Patent Publication Number: US-4545645-A

Title: Connection joining the ends of two under-water optical fiber cables and a method of manufacturing same

Description:
The present invention relates to a connection joining the ends of two under-water optical fiber cables, each cable comprising an optical core constituted by a carrier wire covered by a helically grooved plastics rod having optical fibers received in its the grooves; a protective tape surrounding the optical core; a steel wire arch assembly; and an insulating sheath made of a thermoplastic substance. 
     It also relates to a method of manufacturing such a connection. 
     BACKGROUND OF THE INVENTION 
     The Applicant&#39;s French Patent application No. 81 24 514 describes various connections for joining two cable ends to repair a damaged cable. These connections are formed by connection boxes which take up an appreciable volume and with an outside diameter of about 150 mm and a length of about 1.30 m. 
     Further, said connection box is completely rigid. This makes it less easy for the box to pass a davit when winding said cable. These boxes can be used only for such repairs as may be necessary after complete manufacture of the cable. 
     Preferred embodiments of the present invention remedy such drawbacks, by providing a connection and a method of connecting which allows a cable to be repaired during its various manufacturing steps. Repairs are made after insulation with a first thermoplastic insulating sheath. 
     Further, such preferred embodiments allow a connection to be made which maintains the geometric and dimensional appearance of the cable without increasing its rigidity, thus making it easier for the repaired cable to pass on a davit. 
     SUMMARY OF THE INVENTION 
     The present invention provides a connection joining the ends of two under-water optical fiber cables, each cable comprising an optical core constituted by a carrier wire covered by a helically grooved plastics rod having optical fibers received in its grooves; a protective tape surrounding the optical core; a steel wire arch assembly; and an insulating sheath made of a thermoplastic substance; wherein the connection includes: 
     a. two plastics rods glued at the ends of each cable to the carrier wire around which the ends of optical fibers are wound, said rods being welded individually to each other and being protected by two tapes; 
     b. two split plastics tubes covering the optical fibers which are surrounded with tape at the ends of each cable; 
     c. a sheath around which the ends of each arch assembly are reconstituted; and 
     d. a sleeve glued and/or crimped onto the ends of each arch assembly. 
     Advantageously, the space left free between the ends of each arch assembly, the sheath and the sleeve as well as the ends of the sleeve are filled with glue. 
     In the method of manufacturing a connection according to the invention: 
     a. the insulating sheath and the drawn down copper tube are removed from each cable end along a length very much greater than that required for said connection, the arch assembly is untwisted and the grooved rod is removed from each cable end along a length very much greater than that required for said connection, leaving the optical fibers and the carrier wire stripped; 
     b. the sheath and the sleeve are engaged on a cable end; 
     c. the two smooth rods are placed on the cable ends; 
     d. the optical fibers are welded together one-to-one and they are wound round the smooth rods on either side of their welds; 
     e. the resilient protective tapes are set in position on the fibers and then the split tubes are set in position on the tapes; 
     f. the sheath is brought back to the center of the connection, covering each end of the split tube, then each arch assembly is reformed over the sheath, and 
     g. the sleeve is brought back to the center of the connection on the end of each arch assembly. 
     Preferably, the space left free between the ends of each arch assembly, the sheath and the sleeve as well as the ends of the sleeve is filled with glue. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Both a connection in accordance with the invention for joining together two cable ends each having a return conductor and a protective thermoplastic sheath which surrounds said return conductor and a method of manufacturing said connection are described by way of example with reference to the accompanying drawings, in which: 
     FIGS. 1A and 1B are perspective views of two cable ends to be connected, showing their various components; 
     FIG. 2 is a partially cutaway elevation of a cable connection showing various reconstituted layers; and 
     FIG. 3 illustrates in detail the connection shown in FIG. 2. 
    
