Curved pipe manufacturing method and curved pipe

Abstract

To provide a method for manufacturing a curved pipe with which it is possible to inexpensively form the curved pipe by a highly versatile die, and the curved pipe.SOLUTION: A method for manufacturing a curved pipe includes: a cutting step of cutting a tubular initial member including at least one inner layer 10 containing fiber-reinforced plastic at a predetermined angle θ with respect to an axis Lo; a joining step of forming a curved part 18 in the initial member by changing directions of cut surfaces 15b and 16b of the initial member in a circumferential direction and by joining them together into a butt state; and an outer layer formation step of forming an outer layer 12 on the initial member having the curved part 18.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a curved pipe and a curved pipe. [Background technology]

[0002] For example, filament winding molding is known as a method for forming a curved pipe containing fiber-reinforced plastic. In filament winding molding, one to several dozen roving strands are aligned and wound around the curved body of a cylindrical mold while impregnating them with resin. After winding the roving, the resin is cured and the mold is removed to form a curved pipe containing fiber-reinforced plastic (see, for example, Patent Document 1).

[0003] Another known method is to use a so-called seesaw mold instead of a cylindrical mold for forming a curved pipe. The seesaw mold has a first mold and a second mold in the curved body portion. The first mold and the second mold are connected so that the bending angle can be adjusted. Therefore, the seesaw mold makes it possible to change the bending angle of the curved pipe. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-52911 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the cylindrical mold used in Patent Document 1 has a fixed curvature, so if the curvature is to be changed, a mold according to the curvature is required, which increases costs. Furthermore, the seesaw mold is costly, especially because the shape of the curved body is complex. Furthermore, the seesaw mold does not allow for adjustment of the length of the curved pipe, and it is difficult to remove the curved pipe after forming. Therefore, when forming multiple layers of curved pipe, it is necessary to form the multiple layers while the seesaw mold is attached. In addition, seesaw molds are generally made of metal, which makes them heavy. Therefore, the ancillary equipment required for filament winding molding, such as cranes and molding machines, must be large.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a method for manufacturing a curved pipe that can form a curved pipe using a mold that is low cost and highly versatile, and the curved pipe. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention proposes the following means. A method for manufacturing a curved pipe according to one embodiment of the present invention includes a cutting process for cutting a cylindrical initial member including at least one inner layer containing fiber-reinforced plastic at a predetermined angle relative to an axis, a joining process for forming a bent portion in the initial member by joining the cut surfaces of the initial member in a butted state while changing their orientation circumferentially, and an outer layer forming process for forming an outer layer on the initial member having the bent portion. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a method for manufacturing a curved pipe that can form a curved pipe using a mold that is highly versatile and low cost, and the curved pipe. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a plan view showing a curved pipe according to an embodiment of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the curved pipe of FIG. 1, with the outer layer cut away. [Figure 3] 3 is a cross-sectional view of the curved pipe of FIG. 2 taken along line AA. [Figure 4] FIG. 2 is a side view showing a mold pipe member according to the embodiment. [Figure 5] 5 is a cross-sectional view of the mold pipe member of FIG. 4 taken along line BB. [Figure 6] FIG. 10 is a side view showing an example of forming an inner layer around the mold pipe member according to the embodiment. [Figure 7] 7 is a cross-sectional view of the mold tube member and the inner layer of FIG. 6 taken along line CC. [Figure 8] FIG. 10 is a cross-sectional view illustrating an example in which the second mold member is moved to remove the initial member from the mold pipe member according to the embodiment. [Figure 9] FIG. 10 is a cross-sectional view illustrating an example in which the first mold member is moved to remove the initial member from the mold pipe member according to the embodiment. [Figure 10] 10A and 10B are side views illustrating an example of cutting the initial member according to the embodiment. [Figure 11] 10A and 10B are side views illustrating an example of joining initial members according to an embodiment. [Figure 12] 10 is a side view illustrating an example of attaching a socket die to a first member according to an embodiment. FIG. [Figure 13] 10 is a side view illustrating the state in which a support member is attached to the socket die according to the embodiment. FIG. [Figure 14] 10 is a side view illustrating an example of forming a first outer layer around the socket die and the first member according to the embodiment. FIG. [Figure 15] 10 is a side view illustrating the state in which an outer layer is formed around the socket die and the first member according to the embodiment. FIG. [Figure 16] 10 is a side view illustrating an example of attaching a socket die to a second member according to an embodiment. FIG. [Figure 17] 10 is a side view illustrating an example of forming a second outer layer around the socket die and the second member according to the embodiment. FIG. [Figure 18] FIG. 10 is a plan view showing an initial member of a modified example according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a method for manufacturing a curved pipe and a curved pipe according to one embodiment of the present invention will be described with reference to the drawings.

