GB179613A - Improvements in and relating to electric arc welding systems and apparatus therefor - Google Patents

Abstract

179,613. British Thomson-Houston Co., Ltd., (General Electric Co.). Feb. 4, 1921. Heating by electricity.-Consists in an electricarc welding system of the type in which the are is struck and the feed of the electrode and work are regulated automatically and which is adapted for use with different types of supply circuits. The movable electrode is fed by an electric motor which when feeding the electrode is subject to the voltage between the electrodes, but when reversed to withdraw the electrode to strike the arc is subject to the difference between the voltage of the system and the potential difference across the electrodes. Fig. 1 shows diagrammatically an arrangement in which the work 3 is traversed automatically by a screw 6 rotated by an electric motor 7. The electrode 1 is fed from a reel 2 by rollers 9, 10, the latter of which is connected by a brush to an intermediate main 15. The welding current passes from the main 13 through a resistance 58 to the work and through the electrode 1 to the main 15. The feed-rollers are driven by an electric motor 11, the armature of which is in a shunt across the arc. The field 12 is independently energized from the main 13. The main 15 when the machine is in use, is coupled by a switch 18 through an adjustable resistance 17, to the main 16. To start the machine the push-buttons 20, 21 are closed to complete a circuit between the mains 13, 16, through a coil 19 which then closes the switches 18, 22 and short circuits the button 21. The current now flows round coils 25, 28, 34. The opening of switch 33 cuts out the coil 38 so that the switch 37 remains in the position shown and the motor 7 remains at rest. The rising of the switch 26 opens the circuit through the armature of motor 11, but as the field 12 is strongly energized the armature rotates slowly to feed the electrode 1. When the latter touches the work the coils 25, 28, 34 are de-energized. The closing of the switch 24 sends a reverse current through the armature to reverse the motor 11 and raise the electrode 1 to strike the arc. The coil 38 is then energized to raise the switch 37 and start the motor 7 to feed the work. A vibrator 31, 32 and resistance 30 control the current through the field 12 to regulate the speed of the motor 11 and so keep the length of the arc constant as described in Specification 139,919. In a modification, a welding circuit of the balancing type as disclosed in Specification 133,439 may be used. In another modification a welding-generator of the type described in Specification 159,374, [Class 35, Dynamo-electric generators &c.] may be used. Specification 145.330 is also referred to.