JPH11337790A - Aerial optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to provide good strength and to reduce a cost by winding an aluminum pipe in which an optical fiber is stowed around a supporting wire, thereby constituting an aerial optical cable. SOLUTION: This aerial optical cable is obtd. by manufacturing the aluminum pipe 3 while stowing the optical unit 2 therein, then forming a pipe sheath 5 on its circumference to manufacture a cable body 10, forming a supporting wire sheath 4 on the circumference of the supporting wire 1 aside therefrom, then winding the cable body 10 around the supporting wire 1. As a result, the aluminum pipe 3, in which the optical unit 2 is housed, has the higher mechanical strength than the mechanical strength of the conventional loose tubes and does not require the installation of a tension member for reinforcement. Then, the mechanical characteristics of the aerial optical cable are greatly improved by using the aluminum pipe 3. In addition, the extrusion workability at the time of manufacturing the cable body 10 may be improved and the cost may be reduced as well. The aluminum pipe 3 has advantages, such as ease of bending and difficulty in buckling at the time of bending.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small number of overhead optical cables.

[0002]

2. Description of the Related Art FIGS. 3 and 4 show an example of a conventional small-core, small-diameter overhead optical cable. In the example of FIG. 3, a cable body 23 in which about 6 to 12 optical fibers 11 are accommodated in a loose tube 21 made of resin and a coating layer 22 made of polyethylene is provided on the circumference thereof, and a support made of a steel stranded wire FIG. 3A shows a structure in which the cable main body 23 is wound around the support wire 12, and FIG. 3B shows the structure in which the cable main body 23 and the support wire 12 are formed on the collective coating layer 13. It has an integrated structure. Jelly 24 is filled in the loose tube 21, and a reinforcing steel wire 25 is embedded in the coating layer 22 on the periphery of the loose tube 21. In the structure shown in FIG. 3A, a coating layer 14 made of polyethylene is provided on the periphery of the support wire 12.

FIG. 4 shows a cable main body 33 in which about 6 to 12 optical fibers 11 are accommodated in a pipe 31 made of stainless steel (SUS) and a coating layer 32 made of polyethylene is provided on the periphery thereof. FIG. 4A shows a structure in which a cable main body 33 is wound around the support wire 12, and FIG. 4B shows a structure in which the cable main body 33 and the support wire 12 are connected to each other. Are integrated by the collective coating layer 13. The jelly 24 is filled in the stainless steel pipe 31, and in the structure of FIG. 4A, a coating layer 14 made of polyethylene is provided on the periphery of the support wire 12.

[0004]

However, the one using the loose tube 21 is susceptible to lateral pressure, and the loose tube 21 is made of resin, and therefore expands and contracts due to a change in temperature. For this reason, if there is a portion where the support wire 12 and the cable main body 23 are separated such as a connection portion or a retaining portion of the optical cable, the length of the loose tube 21 changes due to a change in temperature, which may cause an increase in optical transmission loss. There is. In order to prevent this, a thin steel wire 25 for reinforcement is arranged in the coating layer 22 of the cable body 23, but the workability at the time of extruding the coating layer 22 is not good, and the cost is low. There was a problem that it would increase. In the case of using the stainless steel pipe 31, there is no problem in strength,
Since the pipe 31 itself is hard, there is a disadvantage that the optical cable is easily buckled when it is bent with a small diameter. Also pipe 3
There was also a problem that the processing cost and material cost for manufacturing 1 became considerably high.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide an overhead optical cable having good strength and capable of reducing costs.

[0006]

The above object can be attained by an overhead optical cable characterized in that an aluminum pipe containing an optical fiber and a support wire are integrated. Specifically, an aluminum pipe containing an optical fiber can be wound around a support wire. Alternatively, an aluminum pipe containing an optical fiber and a support wire may be collectively covered with a collective sheath.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
FIG. 1 is a sectional view showing a first embodiment of an overhead optical cable according to the present invention. The overhead optical cable according to the present embodiment has a support wire 1.
A cable body 10 having an aluminum pipe 3 containing an optical unit 2 is wound therearound.
The support wire 1 is made of a tensile strength material, and a galvanized steel wire is preferably used. Although the thickness of the support wire 1 varies depending on the weight of the optical cable and the like, for example, a wire having a diameter of about 1.8 to 2.6 mm is preferably used. A support wire sheath 4 is provided on the periphery of the support wire 1 by extrusion coating of a resin. As the material of the support wire sheath 4, polyethylene such as low-density polyethylene, medium-density polyethylene, and high-density polyethylene is preferably used.

