Method and assembly kit for forming defined longitudinally watertight sections in wirings comprising a plurality of individual strands and/or cable strands

The invention relates to a method and an assembly kit for forming locally defined longitudinally water-tight sections in a wiring comprising a plurality of conductor strands, individual conductors and/or cable strands for the electric or electronic control of functions. Inserted between the conductor strands of such a wiring is a plastic element containing, or consisting of, a thermoplastic melt adhesive. This plastic element is caused to expand in response to being heated. A section of a heat-shrinkable component is mounted on the exterior of the wiring. Application of heat causes the shrinkable component to tightly contract around the wiring, and the plastic element positioned between the conductor strands to expand. The contraction of the heat-shrinkable component and the expansion of the plastic element result in the generation of pressure forces within the space enclosed by the heat-shrinkable component, whereby the heat-softened melt adhesive is sealingly forced into any existing voids.

The invention relates to a method for forming defined longitudinally 
water-tight sections in wirings comprising a plurality of individual 
strands and/or cable strands. Wirings of this type are mainly used for the 
electric and electronic control of functions. The invention also relates 
to an assembly kit for forming such local sealing sections. 
In various industries, for instance the motor industry, there is frequently 
the problem of forming locally defined longitudinally water-tight sections 
in multiple-component wirings such as cable trees. This problem is 
primarily encountered in the vicinity of soldering terminals and when a 
wiring is passed through a partition, for instance from the engine space 
into the cabin of a vehicle. It is frequently also required to seal a 
wiring in a gas-tight and water-tight manner. If water is permitted to 
flow along the individual strands and/or cable strands of a wiring system, 
it causes severe corrosion at soldering terminals. If such longitudinally 
flowing water enters a plug connection it may lead to the occurrence of 
shortcircuits. This may result in heavy accidents in the case for instance 
of anti-locking break control systems. In the absence of a longitudinally 
water-tight sealing system at the location for instance of the passage of 
a wiring from the motor space into the central processing units of a motor 
vehicle, moisture may be permitted to enter said sensitive units. 
It is therefore an object of the invention to provide a method permitting 
locally defined sections of wiring systems to be sealed against the 
longitudinal flow of water. 
This object is attained by the invention as defined in claim 1. 
The assembly kit according to the invention permits the method according to 
the invention to be implemented and enables existing wirings to be locally 
sealed. 
According to the invention, an assembly kit of this type consists of a 
heat-shrinkable component adapted to re-shrink to a reduced diameter in 
response to being heated, and a core made of a material adapted to expand 
temporarily or permanently to an enlarged cross-section in response to 
being heated and containing, or consisting of, a thermoplastic melt 
adhesive, said shrinkable component and said expandable core material 
defining a space therebetween, preferably an annular space for receiving 
individual strands or cable strands therein. 
The technical progress to be achieved by the invention (method and assembly 
kit) results from the fact that after the expanding plastic core element 
has been embedded, the heat-shrinkable component has been mounted and the 
heat treatment has been carried out, the individual strands, or cable 
strands are sealed in a longitudinally water-tight (gas-tight) manner both 
between one another and over the entire cross-sectional area of the 
wiring, since the thermoplastic melt adhesive has penetrated into all of 
the voids between individual strands and/or cable strands as a result of 
the pressure exerted on the wiring by the heat-shrinkable component as it 
is being tightly shrunk thereabout, and of the pressure exerted by the 
expanding core element from within the wiring. 
In performing the method according to the invention, at least one plastic 
element adapted to expand to an enlarged cross-sectional shape in response 
to a heat treatment and containing, or consisting of, a thermoplastic melt 
adhesive or a (cross-linkable) plastic material, respectively, is embedded 
between the conductor strands of the wiring. It is of decisive importance 
that the application of heat causes the plastic element to increase its 
diameter and to create an internal melt flow penetrating into the spaces 
between the conductor strands of the wiring so as to completely fill these 
spaces. The volume increase of the plastic element to be embedded 
resulting from the application of heat will of course result in a pressure 
increase within the wiring, whereby the melt adhesive is forced into the 
spaces to be sealed. It is obvious that the sealing system according to 
the invention may be applied to one or several locally defined sections of 
a wiring of extended length, but that it is also possible to seal wiring 
sections of considerable length in a longitudinally water- and gas-tight 
manner by the method according to the invention. 
