JP2023047542A - Corrugated covering pipe and composite pipe - Google Patents

Abstract

To increase a superimposed load on a composite pipe by enhancing the strength of a corrugated covering pipe against a radial compressive load.SOLUTION: A corrugated covering pipe 20 covering a flexible inner pipe 10 comprises annular crest parts 21 and annular trough parts 22 alternately arranged in a pipe axis direction, and holding protrusions 23 dispersed in the pipe axis direction and a circumferential direction, and arranged independently of each other. The holding protrusions 23 protrude in a radial inward direction from the trough parts 22, and hold the inner pipe substantially concentrically with a pipe axis by tips 230 thereof. The holding protrusions 23 are formed so as to cross the crest parts 21 and the trough parts 22 in the pipe axis direction, and a dimension L of the holding protrusions 23 in the pipe axis direction is longer than one pitch P including the crest part 21 and the trough part 22.SELECTED DRAWING: Figure 2

Description

The present invention relates to a corrugated cladding over a flexible inner tube suitable for fluid transport and a composite tube comprising an inner tube and a corrugated cladding.

As a flexible cladding pipe for protecting a flexible pipe (inner pipe) for supplying water and hot water, a corrugated cladding pipe in which crests and troughs are alternately arranged is known. Since it is necessary to expose the inner pipe when connecting the inner pipe to the joint, the corrugated cladding pipe easily expands and contracts in the pipe axial direction.

In the corrugated cladding pipes of Patent Documents 1 to 3, holding projections protruding further radially inward from the troughs are dispersedly arranged, and lateral movement of the inner pipe is restricted by the tips of these holding projections, so that the inner pipe is secured to the corrugated cladding pipe. held concentrically with the tube axis of This suppresses the flapping sound of water hammer caused by sudden closing of the faucet, etc., and enhances heat retention.

JP 2021-41539 A Japanese Patent Application Laid-Open No. 2021-138140 Japanese Patent Application Laid-Open No. 2021-139500

In the cladding tubes of Patent Documents 1 to 3, the holding protrusions are formed so as to protrude further radially and inward from the troughs, and their axial dimensions are limited to approximately the width of the troughs. there is As a result, the strength of the holding projections against a compressive load in the radial direction is insufficient, and for example, when a composite pipe in which an inner pipe is covered with a cladding pipe is loaded, the cladding pipe may be crushed.

In order to solve the above problems, the present invention provides a corrugated cladding tube for cladding a flexible inner tube, comprising annular peaks and annular troughs alternately arranged in the axial direction of the tube, and holding protrusions distributed in the circumferential direction and arranged independently of each other, protruding radially inward from the valley portion, and holding the inner tube substantially concentrically with the tube axis by the tip of the protrusion, A dimension of the holding protrusion in the tube axis direction is longer than one pitch including one peak and one valley.
According to this configuration, since the holding projections have a dimension in the tube axial direction longer than one pitch between the peaks and the valleys, the strength of the holding projections against radial compressive load can be increased, and the corrugated cladding tube has a diameter Even if a compressive load is applied from the direction outside, it will not be crushed easily. Therefore, it is possible to increase the load of the composite pipe in which the inner pipe is covered with the cladding pipe.

Specifically, the holding projection is formed so as to cross at least one valley or at least one peak in the pipe axial direction.

Preferably, the holding protrusion is formed so as to traverse one peak and two valleys in the pipe axial direction. According to this configuration, the dimension of the holding projection in the tube axis direction can be made sufficiently long, and the strength of the holding projection can be reliably increased.

More preferably, the holding projection is formed so as to cross two peaks and three valleys in the pipe axial direction. According to this configuration, the dimension of the holding protrusion in the tube axis direction can be further increased, and the strength of the holding protrusion can be further increased.

Preferably, the holding projection has a pair of first side walls facing each other in the axial direction and a pair of second side walls facing each other in the circumferential direction, and the roots of the pair of first side walls are connected to the ridges. , the pair of second side walls are connected to the troughs and peaks crossed by the holding projections.
According to this configuration, the bases of the pair of first side walls are connected to the ridges, and the bases of the pair of second side walls are connected to the troughs and ridges crossed by the holding protrusions. Strength against radial compressive load can be further increased.

Preferably, the pair of first side walls incline toward each other in a radially inward direction, and each of the first side walls has an inclination angle of more than 20° with respect to a plane perpendicular to the tube axis. are doing.

