Design and Experiments of Electromagnetic Heating Forming Technology

Electromagnetic forming (EMF) has been widely applied in industries. However, it's still hard to form thick or hard metal work pieces due to the limitation of its system power. Moreover, increasing the input voltage or capacitors may cause the problem of insulation, reduce the lifetime performance of devices, and lead to the 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. The EMHF can reduce the deformation resistance of work pieces by preheating treatment, and produce small discharge energy to deform work pieces. A 5kV/1.68kJ/135μ F EMHF system with a high-current pulse generator and a high-frequency heating source, which consists of an autonomous currentfed push-pull 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 the 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 the EMHF can reduce the requirements of the 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, the EMHF has great potential in industrial applications.