JPH0596675U - Corrugated synthetic resin flexible tube - Google Patents

Abstract

(57) [Summary] [Constitution] When the maximum outer diameter of the corrugated synthetic resin flexible tube is D, the Young's modulus of the tube material is E, and the tensile yield strength of the tube material is F,
The wave height h of the corrugation satisfies (E × h) / D ≧ 375 kg / cm ² , the pitch p of the corrugation satisfies p / h ≦ 5, and the length of the pipe in the longitudinal direction is 15 mm in the longitudinal section passing through the axis of the pipe. Corrugated synthetic resin flexible tube, characterized in that the minimum area S of the cut end face of is satisfied with F × S ≧ 150 kg. [Effect] It has flat compression strength and flexibility, and at the same time has the property of being able to withstand local stress to the extent that even if the pipe is hit with a pickaxe Tsuruhashi, it will not cause holes or cracks in the pipe or deformation that will hinder the passage of wires. . It is extremely useful as a protective tube for underground cables.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a corrugated synthetic resin flexible tube suitable for protecting underground power cables, communication cables and the like. More specifically, it relates to a corrugated synthetic resin flexible tube having excellent balance of mechanical strength and flexibility, and particularly excellent local stress resistance.

[0002]

[Prior Art]

 In recent years, from the viewpoint of effective use of land and beautification of cityscapes, underground embedding of power cables has been actively carried out. Especially in urban areas, the demand is remarkable. Such protective tubes for underground power cables include Japanese Patent Publication No. 60-40248 and Japanese Patent Publication No. 61-27972, and the protective tubes for underground electric power cables listed therein are Since it is a rigid straight pipe, it is not flexible and cannot easily bypass the existing pipeline, making it difficult to handle, and since it cannot be supplied in a long length, it has many connection points and poor workability.

Considering the conditions required at the time of laying a pipe to be buried underground, first of all, it is desired to shorten the construction period because of the large traffic volume. For this reason, pipes that are buried underground are required to be capable of excavating, laying pipes, and backfilling overnight, being lightweight and easy to handle, and being long and have few connection points. .. Second, in urban areas, there are many existing buried objects such as pipelines, so it is necessary to be able to easily bypass such existing buried objects and to be able to easily cut where necessary. Therefore, a synthetic resin flexible tube provided with a corrugated shape is used.

As a synthetic resin flexible tube for such purpose, when the maximum outer diameter D of the tube and Young's modulus E of the tube material are disclosed in Japanese Patent Publication No. 46-20230, the wave height h is (E × h) / D. ≧ 375 kg / cm ² , wall thickness t is between 1 mm ≦ t ≦ 5 mm, pitch p satisfies p / h ≦ 5, and has axis symmetry or spiral waveform 10-250 kg / mm A corrugated synthetic resin flexible tube consisting essentially of a thermoplastic resin with a yang factor of ² is shown. Such a corrugated synthetic resin flexible tube has flexibility such that it can be bent manually and has a high flat strength such as 1 ton / m or more when deformed by 20% under lateral pressure.

Further, as an example of the mechanical strength of such a corrugated synthetic resin flexible tube, there is a corrugated synthetic resin flexible tube in which a metal reinforcing layer is provided in Japanese Utility Model Publication No. 1-123420. However, since such a flexible tube uses metal, it has a problem of metal corrosion by all means, and especially in the underground, it is humid and it is not known what kind of chemicals it is exposed to. There is a problem with long life to use as. Also in terms of workability, since metal is used, it cannot be easily cut, resulting in poor workability.

On the other hand, during construction such as re-excavation of an already buried pipe and its peripheral portion, a worker may accidentally hit the pipe with a crane bridge and damage the pipe. Not only is the damage caused even to the cables that pass through it, but it is also dangerous. For this reason, it is desirable that the cable protection pipe buried underground should have the property of withstanding local stress such that holes, cracks, and deformation will not occur even if it is hit by a pickaxe. However, neither the above-mentioned corrugated synthetic resin flexible tube nor the above corrugated synthetic resin flexible tube provided with the metal reinforcing layer can withstand a sufficient local stress.

[0007]

[Problems to be solved by the device]

 Therefore, the present invention has, as basic performance required as an underground buried pipe for urban areas used for protecting power cables, a flat strength capable of withstanding earth pressure and a live load such as a passing truck. It has the characteristics of being flexible, lightweight and easy to handle, as well as being capable of easily avoiding existing pipelines, being able to withstand uneven settlement, and being bendable by human power. It is an object of the present invention to provide a corrugated synthetic resin flexible tube having characteristics (hereinafter referred to as pick-should impact resistance) capable of withstanding local stress to the extent that deformation that would hinder holes, cracks, and wires does not result.

[0008]

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention provides a corrugated wave height h when the maximum outer diameter of the corrugated synthetic resin flexible tube is D, the Young's modulus E of the tube material, and the tensile yield strength of the tube material are F. Satisfies (E × h) / D ≧ 375 kg / cm ² , the pitch p of the corrugations satisfies p / h ≦ 5, and the cut end surface of the longitudinal direction of the pipe in the longitudinal direction passing through the axial center of the pipe is 15 mm. Provided is a corrugated synthetic resin flexible tube having a minimum area S satisfying F × S ≧ 150 kg.

Assuming that the wave height h does not satisfy the range of (E × h / D) ≧ 375 kg / cm ² , the flat strength at 20% deformation of the corrugated synthetic resin flexible tube is 1 ton / m or less, which is sufficient. It will not be a corrugated synthetic resin flexible tube with excellent pressure resistance.

