Honeycomb Core

Abstract

To provide a honeycomb core capable of suppressing deformation of a honeycomb core caused by input of load in a direction vertical to a thickness direction of the honeycomb core when the honeycomb core is arranged along a curved surface of a part to be installed.SOLUTION: There is provided a honeycomb core in at least part of which a contour shape of each of a plurality of cells which are defined by cell walls is of a concave X-shape in a cross section orthogonal to a thickness direction. Each of a plurality of oblique wall parts which are provided on the cell walls is folded along 2n second ridge lines which are linear and extend in the thickness direction of the honeycomb core. In the concave X-shape of each cell, an interior angle at each apex from a second peak to the (n+1)th peak as counted from an end apex which is positioned at an end part of the concave X-shape in a ribbon direction is a reentrant angle, and an interior angle at each apex from the (n+2)th peak to the (2n+2)th peak is a convex angle, where X: 8n+2k (n is a natural number, and k is 2 or 3).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a honeycomb core. [Background technology]

[0002] Patent Document 1 discloses a method for manufacturing a flexible honeycomb core, in which a strip-shaped foil material made of a composite material combining metal fibers and resin is passed between corrugating rollers and corrugated into a corrugated sheet having continuously folded triangular wave-shaped irregularities by utilizing the plastic deformation of the metal fibers, an adhesive is applied to every other peak or valley of the corrugated sheet and the corrugated sheet is cut into predetermined lengths, a plurality of the corrugated sheets are stacked in a positional relationship in which the positions where the adhesive is applied are alternately shifted between the upper and lower corrugated sheets, and the corrugated sheets are bonded together by heating and pressurizing, and then the corrugated sheets bonded in this way are expanded by applying a tensile force in the stacking direction, thereby obtaining a flexible honeycomb core consisting of a planar assembly of hollow columnar cells in which each cell wall is bent midway and each cell is rounded and roughly convex. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3107473 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above flexible core, the cell walls are bent so that each cell has a rounded, generally convex shape. A honeycomb core having cell walls bent in such a curved manner may be deformed when a load is applied in a direction perpendicular to the thickness direction of the honeycomb core.

[0005] An object of the present invention is to suppress deformation of a honeycomb core caused by input of a load perpendicular to the thickness direction of the honeycomb core when the honeycomb core is placed along the curved surface of an installation portion. [Means for solving the problem]

[0006] In at least a part of a honeycomb core according to one embodiment of the present invention, the contour shape of each of the multiple cells defined by the cell walls in a cross section perpendicular to the thickness direction is a concave X-shaped polygon. Each of the multiple oblique wall portions of the cell walls is folded along 2n linear second ridge lines extending in the thickness direction of the honeycomb core. In each of the multiple cells, the interior angles of the 2nd to n+1th vertices counting from the end vertex located at the end of the concave X-shaped polygon in the ribbon direction are concave angles, and the interior angles of the n+2nd to 2n+2nd vertices are convex angles, where X: 8n+2k (n is a natural number, k is 2 or 3). Effect of the Invention

