JPH1050148A - Cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily lead out an inner electric wire and keep a sufficient length of a led out part in branching connecting by producing a center intermediate material whose circumference is surrounded with a plurality of stranded electric wires from a hollow member which can be partially pulled out or whose diameter can be reduced. SOLUTION: A hollow member produced by spirally forming a string-like body 12 of synthetic resin is used as a center intermediate material 10. A cable core 2 is formed by stranding a plurality of electric wires in the circumference of the intermediate material 10 and a sheath 3 is further formed in the circumference of the resultant cable core. After the inner electric wire are exposed by stripping the sheath 3 of a branching and connecting part A, a cutting tool is inserted into a gas between neighboring electric wires 1 and the string-like body 12 is cut in the middle. As a result, the spiral shape of the string-like body 12 is partially eliminated and the string- like body is converted into a simple linear shape, so that the string-like body 12 can be easily pulled out of a gap between neighboring electric wires 1. Consequently, electric wires 1 are greatly loosened and, by utilizing the loosening, a prescribed electric wire 1 can be easily cut and pulled out in the sufficient length and a branching and connecting work can be carried out excellently.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable suitable for a communication cable and the like.

[0002]

2. Description of the Related Art Conventionally, as various cables including communication cables, a plurality of electric wires 1 are twisted with each other to form a cable core 2 as shown in FIG.
A cable in which a sheath 3 is formed around the cable core 2 is often used.

[0003]

In the above-mentioned cable, for example, when branching and connecting at the intermediate portion A shown in FIGS. 9A and 10A, as shown in FIG. It is necessary to strip off the sheath 3 in the portion A to expose the inner electric wire 1, appropriately divide the predetermined electric wire 1, and lead the electric wire 1 to the outside of the sheath 3.

However, in the structure shown in FIG. 9A, it is not easy to pull out only the necessary wires 1 because the wires are densely packed in the cable. Since the wires are twisted without a long length, the drawer length y required for making the branch connection (FIG. 10)
(B)) cannot be secured. For this reason, conventionally,
An operation of once cutting the entire cable at the portion A and then reconnecting only an appropriate portion using a joint device is performed. However, such an operation is troublesome and greatly hinders improvement in efficiency. Also, since the joints have low joint strength, the joints are stepped on, the office equipment is placed on them, or intersected with other cables while the cables are laid on the floor. If a large pressure is applied to the above-mentioned joint portion due to the above-mentioned operation, there is also an inconvenience that disconnection is likely to occur at the portion.

[0005] As means for allowing the electric wire to be drawn out without cutting the entire cable as described above, FIG.
Instead of twisting the wires 1 in one direction as shown in (a), a so-called SZ twist is performed, as shown in FIG. A lengthy structure is provided. But,
Even with this structure, there is a limit in increasing the length y of the drawer, and when the wires 1 are densely packed, the wires 1 hardly move relative to each other, so that the draw operation is difficult. There is.

In view of such circumstances, the present invention provides a cable capable of easily drawing out an internal electric wire at the time of branch connection at an intermediate portion and securing a sufficient drawing length for branch connection. The purpose is to do.

[0007]

As a means for solving the above-mentioned problems, the present invention provides a method for twisting a plurality of electric wires around a central inclusion, covering these electric wires with a sheath, and disposing the above-mentioned central inclusion. Is constituted by a hollow member that can be extracted or reduced in diameter only in a part of its axial direction.

[0008] The term "electric wire" used herein includes not only a normal insulated wire but also a wire unit in which a plurality of wires are combined.

In the above cable, the sheath at the place where the branch connection is made is peeled off, and the central inclusion at that place is partially extracted or partially reduced in diameter, so that the length of each wire is reduced by the extracted or reduced diameter. It is possible to spare (that is, to loosen each wire). Accordingly, in this state, it is possible to easily draw out an appropriate electric wire, and it is possible to sufficiently secure the length of the drawn out electric wire.

[0010] More specifically, according to the above-mentioned structure in which the central inclusion is formed by a spiral, the spiral is cut in the middle to make the spiral into a wire material, thereby forming a gap between the electric wires. Can be easily removed.

Further, according to the heat-shrinkable tube made of polyvinyl chloride or the like as the central inclusion, the diameter of the pipe can be reduced at that point by locally heating the branch connection portion. The wire can be slackened by the reduced diameter.

