JP2019027573A - Synthetic resin pipe having flexibility - Google Patents

Abstract

To provide a synthetic resin pipe having excellent durability and flexibility by preventing bending stress from concentrically acting on a basic end portion of a reinforcement projection spirally wound on an outer peripheral face of a pipe main body, in curving the pipe main body composed of a soft synthetic resin.SOLUTION: In a synthetic resin pipe obtained by spirally winding a reinforcement projection 2 composed of hard synthetic resin, to an outer peripheral face of a pipe main body 1 composed of soft synthetic resin, a pipe wall portion between adjacent reinforcement projecting portions 2a, 2a is composed of an inner layer wall portion 1a and a curved outer layer wall portion 1b' curved into the convex arc shape applying parts connected to the basic end portion of the adjacent reinforcement projecting portions 2a, 2a as both end fulcrum portions 3, 3, so that bending stress acting on the pipe main body 1 is disposed to both end fulcrum portions 3, 3 of the curved outer layer wall portion 1b' and both end portions of the inner layer wall portion 1a connected to an inner peripheral side of both end fulcrum portions 3, 3.SELECTED DRAWING: Figure 4

Description

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

  Conventionally, as the pressure-resistant synthetic resin resin tube having flexibility, for example, those having structures described in Patent Document 1 and Patent Document 2 are widely known. Specifically, as shown in FIG. The outer peripheral surface of the tube main body 11 made of a soft synthetic resin having an inner peripheral surface formed on a flat surface over the entire length is spiraled with a reinforcing protrusion 12 having a square cross section made of a hard synthetic resin at a constant pitch. It has a structure that is wound in a shape.

  In Patent Document 3, a reinforcing protrusion having a circular cross section is wound on the outer peripheral surface of a tube made of a soft synthetic resin in a spiral manner with a part of the reinforcing protrusion being embedded in the tube. A wear-resistant composite hose is described in which a rubber layer is deposited on the inner peripheral surface of a tubular body.

JP 2003-214563 A JP 2008-281167 A Japanese Patent Laid-Open No. 9-222183

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

  Further, a corner c formed by the base end of the reinforcing protrusion 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 has a pipe main body. In the outer peripheral wall portion 11-1 of the tube main body 11 that bends into a convex arc shape when the tube 11 is bent, the bending stress that causes the reinforcing protrusion 12 to peel from the outer peripheral surface of the tube main body 11 together with the tensile force described above. If intensively acts and bends repeatedly, there is a risk that cracks may occur between the outer peripheral surface of the tube main body 11 and the base end portion of the reinforcing protrusion 12, and the resistance to bending increases. There is a point.

  On the other hand, in the inner peripheral wall portion 11-2 of the tube main body 11 curved in a concave arc shape, the space between the adjacent reinforcing ridge portions 12a and 12a is narrowed by the compression force, and the tube between these reinforcing ridge portions 12a and 12a is narrowed. The pipe wall portion 11a of the main body 11 is bent and deformed so as to be slackened between the reinforcing ridge portions 12a and 12a with the proximal 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 bending of the tube wall portion 11a is concentratedly applied to the base end corner portion of the reinforcing protrusion 12a, and the bending resistance is increased and the bending rigidity of the tube main body 11 is increased as described above. There is a problem that it becomes difficult to bend.

  Such a problem is that, as described in Patent Literature 3, a reinforcing protrusion having a circular cross section is embedded in the outer peripheral surface of a tube made of a soft synthetic resin, and a part thereof is embedded in the tube. Even in a hose that is spirally wound in a state, a reinforcing protrusion made of a hard synthetic resin having a semicircular or bowl-shaped cross section is wound helically on the outer peripheral surface of a tube made of a soft synthetic resin. This also occurs in the synthetic resin tube.

