Profiled pipe

Abstract

To provide a deformed pipe made of FRP in which a fiber member is embedded in a resin molded body, and in which the fiber member is arranged in the resin molded body of which the cross-sectional peripheral length and the cross-sectional shape are changed over the whole in the longitudinal direction and the peripheral direction of the deformed pipe with little deviation and high density, and to provide a method for manufacturing the same.SOLUTION: A deformed pipe 1 made of FRP in which a braided sleeve (a braided sleeve 13 for an inner layer and a braided sleeve 12 for an outer layer) is embedded inside a resin molded body includes a normal portion 2 having a predetermined cross-sectional circumferential length and a deformed portion 3 connected to the normal portion 2 and having a cross-sectional circumferential length longer than the cross-sectional circumferential length of the normal portion 2, and the braided sleeve has a tubular braided structure and is integrally disposed over the normal portion 2 and the deformed portion 3.SELECTED DRAWING: Figure 1

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 a special-shaped pipe made of FRP, 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. To achieve this, it is necessary to uniformly arrange the fiber members embedded inside the resin molding of the special-shaped pipe made of FRP 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] 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. [Means for solving the problem]

[0014] 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-circular portion connected to the normal portion and having at least one of a cross-sectional perimeter 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 characterized in that it is integrally disposed across the normal portion and the irregular-shaped portion.

[0015] 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.

[0016] Furthermore, the present invention may be characterized in that, in the above-mentioned irregularly shaped pipe, when there is a difference between the cross-sectional circumference of the normal portion and the cross-sectional circumference of the irregularly shaped portion, the cross-sectional circumference relative ratio, which is the value obtained by dividing the difference between the cross-sectional circumference of the normal portion and the cross-sectional circumference of the irregularly shaped portion by the cross-sectional circumference of the normal portion, is 0.63 or less.

[0017] According to the above configuration, the braided fiber member can be uniformly arranged throughout the entire irregular-shaped pipe, and can be arranged more precisely and integrally and continuously from the normal portion to the irregular-shaped portion, resulting in an irregular-shaped pipe with no uneven strength throughout the normal portion and the irregular-shaped portion.

[0018] Further, in the above-mentioned irregularly shaped pipe, the fiber material includes a braided sleeve formed by combining braided yarns oriented at an orientation angle with respect to the central axis direction of the irregularly shaped pipe in a range of ±5 to 85°, In the braided sleeve, The width of the braid is b f [mm], The number of the braided yarns is n [pieces], The inner diameter of the braided sleeve is D [mm], The orientation angle of the braided yarn with respect to the central axis of the irregular tube is θ [°], The present invention may be characterized in that the value of a cover factor cf1, which indicates the ratio of the surface area of ​​the braided yarn to the surface area of ​​the braided sleeve, for each of the normal portion and the irregular-shaped portion, is calculated by the following (Equation 1) when

number

[0019] According to the above configuration, the rigidity and impact resistance of the specially shaped pipe can be improved.

[0020] Further, the present invention provides the above-mentioned irregularly shaped pipe, wherein the fiber member includes a braided sleeve formed by combining an axial yarn oriented in the central axis direction of the irregularly shaped pipe and a braided yarn oriented at an orientation angle in the range of ±5 to 85° with respect to the central axis direction of the irregularly shaped pipe, In the braided sleeve, The width of the braid is b f [mm], The number of the braided yarns is n [pieces], The inner diameter of the braided sleeve is D [mm] The orientation angle of the braided yarn with respect to the central axis of the irregular tube is θ [°], The width of one cell of the braided sleeve is f [mm], The width of the axon is b m [mm], The braided sleeve may be characterized in that the values ​​of a cover factor cf3, which indicates the proportion of the surface area of ​​the braided yarns and the axial yarns in the normal portion and the irregular portion, respectively, calculated by the following (Equation 2) when

number

[0021] According to the above configuration, the rigidity and impact resistance of the specially shaped pipe can be improved.

