Sealing cable junctions

Abstract: To seal a cable junction, an insert is placed between two branch cables (42a,42b;55,56;56,101a,101b) of the junction, which is then enclosed by a heat shrinkable envelope (45,58,­ 103). The insert has at least one insert part having a block (32,43a,43b,50,70,80,100a,100b,100c) of heat fusible material attached by one or more flanges (31,41a,41b,51,82,102a,102b,­ 102c) of heat conductive material to the branch cables (42a,42b,­ 55,56,101a,101b). The block (32,43a,43b,50,70,80,100a,100b,­ 100c) lies between the branch cables (42a,42b,55,56,101a,101b) at least partially inside the envelope (45,58,103). Then when the envelope (45,58,103) is heated to cause it to shrink, the block (32,43a,43b,50,70,80,100a,100b,100c) fuses, thus forming a seal. For most sizes of branch cable, two insert parts may be used, but three or more may be used for large branch cables. The flange (31,41a,41b,51,82,102a,102b,102c) preferably has a tongue (33,61,81) extending into the block (32,43a,43b,50,70,80,100a,100b,100c) to assist heat conduction.

Description: The present invention relates to the sealing of cable junctions when it is desired to form a gas-tight enclosure around the junction, and when the means for supplying that enclosure is an envelope of heat-shrinkable material. The present invention relates to a method of sealing such a cable junction, and also to a device for use in such a method. The present invention may be used, for example, in the sealing of branch junctions of electric or communication cables. Where two or more branch cables emerge from an enclosure in which they are sealed, there is a problem of ensuring sealing between the cables as they emerge from one side of the junction. The problem is, of course, that as the material forming the envelope shrinks, it will tend to draw apart from the volume between the branches of the cables, and will not readily seal or bond to it. This problem has been met in the past by clipping together the material of the heat-shrinkable envelope between the branches to form an indented conformation which is forcibly held by the clip at least until the assembly is stable after each shrinkage treatment (usually heat-shrinkage). Thus, the clip resists the tendency of the material to draw apart. An example of such sealing of a cable junction is shown in Figs. 1 to 3 of the accompanying drawings. Referring to those figures, a cable junction 1 has branch cables 2,3 extending from one end 4 thereof. The branch junction is surrounded with an envelope 5 of e.g. heat-shrinkable material, which normally includes a heat-shrinkable outer layer and a fusible inner layer. When heat is applied to the envelope 5, the sleeve shrinks radially inwards and its inner surface fuses to the cable junction, thereby sealing it. As discussed above, in order to prevent the parts of the envelope 5 surrounding the branch cables 2 and 3 from moving apart, a U-shaped clip 6 is fitted over the free end of the envelope, between the branch cables 2,3. The clip 6 has a pair of generally parallel legs 7 connected together by a connecting part 8. Fig. 2 shows in more detail how the legs 7 of the clip hold the envelope 5 together between the branch cables 2,3, and Fig. 3 shows the general shape of the clip in more detail. The clip 6 is made of heat resistant material, so that it is not affected by the heat used to shrink the envelope. This arrangement has the advantage that the parts of the envelope 5 between the leg 7 of the clip will be fused together at a region 9, so that the clip 6 can be removed once the seal has been formed, if desired. However, it can be seen that gaps 10 are formed between the region 9 and the branch cables 2,3, so that complete sealing is not achieved. Furthermore, if the clip is not placed so that its axis of symmetry coincides with the axis 11 joining the centres of the branch cables 2,3, the size of the gaps 10 may be increased. A further problem is that the envelope material is greatly deformed at the region 9 between the legs of the clip, and there is the risk that it may crack. Therefore, a further arrangement that has been proposed is to provide a shaped insert within the sleeve, as shown in Fig. 4 of the accompanying drawings. In that figure, the envelope 5 and the branch cables 2,3 are the same as those in Figs. 1 to 3, and an insert 20 is fitted between the branch cables 2,3. This insert 20 has curved recesses 21,22 which receive the branch cables 2,3 and also contains means 24 for heating the material of the insert 20. When the envelope 5 is heat-shrunk around the branch cables 2,3, the insert 20 is also heated by the heating means 24, and thereby the insert 20 is sealed both to the inner surface of the envelope 5, and also to the branch