JP6960662B2 - Flexible synthetic resin pipe - Google Patents

Description

The present invention relates to a flexible synthetic resin pipe formed by spirally winding a reinforcing ridge around an outer peripheral surface of a pipe mainly made of a soft synthetic resin.

Conventionally, as a flexible pressure-resistant synthetic resin tube, for example, those having the structures described in Patent Document 1 and Patent Document 2 are widely known, and specifically, as shown in FIG. , A reinforcing ridge 12 made of hard synthetic resin having a quadrangular cross section is spirally formed at a constant pitch on the outer peripheral surface of a pipe main body 11 made of soft synthetic resin whose inner peripheral surface is formed as a flat surface over the entire length. It has a structure that is wound in a shape.

Further, in Patent Document 3, a reinforcing ridge having a circular cross section is spirally wound around the outer peripheral surface of a tubular body made of a soft synthetic resin with a part thereof embedded in the tubular body. A wear-resistant composite hose having a rubber layer layered on the inner peripheral surface of the pipe body is described.

Japanese Unexamined Patent Publication No. 2003-214563 Japanese Unexamined Patent Publication No. 2008-281167 Japanese Unexamined Patent Publication No. 9-222183

When the flexible synthetic resin pipe described in Patent Documents 1 and 2 is curved (bent) as shown in FIG. 9, the outer peripheral wall portion 11-1 of the pipe main body 11 that is curved in a convex arc shape is formed. , A tensile force is generated in the direction in which the adjacent reinforcing ridges 12a and 12a in the reinforcing ridge 12 spirally wound around the outer peripheral surface of the pipe main body 11 are to be separated from each other, and the inside is curved in a concave arc shape. A compressive force is generated in the peripheral wall portion 11-2 in the direction in which the adjacent reinforcing ridge portions 12a and 12a are attracted to each other.

Further, the corner portion c formed by the base end of the reinforcing ridge 12 fixed to the outer peripheral surface of the pipe main body 11 and the outer peripheral surface of the pipe wall portion 11a of the pipe main body 11 connected to the base end is a pipe main body. When the 11 is curved, in the outer peripheral wall portion 11-1 of the pipe main body 11 that is curved in a convex arc shape, the bending stress that tries to separate the reinforcing ridge 12 from the outer peripheral surface of the pipe main body 11 together with the above tensile force. If they act intensively and are repeatedly curved, cracks may occur between the outer peripheral surface of the pipe main body 11 and the base end of the reinforcing ridge 12, and the resistance to bending also increases. There is a point.

On the other hand, in the inner peripheral wall portion 11-2 of the pipe main body 11 curved in a concave arc shape, the space between the adjacent reinforcing ridges 12a and 12a is narrowed by the compressive force, and the pipe between these reinforcing ridges 12a and 12a is narrowed. The pipe wall portion 11a of the main body 11 is curved and deformed so as to slacken between the reinforcing ridge portions 12a and 12a with the base end corner portions 12a1 and 12a1 of the adjacent reinforcing ridge portions 12a and 12a as fulcrums. At this time, the stress due to the curvature of the pipe wall portion 11a is concentrated on the base end corner portion of the reinforcing ridge portion 12a, and the bending resistance increases and the bending rigidity of the pipe main body 11 increases as described above. , There is a problem that it becomes difficult to bend.

As described in Patent Document 3, a reinforcing ridge having a circular cross section is embedded in the outer peripheral surface of a tubular body made of a soft synthetic resin, and a part of the reinforcing ridge is embedded in the tubular body. Even in a hose that is spirally wound in a state, or a reinforcing ridge made of a hard synthetic resin having a semicircular cross section or a stalk-like cross section is spirally wound around the outer peripheral surface of a pipe mainly made of a soft synthetic resin. This will occur in the same way as described above in the synthetic resin pipe.

The present invention has been made in view of such problems, and an object of the present invention is that when a tube main body made of a soft synthetic resin is curved, it is spirally wound around the outer peripheral surface of the tube main body. It is an object of the present invention to provide a flexible synthetic resin pipe which can prevent the stress from acting intensively on the base end portion of the reinforcing ridge and has excellent durability and flexibility.

