JP2022010112A - How to disassemble the optical fiber cable and the optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve workability of ripping a reinforcement sheet and an external sheath and increase efficiency of manufacturing an optical fiber cable.

SOLUTION: An optical fiber cable 1A includes: a cable body having a core 11 and an internal sheath 14 for containing the core; a reinforcement sheet 20 surrounding the cable body; an external sheath 30 for containing the cable body and the reinforcement sheet; and an external lip cord 12 buried in the internal sheath. The internal sheath has a protrusion part 15 protruding to an outside in a radial direction, and at least a part of the external lip cord is located in an inside of the protruding part.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to a method for disassembling an optical fiber cable and an optical fiber cable.

Conventionally, an optical fiber cable as shown in Patent Document 1 below has been known. This optical fiber cable includes a cable body having an optical fiber, a ripcord, a reinforcing sheet, and an external sheath. The reinforcing sheet surrounds the cable body and prevents the cable body from being bitten by a mouse or a squirrel and damaging the optical fiber. The ripcord is provided in the gap between the cable body and the reinforcing sheet, and is used to tear the reinforcing sheet and the outer sheath when disassembling the optical fiber cable or performing intermediate post-branching work.

Japanese Unexamined Patent Publication No. 2017-72801

By the way, in recent years, for example, a short optical fiber cable having a total length of about 1 m may be used. When the optical fiber cable is short in this way, even if an attempt is made to tear the reinforcing sheet and the outer sheath using the ripcord, the ripcord will suddenly come out of the optical fiber cable and the tearing operation cannot be performed normally. There was a case. In particular, in the configuration of Patent Document 1, the ripcord is arranged in the gap between the cable body and the reinforcing sheet, and the ripcord is easily pulled out during the tearing operation.
Further, when the reinforcing sheet is rolled and has an overlapping portion, if the ripcord is located inside the overlapping portion, the force required to tear the reinforcing sheet becomes extremely large. Therefore, even if an attempt is made to position the ripcord at a position other than the inside of the overlapping portion of the reinforcing sheet during the manufacture of the optical fiber cable, the position of the ripcord is not stable in the configuration of Patent Document 1 and the manufacturing efficiency is lowered. It was.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to improve the tearing workability of the reinforcing sheet and the outer sheath and to improve the manufacturing efficiency of the optical fiber cable.

In order to solve the above problems, the optical fiber cable according to the first aspect of the present invention includes a cable body having a core and an internal sheath for accommodating the core, a reinforcing sheet surrounding the cable body, and the cable body. And an outer sheath accommodating the reinforcing sheet and an outer ripcord embedded in the inner sheath, the inner sheath is formed with a protrusion protruding outward in the radial direction, and the outer ripcord is formed. At least a part of the above is located inside the protrusion.

According to the first aspect, the reinforcing sheet and the outer ripcord for tearing the outer sheath are embedded in the inner sheath. Therefore, the pulling force when pulling out the outer ripcord from the inside of the optical fiber cable is increased, and it is possible to prevent the outer ripcord from being unexpectedly pulled out during the tearing operation. Further, since at least a part of the outer ripcord is located inside the protrusion, the outer ripcord can be pinched together with the protrusion by using a tool or the like, and the outer ripcord can be taken out to the outside of the outer sheath. .. Therefore, it is possible to facilitate the tearing work using the outer ripcord.
In addition, the outer ripcord is secured within the inner sheath, which stabilizes the position of the outer ripcord during fiber optic cable manufacturing. As a result, it becomes easy to manufacture the optical fiber cable so that the outer ripcord is located in the region other than the inside of the overlapping portion of the reinforcing sheet, and the manufacturing efficiency can be improved.

According to the above aspect of the present invention, the tearing workability of the reinforcing sheet and the outer sheath can be improved, and the manufacturing efficiency of the optical fiber cable can be improved.