In a preferred embodiment of the invention, the heat-shrinkable component 
surrounding the wiring at the location to be sealed has its interior 
surface coated with a melt adhesive. The heat treatment causes this melt 
adhesive coating to melt and to be forced into the spaces of the section 
to be sealed between the separate conductor strands by the two 
above-mentioned pressure components (internal and external). 
It is to be emphasized that the pressure forces acting on the section to be 
sealed from its interior and its exterior are due to the provision, 
respectively, that in the case of the exteriorly acting pressure a 
previously radially expanded shrinkable component is caused to re-shrink 
to its smaller original diameter by the application of heat, and that in 
the case of the internally acting pressure the embedded plastic element 
exerts an outwards directed pressure from within as a result of its 
expansion, i.e. as a result of the temporary or permanent increase of its 
cross-sectional area in response to the heat treatment. As already 
mentioned, these two oppositely directly pressure components are effective 
to force the thermoplastic melt adhesive into the spaces to be filled 
after the adhesive has been softened by the heat treatment. 
The plastic elements to be embedded according to the invention may be of 
various types, namely, 
(a) elements consisting of a core made of a cross-linkable plastic material 
and an outer layer of a thermoplastic melt adhesive extruded on the core, 
(b) elements not provided with a core of a cross-linkable plastic material 
and consisting solely of a thermoplastic melt adhesive of a type causing 
the plastic element, after having been pre-stretched in its longitudinal 
direction, to re-assume its original (nonstretched) configuration, 
accompanied by an increase of its diameter, in response to a subsequent 
heat treatment, and 
(c) elements substantially consisting of a heat-responsive adhesive adapted 
to expand, accompanied by the formation of foam, in response to the 
application of heat, to thereby penetrate into any voids encountered in 
the section to be sealed. 
Further preferred embodiments of the invention are set forth in the 
subclaims.

In the following description, the term "conductor strand" is used as a 
collective term for "individual strands and/or cable strands". 
The plastic element shown in FIG. 1 comprises a core 1 made of a 
cross-linkable plastic material, for instance a suitable polyethylene 
composition, and an outer layer 2 made of a melt adhesive extruded about 
core 1. FIG. 6 shows a plastic element 1, 2 of this type embedded in a 
conductor lane comprising a plurality of conductor strands 10, in the 
state prior to a heat treatment. FIG. 11 depicts the state after the heat 
treatment has been carried out. 
After the thermoplastic melt adhesive 2 has been extruded about core 1 
consisting of a cross-linkable plastic material, the system formed by 
these two components is at least partially cross-linked, to which purpose 
the material is exposed to beta or gamma radiation or subjected to a 
chemical treatment, whereby the cross-linking of the core material, for 
instance polyethylene, is brought about Depending on additives contained 
in melt adhesive 2, this treatment may also result in the outer layer 
material being cross-linked to a suitable degree. 
After the core and optionally also the outer layer material, has or have 
been thus cross-linked, the element shown in FIG. 1 is stretched in the 
direction of its longitudinal axis. This stretching step is preferably 
carried out at a stretching rate of 2:1 or 3:1 or 4:1, the relationship 
between the outer diameter of the melt adhesive outer layer 2 and the 
outer diameter of the (polyethylene) core 1 being preferably 2:1 or 3:1 or 
4:1. 
In the embodiment shown in FIG. 1, core 1 is in the shape of a rod of 
circular cross-sectional shape. The melt adhesive outer layer 2 extruded 
thereabout is therefore of circular annular cross-sectional shape. 
