JPH07230722A - Tension resisting cable - Google Patents

Abstract

PURPOSE:To prevent generation of biased condition in a cable due to loosening and also meandering of the cable by furnishing two protective covering layers on the outside of an insulating substance for a conductor, and providing a tension-resisting body consisting of a bundle of high tensile force fibers between the two layers in such an arrangement stretching longitudinally. CONSTITUTION:Outside of the insulating substance for a conductor 1, an internal protective covering layer 3 and an external protective covering layer 5 are installed in such a way as surrounding a tensile strength body 4 and adhered to the internal covering layer 3. The tension-resisting body 4 consists of at least one bundle of high tensile force fibers such as alamid fiber impregnated with poiyurethane resin, etc., wherein the bundle is twined or braided and laid in the longitudinal direction. The body 4 takes a form as embedded in the internal and external layers 3, 5 and there is no risk that eccentric conduction due to untying is generated when the resultant cable is bent and elongated. Even thought the tension is released after the cable is subjected to an elongation process, reversible shrinkage takes place from the elongated condition to the original, so that no swell will be generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tension resistant cable used in, for example, an uninterruptible bypass construction method for overhead distribution lines.

[0002]

2. Description of the Related Art In the uninterruptible bypass construction method for overhead power distribution lines, Japanese Utility Model Laid-Open No. 3-12313 is known as a tensile strength cable that can be directly installed without hanging on a messenger wire. The present inventors also proposed Japanese Utility Model Application No. 5-2617 as a cable of the same type.

The former is, as shown in a transverse sectional view in FIG. 3, an inner protective coating layer 3 of polyethylene, vinyl chloride or the like and a similar outer protective coating on the outside of an insulator 2 such as polyethylene or cross-linked polyethylene which wraps the conductor 1. Layer 5 has been applied.

Then, the inner and outer two protective coating layers 3, 5
A plurality of high-strength fibers 41, such as aramid fibers impregnated with a resin such as polyester, are vertically provided between them.

In the latter, the high-tensile fibers 41 are not vertically attached, but an appropriate number of high-tensile fibers are bundled, and the outside is wrapped vertically with a thin film layer of nylon, polyurethane, vinyl chloride or the like and vertically attached. It is a thing.

[0006]

In the conventional tensile strength cable as shown in FIG. 3, since many aramid fiber monofilaments are vertically aligned in a state that they are aligned, the cable may be bent, When the cable is stretched, the alignment state may be separated in the two inner and outer protective coating layers, resulting in a biased state, which may cause the cable to meander after bending and stretching.

The uneven deviation state that causes the meandering is caused by the resin impregnated in the aramid fiber being adhered to the inner surface of the outer protective coating layer together with a part of the aramid fiber.
The non-uniform adhesion part becomes an obstacle and is promoted.

When the tension-proof cable is used by being mounted between electric poles, both ends of the cable are usually gripped by an anchoring metal fitting having a wedge-shaped grip.

That is, both ends of the cable are sandwiched from the outside by wedges of a pulling metal fitting, and the mounting tension of the cable is changed to the aramid fiber by the frictional force between the outer layer of the protective coating layer, the aramid fiber and the protective coating layer. It is a method of sharing.

By the way, aramid fibers have an extremely high tensile strength, but have a small coefficient of friction, and as described above, when gripping by friction between the outer layer-aramid fibers-inner layer, slippage is likely to occur, thereby causing a gap between the layers. The unevenness of the elongation between the layers occurs. That is, the outer layer-aramid fiber = extension is large, and the inside after the inner layer is small = extension.

As a result, when the tension of the cable is released, each part tries to shrink to its original state in accordance with the amount of elongation, in order to eliminate the unevenness of the elongation between the layers. When the inner and outer protective layers are separated and are in a one-sided state, the aramid fiber, which has a large elongation, just becomes a string like a bowstring and shrinks, causing undulation (meander) in the cable. Once waviness occurs, bending fatigue concentrates on that part and leads to conductor breakage, or when the cable is rewound on the drum and stored again after use, the meandering part becomes an obstacle and the cable cannot be wound around the drum. There was a problem.

Further, when treating the cable end, it is necessary to hold the aramid fiber itself to the end portion. However, as described above, the aramid fiber has a small friction coefficient and is very flexible, so that it is mechanically gripped. Even if an attempt is made to hold it, slipping occurs at the gripping portion, making it difficult to hold it firmly.
For this reason, fixing is performed by using a curable resin such as epoxy resin, but this method is much more labor-intensive than the end treatment of a general cable that does not vertically attach aramid fiber. However, there is a problem in that the size of the end portion becomes large because it is necessary to secure the fixing dimension necessary for firmly holding the aramid fiber.

[0013] The Japanese Patent Application No. 5-2617, which was previously proposed by the present inventors.
No. 6 is intended to eliminate the above-mentioned defects caused by vertically aramide fibers, and a plurality of the fibers are bundled in advance, and the outer periphery of the bundle is vertically wrapped with a resin thin film layer. Is. By forming this bundle, the conventional defects are sufficiently eliminated, but it cannot be said that the cable structure is effective as the frictional force between the layers and the tensile strength of the fiber.

[0014]

DISCLOSURE OF THE INVENTION The present invention provides a structure of a tension-proof cable which eliminates the above-mentioned defects of the conventional tension-proof cable and further exhibits a new effect. Is as follows.

Two inner and outer protective coating layers are provided on the outside of the insulator, and at least one or more tensile strength members obtained by twisting a bundle of high-tensile fibers are vertically provided between the protective coating layers. This is the first feature.

Another feature of the present invention is that the bundle of the high-strength fibers is braided without being twisted to form a tensile strength member and is vertically attached.