[0022] Furthermore, the present invention may be characterized in that, in the above-mentioned irregularly shaped pipe, the fiber material is formed by combining an axial yarn oriented in the central axis direction of the irregularly shaped pipe and a braided yarn oriented at an orientation angle relative to the central axis direction of the irregularly shaped pipe in the range of ±5 to 85°.

[0023] According to the above configuration, the mechanical properties of the shaped pipe in the axial direction can be improved.

[0024] 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 pipe has a normal portion having a predetermined cross-sectional circumferential length, and an irregular portion connected to the normal portion and 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 fiber member with a sleeve having a cylindrical braided structure, the sleeve being stretchable at least within a range from the minimum cross-sectional circumferential length to the maximum cross-sectional circumferential length of the mandrel and having a constant diameter in the longitudinal direction when not stretched; an impregnation and curing step of impregnating the sleeve with a resin and curing the resin after the covering step; and a removing step of removing the mandrel after the resin has hardened.

[0025] 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. 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.

[0026] 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 pipe has a normal portion having a predetermined cross-sectional shape, and an irregular portion connected to the normal portion and 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 process in which the fiber member is covered with a sleeve having a tubular braided structure, 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; an impregnation and curing step of impregnating the sleeve with a resin and curing the resin after the covering step; and a removing step of removing the mandrel after the resin has hardened.

[0027] 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. 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]

[0028] 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. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 2 is a perspective view of a specially shaped pipe according to the present embodiment. [Figure 2] 1A and 1B are a plan view and a cross-sectional view of a special-shaped pipe according to the present embodiment. [Figure 3] 1A is a cross-sectional view of a braided sleeve according to the present embodiment, and FIG. 1B is an explanatory view of a two-layer structure of the braided sleeve according to the present 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] 10 is a cross-sectional view illustrating the placement of a braided sleeve on a mandrel for forming a shaped pipe. 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 diagram of a mandrel for forming a shaped pipe according to the present 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. DETAILED DESCRIPTION OF THE INVENTION

[0030] (Embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0031] (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 and an irregular portion 3 connected to the normal portion 2, 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).

[0032] 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 this 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.

[0033] 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).

[0034] (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 and the irregularly shaped portion 3.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] In this embodiment, as shown in Figure 3(A), the braided structure of the irregular pipe 1 is 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.

[0039] (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°.

[0040] 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.

[0041] 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.

[0042] 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).

[0043] 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.

[0044] 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.

[0045] 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.

[0046] (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.

[0047] 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.

[0048] (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.

[0049] In the profiled pipe 1 of this embodiment, seamless tubular braided sleeves (inner layer braided sleeve 13, outer layer braided sleeve 12) with a braided structure that is highly elastic and has a high thread density are seamlessly and integrally arranged across the normal portion 2 and the profiled portion 3 of the profiled pipe 1. 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 1. As a result, the resin molded body is reinforced with fibers uniformly and with little bias, and a lightweight FRP profiled pipe 1 is obtained 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 portion 2 and an irregular portion 3, each having a different cross-sectional circumferential length. This eliminates the need to manufacture the normal portion 2 and the irregular portion 3 separately and connect them with joints or the like, allowing for efficient formation.

[0050] 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.

[0051] (Relationship between normal part 2, irregular part 3 and braided sleeve) In the case where the irregular pipe 1 has a normal portion 2 and an irregular portion 3 with different cross-sectional circumferences, as in this 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) having a braided structure with high elasticity and 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 and the irregular portion 3, the braided sleeve expands and contracts in accordance with the change in shape of the irregular pipe forming mandrel 21.

[0052] Here, when covering the irregular pipe forming mandrel 21 having a shape corresponding to the normal portion 2 and the irregular portion 3 with a braided sleeve, in order to uniformly arrange the braided sleeve on the irregular pipe forming mandrel 21 and cover the irregular 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 irregular pipe forming mandrel 21 (high adhesion of the braided sleeve to the irregular pipe forming mandrel 21).

