JP3941753B2 - Optical fiber cable and manufacturing method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical fiber cable and a method for manufacturing the same, and more specifically, two or more optical fiber core wires are arranged at the center of a cable core, twisted together with a buffer material filled around the cable core, and the outside thereof. The present invention relates to an optical fiber cable in which a presser winding thread or tape is roughly wound and further has a jacket on the outer side thereof, and a manufacturing method thereof.
[0002]
[Prior art]
If the optical fiber cable is laid for a long period of time, the optical fiber core wire will move in the longitudinal direction in the optical fiber cable due to the expansion and contraction of the optical fiber cable due to environmental temperature changes and stress, and the vibration of the optical fiber. A phenomenon occurs in which the optical fiber core wire enters the outer sheath of the optical fiber cable or the optical fiber core wire protrudes from the end portion of the outer sheath. Such a phenomenon becomes a factor of deteriorating the transmission characteristics of the optical fiber and impairs the reliability of the optical fiber cable.
[0003]
For example, in Patent Document 1, a buffer material made of long fibers is vertically attached or twisted around the optical fiber core, and the buffer material and the optical fiber core are intermittent in the longitudinal direction. In particular, an optical fiber cable is disclosed in which an outer cover is provided outside the buffer material. According to the optical fiber cable described in Patent Document 1, the movement of the optical fiber in the optical fiber cable can be suppressed, and the transmission loss can be prevented from deteriorating even when the cable is bent. ing.
[0004]
However, in the optical fiber cable disclosed in Patent Document 1, when the optical fiber core wire is taken out from the optical fiber cable for branching, the bonded portion between the optical fiber core wire and the buffer provided intermittently is the optical fiber core. If it is included in the part where the wire is taken out, there arises a problem that the work of taking out the optical fiber core wire becomes extremely difficult.
[0005]
In the above case, it is necessary to separate the bonded optical fiber and the buffer, and to remove the adhesive adhered on the optical fiber. At that time, since there is a high possibility of causing damage such as scratches to the fiber, it is very difficult to take out the optical fiber core wire.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-59926
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and maintains the reliability of the transmission characteristics by suppressing the movement of the optical fiber core in the optical fiber cable in the longitudinal direction, and for branching. An object of the present invention is to provide an optical fiber cable in which an optical fiber core wire can be easily taken out and a method for manufacturing the same.
[0008]
[Means for Solving the Problems]
In the optical fiber cable of the present invention, two or more optical fiber core wires are twisted together with a buffer material disposed around the optical fiber core wire, a presser winding is wound around the outer side of the buffer material, and further a presser winding is wound. An optical fiber cable in which an outer jacket is provided on the outer side of the optical fiber core wire and the buffer material, and the winding pitch of the presser winding is greater than 0 mm and not more than 35 mm, and the dynamic tension at the time of winding the presser winding is from 0N This is characterized in that it is largely 2.8 N or less and the presser winding is wound in a direction opposite to the twisting direction of the optical fiber core wire.
[0009]
The optical fiber cable manufacturing method of the present invention includes a step of twisting two or more optical fiber cores together with a buffer material disposed around the optical fiber core wire, and winding a presser winding around the buffer material. A method of manufacturing an optical fiber cable, and a step of forming a jacket on the outside of the optical fiber core wire and the buffer material wound with the presser winding, wherein the step of winding the presser The winding pitch is greater than 0 mm and not greater than 35 mm, the dynamic tension at the time of winding of the presser winding is greater than 0 N and not greater than 2.8 N, and the presser winding is wound in a direction opposite to the twisting direction of the optical fiber core wire. It is a thing.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention includes a cable core in which two or more optical fiber cores are twisted together with a buffer material filled in the periphery thereof, and a presser winding thread or tape is roughly wound on the outer side thereof, and a sheath on the outer side of the cable core. The present invention is applied to the manufacture of an optical fiber cable provided with The cable core is a portion including a communication transmission medium such as an optical fiber inside the outer sheath, and the optical fiber core wire is disposed at the center of the cable core. Here, the central portion refers to a region smaller than the cable core including the axial center of the cable core.
[0011]
In the optical fiber cable as described above, in order to prevent the optical fiber core wire from moving in the longitudinal direction in the optical fiber cable, the winding pitch of the presser winding thread or tape is reduced and the winding tension is increased. It is conceivable to increase the tightening force of the cable core. However, in this case, the side pressure received by the optical fiber core inside the cable core increases, and the transmission loss of the optical fiber increases. That is, the suppression of the movement of the optical fiber core and the maintenance of the transmission characteristics are in a trade-off relationship.
