Polygonal core structure

Abstract

The present invention provides a polygonal core structure that can suppress delamination at the joint surfaces between corrugated plates. [Solution] The polygonal core structure 10 comprises a core body 20 and a reinforcing plate 30 that engages with the core body. The core body has a plurality of corrugated plates 21 with a continuous uneven shape, and has a plurality of polygonal cells 23 formed by joining the joint surfaces 22 where adjacent corrugated plates overlap. The reinforcing plate engages with the core body, spanning adjacent cells in the tension direction W of the core body.

Description

Technical Field

[0007] , ,

[0001] The present invention relates to a polygonal core structure.

Background Art

[0002] As an energy absorption component, a polygonal core structure such as a honeycomb structure is used (see Patent Document 1).

[0003] Patent Document 1 discloses a honeycomb structure in which a plurality of corrugated sheets are combined. The convex portions of the corrugated sheets are joined by welding or the like. In the honeycomb structure, a space smaller than one side of the cell is formed between a pair of double-wall structure partition walls arranged opposite to each other.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] [[ID=3!]]When a compressive load is applied to the honeycomb structure and the joint surface between the corrugated plates is once peeled off, a moment is applied to the joints in a direction in which they are pulled apart from each other. For this reason, the peeling of the joint surface is promoted, and the honeycomb structure collapses without being crushed. As a result, there is a problem that the energy absorption becomes an inefficient failure mode and the energy absorption efficiency decreases.

[0006] Therefore, an object of the present invention is to provide a polygonal core structure capable of suppressing the peeling of the joint surface between the corrugated plates.

Means for Solving the Problems

[0007] One aspect of the present invention for achieving the above objective is a polygonal core structure having a core body and a reinforcing plate that engages with the core body. The core body has a plurality of corrugated plates having a continuous uneven shape, and has a plurality of polygonal cells formed by joining the joint surfaces where adjacent corrugated plates overlap. The reinforcing plate engages with the core body, straddling the cells adjacent to the core body in the direction of extension of the core body. [Effects of the Invention]

[0008] According to the present invention, a polygonal core structure can be provided that can suppress delamination of the joint surfaces between corrugated plates. [Brief explanation of the drawing]

[0009] [Figure 1] This is a plan view showing the polygonal core structure of the embodiment. [Figure 2] This is a schematic diagram used to explain the operation of a polygonal core structure. [Figure 3] This is a schematic diagram used to explain the operation of a polygonal core structure. [Figure 4] This is a plan view showing the polygonal core structure of Modification Example 1. [Figure 5] This is a perspective view showing the corrugated plate that constitutes the core body of the polygonal core structure of Modification Example 1. [Figure 6] This is a perspective view showing the reinforcing plate of the polygonal core structure in Modification Example 1. [Figure 7] This is a plan view showing the polygonal core structure of modified example 2. [Figure 8] This is a perspective view showing the polygonal core structure of modified example 2. [Figure 9] This is a plan view showing the polygonal core structure of modified example 3. [Figure 10] This is a plan view showing the polygonal core structure of modified example 4. [Figure 11] This is a plan view showing the polygonal core structure of modified example 5. [Figure 12] Figure 11 is an enlarged view showing the area enclosed by the dashed line. [Figure 13]It is a plan view showing the polygonal core structure of Modification 6. [Figure 14] It is a perspective view showing the main parts of the reinforcing plate and other reinforcing plates of Modification 6. [Figure 15] It is a plan view showing the polygonal core structure of Modification 7. [Figure 16] It is a plan view showing the polygonal core structure of Modification 8. [Figure 17] It is a perspective view showing the slit of the polygonal core structure of Modification 9.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The embodiments shown here are examples for embodying the technical idea of the present invention and do not limit the present invention. Therefore, all other possible embodiments, examples, operation techniques, etc. that can be conceived by those skilled in the art without departing from the gist of the present invention are included in the scope and gist of the present invention, and are included in the invention described in the claims and its equivalent scope.

