Note: Descriptions are shown in the official language in which they were submitted.
~:~S6~1~7
This invention relates to clips, suitable for use
with heat-recoverable articles, especially their use in
the insulation and protection of substrates such as
supply lines. ~.
Heat-recoverable articles, especially heat-
shrinkable articles, are now widely used in many areas
where insulation, sealing and encapsulation are
required. Usually these articles recovex, on heatlng,
towards an original shape from which they have previously
been deformed, but the term "heat-recoverable", as used
herein, also includes an article which, on heating,
adopts a new configuration, even if it has not been
previously deformed,
In their most common form, such articles com-
prise a heat-shrinkable sleeve made from a polymeric
material exhibiting the property of elastic or plastic
memory as described, for example, in U ~. Patents
2,027,962, 3,0j36,242 and 3,597,372. As is made clear
in, for example, U S. Patent ~,027,962, the original
dimensionally heat-stable form may be a transient form
in a continuous process in which, for example, an
extruded tube is expanded, whilst hot, to a dimen-
siGnally heat-unstable form but, in other applications,
a preformed dimensionally heat stable article is deformed
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to a dimensionally heat unstable form in a separate
stage.
In other articles, as described, for e~ample, in
British Patent 1,440,524, an elastomeric member such as
an outer tubular member is held in a stretched state by
a second member, such as an inner tubular member, which,
upon heating, weakens and thus allows the elastomeric
member to recover.
~eat-shrinkable sleeves find many applications,
especially in the connection and termination of wires,
cables and pipes. However, there are other applications
where it is desirable to provide a connecting, ins~lating
or protective heat-recoverable member ~or elongated
objects such as cables and pipes where the ends are not
accessible or, if they are accessible, where i~ is
undesirable to disconnect or otherwise displace them
For such applications so-called "wrap-around" sleeves
have been developed. Basically these are heat-
recoverable sheets which can be wrapped round the
substrate to form a generally tubular shape and which,
in general, are pr~vided with fastening means for
holding them in the wrapped-up configuration during
recovery. Typically such fastening means are mechanical
in nature and comprise, for example, rigld clamps, pins
or channel members which co-operate with suitable shaped
moulded or extruded protuberances adjacent to the over-
lapping edges of the heat-recoverable sheet Various
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types of fastening means are described, for example, in
U S Patent 3,379,218 and British Patents 1,155,470,
1,211,9~8 and 1,346,479, In other applications, however,
the sheet may be held in the wrapped-up configuration
during recovery by means of an adhesive which may, in
some cases, be applied on site.
Heat-recoverable sleeves and wrap-around sleeves
have been successfully employed in many fields of
application However, problems may arise when two or
more substrates such as supply lines, for example
cables or pipes, have to be sealed at one position,
This pxoblem, which is known as "branch-off", may
occur, for example, at the outlet of a heat-recoverable
part. Amongst areas in which this problem is typically
encountered there may especially be mentioned the out-
lets of the splice cases described and claimed in
British Patent 1,431,167, the feed-through devices
described and claimed in
- 3a -
British Patent 1 245 119 and the duct seal devices
described and claimed in Canadian Patent No. 1 100,156.
One effective solution for tubular sleeves has
been to use moulded heat-shrinkable parts provided
with preformed outlets for the individual supply lines.
However, in general such moulded parts have to be made
to suit a specific ap~lication. Their versatility
has been ~-mproved by the use o~ end caps which seal
outlets which are not needed in a specific operation,
as described and claimed in German Offenlegungsschrift
2 748 383, but they are none~heless expensive and
thus their use becomes economically infeasible in
many routine applications.
Another, less expensive, solution which has
frequently been employed is to use mastic tape to seal
the gap between the supply lines so that, on recove~y,
a proper encapsulation is formed at the end of the
heat-recoverable part. However, the use of such tape
requires skill on the part of the installer and the
method is not applicable to large parts. In addition
the mastic may degrade the overall performance of pro-
ducts with an inner lining or coating of a hot-melt
adhesive.
The present invention is based on the sur-
prising discovery that by the use of a certain nG-~el
type of clip an effective branch-off at the end o
a heat-recoverable part can be obtained,
Accordingly, the present invention provides a
clip which comprises two or more outer elongate legs
and at least one inner elongate leg, at least part
of the surface of the inner leg being provided wi.h
a heat-activatable adhesive or sealant thereon the
legs being so arranged that the clip can be positioned
on the open end of a heat shrinkable sleeve wqth t~e
outer legs outside the sleeve and the inner leg
inside the sleeve, so as to form at lea~ two texminal
conduits capable of receiving elongate substrates.
