GB427863A - Improvements in and relating to arc welding systems - Google Patents

Abstract

427,863. Arc - welding systems. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London. Sept. 17, 1934, No. 26688. Convention date, Sept. 19, 1933. [Class 39 (iii)] In an automatic arc-welding system the electrodes 30, 31 are initially connected to the supply mains 3 through a high impedance and are afterwards connected to the mains through a low impedance coincident with the separation of the electrodes to strike the arc, and the operating speed of the feeding means is reduced after contact of the electrodes. The high impedance consists of the operating coil of the switch 18 and the speed reducing means consists of a shunt 60 to the armature circuit of an electrode feed motor 6 with oppositely wound fields 53, 66 selectively energized under the control of a switch 7 and relays 9, 10, in accordance with a characteristic of the arc. When switches 16, 14 are closed the coil of switch 17 is energized from source 11 to close the switch and connect the electrodes 1 to the mains through the high impedance. Coil 8 is thus energized from source 11 to cause operation of the motor 6. When the electrodes contact the switch 18 is closed. Closure of contacts 55 causes closure of switch 4 to connect the electrodes to the mains through the low impedance 19. Closure of contacts 56 inserts the shunt 60 in the armature circuit of the motor 6. Closure of contacts 57 short-circuits a protective resistance 61 in the circuit of coil 8. An impedance 20 may be inserted in the welding circuit in parallel with impedance 19, to increase the welding current, by closing switches 22, 24. The relative position of the electrodes may be controlled by hand by means of switches 12, 13. A plurality of similar welding systems may be connected to the same supply sources the switches 16, 24 forming master controls.