JPS6125317Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the unfinished structure at the lead-in end of a cable, which is provided with a non-metallic fiber having a high tensile strength as an exterior sheath.

The demand for long cables to be installed in piping, conduit pipes, etc. is increasing from an economic perspective and to reduce the number of cable connections, which are weak points. It is necessary that it can withstand the tension of drawing itself.

In order to meet this demand, cable structures have already been proposed and put into practical use in which reinforcement for lead-in is provided as the cable sheath in addition to the conductor. Non-metallic wires or fibers are used in place of conventional metal wires for this purpose.

That is, reinforced plastics such as Kevlar (trade name, manufactured by DuPont) are used as non-metallic reinforcing wires.

This non-metallic fiber armored cable can compensate for the insufficient tension in the conductor and obtain sufficient strength, but since the reinforcing wire is not a metal body, conventional pulling eyes and wire grips cannot be used to sufficiently strengthen the reinforcing wire. I was unable to take advantage of my strengths as a.

In other words, in the conventional pulling eye, the metallic pulling eye and the metal exterior were attached by mechanical gripping or metal welding using a compression method or a soldering method, but in this method, since it is a non-metallic material, It is difficult to expect grip strength.

In addition, wire grips rely on friction between the wire grip and the cable, so there is a limit to the frictional force, and even if a strong material is used for the reinforcing layer, this has the disadvantage that it cannot be fully utilized.

Incidentally, in order to increase the gripping force of the wire grip, it is possible to increase the cable gripping length of the wire grip, but this is not practical.

The present invention was developed with the aim of solving the drawbacks of the prior art described above, significantly increasing the pulling tension, and providing a compact unfinished structure at the pulling end. At the end of a metal fiber armored cable, the cable conductor is fixed to the pulling eye by compression or soldering, and the outer fiber is arranged around the outer periphery of the pulling eye and fixed to the pulling eye with a curable resin. The lead-in end of the cable is characterized by an unfinished structure.

Next, one embodiment of the present invention will be further described with reference to the accompanying drawings.

Figure 1 shows an example of a cable for a skin heating device used for pipe heating. 1 is a conductor, the outer periphery of which is coated with an insulating coating 2 of silicone rubber, ethylene propylene rubber, etc. A Tetron braid 3 is provided.

In order to draw this cable into the conduit and to extend the length of the cable, it is necessary to increase the tension.

In order to increase the tension, it is possible to use piano wire as an exterior sheath, but in skin heating devices, the return current must be passed through the conduit tube into which the cable is inserted, so it is not possible to pass current through the cable sheath. No, therefore metal sheathing cannot be used.

For this reason, it is necessary to use a reinforcing wire that is non-metallic, has high tensile strength, and can withstand high temperatures.

Therefore, in this embodiment, Kevlar fiber manufactured by DuPont is used as the outer sheath 4.

Kevlar fiber has a heat resistance of over 600℃ and a strong tensile strength of over 200Kg/mm ² .

However, in the conventional pulling eye, as shown in FIG. 2, although the conductor 1 and the pulling eye 5 can be fixed together by compression or soldering, it is not possible to expect the gripping force between the non-metallic sheath 4 and the pulling eye 5 to be strong. I couldn't do it.

In addition, as shown in FIG. 3, wire grips cannot obtain a predetermined gripping force unless a long wire grip 6 is used, and cannot be put into practical use as a conduit lead-in structure that requires a compact structure.

FIG. 4 shows the unfinished structure of the drawing end of the present invention, in which the outside of the pulling eye 7 is shaped into a conical shape.
In the center, the conductor 1 is inserted and held by compression or soldering, as in the conventional case.

Further, the exterior fibers 4 are arranged and bound around the outer periphery of the pooling eye 7, and are hardened with an epoxy resin 8 to fix the pooling eye 7 and the exterior fiber 4.

By adopting such a configuration, it becomes possible to transfer the tension of the exterior fiber 4 to the pulling eye 7, increasing the tension of the pulling eye to more than twice that of the conventional one, and also hardening the edges with epoxy. Therefore, it has the advantage of being able to waterproof the edges.

As explained above, according to the present invention, it is possible to significantly increase the pull-in tension in a non-metallic fiber armored cable, and also to provide a compact structure with an unfinished pull-in end. It has great practical value.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional explanatory diagram showing an example of a non-metallic armored cable to which the structure of the present invention is applied, and Fig. 2 is an explanatory diagram showing an example of a conventional unfinished end structure in which a pooling eye is attached to the unfinished end of the cable. Figures 3 and 3 are diagrams showing an example of a conventional unfinished structure in which a wire grip is attached to the unfinished end of the cable, and Fig. 4 is an explanatory diagram showing an example of the unfinished lead-in end structure of the cable of the present invention. be. 1: Cable, 2: Insulating coating, 4: Non-metallic fiber sheath, 5: Pulling eye, 6: Wire grip, 7: Pulling eye, 8: Curing resin.

Claims (1)

[Scope of utility model registration request] At the end of a non-metallic fiber armored cable, the cable conductor is fixed to the pulling eye by compression or soldering, and the outer fiber is arranged around the outer periphery of the pulling eye and fixed to the pulling eye with a curable resin. The lead-in end of the cable is characterized by an unfinished structure.