JPS6134512A - Waterproof cable - Google Patents

Abstract

PURPOSE:To obtain excellent waterproof characteristic without deteriorating the working circumstance by filling an absorbtive polymer and other waterproof admixture to the gap between the concentrically stranded cable core composed of multiple core wires and to the inner surface formed by these core wires. CONSTITUTION:The titled cable consits of a cable core 2 composed of multiple core wires 1 stranded concentrically and an absorbtive polymer 4 filled in the inner gap composed of these cores, and waterproof admixture 3 or absorbtive polymer fill to the gap other than those formed inside. By employing such structure, water which has permeated to core 2 from ouside of the cable is absorbed and gelled by absorbtive polymer 4, and further penetration is prevented. These absorbtive polymer and waterproof admixture are easy to fill, and since they are powder, it is easy to clean out even if they are spilt on the floor. By employing such a structure, a cable highly efficient in waterproof characteristic is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a waterproof cable in which a cable core formed by concentrically twisting a plurality of core wires is filled with a waterproof mixture.

[Prior art]

Conventionally, waterproof cables, such as the one shown in Figure 2, have been developed as cables designed to prevent moisture from penetrating deeper into the cable even if moisture enters from outside the cable. . This means that multiple cores 1
A waterproof mixture 3 is filled in the gaps between the core wires of a cable core 2 which is concentrically twisted together, and then a pressure-wrapping tape and an external sheath (not shown) are applied.

By the way, the following two methods are generally used to manufacture this type of waterproof cable. The first method is
While applying the waterproof mixture 3 to the core wire 1 individually in advance,
This is a method of arranging each of the core wires 1 using a batten or the like and twisting them concentrically. The feature of this method is that the waterproof mixture 3 can be sufficiently filled into the gaps inside each of the core wires 1. but,
On the other hand, since the waterproof mixture 3 has a sherry-like shape and easily drips, the sherry-like waterproof mixture 3 applied to each core wire 1 does not last until the core wires 1 are assembled. It drips, stains equipment and floors, and is difficult to wipe off, so it has the disadvantage of significantly deteriorating the so-called work environment. On the other hand, the second method is called the pipe filling method. In this method, a waterproof mixture 3 is press-fitted from the outside of the cable core 2 into a cable core 2 made by concentrically twisting a plurality of L 1 fibers at a pressure of about 10 kg/cJ. A feature of this method is that it is suitable for mass production because the waterproof mixture 3 can be filled in one place at any time. However, since the cable core 2, which has already been concentrically twisted, is filled with the waterproof mixture from the outside, the waterproof mixture 3 may not fully enter the gaps inside each core wire 1. In particular, when the outer diameter of each core wire 1 is the same, or when a plurality of core wires 1 that are thinner than the core wire 1 located at the center are concentrically twisted around a thick core wire 1 located at the center. For example, if the array is dense, such as one in the center and six around it as shown in FIG. 2, it becomes even more difficult to penetrate inside. If there is a part inside the cable that is not filled with the waterproof mixture 3, the moisture that has entered will eventually run through this unfilled part, causing a so-called water running phenomenon and penetrating deep into the cable.

In this way, when trying to fill the waterproof mixture 3 into the cable core 2 in which the core wires 1 are arranged in a dense concentric manner by the two conventional methods described above, the work environment will be significantly degraded. There is a problem that the waterproof mixture 3 cannot be sufficiently filled into the inside of the cable core 2.

[Purpose of the invention]

In view of the above problems, an object of the present invention is to provide a waterproof cable that does not deteriorate the working environment and has excellent waterproof properties, which is a cable made by concentrically twisting core wires.

[Structure of the invention]

In order to achieve the above object, the waterproof cable of the present invention includes a cable core formed by concentrically twisting a plurality of core wires, and a water absorbent cable formed by filling an inner gap formed by the plurality of core wires. It is characterized by comprising a polymer and a waterproof mixture or water-absorbing polymer filled in gaps other than the inner gap.