In order to achieve the above object, the flexible synthetic resin pipe of the present invention has, as described in claim 1, the outer circumference of the pipe main body made of a soft synthetic resin having an inner peripheral surface formed as a flat surface. In a flexible synthetic resin pipe in which reinforcing ridges made of hard synthetic resin are spirally wound around the surface at a constant pitch, the pipe wall mainly composed of the pipe has an inner layer wall portion and an outer layer having a constant thickness. In the pipe wall portion which is composed of a wall portion and is in contact with the inner peripheral surface of the reinforcing ridge, the inner layer wall portion and the outer layer wall portion are integrally superposed, and the outer peripheral surface of the outer layer wall portion is inside the reinforcing ridge. While fixed to the peripheral surface, the pipe wall portion between the reinforcing ridges adjacent to the pipe main body in the length direction in the reinforcing ridge separates the outer layer wall portion from the inner layer wall portion and is adjacent to the reinforcing ridge. It is characterized in that it is formed on a curved outer layer wall portion that is curved outward in a convex arc shape with the base end corner portions of the portions as fulcrum portions at both ends.

Further, in the invention according to claim 2, a reinforcing ridge made of a hard synthetic resin is spirally formed on the outer peripheral surface of a pipe main body made of a soft synthetic resin having an inner peripheral surface formed as a flat surface at a constant pitch. In a flexible synthetic resin pipe made by winding, the pipe wall mainly composed of the pipe is composed of an inner layer wall portion and an outer layer wall portion having a certain thickness, and the pipe wall portion in contact with the inner peripheral surface of the reinforcing ridge. Is an integral layer of the inner layer wall portion and the outer layer wall portion, and the outer peripheral surface of the outer layer wall portion is fixed to the inner peripheral surface of the reinforcing ridge, while the length direction of the pipe main body in the reinforcing ridge. In the pipe wall portion between the reinforcing ridges adjacent to the pipe wall portion, one half and the other half of the outer layer wall portion are separated outward from the inner layer wall portion of the pipe wall portion, and in the one half portion of the outer layer wall portion. , One end of which is connected to the base end of one of the reinforcing ridges, and the other end is formed in a convex arcuate curved outer layer wall part which is connected to the outer peripheral surface of the middle part of the inner layer wall part, and the other half part. Is characterized in that one end thereof is connected to the outer peripheral surface of the intermediate portion of the inner layer wall portion, and the other end is connected to the base end of the other reinforcing ridge portion to form an arc-shaped curved outer layer wall portion. And.

In the flexible synthetic resin pipe according to claims 1 and 2, the invention according to claim 3 is a reinforcing protrusion spirally wound around the outer peripheral surface of the main body of the pipe. The strip is characterized in that it is formed in a quadrangular cross section.

According to the invention of claim 1, since the inner peripheral surface of the pipe body made of soft synthetic resin is formed as a flat surface, fluids such as water can flow smoothly and dust is formed on the inner peripheral surface. Of course, it is possible to prevent the pipe main body from staying and adhering, and the pressure resistant strength is given by the reinforcing ridge made of hard synthetic resin spirally wound around the outer peripheral surface of the pipe main body. It can be curved without being deformed into a flat shape and without causing buckling or the like.

Further, when the flexible synthetic resin pipe configured as described above is curved, in the outer peripheral wall portion of the pipe main body which is curved in a convex arc shape, the reinforcing ridge portions adjacent to the pipe wall portion are mutually formed. A tensile force acts in the direction of pulling away, and the reinforcing ridges are separated from the outer peripheral surface of the pipe main body at the corners formed by the base end of the reinforcing ridge portion and the pipe wall portion connected to the base end. However, the bending stress is applied, but the outer layer wall of the pipe wall between the reinforcing ridges is connected to the outer peripheral surface of the pipe main body in the adjacent reinforcing ridge, and the base end is used as the fulcrum at both ends of the pipe wall. Since it is formed on the convex arcuate curved outer layer wall portion separated from the inner layer wall portion outward, the bending stress acting on the corner portion is applied to both ends of the curved outer layer wall portion and both ends of the inner layer wall portion. It is possible to absorb a part of the stress acting on the corner portion while deforming the curved outer layer wall portion on which the largest tensile force acts in the tension direction.

