FR2676796A1 - Article, set of components, and method for forming a sealed branch joint - Google Patents

Abstract

The invention relates to an article which can form a sealed branch joint between a heat-shrink sleeve and substrates of each of at least two different configurations. It includes two parts (7, 8) which can be softened by heat and placed between substrates inside the sleeve. The shape of one of the parts, in transverse section, corresponds to a first configuration of branch, and that of the second part corresponds to a second configuration of branch. Means (3) make it possible to limit the flow of the material when it is heated, in a direction substantially perpendicular to the transverse sections of the parts. Field of application: connection of power cables, telecommunication cables, etc.

Description

 The present invention relates to an article for forming a watertight bypass joint in conjunction with a heat-shrinkable sleeve. It has been found that the article and the sleeve are particularly useful for forming a watertight joint around telecommunications cable, power or other cables, in particular. particular to a cable splice.

 When a cable splice is made, cable sheaths located on the spliced cables are cut and removed to expose the inner conductors.

After the conductors have been connected, the insulation, previously provided by the sheaths, must be restored on the splice. For this purpose, a housing known as a splice box is produced, surrounding the splice and extending from the intact sheath of the input cables to the intact sheath of the output cables.

 Heat shrink sleeves, which can be of the tubular or coiled type, are commonly used to form splice cases or wraps, as they can be supplied in an oversized condition and easily installed around the splice, and then retracted at least each from their ends to contact with the spliced cables.

 This use of a heat-shrinkable sleeve is simple in the case where a single cable enters the splice, since the shape of the cross section of a single cable is obviously entirely convex. As a result, a surrounding sleeve shrinks tightly around the cable, leaving no so-called leakage path between it and the cable, which path would allow moisture or other contaminants to enter the splice jacket. to train.

 In the case of branched or branched cable splices, two or more cables run side by side. The two cables together have a partially concave or re-entrant cross section to the sleeve surrounding them. If a sleeve has retracted around two cables, a watertight seal will therefore not be produced.

 This problem is known as "bypass" and it has been resolved, for most applications, by the use of a bypass clip as described in British patent application GB-B-1 604 981.

This patent describes a method for forming a tight bypass joint between a heat-shrinkable sleeve and at least two substrates (for example cables), which comprises the steps of
(a) positioning the substrates inside
laughing heat shrink sleeve
(b) form at least two terminal conduits
heat shrinkable by positioning a
fastener having at least two branches
lying on the outside surface of the
heat shrink sleeve at one end
open mite of it, at least two
said branches being placed ex
behind the sleeve and the substrates
located inside the conduits
terminals; and
(c) while the clip remains on the on
outer face of the thermo sleeve
retractable, to apply heat
to remove the sleeve
and form the desired seal.

 The fastener may include a third leg coated with a hot melt adhesive which is placed inside the sleeve between the substrates, and the sleeve may also be coated internally with a hot melt adhesive.

 Bypass gaskets can also be used by the use of fillers, rather than fasteners, these filled fillers being placed inside the sleeve and between the bypassed substrates.

 Patent EP-A-0 151 512 shows, in FIG. 13, a filling part designed for the derivation of four cables. The filler piece includes a heat activatable sealant, such as a hot melt adhesive, and a heating element. The filling piece has parts cut along the circumference and extending along its length, in which the branch cables can be received. In general, two extreme layers are provided to prevent the activated sealant from flowing longitudinally, but in some cases only one may be sufficient. At one end of a cable splice enclosure, for example, only the outward end of the filler may require an end layer to prevent the sealing material from flowing. end may include foam or other suitable material.

 Sometimes the configuration of branch cables whose sealing must be achieved may not be known in advance. For example, we can meet a splice having two cables at the output, or three cables, or four cables, etc. This uncertainty poses a problem because it results in the worker in the field having to carry a wide range of different products demanded for different bypass configurations.

 A solution to this is proposed in French patent N 2 614 148. A filling part in two parts, which can be softened by heat, is intended to be placed between cables in diversion inside the end of a heat-shrinkable sleeve. The first part has a substantially rectangular cross section and has concave main sides, extending longitudinally. It is used alone in the case where the waterproofing of a bypass of two cables must be carried out. It is simply placed between the two cables, the concave surfaces corresponding to the convex surfaces of the cables between which it is placed.The second part is of a substantially triangular cross section and, as before, its surfaces extending longitudinally are concave. used alone in the case where the waterproofing of a bypass of three cables must be carried out. A cable is placed along each side of the triangle. The two parts are used together when the watertightness of a four-cable bypass can be achieved. The two parts are supplied by being detachably joined together to allow adaptation of the product, in the field, according to the configuration of cables encountered.