[0011] 1 and 2, the curved pipe 1 is formed by forming a cylindrical initial member (inner layer) containing fiber-reinforced plastic, and then forming an outer layer containing fiber-reinforced plastic around the initial member. A method for manufacturing the curved pipe will be described in detail later. The curved pipe 1 includes, for example, a curved pipe main body 2, a first socket 3, and a second socket 4. In the embodiment, an example is described in which the curved pipe 1 includes the first socket 3 and the second socket 4, but the curved pipe 1 may also be formed only by the curved pipe main body 2. Alternatively, the curved pipe 1 may include an insertion port instead of at least one of the first socket 3 and the second socket 4.

[0012] The curved pipe body 2 is formed into a cylindrical shape around the axis Lo. The curved pipe body 2 has a curved pipe bend portion 2a, and is formed by bending at a predetermined bending angle. The curved pipe body 2 includes, for example, an inner layer 10, a bonding material 11, and an outer layer 12. The inner layer 10 includes a first member 15 and a second member 16. The first member 15 and the second member 16 are formed by cutting an initial member, which will be described later.

[0013] The first member 15 is formed in a cylindrical shape and extends linearly along the axis Lo. The first member 15 is formed so that an end surface 15a is perpendicular to the axis Lo. The first member 15 has a cut surface 15b formed by cutting an initial member, which will be described later. The cut surface 15b of the first member 15 is formed so as to be inclined at a predetermined angle θ with respect to the axis Lo. The cut surface 15b has a first surface 15c and a second surface 15d. The first surface 15c is the portion that protrudes most along the axis Lo. The second surface 15d is the portion closest to the end surface 15a along the axis Lo.

[0014] The second member 16 is formed in a cylindrical shape with the same diameter as the first member 15 and extends linearly along the axis Lo. The second member 16 is formed so that an end face 16a is perpendicular to the axis Lo. The second member 16 has a cut surface 16b formed by cutting an initial member, which will be described later. The cut surface 16b of the second member 16 is formed so as to be inclined at a predetermined angle θ with respect to the axis Lo. The cut surface 16b has a first surface 16c and a second surface 16d. The first surface 16c is the portion that protrudes most along the axis Lo. The second surface 16d is the portion closest to the end surface 16a along the axis Lo.

[0015] The first member 15 and the second member 16 (i.e., the inner layer 10) are formed of at least one layer containing, for example, fiber-reinforced plastic. In the embodiment, an example in which the inner layer 10 is formed of one layer containing fiber-reinforced plastic will be described, but the inner layer 10 may be formed of multiple layers containing fiber-reinforced plastic. Fiber reinforced plastics are formed, for example, by laminating glass mat, glass cloth, and glass mat in this order as resin reinforcing fibers, impregnating the laminate with a matrix resin, and then curing the impregnated matrix resin. Hereinafter, fiber reinforced plastics will sometimes be referred to as "FRP (Fiber Reinforced Plastics)."

[0016] Examples of resin-reinforcing fibers used in the FRP of the first member 15 and the second member 16 include inorganic fibers such as glass fiber, ceramic fiber, and boron fiber; carbon fibers such as PAN (polyacrylonitrile)-based carbon fiber and pitch-based carbon fiber; organic fibers such as aramid, polyester, polyethylene, nylon, vinylon, polyacetal, polyparaphenylene benzoxazole, and high-strength polypropylene; and natural fibers such as kenaf and hemp. These fibers can be used alone or in combination. Examples of the form of the resin-reinforcing fibers include filaments, strands, rovings, bulky rovings, roving cloths, chopped strand mats, and cloths.

[0017] Thermosetting resins are generally preferred as matrix resins for FRP, but thermoplastic resins are not excluded. Examples include urethane, vinyl ester, unsaturated polyester, polyamide, epoxy resin, polycarbonate, nylon, polyethylene, polyethylene terephthalate, polyphenylene sulfide, and poly(meth)acrylic ester. These resins can be used alone or in combination.

[0018] The cut surfaces 15b, 16b of the first member 15 and the second member 16 are abutted against each other. In this state, the first surface 15c of the first member 15 is abutted against the first surface 16c of the second member 16. The second surface 15d of the first member 15 is abutted against the second surface 16d of the second member 16. Therefore, the first member 15 and the second member 16 are arranged in a bent state at the region 18 where the cut surfaces 15b, 16b are abutted against each other. Hereinafter, the region 18 where the cut surface 15b of the first member 15 and the cut surface 16b of the second member 16 are butted together may be referred to as the "bent portion 18." That is, the inner layer 10 has the bent portion 18. The inner layer 10 is divided around the entire circumference at the bent portion 18. The bent portion 18 is joined by a joining material 11.

[0019] As shown in FIGS. 2 and 3 , the bonding material 11 bonds the bent portion 18. Specifically, the bonding material 11 includes a first bonding material 21 and a second bonding material 22. The first bonding material 21 is, for example, an FRP formed by hand layup on the outer periphery of the bent portion 18. The second bonding material 22 is, for example, an FRP formed by hand layup on the inner periphery of the bent portion 18. That is, the first member 15 and the second member 16 are bonded by the bonding material 11 in a state in which the bent portion 18 is separated over the entire periphery. The bonding material 11 may be formed by, for example, forming FRP on either the outer periphery or the inner periphery of the bent portion 18 by hand lay-up.

