GB1437469A - Device for electric arc welding - Google Patents

Abstract

1437469 Welding by fusion MESSER GRIESHEIM GmbH 23 Nov 1973 [24 Nov 1972 5 Sept 1973] 54468/73 Heading B3R [Also in Division H2] In a device for electric arc welding with a consumable electrode, the motor of the electrode feed device is driven from a control transformer winding magnetically coupled to the primary winding of the welding current transformer. The control transformer winding may be either part of the primary winding or a secondary. A control element comprising a variable choke or resistor may be coupled between the control transformer winding and the motor. Alternatively a fixed predetermined voltage may be connected in series with the control winding and the motor voltage may be derived from the secondary winding of a correction transformer in the control winding circuit. The correction transformer may be an autotransformer. The predetermined voltage, which is preferably derived from a transformer secondary permits the attainment of a desired relationship between welding and control voltage. As shown, a shielded arc welding system using CO 2 or CO 2 mixed with Ar, He or O 2 fed from supply 29, comprises a welding transformer 14 having tapped primaries 16, and secondaries 23 and rectifiers 24, the rectified current being fed to electrode 25 and workpiece 26. The electrode wire is driven by rollers 30 from motor 31, which is powered by the rectified supply 32 from the secondary 42 of correction autotransformer 40. The primary supply to this transformer is derived from the control winding 33 which is wound on one primary winding 16 or from taps 44 on the winding. The fixed predetermined voltage is derived from the tapped secondary 37 of mains fed transformer 34. Switchable resistors 47 pass and the variable tappings on the autotransformer permit adjustment of the feed rate. For the initial loading of electrode wire into the torch 26, switches 38 and 44 can be closed and switch L5 opened so that the electrode is not live. The system gives automatic change of electrode feed rate with change of primary voltage tapping (i.e. change of current).