Electromagnetic pulse welding (EMPW) is an environmentally friendly and advanced manufacturing technology. Researches find the macro-morphology of EMPW joint of sheets presents a multilayer ellipse. The EMPW experiments of Al-Cu sheets and Al-Mg sheets were carried out, both the macro-morphology and the micro-morphology showed there were collision zone, bonding zone and bonding affecting zone in the joint, presenting multilayer elliptical morphology, which was independent of material. The welded seam was in the bonding zone. The 3D multiphysics simulation results also showed that the distribution of the plastic deformation of Al sheet, Lorentz force, induced eddy current and magnetic flux density at the welded joint were all elliptical, and they presented a multilayer elliptical continuous equivalent distribution surface due to the difference of amplitude. The magnetic field edge-effect affects the distribution of the magnetic flux density, and the non-uniform distribution produces the multilayer elliptical macro-morphology, which causes the induced eddy current, Lorentz force and the deformed area of the aluminum alloy plate to be the elliptical shape. Therefore, the macro-morphology of EMPW joint of sheets is a multilayer ellipse. This work may provide theoretical support for the performance improvement of the EMPW technology.

Electromagnetic forming (EMF) has been widely applied in industries. However, it’s still hard to form the thick or hard metal work pieces due to the limitation of its system power. And increasing the input voltage or capacitors may cause the problem of insulation, reduce the lifetime performance of devices, and lead to cost increase and safety issue. Therefore, this paper proposes a novel technology named electromagnetic heating forming (EMHF), which combines EMF with electromagnetic induction heating (EIH) based on their similar working principles to make it easier to form the thick or hard metal work pieces. EMHF can reduce the deformation resistance of work pieces by preheating treatment, and produce a small discharge energy to deform work pieces. A 5kV/1.68kJ/135lF EMHF system with a high-current pulse generator and a high-frequency heating source, which consists of an autonomous current-fed pushpull resonant inverter based on a zero voltage switching circuit and a resonant network, has been designed, built, and tested successfully. A finite element model coupling with electromagnetic field, solid mechanics field, thermal field and deformed geometry has also been built in COMSOL Multiphysics to analyze the EMHF process. Tube compression EMHF experiments of different input voltages, thicknesses and temperatures have been carried out. The experimental and simulation results demonstrate that EMHF can reduce the requirements of deformation process by preheating treatment, which can’t be done by EMF. Besides, the deformation can be controlled by the preheating temperature during the EMHF process. Therefore, EMHF has a great potential in industrial applications.

Electromagnetic pulse forming (EMPF) is an attractive manufacturing method using pulse power techniques. Temperature rise of the work piece is usually neglected in previous studies because the forming process is regarded as a cold process. Nevertheless, the temperature rise (if not high) also has influence on the forming process. It is important to study the temperature rise for exploring the related law in the process of EMPF. In this paper, the thermal effect in the process of EMPF, caused by the joule heating generated by the high current and the plastic work produced by the plastic deformation of the work piece in the forming process, is discussed though simulations and experiments. A finite-element simulation coupled with the electromagnetic field, plastic mechanics, deformed geometry, heat transfer, and thermal expansion based on COMSOL multiphysics is established to show the detailed thermal effect in this process. The relationship between parameters of work piece and the thermal effect has been analyzed by comparing different materials and thicknesses of work pieces. The simulation results show that the temperature of work piece has changed because of the thermal effect. A high-current pulse generator has been developed for the experiment of EMPF to verify the results of simulations. This paper describes the forming experiments of different materials and thicknesses. And the experimental results verify that the materials and thickness of work piece affect thermal effect during the process of EMPF. Compared with the Joule heating, the plastic work is the main cause of the thermal effect. Moreover, the thermal expansion caused by temperature rise could affect the forming results and material property.

Electric vehicle is one of the important development directions of the automotive industry, with a broad prospect. The high-voltage wire harness plays a key role in the power system for electric vehicle. Aluminum wire harness was proposed to be crimped with the copper terminal instead of the copper wire harness, which can decrease the weight and the cost. This work proposes an electromagnetic pulse crimping technology to connect the aluminum wire harness and copper terminal of electric vehicle. A 28 kJ electromagnetic pulse crimping system for crimping aluminum wire harness and copper terminal was established and the reliable joints were obtained and tested. The microstructure analysis results show that the connection interface has a corrugated morphology, and there was no obvious effect on the plating during the high-speed collision. The energy dispersive spectroscopy analysis results show that there was metal element diffusion in the connection interface. The testing results show that the joints with good electrical performance can be obtained, which can promote the realization of the aluminum wire harness instead of the copper wire harness. This work can provide technical reference and theoretical support for the development of high-voltage wire harnesses for electric vehicle.