[0011] In addition, the drawings attached to this specification may be schematically expressed with changes from the actual objects in terms of scale, vertical and horizontal dimension ratios, shapes, etc. for the convenience of illustration and easy understanding, but this is only an example and does not limit the interpretation of the present invention.

[0012] In this specification, ordinal numbers such as "first", "second", etc. may be attached. However, unless there is a special explanation regarding these ordinal numbers, they are attached for the convenience of explanation to identify the components and do not specify a number or order.

[0013] <Embodiment> FIG. 1 is a plan view showing the polygonal core structure 10. FIGS. 2 and 3 are schematic views used to explain the operation of the polygonal core structure 10. The L-axis attached to the figure indicates the ribbon direction L, and the W-axis indicates the extension direction W. [[ID=​As shown in Figure 1, the polygonal core structure 10 of the embodiment includes a core body 20 and a reinforcing plate 30 that engages with the core body 20. The core body 20 has a plurality of corrugated plates 21 with a continuous uneven shape. The core body 20 has a plurality of polygonal cells 23 formed by joining the joint surfaces 22 where adjacent corrugated plates 21 overlap. The reinforcing plate 30 engages with the core body 20 by spanning adjacent cells 23 in the tension direction W of the core body 20.

[0015] In the polygonal core structure 10 of this embodiment, the core body 20 has a cylindrical shape including a plurality of planar portions extending along the axial direction (the direction perpendicular to the plane of the paper in Figure 1). When viewed in a cross-section perpendicular to the axial direction of the core body 20, the cells 23 have a regular hexagonal contour shape. A polygonal core structure 10 with this contour shape is generally referred to as a honeycomb core structure. The corner portions of the corrugated plate 21 (such as the portions indicated by reference numeral 24 in Figure 1) may have a rounded shape. The forming materials for the core body 20 and the reinforcing plate 30 are not particularly limited and can be molded from aluminum, paper, resin, FRP material, etc. The joining surfaces 22 of the corrugated plate 21 are joined together by adhesive or welding. The engagement structure between the core body 20 and the reinforcing plate 30 is not particularly limited. For example, examples include a structure in which slits formed in the core body 20 and slits formed in the reinforcing plate 30 are fitted together and engaged, a structure in which they are engaged by adhesive or welding, and a structure in which they are engaged by fastening components such as bolts and clips.

[0016] As shown in Figure 2, when a crushing input is applied to the core body 20 of the polygonal core structure 10 in the axial direction (direction perpendicular to the plane of the paper), an input in the direction of delamination is applied to the joint surfaces 22 of the corrugated plate 21 (see white arrow). However, as shown in Figure 3, the reinforcing plate 30 that engages with the core body 20 biases the core body 20 with a force that opposes the delamination of the joint surfaces 22 (see hatched arrow). As a result, delamination of the joint surfaces 22 is suppressed. Consequently, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is improved.

[0017] The reinforcing plate 30 engages with the core body 20 at a location other than the joint surface 22. Delamination between the joint surfaces 22 occurs starting from the end 22a of the joint surface 22. For this reason, it is preferable for the reinforcing plate 30 to engage with the core body 20 at a location continuous with the end 22a of the joint surface 22. However, the present invention does not exclude the possibility of engaging the reinforcing plate 30 with the core body 20 at the joint surface 22.

[0018] The reinforcing plate 30 is a flat plate that extends in the axial direction of the core body 20 and engages with the core body 20 in the axial direction of the core body 20. However, it is not limited to this case, and the reinforcing plate 30, which is made of a flat plate, may also be engaged with the axial end face of the core body 20, spanning the cells 23 adjacent to the core body 20 in the tension direction W of the core body 20.

[0019] <Example 1> Figure 4 is a plan view showing the polygonal core structure 10 of the modified example 1. Figure 5 is a perspective view showing the corrugated plate 21 that constitutes the core body 20, and Figure 6 is a perspective view showing the reinforcing plate 30.

