Profiled pipe

Abstract

To provide a deformed pipe made of FRP in which a fiber member is embedded in a resin molded body, the fiber member is arranged in high density with little deviation, and homogeneity of physical properties is high over the longitudinal direction of the deformed pipe, and to provide a method for manufacturing the deformed pipe.SOLUTION: A deformed pipe 1 made of FRP in which a braided sleeve for an outer layer is embedded inside a resin molded body has a normal part 2 having a predetermined cross-sectional peripheral length and a deformed part 3 having a cross-sectional peripheral length longer than the cross-sectional peripheral length of the normal part 2. The braided sleeve for the outer layer is formed by combining braids oriented at an orientation angle in a range of ± 5 to 85 ° with respect to the central axis direction of the deformed pipe 1, and an orientation angle θ 2 of the braid in the deformed part 3 satisfies a relationship of the following expression with respect to an orientation angle θ 1 of the braid in the normal part 2.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a deformed pipe made of FRP in which a fiber member is embedded inside a resin molded body. [Background technology]

[0002] BACKGROUND ART Conventionally, aluminum structures have been used for structures such as golf shafts, tennis rackets, fishing rods, bicycle frames, automobile parts, power transmission shafts, and roofs because of their light weight and high rigidity. However, although aluminum is light among metals, when it is used in the above-mentioned structures, even lighter weight may be required.

[0003] In recent years, fiber-reinforced plastic (FRP) pipes (hollow tubular structures) with fiber components embedded inside a resin molded body have been widely used in components that require light weight and high rigidity, such as the structures mentioned above. Recently, they have also been used in structures such as main body frames, propellers, propeller guards, arms, and skids (legs) for next-generation mobility, such as large drones (large unmanned aerial vehicles) and flying cars.

[0004] In this regard, Patent Documents 1 to 6 disclose pipes (hollow molded bodies) made of FRP that contain fiber members as their constituent elements. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-327910 [Patent Document 2] Japanese Patent Application Publication No. 3-161326 [Patent Document 3] Japanese Patent Application Publication No. 5-278128 [Patent Document 4] Japanese Patent Application Laid-Open No. 2015-200050 [Patent Document 5] Japanese Patent Publication No. 62-250258 [Patent Document 6] Patent Publication No. 2021-138120 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] When the FRP pipes (hollow molded bodies) are used in the above structures, irregularly shaped pipes may be used depending on the application and structure. An irregularly shaped pipe is a series of hollow molded bodies that do not have a uniform cross-sectional shape or cross-sectional dimensions, but include multiple sections with different cross-sectional shapes and cross-sectional dimensions. By including sections with different cross-sectional shapes and cross-sectional dimensions, the cross-sectional circumference or cross-sectional shape is not uniform but changes throughout the entire hollow molded body.

[0007] When forming such FRP shaped pipes, it is necessary to obtain uniform strength (no bias in strength) throughout the entire pipe, including areas where the cross-sectional shape and dimensions of the pipe are different. One way to achieve this is to uniformly dispose the fiber members embedded inside the resin molded body of the FRP shaped pipe throughout the entire pipe.

[0008] In this regard, in order to distribute the fibrous material uniformly throughout the entire shaped pipe, it is preferable to select a fibrous material that can be distributed seamlessly (without seams) throughout the entire shaped pipe in an integrated manner (as a series of fibrous structures). However, in hollow molded bodies with different cross-sectional shapes and dimensions (with variable cross-sectional perimeters), it is structurally difficult to distribute the fibrous material in an integrated manner (as a series of fibrous structures). In particular, it is necessary to select a fibrous material that can flexibly follow changes in the cross-sectional shape and cross-sectional dimensions of the mandrel that serves as the inner mold for the shaped pipe (hollow molded body) during the manufacturing process.

[0009] For example, when "threads, cords, etc." are used as the fiber member, the arrangement of the fibers is difficult to follow changes in the cross-sectional shape or cross-sectional dimensions, and the arrangement cannot be maintained, so uniform strength cannot be obtained. Furthermore, when a "woven fabric" woven with warp and weft threads is used as the fiber member, its structure has little elasticity and it may not be able to follow changes in cross-sectional shape or cross-sectional dimensions. Therefore, when manufacturing irregularly shaped FRP pipes using these fiber components ("threads, cords, etc.", "woven fabrics"), each section with a different cross-sectional shape and cross-sectional dimensions must be manufactured separately and then connected using connecting devices such as joints. This not only makes it difficult to form the pipe efficiently, but can also result in uneven strength, such as weakening the strength at the joints.

[0010] In contrast, when a "knitted fabric" is used as the fiber member, it can be formed into a seamless, highly stretchable cylindrical sleeve, which can flexibly follow changes in the cross-sectional shape and cross-sectional dimensions of the mandrel that serves as the inner mold for the irregular pipe. As a result, in a series of hollow molded bodies that include sections with different cross-sectional shapes and dimensions, it is possible to arrange a seamless, integrated (series) fiber structure inside the resin molded body throughout the entire irregular pipe, even through the sections where the cross-sectional circumference changes.

[0011] However, since "knitted fabric" is characterized by the fact that the threads are woven while being entangled in a loop shape, there are inevitably large gaps between the threads, which results in a low thread density.This can lead to uneven placement of the fiber components within the irregularly shaped tube, which can result in uneven strength, making it lacking in reinforcing properties.

[0012] Therefore, as a fiber component to be arranged in a series of hollow molded bodies including areas with different cross-sectional shapes and dimensions (changing cross-sectional circumference), it is desirable to have a fiber component that is a seamless (joint-free) and integrated (continuous) structure throughout the entire molded body, and that can be arranged at a high density with little bias.

[0013] In addition, in order to accommodate a wide range of irregularly shaped pipes, in addition to means for uniformly distributing the fibrous material throughout the entire irregularly shaped pipe, other means for increasing the uniformity of the physical properties (mechanical strength) along the longitudinal direction of the irregularly shaped pipe are also required.

[0014] The object of the present invention is to provide an FRP deformed pipe in which fibrous members are embedded inside a resin molded body, and in which the fibrous members are arranged with little bias and at a high density throughout the entire longitudinal and circumferential directions of the deformed pipe inside a resin molded body whose cross-sectional circumference and cross-sectional shape change, and to provide a method for manufacturing the same. Furthermore, the object of the present invention is to provide a special-shaped pipe that can be efficiently formed as a continuous, integrated FRP molded product, without the need to manufacture each section with a different cross-sectional circumference separately and connect them with joints or the like, and a method for manufacturing the same. A further object of the present invention is to provide a specially shaped pipe having highly uniform physical properties in the longitudinal direction of the specially shaped pipe, and a method for manufacturing the same. [Means for solving the problem]

[0015] The present invention is an FRP deformed pipe in which a fiber member is embedded inside a resin molded body, a normal portion having a predetermined cross-sectional perimeter and a predetermined cross-sectional shape; a non-circumferential portion having at least one of a cross-sectional circumferential length longer than that of the normal portion and a cross-sectional shape different from that of the normal portion; and The fiber member has a tubular braided structure and is integrally disposed across the normal portion and the irregular-shaped portion, and the fiber member is formed by combining braided yarns oriented at an orientation angle with respect to the central axis of the irregularly shaped pipe in the range of ±5 to 85°, The orientation angle θ2 of the braid yarn in the irregular portion satisfies the following relationship with respect to the orientation angle θ1 of the braid yarn in the normal portion:

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[0016] According to the above configuration, the tubular braided fiber member is seamlessly and integrally arranged throughout the normal and irregular portions of the irregular pipe. Therefore, the fiber member is arranged with little fiber bias and at high density throughout the entire longitudinal and circumferential directions of the irregular pipe inside the resin molded body, whose cross-sectional circumference and cross-sectional shape vary. As a result, the resin molded body is reinforced with fibers uniformly and with little bias, resulting in a lightweight FRP irregular pipe that maintains strength comparable to that of metal. Furthermore, the irregular pipe can be formed as an FRP molded product in which the normal portion and the irregular portion are continuous and integrated. Therefore, it is not necessary to manufacture the normal portion and the irregular portion separately and connect them with joints, etc., and it can be formed efficiently. Furthermore, when the orientation angle θ2 of the braided yarns in the irregular portion of the fiber component satisfies the relationship of the above formula relative to the orientation angle θ1 of the braided yarns in the regular portion, the difference between the physical properties (mechanical strength) of the regular portion and the physical properties (mechanical strength) of the irregular portion becomes small. As a result, the physical properties of the regular portion and the irregular portion become nearly equal, which increases the homogeneity between the regular portion and the irregular portion, and as a result, it becomes possible to accommodate irregular pipes of a wide range of shapes.

[0017] Furthermore, the present invention may be characterized in that in the irregularly shaped pipe, the relative ratio of tensile modulus of elasticity, which is the difference between the tensile modulus of elasticity of the irregularly shaped portion and the tensile modulus of elasticity of the normal portion divided by the tensile modulus of elasticity of the normal portion, is 0.25 or less.

[0018] According to the above configuration, the regular portion and the irregular portion have high homogeneity, so that it is possible to accommodate irregular pipes of a wide range of shapes.

[0019] Furthermore, the present invention may be characterized in that in the irregularly shaped pipe, the relative fracture strength ratio, which is the difference between the fracture strength of the irregularly shaped portion and the fracture strength of the normal portion divided by the fracture strength of the normal portion, is 0.25 or less.

[0020] According to the above configuration, the regular portion and the irregular portion have high homogeneity, so that it is possible to accommodate irregular pipes of a wide range of shapes.

[0021] The present invention also provides a method for manufacturing a deformed FRP pipe having a fiber member embedded inside a resin molding, comprising: The irregularly shaped pipe has a normal portion having a predetermined cross-sectional circumferential length and an irregularly shaped portion having a cross-sectional circumferential length longer than the cross-sectional circumferential length of the normal portion, a mandrel having a normal portion forming portion having an outer circumferential shape corresponding to the cross-sectional circumferential length of the normal portion and an irregular portion forming portion having an outer circumferential shape corresponding to the cross-sectional circumferential length of the irregular portion; a covering step of covering the mandrel with a sleeve formed by combining braided yarns, the sleeve being stretchable at least within a range from the minimum cross-sectional perimeter to the maximum cross-sectional perimeter of the mandrel and having a constant diameter in the longitudinal direction when not stretched and having a tubular braided structure made of the fiber member; an impregnation and curing step of impregnating the sleeve with a resin and curing the resin after the covering step; and removing the mandrel after the resin has hardened. In the covering process, the sleeve is placed on the mandrel so that the orientation angle of the braided yarn relative to the central axis direction of the irregularly shaped tube is in the range of ±5 to 85°, and the orientation angle θ2 of the braided yarn in the irregularly shaped portion satisfies the relationship of the following formula with respect to the orientation angle θ1 of the braided yarn in the normal portion.

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[0022] According to the above manufacturing method, the sleeve, in which the fiber member has a cylindrical braided structure, is stretchable within the range from the minimum cross-sectional circumferential length of the mandrel to the maximum cross-sectional circumferential length of the mandrel, and therefore the sleeve can be integrally and continuously placed over the mandrel from the normal portion forming portion to the irregular portion forming portion while following the change in the cross-sectional circumferential length of the mandrel and uniformly disposed over the entire mandrel. This allows the sleeve to be uniformly disposed on the mandrel for the impregnation and curing process. Here, since the sleeve has no seams, it is possible to produce a special-shaped pipe with less unevenness in strength across the normal portion and the special-shaped portion compared to when the sleeve has seams. Furthermore, since the sleeve has a braided structure, that is, a braided product made of braided yarns, the braided yarns can be arranged more densely than when the sleeve is a knitted product made of knitting yarns. As a result, it is possible to produce a specially shaped pipe with little deviation in strength throughout the entire longitudinal and circumferential directions of the pipe. Furthermore, when the orientation angle θ2 of the braided yarns in the irregular portion of the sleeve satisfies the relationship of the above formula with respect to the orientation angle θ1 of the braided yarns in the regular portion, the difference in the physical properties (mechanical strength) between the regular portion and the irregular portion becomes small. As a result, the physical properties (mechanical strength) of the regular portion and the irregular portion become nearly equal, which increases the homogeneity between the regular portion and the irregular portion, and as a result, it becomes possible to accommodate irregular pipes of a wide range of shapes. As a result, it is possible to manufacture a special-shaped pipe with little unevenness in strength across the normal portion and the special-shaped portion.