[0007] According to the present invention, when a honeycomb core is placed along the curved surface of the installation portion, deformation of the honeycomb core caused by a load being input in a direction perpendicular to the thickness direction of the honeycomb core can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a plan view showing at least a portion of a honeycomb core according to an embodiment, illustrating a state in which the honeycomb core is placed on a planar surface. [Diagram 2] 2 is a perspective view showing cell walls and cells which constitute a part of the honeycomb core shown in FIG. 1. [Diagram 3] 1 is a plan view showing a state in which a honeycomb core according to an embodiment is arranged along a curved surface of a mounting portion. FIG. [Figure 4] FIG. 4 is a perspective view illustrating a part of the honeycomb core shown in FIG. 3, for explaining the function of the honeycomb core according to the embodiment. [Diagram 5]FIG. 13 is a diagram for explaining the function of the honeycomb core according to the embodiment, and is a schematic partial perspective view showing a portion of the cell wall when the honeycomb core is placed along the curved surface of the installation portion. [Figure 6] FIG. 11 is a plan view showing at least a part of a honeycomb core according to a modified example of the embodiment, illustrating a state in which the honeycomb core is placed on a planar surface. [Figure 7] FIG. 7 is a perspective view showing cell walls and cells which form a part of the honeycomb core shown in FIG. 6. [Figure 8] FIG. 13 is a diagram for explaining the function of a honeycomb core relating to a modified example of an embodiment, and is an oblique view showing a portion of the honeycomb core when the honeycomb core is placed along the curved surface of the installation portion. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the honeycomb core according to the embodiment will be described with reference to the drawings. In each drawing, W indicates the width direction of the honeycomb core, L indicates the ribbon direction of the honeycomb core, and T indicates the thickness direction of the honeycomb core. The diagonal direction of the honeycomb core refers to a direction perpendicular to the thickness direction of the honeycomb core and intersecting both the width direction and the ribbon direction of the honeycomb core. The lower surface of the honeycomb core refers to a side surface on one side of the honeycomb core in the thickness direction, which is the surface on the side of the part to be installed. The upper surface of the honeycomb core refers to a side surface on the other side of the honeycomb core in the thickness direction, which is the surface opposite to the side of the part to be installed. In the following description, the width direction of the honeycomb core, the ribbon direction of the honeycomb core, the thickness direction of the honeycomb core, and the diagonal direction of the honeycomb core are simply referred to as the "width direction", "ribbon direction", "thickness direction", and "diagonal direction", respectively. Elements having the same function are given the same symbols, and duplicated descriptions are omitted.

[0010] As shown in FIGS. 1 and 2 or 6 and 7, a honeycomb core 1, 1A according to the embodiment or its modified example is composed of a cell wall 10 and a plurality of cells 20 partitioned by the cell wall 10.

[0011] The honeycomb core 1, 1A can be configured as a sandwich panel by bonding a skin plate (not shown) to one side and the other side in the thickness direction of the honeycomb core 1, 1A using a bonding means such as an adhesive. The skin plate is a plate-shaped member having a flat or curved surface for bonding the honeycomb core 1, 1A, and is made of, for example, a metal such as aluminum or fiber reinforced plastic (FRP). As the fiber reinforced plastic, carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), aramid fiber reinforced plastic (AFRP), etc. can be used. In addition, the sandwich panel using the honeycomb core 1, 1A according to the embodiment can be used as a panel that constitutes, for example, the roof, floor, hood, or wheel house of an automobile (not shown). The dimensions of the honeycomb core 1, 1A in the ribbon direction, width direction, or thickness direction can be appropriately determined depending on the application of the honeycomb core 1, 1A.

[0012] The cell walls 10 are members extending in the ribbon direction and the width direction and having a predetermined height in the thickness direction of the honeycomb core 1, 1A. The cell walls 10 are folded at multiple locations along linear creases (ridge lines) extending in the thickness direction of the honeycomb core 1, 1A, and define multiple cells 20 that are open in the thickness direction and have a columnar space with a concave X-shaped cross section perpendicular to the thickness direction. In other words, the cell walls 10 partition the multiple cells 20 by forming a closed cross section perpendicular to the thickness direction of the honeycomb core 1, 1A. In the example shown in FIG. 1 and FIG. 6, a total of 13 cells 20 are defined by the cell walls 10, but this is not limited thereto, and less than 13 or 14 or more cells 20 may be defined.

[0013] The cell wall 10 includes a plurality of oblique wall portions 15 that extend obliquely with respect to the ribbon direction between the first ridges 30 and divide two adjacent cells 20. In addition, each end of the plurality of oblique wall portions 15 is a first ridge 30 shared by at least three adjacent cells 20 among the plurality of cells 20. In the illustrated example, the first ridge 30 is a ridge of the cell wall 10 and is a ridge shared by three adjacent cells 20 among the plurality of cells 20.

[0014] Each of the multiple oblique wall portions 15 of the cell wall 10 is bent along 2n linear second ridge lines 40 (n is a natural number) extending in the thickness direction of the honeycomb core 1, 1A. The contour shape of each of the multiple cells 20 in a cross section perpendicular to the thickness direction of the honeycomb core 1, 1A (hereinafter simply referred to as the "contour shape") is a concave X-shaped polygon represented by X:8n+2k (k is 2 or 3).

