JPS6143930B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention relates to a structure for attaching a stub cable to a dam fitting, and particularly relates to a stub cable attachment structure to a dam fitting that combines the compressive force of a rubber bushing and the self-sealing effect of leakage gas pressure. This relates to the mounting structure.

(2) Technical background Stub cables that require hermetic sealing are coated with lead to maintain reliability of transmission characteristics.
Furthermore, gas is sealed within the lead coating. Therefore, in order to connect a repeater installed in a manhole etc., the stub cable is first connected to the dam fitting, and then the dam fitting is connected to the repeater. There is a need for an easy-to-air-tight mounting structure for connecting metal fittings and squab cables.

(3) Prior art and problems Figure 1 is a sectional side view of the main part to explain the conventional structure for attaching a stub cable to a dam fitting. 2 is a stub cable;
The coaxial cord 23, the intervening wire 24, etc. are covered with a lead coating 22 and an outer coating 21, 3 is a fixing material made of high viscosity epoxy, etc., 4 is a sealing material made of low viscosity epoxy, etc., and 5 is lead. It is engineered solder.

In this configuration, first, the outer sheathing 21 and the lead sheathing 22 corresponding to predetermined dimensions of the end portion of the stub cable 2 to be attached to the dam fitting 1 are cut off, and the outer sheathing 21 and the lead sheathing 22 are separated into a plurality of coaxial cords 23 and intervening wires 24, and each The stub cable 2 is attached to the dam fitting 1 with adhesive treatment applied to improve the adhesion of the adhesive to the dam fitting 1.
The stub cable 2 is inserted into the cable attachment portion 11 of the stub cable 2, and the lead sheathing portion 22 of the stub cable 2 is carefully hermetically welded to the cable attachment portion 11 using, for example, solder 5 or the like. Then, the adhesive material 3 with high viscosity is poured into the sealing part 12 through which the coaxial cord 23 and the intervening wire 24, which have been adhesively treated, are inserted, and the adhesive material 3 and the adhesive material 3 are bonded to the inner surface of the sealing part 12 and the adhesive material 3 and the adhesive material 3. The coaxial cord 23 and the intervening wire 24 are fixed together. Furthermore, a low-viscosity sealing material 4 is introduced into the inner cylinder of the dam fitting 1 into which the coaxial cord 23 and the intervening wire 24 are inserted, so that the internal sealing material 4 of the dam fitting 1, the coaxial cord 23, and the intervening wire 24 are integrated. is airtightly fixed. When inserting the thus completed stub cable 2 with a dam fitting of a predetermined length into a manhole or the like for connecting to a repeater, the stub cable 2 is connected to the stub cable 2 as shown by the dotted line near the soldering of the dam fitting 1 and the stub cable 2. When the coaxial cord 23 is bent (with a radius of curvature of approximately 500 mmR), forces in the directions of arrows A and B are applied to each of the coaxial cords 23, and the adhesive material 3 contracts from the inner surface of the sealing portion 12 of the dam fitting 1 due to contraction during hardening. Due to peeling, the adhesive material 3 of the sealing part 12
The coaxial cord 23, etc., which is airtightly fixed by the adhesive material 4, is moved, and excessive force is applied to the coaxial cord 23, etc., which may peel off, resulting in poor airtightness.

(4) Purpose of the Invention In view of the above-mentioned drawbacks, the present invention provides a space between the dam fitting and the adhesive material, and provides a novel dam fitting that utilizes the compressive force of a rubber bushing and the self-sealing effect of leaking gas pressure. The purpose is to provide a stub cable attachment structure.

(5) Structure of the Invention In order to achieve the above-mentioned object, the present invention provides a state in which a dam fitting is welded to a lead-coated portion of a stub cable, and a cord and an intervening wire in the stub cable are inserted into the dam fitting. In a structure for attaching a stub cable to a dam fitting by injecting and fixing an injection-curing resin into the dam fitting, a predetermined space is provided between the inner periphery of the dam fitting and the injection-curing resin, and the space is This is achieved by fitting a rubber bushing into the small diameter end of the hole, inserting a stepped ring with an O-ring on the large diameter side, and screwing it in with a presser fitting to seal the space.

(6) Embodiments of the Invention Examples of the structure for attaching a stub cable to a dam fitting according to the present invention will be described in detail below with reference to the drawings.