[0023] The present invention also provides a method for manufacturing a deformed FRP pipe having a fiber member embedded inside a resin molding, comprising: The irregular-shaped pipe has a normal portion having a predetermined cross-sectional shape and an irregular-shaped portion having a cross-sectional shape different from the cross-sectional shape of the normal portion, a mandrel having a normal portion forming portion having an outer circumferential shape corresponding to the cross-sectional shape of the normal portion and an irregular portion forming portion having an outer circumferential shape corresponding to the cross-sectional shape of the irregular portion, a covering step of covering the fiber member with a sleeve formed by combining braided yarns, the sleeve being stretchable from at least the outer peripheral shape of the normal portion forming portion to the outer peripheral shape of the irregularly shaped portion forming portion and having a constant diameter in the longitudinal direction when not stretched and having a tubular braided structure; an impregnation and curing step of impregnating the sleeve with a resin and curing the resin after the covering step; and removing the mandrel after the resin has hardened. In the covering process, the sleeve is placed on the mandrel so that the orientation angle of the braided yarn relative to the central axis direction of the irregularly shaped tube is in the range of ±5 to 85°, and the orientation angle θ2 of the braided yarn in the irregularly shaped portion satisfies the relationship of the following formula with respect to the orientation angle θ1 of the braided yarn in the normal portion.

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[0024] According to the above manufacturing method, the sleeve, in which the fiber member has a tubular braided structure, can expand and contract to fit the outer circumferential shape from the normal portion forming portion to the irregular-shaped portion forming portion. Therefore, the sleeve can be integrally and continuously placed over the mandrel from the normal portion forming portion to the irregular-shaped portion forming portion, following the changes in the cross-sectional shape of the mandrel, and uniformly arranged over the entire mandrel. This allows the sleeve to be uniformly disposed on the mandrel for the impregnation and curing process. Here, since the sleeve has no seams, it is possible to produce a special-shaped pipe with less unevenness in strength across the normal portion and the special-shaped portion compared to when the sleeve has seams. Furthermore, since the sleeve has a braided structure, that is, a braided product made of braided yarns, the braided yarns can be arranged more densely than when the sleeve is a knitted product made of knitting yarns. As a result, it is possible to produce a specially shaped pipe with little deviation in strength throughout the entire longitudinal and circumferential directions of the pipe. Furthermore, when the orientation angle θ2 of the braided yarns in the irregular portion of the sleeve satisfies the relationship of the above formula with respect to the orientation angle θ1 of the braided yarns in the regular portion, the difference in physical properties (mechanical strength) between the regular portion and the irregular portion becomes small. As a result, the physical properties (mechanical strength) of the regular portion and the irregular portion become nearly equal, which increases the homogeneity between the regular portion and the irregular portion, and as a result, it becomes possible to accommodate irregular pipes of a wide range of shapes. As a result, it is possible to manufacture a special-shaped pipe with little unevenness in strength across the normal portion and the special-shaped portion. [Effects of the Invention]

[0025] With regard to an FRP shaped pipe in which fiber members are embedded inside a resin molded body, it is possible to provide an shaped pipe in which fiber members are arranged with little bias and at a high density throughout the entire longitudinal and circumferential directions of the shaped pipe inside a resin molded body whose cross-sectional circumference and cross-sectional shape change, and a method for manufacturing the same. Furthermore, it is possible to provide an irregularly shaped pipe and a manufacturing method thereof that can be efficiently formed as a continuous, integrated FRP molded product, without the need to manufacture each section with a different cross-sectional circumference separately and connect them with joints, etc. Furthermore, it is possible to provide a shaped pipe having highly uniform physical properties in the longitudinal direction of the shaped pipe, and a method for manufacturing the same. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 2 is a perspective view of a specially shaped pipe according to the first embodiment. [Figure 2] 1A and 1B are a plan view and a cross-sectional view of a special shaped pipe according to a first embodiment. [Figure 3] 1A is a cross-sectional view of the braided sleeve according to the first embodiment, and FIG. 1B is an explanatory view of the two-layer structure of the braided sleeve according to the first embodiment. [Figure 4] (A) An explanatory diagram of a braided structure (1 cell) formed only with inner layer braid yarns in an inner layer braided sleeve. (B) An explanatory diagram of a braided structure (1 cell) formed with inner layer braid yarns and an axial yarn in an inner layer braided sleeve. [Figure 5] FIG. 2 is an explanatory diagram of the braided structure (one cell) of the outer layer braided sleeve. [Figure 6] 3 is a cross-sectional view illustrating the arrangement of a braided sleeve on a shaped pipe forming mandrel according to the first embodiment. FIG. [Figure 7] 1A is an explanatory diagram of a sleeve braiding process, and FIG. 1B is an explanatory diagram of a spindle track in the sleeve braiding process. [Figure 8] FIG. 2 is an explanatory view of a mandrel for forming a shaped pipe according to the first embodiment. [Figure 9]FIG. 2 is an explanatory diagram of a manufacturing process of a preform. [Figure 10] FIG. 1 is an explanatory diagram regarding a resin molding process for a preform. [Figure 11] 10A and 10B are explanatory diagrams of a special-shaped pipe according to another embodiment. [Figure 12] 10A and 10B are a plan view and a cross-sectional view of a special-shaped pipe according to another embodiment. [Figure 13] FIG. 10 is a perspective view of a specially shaped pipe according to a second embodiment. [Figure 14] 10A and 10B are a plan view and a cross-sectional view of a special shaped pipe according to a second embodiment. [Figure 15] FIG. 10 is a cross-sectional view illustrating the arrangement of a braided sleeve on a shaped pipe forming mandrel according to a second embodiment. [Figure 16] FIG. 10 is an explanatory view of a mandrel for forming a shaped pipe according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0027] (First embodiment) The first embodiment will be described below with reference to the drawings.

[0028] (Deformed pipe 1) As shown in Figures 1 and 2, the irregular pipe 1 is a cylindrical pipe made of FRP in which a braided structure made of a braided sleeve (a fiber member such as a carbon fiber material) is embedded inside a resin molded body, and in its longitudinal direction, it has a cylindrical normal portion 2, an irregular portion 3 which has a rectangular cross-sectional shape perpendicular to the central axis direction X of the irregular pipe 1 and has a cross-sectional perimeter longer than that of the normal portion 2 (the cross-sectional perimeter of the cross section perpendicular to the central axis direction X of the irregular pipe 1), and an intermediate portion 4 which is located between the normal portion 2 and the irregular portion 3 and has a shape in which the cross-sectional perimeter from the normal portion 2 to the irregular portion 3 gradually increases (changes) from the cross-sectional perimeter of the normal portion 2 to the cross-sectional perimeter of the irregular portion 3.

[0029] Here, the irregularly shaped pipe is a series of hollow molded bodies that do not have a constant cross-sectional shape or cross-sectional size, but include multiple sections with different cross-sectional shapes or cross-sectional sizes. By including sections with different cross-sectional shapes or cross-sectional sizes, the cross-sectional circumference or cross-sectional shape is not constant but changes throughout the hollow molded body. Furthermore, the hollow molded body is a molded body having a hollow portion, and includes a molded body having a hollow portion with one end open and a molded body having a hollow portion with both ends open. In the first embodiment, an irregular pipe 1, which is a hollow molded body having a normal portion 2 having a predetermined cross-sectional circumference (cross-sectional circumference relating to a cross section perpendicular to the axial direction of the irregular pipe 1), and an irregular portion 3 having a cross-sectional circumference longer than the cross-sectional circumference of the normal portion 2, will be described as an example. In addition, the intermediate portion 4 in the first embodiment is a portion located between the normal portion 2 and the irregular portion 3 in the irregular pipe 1, and the cross-sectional circumference from the normal portion 2 to the irregular portion 3 gradually increases (changes) from the cross-sectional circumference of the normal portion 2 to the cross-sectional circumference of the irregular portion 3.

[0030] There are no particular limitations on the manner in which the shaped pipe 1 can be used, and the shaped pipe 1 can be used in structures such as golf shafts, tennis rackets, fishing rods, bicycle frames, automobile parts, power transmission shafts, roofs, and large drones (main body frames, propellers, propeller guards, arms, and skids).

[0031] (Braided structure of irregular tube 1) The irregularly shaped pipe 1 is embedded inside a resin molded body in a state where one or more layers of braided sleeves with a tubular braided structure are overlapped and integrally arranged across the normal portion 2, intermediate portion 4, and irregularly shaped portion 3.

[0032] The braided sleeve has a fiber structure that is significantly different from that of knitted fabrics, which are made by intertwining threads into loops, and woven fabrics, which are made by weaving warp and weft threads at right angles, and has a braided structure that is highly elastic and has a high thread density.

[0033] First, compared to woven fabrics made of warp and weft threads, braided sleeves have greater stretchability due to the braided structure of the fabric. Meanwhile, the stretchability of knitted fabrics is as high as that of braided fabrics. However, braided sleeves differ significantly from knitted fabrics in that the braided threads are densely arranged. Knitted fabrics are knitted by intertwining the threads in a loop, which inevitably results in large gaps between the threads. In contrast, braided sleeves have densely arranged threads, resulting in smaller gaps between the threads and a higher thread density than knitted fabrics.

[0034] In addition, the braided sleeve has a seamless, tubular braided structure that is strong and has no joints. Because there are no seams in the braided sleeve, cracks in the shaped pipe 1 can be prevented from occurring at the seams.

[0035] In the first embodiment, as shown in Figure 3(A), the braided structure of the irregular pipe 1 has a two-layer structure consisting of an outer layer braided sleeve 12 arranged on the outer periphery of the irregular pipe 1 and an inner layer braided sleeve 13 arranged on the inner periphery of the irregular pipe 1.

[0036] (Inner layer braided sleeve 13) The inner layer braided sleeve 13 is a cylindrical braided sleeve having a constant diameter in the longitudinal direction when not stretched, and is layered on the inner peripheral side of the outer layer braided sleeve 12 . As shown in Figures 3(B) and 4, the inner layer braided sleeve 13 is formed by crossing and combining an axial yarn 132 formed of high-strength (high elastic modulus) fiber and oriented in the central axis direction X of the irregular pipe 1 (at an orientation angle of 0° relative to the central axis direction X), and an inner layer braided yarn 131 made of elastic yarn and oriented at an orientation angle relative to the central axis direction X in the range of ±5 to 85°.

[0037] Furthermore, with regard to the elasticity (elasticity range) of the inner layer braided sleeve 13, from the viewpoint of uniformly disposing the braided sleeve on the irregular pipe forming mandrel 21 in the manufacturing process (described later), the cross-sectional circumference of the inner layer braided sleeve 13 is required to be elastic within a range from a value smaller than the minimum cross-sectional circumference of the irregular pipe forming mandrel 21 used in the manufacturing process (described later) to a value larger than the maximum cross-sectional circumference of the irregular pipe forming mandrel 21.