The optical unit 2 is a unit in which a plurality of optical fiber cores are collectively covered with an ultraviolet curable resin or the like. The outer diameter of the optical unit 2 is set according to the number of optical fibers constituting the optical unit. For example, an optical unit 2 having an outer diameter of 2.2 to 2.7 mm including 12 to 24 optical fibers is used. It is preferably used. The aluminum pipe 3 is suitably manufactured by an aluminum conform or welded pipe drawing, and is preferably manufactured while housing the optical unit 2. The inner diameter of the aluminum pipe 3 is preferably set to be larger than the outer diameter of the optical unit 2 housed therein by about 1.5 to 2.5 mm. If the thickness of the aluminum pipe 3 is too small, the mechanical strength is inferior. If the thickness is too large, the material cost and the cable weight increase, so that the thickness is preferably about 0.6 to 0.8 mm. A pipe sheath 5 is provided on the circumference of the aluminum pipe 3 by extrusion coating of a resin. As the material of the pipe sheath 5, the same material as the material of the support wire sheath 4 is preferably used.

In the aerial optical cable of the present embodiment, an aluminum pipe 3 is manufactured while housing the optical unit 2, and then a pipe sheath 5 is formed on the periphery thereof to manufacture a cable main body 10, which is separately supported. A support wire sheath 4 is formed on the circumference of the wire 1 and then the cable body 1 is wound around the support wire 1.
It is obtained by winding 0. If the winding pitch of the cable body 10 around the support wire 1 is too small, the production line speed decreases and distortion to the optical fiber increases, and if it is too large, the cable body easily moves.
About 500 mm is preferable.

According to the overhead optical cable of this embodiment, the aluminum pipe 3 housing the optical unit 2 has better mechanical strength than the conventional loose tube, and it is necessary to provide a tensile strength wire for reinforcement. Absent. Therefore, by using the aluminum pipe 3, the mechanical characteristics of the overhead optical cable can be significantly improved, and at the same time, the extrusion workability when manufacturing the cable body 10 is improved, and the cost is reduced. In addition, the aluminum pipe 3 has an advantage that it is easier to bend and harder to buckle during bending than a conventional stainless steel pipe. Further, since the cost is considerably low, the cost can be significantly reduced. Further, in this embodiment, since the optical fiber is used in the form of the optical unit 2, the optical fiber hardly undergoes micro-bending and is hardly affected by moisture from outside, so that the jelly is not filled in the aluminum pipe 3. It can be. Therefore, workability during manufacturing is good, cost can be reduced, and the weight of the cable can be reduced. Further, since the overhead optical cable of this embodiment has a simple structure in which the cable main body 10 is wound around the support wire 1, it is easy to manufacture, and the support wire 1 and the cable main body 10 can be easily separated as necessary. can do.

FIG. 2 is a sectional view showing a second embodiment of the overhead optical cable according to the present invention. In this figure, the same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof may be omitted. The overhead optical cable according to the present embodiment has a support wire 1.
And a cable body 10 having an aluminum pipe 3 in which the optical unit 2 is housed. In this embodiment, a collective sheath 7 is formed directly on the periphery of the support wire 1, and the support wire sheath 4 in the first embodiment is not provided. In this embodiment, a pipe sheath 6 is provided on the periphery of the aluminum pipe 3 by extrusion coating of a resin. As the material of the pipe sheath 6, polyethylene such as low-density polyethylene, medium-density polyethylene, and high-density polyethylene is preferably used. As the material of the collective sheath 7, the same material as the support wire sheath 4 in the first embodiment is preferably used. If the thickness of the collective sheath 7 is too thin, the mechanical strength is deteriorated, and if it is too thick, the outer diameter becomes large. Therefore, it is preferable that the thickness of the thinnest portion is about 0.5 to 0.7 mm. It is formed.

