JP2000243150A - Cable containing pipe for force feed - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent buckling of a pipe, or the disconnecting of connected portions by the sticking out or pulling in of a pipe at an end part of its outer cladding. SOLUTION: An outer cladding 10 is provided outside a cable core 7 having one or a plurality of corrugated pipes 1 made of plastics. By utilizing the ease of expansion/contraction and flexibility of the corrugated pipes 1, the corrugated pipes are prevented from buckling or being disconnected at their portions coming out from an end part of the outer cladding 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable containing a pipe for pressure feeding, which has an internal pipe for optically feeding an optical fiber unit or the like.

[0002]

2. Description of the Related Art A technique for previously laying an elongated cylindrical pipe made of plastic having an inner diameter of 4 to 6 mm and for pressure-feeding an optical fiber unit or the like using compressed air or the like has already been frequently used. In addition, by assembling a plurality of pipes used for the purpose and applying an outer coating to the outside to form a pipe assembly cable, a plurality of pipes can be handled at a time, so that the laying work is also facilitated.

A composite cable in which one or a plurality of pipes are twisted with a power cable unit or a communication cable unit and an outer coating is provided on the outside thereof is also obtained by pressure-feeding an optical fiber unit or the like to the pipe later. Since it can be used additionally, it is used as a multipurpose cable.

[0004]

In the manufacture of such a pipe aggregated cable or a composite cable, usually, at least an assembly step of assembling a pipe alone or a pipe and a power cable unit, a communication cable unit, etc. to form a cable core. And a covering step of providing an outer covering on the assembled cable cores. In the assembly process, pipes,
Since the power cable unit, the communication cable unit, and the like are assembled while applying tension in the longitudinal direction by the back tension, the pipes are assembled in a state in which the pipe is stretched in the longitudinal direction and distortion is inherent. Therefore, an internal stress that tends to contract in the longitudinal direction acts on the pipe, the communication cable unit, and the like.

In the coating process, an external coating such as a corrugated metal coating and a plastic coating is applied. In the case of a metal coating, tension is applied in the coating process, and in the case of a plastic coating, the plastic is stretched during extrusion. Due to the strain, internal stresses are working to shrink in the longitudinal direction.

[0006] These internal stresses are not directly released due to frictional force with other members of the cable, etc., but are held for a long time. If left untreated, internal strain will be relaxed by the above internal stress while shrinking and elongating due to temperature change is repeated,
Longitudinal shrinkage occurs in pipes, outer coatings, etc. For this reason, at the end of the cable, the cable core including the pipe may protrude from the end of the outer jacket, or the cable core including the pipe may be drawn into the outer jacket.

FIG. 3 is a diagram showing an example of a connection portion of a pipe assembly cable using a connection box. FIG. 4 (A)
FIG. 4B is a view showing a state of a pipe assembly cable between the connection boxes, FIG. 4A is a state at the initial stage of laying, and FIG.
Indicates a state after a lapse of time after the installation. 3 and 4, reference numeral 11 denotes a pipe assembly cable, 11a denotes an end portion of an outer coating, 12 denotes a pipe, 13 denotes a pipe connector, 14 denotes a connection pipe, 15 denotes a connection box, and 16 denotes a slack.

In connection, as shown in FIG.
At the ends of the pipe assembly cables 11, the outer coating is removed to expose the pipe 12, and the ends 11a of the outer coating are fixed to the connection boxes 15, respectively. Then, the opposed pipes 12 are connected to each other through a connection pipe 14 using a pipe connection connector 13 in a connection box 15.

At the connection portion of the pipe assembly cable, even if the outer sheath tries to contract in the longitudinal direction, the end portion 11a of the outer sheath cannot be moved because it is fixed to the connection box 15. Therefore, shrinkage of the outer coating appears as the following phenomenon. That is, the pipe assembly cable 11 laid at the beginning of the installation has a slack 16 between the connection boxes 15 as shown in FIG.
When several years have passed after the installation, the shrinkage of the outer coating
As shown in FIG. 4B, the slack 16 is eliminated and the pipe aggregate cable 11 becomes straight, or the slack 16 is smaller than that in FIG.

If the shrinkage of the pipe is smaller than the shrinkage of the outer coating, the pipe becomes relatively longer than the outer coating, and the pipe protrudes from the end of the outer coating. In particular, in the case of an outer coating having a corrugated metal coating, the amount of pipe protrusion is large because the frictional force between the outer coating and the cable core in which the pipes in the inner coating are gathered is small and the cable core is slippery in the outer coating. Become. When the pipe protrudes significantly, it may protrude by 30 mm or more.