[0053] Therefore, 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. In other words, 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 arranged on the irregular pipe forming mandrel 21 in this way, a strength imbalance may occur in the region of the manufactured irregular pipe 1 between the regular portion 2 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 and the irregular portion 3, 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 adheres closely to the irregular pipe forming mandrel 21). This allows the braided sleeve to be uniformly disposed over the entire irregular pipe forming mandrel 21. That is, when the braided sleeve is placed on the irregular pipe forming mandrel 21, the braided sleeve can be prevented from becoming loose when the braided sleeve is placed on the normal portion 2 with the shorter cross-sectional circumference. Furthermore, when the braided sleeve is placed on the irregular pipe forming mandrel 21 with the shorter cross-sectional circumference, the braided sleeve can be properly placed on the irregular pipe forming mandrel 21 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 and the shaped portion 3.

[0055] In addition, in the cross section of the shaped pipe 1 of this embodiment taken along the central axis direction X of the shaped pipe 1, a step is formed between the normal portion 2 and the shaped portion 3. In this step portion, the braided sleeve may be arranged in a curved state with a gentle change, as shown in Figure 6.

[0056] (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 and the irregular portion 3, 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 and the irregular portion 3 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).

[0057] Therefore, as an indicator of the elasticity of the braided sleeve to follow the shapes of the regular portion 2 and the irregular portion 3 of the irregular pipe 1 while maintaining the desired strength, the braided structure of each portion of the braided inner layer sleeve 13 and the braided outer layer sleeve 12 corresponding to the regular portion 2 and the irregular portion 3 of the irregular pipe 1 may be formed using an indicator (value) called the cover factor cf (Equations 1 to 3), which indicates the proportion of the surface area of ​​the braided inner layer braided sleeve 13 and the braided 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).

[0058] 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) and the irregular portion cover factor cf (irregular) of the inner layer braided sleeve 13 and the outer layer braided sleeve 12, which correspond to the normal portion 2 and the irregular portion 3 that make up the irregular pipe 1, can be calculated, respectively. 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).

[0059] (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 fThe normal portion cover factor cf1 (standard) and the irregular portion cover factor cf1 (irregular) of the outer layer braid sleeve 12 corresponding to the normal portion 2 and the irregular portion 3 are calculated from values ​​based on two-dimensional data such as the length n [mm] of the outer layer braided sleeve 12, the number n [pieces] of the 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, using the following (Equation 1).

[0060]

number

[0061] 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) and the irregular portion cover factor cf1 (irregular) calculated by the above (Equation 1) 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.

[0062] (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, as in the case of the inner layer braided sleeve 13 shown in FIG. 4, and a cell (see FIG. 4(B)) composed of a braided structure having an inner layer braid 131 and an axial yarn 132, the cover factor cf3 is calculated taking into account the cover factor cf1 (calculated in the same manner as for the outer layer braided sleeve 12: see Equation 1) for the cell shown in FIG. 4(A) whose braided structure is composed only of the inner layer braid 131, and the cover factor cf2 for the cell shown in FIG. 4(B) whose braided structure is composed of the inner layer braid 131 and an axial yarn 132.

[0063] 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) and irregular portion cover factor cf2 (irregular) of the inner layer braid sleeve 13 corresponding to the normal portion 2 and irregular portion 3 are calculated using the following (Equation 3).

[0064]

number

[0065] 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.

