| 摘要 |
1,225,502. Welding by fusion. UNION CARBIDE CORP. 25 June, 1968 [27 June, 1967], No. 30166/68. Heading B3R. [Also in Division H2] In consumable electrode arc-welding in which the electrode is fed by a D.C. constant field motor, e.g. a shunt, separately excited or permanent magnet excited motor, the welding supply is switched off to extinguish the arc, after the power supply of the motor has been disconnected, when the voltage generated by the motor during coasting falls to a predetermined value. Closure of a start-stop switch 10 actuates a start relay 12 which energizes contactor relay 20 to connect the welding supply P across the electrode E and the work W. Start relay 12 connects the motor supply and control G to the motor M. Start-stop switch 10 also actuates relay 25 to connect a non-linear resistor 9 and a stop relay 7 across the motor M. The arc strikes when the electrode E contacts the work W. To stop welding, the start-stop switch 10 is opened and the release of the start relay 12 disconnects the motor supply and control G and shunts the motor M with a braking resistor 15. When the voltage generated by the coasting motor M falls sufficiently, relay 7 releases the welding contactor relay 20 to disconnect the welding supply. Subsequently after capacitor C has discharged, relay 25 falls back. An inching switch I is provided. Solid state devices may be used to assist or replace relay 7. |
