JPH08220390A - Optical fiber cable and its post-branching method - Google Patents

Abstract

PURPOSE: To provide an optical fiber cable and its post-branching method with which the efficient working of a post-branching operation to branch optical fibers from a laid optical fiber cable is possible. CONSTITUTION: The optical fiber cable 1 formed by inserting >=1 pieces of pipes 34 for pull-in into a sheath 37, inserting an optical fiber unit 35 into this pipe 34 and providing both of the inside surface of the pipe 34 and the outermost surface of the optical fiber unit 35 with lubricating layers is used. The pipe 34 of a position desired to be post-branched of the cable 1 is exposed and the pipe 34a to be inserted with the optical fiber unit 35a to be post branched is selected. Only the pipe 34a or the pipe 34a and the optical fiber unit 35a are cut and a compressed gas 41 is fed into the cut pipe 34a from the terminal of the cable 1 to entrain the optical fiber unit 35a in the flow of the compressed gas 41 and to progress the unit. by which the optical fiber unit 35a is taken out of the cut part 42 of the pipe 34a to a desired length.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber cable used in the field of optical communication using an optical fiber as a transmission medium and a branching method therefor. The work is done efficiently.

[0002]

2. Description of the Related Art Conventionally, in the field of optical communication, an optical fiber cable composed of a large number of optical fiber element wires and optical fiber core wires has been used, and the structure thereof is a layer twist type, a slot type, a loose tube. There are various types such as mold and groove type. In particular, an optical fiber cable in which the optical fiber is branched from the laid optical fiber cable in order to connect with the optical fiber of another optical fiber cable, and the post-branch is taken into consideration. It has been known. As such an SZ type optical fiber cable, specifically, a layer-twisted type optical fiber cable having a structure in which an optical fiber core wire is SZ-twisted, and a slot type optical fiber cable is provided in a longitudinal direction of a slot. Examples include a structure having an SZ slot groove formed therein.

FIG. 5 shows a schematic structure of the above-mentioned optical fiber cable. In the figure, reference numeral 1 is an optical fiber cable. The optical fiber cable 1 includes a tension member 2 made of an FRP rod and a tension member 2
And a coating layer 3 provided around the
The Z-twisted optical fiber core wires 4 ..., the buffer layer 5 provided around the optical fiber core wires 4 ..., and the non-woven tape wound around the buffer layer 5. It is composed of a press winding layer 6 and an outermost PVC sheath 7.

Further, FIG. 6 shows a schematic structure of the above-mentioned optical fiber cable, in which reference numeral 10 is an optical fiber cable. The optical fiber cable 10 includes a long round rod-shaped slot 11 made of polyethylene or the like,
Tension member 2 inserted in the center of the slot 11
A plurality of SZ slot grooves 12 formed in the longitudinal direction of the slot 11, the optical fiber core wires 4 respectively housed in the slots, and a non-woven tape wound around the slot 11. It is composed of a presser winding layer 6 and an outermost PVC sheath 7.

[0005]

By the way, the conventional SZ
Type optical fiber cables have a structure in which optical fibers are twisted into SZ twist in consideration of post branching, but when actually performing post branching, the following problems was there. For example, in the post-branching operation of the optical fiber cable 1 shown in FIG. 5, after the optical fiber cable 1 is laid, the sheath 7, the presser winding layer 6 and the buffer layer at the position where the optical fiber cable 1 is to be post-branched as shown in FIG. By removing the coating such as 5 and releasing the inverted portion of the SZ twist shown by the I-I line, the bundle of the optical fiber core wires 4 ... The optical fiber core wire 4a to be connected to the optical fiber can be selected and taken out. Here, the length of the optical fiber core wire 4a taken out from the coating removal portion of the optical fiber cable 1 is represented by the following formula (a).