[0066] In calculating the value of the cover factor cf3 when the cell (see FIG. 4(A)) includes a braided structure composed only of the inner layer braid 131, and the cell (see FIG. 4(B)) includes a braided structure having the inner layer braid 131 and an axial yarn 132, as in the inner layer braided sleeve 13, the cover factor cf1 for the cell whose braided structure is composed only of the inner layer braid 131 shown in FIG. 4(A) and the cover factor cf2 for the cell whose braided structure is composed of the inner layer braid 131 and an axial yarn 132 shown in FIG. 4(B) are taken into consideration. The values ​​of the standard portion cover factor cf3 (standard) and the irregular portion cover factor cf3 (irregular) are calculated using the following (Equation 2), which takes into account the cover factor cf1 for the cell whose braided structure is composed only of the inner layer braid 131 shown in FIG. 4(A) and the cover factor cf2 for the cell whose braided structure is composed of the inner layer braid 131 and an axial yarn 132 shown in FIG. 4(B). The values ​​of the standard portion cover factor cf3 (standard) and the irregular portion cover factor cf3 (irregular) are set to satisfy the condition of being in the range of 100% to 50% from the viewpoint of high rigidity for the entire irregular pipe 1. This suppresses a decrease in the strength of the entire irregular pipe 1 and extreme imbalances in strength, and maintains the strength of the irregular pipe 1 itself.

[0067] 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 across the normal portion 2 and the irregular portion 3 of the irregular pipe 1.

[0068]

number

[0069] As described above, the values ​​of the standard portion cover factor cf (standard) and the irregular portion cover factor cf (irregular) of the inner layer braided sleeve 13 and the outer layer braided sleeve 12, which correspond to the standard portion 2 and irregular portion 3 constituting the irregular pipe 1, are set to satisfy the condition of being in the range of 100% or less and 50% or more. This is because if the values ​​of the standard portion cover factor cf (standard) and the irregular portion cover factor cf (irregular) 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 the axial yarn 132, and part of the outer layer braided yarn 121, the inner layer braided yarn 131, and the 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) and the irregular portion cover factor cf (irregular) are each less than 50%, the spacing between the inner layer braided sleeve 13 in the standard 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.

[0070] 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) 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.

[0071] Furthermore, it is preferable that the values ​​of the normal portion cover factor cf (standard) and the irregular portion cover factor cf (irregular) 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% and the value of the irregular part cover factor cf (irregular) is 89%, then it can be said that the respective values ​​are approximately the same (the difference between the maximum and minimum values ​​is within 10%). In this way, by making the values ​​of the standard portion cover factor cf (standard) and the irregular portion cover factor cf (irregular) approximately the same, the spacing between the inner layer braided sleeve 13 in the standard 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 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.

[0072] (Method of manufacturing the irregular pipe 1) Next, a method for manufacturing the shaped pipe 1 will be described.

[0073] (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.

[0074] 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.

[0075] 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.

[0076] (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 circumferential shape corresponding to the cross-sectional circumference of the normal portion 2 of the irregular pipe 1 to be manufactured, and an irregular portion forming portion 23 with an outer circumferential 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.

[0077] In this 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.

[0078] (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.

[0079] (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.

[0080] (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.

[0081] (6) Finishing Finally, deburring, cutting, and painting are performed to obtain the special-shaped pipe 1 (see FIG. 1).

[0082] 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 to the irregular portion forming portion 23 of the irregular pipe forming mandrel 21 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).

[0083] 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 irregular pipe 1 with less strength imbalance across the normal portion 2 and the irregular 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.

[0084] As a result of the above, the resin molded bodies of the normal portion 2 and the irregular-shaped portion 3 are reinforced with fibers uniformly with little bias, and an irregular-shaped pipe 1 made of FRP is obtained 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 with the normal portion 2 and the irregular portion 3. Therefore, there is no need to manufacture the normal portion 2 and the irregular portion 3 separately and connect them with joints or the like, and the pipe can be formed efficiently.

[0085] (Other embodiments) (1) In the above 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.

[0086] 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.

[0087] 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). In this case, the irregularly shaped pipe 1001 can be explained by replacing the "cross-sectional perimeter" of the normal portion 2 and the irregularly shaped portion 3 in the above embodiment with the "cross-sectional shape."

