Sandwich panel structure and method for manufacturing a sandwich panel structure

Abstract

This sandwich panel structure (1) comprises a plurality of split members (11). The split members (11) each comprise two sheets of a skin material (12) and a core material (13) disposed between the two sheets of the skin material (12). In a joining part (31) of the plurality of split members (11), a groove part (23), formed by thinning the skin material (12) in a range in which the outer surface of the core material (13) is not exposed, is present in the skin material (12). A patch member (21) is disposed in the groove part (23) via an adhesive (22). In a state in which the plurality of split members (11) are joined, the total thickness of the skin material (12), the adhesive (22), and the patch member (21) in the joining part (31) in the plate thickness direction, and the thickness of the skin material (12) in a non-joining part (32) in the plate thickness direction are continuous at the boundary between the joining part (31) and the non-joining part (32).

Description

Technical Field

[0001] The present disclosure relates to a sandwich panel structure and a method for manufacturing the sandwich panel structure.

Background Art

[0002] In communication and broadcasting satellites, there is an increasing demand for higher functionality, and a large-power satellite bus is required for mounting high-function communication devices that consume a large amount of power. To realize a large-power satellite bus, it is desirable to increase the size of the solar panel. Here, the solar panel is a structure composed of a sandwich panel-made substrate and a plurality of solar cells mounted thereon. To increase the size of the solar panel, it is important to increase the size of the sandwich panel structure. In a sandwich panel structure, it is necessary to integrate the core material and the skin material. Therefore, in the prior art, there has been a problem that the upper limit of the size increase is limited according to the size of the molding furnace. Therefore, a method of realizing a large sandwich panel structure by joining a plurality of divided sandwich panel structures in a post-process has been considered. By dividing the sandwich panel structure into a plurality within the size constraint of the molding furnace, it is possible to increase the size of the sandwich panel structure without being restricted by the size constraint of the molding furnace. Patent Document 1 discloses a sandwich structure and a method for manufacturing the same. The sandwich structure disclosed in Patent Document 1 has a core material and FRP (Fiber Reinforced Plastics) skin plates arranged on both sides thereof, and in the sandwich structure in which the ends are butted and joined, an FRP connecting layer extending over the surfaces of both ends is provided, and a layer containing a resin diffusion medium is provided between the butted end faces.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004] In the technology disclosed in Patent Document 1, it is possible to firmly join multiple divided sandwich structures by providing an FRP connecting layer that extends across the surfaces of both ends at the joint where the sandwich structures are butt-joined. However, in the sandwich structure disclosed in Patent Document 1, since an FRP connecting layer is provided on the surface of the FRP skin plate, the thickness of the FRP layer consisting of the FRP skin plate and the FRP connecting layer at the joint is thicker than at the non-jointed area. The technology disclosed in Patent Document 1 has the problem that this uneven thickness causes uneven thermal deformation and a decrease in strength at the connection between the joint and the non-jointed area. A specific example of this connection is the boundary between the area where the FRP connecting layer 6 exists and the area where it does not exist, as shown in Figures 5 to 7 of Patent Document 1. The present disclosure aims to provide a sandwich panel structure in which, in a sandwich panel structure divided into multiple sections, the thickness in the thickness direction of the jointed section and the thickness in the thickness direction of the non-jointed section are continuous at the boundary between the jointed section and the non-jointed section. [Means for solving the problem]

[0005] The sandwich panel structure relating to this disclosure is In a sandwich panel structure consisting of multiple divided members, where each of the multiple divided members is designated as a first divided member, and the first divided member is joined to a second divided member among the multiple divided members, The first divided member consists of two skin materials and a core material disposed between the two skin materials, with one of the two skin materials designated as the first target skin material. In the joint portion of the first divided member that is joined to the second divided member, the first target skin material has a groove formed by reducing the thickness of the first target skin material in a range in which the outer surface of the core material is not exposed. In the state in which the first divided member and the second divided member are joined together, A patch member is placed in the groove portion via adhesive. At the boundary between the joint and the non-joint portion, which is a part of the first divided member other than the joint, the total thickness in the thickness direction of the first target skin material, the adhesive, and the patch member at the joint is continuous with the thickness in the thickness direction of the first target skin material at the non-joint portion. [Effects of the Invention]

[0006] According to this disclosure, when the first divided member and the second divided member are joined, at the boundary between the joined portion and the non-joined portion, the total thickness in the thickness direction of the first target skin material, adhesive, and patch member at the joined portion is continuous with the thickness direction of the first target skin material at the non-joined portion. Therefore, according to this disclosure, it is possible to provide a sandwich panel structure in which, in a sandwich panel structure divided into multiple parts, the thickness in the thickness direction of the joined portion and the thickness in the thickness direction of the non-joined portion are continuous at the boundary between the joined portion and the non-joined portion. [Brief explanation of the drawing]

[0007] [Figure 1] A perspective view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 1. [Figure 2] A cross-sectional view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 1. [Figure 3] An enlarged cross-sectional view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 1. [Figure 4] A side view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 2. [Figure 5]An enlarged cross-sectional view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 2. [Figure 6] An enlarged cross-sectional view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 3. [Figure 7] A cross-sectional enlarged view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 4. [Figure 8] A top view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 5. [Figure 9] This is an explanatory diagram showing a specific example of the manufacturing method of the sandwich panel structure 1 according to Embodiment 6, where (a) is a diagram illustrating the member molding process, (b) is a diagram illustrating the groove / patch member processing process, (c) is a diagram illustrating the arrangement process, and (d) is a diagram illustrating the integration process. [Modes for carrying out the invention]

[0008] In the description and drawings of the embodiments, the same elements and corresponding elements are denoted by the same reference numeral. The descriptions of elements denoted by the same reference numeral are omitted or simplified as appropriate.