For locally sealing a multiple-conductor wiring a plastic element is 
(partially) cross-linked and longitudinally stretched as explained above, 
and is then positioned in the wiring preferably along the longitudinal 
axis thereof, so that the conductor strands 10 are evenly distributed 
around the outer surface of the outer melt adhesive layer 2 as shown in 
FIG. 6. Subsequently a radially pre-stretched and optionally cross-linked 
heat-shrinkable component is mounted on the wiring system. In the course 
of a subsequent heat treatment, which according to the present invention 
is carried out at a temperature of about 80.degree. to 155.degree. C., 
measured within the sealing portion the thermoplastic melt adhesive 2 is 
activated, and the radially pre-stretched heat-shrinkable component is 
caused to contract towards its original smaller diameter. The heat 
treatment further causes the longitudinally stretched core 1 to contract 
and to thereby expand to its original larger diameter, so that there 
occurs a pressure rise in the space between heat-shrinkable component and 
plastic element 1,2, as a result of which the softened melt adhesive 2 is 
forced into the spaces between the conductor strands 10. 
In the embodiment of FIG. 2, the plastic element does not include an inner 
core but consists solely of a thermoplastic melt adhesive. This melt 
adhesive is of such a composition, or cross-linked in such a manner, that 
the longitudinally pre-stretched element will contract in response to 
being subsequently heated, accompanied by a temporary or permanent 
enlargement of its cross-sectional shape. The employed melt adhesive is 
preferably of a type in which the heat treatment induces the formation of 
foam in the form of closed pores or cells. 
In practical use the plastic element shown in FIG. 2 is embedded in the 
section of a conductor strand bundle to be sealed in the manner described 
with reference to FIG. 1, and subjected to a heat treatment after a heat 
shrinkable component section has been mounted also in the manner described 
with reference to FIG. 1. Since the heat treatment causes the 
pre-stretched plastic element of FIG. 2 to return to the shape it had 
prior to the pre-stretching step, the diameter of the plastic element 
expands during the heat treatment, so that an outwards directed pressure 
is created within the section of the wiring surrounded by heat-shrinkable 
component 4, as a result of which the softened melt adhesive is forced 
into the spaces between the conductor strands 10. 
The pre-stretching of the plastic element of FIG. 2 is preferably carried 
out as described with reference to FIG. 1, i.e. at a stretching ratio of 
2:1 or 3:1 or 4:1. Foaming melt adhesives are not pre-stretched. 
FIG. 7 shows the manner in which a core-less plastic element of the type 
shown in FIG. 2 is positioned within a bundle of conductor strands along 
the longitudinal axis thereof. The individual conductor strands 10 are 
disposed between melt adhesive element 2 and the surrounding 
heat-shrinkable component 4. FIG. 7 shows the assembly of heat-shrinkable 
component 4 conductor strands 10 and centrally located plastic element 2 
prior to the finishing heat treatment. FIGS. 3 and 4 likewise show 
coreless plastic elements made of a cross-linkable thermoplastic melt 
adhesive or of a heat-responsive temporary or permanent foam-forming melt 
adhesive. The plastic element shown in FIG. 3 has a cross-sectional 
configuration similar to the shape of a maltese cross, including four 
pockets in the form of grooves or flutes extending between the arms of the 
cross in the longitudinal direction of the element. 
Each of these pockets is adapted to receive one or several conductor 
strands therein. The plastic element may also suitably be of star-shaped 
cross-sectional configuation. FIG. 8 shows a cross-shaped plastic element 
of the type shown in FIG. 3 positioned along the longitudinal axis of a 
multiple-strand wiring with two conductor strands 10 being disposed in 
each of the four pockets. The conductor strands received in the four 
pockets are surrounded by a plurality of further conductor strands, as 
shown in FIG. 8. 
The plastic element shown in FIG. 4 is formed as a hollow member comprising 
a plurality of longitudinally extending pockets for the accommodation of 
individual conductor strands therein formed on its outer surface. The 
plastic element shown in FIG. 4 consists of a cross-linkable thermoplastic 
melt adhesive or of a heat-responsive foam-forming melt adhesive and may 
be cross-linked and longitudinallly pre-stretched prior to use in the same 
manner as described with reference to FIGS. 2 and 3. Its should be noted 
that the receiving pockets are preferably dimensioned so that no more that 
two conductor strands can be accommodated therein. 
