| 摘要 |
808,725. Moulding pipe &c. couplings. ST. GEORGE., R. O.,and ST. GEORGE LIGHT ENGINEERING CO. (BERKSHIRE) Ltd. May, 17, 1955 [May 26, 1954], No. 15610/54. Class 87(2). [Also in Groups XI and XXVIII] A connecting member of thermoplastic material for making a welded lap joint has embedded in it heating means to effect local softening of the material in that region of the member where the joint is to be made. The heating means may comprise an electrical resistance wire, a metal ring subjected to high frequency induction heating, or a combustible material consisting of cordite accommodated in a hollow ring or in a coiled tube or of a mixture of powdered metal, alloy or silicide and an oxidizing agent, the mixture being selfsupporting or placed in a temporary, fusible container. Fig. 2 shows a polythene T-piece 1 in each arm of which circular wires 2 are embedded so as to lie flush with the inside wall, battery leads 4 being connected to lugs on the ends of each wire. An example of wire dimensions, current value and heating time is given. The heating element may, alternatively, be in the form of wire mesh or a loop of wire forming a double start coil. Fig. 4 shows how the wires 2 are located on the mould core 5 prior to the injection of the plastic, the leads 4 fitting in drillings 6 in the core body. |
