JPH0331831B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention is directed to optical fiber composite overhead ground wires (hereinafter referred to as
This relates to the twisted wire method such as OPGW). [Prior Art] An OPGW is constructed by twisting wires such as aluminum-covered steel wires into a cylindrical shape around an optical fiber unit (also referred to as an OP unit) that includes a plurality of optical fibers. At this time, irregularly shaped wires with fan-shaped cross sections are often used so as not to put pressure on the internal optical fiber unit by twisting the wires together. However, if such irregularly shaped strands are simply twisted together, since steel is contained inside the strands, the strands will be twisted together with a large residual stress. For this reason, if the tension at both ends is loosened after twisting, a problem arises in that the twist returns and unravels. Therefore, a method has conventionally been adopted in which the irregularly shaped wires are given a helical twist in advance through a preform process to prevent stress from remaining during twisting. This method is used, for example, in JP-A-60-
It is disclosed in detail in publications such as Nos. 154828 to 154832. In the preform process of these methods, in order to remove internal stress due to twisting, the deformed wire is wound around a bobbin and subjected to strain removal treatment such as annealing. Then, the irregularly shaped wires with internal stress removed in this way are twisted together at the pitches shaped during preforming to manufacture OPGW. [Problems to be Solved by the Invention] However, even with such conventional methods, it has been impossible to completely remove stress and twist. This is because if an attempt is made to completely remove the strain by annealing or the like, the spirally twisted shape created by the preform process will also be lost. Therefore, in the conventional method, some stress remains in the irregularly shaped wires, which are twisted together to form OPGW.
Due to the residual stress in the overhead wire,
As the OPGW rotated, the optical fibers inside were untwisted or further twisted. For this reason, forces such as compression and tension are applied to the optical fiber, resulting in problems such as a significant reduction in optical transmission loss and breakage of the optical fiber. An object of the present invention is to provide a method for twisting irregularly shaped strands that can be twisted while minimizing the residual stress that causes such problems. [Means for Solving the Problems] In the method for twisting irregularly shaped wires of the present invention, the twisting pitch when twisting irregularly shaped wires around an optical fiber unit is changed so that both ends of the irregularly shaped wires are adjusted after the preform process. It is characterized by the pitch of the twist that is achieved when it is released into a state with almost no distortion. [Function] As described above, even a deformed wire that has been subjected to strain removal treatment such as annealing still has some residual stress. Therefore, when a certain length of the deformed wire is taken out after the preform process and both ends are left open, the twist will be slightly untwisted due to the relaxation of the residual stress. The twist pitch achieved in this state is, for example, about 10 to 20% larger than the pitch formed in the preform process. Therefore, when twisting together the pitches formed in the preform process as in the past, the twisting is done with the distortion remaining. On the other hand, in the present invention, since both ends of the deformed wires are released and twisted at the twist pitch that would be in a state with almost no strain, the wires can be twisted with almost no residual strain. [Example] Example 1 Replaceable mold having a cross section as shown in Fig. 1
Manufactured OPGW. In FIG. 1, 1 is an OP cable, 2 is an aluminum pipe, 3 is a deformed aluminum-covered steel wire as a deformed wire, and 6 is an optical fiber unit. The total cross-sectional area of OPGW is ^55mm2 , and the outer diameter is
It was 9.6mm. The diameter of the aluminum pipe was 5.0 mm, and six deformed aluminum covered steel wires with an equivalent round wire diameter of 3.23 mm were used. To explain the twisting process, first, deformed aluminum-covered steel wires were shaped using the preform process method disclosed in JP-A-60-154832.
At this time, the pitch of the twist shaped in the preform process (hereinafter referred to as preform pitch) is measured, and then the irregularly shaped wire is cut and partially taken out.
Both ends were kept open to maintain an almost distortion-free state, and the pitch of twist achieved at that time (hereinafter referred to as free pitch) was measured. The preform pitch was 136mm and the free pitch was 157mm. Next, using the twisting method disclosed in the above publication, the wires were twisted around the optical fiber unit so that the twisting pitch was 157 mm, the same as the free pitch. The OPGW obtained in this way is wired,
The rotation of the stranded wire was measured to relieve the stress that occurs after the overhead wire is installed. The twisted wire rotation was evaluated by measuring the length of the OPGW covered by one rotation.
The results are shown in Table 1. Example 2 Same as Example 1, exchange type OPGW shown in FIG.
was manufactured. The total cross-sectional area of OPGW is ^70mm2 ,
Its outer diameter was 10.6 mm. The aluminum pipe used was one with a diameter of 5.0 mm, and the six irregular-shaped aluminum covered steel wires with an equivalent round wire diameter of 3.64 mm were used. Preform pitch and free pitch were measured in the same manner as in Example 1. The preform pitch was 136mm and the free pitch was 157mm.
Next, the twisting pitch is the same as the free pitch.
A twisted OPGW was produced with a length of 157 mm. This OPGW was connected to an overhead wire, and the rotation of the stranded wire after the overhead wiring was measured, and the results are shown in Table 1. Example 3 A snow-resistant OPGW as shown in FIG. 2 was manufactured. In FIG. 2, 4 is a spacer, 5 is an optical fiber, 6 is an optical fiber unit, 7 is an aluminum pipe, and 8 is a deformed aluminum-covered steel wire. The total cross-sectional area of the OPGW was 90 mm ² and its outer diameter was 12.7 mm. The aluminum pipes used had a diameter of 6.5 mm, and the deformed aluminum clad steel wires used were eight pieces with an equivalent round wire diameter of 3.57 mm and one piece with an equivalent round wire diameter of 3.95 mm. It was preformed in the same manner as in Example 1, and the preform pitch and free pitch were measured. The preform pitch was 175mm and the free pitch was 195mm. In the same manner as in Example 1, a twisted OPGW was produced by setting the twisted pitch to 195 mm, which is the same as the free pitch. This OPGW was connected to an overhead wire, and the rotation of the stranded wire after the overhead wiring was measured, and the results are shown in Table 1. Comparative Example 1 OPGW was produced in the same manner as in Example 1, except that the twisting pitch in Example 1 was 136 mm, which is the same as the preform pitch.
The twisted wire rotation of the obtained OPGW was measured and is also shown in Table 1. Comparative Example 2 In Example 2, the twisting pitch was set to 136mm, the same as the preform pitch.
Manufactured OPGW. Regarding the obtained OPGW,
The twisted wire rotation was measured and shown in Table 1. Comparative Example 3 In Example 3, the twisting pitch was set to 175 mm, the same as the preform pitch, and
Manufactured OPGW. The twisted wire rotation of the obtained OPGW was measured and shown in Table 1.

