GB906702A - Tube forming die assembly - Google Patents

Abstract

906,702. Making longitudinally-seamed tubing; drawing; bending. FLEXONICS CORPORATION. April 28, 1959 [April 29, 1958], No. 14492/59. Classes 83 (2) and 83 (4). A die assembly, for forming into tubing metal strip moved longitudinally through the die assembly, comprises a die structure defining a generally straight elongated throat having an inlet end adapted to receive flat metal strip and an outlet end shaped to discharge a tube, the throat having a transverse shape which changes progressively from a generally flat form at said inlet to a generally circular form at the outlet, the die structure including principal forming stages spaced from each other longitudinally along the throat and provided narrow principal forming surfaces disposed in transverse relation to the throat and defining short longitudinal segments thereof. Stainless steel strip 30 is pulled, by means 38, through skelping die means 34, an aluminium bronze draw ring 42 and past a welding station 36, to butt or lap weld the longitudinal seam. The die means 34 includes a series of spaced plate-like principal forming stages 50, 60, 74, 88 and 102. The first stage 50 comprise straight upper and lower aluminium bronze bars 54, 56 with strip engaging edges of rounded crosssection. The principal stages 60, 74, 88 and 102 each have a convex upper aluminium bronze bar co-operating with a concave lower bar to bend the strip up to tubular shape, each succeeding stage having a greater curvature than the last. Auxiliary forming stages 116, 124, 130 and 136 are positioned after each stage 60, 74, 88 and 102, and each comprises a pair of maple wood blocks 118 suitably shaped and tapered to support the sides of the strip and guide it to the next principal forming stage, the blocks being suitably adjustable to compensate for wear. For heavier gauge strip upper and lower rollers 190, 192, Fig. 19, may be provided between the die means 34 and draw ring 42 to prevent the edges of the strip from springing out. U.S.A. Specification 2,612,580 is referred to.