[0088] 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)", an irregular pipe forming mandrel 1021 made of silicone resin, which has a normal part forming portion 1022 having an outer circumferential shape corresponding to the cross-sectional shape of the normal part 1002 of the irregular pipe 1001 to be manufactured, and an irregular part forming portion 1023 having an outer circumferential shape corresponding to the cross-sectional shape of the irregular part 1003, is covered in order with an inner layer braid sleeve 13 and an outer layer braid sleeve 12, which can expand and contract from the outer circumferential shape of the normal part forming portion 1022 of the irregular pipe forming mandrel 1021 to the outer circumferential shape of the irregular part forming portion 1023, and which have a constant diameter in the longitudinal direction when not expanded and contracted, to manufacture a preform consisting of two layers of tubular braid sleeves.

[0089] 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 to the irregular portion forming portion 1023 of the irregular pipe forming mandrel 1021, following the changes in the cross-sectional shape of the irregular pipe forming mandrel 1021, and being uniformly arranged over the entire irregular pipe forming 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).

[0090] Furthermore, as in the above embodiment, 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 1001 with less strength imbalance across the normal portion 1002 and the irregularly shaped 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.

[0091] (2) In the above embodiment, the irregular shaped pipe 1 is described as a pipe whose central axis direction X is straight, but it may have a curved portion.

[0092] (3) In the above 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.

[0093] 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 and an irregular portion 203, 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.

[0094] (4) In the above embodiment, the shapes of the regular portion and the irregular 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 regular portion with 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 with an equivalent circle diameter different in size from the equivalent circle diameter of the regular portion.

[0095] (5) In the above embodiment of the irregular pipe 1, an example of a braided structure 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 has been described. However, 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, either one layer of the braided sleeve for the inner layer 13 or the braided sleeve for the outer layer 12 described in the above embodiment may be used as the braided sleeve.

[0096] 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.

[0097] (6) With regard to the braided sleeve having a cylindrical braided structure of the irregular pipe 1 of the above 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.

[0098] Furthermore, the above 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.

[0099] Furthermore, in the above embodiment, if a set of braided sleeves is made up of an inner layer braided sleeve 13 (1 piece) and an outer layer braided sleeve 12 (1 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 a deformed pipe may be constructed by stacking multiple sets of braided sleeves. 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.

[0100] Furthermore, in the above embodiment, the irregular pipe 1 was configured to have one normal portion 2 and one irregular portion 3, 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 that order.

[0101] 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]

[0102] [Verification based on Examples 1 to 14 and Comparative Examples 1 and 2] The irregular pipe of the present invention, in which fiber components are arranged at high density with little fiber bias throughout the entire longitudinal and circumferential directions of the irregular pipe inside a resin molded body in which at least one of the cross-sectional circumference and cross-sectional shape changes, maintains a high level of mechanical properties in the axial direction.

[0103] Therefore, in this example, special-shaped pipes according to Examples 1 to 14 and Comparative Examples 1 and 2 were produced, and comparative verification was carried out by measuring the tensile modulus of the special-shaped pipes and measuring 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.

[0104] (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]

[0105] (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]

[0106] (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.)

[0107] (Manufacturing method for special-shaped pipes (test specimens)) Using the "method for manufacturing a non-circular pipe" described in the above embodiment, non-circular pipes made of FRP and having the braided structure described in Examples 1 to 14 and Comparative Examples 1 and 2 shown in Table 3 were produced. The non-circular pipes produced had one normal portion and one non-circular portion connected to the normal portion.

[0108] (Braided structure of irregular shaped pipe) [Table 3]

[0109] (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 4).

[0110]

number

[0111] 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 (4).

[0112] <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 5). (The test was carried out three times for each.)

