JPH08190036A - Optical fiber cable manufacturing method - Google Patents

Abstract

(57) [Summary] [Purpose] The FRP sheath 20 may be used in a non-metallic optical cable because a metal sheath cannot be used. In this case, the FRP was wound completely around the cable core 10 and then completely cured by thermal crosslinking. Therefore, equipment and time are required to carry out the thermal crosslinking, and the cable manufacturing cost is correspondingly increased. To solve this point. [Structure] An unhardened string-like FRP is used for the cable core 10
After wrapping over, the plastic outer sheath 30 is immediately extruded without heat crosslinking. Then, the heat during this molding cross-links and hardens the uncrosslinked FRP. Even if it is not completely crosslinked during extrusion,
After that, curing progresses naturally (in the state of the cable), reaching a value sufficient to protect the cable from external factors such as compression and impact.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a non-metallic type F
The present invention relates to a method for manufacturing an optical fiber cable with an RP armor.

[0002]

2. Description of the Related Art When laying an optical fiber cable in a strong electric field area along a power transmission line or a railroad, a lightning-prone area, or the like, a nonmetallic optical fiber cable is desirable in consideration of the influence of induction or lightning strike. If there is a possibility that external factors such as compression and impact may be caused by directly burying this cable,
It is necessary to provide protection for the purpose of improving lateral pressure strength.

In the case of the non-metallic type, an outer sheath made of a metallic material cannot be used for this protection. Therefore, for example, a cable with an FRP sheath 20 as shown in FIG. 1 may be used. Reference numeral 10 in the figure shows an example of a non-metallic cable core, 12 is a tension member (for example, a polyethylene coating is provided on the center of FRP), 14 is an optical fiber core, and 1
6 is a buffer layer, 18 is a presser roll, and 19 is an inner sheath (polyethylene or the like).

The sheath 20 is generally formed by a method in which an uncured FRP material is wound around the cable core 10 and then completely cured by thermal crosslinking. Exterior 20
The FRP reinforcing material used in the above is a glass fiber or the like, and the matrix is a thermosetting resin such as an unsaturated polyester resin or an epoxy resin. The uncured FRP is
It refers to a material that has not been completely cured by impregnating glass fiber or the like as a reinforcing material with a matrix resin. It includes those immediately after being impregnated with resin, but also includes those that are in a semi-cured state after being slightly heated. In this state, since the rigidity is low, it can be easily wound around the cable core 10.

An outer sheath 30 is made of polyethylene, vinyl chloride or the like. When FRP is used as a cable exterior material, it is common to protect it with an outer sheath 30 to prevent wear of the FRP. In the case of a non-metallic cable, the outer sheath 30 is made by extrusion of plastic.

[0006]

As described above, the exterior 2
The FRP of 0 was completely cured through a thermal crosslinking process. Therefore, equipment and time are required to carry out the thermal crosslinking, and the manufacturing cost of the cable is increased accordingly. The above problem does not occur if the FRP after being completely cured is used, but the completely cured FRP has extremely high rigidity. Therefore, when the thickness exceeds a certain level, it is almost impossible to wind it around the cable core 10.

[0007]

[Means for Solving the Problems] After winding an uncured FRP on the cable core 10, a plastic outer sheath 30 is applied to the uncured FRP without heat-crosslinking.

[0008]

[Operation] As described above, FR is used as the exterior material for optical cables.
If P is used, it is provided with an outer sheath 30 for protection, and in the case of a non-metallic cable, the outer sheath 30 is made by extrusion of plastic. The heat at the time of this extrusion cross-links the uncrosslinked FRP. Even if the resin is not completely crosslinked during extrusion molding, the curing will naturally proceed after that (in the state of the cable).

In addition to glass fiber, the FRP reinforcing material is
Aramid fiber, carbon fiber, etc. may be used. As the matrix plastic, a thermosetting resin such as unsaturated polyester resin, epoxy resin or phenol resin is used.

The outer sheath 30 is made of polyethylene, vinyl chloride or the like. The extrusion molding temperature is about 200 ° C., and this heat is applied for several seconds to 1 minute during molding, so that the FRP crosslinking proceeds due to this heat. In addition, low temperature fast curing FRP (Nikkan Kogyo Shimbun, industrial materials,
Cross-linking and curing progresses even more when using the November 93 issue, p.24-28).

When the outer sheath 30 is extruded, the outer casing 20 is formed.
Even if the FRP of is not completely cured, then the curing proceeds gradually (in the state of becoming a cable) to reach the required strength.

[0012]

As described above, since the uncured FRP is wound around the cable core, and the uncured FRP is heated and crosslinked, a plastic outer sheath is applied.
It has the following effects. (1) Since the conventional FRP thermal crosslinking step is eliminated, the cable can be manufactured at a lower cost than before. (2) Even in the case of an FRP having a relatively small wire diameter and capable of being wound around a cable core even in a cured state, when the present invention is applied, the FRP remembers the spiral shape on the cable core after winding and curing. Therefore, rather than using the cured FRP,
It is expected that the compression / side pressure strength and the flexibility will be improved.

[Brief description of drawings]

1A and 1B are explanatory views common to a conventional technique and an embodiment of the present invention, in which FIG. 1A schematically shows a state in which a cable is viewed from the side, and FIG. Show.

[Explanation of symbols]

 10 Non-metallic cable core 12 Center tension member 14 Optical fiber core 16 Buffer layer 18 Presser winding 19 Inner sheath 20 Exterior 30 External sheath

Claims (1)

[Claims] 1. An optical fiber cable having an outer sheath formed by winding a string-shaped FRP having a thermosetting resin as a matrix on a non-metallic cable core, and having a plastic outer sheath thereon. On the occasion,
A method for manufacturing an optical fiber cable, characterized in that the uncured FRP is wound around the cable core, and then the outer sheath is immediately applied without thermally crosslinking the uncured FRP. .