Explosive fragmentation devices with coiled wire progressively varied

Abstract

An explosive fragmentation device such as a grenade or a mortar bomb has a casing formed from flat sided notched wire formed into a coil. Instead of coiling the wire so that sides of the coiled wire which are adjacent after coiling lie normal to the longitudinal axis of the coil, as in a known form of grenade body, the wire is given additionally a twist about its own longitudinal axis during coiling, so that the adjacent flat faces of adjacent turns are substantially normal to the surface of the finished casing. In this way adjacent turns overlay one another, preferably completely, and the outer surface of the casing can then be smooth. Also, adjacent turns can then be bonded together as by brazing or soldering, which is impractical with coiling "normal to the axis". This means explosive cannot be trapped between adjacent turns to be accidentally detonated, an outer casing is unnecessary, and the casing is stronger.

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