IMPROVEMENTS IN OR RELATING TO PLASMA-ARC CUTTING

摘要

This invention provides an improved method by which a plasma-arc cutting torch (77) can be used to cut a metal plate (125). The method basically comprises operating the torch (77) with its lowermost end portion submerged in a layer or water provided over the workpiece. In order to enable automatic adjustment of the torch (77) to the appropriate working height above the submerged workpiece, the torch is mounted on a mechanism which permits relative up and down movement between the torch (77) and a support member (88). The torch is lowered towards the workpiece (125) so that it eventually engages the workpiece and is caused to move upwardly relative to the support (88). This upward movement of the torch is detected and is used to initiate raising of the support (88) to bring the torch to its operational height above the workpiece.