[0009] Embodiment 1. This embodiment will now be described in detail with reference to the drawings.

[0010] ***Explanation of the structure*** Figure 1 is a perspective view showing an example of the configuration of a sandwich panel structure 1 according to Embodiment 1. The sandwich panel structure 1 consists of a plurality of divided members 11, a patch member 21, and an adhesive 22.

[0011] Each segmented member 11 consists of two skin materials 12 and a core material 13 positioned between the two skin materials 12. In the dividing member 11, a groove for arranging the patch member 21 is formed by thinning the thickness of the skin material 12 within a range where the outer surface of the core material 13 is not exposed. The thickness of the member is the length of the member in the plate thickness direction. The plate thickness direction is the normal direction of the upper surface of the sandwich panel structure 1. The upper surface of the sandwich panel structure 1 is a surface composed of the skin material 12 and the patch member 21, and is a surface where the core material 13 is not exposed. Adjacent two dividing members 11 are joined through the adhesive 22 and the patch member 21, whereby the sandwich panel structure 1 is integrally formed.

[0012] Hereinafter, the configuration of the joint portion 31 will be described in detail with specific examples. FIG. 2 is a cross-sectional view showing a configuration example of the sandwich panel structure 1. The cross-section is a surface having the same normal line as the normal line of the surface including the joint portion 31 among the side surfaces of the sandwich panel structure 1, and is a surface as shown in FIG. 2. Further, a direction orthogonal to both the normal line of the cross-section and the plate thickness direction of the sandwich panel structure 1 is referred to as the longitudinal direction. Regarding the region of the sandwich panel structure 1 when viewed along the longitudinal direction, as shown in FIG. 2, a region where the patch member 21 exists is referred to as the joint portion 31, and a region other than the joint portion 31 is referred to as the non-joint portion 32. The joint portion 31 is a portion that joins with other dividing members 11. FIG. 2 shows a flat sandwich panel structure having a uniform thickness as an example of the sandwich panel structure 1. The sandwich panel structure 1 shown in FIG. 2 is composed of two dividing members 11 divided by a surface having the longitudinal direction as the normal line.

[0013] The skin material 12 has a groove portion 23 for fitting the patch member 21 at the joint portion 31. At the joint portion 31, the groove portion 23 is formed by thinning the thickness of the skin material 12 within a range where the surface of the core material 13 is not exposed when viewing the sandwich panel structure 1 from the plate thickness direction. The skin material The patch member 21 is a member having a rectangular cross-section. Each patch member 21 is joined to each of the two skin materials 12 by being fitted into grooves 23 provided in each of the two skin materials 12 via adhesive 22. As specific examples, aluminum alloy (A5052) can be used for the skin material 12 and the patch member 21, respectively.

[0014] At the joint 31, the core material 13 constituting each divided member 11 is joined to the opposing core material 13 via an adhesive 22. Specifically, an aluminum alloy honeycomb core can be used as the core material 13, and a film-type adhesive (REDUX® 312, manufactured by Hexel) can be used as the adhesive 22. The thickness of the core material 13 does not change at the boundary between the joint 31 and the non-joint 32. The core material 13 is located between the two skin materials 12 throughout its entire longitudinal direction. The core material 13 is joined to the skin materials 12 via adhesive 22. At the joint 31, the skin material 12 constituting each divided member 11 is joined to the core material 13 or the skin material 12 of the opposing divided member 11 via adhesive 22 on a surface that does not come into contact with the patch member 21.

[0015] Figure 3 is a diagram showing an example of the configuration of the sandwich panel structure 1, and is an enlarged cross-sectional view of one side of the sandwich panel structure 1. In Figure 3, the thickness of the patch member 21 in the thickness direction is set to be uniform with the difference between the depth of the groove 23 in the thickness direction and the thickness of the adhesive 22 in the thickness direction. As a specific example, when the thickness of the patch member 21 is 500 μm and the thickness of the adhesive 22 is 50 μm, the depth of the groove 23 is 550 μm. In this example, by making the thickness of the patch member 21 uniform with the difference between the depth of the groove 23 and the thickness of the adhesive 22, the height of the surface of the skin material 12 in the thickness direction at the non-jointed portion 32 and the height of the surface of the patch member 21 in the thickness direction at the jointed portion 31 become the same. Therefore, smoothness on the surface of the sandwich panel structure 1 can be ensured. Furthermore, since the skin material 12 in the non-jointed portion 32 and the combined configuration of the skin material 12 and patch member 21 in the jointed portion 31 are similar, relatively high homogeneity can be obtained between the non-jointed portion 32 and the jointed portion 31.