The employ of the plastic element (melt adhesive element) shown in FIG. 4 
is illustrated in FIG. 9. For instance the plastic element of FIG. 4 is 
used for longitudinally sealing in a water- and gas-tight manner wirings 
including a great number of conductor strands. In the embodiment depicted 
in FIG. 9, eight conductor strands are disposed around a melt adhesive 
core 2 positioned along the longitudinal axis of the wiring shown. These 
eight conductor strands are surrounded by a hollow member of the type 
shown in FIG. 4, with the plurality of pockets extending in its 
longitudinal direction accommodating a plurality of further conductor 
strands. This hollow member is designated by the reference designation S1 
in FIG. 9. Hollow member S1 and the conductor strands retained thereon are 
surrounded by another hollow member of the type shown in FIG. 4. The 
hollow member is designated by the reference designation S2 in FIG. 9 and 
has a larger diameter than hollow member S1. As in all of the previously 
described embodiments, a heat-shrinkable component 4 is mounted at least 
on the outermost conductor strand array. An arrangement of the type 
depicted in FIG. 9 is preferably assembled in successive steps by the use 
of intermediate heat-shrinkable components not shown in FIG. 9. 
As the assembly shown in FIG. 9 is subjected to a heat treatment, the heat 
activation of the melt adhesive elements 2, S1, S2 made of a pre-stretched 
or foam-generating material and the re-contraction of the outer 
heat-shrinkable component 4 and the preferably employed (not shown) 
intermediate shrink component results in a substantial pressure rise in 
the respective wiring section, as a result of which the melt adhesive 
softened by this head treatment is forced into all of the voids within the 
heat-shrinkable components. The state of the assembly of FIG. 9 after heat 
treatment is depicted in FIG. 11. The intermediate shrinkable components 
are not visible in the drawing; their employ in successive re-contraction 
steps is advisable, however, in order to avoid overheating or excessive 
processing temperatures. 
The melt adhesive elements and the respective heat shrinkable components 
adapted thereto permit any number of circular conductor arrays of 
different diameters to be assembled in the manner described. 
Shown in FIG. 5 is a per se known heat-shrinkable component 4. 
Heat-shrinkable components are usually commercially available in a 
pre-stretched state and resume their original unstretched configuration in 
response to a heat treatment. The deformation from which a shrinkable 
component resumes its original configuration in response to a heat 
treatment may also be imparted to the shrink hose as it is being mounted 
on the outer periphery of a cable bundle. 
In accordance with a preferred embodiment of the invention, the 
heat-shrinkable component 4 shown in FIGS. 5,6,7, and 8 is provided with 
an interior coating 6 of a thermoplastic melt adhesive. This melt adhesive 
coating 6 is softened by the finishing heat treatment and penetrates 
inwards into the spaces between the conductor strands, in addition to the 
melt adhesive forced outwards from the interior of the wiring. 
The above described plastic or melt adhesive elements, irrespective of 
whether or not provided with a core, may selectively be formed as a rod 
having a circular cross-section (FIGS. 1 and 2), a solid profile rod 
member (FIG. 3) or a profiled hollow member as shown in FIG. 4. Further 
melt adhesive elements to be thus embedded are shown in FIGS. 13 and 14. 
All of the embodiments shown are based on the principle that the inwards 
acting pressure is created by the re-contraction of a pre-stretched 
heat-shrinkable component and the outwards directed pressure is created by 
the re-orientation or re-contraction of a longitudinally pre-stretched 
material or by the expansion, respectively, of a melt adhesive capable of 
foaming in response to being heated. 
In the latter case the material employed is a heat-responsive melt adhesive 
of a composition adapted in response to a heat treatment to expand 
temporarily or permanently to an enlarged diameter or an enlarged 
cross-sectional configuration, respectively, accompanied by the generation 
of a closed-cell foam in response to the application of heat. The melt 
adhesive coating 6 on the interior surface of the shrinkable component 4 
shown in FIG. 5 preferably consists of a melt adhesive capable of forming 
a closed-cell foam in response to being heated. 
