Curved panel components

Abstract

A curved plate component comprises: a curved plate made of metal; and a reinforcing member, which is joined to the curved plate and is composed of a plurality of FRP layers containing continuous fibers, each of the plurality of FRP layers being composed of a fiber direction, at least one of the plurality of FRP layers having a fiber direction different from that of the other layers, and in the plurality of FRP layers, the proportion of layers having an angle difference of 30° or more in the fiber directions being at least 15% of all the layers, and regarding the fiber directions of each FRP layer of the reinforcing member joined to the curved plate, when a 0° direction component and a 90° direction component are calculated respectively using trigonometric functions, equation (1) is satisfied, wherein the maximum principal curvature direction of the curved plate is defined as the 0° direction, and the direction orthogonal to the 0° direction is defined as the 90° direction.

Description

Technical Field

[0001] The present invention relates to the construction of a plate having a curvature. Background Art

[0002] As an example of a plate having a curvature (hereinafter, a "curved plate"), there are metal plates having an overall curved surface such as a door outer panel, a roof panel, an engine hood, a fender, and a side outer panel of an automobile. In automobile development, in order to reduce weight for the purpose of improving fuel efficiency, thinning of steel plates, which are used as raw materials for curved plates, is being developed. On the other hand, thinning of steel plates reduces the tensile rigidity of curved plates, and therefore it is required to strengthen the curved plates to ensure sufficient tensile rigidity.

[0003] As a structure for reinforcing a curved panel, Patent Document 1 discloses a curved panel member in which an FRP (fiber reinforced resin) sheet is attached to a metal plate. In the curved panel member of Patent Document 1, the recovery performance of the curved panel when deformed is improved by appropriately changing the shape of the FRP sheet. Patent Document 2 discloses that CFRP is attached within a range of 1% to 30% of the panel area so that the load when the center of the panel is pressed is dispersed to the edge of the panel on the side to which the CFRP is attached. Patent Document 3 discloses a structure having an inner layer made of glass fiber surrounding a hollow core, an intermediate layer made of FRP, and an outer layer made of glass fiber. Patent Document 4 discloses a panel structure in which, in a door of a car, a reinforcing rib forming material such as foamed polyethylene having a width narrower than that of the reinforcing resin layer made of FRP is provided under a reinforcing resin layer made of FRP, and the lower surface of the hem of a reinforcing member having a width wider than that of the reinforcing rib forming material is attached to the panel. Patent document 5 discloses a vehicle roof structure having a reinforcing member made of FRP and extending obliquely with respect to the vehicle width direction. Patent document 6 discloses an FRP structure having a sandwich structure in which FRP layers are arranged on the surface side and the back side of a core material. Patent document 7 discloses a structural member in which a reinforcing member such as a carbon fiber unidirectional material or a carbon fiber cross fabric having a convex bonding portion is bonded to a main structural material.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2001-253371

[0007] Patent Document 2: Japanese Patent Application Publication No. 2018-016171

[0008] Patent Document 3: Japanese Patent Application Publication No. 2003-291232

[0009] Patent Document 4: Japanese Patent Application Laid-Open No. 57-151357

[0010] Patent Document 5: International Publication No. 2014 / 034586

[0011] Patent Document 6: Japanese Patent Application Publication No. 2008-213437

[0012] Patent Document 7: Japanese Patent Application Publication No. 2009-166408 Summary of the invention

[0013] Problem that the invention aims to solve

[0014] Patent document 1 discloses various shapes of FRP sheets, but giving shapes to FRP sheets in order to obtain a reinforcement effect will significantly increase the manufacturing process of FRP sheets, resulting in a decrease in productivity. Therefore, it is desirable to strengthen the curved plate by other methods. In Patent document 2, the load is dispersed only when the center of the plate is pressed, and it is difficult to fundamentally improve the tensile stiffness. The structure of Patent document 3 is a structure that must have a hollow core in the inner layer, so there are problems such as it cannot be applied to situations where there are restrictions on the internal space of the reinforced side of the plate. In the structures of Patent document 4 and Patent document 5, only a part of the plate is reinforced, so there is a limit to the improvement of tensile stiffness, and there is a problem that if the entire surface of the plate is reinforced, the overall weight becomes larger. The FRP structure of Patent document 6 is a structure that must be provided with a core material, so there are problems such as it cannot be applied when there are restrictions on the internal space of the reinforced side of the plate. In the structure of Patent document 7, a convex reinforcement member is attached to the main structural material, so there are problems such as it cannot be applied when there are restrictions on the internal space.

[0015] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a curved panel member capable of improving tensile rigidity without using a cross-woven fabric.

[0016] Solutions for solving problems

[0017] A technical solution of the present invention for solving the above-mentioned problems is a curved panel member comprising:

[0018] A curved plate made of metal; and

[0019] A reinforcing member, which is joined to the curved plate, is composed of a plurality of FRP layers containing continuous fibers,

[0020] Each of the plurality of FRP layers is composed of one fiber direction,

[0021] At least one of the plurality of FRP layers has a fiber direction different from that of the other layers,

[0022] In the plurality of FRP layers, the proportion of layers having a fiber direction angle difference of 30° or more is 15% or more of all layers,

[0023] Regarding the fiber directions of each FRP layer of the reinforcing member joined to the curved plate, the following formula (1) is satisfied when the 0° direction component and the 90° direction component are calculated using trigonometric functions, respectively, wherein the maximum principal curvature direction of the curved plate is defined as the 0° direction, and the direction orthogonal to the 0° direction is defined as the 90° direction,

[0024] 580×K≤(A×4+B) / (C+D) (1)

[0025] A: The 0° direction component of the FRP layer outside the plate thickness center of the reinforcing member

[0026] B: The 0° direction component of the FRP layer located inside the plate thickness center of the reinforcing member

[0027] C: the 0° direction component in all the layers of the plurality of FRP layers

[0028] D: the 90° direction component in all the layers of the plurality of FRP layers

[0029] K: 1 / the radius of curvature in the 0° direction, in mm.

