As one of punching techniques of metal pipe, we present an underwater explosion punching method in which the holes are punched from the inside to the outside by the underwater shock wave due to the explosion of detonating cord in water. The assem bl the consists of a reflection vessel, which converges the underwater shock wave and a metal die for the punching purpose. In this method, the action of underwater shock wave on the interior of the to - be - punched pipe is very important while the die would not be damaged. The effects of the shape of the reflection vessel to converge the underwater shock wave to obtain a required high pressure and impulse are studied by means of pressure measurement and optical observation system. As a result it is found that in the case of the reflection vessel, which has an elliptic cross - section, the high peak - pressure and impulse are obtained and, both values are of approximately 3.3 times those from the case of the detonating cord directly pasted on a metal plate.
金属管への孔あけ加工法として, 水中での導爆線の爆ごうによって発生した水中衝撃波を金属管内に入射させ, 内側から孔をあける水中爆発加工法を提案した｡ 装置は, 導爆線を装薬して水中で爆ごうさせ, 発生した水中衝撃波を収束させるための反射容器と孔あけ加工用の金型で構成される｡ この方法では, 金型を損傷させることなく, 被加工管内にいかに効果的に水中衝撃波を作用させるかが重要である｡ そこで, 導爆線の爆ごうにより発生した水中衝撃波を収束させ, 局所的に高い圧力と圧力の力積を発生させることのできる容器形状について, 圧力測定実験と光学観測を併用して検討した｡ その結果, 容器内面の断面形状が楕円形の場合に最も高いピーク圧力と圧力の力積が得られ, いずれも鋼板に導爆線を貼っただけの場合の約3.3倍であった｡