Therefore, the stress acting in the direction of peeling the reinforcing ridge portion from the outer peripheral surface of the pipe main body can be reduced, and the boundary between the outer peripheral surface of the pipe main body and the base end corner portion of the reinforcing ridge portion is stressed. It is possible to prevent breakage and reduce the rigidity of the main body of the pipe, and the flexibility and durability are improved compared to synthetic resin pipes of the same size and shape, which have the same flexibility in the thickness of the pipe wall. Can be improved.

Further, in the inner peripheral wall portion of the pipe main body which is curved in a concave arc shape when the flexible synthetic resin pipe is bent, the pipe wall portion between the reinforcing ridges adjacent to each other in the length direction of the pipe main body. A compressive force is generated to narrow the pressure, and the bending stress acting on the pipe wall that is connected to the base end corner of the reinforcing ridge is applied to the curved outer layer wall as described above. The curved outer layer wall portion that can be dispersed between both end fulcrums and both ends of the inner layer wall portion connected to the both end fulcrums and exerts the largest compressive force is a reinforcing ridge adjacent to the inner layer wall portion. It is possible to absorb the compressive force while bending it further toward the section.

Therefore, even in the inner peripheral wall portion of the pipe main body that bends in a concave arc shape, the rigidity of the pipe wall can be reduced, and the flexibility and durability can be improved.

According to the invention of claim 2, a reinforcing ridge made of a hard synthetic resin is provided at a constant pitch on the outer peripheral surface of a pipe main body made of a soft synthetic resin having an inner peripheral surface formed as a flat surface over the entire length. Since it is wound in a spiral shape, a fluid such as water can be smoothly circulated and the outer peripheral surface of the main body of the pipe is covered with the same flexible synthetic resin pipe as described in claim 1. Pressure resistance can be imparted by a reinforcing ridge made of a hard synthetic resin wound in a spiral shape.

Further, in the synthetic resin pipe according to claim 2, a half portion in the length direction of the pipe main body and the other in the outer layer wall portion of the pipe wall portion between the reinforcing ridges adjacent to each other in the length direction of the pipe main body. A pair of half parts separated from the inner layer wall part of the pipe wall part to the outside, and both ends connected to the middle part of the inner layer wall part of the pipe wall part and the base end of the adjacent reinforcing ridge part. Since it is formed on the curved outer layer wall portion having a convex arc shape, when the pipe main body is bent, the base end of the reinforcing ridge portion and the pipe wall portion are formed in the same manner as the synthetic resin pipe according to claim 1 above. The bending stress acting on the corners, which are the joints of the pipe wall, is applied to the ends of the curved outer layer wall that is connected to the base end of the reinforcing ridge, and both ends of the pipe wall inner wall that is connected to this end. The curved outer layer wall portion provided on the convex arcuate curved outer peripheral wall portion side of the pipe main body, on which the largest tensile force acts when the pipe main body is bent, is deformed in a tensioning direction. It is possible to absorb a part of the bending stress acting on the corners while allowing the pipes to be absorbed.

Therefore, the bending stress acting in the direction of peeling the reinforcing ridge portion from the outer peripheral surface of the pipe main body can be reduced, and the boundary between the outer peripheral surface of the pipe main body and the base end corner portion of the reinforcing ridge portion can be reduced. It is possible to prevent breakage due to stress and improve flexibility and durability.

Further, when the pipe main body is curved, in the inner peripheral wall portion of the pipe main body which is curved in a concave arc shape, the pipe wall portion between the reinforcing ridges adjacent to each other in the length direction of the pipe main body is narrowed. A compressive force is generated, and the bending stress acting on the pipe wall portion connected to the base end portion of the reinforcing ridge portion by this compressive force is connected to the base end of the reinforcing ridge portion as described above. The curved outer layer wall portion that can be dispersed between the end portion of the curved outer layer wall portion and the end portion of the pipe wall inner layer wall portion connected to this end portion, and the maximum compressive force acts on the curved outer layer wall portion from the inner layer wall portion. It is also possible to absorb the compressive force while bending toward the adjacent reinforcing ridges.

Therefore, the rigidity of the pipe wall can be reduced even in the inner peripheral wall portion of the pipe main body that bends in a concave arc shape, and the flexibility and durability of the entire pipe can be further improved.

