Frame structure, flying object, and method for producing frame structure

Abstract

The present invention addresses the problem of forming a frame structure in which a cylindrical body or a columnar body of a thermosetting resin and a metal member are joined in a stable joined state.　The present invention is a frame structure comprising a resin-metal joined body having a resin member (a) substantially comprising a fiber-reinforced thermosetting resin and a metal member (b). A cylindrical part or a columnar part of the resin member (a) is fitted to the inner periphery of the metal member (b), or a cylindrical part or a columnar part of the metal member (b) is fitted to the inner periphery of the resin member (a). In the fitting part, the outer cross section of the inner member to be fitted and the inner cross section of the outer member to fit have similar shapes; and the outer dimension D of the inner member and the inner dimension d of the outer member satisfy D > d.

Description

Frame structure, flying object, and method for manufacturing the frame structure

[0001] The present invention relates to a resin-metal joint having a resin member having a tubular or columnar portion essentially made of a fiber-reinforced thermosetting resin, and a metal member joined to the outer circumference of the tubular or columnar portion, and a method for manufacturing the same.

[0002] Fiber-reinforced composite materials, which use thermosetting resins as the matrix resin, are widely used in components for aircraft, automobiles, and industrial equipment due to their excellent mechanical properties and lightweight nature. In such applications, frame structures with tubular or columnar fiber-reinforced composite materials as the main framework are sometimes employed.

[0003] When forming a frame structure, it is necessary to connect other components to a tubular or columnar fiber-reinforced composite material, but such components often have relatively complex shapes. Therefore, it was common practice to manufacture the components separately using injection molding or metalworking, and then join them to the fiber-reinforced composite material using adhesives or bolts.

[0004] For example, Patent Document 1 discloses a method of mechanically joining pipes made of fiber-reinforced resin by bolting the joints. Patent Document 2 discloses a structure in which pipes made of carbon fiber-reinforced resin and metal parts are joined with an adhesive.

[0005] Japanese Patent Publication No. 11-350592 Japanese Patent Publication No. 2016-221784

[0006] However, the method described in Patent Document 1 raises concerns about reduced strength due to bolting the pipe, as well as the added weight caused by the bolts themselves. Furthermore, while the method described in Patent Document 2 can improve void-free formation within the adhesive and strengthen the joint, it requires the creation of tapered shapes or surface irregularities on the bonding surface, which reduces productivity.

[0007] The present invention aims to form a resin-metal joint in which a tubular or columnar body of thermosetting resin and a metal member are joined together, in a stable bonded state.

[0008] The present invention and its preferred embodiments for solving the above-mentioned problems have the following configuration: [1] A frame structure made of a resin-metal joint having a resin member (a) substantially made of fiber-reinforced thermosetting resin and a metal member (b), wherein a cylindrical or columnar portion of the resin member (a) is fitted to the inner circumference of the metal member (b), or a cylindrical or columnar portion of the metal member (b) is fitted to the inner circumference of the resin member (a), and in the fitting portion, the outer cross-section of the inner member to be fitted and the inner cross-section of the outer member to be fitted have similar shapes, and the outer dimension D of the inner member and the inner dimension d of the outer member satisfy D > d.

[0009] [2] The fitting allowance (D-d) / D in the fitting portion is 1.0 × 10 －４ ~5.0 x 10 －２ The frame structure described in [1].

[0010] [3] The frame structure according to [1] or [2], wherein the outer dimension D of the cylindrical or columnar portion of the inner member is 10 to 150 mm.

[0011] [4] The frame structure according to any one of [1] to [3], wherein the length of the fitting portion is 5.0 to 200 mm.

[0012] [5] The frame structure according to any one of [1] to [4], wherein at least one of the inner member or the outer member has a buffer layer made of a thermosetting resin or a thermoplastic resin, and the two members are joined together via the buffer layer.

[0013] [6] The frame structure according to [5], wherein the resin member (a) has a fiber-reinforced thermosetting resin layer and a buffer layer made of a thermosetting resin or thermoplastic resin, and the two members are joined together via the buffer layer.

[0014] [7] The ratio t / d of the thickness t of the buffer layer to the inner dimension d of the outer member is 1.0 × 10 －３ ~5.0 x 10 －２ A frame structure as described in [5] or [6], which is within the range of [5].

[0015] [8] The frame structure according to any one of [5] to [7], wherein the buffer layer is made of a thermoplastic resin.

[0016] [9] The frame structure according to [8], wherein the melting point of the thermoplastic resin is 100 to 300°C.

[0017]

[10] The frame structure according to any one of [5] to [9], wherein the buffer layer has a Shore A hardness of 5 or more and 90 or less, or a Young's modulus of 0.1 MPa or more and 4000 MPa or less.

[0018]

[11] The frame structure according to any one of [5] to

[10] , wherein the buffer layer is a polymer coating layer formed on the mating surface or a resin molded body interposed in the mating portion.

[0019]

[12] A frame structure according to any one of [5] to

[11] wherein the buffer layer comprises silicone rubber, fluororubber, thermoplastic polyurethane, thermoplastic elastomer, natural rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, polypropylene resin, polyethylene resin, nylon resin, polycarbonate resin, polyimide resin, polyvinyl chloride, polystyrene resin, polymethyl methacrylate, polyurethane foam, polyethylene foam, elastomer foam, or epoxy resin, or a mixture thereof, or a coating of a polymer coating, ceramic coating, metal oxide coating, glassy coating, or carbon-based coating, or a mixture thereof.

[0020]

[13] The frame structure according to any one of [5] to

[12] , wherein the coefficient of friction at the interface between the mating surface of the metal member (b) and the buffer layer is 0.3 or more.

[0021]

[14] The frame structure according to any one of [1] to

[13] , wherein the surface roughness Ra of the fitting surface of the metal member (b) is 1.0 μm or more and 50.0 μm or less.

[0022]

[15] The frame structure according to any one of [1] to

[14] , wherein the concentricity between the outer cross-section of the inner member and the inner cross-section of the outer member in the fitting portion is 1.0 mm or less.

[0023]

[16] The number of cracks per unit area on the surface of the resin member (a) is 3 / cm ２ A frame structure described in any of the following [1] to

[15] .

[0024]

[17] The frame structure according to any one of [1] to

[16] , wherein the outer member is a joint or a base.

[0025]

[18] A flying object comprising a frame structure as described in any of [1] to

[17] .

[0026]

[19] A method for manufacturing a frame structure by fitting together a resin member (a) substantially made of fiber-reinforced thermosetting resin and a metal member (b), wherein one of the resin member (a) and the metal member (b) has a cylindrical or columnar portion and the other has an opening, the outer dimension D of the cylindrical or columnar portion and the inner dimension d of the opening satisfy the relationship D > d at room temperature, the cylindrical or columnar portion and the opening have similar cross-sectional shapes, the manufacturing method comprising: a step of changing the dimensions of the metal member (b) by heating or cooling; a step of inserting the cylindrical or columnar portion into the opening in a state where it has become insertable due to the dimensional change; and a step of returning the temperature to room temperature so that a tightening allowance is created between the two members and the fitting is completed.