It is sectional drawing of the optical fiber cable which concerns on 1st Embodiment. It is sectional drawing of the optical fiber cable which concerns on 2nd Embodiment. It is a figure explaining the work of taking out a core from the optical fiber cable of FIG. It is sectional drawing of the optical fiber cable which concerns on the modification of 2nd Embodiment. It is sectional drawing of the optical fiber cable which concerns on 3rd Embodiment. It is sectional drawing of the optical fiber cable which concerns on 4th Embodiment. It is sectional drawing of the optical fiber cable which concerns on the modification of 4th Embodiment. It is sectional drawing of the optical fiber cable which concerns on 5th Embodiment. It is sectional drawing of the optical fiber cable which concerns on the modification of 5th Embodiment. It is sectional drawing of the optical fiber cable which concerns on other modification of 5th Embodiment.

(First Embodiment)
Hereinafter, the configuration of the optical fiber cable according to the first embodiment will be described with reference to FIG. In each drawing used in the following description, the scale is appropriately changed in order to make each member a recognizable size.
As shown in FIG. 1, the optical fiber cable 1A includes a cable body 10A having an optical fiber, a reinforcing sheet 20, and an external sheath 30.

Here, in the present embodiment, the longitudinal direction of the cable body 10A is simply referred to as the longitudinal direction, and the central axis of the cable body 10A is simply referred to as the central axis O. Further, a cross section orthogonal to the central axis O is referred to as a cross section. In cross-sectional view, the direction orthogonal to the central axis O is called the radial direction, and the direction orbiting around the central axis O is called the circumferential direction.

The cable body 10A has a core 11, a pair of outer ripcords 12, a pair of tensile strength bodies (tension members) 13, and an inner sheath 14.
The core 11 extends in the longitudinal direction. The core 11 is configured by assembling a plurality of optical fibers. As the optical fiber constituting the core 11, an optical fiber wire, an optical fiber core wire, an optical fiber tape core wire, or the like can be used. The plurality of optical fibers constituting the core 11 are bound by a binding material in a bundled state, for example. The plurality of optical fibers may be covered with a presser roll or a water absorbing tape (sheet). The cross-sectional shape of the core 11 is not particularly limited, and may be circular, elliptical, or rectangular.

The pair of tensile strength bodies 13 are embedded in the inner sheath 14 so as to sandwich the core 11 in the cross-sectional view. Each tensile strength body 13 extends in the longitudinal direction. Each tensile strength body 13 may be arranged parallel to the core 11 in the longitudinal direction, or may be arranged in a spiral shape centered on the core 11.
The tensile strength body 13 has a role of protecting the optical fiber of the core 11 from the tension acting on the optical fiber cable 1A. The material of the tensile strength body 13 is, for example, a metal wire (steel wire or the like), a tensile strength fiber (aramid fiber or the like), FRP or the like. The tensile strength body 13 may be a single wire, or may be a bundle of a plurality of strands or twisted to each other.

In the cross-sectional view, the straight line connecting the centers of the pair of tensile strength bodies 13 is referred to as a neutral line L. When the optical fiber cable 1A is bent in a direction perpendicular to the neutral line L (vertical direction in FIG. 1), the expansion and contraction of the tensile strength body 13 becomes smaller as compared with the case where the optical fiber cable 1A is bent in the other direction. .. Therefore, the optical fiber cable 1A is relatively easy to bend in the direction perpendicular to the neutral wire L.
The cable body 10A may include three or more tensile strength bodies 13. When three or more tensile strength bodies 13 are arranged at equal intervals in the circumferential direction, the bending direction of the cable body 10A becomes small, and the optical fiber cable 1A can be handled more easily.

The inner sheath 14 collectively covers the core 11 and the pair of tensile strength bodies 13. As the material of the inner sheath 14, a resin such as polyethylene (PE) or polyvinyl chloride (PVC) can be used.
The inner sheath 14 is formed in a substantially columnar shape. A pair of protrusions 15 projecting outward in the radial direction are formed on the outer peripheral surface of the inner sheath 14. The inner sheath 14 and the pair of protrusions 15 are integrally formed by extrusion molding or the like. The pair of protrusions 15 are arranged at equal intervals in the circumferential direction. In the cross-sectional view, the pair of protrusions 15 are located on a straight line orthogonal to the straight line connecting the pair of tensile strength bodies 13. Each protrusion 15 is formed in a substantially semicircular shape in a cross-sectional view.