cables 2,3. However, this arrangement has the disadvantages that a large volume of material is necessary to form the insert 20, and therefore the heating means 24 must be an "active" means such as resistance wire. The overall dimensions of the junction are also normally larger than that provided by the system of Figs. 1 to 3. An arrangement corresponding to Fig 1 to 3 is disclosed in GB-A-1604985. EP-A-0050995 discloses an arrangement in which the structure of Fig 1 to 3 has a middle leg that extends into the envelope at the part of the envelope between the parallel outer legs. That middle leg may carry heat fusible material which is fused by the application of heat to the envelope. This document thus corresponds to the pre-characterising part of claims 1 to 3. The present invention therefore provides a method of sealing a cable junction according to claims 1 and 3, comprising: positioning an insert between the first and second branch cables surrounding first and second branch cables of the junction with a heat shrinkable envelope and shrinking the envelope around the branch cables by the application of heat wherein the application of heat also causes the fusion of the heat fusible material and wherein the insert has two insert parts each comprising a flange of heat conductive material and a block of heat fusible material, the two insert parts being positioned so that their blocks are adjacent each other; each insert part is attached to a corresponding one of the first and second branch cables with the block of the insert parts between the first and second branch cables the flange of one of those insert parts being deformed concavely to the first branch cable and the flange of the other insert part being deformed concavely to the other branch cable; It also provides a method of sealing a cable junction, comprising: positioning an insert between the first and second branch cables the insert having a block of heat fusible material; surrounding first and second branch cables of the junction with a heat-shrinkable envelope and shrinking the envelope around the branch cables by the application of heat wherein the application of heat also causes the fusion of the material of the block of the at least one insert part and wherein the insert has a least one insert part comprising two flanges of heat conductive material; prior to the application of heat, the at least one insert part is attached to the first and second branch cables with the block of the at least one insert part between the first and second branch cables each flange being deformed concavely to a corresponding one of the first and second branch cables; wherein the application of heat also causes the fusion of the material of the block of the at least one insert part. In another aspect, as defined in Claims 11,13 it provides an assembly for sealing a cable junction comprising: an insert positioned between first and second branch cables of the junction, a heat shrinkable envelope around the branch cables, at least a part of each of the blocks being within the envelope; wherein the insert has two insert parts, each comprising a flange of heat conductive material and a block of heat fusible material, the two insert parts being positioned so that their blocks are adjacent each other; the flange of one of the insert parts being deformed concavely to the first branch cable and the flange of the other insert part being deformed concavely to the other branch cable. Within this aspect, it also provides an assembly for sealing a cable junction comprising: an insert positioned between first and second branch cables of the junction, a heat shrinkable envelope around the branch cables the insert having at least one insert part having a block of heat fusible material wherein the insert part has two flanges of heat conductive material; each flange of the at least one insert part being attached to a respective one of the first and second branch cables with the block of the at least one insert part between the first and second branch cables; at least a part of the block being within the envelope. Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figs. 1 to 3 show a first known system for sealing a cable branch junction, and have already been described; Fig. 4 shows a second known arrangement for sealing a cable branch junction, and has already been described; Fig. 5 shows a first embodiment of an insert part according to the present invention for sealing a cable branch junction; Fig. 6 shows two insert parts as illustrated in Fig. 5 fitted between two branch cables; Fig. 7 shows the insert parts and two branch cables of Fig. 6 enclosed in a shrinkable envelope; Fig. 8 shows the insert parts and branch cables of Fig. 6 with the envelope shrunk to its final position; Fig. 9 shows a second embodiment of an insert part according to the present invention; Fig. 10 shows a perspective view of the insert part of Fig. 9 fitted between two branch cables, and enclosed in a shrinkable envelope; Fig. 11 shows a detail of the insert part of Fig. 9; Fig. 12 shows a cross-sectional view of the arrangement of Fig. 10, prior to shrinkage of the envelope; Fig. 13 shows a view similar to Fig. 12, but after shrinkage of the envelope; Fig. 14 shows a view similar to Fig. 12, but in which the insert part has been modified; Fig. 15 shows another embodiment of an insert part according to the present invention; Fig. 16 shows yet another insert part according to the present invention; Fig. 17 shows a cross-sectional view of the insert part of Fig. 16; Fig. 18 shows three insert parts as shown in Fig. 16 positioned between two branch cables; Fig. 19 shows a cross-sectional view through the branch cables of Fig. 18, prior to shrinkage of the envelope; and Fig. 20 shows a cross-sectional view corresponding to Fig. 19, but after shrinkage of the envelope. A first embodiment, presently preferred, of the present invention will first be described with reference to Figs. 5 to 8. In this embodiment an insert for sealing two branch cables comprises two insert parts 30 generally in a T-shape and including a flange 31, one such insert part being shown in Fig. 5. The insert part 30 has a T-shaped flange 31 of heat-conductive material, e.g. aluminium which is connected at its central position to a block 32 of resilient material, e.g. a thermoplastic material such as polyethylene, (PVC) and associated copolymers of either polyethylene or PVC, through a tongue 33, the free end of which tongue 33 is embedded in the block 32. The flange 31 is relatively thin and so is deformable so that the flange 31 can be deformed concavely to the cable. The block 32 may also be thin, although its volume is determined by the amount of material needed to fill the space between the envelope and the branch cables. To fit the insert parts to two branch cables to be aligned and sealed, two insert parts as shown in Fig. 5 are placed between the two branch cables, with the plane of the insert parts (the plane seen in plan in Fig. 5) tangential to the branch cables. Then, as shown in Fig. 6, flanges 41a,41b are each wrapped around the corresponding one of the branch cables 42a,42b so that the insert parts are secured to the branch cables 42a,42b. It would also be possible, of course, to wrap the flanges 41a,41b around the branch cables 42a,42b and then place the branch cables 42a,42b in the position shown in Fig. 6. The flanges 41a,41b may be simply deformed concavely in the direction of corresponding branch cables 42a,42b so that excessive heat should not be applied to the branch cables 42a,42b when the flanges 41a,41b are heated. In either case, the blocks 43a,43b of the insert parts then lie between the two branch cables 42a,42b and extend generally tangentially of those branch cables 42a,42b as shown in Fig. 7. Fig. 7 also illustrates that the width (dimension D in Fig. 5) is chosen so that is greater than the distance between the theoretical tangential lines 44 joining the branch cables 42a,42b. A support means generally in a cylindrical form made of a heat and mechanical load resistant material such as metal may be placed to hold the junction before it is surrounded by an envelope 45 made of a heat shrinkable material. The envelope 45 is then wrapped around the insert/branch cable assembly and secured in place. The envelope used in this embodiment may be a conventional one, such as has been described earlier with reference to Fig. 1. Heat is applied to the envelope 45 to cause it to shrink and apply a compressive force to the assembly. The usual way of applying heat is to play a blow torch on the assembly from its outside and by ensuring that the play of the blow torch extends to the flanges 41a,41b of the insert parts, which flanges 41a,41b are outside the envelope 45, satisfactory heating of the blocks 43a,43b will be achieved to cause them to fuse. As the envelope 45 shrinks, the blocks 43a,43b will be compressed so as to fill the spaces 46 around the branch cables within the envelope 45. Of course, where the envelope is elongate, it is not necessary that the blocks 43a,43b extend over the full length of the envelope 45. Provided that the spaces 46 are filled over at least part of the length of the envelope 45, then satisfactory sealing of the branch cables 42a,42b will be achieved. The result is shown in Fig. 8, in which the block material 47 fills completely the space within the envelope 45. The result is, in many ways, similar to that known from the system described with reference to Fig. 4, but it should