[0030] The reinforcing member may be bonded to 70% or more of the area of ​​the curved plate. The reinforcing member may be bonded to the entire surface of the curved plate. The thickness of the reinforcing member may be at least 2.0 times the thickness of the curved plate.

[0031] Alternatively, the curved panel is a hood or roof panel of a car, and the reinforcing member is joined to the lower surface of the curved panel. Alternatively, the curved panel is a fender, door outer panel or side outer panel of a car, and the reinforcing member is joined to the inner surface of the curved panel.

[0032] The curved plate may also be a steel plate with a strength of 440 MPa or more. The FRP may also be CFRP. The FRP may also be GFRP.

[0033] Effects of the Invention

[0034] According to the present invention, it is possible to provide a curved plate member capable of improving tensile rigidity without using a cross-woven fabric. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a perspective view showing a schematic structure of a curved plate member according to one embodiment of the present invention.

[0036] Figure 2 Observed from the back side Figure 1 A three-dimensional image obtained by using a curved panel component.

[0037] Figure 3 This is a diagram showing an example of a vehicle body structure.

[0038] Figure 4 It is a diagram for explaining the layer structure of the reinforcing member according to the present embodiment.

[0039] Figure 5 This is a diagram for explaining the calculation method of the 0° direction component and the 90° direction component of the fiber direction.

[0040] Figure 6 This is a diagram for explaining the calculation method of the 0° direction component and the 90° direction component of the fiber direction.

[0041] Figure 7 This is a diagram showing an example of the layer structure of the reinforcing member according to the present embodiment.

[0042] Figure 8 It is a diagram showing an example of joining a curved plate and a reinforcing member.

[0043] Fig. 9 It is a graph showing conditions for evaluating tensile rigidity. DETAILED DESCRIPTION

[0044] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that in this specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals to omit repeated description.

[0045] like Figure 1 and Figure 2 As shown, the curved panel component 1 of the present embodiment includes a metal curved panel 2 and a reinforcing member 3 formed of a plurality of FRP layers containing continuous fibers joined to the curved panel 2. The raw material of the metal curved panel 2 is not particularly limited, and for example, a steel plate, an aluminum alloy plate, a magnesium alloy plate, etc. can be used. From the viewpoint of improving tensile stiffness and impact resistance, the curved panel 2 is preferably formed of a steel plate of 440 MPa or more. The "curved panel" in this specification includes not only components in which the entire surface of the plate is curved, but also components in which a portion has concave-convex and flat portions and is curved as a whole. As an example of a curved panel 2, Figure 3 Such parts as the hood, roof panel, fender, door outer panel or side outer panel of the automobile. In addition, the curved plate 2 is not limited to automobile parts, and can also be other plate-like members.

[0046] It should be noted that the curved panel 2 is obtained by processing a flat plate. Therefore, at the stage of manufacturing the curved panel 2, the shape and raw materials of the product are determined, and the purpose is also determined. Therefore, it is possible to determine the surface on the surface side and the back side of the curved panel 2 that has a high frequency of inputting loads from the out-of-plane direction when used as a product. For example, in the case of an outer door panel of a car, if the surface side is used as the surface on the outside of the car and the back side is used as the surface on the inside of the car, the surface on the outside of the car has a higher frequency of inputting loads from the out-of-plane direction than the surface on the inside of the car. That is, Figure 1 In the example shown, the side to which the reinforcing member 3 is joined, indicated by the dotted line, becomes the surface of the door outer panel on the vehicle inner side. In this specification, the surface on the front side and the back side of the curved plate 2, whichever side has a higher frequency of inputting the load from the out-of-plane direction as described above, is referred to as the "surface on the load input side". In this embodiment, the curved surface 2a, which is the surface with a smaller curvature among the curved surfaces 2a and 2b of the curved plate 2, is used as the surface on the load input side for the following description, but depending on the use of the curved plate 2, the curved surface 2b, which is the surface with a larger curvature, may also become the surface on the load input side.

[0047] From the viewpoint of effectively improving the tensile rigidity, the reinforcing member 3 is preferably joined to the curved surface 2b on the side opposite to the load input side. When the curved panel 2 is, for example, a hood or a roof panel of an automobile, the curved surface 2a on the load input side is the upper surface (the surface on the outside of the vehicle) of the curved panel 2, and therefore the reinforcing member 3 is preferably joined to the lower surface (the surface on the inside of the vehicle) of the curved panel 2. When the curved panel 2 is, for example, a fender, a door outer panel, or a side panel of an automobile, the curved surface 2a on the load input side is the surface on the outside of the curved panel 2, and therefore the reinforcing member 3 is preferably joined to the surface on the inside of the curved panel 2.

[0048] The reinforcing member 3 of the present embodiment is joined to the curved surface 2b on the side opposite to the load input side of the curved panel 2. The joining method of the reinforcing member 3 to the curved panel 2 is not particularly limited, and for example, it is joined using an adhesive. From the viewpoint of effectively improving the tensile stiffness of the curved panel component 1, the plate thickness of the reinforcing member 3, that is, the total plate thickness of the plurality of FRP layers is preferably 2.0 times or more of the plate thickness of the curved panel 2. The plate thickness of the reinforcing member 3 is more preferably 2.5 times or more of the plate thickness of the curved panel 2, and further preferably 3.0 times or more. The upper limit of the plate thickness of the reinforcing member 3 is appropriately set from the viewpoint of the tensile stiffness and weight of the required curved panel component 1, but the plate thickness of the reinforcing member is preferably 10.0 times or less of the plate thickness of the curved panel 2, more preferably 7.5 times or less, and further preferably 5.0 times or less.