[0016] In other words, in this embodiment, when each of the multiple dividing members 11 is designated as a first dividing member, and the first dividing member is joined to a second dividing member among the multiple dividing members 11, the following holds true. The sandwich panel structure 1, as a specific example, consists of a first dividing member, a second dividing member, a patch member 21, and an adhesive 22. Each of the first and second divided members consists of two skin materials 12 and a core material 13 positioned between the two skin materials 12. Here, one of the two skin materials 12 of the first divided member is designated as the first target skin material. In the joint portion 31 of the first divided member that is joined to the second divided member, the first target skin material has grooves 23 formed by reducing the thickness of the first target skin material in a range where the outer surface of the core material 13 is not exposed. In the state where the first divided member and the second divided member are joined, a patch member 21 is placed in the groove 23 via adhesive 22. In this state, at the boundary between the joined portion 31 and the non-joined portion 32, the total thickness in the thickness direction of the first target skin material, adhesive 22, and patch member 21 in the joined portion 31 is continuous with the thickness in the thickness direction of the first target skin material in the non-joined portion 32. The non-joined portion 32 is the part of the first divided member other than the joined portion 31. As a specific example, the depth of the groove 23 in the thickness direction is the same as the sum of the thickness of the patch member 21 in the thickness direction and the thickness of the adhesive 22 in the thickness direction. The adhesive 22 is placed between the first dividing member and the patch member 21. Furthermore, the material of the first target skin material and the material of the patch member 21 may be the same.

[0017] Although a sandwich panel structure 1 with a uniform thickness and a flat shape has been described, the thickness of the sandwich panel structure 1 does not have to be uniform, and the shape does not have to be flat. As a specific example, the sandwich panel structure 1 may have a curved or cylindrical shape, and the thickness may vary from place to place. Furthermore, although a sandwich panel structure 1 consisting of two dividing members 11 has been described, the sandwich panel structure 1 may consist of three or more dividing members 11. Furthermore, although the dividing surface of the dividing member 11 was described as a surface with the longitudinal direction as its normal, the dividing surface may also be a surface with a direction other than that which is arbitrarily set as its normal. For example, the dividing surface may be a surface with a direction normal to the plane of the paper, or an arbitrary direction within the plane where the longitudinal direction and the plane of the paper intersect. Furthermore, although the use of aluminum alloy as the material for the skin material 12 and patch member 21 has been described, the material does not have to be aluminum alloy. Specific examples of the material for at least one of the skin material 12 and patch member 21 include metals such as stainless steel alloy or magnesium alloy, fiber-reinforced plastics (FRP) such as carbon fiber reinforced plastics (CFRP) or glass fiber reinforced plastics (GFRP), ceramics such as C / C (carbon fiber reinforced carbon) or SiC, wood, or plastic. Furthermore, although we have described the case where both the skin material 12 and the patch member 21 are made of aluminum alloy, that is, where both materials are the same, the materials of the skin material 12 and the patch member 21 may be different from each other. Furthermore, although the case where the patch member 21 is present on both skin materials 12 has been described, the patch member 21 may be present on only one of the skin materials 12. Furthermore, although the case where the core material 13 is a honeycomb core has been described, the material does not have to be a honeycomb core. The material may be a foam core, a flexible core, a paper core, etc. Furthermore, although the case in which the thickness of the skin portion does not change between the joint portion 31 and the non-joint portion 32 has been described, the thickness of the skin portion may change continuously between the joint portion 31 and the non-joint portion 32. In other words, when the first divided member and the second divided member are joined, the thickness of the skin portion in the thickness direction may change continuously along the longitudinal direction of the sandwich panel structure 1 from the joint portion 31 to the non-joint portion 32. The skin portion consists of the first target skin material, the adhesive 22 placed between the first target skin material and the patch member 21, and the patch member 21 as a whole. Furthermore, although the case in which the thickness of the skin material 12 changes discontinuously between the joint 31 and the non-joint 32 has been described, the thickness of the skin material 12 may also change continuously between the joint 31 and the non-joint 32. In the case in which the thickness of the skin material 12 changes continuously between the joint 31 and the non-joint 32, as a specific example, a slope is formed near the boundary between the joint 31 and the non-joint 32 of the first target skin material, and the thickness of the first target skin material in the thickness direction changes tapered along the longitudinal direction near the boundary. Furthermore, although the use of a film-type adhesive as adhesive 22 has been described, adhesive 22 does not have to be a film-type adhesive. Adhesive 22 may be a one-component liquid adhesive, a two-component liquid adhesive, or a foaming adhesive, etc. Furthermore, although the case where the adhesive 22 consists of only one type of adhesive has been described, the type of adhesive 22 may be changed depending on the location where the adhesive 22 is used. As a specific example, it is preferable to use a foam adhesive when joining core materials 13 having voids, such as honeycomb cores. Furthermore, although the case where the cross-section of the patch member 21 is rectangular has been described, the cross-section of the patch member 21 does not have to be rectangular. The patch member 21 may have a taper in whole or in part. The cross-sectional shape of the patch member 21 may be any shape that matches the shape of the groove 23, and specific examples include a triangle or a trapezoid. Furthermore, although the case where the ratio of the thickness of the adhesive 22 to the thickness of the patch member 21 is 1 / 10 has been described, this ratio does not have to be 1 / 10. Specific examples of this ratio include 10, 52, 1, 1 / 2, 1 / 5, 1 / 20, 1 / 50, or 1 / 100. It is preferable that the ratio be small, and more preferably less than 1.

[0018] ***Explanation of the effects of Embodiment 1*** According to this embodiment, the divided member 11 comprises a groove 23 formed therein and a patch member 21 placed in the groove 23, and the patch member 21 and the groove 23 are joined via an adhesive 22. The groove 23 is formed by thinning the skin material 12 of the divided member 11. Therefore, at the boundary between the joined portion 31 and the non-joined portion 32, the total thickness of the patch member 21, skin material 12, and adhesive 22 in the joined portion 31 can be made the same as the thickness of the skin material 12 in the non-joined portion 32. Therefore, according to this embodiment, a member in which the joined portion 31 and the non-joined portion 32 are homogeneous can be realized. Furthermore, according to this embodiment, a uniform structure can be obtained at the joint 31 of the sandwich panel structure 1. Therefore, according to this embodiment, stress concentration and thermal deformation can be suppressed.

