GB831817A - Manufacture of electric insulators - Google Patents

Abstract

831,817. Insulators. MANUFACTURES DES GLACES ET PRODUITS CHIMIQUES DE SAINT GOBAIN, CHAUNY & CIREY S.A., DES. March 6, 1957 [March 7, 1956; Feb. 1, 1957 (2)], No. 7385/57. Class 36. In the manufacture of insulators comprising a hollow casing and a supporting core of mineral (glass) fibres bonded by, or embedded in, thermosetting or thermoplastic resin, the core is inserted in the casing while the plastic is unsolidified, so as to prevent penetration by damp. The core may initially be tubular and held by gas pressure against the casing until solidified, the tube then being given a filling of similar material. In Fig. 1, the core a consisting of parallel threads, or uncrossed cords, or woven fibres formed into a core, is inserted while the plastic is soft, into a stack of toughened glass rings b and spacers c having taper-bored steel endsleeves d for carrying steel suspension caps f. Conical wedges g are forced into the core-ends to compress them against the sleeve-bores. In order to minimize friction in inserting the core, the core may be inserted in centring rings e, Fig. 2, of smaller internal diameter than the rings b and the spaces h subsequently filled with a similar plastic to which a filler may be added. In a modification of this, the rings e are originally loose in the bore but coupled together with links which ensure their correct spacing (Fig. 4, not shown). Fig. 5 shows a form in which supplementary sleeves 3 having uniform bores are attached to each sleeve 2, that at the starting end having a flared entry 3<SP>1</SP> and sawcut 5. With this arrangement the core can be cut to accurate length and its ends protected until the sleeves 3 are removed and the wedges inserted. Fig. 9 shows a form in which damage to the core-ends is minimized by a clamping-ring 8 applied over the splayed-out ends before the wedge is inserted. This arrangement may also be applied to a cylindrical core-end, Fig. 11, which also shows the sleeve 2<SP>1</SP> separated from the casing by a steel tube 9 fixed to the sleeve and forming a suspension-means with the latter. In Fig. 12 (not shown), the wedge has a double taper and a second sleeve is provided to co-operate with the other tapered part. In Fig. 13, the sleeve 2 is externally threaded to receive a nut 2b and a ring 2a separates the sleeve 2 from a saw-cut supplementary sleeve 3<SP>1</SP>. The core is cut to length, sleeve 3<SP>1</SP> is removed, and the core-ends secured to ring 2a by a clamping-ring. The nut 2b is then rotated to bear on the ring 2a and tension the core, which is then held firm by insertion of the wedge. After solidification the nut can be turned back and a saw inserted between the sleeve 2 and ring 2a to enable the fittings to be used again.