be noted that it has not been necessary to provide active heating of the block material, and thus the method of production is simplified. By suitable choice of the material of the blocks 43a,43b that material will fuse when the envelope 45 is heated, causing it to fuse and set to the cables and the envelope. The cable may be covered with the material that will fuse and set with the block material; this may for example, be a coating of material identical to the insert material, or a tape of fusible material wound around the branch cables where the branch junction is to be formed. The embodiment of Figs. 5 to 8 may be further modified by forming the blocks of the insert parts from a material which expands on heating. Then, the blocks need not initially extend beyond the tangential lines of the branch cables, but will expand on heating against the shrinking envelope, and so be compressed around the cables. It should also be noted that Figs. 5 to 8 illustrate branch cables of the same diameter, but it is possible to align branch cables of different diameters in exactly the same way. Fig. 9 shows a second insert part, in which the block 50, of heat-fusible resin, is connected to two flanges by corresponding tongues extending from those flanges 51,52. As can be seen, the block 50 is defined by a pair of generally rectangular block parts 53 which are connected together along a central line of one of their faces, in a direction generally parallel to the direction of the tongue. It can also be seen that the two block parts 53 are curved away from each other to give a measure of conformity to the branch cables between which they are to be fitted. The flanges 51,52 of the insert part may, as shown, each be generally similar to the flange of the insert part of Fig. 5, but as illustrated, spots 54 of a temperature-indicating paint (heat-sensitive paint) may be provided on their opposed surfaces, which surfaces will be outermost when the flanges 51,52 are wrapped around the branch cables. Such heat-sensitive paint may also be used on the flanges of the insert part shown in Fig. 5. As shown in Fig. 10, the insert part of Fig. 9 is positioned between two branch cables 55,56 extending from a branch junction 57, and enclosed within a heat-shrinkable envelope 58, with the flanges 51,52, projecting therefrom. As shown in Fig. 10, the envelope 58 is formed by wrapping a sheet of suitable material around the junction, and then clipping its free edges together by suitable clips 59. Such clips 59 are also shown in Figs. 7 and 8. Furthermore, in order to hold the branch cables 55,56 in place, adhesive tape 60 may be wrapped around them adjacent the junction 57. Fig. 11 illustrates a development of the insert part of Fig. 9, which is also applicable to the insert part of Fig. 5. In this development, the tongue 61 projecting from the flange 52 (and also the tongue projecting from the flange 51) have slots 62 formed therein through which the material of the block 50 extends. In this way, the block material is secured to the tongue 61 so that the heat is transmitted to the block 50 by the tongue 61. The sealing of a branch junction by an insert part described with reference to Figs. 9 to 11 will now be described with reference to Figs. 12 and 13. In fact, the arrangement is very similar to that described in Figs. 7 and 8, in that the envelope 58, and the flanges 51,52 of the insert parts are heated, causing the envelope 58 to shrink until it has reached a position 62' in which it bears on the outer edges of the block parts 53. Then, conduction of heat from the flanges 51,52 along the tongues 61 from those flanges causes the block material to melt, thereby permitting further shrinkage of the sleeve 58 with the block material filling the spaces 63. The result is shown in Fig. 13, in which block material 64 entirely fills the volume within the envelope 58 between the branch cables 55,56. Fig. 14 shows a further modification of the block parts 53. In this modification, the outer edges 65 of the block parts 53 are thicker (in a direction perpendicular to the plane of the flanges 51,52 and the tongue 61) so that there is more block material where it will be needed, rather than between the branch cables 55,56 where it is less necessary. Fig. 15 shows a further embodiment of an insert part according to the present invention, being a modification of the insert part of Fig. 9. In this modification, the flanges, tongues, etc. may be identical to those shown in Fig. 9 and will not be described in detail now. The difference, however, is that the block 50 has curved surfaces 70,71 which receive the branch cables when the insert is fitted between those branch cables. It can also be seen from Fig. 15 that the branch cables need not be the same