JPH11344651A - Overhead optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an overhead optical cable which is free of falling of the neck part of a connection part 12 and stable in the thickness of a coating layer. SOLUTION: In the overhead optical cable which has a support wire 11 and an optical cable 13 mutually connected and made into one body at the connection part 12 and also has separate parts formed at the connection part 12 intermittently along the length of the support wire 11 so that the optical cable 13 has a slack to the support wire 11 at the separate parts, the base part A1 of the connection part 12 on the side of the support wire 11 and the base part B1 on the side of the optical cable 13 have a thick wall structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support line and an optical cable which are connected and integrated at a connecting portion, and which has a slack (excess length) in the optical cable so that stress is not applied to the optical cable core even in an imaginary environment. The present invention relates to a self-supporting overhead optical cable with slack.

[0002]

2. Description of the Related Art Conventionally, this type of overhead optical cable (hereinafter, referred to as "optical cable")
As a SSD, a pre-hanger type SSD was generally used. In this type, the optical cable is suspended by a number of gourd-type hangers along the support line, and the optical cable is fixed with sufficient slack with respect to the support line. At the time of laying or the like, a tensile force or a strain due to the tensile force is not applied to the optical cable or is reduced.

However, such a pre-hanger type SS
In the case of D, the production has three steps, and the molding of the hanger portion is rate-determined in production, the production speed is not increased, and the productivity is poor. In order to solve this problem, the supporting wire and the optical cable are connected and integrated at a connecting portion, and a separating portion is formed intermittently in the connecting portion along the longitudinal direction of the supporting line, and the optical cable is formed at the separating portion. SSD has a structure with slack with respect to the support line
Has been proposed in Japanese Patent Application No. 8-10436. This SSD has a one-step manufacturing process by a batch coating method.
Since the SSD is manufactured in the process, the manufacturing efficiency of the loosened SSD can be improved.

FIG. 3 shows an example of a conventional slack SSD. The SSD includes a support line 11 and a connecting portion 12.
And an optical cable 13. Support line 1
1 is a support wire main body 14 made of a galvanized copper stranded wire or the like.
And a coating layer 15 made of a synthetic resin such as polyethylene for coating the support wire main body 14. The connecting portion 12 connects and integrates the supporting cable 11 and the optical cable 13, thereby suspending the optical cable 13 with the supporting cable 11. The connecting section 12 hangs down from the bottom of the supporting cable 11 and extends to the top of the optical cable 13. It has a continuous wall thickness of about 1 to 4 mm and is made of a synthetic resin such as polyethylene. The optical cable 13 includes a cable core 16 in which a large number of optical fiber cores are accommodated, and a sheath 17 made of a synthetic resin such as polyethylene which covers the cable core 16.

[0005] The connecting portion 12 is formed with a large number of slit-like separating portions 18, 18... Intermittently cut along the supporting line 11, and a neck portion 19 that cannot be cut. . The length of the separation unit 18 is, for example, 5
The distance between the adjacent separating portions 18, that is, the length of the neck portion 19 is, for example, about 5 cm. The length of the separating portion 18 and the length of the neck portion 19 can be arbitrarily changed. Further, the separation portions 18, 1
At the formation position of 8, the optical cable 13 has slack, and the slack is formed on the side of the support wire 11 by changing the direction substantially alternately. In other words, the optical cable 13 is meandering in the left-right direction with respect to the linear support line 11, and the meandering of the optical cable 13 causes the optical cable 13 to move about 0.1 mm with respect to the support line 11.
It has an extra length (slack) of about 0.7%.

The above-mentioned slackened SSD is obtained by a manufacturing method described below. FIG. 4 is a schematic configuration diagram illustrating an example of a method for manufacturing a loosened SSD. In the figure, reference numeral 21 denotes a crosshead die for extrusion coating attached to an extruder. The optical 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 is supplied from an extruder (not shown). An intermediate product N in which resin is coated around the support wire body 16 and the support wire body 14 and the connecting portion 12 is formed is obtained.