The outer ripcord 12 is used when tearing the reinforcing sheet 20 and the outer sheath 30 (hereinafter, simply referred to as tearing work). The outer ripcord 12 is required to have sufficient mechanical strength (for example, tensile strength) to tear the reinforcing sheet 20 and the outer sheath 30.
The pair of outer ripcords 12 are located on a straight line orthogonal to the straight line connecting the pair of tensile strength bodies 13 in a cross-sectional view. Each outer ripcord 12 extends longitudinally. As the outer ripcord 12, a string obtained by twisting synthetic fibers such as polyester and aramid can be used. The outer ripcord 12 is embedded in the protrusion 15 of the inner sheath 14 and is located inside the protrusion 15. In this embodiment, the outer ripcord 12 is not exposed to the outside of the protrusion 15 in cross-sectional view. Therefore, even if the inner sheath 14 and the protrusion 15 are extruded and then cooled in a water tank, it is possible to prevent water from penetrating into the outer ripcord 12.

The reinforcing sheet 20 extends in the longitudinal direction and is formed in a cylindrical shape surrounding the cable body 10A. As the material of the reinforcing sheet 20, a metal such as stainless steel, copper, or a copper alloy can be used. Further, a fiber sheet using glass fiber, aramid fiber or the like, FRP or the like may be used as the reinforcing sheet 20. It is desirable that the reinforcing sheet 20 is in the form of a tape, for example, and is provided so that the length direction is aligned with the length direction of the cable body 10A. The thickness of the reinforcing sheet 20 is, for example, about 0.1 to 0.3 mm. By setting the thickness of the reinforcing sheet 20 within this range, it is possible to prevent the optical fiber of the core 11 from being damaged by feeding damage of animals, and to facilitate the operation of tearing the reinforcing sheet 20 by the outer ripcord 12. ..

The reinforcing sheet 20 surrounds the cable body 10A over the entire circumference and is overlapped in a part in the circumferential direction. The portion on which the reinforcing sheets 20 are overlapped is referred to as an overlapping portion 20a.
Here, as described above, the optical fiber cable 1A tends to bend in the direction perpendicular to the neutral line L. Therefore, for example, when the overlapping portion 20a is located on the neutral line L, the overlapping portion 20a and the external sheath 30 are relatively easy to move when handling the optical fiber cable 1A. When the overlapping portion 20a and the outer sheath 30 move relatively, the side edge 20b of the reinforcing sheet 20 on the outer peripheral side of the overlapping portion 20a may damage the inner surface of the outer sheath 30. Therefore, in the present embodiment, in the cross-sectional view, the side edge 20b of the reinforcing sheet 20 on the outer peripheral side of the overlapping portion 20a and the tensile strength body 13 are arranged at different positions in the circumferential direction.
Further, in the present embodiment, in the cross-sectional view, the entire overlapping portion 20a and the tensile strength body 13 are arranged at different positions in the circumferential direction. As a result, the distance between the side edge 20b and the neutral line L becomes large, and the inner surface of the outer sheath 30 can be more reliably suppressed from being damaged.

The first adhesive film 21 is attached to the surface of the reinforcing sheet 20 facing the cable body 10A, and the second adhesive film 22 is attached to the surface of the reinforcing sheet 20 facing the outer sheath 30. As the adhesive used for the first adhesive film 21 and the second adhesive film 22, for example, a thermosetting adhesive can be used. The material of the adhesive may be changed as appropriate. The second adhesive film 22 has a role of fixing the outer sheath 30 to the reinforcing sheet 20. Further, of the first adhesive film 21 and the second adhesive film 22, a portion of the overlapping portion 20a located between the reinforcing sheets 20 plays a role of fixing the reinforcing sheets 20 to each other at the overlapping portion 20a.

The outer sheath 30 houses the cable body 10A and the reinforcing sheet 20. The outer sheath 30 is formed in a cylindrical shape extending in the longitudinal direction. As the material of the outer sheath 30, a resin such as polyethylene (PE) or polyvinyl chloride (PVC) can be used.

When the core 11 is taken out from the optical fiber cable 1A, first, the outer sheath 30 and the reinforcing sheet 20 are partially cut open by a tool such as a cutter. Next, a tool such as pliers is inserted from the cut-out portion, the outer ripcord 12 is sandwiched together with the protrusion 15, and the outer sheath 30 is pulled out. By this operation, the reinforcing sheet 20 and the outer sheath 30 are torn by the outer ripcord 12 extending in the longitudinal direction, and the cable body 10A can be taken out. Then, the core 11 can be taken out by cutting open the cable body 10A.

