GB1020133A - Fabricated finned tubing and method for making the same - Google Patents

Abstract

1,020,133. Making helically seamed finned tubing; angular bending; coiling welding by pressure; soldering. CALUMET & HECLA Inc. March 29, 1963 [June 11, 1962], No. 12644/63. Headings B3A, B3E and B3R. [Also in Divisions F2 and F4] A helically wound tube comprises a continuous length of strip of generally U-shaped crosssection having a pair of edge flanges 42, 44 which are tapered towards their free edges, the strip being coiled into a tight helix with the outer side surfaces of the flanges of adjacent convolutions of the strip in abutment and bonded together. A strip 30 of a material, e.g. metal or synthetic plastics, is fed through a flange forming roll assembly 34 including rolls 36, 38 and an anvil 40 and thence through an assembly comprising tapering rolls 48, 50 and a stationary anvil 46 to taper the outer face of each flange before being applied to the rotating mandrel 32. The tapering rolls and anvil assembly may be positioned as shown in broken lines in the drawing whence only one set of abutting flanges will be tapered. The rib of the finished tube may comprise flanges of equal height and joined over their whole surface area (Fig. 1, not shown) or only at their outer peripheries the remainder of the flanges being spaced relative to each other (Fig. 3, not shown) or one flange is short and is joined to the base of a longer flange (Fig. 2, not shown). The windings of the tubing may be joined by welding, brazing or soldering in the caes of metal or by heat and pressure treatment in the case of synthetic plastics material. A supply of brazing or soldering rod may be fed to the junction zones in the wound tubing through a passage in the rotating mandrel, the flanges of the tubing being initially connected by spot welding or dimpling at 180-degree intervals during the winding operation and finally connected by passing the tubing through a furnace or induction coil to effect the brazing or soldering (Fig. 8, not shown). In a modification (Fig. 9, not shown) the brazing or soldering rod is brought into engagement with the strip and then wound with the strip into the tubing. The flanges may also be continuously welded together (Fig. 10, not shown). In a further embodiment a short length of tubing is formed on a collapsible rotatable mandrel and then, to prevent unwinding, mounted between clamping members and finally the assembly after the removal of the mandrel is placed in the furnace or induction coil for the joining operation (Fig. 11, not shown). The tubing may be of aluminium, copper or steel.