size, and by suitable curvature of the surface 70,71, different sized cables can be accommodated. Another embodiment of the present invention will now be described with reference to Figs. 16 to 20. This embodiment is particularly appropriate when the branch cables are large. Referring first to Fig. 16, an insert part has a block attached by a tongue 81 to a flange 82. The block 80 is preferably of thermoplastics material, and the tongue 81 and flange 82 are preferably of aluminium. As can be seen from Fig. 16, the end 83 of the tongue 81 which is within the block may be wider than other parts of the tongue 81, to ensure good bonding of the block material to the tongue 81. To improve this bonding further, through-holes 84 may be provided in the end 83 of the tongue 81, through which block material will extend, so securing the block 80 to the tongue 81. This is similar to the function of the slots 62 in Fig. 11. It may also be noted that this widening 83 of the tongue 81 may also be applied to the embodiment of Fig. 5, provided that the total width of the tongue is not so large as to cause it to project beyond the theoretical tangential lines joining the branch cables. As can be seen from Fig. 17, the block has a central region 90, at least part of which has a first thickness, and side regions 91 which are thinner. In this embodiment, thickness refers to the direction perpendicular to the plane of the flange and tongue, length refers to the direction parallel to the direction of extension of the tongue 81 from the flange 82, and the plane of the tongue and the flange, and width refers to the direction perpendicular to the direction of extension of the tongue 81, again in the plane of the tongue and the flange. Collapsible meshes (or foils) 92 which are preferably made of aluminium for good conduction of heat and flexibility, are embedded in the block 80 and (as shown) lie substantially parallel to the wider part 83 of the tongue. The meshes 92 extend along the full width of the central part 90 of the block 80, and indeed may extend into the thinner side regions 91, to help conduct heat towards the edges of the block. The meshes 92 deform when the heat-shrinkable sleeve tightens around them. The purpose of providing the thinner side regions 91 is that they soften earlier than would be the case if they were the same thickness as the central region 10. This early softening permits the side regions 91 to deform more rapidly with the shrinkage of the sleeve. Also, as can be seen from Fig. 17, the central region 90 itself has a thinner part 91 in the middle thereof, as it is not necessary that this part contains a large volume of block material. In use, one or more such insert parts are placed between branch cables to be sealed. The arrangement of Figs. 5 to 8 discuss the use of two insert parts, but Fig. 18 shows the use of three insert parts, which may be the same as in Fig. 16 or 17, or possibly as shown in Fig. 5. For very large branch cables, four or more insert parts may be necessary. The three insert parts 100a,100b,100c are placed adjacent each other between the branch cables 101a,101b, and the flanges 102a,102c of the outer two insert parts are each wrapped around the corresponding adjacent branch cable 101a,101b. The flange 102b of the central insert part is not deformed. Then, as shown in Fig. 19, a heat-shrinkable envelope 103 is wrapped around the branch cables 101a,101b and the blocks 100a,100b,100c of the insert parts. Heat is applied to the envelope 103 and also the flanges 102a,102b,102c to cause the envelope 103 to shrink and also cause the blocks 100a,100b,100c to soften. The heating is continued until the stage shown in Fig. 20 is reached, in which the envelope 103 conforms closely to the tangential lines joining the branch cables 100a,100b, and the interior of the envelope 103 is filled with material from the blocks 100a,100b,100c. Fig. 5 also shows the ends 83a,83b,83c of the tongues of the insert parts and the deformed meshes 92 lying between the branch cables 101a,101b. Apart from the details of the shape of the blocks, the manner in which better heat conduction is achieved through the blocks, and the number of insert parts used, the sealing of cable junctions described in this embodiment is similar to that described for the other embodiments, and therefore developments also discussed with reference to those embodiments may be used with the insert parts of this embodiment. For example, as mentioned above, it is not necessary that the blocks of the insert parts extend over the full length of the envelope. Provided that the space within the envelope 103 is filled over at least a part of the length of the envelope 103, then satisfactory sealing of the branch cables will be achieved.

