JPH11337783A - Optical cable - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to reduce an outside diameter and to enhance the degree of freedom in a bending direction by forming a cylindrical body by molding a belt-like material to a cylindrical shape and constituting at least part of the cylindrical body from any among fiber reinforced plastic, metallic material and parallel continuous metallic wire reinforced plastic. SOLUTION: The cylindrical body 2 is molded to the cylindrical shape by superposing and adhering both edges of the belt-like material along a longitudinal direction in a joint part 5. The cylindrical body 2 has a three-layered structure consisting, successively from its inner peripheral side, of a water absorption layer, tension layer and laminated layer. The tension layer is required to have high tensile strength (for example, 100 to 2000 MPa) bearing the tensile strength of the optical fiber 10. When fibers are used for the filter reinforced plastic, glass fibers, carbon fibers, aramid fibers, etc., are exampled. Iron, aluminum, etc., or their alloys are used as the metallic materials. The parallel continuous metallic wire reinforced plastic formed by lining up plural long-sized metallic wires in parallel with each other and integrating these wires with a resin is used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical cable having a structure in which an optical fiber core is accommodated, and more particularly to an optical cable having a small outer diameter and a high degree of freedom in a bending direction. Capable optical cable.

[0002]

2. Description of the Related Art FIG. 8 shows an example of a conventional optical cable. An optical cable 30 shown in FIG.
8 made of polyethylene or the like,
A tension member 17 such as two steel wires vertically attached to both sides of the body is collectively covered with a sheath 23 made of polyethylene or the like, and the cylindrical body 8 is filled with the filler 4. As the tension member 17, for example, an outer diameter of 0.6
A thickness of about 2.6 mm is used, and the thickness of the sheath 23 that covers the thickness is usually 1.0 to 5.0 mm.

[0003]

The above optical cable has the following problems. That is, in the optical cable 30, it is necessary to use a tension member having a predetermined thickness or more in order to obtain a sufficient tensile strength. For this reason, it is necessary to form the sheath 23 covering the tension member 17 thick, and there has been a dissatisfaction that the outer diameter of the optical cable becomes large. The optical cable 30
Has two tension members 17 vertically attached to both sides of the cylindrical body 8, so that the bending rigidity is not uniform in the circumferential direction. That is, for example, the optical cable 30
When the optical cable 30 is bent in the direction in which the two tension members 17 are arranged in parallel (in the horizontal direction in the figure), a tensile force or a compressive force is applied to the low-elasticity tension member 17, and the optical cable 30 is hardly bent. On the other hand, it is relatively easy to bend the optical cable 30 in a direction (vertical direction in the figure) perpendicular to the parallel direction. As described above, the optical cable 30 has a low degree of freedom in the bending direction, and is difficult to handle during operations such as laying and connection. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical cable that can reduce the outer diameter and can increase the degree of freedom in a bending direction.

[0004]

An optical cable according to the present invention comprises:
A tubular body containing the optical fiber core is covered with a sheath, and the tubular body is formed by molding a band-shaped material into a tubular shape. At least a part of the tubular body is made of a fiber-reinforced plastic, a metal material,
And a parallel continuous metal wire reinforced plastic. Further, the optical cable of the present invention is such that a tubular body accommodating an optical fiber core wire and a tension member attached to the tubular body are collectively covered with a sheath, and the tubular body is formed by molding a band-shaped material into a tubular shape. At least a part of the tubular body may be made of any one of a fiber reinforced plastic, a metal material, and a parallel continuous metal wire reinforced plastic. It is preferable that the cylindrical body is filled with a filler for fixing the optical fiber in the cylindrical body at intervals in the length direction.

[0005]

1 and 2 show one embodiment of an optical cable according to the present invention. An optical cable 10 shown in FIG. 1 has a plurality of, for example, 2 to 20 optical fiber ribbons 1 laminated. The tubular body 2 housed in the state is covered with a sheath 3, and a filling material 4 is filled in the tubular body 2.

As the optical fiber ribbon 1, 2 to 2
A four-core type can be used. The cylindrical body 2 is formed by laminating and bonding both edges of the band-shaped material along the longitudinal direction at the joint portion 5 to form a cylindrical shape. Cylinder 2
Is preferably 0.1 to 0.5 mm in thickness and 3 to 15 mm in outer diameter, and the width of the joint 5 is preferably 2 to 10 mm. For bonding both edges of the band-shaped material at the joint portion 5, for example, a hot melt adhesive made of a polyethylene resin can be used.

