Fragmentation casing for explosive shell etc. - is helically weakened metal cylinder with joint line of gap spot-welded to hold ends together

摘要

The metal sleeve, forming the casing of an explosive shell, grenade or mine, has a helical cut through its wall for part (4) of its length, equidistant between its two ends (2,3). This helical line (5,6) is formed and the ends are forced together so that spot welds (8) can be made along the helical joint line, to form a cylinder with a weakened central zone. A weaker inner sleeve of e.g. aluminium, can be fitted inside, supporting the helical-pattern and holding the ends together without locally welding the helical joint. In alternative designs, the helical joint line is zig-zag shaped, or includes interlocking parts.