Patent GB-1038883-A (GB)
Title: Improvements in or relating to the manufacture of reinforced plastics tubes
IPC: B29C70/16
Filed: 1963-10-09
Abstract: 1,038,883. Pipe-making apparatus. C. GADANI, and U. GADANI, [trading as C.I.M.E.M. DI F. ILI GADANI]. Oct. 9, 1963 [Oct. 18, 1962], No. 39862/63. Heading F2P. Reinforced plastics tubes are made by extruding a plastics core, having a coefficient of thermal expansion greater than that of the reinforced resin to be used, from an extrusion press, winding a reinforcing glass fibre ribbon on to the core, depositing a layer of resin on the glass fibre windings to impregnate the same, subjecting the tube to thermosetting by heating to cause the core to dilate and compress the resin-impregnated windings and cooling the whole so that the core contracts to a greater extent than the tube and can be detached therefrom. A core 4 (Fig. 1a not shown), e.g. of polyvinyl chloride, cellulose acetate or polystyrene is continuously extruded from a worm extruder 1 preferably through a rotary head 2, passes through a cooling chamber 3, a support 5 and a caterpillar conveyer 7 or a helicoidal roller conveyer mounted on a rotating support 6, through further supports 5 (Fig. 1b and through a winding device 8. Said device 8 comprises a rotating collar 33 carrying arms 34, 35 arranged at 45 degrees to the direction of travel of the core, said arms carrying pivots on which are rotatably mounted drums 36, 37 holding a continuous ribbon 9 of glass fibre felt. Two arms 44, 45 extend from the arms 34, 35 and bear guiding rollers 42, 43. The collar 33 is rotated in the same direction as the core but at a lower speed by speed varying device 29. The core is thus wound with spirals of predetermined angle. The wound core then passes through two more supports 5 and through a covering device 38 comprising an internal cylinder 12 carrying a concertina'd fabric sheath 13 and surrounded by a protecting cylinder 14, the whole being connected to a rotating collar 11. The sheath 13 is applied to the tube to ensure that the glass fibres stay in position and so that the tube wall is completely formed and has a high degree of finish. The wound core then passes to an impregnation device which, as described comprises two feed tubes 17, 18 having resin spraying nozzles and situated above the machine, and a pressure roller 16 adjacent the wound core. Resin in the form of a catalyst and a polymerization-accelerating agent falls separately from each tube 17, 18 between the roller and wound core and evenly impregnates the reinforcement. The tube then passes through a calibrating ring 20 mounted on a rotary ring 19 and passes through a furnace (Fig. 1c, not shown) wherein the diameter of the core is increased to exert pressure on the wound layers and reaches a conveying frame 25 (Fig. 1d, not shown) wherein a distancer 26 and a circular saw 24 serve to cut the tube into predetermined lengths. As the tube cools the core contracts to a greater extent than that of the reinforced resin and can be extracted. The core can be recovered and recycled. The resins used for manufacture of the reinforced tube may be polyesters, epoxy resins, silicon resins, phenolic resins, acrylic resins.