Preferably, a cross section of the holding projection along the tube axis direction is V-shaped by the pair of first side walls.

The pair of second side walls are slanted toward each other in the radially inward direction, and each of the second side walls has an inclination angle of more than 20° with respect to a plane passing through the tube axis.

Preferably, the tip of the holding protrusion forms a concave curve when viewed from the tube axis direction. According to this, when a compressive load is applied in the radial direction, the tips of the holding protrusions contact the outer circumference of the inner pipe without slipping, so that the strength against the compressive load can be increased.

Preferably, the ridges have a short cylindrical shape, the groove width of the troughs is 25% or more of the one pitch, and the recess depth of the holding projection is larger than the groove width of the troughs.

Another aspect of the present invention is a composite tube including a flexible inner tube and the corrugated covering tube covering the inner tube.

According to the present invention, the strength of the corrugated cladding tube against radial compressive load can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view showing a composite pipe including a corrugated cladding pipe according to a first embodiment of the present invention, with only an upper half section in cross section; FIG. 2 is a side view showing an enlarged cross-section of the main part of FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2; FIG. FIG. 2 is a view equivalent to FIG. 2 of a composite tube including a corrugated cladding tube according to a second embodiment of the present invention; 3 equivalent view of a composite tube including a corrugated cladding tube according to a third embodiment of the present invention. FIG.

<First embodiment>
An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. As shown in FIG. 1, the composite tube 1 includes a flexible inner tube 10 and a flexible corrugated sheathing tube 20 (corrugated tube) covering the inner tube 10 . The composite pipe 1 is used, for example, as a pipe for water supply/hot water supply. The inside of the inner pipe 10 serves as a fluid passage through which fluid such as water and hot water passes.

The inner tube 10 is formed with a constant circular cross section over its entire length and is flexible. The inner tube 10 may be a crosslinked polyethylene (PE-X) tube, a polybutene (PB) tube, a polyethylene (PE) tube, a heat-resistant polyethylene (PE-RT) tube, or a resin tube containing two or more of these resins. can be used. A metal-reinforced resin pipe containing at least one of the above resins and a metal can also be used. The above is an example, and the material of the inner tube 10 is not particularly limited as long as it can ensure the required performance such as flexibility and fluid flowability.

The corrugated cladding tube 20 is made of a single-layer resin tube, and may be a polyethylene (PE) tube, a crosslinked polyethylene (PE-X) tube, a polybutene (PB) tube, a heat-resistant polyethylene (PE-RT) tube, or any of these resins. A resin tube containing two or more resins can be used. Also, the flexibility of the cladding tube 20 may be improved by foaming. In this case, it is preferable to use polyethylene (PE) as a main component and to have a low foaming ratio of 1.05 to 4 times. The above is just an example, and the material of the corrugated cladding tube 20 is not particularly limited as long as it can ensure the required performance such as flexibility and protection of the inner tube 10 .

As shown in FIGS. 1 and 2, the corrugated cladding tube 20 has a corrugated cross section by alternately arranging annular peaks 21 and annular valleys 22 in the tube axial direction at the same pitch. As shown in FIG. 2, the ridges 21 have a short cylindrical shape with a constant diameter, and the troughs 22 have a U-shaped or V-shaped cross section. One pitch P is defined as a pipe axial dimension including one peak 21 and one valley 22 .

The corrugated cladding tube 20 further has holding projections 23 which are distributed in the axial direction and in the circumferential direction and which are independent of each other. In the present embodiment, four holding projections 23 are formed at equal intervals in the circumferential direction at locations where the holding projections 23 are formed at equal intervals in the pipe axis direction. The holding protrusions 23 protrude radially inward from the troughs 22 , and their distal ends 230 are in contact with or close to the outer circumference of the inner tube 10 . substantially concentric with the

The holding projection 23 has a pair of first side walls 231, 231 facing each other in the axial direction as shown in FIG. 2, and a pair of second side walls 232, 232 facing each other in the circumferential direction as shown in FIG. are doing. The pair of first side walls 231, 231 are slanted so as to approach each other radially inward, so that the holding projection 23 has a V-shaped cross section along the tube axis direction. Similarly, the second side walls 232, 232 are slanted toward each other radially inward, so that the holding projection 23 has a substantially V-shaped cross section orthogonal to the pipe axis. In this embodiment, the tip 230 has a convex curve when viewed from the tube axis direction.