【table】

〔Effect of the invention〕

As explained above, according to the wire twisting method of the present invention, irregularly shaped strands can be twisted around an optical fiber unit while minimizing internal stress. Therefore, the rotation of the stranded wire after the overhead wire has been completed can be significantly reduced compared to the conventional method, and the conventional problems caused by untwisting of the overhead wire can be solved.

[Brief explanation of the drawing]

Figure 1 shows the exchange type manufactured in the example.
FIG. 3 is a cross-sectional view showing the OPGW. FIG. 2 is a sectional view showing the anti-snow accretion type OPGW manufactured in the example. In the figure, 1 is OP cable, 2 is aluminum pipe, 3 is deformed aluminum covered steel wire, 4 is spacer, 5 is
6 is an optical fiber, 6 is an optical fiber unit, 7 is an aluminum pipe, and 8 is a deformed aluminum-covered steel wire.

Claims (1)

[Scope of Claims] 1. A method for twisting irregularly shaped wires, which comprises twisting a plurality of irregularly shaped wires, which have been given a spiral twist in advance through a preform process, around an optical fiber unit at a predetermined pitch, comprising: A method for twisting irregularly shaped strands, characterized in that the twisting pitch is set to the twist pitch achieved when both ends of the irregularly shaped strands are released after the preforming process to create a state with almost no distortion.