[0020] The polygonal core structure 10 of the modified example 1 has an engagement structure between the core body 20 and the reinforcing plate 30, in which slits are fitted together and engaged. The other configurations are the same as in the embodiment.

[0021] As shown in Figures 4, 5, and 6, the core body 20 of the polygonal core structure 10 of Modified Example 1 has a first slit 41 in at least one partition wall 25 that is different from the joint surface 22 among the multiple partition walls that demarcate the cell 23. The reinforcing plate 30 has a second slit 42 at a position corresponding to the first slit 41. The core body 20 and the reinforcing plate 30 engage with each other through the first slit 41 and the second slit 42.

[0022] As shown in Figure 5, the first slit 41 of the core body 20 has an end opening 41a formed at the lower edge in the figure, and a groove 41b that extends upward continuous with the end opening 41a. The groove 41b extends to about half the height of the corrugated plate 21. The second slit 42 of the reinforcing plate 30 has an end opening 42a formed at the upper edge in the figure, and a groove 42b that extends downward continuous with the end opening 42a. The groove 42b extends to about half the height of the reinforcing plate 30.

[0023] With this configuration, the first slit 41 and the second slit 42 fit together, causing the reinforcing plate 30 to firmly engage with the core body 20. As a result, even when crushing forces are applied to the core body 20, a force is biased from the reinforcing plate 30 against delamination of the joint surfaces 22. This suppresses delamination of the joint surfaces 22. Consequently, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is enhanced.

[0024] The reinforcing plate 30 has a surface 31 that is in contact with the partition wall 25 in which the first slit 41 is formed.

[0025] With this configuration, the partition wall 25 of the core body 20 and the surface 31 of the reinforcing plate 30 overlap, thereby improving the rigidity of the partition wall 25 of the core body 20. As a result, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is enhanced.

[0026] As shown in Figure 4, the partition wall 25 of the core body 20 and the surface 31 of the reinforcing plate 30 can be bonded together via adhesive 50 (shown in gray). With this configuration, the structure can withstand shear forces, thereby improving the joint strength between the partition wall 25 of the core body 20 and the surface 31 of the reinforcing plate 30. As a result, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is enhanced.

[0027] In the modified example 1, the reinforcing plate 30 has a continuous corrugated shape similar to the corrugated plate 21, following the partition wall 25 of the core body 20 (see Figures 4 and 6). The reinforcing plate 30 forming the second slit 42 is not limited to this shape.

[0028] As shown in the embodiment in Figure 1, the reinforcing plate 30 may have a surface extending parallel to the tensioning direction W.

[0029] In this case, the core body 20 of the polygonal core structure 10 has a first slit 41 in a partition wall 25 that is different from the joint surface 22 among the multiple partition walls that demarcate the cell 23. The reinforcing plate 30 has a second slit 42 at a position corresponding to the first slit 41. The core body 20 and the reinforcing plate 30 engage with each other through the first slit 41 and the second slit 42.

[0030] With this configuration, since the reinforcing plate 30 is a flat plate, the reinforcing plate 30 can be easily molded, and molding costs can be reduced. Also, because the reinforcing plate 30 is a flat plate, the resistance to tensile load in the direction of extension of the flat plate is improved. Furthermore, since the reinforcing plate 30 extends parallel to the tension direction W, a triangular column section 26 is formed by the two adjacent partition walls 25 of the core body 20 and the reinforcing plate 30. When a compressive load is applied to the core body 20 and buckling failure occurs, the buckling pitch of the small space of the column section 26 is smaller than the buckling pitch of the surface forming the core body 20. This improves the energy absorption efficiency at the time of buckling failure. As a result, the strength and rigidity of the polygonal core structure 10 are improved and the energy absorption efficiency is improved compared to a simple hexagonal honeycomb structure.

[0031] Adhesive can be applied to the small column portion 26. With this configuration, the bond between the core body 20 and the reinforcing plate 30 becomes stronger, and peeling of the joint surfaces 22 can be further suppressed.