 Various problems have been noted with the filling piece described in the aforementioned French patent No. 2,614,148. For example, the shape and often the separability of the two parts is not maintained during storage. It is obvious that the parts must be able to be softened by heat, since it must deform and ensure sealing during the hot installation of the sleeve surrounding them. Unfortunately, this deformation often occurs prematurely. One test is that such parts survive storage at 70 ° C for five days. It appeared difficult to reconcile such a requirement with the ease of installation without damaging the cable and other problems.

 Nevertheless, means have been devised for producing, and, in a preferred embodiment, means for packaging, these first and second parts so that the conflicting requirements of storage, ease of installation and performance can be satisfied.

Thus, the invention provides an article capable of forming a tight bypass seal between a heat-shrinkable sleeve and the substrates of each of at least two different configurations, which comprises
(a) a first part which can be softened
heat bond, which can be placed
between substrates inside the
muff
(b) a second part which can be softened
by heat, attached in a detailed manner
chable in the first part and can
be placed between substrates inside
inside of sleeve
(i) a cross-sectional shape
of the corresponding first part
to a first configuration of
derivation and a sectional shape
transverse of the second part
corresponding to a second con
derivation figuration; and or
(ii) the cross-sectional shape of
the first part corresponding to
the first configuration
vation and shape in section
transverse of the first and
conde parties, set, correspon
in the second configuration of
bypass; and
(c) a means which may oppose
the flow of raw material
and second parts in one direction
substantially perpendicular to the dry
transverse tions.

The invention also provides an article capable of forming a tight bypass seal between a heat-shrinkable sleeve and substrates of each of at least two different configurations, which comprises
(a) a first part which can be softened
heat-bound and can be pla
created between substrates inside the
muff ; and
(b) a second part which can be softened
by heat, attached in a detailed manner
chable in the first part and can
be placed between substrates inside
inside of sleeve
(i) a cross-sectional shape
of the corresponding first part
to a first configuration of
derivation and a sectional shape
transverse of the second part
corresponding to a second con
derivation figuration; and or
(ii) the shape of the cross section
of the corresponding first part
at the first configuration of
derivation and shape of the dry
transverse tion of the first and
second parts, together, matches
according to the second configuration
bypass; and
(c) a retaining layer on surfaces,
extending longitudinally, pre
first and / or second parts.

 Such articles can be provided as part of a set of parts with which is associated a tubular or coiled heat shrinkable sleeve. Such a sleeve advantageously comprises a composite reinforced with fibers, in particular a composite which can be retracted by virtue of a constituent with retractable fibers of this composite.

The article can be used to form a bypass seal, particularly around a bypass splice in a telecommunications or power cable. The invention therefore also provides a method for forming a bypass seal between a heat-shrinkable sleeve and at least two substrates, which comprises the steps which consist
(a) to use an article of the invention and
a heat shrinkable sleeve
(b) choose the first part, the second
part or the first and second by
ties together depending on the con
figuration of substrates
(c) placing the sleeve around the subs
trats
(d) to place the first part, the second
part or the first and second by
ties together, as appropriate, within
laughing sleeve and between subs
trats; and
(e) applying heat to soften
the first and / or second parts and
retract the sleeve to form the
watertight seal desired.

 It is advantageous that the means (c), which can oppose the flow of the material from the first and second parts, include a layer of foam. They can however include any material which does not flow notably (and advantageously not at all) at the softening temperatures of the first and second parts. Such a material is advantageously presented in the form of layers attached (generally directly and face to face) to the extreme faces of the first and second parts. A layer is preferably provided at an end face or at each end face of the first and second parts combined, each layer extending over the two parts.

 It is advantageous that it is unnecessary to remove these means (c) to separate, when necessary, the first and second parts. However, this removal is possible and the removed means (c) can then be cut and their pieces reapplied to each of the first and second parts. On the other hand, it is preferred that each layer, or that other means (c), be provided with a weakening line (such as a notch extending parallel across its thickness or partially across its surface, or two, or a line of perforations, etc.), allowing it to be cut during the separation of the first and second parts.