According to the optical fiber cable 1A having the above-described configuration, the reinforcing sheet 20 and the outer ripcord 12 for tearing the outer sheath 30 are embedded in the protrusion 15 of the inner sheath 14. Therefore, the pulling force when pulling out the outer ripcord 12 from the inside of the optical fiber cable 1A becomes large, and it is possible to prevent the outer ripcord 12 from being unexpectedly pulled out during the tearing operation. Therefore, it is possible to facilitate the tearing work using the outer ripcord 12.

Further, since the outer ripcord 12 is fixed in the protrusion 15, the position of the outer ripcord 12 is stabilized at the time of manufacturing the optical fiber cable 1A. As a result, it becomes easy to manufacture the optical fiber cable 1A so that the outer ripcord 12 is located in a region excluding the radial inner side of the overlapping portion 20a of the reinforcing sheet 20, and the manufacturing efficiency can be improved.

(Second Embodiment)
Next, the second embodiment according to the present invention will be described, but the basic configuration is the same as that of the first embodiment. Therefore, the same reference numerals are given to the same configurations, the description thereof will be omitted, and only the different points will be described.
The optical fiber cable 1B of the second embodiment is a further improvement of the optical fiber cable 1A of the first embodiment, and the work of taking out the core 11 after tearing the reinforcing sheet 20 and the outer sheath 30 is performed. It's getting easier.

As shown in FIG. 2, the cable body 10B of the present embodiment has a pair of inner ripcords 16 in addition to the pair of outer ripcords 12. The inner ripcord 16 is embedded in the radial inner portion of the protrusion 15 and the outer ripcord 12 in the inner sheath 14. Therefore, the wall thickness of the root portion 15b of the protrusion portion 15 is thin, and the protrusion portion 15 is broken from the root portion 15b as a starting point, and is easily separated from the internal sheath 14.

The inner ripcord 16 is in contact with the core 11. When the outer diameter of the inner ripcord 16 is d and the thickness of the portion of the inner sheath 14 where the protrusion 15 is not formed is t, d ≧ t is satisfied. The optical fiber cable 1B does not have to satisfy d ≧ t.
As the material of the inner ripcord 16, a string made of synthetic fibers such as polyester and aramid, a columnar rod made of PP or nylon, or the like can be used.

The protrusion 15 of the present embodiment is formed in a substantially rectangular shape in a cross-sectional view. In the cross-sectional view, the side surface 15a of the protrusion 15 is formed in a straight line. Further, the side surface 15a is inclined so that the width W of the protrusion 15 in the circumferential direction gradually increases toward the outside in the radial direction. That is, the side surface 15a of the protrusion 15 is formed in a so-called reverse taper shape. As a result, tensile stress is likely to be concentrated on the root portion 15b of the protrusion portion 15.

Next, a procedure for taking out the core 11 from the inside of the optical fiber cable 1B having the above configuration will be described.

First, the outer sheath 30 and the reinforcing sheet 20 are partially incised using a tool such as a cutter. Next, as shown in FIG. 3A, an existing tool K such as pliers is inserted into the reinforcing sheet 20 through the incised portion. Then, the outer lip cord 12 is sandwiched together with the protrusion 15 by the tool K. At this time, since the width W in the circumferential direction of the protrusion 15 gradually increases toward the outer side in the radial direction, the tool K holding the protrusion 15 is unlikely to come off from the protrusion 15.

Next, as shown in FIG. 3B, the tool K is pulled up while the protrusion 15 is sandwiched. As a result, tensile stress is concentrated on the root portion 15b of the protrusion portion 15, breakage occurs starting from the root portion 15b, and the protrusion portion 15 and the internal sheath 14 are separated. As a result, the outer ripcord 12 together with the protrusion 15 can be pulled out to the outside of the outer sheath 30. Then, by continuously pulling up the outer ripcord 12, the reinforcing sheet 20 and the outer sheath 30 can be torn by the outer ripcord 12.