[0007] On the outlet hole side of the crosshead die 21, a separating portion forming device 22 is provided. The separating portion 22 has a sharp blade (not shown), and the blade is intermittently advanced or retracted toward the intermediate product N.
While the resin forming the connecting portion 2 of the intermediate product N coming out of the crosshead die 21 is still in a semi-molten state, a straight cut is made in the resin and the separating portion 1 is intermittently cut.
8, 18... Are formed. This separation forming device 2
The intermediate product N in which the linear separating portions 18, 18... Are formed intermittently in the approximate center of the connecting portion 12 by the second cooling device 2 is then sent to the primary cooling water tank 23, where it is cooled and cooled. The resin is sent to the extra-length forming pulley 24 in a semi-solid state.

The extra-length forming pulley 24 has a diameter of 30 to 200.
It is an annular body of about cm, and rotates at a low speed in the direction of the arrow in the figure. The intermediate product N is wound around the extra-length forming pulley 24 for one round and runs in the direction of the arrow. During this winding, the supporting wire 11 and the optical cable 13 come into contact with the outer peripheral surface of the extra-length forming pulley 24 due to the tension caused by the winding.

The support wire 11 and the optical cable 13 have different diameters, and the diameter of the optical cable 13 is larger than the diameter of the support wire 11. Therefore, of the intermediate product N wound around the extra length forming pulley 24, 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 cable 13, that is, the traveling speed becomes faster than the traveling speed of the support wire 11. Thereby, the running speed of the optical cable 13 becomes faster than the running speed of the support wire 11 by winding the intermediate product N around the extra-length forming pulley 24.

The difference between the two traveling speeds is caused when the intermediate product N moves away from the extra length forming pulley 24,
Are partially separated from the support wires 11 at the separation portions 18, 18,..., And are represented as slack (excess length) at the separation portions 18, 18,. For this reason, the intermediate product N moving away from the extra-length forming pulley 24 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 solidified. In this way, a slackened SSD 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 addition, S
The amount of slack in the SD can be adjusted by the diameter of the extra-length forming pulley 24 and the number of windings.

In such a conventional slackened SSD, the optical cable 1 is similar to the pre-hanger type SSD.
No tensile force or distortion due to the tensile force is applied to or reduced. In addition, there is an effect that the SSD can be manufactured at a low cost with a small number of manufacturing steps.

[0013]

However, in such a loosened SSD, there is a problem that the neck portion 19 of the connecting portion 12 is weak and the neck portion 19 falls down in the step of loosening the optical cable 13. . More specifically, in the conventional slackened SSD, as shown in an enlarged cross-sectional view in FIG. 5, the base A of the connection portion 12 with the optical cable 13 and the base B of the support wire 11 with the side surfaces thereof. It is connected to the optical cable 13 and the support wire 11 at substantially right angles. In this case, since the base A and the base B are weak against lateral stress, the stress applied when the optical cable 13 is slackened causes the neck 1 to be loosened.
9 is easy to fall down.

The present invention has been made in view of the above circumstances, and in the above-described SSD with slackness, there is provided a SSD with slackness in which the thickness of the coating layer is stable without the neck portion 19 of the connecting portion 12 falling down. As an issue.

[0015]

According to the present invention, a support wire and an optical cable are connected and integrated at a connecting portion, and a large number of separating portions are formed intermittently in the connecting portion along the longitudinal direction of the supporting line. In the SSD in which the optical cable is slack with respect to the support line in the separation section, the base of the connection section with the support line and the base of the optical cable are thickened. And

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A loosened SSD according to the present invention is different from a conventional loosened SSD in the structure of a connecting portion 12. This will be described with reference to FIGS. FIG. 1 is a cross-sectional view of a neck portion 19 showing an example of a loosened SSD according to the present invention. In the present invention, FIG.
As shown in FIG.
1 and the base B1 of the support wire 11 are connected so that their side surfaces are inclined, and have a structure thicker than other portions of the connection portion 12. In this case, since the base A1 and the base B1 have a structure resistant to lateral stress, the neck 19 can be less likely to fall due to the stress applied when the optical cable 13 is slackened.

In the slack SSD of the present invention, the SSD
As a method of increasing the thickness of the base A1 with the optical cable 13 and the base B1 with the support wire 11 of the connecting portion 12 in the SSD manufacturing method shown in FIG. A method is conceivable.
FIG. 2 is a cross-sectional view showing an example of the dice shape of the crosshead dice 21 suitably used in the present invention. The dice includes a circular portion 13a forming the optical cable 13, a connecting portion forming portion 12a forming the connecting portion 12, and a circular portion 11a forming the support wire 11.