In a cable constituted by connecting a plurality of airbags into which air is press-fitted inside the above-mentioned central inclusions in the longitudinal direction of the cable and connecting them, a hole is formed in the airbag located at the branch connection portion. By releasing the air inside and deflating the airbag, the wire can be slackened by the amount of the deflation.

In the present invention, the specific twisting form of each electric wire is not limited. However, instead of twisting each electric wire in one direction, a so-called S as shown in FIG.
If the wire is made to have an extra length by Z-twisting, the wire becomes easier to move by the extra length, so that the work of extracting or reducing the diameter of the above-mentioned central inclusion becomes easier, and the length of the drawer further increases. .

In each of the above-mentioned cables, in order to peel off the sheath of the branch connection portion, it is necessary to cut the sheath by inserting a blade into the sheath from the outside. When doing so, there is a risk that the internal wires may be accidentally damaged. However, if a ridge extending in the direction having the component in the longitudinal direction of the cable is formed on the surface of the sheath, and a cut is provided at the base of the ridge,
By dividing only the ridge at an appropriate place, and then peeling only the ridge from the sheath body along the shape of this ridge,
Since a slit can be formed in the portion where the ridge was formed, the entire sheath can be easily peeled off without damaging the internal electric wire by using the slit as a point.

The ridge may be a simple straight line. In this case, when the cable is laid with the ridge down, it is extremely difficult to strip the ridge from the sheath body. Become. On the other hand, if the ridge is formed in a spiral shape, even if the cable is wired, there is always a part facing upward in this ridge, so this part is cut off and the ridge is easily removed from the sheath body. Can be stripped off.

[0016]

FIG. 1 shows a first embodiment of the present invention.
(A) and (b).

In this embodiment, as shown in FIG. 1 (a), a spiral body formed of a filament 12 made of a synthetic resin or the like is used as the central inclusion 10 and the periphery thereof is used. A plurality of wires 1 are twisted to form a cable core 2
Is formed, and the sheath 3 is formed therearound.

Each of the wires 1 may be a normal insulated wire or a wire unit combining a plurality of wires. The number of electric wires 1 is not limited to the example shown in the figure, and may be set as appropriate according to the specifications. In this regard, the same applies to the following second embodiment and the following embodiments.

According to the cable shown in FIG. 1A, the sheath 3 at the branch connection portion A is peeled off to expose the inner wires 1, and then a cutting tool is inserted through a gap between the wires 1. By cutting the linear body 12 on the way, the spiral shape of the linear body 12 can be partially eliminated, and the linear body 12 can be made into a simple linear shape.
It can be easily extracted from the gap between them. As shown in FIG. 1 (b), the extraction of the linear body 12 causes a large slack 4 in the electric wire 1. Therefore, the predetermined electric wire 1 is easily cut using the slack 4 and has a sufficient length. It can be drawn out, so that a good branch connection can easily be achieved.

The reason why the wire 4 is slackened 4 due to the extraction of the linear body 12 is as follows. First, FIG.
In the state where a plurality (four in the illustrated example) of the electric wires 1 are twisted around the central inclusion 10 as shown in FIG. 5, the twisted diameter (diameter of a circle shown by a chain line in the drawing) Do is Given by

[0021]

Do = d / 2 + Di + d / 2 = Di + d where Di is the diameter of the central inclusion 10, and d is the diameter of the electric wire 1. Accordingly, the wire twisting length Lo per twisting pitch p is expressed as follows.

[0022]

Lo = {p ² + (πDo) ² } = {p ² + π ² (Di + d) ² } On the other hand, as shown in FIG. The twisting diameter D in the state of being twisted in close contact with each other is equal to the length of a diagonal line of a square having a side length d of √2d, and thus the twisting length per pitch in this state. L is represented by the following equation.

[0023]

L = √ ｛p ² + (πD) ² ｝ = √ ｛p ² + π ² (√2d) ² ｝ The slack 4 is equivalent to the difference ΔL between both twisted lengths Lo and L, This difference L is expressed by the following equation.

[0024]

ΔL = Lo−L = √ ｛p ² + π ² (Di + d) ² ｝ −√ ｛p ² + π ² (√2
d) ²に よ According to Equation 4, the diameter Di of the central inclusion 10 is (√2
-1) If it is larger than d, ΔL> 0, and the slack 4 can be given to the wire 1 by the amount of ΔL. Also, the slack 4 increases as the difference between the inclusion diameter Di and the wire diameter d increases. It can be understood that it can be enlarged.

