Method of making a thermoplastic joint

Abstract

Abstract 942,592. Seaming non-metallic sheet material. TELEPHONE CABLES Ltd. May 11, 1962 [May 24, 1961], No. 18784/61. Heading B5K. [Also in Division H2] A joint is formed between facing surfaces of two thermoplastic members 1, 3 by interposing an electrical heater 5 of coherent open-work form between the two surfaces, fusing the material at the interface between the surfaces by the heater 5 and then withdrawing the heater with a motion which is agitated during at least an early part of the withdrawal. To join two lengths of polythene-sheathed cable, the sheath is cut back to expose the conductors 2 which are joined and a polythene sleeve 4 previously applied over the cable is slipped over the joint. A polythene collar 3 may be provided for each end of the sleeve 4. To join the collar 3 to the sheath 1 the heater 5 is interposed therebetween and a tape 6 is applied under tension to the outside of the collar. The heater 5, Fig. 2, comprises a stainless steel mesh strip cut on the bias and has an unstretched diameter slightly less than that of the sheath 1. A carrier 9 carries the heater 5 by strips or pins 8 and connecting leads 7 secured thereto. The tape 6 may comprise a length of silicon elastomer or neoprene tape having a bias cut stainless steel heater 10 secured thereto and being of such a length that its ends overlap. The inner end of the tape 6 is preferably tapered. The collar 3 is first softened at a temperature between 60 ‹ and 85‹ C. by the heater 10 and the heater 5 heats the material at the interface to a temperature between 150‹ and 180‹ C. to form the joint. The heater 5 is withdrawn by combining both axial and to-and-fro angular movement along the cable axis, the tape 6 still applying pressure. The heater 5 is cut from the cable and the carrier 9 and the tape 6 are removed. Similarly, the sleeve 4 is joined to the collar 3 at A. The heater 10 may be dispensed with and preliminary softening may be obtained by initially running the heater 5 at a low current. In a modification, Fig. 5, the tape 6 is wound without tension and a closed, rectangular crosssection pneumatic tube 12 is applied around the tape 6 and is constrained against movement by U-section members 13 articulated together. Pneumatic pressure is admitted through a port 14 and the tube ends overlap at 12<SP>1</SP>.

Inventors

• 👤 Gandy Robert William

Bibliographic Details