JPH0434122B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to submarine optical cables using optical fibers as transmission media, and particularly relates to a pressure-resistant layer of submarine optical cables that protects optical fibers (units). [Conventional technology] Optical fiber has characteristics such as low loss, wide bandwidth, and light weight, so it has great economic benefits when used in submarine optical cables that transmit large amounts of information over long distances. There is. FIG. 8 shows an example of the cross-sectional structure of such a submarine optical cable, where 1 is an optical fiber unit, 2 is an optical fiber unit, and 2 is an optical fiber unit.
is a metal pressure-resistant layer that protects the optical fiber unit 1 from high water pressure and is also used as a power supply path, and this voltage-resistant layer 2 is divided into three fan-shaped pieces 2a, 2b, and 2c. It is made up of vertically aligned pieces. The gap 3 in the pressure-resistant layer 2 is filled with a compound, and this compound is also filled in the gaps 3 between the tensile strength wires and metal tubes inside and outside the pressure-resistant layer 2, mainly to prevent water running. It is something that exists. 4 is the pressure-resistant layer 2
A tensile strength wire twisted around the outer circumference of a submarine optical cable, which mainly adds tensile strength to submarine optical cables. Reference numeral 5 indicates a metal tube to which the tensile strength wire 4 is fixed, and the gap 3 between these tubes is also filled with compound. 6 is an insulating layer made of plastic or the like. Note that the outer periphery of the insulating layer 6 may be provided with an exterior covering to prevent damage to the cable, if necessary. The characteristics of such submarine optical cables are
As described in Japanese Patent No. 7361, the divided pieces 2a, 2b, and 2c constituting the pressure-resistant layer 2 have characteristics. That is, the pressure-resistant layer 2 is divided into individual pieces 2a, 2b, 2
c is vertically aligned and fixed to the outer periphery of the optical fiber unit 1, so that it can be made thick enough to protect the optical fiber unit 1 even under high water pressure. ,
Since the pressure-resistant layer is not heat-molded during manufacturing,
This has the effect of not damaging the transmission characteristics of the optical fiber. Further, it has advantages such as being able to function as a tension member. [Problem to be solved by the invention] However, such divided pieces 2a, 2
When the pressure-resistant layer 2 is formed, it is required to finish the surface with the highest possible accuracy to prevent the formation of steps on the inner and outer peripheral surfaces of the pressure-resistant layer 2. Because of the structure, when bending stress etc. are applied, the divided pieces 2
There is a problem in that the mutual bonding surfaces of a, 2b, and 2c are displaced or depressed, and therefore, even if the inside of the pressure-resistant layer 2 is filled with a compound, the water running effect is not sufficiently exhibited. In particular, the optical fiber unit 1
Since it is not possible to apply a large contact force to the pressure-resistant layer 2 and the optical fiber unit 1, the interlayer adhesion between the pressure-resistant layer 2 and the optical fiber unit 1 is low, and there is a fear of water running. The joint surface is also filled with compound, but there is a sufficient risk of water running on this joint surface as well. The present invention has been made in view of these problems, and provides a highly reliable submarine optical cable that effectively prevents water running by applying a satin finish to the side surfaces of the divided pieces. [Example] Figure 1 shows the structure of the pressure-resistant layer adopted in the submarine optical cable of the present invention.
Reference numeral 10c denotes three divided metal pieces each having a fan-shaped cross section, and the portion of the divided metal piece 10c is indicated by a dashed line. Each divided metal piece 10a, 10b, 1
0c is formed to have a sector angle of approximately 120°, and its inner peripheral surfaces 11a, 11b, and 11c are made with unevenness of about 0.005 to 0.02 mm in depth to give a satin finish, as shown in the figure. The side surfaces 12a to which the individual metal pieces 10a, 10b, and 10c are joined,
12b and 12c are also given a similar satin finish. Such metal divided pieces 10a, 10b, 10
c can be produced by performing the final forming by rolling with rolls as in the past, and by applying a satin finish to the roll surface used in this rolling in advance by shot blasting. The degree of satin finish is determined by the inner diameter
When forming a pressure-resistant layer with a diameter of 3.0 mm, it is preferable to use shot blast #10, for example, and set the number of satin grains P to about 80 to 100 pieces/mm ² as shown in FIG. Inner peripheral surfaces 11a, 11b, 11c and side surface 12
After the metal pieces 10a, 10b, 10c, each of which has been subjected to a satin finish, are vertically formed on an optical fiber unit, the outer circumferential surface thereof is pressed with a tensile strength wire. Then, the side surfaces 12a, 12 of each metal divided piece 10a, 10b, 10c
b and 12c are embedded into each other, and the adhesion of the joint surfaces is strengthened. In this case, as shown in Figure 3, the joint surface is the side surface 1.
Condensation may occur by Δθ on the satin surfaces of 2a and 12c, but in this case, depending on the degree of satin finishing, it is preferable to make the fan angle θ° of the metal divided pieces larger by Δθ. Although detailed calculation examples are omitted, this condensation angle △θ value can be set to 0.2° for a satin finish of 0.002 mm depth, 0.4 ° for a satin finish of 0.01 mm, and 0.8 ° for a depth of 0.02 mm. good. As mentioned above, the pressure-resistant layer of the submarine optical cable of the present invention has a matte finish on the side surfaces of the individual metal pieces, so when the pressure-resistant layer is formed with such metal pieces, the interlayer adhesion between the individual pieces increases. However, even during cable molding or when bending stress is applied to the cable, there will be no depression (level difference) or misalignment between the divided pieces, and the optical fiber unit 1 will be sufficiently protected. In addition, since the compound is filled in the matte-finished area, the length of the water running path is longer than that of conventional optical submarine cables with pressure-resistant layers, resulting in a higher water running prevention effect. . Hereinafter, test results for the pressure layer of the submarine optical cable of the present invention will be explained. As shown in Figure 4, the following table shows the outer diameter/inner diameter dimensions of the divided pieces D (iron) of 6.1 mmφ/3.0 mmφ, their lengths of 100 mm, and the outer diameter of the optical fiber unit P of 2.75 mm.
φ and 2 as compound C to prevent water running.
Comparative data on interlayer adhesion when using a liquid-mix room-temperature curing type urethane resin.
The surface roughness after conventional surface finishing is ▽▽▽〜▽▽
Drawing data using the divided pieces of ▽▽, B is after satin finishing (depth 0.02 mm, satin finishing 80-100 pieces/mm ² )
Drawing data (Kg/
mm).