[0019] Embodiment 2. The following will explain the differences from the previously described embodiment, primarily with reference to the drawings.

[0020] ***Explanation of the structure*** Figure 4 is a side view showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 2. The sandwich panel structure 1 has a skin-to-skin fitting portion 33. The skin-to-skin mating portion 33 is a portion with an uneven shape formed on two opposing skin materials 12 such that the two skin materials 12 fit together at the joint portion 31. The two opposing skin materials 12 are the two skin materials 12 that are joined together.

[0021] The configuration of the joint 31 will be explained in detail below with specific examples. Figure 5 is a diagram showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 2, and is an enlarged cross-sectional view of one side of the sandwich panel structure 1. With regard to Figure 5, the case in which fiber-reinforced plastic (FRP) is used as the skin material 12 will be explained. Each skin material 12 is composed of six layers, from FRP layer 14a to FRP layer 14f. Each FRP layer 14 consists of carbon fiber T800S (manufactured by Toray Industries, Inc.) and epoxy resin.

[0022] In Figure 5, for the left-side divided member, only FRP layers 14a to 14c are shown among FRP layers 14a to 14f as FRP layer 14. The left-side divided member is the divided member 11 located on the left side in the figure. Each of the FRP layers 14a and 14b of the left-side split member does not reach the split surface 34 of the core in the longitudinal direction, that is, it does not reach the end of the core material 13 of the left-side split member. Therefore, in the left-side split member, the FRP layers 14a and 14b form a recess in the skin-to-skin fitting portion 33.

[0023] On the other hand, in Figure 5, each of the FRP layers 14a and 14b of the right-side split member protrudes from the split surface 34 of the core in the longitudinal direction, extending beyond the end of the core material 13 of the right-side split member to a position opposite each of the FRP layers 14a and 14b of the left-side split member in the longitudinal direction. Therefore, in the right-side split member, the protrusions in the skin-skin fitting portion 33 are formed by the FRP layers 14a and 14b. The right-side split member is the split member 11 located on the right side in the figure.

[0024] Furthermore, the FRP layer 14c is relatively longer in the left-side dividing member and relatively shorter in the right-side dividing member. Therefore, a convex portion is formed by the FRP layer 14c in the left-side dividing member, and a concave portion is formed by the FRP layer 14c in the right-side dividing member. The FRP layer 14c of the left-side dividing member and the FRP layer 14c of the right-side dividing member are opposite each other. The right-side dividing member may be considered as the first dividing member, and the left-side dividing member as the second dividing member. The respective longitudinal lengths of the protrusions of the left-side split member and the right-side split member in the skin-to-skin fitting portion 33 are 20 mm each. The FRP layer 14c forms the lower surface of the groove 23 into which the patch member 21 is fitted. FRP layers 14d to 14f constitute the side surface of the groove 23. In this example, the sandwich panel structure 1 has a skin-to-skin fitting portion 33 in which the FRP layer 14a and FRP layer 14c fit together, thereby enabling the two divided members 11 to be joined relatively firmly.

[0025] In other words, the following holds true in this embodiment. At the joint 31, a recess is formed in the first target skin material. At the portion of the second divided member that joins with the first divided member (joint 31), a protrusion is formed in the second target skin material. The second target skin material is the skin material 12 provided on the second divided member, and is the skin material 12 that faces the first target skin material when the first divided member and the second divided member are joined together. When the first divided member and the second divided member are joined together, the recess and the protrusion are fitted together. The recess is formed on the joint surface where the first and second divided members are joined. The depth direction of the recess is in the longitudinal direction of the sandwich panel structure. The protrusion is formed on the joint surface. The height direction of the protrusion is in the longitudinal direction. The first target skin material and the second target skin material are each made of fiber-reinforced plastic. The recessed portion and the convex portion are each composed of a layer of fiber-reinforced plastic.

[0026] In this embodiment, we have described a case in which carbon fiber is used as the reinforcing fiber and epoxy resin is used as the base resin for fiber-reinforced plastic. However, other reinforcing fibers and base resins may be used to achieve the desired properties. As reinforcing fibers, specific examples include glass fibers, aluminum oxide fibers, boron fibers, silicon carbide fibers, aramid fibers, Kevlar® fibers, Dyneema® fibers, Zylon® fibers, or hemp fibers. Furthermore, the fiber form may be short fibers, long fibers, or fabrics or braids using them. As a base resin, specific examples may include unsaturated polyester resin, vinyl ester resin, phenolic resin, cyanate ester resin, polyvinyl acetate, polycarbonate, polyacetal, polyphenylene oxide, polyphenylene sulfide, polyarylate, polyester, polyamide-imide, polyimide, or polyetherimide. Furthermore, although the explanation described a case where the length of each of the left and right protrusions in the longitudinal direction is 20 mm, this length does not have to be 20 mm. For example, this length may be 10 mm, 50 mm, 100 mm, or 200 mm. Furthermore, although the case where the lengths of the protrusions of the left-side dividing member and the right-side dividing member are the same has been described, these lengths may be different for the left-side dividing member and the right-side dividing member. Furthermore, although we have described the case where the number of protrusions on the left-side dividing member and the number of protrusions on the right-side dividing member are both one, the number of protrusions on each may be two or more.

