Method for manufacturing structure and structure

Abstract

Provided are a method for manufacturing an FRP structure having a high degree of freedom in cross-sectional shape despite low cost and a structure. The method for manufacturing the structure comprises the following steps: a winding step, in which a plurality of composite raw materials including reinforcing fibers and uncured thermosetting resin are wound around a hollow cylindrical core material CY to form a cylindrical laminate LM; a pressing step, in which a strip TP or a film is wound around the outer periphery of the laminate LM and pressurized; a preheating step, in which the laminate LM is heated to a state before the thermosetting resin is completely cured; and a main heating step, in which the laminate LM wound with the strip TP or the film and the cylindrical core material CY are arranged in a forming mold and pressurized, thereby deforming the cylindrical core material CY into a non-circular cross-sectional shape and heating the laminate LM until the thermosetting resin is completely cured. Thus, a structure in which the cylindrical core material CY and the laminate LM are integrated can be formed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a structure and the structure. Background Art

[0002] For example, metal structures have been commonly used in motorcycles, automobiles, etc., but in recent years, new structures with both high strength and light weight are expected to replace the heavier metal structures. FRP (Fiber Reinforced Plastics) is known as a raw material that has high strength despite its light weight. For example, hollow cylindrical members made of FRP are used in bicycle frames, etc.

[0003] However, depending on the structure, for example, in order to avoid interference with surrounding components, it is sometimes desirable to partially change the cross-sectional shape orthogonal to the length direction in the length direction. Such a structure is referred to as an irregular cross-sectional structure. In addition, when a plurality of structures are gathered together for the purpose of ensuring strength, in order to avoid gaps between adjacent structures as much as possible, it is sometimes desirable to make a polygonal cross section. Such a structure is referred to as a polygonal cross-sectional structure. If FRP can be used to form an irregular cross-sectional structure or a polygonal cross-sectional structure, its use is expanded, so it is preferred.

[0004] In the prior art, an irregular cross-section structure or a polygonal cross-section structure made of FRP can also be obtained by the following manufacturing process: for example, a collapse core wrapped with a prepreg of a fiber-reinforced resin is arranged in a forming mold having an inner shape corresponding to a desired outer shape, and the prepreg is formed while being pressurized by an autoclave, a press, etc., and heated and cured. The collapse core inside the structure collapses after manufacturing and can be removed from the open end of the structure.

[0005] However, when an irregular cross-sectional structure or a polygonal cross-sectional structure made of FRP is formed through such a manufacturing process, if the prepreg sheet thickness changes during the pressurization and heating process during the forming process, it is possible that wrinkles, voids, resin enrichment and other appearance defects will occur due to the reinforcing fibers that cannot follow the shape change.

[0006] Furthermore, when the molding die has a complex shape, it is difficult to make the prepreg follow the shape of the molding die evenly and stably, and resin accumulation and voids are likely to occur in corners and other parts where the fusion degree with the molding die is poor. Such undesirable situation not only reduces the appearance quality, but also causes the deviation of product quality such as component strength.

[0007] In contrast, Patent Document 1 discloses a technique for forming an FRP structure having an arbitrary hollow cross-sectional shape. According to the technique disclosed in Patent Document 1, a hollow core having a reinforcing fiber substrate disposed on the periphery is placed in a mold cavity of a forming mold, and after the mold is closed, a resin is injected into the forming mold while pressurizing the inside of the core, thereby forming an FRP structure having an outer shape corresponding to the mold, that is, an irregular cross-section or a polygonal cross-section.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2006-159457 Summary of the invention

[0011] Problem that the invention aims to solve

[0012] According to the technology of Patent Document 1, by injecting resin into the forming mold while pressurizing the hollow core disposed in the forming mold, it is possible to prevent wrinkles, voids, and other defects in an FRP hollow structure having an arbitrary hollow cross-section. However, this technology requires large equipment such as a resin flow path for injecting resin into the forming mold, which has the problem of costly.

[0013] In addition, according to the technology of Patent Document 1, a relatively large opening is required to remove the hollow core from the end of the FRP hollow structure after manufacturing, and the opening may become a hindrance depending on the purpose of the structure. In particular, the collapse core and the hollow core cannot be removed from the irregular cross-section structure with closed ends after manufacturing, so they have to remain inside the structure, which may cause undesirable conditions such as increased weight and abnormal noise. Therefore, it is desired to have a technology for manufacturing FRP structures from a different perspective than before.

[0014] Therefore, an object of the present invention is to provide a method for producing an FRP structure having a high degree of freedom in cross-sectional shape despite low cost, and to provide the structure.

[0015] Solutions for solving problems

[0016] In order to achieve the above object, the manufacturing method of the structure of the present invention comprises the following steps:

[0017] A winding step of winding a plurality of composite raw materials including reinforcing fibers and uncured thermosetting resin around a hollow cylindrical core material to form a cylindrical laminate;

[0018] A pressing step of winding a strip or a film around the outer periphery of the aforementioned laminate and applying pressure;

[0019] a preheating step of heating the laminate to cure the laminate before the thermosetting resin is completely cured, that is, when the degree of cure of the thermosetting resin is in the range of 30% to 90%; and

[0020] The main heating step is to place the laminated body wound with the strip or film and the cylindrical core material in a forming mold, heat the laminated body until the thermosetting resin is completely cured, and apply pressure to deform the cylindrical core material into a non-circular cross-sectional shape.

[0021] A structure is formed in which the cylindrical core material and the laminated body are integrated.

[0022] In addition, the method for manufacturing the structure of the present invention comprises the following steps:

[0023] A first winding step of winding a plurality of first composite materials including first reinforcing fibers and uncured first thermosetting resin around a core rod to form a cylindrical inner laminate;

[0024] A first pressing step of applying pressure around the inner laminate;

[0025] A first heating step of heating the inner laminate until the first thermosetting resin is completely cured;

[0026] A second winding step of winding a plurality of second composite materials including a second reinforcing fiber and an uncured second thermosetting resin around the cured inner laminate to form a cylindrical outer laminate;

[0027] A second pressing step of pressing the periphery of the outer laminate;

[0028] A preheating step of heating the outer laminate to a state before the second thermosetting resin is completely cured;

[0029] an extraction step of extracting the core rod from the outer laminate and the inner laminate; and

[0030] In the main heating step, the outer laminate and the inner laminate are arranged in a molding die, the outer laminate is heated until the second thermosetting resin is completely cured, and pressurized to deform the outer laminate.

[0031] Furthermore, the structure described in the present invention is a hollow structure having:

[0032] an inner laminate formed by curing a first thermosetting resin containing first reinforcing fibers; and

[0033] an outer laminate formed by curing a second thermosetting resin containing second reinforcing fibers, wherein the outer laminate is formed so as to protrude outward from an end portion of the inner laminate,

[0034] The inner laminate inserted into the inner side of the outer laminate maintains the shape of the outer laminate,

[0035] Another member is inserted into the inner side of the inner stack, and a space is formed between the other member and the inner stack.

[0036] A portion of the inner periphery of the end portion of the outer stack protruding outward from the end portion of the inner stack is in close contact with the outer periphery of the other member.

[0037] Furthermore, the structure described in the present invention is a hollow structure having:

[0038] an inner laminate formed by curing a first thermosetting resin containing first reinforcing fibers; and

[0039] an outer laminate formed by curing a second thermosetting resin containing second reinforcing fibers, wherein the outer laminate is formed so as to protrude outward from an end portion of the inner laminate,

[0040] The inner laminate inserted into the inner side of the outer laminate maintains the shape of the outer laminate,

[0041] The structure is closed in a state where another member is inserted into one end of the outer stack and another member is not inserted into the other end of the outer stack.