[0113]

number

[0114] (Regarding test results) <Criteria for determining whether or not a special-shaped pipe is acceptable> Since FRP shaped pipes are often used as replacements for metal parts (e.g., aluminum alloys), from the perspective of replacing aluminum alloys, they are deemed to pass if they maintain the strength characteristics (elastic modulus) equivalent to aluminum alloys. The tensile modulus of the shaped pipes was calculated in the tensile test described above and ranked according to the following criteria. A rating: Tensile modulus of elasticity 43 GPa or more b: Tensile modulus of elasticity is 30 GPa or more and less than 43 GPa C rating: Tensile modulus of elasticity less than 30 GPa

[0115] Furthermore, since FRP shaped pipes are expected to be used as structural components for large drones, etc., their breaking strength is important. The breaking strength of the shaped pipes was calculated using the above-mentioned breaking test and ranked according to the following criteria. A rating: Breaking strength is 500 MPa or more b: Breaking strength is 400 MPa or more but less than 500 MPa C rating: Breaking strength less than 400 MPa

[0116] The overall evaluation was ranked as A (pass), B (pass), C (pass), or D (fail) according to the evaluation criteria in Table 4 below.

[0117] [Table 4]

[0118] <Test results for special-shaped pipes> (Layer structure evaluation (Table 3)) [Example 1: Example of a two-layer structure consisting of an inner layer formed of an axon yarn and braided yarns and an outer layer formed only of braided yarns] The tensile modulus of the normal part was 60.9 GPa (a rating), the tensile modulus of the irregular part was 46.3 GPa (a rating), the breaking strength of the normal part was 780 MPa (a rating), and the breaking strength of the irregular part was 594 MPa (a rating), and the overall rating was A rank (pass).

[0119] [Example 2: Example of a single-layer structure with an inner layer formed from braided yarn] The tensile modulus of the normal part was 46.3 GPa (rating a), the tensile modulus of the irregular part was 25.7 GPa (rating c), the breaking strength of the normal part was 421 MPa (rating b), and the breaking strength of the irregular part was 233 MPa (rating c), and the overall rating was C rank (pass).

[0120] [Example 3: Example of a single-layer structure consisting of an axis yarn and an inner layer formed of braided yarn] The tensile modulus of the normal part was 88.7 GPa (a rating), the tensile modulus of the irregular part was 88.7 GPa (a rating), the breaking strength of the normal part was 861 MPa (a rating), and the breaking strength of the irregular part was 861 MPa (a rating), and the overall rating was A rank (pass).

[0121] [Example 4: Example of a two-layer structure in which the outer layer is formed of an axon yarn and braided yarn, and the inner layer is formed only of braided yarn] The tensile modulus of the normal part was 60.8 GPa (a rating), the tensile modulus of the irregular part was 45.5 GPa (a rating), the breaking strength of the normal part was 751 MPa (a rating), and the breaking strength of the irregular part was 574 MPa (a rating), and the overall rating was A rank (pass).

[0122] (Evaluation of the difference between the cross-sectional perimeter of the normal part and the cross-sectional perimeter of the irregular part (Table 3)) [Comparative Example 1: Example where the relative ratio of cross-sectional perimeter is 0.91] When manufacturing a preform consisting of two layers of tubular braided sleeves, the outer layer braided sleeve 12 floated off the surface of the normal portion forming portion 22 of the mandrel 21 for forming the irregular pipe, and the preform could not be manufactured, so the overall evaluation was D rank (failed).

[0123] [Example 5: Example where the relative ratio of cross-sectional perimeter is 0.62] The tensile modulus of the normal part was 84.9 GPa (a rating), the tensile modulus of the irregular part was 60.9 GPa (a rating), the breaking strength of the normal part was 967 MPa (a rating), and the breaking strength of the irregular part was 780 MPa (a rating), and the overall rating was A rank (pass).

[0124] [Example 6: Example where the relative ratio of cross-sectional circumference is 0.52] The tensile modulus of the normal part was 78.3 GPa (a rating), the tensile modulus of the irregular part was 60.9 GPa (a rating), the breaking strength of the normal part was 918 MPa (a rating), and the breaking strength of the irregular part was 780 MPa (a rating), and the overall rating was A rank (pass).

