JP2001124251A - Strip for forming spiral tube, and spiral pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a strip for forming a spiral pipe which can obtain the spiral pipe which is free from any peeling of a sealing material formed on an inner edge of an opening end of a fitting part, excellent in watertightness and airtightness and excellent in mechanical properties. SOLUTION: In the strip 1 for forming the spiral pipe P by spirally winding the strip having a fork-like fitting part 2 on one side edge and an arrowhead- like locking part 3 on the other side edge, and fitting the adjacent fitting part 2 to the locking part 3, the sealing material 25 is bitten in a recessed groove 211 of a locking part 21 of the strip 1, and integrated with an inner edge of the opening end of the fitting part 2 of the strip forming an outer side in the winding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a band for forming a spiral tube and a spiral tube formed from the band.

[0002]

2. Description of the Related Art A helical tube manufactured by helically winding a strip made of a rigid vinyl chloride resin extruded into a strip and fitting adjacent portions together has excellent elasticity and flexibility. Therefore, it is used in a wide range of fields (for example, see Japanese Utility Model Publication No. 41-16849). As one of the strips, for example, one having a bifurcated fitting portion on one side edge and an arrowhead-shaped locking portion on the other side edge is used.

[0003] The band is formed by extruding a band having a bifurcated fitting portion on one side edge and an arrowhead-like locking portion on the other side edge from a mold. This is performed by uniformly cooling the entire belt-like body in a water tank while shaping with a shaping device, and then winding it around a drum with a winder.

[0004] Normally, it is wound up on a drum and stocked as a work-in-progress, but without being wound up by a winder,
For example, JP-A-1-269786 and JP-A-2-1-1
In some cases, using a tube manufacturing machine disclosed in Japanese Patent Application Laid-Open No. 82430 for manufacturing a spiral tube, a belt-shaped body to be taken up by a take-off machine after being cooled is spirally wound as it is to form a spiral tube.

When the spiral tube is used as a protective tube for a power cable, a communication cable, and the like, a high degree of watertightness and airtightness is required in addition to mechanical properties such as compression and tensile strength and impact resistance. .

For this reason, when extruding a strip, generally, an elastomeric sealing material such as a soft vinyl chloride resin is attached to the inner edge of the open end of the bifurcated fitting portion of the strip. Are formed by co-extrusion over the entire length of.

[0007] When a spiral tube is manufactured, the belt-like body is forcibly spirally wound around a mandrel for manufacturing the tube, so that a circumferential distortion is necessarily generated inside the tube wall of the spiral tube. become.

[0008]

However, in the case where the sealing material is simply co-extruded on the inner edge of the open end of the fitting portion, as in the above-mentioned belt-like body, the seal material is peeled off from the inner edge of the open end when the spiral tube is formed. However, there is a problem that watertightness and airtightness are impaired. In particular, when the diameter of the spiral pipe to be formed is small, when the arrowhead-shaped engaging portion is pushed into the forked fitting portion and fitted therein, the sealing material is more easily peeled off. was there.

When the sealing material is a soft vinyl chloride resin, the degree of migration of the added plasticizer, that is, the kind of the plasticizer accelerates the peeling of the sealing material depending on the type of the plasticizer, and the resistance of the spiral tube is increased. There is a problem that the impact strength is reduced.

[0010] It is an object of the present invention to provide a helical tube which can obtain a helical tube having excellent water-tightness and air-tightness and excellent mechanical strength without peeling off a sealing material formed on an inner edge of an opening end of a fitting portion. The object is to provide a band for forming a tube.

[0011]

According to the first aspect of the present invention, a belt-like body having a bifurcated fitting portion on one side edge and an arrowhead-like locking portion on the other side edge is formed in a spiral shape. In a band for spiral tube formation for forming a tubular spiral tube by winding a winding portion and fitting a fitting portion and a locking portion adjacent in the axial direction,
The sealing material is integrated into the inner edge of the opening end of the fitting portion of the band which is the outer surface side when wound around the entire length of the band.

As the material of the strip in the present invention, a hard vinyl chloride resin having a softening temperature of 80 ° C. or higher and a melting temperature of 130 ° C. or lower or a chlorinated vinyl chloride resin is preferable. Further, as a material of the sealing material, an elastomer such as a soft vinyl chloride resin is preferable, and a material containing a trimellitic acid-based plasticizer such as trimellitic acid-tri-2-ethylhexyl is preferable.

According to a third aspect of the present invention, there is provided a helical tube manufactured using the belt-shaped body according to the first or second aspect.

(Function) In the present invention, the sealing material is integrated into the inner edge of the opening end of the fitting portion of the band which becomes the outer surface side when wound, over the entire length of the band. Also, even when an external force such as bending or torsion generated when the spiral tube is formed acts, the sealing material does not peel off from the strip. For this reason, it is possible to obtain a helical tube that can prevent intrusion of water from the fitting connection portion due to earth pressure or wheel load.