Using the clip, a branch-off seal may be ma~e
between a heat-shrinkable sleeve alnd at least two
substrates such as supply lines, by the steps of
(a) positioning the clip over the open end o,
the sleeve, as specified above,
(b) positioning the substrates within t~e
conduits, and
(c) applyi.ng heat so as to effect shrinkage
and to form the desired seal.
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.. _ , .. . . .. . . . . .. .. . .. . .. . . . . . . ..
It will be appreciated that steps (a) and (b)
may be effected in any order or simultaneously. For
example in many cases the clip will be pushed into
place after the sleeve has been positioned about
the substratesO
It is surprising that a clip constructed
according to the invention does not "milk-off"
during the recovery involved in step (c) above.
Of course the clip must be sufficiently long
especially if the substrates are large~ut a suit-
able length can readily be ascertained by simple
tests and resistance against milk-off can be
increased, if desired, by providing saw-tooth or
sinusoidal surfaces on the legs of the clip but
in general this will not be necessary.
~$~
Another way in which milk off can be avoided is to
apply heat to the clip and the heat-recoverable material
in the vicinity thereof before effecting total recovery
This local heating step results in a local increase in
thickness of the heat~recoverable material and enhances
the gripping action of the clip. In addition, if, as
in preferred embodiments, the sleeve or wrap-around
sleeve is provided with an inner coating of an adhesive,
the adhesive flows and thus ensures that a satisfactory
bond is formed in the vicinity of the clip prior to
recovery about the substrates. Such a local heating
step may advantageously be employed with all forms of
clip used in the present invention,
In further preferred embodiments of the present
invention, as described in more detail hereinafter, the
clip itself is constructed so as to obviate the pro-
blem of milk-off and may, for this purpose, be adjust-
able so as to conform to the requirements of any
situatlon,
The clip used in the present invention is
advantageously made from a thermally conductive
material and/or is so constructed that it facilitates
the application of heat to the heat-recoverable material
in its vicinity (for example, it may be constructed as
described and claimed in German Offenlegungsschrift
2756021). However, in other instances, the heat-
recoverable sleeve may be provided with internal or
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. . .
~L~L5~ f
self-contained heating means,in which case the clip may
be made from a non-thermally conductive material.
For this and other reasons the clip is preferably
made from a metal including, for example, steel, copper,
brass, beryllium copper, and, especially, aluminium.
An aluminium clip may be made, for example by mould
injection possibly followed by a deburring operation.
In many applications it will be desirable to protect
the clip against corrosion, for example, an aluminium
clip is preferably given a black anodization treatment
or is provided with a chromate layer which may itself
be protected against mechanical damage by, for example,
an epoxy resin coating. Such a coating may further
provide electrical insulation, for example where two
lead-jacketed cables are involvecl.
The significance of the function of the clip in
the transference of heat to and away from the heat-
recoverable material and adhesive in its vicinity is
a factor not appreciated in the prior art. Thus,
whilst Belgian Patent 833,016 mentions that a clip
may be made from metal, it also mentions many other
non-thermally conductive materials, such as plastics
which would not, in general, be suitable in the
present invention, its preferred material being a
25 glass filled polyamide. ~erman OS 2,~13,623 does not
mention the material -from which the clip is made.
-- 8 --
In certain applications, the metal of the clip may
be a memory alloy, for example one of the nickel-
titanium alloys described in U.S. Patents 3,174,851,
3,351,463, 3,753,700 and 3,759,552 or a beta-brass
alloy as descxibed in U.S. Patents 3,783,037 and
4,019,925. In such instances the clip itself may be
heat-recoverable so that the legs of the clip move
towards each other when the assembly is heated to effect
shrinkage of the sleeve. (Alternatively, the clip may
be heat-recovered before or after said step.) Pre~
conditioned memory alloys, especially beta-brass alloys,
are preferred for use in this aspect of the present
invention. Such alloys and methods`for preconditioning
them are described and claimed in U.S. Patents 4,036,669,
4,06~,752 and 4,095,999.
In other embodiments the clip may be made from a
resilient metal such as spring steel or beryllium
copper and may exert resilient forces to enhance the
seal formed. Thus resiliently deformed outer legs may
be "held out" for example by hot melt adhesive so that
they spring together on heating.
It will be appreciated that the configuration of the
clip may be varied from application to application. For
example, in some applications it may be necessary to
form more than two outlets at the end of the heat-
recoverable component. This may be done by providlng
two or moxe clips between the outlets or, in another
_ 9 _
arrangement, a single clip may be employed. These, and
other configurations, fall within the scope of the
present invention.