[0012]
As a result of intensive studies to solve the above problems, the present inventors have determined that the coarse winding pitch of the presser winding exceeds 0 mm and 35 mm or less, and the dynamic tension at the time of presser winding winding exceeds 0 N and 2.8 N or less. In addition, it has been found that the movement of the optical fiber core in the longitudinal direction in the optical fiber cable can be suppressed without deteriorating the transmission loss by setting the rough winding direction to be opposite to the twist direction of the optical fiber core. The invention has been completed. Furthermore, the above-described effects are more remarkable by setting the coarse winding pitch of the above-mentioned presser winding to be greater than 0 mm and 25 mm or less and the dynamic tension at the time of winding of the presser winding to be more than 1.5 N and not more than 2.2 N. It was found that can be realized.
[0013]
In order to prevent the transmission characteristics of the optical fiber cable from deteriorating, it is desirable that the heat shrinkage rate of the buffer material is 0.2% or less. As such a buffer material, a low-shrinkage polypropylene fiber string or the like is used. Can be used. Further, nylon thread, nylon tape, and PET tape can be used as the presser winding thread or tape. Further, a thermoplastic resin such as polyethylene can be used for the jacket.
[0014]
FIG. 1 is a diagram showing a configuration example of an optical fiber cable to which the present invention is applied, in which 1 is an optical fiber core wire, 2 is a cushioning material, 3 is a presser winding thread or tape, 4 is a steel wire, 5 is an outer coating, 6 is a twisting direction of an optical fiber core wire, and 7 is a winding direction of a presser winding thread or tape. The cable core is formed by laminating a plurality of tape-shaped optical fiber cores 1 composed of a plurality of optical fibers, the periphery of which is covered with a buffer material 2, and the outer periphery thereof being roughly wound with a presser winding thread or tape 3. Has been. Two steel wires 4 are longitudinally attached to the cable core as a strength member, and further covered with an outer covering 5.
[0015]
In the optical fiber cable as described above, the optical fiber cores 1 of a plurality of layers are twisted together with the buffer material 2, and the winding direction 7 of the presser wound yarn or tape 3 is the same as the twist direction 6 of the optical fiber core wire 1. Are configured in the opposite direction.
[0016]
FIG. 2 is a flowchart for schematically explaining the manufacturing process of the optical fiber cable having the configuration shown in FIG. First, two or more optical fiber cores are twisted together with a buffer material arranged around the optical fiber core (step S1), and a presser thread or tape is wound around the buffer material (step S2). Then, a tensile body is disposed outside the optical fiber core wire 1 and the buffering agent wound with the presser winding thread or tape to further form an outer skin (step S3).
[0017]
(Examples and Comparative Examples)
An optical fiber cable having the structure shown in FIG. 1 was manufactured under the following conditions. First, six tape-shaped optical fiber cores 1 composed of four optical fibers are laminated, and the periphery is covered with a plurality of low-shrinkage polypropylene fiber strings corresponding to a total of 50,000 deniers without any gaps. And twisted together. As the low-shrinkage polypropylene fiber string, one having a heat shrinkage rate of 0.2% or less was used.
[0018]
And the cable core was produced by winding nylon thread around the outer periphery of the low shrinkage polypropylene twisted around the optical fiber core wire 1 as a presser winding. FIG. 3 shows the conditions for winding the nylon yarn and the evaluation results for each condition. Here, cable cores are produced by changing the conditions for the presser coarse winding pitch, the presser winding tension, and the nylon thread winding direction, and a steel wire 2 having a diameter of 0.72 mm is produced for each cable core. An optical fiber cable having an outer diameter of 10 mm was manufactured by covering the book vertically and then covering with polyethylene. Regarding the tension of the presser winding, the dynamic tension at the time of winding the presser winding is shown. The tape winding direction is the opposite direction of the twist direction of the optical fiber core in Examples 1 to 11 and Comparative Examples 1 to 3, and the same direction as the twist direction of the optical fiber core is used for Comparative Example 4. did.
[0019]
And about each produced optical fiber cable, the transmission loss and the optical fiber core wire drawing-out force from a cable core were measured and evaluated. The pulling force of the optical fiber core is used as an index that quantitatively represents the degree of suppression of the movement of the optical fiber core 1 in the longitudinal direction in the optical fiber cable, and the optical fiber core 1 is extracted from the 10 m long optical fiber cable. The force required to pull out is measured. Here, it is shown that the movement in the longitudinal direction of the optical fiber core 1 in the optical fiber cable is suppressed as the pulling force of the optical fiber core 1 is increased.
[0020]
As shown in Examples 1 and 3 and Comparative Example 1, the winding tension of the presser winding was 2.8 N, and the coarse winding pitch was 5 mm (Example 1), 35 mm (Example 3), and 45 mm (Comparative Example 1). Even when the coarse winding pitch of the presser winding was reduced, the degree of increase in transmission loss was small, but the optical fiber core wire drawing force was greatly affected. That is, the optical fiber core drawing force is 29 N in Example 1, 23 N in Example 3, 16 N in Comparative Example 1 and the rough winding pitch is not less than 35 mm. Couldn't get.