[0125] [Example 7: Example where the relative ratio of cross-sectional circumference is 0.20] The tensile modulus of the normal part was 65.8 GPa (a rating), the tensile modulus of the irregular part was 60.9 GPa (a rating), the breaking strength of the normal part was 816 MPa (a rating), and the breaking strength of the irregular part was 780 MPa (a rating), and the overall rating was A rank (pass).

[0126] [Example 8: Example where the relative ratio of cross-sectional circumference is 0.00] The tensile modulus of the normal part was 60.9 GPa (a rating), the tensile modulus of the irregular part was 60.9 GPa (a rating), the breaking strength of the normal part was 780 MPa (a rating), and the breaking strength of the irregular part was 780 MPa (a rating), and the overall rating was A rank (pass).

[0127] [Example 9: Example where the relative ratio of cross-sectional perimeter is 0.44] The tensile modulus of the normal part was 60.9 GPa (a rating), the tensile modulus of the irregular part was 49.7 GPa (a rating), the breaking strength of the normal part was 780 MPa (a rating), and the breaking strength of the irregular part was 629 MPa (a rating), and the overall rating was A rank (pass).

[0128] [Example 10: Example where the relative ratio of cross-sectional circumference is 0.64] The tensile modulus of the normal part was 60.9 GPa (rating a), the tensile modulus of the irregular part was 42.3 GPa (rating b), the breaking strength of the normal part was 780 MPa (rating a), and the breaking strength of the irregular part was 565 MPa (rating a), and the overall rating was B rank (pass).

[0129] [Example 11: Example where the relative ratio of cross-sectional circumference is 1.01] The tensile modulus of the normal part was 60.9 GPa (rating a), the tensile modulus of the irregular part was 35.6 GPa (rating b), the breaking strength of the normal part was 780 MPa (rating a), and the breaking strength of the irregular part was 529 MPa (rating a), and the overall rating was B rank (pass).

[0130] [Comparative Example 2: Example where the relative ratio of cross-sectional perimeter is 1.30] 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 D rank (failed).

[0131] (Cover factor evaluation (Table 3)) The cover factors of the normal portion and the irregular portion described in the following examples and comparative examples are the average values ​​of the cover factors of the braided sleeve for the inner layer and the braided sleeve for the outer layer. [Example 12: Example in which the cover factor of the normal part is 90% and the cover factor of the irregular part is 88%] The tensile modulus of the normal part was 56.2 GPa (a rating), the tensile modulus of the irregular part was 44.5 GPa (a rating), the breaking strength of the normal part was 750 MPa (a rating), and the breaking strength of the irregular part was 574 MPa (a rating), and the overall rating was A rank (pass).

[0132] [Example 13: Example in which the cover factor of the normal portion is 60% and the cover factor of the irregular portion is 56%] The tensile modulus of the normal part was 35.4 GPa (rating b), the tensile modulus of the irregular part was 27.6 GPa (rating c), the breaking strength of the normal part was 459 MPa (rating b), and the breaking strength of the irregular part was 363 MPa (rating c), and the overall rating was C rank (pass).

[0133] [Example 14: Example where the cover factor of the normal part is 49% and the cover factor of the irregular part is 50%] The tensile modulus of the normal part was 23.1 GPa (rating C), the tensile modulus of the irregular part was 18.3 GPa (rating C), the breaking strength of the normal part was 366 MPa (rating C), and the breaking strength of the irregular part was 287 MPa (rating C), giving an overall rating of C rank (pass).

