JPH10160944A - Aerial optical fiber cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aerial optical fiber cable which may be inexpensively produced with the need for fewer production stages and lesser production equipment and with which the tensile force acting on the optical fiber cable and the strains arising therefrom may be decreased at the time of aerial laying. SOLUTION: This aerial optical fiber cable is obtd. by connecting and integrating a supporting wire 11 which is formed by coating supporting wire bodies 14 with a coating material 15 consisting of a synthetic resin and the optical fiber cable 13 which is formed by coating cable cores 16 with a cable sheath 17 consisting of a synthetic resin by a connecting part 12 consisting of the synthetic resin. Many separating parts 18 are formed intermittently along the longitudinal direction of the supporting wire 11 in this connecting part 12. The optical fiber cable 13 is formed in a state to have a slack with the supporting wire 11 in these separating parts 18. In such a case, the thickness (a) of the connecting part 12 is confined to the thickness (c) of the cable sheath 17 or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-supporting overhead optical fiber cable in which a support wire and an optical fiber cable are connected and integrated at a connecting portion, and the optical fiber cable has a slack (excess length). About.

[0002]

2. Description of the Related Art Conventionally, as this type of overhead optical fiber cable, there is a pre-hanger type cable having a structure shown in FIG. In the figure, reference numeral 1 is a support line. The support wire 1 is formed by coating a support wire main body such as a galvanized steel stranded wire with a coating material made of a synthetic resin such as polyethylene or polyvinyl chloride. It is to be erected.

[0003] An optical fiber cable 3 in which a large number of optical fiber cores are accommodated is suspended from the support wire 1 via a large number of hangers 2. The hanger 2 has a gourd-shaped plate shape in cross section, and is made of a synthetic resin such as polyethylene or polyvinyl chloride. A support wire 1 penetrates and is fixed to an upper part of the hanger 2, and an optical fiber cable 3 is penetrated and fixed to a lower part thereof. The hangers 2 are arranged at predetermined intervals (about 50 c) with respect to the support wire 1 and the optical fiber cable 3.
m), and the optical fiber cable 3 is fixed in this space between the hangers 2... with a sufficient slack with respect to the support wire 1. That is, between the support wire 1 and the optical fiber cable 3, there are formed a plurality of gaps 4 opening to the side of the cable, separated by a plurality of hangers 2.

In such a pre-hanger type aerial optical fiber cable, the optical fiber cable 3 has a slack structure with respect to the support wire 1, so that the optical fiber cable can be used in an aerial installation or the like. No tensile force or distortion due to the tensile force is applied to or reduced. The slack prevents the optical fiber core housed therein from moving in the longitudinal direction and jumping out of the cable end.

[0005] Further, it has a characteristic that dancing is hard to occur. That is, when an aerial cable is laid, if a cross-section of the cable whose cross-sectional shape is asymmetrical is blown from the side, lift (force acting in the upward direction of the cable) is generated. Frequency oscillation occurs. Since the vibration (dancing) easily deteriorates the optical fiber cores and the like in the inside thereof, it is preferable to prevent the dancing as much as possible. In the above-mentioned pre-hanger type overhead optical fiber cable, a gap 4 between the support wire 1 and the optical fiber cable 3 is used.
Are formed, a part of the cross wind from the side of the cable passes through the gaps 4. As described above, since the crosswind passes through the gaps 4 between the support wire 1 and the optical fiber cable 3, the lift is small, and the dancing is less likely to occur.

However, when manufacturing this pre-hanger type overhead optical fiber cable, first, the support wire body is extrusion-coated with polyethylene, polyvinyl chloride or the like to form the support wire 1, and the support wire 1 is formed in a separate process. The surface of the optical fiber cable core is extrusion-coated with polyethylene, polyvinyl chloride, or the like, and a sheath is provided to obtain an optical fiber cable 3. Then, the support wire 1 and the optical fiber cable 3 are assembled, and when the hangers 2 are provided intermittently by injection molding, the optical fiber cable 3 is manufactured such that a slack is formed in the optical fiber cable 3. For this reason, in manufacturing this pre-hanger type aerial optical fiber cable, there are drawbacks in that the number of manufacturing steps is increased and many manufacturing facilities are required.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances by using a ship, and requires only a small number of manufacturing steps and a small number of manufacturing equipment in its manufacture, can be manufactured at low cost, and can be used for overhead installation. In, the tensile force applied to the optical fiber cable and the resulting distortion can be reduced,
An object of the present invention is to provide an optical fiber cable in which dancing is less likely to occur.