[0032] <Variation 2, Variation 3> Figures 7 and 8 are plan and perspective views, respectively, of the polygonal core structure 10 of Modification 2. Figure 9 is a plan view of the polygonal core structure 10 of Modification 3.

[0033] The polygonal core structure 10 in Modification 2 and Modification 3 differ from the embodiment in terms of the polygonal shape of the cell 23. The reinforcing plate 30 in Modification 2 has a shape that follows the partition wall of the core body 20, similar to Modification 1. The reinforcing plate 30 in Modification 3 has a surface that extends parallel to the tensioning direction W, similar to the embodiment.

[0034] In the polygonal core structure 10 of Modified Examples 2 and 3, the core body 20 has a cylindrical shape including a plurality of planar sections extending along the axial direction. Viewed in a cross section perpendicular to the axial direction of the core body 20, the cell 23 has a 14-sided contour shape. The contour shape has a first inflection point 61 shared by three adjacent cells 23, and a second inflection point 62 and a third inflection point 63 shared by two adjacent cells 23 that are positioned diagonally with respect to the ribbon direction L. The plurality of planar sections of the core body 20 have partition walls 51 bent along ridges extending axially from each of the second inflection point 62 and the third inflection point 63.

[0035] With this configuration, although the shape of the reinforcing plate 30 differs in Modification 2 and Modification 3, the partition wall 51 of the core body 20 and the reinforcing plate 30 form a triangular column section 26 including the first inflection point 61. When a compressive load is applied to the core body 20 and buckling failure occurs, the buckling pitch of the small space column section 26 becomes smaller than the buckling pitch of the surface forming the core body 20. This improves the energy absorption efficiency at the time of buckling failure. As a result, the strength and rigidity of the polygonal core structure 10 are improved and the energy absorption efficiency is improved compared to a simple hexagonal honeycomb structure.

[0036] Adhesive can be applied to the small column portion 26. With this configuration, the bond between the core body 20 and the reinforcing plate 30 becomes stronger, and peeling of the joint surfaces 22 can be further suppressed.

[0037] <Modification 4> Figure 10 is a plan view showing the polygonal core structure 10 of the modified example 4.

[0038] The polygonal core structure 10 of Modification 4 differs from Modification 2 (see Figures 7 and 8) and Modification 3 (see Figure 9) in terms of the polygonal shape of the cells 23 (however, they are common in that they have a 14-sided contour shape). The reinforcing plate 30 of Modification 4 has a surface that extends parallel to the tensioning direction W, similar to the embodiment and Modification 3.

[0039] In the polygonal core structure 10 of Modification 4, the core body 20 has a cylindrical shape including a plurality of planar sections extending along the axial direction. Viewed in a cross section perpendicular to the axial direction of the core body 20, the cell 23 has a 14-sided contour shape. The contour shape has a first inflection point 64 shared by three adjacent cells 23 among the plurality of cells 23, and a second inflection point 65 adjacent to the first inflection point 64 and a third inflection point 66 adjacent to the second inflection point 65, shared by two adjacent cells 23 in a direction oblique to the ribbon direction L. The second inflection point 65 and the third inflection point 66 are located parallel to the ribbon direction L. The plurality of planar sections of the core body 20 have partition walls 52 bent along ridges extending axially from each of the second inflection point 65 and the third inflection point 66. The multiple planar sections also have partition walls 53 bent along ridges extending axially from the first inflection point 64 and the second inflection point 65, respectively. The core body 20 has a first slit 41 in the partition wall 52. The reinforcing plate 30 has a surface extending parallel to the tensioning direction W and engages with the partition wall 52 of the core body 20.

