JPS6119008A - Cable sheath - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a cable jacket, and more particularly, to a cable jacket that reduces the tension applied to the outer surface of the cable jacket when the cable is drawn into a pipe or the like. It is related to.

[Background of the invention]

FIG. 1 shows a cross-sectional view of a conventional cable, in which 1 indicates a cable core and 2 indicates a cable jacket body.

As is clear from Fig. 1, the cable has a cable jacket 2 which is an insulating material on the outer periphery of a cable core 1 which serves as a conductive path.
Furthermore, as is clear from this figure, the conventional cable jacket is made of polyethylene (PE),
It had a circular shape with a smooth outer surface and was extruded from a plastic material such as polyvinyl chloride (PVC).

The tension generated when such cables are installed in piping is proportional to the coefficient of friction between the cable sheath and the piping, and if the piping diameter is not sufficiently large compared to the cable diameter, the friction coefficient increases and the installation tension increases. The drawback was that it became bulky, making it difficult to install over long distances.

In order to solve these drawbacks, a method is known in which a lubricant such as oil is applied to the surface of the cable jacket. However, this method has the drawbacks of reduced workability and the fact that the lubricant is not necessarily distributed over the entire length of the long-distance pull-in, and it cannot be said that it is sufficiently effective. is the current situation.

[Summary of the invention]

The present invention has been made in view of the current situation, and it is an object of the present invention to provide a cable jacket that is easy to work with and has a small coefficient of friction when installed in pipes.

Therefore, the cable jacket according to the present invention is characterized in that continuous grooves are formed in the longitudinal direction at predetermined intervals in the circumferential direction on the outer surface of the cable jacket body.

〔Example〕

An embodiment of the present invention will be described in detail below based on the drawings.

FIG. 2 is a sectional view of an embodiment of the cable jacket according to the present invention, in which 21 is the cable jacket body, 22 is a groove continuously formed in the longitudinal direction of the cable jacket body, and 23 is a groove formed continuously in the longitudinal direction of the cable jacket body. As a result of forming the groove 22, a convex portion is shown that is continuously formed in the longitudinal direction of the cable jacket body 21.

As is clear from FIG. 1, the cable jacket according to the present invention consists of a cable jacket body 21 that covers a cable core (not shown) and a groove 22 formed on the outer surface of the cable jacket body 21. . The grooves 21 are formed continuously in the longitudinal direction of the cable jacket body 21, and are formed at predetermined intervals over the entire circumference in the circumferential direction.

Generally, the thickness of the cable jacket of a cable is about 5 to 20% of the total outer diameter of the cable, and is less than 50%. In the cable sheath according to the present invention described above, if the depth of the groove 22 is made too deep, it becomes necessary to thicken the cable sheath body 21 in order to ensure mechanical properties, and as a result, the outer diameter of the cable decreases. Therefore, in a cable jacket having a thickness of 5 mm or less as described above, the depth of s22 is preferably 1 fl or less.

In this way, the grooves 2 are continuous in the longitudinal direction on the outer surface of the cable jacket body and are formed at predetermined intervals all around the circumference.
2, the convex portion 23 is the only contact portion between the cable jacket and the pipe when a cable is installed inside the pipe. Therefore, compared to the conventional one,
Since the contact area is smaller, the coefficient of friction is lowered and tension can be reduced.

FIG. 3 is a sectional view of a second embodiment of the present invention, in which the same reference numerals as in FIG. 2 indicate the same members, and 24
indicates a fluid substance.

In the embodiment shown in FIG. 3, as in the first embodiment, the cable sheathing body 21 is continuous in the longitudinal direction and at predetermined intervals over the entire circumference in the circumferential direction. A groove 22 is bored.

In this embodiment, the groove 22 is additionally filled with a fluid substance 24. Such a configuration requires that the opening width of the groove 22 is too large or that the filling material 2
The dropping point of No. 4 must not be too low. That is, the groove 22
This is because if the width of the opening is too large or the dropping point of the fluid substance 24 is too low, there is a risk that the fluid substance 24 will drip. Therefore, under normal environment (-30℃~60℃
) It is necessary to select a material that does not drip as the fluid material 24 for filling.

As such a fluid material 24, for example, a polybutene-based mixture can be mentioned, and the opening width varies depending on the type of fluid material 24 to be filled, but is generally 1.
It is preferable that it be less than or equal to fi.

According to the cable jacket according to the second embodiment of the present invention, when a cable is laid in a pipe or the like, lateral pressure is applied to the cable jacket in places where the tension is large, such as at bends, and the convex portion 23 is compressed and a fluid substance 24 such as oil filled in the groove 24 flows out to the outer surface of the cable jacket and acts as a lubricant for the cable and piping,
It has the effect of lowering the laying tension.

In addition, in Examples 1 and 2, if a material with a small coefficient of friction, such as a fluororesin, is used for the above-mentioned convex portion 23, there is an advantage that the laying tension can be further reduced.

〔Effect of the invention〕

As explained above, according to the cable jacket according to the present invention, grooves are formed continuously in the longitudinal direction and all the way in the circumferential direction on the surface of the cable jacket body, so that it can be used for piping, etc. This has the advantage of reducing the contact area between cables and piping, thereby reducing the coefficient of friction between cables and piping.

Furthermore, if this groove is filled with a fluid substance, the lubricant will flow out as the tension increases, so during normal handling, the cable jacket will dry and workability will be good. Moreover, since the lubricant leaks only where it is needed, it has the advantage that its lubricating action can be maintained even in long pipes.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional cable, FIG. 2 is a cross-sectional view of a cable jacket according to an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a cable jacket according to another embodiment of the present invention. 21...Cable jacket body, 22...Groove, 23...
- Convex portion, 24...Fluid substance.

Claims (2)

[Claims] (1) A cable jacket characterized in that continuous grooves are provided in the longitudinal direction at predetermined intervals in the circumferential direction on the outer surface of the cable jacket body. (2) The cable jacket according to claim 1, wherein the groove is filled with a fluid substance.