The spiral body according to the present invention is not limited to the above-mentioned one, and as a second embodiment, as shown in FIG. 3 (a), a spiral cut 13 is formed in the peripheral wall of the pipe to form a spiral. The linear body 14 may be formed, and at the time of branch connection, the linear body 14 may be cut in the middle and taken out linearly, or as a third embodiment, as shown in FIG. ,
A plurality of spiral linear bodies 12 having different winding directions from each other may be overlapped and joined at their intersections 15 to form a net-like body.

FIGS. 4A and 4B show a fourth embodiment. Here, the heat shrink tube 1 is used as the central inclusion 10.
6, a plurality of electric wires 1 are twisted around the heat-shrinkable tube 16 in a state before the heat-shrinkable tube 16 thermally shrinks (a state shown in FIG. 4A). The heat-shrinkable tube 16 can be manufactured, for example, by expanding a plastic tube made by extrusion molding while heating it to an appropriate temperature and performing molecular orientation in the circumferential direction. , Polyethylene, polypropylene and the like are preferred.

According to such a cable, the heat-shrinkable tube 16 can be formed only by locally heating the branch connection portion.
Can be opened to form a gap 17 between the heat-shrinkable tube and the electric wire 1 (FIG. 4B).
Therefore, each of the electric wires 1 can have a suitable slack.

FIGS. 5A and 5B show a fifth embodiment. Here, the airbags 18 in which pressurized air is sealed are arranged in a line, and these airbags 18 are integrally connected by a connecting portion 19 to thereby form the central inclusion 1.
0 is configured. That is, each airbag 18
As shown in FIG. 5 (a), it is formed in a substantially cylindrical shape in a state in which it is expanded by the internal pressure of the air, and a plurality of electric wires 1 can be twisted around the cylindrical shape as shown in each of the above embodiments. ing.

The material of each airbag 18 is polyethylene, polyvinyl chloride, polypropylene,
Various polymer materials such as nylon are suitable, and it is also possible to integrally mold the entire central inclusion 10 with these materials.

When such a central inclusion 10 is used, a hole is formed with a needle or the like only in the airbag 18 located at the branch connection portion, and air is released from the airbag 18 to squeeze the airbag 18. (FIG. 5
(State (b)), the diameter of the airbag 18 can be significantly reduced, and the electric wire 1 can be suitably slackened.

Although not shown, if a central inclusion is formed by a bellows-shaped pipe (ie, an electric wire is twisted around the bellows-shaped pipe), a portion corresponding to a branch connection portion can be formed. By locally pulling out the bellows by pulling both ends of the pipe, the diameter of the pipe at this point can be significantly reduced, thereby also providing a suitable slack to the electric wire.

In each of the above embodiments, it is necessary to peel off the sheath 3 before extracting or reducing the diameter of the central inclusion 10. At this time, a blade is directly attached to the sheath 3 from the outside. If the cutting method is used, the blade may inadvertently damage the internal electric wire 1, so that the stripping operation must be performed very carefully, and the burden on the operator becomes very large.

However, by making the cross-sectional shape of the sheath 3 as shown in FIG. 6, for example, the stripping operation of the sheath 3 can be greatly facilitated. In the figure, a ridge 30 extending linearly in the longitudinal direction of the cable is formed on a part of the sheath 3 in the circumferential direction. A pair of left and right knobs 31 are provided on the top of the ridge 30 so as to protrude on both left and right outer sides, and a cut 32 is formed at the base of the ridge 30 inward in the radial direction.

According to such a sheath 3, the ridge 3
The ridge 30 is cut into the longitudinal direction of the cable at an appropriate place by inserting a blade into the ridge 0, and one of the divided ridges 30 is gripped with a finger or the like, and is moved from the main body of the sheath 3 along the path where the ridge 30 is formed. By stripping off (FIG. 7), a slit 33 can be formed at the place where the ridge 30 was located.
And the sheath 3 can be easily stripped off without damaging the electric wire 1 inside.

When the ridges 30 are linear as described above, if the cable is laid in a state where the ridges 30 face downward (that is, a state in which the ridges 30 are in contact with the floor surface or the like), the ridges 30 are formed.
However, if the ridge 30 is formed in a spiral shape as shown in FIG. Since there is a portion facing (ie, facing the side opposite to the floor surface or the like), there is an advantage that the stripping operation of the ridge 30 can be easily performed using this portion as a starting point.

[0036]

As described above, according to the present invention, a plurality of electric wires are twisted around the central inclusion so that the electric wire can be loosened by partially extracting or reducing the diameter of the central inclusion. Therefore, there is an effect that the operation of drawing out the wire for branch connection can be easily performed, and the length of the drawn out wire can be sufficiently secured.