[0049] (Example of reinforcement member)

[0050] FRP that can be used for a reinforcement member (also referred to as an FRP member) refers to a fiber-reinforced resin composed of a matrix resin and a composite reinforcing fiber material contained in the matrix resin.

[0051] As the reinforcing fiber material, for example, carbon fiber and glass fiber can be used. In addition, as the reinforcing fiber material, boron fiber, silicon carbide fiber, aramid fiber, etc. can also be used. In the FRP used for the FRP component, as the reinforcing fiber substrate that becomes the substrate of the reinforcing fiber material, for example, a unidirectional reinforcing fiber substrate (UD material) can be used. These reinforcing fiber substrates can be appropriately selected according to the needs of the orientation of the reinforcing fiber material.

[0052] CFRP is FRP that uses carbon fiber as a reinforcing fiber material. As the carbon fiber, for example, PAN-based or asphalt-based carbon fiber can be used. The carbon fiber of CFRP is preferably asphalt-based carbon fiber with a high elastic modulus. The reinforcement member 3 using asphalt-based carbon fiber can obtain a higher reaction force and improve the tensile rigidity.

[0053] GFRP is FRP that uses glass fiber as a reinforcing fiber material. Although its mechanical properties are inferior to carbon fiber, it can suppress the electrical corrosion of metal components.

[0054] As the matrix resin for FRP, both thermosetting resin and thermoplastic resin can be used. As thermosetting resin, epoxy resin, unsaturated polyester resin and vinyl ester resin etc. can be listed. As thermoplastic resin, polyolefin (polyethylene, polypropylene etc.) and its acid modified product, polyamide resin such as nylon 6 and nylon 66, thermoplastic aromatic polyester such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate, polyether sulfone, polyphenylene ether and its modified product, polyarylate, polyether ketone, polyether ether ketone, polyether ketone ketone, vinyl chloride, polystyrene etc. styrene resin and phenoxy resin etc. can be listed. It should be noted that the matrix resin can also be formed by a variety of resin materials.

[0055] If the application to metal components is considered, from the viewpoint of processability and productivity, it is preferred to use a thermoplastic resin as the matrix resin. Moreover, by using a phenoxy resin as the matrix resin, the density of the reinforcing fiber material can be increased. In addition, the phenoxy resin has the same degree of heat resistance as the epoxy resin because its molecular structure is very similar to that of the epoxy resin as a thermosetting resin. In addition, by further adding a curing component, it can also be applied to a high temperature environment. When adding a curing component, its addition amount is appropriately determined considering the impregnation of the reinforcing fiber material, the brittleness of FRP, the production cycle time and processability.

[0056] <Adhesive Resin Layer>

[0057] When the reinforcing member is formed of an FRP member or the like, an adhesive resin layer (not shown) may be provided between the FRP member and the metal member (in this embodiment, the curved plate 2 ) to bond the FRP member and the metal member using the adhesive resin layer.

[0058] The type of the adhesive resin composition forming the adhesive resin layer is not particularly limited. For example, the adhesive resin composition can be any one of a thermosetting resin and a thermoplastic resin. The types of thermosetting resins and thermoplastic resins are not particularly limited. For example, as a thermoplastic resin, one or more selected from thermoplastic aromatic polyesters such as polyolefins and acid-modified products thereof, polystyrene, polymethyl methacrylate, AS resin, ABS resin, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyimide, polyamide, polyamide-imide, polyetherimide, polyether sulfone, polyphenylene ether and modified products thereof, polyphenylene sulfide, polyoxymethylene, polyarylate, polyether ketone, polyether ether ketone and polyether ketone ketone can be used. In addition, as a thermosetting resin, for example, one or more selected from epoxy resins, vinyl ester resins, phenolic resins and polyurethane resins can be used.

[0059] The adhesive resin composition can be appropriately selected according to the properties of the matrix resin constituting the FRP member, the properties of the reinforcing member or the properties of the metal member. For example, by using a resin having a polar functional group or a resin subjected to acid modification as the adhesive resin layer, the adhesiveness can be improved.

[0060] By bonding the FRP component to the metal component using the adhesive resin layer, the adhesion between the FRP component and the metal component can be improved. In this way, the deformation followability of the FRP component when the metal component is input with a load can be improved. In this case, the effect of the FRP component on the deformation of the metal component can be more reliably exerted.

[0061] The adhesive resin composition used to form the adhesive resin layer may be in the form of, for example, a powder, a liquid such as a varnish, or a solid such as a film.

[0062] In addition, a cross-linking curable resin and a cross-linking agent may be mixed in the adhesive resin composition to form a cross-linking adhesive resin composition. As a result, the heat resistance of the adhesive resin composition is improved, so it can be used in a high temperature environment. As a cross-linking curable resin, for example, an epoxy resin with more than two functionalities and a crystalline epoxy resin can be used. In addition, as a cross-linking agent, amines, acid anhydrides, etc. can be used. In addition, various rubbers, inorganic fillers, solvents and other additives may also be mixed in the adhesive resin composition within the range of not damaging its adhesion and physical properties.

