GB1330861A - Production of tube by helical winding - Google Patents

Abstract

1330861 Wrapping cores with metal IMPERIAL CHEMICAL INDUSTRIES Ltd 18 Jan 1971 [27 Jan 1970] 3923/70 Heading B3E [Also in Division F2] Tube is produced by forming overlapping helical windings of plastics or metal ribbon and bonding adjacent windings together, the margin of the ribbon that forms the overlap being differentially heated before winding so as to expand this margin with respect to the remaining width of the ribbon and hence substantially compensate for the additional circumferential distance encompassed by this lap margin during winding. The lap margin may also be mechanically stretched before the ribbon is wound to form the tube. In a preferred method of manufacturing foam laminate tubes, a tubular core 21 which may be self-supporting or supported by a mandrel is advanced longitudinally and rotated by means of belt and pulley drives 23, 24, 27 and 28. Ribbon 2 is drawn from a supply roll (Fig. 2, not shown) by rotation of the core and fed by rollers 3, 5 over table 4 and under foam dispenser 9, the foam-forming composition 10 being deposited so as to leave a substantially uncoated strip 11 on the leading edge of the ribbon, this strip forming the lap margin. The table 4 is pivoted (6) under the axis of the advancing core and is movable in an arc about the pivot point on a wheel (7) to allow for changes in the angle of winding. The stop 11 is then heated by means of electric heating unit 12, the foam-forming composition being protected by a curtain of cold air supplied through pipe 20 (see also Figs. 3, 4, not shown). Before winding the ribbon on to the core the lap margin may be further stretched by, for example, passing it between a pair of frustoconical rollers. The period between application of the foam-forming composition and winding of the ribbon is arranged so that the composition is still tacky on winding hence bonding adjacent windings together. The strip may be, for example, of aluminium, copper or steel.