[0038] Here, "uniformly arranging the braided sleeve on the mandrel 21 for forming the irregular pipe" means that the braided sleeve can be fitted over the mandrel 21 for forming the irregular pipe well, and the braided sleeve is arranged on the mandrel 21 for forming the irregular pipe with little bias while suppressing the braided sleeve from becoming loose on the mandrel 21 for forming the irregular pipe.

[0039] For example, if the minimum cross-sectional circumference of the mandrel 21 for forming a special-shaped pipe is 60 mm and the maximum cross-sectional circumference of the mandrel 21 for forming a special-shaped pipe is 90 mm, the cross-sectional circumference of the inner layer braid sleeve 13 is required to have an elasticity ranging from a value smaller than 60 mm (e.g., 50 mm) to a value larger than 90 mm (e.g., 100 mm).

[0040] Furthermore, when the cross-sectional circumferential length of the inner layer braid sleeve 13 is smaller (contracted) than the cross-sectional circumferential length of the irregularly shaped portion 3, as in the regular portion 2, the orientation angle (θ) is small. On the other hand, when the cross-sectional circumferential length of the inner layer braid sleeve 13 is larger (expanded) than the cross-sectional circumferential length of the regular portion 2, as in the irregularly shaped portion 3, the orientation angle (θ) is large. Therefore, from the viewpoint of the strength of the irregularly shaped portion 3, it is preferable that the orientation angle (θ) of the inner layer braid sleeve 13 in the irregularly shaped portion 3 be in the range of 15° to 80°, for example.

[0041] Examples of high-strength (high elastic modulus) fibers that can be used to form the axial thread 132 of the inner layer braided sleeve 13 include carbon fiber, glass fiber, aramid fiber, boron fiber, silicon carbide fiber, steel fiber, polyethylene fiber, nylon fiber, alumina fiber, Tyranno fiber, basalt fiber, and amorphous fiber.

[0042] Examples of elastic yarns that can be used to form the inner layer braided yarn 131 of the inner layer braided sleeve 13 include multifilament yarns made of thermoplastic resins such as nylon resin, polybutylene terephthalate resin, and polyester resin, and false twisted yarns (also called crimped yarns or woolly yarns) obtained by processing monofilament yarns, urethane fibers, etc.

[0043] (Outer layer braid sleeve 12) The outer layer braided sleeve 12 is a cylindrical braided sleeve having a constant diameter in the longitudinal direction when not stretched, and is layered on the outer peripheral side of the inner layer braided sleeve 13 . As shown in Figures 3(B) and 5, the outer layer braided sleeve 12 is formed by combining outer layer braided yarns 121 made of high-strength (high elastic modulus) fibers, oriented at an orientation angle (θ) relative to the central axis direction X of the irregular pipe 1 within the range of ±5 to 85°, so that they intersect.

[0044] In addition, the elasticity of the outer layer braided sleeve 12 (more specifically, the elasticity range based on the cross-sectional circumference of the deformed pipe forming mandrel 21 including the inner layer braided sleeve 13 when the deformed pipe forming mandrel 21 is covered with the inner layer braided sleeve 13) is the same as that of the inner layer braided sleeve 13. From the viewpoint of the strength of the irregularly shaped portion 3, the orientation angle (θ) of the outer layer braid sleeve 12 in the irregularly shaped portion 3 is preferably set in the range of, for example, 15° to 80°. In addition, examples of high-strength (high elastic modulus) fibers that can be used to form the outer layer braided yarn 121 of the outer layer braided sleeve 12 include carbon fiber, glass fiber, aramid fiber, boron fiber, silicon carbide fiber, steel fiber, polyethylene fiber, nylon fiber, alumina fiber, Tyranno fiber, basalt fiber, and amorphous fiber.

[0045] (Resin molding of irregular pipe 1) Resin materials used for resin molding of the braided structure of the irregular pipe 1 (inner layer braided sleeve 13, outer layer braided sleeve 12) include thermosetting resins (matrix resins) such as epoxy resin, polyester resin, vinyl ester resin, phenolic resin, and polyurethane resin, as well as thermoplastic resins such as nylon resin, polyethylene resin, polypropylene resin, polyphenylene sulfide resin, polyether ether ketone resin, polycarbonate resin, acrylonitrile-butadiene-styrene copolymer resin (ABS resin), polyacetal resin, polyethylene terephthalate resin, polybutylene terephthalate resin, polystyrene resin, acrylonitrile-styrene resin, polyvinyl chloride resin, and acrylic resin. Resin molding methods include resin transfer molding (RTM: vacuum suction and pressure impregnation), VaRTM (vacuum impregnation method), and internal pressure molding.

[0046] In the profiled pipe 1 of the first embodiment, seamless tubular braided sleeves (braided sleeve 13 for the inner layer, braided sleeve 12 for the outer layer) with a braided structure having high elasticity and a high thread density are seamlessly and integrally arranged throughout the normal portion 2, middle portion 4, and profiled portion 3 of the profiled pipe 1. Therefore, the braided sleeves are arranged with little fiber bias and at high density throughout the entire longitudinal and circumferential directions of the profiled pipe 1 inside the resin molded body, whose cross-sectional circumference varies. As a result, the resin molded body is reinforced with fibers uniformly and with little bias, resulting in a lightweight FRP profiled pipe 1 that maintains strength comparable to that of metal. Furthermore, the irregular pipe 1 can be formed as a continuous, integrated FRP molded product with a normal section 2, an intermediate section 4, and an irregular section 3, each with a different cross-sectional circumferential length. Therefore, it is not necessary to manufacture the normal section 2, the intermediate section 4, and the irregular section 3 separately and connect them with joints or the like, and the pipe can be formed efficiently.

[0047] The profiled pipe 1 is also provided with an inner layer braided sleeve 13 formed by combining an axial yarn 132 oriented in the central axis direction X of the profiled pipe 1 with an inner layer braided yarn 131 oriented at an orientation angle relative to the central axis direction X in the range of ±5 to 85°. This allows for improved mechanical properties in the axial direction of the profiled pipe 1 compared to a profiled pipe provided with only a braided sleeve formed by combining braided yarns.

[0048] (Relationship between the normal part 2, irregular part 3, and intermediate part 4 and the braided sleeve) When the irregular pipe 1 has a normal portion 2, an irregular portion 3, and an intermediate portion 4 with different cross-sectional circumferences, as in the first embodiment, in the manufacturing process (details will be described later), when a seamless tubular braided sleeve (inner layer braided sleeve 13, outer layer braided sleeve 12) with a braided structure having high elasticity and a high thread density as described above is placed over the irregular pipe forming mandrel 21 having a shape corresponding to the shapes of the normal portion 2, the irregular portion 3, and the intermediate portion 4, the braided sleeve expands and contracts in accordance with the change in shape of the irregular pipe forming mandrel 21.

[0049] Here, when covering a shaped pipe forming mandrel 21 having a shape corresponding to the shapes of the normal section 2, the shaped section 3, and the intermediate section 4 with a braided sleeve, in order to uniformly arrange the braided sleeve on the shaped pipe forming mandrel 21 and cover the shaped pipe forming mandrel 21 with the braided sleeve integrally and continuously, it is required that the braided sleeve have high followability when expanding and contracting in response to changes in the shape of the shaped pipe forming mandrel 21 (high adhesion of the braided sleeve to the shaped pipe forming mandrel 21).

[0050] Therefore, as shown in Figure 2, the angle E between the normal portion 2 and the intermediate portion 4 in the cross section of the irregular pipe 1 in the direction of the central axis X, and the angle F between the intermediate portion 4 and the irregular portion 3 in the cross section of the irregular pipe 1 in the direction of the central axis X, may be 12° or less. Here, if the angle E and the angle F are greater than 12°, during the manufacturing process, when the braided sleeve is placed over the irregular pipe forming mandrel 21, the braided sleeve will sag around the irregular pipe forming mandrel 21 in the areas of the braided sleeve corresponding to the areas between the normal portion 2 and the intermediate portion 4 and the areas between the intermediate portion 4 and the irregular portion 3, which may result in strength imbalances in the areas of the manufactured irregular pipe 1 between the normal portion 2 and the intermediate portion 4 and the areas between the intermediate portion 4 and the irregular portion 3.

[0051] According to the above configuration, the region between the normal portion 2 and the intermediate portion 4 and the region between the intermediate portion 4 and the irregular portion 3 can be made smooth. This improves the ability of the braided sleeve to conform to changes in shape of the irregular portion 2 when it is placed over the irregular portion 2, the irregular portion 3, and the intermediate portion 4. This also improves the ability of the braided sleeve to fit the irregular portion 2 as it expands and contracts in response to changes in shape of the irregular portion 2. Furthermore, the braided sleeve, which is a seamless, tubular braided sleeve, can be more precisely and integrally and continuously arranged from the normal portion 2 to the irregular portion 3 via the intermediate portion 4, which has a smooth slope (no steep or stepped portions). This results in an irregular portion 1 with uniform strength across the normal portion 2, the intermediate portion 4, and the irregular portion 3.

[0052] The angles E and F are not limited to 12° or less, and may be greater than 12°. In this case, the braided sleeve may be disposed in a curved state with a gentle change in shape in the region between the normal portion 2 and the intermediate portion 4, as shown in FIG. 6.

[0053] Furthermore, the relative ratio of cross-sectional perimeters, which is the difference between the cross-sectional perimeters of the regular portion 2 and the irregular portion 3 divided by the cross-sectional perimeter of the regular portion 2, is preferably 0.63 or less. The reason for this is that if the relative ratio of cross-sectional perimeters is greater than 0.63, it may not be possible to uniformly arrange the braided sleeve over the entire irregular pipe forming mandrel 21 during the manufacturing process. That is, when a braided sleeve is assembled to fit the irregular portion 3, which has the longer cross-sectional perimeter of the regular portion 2 and the irregular portion 3, if the relative ratio of cross-sectional perimeters is greater than 0.63, when the braided sleeve is placed over the regular portion 2, which has the shorter cross-sectional perimeter, the braided sleeve may become loose even if the diameter of the braided sleeve is reduced. Conversely, when a braided sleeve is assembled to fit the regular portion 2 with the shorter cross-sectional perimeter, if the relative cross-sectional perimeter ratio is greater than 0.63, it may not be possible to successfully cover the irregular portion 3 with the longer cross-sectional perimeter even if the braided sleeve is expanded in diameter. If the braided sleeve cannot be uniformly disposed over the entire irregular pipe forming mandrel 21 in this way, strength imbalances may occur in the region between the regular portion 2 and the middle portion 4 of the manufactured irregular pipe 1, and in the region between the middle portion 4 and the irregular portion 3.

[0054] According to the above configuration, when the braided sleeve is placed on the irregular pipe forming mandrel 21, which has a shape corresponding to the shapes of the normal portion 2, the irregular portion 3, and the intermediate portion 4, the braided sleeve can be made to conform to changes in shape of the irregular pipe forming mandrel 21 as it expands and contracts (the braided sleeve's adhesion to the irregular pipe forming mandrel 21) more easily. This allows the braided sleeve to be uniformly disposed on the irregular pipe forming mandrel 21 throughout its entirety. That is, when the braided sleeve is placed on the irregular portion 3, which has the longer cross-sectional perimeter of the normal portion 2 or the irregular portion 3, the braided sleeve can be prevented from becoming loose when the braided sleeve is placed on the normal portion 2, which has the shorter cross-sectional perimeter. Furthermore, when the braided sleeve is placed on the regular portion 2, which has the shorter cross-sectional perimeter, the braided sleeve can be properly placed on the irregular portion 3 by expanding the diameter of the braided sleeve. Furthermore, the seamless tubular braided sleeve with a braided structure can be uniformly arranged on the shaped pipe forming mandrel 21, and can be more precisely and integrally and continuously arranged from the normal portion 2 to the shaped portion 3. As a result, a shaped pipe 1 can be produced that has no uneven strength across the normal portion 2, intermediate portion 4, and shaped portion 3.