[0063] The composite of the FRP component to the metal component is achieved by various methods. For example, the FRP component to be the FRP component or the FRP molding prepreg as its precursor is bonded to the metal component by using the above-mentioned adhesive resin composition and the adhesive resin composition is cured (or hardened). In this case, for example, the FRP component and the metal component can be composited by performing heat pressing.

[0064] The bonding of the above-mentioned FRP or FRP prepreg for molding to the metal component can be carried out before, during or after the component is molded. For example, after the metal material as the workpiece is molded into the metal component, the FRP or FRP prepreg for molding can be bonded to the metal component. In addition, after the FRP or FRP prepreg for molding is bonded to the workpiece by heat pressing, the workpiece bonded with the FRP component can be molded to obtain a composite metal component. If the matrix resin of the FRP component is a thermoplastic resin, the portion bonded with the FRP component can also be bent and molded. In addition, in the case where the matrix resin of the FRP component is a thermoplastic resin, the heat pressing process and the molding process can be integrated into a composite molding.

[0065] It should be noted that the method of joining the FRP component and the metal component is not limited to the bonding performed using the above-mentioned adhesive resin layer. For example, the FRP component and the metal component can also be mechanically joined. More specifically, fastening holes can also be formed at positions corresponding to the FRP component and the metal component, and they can be fastened through the holes using fastening components such as bolts and rivets, thereby joining the FRP component and the metal component. In addition, the FRP component and the metal component can also be joined using known joining means. In addition, the FRP component and the metal component can also be compositely joined using multiple joining means. For example, bonding using an adhesive resin layer and fastening based on fastening components can also be used in a composite manner.

[0066] <Metal components and their surface treatment>

[0067] The metal component of the present invention may be a hot-rolled steel plate or a cold-rolled steel plate, but these steel plates may also be plated. Thus, the corrosion resistance is improved. In particular, it is more suitable when the metal component is a steel material. The type of plating is not particularly limited, and known plating can be used. For example, as a plated steel plate (steel material), a hot-dip galvanized steel plate, an alloyed hot-dip galvanized steel plate, a Zn-Al-Mg alloy plated steel plate, an aluminum-plated steel plate, an electro-galvanized steel plate, a Zn-Ni alloy electro-plated steel plate, etc. may be used. There is no need to specifically limit the plate thickness of the metal component. For example, in automotive components, the plate thickness is mostly around 0.60 mm to 3.2 mm.

[0068] In addition, the metal component may also be covered with a coating called chemical conversion treatment on the surface. Thereby, the corrosion resistance is further improved. As the chemical conversion treatment, a commonly known chemical conversion treatment can be used. For example, as the chemical conversion treatment, zinc phosphate treatment, chromate treatment, chromate-free treatment, etc. can be used. In addition, the above-mentioned coating may also be a known resin coating.

[0069] In addition, the metal components can also be subjected to commonly known coatings. Thus, the corrosion resistance is further improved. As a coating, a well-known resin can be used. For example, as a coating, a coating with epoxy resin, polyurethane resin, acrylic resin, polyester resin or fluorine resin as the main resin can be used. In addition, a commonly known pigment can also be added to the coating as needed. In addition, the coating can also be a transparent coating without adding pigment. The coating can be applied to the metal component in advance before the FRP component is compounded, or it can be applied to the metal component after the FRP component is compounded. In addition, it is also possible to apply the coating to the metal component in advance, compound the FRP component, and then apply the coating. The coating used in the coating can also be a solvent-based coating, a water-based coating or a powder coating. As a coating construction method, a commonly known method can be applied. For example, as a coating construction method, electrodeposition coating, spraying, electrostatic coating or dipping coating can be used. Electrodeposition coating is suitable for covering the end faces and gaps of metal components, so the corrosion resistance after coating is excellent. Furthermore, by subjecting the surface of the metal member to a generally known chemical conversion treatment such as zinc phosphate treatment or zirconium oxide treatment before painting, the coating film adhesion is improved.

[0070] (Multiple FRP layers)

[0071] (Each FRP layer has one fiber direction)

[0072] (The ratio of the FRP layer having an angle difference of 30° or more in the fiber direction is 15% or more of the total layers)

[0073] Figure 4 It is a diagram for explaining the layer structure of the reinforcing member 3. Each of the multiple FRP layers constituting the reinforcing member 3 is composed of one fiber direction, and at least one of the multiple FRP layers has a fiber direction different from that of the other layers. Here, in this specification, the maximum principal curvature direction of the curved plate 2 is defined as the "0° direction", and the direction orthogonal to the 0° direction when facing the curved surface defining the 0° direction is defined as the "90° direction". Figure 4In the example shown, the FRP has a 6-layer structure. In the 4 layers of the FRP layers close to the curved surface 2b of the curved plate 2, the continuous fibers are oriented in the 0° direction, and in the remaining 2 layers, the continuous fibers are oriented in the 90° direction. It should be noted that in this specification, the layer in which the continuous fibers are oriented in a specific direction is called an "oriented layer". For example, the layer in which the fibers are oriented in the 0° direction is called a 0° oriented layer, and the layer in which the fibers are oriented in the 90° direction is called a 90° oriented layer. That is, Figure 4 The reinforcement member 3 shown has four 0° oriented layers 3a and two 90° oriented layers.

[0074] It should be noted that the "θ° oriented layer" also includes an oriented layer composed of continuous fibers oriented along θ±5°. For example, the "0° oriented layer" not only includes an FRP layer in which the fiber direction of the continuous fibers strictly indicates the 0° direction, but also includes an oriented layer containing continuous fibers oriented along -5° to 5° relative to the 0° direction. The fiber direction of the oriented layer can be determined by observing and analyzing the fiber reinforced resin component using microfocus X-ray CT (X-ray Computed Tomography). The total number of layers constituting the reinforcing member 3 is not particularly limited and can be appropriately changed according to the shape of the curved panel 2, the required tensile stiffness, etc. In addition, the size of the reinforcing member 3, the thickness of each layer of the FRP, and the joining position of the reinforcing member 3 relative to the curved panel 2 are not particularly limited and can be appropriately changed according to the shape of the curved panel 2, the required tensile stiffness, etc.