[0020] As shown in Figures 1 to 3, the outer layer 12 is, for example, at least one layer laminated on the outer periphery of the inner layer 10 and the outer periphery of the connecting material. In the embodiment, an example in which the outer layer 12 is formed of one layer will be described, but the outer layer 12 may be formed of multiple layers. The outer layer 12 is provided continuously in the direction of the axis Lo at the bent portion 18 of the inner layer 10. The outer layer 12 is continuous without interruption at the bent pipe portion 2a of the curved pipe 1 (specifically, the curved pipe main body 2). The outer layer 12 includes, for example, at least one layer of FRP. The FRP of the outer layer 12 is formed by a filament winding method or a hand layup method. The resin reinforcing fibers and matrix resin used in the FRP of the outer layer 12 are, for example, the same as those used in the FRP of the inner layer 10.

[0021] The portion of the outer layer 12 corresponding to the bent portion 18, together with the bent portion 18 and the bonding material 11, forms the bent portion 2a of the curved pipe 1. The thickness T1 of the outer layer 12 is 3 to 50 times the thickness T2 of the inner layer 10. Preferably, the thickness T1 of the outer layer 12 is 4 to 20 times the thickness T2 of the inner layer 10. Furthermore, the thickness T2 of the inner layer 10 is 1% or less, and preferably 0.5% or less, of the nominal diameter of the curved pipe.

[0022] The first socket 3 is provided integrally with the outer layer 12 at one end 2b of the curved pipe body 2. The inner diameter of the first socket 3 is larger than the inner diameter of the curved pipe body 2. The outer diameter of the first socket 3 is larger than the outer diameter of the curved pipe body 2. A straight pipe (not shown), for example, is connected to the first socket 3. The second socket 4 is integrally formed on the outer layer 12 at the other end 2c of the curved pipe body 2. The inner diameter of the second socket 4 is larger than the inner diameter of the curved pipe body 2. The outer diameter of the second socket 4 is larger than the outer diameter of the curved pipe body 2. A straight pipe (not shown), for example, is connected to the second socket 4.

[0023] Next, a method for manufacturing the curved pipe 1 will be described with reference to FIGS. First, a mold pipe member used in the manufacturing method of the curved pipe 1 will be described with reference to FIGS. <Mold tubing> As shown in Figures 4 and 5, the mold pipe member 100 is a cylindrical mold such as a wooden mold, FRP mold, or metal mold. The mold pipe member 100 is formed, for example, in a cylindrical shape along a linearly extending axis Lo. The mold pipe member 100 is configured as a straight pipe by being divided into four parts (segments) in the circumferential direction. Specifically, the mold pipe member 100 has a pair of first mold members 101 arranged opposite to each other and a pair of second mold members 102 arranged opposite to each other. The mold pipe member 100 is configured by combining a pair of first mold members 101 and a pair of second mold members 102 so that they are arranged alternately in the circumferential direction.

[0024] The first mold member 101 has, for example, an outer peripheral surface 105, an inner peripheral surface 106, and a pair of end surfaces 107. The outer peripheral surface 105 of the first mold member 101 is formed in an arc shape with a central angle of approximately 150 degrees when viewed from the direction of the axis Lo. The inner peripheral surface 106 of the first mold member 101 is formed in an arc shape with a central angle of approximately 90 degrees when viewed from the direction of the axis Lo. The end surfaces 107 of the first mold member 101 are connected to the ends of the outer peripheral surface 105 and the inner peripheral surface 106. The pair of opposing end surfaces 107 are inclined such that the distance between them gradually decreases from the inner peripheral surface 106 to the outer peripheral surface 105. The second mold member 102 is fitted between the pair of opposing end surfaces 107 from the radially inward direction.

[0025] The second mold member 102 has, for example, an outer peripheral surface 115, an inner peripheral surface 116, and a pair of end faces 117. The outer peripheral surface 115 of the second mold member 102 is formed, for example, in an arc shape with a central angle of approximately 30 degrees when viewed from the direction of the axis Lo. The inner peripheral surface 116 of the second mold member 102 is formed in an arc shape with a central angle of approximately 90 degrees when viewed from the direction of the axis Lo. The end faces 117 are connected to an end of the outer peripheral surface 115 and an end of the inner peripheral surface 116. The pair of oppositely disposed end faces 117 are fitted like wedges between the pair of end faces 107 of the first mold member 101 from the radially inner side.

