JPH0810568B2 - Electric power / optical composite cable manufacturing method - Google Patents

Description

The present invention relates to a method for manufacturing a power / optical composite cable.

Conventionally, there have been the following problems when laying a power / optical composite cable. That is, the tension at the time of laying causes the electric power core wire (referred to as an electric power insulation wire; hereinafter referred to as the electric power core wire) to be expanded by about 0.4% at the maximum as an initial elongation. However, the optical fiber (the one coated with an optical fiber and the one obtained by twisting or bundling several of the above-mentioned fibers; hereinafter referred to as the optical fiber) is generally said to have an allowable elongation of 0.2%. Therefore, further elongation causes breakage or deterioration of reliability.
Therefore, as described above, when the electric power core wire is stretched by 0.4% at the initial elongation due to the tension at the time of installation, the optical fiber cores twisted at the same pitch are also stretched, and it is necessary to break and reduce reliability.
Therefore, various contrivances have been made in order to reduce the laying tension when laying the power / optical composite cable.

For example, the laying length is reduced by making the laying length shorter than the laying length of the conventional power cable alone, or by arranging a cable feeding device in the laying pipeline to reduce the laying tension.

However, in the former case, the cost is inevitably increased due to the increase in the number of manholes and the number of connection points, and in the latter case, the increase in construction cost is unavoidable.

On the other hand, the problem can be solved by using an optical fiber that does not break even if it is stretched by about 0.4% as much as the power fiber, and does not cause a decrease in reliability. Is difficult in terms of technology and cost.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing an electric power / optical composite cable that does not cause breakage of the optical fiber or deterioration in reliability.

A feature of the present invention is that it applies the elastic strain of the electric power core wire that occurs during twisting. That is, back tension is applied to the power core wire in the power core wire and the optical core wire delivered by the cage of the aggregate machine. In this case, the amount of back tension may be equal to or greater than the value of the installation tension when the installation tension is estimated in advance. Needless to say, a value slightly larger than the estimated laying tension is sufficient because no extra back tension is necessary. On the other hand, the optical fiber line may be normal. In the above state, both are twisted and simultaneously twisted.

 An embodiment of the present invention will be described below with reference to the schematic diagram.

Now, as shown in FIG. 1, three power cores 1 and three optical cores 2 are used.
In the case of manufacturing the electric power / optical composite cable according to the present invention, which consists of the cores, which are gathered at the same time, the holding tape 3 is wound, and the anticorrosion layer 4 is applied, first, as shown in FIG. 6, 7, optical fiber supply drum 8, 9, 10
To the cage of the aggregate machine. Next, for the power supply core supply drums 5, 6, and 7, the installation tension is preliminarily estimated by the supply brake (the supply brake may be any method such as a torque motor type or a band brake type) shown in FIG. 13 as described above. If so, apply back tension slightly higher than the estimated value.

On the other hand, the optical fiber is back tensioned so as not to cause slack during manufacturing.

The supply brake 13 shown in FIG. 3 is provided for each cage, and the brakes can be adjusted independently. By the way, the cable with the cross-sectional view of Fig. 1 has a self-weight of 1,500 kg /
When laying a cable with a length of 500 m at Km, the laying tension is about 250 Kg (however, laying in a straight line). In this embodiment, since the number of power cords is three, the laying tension per power cord is about 90 kg. In the conventional case, the back tension per power core is about 40 to 50 kg, but according to the present invention, the back tension is about 100 kg. On the other hand, it is about 0.5 kg for the optical fiber. After adjusting the back tension for each drum as described above, the supply cage is twisted through the collective spinneret 11 which is rotated in the direction of arrow A in FIG. 2 (or may be reversed), and tape winding is performed as required in FIG. While rotating the taping head in the direction of arrow B (or vice versa). In the power / optical composite cable assembled by the above-mentioned method, the back tension at the time of assembly is relaxed and the elastic elongation generated at the assembly is restored by the time the next official approval of coating of the anticorrosion layer is completed. In that case, the optical cores gathered at the same pitch are compressed, and as a result, an amount corresponding to the elastic extension of the power cores is accommodated in the cable as slack.

Generally, as shown in the cross section of FIG. 1, the optical core diameter is much smaller than the power core diameter. Therefore, there are many spaces that allow the slack of the optical fiber. Further, since the back tension applied to the optical fiber at the time of assembly is as small as about 0.5 kg, the slack can be uniformly and easily generated in the longitudinal direction of the cable.

By laying the electric power and optical composite cable in such a state, a tension state slightly smaller than the tension state at the time of assembly can be reproduced. That is, the tension applied to the optical fiber in question is reduced by an amount corresponding to the elastic elongation of the power core, and there is practically no elongation, but even if there is, it is below the allowable elongation.

In other words, if the conventional method is used, the maximum elongation when laying the power core will be 0.4%.
%, The reliability is lowered, and in the worst case, breakage occurs. However, the elongation was halved by using the manufacturing method of the present invention, and the reliability of the optical fiber was not impaired at all.

As described above, the present invention, by applying back tension to the power core wire in the method of twisting the power core wire and the optical core wire, by twisting the optical core wire while stretching the power core wire,
Since the tension is removed thereafter, it is possible to manufacture an electric power / optical composite cable that does not cause breakage of the optical fiber core or deterioration of reliability when the cable is laid.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of an electric power / optical composite cable, FIG. 2 is a perspective view showing a state in which a power core wire and an optical core wire are twisted together by a collective machine according to the present invention, and FIG. 3 is a book. FIG. 3 is a perspective view showing a state in which the supply drum is set in the cage of the collecting machine according to the invention. 1 is a power core wire, 2 is an optical core wire, 5, 6, 7 are power core supply drums, 8, 9 and 10 are optical core supply drums, 13 is a supply brake (back tension adjusting device)

 ─────────────────────────────────────────────────── ─── Continuation of the front page Judgment body for referee Shinichi Morita Judge Jaeko Kakizawa Judge Akihiro Kitamura (56) Reference JP 57-155504 (JP, A) JP 56-167205 (JP, A) )

Claims (1)

[Claims] 1. A method for twisting a power core wire and an optical core wire of a power / optical composite cable, wherein the power core wire is stretched by applying a back tension greater than the tension applied to the power core wire when the cable is laid. A method for manufacturing an electric power / optical composite cable, which comprises twisting an optical core wire in a state and removing the tension after the twisting.