[0015] Furthermore, the concave X-shaped polygon that is the contour shape of each of the multiple cells 20 has an end vertex 45 located at the end of the concave X-shaped polygon in the ribbon direction. Counting end vertex 45 as the 1st (counting from end vertex 45), the interior angles of the 2nd to n+1th vertices are concave angles, and the interior angles of the n+2nd to 2n+2nd vertices are convex angles. Note that "counting from" refers to a method of counting in which the starting point is counted as 1 and included in the total number.

[0016] In addition, in the concave X-shaped polygon that is the contour shape of each of the multiple cells 20, the length of the side between end vertex 45 and the n+1th vertex counting from end vertex 45 is shorter than the length of the side between the n+1th vertex and the n+2nd vertex counting from end vertex 45.

[0017] 1 and 2, the outline shape of each of the multiple cells 20 is a concave tetradecagon (n=1, k=3). Each of the multiple oblique wall portions 15 of the cell wall 10 is bent along two linear second ridge lines 40 extending in the thickness direction of the honeycomb core 1.

[0018] Each of the diagonal walls 15 has an end wall 15a extending between the first ridge 30 and the second ridge (turned portion 40a) of the second ridges 40 counting from the first ridge 30. An intermediate wall 15b is formed adjacent to the end wall 15a with the turned portion 40a in between. Thus, the turned portion 40a is a ridge that is a boundary between the end wall 15a and the intermediate wall 15b. The two end walls 15a that share the same first ridge 30 and face each other in the width direction form a protruding portion 18. The cell wall 10 further includes a plurality of joint walls 12 that extend in the ribbon direction and divide two adjacent cells 20 in the width direction. The end of each of the plurality of joint walls 12 in the ribbon direction is the first ridge.

[0019] The illustrated recessed tetradecagon has an end vertex 45 located at the end of the recessed tetradecagon in the ribbon direction. When viewed in the axial direction parallel to the thickness direction of the honeycomb core 1 (viewed in the thickness direction), the end vertex 45 is a vertex corresponding to the first ridge 30 constituting the protruding portion 18. The second and third vertices counting from the end vertex 45 are vertices corresponding to the folded-back portion 40a. The fourth vertex counting from the end vertex 45 is a vertex corresponding to a first ridge 30 that is different from the first ridge 30 corresponding to the end vertex 45, among the first ridges 30 that are the ends of the oblique wall portion 15.

[0020] Furthermore, in the concave tetragon that is the contour shape of each of the plurality of cells 20, the interior angle at the second vertex counting from end vertex 45 is a concave angle, and the interior angles at the third and fourth vertices are convex angles. Also, in the concave tetragon, the interior angle at end vertex 45 is a convex angle.

[0021] In the illustrated concave tetragon, the length of the side between end vertex 45 and the second vertex counting from end vertex 45 is shorter than the length of the side between the second vertex and the third vertex counting from end vertex 45. In other words, the end (bottom side) of intermediate wall portion 15b of cell wall 10 in the thickness direction of honeycomb core 1 is configured to be longer than the bottom side of end wall portion 15a.

[0022] Next, as an example of a case where n is 2 or more, a honeycomb core 1A according to a modified example of the embodiment will be described with reference to Fig. 6 and Fig. 7. In the honeycomb core 1A, the contour shape of each of the multiple cells 20 is a concave 22-sided polygon (n = 2, k = 3). Each of the multiple oblique wall portions 15 of the cell wall 10 is bent along four linear second ridge lines 40 extending in the thickness direction of the honeycomb core 1A.

[0023] Each of the diagonal wall portions 15 has an end wall portion 15a extending between the first ridge 30 and the third ridge (turned portion 40a) of the second ridges 40, counting from the first ridge 30. The end wall portion 15a also has a second ridge (middle turned portion 40b) of the second ridges 40, counting from the first ridge 30. Thus, the end wall portion 15a is composed of two rectangular regions, with the middle turned portion 40b as the boundary, and with the thickness direction of the honeycomb core 1A as the long direction. Also, an intermediate wall portion 15b is formed adjacent to the end wall portion 15a with the turned portion 40a sandwiched therebetween.

