Patent GB-811217-A (GB)
Title: Improvements in or relating to welding apparatus
Inventor: RICHARDSON ERIC KENNETH
IPC: B23K9/028
Filed: 1954-12-31
Abstract: 811,217. Welding by fusion. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Dec. 13, 1955 [Dec. 31, 1954], No. 37734/54. Class 83 (4). [Also in Group XXXVII] Arc welding apparatus consists of a welding torch movable along a preset path by an electric motor drive, a first control for the speed of the motor and a second control ganged with the first and arranged to send signals to adjust the current output of a remote generator supplying welding current to the torch. A portable welding apparatus for use in butt-welding pipes 13, 14, Figs. 1 and 2, consists of a frame 10 carrying at its ends clamps 11, 12 which may be secured on the pipes 13, 14. A split collar formed of two portions 19, 55 hinged together is rotatably mounted on a bearing 42 mounted on the frame 10. Each portion 19, 55 carries half of a gear 20 rotatable by an electric motor 23 fixed on the frame. An argon shielded arc welding torch 16 is adjustably secured in a plate 34 having projections 37, 38, 47 in sliding engagement with a block 17 mounted on the collar portion 19. The plate 34 when in position is spring-urged towards the pipes 13, 14 and is spaced from the pipes by a ball rotatably held in a boss 36. In operation with switches HAR, BS1, BS2, ISS1, ISS2 closed, a projection 45a extending from the housing of the bearing 42, and a projection 45b retracted within the housing a control SDS, Figs. 1 and 4, is set to adjust the speed of the torch motor TM or 23 and a control R3 ganged to the control SDS sets the resistance of one arm of a bridge circuit R1 ... R4. Actuation of a start push button SPB operates relays SR, SC to connect up the welding generator and the bridge circuit R1 ... R4, respectively. If the bridge circuit is unbalanced, a relay PR operates a motor SM which adjusts a resistance in the output of the generator to set the welding current and simultaneously adjusts a variable resistance R4. When the bridge circuit is balanced PR disconnects the motor SM. Fifteen seconds after the operation of SR, relay GD releases SC and temporarily energizes, a surge injector SI to strike the arc. Relays DA, DB operate slowly and TF follows to start the feed motor TM to rotate the torch 16 through a complete revolution in the forward direction indicated by the arrow in Fig. 3. The rotary support for the torch 16 carries cams 50, 51 and 52 and a pivoted member 46. As the torch 16 regains a vertical position the cain 52 operates a switch TCS and the cam 46 rides over the projection 45a to lift the torch 16 away from the pipes 13, 14 and to cause the cam 51 to operate a switch CSA whereupon a relay RR disconnects the welding generator. The torch 16 continues to rotate until the release of the switch TCS when cleared by the cam 52 operates RG and releases SR, GD, DA, DB and TF so stopping the torch 16. After a delay, relay DC connects up relay TR to reverse the motor TM and relay DD energizes. When the torch 16 has completed a revolution in reverse, cam 52 re-operates the switch TCS and DE follows to stop the motor and to release all operated relays. In an alternative manner of operation the torch is moved into its lowermost position by means of an inching switch ITS with switch HAR open. Then, with a hand-operated forward/reverse switch HFR in the reverse position and projection 45b alone extended, the torch is driven in reverse and welds until lifted by the projection 45b. Cam 50 operates a switch CSB to release relay SR. The torch is then brought to the lowermost position by operating a reverse push-button RPB and the inching switch ITS. The apparatus is then set up for forward welding and the second .half of the weld is made as described above. Specification 811,216 is referred to.