The cylindrical body 2 has a three-layer structure including a water absorbing layer 2a, a tensile strength layer 2b, and a laminate layer 2c from the inner peripheral side. The water-absorbing layer 2a is for improving the waterproofness of the optical cable, and it is preferable to use a water-absorbing material such as a nonwoven fabric coated with a water-absorbing material, and the thickness is set to 0.1 to 0.4 mm. Is preferred.

In the optical cable 10 of the present embodiment, the tensile strength layer 2b is responsible for the tensile strength of the optical cable 10, and has a high tensile strength (for example, 1000 to 2000MP).
It is made of fiber reinforced plastic which is the material shown in a). The fibers used for the fiber reinforced plastic include glass fiber, carbon fiber, aramid fiber, polyparaphenylene benzobisoxazole (PB
O) Fibers, polyethylene fibers, polyarylate fibers, silicon oxide fibers, silicon carbide fibers, silicon nitride fibers, alumina fibers, and the like. Examples of matrix resins include epoxy resins, unsaturated polyester resins, bismaleimide resins, and polyimides. Resin or the like can be used. Further, as the matrix resin, a thermoplastic resin such as polyethylene, nylon, polyvinyl chloride or the like can be used. In particular, it is preferable to use glass fiber, carbon fiber, and aramid fiber as the fibers, and use an epoxy resin as the matrix resin, or use a glass fiber reinforced resin using an unsaturated polyester resin as the matrix resin from the viewpoint of improving tensile strength. . Further, it is preferable to use a fiber having a single fiber diameter of 1 to 200 μm, and the fiber content of the fiber reinforced plastic is
It is preferable to set it as 20-80 vol% from a viewpoint of improvement in tensile strength.

The thickness of the tensile strength layer 2b is preferably set to 0.2 to 1 mm. If the thickness is less than 0.2 mm, the tensile strength of the optical cable decreases, and if it exceeds 1 mm, it is not preferable because molding processing becomes difficult in a manufacturing process described later. The laminate layer 2c is used to increase the bonding strength of the tubular body 2 to the sheath 3 and increase the strength of the optical cable 10, and it is preferable to use a material that can be heat-fused to the sheath 3, for example, ethylene vinyl acetate copolymer. Merging (EV
A), ethylene acrylic acid copolymer (EAA), ethylene ethyl acrylate copolymer (EEA) and the like are preferably used.

A gap between the inner wall of the cylindrical body 2 and the optical fiber ribbon 1 is filled with a filler 4. This filler 4
Is for fixing the optical fiber ribbon 1 in the cylinder 2 and is preferably filled at intervals in the longitudinal direction of the cylinder 2. As the filler 4, a hot-melt resin which is semi-solid at room temperature and has a property of melting when heated is suitably used.
Styrene-based elastomers, rubber-based resins, and the like can be used. It is preferable that a tear string 6 be vertically attached on the cylindrical body 2. The sheath 3 can be made of polyethylene or the like. The thickness of the sheath 3 is 0.5 to
It can be 4.0 mm.

Hereinafter, a method of manufacturing the optical cable 10 having the above configuration will be described with reference to FIGS. First,
A band-shaped material 11 having a three-layer structure having the water absorbing layer 2a, the tensile strength layer 2b, and the laminate layer 2c is prepared in advance, and an adhesive is applied to one or both edges 11a and 11b of the band-shaped material 11. (Not shown) is formed. At this time, the adhesive layer is formed on a joining surface to be overlapped when the belt-shaped material 11 is formed into a tubular shape in a step described later.

Next, on the water-absorbing layer 2a side of the belt-shaped material 11,
A plurality of optical fiber ribbons 1 are arranged in parallel with the strip material 11. At this time, the strip material 11 and the optical fiber ribbon 1 may be in contact with each other or may be separated from each other. Next, the filler 4 is filled on the water-absorbing layer 2a of the belt-shaped material 11 and the optical fiber ribbon 1 at intervals in the length direction. At this time, the amount of the filler 4 to be filled needs to be at least enough to fix the optical fiber ribbon 1 to the inner wall of the cylindrical body 2 when the band-shaped material 11 is formed into the cylindrical body 2. In addition, if the amount of the filler 4 is such that the space between the inner wall of at least a part of the cylindrical body 2 in the length direction and the optical fiber ribbon 1 can be buried without a gap, the waterproof function of the optical cable 10 is improved. preferable.

