Patent GB-563833-A (GB)
Title: Improvements in and relating to electrical welding machines
IPC: B23K11/093
Filed: 1943-05-11
Abstract: 563,833. Welding boxes, tanks, &c. BRIGGS MOTOR BODIES, Ltd., UREN, H., and DALLISSON, R. T: A. May 11, 1943, No. 7474. [Classes 83 (ii) and 83 (iv)] In an electric resistance welding machine for forming a continuous seam or series of overlapping or spaced spot welds between the edges of fluid-tight sheet metal boxes, tanks, &c., a number of stationary electrodes co-operate with a number of electrodes which are given a rolling movement with respect to the work to produce a number of welds. A machine for welding the flanges 45, 46 extending from the halves 42, 43 of a rectangular can comprises a pyramidshaped frame, each sloping side 1 of which has bolted thereto a plate 2 provided with curved guides 3, 4 for rollers 8, 9 at the corners of a sector-shaped electrode holder 5, the centre of which carries a spindle 10 on which are mounted rollers 11, 12 running on tracks 13, 14 mounted in the main frame. An electrode 6 is bolted to the curved edge 7 of each holder so that when the rollers 11, 12 are traversed along the tracks 13, 14 by a motordriven lead screw 15, the electrode rolls along the flange 46. The work parts rest on a support at the top of the frame and have their flanges 45 engaged by four stationary electrodes 35 secured to holders 34 which may be moved towards and from the work into positions to permit insertion and removal of the work in guides in an upper frame 33. The movement is effected by cam slots 38 in a ring 36 operated by fluid pressure piston 41 through a link 40 engaging rollers on pins 39 carried by the electrode holders. , The holders 34 are corinected to one terminal of the welding circuit, the other of which is connected to the movable electrodes by flexible conductors 31 secured to a stepped contact plate 28 which extends through an opening in the plate 2 and is pressed into engagement with the holder 5 by springs bolted to the plate 2. The electrode pressure is varied by set-screws 22 which through a plate 21 and rubber strip 20 adjust the track 13 vertically. The track 14 is secured to the plate 2 by bolts passing through elongated slots and is urged downwardly by springs to accommodate upward movement of the roller 12 when the screws 22 are adjusted. When the screws 15 are rotated, the electrodes 6 roll on the work flanges to effect the welds, limit switches cutting out the welding circuit automatically when the weld is complete. The ends 6a of the electrodes may be curved to extend round part of the adjacent sides of the work to obtain a number of overlapping welds. The screws 15 may be connected together by bevel gears 1& and driven from a single motor through variable speed gear and clutch, a trigger mechanism being provided actuated by the electrode holders 5 to disengage the clutch on completion of the weld. Alternatively, each screw may be driven by a separate motor, cams being used to vary the speed of the motors as the welding proceeds and also the strength of the welding current. An automatic timing device may be used to interrupt the welding circuit intermittently so as to cause pulsations of current to produce a series of closely spaced spot welds and the time intervals of the pulsations may be adjusted to cause the spot welds to overlap to produce a continuous seam. When the adjacent sides of the work are at a suitable angle to each other, one pair of cooperating electrodes 6, 35 may be used to weld along two or more sides. When welding long seams, two or more pairs of electrodes may be used for each side.