[0026] An end face 107 of the first mold member 101 and an end face 117 of the second mold member 102 that contacts the end face 107 are fixed together by bolts 119. As a result, the mold pipe member 100 forms a cylindrical straight pipe with the outer circumferential surfaces 105 of the pair of first mold members 101 and the outer circumferential surfaces 115 of the pair of second mold members 102. The mold pipe member 100 is configured so that the pair of first mold members 101 and the pair of second mold members 102 can be separated by removing the bolts 119 from the end faces 107 of the first mold member 101 and the end faces 117 of the second mold member 102.

[0027] Next, a method for manufacturing a curved pipe 1 using a mold pipe member will be described with reference to FIGS. <Initial component formation process> 6 and 7, in the initial member forming step, an inner layer 10 is formed around a mold pipe member 100. The inner layer 10 includes at least one layer of FRP formed by various methods such as a hand lay-up method. Specifically, the FRP of the inner layer 10 is formed by winding resin reinforcing fibers around the mold pipe member 100 by a hand lay-up method, for example, and then impregnating the resin with a matrix resin and curing the impregnated matrix resin.

[0028] A cylindrical initial member is formed by forming an inner layer 10 around the mold pipe member 100. The cylindrical initial member includes the inner layer 10. In the embodiment, the inner layer 10 will be described as the "initial member 10." The initial member 10 is formed so as to extend linearly along the axis Lo by forming the inner layer 10 around the mold pipe member 100. The initial member 10 can be formed over a predetermined length in the direction of the axis Lo of the mold pipe member 100.

[0029] <Demolding process> 7, in the demolding step, the initial member 10 is removed from the mold pipe member 100 and demolded. Specifically, first, the bolts 119 are removed from the end face 107 of the first mold member 101 and the end face 117 of the second mold member 102. This allows the pair of first mold members 101 and the pair of second mold members 102 to be separated.

[0030] As shown in FIG. 8, the pair of second mold members 102 are moved radially inward (diameter reduced) of the mold pipe member 100. That is, the pair of second mold members 102 are moved so as to approach each other in the radial direction. At this time, for example, the inner circumferential surfaces 116 of the pair of second mold members 102 can be connected to each other with turnbuckles (not shown), and then the pair of second mold members 102 can be moved closer to each other with the turnbuckles. This releases the contact state between the first mold member 101 and the second mold member 102. After the contact state between the first mold member 101 and the second mold member 102 is released, the pair of second mold members 102 are moved in the direction of the axis Lo and removed from the pair of first mold members 101.

[0031] 8 and 9, the pair of second mold members 102 is removed from the pair of first mold members 101, thereby releasing the contact state between the pair of second mold members 102 and the pair of first mold members 101. After releasing the contact state between the pair of second mold members 102 and the pair of first mold members 101, the pair of first mold members 101 is moved (reduced in diameter) in the direction of the axis Lo and removed from the initial member 10. This allows the initial member 10 to be easily removed from the mold tube member 100.

[0032] <Cutting process> As shown in Figure 10, in the cutting process, the cylindrical initial member 10 is cut at a predetermined angle θ with respect to the axis Lo. Thus, the initial member 10 is cut into a first member 15 and a second member 16. The cut surface 15b of the first member 15 is formed so as to be inclined at the predetermined angle θ with respect to the axis Lo. The cut surface 15b has a first surface 15c that protrudes most along the axis Lo and a second surface 15d that is closest to the end surface 15a along the axis Lo. The end surface 15a of the first member 15 is formed so as to be perpendicular to the axis Lo.

[0033] The cut surface 16b of the second member 16 is formed so as to be inclined at a predetermined angle θ with respect to the axis Lo. The cut surface 16b has a first surface 16c that protrudes most along the axis Lo and a second surface 16d that is closest to the end surface 16a along the axis Lo. The end surface 16a of the second member 16 is formed so as to be perpendicular to the axis Lo.

[0034] <Joining process> As shown in FIG. 11 , in the joining process, the cut surface 15b of the first member 15 and the cut surface 16b of the second member 16 are butted against each other. Specifically, the cut surfaces 15b, 16b of the first member 15 and the second member 16 are joined in a state where they are butted against each other with their orientations changed in the circumferential direction. In this state, the first surface 15c of the first member 15 and the first surface 16c of the second member 16 are butted against each other. The second surface 15d of the first member 15 and the second surface 16d of the second member 16 are butted against each other. Therefore, the first member 15 and the second member 16 can be arranged in a bent state at the bent portion 18 where the cut surface 15b of the first member 15 and the cut surface 16b of the second member 16 are butted against each other. As a result, the initial member 10 has the bent portion 18 and is formed in a bent state at the bent portion 18.

[0035] As shown in FIGS. 3 and 11 , the bent portion 18 is joined with the joining material 11. Specifically, for example, a first joining material 21 of the joining material 11 is formed of FRP on the outer periphery of the bent portion 18 by hand layup. Also, a second joining material 22 of the joining material 11 is formed of FRP on the inner periphery of the bent portion 18 by hand layup. Thus, the cut surface 15b of the first member 15 and the cut surface 16b of the second member 16 can be joined together by the joining material 11. As a result, the bent portion 18 can be joined with the joining material 11 in a state where it is divided over the entire periphery. The bonding material 11 may be formed by, for example, forming FRP on either the outer periphery or the inner periphery of the bent portion 18 by hand lay-up.