[0075] In addition, the inventors of the present application evaluated the tensile stiffness of a member formed by pasting a raw material such as the carbon fiber cross fabric of Patent Document 7, in which fibers in two or more directions are woven into one layer of FRP, to a curved plate. As a result, the effect of improving the tensile stiffness was small. The reason is not clear, but it is believed that the cross fabric may be affected by fiber fluctuations. The present invention is based on the evaluation results and studies on improving the tensile stiffness by stacking FRP layers in one fiber direction without using cross fabrics. Therefore, the reinforcing member of the present invention is composed of multiple FRP layers, and each of the multiple FRP layers has one fiber direction.

[0076] According to the research of the inventors of the present application, it is found that even if the fiber directions of each FRP layer are in one direction, when the fiber directions of multiple FRP layers are all in the same direction (for example, the fiber directions of all FRP layers are in the direction perpendicular to the maximum principal curvature, that is, all FRP layers are 90° oriented layers), as described later, the effect of improving tensile stiffness is small. Based on this view, the inventors found that in order to improve tensile stiffness, it is better not to align the fiber directions of multiple FRP layers in one direction, and it is better that there are FRP layers with an angle difference of more than 30° in the fiber directions and the proportion of FRP layers with an angle difference of more than 30° in the fiber directions is more than 15% of all FRP layers. The value of "the proportion of FRP layers with an angle difference of more than 30° in the fiber directions in all layers" in FRP layers with different fiber directions varies depending on the fiber direction used as the reference among multiple fiber directions, but in this specification, the above proportion is calculated separately when each fiber direction is used as the reference, and the lowest proportion value is used. For example, in case a11 of the embodiment described later, the proportion of the FRP layer with an angle difference of 30% or more in the total layers is 67% (4 layers / 6 layers = 0.67) when the 90° direction is used as the reference, and the proportion is 33% (2 layers / 6 layers = 0.33) when the 0° direction is used as the reference. Therefore, the lowest value of the proportion in this case is 33%, so the proportion of the FRP layer with an angle difference of 30° or more in the fiber direction is 33% of the total layers. It should be noted that when the thickness of each FRP layer is approximately the same as the density of the FRP fiber, the calculation is performed by the above method, but when the thickness and density of each layer are different, the thickness and density of each layer are used as weights to calculate the proportion.

[0077] The angle difference of the FRP layer is preferably larger, preferably 40° or more, 50° or more, or 60° or more. The upper limit of the angle difference is of course 90°. The proportion of the FRP layer in the fiber direction above the predetermined angle difference in the total layer is preferably larger, preferably 20% or more, 25% or more, or 30% or more. However, the upper limit of this proportion is 50%.

[0078] The curved plate member 1 is constructed as described above. Figure 1 In the case of such a curved plate 2, if a load F from the out-of-plane direction is input to the curved surface 2a on the load input side of the curved plate 2, a substantially circular deformation occurs around the load input position. The inventors of the present invention have found that in such a case, if a curved plate member 1 having a reinforcing member 3 that satisfies the following formula (1) and at least one of the multiple FRP layers has a fiber direction different from that of the other layers, and the proportion of the FRP layers having an angle difference of 30° or more in the fiber direction is 15% or more of all the layers, is effectively improved in tensile rigidity.

[0079] 580×K≤(A×4+B) / (C+D) (1)

[0080] A: The 0° direction component of the FRP layer outside the plate thickness center of the reinforcing member

[0081] B: The 0° direction component of the FRP layer located inside the plate thickness center of the reinforcing member

[0082] C: the 0° direction component in all the layers of the plurality of FRP layers

[0083] D: the 90° direction component in all the layers of the plurality of FRP layers

[0084] K: 1 / radius of curvature in the 0° direction (mm)

[0085] (Calculation method of 0° direction component and 90° direction component)

[0086] In this specification, the ratio of the 0° direction component (the component parallel to the direction of the maximum principal curvature of the curved plate 2) and the 90° direction component (the component parallel to the direction perpendicular to the direction of the maximum principal curvature of the curved plate 2) is calculated as follows. Here, an example is shown in which all the layers of FRP constituting the reinforcing member joined to the curved plate 2 contain two types of fiber directions. Figure 5 Indicates that the angle (acute angle) with the 0° direction is θ 1 The first fiber direction of the FRP layer, Figure 6 Indicates that the angle (acute angle) with the 0° direction is θ 2 The first fiber direction and the second fiber direction are different directions. The "0° direction component" in this specification refers to the fiber direction of the FRP layer, which is decomposed into the 0° direction component (that is, cosθ 1 or cosθ 2 ) and the 90° component (that is, cos(90°-θ 1 )=sinθ 1 or cos(90°-θ 2 )=sinθ 2 ) and the absolute value of the 0° direction component calculated. In addition, the "90° direction component" in this specification is the absolute value of the 90° direction component calculated by decomposing the fiber direction of the FRP layer into the 0° direction component and the 90° direction component using a trigonometric function component.

