JP3506954B2 - 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 with reduced friction with an existing cable or conduit. In addition, when laying additional cables and the like, the existing cables can be prevented from being damaged, the cables can be pulled with a small pulling force, and the rope can be easily led out. 2. Description of the Related Art Among cables such as power cables, optical cables, and coaxial cables, those laid in underground pipes or the like have flame-retardant sheaths. Is formed by adding magnesium 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 such as nylon and polyester has been used as the rope for wire drawing. [0003] However, since the conventional rope for drawing wire is formed by twisting fibers into a rope shape, the surface thereof has irregularities and is not smooth. Also,
Since sheaths of cables such as power cables, optical cables, and coaxial cables are added with magnesium hydroxide or the like, the flame retardancy is excellent, but the mechanical strength is not sufficient. For this reason, when laying a cable in a pipeline using a rope for extension, if the existing cable in the pipeline intersects with the rope for extension, a large frictional force is generated between the existing cable and the existing cable. There is a problem that the sheath is worn and damaged, the cable core is exposed, and the optical fiber is broken, and it is difficult to additionally lay an optical fiber cable or the like in an existing pipeline. In order to solve this problem, various methods have been tried, such as adopting a fiber having good slipperiness for the rope used for the extension wire. In order to meet the increasing demand for optical cables and the like, there is no other way but to lay new pipes. This has been a major obstacle in expanding the use of optical communication and the like. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to reduce the friction between a cable and a pipeline to suppress damage to the cable, to pull the cable with a small pulling force, and to connect the cable with a cable or the like. An object of the present invention is to provide a rope for wire drawing which is excellent in workability so that a rope at a tip portion can be easily led out at the time of connection. [0005] An object of the present invention is to provide a cable extension in which a resin coating is provided on the circumference of a rope formed by twisting fibers, and a tear string is provided between the rope and the resin coating. A rope for drawing wire, wherein the sum of the extra length (%) of the tear string and the elongation at break (%) of the tear string is larger than the allowable tension elongation (%) of the rope. Can be solved. 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. A tear string 15 is provided between the rope 13 and the resin coating 14 for tapping the rope 13. The rope 13 usually collects a large number of fibers 11 to form a bundle 12,
Further, the bundle 12 is formed by twisting.
It is desirable that the fiber 11 is flexible and has excellent strength. Usually, high-strength synthetic fibers such as nylon, Tetron (trade name) and Dyneema (trade name) are used, and particularly, the tensile strength is excellent. Therefore, nylon or Tetron is preferably used. The type and number of fibers 11 forming the rope 13 are appropriately selected according to the type and weight of the cable to be pulled, and are not particularly limited. For example, in the case of pulling a cable having a pulling force of 150 kgf, a bundle of four bundles of 1000 d fibers 11, six bundles thereof, and a twist of twelve such bundles is used. When a cable such as a power cable, an optical cable, a coaxial cable, or the like is pulled into a pipeline by using the extension rope 10, the resin coating 14 forms a gap between the extension rope 10 and an existing cable in the pipe. To prevent the cable sheath from being worn and damaged, and to reduce the frictional resistance between the extension rope 10 and the conduit so that the cable can be pulled with a small pulling force. And is formed on the circumference of the rope 13. 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 the frictional resistance can be obtained, but in order to obtain a further improvement effect, a resin composition containing a lubricant mixed with the resin must be 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 lubricity of the surface of the resin coating 14 can be maintained for a long time. The tear cord 15 provided between the resin coating 14 and the rope 13 is used to connect the cable to be laid with the cable for extension 10 with the resin coating 14 of the cable for extension 10.
Is used to pierce the rope 13 and twist the fiber having a large elongation at break (%) to form a thread. As such a fiber, a polyester fiber, a polypropylene fiber, an aramid fiber or the like is usually used. Further, the tear string 15 in the present invention has a tear string 15 whose length is longer than the entire length of the rope 13, that is, has an extra length (%), and has an elongation at break of the tear string 15 (%). %) And the surplus length (%) of the tearing string 15 are larger than the allowable tension elongation (%) of the rope 13. That is, even when the rope 13 extends to near the allowable tension elongation, the tear string 15 is not torn. Here, the extra length (%) of the tear string 15 is
It is a ratio of the length obtained by subtracting the total length of the rope 13 from the total length of the tear string 15 to the total length of the rope 13, and is defined by the formula (I). ｛(Total length of tear string 15−total length of rope 13) / total length of rope 13｝ × 100 (%) (I) The elongation at break (%) of tear string 15 is defined as the tensile test of tear string 15. , The elongation percentage of the tear string 15 when the tear string 15 is broken,
Defined in I). ｛(Length of tear string at break 15−length of tear string 15 before tensile test) / length of tear string 15 before tensile test｝ × 100 (%) (II) Allowable tension of rope 13 Elongation (%) is similarly defined by equation (III). ｛(Length of rope 13 at the time of application of allowable tension−length of rope 13 before tensile test) / length of rope 13 before tensile test｝ × 100 (%) (III) Allowable tension elongation (%) of the defined rope 13 and elongation at break of the tear string 15 (%)
Varies depending on the material and shape of the tearing string 15 and the rope 13, and the sum of the elongation at break (%) of the tearing string 15 and the extra length (%) of the tearing string 15 is equal to the rope 1.
3, the material and shape of the rope 13 and the tear string 15 and the tear string 15 so as to be greater than the allowable tension elongation (%).
