GB587580A - Jointing thermoplastic-insulated cables - Google Patents

Abstract

587,580. Cable joints. TELEGRAPH CONSTRUCTION & MAINTENANCE CO., Ltd., DEAN, J. N., WILSON, H. F., and COOK, E. I. June 1, 1944, No. 10565. [Class 38 (i)] Two lengths of cable insulated with the same or different thermoplastic dialectric materials which are not wholly composed of polyisobutylene are joined together by a jointing medium consisting of or comprising polyisobutylene. Several examples are shown, such as that in Fig. 1, in which the insulation of the cables is respectively deresinated gutta percha G and polyethylene P. The insulation is pared down to a cone shape, or is heated and pulled back, and a layer of polyethylene tape 1 carrying an adhesive layer or layers of polyisobutylene is wound on the reduced portion and for about an inch on either side of the outer ends of the cones. Other examples describe methods for jointing different combinations of insulation, e.g., polyethylene to polyethylene, polyethylene to deresinated balata, &c. In another example, Fig. 5, in which gutta percha is joined to polyethylene, the gutta percha G is covered with a gutta percha-polyisobutylene tape 4 and the polyethylene P with a polyethylene-polyisobutylene tape 1. The whole is then covered with polyisobutylene tape 2, a layer of polyethylene-polyisobutylene tape 1 and an outer layer of polyethylene tape 31. Where commercial gutta percha or balata is to be joined to polyethylene, an intermediate section of deresinated gutta percha or balata respectively is placed between the two sets of insulation, Fig. 6 (not shown). The applied materials may be welded together by heating the joints by a spirit lamp or by covering the joint with a metal tube which is heated to between 130‹C. to 160‹C, and which, after cooling, is stripped off, Fig. 8 (not shown). In Fig. 9 (not shown), a number of joints are covered with hot lead which is stripped off when cool. In another method, Figs. 7, 7A, 7B (not shown), the joint is covered with proofed tape and is placed in a heated mould where a covering of polyethylene is applied. The ends of the mould are cooled gently, and the polyethylene and the proofing are removed.