GB270175A - Improvements in and relating to electric arc cutting - Google Patents

Abstract

270,175. British Thomson-Houston Co., Ltd., (General Electric Co.). Nov. 26, 1926. Perforating and dividing by fusion. - Metals are cut by an electric arc formed between the ,electrode and the work in conjunction with a blast of a reducing gaseous medium decomposed in the arc to produce a considerable percentage of hydrogen to envelop the arc and remove molten metal. A generator suitable also for welding may be used such as is described in Specification 169,374, [Class 35, Dynamo-electric generators &c.], and wound for about 80 volts on open circuit. The gaseous medium may consist of illuminating gas. A carbon or graphite negative electrode 10 adjustable by a screw in a tube 11 with an enamelled end in a nozzle 12 is attached thereby to a copper tube 14, to which the gas and current connections are attached at 15, 16 respectively. The tube 14 is adjustable in a block 17 which is freely slidable in a sleeve 18 attached to a carriage 19. The carriage is provided with a motor 25 which through gearing 27 traverses the carriage on racks 24. The block 17 has arms 20 with cam followers 21 resting on cams 22 splined to the axles 23 so that the electrode is oscillated vertically in the plane of the kerf during operation. A constant speed motor may be used, or, as shown, one in which the terminals are connected across the arc so as to vary the speed of cutting in accordance with the arc. length. The arc is preferably kept within the kerf so as to avoid wandering. The machine may be mounted to travel directly on the work or may be stationary and the work moved, or a hand tool form of apparatus may be used.