[0024] In the illustrated recessed 22-sided polygon, the third and fourth vertices counting from end vertex 45 correspond to folded portion 40a. The second and fifth vertices counting from end vertex 45 correspond to intermediate folded portion 40b. And the sixth vertex counting from end vertex 45 corresponds to a first edge 30 that is different from the first edge 30 that corresponds to end vertex 45, among the first edge lines 30 that are the end portions of oblique wall portion 15.

[0025] Furthermore, in the recessed 22-gon that is the contour shape of each of the plurality of cells 20, the interior angles at the second and third vertices counting from end vertex 45 are recessed angles, and the interior angles at the fourth to sixth vertices are convex angles. In addition, in the recessed 22-gon, the interior angle at end vertex 45 is a convex angle.

[0026] In the illustrated recessed 22-sided polygon, the length of the side between the end vertex 45 and the third vertex counting from the end vertex 45 is shorter than the length of the side between the third vertex and the fourth vertex counting from the end vertex 45. In other words, the end (bottom side) of the intermediate wall portion 15b of the cell wall 10 in the thickness direction of the honeycomb core 1A is configured to be longer than the bottom side of the end wall portion 15a.

[0027] Here, n=2, k=3, and the honeycomb core 1A in which the outline shape of each of the cells 20 is a concave 22-sided polygon has been exemplified, but n may be greater than 2. For example, when n=3, k=3, the outline shape of each of the cells 20 is a concave 30-sided polygon. In that case, each of the diagonal wall portions 15 has the fourth ridge line, counting from the first ridge line 30, among the second ridge lines 40 as the folded portion 40a. The end wall portion 15a has the second and third ridge lines, counting from the first ridge line 30, among the second ridge lines 40 as the intermediate folded portion 40b. In this way, when n is 2 or more, at least one intermediate folded portion 40b is formed in the end wall portion 15a.

[0028] In the examples shown in Figures 1 and 2 or 6 and 7, the cell wall 10 has a joint wall portion 12, but the joint wall portion 12 does not have to be formed. In such an embodiment, the first edge 30 is shared by four adjacent cells 20. In other words, the first edge is a edge shared by at least three adjacent cells out of the multiple cells 20. The contour shape of each of the multiple cells 20 defined by the cell wall 10 is a concave dodecagon (n=1, k=2) or a concave icosadogon (n=2, k=2).

[0029] (Manufacturing method) The honeycomb cores 1, 1A can be manufactured by a well-known method such as a corrugating method or an expansion method.

[0030] For example, in the corrugation method, a sheet material (base material) that is the material of the honeycomb core 1, 1A is passed between corrugated rollers, and a corrugated sheet having a ridge line corresponding to the first ridge line 30 or the second ridge line 40 is laminated in a direction corresponding to the width direction of the honeycomb core 1, 1A. Then, predetermined joints in the corrugated sheets, such as wall surfaces corresponding to the joint wall portion 12 of the cell wall 10, are joined together by a joining means such as an adhesive, to obtain the honeycomb core 1, 1A. The ridge line corresponding to the first ridge line 30 and the ridge line corresponding to the second ridge line 40 may be formed by using separate corrugated rollers. The honeycomb core 1, 1A obtained in this manner may be cut according to a desired thickness.

[0031] The sheet material may be, for example, a metal foil such as aluminum, a fiber reinforced plastic (FRP) sheet, paper, etc. The thickness of the sheet material is not particularly limited, but is, for example, about 0.01 to 0.5 mm.

[0032] Examples of materials for FRP sheets include aramid fiber reinforced plastics (AFRP), carbon fiber reinforced plastics (CFRP), glass fiber reinforced plastics (GFRP), etc. As the matrix resin for these, thermosetting resins such as epoxy resin, polyester resin, vinyl ester resin, phenolic resin, etc., and thermoplastic resins such as polypropylene resin, polyamide resin, polycarbonate resin, polyetherimide resin, etc. can be used.

[0033] The paper material may be kraft paper, mixed paper, etc. Examples of mixed paper include mixed paper made of synthetic fiber, carbon fiber, glass fiber, etc., and pulp fiber. The paper material may be imparted with water resistance by coating, impregnating, laminating, etc. with a synthetic resin such as an acrylic resin, a polyurethane resin, or a phenolic resin.