〔Effect of the invention〕

As explained above, in the submarine optical cable of the present invention, the fan-shaped angle of the three pieces constituting the pressure-resistant layer is set between 120.1 degrees and 121 degrees depending on the degree of satin finish, and the joint surface and inner peripheral surface The optical fiber is given a satin finish, and the joint surfaces and inner circumferential surfaces are filled with compound and molded vertically to protect the optical fiber, so the joint surfaces of the three separate pieces do not dig into each other. A cylindrical pressure-resistant layer can be formed, the adhesion between the three divided pieces increases, and the three divided pieces do not slip or fall into each other. As a result, the optical fibers housed inside are sufficiently protected, and the effect of preventing submarine optical cables from running in the water is increased, and the life cycle of submarine optical cables is lengthened, resulting in significant economic benefits. You get the advantage of being

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the pressure layer of the submarine optical cable of the present invention, Fig. 2 is an enlarged plan view of the matte finish surface, and Fig. 3 is an explanatory diagram of the pressure layer of the present invention when it is vertically formed. , Fig. 4 is a perspective view of a submarine optical cable showing a sample for a pull-out test of an optical fiber unit, Fig. 5 is an explanatory diagram showing an experimental apparatus for water running prevention effect, and Fig. 6 shows a cable of the present invention and a conventional submarine optical cable. A graph showing experimental data on the hydrotravel length of
FIG. 7 is a sectional view showing another embodiment of the three-part individual piece;
FIG. 8 is a cross-sectional view of a submarine optical cable whose pressure-resistant layers are made up of three separate pieces. In the figure, 10a, 10b, 10c are individual metal pieces forming a pressure-resistant layer, 11a, 11b, 11c are inner peripheral surfaces with satin finishing, 12a, 12b,
12c indicates a side surface with satin finishing, and θ indicates the fan angle.

Claims (1)

[Claims] 1. A seabed equipped with a cylindrical pressure-resistant layer in which three pieces each having a fan-shaped cross section are vertically arranged in order to protect an optical fiber unit in which at least one optical fiber is housed. In the optical cable, the cylindrical pressure-resistant layer sets the fan angle of the fan-shaped three-part pieces in the range of 120.1 degrees to 121 degrees, and also connects the joint surfaces of the three-part pieces and the optical fiber unit. 1. A submarine optical cable, characterized in that opposing inner circumferential surfaces are given a matte finishing, and the bonding surfaces and inner circumferential surfaces are filled with a compound to be vertically formed.