[0027] ***Explanation of the effects of Embodiment 2*** According to this embodiment, the skin materials 12 are joined together in a fitted state at the joint 31 of the sandwich panel structure 1. Therefore, according to this embodiment, the divided members 11 can be joined together more firmly.

[0028] Embodiment 3. The following will explain the differences from the previously described embodiment, primarily with reference to the drawings.

[0029] ***Explanation of the structure*** Figure 6 is a diagram showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 3, and is an enlarged cross-sectional view of one side of the sandwich panel structure 1. Each of the skin material 12 and patch member 21 is made of FRP and consists of multiple layers. Between the left-side dividing member and the right-side dividing member, each opposing layer has the same fiber orientation. The fiber content (Vf) of the skin material 12 is lower than the fiber content of the patch member 21. In other words, the fiber content of the patch member 21 is higher than the fiber content of the first target skin material.

[0030] The configuration of the joint 31 will be explained in detail below with specific examples. In Figure 6, the patch member 21 has three layers, from FRP layer 14d to FRP layer 14f, and each skin material 12 has six layers, from FRP layer 14a to FRP layer 14f. The thickness of the skin material 12 at the non-jointed portion 32 is 600 μm. The thickness of the patch member 21 is 270 μm, and the thickness of the adhesive 22 is 30 μm. The FRP layers 14d to 14f of the patch member 21 and the FRP layers 14d to 14f of the skin material 12 are opposite each other. Each of the opposing layers has the same fibers, resin, and fiber orientation.

[0031] On the other hand, the fiber content of each of the FRP layers 14d to 14f of the patch member 21 is 56%. Also, the Vf of each of the FRP layers 14a to 14f of the skin material 12 is 50%. Therefore, at the joint 31, the Vf when the FRP layers 14a to 14c of the skin material 12, the adhesive 22, and the FRP layers 14d to 14f of the patch member 21 are considered as a single unit is 50%. Consequently, the Vf of the joint 31 matches the Vf of the skin material 12 at the non-jointed area 32. Therefore, the homogeneity between the joint 31 and the non-jointed area 32 is high. In other words, in this embodiment, when the first divided member and the second divided member are joined together, the material constituting the skin portion is continuous along the longitudinal direction at the boundary between the joined portion 31 and the unjoined portion 32.

[0032] ***Explanation of the effects of Embodiment 3*** According to this embodiment, each opposing layer has the same fiber orientation, and the fiber content is the same between the joined portion 31 and the unjointed portion 32. Therefore, according to this embodiment, relatively high homogeneity can be obtained between the joined portion 31 and the unjointed portion 32 of the sandwich panel structure 1.

[0033] Embodiment 4. The following will explain the differences from the previously described embodiment, primarily with reference to the drawings.

[0034] ***Explanation of the structure*** Figure 7 is a diagram showing an example of the configuration of the sandwich panel structure 1 according to Embodiment 4, and is an enlarged cross-sectional view of one side of the sandwich panel structure 1. In Embodiment 4, the protruding convex portion of the skin-skin fitting portion 33 of the skin material 12 is configured so that it does not warp due to thermal deformation. The convex portion according to this embodiment does not warp beyond the standard value in the thickness direction due to normal thermal deformation.

[0035] The configuration of the joint 31 will be explained in detail below with specific examples. In Figure 7, each skin material 12 is composed of seven layers of the same material, from FRP layer 14a to FRP layer 14g, with the FRP layers 14a to 14d of the left-side divided member's skin material 12 facing each other. The FRP layers 14e to 14g of the skin material 12 form the side surface of the groove 23.

[0036] Regarding the FRP layers 14a to 14c, the right-side splitting member is longer than the left-side splitting member. Therefore, a protrusion of the skin-skin fitting portion 33 is formed in the right-side splitting member. Furthermore, the FRP layers 14a to 14c are symmetrically laminated. More specifically, with the longitudinal direction as the 0° direction, the FRP layers 14a to 14c have an orientation of [0 / 90 / 0]. On the other hand, the FRP layer 14d is longer on the left-side split member than on the right-side split member. Therefore, a protrusion of the skin-skin fitting portion 33 is formed on the left-side split member. Also, the FRP layer 14d is a single layer of [0]. Here, the single layer can be considered as a symmetrical lamination. In other words, the layer of the protrusion is a symmetrical lamination. In symmetrical lamination of the same material, deformation (warping) in the thickness direction does not occur. Therefore, when the divided member 11 is divided, no warping occurs in the right FRP layer 14a to FRP layer 14c and the left FRP layer 14d, which correspond to the protrusions of the skin-skin fitting portion 33. Consequently, assembly of the divided member 11 becomes relatively easy. Note that the expression "no warping occurs" may also refer to the amount of warping being below a certain value. Furthermore, the patch member 21 has a symmetrical [0 / 90 / 0] lamination pattern that matches the orientation of the FRP layer 14e to the FRP layer 14g. Therefore, no warping occurs in the patch member 21.