[Embodiments of the invention]

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

FIG. 1 shows an embodiment of the waterproof cable of the present invention. As shown in this figure, the cable core 2 of the present invention has cable cores 2 concentrically twisted in a so-called 1-6 arrangement of one core wire and six core wires around the core wire 1, such as an optical fiber. , before the cable core 2 is concentrically twisted, a powdery water-absorbing polymer 4 such as cross-linked sodium polyacrylate is filled into the gaps inside each core wire 1, and then the same process as before is carried out. The waterproof mixture 3 is filled or applied from the outside of the cable core 2 by a pipe filling method, etc. Of course, instead of the waterproof mixture 3, the water absorbent polymer 4 is applied to the inside of each core wire 1. It may be filled not only in the gaps but also in the entire area. Here, as an example of a method for filling the powdery water-absorbing polymer 4, for example, silicone oil or the like is applied around the core wire 1 arranged at the center, and the powdery water-absorbing polymer 4 is applied thereto. There is a way to attach it. After the cable core 2 is filled with the water-absorbing polymer 4 and the waterproof mixture 3 in this way, a suitable pressure-wrapping tape 5 is applied, and the waterproof mixture 3 is also applied on the pressure-wrapping tape 5. While doing so,
For example, an external sheath 6 is provided. It should be noted that there are various ways of forming the outer sheath 6 including the pressure-wrapping tape 5.
The appropriate one is selected each time. Here, the core wire 1
In addition to the single optical fiber, single wire of an insulated metal conductor and reinforced wire for tensile strength, and a set of multiple optical fibers and insulated metal conductors with a waterproof outer sheath such as a polyethylene sheath are used. This includes those with a circular cross section. In addition, the water-absorbing polymer refers to a material such as the cross-linked sodium polyacrylate that gels by absorbing water and has a strong water-retaining ability that prevents the absorbed water from flowing back even when external pressure is applied. This is different from what is known as a mixture of calcium carbonate and an organic polymer material, which absorbs water and becomes sticky to block water. The crosslinked sodium polyacrylate is obtained by heating and polymerizing acrylic acid and crosslinking it, and usually absorbs about 1000 times its own weight of water. Therefore, the water absorption effect is very good.

According to the waterproof cable of the present invention made in this way,
As described above, the gap inside the cable core 2, which is made by concentrically twisting a plurality of cores 15!1, is filled in advance with a water-absorbing polymer 4 such as a cross-linked powdered sodium polyacrylate. Therefore, even if moisture intrudes from the outside of the cable and reaches the inside of the cable core 2, the water-absorbing polymer 4 absorbs this intruding moisture and turns it into a gel, preventing it from penetrating deeper into the cable. prevent. Therefore, unlike the conventional case where the waterproof mixture 3 is filled by forcibly applying high pressure to the gaps inside the cable core 2 made up of the cable core 1, filling is easy. For example, when filling the cable core 2 in Figure 1 with the waterproof mixture 3, there is no need to fill the inside with the waterproof mixture 3, so the filling pressure is as low as 1 to 3 kg/c+l. good. Moreover, since the water-absorbing polymer 4 is in powder form, even if it spills on the floor, there is no stickiness and cleaning is easy.
Unlike the previous case, it does not significantly deteriorate the working environment. Since the water-absorbing polymer 4 is filled inside the cable core 2 in advance in this way, in addition to the effect that filling the waterproof mixture 3 is facilitated, the filling pressure is low, so that the core wire 1 is an optical fiber. In this case, there is also the effect that the deterioration of the transmission characteristics due to the filling pressure of the waterproof mixture 3 is reduced.

〔Effect of the invention〕

As described above, according to the waterproof cable of the present invention, it is possible to prevent a significant deterioration of the working environment and to obtain a waterproof cable with excellent waterproof properties very easily.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing an embodiment of the waterproof cable of the present invention, and FIG. 2 is a cross-sectional view of a conventional waterproof cable.

Claims (2)

[Claims] (1) A cable core formed by concentrically twisting a plurality of core wires, a water-absorbing polymer filled in the inner gap formed by the plurality of core wires, and a water-absorbing polymer filled in gaps other than the inner gap. 1. A waterproof cable comprising a waterproof mixture or a water-absorbing polymer. (2) The waterproof cable according to claim 1, wherein the water-absorbing polymer is crosslinked sodium polyacrylate.