When the reinforcing sheet 20 and the outer sheath 30 are torn along the longitudinal direction using the outer ripcord 12, the protrusion 15 is pulled away from the inner sheath 14 together with the outer ripcord 12. Therefore, the protrusion 15 is also separated from the internal sheath 14 along the longitudinal direction.
Here, the inner ripcord 16 is in contact with the core 11, and the outer diameter d of the inner ripcord 16 is equal to or larger than the thickness t of the inner sheath 14. Therefore, when the protrusion 15 and the internal sheath 14 are divided along the longitudinal direction, the internal sheath 14 is naturally divided into two as shown in FIG. 3 (c). As a result, the core 11 can be easily taken out.

As described above, according to the optical fiber cable 1B of the present embodiment, the inner ripcord 16 is arranged in addition to the outer ripcord 12, and the reinforcing sheet 20 and the outer sheath 30 are provided by using the outer ripcord 12. By tearing, the internal sheath 14 is naturally divided into two. Therefore, the core 11 can be easily taken out during the dismantling work of the optical fiber cable 1B, the intermediate post-branching work, and the like, and the work efficiency can be improved.

Further, the width W in the circumferential direction of the protrusion 15 increases toward the outside in the radial direction. With this configuration, the protrusion 15 can be easily sandwiched by the tool K, and the tensile stress can be easily concentrated on the root portion 15b of the protrusion 15. Therefore, it becomes easier to pull out the outer ripcord 12 together with the protrusion 15 to the outside of the outer sheath 30.

Further, since the inner diameter d of the inner ripcord 16 and the thickness t of the inner sheath 14 satisfy d ≧ t, the inner sheath 14 is more reliably divided when the protrusion 15 and the inner sheath 14 are separated. Can be made to.

In FIG. 2, a pair of inner ripcords 16 and a pair of outer ripcords 12 are arranged in a straight line in a cross-sectional view, but the present invention is not limited to this. For example, as shown in FIG. 4, the outer ripcord 12 may be arranged at a position shifted in the circumferential direction with respect to the inner ripcord 16. Even in this case, since the wall thickness at the root portion 15b of the protrusion portion 15 is thin, breakage is likely to occur starting from the root portion 15b, and the inner ripcord 16 can be easily exposed.

(Third Embodiment)
Next, the third embodiment according to the present invention will be described, but the basic configuration is the same as that of the second embodiment. Therefore, the same reference numerals are given to the same configurations, the description thereof will be omitted, and only the different points will be described.
In the present embodiment, the waterproof performance is enhanced in consideration of the case where the optical fiber cable is installed outdoors and the case where the internal sheath 14 and the protrusion 15 are immersed in a water tank for cooling when extruded. In particular, when the outer ripcord 12 and the inner ripcord 16 are in the form of a string in which fibers are twisted, moisture permeates the outer ripcord 12 and the inner ripcord 16, and running water is generated in the cable body. There is a risk that it will end up.

Therefore, in the optical fiber cable 1C of the present embodiment, as shown in FIG. 5, the outer ripcord 12 is covered with the coating 12a. As the material of the coating 12a, a material that does not allow moisture to permeate is preferable. For example, the coating 12a may be formed by applying an adhesive resin to the outer periphery of the outer ripcord 12.

According to the present embodiment, even if the outer ripcord 12 is partially exposed from the protrusion 15 as shown in FIG. 5, it is possible to prevent water from entering the inside of the protrusion 15 through the exposed portion. can do. Therefore, it is possible to prevent running water in the cable body 10C and improve the waterproof performance.

(Fourth Embodiment)
Next, the fourth embodiment according to the present invention will be described, but the basic configuration is the same as that of the second embodiment. Therefore, the same reference numerals are given to the same configurations, the description thereof will be omitted, and only the different points will be described. In the first to third embodiments, the protrusion 15 protrudes radially outward from the outer peripheral surface of the columnar inner sheath 14. In the present embodiment, the internal sheath 14 has a shape in which a part of the cylindrical shape is removed to form a protrusion.

