GB1258561A - - Google Patents

Abstract

1,258,561. Welding by fusion. WELDING INSTITUTE. 31 Dec., 1968 [2 Oct., 1967], No. 44725/67. Heading B3R. In electric welding using, e.g. electron beam, T.I.G., or micro-plasma arc processes, in which a thin consumable filler wire is fed into the molten weld pool, the filler wire 2 is guided by a guide which causes the wire to enter the weld pool along a curved path which is convex towards the work, and which guide affords surfaces for guiding the lateral and outer circumferential surfaces of the wire which is fed into re-entrant surfaces 3, 4 formed in the work. Welding apparatus includes a torch 5 and wirefeed mechanism 12 (Fig. 1) in which filler wire passing from a reel 11 over a dancer-arm wheel 16, fixed pulley 22 and traction wheel 23 cooperable with an adjustably biased pressure roll 25, enters a guide tube 31-extending to adjacent the weld pool. Both the wheel 23 and roll 25 are formed with V-groove peripheries for receiving the wire. The guide tube 31 includes an inner tube 33 of stainless steel adjustably retained at its upper end by a nylon collet 35 and projecting at both ends from an outer soft copper tube 32 mounted at its upper end in a split ball joint 34 allowing angular, rotational and axial adjustment. The centre of curvature of the guide tube lies approximately on the perpendicular from the weld pool. By virtue of the relative locations of the tip of the inner tube 33 and the groove defined by the surfaces 3, 4, the filler wire is sprung into the groove and guided thereby to the weld pool. In butt welding thin sheets either or both abutting surfaces may be chamfered to form the groove, and the chamfers may be plane, concave or convex. The surfaces of the workpieces 1 to be joined may be aligned (Fig. 3, not shown) or staggered, as shown. The workpieces and wire may be of maraging steel. The torch 5 which has an electrode (6) (Fig. 2, not shown), an inner duct (7) for passage of argon plasma-forming gas, and an outer annular duct (8) for shielding gas comprising argon and 1% hydrogen, is adjustable on the plate 13 of the wire feed mechanism and the plate 13 is carried on a manually operated XY axis traverse slide head mounting (not shown). The wire reel 11 is braked, and a motor having an electro-mechanical governor drives the traction wheel 23 via step-down gearing. The work may be fed past the torch.