[0034] The thickness of the honeycomb core 1, 1A is not particularly limited and may be, for example, about 3 mm to 20 mm. The size of each of the plurality of cells 20 in the ribbon direction, width direction, or thickness direction may be appropriately determined depending on the application of the honeycomb core 1, 1A. For example, the size of each of the plurality of cells 20 in the width direction of the honeycomb core 1, 1A may be 3 mm to 30 mm.

[0035] As another manufacturing method, the honeycomb core 1, 1A may be constructed by forming a closed cross section in a direction perpendicular to the thickness direction of the honeycomb core 1, 1A in a shape corresponding to the outline shape of each of the plurality of cells 20, and arranging a plurality of cell walls 10 formed in a hollow concave X-shaped columnar shape extending in the thickness direction in parallel without gaps in the ribbon direction and width direction. In this case, at least one of the adjacent oblique wall portions 15 or the adjacent joint wall portions 12 of the cell walls 10 formed in a concave X-shaped columnar shape can be joined together by a joining means such as an adhesive.

[0036] Next, with reference to Figs. 3 to 5 and 8, the function and effect of the honeycomb core 1, 1A according to the embodiment when the honeycomb core 1, 1A is placed along the curved surface of the installation portion 100 will be described.

[0037] 3, when the honeycomb core 1 illustrated in Fig. 1 and Fig. 2 is placed along the curved surface of the mounting portion 100, a force acts on the lower surface side of the honeycomb core to shrink the cells 20, and a force acts on the upper surface side of the honeycomb core to expand the cells 20. Therefore, an area difference occurs between the cross section of the cells 20 on the upper surface side of the honeycomb core and the cross section of the cells 20 on the lower surface side of the honeycomb core. This causes a force to act to change the distance between the end wall portions 15a that constitute the protrusions 18.

[0038] In the example shown in FIG. 4, the left protrusion 18 in the figure is subjected to a force that reduces the distance between the end wall portions 15a constituting the protrusion 18 on the lower surface side of the honeycomb core, and a force that expands the distance between the end wall portions 15a constituting the protrusion 18 on the upper surface side of the honeycomb core. Therefore, the distance between the folded-back portions 40a on the lower surface side of the honeycomb core is reduced, and the distance between the folded-back portions 40a on the upper surface side of the honeycomb core is expanded. As a result, the folded-back portions 40a are inclined relative to the other ridge lines. Since each ridge line has rigidity, a torsional moment is input from each ridge line at the end to at least one of the end wall portions 15a and the intermediate wall portions 15b constituting the oblique wall portion 15. The wall surface to which such a torsional moment is input is folded while generating creases along the diagonal line, absorbing the torsional moment. For example, as in the intermediate wall portion 15b shown in Fig. 5, the torsional moment input from the folded portion 40a is absorbed by folding while forming a crease (ridge line) along a diagonal line 50. Note that Fig. 5 shows an example in which the ridge line is formed along the diagonal line 50 from the lower left to the upper right in the figure, but this is not limited thereto. The ridge line may be formed along a diagonal line from the lower right to the upper left in the figure, and which diagonal line the ridge line is formed along is appropriately determined depending on the bending method when the honeycomb core 1 is placed along the curved surface of the installation portion 100 and the relative positional relationship of each wall surface included in the cell wall 10.

[0039] Also, for example, a case where the honeycomb core 1A shown in Fig. 6 and Fig. 7 is arranged along the curved surface of the installation portion 100 will be described with reference to Fig. 8. In both the left and right protrusions 18 in Fig. 8, a force acts on the lower surface of the honeycomb core to reduce the distance between the end wall portions 15a constituting the protrusions 18, and a force acts on the upper surface of the honeycomb core to expand the distance. Therefore, the folded portion 40a forming the boundary between the protrusions 18 and the adjacent intermediate wall portion 15b is inclined relative to the other ridges. As a result, the intermediate wall portion 15b absorbs the torsional moment input from the folded portion 40a by folding while generating a ridge line along the diagonal line 50.

[0040] In this way, in the honeycomb core 1, 1A according to the embodiment, even when the honeycomb core 1, 1A is placed along the curved surface of the installation portion 100, the cell walls 10 are bent at the ridge lines to define each of the multiple cells 20. Therefore, compared to a case in which the cell walls 10 are bent at a curved surface to define each of the multiple cells 20, the rigidity (shear rigidity) of the honeycomb core 1, 1A against a load input in a direction perpendicular to its thickness direction can be increased.