[0040] With this configuration, the partition wall 52 of the core body 20 and the reinforcing plate 30 engage perpendicularly. The first slit 41 of the core body 20 can be formed perpendicular to the surface of the partition wall 52. The second slit 42 of the reinforcing plate 30 can be formed perpendicular to the surface of the reinforcing plate 30. There is no need to form the first slit 41 at an angle to the surface of the partition wall 52. There is no need to form the second slit 42 at an angle to the surface of the reinforcing plate 30. This improves the moldability (productivity) of the corrugated plate 21 and the reinforcing plate 30. Also, because the partition wall 52 of the core body 20 and the reinforcing plate 30 are perpendicular, it becomes easier to fit the first slit 41 and the second slit 42 together, improving the ease of assembly between the core body 20 and the reinforcing plate 30. When the slits are formed at an angle, the slit width becomes relatively large. On the other hand, in modified example 4, the slit width can be made equal to the thickness of the mating plate, resulting in less reduction in strength.

[0041] The partition wall 52 of cell 23 and the reinforcing plate 30 form a relatively small column section 26 containing a first inflection point 64. When a compressive load is applied to the core body 20 and buckling failure occurs, the buckling pitch of the column section 26 becomes smaller than the buckling pitch of the surface forming the core body 20. This improves the energy absorption efficiency at the time of buckling failure. As a result, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is enhanced.

[0042] Adhesive can be applied to the small column portion 26. With this configuration, the bond between the core body 20 and the reinforcing plate 30 becomes stronger, and peeling of the joint surfaces 22 can be further suppressed.

[0043] <Modification 5> Figure 11 is a plan view showing the polygonal core structure 10 of modified example 5, and Figure 12 is an enlarged view showing the portion enclosed by a dashed line and labeled with reference numeral 12A in Figure 11.

[0044] The polygonal core structure 10 of Modification 5 differs from Modification 4 (see Figure 10) in terms of the polygonal shape of the cell 23.

[0045] In the polygonal core structure 10 of Modified Example 5, the core body 20 has a cylindrical shape including a plurality of planar portions extending along the axial direction. Viewed in a cross section perpendicular to the axial direction of the core body 20, the cell 23 has a 22-sided contour shape. The contour shape has a first inflection point 64 shared by three adjacent cells 23 among the plurality of cells 23, and a fourth inflection point 67 adjacent to the first inflection point 64, a second inflection point 65 adjacent to the fourth inflection point 67, and a third inflection point 66 adjacent to the second inflection point 65, shared by two adjacent cells 23 in a direction diagonally with respect to the ribbon direction L. The second inflection point 65 and the third inflection point 66 are located parallel to the ribbon direction L. Note that there are six first inflection points 64 for one cell 23. Depending on which point of the first inflection point 64 is focused on, the inflection point labeled 65 in the figure may become the third inflection point, and the inflection point labeled 66 may become the second inflection point. The multiple planar sections of the core body 20 have partition walls 52 bent along ridges extending axially from the second inflection point 65 and the third inflection point 66, respectively. The multiple planar sections also have partition walls 54 (see Figure 12) bent along ridges extending axially from the second inflection point 65 and the fourth inflection point 67, respectively, and partition walls 55 (see Figure 12) bent along ridges extending axially from the third inflection point 66 and the fourth inflection point 67, respectively. The core body 20 has a first slit 41 in the partition wall 52. The reinforcing plate 30 has a surface that extends parallel to the tensioning direction W and engages with the partition wall 52 of the core body 20.

[0046] With this configuration, similar to the polygonal core structure 10 of Modification 4, the partition wall 52 of the core body 20 and the reinforcing plate 30 engage perpendicularly. The first slit 41 of the core body 20 can be formed perpendicular to the surface of the partition wall 52. The second slit 42 of the reinforcing plate 30 can be formed perpendicular to the surface of the reinforcing plate 30. There is no need to form the first slit 41 at an angle to the surface of the partition wall 52. There is no need to form the second slit 42 at an angle to the surface of the reinforcing plate 30. This improves the moldability (productivity) of the corrugated plate 21 and the reinforcing plate 30. Also, because the partition wall 52 of the core body 20 and the reinforcing plate 30 are perpendicular, it becomes easier to fit the first slit 41 and the second slit 42 together, improving the ease of assembly between the core body 20 and the reinforcing plate 30. When the slits are formed at an angle, the slit width becomes relatively large. On the other hand, in the 4th modified example, the slit width can be made equal to the thickness of the mating plate, resulting in less reduction in strength.