If the shrinkage of the pipe is greater than the shrinkage of the outer coating, the pipe will be relatively shorter than the outer coating, and the pipe will be drawn inside the outer coating. The degree of shrinkage of the pipe and the outer coating varies depending on the manufacturing conditions of the assembling process and the coating process, but in general, the shrinkage of the outer coating is often greater than the shrinkage of the pipe, so the pipe is Often protruding from the end.

When the pipe 12 protrudes from the end 11a of the outer sheath, the end 11a of the outer sheath and the pipe connector 1
The pipe 12 bends between 3 and 3
2 bends and buckles. Then, the optical fiber unit and the like inserted into the pipe may be damaged. Further, when the inside of the pipe is not inserted, the optical fiber unit or the like cannot be inserted due to the bending of the pipe. Also, the pipe 12 is connected to the end 1
When it is pulled in from 1a, a situation occurs in which the pipe connection connector 13 between the pipe 12 and the connection pipe 14 comes off.

An object of the present invention is to provide a pressure-feeding cable with a pipe in which the problems caused by the protrusion or retraction of the pipe from the end of the outer sheath of the cable with a pressure-feeding pipe according to the prior art described above are reduced.

[0014]

According to the present invention, there is provided a cable with a pressure-feeding pipe provided with an outer coating on the outside of a cable core having one or a plurality of corrugated pipes made of plastic. Since the corrugated pipe is easy to expand and contract or bend, even if the corrugated pipe protrudes from the end of the outer coating, or if the corrugated pipe is drawn into the inside of the outer coating, the wave reaching the connection connector will not occur. The exposed portion of the pipe with buckle does not buckle or the pipe with undulation does not come off from the connector.

Further, the outer coating is a composite of a corrugated metal coating and a plastic coating provided on the outer side thereof, wherein the frictional force between the outer coating and the cable core is small and the cable core slips in the outer coating. In the case of a cable containing a pipe for pressure feeding that is easy to move, the protrusion of the cable core having the pipe tends to be large, so that the effect of easy expansion and contraction and bending of the corrugated pipe is great.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing an embodiment of a cable with a pressure-feeding pipe according to the present invention, and FIG. 1 (A) is a perspective view of the cable with a pressure-feeding pipe with a part of the outer coating removed. FIG. 1B is a cross-sectional view. In FIG. 1, 1
Is a corrugated pipe, 2 is a communication line, 3 is a press winding, 4 is a communication cable unit, 5 is an interposition cord, 6 is a press winding, 7 is a cable core, 8 is a corrugated metal coating, 9 is a plastic coating, and 10 is a plastic coating. External coating.

This cable with a pipe for pressure feeding has two corrugated pipes 1 made of plastic and two communication cable units 4 in which a plurality of communication lines 2 are twisted to form a presser winding 3. A cable unit 7 is formed by twisting and gathering around the string 5 and applying a presser winding 6,
An outer coating 10 comprising a corrugated metal coating 8 and a plastic coating 9 such as polyethylene is provided on the outside.

In the example of FIG. 1, the number of corrugated pipes 1 is two.
Although it is a book, any number of corrugated pipes may be used. Although the example of FIG. 1 is a composite cable of the corrugated pipe 1 and the communication cable unit 7, the corrugated pipe alone may be assembled, or a corrugated pipe, a power cable unit, an optical cable unit, or another such cable. It may be combined with the unit of use. Also, the outer coating 10 is a composite of the corrugated metal coating 8 and the plastic coating 9, but there are cases where only the plastic coating is used. There are also examples in which the plastic coating is of a self-supporting type, or an exterior is provided outside the plastic coating.

FIG. 2 is a longitudinal sectional view showing an example of a corrugated pipe used for the cable with a pipe for pressure feeding of the present invention. The corrugated pipe 1 is made of a plastic such as high-density polyethylene, polyamide, or the like. The inner diameter d is about 4 to 6 mm, the thickness t is about 1 mm, and the pitch p of the wave shape is 1 to 2 m.
m, the depth h of the wave shape is about 0.5 to 1 mm, and the longitudinal cross section has a smooth wave shape. Since a corrugated pipe needs not only elasticity and flexibility but also a certain degree of compressive strength and tensile strength, it is desirable that the longitudinal cross-sectional shape be sinusoidal on both the outer and inner surfaces.

The corrugated pipe 1 may be formed in a spiral shape along the pipe surface, or the corrugated peaks and valleys may be ring-shaped so as to be rotationally symmetric about the pipe axis. Can also be formed.