[0037] The configuration of the FRP layer 14 corresponding to the protrusion of the skin-skin fitting portion 33 and the configuration of the patch member 21 have been described in terms of the case where the same material is used for each layer and symmetric lamination is performed. However, the materials of each layer do not all have to be the same, and symmetric lamination is not required; that is, the layers of the protrusion may be asymmetrically laminated. When non-identical materials are used for each layer, warping will not occur if both the material and orientation are symmetrically laminated. Furthermore, it is also possible to create a configuration that does not warp by using non-identical materials for each layer, laminating them so that the orientation is asymmetrical, and designing it so that the bending component of the thermal expansion coefficient is small. As a specific example, the configuration can be such that the warping of the protrusion in the thickness direction caused by thermal changes during molding is 1 / 1, 1 / 2, 1 / 5, 1 / 10, or 1 / 20 or less of the thickness of one FRP layer. Each value corresponds to the warping standard value. Note that when the protrusion is a single layer, it can be considered as symmetrically laminated with the center of the layer as the neutral axis. Furthermore, although we have described a case in which neither the FRP layer 14 corresponding to the protrusion of the skin-skin fitting portion 33 nor the patch member 21 warps, it is also possible that only a portion of the portion does not warp. In addition, a configuration in which warping does not occur in the thick plate portion with high rigidity is preferable.

[0038] ***Explanation of the effects of Embodiment 4*** According to this embodiment, due to the improved fiber orientation, warping does not occur at the joint 31 of the sandwich panel structure 1 when the dividing member 11 is divided in the skin material 12, the patch member 21, or both. Therefore, according to this embodiment, the assembly of the sandwich panel structure 1 can be made relatively easy.

[0039] Embodiment 5. The following will explain the differences from the previously described embodiment, primarily with reference to the drawings.

[0040] ***Explanation of the structure*** Figure 8 is a top view showing an example of the configuration of a sandwich panel structure 1 according to Embodiment 5. As shown in Figure 8, in Embodiment 5, the skin material 12 and the patch member 21 have interlocking grooves that allow them to fit together. More specifically, in Figure 8, each of the skin material 12 and the patch member 21 has a skin-patch fitting portion 35 that allows the skin material 12 and the patch member 21 to fit together in a dovetail joint shape. The patch member 21 has the same shape in the thickness direction. In this example, the skin material 12 and the patch member 21 have a skin-patch fitting portion 35 that fits together, which allows for a stronger bond between the skin material 12 and the patch member 21.

[0041] In other words, the following holds true in this embodiment. The first target skin material has a first uneven surface formed thereon. The patch member 21 has a second uneven surface formed thereon. In the target plane, which is a plane normalized to the plate thickness direction, the shape of the first uneven surface is uneven, and the shape of the second uneven surface is uneven. When the first divided member and the second divided member are joined together, the first uneven surface and the second uneven surface are fitted together. Furthermore, on the target plane, at least a portion of the edges of the first protrusions does not align with the longitudinal direction, and at least a portion of the edges of the second protrusions does not align with the longitudinal direction. Therefore, when the first protrusions and the second protrusions are fitted together, the first target skin material and the patch member 21 will not separate even if they are pulled in opposite directions along the longitudinal direction.

[0042] Although the description has focused on the case where the shape of the skin-patch fitting portion 35 is a dovetail joint, the shape does not have to be a dovetail joint. For example, the shape may be a sickle joint or a dovetail joint. Furthermore, although the case in which the patch members 21 have the same shape in the thickness direction has been described, the patch members 21 may have different shapes in the thickness direction.

[0043] ***Explanation of the effects of Embodiment 5*** According to this embodiment, the skin material 12 and the patch member 21 are joined in a fitted state at the joint 31. Therefore, according to this embodiment, the bond between the skin material 12 and the patch member 21 can be made stronger.

[0044] Embodiment 6. The following will explain the differences from the previously described embodiment, primarily with reference to the drawings.

[0045] ***Explanation of Manufacturing Method*** A specific example of the manufacturing method for the sandwich panel structure 1 according to this disclosure will be described with reference to Figure 9. This manufacturing method is a sandwich panel structure manufacturing method. Figure 9 is an explanatory diagram showing a specific example of the manufacturing method for the sandwich panel structure 1 according to Embodiment 6. Steps 1 to 4 produce a sandwich panel structure 1 consisting of divided members 11, patch members 21, and adhesive 22 placed between the members. Here, we will describe the case where there are a total of two divided members 11, and each of the skin material 12 and patch members 21 is made of FRP.

[0046] (Process 1: Component molding process) In this process, the divided member 11 and the patch member 21 are manufactured separately. Figure 9(a) shows a cross-sectional view after each member has been manufactured separately. The divided member 11 is manufactured by first creating the skin material 12, and then joining the skin material 12 and the core material 13 together using an adhesive 22 to create a single unit. Furthermore, when manufacturing the skin material 12, the general shape of the groove portion 23 is formed by making the number of FRP layers in the joint portion 31 less than the number of FRP layers in the non-joint portion 32. After this process, the surfaces of the skin material 12 and patch member 21 are relatively smooth, as they reflect the surface condition of the mold. The component molding process also involves molding the first divided component, the second divided component, and the patch component 21.

[0047] (Process 2: Groove and patch material processing process) In this process, machining is performed on the groove 23 and the patch member 21. Figure 9(b) shows a cross-sectional view after the groove machining is completed. In the groove and patch material processing process, two types of processing are performed: shape processing and surface condition processing. In the shaping process, the groove portion 23, which was roughly shaped in step 1, is machined to obtain the desired shape in order to address resin leakage and shape deviations caused by curing shrinkage deformation. In the surface treatment process, the adhesion between the groove 23 and the patch member 21 is improved by grinding the respective surfaces of the groove 23 and the patch member 21 using abrasive paper. The process of forming the general shape of the groove 23 and the process of processing the groove 23 in this process are collectively called the groove processing process. The groove processing process is also a process of processing the first groove by reducing the thickness in the thickness direction of the first target skin material to the extent that the outer surface of the core material 13 of the first divided member is not exposed, and processing the second groove by reducing the thickness in the thickness direction of the second target skin material to the extent that the outer surface of the core material 13 of the second divided member is not exposed. The depth of the first groove is a depth determined according to the sum of the thickness in the thickness direction of the patch member 21 and the thickness in the thickness direction of the adhesive 22 placed between the first groove and the patch member 21. The depth of the second groove is a depth determined according to the sum of the thickness in the thickness direction of the patch member 21 and the thickness in the thickness direction of the adhesive 22 placed between the second groove and the patch member 21.

