Innovative design of a separatable coil for tube frame structure in magnetic pulse crimping

Magnetic pulse crimping (MPC) employs magnetic forces for high-speed metal forming, offering superior reliability compared to bolted joints and conventional fusion welding. However, the widely utilized devices often feature a monolithic structure and tend to be larger in volume, resulting in notable limitations regarding flexibility. This leads to a degree of complexity when attempting to join the closed-loop structure. This study proposed a highly flexible coil, characterized by a separatable working area, which could be employed to join complex structures. Numerical simulations were performed to analyze the feasibility of the separatable coil structure and the crimping parameters of the workpiece. The results revealed that the coil was reduced in size and reliable in strength. The velocity and displacement parameters displayed by the tube were well within the intended crimping range, thus confirming that the coil had basic functionality. The crimping tests on AA5052 tubes and rods confirmed the operational performance of the coil. Subsequently, the mechanical properties of the joints were evaluated through quasi-static tensile tests. Meanwhile, laser microscopy provided a detailed characterization of the interface morphology. The specimens developed two distinct types of joint mechanisms. At 24 kJ and below, the joints were joined by embedded mechanical interlocking. At exceeding 26 kJ, the observation of continuous interfacial waves highlighted the coil's capability in magnetic pulse welding. Finally, the typical engineering samples of AA5052-ZS304 dissimilar materials were successfully fabricated by using the separatable coil. The coil had demonstrated its flexibility in joining complex structures, effectively overcoming the constraints of traditional crimping devices.