In the case of the cable containing the pipe for pressure feeding shown in FIG.
On the outside of the cable core 7, an outer coating 10 composed of a corrugated metal coating 8 and a plastic coating 9 is provided. The corrugated metal coating 8 is formed by deforming a steel tape into a cylindrical shape and extending it vertically, welding the longitudinal butted portion into a tube shape, and corrugating the steel tape. In some cases, peaks and valleys of waves that are rotationally symmetric with respect to the cable axis form a ring shape. The plastic coating is formed by extrusion using polyethylene or the like.

When the same connection as that shown in FIG. 3 is performed using the above-described cable with a pressure-feeding pipe of the present invention, if a corrugated pipe tries to protrude from the end of the outer coating, the pipe is corrugated and expands and contracts. Since it is easy and has high flexibility, when the amount of protrusion is small, the corrugated pipe itself only contracts and does not bend and buckle. Also, even if the amount of protrusion is large, the corrugated pipe draws a curve and smoothly bends, so that the corrugated pipe does not bend and buckle.

Therefore, even if the optical fiber unit is already inserted into the corrugated pipe, it is not damaged. Further, even if the inside of the corrugated pipe is not inserted, the pipe is not bent and crushed, and the inner diameter section is kept substantially circular, so that the insertion of the optical fiber unit or the like into the pipe is not hindered. Further, when the corrugated pipe is about to be drawn inside the outer coating, the pitch of the corrugated pipe is increased, so that the connection between the pipe and the pipe connector is not disconnected.

In the case of a cable in which a plurality of corrugated pipes are assembled and only the corrugated pipe is provided with an outer coating on the outside thereof, the pipe aggregate is simply wound roughly, and the corrugated pipe of the pipe aggregate is used. If the outer coating is in direct contact with the outer coating, the corrugated pipe will expand and contract due to the frictional force between the outer coating and the corrugated pipe as the outer coating expands and contracts due to temperature changes. The protrusion from the part and the corrugated pipe are prevented from being drawn inside the outer coating.

Although the optical fiber unit was pressure-fed into the corrugated pipe of the cable with a pressure-feeding pipe using the corrugated pipe shown in FIG. 2, the pressure-feeding was performed without any problem similarly to the conventional cylindrical pipe. I was able to do it.

[0026]

According to the present invention, the cable containing a pipe for pressure feeding is
The outer sheath is provided on the outside of the cable core having the corrugated pipe, so that the pipe can be easily expanded and contracted or bent, and the corrugated pipe protrudes from the end of the outer sheath or has a wavy shape inside the outer sheath. Even when the pipe is pulled in, the exposed portion of the corrugated pipe reaching the connection connector does not buckle, and the corrugated pipe does not come off from the connection connector.

When the outer coating is a cable having a small frictional force between the outer coating and the cable core, such as a composite of a corrugated metal coating and a plastic coating, and the cable core is slippery in the outer coating, the pipe is formed by a pipe. It is very effective to corrugate the pipe, as it often protrudes and retracts. In addition, by making the vertical cross section of the pipe a sinusoidal shape on both the outer and inner surfaces, the expansion and contraction of the pipe,
Bending can be smoothed, and the pipe can be made strong against compressive force.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a view showing an embodiment of a cable with a pressure-feeding pipe according to the present invention, in which (A) is a perspective view of the cable with a pressure-feeding pipe with a part of an outer coating removed, and (B) is a cross-sectional view. is there.

FIG. 2 is a longitudinal sectional view showing an example of a corrugated pipe used in the cable with a pipe for pressure feeding of the present invention.

FIG. 3 is a diagram illustrating an example of a connection portion of a pipe assembly cable using a connection box.

4 (A) and 4 (B) are diagrams showing a state of a pipe assembly cable between junction boxes, and FIG.
(B) shows a state in which time has elapsed after the installation.

[Explanation of symbols]

 1: Corrugated pipe 2: Communication line 3: Holding coil 4: Communication cable unit 5: Intermediate cord 6: Holding coil 7: Cable core 8: Corrugated metal coating 9: Plastic coating 10: External coating

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H038 CA69 3H111 AA02 AA03 BA01 BA15 CA42 CA52 CB02 CB03 CB29 DA20 DA26 DB11 DB23 5G309 KA04 5G319 HA01 HA08 HD03 HE15 HE17 HE26

Claims (3)

[Claims] 1. A cable with a pipe for pressure feeding, wherein an outer coating is provided outside a cable core having one or more corrugated pipes made of plastic. 2. A cable with a pipe for pressure feeding according to claim 1, wherein the longitudinal section of the corrugated pipe has a sinusoidal shape on both the outer surface and the inner surface. 3. The cable with a pipe for pressure feeding according to claim 1, wherein the outer coating is a composite of a corrugated metal coating and a plastic coating provided outside the corrugated metal coating.