 In general, the layers, or other means (c), have a surface shape and advantageously a dimension corresponding to (and advantageously identical to) the shape of the cross section of the first and / or second parts.

 To ensure the formation of a good seal in the bypass area of the splice envelope, it is necessary that, when the sleeve is heat shrunk, the first and second parts do not excessively flow approximately perpendicular to the section transverse of the parts, that is to say generally longitudinally to the cables. This is obviously the function of the means (c). Restricted flow means cleaning or otherwise preparing a shorter cable length, less sealing material, and a cleaner and generally more rectangular sleeve end. However, some flow may be desirable.First, the parts are intended to deform to fill any voids between the cables and the sleeve surrounding them, and we cannot provide close manufacturing tolerances taking into account the different cable dimensions and different diversion configurations encountered. An even greater degree of flow may be desired if the parts include a hot melt adhesive which is intended to bond to cables and the sleeve. Another reason is that some flow of material from the parts outside of the splice shell may be desirable to provide a visible indication of sufficient application of heat. This reason does not apply to a flow entering the envelope of the splice. We therefore prefer that the means (c) restrict the flow of the material of the first and second parts in each of two opposite directions, the degree restriction in one direction being greater than the degree of restriction in the other direction. This can be achieved if the means (c) comprises a first layer on one end face of the parts and a second layer on the other end face, the first and second layers being of different thicknesses along said direction and / or s 'extending to different degrees on the respective end faces, and / or having different resistances.

 The first and second parts are preferably substantially cylindrical, one of them advantageously having a substantially triangular cross section and / or the other having a substantially rectangular cross section. Surfaces of the parts, extending longitudinally, are advantageously concave, the concavities being capable of receiving, at least to a certain degree, the cables with which sealing must be carried out. In this way, the first and second parts can be provided with cross-sectional shapes which correspond to various cable branching configurations. For example, a rectangular part having long opposite concave sides corresponds to two cables side by side, and a triangular part with concave sides corresponds to three cables placed at the angles of a triangle turned by 60 relative to the part.

 The first and second parts advantageously comprise an adhesive, for example a polyolefin-based material, such as a polyethylene or a copolymer such as an ethylene-vinyl acetate, or a polyamide-based material. It can contain a filler such as heat conducting particles or another material, such as graphite or carbon black. Its mechanical properties depend on the conditions under which it must be stored, installed and the service to be provided. However, for many applications, it is preferred that it has a Brookfield HBT viscosity at 160 C of between 1 and 150 Pa.s, in particular 30-60 Pa.s, and that it has a softening point TMA T60 of 65 to 105 C, especially 70 to 85 C.

 We can now consider why and how the first and second parts are advantageously detachably joined to each other.

 The two parts are supplied joined to each other and can be used together for sealing cables having a configuration which corresponds to their combined shape, generally four cables at the corners of a square or a rectangle. If two cables are encountered, the parts can be separated and, for example, the first of them used; and if three cables are encountered, the second of them can be used. These are only examples and the parts can be formed for other configurations.

 It is preferred that the parts are joined to each other by a veil or other means which extends between them, which is advantageously in one piece with them and which can be torn by hand if desired . The veil advantageously joins the parts so that they can be used together without tearing the veil and repositioning the parts relative to one another.

Thus, the veil being intact, the surfaces (rather than simply the edges), are advantageously in abutment. The veil, etc., advantageously extends over the length of the two parts and advantageously at an edge rather than along a surface between two edges. The positioning of the veil at one edge facilitates the tearing of the veil because the two parts can be pivoted relative to each other, which allows them to be taken more easily. It also allows easier insertion of a protective layer between the parts, thus preventing the two parts from bonding by coalescence if they are stored at a high temperature.

Such a separating layer can comprise at least part of a retaining layer, and this will now be described.

 A retaining layer is advantageously provided to help maintain the cross-sectional shapes of the parts during storage at an elevated temperature. Unlike the extreme foam layers described above, it is intended (although this is not always necessary) that it be removed from the parts before use.

 A retaining layer advantageously extends over the surfaces of the parts extending longitudinally. Such a layer can be provided in the absence of the means (c), and it advantageously extends around the first and second parts. The first and second parts are advantageously in abutment with one another and, as mentioned above, they are advantageously joined to each other by a web located between them. The retaining layer advantageously extends between these abutment surfaces. It is preferred that the retaining layer which thus extends is attached to or made in one piece with a retaining layer which extends around outwardly facing surfaces of the first and / or second parts. This ensures that the part of the retaining layer between the parts is removed if its visible outer part is removed, so a leakage path between the two parts is less likely to form.

