JP2989640B2 - Pneumatic optical fiber cable and method of manufacturing the same - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic optical fiber cable and a method of manufacturing the same, and facilitates pneumatic transmission of an optical fiber unit into a pipe.

[Problems to be solved by conventional technology and invention]

2. Description of the Related Art Conventionally, a pneumatic optical fiber cable has been obtained by sending an optical fiber unit having an outer layer made of foamed polyethylene into a pipe made of polyethylene or the like by using compressed air and laying the fiber. FIG. 3 shows a typical example of an optical fiber unit, in which seven optical fiber core wires 1 having a diameter of 0.25 mm are twisted together.
Apply an inner layer 2 made of nylon 12 around the outer diameter of 1.0m
m, and an outer layer 3 of foamed polyethylene is further provided therearound to have an outer diameter of 2.0 mm. The reason why foamed polyethylene is adopted as the outer layer is that it is required to be lightweight in terms of the pressure-feeding characteristics.

However, the surface of foamed polyethylene obtained by the usual extrusion method is very smooth, and the surface roughness is 100 μm.
It is as follows. When trying to feed an optical fiber unit having such a smooth surface into a polyethylene pipe by pneumatic feeding, it is possible to use a short polyethylene pipe having a length of 200 m or less, but not a long polyethylene pipe having a length of 300 m or more. Possible or time consuming.

The reason is that a large propelling force cannot be obtained because the outer surface of the foamed polyethylene which is to be a driving force for the compressed air is smooth. Further, it is considered that the smooth outer surface of the foamed polyethylene increases the contact area with the polyethylene pipe and increases the frictional resistance.

[Means for solving the problem]

The present invention has been made from the above viewpoint, and a first aspect of the present invention is an air-pneumatic optical fiber cable in which an optical fiber unit is loosely housed in a pipe. The outer layer of the unit is made of foamed polyethylene having a surface roughness of 200 to 500 μm.

The invention according to the second aspect has a surface roughness of 200 to 500 μm.
m is to pneumatically feed an optical fiber unit having an outer layer of foamed polyethylene into a pipe.

In addition, the surface roughness of the foamed polyethylene outer layer is 200 to 500 μm.
The reason for this is that if it is less than 200 μm, not only is it too smooth to obtain a large propulsive force, but also the contact area with the pipe is too large, the frictional force increases, and pneumatic feeding becomes difficult,
If it is 500 μm or more, the foamed polyethylene may be cut off during production.

As means for roughening the surface of the foamed polyethylene outer layer, for example, there is a method in which foamed polyethylene is extrusion-coated on an optical fiber and then the surface is brushed.

[Action]

Since the outer surface of the foamed polyethylene layer that constitutes the optical fiber unit is rough, a large driving force is obtained,
Since the contact area with the inner surface of the pipe is small, the optical fiber unit is smoothly pneumatically fed.

〔Example〕

FIG. 1 is a sectional view of a pneumatic optical fiber cable according to the present invention. In the figure, 10 is an optical fiber unit, 12 is an optical fiber core having seven twisted fibers, 14 is an inner layer made of nylon 12 which is extrusion-coated around it, and 16 is extrusion-coated on this inner layer 14. A foamed polyethylene outer layer whose surface is later brushed to a roughness of 300 μm, and a polyethylene pipe 18 loosely stores the optical fiber unit 10.

FIG. 2 is a schematic explanatory view of an apparatus for manufacturing the pneumatic optical fiber cable of FIG. In the figure, reference numeral 20 denotes a cylindrical device body as a whole, which is provided with a passage 22 for passing the optical fiber unit 10. Reference numeral 24 denotes an optical fiber unit inlet which is one end of the passage 22, reference numeral 26 denotes an optical fiber unit outlet which is the other end of the passage 22, reference numeral 28 denotes a joint pipe inserted and fixed in the outlet 26, and reference numerals 30 and 30 denote enlarged portions of the passage 22. A roller 32 is provided for sending out the optical fiber unit 10 to the other end of the passage. Reference numeral 32 denotes a compressed air flow passage connected to the passage 22. Reference numeral 18 denotes a polyethylene pipe detachably connected to the pipe 28 and through which the optical fiber unit 10 is pressure-fed.

In the above configuration, when the compressed air is sent from the passage 32 to the passage 22 while rotating the rollers 30, 30, the optical fiber unit 10 is pressure-fed into the polyethylene pipe 18 by the air pressure.

(Specific example) While rotating the rollers 30, 30, the optical fiber unit 10 having a diameter of 2.0 mm and the outer surface of the foamed polyethylene having a roughness of 300 μm is sent out from the compressed air flow passage 32 into the passage 22 at 8 kg / cm ² pressure. Of air.

As a result, the optical fiber unit 10 could be sent into the polyethylene pipe 18 having a length of 1000 m.

〔The invention's effect〕

According to the present invention, since a foamed polyethylene outer surface having an outer layer having an roughness of 200 to 500 μm, which is an outer layer of an optical fiber unit, is pneumatically fed into a pipe, a large propulsive force is obtained and a contact area with the pipe is small. Therefore, the frictional force between the two can be suppressed, so that the air pressure feeding of the optical fiber unit into the long pipe can be performed in a short time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pneumatic optical fiber cable of the present invention, FIG. 2 is a schematic sectional view of an apparatus for manufacturing the cable of the present invention, and FIG. 3 is a sectional view of a conventional optical fiber unit. In the figure, 10: optical fiber unit, 16: foamed polyethylene outer layer, 18: polyethylene pipe, 32: compressed air flow passage.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hideo Suzuki 1440 Mitsusaki, Sakura-shi, Chiba Fujikura Electric Wire Co., Ltd. Inside the Sakura Plant (72) Inventor Tohru Wada 1-5-1 Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. In-company (72) Inventor Yoji Koike 1-5-1, Kiba, Koto-ku, Tokyo Fujikura Electric Wire Co., Ltd. (56) References JP-A-2-50111 (JP, A) (58) Fields investigated (Int. Cl. ^6, DB name) G02B 6/46 G02B 6/44

Claims (2)

(57) [Claims] In an air pressure type optical fiber cable in which an optical fiber unit is loosely housed in a pipe, an outer layer of the optical fiber unit has a surface roughness of 200 to 500.
A pneumatic fiber optic cable made of μm foamed polyethylene. 2. A method for producing a pneumatic optical fiber cable, comprising: pneumatically feeding an optical fiber unit having a foamed polyethylene outer layer having a surface roughness of 200 to 500 μm into a pipe.