Patent GB-1266321-A (GB)
IPC: B23K9/028
Filed: 1968-03-01
Abstract: 1,266,321. Welding by fusion. F. P. GILL. 30 May, 1969 [1 March, 1968], No. 10086/68. Heading B3R. In the operation of a rotary arc (e.g. argonshielded) welding machine, the rotation of the workpiece is speeded up after completion of one revolution so that the heat applied to the seam is smoothly reduced and hence crater formation in the weld metal is obviated or mitigated. As shown, the machine comprises a chuck 6 driven by a variable-speed motor 2 through reduction gear-boxes 3 and a belt 4, a slide 11 carrying a toggle actuated and screw-locked back centre 10 and a welding head 12a, a motor speed controller 7 incorporating an operating lever and stop/start switch (not shown), and an argon arc high frequency and suppressor unit 8 connected to a contactor box 9. The welding head 12a is lockable against longitudinal movement on the slide 11 and comprises an argon arc electrode holder and nozzle unit 19 carried on a cranked arm 18. The latter is longitudinally and rotatably adjustable and screw-lockable in a sleeve 16 which is pivotable, in a generally horizontal plane, in a block 14 in turn pivotable in a vertical plane. The arm 18 also carries, longitudinally and rotatably adjustable and screw-lockable thereon, a collar 21 in which a guide arm 23 is adjustable and screw-lockable. A tension spring 30 biases the sleeve 16 downwardly. A tension spring 26 is connected between an arm 25 fast with the sleeve 16 and an arm 28 pivotable about a pivot member 17. With a keep 29 connected across the spring 26, the sleeve 16 is free to swing in its generally horizontal plane, whereas with the keep removed and the arm 28 swung and stationed to one side or the other by engagement of a post 27 of the arm with the block 14, the sleeve 16 is biased in one or the other generally horizontal direction. When circumferentially welding together two halves of a float (not shown) supported by the chuck 6 and back centre 10, a grooved roller is attached to the arm 23 and the arms 18, 23 and collar 21 are adjusted and locked so that the float halves are located in the roller groove and the unit 19 is correctly positioned with respect to the seam to be welded. The spring 30 downwardly biases the roller and the unit 19 into position. The machine is thereby set for batch operation. In operation, the operator sets the lever of the controller 7 to give a suitable welding speed and the start/stop switch is actuated by the operator to start the motor 2 and the welding. When the float has completed one revolution (indicated by a scale) the operator moves the lever back to an extreme position in which it acts on the start/stop switch to stop the motor and to cut welding current, and during this movement the lever is so arranged as to cause the motor 2 to be speeded up smoothly until the welding current is cut. The guide roller ensures that the unit 19 accurately follows any workpiece deviations. During the use of the roller the keep 29 is fitted and the spring 26 inoperative. Where a workpiece is such that a guide roller cannot be used, the arm 23 fitted is provided with a cranked end and the spring 26 is rendered effective to bias said cranked end into engagement with a shoulder or end of the workpiece so as to guide the unit 19.