GB1358360A - Method of forming a tapered pipe - Google Patents

Abstract

1358360 Plastic pipes F USUI 15 Aug 1972 38080/72 Heading B5A [Also in Division F2] A tapered pipe is formed by:- (a) helically winding one or more layers of a reinforcing fibrous material on to a tapered mandrel, (b) inserting the mandrel and wound core into a tapered mould, (c) extracting the mandrel, (d) inserting the mould into a rotatable body and introducing liquid thermosetting resin into the core. (e) inclining the axis of rotation of the rotatable body to the horizontal so that the larger end of the core is uppermost and rotating it at a predetermined speed, (f) extracting the pipe thus formed from the mould when hardened. The pipe may be left straight until hardened or the mould may be flexible (see Fig. 11, not reproduced) and the centrifugal pipe may be bent in the mould before hardening. The mandrel may be provided with retractable pins to retain the wound material until the pins are retracted. Polyester, epoxy, phenolformaldehyde, melamineformaldehyde and polyimide resins, including finely crushed aggregates, are poured or sprayed into the mould. The mould is of aluminium, duralumin, synthetic resin, or wire reinforced rubber. As described, a tapered mandrel 1 (Fig. 2) is wound with fibrous materials 2 from reels 22 carried in rotating drums 21, the mandrel being moved axially the while by cords 26, 27 driven from motor 25, which motor also rotates the drums 21. The wound core is thus pulled into mould 4 and the cords 26, 27 are subsequently removed. The mandrel is then removed and the mould and core mounted in a cylindrical vessel 5 (Fig. 4) rotatably supported on rollers 42, 43 within a shield 48. The frame supporting vessel 5 is tiltable about fulcrum 49 by gearing operated by wheel 52. The vessel 5 may be rotated about its longitudinal axis by a motor 47. Resin may be introduced into the core by any suitable method (e.g. pouring or spraying). The body of the Specification describes relationships between the angle of tilt of the core axis with respect to the horizontal, the angle of taper of the core, and the speed of rotation of the vessel 5 with the evenness of distribution of the resin. A base-plate form may be incorporated at the wide end of both mandrel and mould and may be of such kind as is incorporated into the finished pipe.