The expansion of the melt adhesive brought about according to the invention 
by the heat treatment, be it by a re-contraction to an original 
cross-sectional configuration or by the foam-generation in the case of a 
foam-generating melt adhesive, cooperates with the re-contraction of the 
surrounding shrinkable component brought about by the same heat treatment 
to create a melt flow within the cable bundle, whereby the individual 
conductor strands of the wiring are sealed in a gas-tight and 
longitudinally water-tight manner. 
The assembly kit according to the invention is shown in FIGS. 6 to 9 in its 
state before the heat treatment, and in FIGS. 10 and 11 after the heat 
treatment. 
This assembly kit comprises a heat-shrinkable component 4 adapted to be 
re-shrunk to a reduced diameter by the application of heat, and a core 
made of a material adapted to expand temporarily or permanently to an 
enlarged cross-section in response to being heated and consisting of, or 
containing, a thermoplastic melt adhesive. According to FIG. 6 this core 
may consist of an inner core 1 made of a cross linkable plastic material 
and an outer layer of a thermoplastic melt adhesive 2 surrounding the 
inner core. According to FIG. 7 the core consists solely of a 
thermoplastic melt adhesive 2 preferably of a foam-generating type. The 
cores of FIGS. 6 and 7 are of circular cross-sectional shape. 
The core shown in FIG. 8 has a cross-sectional shape similar to a maltese 
cross, the spaces between its four cross arms being formed as pockets for 
receiving individual strands and/or cable strands therein. It is also 
possible to employ star-shaped cross-sectional configurations having five 
arms for instance. 
In the assembly kit shown in FIG. 6 the system of inner core 1 and 
thermoplastic melt adhesive 2 is at least partially cross-linked. After 
the cross-linking process the inner core and outer melt adhesive layer are 
longitudinally pre-stretched as a unit. With regard to specific details, 
reference is made to the respective description of the method according to 
the invention. 
The cores depicted in FIGS. 7 and 8 may consist of a thermoplastic melt 
adhesive being of a composition and/or cross-linked in such a manner that 
the application of heat causes it to re-contract after having previously 
been pre-stretched in the longitudinal direction. Preferably, however, the 
cores consist of a material capable of expanding by the generation of foam 
in response to the application of heat. 
Defined between the surrounding heat-shrinkable hose section and the core 
is a space for the accommodation of the wiring system comprising a 
plurality of conductor strands 10. 
The assembly kit according to the invention is employed as follows: 
A plurality of conductor strands 10 is distributed in the most uniform 
manner possible between the core and the surrounding heatshrinkable 
component as shown in FIGS. 6, 7 and 8. A heat treatment in the 
temperature range of about 80.degree. to 155.degree. measured with the 
sealing portion causes the surrounding shrinkable component 4 to shrink 
from the relative large diameter shown in FIGS. 6 to 9 to the relatively 
small diameter shown in FIGS. 10 to 11, so that the heat-shrinkable 
component exerts an inwards directed force. At the same time the heat 
treatment causes the core to expand, accompanied by a softening of the 
thermoplastic melt adhesive of which the core is at least partially 
formed. As already mentioned, the core shown in FIGS. 7 and 8 consists 
solely of a melt adhesive, while the core shown in FIG. 6 consists of a 
melt adhesive 2 surrounding a central inner core 1. The expansion of the 
core in response to the application of heat may be based on the principle 
that the material forming the core has been previously partially 
cross-linked and subsequently pre-stretched in the longitudinal direction. 
The heat treatment causes the pre-stretched material to resume its 
original shape, which in the case of a substantially rod-shaped core is 
accompanied by an enlargement of the cross-sectional dimensions, with the 
result that the melt adhesive softened by the heat treatment penetrates 
into any existing voids. 
Instead of a cross-linked and pre-stretched material the core may also be 
forced of a material capable in response to the application of heat of 
generating a closed-cell foam temporarily or permanently and of 
penetrating into any voids within the surrounding heat-shrinkable 
component. 
