GB949037A - Electric arc welding - Google Patents

Abstract

949,037. Welding by fusion. BRITISH OXYGEN CO. Ltd. Aug. 11, 1960 [Aug. 14, 1959], No. 27944/59. Heading B3R. In a method of arc welding spaced in line butt joints in which relative movement between a welding head and the work is effected at welding speed during the welding operation and at the same or a faster speed between welding operations, and in which the relative movement is halted for predetermined periods at the beginning and end of each operation during which periods the arc is struck or extinguished, the periods occur when the welding head is over the work but spaced a short distance from the ends of the joint and weld metal is allowed to melt back or forward to the ends of the joint where it is supported until solidified. The movement may be controlled photo-electrically as described in Specification 935,586 or by a mechanically operated cam arrangement. In a machine for butt welding the projecting portions 107 of two castellated beam halves 105, 106 to form an I-beam, the joints are backed by a bar 113, e.g. copper, on which are positioned damming members 114 which may be recessed and which serve to retain granular flux 115 against the edges of the portions 107. When the welding head 100 dwells over the point X near the beginning of the joint the arc is struck using a high-frequency voltage and the weld melts back to the supporting flux 115. When the welding head 100 dwells over the point X near the end of the joint, feeding of the electrode is stopped and the electrode burns back before the welding current is interrupted. Meanwhile, the weld melts forward to the supporting flux 115. The flux 115 may be deposited before welding commences or where a submerged arc welding head is used, the flux is deposited from the flux nozzle 119 preceding the electrode.