GB155899A - Improvements in and relating to electric welding machines - Google Patents

Abstract

155,899. British Thomson - Houston Co., Ltd., (General Electric Co.). Sept. 22, 1919. Welding.-In an electric resistance line-welding apparatus, a number of electrodes are arranged in tandem so as to move alcng the seam, and thus effect a longer weld with a given stroke of the electrodes. The movable electrodes are preferably connected in series, the weld. ing circuit being completed through a stationary electrode on the other side of the work so as to maintain a substantially constant impedance. Two series of electrodes 8, 9 mounted in turrets are respectively carried by arms 10, 11 insulated from each other at 20, 21 and connected to each other by a slot 13 and bolt and nut 12. The arm 11 is connected at 18 to one end of the secondary 15 of a transfcrmer 14, Fig. 1, the other end of which is connected at 17 to a shoe 16 in contact with the arm 10. The arms are provided at each side with uprights connected to cross bars 26 and through the uprights pass the shafts of rollers 27, 27 so as to form a carriage. The ends of the roll shafts are received in plungers 31 cushioned by springs in cylinders 32 on the cross-bars, the tension of the springs being adjustable to vary the pressure, of the electrodes on the work. The transformer moves with the carriage and may serve to exert pressure on the work. The rollers run on a pair of arms 35 connected together at 36, and pivoted to the frame at 37. The arms 35 are attached at the other end to levers 48 connected by a rocker arm 39 and lever 41 to a cam 42 which is operated by a handle 43 so as to raise the arms 35 and thereby raise the electrodes from contact with the work after welding or prior to changing the electrodes. This motion is assisted by a counterweight 45 connected by a cable 46 to a lever 44 pivoted to the shaft carrying the arm 39. The electrodes are positively rotated during their traverse by worm and spur gear, the wormwheel being mounted on the same shaft as a spur-wheel which engages spur gears on the roll shafts. The turret is prevented from rotating during operation by a worm-wheel 60 pressing a wcrm 57 against a shoulder 59. On reverse rotation of the carriage, the worm-wheel 60 pushes the worm 57 axially to the left and in so doing is rotated so as to remove the electrodes out of contact with the work as shown in Fig. 3. When the next piece of work is placed in position, the turret is rotated, after raising the arms 35, by a handle 61 so as to place the next electrode into working position. The work is placed on the adjustable stationary electrode 7. Specification 135,244 is referred to.