JPS59104605A - Airtight terminal plate of optical fiber - Google Patents

Abstract

PURPOSE:To maintain airtightness of sealing by removing a part of the outermost layer of an optical fiber, disclosing the intermediate layer of a material of knitted fiber structure, impregnating this part with an epoxy resin adhesive, hardening it, inserting it into the mold of a terminal plate, and casting the epoxy resin. CONSTITUTION:A part of the outermost layer 3 of a single type optical fiber 2 is removed, an intermediate layer 4B of a knitted material or cloth structure covering a core fiber 21, a clad 22, and an inner coating layer 5 is impregnated with an epoxy resin adhesive, and hardened. Such an optical fiber or plural ones are inserted into the mold 1 of the terminal plate, and the epoxy resin is cast. Since the layer 4B is made of a knitted or woven material, slipping of fibers or uneven coating of the adhesive is prevented, and the airtightness of sealing is maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a monopolar or multipolar epoxy resin hermetic terminal plate having one or more optical fibers passed therethrough.

In recent years, the range of applications of optical fibers has become extremely wide, and in addition to applications in general communications, they have also come to be applied to electrical equipment. Such electrical equipment includes, for example, switches,
There are transformers, electrical equipment related to DC power transmission, etc. In such devices, optical fibers are used to convert optical signals or electrical energy into light, introduce it, and extract it. In addition, in such equipment, sulfur hexafluoride (5F6
) using gas, this SF.

Gas is generally sealed at a constant pressure of at least atmospheric pressure and at most 6 kg/c+f. If the enclosed SF or gas leaks from the terminal board used in such electrical equipment, it is unacceptable because it will make the equipment itself unusable.

There are various optical fibers depending on their configuration, but the optical fiber used in the present invention has a diameter of 0.1 to 0.5, for example.
mm, usually 0.2 to 0.3 inches, coated with a protective coating (hereinafter referred to as a single type optical fiber). The filament of the above-mentioned single type optical fiber is usually provided with a clad layer of quartz, multi-component glass, plastic, etc. around the core wire, and around this filament, there is an inner coating layer such as nylon or polyester, an intermediate layer of fiber material, etc. It has a protective coating consisting of outermost layers of polyethylene, polyvinyl chloride, etc., stacked in this order. It should be noted that it is well known that these protective coatings have other configurations, and there is no need to explain them in detail here.

The present invention relates to an improvement in an optical fiber hermetic terminal board made by casting an epoxy resin casting material as a terminal board for the above-mentioned various electrical devices through which an optical fiber having a protective coating is passed through.

In such a terminal board, an airtight seal can be achieved by installing the terminal board itself into the opening of the device using a conventional packing structure, etc. However, due to the structure of the optical fiber, it cannot be said to be completely airtight, and the high-pressure SF6 gas inside the device can be sealed. However, the optical fiber has the disadvantage that it leaks through the protective coating of the optical fiber.

In order to eliminate the defects of the optical fiber penetrating terminal plate due to the structure of the optical fiber described above, the present inventors proposed that the protective coating of the single type optical fiber located in the terminal plate was made of polyvinyl vinyl. It has been found that airtight sealing properties can be maintained by removing a portion of the outermost layer to expose the fibrous intermediate layer, impregnating this portion with a low viscosity epoxy adhesive, and curing.

However, in general, in the constituent materials of optical fibers, fibrous reinforcing materials such as Kevlar fibers used in the intermediate layer are vertically attached for the purpose of withstanding external tension. However, in the present invention, in order to create an airtight seal, it is necessary to peel off the outermost layer and impregnate the exposed part of the Kevlar fiber layer with epoxy resin adhesive, which then hardens. During the application and curing process of the adhesive, the fibers move, making it impossible to evenly cover the outer surface of the inner coating layer made of plastic such as nylon, and sometimes coming off from around the inner coating layer, causing uneven coating of the adhesive and disrupting its protective role. It turned out that this was the cause of a gas leak.

For this reason, the inventors of the present invention changed the structure of the fiber reinforcing layer from the conventional vertically bonded layer to a single set, so that even after the outermost layer of the protective coating was removed, the exposed portion was treated with epoxy adhesive, the fiber layer remained intact. It has been found that it can be held uniformly over the entire surface and the above drawbacks can be prevented.

The terminal board is made by inserting one or more single optical fibers treated as described above into a mold for the intended terminal board, assembling it, and casting epoxy casting material in the usual manner. Manufacture.

The present invention will be explained below with reference to the drawings.

In Fig. 1, (1) is an epoxy resin cast terminal board, through which the necessary number of single type optical fibers (2 (three in the illustrated example)) pass through.Single type optical fiber (2)
has a protective covering consisting of an outermost covering layer (3), for example of polyvinyl chloride, and an intermediate layer of textile material (Φ), for example of Kevlar fibers, and an inner covering layer (5) of, for example, nylon.

Figure 2 shows a cross section of a single type optical fiber embedded in an epoxy cast terminal board, showing the conventional type shown in Figure 2 (A) and the horizontally placed optical fiber according to the present invention shown in Figure 2 (B). This is a comparison of the state when impregnated with epoxy M adhesive and cured, (21) is the core wire, (22)
indicates the cladding layer. This figure shows that because the fibers used as the fiber material intermediate layer (4A) in conventional optical fibers are vertically attached, the fibers become uneven after being treated with an epoxy resin adhesive, and the inner layer of the inner optical fiber core wire (4A) is unbalanced. 5) had peeling and the adhesive layer was non-uniform, and the airtight treatment effect could not be fully exhibited. On the other hand, in the present invention, by forming the intermediate fiber material J#(4B)' (FIG. 2 (O)) such as Kevlar fiber into a seed or woven structure, even after treatment with epoxy adhesive, due to the entangling effect of the fibers, It can be maintained evenly on the outer circumferential surface of the inner coating layer (5), and air treatment can be ensured without causing displacement of the expanded fibers of the intermediate layer (4) or uneven application of the adhesive, which are the conventional drawbacks. The knitted or woven fabric is not limited to a specific structure, as long as the fibers are intertwined to the extent that the fibers are not lopsided when the epoxy resin adhesive is applied.

One or more single-type optical fibers treated in this way are inserted into a mold for the intended terminal plate, and then integrally molded with epoxy resin material using a conventional method to make the single-pole or multi-pole airtight. A through terminal board can be made.

Any commercially available epoxy resin adhesive and epoxy resin casting material used in the present invention can be used.
For example, Araldite (Switzerland: Chihakaigy product),
Examples include Epon (USA: Shell Chemical Company product).

In addition, impregnation hardening and casting hardening methods themselves can be carried out using any well-known methods.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing an example of a terminal plate manufactured according to the present invention, and FIG. 2 is a cross-sectional view of an optical fiber comparing the conventional one and the one of the present invention, excluding the outermost coating layer. It is a front view. (1) is an epoxy terminal board, (2) is a single type optical fiber 1, (3) is the outermost protective coating layer, (4 is a fiber material intermediate layer,
(5) is the inner layer of the protective coating. Figure 1, Figure 2

Claims (1)

[Claims] 1. An optical fiber airtight terminal board with one or more optical fibers passed through it, in which a part of the outermost layer of the protective coating of the optical fiber located inside the terminal board penetration part is removed, and this exposed fiber is removed. The material intermediate layer is pre-impregnated with an epoxy resin adhesive and cured, the treated optical fiber is inserted into a terminal plate mold, and the epoxy resin is cast.The fiber material intermediate layer is knitted. Or an optical fiber terminal board characterized by having a woven structure.