[0036] <First socket type installation process> As shown in FIG. 12, in the first socket die attachment step, a socket die 150 is attached to an opening 15f of an end portion 15e of the first member 15. The end portion 15e of the first member 15 corresponds to 10a of the initial member 10. The socket die 150 is a die that forms, for example, a socket 3 (see FIG. 2) that connects a straight pipe to the end portion of a curved pipe 1. Specifically, the socket die 150 has a large diameter portion 151 and a small diameter portion 152. The large diameter portion 151 is formed with an outer diameter larger than that of the first member 15. The small diameter portion 152 is formed with an outer diameter that allows it to be inserted into the opening 15f of the first member 15.

[0037] 13, the small diameter portion 152 of the socket die 150 is inserted into the opening 15f of the end portion 15e of the first member 15 in the direction of the axis Lo. With the small diameter portion 152 inserted into the opening 15f, FRP (not shown) is layered on the end portion 15e of the first member 15 and the socket die 150 by, for example, a hand layup method, and then hardened. This temporarily fixes the end portion 15e of the first member 15 and the socket die 150 with the FRP. The socket die 150 is formed from, for example, a metal such as stainless steel having a hard plating layer on the surface, FRP, or the like.

[0038] <First support member mounting process> As shown in Figure 13, in the first support member attachment step, the socket die 150 temporarily fixed to the end 15e of the first member 15 is fixed to the support member 160. Thus, the end 15e of the first member 15 is fixed to the support member 160 via the socket die 150. The support member 160 is rotatable around the horizontal axis X. The horizontal axis X is arranged coaxially with the axis Lo of the first member 15. Thus, the first member 15 fixed to the support member 160 can be rotated around the horizontal axis X.

[0039] <First outer layer formation process (outer layer formation process)> As shown in FIG. 14, in the first outer layer forming step, a first outer layer (outer layer) 24 (see FIG. 15) is formed around the large diameter portion 151 of the receiving die 150 and around the first member 15 by, for example, a filament winding method. Specifically, the receiving die 150 and the first member 15 are rotated around the horizontal axis X. In this state, resin reinforcing fibers 27 impregnated with a matrix resin are wound around the large diameter portion 151 and around the first member 15. As a result, the first outer layer 24 is laminated around the large diameter portion 151. Furthermore, the first outer layer 24 is laminated from one end 10a of the initial member 10 (i.e., the end 15e of the first member 15), across the bent portion 18, and up to the other end 10b of the initial member 10 (i.e., the end 16e of the second member 16). Here, the portion of the first outer layer 24 closer to the other end 10b than the bent portion 18 (the portion on the second member 16) is referred to as the tip portion 24a of the first outer layer 24. The tip portion 24a extends from the bent portion 18 toward the second member 16. The thickness of the tip portion 24a decreases from the bent portion 18 toward the other end 10b. The length of the tip portion 24a in the direction of the axis Lo is, for example, one-third of the length of the second member 16 in the direction of the axis Lo. In this way, since the first outer layer 24 has the tip portion 24a and extends toward the other end 10b than the bent portion 18, the outer layer 12 can more easily bear the load, for example, when the curved pipe 1 is bent by a load from above during installation. However, the tip portion 24a is not necessary.

[0040] 15 , the periphery of the large diameter portion 151, the periphery of the first member 15, and the periphery of a portion of the second member 16 are covered with a first outer layer 24 (i.e., resin reinforcing fiber 27). After the periphery of the large diameter portion 151 and the periphery of the first member 15 and the second member 16 have been covered with the resin reinforcing fiber 27, the receiving die 150 and the initial member 10 are removed from the supporting member 160. After the receiving die 150 and the initial member 10 are removed from the supporting member 160, the receiving die 150 is removed from the first member 15 of the initial member 10.

[0041] <Second socket mold mounting step, second support member mounting step> 16 and 17, in the second socket mold attaching step, similar to the first socket mold attaching step, a socket mold 150 is attached and temporarily fixed to the opening 16f of the end portion 16e of the second member 16. The end portion 16e of the second member 16 corresponds to 10b of the initial member 10. Furthermore, similarly to the first support member attachment step, the socket die 150 temporarily fixed to the end portion 16e of the second member 16 is fixed to the support member 160. Therefore, the second member 16 fixed to the support member 160 can be rotated around the horizontal axis X.

