| 摘要 |
862,782. Moulding tube couplings. SUDWEST-CHEMIE G.m.b.H. Feb. 16, 1959 [Feb. 17, 1958], No. 5333/59. Class 87(2). [Also in Groups XI and XXVIII] A " welding muff " for use in joining tubes of thermoplastic material, and having an embedded heating element 3 is made by an injection moulding process in which the element 3 is wound on a carrier tube 1 of thermoplastic material, the carrier tube is fitted on to a core of an injection moulding machine, and a sleeve S is moulded around the carrier tube to embed the heating element. Prior to use, the carrier tube 1 is softened by heating and removed from the sleeve. The element 3 may be a bifilar winding located by means of a screw thread in the outer surface of the tube 1. The tube 1 may be of p.v.c. and the sleeve S of polythene. Alternatively the sleeve and tube may be of the same material provided the injection temperature is sufficiently low. |