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

  In order to achieve the above object, a flexible synthetic resin pipe according to the present invention is the outer circumference of a pipe main body made of a soft synthetic resin having a flat inner peripheral surface as defined in claim 1. A flexible synthetic resin pipe formed by winding a reinforcing ridge made of hard synthetic resin on a surface in a spiral shape with a constant pitch, wherein the tube wall of the pipe main body has an inner layer wall portion and an outer layer having a constant thickness The tube wall portion that is in contact with the inner peripheral surface of the reinforcing ridge is formed by integrally polymerizing the inner layer wall portion and the outer layer wall portion, and the outer peripheral surface of the outer layer wall portion is connected to the inner surface of the reinforcing ridge. The tube wall portion between the reinforcing ridge portions adjacent to the circumferential surface of the reinforcing ridge in the length direction of the tube main body is fixed to the peripheral surface, and the reinforcing ridge adjacent to the outer layer wall portion is separated from the inner layer wall portion. The base end corner of the part is formed on a curved outer layer wall curved in a convex arc shape toward the outside with both ends as fulcrum parts. And wherein the Rukoto.

  Further, in the invention according to claim 2, the reinforcing protrusion made of hard synthetic resin is spirally formed at a constant pitch on the outer peripheral surface of the tube main body made of soft synthetic resin, which has a flat inner peripheral surface. In the flexible synthetic resin pipe formed 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 is in contact with the inner peripheral surface of the reinforcing protrusion. The inner layer wall portion and the outer layer wall portion are integrally polymerized, and the outer peripheral surface of the outer layer wall portion is fixed to the inner peripheral surface of the reinforcing protrusion, while the length direction of the tube main body in the reinforcing protrusion is The pipe wall part between the reinforcing ridges adjacent to the outer wall part separates one half of the outer layer wall part and the other half part from the inner layer wall part of the pipe wall part. A convex circle having one end connected to the base end of one reinforcing protrusion and the other end connected to the outer peripheral surface of the intermediate portion of the inner layer wall portion. In the other half, one end is connected to the outer peripheral surface of the intermediate portion of the inner layer wall, and the other end is connected to the base end of the other reinforcing ridge. It forms in the circular-arc-shaped curved outer-layer wall part, It is characterized by the above-mentioned.

  The flexible synthetic resin pipe according to claim 1 or 2 configured as described above, wherein the invention according to claim 3 is a reinforcing protrusion spirally wound around the outer peripheral surface of the pipe main body. The strip is formed in a quadrangular cross section.

  According to the first aspect of the present invention, since the inner peripheral surface of the tube main body made of a soft synthetic resin is formed into a flat surface, fluid such as water can be circulated smoothly and dust can be found on the inner peripheral surface. It is possible to prevent stagnation and adhesion, etc., as well as pressure resistance is provided by a reinforcing protrusion made of a hard synthetic resin spirally wound around the outer peripheral surface of the pipe main body. It can be curved without deforming into a flat shape and without causing buckling.

  Further, when the flexible synthetic resin pipe configured as described above is curved, the outer peripheral wall part of the pipe main body that is curved in a convex arc shape has the reinforcing ridges adjacent to each other on the pipe wall part. At the corner formed by the base end of the reinforcing ridge and the tube wall connected to the base end, the reinforcing ridge will be peeled off from the outer peripheral surface of the pipe body. However, the outer wall of the tube wall between the reinforcing ridges is connected to the outer peripheral surface of the tube main body at the adjacent reinforcing ridge, and both ends of the tube wall are used as fulcrums. Since it is formed in the curved outer layer wall portion having a convex arc shape separated outward from the inner layer wall portion, 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. The curved outer layer wall portion where the greatest tensile force acts can be dispersed in While deforming in the direction of Zhang can absorb some of the stress acting on the corners.

  Accordingly, it is possible to reduce the stress acting in the direction in which the reinforcing ridge is peeled off from the outer peripheral surface of the pipe main body, and the boundary between the outer peripheral surface of the pipe main body and the base end corner of the reinforcing ridge is stress. Can be prevented from breaking, and the rigidity of the tube main body can be reduced, and the thickness and flexibility of the tube wall are the same as those of the same size and shape synthetic resin tube. Can be improved.

  Further, when the flexible synthetic resin tube is bent, the tube wall portion between the reinforcing protrusions adjacent in the length direction of the tube main body in the inner peripheral wall portion of the tube main body that curves in a concave arc shape. A compressive force is generated to reduce the bending stress acting on the tube wall portion connected to the base end corner portion of the reinforcing ridge portion due to the compressive force in the same manner as described above. The curved outer layer wall portion on which the greatest compressive force acts can be dispersed between the both end fulcrum portions and both end portions of the inner layer wall portion connected to the both end fulcrum portions. The compressive force can be absorbed while being further bent toward the part.