[0042] <Second outer layer formation process> As shown in FIGS. 1, 2, and 17, in the second outer layer forming step, similar to the first outer layer forming step, a second outer layer (outer layer) 25 is formed around the large diameter portion 151 of the receiving die 150, around the second member 16, and around the tip end 24a of the first outer layer 24 by, for example, a filament winding method. Specifically, the receiving die 150 and the second member 16 are rotated around the horizontal axis X. In this state, resin reinforcing fibers 27 impregnated with a matrix resin are wound around the large diameter portion 151, around the second member 16, and around the tip end 24a of the first outer layer 24. As a result, the second outer layer 25 is laminated around the large diameter portion 151. Furthermore, the second outer layer 25 is laminated from the other end 10b of the initial member 10 (i.e., the end 16e of the second member 16) to the bent portion 18.

[0043] This allows the first outer layer 24 and the second outer layer 25 to be laminated in a continuous state from one end 10a to the other end 10b of the initial member 10 via the bent portion 18. Hereinafter, the first outer layer 24 and the second outer layer 25 may be collectively referred to as the "outer layer 12." That is, in the first outer layer forming step and the second outer layer forming step, the outer layer 12 can be formed over the entire initial member 10 having the bent portion 18 in the direction of the axis Lo. Therefore, the outer layer 12 can be made continuous without any breaks at the bent portion 2a of the curved pipe 1 (specifically, the curved pipe main body 2).

[0044] The entire initial member 10 is covered with the outer layer 12 (i.e., the resin reinforcing fibers 27) over the entire direction of the axis Lo. After the entire initial member 10 is covered with the outer layer 12 (i.e., the resin reinforcing fibers 27), the receiving die 150 and the initial member 10 are removed from the support member 160. After the receiving die 150 and the initial member 10 are removed from the support member 160, the receiving die 150 is removed from the second member 16 of the initial member 10.

[0045] After the receiving die 150 is removed from the second member 16, the initial member 10 covered with the outer layer 12 (resin reinforcing fibers 27) is placed in a curing oven (not shown). In the curing oven, the initial member 10, the joints, and the matrix resin impregnated in the resin reinforcing fibers 27 are cured. The initial member 10, bonding material, and matrix resin are hardened to form the curved pipe 1. The curved pipe 1 is formed into a V-shape by the curved pipe body 2, the first socket 3, and the second socket 4. This completes the manufacturing method for the curved pipe 1.

[0046] In the embodiment, an example in which the same socket die 150 is attached to the end 15e of the first member 15 and the end 16e of the second member 16 will be described, but this is not limiting. As another example, different socket dies may be attached to the end 15e of the first member 15 and the end 16e of the second member 16. In the embodiment, an example in which the initial member 10 is formed in a linear shape will be described, but this is not limiting. As another example, the initial member 10 may be formed in a curved shape. This makes it possible to form the initial member 10 in other shapes, such as an S-shape.

[0047] According to the method for manufacturing a curved pipe according to the embodiment described above, as shown in FIGS. 6, 10, and 11, the initial member 10 is cut at a predetermined angle θ with respect to the axis Lo, and the cut surfaces 15b, 16b are butted together and joined to form a bent portion 18 in the initial member 10. This makes it possible to form curved pipes 1 (see FIG. 1) with a variety of curvatures without being largely dependent on the shape of the initial member 10. This, for example, increases the versatility of the mold pipe member 100 used to manufacture the initial member 10, allowing curved pipes 1 with various bending angles to be formed using a single mold pipe member 100. This eliminates the need to prepare multiple molds for each bending angle of the curved pipe 1. This allows, for example, to form a curved pipe 1 using a low-cost, highly versatile mold (i.e., mold pipe member 100).

[0048] Furthermore, a mold pipe member 100 extending linearly is used to form the initial member 10. This simplifies the mold pipe member 100. Furthermore, when forming the initial member 10 with the mold pipe member 100, the length of the initial member 10 can be adjusted. This allows the length of the initial member 10 to be adjusted with one mold pipe member 100. In addition, the mold pipe member 100 is extended linearly. This allows the formed initial member 10 to be easily removed from the mold pipe member 100 and demolded. Furthermore, the outer layer 12 can be formed on the initial member 10 that has been demolded from the mold pipe member 100. Therefore, for example, compared to when the outer layer 12 is formed on the initial member 10 with the mold pipe member 100 still attached, incidental equipment (not shown), such as a crane or molding machine, that is required when forming the outer layer 12 on the initial member 10 can be made smaller.

[0049] Here, the cut surfaces 15b and 16b of the initial member 10 (i.e., the first member 15 and the second member 16) are joined together in a state where they are turned circumferentially and butted against each other. Therefore, the area where the cut surfaces 15b and 16b butt against each other is formed as a bent portion 18. Therefore, the bent portion 18 where the cut surfaces 15b and 16b butt against each other is joined with the joining material 11 by a hand layup method. Therefore, the joining material 11 can be suitably formed in the bent portion 18 to match the shape of the bent portion 18. As a result, the bent portion 18 where the cut surfaces 15b and 16b butt against each other can be appropriately joined with the joining material 11.

