EP0170471A2

EP0170471A2 - Cable jointing

Info

Publication number: EP0170471A2
Application number: EP85305126A
Authority: EP
Inventors: Michael John Sleeman; Robin Louvel
Original assignee: Bowthorpe Hellerman Ltd
Current assignee: Bowthorpe Hellerman Ltd
Priority date: 1984-07-20
Filing date: 1985-07-18
Publication date: 1986-02-05
Also published as: GB8418619D0; GB2162000A; GB8518165D0; GB2162000B; EP0170471A3

Abstract

57 A cable jointing kit comprises a length of tubing 10 to enclose the joint, together with a pair of end members 12 each with a cylindrical portion 16 to fit into the tubing and a heat-recoverable tubular portion 14 to be recovered about the cable: the end member cylindrical portion is formed with a series of grooves 20, interconnected at staggered points 21, into which a sealing substance is injected (through the tubing wall) once the end members have been fitted into the tubing. The injected sealing substance flows freely around these grooves to ensure that at least one (and usually several) complete annular sealing rings are formed between each end member and the tubing.

Description

This invention relates to cable jointing, particularly but not solely for telecommunications cables.
One form of cable jointing kit which has been proposed comprises a length of tubing to enclose the cables over the jointing zones, and two heat-recoverable end members for fitting to the opposite ends of the tubing and embracing the respective cables upon recovery. The end members have cylindrical portions which fit closely within the end of the tubing and, in accordance with one proposal, a sealing compound (e.g. an adhesive) is injected into such clearance as exists between the inner surface of the tubing and the outer surface of the inserted end member. However, it is difficult to ensure, or to confirm, that the sealing compound will flow so as to form a complete seal around the full circumference of the tubing.
In accordance with this invention, there is provided a cable jointing kit comprising a length of tubing and two heat-recoverable end members having cylindrical portions for fitting into the opposite ends of the tubing, at least one annular groove being formed in the interfitting surfaces of the tubing and/or each end member cylindrical portion, which grooves serve to receive a substance to form annular seals between the two end members of the tubing.
In an embodiment to be described herein, the outer surface of the cylindrical portion of each end member is formed with a series of interconnected annular grooves. When a sealing compound is injected through the tubing wall which overlies these grooves (after assembly of the joint), the grooves guide the injected compound and ensure that it will form at least one complete annular sealing ring, and usually several such rings. Preferably the end members are a locking fit into the opposite ends of the length of tubing, by virtue of annular ribs on the cylindrical portions of the end members engagingwithin annular grooves in the inner surface of the tubing adjacent its ends.
Also in accordance with this invention, there is provided a method of jointing cables, in which the cables to be joined are threaded through respective heat-recoverable end members and one of the cables is threaded through a length of tubing, then the cables are joined, the tubing is slid along the cables and positioned around the joined cable ends, the end members are slid along the cables to fit cylindrical portions of the end members into the opposite ends of the tubing, tubular portions of the end members are heat-recovered about the cables and a sealing substance is injected into annular grooves which are formed in the interfitting surfaces of the tubing and/or end member cylindrical portions, so as to form an annular seal between each end member and the tubing.
An embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawings, the single Figure of which is a side view of one end member of a cable joint in accordance with the invention, showing also in longitudinal section the corresponding end of a length of tubing for the joint.
Referring to the drawing, the embodiment of cable jointing kit which is illustrated comprises a length of tubing 10 (which may be formed of metal or plastics material or a combination of metal and plastics), and two moulded end members, one such end member 12 being shown. The end member provides an end closure wall having at least one cable sleeve 14 projecting in one djrection (to project outwardly from the joint), and a short cylindrical or tubular portion 16 projecting in the opposite direction, for fitting into the end of the tubing 10. A conical tapering entry surface 11 is formed on the tubing end to mate with a conical surface 17 on the end member: adjacent the tapering surface 11 the tubing is formed with an annular groove 13 which is to receive an annular ridge 18 on the end member. The end of the tubular portion 16 of the end member is formed with another annular ridge 19, to be received within an annular groove 15 in the tubing, the extreme end surface of the portion 16 being formed as a conical tapering surface which provides the forward side of the ridge 19,
Between the ridges 18 and 19 of the end member, its outer surface is formed with a series of annular grooves 20 which are interconnected at points 21 which are staggered or offset from each other around the circumference.
In use, (after the closed outer ends 14a of the sleeves 14 are cut-off) the cables to be joined are threaded through the respective end members and one of the cables is threaded through the tubingi then the cable ends are joined, the tubing slid along the cables into position over the joined cable ends, and the end members slid along the cables to fit into the opposite ends of the tubing so that the cable joint is enclosed. The ridges 18 and 19 of each end member snap-fit into the corresponding grooves 13, 15 of the tubing 10 to provide a mechanical lock. The sleeves are then heat-recovered so as to shrink down to embrace and seal around the cables. The clearance between the tubing inner surface and the tubular portion 16 of each end member now comprises the series of interconnected annular grooves 20. A sealing compound is now injected into this clearance space through one or more apertures provided through the tubing wall. The compound may comprise a curable liquid resin or polymer and preferably an adhesive: the grooves 20 guide the flow of injected compound and ensure that several complete annular rings of such compound are formed between the end member and the tubing, so as to ensure the required seal.
The jointing kit will comprise, in addition to the length of tubing and two end members, a quantity of the sealing compound and a device for injecting this into the grooves 20.

