GB876068A - Method and apparatus for electric arc cutting - Google Patents

Abstract

876,068. Cutting by electric arcs. BRITISH OXYGEN CO. Ltd. Jan. 21, 1958 [Jan. 31, 1957], No. 3475/57. Addition to 872,726. Class 83 (4). An improvement in the electric arc cutting device claimed in the parent Specification consists in providing an auxiliary nozzle 18 which directs a jet of fluid into the cut to remove unwanted material therefrom. The tungsten non- consumable electrode 7 is axially adjustable and projects through a graphite insert 6 in a main copper nozzle 1 which is circulated with a coolant through conduits 3, 4. An inert or reducing shielding gas surrounds the arc and may be nitrogen or a mixture of hydrogen and at least one of the gases nitrogen, argon, carbon dioxide or gaseous hydrocarbons such as methane, propane or acetylene. The insert 5 forms a secondary electrode fed through conduit 4 from a high-frequency generator 15, Fig. 2 (not shown), for ionizing the shielding gas. An auxiliary electrode 18 of tungsten carbide is adjustably mounted on a collar at the rear of the main nozzle to direct a parallel or inclined thin jet of fluid into the cut. The auxiliary nozzle may extend into the cut. The main and auxiliary nozzles may alternatively be formed integral with each other. The fluid may be compressed air carbon dioxide, oxygen, hydrogen, nitrogen, argon or water. References are made to cutting ferrous metal including stainless steel, and aluminium. Specific examples are given including the voltage, current and consumption of shielding gas and auxiliary fluid. Specification 859,363 also is referred to.