As shown in FIG. 2, the axial dimension L of the holding protrusions 23 is longer than 1 pitch P, and is about 1.5P in this embodiment. The holding projection 23 is formed so as to traverse one peak portion 21 and two valley portions 22 in the pipe axial direction. The center of the holding protrusion 23 in the tube axis direction coincides with the position of the one peak portion 21 in the tube axis direction. The pair of first side walls 231 are symmetrical with respect to the center of the holding projection 23 in the tube axis direction and are inclined at the same angle. The inclination angle Θ1 of the first side wall 23a with respect to the plane perpendicular to the tube axis is 20° or more, and is about 30° in this embodiment. Roots 231a of a pair of first side walls 231 of the holding projection 23 are connected to two peaks 21 adjacent to the two crossed valleys 22, respectively.

As shown in FIG. 3, the pair of second side walls 232 of the holding projection 23 are symmetrical about the circumferential center of the holding projection 23 and inclined at the same angle. The inclination angle Θ2 of the second side wall 232 with respect to the plane containing the tube axis is 20° or more, and is about 45° in this embodiment. A root 232a of the second side wall 232 is connected to one peak 21 and two valleys 22 crossed by the holding projection 23, forming a wave shape.

In the corrugated cladding tube 20, the holding projections 23 hold the inner tube 10 concentrically, thereby suppressing the fluttering of the inner tube 10 and suppressing noise, as well as improving heat retention. Since the holding projections 23 are distributed in the direction of the tube axis, they do not affect the stretchability in the direction of the tube axis. Since the holding protrusions 23 are distributed in the circumferential direction, the risk of the structure being caught can be suppressed.

The holding protrusions 23 have a dimension in the pipe axis direction longer than 1 pitch P between the peaks 21 and the valleys 22, and in this embodiment have a dimension of about 1.5P, so that the compressive strength in the radial direction is increased. In addition, the strength of the corrugated cladding tube 20 against a radial compressive load can be increased. As a result, when loading the composite pipe 1 with the corrugated cladding pipe 20 covering the inner pipe 10, the load that can be loaded can be increased without the corrugated cladding pipe 20 being crushed.

Moreover, the pair of first side walls 231 have an inclination angle Θ1 greater than 20° (approximately 30° in this embodiment) to form a V-shaped cross section, and the root 231a thereof is connected to the peak 21; A pair of second wall portions 232 has an inclination angle Θ2 greater than 20° (approximately 45° in this embodiment) to form a V-shaped cross section, and its base 232a has one peak 21 and two valleys 22. , the radial compressive strength can be further increased.

As described above, the holding protrusions 23 are set regardless of the groove width of the valley portion 22 . In other words, it is not necessary to forcibly widen the groove width of the valley portion 22 in order to widen the dimension of the holding projection 23 in the pipe axis direction. Therefore, the groove width of the valley portion 22 can be limited to a width that can prevent the corners of the structure from entering and being caught. However, the groove width of the valley portion 22 is set to 25% or more of one pitch P in order to ensure stretchability in the tube axial direction (to ensure compression allowance). In this embodiment, the groove width of the valley portion 22 is about 30% of one pitch P. As shown in FIG. As a result, the 200 mm corrugated cladding tube 20 can be easily shortened by 50 mm or more.

In order to prevent the corners of the structure from entering deep into the valley 22, the groove depth of the valley 22 is made larger than the groove width. Further, the depth of the concave portion of the holding protrusion 23, which forms a substantially quadrangular pyramid, is set to be greater than the groove width of the valley portion 22. As shown in FIG.

Here, for reference, specific dimensions of the composite pipe 1 of the above-described first embodiment are exemplified.
Outer diameter of peak 21 30.5 mm
Inner diameter of valley 22 25.5 mm
The outer diameter of the bottom (minimum diameter portion) of the valley portion 22 is 26.5 mm
The diameter of the inscribed circle of the holding protrusion 23 is 17.8 mm
The inner tube 10 made of a crosslinked polyethylene tube has an outer diameter of 17 mm.
The inner diameter (nominal diameter) of the inner tube 10 is 13 mm
Pitch P between peaks 21 and valleys 22 4.3 mm
Width of crest 21 3.0 mm
Width of valley 22 1.3 mm
R 0.5 mm of the groove tip of the valley portion 22 and the concave portion of the tip of the holding projection 23

