Study on Explosive Forming Using Pressure Vessel and Metal Die

Explosive forming is one particular forming technique, in which, most commonly, water is used as the pressure transmission medium. An explosive is set at the top of the pressure vessel filled with water and is exploded by an electric detonator. An underwater shock wave propagates through the water medium and impinges on the metal plate causing it deformation. If a metal die is used, the metal plate deforms to a specified form. Generally, explosive forming has little spring back of the metal plate, because sufficient plastic deformation is obtained. There are two pressure actions to the metal plate on explosive forming. The first pressure pulse is from the shock loading and the second pressure pulse is caused by the expansion gas generated by the detonation of the explosive. The secondary pressure pulse duration is longer, but the peak pressure is lower than the primary shock pressure. The intensity of the pressure pulse is based on the conditions of the pressure vessel. We have also been using the metal die for explosive forming. The deformation shape of the metal plate is effected by a distribution shape of shock loading. In this technique, the pressure vessel has a desired internal shape. The pressure vessel has an internal shape of a parabola. In order to understand the deformation mechanism of the metal plate, some experiments and numerical analysis were carried out.