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

  According to the second aspect of the present invention, the reinforcing protrusions made of the hard synthetic resin are arranged at a constant pitch on the outer peripheral surface of the tube main body made of the soft synthetic resin having the inner peripheral surface formed into a flat surface over the entire length. Thus, since it is wound spirally, like the flexible synthetic resin pipe according to claim 1, fluid such as water can be circulated smoothly and on the outer peripheral surface of the pipe main body. The pressure-resistant strength can be imparted by a reinforcing protrusion made of a hard synthetic resin wound in a spiral shape.

  Furthermore, in the synthetic resin pipe described in claim 2 above, one half of the length direction of the pipe main body in the outer layer wall part of the pipe wall part between the reinforcing ridges adjacent in the length direction of the pipe main body and the like A pair of half portions are separated outwardly from the inner layer wall portion of the tube wall portion, and both end portions are respectively connected to an intermediate portion of the inner layer wall portion in the tube wall portion and a proximal end of the adjacent reinforcing ridge portion. Since the convex arc-shaped curved outer layer wall portion is formed, when the tube main body is bent, the base end of the reinforcing ridge portion and the tube wall portion are similar to the synthetic resin tube according to claim 1. The bending stress acting on the corner which is the connecting portion of the curved outer layer wall portion connected to the base end of the reinforcing ridge portion, and both end portions of the tube wall inner layer wall portion connected to this end portion, It is provided on the outer peripheral wall side curved in a convex arc shape of the tube main body where the greatest tensile force acts when the tube main body is bent. That while deforming in a direction to tension the curved outer wall portion can absorb a portion of the bending stress acting on the corners.

  Therefore, it is possible to reduce the bending stress acting in the direction in which the reinforcing ridge is peeled from the outer peripheral surface of the pipe main body, and the boundary between the outer peripheral surface of the pipe main body and the base end corner of the reinforcing ridge is formed. Breakage due to stress can be prevented and flexibility and durability can be improved.

  In addition, when the tube main body is bent, the tube wall portion between the reinforcing ridges adjacent in the length direction of the tube main body is narrowed in the inner peripheral wall portion of the pipe main body that is curved in a concave arc shape. As described above, the bending stress acting on the tube wall portion connected to the base end portion of the reinforcing ridge portion 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 tube wall inner layer wall portion that is connected to the end portion is more effective than the inner layer wall portion. In addition, it is possible to absorb the compressive force while bending the reinforcing protrusions between adjacent reinforcing protrusions.

  Accordingly, the rigidity of the tube wall can be reduced even in the inner peripheral wall portion of the tube main body bent in a concave arc shape, and the flexibility and durability of the entire tube can be further improved.

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

The side view which sectioned a part of synthetic resin pipe of the present invention. The enlarged vertical side view of the part. The longitudinal side view of the state bent. The enlarged vertical side view of the part. The one part vertical side view which shows the other Example of the synthetic resin pipe | tube of this invention. The longitudinal section side view of a part of the state bent. The enlarged vertical side view of the part. The longitudinal side view of the conventional synthetic resin pipe | tube. The longitudinal side view of the state bent.

  Next, a specific embodiment of the present invention will be described with reference to the drawings. In FIGS. 1 and 2, the synthetic resin pipe P having flexibility has a flat surface with a constant diameter over the entire inner circumferential surface. On the outer peripheral surface of the tube main body 1 made of a soft synthetic resin, a rectangular reinforcing rib 2 having a constant width and a constant thickness made of a hard synthetic resin is spirally wound at a constant pitch. It is formed so that it can be bent through the tube wall part between the reinforcing ribs 2a, 2a adjacent to the length of the pipe main body 1 in the reinforcing rib 2, and the reinforcing rib 2 provides pressure resistance strength. doing.