A third feature of the present invention is that unevenness is formed on the surface of the strength member by the twist groove formed by the twisting or the stitches formed by the braiding, and the number of projections is 1 cm ^{2 on the} outer surface of the strength member.
It is to be 10 or more per.

A fourth feature of the present invention is that each fiber bundle to be twisted or braided is impregnated with resin in advance, or resin is applied during twisting or braiding to impregnate the tensile strength member with resin. Is. The impregnated resin is
In order to adhere to the protective coating layer, it is preferable to impregnate a resin having a Vicat softening point of 150 ° C. or higher such as an ester type polyurethane resin.

The fifth feature of the present invention is that the outer protective coating layer is coated so as to surround the strength member, and is bonded to the inner coating layer with a peeling force of 0.1 kg / 12.4 mm or more. The contents will be described below with reference to examples.

[0020]

EXAMPLE FIG. 1 (a) is a cross-sectional view of a tensile strength cable in Examples 1 and 2, and FIG. 1 (b) is a side view of a tensile member forming a part of the tensile strength cable in Example 1. FIG. 1C is a side view of a strength member forming a part of the tension resistant cable according to the second embodiment.

In FIG. 1A, 1 is a conductor, 2 is an insulator such as polyethylene or cross-linked polyethylene, and the insulator 2
The outer protective coating layer 3 and the outer protective coating layer 5 such as polyethylene or vinyl chloride surround the strength member 4 and are adhered to the inner protective coating layer 3 with a peeling force of 0.1 kg / 12.4 mm or more. Between the inner and outer two protective coating layers 3 and 5, a plurality of tensile strength members 4, for example, ten or more, are evenly provided over substantially the entire circumference. Strength member 4
Is just embedded in the inner / outer protective coating layer, and does not cause a loose biased state due to bending and stretching of the cable, and reversibly shrinks from the stretched state to the original state even after releasing the tension after pulling the cable. , Swell does not occur.

In the first embodiment, the strength member 4 is
Ester type Vicat softening point 1500d x 2 impregnated with polyurethane resin of 100 ° C or less 4 pieces of aramid fiber with a uniform arrangement, twisted at a pitch of about 10mm and cured Fig. 1
The structure shown in (b) was used. In the figure, A and B represent the length and width as a unit when viewed from directly above the side surface of the strength member, and the number of protrusions C on the outer surface caused by twisting is 10 in A × B = 1 cm ^2. It is formed to have more than one piece.

In the second embodiment, the strength member 4 is
The type of impregnated resin and fiber used is the same, but 1500d x 1
Eight book gathering pieces are braided into a structure as shown in FIG. The number of convex portions C caused by the stitches of the braid was set to 10 or more per unit by the same counting method as in Example 1.

As described above, the tensile strength member 4 is formed by twisting or braiding high-tensile fiber bundles, or is further impregnated with resin and hardened. It has a high tensile strength and also adheres well to the outer protective coating layer. Further, the frictional resistance between the inner and outer two protective coating layers is remarkably increased due to the unevenness of the outer surface thereof, and the effect of vertically adding the tensile strength body becomes remarkable.

Further, due to the increase in the frictional resistance, the tensile strength cable can be erected on the same frame, but as shown in FIG. 2, the tensile strength member 4 at the end of the cable is attached to the outer circumference of the internal pulling metal fitting 6a. The tensile strength member 4 can be mechanically gripped, for example, by bending along it and pressing it with the pressing metal fitting 6b to grip it.

[0026]

As described in the above paragraphs, in the tensile strength cable of the present invention, the tensile strength member vertically attached so as to be embedded between the two inner and outer protective coating layers is a bundle of high tensile fibers. Since they are twisted or braided, or are further impregnated with a resin and cured, high tensile strength is uniformly maintained, unevenness due to loosening does not occur, and meandering of the cable is prevented. Also, for the terminal treatment of the cable,
It can be easily mechanically gripped and can be retained with a small size.

[Brief description of drawings]

1 (a) is a cross-sectional view of a tensile strength cable in Examples 1 and 2, FIG. 1 (b) is a side view of a strength member in Example 1, and FIG. 1 (c) is in Example 2. It is a side view of a strength member.

FIG. 2 is a conceptual diagram illustrating an example of a terminal treatment of the tensile strength cable of the present invention.

FIG. 3 is a cross-sectional view showing a structural example of a conventional tensile strength cable.

[Explanation of symbols]

1 conductor 2 insulator 3 internal protective coating layer 4 tensile strength body 41 high-strength fiber 5 external protective coating layer 6a internal retention metal fitting 6b holding metal fitting A unit length seen from above the side surface of the tensile strength material B seen from directly above the lateral surface of the tensile strength material Unit width C Convex portion on the outer surface of the tensile strength body caused by twisting or braiding

Claims (5)

[Claims] 1. A protective coating layer of two layers inside and outside is provided on the outside of an insulator, and at least one or more tensile strength member formed by twisting a bundle of high-strength fibers is vertically provided between the protective coating layers. A tensile strength cable characterized in that 2. A protective coating layer of two layers inside and outside is provided on the outside of an insulator, and at least one tensile strength body formed by braiding a bundle of high-strength fibers is vertically provided between the protective coating layers. A tensile strength cable characterized in that 3. The resistance according to claim 1 or 2, wherein the outer surface of the strength member is provided with unevenness due to twisted grooves or stitches, and the number of projections is 10 or more per cm ^{2 of the} outer surface. Tension cable. 4. The strength member has a Vicat softening point of 150 ° C.
The tensile strength cable according to claim 1, wherein the cable is impregnated with the following resin. 5. The outer protective coating layer is coated so as to surround the strength member, and is adhered to the inner protective layer with a peeling force of 0.1 kg / 12.4 mm or more.
The tensile strength cable described in 2, 3, or 4.