[0008]

SUMMARY OF THE INVENTION The object of the present invention is to provide a support wire in which a support wire main body is covered with a covering made of synthetic resin, and an optical fiber cable in which a cable core is covered with a cable sheath made of synthetic resin. Are connected and integrated by a connecting portion made of a synthetic resin, and a large number of separating portions are formed intermittently in the connecting portion along the longitudinal direction of the support line. In this separating portion, the optical fiber cable is connected to the supporting line. It is possible to solve the problem by configuring an overhead optical fiber cable having a slack with respect to the above, wherein the thickness of the connecting portion is less than or equal to the thickness of the cable sheath. . The overhead optical fiber cable having such a configuration can be manufactured efficiently and at low cost. The manufacturing speed can be further improved by setting the thickness of the connecting portion to be equal to or less than the thickness of the cable sheath and equal to or more than の of the thickness of the cable sheath.

[0009]

1 and 2 show an example of an overhead optical fiber cable according to the present invention. FIG. 1 is a sectional view and FIG. 2 is a perspective view. This overhead optical fiber cable is roughly composed of a support wire 11, a connecting portion 12, and an optical fiber cable 13. In this embodiment, the support wire 1
Reference numeral 1 denotes a support wire main body 14 having an outer diameter of 6 mm made of a galvanized steel stranded wire or the like, and a cover 1 made of a synthetic resin such as polyethylene or polyvinyl chloride covering the support wire main body 14.
The support wire 11 has an outer diameter of 8 mm.

On the other hand, the optical fiber cable 13 is composed of a cable core 16 having an outer diameter of 16 mm in which a large number of single-core or multiple-core optical fibers are accommodated, and this cable core 16.
The optical fiber cable 13 has an outer diameter of 19 mm and a cable sheath thickness c of 1.5 mm. The cable core 16
Various configurations can be used, and for example, the configuration shown in FIG. 1 can be used. That is, reference numeral 16a in the drawing denotes a slot, at the center of which a tensile strength line 16b is arranged, and further, along the longitudinal direction thereof, five U-shaped grooves 16c are provided.
6a is configured. In the groove 16c, a laminated body in which a plurality of optical fiber ribbons 16d are collected is stored, and the holding tape 1 is placed on the slot 16a.
The cable core 16 is formed by winding 6e without any gap.

The connecting portion 12 connects and integrates the support wire 11 and the optical fiber cable 13 so that the optical fiber cable 13 is hung on the support wire 11, and hangs down from the bottom of the support wire 11. It is a wall-shaped member extending continuously to the top of the optical fiber cable 13 and having a constant thickness, and is made of a synthetic resin such as polyethylene or polyvinyl chloride. The connection part thickness a is about 1 mm, and the connection part height b is about 4 mm. The details will be described after the description of the method of manufacturing the overhead optical fiber cable.
In order to prevent the cable sheath 17 constituting the outermost layer from being deformed, the cable sheath thickness c (1.5 m
m) Design below. When the thickness a of the connecting portion is equal to or less than the thickness c of the cable sheath and equal to or more than の of the thickness c of the cable sheath, the deformation of the cable sheath 17 can be prevented, and the manufacturing speed is improved. Can be preferred.

The connecting portion 12 has a plurality of slit-shaped separating portions 18 intermittently cut along the supporting line 11,
18 (gap) are formed, and the support wire 11 and the optical fiber cable 13 are connected to each other at the connecting portion 12a where the separating portion 18 is not formed. The length of the separation part 18 is, for example, about 50 cm, and the interval between adjacent separation parts 18, 18 is, for example, about 5 cm. The length and interval of the separation part 18 can be arbitrarily changed. Further, the optical fiber cable 13 has a slack at the position where the separating portions 18, 18... Of the connecting portion 12 are formed, and the slack is formed on the side of the support wire 11 by changing the direction substantially alternately. ing. In other words, the optical fiber cable 13 is meandering in the left-right direction with respect to the linear support wire 11. .1 to 0.7%. With this structure, the overhead optical fiber cable does not apply or reduce a tensile force or a strain due to the optical fiber cable 13 similarly to the conventional pre-hanger type cable. The optical fiber ribbon 16d and the like do not move, and the dancing is less likely to occur.

Next, a method for manufacturing such an overhead optical fiber cable will be described. FIG. 3 shows an example of a method for manufacturing an overhead optical fiber cable of the present invention.
Is a crosshead die for extrusion coating attached to an extruder. The optical fiber cable core 16 and the support wire main body 14 are simultaneously fed into the crosshead die 21 from an inlet hole of the mandrel, and a molten resin such as polyethylene or polyvinyl chloride is supplied from an extruder (not shown). An intermediate product N in which the resin is coated around the optical fiber cable core 16 and the support wire main body 14 in the head die 21 and the connecting portion 12 is formed is obtained.

As shown in FIG. 4, the intermediate product N is continuously led out from the exit hole of the crosshead die 21 with the support wire 11 positioned below and the optical fiber cable 13 positioned above. By arranging the supporting wire 11 having a heavy weight below, the connecting portion 12 is formed in a straight state by the weight.