[0055] (Relationship between the orientation angle θ2 of the outer layer braiding yarns 121 of the irregular portion 3 and the orientation angle θ1 of the outer layer braiding yarns 121 of the normal portion 2 in the outer layer braid sleeve 12) In the profiled pipe 1 of the first embodiment, as described above, the outer layer braided sleeve 12 is formed by combining outer layer braided yarns 121 oriented at an orientation angle in the range of ±5 to 85° with respect to the central axis direction X of the profiled pipe 1. In this outer layer braided sleeve 12, the orientation angle θ2 of the outer layer braided yarns 121 in the profiled portion 3 satisfies the relationship of the following (Equation 1) with respect to the orientation angle θ1 of the outer layer braided yarns 121 in the normal portion 2.

number

[0056] According to the above configuration, the difference between the physical properties (mechanical strength) of the regular portion 2 and the physical properties (mechanical strength) of the irregularly shaped portion 3 is reduced. That is, the value obtained by dividing the difference between the tensile modulus of elasticity of the irregularly shaped portion 3 and the tensile modulus of elasticity of the regular portion 2 by the tensile modulus of elasticity of the regular portion 2 (hereinafter referred to as the tensile modulus relative ratio) can be set to 0.25 or less. Furthermore, the value obtained by dividing the difference between the breaking strength of the irregularly shaped portion 3 and the breaking strength of the regular portion 2 by the breaking strength of the regular portion 2 (hereinafter referred to as the breaking strength relative ratio) can be set to 0.25 or less. As a result, the physical properties (mechanical strength) of the regular portion 2 and the irregularly shaped portion 3 become nearly equal, which increases the homogeneity of the regular portion 2 and the irregularly shaped portion 3, and as a result, irregularly shaped pipes with a wide range of shapes can be accommodated.

[0057] Furthermore, the irregular pipe 1 of this embodiment has a relative ratio of tensile modulus of elasticity of 0.25 or less. With this configuration, the difference between the tensile modulus of elasticity of the normal portion 2 and the tensile modulus of elasticity of the irregular portion 3 is small, and the uniformity between the normal portion 2 and the irregular portion 3 is high, so it can accommodate irregular pipes of a wide range of shapes. Furthermore, the irregular pipe 1 of this embodiment has a relative ratio of breaking strength of 0.25 or less. With this configuration, the difference between the breaking strength of the normal portion 2 and the tensile modulus of elasticity of the irregular portion 3 is small, and the uniformity between the normal portion 2 and the irregular portion 3 is high, so it can accommodate irregular pipes of a wide range of shapes.

[0058] (cover factor) When manufacturing the irregular pipe 1, the braided sleeves (inner layer braided sleeve 13, outer layer braided sleeve 12) must be stretched and contracted to fit the regular portion 2, irregular portion 3, and intermediate portion 4, which have different cross-sectional circumferences, when they are placed over the irregular pipe forming mandrel 21, which has a shape corresponding to the shapes of the regular portion 2, irregular portion 3, and intermediate portion 4 of the irregular pipe 1. In such a case, compared to when the braided sleeve is placed over a cylindrical mandrel, the regular portion 2 acts to shrink the braided sleeve, while the irregular portion 3 acts to stretch the braided sleeve, which may result in an imbalance in the braided structure of the irregular pipe 1 (a difference in strength).

[0059] Therefore, as an indicator of the elasticity of the braided sleeve to follow the shapes of the normal section 2, the irregular section 3, and the middle section 4 of the irregular pipe 1 while maintaining the desired strength, the braided structure of each section of the inner layer braided sleeve 13 and the outer layer braided sleeve 12 corresponding to the normal section 2, the irregular section 3, and the middle section 4 of the irregular pipe 1 may be formed using an indicator (value) called the cover factor cf (Equations 2 to 4), which indicates the proportion of the surface area of ​​the braided inner layer braided sleeve 13 and the outer layer braided sleeve 12 that is occupied by the braided yarns (outer layer braided yarns 121, inner layer braided yarns 131) and the axial yarns (axial yarns 132).

[0060] Here, as shown in Figures 1 to 5, the normal portion 2 and the irregular portion 3 of the irregular pipe 1 have different widths f [mm] per cell (one section surrounded by braided yarn) of the braided structure and different orientation angles θ [°] relative to the central axis direction X of the irregular pipe 1. Therefore, the normal portion cover factor cf (standard), irregular portion cover factor cf (irregular), and middle portion cover factor cf (middle) of the inner layer braided sleeve 13 and the outer layer braided sleeve 12, which correspond to the normal portion 2, irregular portion 3, and middle portion 4 that make up the irregular pipe 1, can be calculated. Furthermore, the calculation of the cover factor cf must take into consideration the following cases: a case where the cells of the braided structure are composed only of braid yarns (outer layer braid yarns 121) (cf1), as in the outer layer braided sleeve 12 shown in FIG. 5; and a case where the cells (see FIG. 4(A)) include a braided structure (cf1) composed only of braid yarns (inner layer braid yarns 131) and a braided structure (cf2) (see FIG. 4(B)) having a braid yarn (inner layer braid yarn 131) and an axial yarn (axial yarn 132), as in the inner layer braided sleeve 13 shown in FIG. 4 (cf3).

[0061] (Cover factor of outer layer braid sleeve 12) When the braided cell is made up of only the outer layer braid yarn 121, as in the outer layer braided sleeve 12 shown in FIG. 5, the width b fFrom values ​​based on two-dimensional data such as the length n [mm] of the outer layer braided sleeve 12, the number n [pieces] of outer layer braided yarns 121, the inner diameter D [mm] of the outer layer braided sleeve 12, and the orientation angle θ [°] of the outer layer braided yarns 121 with respect to the central axis direction X of the irregular tube 1, the normal portion cover factor cf1 (standard), the irregular portion cover factor cf1 (irregular), and the middle portion cover factor cf1 (middle) of the outer layer braided sleeve 12 corresponding to the normal portion 2, the irregular portion 3, and the middle portion 4 are calculated using the following (Equation 2).

[0062]

number

[0063] Furthermore, when the braided structure is composed only of the outer layer braided yarn 121 (when the braided structure does not include an axial yarn), as in the outer layer braided sleeve 12, the values ​​of the normal portion cover factor cf1 (standard), irregular portion cover factor cf1 (irregular), and middle portion cover factor cf1 (middle) calculated by the above (Equation 2) are set to satisfy the condition of being in the range of 100% or less and 50% or more from the viewpoint of high rigidity for the entire irregular pipe 1. This makes it possible to suppress a decrease in the strength of the entire irregular pipe 1 and extreme imbalances in strength, and maintain the strength of the irregular pipe 1 itself.

[0064] (Cover factor of inner layer braid sleeve 13) When the cover factor cf3 is calculated for a braided structure having a cell (see FIG. 4(A)) composed only of an inner layer braid 131, and a cell (see FIG. 4(B)) composed of an inner layer braid 131 and an axial yarn 132, as in the case of the inner layer braided sleeve 13 shown in FIG. 4(A), the cover factor cf1 (calculated in the same manner as for the outer layer braided sleeve 12: see Equation 2) for the cell whose braided structure is composed only of the inner layer braid 131 is calculated, and the cover factor cf2 for the cell whose braided structure is composed of the inner layer braid 131 and the axial yarn 132 is calculated, as in the case of the inner layer braided sleeve 13 shown in FIG. 4(B).

[0065] Here, as shown in FIG. 4(B), when the braided cell includes an inner layer braid 131 and an axial thread 132, the width b f [mm], the number n [pieces] of the inner layer braided yarns 131, the inner diameter D [mm] of the inner layer braided sleeve 13, and the orientation angle θ [°] of the inner layer braided yarns 131 with respect to the central axis direction X, in addition to the width f [mm] per cell of the braided structure (one section surrounded by the inner layer braided yarns 131: see FIG. 4(B)), the width b m [mm] and the number n of the axial threads 132 m From values ​​based on two-dimensional data such as [book], the normal portion cover factor cf2 (standard), irregular portion cover factor cf2 (irregular), and middle portion cover factor cf2 (middle) of the inner layer braid sleeve 13, which correspond to the normal portion 2, irregular portion 3, and middle portion 4, are calculated using the following (Equation 3).

[0066]

number

[0067] As shown in Figures 4(A) and 4(B), in (Equation 3), A is the area of ​​one cell of the braided structure of the inner layer braided sleeve 13, and A S is the area of ​​the voids in one cell of the braided structure of the inner layer braided sleeve 13 excluding the inner layer braid 131 portion, and A a is the area of ​​the axial yarn 132 (excluding the portion overlapping with the inner layer braid yarn 131) in one cell of the braided structure of the inner layer braided sleeve 13.

[0068] In calculating the value of the cover factor cf3 when the cell (see Figure 4(A)) includes a braided structure composed only of the inner layer braid 131, as in the inner layer braided sleeve 13, and the cell (see Figure 4(B)) includes a braided structure having the inner layer braid 131 and an axial yarn 132, the cover factor cf3 is calculated using the following (Equation 4) taking into account the cover factor cf1 in the cell whose braided structure is composed only of the inner layer braid 131 as shown in Figure 4(A) and the cover factor cf2 in the cell whose braided structure is composed of the inner layer braid 131 and an axial yarn 132 as shown in Figure 4(B).The values ​​of the standard portion cover factor cf3 (standard), irregular portion cover factor cf3 (irregular), and middle portion cover factor cf3 (middle) are each set to satisfy the condition of being in the range of 100% or less and 50% or more, from the viewpoint of high rigidity for the entire irregular tube 1. This prevents the strength of the shaped pipe 1 as a whole from decreasing or becoming extremely unbalanced in strength, and allows the strength of the shaped pipe 1 itself to be maintained.

[0069] In the case of the above-mentioned braided sleeve for the inner layer 13, elastic yarn is used for the braided yarn for the inner layer 131, so that the braided sleeve for the inner layer 13 itself can be made flexible, and therefore the axial yarn 132 can be arranged seamlessly and uniformly along the central axis direction X throughout the normal portion 2, the intermediate portion 4, and the irregular portion 3 of the irregular tube 1.

[0070]

number

[0071] As described above, the values ​​of the normal section cover factor cf (standard), irregular section cover factor cf (irregular), and middle section cover factor cf (middle) of the inner layer braided sleeve 13 and the outer layer braided sleeve 12, which correspond to the normal section 2, irregular section 3, and middle section 4 that make up the irregular pipe 1, are set to satisfy the condition of being within the range of 100% or less and 50% or more. This is because if the values ​​of the standard portion cover factor cf (standard), irregular portion cover factor cf (irregular), and middle portion cover factor cf (middle) exceed 100%, they will exceed the surface area of ​​the inner layer braided sleeve 13 and the outer layer braided sleeve 12, which are formed by the braided structure of the outer layer braided yarn 121 and the braided structure of the inner layer braided yarn 131 and axial yarn 132, and part of the outer layer braided yarn 121, inner layer braided yarn 131, and axial yarn 132 will float on the surface of the irregular pipe 1, and loads will be applied to the floating parts or the surrounding area, which may reduce the high rigidity and impact resistance of the irregular pipe 1. Furthermore, if the values ​​of the standard portion cover factor cf (standard), irregular portion cover factor cf (irregular), and middle portion cover factor cf (middle) are each less than 50%, the spacing between the inner layer braided sleeve 13 in the regular portion 2 and irregular portion 3 of the irregular pipe 1, and the outer layer braided yarn 121, inner layer braided yarn 131, and axial yarn 132 in the outer layer braided sleeve 12 will increase, resulting in a decrease in thread density, which may reduce the high rigidity and impact resistance of the irregular pipe 1.