[0041] In addition, the torsional moment generated in the diagonal wall portion 15 due to the honeycomb core 1, 1A being arranged along the curved surface of the installation portion 100 may be absorbed by the end wall portion 15a bending while generating a ridge line along its diagonal line 50.

[0042] (1) A honeycomb core 1, 1A according to an embodiment is a honeycomb core 1, 1A including a cell wall 10 and a plurality of cells 20 partitioned by the cell wall 10. In at least a part of the honeycomb core 1, 1A, the contour shape of each of the plurality of cells 20 defined by the cell wall 10 in a cross section perpendicular to the thickness direction of the honeycomb core 1, 1A is a concave X-shaped polygon. The cell wall 10 has a plurality of oblique wall portions 15 extending in an oblique direction with respect to the ribbon direction to partition two adjacent cells 20. The end is a first ridge 30 shared by at least three adjacent cells 20 among the plurality of cells 20, each of the plurality of oblique wall portions 15 is bent along 2n straight second ridges 40 extending in the thickness direction of the honeycomb core 1, 1A, and in the concave X-shaped polygon of each of the plurality of cells 20, the interior angles of the 2nd to n+1th vertices counting from the end vertex 45 located at the end of the concave X-shaped polygon in the ribbon direction are concave angles, and the interior angles of the n+2nd to 2n+2nd vertices are convex angles, where X: 8n+2k (n is a natural number, k is 2 or 3).

[0043] As a result, at least one of the wall surfaces constituting the oblique wall portion 15 absorbs the area difference between the cross section of the cells 20 on the upper surface side of the honeycomb core and the cross section of the cells 20 on the lower surface side of the honeycomb core, which occurs when the honeycomb core 1, 1A is placed along the curved surface of the installation portion 100, by folding while generating a ridge line along the diagonal line 50 of the wall surface. Therefore, the wall surface functions as a surface (strain absorbing surface) that absorbs the strain caused by placing the honeycomb core 1, 1A along the curved surface. Since the honeycomb core 1, 1A according to the embodiment has such a strain absorbing surface, it can be installed on the installation portion 100 having a curved surface.

[0044] Furthermore, when the honeycomb core 1, 1A is placed along the curved surface of the installation portion 100, the strain absorbing surface folds to form a crease (ridge line) extending in the diagonal direction. Therefore, the honeycomb core 1, 1A has rigidity (shear rigidity) against a load input in a direction perpendicular to its thickness direction, and a decrease in the shear rigidity of the honeycomb core 1, 1A can be suppressed. Therefore, when the honeycomb core 1, 1A is placed along the curved surface of the installation portion 100, deformation of the honeycomb core 1, 1A caused by a load input in a direction perpendicular to the thickness direction of the honeycomb core 1, 1A can be suppressed.

[0045] (2) In the honeycomb core 1 according to the embodiment, the recessed X-shaped polygon of each of the cells 20 is a recessed tetradecagon.

[0046] This makes it possible to form strain absorbing surfaces by bending the oblique wall portions 15 along the two second ridge lines 40. Therefore, the honeycomb core 1 can be easily constructed.

[0047] (3) In the honeycomb core 1A according to the modified example of the embodiment, the recessed X-shaped polygon of each of the plurality of cells 20 is a recessed X-shaped polygon where n is 2 or more.

[0048] As a result, at least one intermediate folded portion 40b is formed on the end wall portion 15a. By arranging the honeycomb core 1A along the curved surface of the installation portion 100, when a force acts to reduce or expand the interval between the cell walls 10 constituting the protruding portion 18, the interval between the folded portions 40a facing each other in the width direction of the honeycomb core 1A and the interval between the intermediate folded portions 40b can be changed. In other words, the force that changes the interval between the cell walls 10 constituting the protruding portion 18, which is generated by arranging the honeycomb core 1A along the curved surface of the installation portion 100, is shared and received by the folded portion 40a and at least one intermediate folded portion 40b. Therefore, as illustrated in FIG. 8, the interval between the cell walls 10 constituting the protruding portion 18 can be changed in stages. This allows the oblique wall portion 15 to be more flexibly aligned with the curved surface of the installation portion 100. As a result, it is possible to configure the honeycomb core 1A which can be more reliably installed on the installation portion 100 having a curved surface.

