Electromagnetic impacting medium forming (EIMF) for aluminum alloy tube by using flat spiral coil

Abstract

This paper proposes an innovative electromagnetic forming process for the manufacturing of aluminum alloy tubes, namely electromagnetic impacting medium forming (EIMF) process using flat spiral coil. The proposed EIMF process was implemented and characterized by numerical and experimental methods. Based on medium height and discharge energy, deformation region of tube was analytically determined and verified by finite element (FE) analysis. Effects of medium height and discharge energy for maximum diameter and strain rate of deformation tube were characterized numerically and experimentally. Flow defect of medium was observed at higher discharge energy. To estimate the effect of capacitance, four types of capacitance were designed and evaluated by numerical analysis. Through EIMF experiments, tubes with temperature from 25 °C to 200 °C were investigated and variations of maximum diameter (expansion ratio), thickness (thinning ratio) were obtained. Comparing with results under discharge energy, temperature has more obvious effects. Major and minor strains displayed higher level at 200 °C. Metallographic and morphologies were characterized by optical microscope (OM) and scanning electron microscopy (SEM). Results showed that refinement of average grain size and ductile fracture depends on the increase of discharge energy and temperature.