[0027]

[20] The method for manufacturing a frame structure according to

[19] , wherein the resin member (a) has the cylindrical or columnar portion, the metal member (b) has the opening, the step of changing the dimensions of the metal member (b) by heating is the step of heating and expanding the metal member (b), and the step of returning the temperature to room temperature is the step of cooling and shrinking the metal member (b).

[0028]

[21] The method for manufacturing a frame structure according to

[19] , wherein the metal member (b) has the cylindrical or columnar portion, the resin member (a) has the opening, the step of changing the dimensions of the metal member (b) by cooling is the step of cooling and shrinking the metal member (b), and the step of returning the temperature to room temperature is the step of expanding the metal member (b) by heating.

[0029]

[22] A method for manufacturing a frame structure according to any one of

[19] to

[21] , wherein a buffer layer made of a thermosetting resin or thermoplastic resin is formed in advance on at least one of the outer surface of the cylindrical portion or columnar portion, or the inner surface of the opening, and the two members are fitted together after the outer dimension D and the inner dimension d are filled with the buffer layer.

[0030] According to the present invention, a frame structure made of a resin-metal joint, which integrates a resin member made substantially of fiber-reinforced thermosetting resin with a metal member, can be manufactured in a stable bonded state without forming cracks on the surface of the resin member.

[0031] This is a schematic diagram showing an example of a joint as a metal member (b). This is a schematic diagram showing an example of a resin-metal joint in which the joint shown in Figure 1 is joined to a resin member (a). This is a schematic diagram showing an example of a base as a metal member (b). This is a schematic diagram showing an example of a resin-metal joint in which the base shown in Figure 3 is joined to a resin member (a). This is a schematic diagram showing an example of a second cylindrical body as a metal member (b). This is a schematic diagram showing an example of a resin-metal joint in which the second cylindrical body shown in Figure 5 is joined to a resin member (a). This is a cross-sectional view showing an example of a joint in a resin-metal joint in which a resin member (a) and a metal member (b) are joined. This is a schematic diagram showing an example of a resin-metal joint in which a resin member (a) and a metal member (b) are joined via a buffer layer. This is a cross-sectional view showing an example of a joint in a resin-metal joint in which a resin member (a) and a metal member (b) are joined via a buffer layer.

[0032] The frame structure according to the present invention comprises a resin-metal joint having a resin member (a) substantially made of fiber-reinforced thermosetting resin and a metal member (b). In this specification, "substantially made of a certain material" means that the material is contained as the main component and is typically composed only of that material, but other components may be included as long as the effects of the invention are not lost. For example, as will be described later, the resin member (a) may have a thermoplastic resin area on its surface, but if the majority is made of fiber-reinforced thermosetting resin, it will be considered to be substantially made of fiber-reinforced thermosetting resin. Preferably, for example, 90% or more of the volume of the resin member (a) is made of fiber-reinforced thermosetting resin. Furthermore, even if the resin member (a) or metal member (b) to be joined are themselves integrated with a member made of another material, if the joint is formed of resin, it will be considered the resin member (a), and if it is formed of metal, it will be considered the metal member (b).

[0033] The type of thermosetting resin constituting the resin member (a) is not particularly limited, and examples include unsaturated polyester resin, vinyl ester resin, epoxy resin, phenol (resol type) resin, urea-melamine resin, polyimide resin, copolymers and modified versions thereof, and resins blended with at least two of these. Among these, thermosetting resins mainly composed of epoxy resin are preferred because they have excellent rigidity and strength. The main component of the thermosetting resin refers to the component whose ratio in the resin composition constituting the resin member (a) is 60% by mass or more.

[0034] The fibers contained in the fiber-reinforced thermosetting resin of the resin member (a) can be general reinforcing fibers and are not particularly limited. Examples include glass fibers, polyacrylonitrile, rayon, lignin, and pitch-based carbon fibers (including graphite fibers), potassium titanate whiskers, zinc oxide whiskers, calcium carbonate whiskers, wollastonite whiskers, aluminum borate whiskers, aramid fibers, alumina fibers, silicon carbide fibers, ceramic fibers, asbestos fibers (no longer used), gypsum fibers, and metal fibers. Among these, glass fibers, polyacrylonitrile, and pitch-based carbon fibers are preferred, with polyacrylonitrile and pitch-based carbon fibers being more preferred from the viewpoint of lightness and mechanical properties, and polyacrylonitrile-based carbon fibers being particularly preferred.

[0035] From the viewpoint of improving mechanical properties, it is preferable that the fibers contained in the resin member (a) are surface-treated with a sizing agent. Examples of the sizing agent include polyfunctional epoxy resins, acrylic acid polymers, polyhydric alcohols, and polyethyleneimines. Specifically, examples include polyglycidyl ethers of aliphatic polyhydric alcohols such as glycerol triglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, arabitol polyglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol polyglycidyl ether; polyacrylic acid; copolymers of acrylic acid and methacrylic acid; copolymers of acrylic acid and maleic acid; or mixtures of two or more of these; polyvinyl alcohol; glycerol; diglycerol; polyglycerol; sorbitol; arabitol; trimethylolpropane; pentaerythritol; and polyethyleneimines that contain a large number of amino groups in one molecule, which can be expected to provide high adhesion to fibers. Among these, glycerol triglycidyl ether, diglycerol polyglycidyl ether, and polyglycerol polyglycidyl ether are preferred in the present invention because they contain a large number of highly reactive epoxy groups in a single molecule, have high water solubility, and are easy to apply to fibers.

[0036] It is preferable that the sizing agent is contained in an amount of 0.01 to 5 parts by mass, more preferably 0.1 to 2 parts by mass, per 100 parts by mass of the fiber.

[0037] The fiber contained in the resin member (a) is preferably a continuous fiber. Here, the continuous fiber in the present invention means a fiber having a length of 10 mm or more. As long as it has this length, it does not necessarily have to be continuous throughout the entire member and may be interrupted halfway. Examples of the form of the continuous fiber include a woven fabric in which a fiber bundle is woven, a form in which filaments, blades, filament bundles, spun yarns, etc. are aligned in one direction. Further, according to a general molding method of fiber-reinforced thermosetting resin, the resin member (a) can also be formed by using two or more of these fiber forms in combination.

[0038] Among them, the resin member (a) is preferably a molded body having a laminated structure formed by laminating prepreg sheets made of fiber-reinforced thermosetting resin. When the prepreg sheet is in a form in which the fibers are aligned in one direction, it is preferable to have a configuration in which the prepreg sheets are isotropically laminated so that the fiber angles are approximately 0°, approximately ±45°, approximately 90°, etc. A layer configuration with an angle other than the above may also be included.