[0050] 2 and 10, according to the curved pipe 1 of the embodiment, the inner layer 10 is divided around the entire circumference at the bent portion 18. Therefore, for example, the curved pipe 1 can be manufactured by a manufacturing method using the initial member 10. However, if a pipe material with an inner layer 10 and an outer layer 12 laminated from the beginning is used without using the initial member 10, and this pipe material is cut and the cut pieces are joined together in different directions to manufacture a curved pipe, both the inner layer and the outer layer will be separated along the entire circumference at the bend. In such a divided bend, for example, when an external force is applied to the bent pipe in an out-of-plane direction, large compressive stresses are likely to occur inside the bent pipe and large tensile stresses are likely to occur outside the bent pipe.

[0051] On the other hand, as described above, the outer layer 12 can be made continuous without any breaks at the curved pipe bend 2a of the curved pipe 1 (specifically, the curved pipe main body 2). Therefore, at the curved pipe bend 2a where the outer layer 12 is not broken, stress is unlikely to occur even when an external force is applied to the curved pipe 1.

[0052] In this curved pipe 1, the inner layer 10 is divided around the entire circumference at the bent portion 18, while the outer layer 12 is continuous in the direction of the axis Lo at the bent portion 18. Furthermore, the thickness T1 of the outer layer 12 is 3 to 50 times the thickness T2 of the inner layer 10. Therefore, the thickness T1 of the outer layer 12 is greater than the thickness T2 of the inner layer 10, and the occurrence of the aforementioned stress can be suppressed.

[0053] Furthermore, by making the thickness T1 of the outer layer 12 3 to 50 times the thickness T2 of the inner layer 10, the thickness T2 of the inner layer 10 can be made thinner. This makes it possible to easily cut the inner layer 10 (i.e., the initial component 10) at a predetermined angle relative to the axis Lo. Note that the thickness T1 of the outer layer 12 is preferably 4 to 20 times the thickness T2 of the inner layer 10. Furthermore, the thickness T2 of the inner layer 10 is preferably 1% or less, and more preferably 0.5% or less, of the nominal diameter of the curved pipe.

[0054] Next, a modified example of the curved pipe 1 in the embodiment will be described with reference to Fig. 18. In the modified example, the same or similar members as those in the curved pipe 1 in the embodiment will be assigned the same reference numerals and detailed description thereof will be omitted. (Variation) 18, in the curved pipe 50 of the modified example, at least one layer of the inner layer 51 is divided at multiple locations in the direction of the axis Lo. In the modified example, two locations are described as the multiple divided locations, but the number of divided locations is not limited to two. Also, in the modified example, as in the embodiment, an example in which the inner layer 51 is formed of a single layer containing fiber-reinforced plastic is described, but the inner layer 51 may be formed of multiple layers.

[0055] The inner layer 51 includes a first member 55, a second member 56, and a third member 57. The first member 55, the second member 56, and the third member 57 are formed, for example, by cutting a linearly extending cylindrical initial member (not shown) at a predetermined angle θ with respect to the axis Lo. The cylindrical initial member includes the inner layer 51. Cut surfaces 56a, 56b at both ends of the second member 56 are inclined in a V-shape. A bent portion 61 where a cut surface 55a of the first member 55 and a cut surface 56a of the second member 56 are butted together is joined by a bonding material 11. A bent portion 62 where a cut surface 56b of the second member 56 and a cut surface 57a of the third member 57 are butted together is joined by a bonding material 11.

[0056] According to the modified curved pipe manufacturing method and curved pipe 50, the curved pipe 50 can be easily formed into any angle, length, or shape by dividing the inner layer 51 at multiple locations. This allows for a wider range of uses for the curved pipe 50. Furthermore, according to the modified example, it is possible to obtain the same functions and effects as the curved pipe manufacturing method and curved pipe 1 according to the embodiment.

[0057] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0058] In addition, the components in this embodiment can be replaced with well-known components as appropriate, without departing from the spirit of the present invention.

[0059] (Addendum) The embodiment can be understood, for example, as follows.

[0060] <1> A method for manufacturing a curved pipe according to one embodiment of the present invention includes a cutting process for cutting a cylindrical initial member including at least one inner layer containing fiber-reinforced plastic at a predetermined angle relative to an axis, a joining process for forming a bent portion in the initial member by joining the cut surfaces of the initial member in a butted state while changing their orientation circumferentially, and an outer layer forming process for forming an outer layer on the initial member having the bent portion.

[0061] According to the method for manufacturing a curved pipe, an initial member is cut at a predetermined angle relative to the axis, and the cut surfaces are butted together to form a bent portion in the initial member. This makes it possible to form curved pipes with a variety of curvatures without being heavily dependent on the shape of the initial member. This, for example, increases the versatility of the mold pipe member used to manufacture the initial member, allowing curved pipes with various bending angles to be formed using a single mold pipe member. This eliminates the need to prepare multiple molds for each bending angle of the curved pipe. This makes it possible to form curved pipes using a low-cost, highly versatile mold, for example.

