat coil and field shaper, and innovatively propose a new type of field shaper with an arc-shaped hole structure, which effectively improved the welding quality without changing the welding energy. Furthermore, a magnetic pulse spot welding (MPSW) experimental platform was built using the optimized magnet device, achieving the spot welding of AA1060 aluminum sheets and stainless steel (SS304) sheets both with a thickness of 1 mm. Through peeling and stretching experiments, it was proven that the strength of the welded joint exceeded that of the base metal, indicating that the effective welding of dissimilar metals has been achieved. In addition, through microscopic analysis, it could be seen that a waveform composite interface was formed at the welding interface, which further indicated that the welding performance of the welded joint was good. The results indicated that the use of the new field shaper with an arc-shaped hole structure could reduce the critical discharge voltage for effective welding by 2 kV, directly converting it into lower energy consumption requirements and a wider process window, which had important economic value for industrial applications.