As shown in FIG. 6, in the optical fiber cable 1D (cable main body 10D) of the present embodiment, the first groove portion 14a1 and the second groove portion 14a2 are recessed inward in the radial direction on the outer peripheral surface of the cylindrical inner sheath 14. Is formed. The first groove portion 14a1 and the second groove portion 14a2 are arranged at intervals in the circumferential direction. The portion of the inner sheath 14 between the first groove portion 14a1 and the second groove portion 14a2 has a shape protruding outward in the radial direction. That is, in the present embodiment, the first protrusion 17a is formed by the pair of groove portions 14a1 and 14a2.

Further, a third groove portion 14a3 and a fourth groove portion 14a4 are formed on the radial opposite sides of the groove portions 14a1 and 14a2 sandwiching the core 11. The third groove portion 14a3 and the fourth groove portion 14a4 are recessed inward from the outer peripheral surface of the inner sheath 14 in the radial direction, and are arranged at intervals in the circumferential direction. The portion of the inner sheath 14 between the third groove portion 14a3 and the fourth groove portion 14a4 has a shape protruding outward in the radial direction. That is, the second protrusion 17b is formed by the pair of groove portions 14a3 and 14a4 arranged on the radial opposite sides of the pair of groove portions 14a1 and 14a2.

The inner surfaces of the grooves 14a1 to 14a4 are formed in a curved surface shape that is convex inward in the radial direction. The shapes of the grooves 14a1 to 14a4 may be changed as appropriate. For example, the grooves 14a1 to 14a4 may be triangular or rectangular in cross-sectional view. Further, the shapes of the groove portions 14a1 to 14a4 may be different from each other.

The pair of groove portions 14a1 and 14a2 forming the first protrusion 17a are arranged so as to sandwich the outer ripcord 12 in the circumferential direction. Similarly, the pair of groove portions 14a3 and 14a4 forming the second protrusion 17b are arranged so as to sandwich the outer ripcord 12 in the circumferential direction. As a result, at least a part of the outer ripcord 12 is located inside the first protrusion 17a or the second protrusion 17b.
The first protrusion 17a and the second protrusion 17b extend along the longitudinal direction. Also in this embodiment, the outer ripcord 12 can be pulled out to the outside of the outer sheath 30 by holding the first protrusion 17a or the second protrusion 17b with the tool K and pulling it up (FIGS. 3A to 3A. c) See).

In the present embodiment, a pair of inner ripcords 16, a pair of outer ripcords 12, and a pair of protrusions 17a and 17b are arranged in a straight line in a cross-sectional view. However, this arrangement may be changed as appropriate. For example, as shown in FIG. 7, the protrusions 17a and 17b (outer ripcords 12) may be arranged at positions different from the inner ripcords 16 in the circumferential direction.

(Fifth Embodiment)
Next, the fifth embodiment according to the present invention will be described, but the basic configuration is the same as that of the fourth embodiment. Therefore, the same reference numerals are given to the same configurations, the description thereof will be omitted, and only the different points will be described.
As shown in FIG. 8, in the optical fiber cable 1E (cable main body 10E) of the present embodiment, a plurality of flat surfaces 14b1 to 14b4 are formed on the inner sheath 14. The inner sheath 14 has a cylindrical shape in which a part of the outer peripheral surface is cut off. The first flat surface 14b1 and the second flat surface 14b2 are arranged so as to sandwich the first protrusion 17a in the circumferential direction. It can also be said that the first protrusion 17a is formed by a pair of flat surfaces 14b1 and 14b2. Similarly, the third flat surface 14b3 and the fourth flat surface 14b4 are arranged so as to sandwich the second protrusion 17b in the circumferential direction. It can also be said that the second protrusion 17b is formed by a pair of flat surfaces 14b3 and 14b4.

The first protrusion 17a and the second protrusion 17b extend along the longitudinal direction. Also in this embodiment, at least a part of the outer ripcord 12 is located inside the first protrusion 17a or the second protrusion 17b. Therefore, by holding the first protrusion 17a or the second protrusion 17b with the tool K and pulling it up, the outer ripcord 12 can be pulled out to the outside of the outer sheath 30 (FIGS. 3A to 3C). reference).

