GB1349909A - Manufacture of heat exchange tubes - Google Patents

Abstract

1349909 Coiling; making heat exchangers; shearing GENERAL ELECTRIC CO 8 July 1971 [13 July 1970] 32152/71 Headings B3E B3A and B3W In a method of simultaneously winding two metal strips 16, 17, Fig. 9, onto a tube the strips are fed to two diametrically opposite rolls 18 of a winding head 10 from a coil 141 consisting of the two strips wound in an interleaved double spiral. In operation the coil 141 is rotated by a table 14 at a faster rate than the winding head so that at the start of the winding operation an inner coil B is built up around the winding head. The building up of the coil B continues until approximately one half of the strips have been removed from the inside diameter of the coil 141, whereafter the thickness of the coil B begins to decrease. After passing guide rolls 18 the two strips are guided by guides 19, Fig. 1, rolls 21, 22 and guides 23 to their respective lancing stations 24. The lancing stations, Fig. 4, impart cuts to each strip, the cuts extending in from adjacent opposite edges (Fig. 4a) and the cutting being effected by a drive roll 31 and idle rolls 32, 33. The lanced strips 16a, 17a pass to forming stations 26, Fig. 5, where each is engaged by a drive roll 40 and is carried in a groove 46 of the roll 40 until it engages an idler roll 42. At this point the lanced strip is bent into a U-shaped configuration. The strips 16b, 17b then pass to hemming stations 27, Fig. 6A, where each U-shaped strip engages a roll 58 at a point ahead of rolls 57, 59, 61. As the strip is carried through the nip of the four rolls, the strip is deformed to provide a hemmed base 91 having diverging fins. Finally the hemmed strips 16c, 17c pass around guide rolls 28 and are wound on to the tube 12 to produce the finned tube shown in Fig. 7. If the materials of the tube and strips are different, e.g. aluminium and iron, the tube is first coated with a dielectric adhesive layer 130 to prevent galvanic action.