[0049] When n is 2, the oblique wall portion 15 can be bent along the four second ridge lines 40 to form a strain absorbing surface. This makes it possible to more easily configure the honeycomb core 1A, which can be more reliably installed on the installation portion 100 having a curved surface.

[0050] (4) In the honeycomb core 1, 1A according to the embodiment, in each of the concave X-shaped polygons of the multiple cells 20, the length of the side between the end vertex 45 and the n+1-th vertex counting from the end vertex 45 is shorter than the length of the side between the n+1-th vertex and the n+2-th vertex counting from the end vertex 45.

[0051] Therefore, the bottom side of the intermediate wall portion 15b is longer than the bottom side of the end wall portion 15a. Therefore, when the honeycomb core 1, 1A is placed along the curved surface of the installation portion 100, the intermediate wall portion 15b is more likely to break along the ridge line along the diagonal line 50. This makes it possible for the intermediate wall portion 15b to function more reliably as a strain absorbing surface. This makes it possible to configure the honeycomb core 1, 1A that can be more reliably installed on the installation portion 100 having a curved surface.

[0052] Further, honeycomb cores 1, 1A according to other embodiments will be described. In the following description of each embodiment, only configurations different from the preceding embodiment and modified examples (hereinafter, the preceding embodiment, etc.) will be described, and elements having the same functions as elements already described in the preceding embodiment, etc. will be denoted by the same reference numerals and description thereof will be omitted.

[0053] In the honeycomb core 1, 1A according to an embodiment, the length of all sides of the concave X-shaped contour of each of the cells 20 is the same. In other words, the bottom side of the intermediate wall portion 15b and the bottom side of the end wall portion 15a of the cell wall 10 of the honeycomb core 1, 1A are the same length. In addition, in the honeycomb core 1, 1A according to an embodiment, the length of the side between the end vertex 45 and the n+1th vertex counting from the end vertex 45 is longer than the length of the side between the n+1th vertex and the n+2th vertex counting from the end vertex 45. In other words, the bottom side of the intermediate wall portion 15b of the cell wall 10 of the honeycomb core 1, 1A is shorter than the bottom side of the end wall portion 15a.

[0054] According to the honeycomb core 1, 1A according to the other embodiment, at least the effects described in (1) to (3) above can be obtained, and the following effect can also be obtained.

[0055] (5) In the honeycomb core 1, 1A according to an embodiment, all sides of the concave X-shaped polygon of each of the cells 20 are the same length. Therefore, the bottom side of the intermediate wall portion 15b and the bottom side of the end wall portion 15a of the cell wall 10 of the honeycomb core are the same length. This allows the cell wall 10 to be formed by bending the base material at equal intervals. Therefore, the honeycomb core 1, 1A can be easily constructed.

[0056] (6) In the honeycomb core 1, 1A according to an embodiment, in each of the concave X-gons of the cells 20, the length of the side between the end vertex 45 and the n+1th vertex counting from the end vertex 45 is longer than the length of the side between the n+1th vertex and the n+2th vertex counting from the end vertex 45. Therefore, the bottom side of the end wall portion 15a of the cell wall 10 of the honeycomb core 1, 1A is configured to be longer than the bottom side of the intermediate wall portion 15b. As a result, when the honeycomb core 1, 1A is placed along the curved surface of the installation portion 100, the end wall portion 15a is more likely to bend along the ridge line along the diagonal line 50. Therefore, the end wall portion 15a can be more flexibly aligned with the curved surface of the installation portion 100. Therefore, it is possible to configure the honeycomb core 1, 1A that can be more reliably installed on the installation portion 100 having a curved surface.