[0042] Effects of the Invention

[0043] According to the present invention, a method for producing an FRP structure having a high degree of freedom in cross-sectional shape and a structure can be provided despite low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a diagram showing a winding step in the method for producing a structure according to the first embodiment, and shows a prepreg and a cylindrical core material in a plan view.

[0045] Figure 2 It is a diagram showing a pressing step in the method for manufacturing a structure according to the first embodiment.

[0046] Figure 3 It is a diagram showing a preheating step in the method for producing a structure according to the first embodiment.

[0047] Figure 4This is a diagram showing an example of a DSC curve of an uncured thermosetting resin, in which the vertical axis represents heat flow and the horizontal axis represents temperature.

[0048] Figure 5 : is a figure which shows an example of the DSC curve of the thermosetting resin after complete curing, and the vertical axis|shaft represents heat flow, and the horizontal axis|shaft represents temperature.

[0049] Figure 6 This is a diagram showing a cutting step in the method for manufacturing a structure according to the first embodiment, and shows a state in which the end portion of the cylindrical core material is cut.

[0050] Figure 7 This is a diagram showing a part of the main heating step in the method for producing a structured body according to the first embodiment, and shows a state before mold clamping as viewed along the axial direction of the stacked body.

[0051] Figure 8 It is a cross-sectional view showing a part of the main heating step in the method for manufacturing the structure according to the first embodiment, and shows a state in which the mold is closed and heated.

[0052] Fig. 9 This is a perspective view of a structure manufactured by the manufacturing method according to the first embodiment.

[0053] Fig.10 This is a diagram showing a part of the main heating step in the method for producing a structure according to a modified example, and shows a state before mold clamping as viewed along the axial direction of the stacked body.

[0054] Fig.11 This is a perspective view of a structure manufactured by the manufacturing method described in the modification of the first embodiment.

[0055] Fig.12 It is a diagram schematically showing a first winding step in the method for producing a structure according to the second embodiment.

[0056] Fig.13 This is a diagram schematically showing a first pressing step in the method for producing a structure according to the second embodiment, and shows a prepreg and a core rod in a plan view.

[0057] Fig.14 It is a diagram schematically showing a second winding step in the method for producing a structure according to the second embodiment.

[0058] Fig.15 It is a diagram schematically showing a main heating step in the method for producing a structured body according to the second embodiment.

[0059] Fig.16 This is when the mold is closed as viewed along the arrow direction in the AA section. Fig.15A diagram of the state of the composition.

[0060] Fig.17 This is a perspective view of a structure having an irregular cross-sectional shape manufactured by the manufacturing method according to the second embodiment.

[0061] Fig.18 This is a main heating step of the manufacturing method according to the first modified example of the second embodiment. Fig.15 Same picture.

[0062] Fig.19 This is a perspective view of a structure having an irregular cross-section manufactured by the manufacturing method described in the first modification, showing a state in which the internal structure is seen through.

[0063] Fig. 20 This is a main heating step of the manufacturing method according to the second modification of the second embodiment. Fig.15 Same picture.

[0064] Fig.21 This is a perspective view of a structure having an irregular cross-sectional shape manufactured by the manufacturing method described in the second variation.

[0065] Fig. 22 This is a main heating step of the manufacturing method according to the third modification of the second embodiment. Fig.15 Same picture.

[0066] Fig.23 This is a perspective view of a structure having an irregular cross-sectional shape manufactured by the manufacturing method described in the third variation.

[0067] Fig.24 This is a main heating step of the manufacturing method according to the fourth modification of the second embodiment. Fig.15 Same picture.

[0068] Fig.25 This is a perspective view of a structure having an irregular cross-sectional shape manufactured by the manufacturing method described in the fourth variation.

[0069] Fig.26 This is a perspective view of a structure similar to the fourth modification example.

[0070] Fig. 27 This is a perspective view of a structure similar to the second modification example.

[0071] Fig.28 The main heating step of the manufacturing method according to the third embodiment is shown. Fig.15 Same picture.

[0072] Fig.29The figure shows the mold clamping condition when viewed along the arrow direction in the Dx-Dx section. Fig.28 A diagram of the state of the composition.

[0073] Fig.30 This is a perspective view of a composite structure composed of a structure having an irregular cross-sectional shape and a rod material manufactured by the manufacturing method according to the present embodiment.

[0074] Fig.31 It shows the EE section viewed along the arrow direction. Fig.30 A diagram of the state of the composition.

[0075] Fig.32 It shows the FF section viewed along the arrow direction Fig.30 A diagram of the state of the composition.

[0076] Fig.33 is a composite structure similar to the third embodiment. Fig.32 Same cross-section view.

[0077] Fig.34 It shows the GG section viewed along the arrow direction. Fig.33 A diagram of the state of the composition.

[0078] Fig.35 is a composite structure similar to the third embodiment. Fig.30 Same stereogram.

[0079] Fig.36 It shows the HH section viewed along the arrow direction Fig.35 A diagram of the state of the composition.

[0080] Fig.37 is a composite structure similar to the third embodiment. Fig.32 Same cross-section view. DETAILED DESCRIPTION

[0081] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0082] It should be noted that, in this specification, "reinforced fiber" is preferably organic fiber represented by carbon fiber, glass fiber, aramid fiber, silicon carbide fiber, metal fiber, etc. Furthermore, "thermosetting resin" is preferably epoxy resin, polyester resin, vinyl ester resin, phenolic resin, urethane resin, polyimide resin, etc., and more preferably the more commonly used epoxy resin.

[0083] The "laminate", "inner laminate" and "outer laminate" can be formed by using a sheet winding method to wind a sheet of prepreg (composite raw material) that is made into a semi-cured state by impregnating reinforcing fibers with a thermosetting resin and heating or drying. In addition, they can be formed by winding a strip of prepreg using a strip winding method.

[0084] Alternatively, these laminates can be formed by winding the roving fibers while impregnating the roving fibers with resin. Among them, the sheet winding method and the strip winding method are more preferred because they can use prepregs with a controllable and stable ratio of resin to reinforcing fibers.

[0085] As the prepreg, for example, TORAYCA (registered trademark) manufactured by Toray Industries, Inc. can be preferably used.

[0086] The “cylindrical core material” is preferably made of a thin-walled metal (eg, SUS) that has a certain degree of rigidity and is plastically deformable. Alternatively, a hollow laminated body obtained by completely curing a thermosetting resin impregnated into reinforcing fibers may be used.

[0087] The material of the "core rod" can be any of metal, resin, ceramic, etc., and metal is preferably used from the viewpoint of cost and durability. In addition, the shape of the core rod is preferably a solid cylinder or a hollow cylinder, and can be a divisible shape rather than a single shape.

[0088] The "polygonal shape" is preferably a quadrilateral or larger.

[0089] In this specification, "strip or film" refers to a thin-walled member regardless of the raw material. Among them, from the viewpoint of ease of use, it is preferred to use a strip. The strip may be made of any of resin or metal, and it is preferred to use a resin strip with good workability. In addition, when using a resin strip, it may be any of polypropylene, polyethylene, polyester, cellophane, Teflon (registered trademark), polyimide, etc. From the viewpoint of a good balance of strip properties, it is preferred to use polypropylene or polyester.

[0090] [First embodiment]

[0091] A method for manufacturing the structure according to the first embodiment will be described. Figure 1 Schematically shows the winding process. Figure 1 As shown, a cylindrical core material CY and various prepreg sheets PS1 to PS6 are prepared. The cylindrical core material CY is used as a core rod for stacking and winding prepreg in the winding process, used as a tool for maintaining the shape of the stacked body in the main heating process, and used as a reinforcing member integrated with the structure after manufacturing.