[0062] <2> the above <1> The method for manufacturing a curved pipe according to the present invention may include, before the cutting step, an initial member forming step of forming the initial member by forming an inner layer around the mold pipe member, and a demolding step of removing the initial member from the mold pipe member.

[0063] According to the method for manufacturing a curved pipe, when forming an initial part using a mold pipe member, the length of the initial part can be adjusted by adjusting the length of the initial part using a single mold pipe member. In addition, an outer layer can be formed on the initial part after it has been removed from the mold pipe member. Therefore, for example, compared to when an outer layer is formed on the initial part while the mold pipe member is still attached, the ancillary equipment, such as a crane or molding machine, required to form the outer layer on the initial part can be made smaller.

[0064] <3> the above <1> or <2> In the method for manufacturing a curved pipe according to the above aspect, in the joining step, the cut surfaces of the initial members may be butted together with their circumferential orientations changed, and joined by a hand layup method.

[0065] Here, by joining the cut surfaces of the initial members in a state where they are turned circumferentially and butted together, the area where the cut surfaces butt together is formed into a bent portion. Therefore, we decided to join the bent portion where the cut surfaces butt together using the hand layup method. This allows the resin to be well formed in the bent portion according to the shape of the bent portion. This allows the bent portion where the cut surfaces butt together to be properly joined.

[0066] <4> A curved pipe according to one embodiment of the present invention is a curved pipe having a bent portion, and is provided with at least one inner layer containing fiber-reinforced plastic and at least one outer layer laminated on the inner layer, wherein at least one of the inner layers is divided around the entire circumference at the bent portion, the outer layer is continuous in the axial direction at the bent portion, and the thickness of the outer layer is at least 3 times and at most 50 times the thickness of the inner layer.

[0067] At least one of the inner layers is divided around the entire circumference at the bent portion. Therefore, for example, the bent pipe can be manufactured by the manufacturing method using the initial member described above. However, if a pipe material with an inner and outer layer laminated from the beginning is used without using initial components, and this pipe material is cut and the cut components are joined together in different orientations to produce a curved pipe, both the inner and outer layers will be separated along the entire circumference at the bend. In a curved pipe that is separated in this way, for example, when an external force is applied to the bent pipe in an out-of-plane direction, large compressive stresses are likely to occur inside the bend and large tensile stresses are likely to occur outside the bend. In contrast, a curved pipe without the aforementioned separation is less likely to generate stress even when the external force is applied.

[0068] In this bent pipe, at least one inner layer is divided around the entire circumference at the bend, while the outer layer is continuous in the axial direction at the bend. Moreover, the thickness of this outer layer is 3 to 50 times the thickness of the inner layer. Therefore, the thickness of the outer layer is greater than the thickness of the inner layer, and the generation of the aforementioned stress can be suppressed. Furthermore, by making the thickness of the outer layer 3 to 50 times the thickness of the inner layer, the thickness of the inner layer can be made thin, which makes it easy to cut the inner layer (i.e., the initial member) at a predetermined angle relative to the axis.

[0069] <5> the above <4> In the curved pipe according to the above aspect, at least one of the inner layers may be divided at a plurality of locations in the axial direction.

[0070] According to the curved pipe, by dividing at least one of the inner layers at multiple locations, the curved pipe can be easily formed into any angle, length, or shape, thereby expanding the uses of the curved pipe. [Explanation of symbols]

[0071] 1,50…bent pipe 10,51...inner layer 10...Initial parts 11...Joining material 12…outer layer 15b,16b,55a,56a,56b,57a...cut surface 18, 61, 62...Bent section 100...Mold tube member Lo…Axis line θ: specified angle

Claims

1. a cutting step of cutting a cylindrical initial member including at least one inner layer containing a fiber-reinforced plastic at a predetermined angle relative to an axis; a joining step of joining the cut surfaces of the initial members together in a state where the cut surfaces are butted against each other while changing the orientation in the circumferential direction, thereby forming a bent portion in the initial member; and forming an outer layer on the initial member having the bent portion.

2. Before the cutting step, an initial member forming step of forming an inner layer around a mold tube member to form the initial member; The method for manufacturing a curved pipe according to claim 1, further comprising a demolding step of removing the initial member from the mold pipe member.

3. 3. The method for manufacturing a curved pipe according to claim 1, wherein in the joining step, the cut surfaces of the initial members are butted together with their circumferential orientations changed, and then joined by a hand layup method.

4. A curved pipe having a bent portion, at least one inner layer including a fiber-reinforced plastic; At least one outer layer laminated on the inner layer, At least one of the inner layers is divided around the entire periphery at the bent portion, the outer layer is continuous in the axial direction at the bent portion, The thickness of the outer layer is 3 times or more and 50 times or less than the thickness of the inner layer.

5. 5. The curved pipe according to claim 4, wherein at least one of the inner layers is divided at a plurality of locations in the axial direction.

Images