[0039] The mass content rate of the fiber present in 100% by mass of the resin member (a) is preferably 20 to 70% by mass, more preferably 25 to 70% by mass, and particularly preferably 30 to 65% by mass. By setting the mass content rate of the fiber within the above range, a resin member (a) with high rigidity and good dimensional accuracy can be obtained.

[0040] The fiber-reinforced thermosetting resin may contain other fillers and additives according to the application and the like. Examples of such fillers and additives include elastomers, rubber components, inorganic fillers, flame retardants, conductivity-imparting agents, antibacterial agents, insect repellents, deodorants, anti-coloring agents, mold release agents, antistatic agents, plasticizers, coloring agents, pigments, dyes, foaming agents, foam suppressants, coupling agents, and the like.

[0041] In the present invention, the resin member (a) or the metal member (b) is a member having at least a cylindrical or columnar portion. Columnar means a solid shape in which there is no hollow space in the cylindrical portion. Typically, such as when forming the main skeleton of the aforementioned frame structure, the overall shape can be columnar or cylindrical. Alternatively, it may have a form that combines a cylindrical or columnar portion with other shaped portions. In either case, the cylindrical or columnar portion may be curved. Furthermore, if it has a cylindrical portion, the thickness of the cylindrical portion may vary depending on the location.

[0042] When the resin member (a) has a cylindrical portion, it is preferable for the cylindrical portion to have a shape in which the length in the direction perpendicular to the opening surface is longer than the diameter of the cylindrical shape, i.e., a tubular shape, for forming a frame structure. It is a preferred embodiment of the present invention that at least one of the members is a cylindrical body that is cylindrical as a whole, and it is a particularly preferred embodiment of the present invention from the viewpoint of application to a frame structure that the member as a whole is tubular, i.e., a pipe-shaped member.

[0043] There are no particular restrictions on the radial cross-section of the cylindrical or columnar portion of such resin member (a), however, if the resin member (a) is an inner member, it is preferable that the radial outer cross-section (hereinafter simply referred to as the "outer cross-section") is circular or rectangular, and if the resin member (a) is an outer member, it is preferable that the radial inner cross-section (hereinafter simply referred to as the "inner cross-section") is circular or rectangular.

[0044] In this invention, the member that is positioned on the inside and fitted to the mating portion is referred to as the "inner member," and the member that is positioned on the outside and fitted to the mating portion is referred to as the "outer member," depending on the radial positional relationship at the mating portion. The outer dimension D of the inner member and the inner dimension d of the outer member satisfy the relationship D > d at room temperature, thereby forming an interlocking fit. The frame structure of this invention can be separated again into the outer member and the inner member by heating or cooling, so it is possible to measure the inner dimension d of the outer member and the outer dimension D of the inner member after separation. The inner member and the outer member may be made of either a resin member (a) or a metal member (b).

[0045] Furthermore, the cross-sectional area of ​​the outer cross-section of the cylindrical or columnar part of the resin member (a) is 20 mm².２ Above 300 mm ２ Below is preferable, more preferably 50 mm ２ Above 200 mm ２ Below. When the cross-sectional area of the outer cross-section of the resin member (a) is within this range, a highly rigid resin / metal bonded body can be obtained with good productivity.

[0046] In the present invention, the outer dimension D of the cylindrical portion or columnar portion of the inner member is defined as the distance between the two farthest points of the outer cross-section of the cylindrical portion or columnar portion in the normal temperature environment (25 °C) of the inner member alone. For example, when the outer shape of the cross-section is a perfect circle, the diameter is the outer dimension D, when it is an ellipse, the major axis is the outer dimension D, and when it is a rectangle, the length of the diagonal line is the outer dimension D.

[0047] In the present invention, the outer dimension D of the cylindrical portion or columnar portion of the inner member is preferably in the range of 10 to 150 mm. By using a member having an outer dimension within the above range, a resin / metal bonded body that is resistant to compression from the radial direction can be obtained with good productivity. The outer dimension D of the cylindrical portion or columnar portion of the inner member is more preferably 20 to 100 mm, and even more preferably 25 to 50 mm.

[0048] In the present invention, the length of the joint portion is preferably in the range of (此处原文有误,推测应该是5.0~200mm,按照正确内容翻译)5.0 to 200 mm, more preferably 20 to 150 mm, and even more preferably 50 to 100 mm. By setting the length of the joint portion to 200 mm or less, more preferably 150 mm or less, and even more preferably 100 mm or less, the handling during the joining of the resin member (a) and the metal member (b) becomes simple. On the other hand, by setting the length of the joint portion to 5.0 mm or more, more preferably 20 mm or more, and even more preferably 50 mm or more, when a load is applied to the joint portion, the influence of the out-of-plane direction force on the joint portion becomes small, and as a result, sufficient joint strength can be obtained.

[0049] Since residual stress is generated when the resin member (a) and the metal member (b) are fitted together, it is preferable to provide a function to buffer the stress between the resin member (a) and the metal member (b) at the mating portion. In a more preferable embodiment, it is preferable to provide a layered buffer layer made of a thermosetting resin or thermoplastic resin on at least one of the resin member (a) or the metal member (b). From the viewpoint of adhesion, it is more preferable that it is arranged on the mating surface of the resin member (a). In such a case, the buffer layer is also considered to be part of the resin member (a) or the metal member (b). That is, the outer dimension D and the inner dimension d are dimensions including the buffer layer if a buffer layer is present. Such a buffer layer is typically provided integrally on the surface of the resin member (a) or the metal member (b), and its thickness is usually 1 to 300 μm, preferably 50 to 150 μm. It is preferable that the buffer layer is provided so as to cover the entire surface of the mating surface over the entire joint, but it is not necessarily required to cover the entire surface, and it may be provided in a spot, mesh, or grid pattern. This embodiment, among others, will be referred to as a "buffer layer" in this specification. By providing a buffer layer, residual stress during integration can be suppressed, and the overall strength of the metal-resin joint can be improved.

[0050] The ratio of the thickness t of the buffer layer to the inner dimension d in the fitting portion of a member provided with a buffer layer (= t / d) is 1.0 × 10 －４ ~5.0 x 10 －２ It is preferable that the value be within this range. By keeping it below the upper limit, sufficient shear strength can be achieved while maintaining structural stability, and by keeping it above the lower limit, stress relaxation sufficient to prevent crack formation in each member can be achieved while ensuring adhesion.

[0051] In the present invention, it is preferable that the buffer layer is made of a resin having a Shore A hardness of 5 to 90, or a Young's modulus of 0.1 MPa to 4000 MPa. By keeping it below the upper limit, stress during fitting can be concentrated in the buffer layer, suppressing crack formation in the resin member (a) and the metal member (b). By keeping it above the lower limit, it becomes easier to avoid unintended deformation of the buffer layer, and as a result, it becomes possible to ensure the structural stability of the frame structure.

