| 摘要 |
1373761 Winding extruded material; seaming MANNESMANN AG 22 Oct 1971 [26 Oct 1970] 49250/71 Headings B5A and B5K [Also in Division F2] In a method of making a sleeve of thermoplastic material for use in coupling thermoplastic tubes, a heating wire coil 16, to be incorporated in the sleeve, is supported on a rotating mandrel 2 and a band 17 of thermoplastic material is fed from a long slit of an extruder 7 and wound about the heating coil to the desired thickness. The band 17 is stretched longitudinally by a roller 9. The ends of thermoplastic pipes to be coupled by the sleeve are inserted into the sleeve and an electric current is applied to the coil 16 to soften the material of the sleeve and pipe ends to effect welded joints. As shown, the mandrel 2 used in the method which is heated to about 150‹ C. carries steel bands 3 having bent ends 4 engaged in a slot 1. The ends of the wire coil are attached to projections 5 on the steel bands. A line of mandrels may be used, each successively moving past the extruder head 7. Rod-like reinforcing members, e.g. fibreglass-reinforced epoxy resin, may be wound into the sleeve layers. After application of the extruded material the ends of the sleeves are trimmed and the sleeves are removed from the mandrels. The steel bands are removed and holes are formed in the sleeve at the coil ends, which may carry connector eyelets, to facilitate connection of a current source to the coil. Two layers of different materials may be applied to the coil either by successive windings or from a single extruder slot fed from two extruders (14, 15) (Fig. 4, not shown). The inner layer adjacent the coil may be a copolymer of polyethylene and the outer layer of a high molecular weight plastics such as polyethylene of molecular weight in excess of 90,000. Preferably, the winding band for multilayer application is as wide as the length of the mandrel for convolute winding. In another arrangement, the mandrel is made of two interfitting parts (12) (Fig. 5, not shown) on either side of an annular bearing ring (11) which is incorporated in the sleeve to act as a stop for inserted pipes. |
