GB232995A - Improvements in and relating to electric arc welding machines - Google Patents

Abstract

232,995. British Thomson-Houston Co., Ltd., (Assignees of Merrill, W. L.). April 28, 1924, [Convention date]. Heating by electricity.-An are-welding machine is provided with electrode feeding mechanism comprising a rotatable disc 20 driven by friction rolls 21, 22 moved into and out of engagement therewith by means responsive to the electrical condition of the arc so as to keep an arc of constant length. The disc 20 drives the feed rolls through a worm gear. The friction rolls are mounted so as to be capable of longitudinal adjustment on a shaft 23 carried in bearings 25, 26 pivoted at 27, 28 and under the control of electromagnets 29, 30 and springs 33, 34, arms 31, 32 of the bearings forming armatures of the magnets. The current to the magnets is supplied by a source of constant voltage 78, 79, Fig. 5, and is under the control of switches 80, 82 and a relay under the control of a coil 71 in shunt to the arc, which is fed from a source of constant current or constant voltage 69, 70. In a variable-current supply system wherein the current through the arc varies sensitively with the change in arc voltage, the coil 71 is connected in series with the arc. The feeding of the electrode may be controlled manually by means of a switch 85. The feeding mechanism is enclosed in a case fitted with a hinged lid and is mounted on a standard carrying a constantspeed motor which drives the shaft 23 through belt gearing. In a modification the motor is coupled to the shaft 23 by a flexible shaft and the rolls 21, 22 are embraced by adjustable forks for longitudinal adjustment. In this case a variable-speed gear is fitted between the worm gear driven by the disc 20 and the feed rolls. The feed rolls comprise a roller driven by the disc 20, and a roller 6, Fig. 8, carried in a pivoted bearing 66 fitted with a flat springs 67, the roller being pressed against the electrode by a screw 68. The apparatus may be used with metal electrodes or carbon electrodes fitted to suitable holders. Specification 159,374, [Class 35, Dynamo-electric generators &c.], is referred to. The Specification as open to inspection under Sect. 91 (3) (a) contains a reference to Specification 171,442. This reference does not appear in the Specification as accepted.