Subsequently, the strip material 11 and the optical fiber ribbon 1 are introduced into the former 12. Former 1
2 is formed in a conical tubular shape whose diameter gradually decreases from the inlet 12a into which the strip-shaped material 11 and the optical fiber ribbon 1 are inserted, and passes through the former 12. 11 is a water absorbing layer 2a
Are bent to surround the periphery of the optical fiber ribbon 1 with the inner peripheral side, and both edges 11 a, 11
The cylindrical body 2 in which b overlaps is formed.

Thereafter, the adhesive layer on both edges 11a and 11b of the band-shaped material of the cylindrical body 2 coming out of the former 12 is heated by a heating means 14 such as a hot jet to melt the adhesive of the adhesive layer.
By bonding, a joint 5 is formed. Subsequently, in a state where the tear string is longitudinally attached to the cylindrical body 2 on which the joint portion 5 is formed, the cylindrical body 2 is introduced into the extruder 13 and passed therethrough, thereby covering the cylindrical body 2 with a resin such as polyethylene. Thus, the sheath 3 is formed, and the optical cable 10 is obtained.

In the optical cable 10 of the present embodiment,
Since the tensile strength layer 2b of the cylindrical body 2 is made of fiber reinforced plastic having high tensile strength, the optical cable 10
The tension member can be made unnecessary without lowering the tensile strength. For this reason, the sheath 3 can be formed thinner and the outer diameter can be reduced as compared with a conventional optical cable having a tension member. Further, since the optical cable 10 has a substantially uniform structure in the circumferential direction as compared with the conventional example having two tension members shown in FIG. 8, the bending rigidity is uniform in the circumferential direction, and the bending direction is free. The degree is high. For this reason, handleability in laying and connecting can be improved.

Further, in the optical cable 10 of the above embodiment, the steps of molding the cylindrical body 2 and storing the optical fiber ribbon 1 inside the cylindrical body 2 in manufacturing the optical cable 10,
Can be manufactured by a method of continuously performing a step of coating the sheath 3 with the sheath 3. For this reason, easy and efficient manufacturing is possible with a small number of steps.

Further, the optical cable of the present invention is not limited to the above-described embodiment, and as shown in FIG. 5, the cylindrical body 22 may have a tensile strength layer 22b made of a metal material. As the metal material, iron, aluminum, stainless steel, copper, or an alloy containing these as main components can be used. The thickness of the tensile strength layer 22b is
It is preferable that the thickness be 0.2 to 2.0 mm. If the thickness is less than 0.2 mm, the tensile strength of the optical cable decreases,
If it exceeds 2.0 mm, the weight becomes large and handling becomes difficult, which is not preferable. The tensile strength layer 22b is
The corrugated strip may be formed in a tubular shape.

The tensile strength layer 22 made of such a metal material
Also in the case where the cylindrical body 22 having b is used, similarly to the optical cable 10 of the above-described embodiment, the effect of increasing the strength of the cylindrical body 22, reducing the outer diameter of the cable, and increasing the degree of freedom in the bending direction is obtained. be able to. In addition to this, in the optical cable shown here, since the cylindrical body 22 having the tensile strength layer 22b made of a metal material that is easy to form is used, the band-shaped material is curved using the former 12, and is formed into a cylindrical shape. Work can be facilitated and manufacturing can be facilitated.

