GB2241386A - Cable joint closure - Google Patents

Abstract

A cable joint closure 10 includes a inner cap 14 which carries preformed heat meltable sealant 15 with a number of ribs 36 between which cables 11a - 11d are positioned. On positioning the inner cap 14 within the heat shrinkable band 27 and on applying heat the band 27 shrinks to seal on the portion 25a of base 25 and the sealant melts around the cables and on cooling seals between the inner cap 14 and the band 27. The ribs 36 can be T-shaped to provide more-defined cable positions and the cables can be placed in protective tubes 16, inner cap 14 can be heat expandible. The base 25 is closed at one end, or open at both ends to received two closures 10. Band 27 is coated with a sealant. <IMAGE>

Description

Cable Joint Closure The invention relates to a cable joint closure for telecommunications or other cables.

When cables are joined it is necessary to provide a closure which prevents ingress of water, mud or other undesirable products which may be in the environment where the joint has been made.

According to the invention there is provided a cable closure comprising: at least one outer heat shrinkable closure member; at least one inner closure member, and a heat meltable sealant therebetween preformed to include a plurality of apertures each for receiving a cable, whereby cables when positioned therein are sealed between the inner and outer closure members after heating.

Further according to the invention there is provided a cable closure kit comprising an outer closure member, an inner closure member for insertion within the outer member and a heat meltable sealant preformed to include a plurality of apertures each for receiving a cable.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows one embodiment of the invention prior to a heating step; Figure 2 shows the Figure 1 closure after the heating step, Figure 3 shows an end view of the Figure 2 closure, Figure 4 shows alternative sealant arrangements carried on the inner cap; and Figure 5 shows an alternative embodiment to that of Figure 1.

Figure 1 shows a joint closure configuration 10 prior to assembly and heating to effect the desired closure. The cables I Ia - 1 lid are arranged around the periphery of a cap 14. The cap 14 is generally tubular with a domed end portion 14a. A ring of heat meltable sealant 15 is provided on the cap 14, between the cables. Extending from the ring of sealant 15 are a number of ribs 36 which define an aperture between which the cables are located. These apertures correspond to the number of cables required to be accommodated. These ribs are also of sealant material to assist in sealing during the heating step. Different rib configurations can be employed for different numbers of cables. These can be available on different sealant rings and slipped onto the closure 14 prior to assembly.The cap may be formed of plastics material which does not change size or shape during heating (e.g. compression moulded thermosetting plastic). Alternatively it may be formed of heat expandible material. In the area of the sealant, a cable wrap 16 is provided which may comprise a strip of metallic mesh, gauze or other heat absorbing/reflecting material to prevent damage to the cables during the heating step.

The various cables are interconnected as indicated by joint connectors 22.

The configuration thus far described is now ready to be placed in a base portion 25 which is typically of a compression moulded thermosetting plastic. The base as shown in this example is configured as a tubular portion 25a and a domed portion 25b. A clamp 30 (see Figure 3) would normally hold the two portions in intimate contact to provide a seal therebetween in combination with an O-ring seal.

The configuration in the base portion is sealed thereto by means of a heat shrinkable band 27, which overlies portion 25a when assembled.

The heat shrinkable band 27 is typically manufactured from a cross linked polyolifin which has been originally artificially expanded while hot during manufacture and held in that state till it is cooled. The band will then be internally coated with sealant (not shown).

As mentioned above, the cap 24 may be, in one configuration, of heat expandible material. Such a cap 14 will also typically be manufactured from a cross linked polyolifin. However during manufacture, it is converted from its original larger dimensions by forming it into smaller dimensions while hot and is then allowed to cool to retain this reduced shape.

In this case, during the heating step after assembly of the Figure 1 configuration, a gas torch or other suitable heater is applied and this will cause the expandable cap 14 to expand to be closer to the cable positions (see Figure 3) and the band 27 will shrink to conform to the shape of the end portion 25a and the cables (see Figure 2). At the same time the sealant on the band 27, the extension ribs 36 and the band 15 will melt and seal around the cables and between the band 27 and the cap 14 to provide a permanent and reliable seal on cooling (see Figure 3). The end portion 25a of the base 25 will not itself change its shape or character during this step.

If desired the heating can be carried out in two steps, the first step dealing with that portion of the band 27 adjacent the end portion 25a so that this shrinks down to provide a seal therewith whilst leaving the remaining band portion at its earlier diameter to receive the cables and heat expandable cap after this step. Thereafter a second heating step allows the remainder of the band 27 to shrink down and the cap 14 to expand to form the seal.

This second heating step preferably is carried out by heating the band 27 till it shrinks to loosely gather the cables and thereafter applying heat to the inside of the cap 14 and the outside of the band 27 simultaneously (or rapidly between the two) until the cap is fully expanded and the band is full shrunk and the cables trapped and sealed therebetween.

In the case of the inner cap 14 being non-expandible, the band 27 will be sufficiently shrinkable to cause an effective seal in combination with the sealant.

The clamp 30 of Figure 2 includes a hinged portion 32 and a screw portion 33 to allow reopening and removal of the base portion 25b should a change in the connections therein be required or for repair purposes.