According to the invention of claim 3, since the reinforcing ridge spirally wound around the outer peripheral surface of the pipe main body is formed in a rectangular cross section, the reinforcing ridge is joined to the outer peripheral surface of the pipe main body. It is possible to provide a synthetic resin pipe having an area larger than that of a reinforcing ridge having a circular or elliptical cross section and having the reinforcing ridge firmly integrated with the outer peripheral surface of the pipe main body by fusion or the like.

A side view of a part of the synthetic resin pipe of the present invention in cross section. An enlarged vertical side view of a part of it. Longitudinal side view in a bent state. An enlarged vertical side view of a part of it. A partial longitudinal side view showing another embodiment of the synthetic resin pipe of the present invention. A vertical sectional side view of a part of the bent state. An enlarged vertical side view of a part of it. Longitudinal side view of a conventional synthetic resin pipe. Longitudinal side view in a bent state.

Next, a specific embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, the flexible synthetic resin tube P has an inner peripheral surface as a flat surface having a constant diameter over the entire length. A reinforcing ridge 2 having a constant width and a constant thickness made of a hard synthetic resin is spirally wound around the outer peripheral surface of the pipe main body 1 made of the soft synthetic resin formed in the above at a constant pitch. Therefore, the reinforcing ridge 2 is formed so as to be bendable through the pipe wall portion between the reinforcing ridges 2a and 2a adjacent to each other in the length direction of the pipe main body 1, and the pressure resistant strength is imparted by the reinforcing ridge 2. doing.

The tube main body 1 is made of a soft synthetic resin such as a soft vinyl chloride resin or a soft polyethylene resin, and the reinforcing ridge 2 is made of a hard synthetic resin such as a hard vinyl chloride resin or a hard polyethylene resin. When the main body 1 and the reinforcing ridge 2 are made of the same resin, for example, the pipe main body 1 is made of a soft vinyl chloride resin, the reinforcing ridge 2 is made of a hard vinyl chloride resin. Further, the reinforcing ridge 2 is fixed by fusing the inner peripheral surface (bottom surface) in close contact with the outer peripheral surface of the pipe main body 1 to the outer peripheral surface of the pipe main body 1.

The pipe wall of the pipe main body 1 is composed of an inner layer wall portion 1a having a constant thickness and an outer layer wall portion 1b having a constant thickness, and the pipe wall portion 1-1 in contact with the inner peripheral surface of the reinforcing ridge 2 is the inner layer. The wall portion 1a and the outer layer wall portion 1b are integrally polymerized and fused, and the outer peripheral surface of the outer layer wall portion 1b is fixed to the inner peripheral surface of the reinforcing ridge 2.

On the other hand, the pipe wall portion 1-2 between the reinforcing ridge portions 2a and 2a adjacent to the pipe main body 1 in the reinforcing ridge 2 in the length direction has the outer layer wall portion 1b of the reinforcing ridge portions 2a and 2a. It is formed in a curved outer layer wall portion 1b'separated from the inner layer wall portion 1a toward the outside in a convex arc shape with the opposite base end corners as fulcrums at both ends. The curved outer layer wall portion 1b'exposes its outer peripheral surface to the outside from between the base ends of the adjacent reinforcing ridge portions 2a and 2a, and is spirally continuous in the length direction of the pipe main body 1. , A crescent-shaped space 5 spirally continuous in the length direction of the pipe main body 1 between the inner peripheral surface of the curved outer layer wall portion 1b'and the outer peripheral surface of the inner layer wall portion 1a facing the inner peripheral surface. Is formed.

The thickness of the curved outer layer wall portion 1b'in the pipe wall portion 1a is formed to be equal to or less than the thickness of the inner layer wall portion 1a.

When the synthetic resin pipe P configured as described above is curved as shown in FIGS. 3 and 4, the length direction of the pipe main body 1 is on the outer peripheral wall portion P-1 side of the pipe P which is curved in a convex arc shape. A tensile force acts on the pipe wall portion 1-2 between the reinforcing ridges 2a and 2a adjacent to the reinforcing ridges 2a and 2a in the direction in which the opposing reinforcing ridges 2a and 2a are separated from each other, and the reinforcing ridges 2a, Reinforcing ridges 2a are provided in the pipe main body 1 at the corner c formed by the base ends of the opposite side surfaces 2a1 and 2a1 of 2a and the outer peripheral surface of the end of the pipe wall portion 1-2 connected to the base ends. Bending stress that tries to peel off from the outer peripheral surface acts.