[0087] When calculating the 0° direction component (“C” in the above formula (1)) and the 90° direction component (“D” in the above formula (1)) in all layers, first, for the FRP layer having the first fiber direction, the angle θ 1 The components are decomposed to calculate the 0° direction component and the 90° direction component. At this time, if there is another FRP layer with the first fiber direction, the angle θ is also calculated for this layer. 1 Component decomposition is performed to calculate the 0° direction component and the 90° direction component. Next, for the FRP layer with the second fiber direction, the angle θ 2 The components are decomposed to calculate the 0° direction component and the 90° direction component. At this time, if there is another FRP layer with a second fiber direction, the angle θ is calculated for this layer in the same way. 2 Component decomposition is performed to calculate the 0° direction component and the 90° direction component. In this way, after calculating the 0° direction component and the 90° direction component for each layer, the 0° direction component of each layer is summed up to calculate the 0° direction component of all layers in formula (1) ("C" in formula (1)). Similarly, the 90° direction component of all layers in formula (1) is summed up to calculate the 90° direction component of all layers ("D" in formula (1)).

[0088] For example, Figure 5 In the angle θ 1 When the angle θ is 30°, the absolute value of cos30° is the 0° direction component, and the absolute value of sin30° is the 90° direction component. 1 When the first fiber direction is 30°, the 0° direction component is about 0.866, and the 90° direction component is 0.5. Figure 6 In the angle θ 2 When the angle θ is -60°, the absolute value of cos-60° is the 0° direction component, and the absolute value of sin-60° is the 90° direction component. 2 When the angle is -60°, the 0° direction component of the second fiber direction is 0.5, and the 90° direction component is about 0.866. Figure 5 and Figure 6In the case where there are 4 layers with the first fiber direction and 2 layers with the second fiber direction, the 0° direction component in all layers is approximately 4.46 (0.866×4+0.5×2), and the 90° direction component in all layers is approximately 3.73 (0.5×4+0.866×2). The total value of the 0° direction component and the total value of the 90° direction component are calculated in this way. It should be noted that when the fiber direction is in the 0° direction, the value of the 0° direction component is cos0°, that is, 1, and the value of the 90° direction component is sin0°, that is, 0. In addition, when the fiber direction is in the 90° direction, the value of the 0° direction component is cos90°, that is, 0, and the value of the 90° direction component is sin90°, that is, 1.

[0089] In addition, when the thickness of each FRP layer and the density of the FRP fiber are approximately the same, the calculation is performed by the above method. When the thickness and density of each layer are different, the thickness and density of each layer are used as weights to calculate the ratio. For example, when the value of the 0° direction component of the kth layer from the bonding side among n layers of FRP is set to x k , and the thickness of this layer is set to t k In the case of 1 ×t 1 +…+x n ×t n The total value of the 90° direction component is obtained in the same manner.

[0090] In this specification, the center T of the plate thickness of the reinforcing member 3 (that is, the total plate thickness of each layer) is C The FRP layer located on the side of the curved plate 2 is referred to as the "FRP layer at the center of the plate thickness T C The FRP layer on the side opposite to the joining side is referred to as the "layer at the center of the plate thickness T C For example, Figure 4 In the reinforcing member 3, if the thickness of each FRP layer is equal, the three layers on the lower side of the six-layer FRP layer are located at the center of the thickness T of the reinforcing member 3. C The upper three layers of the six-layer FRP are the layers located inside the plate thickness center of the reinforcing member 3. Figure 4 In the example of , the 0° direction component of the FRP layer located outside the plate thickness center of the reinforcing member 3 in formula (1) (“A” in formula (1)) is the total value of the 0° direction components of the three lower layers among the six FRP layers, and the 0° direction component of the FRP layer located inside the plate thickness center of the reinforcing member 3 in formula (1) (“B” in formula (1)) is the total value of the 0° direction components of the three upper layers among the six FRP layers.

[0091] "K" in formula (1) is a value obtained by dividing "1" by the radius of curvature of the curved panel 2 in the 0° direction, which is equivalent to the maximum principal curvature. "K" in formula (1) is an index indicating the shape of the curved panel 2, and therefore, in the following description, "K" in formula (1) is referred to as the shape index K. In order to improve the tensile stiffness of the curved panel component 1, it is important to specify the fiber direction in each FRP layer, but the effect of the fiber direction of FRP on the tensile stiffness of the curved panel component 1 varies depending on the shape of the curved panel 2. In other words, the contribution of the fiber direction of FRP to the tensile stiffness varies depending on the shape of the curved panel 2. Therefore, in order to improve the tensile stiffness of the curved panel component 1, it is important to specify the fiber direction of FRP while also considering the shape of the curved panel 2.

[0092] The condition for satisfying this requirement is formula (1). As shown in the embodiment described later, the use of a curved panel member 1 having a reinforcing member 3 satisfying formula (1) can improve the tensile rigidity by using a reinforcing member 3 having at least one layer among a plurality of FRP layers having a fiber direction different from that of the other layers, a ratio of FRP layers having an angle difference of 30° or more in the fiber direction of more than 15% of all layers.

[0093] It should be noted that, in the description of this embodiment, the fiber directions are two directions, but it may be three or more directions. Figure 7 The reinforcement member 3 shown has a 90° orientation layer 3b, a 45° orientation layer 3c, a -45° orientation layer 3d, a 0° orientation layer 3a, a 90° orientation layer 3b, and a 0° orientation layer 3a in order from the curved surface 2b of the curved plate 2. Even in such a case, by having at least one of the multiple FRP layers have a fiber direction different from that of the other layers, the proportion of the FRP layers having an angle difference of 30° or more in the fiber direction is 15% or more of all the layers, and the reinforcement member 3 satisfying formula (1) is joined to the curved plate 2, the tensile stiffness of the curved plate member 1 can be improved.