[0072] In addition, in the inner layer braided sleeve 13 and the outer layer braided sleeve 12 that constitute the irregular pipe 1, from the viewpoint of further enhancing the high rigidity and impact resistance of the irregular pipe 1, it is more preferable that the values ​​of the normal portion cover factor cf (standard), irregular portion cover factor cf (irregular), and middle portion cover factor cf (middle) each satisfy the condition of being in the range of 100% or less and 60% or more. Furthermore, it is most preferable that the values ​​of the normal portion cover factor cf (standard), irregular portion cover factor cf (irregular), and middle portion cover factor cf (middle) each satisfy the condition of being in the range of 100% or less and 70% or more.

[0073] Furthermore, it is preferable that the values ​​of the normal portion cover factor cf (standard), irregular portion cover factor cf (irregular), and middle portion cover factor cf (middle) are approximately the same (the difference between the maximum and minimum values ​​is within 10%). For example, if the value of the normal part cover factor cf (standard) is 99%, the value of the irregular part cover factor cf (irregular) is 89%, and the value of the middle part cover factor cf (middle) is 95%, then it can be said that each value is approximately the same (the difference between the maximum and minimum values ​​is within 10%). In this way, by making the values ​​of the standard section cover factor cf (standard), irregular section cover factor cf (irregular), and middle section cover factor cf (middle) approximately the same, the spacing between the inner layer braided sleeve 13 in the regular section 2 and irregular section 3 of the irregular pipe 1, and the outer layer braided yarn 121, inner layer braided yarn 131, and axial yarn 132 in the outer layer braided sleeve 12 are maintained at approximately the same level, and the thread density is also uniform, thereby suppressing strength imbalances (strength differences) throughout the irregular pipe 1.

[0074] (Method of manufacturing the irregular pipe 1) Next, a method for manufacturing the shaped pipe 1 will be described.

[0075] (1) Sleeve braiding process First, as shown in FIG. 7(a), the outer layer braided sleeve 12 and the inner layer braided sleeve 13 are manufactured using a braiding machine.

[0076] For example, in the case of the outer layer braided sleeve 12, braided yarns (outer layer braided yarns 121) wound around a spindle are combined on the outer periphery of a cylindrical sleeve-forming mandrel to form the outer layer braided sleeve 12. As shown in Fig. 7(b), the spindle moves along the track, so that the braided yarns (outer layer braided yarns 121) are combined, and a seamless outer layer braided sleeve 12 is formed on the sleeve-forming mandrel and then wound up by a winding device.

[0077] In the case of the inner layer braided sleeve 13, the braided yarn (inner layer braided yarn 131) wound around the spindle and the axial yarn 132 supplied from the bottom of the braiding machine (supplied from a fixed cylinder) are combined on the outer periphery of a cylindrical sleeve-forming mandrel to form the inner layer braided sleeve 13. As shown in Fig. 7(b), the spindle moves along the track, so that the braided yarn (inner layer braided yarn 131) and the axial yarn 132 are combined, and a seamless inner layer braided sleeve 13 is formed on the upper part of the sleeve-forming mandrel, and then wound up by a winding device.

[0078] (2) Preform manufacturing (coating process) Next, as shown in Figures 8 and 9, a silicone resin irregular pipe forming mandrel 21 having a normal portion forming portion 22 with an outer peripheral shape corresponding to the cross-sectional circumference of the normal portion 2 of the irregular pipe 1 to be manufactured, an intermediate portion forming portion 24 with an outer peripheral shape corresponding to the cross-sectional circumference of the intermediate portion 4, and an irregular portion forming portion 23 with an outer peripheral shape corresponding to the cross-sectional circumference of the irregular portion 3 is covered in order with an inner layer braid sleeve 13 and an outer layer braid sleeve 12, as described above, which are expandable within the range from the minimum cross-sectional circumference to the maximum cross-sectional circumference of the irregular pipe forming mandrel 21 and have a constant diameter in the longitudinal direction when not expanded or contracted, to produce a preform (hereinafter referred to as a preform) in which two layers of cylindrical braid sleeves are stacked.

[0079] In the first embodiment, a mandrel 21 for forming an irregular pipe made of silicone resin is used for the shaft portion (rod) of the preform, but the material used for the mandrel 21 for forming an irregular pipe may also be an elastic thermosetting resin or thermoplastic resin, or, for example, wax, polystyrene foam, plaster, low-melting point alloy, etc., may be used, making it possible to remove the mandrel 21 for forming an irregular pipe from the molded product even after molding.

[0080] In addition, in this covering process, the outer layer braid sleeve 12 is covered onto the irregular pipe forming mandrel 21 so that the orientation angle of the outer layer braiding yarns 121 relative to the central axis direction X of the irregular pipe 1 is in the range of ±5 to 85°, and the orientation angle θ2 of the outer layer braiding yarns 121 in the irregular section 3 satisfies the relationship of the above (Equation 1) with respect to the orientation angle θ1 of the outer layer braiding yarns 121 in the normal section 2.

[0081] (3) Installation in the mold Next, as shown in FIG. 10, the mandrel 21 for forming a special-shaped pipe on which the preforms are stacked is fitted into the cavity of the mold, and the lid is closed.

[0082] (4) Resin molding process (impregnation and hardening process) Next, as shown in Figure 10, thermosetting resin (matrix resin) is pressure-injected into the cavity of the mold using resin transfer molding (RTM), impregnating the preform with the thermosetting resin, and the excess thermosetting resin is vacuum-sucked out. The resin molding method may be Vacuum Reverse Transfer Molding (VaRTM) or internal pressure molding.

[0083] (5) Removal of the mandrel (removal process) Next, after the thermosetting resin impregnated in the preform has hardened, the shaped pipe forming mandrel 21 is removed. Alternatively, after the thermosetting resin has hardened, the shaped pipe forming mandrel 21 is melted by heating and removed.

[0084] (6) Finishing Finally, deburring, cutting, and painting are performed to obtain the special-shaped pipe 1 (see FIG. 1).

[0085] According to the above manufacturing method, the braided sleeves (the inner layer braided sleeve 13 and the outer layer braided sleeve 12) having a tubular braided structure are stretchable within a range from the minimum cross-sectional circumferential length to the maximum cross-sectional circumferential length of the irregular pipe forming mandrel 21. Therefore, the braided sleeve can be integrally and continuously covered from the normal portion forming portion 22 of the irregular pipe forming mandrel 21, through the intermediate portion forming portion 24, to the irregular portion forming portion 23, while following the change in the cross-sectional circumferential length of the irregular pipe forming mandrel 21 and while being uniformly disposed over the entire irregular pipe forming mandrel 21. This allows the braided sleeve to be uniformly disposed on the profiled pipe forming mandrel 21 and subjected to a resin molding process (impregnation and curing step).

[0086] Here, since there are no seams in the braided sleeves (braided sleeve 13 for the inner layer and braided sleeve 12 for the outer layer), it is possible to produce an irregularly shaped pipe 1 with less strength imbalance across the normal portion 2, the middle portion 4, and the irregularly shaped portion 3 compared to when the braided sleeves have seams. Furthermore, since the braided sleeve has a braided structure, that is, is a braid made of braided yarns, the braided yarns can be arranged more densely than when the sleeve is a knitted fabric made of knitted yarns. As a result, the shaped pipe 1 can have little unevenness in strength throughout the entire longitudinal and circumferential directions of the shaped pipe 1. Furthermore, when the orientation angle θ2 of the outer layer braiding yarns 121 of the irregular portion 3 in the outer layer braid sleeve 12 satisfies the relationship of (Equation 1) with respect to the orientation angle θ1 of the outer layer braiding yarns 121 of the regular portion 2, the difference between the physical properties of the regular portion 2 and the physical properties of the irregular portion 3 becomes small. This makes the physical properties of the regular portion 2 and the irregular portion 3 nearly uniform, thereby improving the homogeneity of the regular portion 2 and the irregular portion 3, and as a result, it is possible to accommodate irregular pipes 1 with a wide range of shapes.

[0087] As a result of the above, the resin molded bodies of the normal portion 2, the middle portion 4 and the irregular portion 3 are reinforced with fibers uniformly with little bias, resulting in an irregular FRP pipe 1 that is lightweight while maintaining strength comparable to that of metal. Furthermore, the irregular pipe 1 can be formed as a continuous, integrated FRP molded product consisting of the normal section 2, the intermediate section 4, and the irregular section 3. This eliminates the need to manufacture the normal section 2, the intermediate section 4, and the irregular section 3 separately and connect them with joints or the like, allowing for efficient formation.

[0088] (Other embodiments) (1) In the above first embodiment, an irregular pipe 1, which is a hollow molded body having a normal portion 2 having a predetermined cross-sectional circumference (cross-sectional circumference relating to a cross section perpendicular to the axial direction of the irregular pipe 1), and an irregular portion 3 having a cross-sectional circumference longer than the cross-sectional circumference of the normal portion 2, was described as an example.

[0089] However, even if the cross-sectional perimeter of the normal portion 2 and the cross-sectional perimeter of the irregular portion 3 are the same, if the cross-sectional shape of the normal portion 2 (the cross-sectional shape relating to a cross section perpendicular to the axial direction of the irregular pipe 1) and the cross-sectional shape of the irregular portion 3 are different, the same problems will arise as when the cross-sectional perimeter of the normal portion 2 and the cross-sectional perimeter of the irregular portion 3 are different.

[0090] Therefore, the irregular pipe 1001 can also be described as a hollow molded body having a normal portion 1002 having a predetermined cross-sectional shape (a cross-sectional shape relating to a cross section perpendicular to the axial direction of the irregular pipe 1001) and an irregular portion 1003 having a cross-sectional shape different from the cross-sectional shape of the normal portion 1002 (see Figures 1 and 2). Furthermore, the intermediate section 1004 is located between the normal section 1002 and the irregular section 1003 in the irregular pipe 1001, and can be described as a portion where the cross-sectional shape from the normal section 1002 to the irregular section 1003 changes from the cross-sectional shape of the normal section 1002 to the cross-sectional shape of the irregular section 1003. The irregularly shaped pipe 1001 in this case can be explained by replacing the "cross-sectional perimeter" of the normal portion 2, irregularly shaped portion 3, intermediate portion 4, etc. in the first embodiment with "cross-sectional shape."

[0091] Furthermore, the manufacturing method of the irregular pipe 1001 is similar to the manufacturing method of the irregular pipe 1 described above, but in "(2) Manufacturing of preform (coating process)", a preform is manufactured by sequentially covering an irregular pipe forming mandrel 1021 made of silicone resin, which has a normal portion forming portion 1022 having an outer circumferential shape corresponding to the cross-sectional shape of the normal portion 1002 of the irregular pipe 1001 to be manufactured, an intermediate portion forming portion 1024 having an outer circumferential shape corresponding to the cross-sectional shape of the intermediate portion 1004, and an irregular portion forming portion 1023 having an outer circumferential shape corresponding to the cross-sectional shape of the irregular portion 1003, with an inner layer braid sleeve 13 and an outer layer braid sleeve 12, which are expandable from the outer circumferential shape of the normal portion forming portion 1022 of the irregular pipe forming mandrel 1021 to the outer circumferential shape of the irregular portion forming portion 1023 and have a constant diameter in the longitudinal direction when not expanded or contracted, to produce a preform consisting of two layers of tubular braid sleeves. In this process, the outer layer braid sleeve 12 is placed over the irregular pipe forming mandrel 1021 so that the orientation angle of the outer layer braiding yarns 121 relative to the central axis direction X of the irregular pipe 1001 is in the range of ±5 to 85°, and the orientation angle θ2 of the outer layer braiding yarns 121 in the irregular section 1003 satisfies the relationship of the above (Equation 1) with respect to the orientation angle θ1 of the outer layer braiding yarns 121 in the normal section 1002.