As described above, the cap 14 carries a sealant ring with preformed ribs and in the Figure 1 arrangement, four ribs are provided for the four cables. This assists in positioning and sealing the cables. Other configurations could be preformed on the sealant ring 15 as desired to suit cable numbers and placed on the expandable cap 14 prior to assembly.

Figure 4 shows two further configurations. The first has five ribs 36 to accommodate five cables. The second has six ribs 38 for six cables.

Ribs 38 are shown extending towards each other to aid the sealing of the cables when placed therebetween. Thus, the apertures shown in Figure 4 can be channel-like in form, the upper end being more closed by ribs 38 than by ribs 36.

An alternative embodiment is shown in Figure 5. The sealing mechanism comprised of the inner cap 14, the ribbed sealant ring 15, and the cable wrap 16 together with the heat shrinkable band 27 is provided at each end of an elongate tubular central base 40. The base can be formed of a compression moulded thermosetting plastic material. This arrangement allows cable interconnections in different configurations to be achieved as represented by the inclusion of further cables 12a-12d.

The assembly and heating steps can be identical to those described in relation to Figure 1, although they will be required twice to deal with both ends in this case.

If access is required to connections in this closure at some later date, sufficient cable slack would be provided inside the base 40 and the band 27 could be cut around its periphery and on warming the end could be slid off. Re-closure could be achieved using a further band or a piece of wrap-round heat shrink material.

The embodiments of the closure described would normally be supplied in kit form with instructions for use as necessary.

Claims (28)

1. A cable closure comprising: at least one outer heat shrinkable closure member; at least one inner closure member; and a heat meltable sealant therebetween preformed to include a plurality of apertures each for receiving a cable, whereby cables when positioned therein are sealed between the inner and outer closure members after heating.

2. A closure as claimed in claim 1 wherein the heat meltable sealant is preformed to include ribs or the like to define the apertures between which the cables are to be located.

3. A closure as claimed in claim 1 or 2 wherein the inner closure member is substantially cylindrical with a closed end portion.

4. A closure as claimed in claim 3 wherein the end portion is dome shaped.

5. A closure as claimed in any preceding claim wherein the inner closure member is formed from plastics material.

6. A closure as claimed in any preceding claim wherein the inner closure member is formed from a heat expandible material.

7. A closure as claimed in any preceding claim wherein the preformed heat meltable sealant is carried by the inner closure member.

8. A closure as claimed in any preceding claim wherein the at least one outer heat shrinkable closure member cooperates with a body portion.

9. A closure as claimed in Claim 8 wherein the body portion includes access means for allowing access to the closure after sealing.

10. A closure as claimed in Claims 8 or 9 wherein the body portion has a normally closed end portion.

11. A closure as claimed in Claim 10 wherein the end portion is substantially dome shaped.

12. A closure as claimed in Claim 8 wherein the body portion is elongate and an outer heat shrinkable closure member and an inner closure member are each provided at each end thereof.

13. A method of forming a cable closure including the steps of providing at least one cable in at least one aperture in a heat meltable sealant between an inner and outer closure member of the type claimed in any preceding claim and heating the closure to shrink the outer closure member and to melt the sealant therebetween.

14. A method as claimed in Claim 13 wherein the heating step includes a first heating step effected by heating a portion of the outer closure member to cause this to shrink onto a body portion to provide a seal therewith and a second heating step to seal between the inner and outer closure members following the step of providing at least one cable in at least one sealant aperture between the inner and outer closure members.

15. A closure member for use as an inner closure device for a cable closure comprising an elongate body portion and a heat meltable sealant portion preformed to include a number of apertures each for receiving a cable, the body portion acting as the sealant carrier.

16. A member as claimed in Claim 15 wherein the sealant portion is preformed to include ribs of the like to define the apertures between which the cables are to be located.

17. A member as claimed in Claims 15 or 16 wherein the body portion is substantially cylindrical with a closed end portion.

18. A member as claimed in Claims 15, 16 or 17 wherein the body portion is formed from a heat expandible material.

19. A cable closure kit comprising a heat shrinkable outer closure member, an inner closure member for insertion within the outer member and a heat meltable sealant preformed to include a plurality of apertures each for receiving a cable.

20. A kit as claimed in Claim 20 wherein meltable sealant is also carried on the closure member.

21. A kit as claimed in Claims 19 or 20 wherein the preformed sealant is dimensioned to fit over the inner closure member.

22. A kit as claimed in Claim 21 wherein the sealant on the carrier includes ribs or the like for at least partially surrounding the cable when located in the apertures therein.

23. A kit as claimed in any one of Claims 19 to 22 including a body portion for use with the inner and outer closure members.

24. A kit as claimed in Claim 23 wherein the body portion is closed at one end and includes access means.

25. A kit as claimed in Claim 23 wherein the body portion is elongate and two outer and inner closure members are provided for use therewith.

26. A cable closure substantially as described herein with reference to the accompanying drawings.

27. A closure member substantially as described herein with reference to the accompanying drawings.

28. A cable closure kit substantially as described herein.