In one especially preferred embodiment of the
present invention the clip is formed as a trident and
the central leg of the trident passes into the heat-
recoverable sleeve whilst at least one of the outer legs
passes outside it. In this way a layer of heat-
recoverable material is pinched between the central leg
and the outer leg. In such a clip the inner surfaces
of the outer legs preferably taper inwardly, so that
the gap between the outer legs is greater at the open
end of the clip than at the base of the gap. The
surfaces of the central leg are also preferably tapered
so that they run substantially parallel with the inner
surfaces of the outer legs~ Such an arrangement
facilitates the positioning of the clip on the sleeve,
which is especially useful for large diameter sleeves,
and, once the clip is positioned in the heat-recoverable
sleeve, milkin~-off becomes practically impossible,
especially after recovery. It will be appreciated that
with such a clip the inner surfaces of the heat-
recoverable sleeve do not come into contact in the
vicinity of the clip and the central leg of the clip
acts to separate the two conduits which are formed. For
this reason the central leg is preferably provided on
each side with a layer of hot-melt adhesive or another
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. :. ,
heat-activatable sealant, which ~lows during recovery
to seal the gap between the conduits and thus ensures
that the substrates within the conduits do not come
into contact.
he sides of the central leg are, therefore,
preferably roughened or contoured to facilitate adhesion
and, also, to ensure the adhesive xemains in the area
of the clip on heating ~n especially preferred clip
has a waffled pattern on the surfaces of the central
leg.
The outer legs of the clip are preferabl~ pro~
vided with a thermochromic indicator. The reason for
this is that when heat is applied to the clip, there
may be a temperature di~ferent o~ as much as 20C between
the outer legs and the central leg. The use of a
thermochromic indicator (such as, for example, a system
using the melting of white polypropylene powder in a
suitable binder) ensures that the operator applies
sufficient heat to cause the hot--melt adhesive on the
central leg to melt and flow.
The clip may, of course, be provided with other
means for indicating that a desired temperature has been
reached. For example, a resilient member such as a
spring having an indicator element attached thereto,
may be held in a biased position by a hot-melt adhesive
so that, when the adhesive melts, the spring resiliently
recovers causing the indicator element to move and thus
6~t~
signify that the desired temperature has been achieved.
Similarly, ~he clip may be provided with means for
indicating that pressure seal has been safely achieved.
In one preferred embodiment means are provided for
indicating bo~h that the desired temperature has been
achieved and that there are no leaks in the seal at the
outlet(s) of, for example, a pressurized splice case.
In such an ernbodiment an indicator element may be held
in a fixed position by a hot-melt adhesive but may be
caused to move when the adhesive melts by the pressure
built up inside the sealed joint, if the indicator does
not move, either the adhesive has failed to melt, i.e.,
the required temperature has not been reached, or else
the pressure has failed to reach the required level
because of a leak in the seal formed on recovery. In
a simple device of this sort, the hot-melt adhesive
(or another thermofusible material) may itself act as
the indicator, being extruded from the clip when the
pressure builds up inside the joint.
In certain applications, especially in the formation
of branch-offs from pressurized splice cases and/or with
cables of 30 mm diameter or more (e.g. from 35 to 80 mm),
it may be advantageous for the inner edges of both outer
legs and edges of the central leg to lie in a mutually
parallel arrangement.
However, in many applications, as described before,
it will be preferable for the inner edges of the outer
legs and the edges of the central leg to taper inwardly
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'7
towards the closed base of the clip. Such a clip has
certain advantages. First of all, the tapering of the
inner edges of the outer legs and the edges of the
central leg provides two sloping channels, so that when
the clip is slipped on to the sleeve it is virtually
locked in position. It will be appreciated, however,
that once again, on shrinkage the heat-recoverable
material thickens and further tightens the clip to the
sleeve Another advantage is that by correct choice
of the angle defined by the outer legs and correct
choice of the maximum width of the central leg, it is
possible to tailor the clip to conform wi~h the sub-
strates, In this respect it may also be preferable ~or
the central leg to be longer than the outer legs. In
this way the required seal between the branch conduits
formed is facilitated.
Other ways in which the clip may be shaped to con-
form with the substrates and thus, for example, to
reduce the risk of adhesion failure are to provide
concave outer surfaces on the central leg of the clip
to accommodate small sized cables (e.g. of from about
8 mm to 35 mm diameter) and to provide a central leg
of lesser thickness, at least over part of its length,
to accommodate large size cables (e.g. of diameter
greater than about 30 mm, typically from 35 to 80 mm),
Once the hot-melt adhesive has flowed to fill the
gap between the conduits, it will not be possible to
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17
remove the clip without causing the sleeve to become
disbonded from the substrates Thus there is no danger
of the clip slippillg off and leaving the branch-off
division liable to failure by peel.