[0092] According to the above manufacturing method, the braided sleeves (the inner layer braided sleeve 13 and the outer layer braided sleeve 12) having a tubular braided structure can expand and contract to fit the outer peripheral shape of the normal portion forming portion 1022 of the irregular pipe forming mandrel 1021 to the irregular portion forming portion 1023. Therefore, the braided sleeve can be integrally and continuously covered from the normal portion forming portion 1022 of the irregular pipe forming mandrel 1021, through the intermediate portion forming portion 1024, to the irregular portion forming portion 1023, while following the changes in the cross-sectional shape of the irregular pipe forming mandrel 1021 and while being uniformly disposed over the entire mandrel 1021. This allows the braided sleeve to be uniformly disposed on the profiled pipe forming mandrel 1021 and subjected to a resin molding process (impregnation and curing step).

[0093] Furthermore, as in the first embodiment described above, the braided sleeves (braided sleeve 13 for the inner layer and braided sleeve 12 for the outer layer) have no seams, so the irregular pipe 1001 can have less strength variation across the normal portion 1002, the middle portion 1004, and the irregular portion 1003 compared to when the braided sleeves have seams. Furthermore, since the braided sleeve has a braided structure, that is, is a braid made of braided yarns, the braided yarns can be arranged more densely than when the sleeve is a knitted fabric made of knitted yarns. As a result, the irregular shaped pipe 1001 can have little unevenness in strength over the entire length and circumferential direction of the irregular shaped pipe 1001. Furthermore, when the orientation angle θ2 of the outer layer braiding yarns 121 of the irregularly shaped portion 1003 in the outer layer braid sleeve 12 satisfies the relationship of (Equation 1) with respect to the orientation angle θ1 of the outer layer braiding yarns 121 of the regular portion 1002, the difference between the physical properties of the regular portion 1002 and the physical properties of the irregularly shaped portion 1003 becomes small. This makes the physical properties of the regular portion 1002 and the irregularly shaped portion 1003 nearly uniform, thereby improving the homogeneity of the regular portion 1002 and the irregularly shaped portion 1003, and as a result, it is possible to accommodate irregularly shaped pipes 1001 of a wide range of shapes.

[0094] (2) In the first embodiment, the special shaped pipe 1 is described as a pipe whose central axis direction X is straight, but it may have a curved portion.

[0095] (3) In the first embodiment, the normal portion 2 of the irregular pipe 1 has a cylindrical shape with a circular cross section, but the cross section may be a cylindrical shape with a square, triangle, or ellipse, and the shape is not particularly limited. Similarly, the irregular portion 3 of the irregular pipe 1 may also have a cylindrical shape with a circular, square, triangle, or ellipse cross section, and the shape is not particularly limited. Furthermore, the normal portion and the irregular-shaped portion may have the same cross-sectional shape (for example, a circle) but different cross-sectional perimeters, or may have the same cross-sectional perimeter but different cross-sectional shapes (for example, a circle and a triangle). That is, the irregular-shaped portion may have A) a cross-sectional perimeter longer than that of the normal portion and a cross-sectional shape different from that of the normal portion, B) a cross-sectional perimeter the same as that of the normal portion and a cross-sectional shape different from that of the normal portion, or C) a cross-sectional perimeter longer than that of the normal portion and a cross-sectional shape the same as that of the normal portion.

[0096] Furthermore, an irregular pipe is a hollow molded body having a normal portion having a predetermined cross-sectional circumference (cross-sectional circumference in a cross section perpendicular to the axial direction of the irregular pipe) and an irregular portion having a cross-sectional circumference longer than the cross-sectional circumference of the normal portion, or a hollow molded body having a normal portion having a predetermined cross-sectional shape (cross-sectional shape in a cross section perpendicular to the axial direction of the irregular pipe) and an irregular portion having a cross-sectional shape different from the cross-sectional shape of the normal portion.Therefore, for example, an irregular pipe may be an irregular pipe 201 having a normal portion 202, an irregular portion 203, and an intermediate portion 204, as shown in Figures 11 and 12, in which the irregular portion 203 has a cylindrical shape and the normal portion 202 has a plate shape obtained by radially compressing a cylindrical pipe.

[0097] (4) In the first embodiment, the shapes of the normal portion, irregular portion, and intermediate portion are defined by the cross-sectional perimeter or cross-sectional shape, but they may also be defined by the diameter (equivalent circle diameter: the value obtained by dividing the cross-sectional perimeter by π) calculated by regarding the cross-section (a cross-section perpendicular to the central axial direction X of the irregular pipe 1) as a circle. In this case, the irregular pipe can be defined as a hollow molded body having a normal portion having a predetermined equivalent circle diameter (equivalent circle diameter for a cross-section perpendicular to the axial direction of the irregular pipe) and an irregular portion having an equivalent circle diameter different in size from the equivalent circle diameter of the normal portion.

[0098] (5) In the above-described first embodiment of the profiled pipe 1, an example of a braided structure was described in which two layers of braided sleeves having a tubular braided structure (braided sleeve 13 for the inner layer and braided sleeve 12 for the outer layer) are embedded in a stacked state, but the braided sleeve may be a single layer, or may have a structure in which three or more layers are stacked. For example, when the braided sleeve is one layer, one layer of the outer layer braided sleeve 12 described in the above embodiment may be used as the braided sleeve.

[0099] The arrangement and type of the braided yarns and axial yarns that make up the braided sleeve can be selected appropriately depending on the required characteristics of the irregularly shaped pipe 1. The braided sleeve includes at least braided yarns, but the axial yarns may be configured to include or not include axial yarns.

[0100] (6) With regard to the braided sleeve having a cylindrical braided structure of the irregular pipe 1 of the first embodiment, the type of thread must be a high-strength fiber with high reinforcing properties (carbon fiber, aramid fiber, glass fiber, etc.), and may also include elastic thread. When multiple braided sleeves are stacked, the type of thread to be applied to which thread (braiding thread, axial thread) in which layer of the braided sleeve can be appropriately selected depending on the required characteristics.

[0101] Furthermore, the above-mentioned first embodiment of the deformed pipe 1 has been described as having a two-layer structure with one inner layer braided sleeve 13 as the inner layer and one outer layer braided sleeve 12 as the outer layer, but in consideration of the flexibility and strength of the deformed pipe 1, each layer may also be configured by stacking multiple braided sleeves of the same type. For example, the inner layer may be configured by stacking a plurality of inner layer braid sleeves 13, or the outer layer may be configured by stacking a plurality of outer layer braid sleeves 12. In this way, by changing the number of braided sleeves layered on the inner layer and the outer layer, the flexibility and strength of the shaped pipe 1 can be changed according to the required specifications.

[0102] Furthermore, in the first embodiment described above, if a set of braided sleeves is made up of an inner layer braided sleeve 13 (one piece) and an outer layer braided sleeve 12 (one piece), stacked in order from the inner periphery, the deformed pipe 1 will be composed of one set of braided sleeves, but this configuration is not limited to this, and the deformed pipe may also be composed of multiple sets of braided sleeves stacked on top of each other. In this way, by changing the number of sets of braided sleeve groups that make up the profiled pipe, the flexibility and strength of the profiled pipe can be changed according to the required specifications.

[0103] Furthermore, in the first embodiment, the irregular pipe 1 was configured to have one normal section 2, one irregular section 3, and one intermediate section 4, but this configuration is not limited to this, and for example, the irregular pipe may be configured to have a normal section, intermediate section, irregular section, intermediate section, and regular section in that order.

[0104] (Second embodiment) The second embodiment will be described below.

[0105] The special shaped pipe 501 according to the second embodiment has the same configuration as the special shaped pipe 1 according to the first embodiment, except that it does not have an intermediate portion. Therefore, in the special shaped pipe 501 according to the second embodiment, for the configurations corresponding to the special shaped pipe 1 according to the first embodiment, symbols are added by adding "500" to the symbols assigned to each configuration of the special shaped pipe 1 according to the first embodiment, and explanations will be omitted as appropriate.

[0106] As shown in Figures 13 and 14, the irregular pipe 501 is a hollow molded body having a normal portion 502 having a predetermined cross-sectional circumference (cross-sectional circumference relating to a cross section perpendicular to the axial direction of the irregular pipe 501) and an irregular portion 503 connected to the normal portion 502 and having a cross-sectional circumference longer than the cross-sectional circumference of the normal portion 502.

[0107] The braided structure of the irregular tube 501 is a two-layer structure consisting of an outer layer braided sleeve 512 placed on the outer periphery of the irregular tube 501 and an inner layer braided sleeve 513 placed on the inner periphery of the irregular tube 501 (see Figure 15).

[0108] In the profiled pipe 501 of the second embodiment, seamless tubular braided sleeves (inner layer braided sleeve 513, outer layer braided sleeve 512) with a highly elastic and high thread density braided structure are seamlessly and integrally arranged across the normal portion 502 and the profiled portion 503 of the profiled pipe 501. Therefore, the braided sleeves are arranged with little fiber bias and at high density inside the resin molded body, whose cross-sectional circumference varies, throughout the entire longitudinal and circumferential directions of the profiled pipe 501. As a result, the resin molded body is reinforced with fibers uniformly and with little bias, resulting in a lightweight FRP profiled pipe 501 that maintains strength comparable to that of metal. Furthermore, the irregular pipe 501 can be formed as a continuous, integrated FRP molded product in which the normal portion 502 and the irregular portion 503, which have different cross-sectional circumferential lengths, are continuous. Therefore, there is no need to manufacture the normal portion 502 and the irregular portion 503 separately and connect them with joints or the like, and they can be formed efficiently.

[0109] (Relationship between the normal portion 502 and the irregular portion 503 and the braided sleeve) When the irregular pipe 501 has a normal portion 502 and an irregular portion 503 with different cross-sectional circumferences, as in the second embodiment, in the manufacturing process, a seamless tubular braided sleeve (inner layer braided sleeve 513, outer layer braided sleeve 512) having a braided structure with high elasticity and high thread density, as described above, is placed over the irregular pipe forming mandrel 521 having a shape corresponding to the shapes of the normal portion 502 and the irregular portion 503, and the braided sleeve expands and contracts in accordance with the change in shape of the irregular pipe forming mandrel 521.

[0110] However, since the irregularly shaped pipe 501 of this embodiment does not have an intermediate portion, a step will be formed between the normal portion 502 and the irregularly shaped portion 503 in the cross section of the irregularly shaped pipe 501 in the central axis direction X. In this step portion, the braided sleeve may be arranged in a curved state with a gradual change, as shown in Figure 15.

[0111] Furthermore, the relative ratio of cross-sectional perimeters, which is the difference between the cross-sectional perimeters of the normal portion 502 and the irregular portion 503 divided by the cross-sectional perimeter of the normal portion 502, is preferably 0.63 or less. The reason for this is that, as explained in the first embodiment above, if the relative ratio of cross-sectional perimeters is greater than 0.63, it may not be possible to uniformly arrange the braided sleeve over its entirety on the irregular pipe forming mandrel 21 during the manufacturing process.

[0112] (cover factor) In the case of the outer layer braided sleeve 512, by satisfying the condition that the values ​​of the normal portion cover factor cf1 (standard) and the irregular portion cover factor cf1 (irregular), calculated by the above (Equation 2), are within the range of 100% or less and 50% or more, the strength of the irregular pipe 501 as a whole can be suppressed from decreasing or having extreme strength imbalances, and the strength of the irregular pipe 501 itself can be maintained.

