| 摘要 |
<p>A plasma arc cutting torch housing (12) defines a chamber (20) which has an outlet (22) at the end of the housing. An electrode (40) is fitted in the chamber near the outlet whereat a cup tip (32) separates the gas flowing towards the outlet of the housing into a primary gas flow adjacent to the electrode and through a central orifice (38) for generating a plasma and a secondary gas flow outside the electrode and tip for cooling the torch and the workpiece. The electrode has a centrally disposed axial bore (116) for conveying gas. Inserts (112, 114) in the bore at opposite ends of the electrode burn away so as to expose the axial bore and thereby automatically quench operation of the plasma arc so as to prevent damage to the torch In the preferred embodiment, the electrode has a centrally disposed transverse passage (122) and a pair of transverse passages (118, 120) between the central passage and the electrode ends for flow of the primary gas In an alternative embodiment, the transverse passages are eliminated and primary gas is conducted by means of passages through an annular member (72) around the electrode.</p> |