Length of optical fiber core wire = length of coating removal portion L ₁ × ( ₁ + twisting rate of optical fiber core wire) (a)

From the length L ₁ of the coating removal portion, It was only a few to a few percent longer. That is, the length L ₁ of the coating removal portion is determined by the length of the closure for covering the coating removal portion of the optical fiber cable 1 and the connection portion of the other optical fiber cable with the optical fiber, and the length of the closure. Since the length is usually about 600 mm, the length L ¹ of the coating removal portion housed in this closure is about 500 mm, and therefore the length of the optical fiber core wire 4a taken out by releasing the twist switching portion is at most. It was about 500 mm.

However, the optical fiber core wire 4 to be taken out
If the length of a is about 500 mm, it is too short to be connected to the optical fibers of other optical fiber cables and is insufficient for work. Therefore, as shown in FIG. After taking out all the wires 4, the central tension member 2 is cut along the line II-II and the line III-III, and then the two cut end faces of the optical fiber cable 1 are drawn together as shown in FIG. 8B. The bundle of the optical fiber core wires 4 ... Is further loosened, the optical fiber core wires 4a to be connected to the optical fibers 24 of the other optical fiber cables 20 are selected, and the optical fiber core wires 4a and the optical fibers 24 are fused. The optical fiber cable 1 and the optical fiber 24 of the other optical fiber cable 20 are finally connected.
In many cases, a post-branch construction method such as covering the connection portion with and with the closure 25 was adopted. Such a conventional post-branching method has a drawback that the work efficiency is poor because the work is complicated.

The present invention has been made in view of the above circumstances, and provides an optical fiber cable capable of efficiently performing a post-branching operation for branching an optical fiber from a laid optical fiber cable, and a branching method thereafter. Especially.

[0010]

In the optical fiber cable according to the first aspect of the present invention, at least one optical fiber unit drawing pipe is inserted into the sheath, and the optical fiber unit is inserted into the pipe. The optical fiber cable is characterized in that a lubricating layer is provided on at least one of an inner surface of the optical fiber unit drawing pipe and an outermost surface of the optical fiber unit.

In the optical fiber cable according to the present invention, at least one of the optical fiber unit drawing pipes is integrated by an integrated layer made of a covering material, and the optical fiber unit is inserted into the pipe. The optical fiber cable is characterized in that a lubricating layer is provided on at least one of an inner surface of the optical fiber unit drawing pipe and an outermost surface of the optical fiber unit.

According to a third aspect of the present invention, there is provided a post branching method for an optical fiber cable, wherein the optical fiber cable according to the first or second aspect is used, and a pipe for introducing an optical fiber unit at a position where the optical fiber cable is desired to be post branched is provided. The optical fiber unit drawing pipe in which the optical fiber unit to be exposed and branched after is inserted is selected, and only the pipe or the pipe and the optical fiber unit are cut,
Compressed gas is sent into the optical fiber unit drawing pipe cut from the end of the optical fiber cable, and the optical fiber unit is propelled by being placed on the flow of the compressed gas, and the optical fiber is cut from the cut part of the optical fiber unit drawing pipe. It is characterized in that the unit is taken out to a desired length. The optical fiber cable post-branching method according to claim 4 uses the optical fiber cable according to claim 1 or 2 to expose the optical fiber unit drawing pipe at a position where the optical fiber cable is to be branched later. The optical fiber unit drawing pipe through which the optical fiber unit to be branched later is selected, and only the pipe or the pipe and the optical fiber unit are cut, and the optical fiber unit is cut to a desired length from the cut part of the optical fiber unit drawing pipe. It is characterized by pulling out.

[0013]

In the optical fiber cable of the present invention, since the lubricating layer is provided on at least one of the inner surface of the optical fiber unit drawing pipe and the outermost surface of the optical fiber unit, the optical fiber unit drawing pipe is provided. Since at least one of the optical fiber unit and the optical fiber unit has excellent surface lubricity, the optical fiber unit can be used when propelling the optical fiber unit in the drawing pipe in the flow of the compressed gas in the post-branching work. It is easy to smoothly propel the optical fiber unit without damaging the optical fiber unit, and it becomes possible to take out the optical fiber unit from the cut portion of the optical fiber unit drawing pipe by a desired length.