[0134] From the above results, it was confirmed that a deformed pipe in which the fiber components are arranged with little fiber bias and at high density throughout the entire longitudinal and circumferential directions of the deformed pipe inside a resin molded body in which at least one of the cross-sectional circumference and cross-sectional shape changes can maintain a high level of axial mechanical properties. Furthermore, as can be seen from the test results of Examples 1 to 4, it was confirmed that the deformed pipes in which a braided sleeve formed of an axial yarn and braiding yarn is arranged (Examples 1, 3, and 4) have higher axial mechanical properties than the deformed pipe in which only a braided sleeve formed of braiding yarn is arranged (Example 2). [Explanation of symbols]

[0135] 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-circular portion connected to the normal portion and having at least one of a cross-sectional perimeter longer than that of the normal portion and a cross-sectional shape different from that of the normal portion; and The irregularly shaped pipe is characterized in that the fiber member has a tubular braided structure and is integrally arranged across the normal portion and the irregularly shaped portion.

2. When there is a difference between the cross-sectional perimeter of the normal portion and the cross-sectional perimeter of the irregularly shaped portion, The irregular pipe according to claim 1, characterized in that a cross-sectional perimeter relative ratio, which is the difference between the cross-sectional perimeter of the normal portion and the cross-sectional perimeter of the irregular portion divided by the cross-sectional perimeter of the normal portion, is 0.63 or less.

3. the fiber member includes a braided sleeve 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, In the braided sleeve, The width of the braid is b ｆ [mm], The number of the braided yarns is n [pieces], The inner diameter of the braided sleeve is D [mm], The orientation angle of the braided yarn with respect to the central axis of the irregular tube is θ [°], A cover factor cf, which indicates the ratio of the braided yarn to the surface area of ​​the braided sleeve in each of the normal portion and the irregular-shaped portion, is calculated by the following (Equation 1) when １ The shaped pipe according to claim 1, characterized in that the values ​​of are all 100% or less and 60% or more. [Equation 1] ...(Formula 1)

4. the fiber component includes a braided sleeve formed by combining an axial yarn oriented in the central axis direction of the irregularly shaped pipe and a braided yarn oriented at an orientation angle in the range of ±5 to 85° with respect to the central axis direction of the irregularly shaped pipe, In the braided sleeve, The width of the braid is b ｆ [mm], The number of the braided yarns is n [pieces], The inner diameter of the braided sleeve is D [mm] The orientation angle of the braided yarn with respect to the central axis of the irregular tube is θ [°], The width of one cell of the braided sleeve is f [mm], The width of the axon is b ｍ [mm], A cover factor cf, which indicates the ratio of the braid yarn and the axial yarn to the surface area of ​​the braided sleeve in each of the normal portion and the irregular portion, is calculated by the following (Equation 2) when ３ The shaped pipe according to claim 1, characterized in that the values ​​of are all 100% or less and 60% or more. [Equation 2] ...(Formula 2)

5. The irregular pipe described in claim 1, characterized in that the fiber member is formed by combining an axial yarn oriented in the central axis direction of the irregular pipe and a braided yarn oriented at an orientation angle relative to the central axis direction of the irregular pipe in the range of ±5 to 85°.

6. A method for manufacturing a deformed pipe made of FRP in which a fiber member is embedded inside a resin molded body, The irregular pipe has a normal portion having a predetermined cross-sectional circumferential length, and an irregular portion connected to the normal portion and 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 fiber member with a sleeve having a cylindrical braided structure, the sleeve being stretchable at least within a range from the minimum cross-sectional circumferential length to the maximum cross-sectional circumferential length of the mandrel and having a constant diameter in the longitudinal direction when not stretched; an impregnation and curing step of impregnating the sleeve with a resin and curing the resin after the covering step; and a removal step of removing the mandrel after the resin has hardened.

7. A method for manufacturing a deformed pipe made of FRP in which a fiber member is embedded inside a resin molded body, The irregular pipe has a normal portion having a predetermined cross-sectional shape, and an irregular portion connected to the normal portion and 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 process in which the fiber member is covered with a sleeve having a tubular braided structure, 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; an impregnation and curing step of impregnating the sleeve with a resin and curing the resin after the covering step; and a removal step of removing the mandrel after the resin has hardened.

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