[0092] Considering the thickness of the laminate wound to the outside, the outer diameter of the cylindrical core material CY is set slightly smaller than the outer circumference of the final structure. That is, it is expected that the outer diameter of the cylindrical core material CY in the state where the plurality of prepreg sheets are wound around the cylindrical core material CY is roughly consistent with the design value of the outer circumference of the final structure.

[0093] Prepreg sheets PS1 to PS6 are obtained by impregnating carbon fibers with epoxy resin raw materials. In each prepreg sheet, the carbon fibers are oriented regularly. Figure 1 The solid line in shows the orientation direction of the carbon fibers. Hereinafter, the orientation direction of the carbon fibers is defined as the direction in a state where the prepreg sheet is developed.

[0094] (Winding process)

[0095] The winding process of the present manufacturing method is described. The prepreg sheet PS1 is made by overlapping and bonding two layers of a sheet with a carbon fiber orientation direction of +45 degrees and a sheet with a -45 degree orientation relative to the axis of the cylindrical core material CY, and has the function of resisting the torsional stress borne by the structure. The prepreg sheet PS1 is wound around the outer periphery of the cylindrical core material CY, which has been subjected to a peeling treatment as needed.

[0096] The orientation direction of the carbon fibers of the prepreg sheets PS2, PS3 and PS4 is parallel to the axis of the cylindrical core material CY, and has the function of resisting the tensile stress borne by the structure. The prepreg sheets PS2, PS3 and PS4 are sequentially wound on the prepreg sheet PS1.

[0097] In the prepreg sheet PS5, the orientation direction of the carbon fibers is perpendicular to the axis of the cylindrical core material CY, and has a function of resisting expansion when the structure is subjected to compressive stress. This prepreg sheet PS5 is wound around the prepreg sheet PS4.

[0098] In the pair of prepreg sheets PS6, the orientation direction of the carbon fibers is perpendicular to the axis of the cylindrical core material CY, and the pair of prepreg sheets PS6 has a trapezoidal shape. The prepreg sheets PS6 are wound around both ends of the prepreg sheet PS5.

[0099] In this embodiment, the reinforcing effect is achieved by winding only the outermost prepreg sheets PS6 at both ends. The number of prepreg sheets and the orientation direction of carbon fibers can be appropriately changed according to the desired mechanical strength of the structure.

[0100] In this way, a cylindrical laminate LM ( Figure 2 ).

[0101] (Pressure process)

[0102] The pressurizing step of the present production method will be described. Figure 2 It is a diagram schematically showing a pressurizing process. Figure 2 In the process, one end of the cylindrical core material CY around which the laminate LM is wound is connected to a rotation driving body RD such as a motor shaft, and one end of a thin strip TP (here transparent) is attached to the outer periphery of the laminate LM.

[0103] From this state, the cylindrical core material CY is rotated together with the rotary drive body RD, and a predetermined tension is applied to wind the strip TP around the outer periphery of the laminate LM. The predetermined tension varies depending on the conditions such as the outer diameter of the laminate LM, and is preferably in the range of 1 to 5 kgf. By compressing and pressurizing the prepreg sheets PS1 to PS6 thus laminated, the gaps between the prepreg sheets can be eliminated, and the laminate LM can be densified.

[0104] Furthermore, by relatively moving the strip TP in the direction of the axis O of the cylindrical core material CY, the strip TP is entirely wound in the direction of the axis O of the laminated body LM, and a thin layer having a substantially uniform thickness is formed.

[0105] The means for pressurizing the laminate LM wound around the cylindrical core material CY is not limited to the strips, but for example, a tube made of a heat shrinkable film may be arranged around the laminate LM, and the laminate LM may be compressed by heating the heat shrinkable film to shrink it.

[0106] Alternatively, a product (rubber tube) made of a rubber strip or rubber film may be placed around the laminate LM to compress the laminate LM using its elastic force. This eliminates the need for a rotary drive body to rotate the cylindrical core material CY, and reduces equipment costs.

[0107] (Preheating process)

[0108] The preheating step of the present production method will be described. Figure 3 Schematically showing the preheating process. The laminate LM wound with the strip TP is placed in an oven OV together with the cylindrical core material CY. The laminate LM is heated in the oven OV until the resin of the prepreg sheet of the laminate LM is heated to a state before it is completely cured. More specifically, the laminate LM is heated in such a way that the degree of cure of the thermosetting resin reaches 30 to 90%.

[0109] Here, the degree of curing of thermosetting resins is described. For example, when an uncured epoxy resin is heated from room temperature to 200°C at a rate of 5°C / min, and the heat flow (exothermic or endothermic) is measured using DSC (differential scanning calorimetry), it is known that a phenomenon unique to thermosetting resins occurs.

[0110] Specifically, if Figure 4As shown in the DSC curve, a strong exotherm occurs from about 103°C, an exotherm peak occurs at 110.7°C, and then the exotherm decreases sharply. This exotherm indicates that the epoxy resin is polymerized (cured) by heating. Here, 110.7°C is referred to as the maximum exotherm temperature of the epoxy resin.

[0111] It can be seen that if the epoxy resin is cooled to room temperature again and heated to 200°C at a rate of 5°C / min again, Figure 5 As shown in the DSC curve, there is no exothermic peak, but endothermic peak occurs, and glass transition occurs at 116.1°C. This is a phenomenon caused by the complete curing of the epoxy resin. ("Investigation on the curing temperature and glass transition temperature of epoxy resin", MST technical data: No. C0220, published on October 20, 2011, Foundation: Materials Science and Technology Promotion Foundation)

[0112] On the other hand, if the heating is interrupted before the epoxy resin is completely cured, the exothermic peak becomes X°C ( Figure 4 ). This means that there is room for the epoxy resin to further polymerize, that is, the epoxy resin is in a state before it is completely cured.

[0113] In other words, by measuring the exothermic peak when the thermosetting resin is heated at any time and interrupting the heating when the temperature is lower than the maximum exothermic temperature X°C, the thermosetting resin can be kept in a state before being completely cured.

[0114] Figure 4 In the figure, the area enclosed by the DSC curve at the time of complete curing and the baseline BS (called the exothermic peak area) is recorded as S1, and the area enclosed by the DSC curve with an exothermic peak of X°C and the baseline BS is recorded as S2, and (S2 / S1)×100% is defined as the degree of curing of the thermosetting resin.

[0115] The inventors of the present invention have found that the formability of the laminate LM can be improved by utilizing the thermal characteristics of the thermosetting resin and interrupting the heating of the laminate LM before the thermosetting resin is completely cured, for example, when the degree of cure is 30 to 90%. The exothermic peak X°C corresponding to the degree of cure of 30 to 90% can be obtained by experiments and simulations. The effect of improving the formability of the laminate LM will be described later in connection with the main heating process.

[0116] (Cutting process)

[0117] The cutting step of the present production method will be described. Figure 6 Schematically showing the cutting process. The laminated body LM wound with the strip TP is taken out of the oven OV. Figure 6As shown in FIG. 1 , at the end position (D) of the laminate LM, the two ends of the cylindrical core material CY are cut off. The component including the laminate LM and the cylindrical core material heated until completely solidified is called a preform. It should be noted that the cylindrical core material CY can also be left without being cut off, for example, for use in combination with other components or in forming bolts for screwing.

[0118] Unheated laminates need to be stored in a refrigerator or cold storage to prevent degradation of the resin material. However, the laminate LM in the preform formed is a laminate with the degree of curing of the resin material adjusted, and there is almost no degradation of the resin material even if it is stored at room temperature. Therefore, by mass-producing preforms in advance and storing them, products can be supplied in response to urgent needs.