At this time, the pipe wall portion 1-2 between the adjacent reinforcing ridge portions 2a and 2a has the inner layer wall portion 1a having a constant thickness and the opposing side surfaces 2a 1 and 2a of the reinforcing ridge portions 2a and 2a whose both ends are adjacent to each other. It is connected to the base end of 2a1 and is composed of a curved outer layer wall portion 1b'curved in a convex arc shape by separating the connecting base end portions from the inner layer wall portion 1a outward with the fulcrum portions 3 and 3 at both ends. Therefore, the bending stress acting on the corner portion c is applied to both end fulcrums 3 and 3 of the curved outer layer wall portion 1b1'and both ends of the inner layer wall portion 1a connected to both end fulcrums 3 and 3 of the outer layer wall portion 1b. The curved outer layer wall portion 1b', which can be dispersed in the portion 4 and exerts the largest tensile force, is deformed in the direction of tension and absorbs a part of the bending stress acting on the corner portion c to be absorbed in the corner portion. It is possible to eliminate the concentration of bending stress on c, reduce the bending rigidity of the pipe main body 1, and provide a synthetic resin pipe having excellent flexibility and durability.

Further, when the flexible synthetic resin pipe P is bent, the reinforcing protrusion adjacent to the pipe main body 1 in the length direction on the inner peripheral wall portion P-2 side of the pipe P which is curved in a concave arc shape. A compressive force is generated to narrow the pipe wall portion 1-2 between the strips 2a and 2a, and the opposite side surfaces 2a1 of the reinforcing ridges 2a and 2a are generated.
, 2a1 and the outer peripheral surface of the end of the pipe wall portion 1-2 connected to the base end, the corner portion c has reinforcing ridges 2a, 2a at both ends of the pipe wall portion 1a. Bending stress is generated to try to bite into the corners of the.

At this time, as described above, the pipe wall portion 1-2 between the adjacent reinforcing ridge portions 2a and 2a faces the inner layer wall portion 1a and the reinforcing ridge portions 2a and 2a whose ends are adjacent to each other as described above. The curved outer layer wall portion 1b'which is connected to the base ends of the side surfaces 2a1 and 2a1 and is curved in a convex arc shape and separated outward from the inner layer wall portion 1a with the connecting base ends as fulcrums 3 and 3 at both ends. Therefore, the bending stress acting on the corner portion c is applied to both end fulcrums 3 and 3 of the curved outer layer wall portion 1b'and both end portions 4 of the inner layer wall portion 1a connected to both end fulcrum portions 3 and 3. It can be dispersed into 4 and 4.

Therefore, it is the most than the inner layer wall portion 1a that enters between the adjacent reinforcing ridge portions 2a and 2a with the portions connected to the fulcrums 3 and 3 at both ends of the curved outer layer wall portion 1b'as the fulcrum due to the compressive force. The curved outer layer wall portion 1b'on which a large compressive force acts is inserted between the adjacent reinforcing ridge portions 2a and 2a with the fulcrums 3 and 3 at both ends as fulcrums while being curved and deformed even more than the inner layer wall portion 1a. Therefore, it is possible to absorb a part of the bending stress acting on the corner portion c, eliminate the concentration of the bending stress on the corner portion c, and reduce the bending rigidity of the pipe main body 1. Therefore, it is possible to provide a synthetic resin tube P having excellent flexibility and durability.

FIG. 5 shows another embodiment of the synthetic resin pipe P of the present invention. In the above embodiment, the pipe wall portion 1 between the reinforcing ridge portions 2a and 2a adjacent to each other in the length direction of the pipe main body 1 -2 has a convex arc shape outward with the base ends of the reinforcing ridges 2a and 2a facing each other and the base ends of 2a1 as the fulcrums 3 and 3 at both ends with respect to the inner layer wall portion 1a. The structure is such that one curved outer layer wall portion 1b'is provided, but in this embodiment, the pipe wall portion 1-2 is provided on the inner layer wall portion 1a and the inner layer wall portion 1a. It is composed of a pair of curved outer layer walls 1b1'and 1b1'.

