GB802997A - Improvements in or relating to the manufacture of tubing - Google Patents

Abstract

802,997. Making seamed tubes; angular bending; brazing. BUNDY TUBING CO. May 13, 1957 [May 21, 1956], No. 15033/57. Classes 83 (2) and 83 (4). A method of making tube comprises forming moving strip transversely to form a tube with overlapping portions, feeding bonding metal inside the tube, passing the tube through a heating zone with an edge of the overlap at the bottom so that molten bonding metal enters and flows throughout the interfacial area after which the bonding metal is solidified. Strip 2, Fig. 1, e.g. steel or the metal known under the Registered Trade Mark " Monel," from a coil 1 is curled transversely about an arbor 12, Fig. 3, through 720 degrees in a roll-mill 30 to form a tube having an outer ply 4, an inner ply 5, and a seam 10 with interfaces 8 and 9, Fig. 2. The trailing edge of the strip is temporarily flanged at 11 to resist the compression forces due to the lateral movement to effect curling round the arbor. The arbor makes contact with the inside of the tube only at the point where final rollers 15, 16 bring the interfaces into tight engagement. Bonding metal 21, e.g. copper, copper alloy or other suitable hard solder in wire form is drawn from a coil 20 into a passage 18 through the arbor 12 and into the tube. Alternatively the bonding metal may be powder or fine particles which are forced through the passage 18. The tube 3 is then passed through a furnace 25 having a non-oxidizing or reducing atmosphere and heated by current from electrode rollers 26, 27, 28 connected as shown to simplify insulation of the apparatus. Molten bonding metal is thereby caused to enter the interface at 8 and flows circumferentially throughout the interfaces. Finally the tube passes through a cooler 42.