In an embodiment of the assembly kit shown in FIG. 9, an inner tubular melt 
adhesive element S1 and an outer tubular melt adhesive element S2 are 
disposed between the surrounding heat-shrinkable component 4 and the core 
element 2 extending along the longitudinal axis of the wiring. The two 
tubular melt adhesive elements are of different diameters and have their 
outer surfaces formed with a plurality of pockets extending adjacent one 
another in the longitudinal direction. The pockets may be formed as 
groove-like recesses in the material or defined by circumferentially 
spaced webs extending in the longitudinal direction. 
The two tubular members S1 and S2 are made in the same manner as the cores 
described above with reference to FIGS. 7 and 8 and have the same 
properties. They consist thus either of a cross-linked thermoplastic melt 
adhesive compsed and cross-linked so that the application of heat in a 
pre-stretched state causes a re-contraction, or they consist of a material 
capable in response to the application of heat of foam generation to 
thereby expand temporarily or permanently and fill any existing voids. As 
already mentioned, the heat treatment of the assembly shown prior to such 
heat treatment in FIG. 6 results in the sealed section of a 
multiple-strand wiring system shown in FIG. 10 in a cross-sectional view. 
In this figure it is clearly shown that the melt adhesive 2 sealingly 
fills the space around the conductor strands 10 between the core and the 
heat-shrinkable component. 
The assembly kit shown in FIG. 9 is advantageously employed for wiring 
systems having a great number of conductor strands. The wiring system 
shown in FIG. 9 prior to heat treatment comprises forty-five conductor 
strands 10. FIG. 11 shows that the heat treatment of the assemblies shown 
in FIGS. 7, 8 and 9 results in a respective sealed section in which the 
spaces between the individual conductor strands and the surrounding 
shrinkable component 4 are completely filled by the solidified 
(cross-linked) melt adhesive 2. As already mentioned, intermediate 
shrinkable components are preferably shrunk around the conductor strand 
arrays retained by elements S1 and S2. 
The interior wall surface of the surrounding heat-shrinkable component 4 
may advantageously be provided with a coating 6 of a thermoplastic melt 
adhesive. The melt adhesive of this coating 6 may be a material capable in 
response to being heated of generating a closed cell foam temporarily or 
permanently. The material of the interior coating 6, is preferably the 
same as, or similar to, the material of the heta-expandable melt adhesive 
elements or cores. 
A particularly interesting application for the method and assembly kit 
according to the invention is the employ in a wiring comprising a 
plurality of electric conductors (individual strands) soldered to one 
another at their ends. FIG. 12a shows a wiring of this type, also referred 
to as "splicing", wherein four individual insulated strands are soldered 
to one another adjacent their ends and provided with a crimp. The 
individual strands are designated a, b, c and d. Connections of this type 
are obviously particularly endangered by corrosion. For sealing a splicing 
of this kind against longitudinal water flow, the electric conductors are 
separated to form two bundles having substantially the same number of 
conductors or the same overall cross-sectional area. Prior thereto a 
tubular plastic element consisting of, or containing, a melt adhesive 2 is 
mounted on one of the conductor bundles as shown in FIG. 12a. As depicted 
in FIG. 12b, the tubular plastic element (hot melt adhesive element) is 
longitudinally slipped over the crimp of the solder connection e, the 
diameter of the tubular element being selected so that the tubular element 
is fixedly retained on the crimp. 
FIG. 12b.sup.1 shows a sideview for explaining the arrangement of FIG. 12b. 
After a heat-shrinkable component 4 has been slipped onto the 
above-described assembly, heat is applied for causing the shrinkable 
component to contract and the tubular plastic element to expand, until the 
softened melt adhesive has uniformly advanced to the ends of the 
shrinkable component. 
In FIG. 12 the merely diagrammatically shown plastic element 2 consists at 
least partially of a thermoplastic melt adhesive capable in response to 
being heated of forming a closed-cell foam. 
