Experimental Study on Formability in Electrohydraulic Forming with and without Bridging Wire

Abstract

Electrohydraulic forming (EHF) can overcome the shortcomings of deep drawing and electromagnetic forming, demonstrating a reduced bouncing effect, formation in narrow areas, and no effect on the electrical conductivity of the blank. In existing EHF experiments, wires are fastened to provide a forming force at variable positions. Therefore, production of uniform products is difficult, and the experimentation is time-consuming and difficult to apply in industrial processes. In this study, wireless and wire-cross EHF were presented to reduce the time required for EHF experiments and produce a uniform forming force. The maximum forming height and formability were evaluated using a 0.5 t SUS430 specimen and free-bulging die. The required experimentation time was measured by comparing each EHF with a conventional EHF. The wireless EHF experiments required the least time and produced a constant forming force. A wire-cross EHF was proposed to compensate for the time required to connect the fully connected wires in a conventional EHF. However, this did not substantially reduce the experiment time. Although wire-cross EHF has a higher energy efficiency than wireless EHF because wires are incorporated, it cannot completely overcome the fundamental problems of EHF. In wireless EHF, two consecutive experiments were performed to produce the same height under an applied voltage of 6 kV. When conducting consecutive experiments, if the experiment is ready for the first time, only the capacitor must be repeatedly charged and discharged while maintaining a constant electrode spacing, so the experiment can be completed faster.