Patent GB-533529-A (GB)
Title: Improvements in and relating to arc welding apparatus
IPC: B23K9/133
Filed: 1939-09-18
Abstract: 533,529. Uniting by fusion. BRITISH THOMSON-HOUSTON CO., Ltd. Sept. 18, 1939, No. 26092. Convention date, Sept. 16, 1938. [Class 83 (iv)] In an arc welding apparatus current is supplied to a flux-coated electrode by a contact device comprising a main frame on which is pivoted and held in pre-determined position a second frame carrying means for cutting a slot through the flux coating and a brush contact, the pressure of the cutting means and brush being individually adjustable. The contact mechanism may be screwed on a wire guide 17 screwed into an insulating bush 19, which may be externally threaded so as to screw into a split screwed clamp 15 or may be of deformable material, smooth externally and of oversize and screwed into an integral screwed clamp. The contact mechanism is thus insulated from the electrode feed mechanism. The clamp 15 is pivotally mounted in a ring 14, which is itself pivoted on a bracket 13 secured to the welding head so that the electrode may be oscillated in one of two planes at right angles to one another by mechanism connected to a rod 15a as described in Specification 534,734. The contact mechanism comprises a main frame 11 on which is mounted on hollow pivots 24 a frame 12, the two parts being held together by an arm 25 pivoted at 26 on the main frame and having a cam 28 engaging ears 29 on the frame 12. The frame 12 may comprise two metal blocks 31, 31a mounting plungers 30, 30a, 30b carrying respectively a cutter 38 for cutting a slot in the flux coating, a notched tool 40 for scraping the base of the slot, and contact brushes 42. The operative parts may consist of sintered carbide. All three plungers are held in contact with the electrode by springs 34 adjusted by screwed bushes 35 from which they are insulated. The plunger 30 is insulated from the frame and the plungers 30a, 30b are connected to the main frame by shunts 41 so that they carry current. The nozzle block 10, through which the electrode is fed, and the frames 11 and 12 are cooled by fluid which passes from the inlet 56 through a passage 43 in the frame 11, then via passage 44a through apertures 48 in a hollow screwed plug 47, and after passing through the pivot 24, thence through a passage 51 in the frame 12 and thence through a cross-passage into a passage 52 and then via passages in the other pivot to passage 44 connected with the outlet. In a modification, the lower ends of the passages 43 and 51 and of 44 and 52 may be directly connected by tubes. The frame is provided with a shield 58 for protecting the apparatus from the heat of the arc, the shield having a bent tongue 59 to allow the pivotal movement of the frame 12. In a modification, the pivoted frame may consist of insulating blocks 60, 61, Fig. 5, pivoted at 81 to the nozzle block 74, the plungers being pushed forward by springs 65 and being provided with tapped openings 63 adjusted by screws 62. The parts are secured in position by a ring 82 operated by a lever 84 and engaging a notched pin 83. Cooling may be effected by fluid passed from an inlet 77 down one side of a partitioned tubular frame member 69 and thence via a passage 73 in the nozzle block through the other passage in the frame member 69.