Specifically, a reinforcing ridge 2 made of a hard synthetic resin is spirally wound around the outer peripheral surface of a pipe main body 1 made of a soft synthetic resin whose inner peripheral surface is formed as a flat surface at a constant pitch. In the flexible synthetic resin pipe P, the pipe wall of the pipe main body 1 is composed of an inner layer wall portion 1a having a constant thickness and an outer layer wall portion 1b having a constant thickness, and is the inner circumference of the reinforcing ridge 2. In the pipe wall portion 1-1 in contact with the surface, the inner layer wall portion 1a and the outer layer wall portion 1b are integrally polymerized and fused, and the outer peripheral surface of the outer layer wall portion 1b is reinforced by the inner peripheral surface of the ridge 2. It is stuck to.

On the other hand, the pipe wall portion 1-2 between the reinforcing ridge portions 2a and 2a adjacent to the pipe main body 1 in the reinforcing ridge 2 in the length direction is a half in the length direction of the pipe main body 1 in the outer layer wall portion 1b. The portion and the other half portion are separated outward from the inner layer wall portion 1a of the pipe wall portion 1-2, and are formed into curved outer layer wall portions 1b1'and 1b1', which are curved in a convex arc shape, respectively.

Specifically, on the one-half side of the outer layer wall portion 1b of the pipe wall portion 1-2, one end is connected to the base end of one reinforcing ridge portion 2a in the adjacent reinforcing ridge portions 2a and 2a 3a. , The other end is connected to the outer peripheral surface of the intermediate portion between the adjacent reinforcing ridges 2a and 2a in the inner layer wall portion 1a, and these connecting portions 3a and 3b are used as fulcrums with respect to the outer peripheral surface of the inner layer wall portion 1a. It is formed on the curved outer layer wall portion 1b1'that bulges outward in a convex arc shape, and on the other half side, one end is between the adjacent reinforcing ridges 2a and 2a in the inner layer wall portion 1a. 3b is connected to the outer peripheral surface of the middle portion of the above, and the other end is connected to the base end of the other reinforcing ridge 2a in the adjacent reinforcing ridges 2a and 2a. It is formed in a curved outer layer wall portion 1b1'that bulges outward in a convex arc shape with respect to the outer peripheral surface of the wall portion 1a2.

When the synthetic resin pipe P configured as described above is curved as shown in FIGS. 6 and 7, the length direction of the pipe main body 1 is on the outer peripheral wall portion P-1 side of the pipe P which is curved in a convex arc shape. A tensile force acts on the pipe wall portion 1-2 between the reinforcing ridges 2a and 2a adjacent to the reinforcing ridges 2a and 2a in the direction in which the opposing reinforcing ridges 2a and 2a are separated from each other, and the reinforcing ridges 2a, Reinforcing ridges 2a are provided in the pipe main body 1 at the corner c formed by the base ends of the opposite side surfaces 2a1 and 2a1 of 2a and the outer peripheral surface of the end of the pipe wall portion 1-2 connected to the base ends. Bending stress that tries to peel off from the outer peripheral surface acts.

At this time, one half and the other half of the pipe main body 1 in the outer layer wall portion 1b of the pipe wall portion 1-2 between the reinforcing ridges 2a and 2a adjacent to each other in the length direction of the pipe main body 1 Is curved in a pair of convex arcs with both ends connected to the intermediate portion of the inner layer wall portion 1a of the pipe wall portion 1-2 and the opposing base ends of the adjacent reinforcing ridge portions 2a and 2a, respectively, 3a and 3b. Since it is formed on the curved outer layer wall portions 1b1'and 1b1', the bending stress acting on the corner c which is the connecting portion between the base end of the reinforcing ridge portion 2a and the pipe wall portion 1-2 is reinforced. It can be dispersed between the ends of the curved outer layer wall portions 1b1'and 1b1' connected to the base end of the portion 2a and both ends of the inner layer wall portion 1a connected to this end, and the pipe main body 1 is bent. When the bending stress is applied, the curved outer layer wall portions 1b1'and 1b1', on which the largest tensile force acts, become tense and deform toward the outer peripheral surface of the inner layer wall portion 1a in a direction that reduces the degree of curvature. Can absorb part.