[0052] When forming the buffer layer with a thermosetting resin, it is preferable to use a thermosetting resin with a minimum viscosity in the range of 10 to 500 Pa·s. A minimum viscosity above the lower limit ensures good handling, while a minimum viscosity below the upper limit allows the thermosetting resin to flow sufficiently, resulting in good bonding strength. The minimum viscosity is more preferably 20 to 300 Pa·s, and even more preferably 40 to 200 Pa·s. As such a thermosetting resin, it is preferable to use at least one selected from the group consisting of epoxy resin, phenolic resin, benzoxazine resin, unsaturated polyester resin, and silicone rubber, fluororubber, natural rubber, styrene-butadiene rubber, nitrile rubber, and ethylene propylene rubber.

[0053] When the buffer layer is formed from a thermoplastic resin, there are no particular restrictions on the thermoplastic resin, and examples include polyolefin resins such as polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyester resins such as liquid crystal polyester, thermoplastic elastomers, polycaproamide (nylon 6), polyhexamethylene adipamide (nylon 66), polypentamethylene adipamide (nylon 56), polyhexamethylene sebaamide (nylon 610), and polyhexamethylene Dodecamido (Nylon 612), Polyundecaneamide (Nylon 11), Polydodecaneamide (Nylon 12), Polycaproamide / Polyhexamethylene adipamide copolymer (Nylon 6 / 66), Polycaproamide / Polyhexamethylene terephthalamide copolymer (Nylon 6 / 6T), Polyhexamethylene adipamide / Polyhexamethylene terephthalamide copolymer (Nylon 66 / 6T), Polyhexamethylene adipamide / Polyhexamethylene isophthalamide copolymer (Nylon 66 / 6I), Polyhexamethylene adipamide / Polyhex Smethylene isophthalamide / caproamide copolymer (nylon 66 / 6I / 6), polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 6T / 6I), polyhexamethylene terephthalamide / polydodecaneamide copolymer (nylon 6T / 12), polyhexamethylene adipamide / polyhexamethylene terephthalamide / polyhexamethylene isophthalamide copolymer (nylon 66 / 6T / 6I), polyhexamethylene terephthalamide / poly-2-methylpentamethylene terephthalamide copolymer Polyamide resins such as M (nylon 6T / M5T), polynonamethylene terephthalamide (nylon 9T), polycarbonate resins, polyphenylene sulfide (PPS) resins, polyacetal resins or polyoxymethylene resins, polyimide (PI) resins, polyamideimide (PAI) resins, polyetherimide resins, polysulfone resins, polyetherketone (PEK) resins, polyetheretherketone (PEEK) resins, polyetherketoneketone (PEKK) resins, polytetrafluoroethylene resins, polyarylate (PAR) resins, andExamples include resins that are blends of at least two of these types.

[0054] In particular, it is preferable to use a thermoplastic resin with a melting point in the range of 100 to 300°C for the buffer layer. A melting point above the lower limit prevents the thermoplastic resin from melting and separating with minimal heating, thus improving the reliability of the bond. Furthermore, a melting point below the upper limit allows for sufficient bonding strength to be achieved while suppressing the heating temperature, thus improving productivity. The melting point of the thermoplastic resin in the buffer layer is more preferably 125 to 275°C, and even more preferably 150 to 250°C. Suitable thermoplastic resins include polyolefin resins, polyester resins, polyamide resins, polycarbonate resins, polyphenylene sulfide resins, polyimide resins, polyamide-imide resins, polyetherimide resins, polyetherketone resins, polyetheretherketone resins, polyetherketone ketone resins, and polyarylate resins.

[0055] Constructing the buffer layer from a thermoplastic resin is a particularly preferred embodiment for the following reasons: Thermoplastic resins reversibly soften upon heating, making them responsive to dimensional changes during mating. Furthermore, thermoplastic resins have higher plastic deformability compared to thermosetting resins, effectively relieving residual stresses generated by mating. In addition, because they are easily supplied in film form, the thickness of the buffer layer can be precisely controlled, resulting in a resin-metal joint of stable quality. Moreover, since a curing reaction like that required for thermosetting resins is unnecessary, manufacturing conditions can be easily controlled, and variations between batches can be suppressed. Due to these characteristics, a buffer layer made of thermoplastic resin realizes a mating structure that combines high reliability and practicality.

[0056] When a buffer layer is present on the outer surface of the cylindrical or columnar portion of the resin member (a), high bonding strength can be obtained if the interface between the thermosetting resin of the resin member (a) and the buffer layer forms an uneven shape. Here, the interface forming an uneven shape means that the interface between the thermosetting resin and the buffer layer is not flat, but rather forms an interface in which a combination of recessed shapes on the thermosetting resin side and recessed shapes on the buffer layer side coexist. In this case, the depth of the recess is preferably 1 to 200 μm, and more preferably 10 to 100 μm.

[0057] In the present invention, the method for manufacturing the resin member (a) is not particularly limited. When the resin member (a) is a tubular body, possible manufacturing methods include a method in which a prepreg, made by aligning fibers impregnated with a thermosetting resin using a filament winding method or a sheet winding method, is wound onto a mandrel while applying a predetermined tension to form it, and then cured; or a method in which it is formed by internal pressure molding using a shaping mold, or by press molding, and then cured.

[0058] As a method for forming a buffer layer of thermoplastic resin on at least a portion of the outer surface of the cylindrical or columnar part of the resin member (a), one method is to wrap at least one layer of film made of thermoplastic resin around it at the beginning or end of the above method, and then integrate it with the thermosetting resin and cure it.

[0059] The metal component (b) in this invention is a component made substantially of metal. There are no particular restrictions on the metal, and examples include aluminum, copper, nickel, tin, gold, silver, iron, magnesium, chromium, tungsten, zinc, lead, and alloys thereof. Furthermore, the metal component (b) may be composed of one type of metal or a combination of two or more types of metals. Among these, aluminum alloys and titanium alloys with high specific strength are preferred, and aluminum alloys are most preferred.

[0060] When forming a frame structure, after fitting with the metal member (b), the number of cracks on the surface of the resin member (a) is 3 (cracks / cm²) per unit area. ２It is preferable that the number of cracks is 0 or less. As a method for checking for cracks, a laser microscope (VHX-7000: manufactured by Keyence Corporation) is used to magnify 200 times, and images are taken of 10 locations where the fields of view do not overlap. The number of cracks in each image is then counted to confirm the cracks. More preferably, the number of cracks is 0 (cracks / cm²). ２ )

[0061] When forming a frame structure, the metal member (b) is preferably either a joint or a base. A joint is a member used to connect two cylindrical or columnar parts, change their direction, connect cylindrical or columnar parts of different diameters, or merge or branch three or more cylindrical or columnar parts. A base is a member used to support and hold a cylindrical or columnar part. In a frame structure, which is one aspect of the present invention, at least one of these cylindrical or columnar parts is a resin member (a) having the aforementioned cylindrical or columnar part, and in a preferred embodiment, all of them are the aforementioned cylindrical or columnar parts. Figures 1A to D show typical joints, Figures 2A to D show resin-metal joints in which a resin member (a) (cylindrical body) and a joint are joined, Figures 3A to B show typical bases, and Figures 4A to B show schematic diagrams of resin-metal joints in which a resin member (a) (cylindrical body) and a base are joined. However, these figures do not limit the present invention in any way.

