GB1372518A - Method and apparatus for electric arc welding - Google Patents

Abstract

1372518 Welding by fusion MESSER GRIESHEIM GmbH 22 June 1973 [24 June 1972] 29789/73 Heading B3R In a method of electric arc welding with a consumable electrode, a pulsating gas flow of a predetermined frequency is directed to the melting end of the electrode and the kinetic energy of the gas pulses breaks of the drops formed at the end of the electrode. The pulsating gas may be CO 2 , He, Ar, N 2 , Ne or a mixture thereof and may include between 1 and 15% O 2 . It may also be surrounded by a continuously flowing gas envelope of a shielding gas also of the above named kinds. In an apparatus for carrying out the method electrode 15 is fed by motor 18 controlled by circuit 12 which also controls the welding current such that the electrode feed may be continuous or discontinuous and the welding current supplied may be pulsed. Gas is supplied to a pulser unit 34 which may comprise a reciprocating piston 61 (Fig. 3, not shown) or flutter valves, or rotating chamber pistons. The pulsating gas is passed down passages 52, 51 of an annular clearance nozzle 33, 41 (Fig. 2) in torch 14, 40, the nozzle comprising two relatively movable screw-fitted parts 43, 44 whose conical interfitting ends provide an adjustable gas envelope directed towards the end of the electrode. Alternatively, the nozzle may comprise a plurality of orifices or individual nozzles disposed around the electrode. The second and continuous gas flow is provided by arrangement 13 and passes along pipe 57 to annular channel 54 in the torch which communicates through bases 55 with inner space 56 around the nozzle.