Fig. 2 is a side sectional view of the main part for explaining one embodiment of the present invention, and Fig. 3 is an enlarged view of the sealing part, and the same parts as in the previous figure are given the same reference numerals. . 6 is a sealing material made of low viscosity epoxy, etc.;
7 is a space between the dam fitting and the sealing material, 8 is made of metal such as brass, and has a cable attachment part 81, a sealing part 82, a collar 83 for attaching to the repeater, and a female thread 84 at the open end. The dam fitting 9 is made of metal, such as brass, and has a small diameter part 91 and a large diameter part 9.
2 and a stepped ring having a groove 93 into which the O-ring 14 is fitted on the outer periphery of the large diameter portion; The O-ring 15 is made of an elastic material such as rubber, and is an annular holding fitting made of metal such as brass and having a male screw 151 formed on its outer periphery.

In FIG. 2, the process of cutting off the covering of the stub cable 2, airtightly welding it to the dam fitting 8, and flowing the fixing material 3 into the sealing part 62 through which the coaxial cord 23 and the intervening wire 24 are inserted is conventional. Since it is the same as that, the explanation will be omitted. After the coaxial cord 23 and the intervening wire 24 are fixed at the sealing part in this way, a space 7 is formed in the inner cylinder of the dam fitting 8 through which the coaxial cord 23 and the intervening wire 24 are inserted.
After inserting a cylindrical tool (not shown) in advance to form a cylindrical tool, when the sealing material 6 with a low viscosity is poured into the tool, the coaxial cord 23 and the intervening wire 24 are integrally bonded to the sealing material 4, so the tool can be removed after curing. Pull it out and remove it. Then, a part of the rubber bushing 10 is fitted in advance into the small diameter part 91 of the stepped ring 9, and the O-ring 14 is fitted into the groove 93 formed in the large diameter part 92, and the rubber bushing 10 contacts the sealing material 6. Then, the stepped ring 9 is screwed and fixed with the presser metal fitting 15. In this case, it goes without saying that the male thread 151 of the presser metal fitting 15 is screwed into the female thread 84 of the dam metal fitting 8. When the completed stub cable 2 with a dam fitting of a predetermined length is inserted into a manhole or the like to connect it to a repeater, the stub cable 2 is connected to the dam fitting 8 in the vicinity of the solder of the stub cable 2 as shown in the dotted line above. When the coaxial cord 23 is bent and force is applied in the directions of arrows A and B, the adhesive material 3 is peeled off from the inner surface of the sealing part 82 of the dam fitting 8 due to shrinkage during hardening.
The adhesive material 3 of the sealing part 82 moves, and the gas inside the cable 2 leaks into the space 7 provided on the outer periphery of the adhesive material 6. However, since the space 7 is sealed by the rubber bushing 10, the pressure of the leaked gas is suppressed. The airtightness within the dam fitting 8 can be maintained due to the self-sealing effect.

(7) Effects of the Invention As is clear from the above explanation, according to the stub cable attachment structure to the dam fitting according to the present invention, when connecting to a repeater inside a manhole, a slightly excessive force is applied to the cable. Since there is no risk of poor airtightness even if the device is used, it greatly contributes to improving transmission characteristics and can be expected to have a longer service life.

[Brief explanation of the drawing]

Fig. 1 is a side sectional view of main parts for explaining a conventional structure for attaching a stub cable to a dam fitting, and Fig. 2 is a side sectional view for explaining an embodiment of the structure for attaching a stub cable to a dam fitting according to the present invention. A side sectional view of the main part, and FIG. 3 is an enlarged view of the sealed part. In the figure, 1 and 8 are dam fittings, 2 is a stub cable, 3 is a fixing material, 4 and 6 are a sealing material,
5 is solder, 7 is a space, 9 is a stepped ring, 10 is a rubber bushing, 14 is an O-ring, 15 is a fixing bracket, 11 and 81 are cable attachment parts, 12 and 82 are sealing parts, 13 and 83 are for mounting 21 is an outer coating, 22 is a lead coating, 23 is a coaxial cord, 24 is an intervening wire, 84 is a female thread, 91 is a small diameter portion, 92 is a large diameter portion, 93 is a groove, and 151 is a male thread.

Claims (1)

[Claims] 1. A dam fitting made by welding a dam fitting to the lead-coated portion of a stub cable, inserting the cord and intervening wire in the stub cable into the dam fitting, and injecting and fixing an injection hardening resin into the dam fitting. In the stub cable attachment structure, a predetermined space is provided between the inner periphery of the dam fitting and the injection hardening resin, a rubber bushing is fitted into the small diameter end of the space, and an O-ring is provided on the large diameter side. A structure for attaching a stub cable to a dam fitting, characterized in that a stepped ring is inserted and screwed with a holding fitting to seal the space.