  The tube main body 1 is made of soft synthetic resin such as soft vinyl chloride resin or soft polyethylene resin, and the reinforcing protrusion 2 is made of hard synthetic resin such as hard vinyl chloride resin or hard polyethylene resin. When the main body 1 and the reinforcing protrusion 2 are made of the same resin, for example, when the pipe main body 1 is made of soft vinyl chloride resin, the reinforcing protrusion 2 is made of hard vinyl chloride resin. The reinforcing protrusion 2 is fixed by fusing an 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 tube wall of the tube main body 1 is composed of an inner layer wall portion 1a having a certain thickness and an outer layer wall portion 1b having a certain thickness, and the tube wall portion 1-1 in contact with the inner peripheral surface of the reinforcing protrusion 2 is the inner layer wall portion 1a. 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 protrusion 2.

  On the other hand, the pipe wall portion 1-2 between the reinforcing ridges 2a and 2a adjacent to the longitudinal direction of the pipe main body 1 in the reinforcing ridge 2 has its outer layer wall 1b connected to these reinforcing ridges 2a and 2a. Are formed in a curved outer layer wall portion 1b 'separated from the inner layer wall portion 1a in a convex arc shape outwardly with the opposite base end corner portions as both fulcrums. The curved outer layer wall portion 1b ′ has an outer peripheral surface exposed to the outside from between the proximal ends of the adjacent reinforcing protrusions 2a and 2a, and is continuous in a spiral shape 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 opposed to the inner peripheral surface, a crescent-shaped space portion 5 spirally continuous in the length direction of the pipe main body 1 is provided. Is formed.

  The thickness of the curved outer layer wall portion 1b ′ in the tube wall portion 1a is 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 curved in a convex arc shape. In the tube wall portion 1-2 between the reinforcing ridges 2a, 2a adjacent to each other, a tensile force acts in a direction to separate the opposing reinforcing ridges 2a, 2a from each other, and the reinforcing ridges 2a, Reinforcing ridges 2a are formed in the tube main body 1 at the corners 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 tube wall 1-2 connected to the base ends. Bending stress is applied to peel from the outer peripheral surface.

  At this time, the tube wall portion 1-2 between the adjacent reinforcing ridge portions 2a, 2a includes an inner layer wall portion 1a having a certain thickness, and opposite side surfaces 2a 1, 2a, 2b of the reinforcing ridge portions 2a, 2a adjacent to each other, It is connected to the base end of 2a1, and this connection base end part is formed as a both-end fulcrum part 3, 3 and is separated outward from the inner layer wall part 1a and curved outer layer wall part 1b 'curved in a convex arc shape. Therefore, the bending stress acting on the corner c is the both end fulcrum portions 3 and 3 of the curved outer layer wall portion 1b1 ′ and the both end fulcrum portions 3 and 3 of the outer layer wall portion 1b. The curved outer layer wall portion 1b 'to which the greatest tensile force acts can be dispersed in the portion 4, and a part of the bending stress acting on the corner portion c is absorbed while the curved outer layer wall portion 1b' is deformed in the tensioning direction. It is possible to eliminate the concentration of bending stress on c, to reduce the bending rigidity of the tube main body 1, and to achieve excellent flexibility and durability. A synthetic resin tube can be provided.

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

  At this time, as described above, the tube wall portion 1-2 between the adjacent reinforcing ridge portions 2a and 2a is opposite to the inner layer wall portion 1a and the reinforcing ridge portions 2a and 2a adjacent at both ends as described above. Curved outer layer wall portion 1b ′ curved in a convex arc shape which is connected to the base ends of the side surfaces 2a1 and 2a1 to be separated and outwardly separated from the inner layer wall portion 1a with the connecting base end portions as both fulcrum portions 3 and 3. Therefore, bending stress acting on the corner c is applied to both end fulcrum portions 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 the both end fulcrum portions 3 and 3. 4 can be dispersed.

  Accordingly, the inner wall portion 1a that is bent and deformed between the reinforcing ridges 2a, 2a adjacent to each other by using the portion connected to the both end fulcrum portions 3, 3 of the curved outer layer wall portion 1b 'by the compressive force is more The curved outer layer wall portion 1b 'on which a large compressive force is applied is inserted between the reinforcing ridges 2a and 2a adjacent to each other with the both end fulcrum portions 3 and 3 as fulcrums while being further curved and deformed than the inner layer wall portion 1a. Thus, a part of the bending stress acting on the corner c can be absorbed, the bending stress can be prevented from concentrating on the corner c, and the bending rigidity of the tube main body 1 can be reduced. Thus, the synthetic resin pipe P having excellent flexibility and durability can be provided.