Claims: A method of sealing a cable junction, comprising: positioning an insert between the first and second branch cables (42a, 42b; 55, 56; 101a, 101b) the insert having first a part of heat conductive material and a seond part of heat fusible material; surrounding first and second branch cables (42a, 42b, 55, 56; 101a, 101b) of the junction with a heat shrinkable envelope (45, 58, 103); and shrinking the envelope (45, 58, 103) around the branch cables (42a, 42b, 55, 56, 101a, 101b) by the application of heat; wherein the application of heat also causes the fusion of the heat fusible material; characterised in that: the insert has two insert parts each comprising a flange (31, 41a, 41b, 51, 82, 102a) of the heat conductive material and a block (32, 43a, 43b, 50, 70, 80, 100a, 100c) of the heat fusible material, the two insert parts being positioned so that their blocks (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) are adjacent each other; and each insert part is attached to a corresponding one of the first and second branch cables (42a, 42b, 55, 56; 101a, 101b) with the block (32, 43a, 43b, 50, 70, 80, 100a, 100c) of the insert parts between the first and second branch cables (42a, 42b; 55, 56, 101a, 101b) the flange (31, 41a, 51, 82, 102a) of one of those insert parts being deformed concavely to the first branch cable (42a; 55; 101a) and the flange (31, 41b, 51, 82, 102c) of the other insert part being deformed concavely to the other branch cable 42b; 56; 101b). A method according to claim 1, wherein the insert has at least three insert parts, being two outer insert parts and at least one central insert part between the outer insert parts, the flange (102a) of one of the outer insert parts being deformed concavely to one of the branch cables (101a) and the flange (102c) of the other outer insert parts being attached to the other branch cable (101b). A method of sealing a cable junction, comprising: positioning an insert between the first and second branch cables (42a, 42b; 55, 56; 101a, 101b); the insert having a block (32, 43a, 43b, 50, 70, 80, 100a. 100b, 100c) of heat fusible material and a part of heat conductive material; surrounding first and second branch cables (42a, 42b, 55, 56; 101a, 101b, of the junction with a heat-shrinkable envelope (45, 58, 103); and shrinking the envelope (45, 58, 103) around the branch cables (42a, 42b; 55, 56; 101a, 101b) by the application of heat; wherein the application of heat also causes the fusion of the material of the block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) of the at least one insert part; characterised in that: the insert has at least one insert part comprising two flanges (31, 41a, 41b, 51, 82, 102, 102b, 102c) of the heat conductive material; and prior to the application of heat, the at least one insert part is attached to the first and second branch cables with the block (32, 43a, 43b, 50, 70, 80, 100a 100b, 100c) of the at least one insert part between the first and second branch cables (42a, 42b, 55, 56; 101a, 101b), each flange (31, 41a, 41b, 51, 82, 102, 102b, 102c) being deformed concavely to a corresponding one of the first and second branch cables (42a, 42b, 55, 56; 101a, 101b). A method according to any one of the preceding claims wherein the block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) of the at least one insert part projects beyond the theoretical tangential lines joining the first and second branch cables (42a, 42b; 55, 56; 101a, 101b) least during the shrinking of the envelope (45, 58, 103). A method according to any one of the preceding claims, wherein the material of the block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) of the at least one insert part has a higher melt flow index and a lower melting point than the material of the envelope (45, 58, 103). A method according to any one of the preceding claims, wherein the or each flange (31, 41a, 41b, 51, 82, 102, 102b, 102c) is planar and the or each block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) has a central region and outer regions on opposite sides of the central region at least a part of the central region being of a first thickness in a direction perpendicular to the plane of the flange (31, 41a, 41b, 51, 82, 102a, 102b, 102c), and the outer regions have a thickness in that direction less than the first thickness. A method according to claim 6, wherein the central region has a part with a thickness in the direction perpendicular to the plane of the flange (31, 41a, 41b, 51, 82, 102, 102b, 102c) which is less than the first thickness. A method according to