On the outlet side of the crosshead die, a separation section forming device 22 is provided. The separation portion forming device 22 has a sharp blade (not shown), and the blade is intermittently advanced or retracted toward the intermediate product N, so that the intermediate product N coming out of the crosshead die 21 is removed. While the resin forming the connecting portion 12 is still in a semi-molten state, a linear cut is made in the resin to form the separating portions 18 intermittently. As shown in FIG. 5, the intermediate product N in which the linear separating portions 18 are intermittently formed substantially at the center of the connecting portion 12 by the separating portion forming device 22 is then sent to the primary cooling water tank 23. Then, it is cooled and the resin on the surface thereof is semi-cured, and is sent to the extra length forming pulley 24.

The extra length forming pulley 24 has a diameter of 30 cm to 2 cm.
It is of an annular shape of about 00 cm, and rotates at a constant speed in the direction of the arrow in the figure. This extra length forming pulley 2
4, the intermediate product N is wound around the circumference and travels in the direction of the arrow. At the time of this winding,
As shown in FIG. 6, the supporting wire 11 and the optical fiber cable 1 are attached to the outer peripheral surface of the extra length forming pulley 24 by the tension caused by the winding.
3 will be in contact.

Since the optical fiber cable 13 and the support wire 11 have different diameters, and the diameter of the optical fiber cable 13 is larger, the optical fiber cable 13 of the intermediate product N wound around the extra length forming pulley 24 13 is larger than the winding diameter of the support wire 11. Since the extra-length forming pulley 24 rotates at a constant speed, the peripheral speed of the optical fiber cable 13, that is, the traveling speed is lower than the supporting line 1.
1 will be faster than the traveling speed. This allows
By winding the intermediate product N around the extra-length forming pulley 24, the traveling speed of the optical fiber cable 13 becomes faster than the traveling speed of the support wire 11.

The difference between the two traveling speeds is that when the intermediate product N moves away from the extra length forming pulley 24, the optical fiber cable 13 is partially cut off from the support wire 11 at the separation portions 18, 18,. Therefore, the separation units 18 and 18
... appears as slack (extra length). For this reason,
The intermediate product N moving away from the extra length forming pulley 24 has its optical fiber cable 13 slackened at the positions of the separation parts 18, 18,..., And exhibits a meandering state as shown in FIG.

The intermediate product N in this state is immediately sent to the secondary cooling water tank 25, where it is completely cooled and the resin is cured. Thus, an aerial optical fiber cable having the appearance shown in FIG. 2 is continuously obtained, and is appropriately wound on a winding drum or the like to obtain a product.

In such a manufacturing method, the extra-length forming pulley 24
If the diameter of is reduced, the slack increases, and if the diameter is increased, the slack decreases. Further, the extra length forming pulley 24
The amount of slack of the optical fiber cable 13 can be changed even if the number of times of winding around the optical fiber cable 13 is changed. Therefore, the slack (excess length) required for the optical fiber cable 13 can be easily formed by appropriately using these methods.

As described above, in the above-mentioned overhead optical fiber cable, the resin coating on the optical fiber cable core 16 and the supporting wire main body 14, the formation of the connecting portion 12, and the provision of the slack to the optical fiber cable 13 are performed in one production line. Can be performed all at once in a single step, and can be manufactured extremely efficiently. Also, compared to the conventional method of manufacturing a pre-hanger type aerial optical fiber cable, the manufacturing speed can be significantly increased, and no special manufacturing equipment is required, thereby significantly reducing the manufacturing cost. it can.

When the intermediate product N is wound around the extra length forming pulley 24 as described above, the traveling speed of the optical fiber cable 13 is faster than the traveling speed of the support wire 11. Therefore, at this time, the optical fiber cable 13 is pulled from the support wire 11 via the coupling portion 12a in the direction opposite to the running direction by the difference in the traveling speed between the optical fiber cable 13 and the support wire 11. Power is added.

At this time, since the synthetic resin forming the connecting portion 12a and the cable sheath 17 adhered to the connecting portion 12a is in a semi-cured state, the force causes the connecting portion 12a and the cable sheath 17 to be distorted. The lower the strength, the greater the deformation. If the cable sheath 17 is deformed or damaged, not only is the appearance significantly reduced, but also the optical fiber tape core 16 d housed in the optical fiber cable 13 is deteriorated. To prevent the cable sheath 17 from being connected to the connecting portion 1.
It is necessary to appropriately set the intensity of 2a. In order to solve this problem, the present inventors have conducted various studies, and as a result, when the connecting portion thickness a is equal to or less than the cable sheath thickness c, the strength balance between the cable sheath 17 and the coupling portion 12a is good, It has been found that deformation and damage of the cable sheath 17 due to the difference in traveling speed can be prevented.

