GB1237325A - Improved helically wound tubing - Google Patents

Abstract

1,237,325. Making tubing; coiling; seaming; perforating. BOWATER FLEXPIPE Ltd. 13 Oct., 1969 [17 Oct., 1968; 12 May, 1969], No. 50122/69. Headings B3A, B3E and B3J. [Also in Division F2] A method for the manufacture of helically wound metal tubes comprises longitudinally corrugating aluminium strip 1, see Fig. 1, by rolls (not shown), after which ribs 2 and 3, Fig. 4, are formed by rolls 4, the ribs 2 and 3 being deepened by rolls 5, 6 and 7. The edge margins of the strip are then turned down to form a channel element 11, see Fig. 6, and a flange element 12 having convexities 10. The strip is perforated by passing it between a spiked roll 37, see Fig. 16, and a backing roll 36 which can be moved towards or away from each other by operating a ram 43 which pivots a bracket 39 about a pivot 41. As the strip is fed to a forming head 17 it passes between rolls 21 and 22, see Fig. 8, and is coiled about a mandrel 18 with the flange 12 lying in the channel 11. The strip then passes between rolls 23 and 20 which deform the ribs 2 and 3 inwardly to partly close the mouth of the channel 11. As the partly formed seam continues around the mandrel it again passes rolls 21 and 22 which crush the seam flat. In a second embodiment, Fig. 13, a driven, grooved forming roll 23a provided with a V- groove 30 inwardly deforms the ribs 2 and 3 and the partly formed seam is flattened by a roll 31 placed at the end of the mandrel. In a third embodiment the strip has an L- shaped flange 51, Fig. 18, formed on one edge and a U-shaped channel 52 formed on the other edge, the channel 52 having its open mouth directed inwardly of the formed tube. The flange 51 is mated with the channel 52 and as the strip passes around the mandrel, it passes between rolls which nip-in the base of the channel to partially close its mouth as shown at A in Fig. 18. As the seam passes further around the mandrel it is finally flattened by the rolls 21, 22. In a fourth embodiment one edge of the strip has a pair of ribs formed on it which are outwardly directed with respect to the tube (Fig. 19, not shown), and the other edge has a pair of channels formed with their mouths facing inwardly with respect to the tube. As the strip is convoluted about the mandrel, the ribs are first mated with the channels after which the channels are spread apart and finally they are flattened down to form the locked seam.