Claims

1. A cable jointing kit comprising a length of tubing (10) and two heat-recoverable end members (12) having cylindrical portions (16) for fitting into the opposite ends of the tubing, characterised by at least one annular groove (20) being formed in the interfitting surfaces of the tubing and/or each end member cylindrical portion, which grooves serve to receive a substance to form an annular seal between the two end members and the tubing.

2. A cable jointing kit as claimed in Claim 1, characterised in that the outer surface of the cylindrical portion of each end member is formed with a series of interconnected annular grooves (20).

3. A cable jointing kit as claimed in Claim 2, characterised in that the adjacent interconnection points (21) are offset from each other around the circumference of the end member cylindrical portion.

4. A cable jointing kit as claimed in any preceding claim, characterised in that the end members are a locking fit into the opposite ends of the length of tubing.

5. A cable jointing kit as claimed in Claim 4, charac- rised in that the cylindrical portions (16) of the end members are formed with annular ribs (18,19) engageable within annular grooves (13,15) formed in the inner surface of the tubing adjacent its ends.

6. A cable jointing kit as claimed in Claim 5, characterised in that the cylindrical portion (16) of each end member is provided with two said annular ribs (18,19) and each end of the tubing is provided with two said grooves (13,15) for receiving those ribs, and a series of interconnected annular grooves (20) for receiving the sealing substance are formed in the end member cylindrical portion between its said ribs.

7. A cable jointing kit as claimed in Claim 5 or 6, characterised in that the leading rib (19) of each end member is formed with a tapering surface on its forward side, for co-operating with a tapering entry surface (11) formed on each end of the tubing.

8. A cable jointing kit as claimed in any preceding claim, further comprising a quantity of sealing substance and means for injecting said substance through apertures provided in the tubing wall and into the grooves which are formed in the interfitting surfaces of the tubing and/or end member cylindrical portions.

9. A method of jointing cables, in which the cables to be joined ere threaded through respective heat-recoverable end members (12) and one of the cables is threaded through a length of tubing (10) then the cables are joined, the tubing is slid along the cables and positioned around the joined cable ends, the end members are slid along the cables to fit cylindrical portions (16) of the end members into the opposite end of the tubing, and tubular portions (14) of the end members are heat-recovered about the cables, characterised in that a sealing substance is injected into annular grooves (20) which are formed in the interfitting surfaces of the tubing and/or end member cylindrical portions, so as to form an annular seal between each end member and the tubing.