At this time, the circular portion 1 of the connecting portion forming portion 12a
The base of the connecting portion 3a and the base of the circular portion 11a have inclined sides, and the tangent at the contact point between the center line of the connecting portion forming portion 12a and the circumference of the circular portions 11a and 13a is the side of the connecting portion. Is about 45 degrees.
The connecting portion 12 formed by this portion is connected to its base A1.
In addition, the base portion B1 becomes thicker and more resistant to the stress applied when the optical cable 13 is slackened, so that the neck portion 19 of the connecting portion 12 is less likely to fall.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments. (Example) A loosened SSD was manufactured using the apparatus shown in FIG. The shape of the crosshead dice 21 is shown in FIG. 2. The zinc aluminum plated steel stranded wire and the optical cable core are simultaneously fed into an extruder to which the crosshead dice 21 is attached, and molten polyethylene is supplied to the extruder. Then, while coating these with polyethylene and forming the connecting portion 12, they were cooled in the primary cooling tank 23 to semi-solidify the polyethylene to obtain an intermediate product N. Next, the length of the separating portion 18 is set to 500 to 600 c by the separating portion forming device 22 in the connecting portion 12 of the intermediate product N.
m, a cut was made so that the length of the neck portion 19 was 3 to 5 cm, and wound around the extra-length forming pulley 24. At this time, the diameter of the extra length forming pulley 24 was 30 to 200 cm, the rotation speed was 0 to 20 rpm, and the number of winding times of the intermediate product M was 1 to 5 times. Then, the wound intermediate product L is sent from the extra length forming pulley 24 to the secondary cooling tank 25, and the solid product obtained by cooling and completely solidifying the polyethylene is taken up by a take-up drum by 0 to 10 km. A loosened SSD according to an example was obtained. In the SSD manufactured at this time, the optical cable 13 had a slack of about 0.1 to 0.4%.

(Comparative Example) A loosened SSD was manufactured using the apparatus shown in FIG. The shape of the dice of the crosshead dice 21 was set in the same manner as in the above-described example, with the connecting portion forming part being substantially rectangular, and the loose S
SD was obtained.

With respect to the loosened SSDs of the above embodiment and the comparative example, the number of the folded portions of the neck portion 19 of the connecting portion 12 was visually checked. As a result, in the example,
In comparison with 7 places in 30m,
It was 15 places in 30m.

[0022]

As described above, according to the present invention, the slack S
In the SD, since the base of the optical cable and the connecting portion and the base of the support wire and the connecting portion have a thick structure, even in the step of forming the optical cable slack, the neck of the connecting portion is less likely to fall down and is stable. A coating layer is formed. Therefore, the appearance is improved and the optical fiber cable can be suitably used as a self-supporting overhead optical cable.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a neck portion of an example of an overhead optical cable of the present invention.

FIG. 2 is a sectional view showing a shape of a conventional crosshead die of the present invention.

FIG. 3 is a perspective view showing an example of an overhead optical cable of the present invention.

FIG. 4 is a schematic configuration diagram illustrating an example of a method for manufacturing an overhead optical cable according to the present invention.

FIG. 5 is a sectional view showing a neck portion of a conventional overhead optical cable.

[Explanation of symbols]

A1 base, B1 base, 11 support wire, 12 connecting part, 13 optical cable, 14 support body, 16 optical cable core

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Miyaji 1440, Mukurosaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Factory (72) Inventor Suehiro 1440, Misaki, Sakura City, Chiba Prefecture Fujikura Sakura Factory ( 72) Inventor Hideyuki Iwata Nippon Telegraph and Telephone Corporation, 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo

Claims (1)

[Claims] 1. A supporting line and an optical cable are connected at a connecting portion.
An aerial optical cable in which a large number of separated portions are formed intermittently along the longitudinal direction of the support line at the connecting portion, and the optical cable has a slack with respect to the support line at the separated portion. An aerial optical cable, characterized in that the base of the connecting portion with the support wire and the base of the optical cable with a thickness are thickened.