FIG. 13 shows a preferred embodiment of the tubular melt adhseive element 
2. In this embodiment the handling of the melt adhesive element 2 is 
facilitated by the provision of an upper projection 12. Opposite handling 
projection 12 the melt adhesive element is formed with a thickened portion 
13 acting as a melt adhesive supply. In the assembly shown in FIG. 12 the 
tubular melt adhesive element of FIG. 13 is suitably arranged so that 
thickened portion 13 is disposed at a location whereat the stripped ends 
of conductors a, b, c and d terminate at the solder connection or crimp, 
respectively. The thickened portion 13 thus ensures that there is a 
sufficient supply of melt adhesive at the location whereat there is a 
plurality of stripped conductors. 
In the case of end closures of the type shown in FIG. 12c it is also 
possible to replace the shrinkable component by a shrink cap, i.e. a 
shrink component closed at one end. 
FIG. 14 shows a preferred embodiment of a tubular melt adhesive element 
having a plurality of retaining pockets 14 distributed about its outer 
periphery. In the embodiment shown there are nine such retaining pockets 
14. The number of retaining pockets 14 may be increased or reduced as 
required. As already explained, each retaining pocket 14 is preferably 
adapted to retain no more than two individual strands or the like to 
thereby ensure that there are nowhere more than two individual strands or 
the like in direct contact with one another. In this manner it is ensured 
that there remain no voids between adjacent strands or cables into which 
the melt adhesive would not penetrate. In a triangle configuration for 
instance of three adjacent conductors or wires there would remain an 
outwards closed central void which would act as a highly disadvantageous 
moisture bridge. The pockets 14 are separated from one another by 
projections 16 extending radially from the outer circumferential surface 
of the tubular melt adhesive element. For permitting the tubular element 
shown in FIG. 14 to be readily positioned at any location of a wiring, it 
is longitudinally cut as indicated at 18. This longitundinal cut 18 
permits the element shown in FIG. 14 to be readily opened for receiving a 
suitable number of conductors or strands in its interior. Preferably one 
or two cable strength of greater thickness may thus extend through the 
interior of the element. The tubular element shown in FIG. 14 is 
preferably formed with a longitudinally extending weakened portion to 
facilitate its being opened at cut 18. To this purpose the tubular element 
may have a longitudinally extending wall portion of reduced thickness. 
In a further embodiment not shown in the drawing, a melt adhesive core may 
have a part-annular cross-sectional configuration with a sector of the 
circular shape missing. This configuration may also be referred to as a 
U-shaped channel. This profile permits the melt adhesive core to be 
readily installed in a wiring. If a closed tubular core were used the 
components of the wiring system would have to be threaded through its 
opening. Both the embodiment of FIG. 14 and the (not shown) U-channel hot 
melt adhesive core permit the components of the wiring to be readily 
positioned within the tubular or part-tubular core. 
FIGS. 15a and 15b show a particular embodiment of the invention employing 
two melt adhesive cores. The two cores 2, 2' consist at least partially of 
a melt adhesive capable in response to being heated of forming a 
closed-cell foam temporarily or permanently. 
Each melt adhesive core 2, 2' is formed as a U-shaped channel member, so 
that it may be readily mounted on an individual strand. In the arrangement 
shown in FIG. 16, the method or assembly kit, respectively, according to 
the invention is used for longitudinally sealing a connection of three 
electric conductors entering from the left to three conductors extending 
to the right. The mechanical connection of respective conductors is 
accomplished by a solder spot and a crimp e. For forming a longitudinally 
sealed section on opposite sites of the crimp e, the melt adhesive 
u-profiles 2 and 2' are mounted on the respective center strands. 
Subsequently a cross-linked and pre-stretched shrink hose 4 is mounted on 
the strands. Application of heat causes component 4 to re-contract and the 
material of melt adhesive cores 2, 2' to expand, accompanied by the 
formation of foam. The heat treatment is terminated when the melt adhesive 
material exits at the two end portions of the shrink component. As evident 
from FIG. 15b, water flowing along the individual strands in the 
longitudinal direction towards the soldered connection is absolutely 
prevented from penetrating the longitudinally sealed sections formed in 
accordance with the invention. At the same time the surrounding shrink 
component prevents any moisture from reaching the soldered connection and 
the associated crimp e in radial directions. 