More specifically, according to the above-mentioned structure in which the central inclusion is formed of a spiral, the spiral can be easily extracted from the gap of the electric wire only by cutting the spiral. Can be.

According to the structure in which the central inclusion is formed of a heat-shrinkable tube made of polyvinyl chloride or the like, the diameter of the central inclusion can be easily reduced only by locally heating the branch connection portion.

In a cable constituted by connecting a plurality of airbags into each of which the above-mentioned central inclusion is press-fitted with air and arranged in the longitudinal direction of the cable, it is only necessary to make a hole in an appropriate airbag to release the air inside. In operation, the central inclusion can be significantly reduced in diameter.

Further, according to the sheath in which a ridge extending in a direction having a component in the longitudinal direction of the cable is formed on the surface of the sheath, and a cut is provided at a base portion of the ridge, the ridge is used to make use of the ridge. The effect of easily stripping off the sheath without damaging the inner electric wire is obtained.

In particular, in the case where the ridge is formed in a spiral shape,
Regardless of the wiring state of the cable, the stripping operation of the ridge can always be easily performed.

[Brief description of the drawings]

FIG. 1A is a cross-sectional perspective view showing a state before a center inclusion is extracted from a cable in a first embodiment of the present invention, and FIG. 1B is an electric wire obtained by extracting a center inclusion from the cable. It is a sectional perspective view showing the state where slack was given.

2A is a cross-sectional front view showing a twisted diameter of an electric wire before removing a central inclusion in the present invention, and FIG. 2B is a cross-sectional view showing a twisted diameter of the electric wire after removing a central inclusion. FIG.

FIG. 3 (a) is a perspective view of a central inclusion in a second embodiment of the present invention, and FIG. 3 (b) is a perspective view of a central inclusion in a third embodiment of the present invention.

FIG. 4A is a cross-sectional perspective view showing a state before a heat-shrinkable tube as a central inclusion is shrunk in a fourth embodiment of the present invention, and FIG. 4B is a view after a heat-shrinkable tube is shrunk. It is a sectional perspective view showing the state of.

FIG. 5A is a cross-sectional side view showing a state before an airbag serving as a central inclusion is squeezed in a fifth embodiment of the present invention, and FIG. 5B is a view after squeezing the airbag. It is a sectional side view showing a state.

FIG. 6 is a cross-sectional front view showing a preferable cross-sectional shape of a sheath.

FIG. 7 is a perspective view showing a state in which a ridge is peeled off from a main body of the sheath.

FIG. 8 is a perspective view showing an example in which the ridge is formed in a spiral shape.

9 (a) is a cross-sectional perspective view showing a conventional cable in which electric wires are twisted in one direction, and FIG. 9 (b) is a cross-sectional perspective view showing a conventional cable in which electric wires are twisted by SZ twist.

10 (a) is a schematic diagram of the cable shown in FIG. 9,
(B) is a schematic diagram showing a state where a predetermined electric wire is drawn from the cable.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric wire 2 Cable core 3 Sheath 4 Looseness 10 Central inclusion 12, 14 Linear body (a spiral body) 16 Heat shrinkable tube 18 Airbag 30 Ridge 32 Cut

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Noriaki Yamano 1-114, Nishisuehiro-cho, Yokkaichi-shi, Mie Sumitomo Wiring Systems, Ltd. (72) Inventor Takakazu Ishida 1-114, Nishisuehiro-cho, Yokkaichi-shi, Mie Sumitomo Wiring Systems, Ltd.

Claims (6)

[Claims] 1. A plurality of electric wires are twisted around a central inclusion, these electric wires are covered with a sheath, and the central inclusion is formed of a hollow member which can be extracted or reduced in diameter only in a part of its axial direction. A cable characterized by comprising. 2. The cable according to claim 1, wherein said central inclusion is constituted by a spiral body. 3. The cable according to claim 1, wherein said central inclusion is constituted by a heat-shrinkable tube. 4. The cable according to claim 1, wherein the central inclusion is formed by connecting a plurality of airbags, into which air is press-fitted, in a longitudinal direction of the cable. 5. The cable according to claim 1, wherein a ridge extending in a direction having a component in a longitudinal direction of the cable is formed on a surface of the sheath, and a cut is provided at a base portion of the ridge. A cable characterized in that: 6. The cable according to claim 5, wherein said ridge is formed in a spiral shape.