Patent GB-620299-A (GB)
Title: Improvements in and relating to arc lamps and electric welding machines
IPC: B23K9/12
Filed: 1945-01-19
Abstract: 620,299. Direct connections between conductors. MORGAN CRUCIBLE CO., Ltd., and HALLETT, C. G. H. Jan. 19, 1945, No. 1626. [Class 38 (i)] [Also in Groups XI and XL (a)] An arc lamp or welding-machine has a contact block for an electrode comprising a series of wedge elements, one behind the other with respect to the direction of the electrode feed, co-acting with a corresponding series of sloping surfaces formed in the electrode holder so that a thrust on the contact block parallel to the electrode causes the contact block to bear upon the electrode holder and upon the electrode. Preferably a plurality of such contact blocks are arranged around the electrode. The wedge elements are preferably formed as an integral unit and the face of the contact block opposite that which bears on the electrode has a serrated formation and the surface of the electrode holder is correspondingly serrated. The face of the contact block may be plane, except for serrations transverse to its length forming a series of wedge faces, or alternatively it may be of cylindrical or conical form serrated with substantially circular grooves. The contact blocks for the electrode 22 and detachable electrode holder nose-piece 21 are complementary segments 41 of a cylindrical bolt divided along its length and threaded at 42 and screwed into the threaded bore 43 of the nosepiece 21. The wedge slope may be 57¢ degrees. The rear ends of the contact block segments 41 are formed with projections 44 serving as gimbals engaging a recess 45 in a ring 46 mounted at the head of a carriage structure 47 supporting the electrode feeding means which comprises a shaft 23 driving through gears 24, 25 an articulated shaft 26 having a bearing at 27 and carrying a worm 28 driving the wormwheels 29, 30 splined on spindles on which are splined wheels 31, 32 each having two toothed elements 33, 33 and 34, 34, engaging the electrode 22. The spindles of the wheels 31, 32 are carried by frames 35, 36 pivoted at 37, 38, and urged to press the wheels upon the electrode by compression springs 39, 40. The carriage structure 47 at its rear end is slidably mounted on a tube 48 and forms a floating carriage. A compression spring 49 is interposed between a shoulder on the carriage 47 and a rear cap 50. The reaction thrust from the drive between the wheels 33, 34 and the electrode is rearwardly transmitted by the carriage 47 to oppose the force of the spring 49, thus maintaining the wedge pressure substantially constant notwithstanding changes of friction between the contact block segments 41 and the electrode 22. A trip lever 51 has a nose 52 bearing on the electrode 22 and a tail carrying a contact 53 which comes into engagement with a contact 54 when the end of the electrode 22, in the course of consumption, passes beyond the nose 52, the spring 55 then causing the lever 51 to trip. The contacts 53, 54 may be connected in an electrical circuit adapted, when closed, to give an indication that the electrode 22 has been nearly consumed. The electrode holder nose-piece 21 has passages 56 for the circulation of cooling water supplied at the union 57 and discharged through a similar union not shown.