    
     MORE DETAILED DESCRIPTION 
     In FIGS. 1A and 1B, the end of each cable has an optical core 1, 1&#39; constituted by a carrier wire 2, 2&#39; covered by a helically grooved rod 3, 3&#39; made of a plastics material in which optical fibers 4, 4&#39; are received. Said optical core is covered by a protective tape 5, 5&#39; then by an arch assembly 6, 6&#39; made of steel wires and consisting of a first arch 6, 6&#39;A and of a second arch 6B, 6&#39;B. The ends of the wires are held clamped against the optical core by two regions of whipping or binding 7A, 7&#39;A and 7B, 7&#39;B to prevent said arch assembly from becoming untwisted and coming apart before the ends are connected together. A copper tube 8, 8&#39; is drawn on the arch assembly and is covered by an insulating sheath 9, 9&#39;. In the above embodiment, the cable has a return conductor 10, 10&#39; covered with a protective sheath 11, 11&#39;. 
     In FIG. 2, which shows the end of one of the cables, the arch assembly 6 is enclosed in a sleeve 12. The copper tube 8 drawn down on the arch is reconstituted by a copper tape 13 longitudinally welded at 14. 
     A thermoplastic moulding 15 connects the insulating sheath 9 of said cable end and the insulating sheath of the end of the other cable, not shown. In the above form of embodiment which includes a return conductor, a metal braiding 16 connects the return conductor 10 of said cable end and the conductor of the end of the other cable, not shown, and a heat-shrinkable sleeve 17 connects the protective sheath 11 of said cable end and the protective sheath of the end of the other cable, not shown. 
     FIG. 3 shows the inside of the sleeve 12 and the various reconstituted layers. In said figure, the optical fibres 4, 4&#39; are connected by welding and protected by individual sleeves 21. 
     The fibers 4 are wound round smooth rod 22 which is itself glued to the carrier wire 2 and they are protected by a tape 23 equivalent to the tape 5 of FIG. 1A. A split tube 24 covers the tape 23. 
     The same applies to the fibers 4&#39; wound round a smooth rod 22&#39; which is itself glued to the carrier wire 2&#39; and protected by a tape 23&#39; equivalent to the tape 23. A split tube 24&#39; covers the tape 23&#39;. 
     Both ends of each split tube 24, 24&#39; are covered by sheaths 19. The ends of the arch assemblies are wound onto said sheath to reconstitute a cable. The sleeve 12 covers the ends of the arch assemblies and is filled with glue 20. Two longitudinally welded copper tapes 13, 13&#39; on each side of the sleeve reconstitute the copper tubes 8, 8&#39; drawn down over each cable end. A reconstitution moulding 15 made of a thermoplastic substance ensures the continuity of the insulating sheaths 9, 9&#39; of each cable end. In said form of embodiment a longitudinally welded conductive metal tape 16 provides continuity of the return conductor 10, 10&#39; and a heat shrinkable sleeve 17 provides continuity of the protective sheath 11, 11&#39; at each cable end. 
     The connection described hereinabove is manufactured as follows: 
     The protective sheath 11, the return conductor 10, the insulating sheath 9 and the drawn down copper tube 8 are removed from each cable end along a length very much greater than that required for said connection. 
     The arch assembly 6 is untwisted and the rod 3 is removed from each cable end along a length greater than that required for said connection, leaving the optical fibers 4 and the carrier wire 2 stripped. 
     The sheath 19 and the sleeve 12 are engaged on a cable end. 
     The two smooth rods 22, 22&#39; are placed on the two carrier wires 2, 2&#39;. 
     The optical fibers are welded together one-to-one and each weld is protected by an individual sleeve 21 and the fibers are wound round each smooth strength member on either side of their welds 
     The resilient tapes 23, 23&#39; are set in position on the fibers then the split tubes are set in position on the tapes. 
     The sheath 19 is brought back to the centre of the connection, covering each end of the split tube, then each arch assembly is reformed over the sheath. 
     The sleeve 12 is brought back to the centre of the connection on the end of each arch assembly. 
     The space left free between the ends of each arch assembly, the sheath and the sleeve as well as the ends of the sleeve is filled with glue 20. 
     The drawn down copper tube 8, 8&#39; is reconstituted up to the level of the sleeve 12 by placing two copper tapes 13, 13&#39; on either side thereof, said copper tapes being welded longitudinally by two welds 14, 14&#39;. 
     The continuity of the insulating sheath 9, 9&#39; of each cable end is provided by a moulding 15 made of a thermoplastics substance along the whole length of the connection. 
     In said form of embodiment, the continuity of the return conductor on each cable end is provided by a longitudinally welded conductive metal tape 16 and the continuity of the protective sheath at each cable end is provided by a heat shrinkable sleeve 17. 
     Of course, without going beyond the scope of the invention, metal braid could be used to reconstitute the return conductors. 
     Also the invention can be applied to cables which do not have a return conductor, in which case the number of steps is reduced.