GB955154A - Improvements in and relating to finned tubes and method for the production thereof - Google Patents

Abstract

955,154. Making helically-finned tubing; coiling; angular bending; corrugating; soldering. HALBERGERHUTTE G.m.b.H. Nov. 24, 1960 [Nov. 27. 1959; Oct. 7, 1960], No. 40491/60. Headings B3A, B3E and B3R. A finned tube is made by forming a strip into channel section with a web and two side flanges, then winding it helically on the tube with the flanges extending outwardly and bonding the web portion to the tube. Copper strip 1 is guided by rollers 2, engaging its edges, to a pair of rollers 3, which bend the edge portions of the strip obliquely up relative to the centre portion, then to rollers 4, which transversely corrugate the centre portion, then to rollers 5 and 6 which form the strip into channel section. The centre web of the channel section strip may then be heated by a gas heater 11 before passing through a pickling bath 7, where the side flanges or fins of the channel are cooled by an air jet 12, through a solder tank 8 which coats the underside of the centre web of the channel with solder. The channel strip is then wound helically on to a tube 13, rotated and moved axially, by pressure rolls 15, 16, 17. The flange edges of the channel are stretched, so that the channel will remain coiled on the tube 13, by a tool 18 between the rolls 16 and 17. The tool 18 comprises, Fig. 7, four hard needles 19, 20, 21, 22 between which the channel flange edges pass to be deflected, and thus stretched, and then straightened. The free end portions of the needles are of conical shape. Separate flange straightening means may be provided on the roller 17 by forming the roller of a flat central disc and two outer sections each defining a groove 24, Fig. 9, with the central disc. The channel strip is secured to the tube 13 by heating with a gas burner, at a point along the tube beyond the coiling point, so as to melt the solder. In modified coiling means, Fig. 10, the first roller 16 is spaced an angle B from the point on the tube 13 to which the path of the strip 1 is tangential, a spring 35 urging the strip into contact with the tube. The roller 16, and if desired the roller 17, may comprise a centre section 36, Fig. 11, and two outer discs 37 urged together by springs 38. Alternatively, the rollers 16, 17 may comprise three discs 41, 42, Fig. 12, inclined to one another. A modified stretching tool 18<SP>1</SP> may be used and comprise a rod adjustable in a sleeve pivoted at 43 and have two grooves, Fig. 13, or a single broad groove, Fig. 14 (not showh), at its end to accommodate the channel flanges. Welding by pressure.-To equip a steel tube with aluminium fins the tube is first coated with an alloy of 95% aluminium and 5% magnesium, sprayed thereon after sand-blasting, and the fin secured by pressure-welding.