[0048] (Process 3: Placement process) In this process, each component constituting the sandwich panel structure 1 is placed in the desired position. Figure 9(c) shows a cross-sectional view during the placement process. The arrows in Figure 9(c) indicate the direction of movement of each component. The placement process will be described below in order. First, the adhesive 22 is placed on the surfaces where the divided members 11 come into contact with each other. Next, each divided member 11 is slid in the longitudinal direction to butt together. At this time, if there is a skin-to-skin fitting portion 33, the members are positioned so that the left and right concave and concave shapes fit together. Here, since the divided members 11 are slid in the longitudinal direction, it is not necessary to lift the divided members 11. Next, adhesive 22 is placed in the groove 23 formed by the two divided members 11. Next, each patch member 21 is positioned from the thickness direction of the sandwich panel structure 1. When a skin-patch fitting portion 35 is present, the patch members 21 are positioned so that their concave and concave shapes fit together. The arrangement step is also a step of arranging the first divided member, the second divided member, the patch member 21, and the adhesive 22 according to the shape of the sandwich panel structure 1. In the arrangement step, the first divided member and the second divided member may be joined together by moving each of them in the direction normal to the joint surface between the first divided member and the second divided member in the state in which the first divided member and the second divided member are joined.

[0049] (Process 4: Integration process) In this process, the individual components constituting the sandwich panel structure 1, which were positioned at the desired locations during the placement process, are integrated. Figure 9(d) shows a cross-sectional view after integration. In the integration process, the adhesive 22 at the joint 31 is cured to integrate the components that make up the sandwich panel structure 1. One curing method involves covering the surface of the joint 31 with a rubber heater (not shown) and heating the rubber heater by applying electricity to it to heat and cure the adhesive 22. When heating with a rubber heater, placing a weight (not shown) on a surface of the rubber heater other than the surface in contact with the sandwich panel structure 1 can reduce the gap between the patch member 21 and the skin material 12, thereby achieving a stronger bond. The integration process also involves integrating the first divided member, the second divided member, and the patch member 21 by curing the adhesive 22.

[0050] In step 1, the case was described in which the divided member 11 is manufactured by first producing the skin material 12 and then integrating the skin material 12 and the core material 13 using an adhesive 22. However, the skin material 12 may be placed on the core material 13, and the molding of the skin material 12 and the integration of the skin material 12 and the core material 13 may be performed simultaneously. In this case, the adhesive 22 may be placed between the skin material 12 and the core material 13. Furthermore, although the case in which the general shape of the groove 23 is formed in step 1 has been described, it is not necessary to form the general shape of the groove 23 in step 1. If the general shape of the groove 23 is not formed in step 1, the groove 23 will be formed in the shape processing in step 2. Furthermore, while we have described the case of grinding using abrasive paper as a surface treatment, this treatment does not necessarily have to be done using abrasive paper. As specific examples of surface treatment, grinding using abrasive cloth, wire brush, or sandblasting may also be performed. In addition, in surface treatment, chemical treatment, primer treatment, ultraviolet irradiation treatment, or plasma treatment may be performed instead of or in addition to grinding. Furthermore, although step 4 describes the case of heating using a rubber heater, heating may be done without using a rubber heater. Specific heating methods include using an IR (infrared) heater, a heat gun, or an oven. Furthermore, although the use of weights to reduce the gap between the patch member 21 and the skin material 12 was described in step 4, the gap may also be reduced using methods that do not involve weights. Specific examples of such methods include clamping using a vise or localized bagging.

[0051] ***Explanation of the effects of Embodiment 6*** According to this embodiment, the sandwich panel structure 1 can be assembled relatively easily.

[0052] ***Other Embodiments*** The aforementioned embodiments can be freely combined, any component of each embodiment can be modified, or any component can be omitted in each embodiment. Furthermore, the embodiments are not limited to those shown in Embodiments 1 to 6, and various modifications can be made as needed. [Explanation of symbols]

[0053] 1 Sandwich panel structure, 11 Divided member, 12 Skin material, 13 Core material, 14, 14a, 14b, 14c, 14d, 14e, 14f, 14g FRP layers, 21 Patch member, 22 Adhesive, 23 Groove, 31 Joint, 32 Non-joint, 33 Skin-to-skin fitting, 34 Divided surface, 35 Skin-to-patch fitting.

Claims

1. In a sandwich panel structure consisting of multiple divided members, where each of the multiple divided members is designated as a first divided member, and the first divided member is joined to a second divided member among the multiple divided members, The first divided member consists of two skin materials and a core material disposed between the two skin materials, with one of the two skin materials designated as the first target skin material. In the joint portion of the first divided member that is joined to the second divided member, the first target skin material has a groove formed by reducing the thickness of the first target skin material in a range in which the outer surface of the core material is not exposed. In the state in which the first divided member and the second divided member are joined together, A patch member is placed in the groove portion via adhesive. A sandwich panel structure in which, at the boundary between the joint and the non-joint portion, which is a part of the first divided member other than the joint, the total thickness in the thickness direction of the first target skin material, the adhesive, and the patch member at the joint is the same as or continuously changes the thickness in the thickness direction of the first target skin material at the non-joint portion.