  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 in the length direction of the pipe main body 1 is shown. -2 is an outwardly convex arc shape with the base end portions of the opposing side faces 2a1 and 2a1 of the reinforcing protrusions 2a and 2a adjacent to the inner layer wall 1a at both ends adjacent to each other, as both fulcrum portions 3 and 3 However, in this embodiment, the tube wall portion 1-2 is provided on the inner layer wall portion 1a and the inner layer wall portion 1a. A pair of curved outer layer wall portions 1b1 ′ and 1b1 ′ is formed.

  Specifically, a reinforcing protrusion 2 made of hard synthetic resin is spirally wound at a constant pitch on the outer peripheral surface of a tube main body 1 made of a soft synthetic resin having a flat inner surface. In the synthetic resin pipe P having flexibility, 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. The inner wall 1a and the outer wall 1b are integrally superposed and fused on the pipe wall 1-1 in contact with the surface, and the outer wall of the outer wall 1b is connected to the inner wall of the reinforcing protrusion 2. It is stuck to.

  On the other hand, the pipe wall portion 1-2 between the reinforcing ridges 2a and 2a adjacent in the length direction of the pipe main body 1 in the reinforcing ridge 2 is half of the length direction of the pipe main body 1 in the outer layer wall portion 1b. The first and second halves are separated outward from the inner layer wall 1a of the tube wall 1-2, and formed into curved outer layer walls 1b1 ′ and 1b1 ′ that are curved in a convex arc shape, respectively.

  Specifically, on one half of the outer wall portion 1b of the pipe wall portion 1-2, one end is connected to the proximal end of one reinforcing ridge portion 2a in the adjacent reinforcing ridge portions 2a, 2a 3a. The other end is connected 3b to the outer peripheral surface of the intermediate portion between the adjacent reinforcing protrusions 2a, 2a in the inner layer wall portion 1a, and these connecting portions 3a, 3b are used as fulcrums to the outer peripheral surface of the inner layer wall portion 1a. Is formed on the curved outer layer wall portion 1b1 'bulging outward in a convex arc shape, and on the other half side, one end is between the adjacent reinforcing ridge portions 2a, 2a in the inner layer wall portion 1a. 3b is connected to the outer peripheral surface of the intermediate portion of the other, and the other end is connected to the proximal end of the other reinforcing ridge 2a in the adjacent reinforcing ridge 2a, 2a, and the inner layer with these connecting portions 3a, 3b as fulcrums. 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 curved in a convex arc shape. In the tube wall portion 1-2 between the reinforcing ridges 2a, 2a adjacent to each other, a tensile force acts in a direction to separate the opposing reinforcing ridges 2a, 2a from each other, and the reinforcing ridges 2a, Reinforcing ridges 2a are formed in the tube main body 1 at the corners 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 tube wall 1-2 connected to the base ends. Bending stress is applied to peel from the outer peripheral surface.

  At this time, one half and the other half of the pipe main body 1 in the length direction in the outer wall 1b of the pipe wall 1-2 between the reinforcing protrusions 2a and 2a adjacent to each other in the length direction of the pipe main 1 Are bent into a pair of convex arcs with both ends connected to the intermediate portion of the inner layer wall portion 1a in the tube wall portion 1-2 and the adjacent proximal ends of the reinforcing ridge portions 2a, 2a, respectively. Since the curved outer layer wall portions 1b1 ′ and 1b1 ′ are formed, the bending stress acting on the corner portion c which is the connecting portion between the proximal end of the reinforcing protrusion portion 2a and the tube wall portion 1-2 is reinforced. It is possible to disperse the curved outer layer wall portions 1b1 'and 1b1' connected to the base end of the portion 2a and the both end portions of the inner layer wall portion 1a connected to this end portion, so that the tube main body 1 is bent. The bending outer layer wall portions 1b1 ′ and 1b1 ′ to which the largest tensile force acts when deformed are deformed in a direction to reduce the degree of curvature toward the outer peripheral surface of the inner layer wall portion 1a, and the bending stress is increased. Absorb some Door can be.