any one of the preceding claims wherein the or each flange (31, 41a, 41b, 51, 82, 102a, 102b, 102c) is connected to the corresponding block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 1000c) by a tongue (33, 61, 81) extending into the block (82, 43a, 43b, 50, 70, 80, 100a, 100b, 100c). A method according to claim 8 wherein the tongue (33, 61, 81) has through holes (62, 84) therein, that material of the block, (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) extending through the holes (62, 84). A method according to any one of the preceding claims wherein the block (32, 43a, 43b, 50, 70, 80, 100a 100b, 100c) has at least one collapsible heat conducting member therein. An assembly for sealing a cable junction comprising: an insert positioned between first and second branch cables (42a, 42b; 55, 56; 101a, 101b) of the junction, the insert having first a part of heat conductive material and a second part of heat fusible material, a heat shrinkable envelope (45, 58, 103) around the branch cables (42a, 42b, 55, 56, 101a, 101b), at least a part of each of the blocks (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) being within the envelope (45, 58, 103); characterised in that: the insert has two parts, each comprising a flange (31, 41a, 41b, 51, 82, 102a, 102b, 102c) of the heat conductive material and a block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) of the heat fusible material, the two insert parts being positioned so that their blocks (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) are adjacent each other; the flange (31, 41a, 51, 82, 102a) of one of the insert parts being deformed concavely to the first branch cable (42a, 55, 101a) and the flange (31, 41b, 51, 82, 102x) of the other inert part being deformed concavely to the other branch cable (42b, 56, 101b). An assembly according to claim 11, wherein the insert has at least three insert parts, being two outer insert parts and at least one central insert part between the outer insert parts, the flange (31, 41a, 51, 82, 102) of one of the other insert parts being deformed concavely to one of the branch cables (42a, 55, 101a) and the flange (31, 41b, 51, 82, 102b) of the other outer insert parts being deformed concavely to the other branch cable (42b, 56, 101b). An assembly for sealing a cable junction comprising: and insert positioned between first and second branch cables (42a, 42b; 55, 56; 102a, 102b) of the junction, a heat shrinkable envelope (45, 58, 103) around the branch cables (42a, 42b; 55, 56; 102a, 102b), the insert having at least one insert part having a block of (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) of heat fusible material and a part of heat conductive material, at least a part of the block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) being within the envelope (45, 58, 103); characterised in that: the insert part has two flanges (31, 41a, 41b, 51, 82, 102a, 102b, 102c) of heat conductive material; each flange (31, 41a, 41b, 51, 82, 102a, 102b, 102c) of the at least one insert part being attached to respective one of the first and second branch cables (42a, 42b; 55, 56; 102a, 102b) with the block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) of the at least insert part between the first and second branch cables (42a, 42b; 55, 56; 102a, 102b). An assembly according to any one of claims 12 to 13, wherein the block (32a, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) of the at least one insert part projects beyond the theoretical tangential lines joining the first and second branch cables (42a, 42b; 55, 56; 101a, 101b). An assembly according to any one of claim 12 to 14, wherein the block (32, 43a, 43b, 50, 70, 80, 100a, 100b, 100c) has a central region and outer regions on opposite sides of the central region, at least a part of the central region of the block being of a first thickness in the direction of the line joining the centres of the branch cables (42a, 42b; 55, 56, 101a, 101b), and the outer regions have a thickness in that direction less than the first thickness. An assembly according to claim 15, wherein the central region has a part with a thickness in the direction joining the centres of the branch cables (42a, 42b; 55, 56; 101a, 101b) which is less than the first thickness.

Inventors: CURTIS ROBERT LESLIE, GOTO SHIGENORI, MAKIYO MINORU, WADE PHILIP JAMES, YOKOSUKA HIROSHI, CURTIS, ROBERT LESLIE, GOTO, SHIGENORI, MAKIYO, MINORU, WADE, PHILIP JAMES, YOKOSUKA, HIROSHI
Applicants: FUJIKURA LTD, FUJIKURA LTD.
Application year: 1987
Main classification: H02G15
IPC codes: H02G15, B29C61