Improvements relating to a method of forming a joint between the ends of, or repairing, rods, tubes or the insulation of cable joints

摘要

856,040. Moulding joints between rods, tubes, cable insulation &c. TELEGRAPH CONSTRUCTION & MAINTENANCE CO. Ltd. March 14, 1957 [March 21, 1956], No. 8871/56. Class 87(2). [Also in Groups XXVIII and XXXVI] A method of forming a joint between the ends of or repairing elongated thermoplastic articles, e.g. rods, tubes or the insulation of electrical conductors comprises enclosing the ends of the article in a mould having an injection aperture and one or more spew outlets, injecting into and maintaining through the mould a flow of molten thermoplastic material to heat the ends of the article to fusion temperature, and then cooling to bond the injected material to the ends of the article. The injected material may be of a different colour to that of the article so that on fusion of the article the material issuing from the spew apertures contains traces of this colour whereupon injection may cease. The mould may be transparent to provide visual indication of the joint. Three embodiments are described. Firstly electrical cable ends 1, 2 with insulation 4, 5 are enclosed in a two-part mould S, S2 with injection aperture 7 and spew outlets 8 to 11. Material injected through the aperture 7 flows through the mould and through the outlets 8 to 11 until traces of the insulation 4, 5 are seen whereupon injection ceases. Secondly, Fig. 2 (not shown), a large cable is enclosed in a polythene tube and one end of the tube enclosed in a mould so that injected material bonds to the end portion of the tube and the cable insulation only and the procedure is then repeated at the other end of the tube which forms part of the moulded joint. In this embodiment two injection apertures and no spew outlets are provided, the material being alternately injected into one aperture and discharged through the other. Thirdly, Fig. 3 (not shown), two ends of a tube having recessed between them a sleeve are enclosed in a mould with two injection apertures and four spew outlets. In this embodiment one injection aperture is plugged alternately and the material issues from the spew outlets. The materials of the articles and injected material are preferably the same and may be polythene, polyvinylchloride, polystyrene or polyamide. Ceramic, glass, polytetrafluoroethylene or " Perspex " (Registered Trade Mark) moulds may be used.