[0062] The metal member (b) may be a cylindrical member. Typically, a cylindrical member is a cylindrical body that differs in length, diameter, thickness, etc. from the cylindrical or columnar portion of the resin member (a). Figure 5 shows a typical cylindrical member 2, and Figure 6 is a schematic diagram of a resin-metal joint in which a cylindrical resin member (a) 1 and a cylindrical metal member (b) 2 are joined.

[0063] The metal member (b) preferably has a surface roughness (Ra) of 1.0 μm or more and 50.0 μm or less on the mating surface. By setting the surface roughness to be above the lower limit of the above range, it is possible to ensure sufficient bonding strength between the metal member (b) and the resin member (a), and by setting it to be below the upper limit of the above range, improved workability during mating can be expected. In order to achieve the above surface roughness, the metal member (b) may be surface-treated on at least a part of its surface. Examples of surface treatment methods include roughening treatment, easy bonding treatment, antistatic treatment, sandblasting treatment (sand mat treatment), corona discharge treatment, plasma treatment, excimer treatment, chemical etching treatment, water mat treatment, flame treatment, acid treatment, alkali treatment, oxidation treatment, ultraviolet irradiation treatment, silane coupling agent treatment, etc.

[0064] The static friction coefficient at the interface between the metal member (b) and the buffer layer at the mating surface is preferably 0.3 or higher. The static friction coefficient can be measured according to JIS K7125 by preparing a thin-walled plate with the same configuration as the resin member (a) and the metal member (b). By making the static friction coefficient 0.3 or higher, it is possible to ensure sufficient shear strength, and an improvement in the overall strength of the frame structure can be expected.

[0065] The radial cross-sectional shape of the metal member (b) at the fitting portion with the cylindrical or columnar portion of the resin member (a) is similar in shape to the cross-sectional shape of the cylindrical or columnar portion of the resin member (a) at the joint. When the metal member (b) is the outer member and the resin member (a) is the inner member, the radial inner cross-sectional shape of the metal member (b) and the radial outer cross-sectional shape of the resin member (a) are similar in shape. On the other hand, when the metal member (b) is the inner member and the resin member (a) is the outer member, the radial outer cross-sectional shape of the metal member (b) and the radial outer cross-sectional shape of the resin member (a) are similar in shape. At the same time, the resin member (a) and the metal member (b) are fitted together such that the outer dimension D of the cylindrical or columnar portion of the inner member and the inner dimension d of the outer member satisfy D > d. Here, the inner dimension d of the outer member is defined as the distance between the two furthest points on the inner cross-section of the outer member alone at room temperature (25°C). For example, if the inner cross-section of the outer member is a perfect circle, the diameter is the inner dimension d; if it is an ellipse, the major axis is the inner dimension d; and if it is a rectangle, the diagonal is the inner dimension d. By making the outer cross-section of the inner member and the inner cross-section of the outer member similar, the pressure from the outer member to the inner member can be made uniform, preventing the outer member and its failure due to stress concentration. Furthermore, by setting d to be greater than D, pressure is generated from the outer member to the inner member when they are fitted together, improving the joint strength.

[0066] The fitting allowance ΔD / D (= (D - d) / D) at the joint between the outer and inner members is 1.0 × 10 －４ ~5.0 x 10 －２ It is preferable to design it in this way. By designing the fit allowance to be above the lower limit, the outer member can be sufficiently tightly fitted to the inner member, improving the joint strength. On the other hand, by designing the fit allowance to be below the upper limit, crack formation in the outer and inner members due to excessive pressure can be suppressed. Since the frame structure of the present invention can be separated again into the outer and inner members by heating or cooling, it is possible to measure the inner dimensions of the outer member and the outer dimensions of the inner member after separation and calculate the fit allowance.

[0067] At the joint, the concentricity, which indicates the misalignment between the outer cross-section of the inner member and the inner cross-section of the outer member, is preferably 1.0 mm or less. The center of the cross-section of each member is the center if the cross-sectional shape is a circle or ellipse, and the geometric center if it is a polygon. The concentricity can be measured by comparing the geometric center positions of each member using a CNC three-dimensional measuring machine.

[0068] Figure 9 is a schematic cross-sectional view of an embodiment in which a metal member (b), which is a joint 2, is joined to the outer circumferential surface of a resin member (a) 1 via a buffer layer. In this embodiment, a buffer layer 4 is formed around the entire outer circumferential surface of the resin member (a) 1. The inner circumferential surface of the cylindrical metal member (b) 2 is joined to the resin member (a) 1 via the buffer layer 4, surrounding it around its entire circumference.

[0069] The metal member (b) may be fitted to the resin member (a) by contacting only a portion of its outer or inner circumferential surface, rather than the entire circumference. However, to increase the bonding strength, it is preferable that the metal member (b) is in contact with the circumferential portion of the cylindrical or columnar part of the resin member (a) over a range of 50% or more, and particularly preferable that it is in contact with 100% (the entire circumference).

[0070] The present invention relates to a method for manufacturing a frame structure, which involves fitting together a resin member (a) made substantially of fiber-reinforced thermosetting resin with a metal member (b). Details of the materials used in the method for manufacturing the frame structure of the present invention, such as the resin member (a), the metal member (b), and the buffer layer, are the same as those described in the description of the frame structure of the present invention.

[0071] In the method for manufacturing a frame structure of the present invention, one of the resin member (a) and the metal member (b) has a cylindrical or columnar portion, and the other has an opening, the outer dimension D of the cylindrical or columnar portion and the inner dimension d of the opening satisfy the relationship D > d at room temperature, and the cylindrical or columnar portion and the opening have similar cross-sectional shapes.

[0072] When the resin member (a) is the inner member, the resin member (a) has the cylindrical or columnar portion, and the metal member (b) has the opening.

[0073] When the metal member (b) is the inner member, the metal member (b) has the cylindrical or columnar portion, and the resin member (a) has the opening.

[0074] In the method for manufacturing the frame structure of the present invention, in both cases where the resin member (a) is the inner member and where the metal member (b) is the inner member, it is preferable that the buffer layer is formed on at least one of the fitting surfaces of the resin member (a) or the metal member (b) as described above. That is, it is preferable to pre-form a buffer layer made of a thermosetting resin or thermoplastic resin on at least one of the outer surface of the cylindrical or columnar portion, or the inner surface of the opening, and then fit the two members together after satisfying the outer dimensions D and inner dimensions d with the buffer layer included.