[0119] Furthermore, since a variety of structures can be formed from one type of preform, a reduction in manufacturing cost can be achieved.

[0120] (Main heating process)

[0121] The main heating step of the present production method will be described. Figure 7 , 8 Schematically shows the main heating process. Figure 7 As shown in FIG. 1 , the laminated body LM whose inner periphery is supported by the cylindrical core material CY is arranged between the plate-shaped upper die UD and the groove-shaped lower die LD. The upper die UD and the lower die LD constitute a forming die.

[0122] Here, when the width of the bottom surface of the groove in the lower mold LD is denoted as W, the height of the inner wall of the groove is denoted as H, and the outer diameter of the stacked body LM wound with the strip TP is denoted as D, if πD≈2(W+H), the inner circumference of the mold can be made roughly consistent with the outer circumference of the final structure, thereby obtaining a structure with a stable shape.

[0123] Afterwards, if Figure 8 As shown in the figure, the upper mold UD and the lower mold LD are brought relatively close to each other for mold clamping. As a result, the cylindrical core material CY is plastically deformed (partially elastically deformed) into a square cylinder. At the same time, since the thermosetting resin of the laminated body LM is heated to a curing degree of less than 90% by the previous preheating process, the laminated body LM can be deformed in a manner along the inner wall shape formed by the upper mold UD and the lower mold LD.

[0124] Here, since the cylindrical core material CY has a certain degree of rigidity, it resists the pressure from the forming die, thereby maintaining the deformed state of the laminated body LM along the die and suppressing its collapse.

[0125] Furthermore, by heating the interior of the upper mold UD and the lower mold LD using a heater (not shown), the laminated body LM can be completely cured. The cylindrical core material CY also maintains the square cylindrical deformation due to the cured laminated body LM.

[0126] According to the present embodiment, the strip TP with high sliding property is wound around the laminate LM with a predetermined tension. Therefore, when the outer surface of the laminate LM and the inner wall surface of the forming mold are relatively displaced with the pressurization of the upper mold UD and the lower mold LD, the two can slide with almost no resistance. As a result, the mold adaptability of the laminate LM is improved, and a stable product shape can be obtained. Therefore, especially at the corner CR, it is not easy to cause a local pressure drop due to the resistance caused by the strip TP, and the undesirable conditions such as wrinkles, voids, and resin enrichment of the laminate LM can be effectively suppressed, and stable product quality can be obtained.

[0127] On the other hand, the mold adaptability of the laminated body LM is improved, so the pressure of the forming mold can be reduced, and the strength and rigidity of the mold can be reduced, so the freedom of choice of the mold material that can be used is expanded. In addition, the equipment that drives the forming mold can also be simplified, thereby reducing the equipment cost.

[0128] Furthermore, due to the shape-retaining function of the strip TP, the intersection of the side surface (first surface) and the upper and lower surfaces (second surfaces whose normal direction is different from that of the first surface) of the laminate LM formed by strong pressure on the right-angled corner CR has a curved surface with a constant or slowly changing curvature (i.e., no edges are formed at the intersection). Furthermore, since the reinforcing fibers at the intersection are bent without breaking (the continuity of the fibers is maintained), the strength of the structure can be ensured.

[0129] (Peeling process)

[0130] Thereafter, the heating is stopped and the upper mold UD is separated from the lower mold LD, and the strip TP is peeled off from the laminated body LM deformed into a rectangular tube shape, thereby completing the Fig. 9 The structure (polygonal structure) ST1 with a partially rectangular cross-sectional shape is shown in FIG. As for the structure ST1, since the laminated body LM is closely formed on the outer periphery of the cylindrical core material CY whose cross section is deformed into a square and the two are integrated, it presents a hybrid structure having both the metal property of anti-bending and the FRP property of light weight and high strength. Therefore, the structure ST1 can be used as an impact absorbing structure, such as a vehicle. In addition, the structure ST1 can also be combined with other components such as metal, thereby expanding the use.

[0131] (Variation Example)

[0132] Fig.10 The main heating step of the manufacturing method according to the modified example is shown. Figure 7 Same figure. In this modification, the upper mold UD and the lower mold LD have a common shape, specifically, they have trapezoidal transfer surfaces facing each other, and a hexagonal shape is formed by a pair of transfer surfaces when the molds are closed. In this modification, similarly to the above-mentioned embodiment, a preform is used in which a laminated body LM is wound around the outer periphery of a cylindrical core material CY and a strip TP is wound around the outer periphery.

[0133] like Fig.10 As shown in the figure, the preform is arranged between the upper mold UD and the lower mold LD, and the upper mold UD and the lower mold LD are brought relatively close to each other for mold clamping. In the preheating step, the thermosetting resin of the laminate LM is heated to a curing degree of 90% or less, so that the laminate LM can be deformed into a hexagonal shape along the inner wall shape formed by the upper mold UD and the lower mold LD. Furthermore, by using a heater (not shown) to heat the inside of the upper mold UD and the lower mold LD, the laminate LM can be completely cured.

[0134] Thereafter, the upper mold UD and the lower mold LD are separated to remove the Fig.11 The structure (polygonal structure) ST2 having a hexagonal cross-sectional shape shown. In the structure ST2, a laminate LM is formed on the periphery of a cylindrical core material CY whose cross section is deformed into a hexagonal shape. For example, by arranging the structures ST2 so that the axes are parallel and without gaps, a honeycomb-shaped impact absorber with almost no space between adjacent structures ST2 can be formed.

[0135] It should be noted that the first laminate LM1 formed by the first winding step, the first pressing step and the first heating step in the manufacturing method of the second embodiment described later can be used as the cylindrical core material CY. In addition, a portion of the preform in the longitudinal direction can be subjected to pressurization deformation based on the forming mold, thereby forming a structure with an irregular cross-section.

[0136] [Second Embodiment]

[0137] Next, a manufacturing method according to the second embodiment will be described. Fig.12 Schematically shows the first winding process. Figure 1 As shown, a core rod (mandrel) MD having a circular cross section and prepreg sheets (composite material) PS11 and PS12 in a semi-cured state are prepared by impregnating first reinforcing fibers with a first thermosetting resin and heating or drying them.

[0138] As with the cylindrical core material CY, the outer diameter of the mandrel rod MD is slightly smaller than the outer diameter of the product. In addition, the total length of the mandrel rod MD is greater than the product length of the structure.

[0139] (First Winding Step)

[0140] The outer periphery of the mandrel MD is subjected to demoulding treatment as needed, and the prepreg sheets PS11 and PS12 are wound around the mandrel MD. As a winding method, the above-mentioned winding method can be used. As the first reinforcing fiber and the first thermosetting resin, any fiber and resin can be selected from the above-mentioned reinforcing fibers and thermosetting resins.

[0141] The fiber orientation direction of the prepreg sheets PS11 and PS12 is preferably inclined within a range of 15° to 90° with respect to the axis of the core rod MD. This ensures that the preform has sufficient strength to withstand the pressure during mold clamping when it is formed.

[0142] In this way, a cylindrical first laminate (inner laminate) LM1 (LM2) is formed by winding the prepreg sheets PS11 and PS12 around the core rod MD. Fig.13 ). It should be noted that three or more prepreg sheets may be wound around the core rod MD. In addition, a hollow cylindrical member may be inserted into the core rod MD instead of the first laminate, and the following steps may be performed.