It will be appreciated that the trident cllp may
be adapted to multi-outlet branch-off arrangements in
the same way as the simple U-clip and, in some instances,
it is even possible to construct a clip which is adjust-
able according to the direction required by the conduits.
In some multi-outlet clips it may be appropriate to
form the central leg as a solid or hollow generally
conical member co-operating with a plurality of outer
legs. Similarly, as in the simple U-clips, the base
of the gaps in the trident clip may be cut away to
provide extra strength, in which case the thickness of
the adhesive coating must be such as to provide suffi-
cient material to fill these gaps on recovery A
typical range of hot-melt adhesive thickness on each
side of the central leg is from 2 to 5 mm, but the
thickness may, if desired, be varied along the len~th
of the leg, it being greater at the open end of the
clip than at the base. As mentioned above, the surface
of the central leg is preferably rough or is corrugated
or waffled to provide a seal for the adhesive and also
to ensure that, on recovery, adhesive is not forced
away from the central leg but, rather, is forced into
the surface irregularities In these and other
- 14 -
embodiments of the present invention it may beadvantageous to pigment the hot-melt adhesive so that
its diffusion into and coalescence with the clear hot-
melt lining of the sleeve may be noted to indicate that
sufficient heating has occurr2d.
A further design modification concerning the pro-
vision of a hot-melt adhesive layer on the central leg
is to provide it with one or more upper and/or lower
longitudinal ridges over at least part of the length
of the central leg to enhance the initial push-fit
force of the clip on a sleeve and thereby to facilitate
secure positioning of the clip on relatively thin
expanded coated sleeves.
The strength of the clips used in the present
invention is enhanced when they are made from flat
stock, that is to say, when the width of the legs
extending above and below the heat-recoverable sleeve
is greater than their thickness in contact with the
sleeve. Typically, the width will be from 1.5 to 3
times the thic~ness.
In some especially preferred embodiments of the
present invention, one or more of the legs of the clip,
espcially khe central leg, may be used to fulfil a
secondary function. For example, the central leg may
be hollow and act as an inlet or outlet for compressed
air, as in a pressurized splice case, or for jelly,
epoxy resins or foam materials, etc. The leg may, of
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~5~17
course, be provided with a valve for such a purpose.In some of these embodiments the leg may itself act as
a substrate. For example, a branch-off may be made
from a single cable using such a clip specifically to
provide an inlet valve.
In other embodiments, the clip may be provided with
means for ensuring that electrical continuity is main-
tained between, for example, shielded cables positioned
within the conduits. Such means may comprise, for
example, jaws or similar members positioned on one or
more of the legs of the clip and adapted to receive and
grip tags cut from or attached to the shielding of the
cables.
Whilst, in general, it is not contemplated that
the clips will be used in conjunction with other members
it is possible that in some cases it may be advantageous
to provide a co-operating insert member and/or to use
the method of the present invention in conjunction with
other methods including, for example, the mastic tape
method referred to above. In certain instances it may
also be advantageous to use the clip to connect the
heat-recoverable sheet material to anothe. component.
For example, a plurality of clips may be used to form
branch-offs around a distribution box or to form a
large number of branch-offs from a single splice case
by using a further heat-recoverable conponent such as
a cap positioned internally of the heat-shrinkable
- 16 -
. . .
sleeve. Such embodiments are explained in more detailhereinafter.
It will be appreciated that the heat-recoverable
sleeve may be a wrap-around sleeve and/or may comprise
a closed end, l.e. it may be an end-cap, or may be part
of a larger article, for example a larger heat-
recoverable article, and that, in any case, the present
invention is not in any way limited to the size or con-
figuration of the heat-recoverable componentO For
example, the heat-shrinkable sleeve may be formed from
two (or more) sheets of heat-recoverable material. All
that is necessary for the purposes of the present
invention is that the heat-shrinkable component has a
hollow terminal portion within which the substrates are
positioned.
When the clips are used in conjunction with a wrap-
around sleeve it may be advantageous to form the clip so
that it can co-operate with the fastening means of the
wrap-around device, In some instances it may even be
possible to form the clip as part of said fastening
means.
