A Method of Explosive Forming Process for Making a Palm and a Back of Human Hand

Abstract

t is well known as an important merit of the explosive forming process that the delicate figure of the die surface is precisely transferred onto the specimen of a thin metal plate, because the plate is strongly pressed against the die by the very high pressure of underwater shock wave. However, we cannot find any examples of work pieces making the best use of the merit in literatures until now. We tried to form explosively a thin copper plate into shapes of a palm and a back of human hand, as a work piece making the best use of the merit. The palm has many small delicate lines such as fingerprints and the back has interesting figures such as loose skin at the joints of fingers and the borders of fingernails. The object of the present investigation is to make work pieces just like to a real hand. In this investigation, the following process is adopted in order to perform successfully explosive forming ; real hand plaster concave model convex model of Duplicone (material for dental impression) die of Ren Cast (a kind of epoxy resin) explosive forming. Annealed copper plates of 0.3 mm thick were used in the experiments. Since the extension limit of the plate is not so large, the plate is apt to be broken. If the plate is broken, the die is modified not to break the plate. Though the die made of epoxy resin is too hard to be modified, the plaster model can be easily modified with a cutter knife or a chisel. The modified die is obtained through model of Duplicone made by using the modified plaster model. After a few times of repeating modification, the breakage of plate was scarcely produced. On the work piece of palm, a lot of small lines including finger prints clearly appeared and the work piece of the back showed the shape just like to real human hand.