Next, another embodiment of the present invention will be described. In these embodiments, components corresponding to those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.
<Second embodiment>
The tube axis dimension of the holding projection 23 of the second embodiment shown in FIG. 4 is longer than that of the first embodiment, and the holding projection 23 is formed so as to cross two peaks 21 and three valleys 22 in the tube axial direction. It is That is, the roots 232a of the pair of second side walls 232 are connected to the two peaks 21 and the three valleys 22, respectively. The roots 231a of the pair of first wall portions 231 are connected to the two peak portions 21 located on both sides of the two peak portions 21 and the three valley portions 22 in the pipe axis direction. The inclination angle Θ1 of the first side wall 231 of this embodiment is about 45°.

In the second embodiment, the tube axial dimension of the holding protrusions 23 is made longer than in the first embodiment, and the inclination angle Θ1 of the first side wall 231 is increased, thereby further increasing the strength of the corrugated cladding tube 20 against the radial compressive load. be able to.

<Third Embodiment>
In the third embodiment shown in FIG. 5, the shape of the tip 230 of the holding projection 23 when viewed from the tube axial direction draws an arc (concave curve) corresponding to the inner tube 10, so that the inner tube 10 can be held more stably. can be done. Further, when a compressive load is applied from the radially outer side, the tip 230 of the holding projection 23 contacts the outer circumference of the inner tube 10 without slipping, so that the strength against the compressive load can be increased.

The present invention is not limited to the above embodiments, and various forms can be adopted without departing from the scope of the invention. For example, the four circumferentially separated holding projections in the above-described embodiment may be shifted in the pipe axial direction.

The present invention can be applied, for example, to water supply pipes.

1 composite tube 10 inner tube 20 cladding tube 21 crest 22 trough 23 holding protrusion 231 first side wall 231a first side wall base 232 second side wall 232a second side wall base P pitch L dimension of the holding protrusion in the tube axis direction Θ1 Inclination angle Θ2 of the first side wall Inclination angle of the second side wall

Claims (11)

A corrugated cladding tube covering a flexible inner tube,
annular peaks and annular valleys alternately arranged in the tube axial direction;
holding projections dispersed in the tube axial direction and circumferential direction and arranged independently of each other, protruding radially inward from the valley portion, and holding the inner tube substantially concentrically with the tube axis by their tips;
with
A corrugated cladding tube, wherein the axial dimension of the holding protrusions is longer than one pitch including one peak and one valley. 2. The corrugated cladding tube according to claim 1, wherein said retaining projection is formed across at least one trough or at least one peak in the tube axial direction. 3. The corrugated cladding tube according to claim 2, wherein said holding protrusions are formed so as to traverse one crest and two troughs in the pipe axial direction. 3. The corrugated cladding tube according to claim 2, wherein said holding protrusions are formed so as to traverse two crests and three troughs in the tube axial direction. It has a pair of first side walls facing each other in the axial direction of the holding protrusions and a pair of second side walls facing each other in the circumferential direction,
5. The pair of first side walls according to any one of claims 2 to 4, wherein the roots of the pair of first side walls are connected to the ridges, and the pair of second side walls are connected to the troughs and ridges crossed by the holding projections. A corrugated cladding tube according to claim 1. The pair of first side walls are inclined toward each other in the radial direction, and each of the first side walls has an inclination angle of more than 20° with respect to a plane orthogonal to the tube axis. The corrugated cladding tube according to claim 5, characterized in that: 7. The corrugated cladding tube according to claim 5, wherein a cross section of said holding protrusion along the tube axis direction is V-shaped by said pair of first side walls. The pair of second side walls are inclined radially inward toward each other, and each of the second side walls has an inclination angle of more than 20° with respect to a plane passing through the tube axis. The corrugated cladding tube according to any one of claims 5 to 7, characterized by: 9. The corrugated cladding tube according to claim 8, wherein the tip of said holding projection forms a concave curve when viewed from the tube axial direction. The ridges have a short cylindrical shape, the groove width of the troughs is 25% or more of the one pitch, and the recess depth of the holding projection is larger than the groove width of the troughs. Item 10. The corrugated cladding tube according to any one of items 1 to 9. A composite tube comprising a flexible inner tube and the corrugated coated tube according to any one of claims 1 to 10 covering the inner tube.

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