Further, as shown in FIG. 6, in the optical cable of the present invention, the tensile strength layer 32b of the cylindrical body 32 is formed by arranging a plurality of long metal wires 32d in parallel with each other, and integrating these with a resin. It can also be made of metal wire reinforced plastic. The thickness of the tensile strength layer 32b is 0.2 to
Preferably, it is 1.0 mm. This thickness is 0.2m
m, the tensile strength of the optical cable is reduced to 1.0 m
If it exceeds m, molding processing becomes difficult, which is not preferable.
As the material of the metal wire 32d, iron, aluminum, stainless steel, copper, an alloy containing these as a main component, or the like can be used, and the outer diameter is preferably 0.2 to 1.0 mm. The interval between the metal wires 32d is preferably 0 to 1 mm. In addition, as the resin, a thermoplastic resin such as polyethylene, nylon, and polyvinyl chloride can be used in addition to an epoxy resin, an unsaturated polyester resin, a bismaleimide resin, and a polyimide resin. It is also possible to use the above-mentioned fiber reinforced plastic.
As described above, by forming the tensile strength layer 32b of the parallel continuous metal wire reinforced plastic having the metal wire 32d, the cable strength can be further improved.

FIG. 7 shows another embodiment of the optical cable according to the present invention. The optical cable 20 shown in FIG.
A tension member 7 is vertically attached on the circumference of the above-described cylinder 2,
These are collectively covered with a sheath 13 made of polyethylene or the like. Since the optical cable 20 uses the cylindrical body 2 made of a material having high strength, the diameter of the tension member 7 is smaller than that of the tension member 17 used in the conventional optical cable 30 shown in FIG. Those having a size of 2.0 mm can be used. For this reason, the sheath 13 is thinner than the conventional example, for example, 0.6 to
It can be 4.0 mm.

Therefore, in the optical cable 20 shown here,
Similarly to the optical cable 10 of the above-described embodiment, the outer diameter of the cable can be reduced. Also tension member 7
By making the outer diameter smaller, the deviation of the bending rigidity in the circumferential direction can be made smaller and the degree of freedom in the bending direction can be made higher than in the conventional example.

In the optical cables of the above embodiments,
The cylindrical body has a three-layer structure including a water-absorbing layer, a tensile strength layer, and a laminate layer. However, the present invention is not limited to this, and the cylindrical body may have a two-layer structure including a tensile strength layer and a laminate layer, or a tensile strength. It is also possible to use only layers. Further, in the optical cable of each of the above embodiments, the tubular body is formed by overlapping both edges of the band-shaped material. However, the present invention is not limited to this, and the tubular body is formed by abutting the end faces of both edges of the belt-shaped material. You may. Further, in each of the above embodiments, the example in which the optical fiber ribbon is accommodated in the cylinder is described.
It is also possible to use a single optical fiber core instead of the optical fiber ribbon.

[0023]

As described above, in the optical cable of the present invention, the outer diameter can be reduced without lowering the tensile strength, and the flexibility in the bending direction can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of an optical cable of the present invention.

FIG. 2 is a sectional view of a main part of the optical cable shown in FIG.

FIG. 3 is a perspective view showing a strip-shaped material used for manufacturing the optical cable shown in FIG. 1;

FIG. 4 is an explanatory diagram of a method of manufacturing the optical cable shown in FIG.

FIG. 5 is a sectional view of a main part showing a modified example of the tubular body of the optical cable of the present invention.

FIG. 6 is a sectional view of a main part showing another modified example of the cylindrical body of the optical cable of the present invention.

FIG. 7 is a sectional view showing another embodiment of the optical cable of the present invention.

FIG. 8 is a sectional view showing an example of a conventional optical cable.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical fiber tape core wire, 2, 22, 32 ... Cylindrical body,
2b, 22b, 32b ... tensile strength layer, 3 ... sheath, 1
0, 20: Optical cable, 32d: Metal wire

Claims (3)

[Claims] 1. A tubular body accommodating an optical fiber core wire is covered with a sheath, and the tubular body is formed by molding a band-shaped material into a tubular shape, and at least a part of the tubular body is made of a fiber-reinforced plastic or a metal material. And an optical cable made of any one of parallel continuous metal wire reinforced plastics. 2. A tubular body accommodating an optical fiber core and a tension member attached to the tubular body are collectively covered with a sheath, and the tubular body is formed by molding a band-shaped material into a tubular shape.
An optical cable, characterized in that at least a part of the cylindrical body is made of any one of a fiber reinforced plastic, a metal material, and a parallel continuous metal wire reinforced plastic. 3. The optical cable according to claim 1, wherein a filler for fixing the optical fiber in the cylinder is filled in the cylinder at intervals in the length direction. .