GB952738A - Improvements relating to flexible couplings for pipes - Google Patents

Abstract

952,738. Moulding flexible pipe couplings. DUNLOP RUBBER CO. Ltd. July 19, 1960 [Aug. 29, 1959], No. 29569/59. Heading B5A. A flexible pipe coupling is made by forming a length of mouldable tube 4 with at least two radially inextensible portions, each of which forms a supported portion of the tube, the portions extending axially and circumferentially of the tube and lying spaced apart from each other by a radially extensible portion of the tube and also from the ends of the tube, expanding the radially extensible portion of the tube between the supported portions and moulding the ends of the tube into annular flanges 8, the expansion of the tube between the supported portions being effected at least in part by applying a differential fluid pressure between the interior and exterior of the tube. The tube 4 is formed from mouldable material which remains flexible in its final state such as natural or synthetic rubber or a thermoplastic having a reinforcement 5 of cord or fabric which may be textile or metallic. It is further strengthened at the supports by the incorporation of encircling non-extensible bands 6. In the embodiment described, the apparatus used is a three-part mould (Fig. 4) comprising an axially split segmental hollow cylindrical member 20 and two end plates 30, 31. One of the end plates, 31, is secured to a mould core 32, the two components forming a joint mould member, while the other end plate, 30, has an inlet 33 connecting a fluid pressure supply line to perforations 34 in the core 32. Member 20 is provided with one or more depressions 21 to form the corrugations of the coupling and with recesses 22 to form the flanges 8. A tube 4, of unvulcanised rubber, for example, is placed around the core 32 and the mould then assembled, the end plates 30, 31 forcing the end portions of the tube 4 which have been turned outwards by swaging into the recesses 22 and axially compressing the tube between the flanges to force the unsupported regions into the depressions 21. The mould is then heated and subjected to internal steam or air pressure. In an alternative apparatus, the fluid pressure is applied by an inflatable liner. A tube with preformed expanded portions cut from a length of corrugated tubing may be used in place of a cylindrical tube and the flanges 8 formed as above, the tubing being cut at two peaks with at least one peak in between them. Annular rings of unvulcanised rubber may be positioned between the outwardly directed end portions of the tube 4 and the end plates 30, 31 so that during moulding they become incorporated into the flanges 8.