JPS58211709A - Production of optical cable unit - Google Patents

Abstract

PURPOSE:To permit the increase in the twisting diameter of optical fiber cores and to prevent the increase in transmission loss by twisting plural optical fibers around a long sized tensile body to form a coating layer then relieving the tension. CONSTITUTION:A long sized tensile body 5 has a coating layer 7 of low Young's modulus of an Si resin or the like on the outside circumference of a body 6 consisting of a metallic wire such as steel wire or a fiber reinforced plastic wire or the like and is drawn out with a take-off machine 8. The body 5 is elongated with the machine 8 and a back tension machine 9. Plural optical fiber cores 1 are twisted at a prescribed pitch on the outside circumference thereof with a twister 10. A unit coating layer 11 of an Si resin or the like having low Young's modulus is coated on the outside circumference of such twisted layer with a coater 12 and the layer 11 is calcined with a calcining device 13 to calcine the respective fibers 11 around the cores 1. When the body 5 passes through the machine 8, the tension is relieved and said body shrinks so that the twisting pitch of the respective fiber cores 1 is reduced and a surplus length is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an optical cable unit.

In forming an optical cable, there is a core that prevents the optical fiber from breaking during manufacturing, installation, and use.

Optical fibers are sensitive to stretching. For this reason, conventionally, in order to prevent tension from being applied to the optical fiber, the optical fiber was wound around the outer circumference of a long tensile strength body and fixed, or an extra length was provided inside the protective pipe. It was housed and housed.

However, in order to prevent the optical fiber from stretching with a long tensile strength body, it is necessary to use a long tensile strength body with high strength. However, there are drawbacks such as increased cost and poor flexibility.

In addition, it is technically very difficult to insert the optical fiber core wire into the elongated protective pipe with a suitable extra length.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an optical cable unit in which extra length can be easily added to a cored optical fiber.

The method for manufacturing an optical cable unit according to the present invention involves twisting a plurality of optical fiber core wires around the outer periphery of a tensile elongated body that has been stretched by applying tension, and then applying a unit coating layer with a low Young's modulus to the outer periphery. There is a patent which is characterized in that the structure is integrally covered, and then the tension on the tensile elongated body is removed and the tensile elongated body is contracted to give an extra length to each optical fiber core.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an example of the optical fiber core 1 used in the present invention. This optical fiber core wire 1 is made of nylon on the outer periphery of an optical fiber 2 (one in which a primary coating is provided on the outer periphery of the optical fiber, or one in which a buffer layer with a low Young's modulus is further provided on the outer periphery of the first ash coating). A uniform secondary coating 6 is provided, and a low Young's modulus (for example, 0.01 to 1.OKg/md) is provided on the outer periphery.
) core wire coating layer 4 with a low Young's modulus such as silicone resin.
It has a structure with

Next, the manufacturing method of this example will be explained with reference to FIGS. 2 to 4 (A) CB). The tensile elongated body 5 has a structure in which a coating layer 7 having a low Young's modulus such as silicone resin is provided on the outer periphery of a tensile elongated body main body 6 made of a metal wire such as a steel wire or a fiber-reinforced plastic wire, etc. While being picked up by a pulling machine 8, it is delivered to the production line. Back tension is applied to this tensile elongated body 5 by a back tension machine 9, and a pulling machine 8
and a back tensioning machine 9, the tensile elongate body 5 is stretched within its elastic limit or slightly beyond its elastic limit. A plurality of optical fiber core wires 1 are twisted together at a predetermined pitch by a twisting machine 10 around the outer periphery of the tensile elongated body 5 thus stretched, as shown in FIG. 4(2). A unit coating layer 11 having a low Young's modulus such as silicone resin having a low Young's modulus (for example, 0.01 to 1.0 Kg/ynd) is applied to the outer periphery of the twisted layer of the optical fiber core 1 using an applicator 12.
and then passed through a baking machine 16 to form a unit coating layer 11.
are baked onto the outer periphery of the twisted layer of each fiber core wire 1 to integrate them. When the optical cable unit 14 obtained in this way passes through the pulling machine 8, back tension is no longer applied, and the tensile elongated body 5 contracts as shown in FIG. 4(B). The twist pitch of the wire 1 is reduced, and extra length is given to each fiber core wire 1. At this time, the twisted outer diameter of each optical fiber core wire 1 increases from D to D', but since the unit coating layer 11 is formed of a material with a low Young's modulus, the twisted outer diameter of each optical fiber core wire 1 increases from D to D'. Following the increase in diameter, the radius increases and a stable state is reached. If the unit coating layer 11 is not made of a material with a low Young's modulus, even if the twisted diameter of each party's fiber core 1 attempts to increase when the tensile elongated body 5 shrinks,
As a result, compressive strain is applied to each optical fiber core 1, causing each fiber core 1 to microbend.
This results in an increase in transmission loss. However, in the present invention, since the structure is such that the twisted diameter of each party fiber core wire 1 is allowed to increase when the tensile elongated body 5 is contracted,
It is possible to prevent an increase in transmission loss.

When such tension acts on the optical cable unit 14 and the tensile elongated body 5 stretches, the fiber cores 1 of each party are given extra length, so the tension is absorbed by extending the extra length. , it is possible to prevent breakage, etc. of the fiber core wire 1 of each party.O Such an optical cable unit 14 can be used as an optical cable by sheathing its outer periphery, or by twisting a plurality of units together and covering their outer periphery with a sheath. .

Note that the low Young's modulus fiber coating 114 on the outer p-plane of each optical fiber and the core wire 1 and the coating layer 7 on the surface of the tensile elongated body 5 may be provided as necessary. Also, Hikari 7 Aiba Kokoro 1! IFi
The material is not limited to those having a nylon coating, but may be any material that is wide enough to withstand twisting.

As explained above, in the method for manufacturing an optical cable unit according to the present invention, a tensile elongated body is stretched under tension, and optical fiber cores are twisted around the outer periphery of the long body, and a unit coating layer with a low Young's modulus is coated on the outer periphery. After that, the tension applied to the tensile elongated body is removed, and the tensile elongated body is contracted to shorten the burn pitch of the optical fiber core wire on its outer periphery and provide extra length. Therefore, extra length can be easily provided to the optical fiber core wire. In the present invention, the twisted diameter of the optical fiber cored wire tends to increase when extra length is provided, but since the unit coating layer with a low Young's modulus is twisted around the outer periphery, the twisted diameter of the optical fiber cored wire tends to increase. The increase in transmission loss is not inhibited, and an increase in transmission loss can be prevented.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of an optical fiber core wire used in the present invention, FIG. 2 is a schematic side view of a fissure in which the method of the present invention is carried out, and FIG. Cross section 5 showing an example of an optical cable unit... Tensile elongated body, 8.
...Collection machine, 9...Pack tension, 10...
Stranding machine, 11...Low Young's modulus unit + coating layer, 14.
...Optical cable unit.

Claims (1)

[Claims] After twisting a plurality of optical fiber core wires around the outer periphery of a tensile elongated body that has been stretched by applying tension, the outer periphery is integrally coated with a unit coating I- having a low Young's modulus, and then the above-mentioned 1. An a-adjustment method for an optical cable unit, characterized in that the tension on the long tensile strength body is removed and the long strength strength body is shortened to give a full length to the core fibers of each party.