[0075] There are no particular limitations on the method for forming the buffer layer. Examples include a method in which a buffer layer is provided by polymer coating after preparing a resin member (a) or a metal member (b), or a method in which the resin member (a) or metal member (b) is integrally molded together with the buffer layer.

[0076] The method for manufacturing the frame structure of the present invention includes the steps of: changing the dimensions of the metal member (b) by heating or cooling; inserting the cylindrical or columnar portion into the opening in the state in which insertion is possible due to the dimensional change; and returning the temperature to room temperature so that a tightening margin is created between the two members and the fitting is completed.

[0077] When the resin member (a) becomes the inner member, the metal member (b) is heated and expanded in a step that changes its dimensions by heating. Due to the thermal expansion of the metal member (b), the resin member (a), which has an outer dimension D that is larger than the inner dimension d of the outer metal member (b), can be inserted as the inner member. Then, in the step of returning the temperature to room temperature, the metal member (b) is contracted by cooling. This cooling may be forced cooling or allowed to cool at room temperature. Due to the contraction of the metal member (b), an overlap is created between the two members and the fitting is completed.

[0078] When the metal member (b) is to be the inner member, the metal member (b) is cooled and shrunk by a process of changing its dimensions by cooling. Due to the cooling and shrinkage of the metal member (b), the metal member (b), which has an outer dimension D that is larger than the inner dimension d of the resin member (a), which is the outer member, can be inserted as the inner member. Then, in the process of returning the temperature to room temperature, the metal member (b) is expanded by heating. This heating may be forced heating or it may be a heating process at room temperature. Due to the expansion of the metal member (b), an overlap is created between the two members and the fitting is completed.

[0079] The frame structure of the present invention is suitable for use as a component in forming a frame structure because it firmly joins a lightweight, highly rigid resin component (a) with a metal component (b) that can be connected, joined, branched, and fixed in place. Such a frame structure is used in the bodies and arms of industrial robots, automobiles, motorcycles, bicycles, aircraft, helicopters, drones, ships, submarines, and building materials. In particular, from the viewpoint of rigidity and lightness, the frame structure of the present invention is preferably used as a component for flying objects such as aircraft, helicopters, and drones. That is, the flying object of the present invention includes the frame structure of the present invention.

[0080] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by the description of the examples.

[0081] [Measurement Method] (1) Concentricity The concentricity was measured using a CNC three-dimensional measuring machine (CRYSTA-ApexV9166: manufactured by Mitutoyo Corporation) in the following manner. In the case of a circular cross-section, the coordinates of three equally spaced points (at 120° intervals) on the outer surface of the inner member and three equally spaced points (at 120° intervals) on the inner surface of the outer member were measured. In the case of a polygonal cross-section, the coordinates of the center of each side of the outer surface of the inner member and the center of each side of the inner surface of the outer member were measured. From the obtained coordinates, the geometric center position of each member was calculated using the least squares method, and the distance between the two centers was determined as the concentricity.

[0082] (2) For five samples of the joint strength frame structure, both ends in the longitudinal direction (pipe and aluminum molded body) were fixed with a special jig, and a tensile test was performed using a universal testing machine (5900 series universal testing machine: manufactured by Instron Japan Co., Ltd.).

[0083] (3) Number of cracks The surface of the mating part was magnified 200 times with a laser microscope (VHX-7000: manufactured by Keyence Corporation) and the field of view was 1.5 cm. ２ Ten locations were photographed where the fields of view did not overlap. In each image, the total number of cracks was counted and divided by the field of view to calculate the number of cracks per unit area.

[0084] [Example 1] A polyamide film was obtained by hot-pressing pellets of polyamide 6 / 66 / 610 copolymer (CM4000, manufactured by Toray Industries, Inc., melting point 150°C). Separately, a stainless steel mandrel with a perfectly circular cross-section, an outer diameter of 27.6 mm at the tip, and a length of 1.5 m was subjected to a release treatment. Thermosetting prepreg (Toray Industries, Inc., Torayca® prepreg P3051S-30) was used on the release-treated mandrel, and the layers were laminated at ±45°, 90°, and 0° angles with the longitudinal direction of the mandrel as the 0° axis. Then, the above polyamide film was adjusted to a thickness of 100 μm and wrapped around the mandrel once. Furthermore, wrapping tape (heat-resistant film tape, width 10 mm) was wrapped around the outside with a tension of 3 kg, and heat molding was performed in a curing oven at 150°C for 30 minutes. After this, the mandrel was removed, the wrapping tape was removed, and then it was cut to obtain pipe 1 with an outer diameter of 28.6 mm, a thickness of 0.5 mm, and a length of 500 mm.

[0085] Furthermore, an annular A2000 series aluminum molded body 1 with an inner diameter of 28.3 mm, an outer diameter of 40 mm, and a length of 30 mm was prepared in a room temperature environment.

[0086] With the aluminum molded body 1 heated to 300°C using a far-infrared heater, the pipe 1 was inserted into the aluminum molded body 1, and fitted so that 30 mm from the end of the outer surface of the pipe 1 was in contact with the inner surface of the aluminum molded body 1. The pipe was then fixed in a vise and cooled by being left undisturbed at room temperature for 24 hours to manufacture the frame structure.

[0087] The concentricity of the obtained frame structures was 0.01 mm, and the joint strength was 15 MPa or higher for all five samples. Furthermore, no cracks were observed.

[0088] [Example 2] A stainless steel mandrel with a perfectly circular cross-section, a tip outer diameter of 27.5 mm, and a length of 1.5 m was subjected to a release treatment. Thermosetting prepreg (Toray Industries, Inc., Torayca® Prepreg P3051S-30) was used on the release-treated mandrel, and layers were stacked at ±45°, 90°, and 0° angles with the longitudinal direction of the mandrel as the 0° axis. Then, wrapping tape (heat-resistant film tape, width 10 mm) was wrapped around it with a tension of 3 kg, and heat molding was performed in a curing oven at 150°C for 30 minutes. After this, the mandrel was removed, the wrapping tape was removed, and then it was cut to obtain a pipe 2 with an outer diameter of 28.5 mm, a thickness of 0.5 mm, and a length of 500 mm.

[0089] Next, an annular A2000 series aluminum molded body 2 with an inner diameter of 28.3 mm, an outer diameter of 40 mm, and a length of 30 mm was prepared in a room temperature environment.

[0090] An epoxy adhesive (3M Panel Bond 8115) was applied to the outer surface of pipe 2 up to 30 mm from the end. Then, with the aluminum molded body 2 heated to 250°C using a far-infrared heater, pipe 2 was inserted into the aluminum molded body 2, and the pipe 2 was fitted so that 30 mm from the end of the outer surface of pipe 2 was in contact with the inner surface of the aluminum molded body 2. The pipe 2 was then fixed in a vise and allowed to cool at room temperature for 24 hours to manufacture the frame structure.

[0091] The concentricity of the obtained frame structures was 0.11 mm, and the joint strength was 15 MPa or higher for all five samples. Furthermore, no cracks were observed.