[0143] (First Pressing Step)

[0144] The first pressurizing step of the present production method will be described. Fig.13 It is a diagram schematically showing the first pressurizing step. Fig.13 In the process, one end of the mandrel MD wound with the first laminate LM1 is connected to a rotation driving body RD such as a motor shaft, and one end of a thin first tape TP1 (which may be a film) is attached to the outer periphery of the first laminate LM1.

[0145] The core rod MD is rotated together with the rotary drive body RD from this state, and the first tape TP1 is wound around the outer periphery of the first laminate LM1 while applying a predetermined tension. The predetermined tension varies depending on the conditions such as the outer diameter of the first laminate LM1, and is preferably in the range of 1 to 5 kgf. Thus, the stacked prepreg sheets PS11 and PS12 are pressurized, thereby removing the gaps between the prepreg sheets and achieving the densification of the first laminate LM1.

[0146] Furthermore, by relatively moving the first tape TP1 in the direction of the axis O of the mandrel MD, the first tape TP1 is wound in the entire direction of the axis O of the first laminate LM1 to form a thin layer having a substantially uniform thickness.

[0147] The means for pressurizing the first laminate LM1 wound around the mandrel MD is not limited to the first strip. For example, a tube made of a heat shrinkable film may be arranged around the first laminate LM1 and the heat shrinkable film may be shrunk by heating to pressurize the first laminate LM1.

[0148] Alternatively, a rubber band or rubber film may be formed into a tube (rubber tube) and arranged around the first laminate LM1 to apply pressure to the first laminate LM1 by its elastic force. This eliminates the need for a rotary drive body to rotate the mandrel MD, and reduces equipment costs.

[0149] (First Heating Step)

[0150] The first laminate LM1 wound with the first tape TP1 is placed in an oven (not shown) together with the mandrel MD, and the temperature in the oven is set to 135° C., for example, and heated for 2 hours. Thus, the first laminate LM1 is completely cured.

[0151] Thereafter, the first laminate LM1 is taken out of the oven together with the core rod MD, and the first tape TP1 wound around the outer periphery is peeled off. Thereafter, the outer peripheral surface of the first laminate LM1 is roughened by grinding or the like, thereby forming a minute concave-convex structure. Alternatively, a thin fabric sheet (discarded skin) may be wound on the outermost layer after the prepreg sheet PS12 is wound through the first winding process, and after the first tape TP1 after the first heating process is peeled off, the discarded skin is peeled off, thereby forming minute convex-convex structures on the surface. Furthermore, an adhesive sheet may be wound around the outer periphery of the first laminate LM1. Thus, the adhesion between the first laminate LM1 and the second laminate LM2 described later is improved.

[0152] (Second Winding Process)

[0153] Next, the second winding step of the present production method will be described. Fig.14 Schematically showing the second winding process. Prepreg sheets PS13 to PS17 are composite raw materials made by impregnating the second reinforcing fiber with the second thermosetting resin and heating or drying to form a semi-cured state. As the second reinforcing fiber and the second thermosetting resin, any fiber and resin can be selected from the above-mentioned reinforcing fibers and thermosetting resins. The second reinforcing fiber may be the same as or different from the first reinforcing fiber. In addition, the second thermosetting resin may be the same as or different from the first thermosetting resin. In addition, the outer laminate may be wound around at least a portion of the inner laminate.

[0154] The prepreg sheet PS13 is made by overlapping and bonding two layers of a sheet with a fiber orientation direction of +45 degrees and a sheet with a fiber orientation direction of -45 degrees relative to the axis of the core rod MD, and has the function of resisting the torsional stress borne by the structure. The prepreg sheet PS13 is made to protrude from both ends of the first laminate LM1 along the length direction and is wound around the outer periphery of the core rod MD. As a winding method, the above-mentioned winding method can be used, and the same applies to the following.

[0155] The orientation direction of the fibers of each prepreg sheet PS14, PS15 is parallel to the axis of the core rod MD, and has a function of resisting the tensile stress to which the structure is subjected. The prepreg sheets PS14, PS15 are sequentially wound around the prepreg sheet PS13 of the same length.

[0156] The orientation direction of the fibers of the prepreg sheet PS16 is perpendicular to the axis of the core rod MD, and it has a function of resisting expansion when the structure is subjected to compressive stress. The prepreg sheet PS16 is wound around the prepreg sheet PS15 of the same length.

[0157] The fibers of the pair of prepreg sheets PS17 are oriented in a direction perpendicular to the axis of the core rod MD, and have a trapezoidal shape. The prepreg sheets PS17 are wound around both ends of the prepreg sheet PS16.

[0158] In this embodiment, the outermost prepreg sheet PS17 is wound only at both ends to achieve a reinforcing effect. The number of prepreg sheets and the orientation direction of the fibers can be appropriately changed according to the desired mechanical strength of the structure.

[0159] In this way, a second laminate (outer laminate) LM2 is formed by winding a plurality of prepreg sheets around the first laminate LM1. It should be noted that in order to avoid height differences in the longitudinal direction, it is preferred that the first laminate LM1 and the second laminate LM2 are joined in a manner that changes the outer diameters gradually.

[0160] (Second Pressing Step)

[0161] The second tape TP2 (which may be a film) is wound around the outer periphery of the second laminated body LM2 formed on the mandrel MD in the same manner as the pressing step of the first embodiment. Other pressing means as described above may be used instead of the second tape.

[0162] (Preheating process)

[0163] A core rod MD with a second strip TP2 wound around the outer periphery of the second stack LM2 is arranged in an oven not shown in the figure, and is heated in the same manner as the preheating process of the first embodiment until the resin of the prepreg sheet of the second stack LM2 is in a state before it is completely cured, that is, the degree of cure of the thermosetting resin of the second stack LM2 is made to be 30 to 90%.

[0164] (Extraction process)

[0165] Thereafter, the mandrel MD is taken out of the oven and extracted from the first stack LM1 and the second stack LM2. At this time, the second stack LM2 is supported by the first stack LM1 that has been heated and solidified, and the second strip TP2 is wound around the outer periphery of the second stack LM2, so that the cylindrical shape can be maintained even if the mandrel MD is pulled out. A component including the first stack LM1 that has been completely solidified and the second stack LM2 that has been heated until it is completely solidified is called a preform. The preform in which the second stack LM2 is wound around the mandrel MD and densified can be produced with relatively simple equipment and stable quality.

[0166] Even if the first laminate LM1 is completely heated, if the second laminate LM2 is not heated, it needs to be stored in a refrigerator or cold storage to prevent degradation of its resin material. However, in the preform formed, the first laminate LM1 is stable, and the second laminate LM2 is a laminate with adjusted curing degree of the resin material, and there is almost no degradation of the resin material even if it is stored at room temperature. Therefore, by mass-producing and storing preforms in advance, products can be supplied in response to urgent needs.

[0167] In addition, a variety of structures can be formed from one preform (see below). Fig.17 , 19 , 21, 23), therefore, the manufacturing cost can be reduced.

[0168] (Main heating process)

[0169] The main heating step of the present production method will be described. Fig.15 It is a diagram schematically showing the main heating process. Fig.16 The figure shows the mold closing when viewed along the arrow direction in the AA section. Fig.15 A diagram of the state of the composition.

[0170] First, if Fig.15 As shown in the figure, a pair of upper mold UD and lower mold LD are arranged so as to sandwich both ends of the preform formed of the first laminate LM1 and the second laminate LM2. The upper mold UD and the lower mold LD constitute a forming die.

[0171] The upper mold UD and the lower mold LD have a common shape. Specifically, the block-shaped upper mold UD has a flat surface UDc, a semi-cylindrical concave surface UDa having a diameter substantially the same as that of the second stack LM2, and a concave curved transition surface UDb connecting the flat surface UDc and the concave surface UDa. In addition, the block-shaped lower mold LD has a flat surface LDc, a semi-cylindrical concave surface LDa having a diameter substantially the same as that of the second stack LM2, and a concave curved transition surface LDb connecting the flat surface LDc and the concave surface LDa.

