Abstract: In the manufacture of an electrofusion coupler, a winding of an electrical resistance heating wire is wound directly around a mandrel which comprises two parts providing respective ends of the mandrel. The mandrel supports electrically conducting terminal elements by means of supporting locations on the mandrel parts which form an integral part of the mandrel. The resistance wire wound around the mandrel is connected to the electrically conducting terminal elements. Subsequently a body of thermoplastics is molded around the mandrel to form the electrofusion coupler, and thereafter the mandrel parts are extracted axially from the electrofusion coupler from opposite ends, leaving the winding and terminal elements in place in the electrofusion coupler. In a variant, a thermoplastic preform is manufactured having electrically conducting terminal plates secured thereto, the preform having an electrical resistance heating wire wound therearound and secured to said terminal plates.

Abstract: Thermo-weldable coupling for connecting in particular at least two members made from an identical or compatible plastics material, comprising a body (1) which is of the type constituted at least partly by a thermo-fusible material compatible with the plastics material of these members and which comprises an inner wall (2) or connection surface, directly opposite the outer wall of the members, provided with an electrically conducting element (3). This electrically conducting element (3) is resilient and of non-rectilinear shape. Application to the connections of fluid-carrying pipes made from plastics material.

Abstract: A method is disclosed for the manufacture of an electrofusion coupler, for connecting adjoining lengths of thermoplastics pipes, and which coupler takes the form of a sleeve of thermoplastics material, to receive adjoining ends of adjoining pipes, the sleeve having an electrical resistance heater embedded therein and extended around the sleeve. In the method, a plastics preform is wound with a resistance heating wire, while heating the wire, to melt the surface of the preform, or applying molten plastics to the preform in the vicinity where the wire runs onto the preform, in order to ensure that the heating wire is fully embedded in the preform. A pressing roller may be run over the preform surface before the molten plastics has solidified, in order to smooth over the molten plastics. The preform 10 is subsequently placed in an injection mould and an outer encapsulating jacket is injection moulded around the preform.

Abstract: A method is disclosed for the manufacture of an electrofusion coupler, for connecting adjoining lengths of thermoplastics pipes, and which coupler takes the form of a sleeve of thermoplastics material, to receive adjoining ends of adjoining pipes, the sleeve having an electrical resistance heater embedded therein and extended around the sleeve. In the method, a plastics preform is wound with a resistance heating wire, while heating the wire, to melt the surface of the preform, or applying molten plastics to the preform in the vicinity where the wire runs onto the preform, in order to ensure that the heating wire is fully embedded in the preform. A pressing roller may be run over the preform surface before the molten plastics has solidified, in order to smooth over the molten plastics. The preform 10 is subsequently placed in an injection mould and an outer encapsulating jacket is injection moulded around the preform.

Abstract: An electrofusion coupler sleeve for use in connecting together two plastics pipes by fitting the ends into opposite ends of the sleeve and passing an electric current through a resistance heater embedded in the sleeve adjacent its inner surface to fuse together the pipes and the sleeve, incorporates visual indicating means for indicating if the electrical energy supplied has been adequate for proper fusing. The indicating means takes the form of a blind bore extending into the sleeve from the exterior towards the interior. When, in use, the heater is energized, if the electrical energy supplied has been adequate for proper fusing, the softened flowable plastics material is forced, by the pressure produced by heating and fusing, to rise within the blind bore and project from the outer surface of the sleeve.