JP3296596B2 - Manufacturing method of optical fiber composite overhead ground wire - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an optical fiber composite overhead ground wire used as an overhead ground wire of an overhead transmission line.

[0002]

2. Description of the Related Art A general example of an optical fiber composite overhead ground wire is shown in FIG. This optical fiber composite overhead ground wire 11 is obtained by twisting a metal wire 3 having a segmental cross section around the outer circumference of a metal tube 2 containing an optical fiber 1 in the form of a cable, and twisting a metal wire 4 having a circular cross section around the outer circumference. It is.

An aluminum tube is generally used as the metal tube 2, and an aluminum-coated steel wire is generally used as the metal wires 3 and 4. Although the example of FIG. 2 is a case where the metal wires have two layers, the metal wires may have only one layer. When there are two metal wires, a metal wire having a segment-shaped cross section may be used as the metal wire 4 in the outer layer.

Next, a conventional method for manufacturing such an optical fiber composite overhead ground wire will be described with reference to FIG. When there is only one metal wire (when there is no outer metal wire 4 in FIG. 2)
Sends out the metal tube 2 containing the optical fiber 1 from the supply drum 5, and the metal wire 3
To form an optical fiber composite overhead ground wire 11,
The optical fiber composite overhead ground wire 11 is taken up by the take-up capstan 7 and wound up on the take-up drum 8.

[0005] When the metal wire has two layers (FIG. 2)
Sends out an inner layer stranded wire 9 in which a metal wire 3 is twisted around a metal tube 2 containing an optical fiber 1 from a supply drum 5, and twists a metal wire 4 around the outer periphery with a twisting machine 6 to form an optical fiber. A composite overhead ground wire 11 is formed, and the optical fiber composite overhead ground wire 11 is taken up by a take-up capstan 7 and wound around a winding drum 8.

[0006]

When the metal wire is twisted around the outer periphery of the metal tube or the inner layer stranded wire, the twist is tight,
Preforms and strong back tension are applied to metal wires to make them firm. When the metal wire to be twisted has a segmental cross section, the temperature of the metal wire rises because the forming process is performed from a wire having a circular cross section to a wire having a segmental cross section at the time of twisting.

For this reason, the metal wire of the outer layer is twisted in a stretched state due to the back tension and temperature rise. On the other hand, since the metal tube or the inner layer stranded wire is supplied in a state of almost no tension, when twisted, the phenomenon that the inner metal tube or the inner layer stranded wire is contracted in the longitudinal direction due to the contraction of the outer layer metal wire occurs. . This phenomenon is a preferable phenomenon in that the extra length of the optical fiber is relatively increased. .
It was difficult to suppress the increase in the transmission loss by the conventional manufacturing method.

[0008]

SUMMARY OF THE INVENTION The present invention provides a method for manufacturing an optical fiber composite overhead ground wire which solves the above-mentioned problems, and has a structure formed around an outer periphery of a metal tube containing an optical fiber. In a method of manufacturing an optical fiber composite ground wire by twisting one or more layers of metal wires, a supply drum for supplying an inner layer twisted wire obtained by twisting a metal wire around the metal tube or the outer periphery of the metal tube, A heating device is installed between the metal tube or the stranded wire machine that twists the metal wire around the outer circumference of the inner stranded wire, and the heating device allows the metal tube or inner stranded wire to be wound around the outer circumference of the metal wire. It is characterized in that heating is performed so as to generate elongation substantially equal to elongation due to back tension and temperature rise.

[0009]

[Function] By heating a metal tube or an inner layer stranded wire containing an optical fiber and causing the same expansion as the expansion of the metal wire twisted around its outer circumference by thermal expansion, the shrinkage after the twist is increased. Since the inside and outside of the stranded wire are substantially the same, fine bending of the optical fiber can be prevented, and an increase in transmission loss can be prevented. Therefore, in the present invention, a heating device is provided between the supply drum and the twisting machine, and the heating device heats the metal tube or the inner-layer stranded wire.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIG. In the manufacturing method of the present invention, a heating device 10 is provided between the supply drum 5 and the stranded wire machine 6, and the heating device 10 is provided with the optical fiber-containing metal tube 2 or the inner layer stranded wire 9 sent out from the supply drum 5. Heat through. As the heating device 10, a high-frequency heater capable of efficiently heating a traveling wire rod may be used. Thereafter, the metal wire 3 or 4 is twisted around the outer periphery of the metal tube 2 or the inner-layer stranded wire 9 which has been thermally expanded by heating by the twisting machine 6, and the twisted optical fiber composite overhead ground wire 11 is taken up and the capstan 7 is taken up.
To take up and take up on the winding drum 8.

The heating temperature of the metal tube 2 or the inner-layer stranded wire 9 is as follows:
The temperature at which the metal tube 2 or the inner-layer stranded wire 9 expands by the same degree as the back tension of the metal wire 3 or 4 to be twisted thereon and the elongation due to the temperature rise is set as the temperature.
With this configuration, the shrinkage after the twisting becomes equal between the inside and the outside of the stranded wire, so that it is possible to prevent the optical fiber from being finely bent and to prevent an increase in transmission loss.

[0012]

As described above, according to the present invention, a heating device is provided between the supply drum and the twisting machine, and the heating device heats the metal tube or the inner stranded wire containing the optical fiber. Since the elongation due to thermal expansion is controlled to be about the same as the metal wire twisted on it, the inner metal tube or inner layer stranded wire can be contracted in the longitudinal direction by the outer metal wire after twisting. Therefore, there is an advantage that a fine bend of the optical fiber can be prevented and an increase in transmission loss can be prevented.

[Brief description of the drawings]

FIG. 1 is a line configuration diagram showing one embodiment of a method for manufacturing an optical fiber composite overhead ground wire according to the present invention.

FIG. 2 is a sectional view showing an example of an optical fiber composite overhead ground wire.

FIG. 3 is a line configuration diagram showing a conventional method for manufacturing an optical fiber composite overhead ground wire.

[Explanation of symbols]

 1: Optical fiber (cable form) 2: Metal tube 3, 4: Metal wire 5: Supply drum 6: Twisting machine 7: Take-up capstan 8: Winding drum 9: Inner layer stranded wire 10: Heating device 11: Optical fiber Composite overhead ground wire

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01B 13/00-13/02 H01B 5/10 G02B 6/44

Claims (1)

(57) [Claims] 1. A method for manufacturing an optical fiber composite ground wire by twisting one or more layers of a metal wire around an outer periphery of a metal tube containing an optical fiber, wherein the metal tube or the outer periphery of the metal tube is made of metal. A heating device is installed between a supply drum that supplies an inner layer stranded wire obtained by twisting wires and a stranded wire machine that twists a metal wire around the outer periphery of the metal tube or the inner layer stranded wire. Or the inner layer stranded wire,
A method for manufacturing an optical fiber composite overhead ground wire, comprising heating the metal wire twisted around its outer periphery so that the metal wire stretches by the same degree as the back tension and the temperature rise.