[0057] In the above embodiment, the honeycomb cores 1, 1A are arranged along the curved surface of the mounting portion 100, but it goes without saying that they can also be mounted on a mounting portion having a flat surface. [Explanation of symbols]

[0058] 1,1A Honeycomb core 10 Cell Wall 15 Diagonal wall 20 cells 30 First Ridge 40 Second Ridge 45 End Vertex

Claims

1. A honeycomb core including a cell wall and a plurality of cells partitioned by the cell wall, wherein at least a portion of the honeycomb core is A contour shape of each of the plurality of cells defined by the cell walls in a cross section perpendicular to a thickness direction of the honeycomb core is a concave X-shaped polygon, The cell wall has a plurality of oblique wall portions extending in a direction oblique to the ribbon direction and dividing two adjacent cells, an end portion of each of the plurality of oblique wall portions is a first edge line shared by at least three adjacent cells among the plurality of cells, Each of the plurality of oblique wall portions is bent along 2n linear second ridge lines extending in a thickness direction of the honeycomb core, In the concave X-shaped shape of each of the plurality of cells, the interior angles of the 2nd to n+1th vertices, counting from an end vertex located at the end of the concave X-shaped shape in the ribbon direction, are concave angles, and the interior angles of the n+2th to 2n+2th vertices are convex angles. where X is 8n + 2k (n is a natural number of 2 or more, k is 2 or 3).

2. 2. The honeycomb core according to claim 1, wherein in the concave X-gon of each of the plurality of cells, the length of a side between the end vertex and the (n+1)th vertex counting from the end vertex is shorter than the length of a side between the (n+1)th vertex and the (n+2)th vertex counting from the end vertex.

3. 2. The honeycomb core according to claim 1, wherein all sides of the concave X-shaped portion of each of the plurality of cells have the same length.

4. 2. The honeycomb core according to claim 1, wherein in the concave X-shaped polygon of each of the plurality of cells, a length of a side existing between the end vertex and the (n+1)th vertex counting from the end vertex is longer than a length of a side between the (n+1)th vertex and the (n+2)th vertex counting from the end vertex.

5. A honeycomb core comprising a cell wall and a plurality of cells partitioned by the cell wall, wherein at least a portion of the honeycomb core is A contour shape of each of the plurality of cells defined by the cell walls in a cross section perpendicular to a thickness direction of the honeycomb core is a concave X-shaped polygon, The cell wall has a plurality of oblique wall portions extending in a direction oblique to the ribbon direction and dividing two adjacent cells, an end portion of each of the plurality of oblique wall portions is a first edge line shared by at least three adjacent cells among the plurality of cells, Each of the plurality of oblique wall portions is bent along 2n linear second ridge lines extending in a thickness direction of the honeycomb core, In the concave X-shaped polygon of each of the plurality of cells, the interior angles of the 2nd to n+1th vertices counting from an end vertex located at the end of the concave X-shaped polygon in the ribbon direction are concave angles, and the interior angles of the n+2nd to 2n+2nd vertices are convex angles, A honeycomb core, wherein all sides of the concave X-shaped portion of each of the plurality of cells have the same length. where X is 8n + 2k (n is a natural number, k is 2 or 3).

6. A honeycomb core comprising a cell wall and a plurality of cells partitioned by the cell wall, wherein at least a portion of the honeycomb core is A contour shape of each of the plurality of cells defined by the cell walls in a cross section perpendicular to a thickness direction of the honeycomb core is a concave X-shaped polygon, The cell wall has a plurality of oblique wall portions extending in a direction oblique to the ribbon direction and dividing two adjacent cells, an end portion of each of the plurality of oblique wall portions is a first edge line shared by at least three adjacent cells among the plurality of cells, Each of the plurality of oblique wall portions is bent along 2n linear second ridge lines extending in a thickness direction of the honeycomb core, In the concave X-shaped polygon of each of the plurality of cells, the interior angles of the 2nd to n+1th vertices counting from an end vertex located at the end of the concave X-shaped polygon in the ribbon direction are concave angles, and the interior angles of the n+2nd to 2n+2nd vertices are convex angles, a honeycomb core, wherein in the concave X-shaped shape of each of the plurality of cells, the length of a side between the end vertex and the (n+1)th vertex counting from the end vertex is longer than the length of a side between the (n+1)th vertex and the (n+2)th vertex counting from the end vertex. where X is 8n + 2k (n is a natural number, k is 2 or 3).

7. A honeycomb core as described in claim 5 or 6, wherein the concave X-gon of each of the plurality of cells is a concave tetradecagon.

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