Whilst the clip will be held securely in position
by the heat-recoverable sleeve and, in some embodiments,
may be made adjustable so that the gap between the legs
can be altered accoxding to the thickness of the sleeve
so as further to facilitate the formation of a secure
grip upon recovery, it may, in certain applications, be
- 17 -
advantageous to provide the clip with one or moremembers which co-operate with the substrates externally
of the heat-recoverable sleeve so as to facilitate the
correct positioning of the clip. For example a clip
may be provided with a ring member which is adapted to
surround a pressure transducer externally of a heat-
shrinkable splice case joint In another embodiment a
clip may be provided with metal straps which can be
fastened around heavy cables as they leave so as to
provide strain relief for the jointO
The heat-recoverable material may be any of the
polymers known from the art to be useful for the
production of heat-recoverable articles. Generally
the sheet material will be of constant composition
throughout, however laminates of two different polymers
bonded or fused together may be used in certain
instances. Amongst suitable polymers there may be
mentioned, for example, polyolefins, especially poly-
ethylene, copolyrners o~ ethylene and vinyl acetate,
copolyrners of ethylene and ethyl acrylate, chlorinated
and fluorinated polymers, especially polyvinyl chloride,
polyvinylidene fluoride and polymers incorporating
units from vinylidene fluoride, hexafluoroethylene and
chlorotrifluoroethylene, and rubbers such as ethylene/
propylene rubber, chlorinated rubbers, e.g. Neoprene,
and silicone rubbers which may be used in a blend with
a crystalline or glassy polymer such as an olefin
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~.~, ' .
~5~ 7
polymer. All of the above materials m~y, if desired,be cross-linked for example by irradiation and/or
chemical means~
As mentioned above,-the internal surface of the
heat-recoverable component will, in general, be pro-
vided with a coating of an adhesive or a sealant such
as a hot-melt adhesive or a mastic. Especially suit-
able hot-melt adhesives include, for example, poly-
amides, ethylene/vinyl acetates copolymers and
te~polymers (with or without incorporated waxes) and
polyesters. Such materials are described, for example.
in British Patent 1,440,810 and German OS 2,709,717.
Also suitable are curable adhesives which melt and
flow on heating but which will not afterwards be hot-
meltable~ There may also be mentioned epoxy xesins andconventional mastics such, for example, as those based
on butyl and isobutylene rubbers modified with suitable
materials known in the art. Obviously the use or
otherwise of such materials and their type, if chosen,
will depend upon the particular requirements in any
given case.
In most applications the force exerted on the clip
will lie in the range of from 5 to 15 kg, depending on
the diameter of the substrate and the wall thickness
and the degree of unresolved recovery of the sleeve.
It will be appreciated in this latter respect that, as
compared with the mastic tape method, the heat-
recoverab~e sleeve will be required to shrink less and,
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~ ~5~
therefo~e, have a smaller expansion ratio, becausethe clip forces the sleeve to conform to the circum-
stances of the cables in the central region, whereas
in the mastic tape method the sleeve does not come into
contact with the cables in this region. Of course, the
degree of expansion required for the sleeve is lower
when a trident clip is used than when z simple U-clip
is employed.
It will be appreciated that the present invention
provides a very simple method of making a satisfactory
branch-off, thus removing any need for skillful instal-
lation and providing a consequent decrease in cost. The
elongate legs of the clip ensure that a seal is formed
from the edge of the heat-recoverable materials to the
- 15 ends of said legs, thereby satisfactorily separating the
substrates throughout that region.
- l9a -
Vario~s embodiments of the present invention ~
now be described by way of example only with reference
to the accompanying drawings in which:
Figures 1 to 6 while not illustrating a clip con-
structed according to the claimed invention illllstratea clip suitable for use in the method which is the
subject-matter of our copending application ~o. 319 306
for which method the clips of the present invention are
also and especially suitable~ These figures accord-
ingly are illustrative of the use to which clips o~ thepresent invention may be put.
Figure 7 shows a preferred form of trident clip in
accordance with the present invention,
Figure 8 shows the use of the t.rident clip in
forming a branch~off,
Figures 9a and 9b show a modified trident clip
designed to form a 3-way branch-off,
Figure 10 illustrates a further modification for
forming an asymmetric branch-off,
Figure 11 illustrates a clip for forming a ~-way
branch-off,
Figure 12 illustrates a clip forming an 8-wrcy
branch-off,
Figures 13a and 13b illustrate an adaptable clip
for forming a 3-way branch~off,
Figures 14a and 14b illustrate a clip which can
act as an inlet valve,
- 20 -
~igures 15a and 15b illustrate the use of a clip
to provide a branch-off for an inlet or outlet valve;
Figures 16a and 16b show a preferred form of trident
clip,
Figures 17a to 17e and 18a to 18c show the use of a
form of clip not constructed in accordance with the inven-
tion but which like that of Figs. 1 to 6 is used in a
method in which the clip of th~ present invention may k~
used i.e., in conjunction with a heat-recoverable sleeve
and a distribution box to form a multi-outlet termination,
Figures 18a to 18c show a similar multi-outlet
termination,
Figure 19 shows a clip provided with a temperature
indication device,
Figures 20a to 20c show a cli.p provided with a
combined pressure and temperature indicatio~ device,
Figures 21a to 21c illustrate the use of a clip
provided with means for facilitating electrical continuity,
Figures 22a and 22b show a clip suitable for use with
20 a pressure transducer,
Figures 23a and 23b show a clip designed to provide
strain relief to a formed joint'
Figures 24a and 24b show a self-adjusting clip for
use in the present invention,
Figure 25 shows a further form of clip for use
with a pressurized splice case joint'
Figures26a and 26b show a clip for use with small
diameter cables, and
Figures 27a to 27c show a clip for use with
larger diameter cable 5 .