[0172] like Fig.15 As shown, the preform is arranged between the upper mold UD and the lower mold LD so that the concave surfaces UDa and LDa are located radially outside the end of the first laminate LM1 and the flat surfaces UDc and LDc are located radially outside the end of the second laminate LM2.

[0173] If the upper mold UD and the lower mold LD are brought relatively close to each other in this state and then the molds are closed, the flat surfaces UDc and LDc will clamp the ends of the preform. Since the thermosetting resin of the second laminate LM2 is heated to a curing degree of 90% or less by the previous preheating step, the second laminate LM2 can be easily deformed in a manner of being flattened by the flat surfaces UDc and LDc (see Fig.16 ).

[0174] At this time, since the second tape TP2 is wound around the second stack LM2 under a predetermined tension, and the second tape TP2 has a shape-maintaining function, even if the second stack LM2 is pressed into a flat plate, the two edges of the end of the second stack LM2 ( Fig.16 The outer surface of the left and right sides of the structure also has a curved surface with a constant or slowly changing curvature. As a result, the appearance quality of the structure and the strength against bending or torsion can be improved. In addition, by bending the reinforcing fibers passing through the two edges without breaking them (maintaining the continuity of the fibers), higher strength can be ensured. However, depending on the cross-sectional shape of the structure, the second strip TP2 is not necessarily used.

[0175] On the other hand, the central part of the second stack LM2 is maintained in a cylindrical shape by resisting the pressure of the forming mold with the help of the solidified first stack LM1. In particular, by providing the second stack LM2 with concave surfaces UDa and LDa on the outer periphery of the first stack LM1, it is possible to maintain a cylindrical shape with good precision without directly applying pressure.

[0176] Furthermore, by heating the upper mold UD, the lower mold LD, and the second laminated body LM2 as a whole using a heater or an oven (not shown), the second laminated body LM2 can be completely cured in the deformed state.

[0177] Thereafter, the upper mold UD is separated from the lower mold LD, and the second tape TP2 is peeled off, thereby obtaining Fig.17 The structure (irregular cross-sectional structure) ST3 shown in FIG. The structure ST3 has a hollow cylindrical central portion CT and a closed flat end ED. The intermediate surface MP connecting the central portion CT and the end ED is pressed from the upper and lower directions by the transition surfaces UDb and LDb, so that each is formed into a partial spherical shape. By providing the intermediate surface MP, a sharp shape change between the central portion CT and the end ED is avoided, and stress concentration can be suppressed.

[0178] For example, if a bolt hole is formed at the end ED, the bolt hole can be used to bolt the structure ST3 to other components. Here, both ends ED of the structure ST3 are made into a shape consistent with the horizontal plane. However, by changing the mold closing direction of the forming mold, it is also possible to make the structure ST3 such that one end ED is consistent with the horizontal plane and the other end ED is consistent with the vertical plane. In addition, it is also possible to use only a pair of upper molds UD and lower molds LD to form a single end ED in sequence. As a result, the equipment cost can be greatly reduced.

[0179] (First Modification)

[0180] Fig.18 This is a main heating step of the manufacturing method according to the first modification example and Fig.15 Same figure. In this modification, the upper mold UD and the lower mold LD are used in the same manner as in the second embodiment to pressurize and heat the preform, and before pressurization, the metal plate MT is embedded in both ends of the second laminate LM2. By the subsequent clamping of the upper mold UD and the lower mold LD, the plate MT is pressed against the upper and lower parts of the end of the second laminate LM2, and while maintaining this state, the second laminate LM2 is heated and cured.

[0181] According to the first modification, the upper mold UD and the lower mold LD are heated and pressurized to produce Fig.19 The irregular cross-sectional structure (irregular cross-sectional structure) ST4 shown. The structure ST4 has a central portion CT in a hollow cylindrical shape and an end portion ED in which a plate MT is embedded. Therefore, even if a bolt hole is formed at the end portion ED, it is not easy to break, and the function as a structure is further improved. It should be noted that the component embedded in the end portion of the second stack LM2 is not limited to metal. For example, by embedding rubber, resin, etc., the central portion CT of the structure ST4 can also be sealed to prevent gas and fluid from flowing in from the outside.

[0182] (Second Modification)

[0183] Fig. 20 The main heating step of the manufacturing method according to the second modification is shown. Fig.15Same figure. In this modification, an upper mold UD and a lower mold LD having shapes different from those of the second embodiment are used. Specifically, the block-shaped upper mold UD has a flat surface UDc, a semi-cylindrical concave surface UDa having a diameter substantially the same as that of the second stack LM2, and a planar transition surface UDb connecting the flat surface UDc and the concave surface UDa. In addition, the block-shaped lower mold LD has a flat surface LDc, a semi-cylindrical concave surface LDa having a diameter substantially the same as that of the second stack LM2, and a planar transition surface LDb connecting the flat surface LDc and the concave surface LDa. The configuration other than this is the same as that of the above-mentioned embodiment.

[0184] According to the second modification, the upper mold UD and the lower mold LD are heated and pressurized to produce Fig.21 The structure (irregular cross-sectional structure) ST5 shown in FIG. The structure ST5 has a hollow cylindrical central portion CT, a closed flat end portion ED, and an intermediate surface MP connecting the central portion CT and the end portion ED. The intermediate surface MP is pressed from the upper and lower directions by the transition surfaces UDb and LDb to form a flat surface.

[0185] (Third Modification)

[0186] Fig. 22 The main heating step of the manufacturing method according to the third modification example is shown. Fig.15 Same figure. In this modified example, an upper mold UD and a lower mold LD having shapes different from those of the second embodiment are used. Specifically, the block-shaped upper mold UD has a flat surface UDc, a semi-cylindrical concave surface UDa moved upward compared to the flat surface UDc, a concave curved transition surface UDb connected to the concave surface UDa, and an inclined surface UDd formed between the transition surface UDb and the flat surface UDc. The block-shaped lower mold LD has a flat surface LDc, a semi-cylindrical concave surface LDa moved upward compared to the flat surface LDc, a concave curved transition surface LDb connected to the concave surface LDa, and an inclined surface LDd formed between the transition surface LDb and the flat surface LDc. The inclined surfaces UDd and LDd become parallel when the molds are closed. The other configurations are the same as those of the above-mentioned embodiment.

[0187] According to the third modification, the upper mold UD and the lower mold LD are heated and pressurized to produce Fig.23The structure ST6 of irregular cross-sectional shape shown in the figure (irregular cross-sectional structure) has a hollow cylindrical central portion CT, a closed flat end portion ED, and an inclined plate portion CL formed between the central portion CT and the end portion ED. The inclined plate portion CL is pressed by the inclined surfaces UDd and LDd to form an inclined plate shape. The structure ST6 is formed with the inclined plate portion CL, and therefore has a shape in which the central portion CT is moved upward compared to the end portion ED, thereby avoiding interference with the surrounding components of the structure ST6. It is also possible to make the cross-sectional shape of the central portion CT have an arbitrary curvature.

[0188] (Fourth Modification)

[0189] Fig.24 The main heating step of the manufacturing method according to the fourth modification is shown. Fig.15 Same figure. In this modification, a preform is used in which the first stack LM1 is inserted into the inner sides of both ends of the second stack LM2. In addition, the upper mold UD and the lower mold LD are plate-shaped, and the center of the preform (the position where the first stack LM1 does not exist) is heated and pressed. The other structures are the same as those in the above embodiment.