[0094] In addition, even if the reinforcing member 3 is joined to the curved surface 2a of the curved panel 2, the tensile rigidity can be improved. However, the reinforcing member 3 is preferably joined to the curved surface 2b on the opposite side of the curved surface 2a. For example, when the curved panel 2 is a component such as a door outer panel, a roof panel, a hood, a fender, or a side outer panel of a car, the load F from the out-of-plane direction is input to the curved surface 2a on the load input side of the curved panel 2, so the tensile stress on the curved surface 2b side of the curved panel 2 becomes large. However, if the reinforcing member 3 is joined to the curved surface 2b of the curved panel 2, the tensile stress generating portion can be effectively reinforced. As a result, it is easier to obtain the effect of improving the tensile rigidity of the curved panel 2.

[0095] In addition, the reinforcing member 3 is preferably as follows Figure 8As shown, the reinforcing member 3 is joined to the entire surface of the curved plate 2. For example, even when the reinforcing member 3 is partially joined to the curved plate 2, the tensile rigidity can be locally improved. However, by joining the reinforcing member 3 to the entire surface of the curved plate 2, the reinforcing effect of the reinforcing member 3 can be obtained regardless of where the load is input to the curved plate 2. Even when the reinforcing member 3 is not joined to the entire surface of the curved plate 2, it is preferred that the reinforcing member 3 is joined to 70% or more of the area of ​​the curved plate 2. More preferably, it is 80% or more of the area of ​​the curved plate 2, and even more preferably, it is 90% or more.

[0096] In addition, when the reinforcing member 3 satisfying the formula (1) is, for example, the same shape as the FRP sheet of the aforementioned patent document 1, the reinforcing effect exerted becomes larger than that of the FRP sheet of the patent document 1. That is, when the product specification related to the tensile rigidity can be satisfied with the reinforcing effect equivalent to that of the patent document 1, for example, the plate thickness of the reinforcing member 3 can be reduced to achieve the weight reduction of the curved plate member 1. Therefore, when the reinforcing member 3 is joined to the entire surface of the curved plate 2, compared with the conventional case where a plurality of FRP sheets are joined to the entire plate, the weight reduction of the plate member can be achieved and sufficient tensile rigidity can be ensured.

[0097] The above describes one embodiment of the present invention, but the present invention is not limited to this example. It is clear that anyone skilled in the art can think of various variations or modifications within the scope of the technical concept described in the claims, and it can be understood that these also belong to the protection scope of the present invention.

[0098] Example

[0099] pass Fig. 9 The method shown evaluates the tensile stiffness of the curved panel component 1. In detail, for the curved panel component 1 in which the reinforcing member 3 is joined to the curved surface 2b on the side opposite to the curved surface 2a on the load input side of the curved panel 2, the tensile stiffness is evaluated by pressing a hemispherical indenter 10 of R50 into the central part of the curved surface 2a of the curved panel 2. The tensile stiffness is evaluated based on the size of the load required to press the indenter 10 into 2mm (hereinafter referred to as "load at 2mm stroke"). The larger the load at 2mm stroke of the curved panel component 1, the higher the tensile stiffness and the less likely it is to deform. The curved panel 2 in this evaluation method is a steel plate with a tensile strength of 590MPa, and the reinforcing member 3 is a member having multiple FRP layers with a Young's modulus of 102GPa.

[0100] In addition, regarding the curved plate 2 , three types of curved plates having different shape indices K as follows were prepared, and the tensile rigidity of each curved plate member was evaluated.

[0101] (a) K = 0.00083 (radius of curvature: 1200 mm)

[0102] (b) K = 0.00125 (radius of curvature: 800 mm)

[0103] (c) K = 0.00250 (radius of curvature: 400 mm)

[0104] The evaluation conditions and results of the tensile stiffness are shown in the following Table 1. As comparative examples, the tensile stiffness was also evaluated for the case of a curved plate alone and the case of CFRP having a single fiber direction.

[0105] [Table 1]

[0106]

[0107] As shown in Table 1, it can be seen that the load at 2 mm stroke of Case a3 to Case a20 in which the curved plate is joined with a reinforcing member is larger than the load at 2 mm stroke of Case a1 and Case a2 in which the curved plate is alone. By joining the reinforcing member to the curved plate, the tensile rigidity is improved.

[0108] The reinforcement members of Case a4 to Case a10 are composed of 6 layers of CFRP with a thickness of 0.20 mm per layer. The weight of the CFRP with a thickness of 1.20 mm (0.20 mm × 6) is about the same as that of the 0.70 mm aluminum plate used as the reinforcement member of Case a3, but the load at 2 mm stroke of Case a4 to Case a9 is smaller than that of Case a3, and the tensile stiffness is poor. On the other hand, Case a12 to Case a20 using CFRP with fiber directions in two or three directions is the same as Case a4 to Case a9 in satisfying formula (1), but the load at 2 mm stroke of Case a12 to Case a20 is larger than that of Case a3 to Case a9, and the tensile stiffness is improved. According to the results, it can be seen that when at least one of the multiple FRP layers has a fiber direction different from that of the other layers, and when the ratio of the layers having a fiber direction angle difference of 30° or more in the multiple FRP layers is more than 15% of all the layers, and when the curved plate is joined with a reinforcing member satisfying formula (1), the tensile stiffness of the curved plate member is improved. In particular, in Case a12 to a20, the tensile stiffness is improved compared to Case a3 using an aluminum plate that is conducive to lightweighting. That is, the tensile stiffness of the curved plate member of Case a12 to a20 as an inventive example is excellent in mass efficiency, and it is possible to achieve both tensile stiffness and lightweighting at a high level.

