GB1317050A - Electrical discharge system for use with oxidising gases - Google Patents

Abstract

1317050 Plasma torch MANSFELD KOMBINAT WILHELM PIECK VEB 31 Dec 1970 61945/70 Heading H5H To prevent the working gas e.g. an oxidizing gas such as air of a plasma blow torch from swirling over the face of the cathode insert 1 and wearing away the mechanically unstable oxide coating formed thereon, the working gas is divided into two streams, a main stream which swirls about the arc 11 to constrict it and a subsidiary stream which is introduced near the face of insert 1 to swirl in the opposite direction and cooperate with the main stream to produce substantially stationary gas zone at the face of insert 1. As shown the gas is divided by a guide ring 8 provided with rows of gas ducts 9 and 10 which produce oppositely swirling subsidiary and main gas flows. Alternatively, Figs. 2 and 3 (not shown), part of a swirling gas stream introduced into the arc chamber is deflected by baffle surfaces provided on the lower surface of cathode mount 2 to swirl in the opposite direction to the undeflected mainstream and cooperate therewith to produce the stationary gas zone at the face of cathode insert 1. The insert 1 is zirconium galvanically coated with copper or silver and is friction welded to the copper mount 2. A cooling tube 5 extends into the mount 2 between an upstanding collar 4 and its outer wall. A nozzle cap 13 surrounds nozzle 6 and is supplied with coolant. The torch is started in the non-transferred mode but works in the transferred mode for cutting. It may work in the non-transferred mode.