In the overhead optical cable of this embodiment, an optical unit 2 is accommodated in an aluminum pipe 3 and a pipe sheath 6 is provided around the optical unit 2 to produce a cable body 10.
With the support wire 1 attached parallel to this, the collective sheath 7
Are collectively extruded and coated to have a circular cross section. According to the overhead optical cable of the present embodiment, the same effects as those of the first embodiment can be obtained by using the aluminum pipe 3 and the optical unit 2.
Since the support wire 1 and the aluminum pipe 3 have a structure integrated by the collective sheath 7, there is an advantage that handling is easy and workability at the time of laying is good.

[0013]

EXAMPLES Hereinafter, the effects of the present invention will be clarified by showing specific examples. (Example 1) An overhead optical cable having the structure shown in Fig. 1 was prepared. As the optical unit 2, an optical fiber having an outer diameter of 2.7 mm, in which 24-core optical fibers are collectively coated with an ultraviolet curable resin, was prepared. The aluminum pipe 3 is used for the optical unit 2 by the welding and drawing method.
Diameter 5.1mm, wall thickness 0.7m manufactured while storing
m. A polyethylene resin was extruded and coated on the circumference of the aluminum pipe 3 to form a pipe sheath 5 to obtain a cable body 10. The outer diameter of the pipe sheath 5 was 7.1 mm. On the other hand, the supporting wire 1 has an outer diameter of 2.6 m.
A galvanized steel wire having a length of m was prepared, and a resin of the same material as that of the pipe sheath 5 was extruded and coated on the periphery thereof to form a support wire sheath 4. The outer diameter of the support wire sheath 4 was 4.6 mm. The cable main body 10 obtained above was wound around the support wire 1 obtained above at a pitch of 500 mm to obtain an overhead optical cable. The thickness of the obtained overhead optical cable was 7.1 mm × 11.7 mm.

Example 2 An overhead optical cable having the structure shown in FIG. 2 was prepared. The same optical unit 2, aluminum pipe 3, and support wire 1 as those in Example 1 were used. First, a polyethylene resin was extruded and coated on the circumference of the aluminum pipe 3 to form a pipe sheath 6, and a cable body 10 was obtained. The outer diameter of the pipe sheath 6 was 7.1 mm. With the support wires 1 attached to the cable body 10, a resin of the same material as that of the pipe sheath 5 in the first embodiment is collectively extruded and coated on the periphery thereof to form a collective sheath 7, and the overhead optical cable is formed. I got The obtained overhead optical cable had a circular cross section and an outer diameter of 11 mm.

An optical signal was transmitted using the optical unit 2 of the overhead optical cable obtained in the first and second embodiments. After testing the mechanical properties of the overhead optical cable,
No increase in light loss occurred up to a lateral pressure load of 400 kg / 50 mm. Regarding impact characteristics, no increase in light loss occurred even with an impact load of 1 kg · m. Also, when wound around a mandrel having a radius five times the outer diameter of the overhead optical cable, no increase in light loss occurred and it was confirmed that the cable had good strength against lateral pressure, impact, and bending. .

[0016]

As described above, the overhead optical cable according to the present invention is formed by integrating the aluminum pipe containing the optical fiber and the support wire, and is therefore good against side pressure, impact or bending. It has high strength. Also, since the number of components is small and the aluminum pipe itself can be obtained at low cost, the cost can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of an overhead optical cable according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the overhead optical cable of the present invention.

FIG. 3 is a sectional view showing two examples of a conventional overhead optical cable.

FIG. 4 is a cross-sectional view showing another two examples of the conventional overhead optical cable.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Support wire, 2 ... Optical unit (optical fiber), 3 ... Aluminum pipe, 4 ... Support wire sheath, 5, 6 ... Pipe sheath,
7: Collective sheath, 10: Cable body

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akira Uejima 1440, Mukurosaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Plant (72) Inventor Suehiro Miyamoto 1440, Misaki, Sakura City, Chiba Prefecture Inside Fujikura Sakura Plant

Claims (3)

[Claims] 1. An overhead optical cable, wherein an aluminum pipe containing an optical fiber and a support wire are integrated. 2. An aluminum pipe in which an optical fiber is housed is wound around a supporting wire.
The optical fiber cable described. 3. The overhead optical cable according to claim 1, wherein the aluminum pipe containing the optical fiber and the support wire are collectively covered with a collective sheath.