GB608636A - Improvements in or relating to arc welding control systems - Google Patents

Abstract

608,636. Automatic control systems for arc welding. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. Dec. 14, 1945, No. 33913. Convention date, Aug. 10, 1944. [Class 38 (iv)] In an automatic arc-welding electrode feed control system, means producing a control voltage for an electrode feed motor include a saturable transformer connected to the arc electrode circuit to develop an arc responsive voltage greater proportionately under arcing conditions than under open circuit conditions. A welding electrode 12, supplied through a transformer 15 from A.C. mains 18, is fed toward work 13 by a D.C. motor 11 connected to a variable voltage D.C. generator 24 driven by a D.C. motor 25 connected to a constant voltage D.C. generator 27 driven by an A.C. motor 28 connected to mains 18. The field 30 of generator 24 is energized by a voltage dependent on arc voltage, obtained through a rectifier 33 and a transformer 32, in opposition to the portion of the voltage of generator 27 obtained from a potentiometer 35, so that the electrode feed is such as to maintain arc voltage constant. With a main switch 19 closed, starting is effected by the operation of relays 38, 40 and 21 in consequence of the operation of a push-button 36 and the electrode is advanced slowly until the arc is struck since a relay 44 is energized by the higher-thannormal voltage from rectifier 33, due to the higher open-circuit voltage applied to transformer 32, to insert a resistance 42 in series with field 30. Transformer 32 is arranged to saturate under these conditions so that its effective ratio is reduced and excessive voltage to rectifier 33 avoided.