[0092] (Example 3) A stainless steel mandrel with a perfectly circular cross-section, a tip outer diameter of 28.0 mm, and a length of 1.5 m was subjected to a release treatment. Thermosetting prepreg (Toray Industries, Inc., Torayca® Prepreg P3051S-30) was used on the release-treated mandrel, and layers were stacked at ±45°, 90°, and 0° angles with the longitudinal direction of the mandrel as the 0° axis. Then, a polyamide film (thickness 100 μm) similar to that used in Example 1 was wrapped around it once. Furthermore, wrapping tape (heat-resistant film tape, width 10 mm) was wrapped around the outside with a tension of 3 kg, and heat molding was performed in a curing oven at 150°C for 30 minutes. After this, the mandrel was removed, the wrapping tape was removed, and then it was cut to obtain a pipe 3 with an outer diameter of 30.0 mm, a thickness of 1.0 mm, and a length of 500 mm.

[0093] Next, an annular A2000 series aluminum molded body 3 with an inner diameter of 28.0 mm, an outer diameter of 40 mm, and a length of 30 mm was prepared in a room temperature environment.

[0094] Subsequently, with the aluminum molded body 3 heated to 300°C using a far-infrared heater, the pipe 3 was inserted into the aluminum molded body 3, and fitted so that 30 mm from the end of the outer surface of the pipe 3 was in contact with the inner surface of the aluminum molded body 3. The pipe was then fixed in a vise and allowed to cool at room temperature for 24 hours to manufacture the frame structure.

[0095] The concentricity of the obtained frame structures was 0.1 mm, and the joint strength was approximately 13 MPa for all five samples. Furthermore, the bonding strength was 2 strands / cm. ２ A crack was observed. In this embodiment, the fit allowance is 0.0714, which is a configuration that exceeds the range described in [2] of "Means for Solving the Problem".

[0096] [Example 4] The same pipe 2 used in Example 2 was used as the pipe.

[0097] Furthermore, an annular A2000 series aluminum molded body 4 with an inner diameter of 28.6 mm, an outer diameter of 40 mm, and a length of 30 mm was prepared at room temperature. This was subjected to sandblasting to adjust the surface roughness Ra to approximately 30 μm. After washing with pure water and drying at room temperature, a silicone coating agent (KR-400 manufactured by Shin-Etsu Chemical Co., Ltd.) was applied, and the surface was left to stand until the coating film no longer adhered to the finger when pressed, thus preparing an aluminum molded body 4 with an inner diameter of 28.4 mm.

[0098] Subsequently, with the aluminum molded body 4 heated to 300°C using a far-infrared heater, the pipe 2 was inserted into the aluminum molded body 4, and fitted so that 30 mm from the end of the outer surface of the pipe 2 was in contact with the inner surface of the aluminum molded body 4. The pipe 2 was then fixed in a vise and cooled by being left undisturbed at room temperature for 24 hours to manufacture the frame structure.

[0099] The concentricity of the obtained frame structures was 0.13 mm, and the joint strength was 11 MPa or higher for all five samples. Furthermore, no cracks were observed.

[0100] [Example 5] A stainless steel mandrel with a perfectly circular cross-section, an outer diameter of 16.0 mm at the tip, and a length of 1.5 m was subjected to a release treatment. Thermosetting prepreg (Toray Industries, Inc., Torayca® Prepreg P3051S-30) was used on the release-treated mandrel, and layers were stacked at ±45°, 90°, and 0° angles with the longitudinal direction of the mandrel as the 0° axis. Then, a polyamide film (thickness 200 μm) was wrapped around it six times. Furthermore, wrapping tape (heat-resistant film tape, width 10 mm) was wrapped around the outside with a tension of 3 kg, and heat molding was performed in a curing oven at 150°C for 30 minutes. After this, the mandrel was removed, the wrapping tape was removed, and then it was cut to obtain a pipe 5 with an outer diameter of 20.0 mm, a thickness of 2.0 mm, and a length of 500 mm.

[0101] Next, an annular A2000 series aluminum molded body 5 with an inner diameter of 19.8 mm, an outer diameter of 25.0 mm, and a length of 30 mm was prepared in a room temperature environment.

[0102] Subsequently, with the aluminum molded body 5 heated to 300°C using a far-infrared heater, the pipe 5 was inserted into the aluminum molded body 5, and fitted so that 30 mm from the end of the outer surface of the pipe 5 was in contact with the inner surface of the aluminum molded body 5. The pipe was then fixed in a vise and cooled by being left undisturbed at room temperature for 24 hours to manufacture the frame structure.

[0103] The concentricity of the obtained frame structures was 0.4 mm, and the joint strength was 10 MPa or higher for all five samples. Furthermore, no cracks were observed. In this embodiment, the ratio of the thickness t of the buffer layer to the inner dimension d of the outer member was 0.061, which falls outside the range described in [7] of "Means for Solving the Problem".

[0104] [Example 6] The same procedure as in Example 1 was followed, except that a mandrel with a square cross-sectional shape and a side length of 20 mm was used to obtain a pipe 6 with an outer dimension of 30.5 mm and a length of 500 mm.

[0105] Next, an annular A2000 series aluminum molded body 6 was prepared, having a square internal cross-sectional shape and measuring 30 mm internally, 40 mm externally, and 30 mm in length at room temperature.

[0106] Subsequently, with the aluminum molded body 6 heated to 300°C using a far-infrared heater, the pipe 6 was inserted into the aluminum molded body 6, and fitted so that 30 mm from the end of the outer surface of the pipe 6 was in contact with the inner surface of the aluminum molded body 6. The pipe was then fixed in a vise and cooled by being left at room temperature for 24 hours to manufacture the frame structure.

[0107] The concentricity of the obtained frame structures was 0.04 mm, and the joint strength was 15 MPa or higher for all five samples. Furthermore, no cracks were observed.

[0108] [Example 7] The same polyamide film used in Example 1 was used. The same release-treated mandrel used in Example 1 was also used. The above polyamide film was adjusted to a thickness of 100 μm and wrapped around the release-treated mandrel once. Next, a thermosetting prepreg (Toray Industries, Inc., Torayca® prepreg P3051S-30) was used and laminated so that the longitudinal direction of the mandrel was ±45°, 90°, and 0° with the 0° axis. Furthermore, wrapping tape (heat-resistant film tape, width 10 mm) was wrapped around the outside with a tension of 3 kg and heat molding was performed in a curing oven at 150°C for 30 minutes. After this, the mandrel was removed, the wrapping tape was removed, and then it was cut to produce a pipe 7 with an inner diameter of 28.0 mm, an outer diameter of 28.5 mm, a thickness of 0.5 mm, and a length of 500 mm.

[0109] Next, an annular A2000 series aluminum molded body 7 with an inner diameter of 23.0 mm, an outer diameter of 28.1 mm, and a length of 80 mm was prepared in a room temperature environment.