In the post-branching method of the optical fiber cable of the present invention, the above-mentioned optical fiber cable is used, and the pipe for introducing the optical fiber unit at a position where the optical fiber cable is desired to be post-branched is exposed and post-branched. The optical fiber unit lead-in pipe through which the optical fiber unit is inserted is selected, only the pipe or the pipe and the optical fiber unit are cut, and compressed into the optical fiber unit lead-in pipe cut from the end of the optical fiber cable. A gas is fed, the compressed optical gas is placed on the air flow to propel the optical fiber unit, and a desired length of the optical fiber unit is taken out from the cut portion of the pipe for drawing in the optical fiber unit. It is possible to secure a sufficient connection length of the unit. Furthermore, since the friction coefficient between the optical fiber unit drawing pipe and the optical fiber unit is small, when the overall length of the optical fiber unit to be branched later is not very long, the optical fiber unit drawing pipe is used. It is also possible to easily pull out the above optical fiber unit from the cutting part of the hand,
It is possible to secure the extra connection length of the optical fiber unit at the position where the branch is desired to be made.

[0015]

EXAMPLES Examples of the present invention will be described in detail below. FIG. 1 shows an embodiment of the optical fiber cable according to claim 1 of the present invention, in which reference numeral 30 is an optical fiber cable. The optical fiber cable 30 includes a tension member 32, a coating layer 33, and an optical fiber unit drawing pipe (hereinafter referred to as a drawing pipe) 3.
4, an optical fiber unit 35, a cushioning material 36, and a sheath 37.

The tension bar 32 is made of twisted steel wire, tensile strength fiber or the like, and a coating layer 33 is provided around the tension member 32. A plurality of drawing pipes 34 ... Are twisted around the coating layer 33.

The lead-in pipe 34 is made of a resin composition composed of polyethylene and a silicone resin, a resin composition composed of polyethylene and a finely powdered fluororesin, and polyethylene and an ultrahigh molecular weight polyethylene having a molecular weight of 1,000,000 or more. And a resin composition containing as an essential component a lubricating resin (A) and a resin (B) having an affinity capable of uniformly dispersing the lubricating resin (A) in a softened state or a molten state. The pipe itself is formed by molding a resin composition by a molding method such as extrusion molding, or the pipe itself has a lubricating layer formed of the above resin composition on at least the inner surface thereof.

The silicone resin to be mixed with the above-mentioned polyethylene has a molecular weight of several hundreds of thousands or more, preferably 3
A polymer having a high degree of polymerization of 0,000 or more is preferably used. Also,
The mixing ratio of the silicone resin is preferably about 5 to 50% by weight. As the fluororesin fine powder to be mixed with the above-mentioned polyethylene, polytetrafluoroethylene or the like is preferable, and the particle size of the fluororesin fine powder is 10 to 100 μm.
The thing of about m is used. The mixing ratio of the ultra high molecular weight polyethylene to the polyethylene is preferably about 5 to 50% by weight.

As the above-mentioned lubricating resin (A), polyorganosiloxane having an average molecular weight of 100,000 or more, a block copolymer of polyorganosiloxane and a polyolefin such as polyethylene, a tetrafluoroethylene-perfluorovinyl ether copolymer ( Examples thereof include fluororesins such as PFA) and copolymers of fluororesins with other resins.

The resin (B) has an affinity with the above-mentioned lubricating resin (A) so that it can be uniformly dispersed in the softened state or the molten state. put it here,
The meaning of "having an affinity capable of being uniformly dispersed" is that both resins (A) and (B) are mixed in a softened state or a molten state,
When kneaded, it means that they are mutually uniformly dispersed or evenly compatible. Further, since the resin (B) is for improving the mechanical properties and molding processability of the lubricating resin (A), a resin having good mechanical properties and molding processability is used. As the specific resin (B), when polyorganosiloxane or a copolymer thereof is used for the lubricating resin (A), linear low-density polyethylene having a molecular weight of 100,000, polypropylene, or the like is preferably used. . When a fluororesin or its copolymer is used as the lubricating resin (A), an ethylene-based resin such as linear low-density polyethylene, polypropylene or polyethylene is preferable.