However, if the thickness a of the connecting portion is smaller than the thickness c of the cable sheath, the following problems may occur. That is, when the intermediate product N is wound around the extra-length forming pulley 24, the semi-cured synthetic resin that forms the coupling portion 12a and the cable sheath 17 is cured first with the coupling portion 12a having a small thickness. At this time,
In particular, when the production linear speed is increased, the curing speed of the synthetic resin is increased, and the joint portion 12a is rapidly cured and contracts.
However, since the curing speed of the cable sheath 17 integrated with the connecting portion 12a is lower than that of the connecting portion 12a, the contraction causes the cable sheath 17 to be deformed. Therefore, it is necessary to appropriately set the connection portion thickness a so that the difference in curing speed between the cable sheath 17 and the connection portion 12a is not too large. As a result of repeated studies by the present inventors, the thickness a of the connecting portion was set to be 1 of the thickness c of the cable sheath.
/ 2 or more, the cable sheath 17 and the connecting portion 1
It was found that the deformation of the cable sheath 17 due to the difference in curing speed of 2a was less likely to occur.

Therefore, it is most desirable that the conditions determined by the above two examination results be simultaneously satisfied. That is, by setting the thickness a of the connecting portion to be equal to or less than the thickness of the cable sheath and equal to or more than の of the thickness c of the cable sheath, the cable sheath 17 is hardly deformed, the product yield is improved, and stable production is achieved. Not only is possible, but also the production linear speed can be increased, so that the production efficiency can be greatly improved.

[0026]

As described above, according to the present invention, an appropriate slack (extra length) is formed in an optical fiber cable.
Provided is a self-supporting overhead optical fiber cable that is hardly subjected to tensile force or distortion due to the pulling force during installation of an overhead, hardly causes movement or dancing of an optical fiber core, and can be manufactured efficiently and at low cost. Can be. Furthermore, by setting the thickness of the connecting portion to be equal to or less than the thickness of the cable sheath, deformation of the cable sheath due to a difference in traveling speed between the support wire and the optical fiber cable when winding the intermediate product around the extra length forming pulley during manufacturing is reduced. Can be prevented. Further, by setting the thickness of the connecting portion to be equal to or more than １ ／ of the thickness of the cable sheath, it is possible to prevent the deformation of the cable sheath due to a difference in curing speed between the connecting portion (joining portion) and the cable sheath. Therefore, by setting the thickness of the connecting portion to be equal to or less than the thickness of the cable sheath and equal to or more than の of the thickness of the cable sheath, not only the product yield is improved, but also stable production becomes possible, Since the production linear velocity can be increased, the production efficiency can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an overhead optical fiber cable according to the present invention.

FIG. 2 is a perspective view showing an example of an overhead optical fiber cable according to the present invention.

FIG. 3 is a configuration diagram showing an example of a method for manufacturing an overhead optical fiber cable of the present invention.

FIG. 4 is a perspective view showing an intermediate product in a production method example of the present invention.

FIG. 5 is a perspective view showing an intermediate product in a production example of the present invention.

FIG. 6 is a configuration diagram showing an enlarged main part of FIG. 2;

FIG. 7 is a perspective view showing a conventional pre-hanger type overhead optical fiber cable.

[Explanation of symbols]

11 support line, 12 connecting part, 12a connecting part, 13
... optical fiber cable, 14 ... support wire main body, 15 ... coating body, 16 ... cable core, 17 ... cable sheath,
18: separation part, a: thickness of connection part, c: thickness of cable sheath

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayoshi Yamanaka 1440, Mukurosaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Factory Co., Ltd. 72) Inventor Hideyuki Iwata Nippon Telegraph and Telephone Corporation

Claims (2)

[Claims] A connecting part made of a synthetic resin, wherein a supporting wire whose supporting wire body is covered with a covering made of a synthetic resin and an optical fiber cable whose cable core is covered with a cable sheath made of a synthetic resin. A plurality of separating portions are formed intermittently in the connecting portion along the longitudinal direction of the supporting line, and the optical fiber cable has a slack with respect to the supporting line at the separating portion. An overhead optical fiber cable, wherein the thickness of the connecting portion is equal to or less than the thickness of the cable sheath. 2. A connecting part made of a synthetic resin, wherein a support wire whose support wire body is covered with a cover made of a synthetic resin and an optical fiber cable whose cable core is covered with a cable sheath made of a synthetic resin. A plurality of separating portions are formed intermittently in the connecting portion along the longitudinal direction of the supporting line, and the optical fiber cable has a slack with respect to the supporting line at the separating portion. Wherein the thickness of the connecting portion is equal to or less than the thickness of the cable sheath and equal to or more than １ ／ of the thickness of the cable sheath. Aerial fiber optic cable.