GB1445427A - Adjustable former - Google Patents

Abstract

1445427 Adjustable former CREATORS Ltd 30 July 1974 [9 Aug 1973] 37903/73 Heading F2P An adjustable former around which a strip may be helically wound to form a tube, comprises a primary inner forming roller 10, a series of auxiliary inner forming rollers 11-13, a series of inner guide rollers 19, a primary outer forming roller 16 and a series of outer guide rollers 18 said rollers 10, 11-13, 16, 18 and 19 being supported by a plate 14. Each inner roller (11-13) and its opposing outer guide roller 18 are mounted on a base member 27 which is releasably secured to the plate 14 by a locking stud which can be secured at any desired position along a guideway 25, roller 18 being adjustably secured to the base member 27 by an arm 30. The primary outer forming roller 16 forms a sealing nip with roller 10 which is rigidly fixed to the plate 14, the gap of said nip being variable by altering the position of roller 16 relative to roller 10. The inner guide rollers 19 are mounted on base members which are releasably secured in selected locations along their respective guideways 26. The rollers 10-13, 16 and 18 are driven at the same peripheral speed. To form a reinforced tube 9, thermoplastics tape (e.g. P.V.C. tape) 21 and reinforcement 22 in the form of P.V.C. covered wire are fed to the nip between rollers 10 and 16 via rollers 34 and 35 respectively. A hot air sealer 20 heats the strip 21 and reinforcement 22 before they enter the nip. The strip 21 and reinforcement 22 are helically wound, following a path 15 defined by the inner rollers 10-13 and in such a way that the longitudinal edges of each turn of the strip overlap each other and the reinforcement, said edges and reinforcement being heat sealed together in the nip provided by rollers 10 and 16. The rollers 10-13, 16 and 18 are helically grooved and when driven, tend to impart axial movement to the formed tube 9, which the removal of is assisted by a haul-off device (not shown). By altering the positions of the adjustably mounted rollers 11-13, 18, 19 on plate 14 the shape and thickness of path 15 and hence the shape and wall thickness of the tube 9 produced on the former, can be varied. The former may be used to produce a tube comprising an outer winding (40) (Fig. 3, not shown) of thermoplastics material and an inner winding of a reinforcing member (41) covered with thermoplastics material (42) the edge portions of adjacent overlapping turns of the outer member being heat sealed together and to the inner winding in such a way that the sealed overlap is restricted to a sector bounded by an arc (43) subtending an angle of not more than 100 degrees, the boundary radii of which intersect at the adjacent centre of the reinforcing member (41).