Further, when the pitch p deviates from the range of p / h ≦ 5, the flat strength at 20% deformation of the corrugated synthetic resin flexible tube becomes 1 ton / m or less, or the minimum bending radius becomes large and human power is increased. Bending is difficult or impossible. That is, the flexibility becomes insufficient.

Furthermore, the relationship between the minimum area S of the cut end face having a length of 15 mm in the longitudinal direction of the pipe and the tensile yield strength F of the pipe material in the longitudinal section passing through the axial center of the pipe is in the range of F × S ≧ 150 kg. It was found for the first time that it had pickaxe impact resistance. Here, the minimum area S of the cut end face having a length of 15 mm in the longitudinal direction of the pipe in the longitudinal section passing through the axial center of the pipe is, as shown in FIG. 1, the longitudinal section 2 passing through the axial center of the corrugated synthetic resin flexible tube 1. It is the minimum value that can be taken by the cut end face 3 having a length of 15 mm in the longitudinal direction of the pipe.

Further, the waveform of the corrugated synthetic resin flexible tube of the present invention may be an axisymmetric waveform or a spiral waveform.

The corrugated synthetic resin flexible tube of the present invention can be manufactured by using various materials. For example, when a hard polyvinyl chloride resin composition is used, a mixing device such as a Henschel mixer or a Banbury mixer is used. It is obtained by mixing and mixing, further extruding using an extruder, for example, a conical twin-direction twin-screw extruder, and then using a molding machine, performing common corrugation for imparting flexibility to the tube. When a high-density polyethylene resin composition is used, it is extruded using a single-screw extruder and then corrugated using a molding machine.

[0014]

【Example】

An embodiment of the present invention will be shown below. Examples 1 to 5 The maximum outer diameter D of the corrugated synthetic resin flexible tube, the Young's modulus E of the tube material, the tensile yield strength F of the tube material, the wave height h of the waveform, and the minimum cross-sectional area S of the width of 15 mm in the tube axis direction are It is the value shown in Table 1, and is the corrugated synthetic resin flexible tube of the present invention satisfying (E × h) / D ≧ 375 kg / cm ² , p / h ≦ 5, and F × S ≧ 150.

Comparative Examples 1 to 3 The maximum outer diameter D of the corrugated synthetic resin flexible tube, the Young's modulus E of the tube material, the tensile yield strength F of the tube material, the wave height h of the waveform, and the disconnection of the tube in the axial direction of 15 mm width. The value of the minimum cross-sectional area S of the area is the value shown in Table 1, which satisfies (E × h) / D ≧ 375 kg / cm ² and p / h ≦ 5, but F × S <150 kg. It is a tube.

Table 1 shows the results of pickaxe impact resistance test performed on the tubes of Examples 1 to 5 and Comparative Examples 1 to 3.

The tensile yield strength of the tube material was measured in accordance with JIS K 7113 using a No. 2 test piece at a tensile speed of 10 mm / min.

In addition, in the test of pickaxe impact resistance, an impact tester that was mechanized and easily quantified was used. This impact tester is JIS C 3801 (insulator test method) 7. Using a tester that complies with the impact load resistance test method in Section 14, attach a 16.16 kg load (pickaxe-like tip) to the tip of an arm that can rotate freely and have a length of 1 m, and then drop the arm by itself from an angle of 95 °. To check whether the test tube fixed perpendicular to the axis center is impacted and does not damage the cable inserted inside the test tube, and whether the tube is cracked or deformed to impair the wireability. Is.

[0019]

[Table 1]

[0020]

[Effect of the device]

In the flexible tube of the present invention, when the maximum outer diameter of the corrugated synthetic resin flexible tube is D, the Young's modulus of the tube material is E, and the tensile yield strength of the tube material is F, the wave height h of the waveform is (E × h ) / D ≧ 375 kg / cm ² , the corrugated pitch p satisfies p / h ≦ 5, and the minimum area S of the cut end face of the longitudinal direction of the pipe of 15 mm in the longitudinal section passing through the axis of the pipe is By satisfying F × S ≧ 150 kg, it has a flat compressive strength that can withstand earth pressure and live load of passing trucks, etc., and can easily avoid existing pipelines and withstand uneven settlement and manpower. It has flexibility such that it can be bent, and at the same time, even if an operator accidentally hits the pipe with the Tsuruhashi Tsuruhashi by all means, the pipe will be deformed that will cause holes, cracks, and obstruction of the passage. It has the characteristic of being able to withstand a local stress that does not cause it (pickling impact resistance). Also, because it is made of resin, it is lightweight, easy to handle, and free from corrosion. Therefore, the corrugated synthetic resin flexible tube of the present invention is extremely useful as an underground cable protection tube.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a corrugated synthetic resin flexible tube of the present invention.

[Explanation of symbols]

1 Waveform synthetic resin flexible tube 2 Cross section in the axial direction of the tube 3 Longitudinal direction 15 m of the tube in the vertical cross section passing through the axis of the tube
Cut end face of m length p Pitch h Wave height D Maximum outer diameter

Claims (1)

[Scope of utility model registration request] 1. When the maximum outer diameter of a corrugated synthetic resin flexible tube is D, the Young's modulus of the tube material is E, and the tensile yield strength of the tube material is F, the wave height h of the waveform is (E × h) / Satisfies D ≧ 375 kg / cm ² , the pitch p of the corrugations satisfies p / h ≦ 5, and the minimum area S of the cut end face having a length of 15 mm in the longitudinal direction of the pipe in the longitudinal section passing through the axial center of the pipe is F × S. A corrugated synthetic resin flexible tube characterized by satisfying ≧ 150 kg.