| abstract |
Contiguous metal plates are welded together without special edge preparation or bevelling e.g. of cut edges (13) from one side using a focussed high intensity laser beam (7). To ensure maintenance of welding conditions even when the plate edges are spaced apart by cutting imperfections or the like a wire (12) is fed to, or near, the beam focus (10) to intercept the beam and give rise to a plasma. This plasma is kept in place by gas supply means (8), the gas supply through ducting (15, 16) of which (a) prevents plasma building up above the weld zone (which would decrease the beam intensity at the weld) but (b) holds some plasma in the region of the beam impingement on the wire so as to allow energy transfer to the adjacent walls. n Butt welds or T welds can be made in this way, even in plate material, in a single pass from one side. The technique thus permits the arrangement of work stations on a production line to be simplified and rationalised when making up multiweld repeat structural units eg in shipbuilding. |