If necessary, the resin composition forming the lubricating layer may include an ultraviolet absorber, an antioxidant, an antistatic colorant,
Flame retardants and lubricants can also be added.

The drawing-in pipe 34 may have an elliptical shape or a rectangular tube shape in addition to a circular cross-section, and further, a large number of ridges extending in the longitudinal direction are formed on the inner wall surface of the drawing pipe 34 to The structure may be such that the contact area with the fiber unit 35 is reduced. Alternatively, the inner surface thereof may be coated with a lubricating layer made of the above resin composition by a two-layer extrusion method or the like. In addition, the pull-in pipe 3
Examples of the twisting method of 4 ... include unidirectional twisting such as S twisting and Z twisting, and SZ twisting, but it is preferable to use SZ twisting. Such a pull-in pipe 3
An optical fiber unit 35 is inserted in each of 4 ...

FIG. 2 shows an example of the optical fiber unit 35. The optical fiber unit 35 of this example is formed by integrating a plurality of optical fiber wires 38 with a primary coating layer 39 and a secondary coating layer 40. The primary coating layer 39 is formed by using nylon or the like, and its thickness is about 100 to 200 μm when the drawing pipe 34 for inserting the optical fiber unit 35 has an outer diameter of 8 mm and an inner diameter of 6 mm. Is. Secondary coating layer 40
Is the one formed by using the resin composition forming the above-mentioned lubricating layer, or the one in which the lubricating layer formed by the resin composition is formed on at least the outermost surface thereof. The thickness of the secondary coating layer 40 is about 0.4 to 1.0 mm, though it depends on the thickness of the primary coating layer 39. The secondary coating layer 40 as described above can be formed around the primary coating layer 39 by a molding method such as extrusion molding.

The tension members 32 ...
And a coating layer 33 formed around this and this coating layer 3
Pulling pipe 34 twisted around the circumference of 3 ...
Are inserted into the sheath 37. The sheath 37
Is a cylindrical shape made of polyethylene, polyvinyl chloride, or the like, and the space inside the sheath 37 is filled with a cushioning material 36 made of a mineral oil-based viscous substance or the like.

In such an optical fiber cable 30, since the lubricating layer is provided on the inner surface of the pull-in pipe 34 and the outermost surface of the optical fiber unit 35, the pull-in pipe 34 and the optical fiber unit 35 are excellent. Since it has a surface lubricity, when the optical fiber unit 35 is propelled by the compressed gas flow in the pull-in pipe 34 in the post-branching work, the optical fiber unit 35 is easily propelled smoothly, The desired length of the optical fiber unit 35 can be taken out from the cut portion of the pull-in pipe 34.

Next, such an optical fiber cable 30
An example of the post-branching method will be described with reference to FIG. First, after laying the optical fiber cable 30, FIG.
As shown in (3), the sheath 37 and the cushioning material 36 at the position where the optical fiber cable 30 is to be branched are removed to expose the bundle of the pull-in pipes 34. Then, Fig. 3
An optical fiber unit 3 for branching as shown in FIG.
The pull-in pipe 34a through which 5a is inserted is selected, and only the pull-in pipe 34a or the pipe 34a and the optical fiber unit 35a (only the pull-in pipe 34a in the drawing) is cut along the line IV. Then, Fig. 3
As shown in (C), compressed gas 41 is introduced into the pull-in pipe 34a cut from the end of the optical fiber cable 30.
Of the compressed gas 41, the optical fiber unit 35a is propelled by the compressed air 41, and the desired length of the optical fiber unit 35a is taken out from the cut portion 42 of the pull-in pipe 34a as shown in FIG. 3D. Then, the optical fiber unit 35a and the optical fibers of other optical fiber cables to be connected thereto are connected by a fusion splicing method or the like, and finally the coating removal portion of the optical fiber cable 30 and the optical fibers of other optical fiber cables are connected. Cover the connection with a closure.