[0190] According to the fourth modification, the upper mold UD and the lower mold LD are heated and pressurized to produce Fig.25 The structure ST7 with an irregular cross-section is shown. The structure ST7 has a flattened central portion CT and hollow cylindrical end portions ED. The central portion CT of the structure ST7 may not be completely flattened to ensure communication between the two end portions ED in its interior.

[0191] It should be noted that the molding die may be in an angle type in addition to a flat plate shape, whereby the second laminate LM2 is pressed and flattened, thereby forming a structure in which the continuity of the fibers is not impaired in the cross-sectional direction.

[0192] (Other Modifications)

[0193] Fig.26 1 is a perspective view of a structure ST8 similar to the fourth modification. The structure ST8 has three hollow cylindrical portions B and two flat plate portions C. Fig. 27It is a three-dimensional diagram of a structure ST9 similar to the second variant. In the structure ST9, the end portion ED is flattened into a flat plate by the forming mold of the second embodiment, and the central portion CT is formed into an elliptical cross-sectional shape by means of the forming mold of the first embodiment. The first stack LM1 can be deformed to a certain extent. Therefore, by pressing with a forming mold, it can have an arbitrary cross-sectional shape at any position in the length direction and is not limited to a cylindrical cross-section like the structure ST9. That is, according to this embodiment, by making the deformation amount of the central portion of the preform different from the deformation amount of the end portion, an irregular end face structure of an arbitrary shape can be formed. Among them, by using a forming mold with the same mold shape along the length direction, a structure with a polygonal cross-section can also be formed as in the first embodiment.

[0194] As described above, according to the present embodiment, by manufacturing a preform having a first stack LM1 that can withstand external pressure during molding and a second stack LM2 adjusted to a state before being fully solidified in a relatively simple manner, and using the preform, it is possible to efficiently manufacture FRP pipes having a closed cross-sectional shape including an ellipse or a polygon and having a contour shape in which the end portions and / or the middle portion are flattened into a flat plate shape with stable quality from the perspective of productivity and cost.

[0195] The structure formed by this embodiment can have any cross-sectional shape at any position along the longitudinal direction, such as a circular cross-sectional shape (including an elliptical cross-sectional shape) or a non-circular cross-sectional shape (polygonal cross-sectional shape, flat cross-sectional shape, free-shaped cross-sectional shape).

[0196] [Third Embodiment]

[0197] Fig.28 This is a main heating step of the manufacturing method according to the third embodiment. Fig.15 Same picture. Fig.29 The figure shows the mold clamping condition when viewed along the arrow direction in the Dx-Dx section. Fig.28 A diagram of the state of the composition.

[0198] In this embodiment, a preform is used in which a first laminate LM1 having a shorter length dimension than the second laminate LM2 is inserted in the center of the length direction of the second laminate LM2. In addition, the upper mold UD has an upper groove UDe with a circular arc cross section connecting its end to the transition surface UDb. On the other hand, the lower mold LD has a lower groove LDe with a circular arc cross section connecting its end to the transition surface LDb. The other configurations (including the process until the main heating process) are the same as those in the above-mentioned embodiment.

[0199] like Fig.28As shown in the figure, a hollow rod (other member) TB made of fiber reinforced plastic such as CFRP, ceramic, resin or metal (stainless steel, copper, brass, aluminum, etc.) having a lengthwise dimension substantially equal to that of the second stack LM2 is inserted into the second stack LM2 and the first stack LM1. The lengthwise dimension of the rod TB can be made larger than the lengthwise dimension of the second stack LM2 (the same also applies to the following embodiments). Furthermore, the preform and the rod TB are arranged between the upper die UD and the lower die LD in such a manner that the concave surfaces UDa and LDa are located radially outside the end of the first stack LM1 and the upper groove UDe and the lower groove LDe are located radially outside the end of the rod TB.

[0200] If the upper mold UD and the lower mold LD are brought relatively close to each other in this state to close the mold, the upper groove UDe and the flat surface UDc, as well as the lower groove LDe and the flat surface LDc, will clamp the end of the preform. Since the thermosetting resin of the second stack LM2 is heated to a curing degree of less than 90% by the previous preheating process, a part of the second stack LM2 can be pressed against the outer periphery of the rod TB by the upper groove UDe and the lower groove LDe, and the remaining second stack LM2 on both sides of the rod TB can be easily deformed by being flattened by the flat surfaces UDc and LDc (see Fig.29 ). It should be noted that the degree of adhesion between the rod TB and the second stack LM2 can be improved by applying an adhesive or wrapping an adhesive film in advance on the outer peripheral surface of the rod TB that is in close contact with the second stack LM2.

[0201] At this time, since the second tape TP2 is wound around the second stack LM2 under a predetermined tension, and the second tape TP2 has a shape-maintaining function, even if the second stack LM2 is pressed into a flat plate, the two edges of the end of the second stack LM2 ( Fig.29 The outer surface of the left and right sides of the structure also has a curved surface with a constant or slowly changing curvature. As a result, the appearance quality of the structure and the strength against bending or torsion can be improved. In addition, the reinforcing fibers passing through the two edges are also bent without breaking (maintaining the continuity of the fibers), thereby ensuring higher strength. However, depending on the cross-sectional shape of the structure, the second strip TP2 is not necessarily used.

[0202] On the other hand, the central portion of the second stack LM2 resists the pressure of the forming mold with the help of the solidified first stack LM1, and is maintained in a cylindrical shape. In particular, by providing the second stack LM2 with concave surfaces UDa and LDa on the outer periphery of the first stack LM1, it is possible to maintain a cylindrical shape with good precision without directly applying pressure. In addition, on the basis of maintaining the cylindrical shape of the first stack LM1, by keeping the end of the rod TB in the center of the forming mold with the help of the upper groove UDe and the lower groove LDe, the outer periphery of the rod TB inserted into the first stack LM1 will not be in close contact with the inner periphery of the first stack LM1, but a tubular space SP with good precision is formed between the two (described later). Fig.31 , 32 ).

[0203] Furthermore, in the main heating step, the upper mold UD, the lower mold LD, and the second laminate LM2 are heated as a whole using a heater or an oven (not shown), so that the second laminate LM2 can be completely cured in the deformed state.

[0204] Thereafter, the upper mold UD is separated from the lower mold LD, and the second tape TP2 is peeled off, thereby obtaining Figures 30-32 A composite structure HB1 composed of a structure (irregular cross-section structure) ST10 with an irregular cross-section and a rod TB as shown. The structure ST10 has a hollow cylindrical central portion CT and a flat end ED. A portion of the inner circumference of the end ED in the second stack LM2 is in close contact with the outer circumference of the rod TB, and the remaining inner circumferences are in close contact with each other. Among them, the vicinity of the end of the second stack LM2 protruding outward from the first stack LM1 in the longitudinal direction does not contact the rod TB. In addition, in the center of the upper and lower surfaces of the end ED, corresponding to the rod TB, a raised portion HM with a half-moon-shaped cross section extends in the longitudinal direction of the structure ST10.

[0205] According to this embodiment, Fig.31 , 32 As shown in FIG. 1 , a space SP sealed relative to the outside of the structure ST10 is formed between the inner periphery of the structure ST10 and the outer periphery of the rod TB. In addition, the space SP is also sealed relative to the internal space of the hollow rod TB. Therefore, by, for example, circulating a first fluid in the space SP and circulating a second fluid in the rod TB, heat exchange can be performed between the first fluid and the second fluid.