[0109] In addition, the results of CASE b1 to b10 and CASE c1 to c10, which have different shape indexes K from CASE a1 to a20, also show that when at least one layer has a fiber direction different from other layers, the proportion of layers with an angle difference of 30° or more in the fiber direction among multiple FRP layers is 15% or more of all layers, and when formula (1) is satisfied, the tensile stiffness of the curved plate member is improved. In particular, in CASE b5 to b10, which are inventive examples, the tensile stiffness is improved compared to CASE b1, which uses an aluminum plate that is advantageous in weight reduction. In addition, in CASE c5, c9, and c10, which are inventive examples, the tensile stiffness is improved compared to CASE c1, which uses an aluminum plate that is advantageous in weight reduction. Therefore, the curved plate members of CASE b5 to b10 and CASE c5, c9, and c10 are also structures with excellent mass efficiency in tensile stiffness, similar to the aforementioned CASE a12 to a20. That is, the curved plate member of the present invention is a member that can achieve both high tensile rigidity and light weight regardless of the shape index K of the curved plate.

[0110] The size (area) of the reinforcing member of Case a13 and Case a20 is different from each other. Specifically, in Case a13, as in the other embodiments except Case a20, the reinforcing member is joined to an area of ​​100% of the area of ​​the curved plate, and in Case a20, the reinforcing member is joined to an area of ​​80% of the area of ​​the curved plate. The tensile stiffness of Case a13 and Case a20 was evaluated under the same conditions except the size of the reinforcing member, but the load was a higher value at a stroke of 2 mm. According to this result, even when the reinforcing member is not joined to the entire surface of the curved plate, the effect of improving the tensile stiffness can be fully obtained.

[0111] In the above Table 1, the layer structure when CFRP is used as a reinforcing member is set to 6 layers, but the case of a 4-layer structure is also Fig. 9 The tensile stiffness was evaluated by the method of . The evaluation results are shown in Table 2 below.

[0112] [Table 2]

[0113]

[0114] As shown in Table 2, even in the case of a 4-layer structure, at least one layer has a fiber direction different from that of the other layers, and among the multiple FRP layers, the proportion of the layers with an angle difference of 30° or more in the fiber direction is 15% or more of all the layers, and when formula (1) is satisfied, the tensile stiffness is also improved. That is, from the viewpoint of obtaining the effect of improving the tensile stiffness of the present invention, the total number of the multiple FRP layers is not particularly limited.

[0115] It should be noted that as a member made of FRP, there is a material in which fibers in two or more directions are woven into one layer of FRP (so-called cross fabric), but for the cross fabric, the use of Fig. 9 The tensile stiffness was evaluated by the method and the results showed that the improvement effect of tensile stiffness was small.

[0116] Industrial Applicability

[0117] The present invention can be used as a door outer panel, a roof panel, an engine hood, a fender or a side outer panel of an automobile.

[0118] Description of Reference Numerals

[0119] 1. curved plate member; 2. curved plate; 2a. surface of the curved plate on the load input side; 2b. surface of the curved plate on the side opposite to the load input side; 3. reinforcing member; 3a. 0° orientation layer; 3b. 90° orientation layer; 3c. 45° orientation layer; 3d. -45° orientation layer; 10. pressure head; T C , the center of plate thickness of the reinforcement component.

Claims

1. A curved panel component, comprising: a curved plate made of metal, wherein at least a portion of the curved plate has a curvature; and A reinforcing member, which is joined to one side of the curved plate having a curvature, and is composed of a plurality of FRP layers containing continuous fibers, Each of the plurality of FRP layers is composed of one fiber direction, At least one of the plurality of FRP layers has a fiber direction different from that of the other layers, In the plurality of FRP layers, the proportion of layers having a fiber direction angle difference of 30° or more is 15% or more of all layers, Regarding the fiber directions of each FRP layer of the reinforcing member joined to the curved plate, the following formula (1) is satisfied when the 0° direction component and the 90° direction component are calculated using trigonometric functions, respectively, wherein the maximum principal curvature direction of the surface having curvature of the curved plate is defined as the 0° direction, and the direction orthogonal to the 0° direction is defined as the 90° direction, 580×K≤(A×4+B) / (C+D) (1) A: The 0° direction component of the FRP layer outside the plate thickness center of the reinforcing member B: The 0° direction component of the FRP layer located inside the plate thickness center of the reinforcing member C: the 0° direction component in all the layers of the plurality of FRP layers D: the 90° direction component in all the layers of the plurality of FRP layers K: 1 / the radius of curvature in the 0° direction, in mm.

2. The curved panel member according to claim 1, wherein: The reinforcing member is joined to more than 70% of the area of ​​the curved plate.

3. The curved panel member according to claim 1, wherein: The reinforcing member is joined to the entire surface of the curved plate.

4. The curved panel member according to claim 1, wherein: The plate thickness of the reinforcing member is 2.0 times or more the plate thickness of the curved plate.

5. The curved panel member according to claim 1, wherein: The curved panel is a hood or a roof panel of a car, The reinforcing member is joined to the lower surface of the curved plate.

6. The curved panel member according to claim 1, wherein: The curved panel is a fender, a door outer panel or a side outer panel of a car, The reinforcing member is joined to the surface of the curved panel on the vehicle interior side.

7. The curved panel member according to claim 1, wherein: The curved plate is a steel plate having a pressure of 440 MPa or more.

8. The curved panel member according to any one of claims 1 to 7, wherein: The FRP is CFRP.

9. The curved plate member according to any one of claims 1 to 7, wherein: The FRP is GFRP.

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