Electrical resistance seam welding method and apparatus

Abstract

An electric resistance seam welding method and apparatus includes a continuous wire electrode which is passed successively over a first electrode reel and thereafter over a second electrode reel via a plurality of guide and deflection rollers, the outer surfaces of the wire confronting each other when passing over the reels and being pressed together by the reels by a predetermined welding force against interposed workpieces to be seam welded together. An electric current is applied so as to pass from the second electrode reel to the first reel through the wire electrode and the interposed workpieces, and the wire electrode is motor driven for feeding the workpieces through the reels. A copper wire is utilized as the wire electrode and has a tensile strength at the elastic limit of between 11 and 13 kg-f/mm.sup.2 and has a percentage elongation at break of 26 to 17%. The reels are pressed together by a force of 60 to 70 kg, and the copper wire is subject to a tensile stress of less than 10 kg-f/mm.sup.2 while passing over and between the reels. The reels are maintained at an operating temperature of 10.degree. to 30.degree. C. as the wire electrode passes thereover, so that a maximum elongation of the wire of 6% when passing over the first reel, and a maximum further elongation of the wire of 6% when passing over the second reel, is attained.