GB1443792A - Method of and machine for welding moncircular cross-section pipes - Google Patents

Abstract

1443792 Welding by fusion AGIP NUCLEARE SpA 12 Sept 1973 [15 Sept 1972] 42949/73 Heading B3R [Also in Division F2] In end-to-end peripheral welding of hollow members, such as pipes, of polygonal crosssection, a MIG, TIG or plasma welding torch is reciprocated rectilinearly along the polygon sides and the hollow members are periodically rotated about their common longitudinal axis. In jointing of square-section pipes 1 shown in Fig. 1, a torch 2, energized, is moved forward (from left to right) with the pipes stationary so as to weld along one side of the pipes, and then the torch is moved back (from right to left) while the pipes are rotated, through 90 degrees, either clockwise or, as shown, anticlockwise to bring the torch and pipes into position for the next weld section. The torch is maintained at a constant distance from the workpiece as by an electromechanical constant arc length system. In Fig. 2, a torch carrier 15 is reciprocated by forward and reverse rotation of a screw 14 which is driven by an electric motor 25 via a 2-speed reverse gear 3. The latter comprises low speed (welding) and high speed (torch return) gear trains 6, 17, 18, 22, 12 and 6, 7, 11, 12 brought into operation by respective electrically operable clutches 20, 9. Automatic changeover clutch actuation is effected, e.g. electrically, upon engagement of the carriage with adjustable stop plates (not shown) which may be automatically adjustable to accommodate irregular polygonal (e.g. rectangular) cross-section pipes. Pipe rotation may be synchronized with the carriage movement by use of synchronized motors or by rotation of the pipes by means driven from the gear-wheel 11 via a third clutch.