 The retaining layer advantageously comprises a thin sheet of aluminum or of another metal, and it is advantageously held in a removable manner (for example by a weak bond or mechanically) on the first and / or the second part. A separation layer or separation composition may be provided between the layer and the parts.

 Other means may be provided to help reduce the deformation of the first and second parts during high temperature storage. For example, they may be provided with a tightly fitting outer package. Since it is generally difficult to produce a separate container within the narrow tolerances required to eliminate the casting of the parts, it is preferred to use vacuum packaging.

The invention is further illustrated by the accompanying drawings in which
FIGS. 1A and 1B show a filling piece of the prior art, which can be heated electrically, and how a similar piece is used
Figures 2 and 3 show the filling pieces of the prior art, in two parts
Figure 4 shows a filling part of the invention;
FIG. 5 shows a retaining layer to be used around the filling part of FIG. 4 and
Figure 6 shows the filling part with a retaining layer in a vacuum package.

 Figures 1A and 1B show a filling piece of the prior art and how a similar piece is used. These figures are taken from the aforementioned patent EP-A-0 151 512. A filling piece 1 comprises a material 2 which can be softened by heat, having concavities along its surfaces for receiving cables to be sealed. The foam extreme layers 3 are shown, as is an interior electric heating element 4. FIG. 1B shows a filling part 1 placed inside one end of a heat-shrinkable sleeve 5 between the cables 6 of derivation. The sleeve is then shrunk hot and the part 1 is softened hot.

 A filling part in two parts, according to the aforementioned patent No. 2,614,148, is shown in FIGS. 2 and 3. The two parts 7, 8 are joined by a web 9.

 The invention is shown in Figures 4 to 6.

 In FIG. 4, the two parts 7, 8 are provided with end layers of foam which can serve as a barrier preventing excessive longitudinal flow of the softened material of which the parts 7, 8 are made. The two parts are joined by a web 9 When joined, it can be seen that surfaces 10 and 11 are in abutment. A weakening line 12 can be seen in one of the extreme layers 3, allowing it to be separated into two parts corresponding to parts 7, 8.

 A thin sheet retaining means 13 is shown in FIG. 5. This is wrapped around the two parts of FIG. 4. The part 14 is inserted between the surfaces 10, 11.

 The assembled part is shown in Figure 6 in a vacuum package.

 It goes without saying that numerous modifications can be made to the article and to the method described and represented without departing from the scope of the invention.

Claims (32)