Further, when the pipe main body 1 is curved, the pipe between the reinforcing ridges 2a and 2a adjacent to the pipe main body 1 in the length direction on the inner peripheral wall portion P-2 side of the pipe P which is curved in a concave arc shape. A compressive force is generated in the direction of narrowing the wall portion 1-2, and this compressive force acts on the pipe wall portion 1-2 connected to the base end portion of the reinforcing ridge portion 2a. The connection between the curved outer layer wall portions 1b1'and 1b1' that are connected to the base end of the reinforcing ridge portion 2a and the inner layer wall portion 1a that is connected to the inner peripheral side of the connecting end portion 3a. The curved outer layer wall portions 1b1'and 1b1', which can be dispersed with the end portion 4a and exert the largest compressive force, are further larger than the inner layer wall portion 1a toward the adjacent reinforcing ridges 2a and 2a. It can absorb compressive force while bending.

Therefore, it is possible to suppress the concentration of bending stress in the corner portion c formed by the base end of the reinforcing ridge portion 2a and the pipe wall portion 1-2 connected to the base end, and the bending of the pipe main body 1. It is possible to provide a synthetic resin tube which can reduce the rigidity and has excellent flexibility and durability.

In each of the above embodiments, the reinforcing ridges 2 and 2'have a square cross section, but the reinforcing ridges made of hard synthetic resin having a circular or elliptical cross section are used. The present invention can be satisfied even if the synthetic resin pipe is spirally wound with the inner peripheral surface in close contact with the outer peripheral surface of the pipe, because the same action and effect as described above can be obtained. ..

1 Tube main body
1a Inner layer wall
1b outer layer wall
1b'Curved outer layer wall 2 Reinforcing ridge
2a Reinforcing ridges 3, 3 fulcrums at both ends 4, 4 joints at both ends

Claims (3)

It has the flexibility of spirally winding reinforcing ridges made of hard synthetic resin around the outer peripheral surface of a pipe mainly made of soft synthetic resin whose inner peripheral surface is formed as a flat surface at a constant pitch. In the synthetic resin pipe, the pipe wall mainly composed of the pipe is composed of an inner layer wall portion and an outer layer wall portion having a certain thickness, and the pipe wall portion in contact with the inner peripheral surface of the reinforcing ridge is the inner layer wall portion and the outer layer wall portion. Is integrally superposed and the outer peripheral surface of the outer layer wall portion is fixed to the inner peripheral surface of the reinforcing ridges, while between the reinforcing ridges adjacent to the pipe main body in the length direction in the reinforcing ridges. The pipe wall portion is formed into a curved outer layer wall portion in which the outer layer wall portion is separated from the inner layer wall portion and the base end corners of adjacent reinforcing ridges are used as fulcrums at both ends and curved outward in a convex arc shape. The curved outer layer wall portion is a flexible synthetic resin pipe whose outer peripheral surface is exposed to the outside from between the base ends of the adjacent reinforcing ridge portions. It has the flexibility of spirally winding reinforcing ridges made of hard synthetic resin around the outer peripheral surface of a tube mainly made of soft synthetic resin whose inner peripheral surface is formed as a flat surface at a constant pitch. In the synthetic resin pipe, the pipe wall mainly composed of the pipe is composed of an inner layer wall portion and an outer layer wall portion having a certain thickness, and the pipe wall portion in contact with the inner peripheral surface of the reinforcing ridge is the inner layer wall portion and the outer layer wall portion. Is integrally superposed and the outer peripheral surface of the outer layer wall portion is fixed to the inner peripheral surface of the reinforcing ridges, while between the reinforcing ridges adjacent to the pipe main body in the length direction in the reinforcing ridges. In the pipe wall portion, one half of the outer layer wall portion and the other half portion are separated outward from the inner layer wall portion of the pipe wall portion, and in one half portion of the outer layer wall portion, one end of the reinforcing ridge is reinforced. It is formed in a convex arcuate curved outer layer wall portion that is connected to the base end of the portion and the other end is connected to the outer peripheral surface of the intermediate portion of the inner layer wall portion. A flexible synthetic resin characterized in that it is formed in an arcuate curved outer layer wall portion which is connected to the outer peripheral surface of the middle portion of the portion and the other end is connected to the base end of the other reinforcing ridge portion. tube. The flexible synthetic resin pipe according to claim 1 or 2, wherein the reinforcing ridge spirally wound around the outer peripheral surface of the main body of the pipe is formed in a rectangular cross section. ..

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