According to the second aspect of the present invention, the belt is made of a hard vinyl chloride resin, and the sealing material is a soft vinyl chloride resin containing trimellitic acid-tri-2-ethylhexyl having a low migration property. Therefore, the adhesiveness between the inner edge of the opening end of the fitting portion and the sealing material is not easily impaired, and the sealing material does not peel off. In addition, since the strength of the strip does not decrease, a helical tube having excellent mechanical strength can be obtained.

Therefore, the spiral tube according to the third aspect of the present invention is suitable as a buried protective tube for a power cable, a communication cable and the like.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a band for forming a spiral tube according to the present invention.

In FIG. 1, a belt-like body 1 is formed by extrusion molding from a hard vinyl chloride resin, and has a substantially Y-shaped cross section over its entire length. The belt-shaped body 1 has a bifurcated fitting portion 2 on one side edge, and a locking portion 3 slidably fitted and locked in the fitting portion 2 on the other side edge. At the inner edge of the open end of the fitting portion 2, retaining portions 21 and 22 are provided to face each other. The open end faces of the retaining portions 21 and 22 are formed as divergent tapered surfaces 23 and 24. An arrowhead-shaped projection 31 is provided at the tip of the locking portion 3.

The retaining portion 21 at the inner edge of the opening end of the fitting portion 2 of the belt-shaped body 1 which is on the outer surface side when winding is provided.
A sealing material 25 made of a soft vinyl chloride resin is coextruded and integrated over the entire length of the belt-shaped body 1. As shown in FIG. 2, a part of the sealing material 25 is
The belt-like body 1 is integrated into the concave groove 211 formed in the same. The width of the concave groove 211 is about 1/3 of the width of the retaining portion 21. Seal material 25
Contains trimellitic acid-tri-2-ethylhexyl as a plasticizer. The ratio of the soft vinyl chloride resin to the plasticizer is about 1: 1 by weight.

In order to manufacture a helical tube using the above-mentioned band-shaped body 1, for example, a bifurcated fitting portion 2 is spirally wound by using a tube making machine disclosed in Japanese Patent Application Laid-Open No. 2-182430. The helical tube P shown in FIG. 3 is manufactured by pushing and fitting the arrowhead-shaped projections 31 of the adjacent locking portions 3 using the tapered surfaces 23 and 24 therein.

In the case of this embodiment, as shown in FIG. 2, since a part of the sealing material 25 is cut into the groove 211 of the retaining portion 21 and integrated, the groove 211 does not exist. In comparison with the case, the bonding area of the sealing material 25 to the retaining portion 21 is about 1.6 times. As a result, the adhesive strength of the sealing material 25 to the retaining portion 21 becomes about 1.6 times. Moreover, the plasticizer contained in the sealing material 25 is
Since it is trimellitic acid-tri-2-ethylhexyl having a low migration property, it does not affect the impact strength of the band 1 made of hard vinyl chloride resin.

The spiral pipe manufactured in this manner is used as an underground pipe, and does not crack even if a repeated load such as earth pressure or wheel load is applied. can do.

[0023]

According to the first aspect of the present invention, since the sealing material is integrated into the inner edge of the opening end of the fitting portion of the band which becomes the outer surface side when wound, over the entire length of the band. Even when external force such as bending or torsion that occurs when forming a spiral tube acts, the sealing material does not peel off from the strip, preventing water from entering from the fitting connection due to earth pressure or wheel load A helical tube can be obtained.

According to the second aspect of the present invention, the strip is made of a hard vinyl chloride resin, and the sealing material is a soft vinyl chloride resin containing trimellitic acid-tri-2-ethylhexyl having a small migration property. Because it is made of
The adhesive property between the inner edge of the opening end of the fitting portion and the sealing material is not impaired, and the sealing material does not peel off. In addition, since the strength of the strip does not decrease, a helical tube having excellent mechanical strength can be obtained.

Therefore, the spiral tube according to the third aspect of the present invention can be suitably used as a buried protective tube for a power cable, a communication cable, and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a band for forming a spiral tube according to the present invention.

FIG. 2 is an enlarged sectional view showing a main part of FIG.

FIG. 3 is a partial cross-sectional view showing a spiral tube formed from the strip of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Band-shaped body 2 Fitting part 21,22 Retaining part 211 Depressed groove 23,24 Tapered surface 25 Seal material 3 Locking part 31 Projection

Claims (3)

[Claims] 1. A belt-like body having a bifurcated fitting portion on one side edge and an arrowhead-like locking portion on the other side edge is spirally wound and locked with a fitting portion adjacent in the axial direction. In a band for forming a helical tube for forming a cylindrical helical tube by fitting the parts, a sealing material is formed on the inner edge of the opening end of the fitting portion of the band which is the outer surface side when wound. A strip for forming a spiral tube, wherein the strip is formed by biting and being integrated over the entire length of the body. 2. The belt-shaped body is made of a hard vinyl chloride resin, and the sealing material is trimellitic acid-tri-2 as a plasticizer.
The strip for forming a spiral tube according to claim 1, wherein the strip is made of a soft vinyl chloride resin containing -ethylhexyl. 3. A helical tube formed from the strip for forming a helical tube according to claim 1.