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Referring now to the drawings, Figures la ar~ 1~
show an aluminium clip 1 which ls for use in the ~e-rod
of Application No. 319,~06~ It will be seen tha. ~he
width of the legs 2 and 3 is greater than their ~hic~ess.
In addition the base of the gap between the legs 2 and 3
has been cut away at 4 for added strength. Such a
strengthening procedure is also applicable to clips c~n-
structed according to the present invention. Typlcal
dimensions or the clip are as follows: length 6A mm'
width 24 mm, length of legs 52 mm, width of arms 10 mm,
thickness of arms 5 mm, gap between arms 4 mm.
Figure 2 shows how the clip 1 may be used to f~
a branch-off for two telecommunication cables 5 and 6
passing into a splice case 7 of the XAGA-type as described
and claimed in British Patent 1,431,167, The asse~bly is
shown after recovery.
Figure 3 (which is a section), shows the use cf iwo
such clips to form a 3-way branch-off on a similar product.
~he clips 1 operate to space the cables 8 9 and 10 apart
and at the same time, ensure that the cables are separated
by hot-melt adhesive. This is most important if the
cables are to be kept separate during subsequent llexing
and bending. This has been a problem with the m2stic
tape method where the mastic has become squeezec ~ut and
created leaXage paths between the cable surfaces
Figure 4 shows the application of a single clip 1
to a duct seal 11 of the type described and claimed in
German Offenlegungsschrift 2,748,894, As can be seen,
the duct seal is arranged tc conduct multi-wire cables
12 and 13 through a duct (not shown) and is provided
with external flanges 14 for the sealant 15 positioned
be~ween them. On heating these flanges 14 to deform
and the sealant 15 melts and flows so as to seal the
device within the duct.
In Figure 5 there is shown an aluminium clip 16,
which is provided with three leys 17, 18 and 19, which
are arranged symmetrically about the longitudinal access
of the clip, The 1egs are in other respects similar to
those of the clip 1 of Figure 1 and, once again, a
portion of the clip has been cut away at the base of the
gaps between the arms for added strength.
Figure 6 shows how the clip 1~ may be used to form
a 3-way branch-off at the end of a X~GA splice case 20,
As can be seen, one of the branch~off conduits 21
so formed has been caused partially to shrink about a
reinforcing coil and has been provided with an end
cap 23 in accordance with German Offenlegungsschrift
2,748,383. The end cap 23 can be removed when it
becomes necessary to use the feed-through device 22.
In Figure 7 there is shown a trident clip 31
according to the present invention. The inner surfaces
of the outer legs 32 and 33 and the surfaces of the
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central leg 34 are tapered so as to define an angle ~.
The surfaces of the outer legs and the central leg run
substant-ally parallel to form two sloping channels 35
and 36, each of which is cut away at the bottom for
increased streng-th by stress distribution.
The central leg 34 is provided on each side with a
hot-melt coating 37 and the surfaces of the outer legs
are provided with a coating 38 of a thermochromic
indicator
10Typical dimensions for the clip are as follows:
thickness, 5 mm' width of central leg, 11 mm decreasing
to 5.5 mm, gap between legs, 1 to 2 mm according to
sleeve material wall thickness.
Figure 8 shows the clip 31 in position on a heat
shrinkable sleeve 39 to form two branch-off conduits 40
and 410 As can be seen, in the recovered position, the
central leg 34 forms a separating barrier between the
conduits.
Figures 9a and 9b show an adapted trident clip 42
~0 deslgned to form a three-way branch-off, the central
leg 43 being formed as a part of Y-shaped cross-section.
Figures 10, 11 and 12 show various clips 44, 45 and
46, respectively, for forming other multi-outlet branch-
offs.
25~igures 13a and 13b shown an ad~ustable three-way
branch-off clip. In this clip two of the outer legs 47
and 48 are rotatably mountable on an extended part of the
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inner leg ~9, whereas outer leg 50 is fixed to said
inner leg 49. Such a clip can be adjusted accordlng to
the nature of the bYanch-off required.
In Figure 14a there is shown the use of a trident
clip 51 to provide an inlet for pressurized air within
a cable splice 52. In this embodiment, as shown in
Figure 14a, the central leg 53 of the trident clip 51
is hollow and is provided with a valve 54 and an inlet
55. The central leg 53 of the clip 51 acts as a
substrate in the branch-off from cable 56.