According to the post branching method of the optical fiber cable as described above, the length L ₂ of the coating removal portion of the optical fiber cable 30 is the length L ₂ of the coating removal portion of the conventional optical fiber cable 1 shown in FIG. _Even if it is the same length as ₁ ,
Since it is possible to secure a sufficient extra connection length of the optical fiber unit at the position to be branched later, it is not necessary to perform work such as cutting the tension member unlike the conventional branching method of the optical fiber cable. There is an advantage that the work of the rear branch becomes easy and the work efficiency is improved. If the overall length of the optical fiber unit 35a to be branched later is not too long, only the pull-in pipe 34a or the pipe 34a and the optical fiber unit 35a are cut and then compressed gas is fed into the pull-in pipe 34a. Pipe 34a for pulling in without feeding
From the cutting portion 35 of the optical fiber unit 3 by hand or the like
Since 5a can be easily pulled out, it is possible to secure the extra connection length of the optical fiber unit at a position where the optical fiber unit is to be branched later.

In the above embodiment, an example in which a lubricating layer is provided on the inner surface of the pull-in pipe 34 and the outermost surface of the optical fiber unit 35 has been described, but the inner surface of the pull-in pipe 34 and the optical fiber are described. A unit having a lubricating layer provided on at least one of the outermost surfaces of the unit 35 may be used. Further, even if the optical fiber unit 35 is mounted on the optical fiber cable 30 in advance at the time of manufacturing the cable, the pipe for drawing the optical fiber unit 35 from the end of the installed optical fiber cable 30 with compressed gas is used. It may be pumped into the container 34.

FIG. 4 shows an embodiment of the optical fiber cable according to claim 2 of the present invention. The optical fiber cable 50 shown in FIG. 4 is different from the optical fiber cable 30 shown in FIG. The point is that the tension member members 32, 32 are arranged in parallel on both sides of the pull-in pipe 34 in which the optical fiber unit 35 is inserted, and they are integrated by an integrated layer 51 made of a covering material. As the covering material forming the integrated layer 51, high density polyethylene, medium density polyethylene, or the like is used.

With such an optical fiber cable 50, the post-branching work can be performed in substantially the same manner as the post-branching method of the optical fiber cable 30 described above. Also, the same effect as the post-branch construction method of the optical fiber cable 30 can be obtained.

Also, in this embodiment, the integrated layer 51
Although the description has been given of the example in which the number of the drawing pipes 34 covered with is one, the number of the drawing pipes may be two or more.

[0032]

As described above, according to the optical fiber cable of the present invention, the lubricating layer is provided on at least one of the inner surface of the optical fiber unit drawing pipe and the outermost surface of the optical fiber unit. Since at least one of the optical fiber unit inlet pipe and the optical fiber unit has excellent surface lubricity, the optical fiber unit is propelled by the compressed gas flow in the inlet pipe during the post branch work. At this time, the optical fiber unit can be easily propelled smoothly, and the optical fiber unit can be taken out from the cut portion of the optical fiber unit drawing pipe by a desired length.

According to the post-branching method of the optical fiber cable of the present invention, the above-mentioned optical fiber cable is used to expose the optical fiber unit lead-in pipe at the position where the optical fiber cable is to be post-branched and post-branch. A pipe for introducing the optical fiber unit into which the optical fiber unit is inserted is selected, and only the pipe or the pipe and the optical fiber unit are cut, and a compressed gas is introduced into the pipe for introducing the optical fiber unit cut from the end of the optical fiber cable. Of the compressed gas, the optical fiber unit is propelled on the compressed gas flow, and the optical fiber unit is taken out at a desired length from the cut portion of the optical fiber unit drawing pipe, so that the optical fiber unit can be branched at a position to be branched later. Since it is possible to secure a sufficient connection extra length, There is no need to perform operations such as cutting the tension member as branching method after the optical fiber cable, therefore it is easy to work the rear branch, there is an advantage of improving the working efficiency.