The preferred material for the heat-shrinkable components according to the 
invention is ethylene-vinylacetate copolymer, because the cross-linking of 
this material is relatively easy to control. The inwards directed force 
exerted by the heat-shrinkable components during their contraction is 
greater than the outwards directed force exerted by the melt adhesive core 
within the section to be sealed. The contraction of the heat-shrinkable 
component forces the softened melt adhesive material to flow in the 
longitudinal direction of the individual strands or cable strands, the 
overall volume remaining substantially constant prior to and after the 
shrinking step. The force exerted by the contraction may be additionally 
controlled by suitably selecting the wall thickness of the material. This 
applies in particular to shrink components consisting of polyethylene. 
The components of the assembly kits according to the invention are suitably 
selected with a view to their intended use. Thus when the temperatures at 
the location of use are not expected to rise above 85.degree. C., as for 
instance in the body structure of motor vehicles, a thermoplastic melt 
adhesive having a melting temperature of about 90.degree. to 95.degree. C. 
would be suitable, for instance a polyamide. If the temperatures to be 
expected during use are higher, for instance 105.degree. C., as in the 
engine compartment of a motor vehicle, use is made of melt adhesives of a 
higher viscosity. The desired viscosity can be rather accurately 
controlled by the pre-cross-linking induced in the material. It is thus 
for instance possible to combine a pre-cross-linked melt adhesive material 
consisting of EVA with a shrinkable component consisting of PE. 
Still higher temperatures of for instance 125.degree. C. require the use of 
suitable materials having a higher viscosity brought about by a higher 
degree of cross-linking. 
The method according to the invention may be performed, and the assembly 
kit according to the invention for performing this method may be made, 
respectively, by using a cross-linkable plastic material of any type in 
which at least partial cross-linking can be induced by electron radiation 
(beta or gamma radiation) or by chemical means. Examples of such materials 
are polyethylene LLDPE, LDPE or HDPE; polyamide PA; polyvinylidene 
fluoride PVDF; polyvinyl chloride PVC or mixtures of such materials. The 
crystallite melting point of thermoplastic melt adhesives preponderantly 
lies in the temperature range of about 60.degree. to 125.degree. C. The 
processing temperature of heat-shrinkable components lies in the 
temperature range of about 80.degree. to 155.degree. C., measured within 
the sealing position. 
The cross-linkable plastic material employed for the inner core of the 
plastic core element according to the invention is preferably 
polyethylene. The outer layer formed on such a polyethylene inner core is 
preferably a thermoplastic melt adhesive on a polyamide base. The plastic 
core elements according to the invention having no inner core are 
preferably made of a thermoplastic melt adhesive consisting of 
ethylene-vinylacetate copolymer (EVA). 
The foaming reaction of the melt adhesive in response to being heated is 
preferably brought about by the use of endothermic foaming agents 
decomposing at about 140.degree. C. to thereby promote the formation of a 
closed-cell foam. An example of such a foaming agent is a composition sold 
under the designation "Hydrocerol" by the firm of Boehringer-Ingelheim. 
In the assembly kits according to the invention, the length of the 
heat-shrinkable components is about three or four times that of the core 
elements (prior to use). In the case of solid core elements having a 
circular cross-section, preferably with recesses in their outer surface, 
and having a diameter of 3 to 8 mm, the longitudinal dimension may be 
about 10 mm. The associated heat-shrinkable components have a length of 
about 35 to 45 mm prior to shrinking. 
Hollow members of circular cross-section (FIG. 4) preferably have a 
diameter up from 10 mm and a length of 10 to 25 mm. The associated shrink 
components have a length of 35 to 75 mm prior to shrinking. 
The preferred shrinkable components having a diameter of about from 10 mm 
prior to shrinking, and of from 2 mm after shrinking. Preferably the 
shrink rate is 4:1 with a wall thickness after shrinking of for instance 
2, 2 mm.