[0110] Subsequently, the aluminum molded body 7 was cooled to -100°C using a refrigerant, and then inserted into the pipe 7. The aluminum molded body 7 was fitted so that 30 mm from the end of the inner circumference of the pipe 7 was in contact with the inner circumference of the aluminum molded body 7, and then fixed in place with a vise. The frame structure was then manufactured by leaving it undisturbed until it reached room temperature.

[0111] The concentricity of the obtained resin-metal joints was 0.1 mm, and the joint strength was 13 MPa or higher for all five samples. Furthermore, no cracks were observed.

[0112] [Comparative Example 1] As the pipe, a pipe 1 with an outer diameter of 28.6 mm, a thickness of 0.5 mm, and a length of 500 mm, similar to the one used in Example 1, was used.

[0113] Furthermore, an annular A2000 series aluminum molded body 8 with an inner diameter of 28.6 mm, an outer diameter of 40 mm, and a length of 30 mm was prepared in a room temperature environment.

[0114] With the aluminum molded body 8 heated to 300°C using a far-infrared heater, the pipe 1 was inserted into the aluminum molded body 8, and fitted so that 30 mm from the end of the outer surface of the pipe 1 was in contact with the inner surface of the aluminum molded body 8. The pipe was then fixed in a vise and allowed to cool at room temperature for 24 hours to manufacture the frame structure.

[0115] The concentricity of the obtained frame structures was 1.0 mm, and the joint strength was 2 MPa or less for all five samples.

[0116] 1. Resin member (a) (first cylindrical body) 2. Metal member (b) (joint, base, or second cylindrical body) 3. Joint 4. Buffer layer

Claims

1. A frame structure comprising a resin-metal joint having a resin member (a) substantially made of fiber-reinforced thermosetting resin and a metal member (b), wherein a cylindrical or columnar portion of the resin member (a) is fitted to the inner circumference of the metal member (b), or a cylindrical or columnar portion of the metal member (b) is fitted to the inner circumference of the resin member (a), and in the fitting portion, the outer cross-section of the inner member to be fitted and the inner cross-section of the outer member to be fitted are similar in shape, and the outer dimension D of the inner member and the inner dimension d of the outer member satisfy D > d.

2. The fitting allowance (D-d) / D in the fitting portion is 1.0 × 10 －４ ~5.0 x 10 －２ The frame structure according to claim 1.

3. The frame structure according to claim 1 or 2, wherein the outer dimension D of the cylindrical or columnar portion of the inner member is 10 to 150 mm.

4. The frame structure according to claim 1 or 2, wherein the length of the fitting portion is 5.0 to 200 mm.

5. The frame structure according to claim 1 or 2, wherein at least one of the inner member or the outer member has a buffer layer made of a thermosetting resin or a thermoplastic resin, and the two members are joined together via the buffer layer.

6. The frame structure according to claim 5, wherein the resin member (a) has a fiber-reinforced thermosetting resin layer and a buffer layer made of a thermosetting resin or thermoplastic resin, and the two members are joined together via the buffer layer.

7. The ratio t / d of the thickness t of the buffer layer to the inner dimension d of the outer member is 1.0 × 10 －４ ~5.0 x 10 －２ The frame structure according to claim 5, which is within the range.

8. The frame structure according to claim 5, wherein the buffer layer is made of a thermoplastic resin.

9. The frame structure according to claim 8, wherein the melting point of the thermoplastic resin is 100 to 300°C.

10. The frame structure according to claim 5, wherein the buffer layer has a Shore A hardness of 5 or more and 90 or less, or a Young's modulus of 0.1 MPa or more and 4000 MPa or less.

11. The frame structure according to claim 5, wherein the buffer layer consists of a polymer coating layer formed on the mating surface or a resin molded body interposed in the mating portion.

12. The frame structure according to claim 5, wherein the buffer layer comprises silicone rubber, fluororubber, thermoplastic polyurethane, thermoplastic elastomer, natural rubber, styrene-butadiene rubber, nitrile rubber, ethylene propylene rubber, polypropylene resin, polyethylene resin, nylon resin, polycarbonate resin, polyimide resin, polyvinyl chloride, polystyrene resin, polymethyl methacrylate, polyurethane foam, polyethylene foam, elastomer foam, or epoxy resin, or a mixture thereof, or a coating of a polymer coating, ceramic coating, metal oxide coating, glassy coating, or carbon-based coating, or a mixture thereof.

13. The frame structure according to claim 5, wherein the coefficient of friction at the interface between the mating surface of the metal member (b) and the buffer layer is 0.3 or greater.

14. The frame structure according to claim 1 or 2, wherein the surface roughness Ra of the mating surface of the metal member (b) is 1.0 μm or more and 50.0 μm or less.

15. The frame structure according to claim 1 or 2, wherein the concentricity between the outer cross-section of the inner member and the inner cross-section of the outer member in the fitting portion is 1.0 mm or less.

16. The number of cracks per unit area on the surface of the resin member (a) is 3 / cm². ２ The frame structure according to claim 1 or 2, which is as follows:

17. The frame structure according to claim 1 or 2, wherein the outer member is a joint or a base.

18. A flying body comprising the frame structure described in claim 1 or 2.

19. A method for manufacturing a frame structure by fitting together a resin member (a) substantially made of fiber-reinforced thermosetting resin and a metal member (b), wherein one of the resin member (a) and the metal member (b) has a cylindrical or columnar portion and the other has an opening, the outer dimension D of the cylindrical or columnar portion and the inner dimension d of the opening satisfy the relationship D > d at room temperature, and the cylindrical or columnar portion and the opening have similar cross-sectional shapes, the manufacturing method comprising: a step of changing the dimensions of the metal member (b) by heating or cooling; a step of inserting the cylindrical or columnar portion into the opening in a state where it has become insertable due to the dimensional change; and a step of returning the temperature to room temperature so that a tightening allowance is created between the two members and the fitting is completed.

20. A method for manufacturing a frame structure according to claim 19, wherein the resin member (a) has the cylindrical or columnar portion, the metal member (b) has the opening, the step of changing the dimensions of the metal member (b) by heating is the step of expanding the metal member (b) by heating, and the step of returning the temperature to room temperature is the step of shrinking the metal member (b) by cooling.

21. The method for manufacturing a frame structure according to claim 19, wherein the metal member (b) has the cylindrical or columnar portion, the resin member (a) has the opening, the step of changing the dimensions of the metal member (b) by cooling is the step of cooling and shrinking the metal member (b), and the step of returning the temperature to room temperature is the step of expanding the metal member (b) by heating.

22. A method for manufacturing a frame structure according to any one of claims 19 to 21, wherein a buffer layer made of a thermosetting resin or thermoplastic resin is formed in advance on at least one of the outer surface of the cylindrical or columnar portion or the inner surface of the opening, and the two members are fitted together after the outer dimension D and the inner dimension d are filled with the buffer layer.

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