JP3492555B2 - Cable extension rope - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cable extension rope used for laying a cable, and more particularly to a cable for reducing frictional resistance with an existing cable or pipeline. Thus, the existing cable can be prevented from being damaged, the cable can be pulled with a small pulling force, and wrinkles-like buckling does not occur on the rope surface during pulling. [0002] Among cables such as electric power cables, optical cables, and coaxial cables, most of those laid in underground pipes and the like have a sheath that is flame-retardant, and are generally made of resin such as polyethylene. Magnesium hydroxide as a flame retardant,
It is formed by adding aluminum hydroxide or the like. When laying such a cable in a conduit such as an underground conduit, the cable is pulled by a cable extension rope (hereinafter referred to as an extension rope). That is, a cable for extension is passed through a pipeline in advance, a cable to be newly laid is connected to one end of the rope for extension, and the cable to be laid is pulled in the pipeline by pulling the other end. I am trying to introduce it. Conventionally, a rope formed by twisting fibers of nylon, polyester, aramid or the like has been used as the rope for wire drawing. However, since such a conventional rope for drawing wire is formed by twisting fibers into a rope shape, the surface thereof has irregularities and is not smooth. Further, since magnesium hydroxide or the like is added to the sheath of a cable such as a power cable, an optical cable, and a coaxial cable, the flame resistance is excellent, but the abrasion resistance is not sufficient. Therefore, when laying a cable in a pipeline using a cable for extension, friction occurs between the existing cable and the cable for extension in the pipeline, and in some cases, the sheath of the existing cable may be damaged. There was also a risk of abrasion and damage to the cable core. In addition, there is also a problem that the traction force is increased due to the large frictional resistance between the extension rope and the pipeline, and the traction cost is high. In order to solve such a problem, as a result of various studies, a resin coating is provided on the circumference of a rope formed by twisting fibers as proposed in Japanese Patent Application No. 11-145704. Solved the problem. However,
This rope is also wrung with a wheel when laying the cable,
It was found that there was a problem of wrinkles and the like depending on the characteristics of the resin coated on the rope when the rope was pulled by the towing machine. In other words, depending on the application, the rope for wire drawing has various characteristics, but when the property balance with the resin coated on the rope is poor, wrinkles are formed on the resin coating due to ironing at the time of wire drawing. It has been found that there is a problem that the buckling phenomenon occurs. The present invention has been made in view of the above circumstances, and does not cause buckling or the like due to towing by a towing machine at the time of laying a cable. Even when the wire rope and the existing cable intersect and generate frictional force,
An object of the present invention is to provide an extension wire rope having excellent slipperiness without causing a problem such as damaging an existing cable. An object of the present invention is to provide a rope for cable extension in which a resin coating is provided on the circumference of a rope formed by twisting fibers. The problem can be solved by a wire drawing rope characterized in that a resin having an elastic limit elongation (%) equal to or more than an allowable tension elongation (%) is used. Hereinafter, the present invention will be described in detail.
FIG. 1 shows an example of a cross-sectional view of a wire rope 10 according to the present invention. This rope for extension 10 is arranged around a rope 13,
A resin coating 14 is provided around it. In the rope 10 for wire drawing of the present invention, whether the elastic limit elongation (%) of the resin coating 14 is the same as the allowable tension elongation (%) of the rope 13,
Alternatively, it is characterized in that it is larger than the allowable tension elongation (%) of the rope 13. Even if the rope 13 is stretched to the allowable tension elongation (%) due to the tension applied to the rope 10 when pulling the cable, the surrounding resin coating 14 follows the rope 10 in the same manner. It is extended. Therefore, even when the rope 13 is elongated to the allowable tension elongation (%), the resin coating 14 is not elongated beyond the elastic limit elongation (%). The buckling phenomenon that causes wrinkles and the like does not occur. Here, the elastic limit elongation (%) of the resin coating 14 is the maximum elongation (%) that hardly causes residual strain. The allowable tension elongation of the rope 13 (%)
Is the maximum tension that is assumed to be applied to the rope 13 at the time of wire drawing, and is set in consideration of a safety factor and the like. The allowable tension of the rope is determined by the application of the wire drawing. [0009] The rope 13 usually has a configuration in which the yarn 12 having a denier of about tens of thousands to one million is twisted 3 to 7 or 3 to 12 times. Desirably, the fibers 11 are flexible and have excellent strength. Usually, synthetic fibers such as nylon, Tetron (trade name), Vinylon (trade name), Dyneema (trade name), and polyester are used. Tetron and Dyneema are preferably used because of their excellent tensile strength and low tensile elongation. In the rope for rope 10 of the present invention, the elastic limit elongation (%) of the resin coating 14 is the same as the allowable tension elongation (%) of the rope 13 or the allowable tension elongation of the rope 13. (%)
The material and shape of 3 are such that the allowable tension elongation (%) of the rope 13 is the same as the elastic limit elongation (%) of the resin coating 14, or
It is appropriately selected so as to be smaller than the elastic limit elongation (%) of the resin coating 14. Allowable tension elongation of rope 13 (%)
