Patent ID: 8987627
Filing Date: 2015-03-24
Classification: B21B,B21C,B23K

Abstract:
1. A method of continuously forming a dual seam welded tubular product, using a first forming roller pair having an outer concave roller and an inner convex roller, and a second forming roller pair having an outer concave roller and an inner convex roller, wherein the inner convex roller of the first forming roller pair and the inner convex roller of the second forming roller pair overlap in an longitudinal plane, the method comprising the steps of: (a) providing a first coil and a second coil of sheet metal material; (b) uncoiling the first coil and the second coil and forming the material into two opposing generally semi-circular half-tubes and bringing the two opposing half-tubes together at a convergence angle by feeding the material of the first coil longitudinally through the first forming roller pair, and feeding the material of the second coil longitudinally, through the second forming roller pair; and (c) electric resistance welding the two seams created between the two opposing half-tubes.