[0113] In the case of the inner layer braided sleeve 513, by satisfying the condition that the values ​​of the normal portion cover factor cf3 (standard) and the irregular portion cover factor cf3 (irregular), calculated by the above (Equation 4), are within the range of 100% or less and 50% or more, the reduction in strength of the entire irregular pipe 501 and extreme imbalances in strength can be suppressed, and the strength of the irregular pipe 501 itself can be maintained.

[0114] In addition, in the inner layer braid sleeve 513 and the outer layer braid sleeve 512 that constitute the irregular pipe 501, from the viewpoint of further enhancing the high rigidity and impact resistance of the irregular pipe 501, it is more preferable that the values ​​of the normal portion cover factor cf (standard) and the irregular portion cover factor cf (irregular) each satisfy the condition of being in the range of 100% or less and 60% or more. Furthermore, it is most preferable that the values ​​of the normal portion cover factor cf (standard) and the irregular portion cover factor cf (irregular) each satisfy the condition of being in the range of 100% or less and 70% or more.

[0115] In addition, it is preferable that the values ​​of the standard portion cover factor cf (standard) and the irregular portion cover factor cf (irregular) are similar (the difference between the maximum and minimum values ​​is within 10%) in order to suppress strength bias (strength difference) throughout the irregular pipe 501.

[0116] (Relationship between the orientation angle θ2 of the outer layer braiding yarns of the irregular portion 503 and the orientation angle θ1 of the outer layer braiding yarns of the normal portion 502 in the outer layer braid sleeve 512) In the outer layer braid sleeve 512, the orientation angle θ2 of the outer layer braid yarns in the irregular portion 503 and the orientation angle θ1 of the outer layer braid yarns in the normal portion 502 satisfy the relationship of the above formula 1.

[0117] (Manufacturing method of the irregular pipe 501) Next, we will explain the manufacturing method of the irregular pipe 501. The manufacturing method of the irregular pipe 501 is substantially the same as the manufacturing method of the irregular pipe 1 described above, except that the irregular pipe forming mandrel used does not have an intermediate portion forming portion, and therefore, the explanation will be omitted as appropriate.

[0118] That is, the manufacturing method of the irregular pipe 501 is similar to the manufacturing method of the irregular pipe 1 described above, and includes (1) a sleeve braiding process, (2) manufacturing a preform (coating process), (3) placing it in a mold, (4) a resin molding process (impregnation and hardening process), (5) removing the mandrel (removal process), and (6) finishing processing.

[0119] Then, in (2) the manufacturing (coating process) of the preliminary molded body (preform), as shown in Figure 16, a silicone resin irregular pipe forming mandrel 521 having a normal part forming portion 522 with an outer circumferential shape corresponding to the cross-sectional circumference of the normal part 502 of the irregular pipe 501 to be manufactured, and an irregular part forming portion 523 with an outer circumferential shape corresponding to the cross-sectional circumference of the irregular part 503, is covered in order with an inner layer braid sleeve 513 and an outer layer braid sleeve 512, which are expandable within the range from the minimum cross-sectional circumference to the maximum cross-sectional circumference of the irregular pipe forming mandrel 521 and have a constant diameter in the longitudinal direction when not expanded or contracted, to manufacture a preliminary molded body (hereinafter referred to as a preform) in which two layers of cylindrical braid sleeves are stacked. In this process, the outer layer braid sleeve 512 is placed over the irregular pipe forming mandrel 521 so that the orientation angle of the outer layer braiding yarns 121 relative to the central axis direction X of the irregular pipe 501 is in the range of ±5 to 85°, and the orientation angle θ2 of the outer layer braiding yarns 121 in the irregular section 503 satisfies the relationship of the above formula 1 with respect to the orientation angle θ1 of the outer layer braiding yarns 121 in the normal section 502.

[0120] According to the above manufacturing method, the braided sleeves (the inner layer braided sleeve 513 and the outer layer braided sleeve 512) having a tubular braided structure are stretchable within a range from the minimum cross-sectional circumferential length to the maximum cross-sectional circumferential length of the irregular pipe forming mandrel 521. Therefore, the braided sleeve can be integrally and continuously covered from the normal portion forming portion 522 to the irregular portion forming portion 523 of the irregular pipe forming mandrel 521 while following the change in the cross-sectional circumferential length of the irregular pipe forming mandrel 21 and while being uniformly disposed over the entire irregular pipe forming mandrel 21. This allows the braided sleeve to be uniformly disposed on the profiled pipe forming mandrel 521 and subjected to a resin molding process (impregnation and curing process).

[0121] Here, since there are no seams in the braided sleeves (braided sleeve for inner layer 513 and braided sleeve for outer layer 512), it is possible to produce an irregularly shaped pipe 501 with less strength imbalance across the normal portion 502 and the irregularly shaped portion 503 compared to when the braided sleeves have seams. Furthermore, since the braided sleeve has a braided structure, that is, is a braid made of braided yarns, the braided yarns can be arranged more densely than when the sleeve is a knitted fabric made of knitted yarns. As a result, the irregular shaped pipe 501 can have little unevenness in strength over the entire length and circumferential direction of the irregular shaped pipe 501. Furthermore, when the orientation angle θ2 of the outer layer braiding yarns of the irregularly shaped portion 503 in the outer layer braid sleeve 512 satisfies the relationship of (Equation 1) with respect to the orientation angle θ1 of the outer layer braiding yarns of the regular portion 502, the difference between the physical properties of the regular portion 502 and the physical properties of the irregularly shaped portion 503 becomes small. This makes the physical properties of the regular portion 502 and the irregularly shaped portion 503 nearly uniform, thereby improving the homogeneity of the regular portion 502 and the irregularly shaped portion 503, and as a result, it is possible to accommodate irregularly shaped pipes 501 of a wide range of shapes.

[0122] As a result of the above, the resin molded bodies of the normal portion 502 and the irregular-shaped portion 503 are reinforced with fibers uniformly with little bias, resulting in an irregular-shaped pipe 501 made of FRP that is lightweight while maintaining strength comparable to that of metal. Furthermore, the irregular pipe 501 can be formed as a continuous, integrated FRP molded product with the normal portion 502 and the irregular portion 503. Therefore, there is no need to manufacture the normal portion 502 and the irregular portion 503 separately and connect them with joints or the like, and they can be formed efficiently.

[0123] (Other embodiments) In the second embodiment, as in the first embodiment, the irregular pipe 1501 can also be described as a hollow molded body having a normal portion 1502 having a predetermined cross-sectional shape (a cross-sectional shape relating to a cross section perpendicular to the axial direction of the irregular pipe 1501) and an irregular portion 1503 having a cross-sectional shape different from the cross-sectional shape of the normal portion 1502 (see Figures 13 and 14). In this case, the irregularly shaped pipe 1501 can be explained by replacing the "cross-sectional perimeter" of the normal portion 502 and the irregularly shaped portion 503 in the above embodiment with the "cross-sectional shape."

[0124] Furthermore, the manufacturing method of the irregular pipe 1501 is similar to the manufacturing method of the irregular pipe 501 described above, but in "(2) Manufacturing of preform (coating process)", an irregular pipe forming mandrel 1521 made of silicone resin, which has a normal part forming portion 1522 having an outer circumferential shape corresponding to the cross-sectional shape of the normal part 1502 of the irregular pipe 1501 to be manufactured, and an irregular part forming portion 1523 having an outer circumferential shape corresponding to the cross-sectional shape of the irregular part 1503, is covered in order with an inner layer braid sleeve 513 and an outer layer braid sleeve 512, which can expand and contract from the outer circumferential shape of the normal part forming portion 1522 of the irregular pipe forming mandrel 1521 to the outer circumferential shape of the irregular part forming portion 1523, and which have a constant diameter in the longitudinal direction when not expanded and contracted, to produce a preform consisting of two layers of tubular braid sleeves. In this process, the outer layer braid sleeve 512 is placed over the irregular pipe forming mandrel 1521 so that the orientation angle of the outer layer braiding yarns 121 relative to the central axis direction X of the irregular pipe 1501 is in the range of ±5 to 85°, and the orientation angle θ2 of the outer layer braiding yarns 121 in the irregular section 1503 satisfies the relationship of the above (Equation 1) with respect to the orientation angle θ1 of the outer layer braiding yarns 121 in the normal section 1502.

[0125] According to the above manufacturing method, the braided sleeves (the inner layer braided sleeve 513 and the outer layer braided sleeve 512) having a tubular braided structure can expand and contract to fit the outer peripheral shape of the normal portion forming portion 1522 of the irregular pipe forming mandrel 1521 to the irregular portion forming portion 1523. Therefore, the braided sleeve can be integrally and continuously covered from the normal portion forming portion 1022 to the irregular portion forming portion 1523 of the irregular pipe forming mandrel 1521, following the changes in the cross-sectional shape of the irregular pipe forming mandrel 1521, and being uniformly arranged over the entire irregular pipe forming mandrel 21. This allows the braided sleeve to be uniformly disposed on the profiled pipe forming mandrel 1521 and subjected to a resin molding process (impregnation and curing process).

[0126] Furthermore, as in the above embodiment, the braided sleeves (braided sleeve for inner layer 513 and braided sleeve for outer layer 512) have no seams, so the irregular pipe 1501 can have less strength imbalance across the normal portion 1502 and the irregular portion 1503 compared to when the braided sleeves have seams. Furthermore, since the braided sleeve has a braided structure, that is, is a braid made of braided yarns, the braided yarns can be arranged more densely than when the sleeve is a knitted fabric made of knitted yarns. As a result, the irregular shaped pipe 1501 can have little unevenness in strength over the entire length and circumferential direction of the irregular shaped pipe 1501. Furthermore, when the orientation angle θ2 of the outer layer braiding yarns of the irregularly shaped portion 1503 in the outer layer braid sleeve 512 satisfies the relationship of (Equation 1) with respect to the orientation angle θ1 of the outer layer braiding yarns of the regular portion 1502, the difference between the physical properties of the regular portion 1502 and the physical properties of the irregularly shaped portion 1503 becomes small. This makes the physical properties of the regular portion 1502 and the irregularly shaped portion 1503 nearly uniform, thereby improving the homogeneity of the regular portion 1502 and the irregularly shaped portion 1503, and as a result, it is possible to accommodate irregularly shaped pipes 1501 of a wide range of shapes.

[0127] Furthermore, in the above second embodiment, the irregular pipe 501 was configured to have one normal portion 502 and one irregular portion 503, but this configuration is not limited to this, and for example, the irregular pipe may be configured to have a normal portion, an irregular portion, and another normal portion in this order.

[0128] Although the embodiments of the present invention have been described above, they are merely illustrative examples and do not particularly limit the present invention, and the specific configurations of each means etc. can be appropriately modified in design. Furthermore, the effects described in the embodiments of the present invention are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention. [Example]

[0129] [Verification based on Examples 1 to 3 and Comparative Examples 1 to 4] The irregular-shaped pipe of the present invention, in which fiber components are arranged densely and with little fiber bias throughout the entire longitudinal and circumferential directions of the resin molded body in which at least one of the cross-sectional circumference and cross-sectional shape changes, has a small difference between the physical properties of the normal portion and the physical properties of the irregular-shaped portion, and maintains a high level of mechanical properties in the axial direction.