  Further, when the pipe main body 1 is bent, the pipe between the reinforcing protrusions 2a and 2a adjacent to the pipe main body 1 in the length direction is provided on the inner peripheral wall portion P-2 side of the pipe P curved in a concave arc shape. A compressive force is generated in a direction to narrow the wall portion 1-2, and the bending force acting on the tube wall portion 1-2 connected to the base end portion of the reinforcing ridge portion 2a is generated by the compressive force. Connection of the curved outer layer wall portions 1b1 'and 1b1' connected to the base end of the reinforcing protrusion 2a and the inner layer wall portion 1a connected to the inner peripheral side of the connecting end portion 3a. The curved outer layer wall portions 1b1 'and 1b1', which can be distributed to the end portion 4a and have the greatest compressive force, are located between the reinforcing ridge portions 2a and 2a that are adjacent to each other and larger than the inner layer wall portion 1a. The compressive force can be absorbed while being bent.

  Therefore, it is possible to suppress the bending stress from concentrating on the corner c formed by the base end of the reinforcing protrusion 2a and the tube wall portion 1-2 connected to the base end, and the bending of the pipe main body 1 can be suppressed. Rigidity can be reduced, and a synthetic resin tube excellent in flexibility and durability can be provided.

  In each of the above embodiments, the reinforcing ridges 2 and 2 'have a rectangular cross section, but the reinforcing ridges made of a hard synthetic resin having a circular or elliptical cross section are used. Even a synthetic resin tube that is spirally wound in a state in which the inner peripheral surface thereof is in close contact with the outer peripheral surface of the tube can exhibit the same effects as described above, so that the present invention can be satisfied. .

1 Pipe main
1a Inner wall
1b Outer wall
1b 'Curved outer layer wall 2 Reinforcing ridge
2a Reinforcing ridge 3, 3 Both-end fulcrum 4, 4 Joints at both ends

Claims (3)

  It has the flexibility that a reinforcing protrusion made of a hard synthetic resin is spirally wound at a constant pitch on the outer peripheral surface of a tube main body made of a soft synthetic resin having a flat inner surface. In the synthetic resin pipe, the tube wall mainly composed of the pipe includes an inner layer wall portion and an outer layer wall portion having a constant thickness, and the tube wall portion in contact with the inner peripheral surface of the reinforcing protrusion is the inner layer wall portion and the outer layer wall portion. Are integrally polymerized and the outer peripheral surface of the outer layer wall portion is fixed to the inner peripheral surface of the reinforcing ridge, while the reinforcing ridge between the reinforcing ridges adjacent to each other in the longitudinal direction of the pipe main body. The tube wall portion is formed on a curved outer layer wall portion that is curved in a convex arc shape outwardly with the base end corner portion of the adjacent reinforcing ridge portion as both end fulcrum portions by separating the outer layer wall portion from the inner layer wall portion. A flexible synthetic resin tube characterized by being made.   It has the flexibility that a reinforcing protrusion made of a hard synthetic resin is spirally wound at a constant pitch on the outer peripheral surface of a tube main body made of a soft synthetic resin having a flat inner surface. In the synthetic resin pipe, the tube wall mainly composed of the pipe includes an inner layer wall portion and an outer layer wall portion having a constant thickness, and the tube wall portion in contact with the inner peripheral surface of the reinforcing protrusion is the inner layer wall portion and the outer layer wall portion. Are integrally polymerized and the outer peripheral surface of the outer layer wall portion is fixed to the inner peripheral surface of the reinforcing ridge, while the reinforcing ridge between the reinforcing ridges adjacent to each other in the longitudinal direction of the pipe main body. The pipe wall part separates one half of the outer layer wall part and the other half part from the inner layer wall part of the pipe wall part, and one half of the outer layer wall part has one end of one reinforcing protrusion. A convex arc-shaped curved outer layer wall part connected to the base end of the part and the other end connected to the outer peripheral surface of the intermediate part of the inner layer wall part. In the other half, one end is connected to the outer peripheral surface of the intermediate portion of the inner layer wall portion, and the other end is formed in an arc-shaped curved outer layer wall portion connected to the base end of the other reinforcing protrusion. A flexible synthetic resin tube characterized by having   The flexible synthetic resin pipe according to claim 1 or 2, wherein the reinforcing protrusion spirally wound around the outer peripheral surface of the pipe main body is formed in a quadrangular cross section. .

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