In Figure 15a there is shown how two trident clips
57 and 58 may be employed with a wrap-around splice 59
to form a branch-off inlet and outlet at the ends
thereof. In this case the inlet and outlet are pro-
vided wlth separate devices 60 and 61 (as shown inFigure 15b) which form the substrates in the branch-
off from cables 62 and 63, respectively.
~ igure 16a and 16b show a further form of
preferred trident clip 6~ in accordan~e with the
present invention. This clip 6~ has the preferred
features that the central leg 65 extends beyond the
ends of the outer legs 66 and 67 and that the side
surfaces of the central leg 65 are waffled to provide
a suitable base for adhesive, as discussed previously.
In Figures 17a to 17e there is shown a procedure
by which branch outlets may be formed from a heat-
recoverable sleeve and a further co-operating component
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although the clip illust~ated is not in accordance with
the invention it will be appreciated, from consideration
of Figure 18, that the presently claimed clips could be
used in similar circumstances,
In Figure 17a there is shown a distribution box 68
provided on its external surfaces with hot-melt adhesive
69. This distribution box is designed to distribute
pairs of cables from a large incoming cable to a large
number of outgoing smaller cables.
The adhesive coatings 69 are pre-cut to remove
strips which are slightly wider than the thickness of
the clips 70 (as shown in Figure 17b). The box 68 is
then inserted within a large diameter heat-recoverable
sleeve 71 and the outgoing cables 72 are arranged around
the surface of the distribution box 68. As is shown in
Figures 17c and 17d the clips 70 are then positioned
between the cables 72 and over the external surface of
the heat-recoverable sleeve 71 and the internal surface
of the distribution box 68. The assembly so produced
may then be heated to cause recovery of sleeve 71 and
flow of the adheslve 69 to produce the completed dis-
tribution box shown in Figure 17e, As indicated, some
of the branch-offs may be occupied by devices 73 pro-
vided with caps 74 for future use,
The distribution box 68, preferably made from a
strong thermally conducti,ve metal, may be provided with
grooves on its internal surface to assist location of
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~' .
. ~ , . .
the clips. The heat-recoverable s]eeve 71 may, of course,
be a wrap-around sleeve and may be internally coated to
reduce water vapour penetration. At its other end it is
shrunk about the large incoming cable 75.
The bo~ 68 may have different geometries such as
circular, elliptical, star-shape etc. and various
different forms of clip 70 may be used.
Figures 18a to 18c show a somewhat similar multi-
outlet branch-off arrangement for use with a pressurized
splice case. A3 shown in Figure 18a the splice case 80,
which may be formed from two metal half shells, is
protected and insulated by a wrap-around heat-shrinkable
sleeve18 provided with a conventional fastening means 82.
Ingoing cable 83 is ~o be spliced to form four outlet
cables 84 and, in accordance with the invention, a seal
is formed at the inlet using a trident clip 85 which
provides a conduit for a pressure valve 86. The seal
at the inlet is formed as described previously. At
the outlet there is provided a heat-shrinkable cap 87
which has a hot melt adhesive coating on its external
surface~ As shown, the cap is provided with four
trident clips 88 which may be constructed in accordance
with the present invention. The cap 87 and the clips 88
co-operate with the outlet end of heat-shrinkable sleeve
81 and the arrangement before recovery is shown in
Figure 18b. It will be seen that the cap, the sleeves
and the clips between them form four conduits for the
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`i~t
A,~
out~oing cables 84. When the assembly shown in Figure18b is complete the heat-recoverable sleeve 81 ls caused
to shrink by using a conventional torch and the heat-
shrinkable cap 87 is preferably caused to shrink by
means of a so-called "hot-pack", i.e. a pyrotechnic
type heating device, which is pre-installed within it.
The recovered assembly is shown in Figure 18c.
Such an arrangement is especially useful in the
formation of multi-outlet branch-offs from pressurized
splice cases where the expansion rate of the heat-
recoverable sleeve is kept as low as possible, usually
at about 1.3 in order to keep the wall thickness of the
sleeve to a maximum and to reduce unresolved recovery
to a minimum, thereby obviating the rupture of the
sleeve under pressure.
In Figure l9 there is shown a trident clip, the
central leg 91 of which is provided with a temperature
indication device which comprises an indicator rod 92
positioned within the leg 91 and a load spring which
is held in compression within chamber 9~ by being
embedded in a thermofusible material (not shown).
When the desired temperature is reached the thermo-
fusible material melts an~ the spring 91 recovers
resiliently to move the rod 92 to the position shown
by the dotted lines, thus indicating that the desired
temperature has been reached.