[0130] Therefore, in this example, special-shaped pipes according to Examples 1 to 3 and Comparative Examples 1 to 4 were produced, and comparative verification was carried out by measuring the tensile modulus of the special-shaped pipes and the breaking strength of the special-shaped pipes. The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0131] (Configuration of irregular pipes) <High-strength fiber used in the braided structure of irregularly shaped pipes> Table 1 lists the high-strength fibers (carbon fibers) used in the braided structure of the irregular shaped pipe. [Table 1]

[0132] (Elastic thread used in the braided structure of irregularly shaped pipes) Table 2 lists the elastic yarns (polyamide fibers) used in the braided structure of the irregular shaped pipe. [Table 2]

[0133] (Resin composition used for resin molded body of irregular shaped pipe) Thermosetting resin: Vinyl ester resin (brand CBZ500LM-AS, viscosity 200-350 mPa·s, manufactured by Japan U-Pica) Accelerator: PR-CBZ01 (made by U-Pica Japan) Hardener: 328E (manufactured by Nouryon Chemical Co., Ltd.)

[0134] (Manufacturing method for special-shaped pipes (test specimens)) Using the "manufacturing method for irregular pipe 1" described in the above embodiment, irregular FRP pipes with braided structures described in Examples 1 to 3 and Comparative Examples 1 to 4 shown in Table 3 were produced. The irregular pipes produced had one normal section, one intermediate section, and one irregular section, in that order. The "allowable orientation angle (°)" in Table 3 indicates the upper limit of the allowable orientation angle θ2 of the braided yarns in the irregular section in the outer layer braided sleeve, calculated from the above (Equation 1). If the orientation angle θ2 of the braided yarns in the irregular section in the outer layer braided sleeve was equal to or less than the allowable orientation angle, it was rated as "a," and if it was greater than the allowable orientation angle, it was rated as "b."

[0135] (Braided structure of irregular shaped pipe) [Table 3]

[0136] (Test Method) <Method for measuring the tensile modulus of irregular shaped pipes> Test pieces measuring L 50 mm x W 5 mm x 1.5 mm were taken from each of the normal and irregular parts of the irregular pipe produced by the above method using the water jet method. Then, test pieces taken from the normal and irregular parts of the irregular pipe were subjected to tensile tests at a speed of 1 mm / min in an environment of 23±2°C and 50±10% humidity in accordance with JIS K7164 (2005), and the tensile modulus E was calculated from the obtained stress-strain curve using (Equation 5).

[0137]

number

[0138] In this test, the area where the slope is linear is used as the strain reading range. σ1: Tensile stress measured at strain ε1 = 0.0025 (MPa) σ2: Tensile stress measured at strain ε2 = 0.0050 (MPa) The tensile modulus E was calculated using equation (5).

[0139] <Method for measuring the breaking strength of irregular shaped pipes> For irregular-shaped pipes, test pieces were taken from the normal and irregular-shaped parts in the same manner as in the above [Method for measuring the tensile modulus of irregular-shaped pipes], and a tensile test was carried out at a speed of 1 mm / min in an environment of a temperature of 23±2°C and a humidity of 50±10% in accordance with JIS K7164 (2005). The tensile stress (test force: F) at which the test piece broke was measured, and the breaking strength was calculated using (Equation 6). (The test was carried out three times for each.)

[0140]

number

[0141] (Regarding test results) <Criteria for determining whether or not a special-shaped pipe is acceptable> In order to accommodate a wide range of shapes of FRP shaped pipes, it is desirable that the difference between the physical properties (mechanical strength) of the regular part and the physical properties (mechanical strength) of the irregular part be small, and that the regular part and the irregular part be highly homogeneous. Therefore, the relative ratio of the tensile modulus of elasticity was calculated as an index to evaluate the homogeneity of the regular part and the irregular part, and ranked according to the following criteria. A rating: Relative ratio of tensile modulus of elasticity is 0.25 or less (25% or less) b: The relative ratio of tensile modulus is greater than 0.25 (greater than 25%)

[0142] In addition, the relative ratio of fracture strength was calculated as another index for evaluating the homogeneity of the normal part and the irregular part, and the parts were ranked according to the following criteria. a rating: The relative ratio of breaking strength is 0.25 or less (25% or less) b: The relative ratio of fracture strength is greater than 0.25 (greater than 25%)

[0143] The overall evaluation was ranked as A (pass), B (pass), or C (fail) according to the evaluation criteria in Table 4 below.

[0144] [Table 4]

[0145] <Test results for special-shaped pipes> (Evaluation of orientation angle (Table 3)) [Example 1] The orientation angle θ2 of the braided yarns in the irregular portion of the outer layer braided sleeve relative to the orientation angle θ1 of the braided yarns in the normal portion satisfied the relationship in Equation 1 above (rating a). In addition, the relative ratio of the tensile modulus of elasticity was 0.240 (rating a), and the relative ratio of the breaking strength was 0.238 (rating a), resulting in an overall rating of A rank (pass).

[0146] [Example 2] The orientation angle θ2 of the braided yarns in the irregular portion of the outer layer braided sleeve relative to the orientation angle θ1 of the braided yarns in the normal portion satisfied the relationship in Equation 1 above (rating a). In addition, the relative ratio of the tensile modulus of elasticity was 0.179 (rating a), and the relative ratio of the breaking strength was 0.178 (rating a), resulting in an overall rating of A rank (pass).

[0147] [Example 3] The orientation angle θ2 of the braided yarns in the irregular portion of the outer layer braided sleeve relative to the orientation angle θ1 of the braided yarns in the normal portion satisfied the relationship in Equation 1 above (rating a). In addition, the relative ratio of the tensile modulus of elasticity was 0.095 (rating a), and the relative ratio of the breaking strength was 0.076 (rating a), resulting in an overall rating of A rank (pass).

[0148] [Comparative Example 1] When manufacturing a preform consisting of two layers of tubular braided sleeves, the outer layer braided sleeve 12 could not be placed over the irregular shape forming section 23 of the irregular shape pipe forming mandrel 21, and the preform could not be manufactured, so the overall evaluation was C rank (failed).

[0149] Comparative Example 2 The orientation angle θ2 of the braided yarns in the irregular portion of the outer layer braided sleeve did not satisfy the relationship in Equation 1 above with respect to the orientation angle θ1 of the braided yarns in the normal portion (evaluation b). In addition, the relative ratio of the tensile modulus of elasticity was 0.307 (evaluation b), and the relative ratio of the breaking strength was 0.353 (evaluation b), resulting in an overall evaluation of Rank B (failure).

[0150] Comparative Example 3 The orientation angle θ2 of the braided yarns in the irregular portion of the outer layer braided sleeve did not satisfy the relationship in Equation 1 above with respect to the orientation angle θ1 of the braided yarns in the normal portion (evaluation b). In addition, the relative ratio of the tensile modulus of elasticity was 0.290 (evaluation b), and the relative ratio of the breaking strength was 0.291 (evaluation b), resulting in an overall evaluation of Rank B (failure).

[0151] Comparative Example 4 The orientation angle θ2 of the braided yarns in the irregular portion of the outer layer braided sleeve did not satisfy the relationship in Equation 1 above with respect to the orientation angle θ1 of the braided yarns in the normal portion (evaluation b). In addition, the relative ratio of the tensile modulus of elasticity was 0.266 (evaluation b), and the relative ratio of the breaking strength was 0.275 (evaluation b), resulting in an overall evaluation of Rank B (failure).

[0152] From the above results, it was confirmed that in an FRP irregular pipe in which the orientation angle θ2 of the braided yarns in the irregular section of the outer layer braided sleeve satisfies the relationship (Equation 1) above relative to the orientation angle θ1 of the braided yarns in the normal section, the difference between the physical properties of the normal section and the irregular section is small, and the axial mechanical properties are maintained at a high level. [Explanation of symbols]

[0153] 1 Irregular tube 2 Normal part 3 Unusual part 12 Braided sleeve for outer layer 13 Braided sleeve for inner layer

Claims

1. An FRP deformed pipe in which a fiber member is embedded inside a resin molded body, a normal portion having a predetermined cross-sectional perimeter and a predetermined cross-sectional shape; a non-circumferential portion having at least one of a cross-sectional circumferential length longer than that of the normal portion and a cross-sectional shape different from that of the normal portion; and The fiber member has a tubular braided structure and is integrally disposed across the normal portion and the irregular-shaped portion, and the fiber member is formed by combining braided yarns oriented at an orientation angle in the range of ±5 to 85° with respect to the central axis of the irregularly shaped pipe, A modified pipe, characterized in that the orientation angle θ2 of the braided yarn in the modified portion satisfies the following relationship with the orientation angle θ1 of the braided yarn in the normal portion: [Equation 1]

2. The irregular pipe according to claim 1, characterized in that the relative ratio of the tensile modulus of elasticity, which is the difference between the tensile modulus of the irregularly shaped portion and the tensile modulus of the normal portion divided by the tensile modulus of the normal portion, is 0.25 or less.

3. The irregular pipe according to claim 1, characterized in that the relative fracture strength ratio, which is the difference between the fracture strength of the irregular portion and the fracture strength of the normal portion divided by the fracture strength of the normal portion, is 0.25 or less.

4. A method for manufacturing a deformed pipe made of FRP in which a fiber member is embedded inside a resin molded body, The irregularly shaped pipe has a normal portion having a predetermined cross-sectional circumferential length and an irregularly shaped portion having a cross-sectional circumferential length longer than the cross-sectional circumferential length of the normal portion, a mandrel having a normal portion forming portion having an outer circumferential shape corresponding to the cross-sectional circumferential length of the normal portion and an irregular portion forming portion having an outer circumferential shape corresponding to the cross-sectional circumferential length of the irregular portion; a covering step of covering the mandrel with a sleeve formed by combining braided yarns, the sleeve being stretchable at least within a range from the minimum cross-sectional perimeter to the maximum cross-sectional perimeter of the mandrel and having a constant diameter in the longitudinal direction when not stretched and having a tubular braided structure made of the fiber member; an impregnation and curing step of impregnating the sleeve with a resin and curing the resin after the covering step; and removing the mandrel after the resin has hardened. A method for manufacturing an irregularly shaped pipe, characterized in that in the covering step, the braided yarn is oriented at an orientation angle in the range of ±5 to 85° with respect to the central axial direction of the irregularly shaped pipe, and the sleeve is placed on the mandrel while the orientation angle θ2 of the braided yarn in the irregularly shaped portion satisfies the following relationship with the orientation angle θ1 of the braided yarn in the normal portion: [Equation 2]

5. A method for manufacturing a deformed pipe made of FRP in which a fiber member is embedded inside a resin molded body, The irregular-shaped pipe has a normal portion having a predetermined cross-sectional shape and an irregular-shaped portion having a cross-sectional shape different from the cross-sectional shape of the normal portion, a mandrel having a normal portion forming portion having an outer circumferential shape corresponding to the cross-sectional shape of the normal portion and an irregular portion forming portion having an outer circumferential shape corresponding to the cross-sectional shape of the irregular portion, a covering step of covering the fiber member with a sleeve formed by combining braided yarns, the sleeve being stretchable from at least the outer peripheral shape of the normal portion forming portion to the outer peripheral shape of the irregularly shaped portion forming portion and having a constant diameter in the longitudinal direction when not stretched and having a tubular braided structure; an impregnation and curing step of impregnating the sleeve with a resin and curing the resin after the covering step; and removing the mandrel after the resin has hardened. A method for manufacturing an irregularly shaped pipe, characterized in that in the covering step, the braided yarn is oriented at an orientation angle in the range of ±5 to 85° with respect to the central axial direction of the irregularly shaped pipe, and the sleeve is placed on the mandrel while the orientation angle θ2 of the braided yarn in the irregularly shaped portion satisfies the following relationship with the orientation angle θ1 of the braided yarn in the normal portion: [Equation 3]

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