[0021]
In addition, as shown in Examples 2 and 3 and Comparative Example 2, when evaluating an optical fiber cable in which the winding tension of the presser winding was changed at a rough winding pitch of 35 mm capable of obtaining a sufficient optical fiber core wire drawing force, An optical fiber cable manufactured with a winding tension of 0.5 N (Example 2) has a transmission loss of 0.20 dB / km, and an optical fiber cable manufactured with a winding tension of 2.8 N (Example 3) has a transmission loss of 0.29 dB / km. km, the transmission characteristics were good.
[0022]
However, in the optical fiber cable (Comparative Example 2) manufactured with the winding tension of the presser winding being 3.0 N, the transmission loss was 0.38 dB / km, and satisfactory transmission characteristics could not be obtained. Furthermore, in order to obtain a good transmission characteristic with a tension of 3.0 N, an optical fiber cable was manufactured with a winding pitch of 45 mm as a holding winding (Comparative Example 3), but the influence of the coarse winding pitch on the transmission characteristic was small as described above. The transmission loss was 0.36 dB / km, so that good transmission characteristics could not be obtained, and the optical fiber core drawing force was reduced to 17N.
[0023]
Furthermore, as shown in Comparative Example 4, the winding tension of the presser winding is set to 2 so that the winding pitch of the presser winding is reduced to 35 mm so that the pulling force of the optical fiber is increased, and good transmission characteristics are obtained. Even if the optical fiber cable is made as large as .8 N, if the winding direction of the press winding with respect to the twisting direction of the optical fiber core is the same direction, the core wire pulling force is 14 N, which is sufficient optical fiber. It was not possible to obtain the core drawing force.
[0024]
Further, in Examples 4 to 7, an optical fiber cable was prepared by setting the winding tension of the press winding to 1.5 N and changing the coarse winding pitch in the range of 5 to 35 mm. In Examples 8 to 11, the press winding was performed. An optical fiber cable was prepared by changing the coarse winding pitch in the range of 5 to 35 mm with a winding tension of 2.2 N. As shown in these Examples 4 to 11, in any of the Examples, good transmission characteristics and core wire drawing force can be obtained, and in particular, when the coarse winding pitch is 25 mm or less, the transmission loss is 0. It was possible to obtain a better result of 22 dB / km or less and a core wire drawing force of 25 N or more.
[0025]
From the above results, in order to set the transmission loss to 0.30 dB / km and the pulling force of the optical fiber core wire to 20 N or more, the winding pitch of the presser winding is 35 mm or less and the winding tension is 2.8 N or less. In particular, it is more preferable that the winding pitch of the press winding is greater than 0 mm and 25 mm or less, and the winding tension is 1.5 N or more and 2.2 N or less.
[0026]
【The invention's effect】
As is apparent from the above description, according to the present invention, the movement of the optical fiber core in the optical fiber cable in the longitudinal direction is suppressed without fixing the optical fiber core and the buffer material with an adhesive or the like. Therefore, it is possible to maintain the reliability of the transmission characteristics and to easily take out the optical fiber core for branching.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of an optical fiber cable to which the present invention is applied.
FIG. 2 is a flowchart for schematically explaining a manufacturing process of the optical fiber cable having the configuration shown in FIG. 1;
FIG. 3 is a table showing presser winding conditions and evaluation results.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Optical fiber core wire, 2 ... Buffer material, 3 ... Holding winding tape, 4 ... Steel wire, 5 ... Outer coating, 6 ... Twisting direction of optical fiber core wire, 7 ... Winding direction of pressing winding tape.

Claims (4)

Two or more optical fiber core wires are twisted together with a buffer material disposed around the optical fiber core wire, a presser winding is wound around the outer side of the buffer material, and the optical fiber core wire is further wound with the presser winding And an optical fiber cable provided with a jacket on the outer side of the cushioning material, wherein the winding pitch of the presser winding is greater than 0 mm and not greater than 35 mm, and the winding tension of the presser winding is greater than 0 N and not greater than 2.8 N. An optical fiber cable, wherein the presser winding is wound in a direction opposite to a twisting direction of the optical fiber core wire. 2. The optical fiber cable according to claim 1, wherein a winding pitch of the presser winding is greater than 0 mm and 25 mm or less, and a winding tension of the presser winding is 1.5 N or more and 2.2 N or less. Twisting two or more optical fiber cores together with a buffer material disposed around the optical fiber core wire, a step of winding a presser winding thread or tape around the buffer material, and the presser winding And a step of forming a jacket on the outer side of the wound optical fiber core and the buffer material, wherein the step of winding the presser winding includes a winding pitch of the presser wound yarn or tape. An optical fiber cable having a winding tension greater than 0 mm and not greater than 35 mm, a winding tension of the retainer winding being greater than 0 N and not greater than 2.8 N, and the retainer winding being wound in a direction opposite to the twisting direction of the optical fiber core wire. Manufacturing method. 4. The step of winding the presser winding comprises setting the winding pitch of the presser winding to be greater than 0 mm and 25 mm or less, and setting the winding tension of the presser winding to be 1.5 N or more and 2.2 N or less. The manufacturing method of the optical fiber cable of description.

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