[0206] Alternatively, if a plurality of through holes are provided on the peripheral wall of the hollow rod TB and connected to the exhaust pipe of an internal combustion engine, etc., the composite structure HB1 can also function as a muffler with the space SP as an expansion chamber. In addition, the rod TB is not limited to being hollow, and can be solid. Furthermore, an external thread / internal thread structure, a Swagelok structure (or a connecting hose), etc. can be provided at the ends of the hollow rods TB of the plurality of composite structures HB1 to connect to each other. Thus, the number of connected composite structures HB1 can be adjusted according to the specifications of the heat exchanger, etc., and packaging can be achieved. In addition, if gas is sealed in the enclosed space SP, the structure ST10 has buoyancy, and therefore, by connecting to each other using a belt / rope inside the hollow rods TB of the plurality of composite structures HB1, it can be used for buoys, floating bodies, oil booms, etc. Furthermore, by forming the peripheral wall of the space SP of the hollow rod TB into a permeable membrane structure or an ion (electron) exchange membrane, the composite structure HB1 can also be used as a water purification filter or a structure for a battery.

[0207] (Other Modifications)

[0208] Fig.33 The composite structure HB2 is similar to the third embodiment. Fig.32 Same cross-section view. Fig.34 Observe along the arrow direction in the GG section Fig.33 A diagram of the state of the composition.

[0209] In this embodiment, a preform is formed by arranging two first laminates LM1 having a common shape at a distance in the second laminate LM2, inserting a rod TB into the preform, and further using two sets of Fig.28 The same mold is subjected to the main heating step, thereby forming a composite structure HB2 composed of the structure (irregular cross-sectional structure) ST11 with an irregular cross section and the rod TB. The composite structure HB2 is sealed from the outside and has two independent spaces SP.

[0210] It should be noted that when the inner periphery of the first laminate LM1 is brought into close contact with the outer periphery of the hollow rod TB, the pressing force in the mold clamping direction is increased, so that Fig.34 As shown in the figure, the cross section of the rod TB can also be deformed into an elliptical shape. The cross sections of both ends of the composite structure HB2 are also the same. However, since no radial external pressure is applied to the rod TB on the inner side of the second stack LM2, the cross section of the rod TB remains circular. The cross-sectional shape of the rod TB is not limited to a circle, and can be made into a hexagonal, octagonal or other cross-sectional shape. In addition, a rod having a cross section that has been partially deformed in advance can also be used to form the composite structure HB2.

[0211] Fig.35 The composite structure HB3 is similar to the third embodiment. Fig.30 Same stereogram. Fig.36 Observed along the arrow direction in the HH section Fig.35 The composite structure HB3 of this modification example uses Fig.15 The forming die shown is used instead Fig.28 The forming die shown can obtain a composite structure HB3 composed of a structure with an irregular cross-sectional shape (irregular cross-sectional structure) ST12 and a rod TB.

[0212] More specifically, similarly to the third embodiment, a hollow rod TB having a lengthwise dimension substantially equal to that of the second stack LM2 and made of fiber reinforced plastic such as CFRP, resin, or metal is inserted into the second stack LM2 and the first stack LM1, and then, Fig.15 By applying pressure to the forming die shown, a composite structure HB3 can be obtained in which the end ED of the first laminate LM1 and the end of the rod TB are flattened. Fig.30 The embodiments shown are identical.

[0213] In this modification, a sealed space SP is formed between the first stacked body LM1 and the rod TB, and another space SPX is formed inside the rod TB whose ends are flattened. The space SP and the space SPX are not connected to each other, so different gases or liquids can be sealed in each. The composite structure HB3 can be used as a reinforcing material by inserting bolts or the like through the through hole formed at the end ED to connect with other members.

[0214] Fig.37 is a composite structure similar to the third embodiment. Fig.32 Same cross-sectional view. The composite structure HB4 of this modified example is composed of a structure with an irregular cross-sectional shape (irregular cross-sectional structure) ST13 and a rod TB. The hollow rod TB is inserted in a state where it is only in close contact with one end ED of the second stack LM2 protruding outward in the length direction of the first stack LM1. In addition, the other end ED of the second stack LM2 protruding outward in the length direction of the first stack LM1 is in an open and closed shape without the rod TB inserted. The portions near the two ends of the second stack LM2 protruding outward in the length direction of the first stack LM1 are in contact with the space SP. For common structures, repeated descriptions are omitted.

[0215] According to this modification, the space SP can be used as a normal pressure or pressurized tank for liquid, gas, etc. In general, the piping connected to the tank is mostly connected to a valve, etc. In this modification, a bolt can be formed on the rod TB protruding from the end ED, and directly connected to a valve, etc., which is not shown in the figure, and liquid and gas can be stored in the central part CT. With this structure, liquid and gas can be moved between the central part CT and the outside with the help of a valve. In addition, the rod TB can be connected to other piping with the help of a joint.

[0216] Industrial Applicability

[0217] The structure of the present invention is used to promote research in walking boosters and nursing boosters. When used in frame components of power suits that are already partially practical, the characteristics of CFRP materials (lightweight, high strength, and high rigidity) and the irregular cross-section / polygonal structure can be effectively utilized. Furthermore, by using the structure of the present invention in vehicles such as motorcycles and automobiles, it is possible to achieve lightweight while ensuring strength, which can help improve fuel consumption. In particular, the composite structure composed of rods and structures has light weight and high strength, and also has toughness due to the material of the rods. Therefore, in addition to frames for walking / nursing boosters and structures for motorcycles / automobiles, it has a wide range of applicability and can contribute to the development of a wide range of industries.

[0218] Description of Reference Numerals

[0219] PS1~PS6、PS11~PS17 prepreg sheets

[0220] MD Mandrel

[0221] CY cylindrical core material

[0222] TP Strip

[0223] OV Oven

[0224] RD Rotary drive

[0225] UD upper die

[0226] LD lower die

[0227] LM1 First stack

[0228] LM2 Second stack

[0229] ST1~ST13 Structure

[0230] TB Rods

[0231] HB1~HB4 composite structure

Claims

1. A method for manufacturing a structure, comprising the following steps: A plurality of first composite materials including first reinforcing fibers and uncured first thermosetting resin are wound around a core rod to form a cylindrical inner laminate. applying pressure around the inner laminate, The inner laminate is heated until the first thermosetting resin is completely cured, thereby forming a cylindrical core material. A winding step of winding a plurality of sheets of a second composite material including a second reinforcing fiber and an uncured second thermosetting resin around the cylindrical core material to form a cylindrical outer laminate; A pressing step of winding a strip or a film around the outer periphery of the outer laminate and applying pressure; A preheating step of heating the outer laminate to cure the second thermosetting resin before the second thermosetting resin is completely cured, that is, when the degree of cure of the second thermosetting resin is in the range of 30% to 90%; an extraction step of extracting the core rod from the outer laminate and the cylindrical core material; and The main heating step comprises placing the outer laminated body wound with the strip or film and the cylindrical core material in a forming mold, heating the outer laminated body until the second thermosetting resin is completely cured, and applying pressure, thereby deforming the outer laminated body into a non-circular cross-sectional shape. forming a structure in which the cylindrical core material and the outer laminated body are integrated, The outer stack is formed so as to protrude outward from the inner stack in the longitudinal direction, and in the main heating step, the deformation amount of the end side of the outer stack is different from the deformation amount of the center side of the inner stack. The composite material is a prepreg in which the reinforcing fibers are impregnated with the thermosetting resin, and in each prepreg sheet, the reinforcing fibers are oriented with regularity.

2. The method for manufacturing a structure according to claim 1, wherein: After the main heating step, the cylindrical core material and the outer laminate are removed from the forming die, and the tape or film is peeled off.

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