Varies depending on the material and shape of the rope 13. For example, not only the material of the fiber 11 but also the fiber 11 of the same material differs depending on the size of the pitch which is the twist interval of the rope 13. . That is, the allowable tension elongation (%) of the rope 13 having a large pitch is small,
Conversely, with the rope 13 having a small pitch, the allowable tension elongation (%) increases. Therefore, the material of the rope 13 and the shape such as the size of the pitch are selected so that the allowable tension elongation (%) of the rope 13 is equal to or less than the elastic limit elongation (%) of the resin coating 14. When the cable such as a power cable, an optical cable, a coaxial cable, or the like is pulled into a pipeline using the rope for extension 10, the resin coating 14 reduces friction between the rope for extension 10 and an existing cable in the pipe. It is intended to prevent abrasion of the sheath of the cable by suppressing the friction and reduce the friction between the extension rope 10 and the pipeline so that the cable can be pulled with a small pulling force. Formed. As the resin coating 14 of the wire rope 10 of the present invention, a resin having excellent strength and a smooth surface and having excellent extrusion characteristics at the time of extrusion molding is used. Further, the elastic limit elongation (%) of the resin coating 14 is
Must be the same as the allowable tension elongation (%) of the rope 13 or larger than the allowable tension elongation (%) of the rope 13.
It is preferable to use a resin having a large elongation, that is, a resin having a large elongation at a yield point. As the resin used for the resin coating 14, a resin excellent in mechanical strength and surface properties and excellent in extrusion characteristics at the time of extrusion molding is used. As such a resin, polyethylene, polyvinyl chloride, nylon, polyester, polyacetal, polypropylene and the like are usually used, and preferably polyethylene is used. The polyethylene is not particularly limited, such as low-density polyethylene, high-density polyethylene, and linear low-density polyethylene. As such polyethylene, for example, DFDJ9301 (trade name) manufactured by Nippon Unicar is used. By using such a resin for the resin coating 14, the desired effect of reducing frictional resistance can be obtained. However, in order to obtain a further improvement effect, a resin composition in which a lubricant is mixed with the resin is used. It is preferable to use a lubricating resin coating for the resin coating 14. As the lubricant, fatty acid amides such as stearic acid amide, oleic acid amide, ethylenebisamide, and erucic acid amide are usually used, and particularly preferably, stearic acid amide and erucic acid amide are used. Such a lubricant may be used alone or in combination of two or more.
Usually, 0.01 to 1 part by weight is added to the parts by weight. This is because when the amount exceeds 1 part by weight, the lubricant is deposited on the surface, causing a problem in handling, and when the amount is less than 0.01 part by weight, a sufficient sliding effect cannot be obtained. The resin forming the resin coating 14 includes:
It is also possible to use a lubricating resin that can further reduce the friction between the wire rope 10 and the existing cable and the friction between the wire rope 10 and the pipeline without adding a lubricant. Silicone dispersed polyethylene as lubricating resin,
Fluororesin-dispersed polyethylene, silicone-grafted polyethylene, fluororesin-coated polyethylene and the like are used. Since it is not necessary to add a lubricant such as stearamide to these resins, so-called bleed-out of the lubricant exuding over time on the surface of the resin coating 14 does not occur. Therefore, the surface of the resin coating 14 can be made smooth, rich in lubricity, and low in friction for a long time. The formation of the resin coating 14 on the circumference of the rope 13 is usually performed by extrusion coating with an extruder. The thickness of the obtained resin coating 14 varies depending on the type and weight of the cable to be pulled, but is usually 0.5 to 5 m.
m, preferably 1-3 mm. This is because if the length exceeds 5 mm, the flexibility of the rope decreases, and the operability at the time of pulling the cable deteriorates. If the length is less than 0.5 mm, sufficient sheath strength cannot be obtained. According to the rope for wire drawing of the present invention, since the resin coating is provided on the periphery of the rope formed by twisting the fibers, the frictional resistance with the cable or the pipeline is small. When laying an additional cable, the existing cable can be laid without abrasion damage. Also, by adding an aliphatic amide such as stearic acid amide as a lubricant to the coating resin to improve the lubricity of the surface, the frictional resistance between the rope for extension and the existing cable, and the rope for extension, The frictional resistance with the pipeline can be further reduced. Furthermore, in the present invention, since the elastic limit elongation (%) of the coating resin is the same as the allowable tension elongation (%) of the rope, or a resin larger than the allowable tension elongation (%) of the rope is used,
To prevent buckling phenomena such as peeling of the resin coating and sagging of the resin coating due to residual strain after pulling even if the rope is stretched to near the allowable tension elongation during cable pulling. Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing an example of a rope for extension wire of the present invention. [Explanation of Signs] 10: Rope for extending wire, 11: Fiber, 13: Rope, 14
... Resin coating

Continuing from the front page (72) Inventor Suehiro Miyamoto 1440, Mukurosaki, Sakura-shi, Chiba Prefecture Inside Fujikura Sakura Office (72) Inventor Takashi Matsuzawa 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (56) References JP-A-58-207806 (JP, A) JP-A-4-343778 (JP, A) JP-A-3-82883 (JP, A) JP-A-7-298440 (JP, A) −135510 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) D07B 1/16

Claims (1)

(1) A rope for cable extension in which a resin coating is provided around a rope formed by twisting fibers, wherein the resin coating has an allowable tension of the rope. A rope for cable extension, wherein a resin having an elastic limit elongation (%) equal to or more than an elongation (%) is used.