2. The depth of the groove in the thickness direction is the same as the sum of the thickness of the patch member in the thickness direction and the thickness of the adhesive in the thickness direction. The sandwich panel structure according to claim 1, wherein the adhesive is disposed between the first divided member and the patch member.

3. The sandwich panel structure according to claim 1 or 2, wherein at least one of the first target skin material and the patch member is made of fiber-reinforced plastic.

4. Each of the patch member and the first target skin material is made of fiber-reinforced plastic. The sandwich panel structure according to claim 1 or 2, wherein the fiber content of the patch member is higher than the fiber content of the first target skin material.

5. In the aforementioned joint, a recess is formed in the first target skin material. In the portion of the second divided member that is joined to the first divided member, the skin material of the second divided member, which is the skin material facing the first target skin material when the first divided member and the second divided member are joined, has a protrusion formed on it. The sandwich panel structure according to claim 1 or 2, wherein the recess and the protrusion are fitted together when the first dividing member and the second dividing member are joined together.

6. The recess is formed on the joining surface, which is the surface where the first dividing member and the second dividing member are joined. The depth direction of the recess is the longitudinal direction of the sandwich panel structure. The aforementioned protrusion is formed on the joining surface, The sandwich panel structure according to claim 5, wherein the height direction of the protrusion is the longitudinal direction.

7. Each of the first target skin material and the second target skin material is made of fiber-reinforced plastic. The sandwich panel structure according to claim 5, wherein each of the recesses and protrusions is composed of a layer of fiber-reinforced plastic.

8. Each of the first target skin material and the second target skin material is made of fiber-reinforced plastic. The sandwich panel structure according to claim 5, wherein the layers of the convex portion are symmetrically stacked.

9. Each of the first target skin material and the second target skin material is made of fiber-reinforced plastic. The materials of each layer of the aforementioned protrusion are not all the same. The aforementioned convex layer is an asymmetrically stacked layer, The sandwich panel structure according to claim 5, wherein the convex portion does not warp beyond a reference value in the thickness direction due to thermal deformation.

10. The first target skin material has a first uneven portion formed thereon. The patch member has a second uneven portion formed therein. In the target plane, which is a plane normalized to the plate thickness direction, the shape of the first uneven portion is an uneven shape, and the shape of the second uneven portion is an uneven shape. The sandwich panel structure according to claim 1 or 2, wherein, in a state in which the first divided member and the second divided member are joined together, the first protrusion and the second protrusion are fitted together.

11. In the aforementioned target plane, at least a portion of the edges of the first uneven portion does not align with the longitudinal direction of the sandwich panel structure, and at least a portion of the edges of the second uneven portion does not align with the longitudinal direction. The sandwich panel structure according to claim 10, wherein, in a state in which the first protrusion and the second protrusion and the first protrusion and the second protrusion and the first target skin material and the patch member are fitted together, the first target skin material and the patch member do not separate even when pulled in opposite directions along the longitudinal direction.

12. The sandwich panel structure according to claim 1 or 2, wherein the material of the first target skin material and the material of the patch member are the same.

13. The sandwich panel structure according to claim 1 or 2, wherein the thickness of the first target skin material in the thickness direction changes continuously along the longitudinal direction of the sandwich panel structure from the joint to the non-joint.

14. The sandwich panel structure according to claim 1 or 2, wherein at the boundary between the joint and the non-joint, the material constituting the first target skin material is continuous along the longitudinal direction of the sandwich panel structure.

15. A sandwich panel structure manufacturing method comprising a first divided member and a second divided member, each consisting of two skin materials and a core material disposed between the two skin materials, a patch member, and an adhesive, wherein the sandwich panel structure is manufactured, When one of the two skin materials of the first divided member is designated as the first target skin material, and the skin material of the second divided member that faces the first target skin material when the first divided member and the second divided member are joined together is designated as the second target skin material, A member molding step for molding the first divided member, the second divided member, and the patch member, A grooving process comprising: processing a first groove by reducing the thickness of the first target skin material in the thickness direction within a range where the outer surface of the core material of the first divided member is not exposed; and processing a second groove by reducing the thickness of the second target skin material in the thickness direction within a range where the outer surface of the core material of the second divided member is not exposed; Arrangement step of arranging the first divided member, the second divided member, the patch member, and the adhesive according to the shape of the sandwich panel structure, An integration step is performed to integrate the first divided member, the second divided member, and the patch member by curing the adhesive. A method for manufacturing a sandwich panel structure comprising: The depth of the first groove is determined according to the sum of the thickness of the patch member in the thickness direction and the thickness of the adhesive disposed between the first groove and the patch member in the thickness direction. A method for manufacturing a sandwich panel structure, wherein the depth of the second groove is determined according to the sum of the thickness of the patch member in the thickness direction and the thickness of the adhesive disposed between the second groove and the patch member in the thickness direction.

16. A method for manufacturing a sandwich panel structure according to claim 15, wherein in the arrangement step, the first divided member and the second divided member are moved in the direction normal to the joining surface between the first divided member and the second divided member in the state in which the first divided member and the second divided member are joined, thereby joining the first divided member and the second divided member.

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