 1. Article capable of forming a leak-tight seal between a heat-shrinkable sleeve and substrates of each of at least two different configurations, characterized in that it comprises  (a) a first part (7) which can be  softened by heat, which can be  placed between substrates inside  sleeve; and  (b) a second part (8) which can be  softened by heat, so joined  detachable from the first part and for  before being placed between substrates  inside the sleeve  (i) a cross-sectional shape  of the corresponding first part  to a first configuration of  derivation and a sectional shape  transverse of the second part  corresponding to a second con  derivation figuration; and or  (ii) the cross-sectional shape of  the first part corresponding to  the first configuration  vation and shape in section  transverse of the first and  conde parties, set, correspon  in the second configuration of  bypass; and  (c) a means (3) which can limit the flow  first and second material  parts in a direction substantially  perpendicular to the cross sections  dirty.  2. Article according to claim 1, characterized in that the means (c) comprises a layer (3) of foam.  3. Article according to one of claims 1 and 2, characterized in that the means (c) comprises a material which does not flow notably at the softening temperatures of the first and second parts, the material of the means (c) being presented in layers attached to end faces of the first and second parts.  4. Article according to claim 3, characterized in that a layer (3) is provided at one or each end face of the first and second parts combined, each layer extending over the two parts.  5. Article according to claim 4, characterized in that each layer has a line of weakness (12) allowing it to be cut during the separation of the first and second parts.  6. Article according to any one of claims 2 to 5, wherein the layer or layers comprising the means (c) have a surface shape corresponding to the shape of the cross section of the first and / or second part .  7. Article according to any one of the preceding claims, characterized in that the means (c) restricts the flow of material from the first and second parts in each of two opposite directions, the degree of restriction in one direction being greater than the degree of restriction in the other direction.  8. Article according to claim 7, characterized in that the means (c) comprises a first layer (3) on one end face and a second layer (3) on the other end face, the first and second layers being of different thicknesses in said direction and / or extending to different degrees on the respective end faces, and / or having different resistances.  9. Article according to any one of the preceding claims, characterized in that each of the first and second parts is substantially cylindrical.  10. Article according to claim 9, characterized in that one of the first and second parts has a substantially triangular cross section and / or the other of the first and second parts has a substantially rectangular cross section.  11. Article according to claim 10, charac terized in that the surfaces (10, 11) extending longitudinally of the first and / or second parts are concave.  12. Article according to any one of the preceding claims, characterized in that the first and / or second parts comprise an adhesive and a heat conductive filler.  13. Article according to any one of the preceding claims, characterized in that the first and / or second parts comprise a material having a Brookfield HBT viscosity at 160 C of between 1 and 150 Pa.s, and / or a softening point TMA T60 between 65 and 105 C.  14. Article according to any one of the preceding claims, characterized in that the first and second parts are joined together along longitudinal edges of these parts, so that surfaces (10, 11) of each part can be abutted with each other.  15. Article according to claim 14, charac terized in that the first and second parts are made in one piece.  16. Article according to any one of the preceding claims, characterized in that it comprises a retaining layer (13) located on its surfaces (10, 11) extending longitudinally.  17. Article according to claim 16, characterized in that a retaining layer (13) extends around the first and second parts.  18. Article according to one of claims 16 and 17, characterized in that surfaces of the first and second parts are in abutment with one another, and the retaining layer extends between these surfaces in abutment.  19. Article according to claim 18, characterized in that the retaining layer which thus extends is attached to or is made in one piece with a retaining layer which extends around surfaces facing outwards , first and / or second parts.  20. Article according to any one of claims 16 to 19, characterized in that the retaining layer comprises a thin metal sheet.  21. Article according to claim 20, charac terized in that the thin sheet is detachably held on the first and second parts.  22. Article according to any one of the preceding claims, characterized in that it also comprises a tightly adjusted outer packaging.  23. Article according to claim 22, characterized in that the packaging is a vacuum packaging.  24. Set of parts, characterized in that it comprises  (a) a heat shrinkable sleeve; and  (b) an article according to any of  previous claims.  25. Set of parts according to claim 24, characterized in that the sleeve comprises a composite reinforced with fibers.  26. A set of parts according to claim 25, characterized in that the composite can be retracted by virtue of a component with retractable fibers of this composite.  27. Method for forming a leak-tight joint between a heat-shrinkable sleeve and at least two substrates, characterized in that it comprises the steps which consist  (a) to use an article according to which one  conch of claims 1 to 24 and a  heat shrink sleeve  (b) to choose the first part (7), the  second part (8) or the first and  second parts, together, following the  substrate configuration  (c) positioning the sleeve around the  substrates  (d) positioning the first part, the  second part or the first ones and get  conde parties, together, as the case may be,  inside the sleeve and between the  substrates; and  (e) applying heat to soften  the first and / or the second part and  to retract the sleeve to form  the desired seal.  28. The method of claim 26, charac terized in that the substrates comprise telecommunication or power cables.  29. Article capable of forming a leak-tight joint between a heat-shrinkable sleeve and substrates of each of at least two different configurations, characterized in that it comprises  (a) a first part (7) which can be  softened by heat and may be  placed between substrates inside  sleeve; and  (b) a second part (8) which can be  softened by heat, so joined  detachable from the first part and for  before being positioned between subs  trats inside the sleeve  (i) a cross-sectional shape  of the corresponding first part  to a first configuration of  derivation and a sectional shape  transverse of the second part  corresponding to a second con  derivation figuration; and or  (ii) the cross-sectional shape of  the first part corresponding to  the first configuration  vation and shape in section  transverse of the first and  conde parties, set, correspon  in the second configuration of  bypass; and  (c) a retaining layer (13) on sur  faces extending longitudinally from  first and / or second parts.  30. Article according to claim 29, charac terized in that a retaining layer extends around the first and second parts.  31. Article according to one of claims 29 and 30, characterized in that the first and second parts are joined together along edges extending longitudinally of these parts.  32. Article according to any one of claims 29, 30 and 31, characterized in that surfaces (10, 11) of the first and second parts are in abutment with each other, and in that the layer of restraint extends between these abutting surfaces.