The flat surfaces 14b1 to 14b4 extend along the longitudinal direction. Further, in the cross-sectional view, the flat surfaces 14b1 to 14b4 extend substantially parallel to the neutral line L. However, the shapes and arrangements of the flat surfaces 14b1 to 14b4 may be appropriately changed. For example, as shown in FIG. 9, the flat surfaces 14b1 to 14b4 may be inclined surfaces gradually inward in the radial direction toward the outer ripcord 12 in the circumferential direction. Further, as in FIG. 7 in the fourth embodiment, the protrusions 17a and 17b (outer ripcords 12) may be arranged at positions different from those of the inner ripcords 16 in the circumferential direction.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, the protrusion 15, the outer ripcord 12, and the inner ripcord 16 are provided by two each, but the number of these may be changed as appropriate.

In addition, it is possible to appropriately replace the components in the above-described embodiment with well-known components without departing from the spirit of the present invention, and the above-described embodiments and modifications may be appropriately combined.

For example, the shape of the protrusion 15 in the second embodiment may be applied to the optical fiber cable 1A in the first embodiment. Even in this case, the same effects as those described in the second embodiment can be obtained.
Further, the outer ripcord 12 in the optical fiber cable 1A of the first embodiment may be covered with the coating 12a.

Further, as shown in FIG. 10, the third embodiment and the fifth embodiment are combined, and as shown in FIG. 10, the outside from the protrusions 17a and 17b sandwiched between the flat surfaces 14b1 and 14b2 or the flat surfaces 14b3 and 14b4 which are inclined surfaces. The ripcord 12 may be exposed. Then, the outer ripcord 12 may be covered with the coating 12a. In this case, the outer ripcord 12 can be easily taken out, and even if the cable body 10E is immersed in cooling water, water is prevented from entering the inside of the outer ripcord 12 and the insides of the protrusions 17a and 17b. Be done.

1A to 1E ... Optical fiber cable 10A to 10E ... Cable body 11 ... Core 12 ... Outer ripcord 12a ... Coating 13 ... Tensile body 14 ... Inner sheath 14a1 to 14a4 ... Groove 14b1 to 14b4 ... Flat surface 15 ... Projection 16 ... Inner Ripcords 17a, 17b ... Protrusions 20 ... Reinforcing sheet 30 ... External sheath

Claims (9)

A cable body having a core and an internal sheath for accommodating the core, a reinforcing sheet surrounding the cable body, an external sheath for accommodating the cable body and the reinforcing sheet, and an outer ripcord embedded in the internal sheath. A method of disassembling an optical fiber cable, wherein at least a part of the outer ripcord is located inside a protrusion that protrudes radially outward from the inner sheath.
A method for disassembling an optical fiber cable, in which the reinforcing sheet and the outer sheath are torn and the cable body is taken out by sandwiching the outer lip cord together with the protrusion and pulling it out to the outside of the outer sheath. A cable body having a core and an internal sheath for accommodating the core,
A reinforcing sheet that surrounds the cable body and
An external sheath that houses the cable body and the reinforcing sheet,
With an outer ripcord embedded in the inner sheath,
The inner sheath is formed with a protrusion protruding outward in the radial direction.
At least a portion of the outer ripcord is located inside the protrusion.
An optical fiber cable in which an inner ripcord is embedded in a portion of the inner sheath that is radially inner than the outer ripcord. The optical fiber cable according to claim 2, wherein at least a part of the outer ripcord is located radially outside the protrusion. The optical fiber cable according to claim 2 or 3, wherein the outer ripcord and the inner ripcord are arranged apart in the radial direction. The optical fiber cable according to any one of claims 2 to 4, wherein the outer peripheral surface of the inner sheath is circular and the side surface of the protrusion is linearly formed in a cross-sectional view. The optical fiber cable according to any one of claims 2 to 5, wherein the width of the protrusion in the circumferential direction gradually increases toward the outside in the radial direction. When the outer diameter of the inner ripcord is d and the thickness of the portion of the inner sheath in which the protrusion is not formed is t.
The optical fiber cable according to any one of claims 2 to 6, which satisfies d ≧ t. The optical fiber cable according to any one of claims 2 to 7, wherein a pair of flat surfaces are formed on the outer peripheral surface of the inner sheath so as to sandwich the protrusion in the circumferential direction. The optical fiber cable according to any one of claims 2 to 8, wherein the outer ripcord is covered with a coating.

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