Rotary arc-welding apparatus

Claim 1

A rotary arc-welding apparatus which comprises: a nozzle rotatable about the center axis thereof at a high speed, said nozzle having in the interior thereof a passage for directing a consumable welding electrode eccentrically from the center axis of said nozzle toward a groove formed between objects of welding; a consumable welding electrode feeding mechanism, provided above said nozzle, for continuously directing said consumable welding electrode toward said groove through said nozzle; a welding current feeding mechanism for feeding a welding current to said nozzle to produce an arc between said groove and the tip of said consumable welding electrode passing through said nozzle; a nozzle rotating mechanism for rotating said nozzle about the center axis thereof at a high speed to cause a circular movement of said arc from the tip of said consumable welding electrode corresponding to the eccentricity thereof, said nozzle rotating mechanism comprising a motor fixed to a carriage, gears for transmitting the rotation of said motor to said nozzle, and a gear box for housing said gears, said gear box rotatably supporting said nozzle passing therethrough; and a shielding gas feeding mechanism for feeding a shielding gas toward said arc and a weld zone to shield said arc and said weld zone from the open air; characterized in that: said welding current feeding mechanism (8) comprises: a circular current receiving plate (9), which is fixed to the upper end of said nozzle (1) and rotates together with said nozzle (1) about said center axis, said current receiving plate (9) having at the center thereof a passage (10) for said consumable welding electrode (4); a circular brush (11), having substantially the same diameter as that of said current receiving plate (9), for feeding said welding current to said current receiving plate (9), said brush (11) having on the upper surface thereof a current feeding plate (13), the lower surface of said brush (11) and the upper surface of said current receiving plate (9) having a flat contact interface (12) therebetween, and said brush (11) and said current feeding plate (13) having at the center thereof a passage (23) for said consumable welding electrode (4); a plurality of rods (19) for stationarily holding said brush (11) and said current feeding plate (13) so as to prevent same from rotating together with said nozzle (1) and said current receiving plate (9), the lower halves of said plurality of rods (19) being inserted into said brush (11) and said current feeding plate (13), and the upper end portions of said plurality of rods (19) being secured to a supporting plate (21) fixed to said carriage; a plurality of springs (22) for applying a pressure onto said contact interface (12) between the lower surface of said brush (11) and the upper surface of said current receiving plate (9), said plurality of springs (22) being provided between said supporting plate (21) and said current feeding plate (13); and, said pressure applied by said plurality of springs (22) onto said contact interface (12) between the lower surface of said brush (11) and the upper surface of said current receiving plate (9) being such that, when actuating said nozzle rotating mechanism (5), said nozzle (1) and said current receiving plate (9) rotate whereas said brush (11) and said current feeding plate (13) do not rotate, and said welding current smoothly flows from said brush (11) to said current receiving plate (9).