Is selected (%). For example, the allowable tension elongation (%) of the rope 13 differs not only depending on the material of the fiber 11, but also depending on the pitch, which is the twist interval of the rope 13, even when the fiber 11 of the same material is used. That is, when the pitch is large, the allowable tension elongation (%) of the rope 13 decreases, and when the pitch is small, the allowable tension elongation (%) increases. Therefore,
The rope 13 is selected in consideration of such a pitch size and the like. It is preferable that the extra length of the tear string 15 is 5% or less. If this exceeds 5%, the tear string 15 contained between the rope 13 and the resin coating 14 is too long.
This is because the adhesion of No. 4 is obstructed and causes peeling, or the amount of the tearing string 15 protruding at the time of tapping increases, and the coating 14 becomes difficult to avoid. As described above, the rope for wire drawing 10 in which the material, shape, and the surplus length (%) of the tearing string 15 are appropriately combined with the material and shape of the rope 13, the rope 13 is pulled in the length direction when the cable is towed. Even when the rope 13 is extended to near the allowable tension elongation (%), the sum of the elongation at break (%) of the tear string 15 and the extra length (%) of the tear string 15 is the allowable tension elongation (%) of the rope 13. ), There is no possibility that the tear string 15 may be torn. Therefore, even when the extension rope 10 is repeatedly used and is pulled many times so as to extend to the vicinity of the allowable tension elongation (%), the tear string 15 does not tear, so that the tear string 15 is used reliably and easily. Resin coating 1
4 can be torn and the rope 13 can be tapped. 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. Such a rope 10 for extending a wire is
Resin coating 1 made of resin such as polyethylene on the circumference of 3
4, the frictional resistance between the cable and the pipeline is reduced to suppress wear and tear of the cable, and the cable can be pulled with a small traction force.
In addition, by adding an aliphatic amide such as stearic acid amide or erucic acid amide as a lubricant to the resin and making the resin coating 14 a lubricating resin coating, the slipperiness of the surface is further improved, and The frictional resistance between the cable 10 and the existing cable and the frictional resistance between the extension rope 10 and the pipeline can be reduced. Further, in the wire rope 10 of the present invention, the tear string 15 is provided between the rope 13 and the resin coating 14 ((the extra length (%) of the tear string 15 + the elongation at break (%) of the tear string 15))> Since the rope 13 is provided so as to have the allowable tension elongation (%), there is no possibility that the tear string 15 may be broken by repeated use. Therefore, the resin coating 14 can be reliably and easily torn by using the tear string 15 and the rope 13 can be tapped. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An extension rope 10 according to an embodiment of the present invention will be specifically described in comparison with a comparative example. Example 1 A rope having an allowable tension elongation (%) as shown in Table 1 was used as the rope 13 constituting the wire rope 10 shown in FIG. 1, and a tear as shown in Table 2 as a tear string 15. Using the tear string 15 having a point elongation (%), various ropes 10 for wire drawing shown in Table 3 were produced. Tear string 1
A sample in which the sum of the extra length (%) of 5 and the elongation at break (%) is smaller than the allowable tension elongation (%) of the rope 13 was used as a comparative example. These various types of extension ropes 10 were evaluated for their leadability. Table 3 shows the results. As is clear from Table 3, those of Examples 1 to 9 in which the sum of the extra length (%) and the elongation at break (%) of the tearing string is larger than the allowable tension elongation (%) of the rope 13. Is the type of the rope 13 and the tear string 15
Irrespective of the type of the lipstick, it shows that the lipstick is excellent. On the other hand, in Comparative Examples 1 to 7 in which the sum of the extra length (%) of the tearing cord 15 and the elongation at break (%) is smaller than the allowable tension elongation (%) of the rope 13, the type and tear of the rope Irrespective of the type of the string 15, the tearing string 15 was torn in the middle of the tear and the mouth could not be opened. [Table 1] [Table 2] [Table 3] As described above, the present invention is a rope for drawing in which a resin coating such as polyethylene is provided on the periphery of a rope formed by twisting a fiber, so that friction between the drawing rope and an existing cable is obtained. In addition, since the friction between the extension rope and the pipeline is small and the cable can be pulled with a small pulling force, the existing cable can be laid without abrasion damage when additionally laying the cable. Also, as the resin coating,
When using aliphatic amides such as stearic acid amide as a lubricant or resin with excellent lubricity such as silicone-dispersed polyethylene, the wear and tear of existing cables during installation is further reduced. Can be done. In addition, the rope for wire drawing of the present invention is provided with a tear string between the rope and the resin coating so as to withstand an elongation larger than the allowable tensile elongation (%) of the rope. Even when the cord is stretched to near the tensile elongation, the tear string does not tear, so that the rope can be reliably and easily pulled out using the tear string.

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, 15 ... Tear string

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Suehiro Miyamoto 1440, Misaki, Sakura City, Chiba Prefecture Fujikura Co., Ltd. Sakura Office (72) Inventor Takashi Matsuzawa 1-5-1, Kiba, Koto-ku, Tokyo Inside Fujikura Co., Ltd. (56) References JP-A-8-110450 (JP, A) JP-A-3-249289 (JP, A) JP-A-3-287886 (JP, A) JP-A-1-1533397 (JP, U) Kaihei 1-153396 (JP, U) Registered utility model 3054928 (JP, U) (58) Fields investigated (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, and a tearing string is provided between the rope and the resin coating. And a sum of a surplus length (%) of the tear string and an elongation at break (%) of the tear string is larger than an allowable tension elongation (%) of the rope.