| 摘要 |
1345822 Extruded tubes J-J WALTER 8 Dec 1971 [11 Dec 1970 15 July 1971 (2)] 57045/71 Heading B5A [Also in Division F2] In a method for the continuous production of banded leak-tight tubing an inner sheath 1 of leak-tight plastic material receives a jacket 2 comprising one or more windings of reinforcement material which is impregnated with a hardenable binder at station F and covered with an outer plastic sheath 3, thereby applying the binder intimately and uniformly against the reinforcement 2, the binder then being polymerized. Apparatus for carrying out the method, as shown, comprises a first extruder A which produces the inner plastic sheath e.g. of polyethylene over a mandrel (12) (Fig. 4, not shown). A cable 24 is attached at one end to the mandrel (12) and at the other end to a plug 25 at a stage where the tubing is completed and the intervening section of tubing is pressurized to support the tubing shape. Drive wheels B advance the sheath 1 to winding stations C, D, E where the reinforcement material 2c, 2d, 2e, e.g. threads, braid or ribbons with a glass fibre base, is wound helically over the sheath 1. At station F the tube passes through a doublewalled impregnating tank (53) (Fig. 8, not shown) over which a second extruder produces the outer plastic sheath 3. The impregnating binder may be a polyester or epoxy resin which may be catalysed and accelerated. Whilst the outer sheath 3 is hot the tube is drawn through driven wheels G which elongate the outer sheath to contract it over the reinforcement layer 2. The tubing is then supported over a hot air nozzle 72, passed through a compression collar 76 and over a cold-air nozzle 74 at a station I which effects further contraction of the outer sheath 3 over the impregnated reinforcement 2 to uniformly spread the binder. Traction belts 70, 71 at station H advance the tube through collars 77 at station J which improve the binder distribution before it is polymerized at a station K. The station K comprises an elongate enclosure having three adjacent compartments (86, 87, 88) (Fig. 11, not shown) part-elliptical in transverse section a source of U.V. light being disposed at a focus of each compartment. The tubing traverses the enclosure through a transparent tube (85) which is fan-cooled to remove heat generated by the polymerization of the binder. In alternative arrangements, the outer sheath is contracted by passing the tube through a reservoir containing liquid at a controlled temperature and pressure (Fig. 12, not shown) and the extruder at stations B or F may include a mandrel having a low-friction surface incorporating a continuous ball race (Figs. 13, 14, not shown). Other materials for the inner and outer sheaths are high or low density polyethylene, acrylonitrile butadiene styrene, P.V.C., polystyrene or polypropylene. |