When the total length of the optical fiber unit to be branched later is not very long, only the pull-in pipe in which the optical fiber unit is inserted or the pipe and the optical fiber unit are cut and then pulled in. Since the optical fiber unit can be easily pulled out from the cut portion of the above-mentioned pipe for drawing without sending compressed gas into the pipe, a surplus connection length of the optical fiber unit can be secured at the position to be branched later. be able to.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the optical fiber cable according to claim 1 of the present invention.

FIG. 2 is a sectional view showing an example of an optical fiber unit used in the optical fiber cable shown in FIG.

3A to 3D are diagrams showing the post-branching construction method of the optical fiber cable shown in FIG. 1 in the order of steps.

FIG. 4 is a sectional view showing an embodiment of the optical fiber cable according to claim 2 of the present invention.

5A is a cross-sectional view showing an example of a conventional optical fiber cable, and FIG. 5B is a perspective view.

6A is a cross-sectional view showing another example of a conventional optical fiber cable, and FIG. 6B is a perspective view.

FIG. 7 is a diagram for explaining a rear branching method of the optical fiber cable shown in FIG.

8A to 8B are views for explaining an actual post-branching method of the optical fiber cable shown in FIG.

[Explanation of symbols]

30 ... Optical fiber cable, 34 ... Pull-in pipe, 34a ... Pull-in pipe, 35 ... Optical fiber unit, 35a ... Optical fiber unit, 37 ... Sheath, 41 ... Compressed gas, 42 ... Cutting part, 50 ... Optical fiber cable, 51 ... Integrated layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Mogi 1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Co., Ltd.Sakura Plant (72) Inventor Koichiro Watanabe 1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Sakura Plant, Inc. ( 72) Inventor Suehiro Miyamoto 1440 Rokuzaki, Sakura City, Chiba Fujikura Ltd. Sakura Factory (72) Inventor Shigekazu Hayami 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (4)

[Claims] 1. An optical fiber cable in which one or more optical fiber unit drawing pipes are inserted into a sheath, and an optical fiber unit is inserted into the pipe, wherein an inner surface of the optical fiber unit drawing pipe and An optical fiber cable, wherein a lubricating layer is provided on at least one of the outermost surfaces of the optical fiber unit. 2. One or more of the optical fiber unit drawing pipes are integrated by an integrated layer made of a covering material,
An optical fiber cable having an optical fiber unit inserted in the pipe, wherein a lubricating layer is provided on at least one of an inner surface of the optical fiber unit drawing pipe and an outermost surface of the optical fiber unit. And optical fiber cable. 3. The optical fiber cable according to claim 1 is used, and the pipe for drawing in the optical fiber unit at a position where the optical fiber cable is to be branched is exposed.
In the optical fiber unit pull-in pipe cut out from the end of the optical fiber cable, selecting the pipe for pulling in the optical fiber unit through which the optical fiber unit to be branched later is inserted, and cutting only the pipe or the pipe and the optical fiber unit A compressed gas is sent to the optical fiber unit, the optical fiber unit is propelled by being placed on the flow of the compressed gas, and the optical fiber unit is taken out from the cut portion of the optical fiber unit drawing pipe to a desired length. Branching method. 4. The optical fiber cable according to claim 1, wherein the optical fiber unit drawing pipe is exposed at a position where the optical fiber cable is to be branched after the optical fiber cable.
The optical fiber unit lead-in pipe in which the optical fiber unit to be branched later is inserted is selected, only the pipe or the pipe and the optical fiber unit are cut, and the optical fiber unit is desired from the cut portion of the optical fiber unit lead-in pipe. A post-branch construction method for optical fiber cables that is characterized by drawing out the length.