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., ,
L7
Figures 20a to 20c show a clip 100 which is
provided with means for indicating that both a
desired temperature and a desired pressure have been
attained within heat-shrinkable sleeve 101. As shown
in Figure 20b the centxal leg 102 of clip 100 is
provided with a chamber 103 in which is positioned a
ball valve 104, Also positioned within chamber 103
and in a channel 105 which connects the chamber to the
closed end of the clip 100 is a thermofusible
material 106.
The positioning of the clip 100 within a .
pressurized splice case joint 107 is shown in Figure
20c. When the desired temperature is reached the
thermofusible material 10~ melts and, provided that
1~ a correct seal is achieved, the pressure within the
joint 107 causes the ball valve 104 to move along the
chamber 103 thereby forcing a volume of molten thermo~
fusible material out from the end of the clip, the
volume extruded being approximately equal to the
volume originally positioned in chamber 103. The
operator can thus be sure not only that has the
correct temperature been reached but also that there
are no leaks in the seal formed at the joint.
Figures 21a to 21c show a trident clip 110, the
central leg of which is provided on each side with
jaw members 111. These are designed to accommodate
and grip strips 112 cut from the aluminium shielding
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~5~ 7
foil of telecommunication cables 113, as shown in
Figure 21c, and thus ensure electrical continuity
bet~een the cables 113 and electrical bond line 114
which is attached to the central leg of clip 110.
Figures 22a and 22b show a further form of clip
116 and its use in the formation of a joint at the
end of a pressurized splice case provided with a
pressure transducer. As shown, the clip 116 is pro-
vided with a locating ring 117 which is designed to
fit around the pressure transducer container 118. If
desired, the ring 117 could be formed as a cap for the
container 118.
Figures 23a and 23b show trident clip 120 which
is provided with two straps 121 and 122 which are
designed to be fastened around cables 123 and 124,
respectively, a~ they leave a splice joint 125. This
arrangement not only serves properly to locate the
cables and the clip at the joint, but also provides
strain relief to the system and ensures that movement
of the cables externally of the joint does not cause
damage. It is, therefore, especially appropriate for
use with heavy duty cables or service pipes, etc.
In Figures 24a and 24b there is shown clip 130
which is designed so as to be self-adjusting in that
the gaps between the central leg 131 of the external
legs 132 and 133 may vary according to the thickness
of the heat-recoverable sleeve For this purpGSe the
30 -
h~5~7
central leg 131 is constructed from two parts, aU-shaped member 135 being slidably mounted on a
central member 136 and, initially, held in an extruded
position against the force of a tension spring 137,
the whole assembly being embedded in a hot-melt
adhesive 138 to prevent recovery of the tension spring.
~hen, in operation, clip 130 is heated the hot-melt
adhesive 138 fuses and the tension spring recovers
causing the U-shaped member 135 to move along the
central member 136 towards the base of the clip, as
shown by the dotted lines. In doing so the gap
between the legs is reduced, thereby ensuring that the
heat-recoverable sleeve material positioned therein is
firmly gripped.
Figure 25 shows a further form of clip 140 for
use with pressurized splice cases. ~s shown this
clip 140 has three legs of equal length which will, in
general, be longer than the clip shown, for example,
Figure 5. In addition, the width of the central leg
141 is constant throughout its length and is kept as
small as practicable, e.g. at about 5 mm, in order to
facilitate the formation of a good seal between the
heat-recoverable sleeve and the cables in the vicinity
of the clip. Both sides of central leg 141 are
provided with a layer of a hot-melt adhesive.
Finally, in Figures 26 and 27 there are shown two
other advantageous clips for use in the present
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invention. The clip sho~n in Figure 26 is designedfor use with cables of outside diameter from about 8
to about 35 mm, As can be seen most clearly from
Figure 26c, which is a section taken near the open
of the clip, the sides of central leg 151 are concave
in nature to accommodate the cables. In addition the
upper and lower surfaces of the hot-melt adhesive
layer 152 are each provided with two longitudinally
extending ribs 153. As mentioned earlier, the pro-
vision of these ribs enhances the push-fit of the
clip over the sleeve prior to shrinkage.
The clip shown in Figure 27 is designed for
larger cables of outside diameter greater than about
30 mm. In this clip the central leg 161 decreases in
thickness from the closed end to the open end of the
clip in order to accommodate the cables. Once again,
hot-melt adhesive layer 16~ is provided with longi-
tudinal ribs 163 to enhance the positioning of the
clip prior to recovery but in this case the ribs 163
e~tend over only a part of the length of centr~l leg
161 in order to allow facile initial installation of
the clip.
Other modifications and variations falling within
the scope of the present invention will be apparent
to those skilled in the art.
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