[0047] The partition wall 52 of cell 23 and the reinforcing plate 30 form a relatively small column section 26 containing a first inflection point 64. When a compressive load is applied to the core body 20 and buckling failure occurs, the buckling pitch of the column section 26 becomes smaller than the buckling pitch of the surface forming the core body 20. This improves the energy absorption efficiency at the time of buckling failure. As a result, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is enhanced.

[0048] In Figures 11 and 12, the gaps between the partition wall 54 and the reinforcing plate 30, and the gaps between the partition wall 55 and the reinforcing plate 30 are shown enlarged for ease of understanding. The dashed line in Figure 12 shows the partition wall 53 in Modification 4. Cell 23 in Modification 5 has a fourth inflection point 67, which allows the partition walls 54 and 55 to be brought closer to the reinforcing plate 30. Adhesive 50 can be applied to the area between the partition wall 54 and the reinforcing plate 30, and adhesive 50 can be applied to the area between the partition wall 55 and the reinforcing plate 30. With this configuration, the bond between the core body 20 and the reinforcing plate 30 is strengthened, and peeling of the joint surfaces 22 can be further suppressed. Compared to filling the inner space of the small column portion 26 with adhesive, the amount of adhesive 50 used can be reduced while suppressing peeling of the joint surfaces 22.

[0049] <Variation 6> Figure 13 is a plan view showing the polygonal core structure 10 of modified example 6, and Figure 14 is a perspective view showing the main parts of the reinforcing plate 30 and other reinforcing plates 70. In Figure 13, gaps are provided between the members for ease of understanding. The same applies to Figures 15 and 16, which will be described later.

[0050] The polygonal core structure 10 of Modification 6 has an additional reinforcing plate 70 that engages with the reinforcing plate 30. In the description of Modification 6 and Modification 7, which will be described later, the reinforcing plate 30 will be referred to as the "first reinforcing plate 30," and the other reinforcing plate 70 will be referred to as the "second reinforcing plate 70."

[0051] The polygonal core structure 10 of the modified example 6 further includes a second reinforcing plate 70 (another reinforcing plate 70) extending in the ribbon direction L. The second reinforcing plate 70 (another reinforcing plate 70) has a third slit 43 that engages with the first reinforcing plate 30 (reinforcing plate 30).

[0052] With this configuration, the core body 20 is also fixed by the second reinforcing plate 70 via the first reinforcing plate 30. Therefore, when a compressive load is applied to the core body 20 and buckling failure occurs, the core body 20 is less likely to collapse. This further suppresses delamination between the joint surfaces 22. As a result, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is enhanced.

[0053] In Figure 13, the uppermost and lowermost cells 23 can be bent at the ends and overlapped with or joined to the first reinforcing plate 30. The ends of the first reinforcing plate 30 can be bent and overlapped with or joined to the second reinforcing plate 70. Similarly, the ends of the second reinforcing plate 70 can be bent and overlapped with or joined to the first reinforcing plate 30. This configuration physically reinforces the mating parts with each other, allowing the core body 20 to be fixed more securely.

[0054] The second reinforcing plate 70 engages with the first reinforcing plate 30 at an external position on the core body 20. The outermost part of the core body 20 is an open recess if the second reinforcing plate 70 is not provided. On the other hand, if the second reinforcing plate 70 is provided, the outermost part of the core body 20 is enclosed by the partition wall 52 of the cell 23 and the second reinforcing plate 70, forming a closed space 27 having approximately half the shape of the cell 23. When a compressive load is applied to the core body 20 and buckling failure occurs, the buckling pitch of the closed space 27 becomes smaller than the buckling pitch of the surface forming the core body 20. This improves the energy absorption efficiency at the time of buckling failure. As a result, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is improved.

[0055] Furthermore, the position in which the second reinforcing plate 70 engages with the first reinforcing plate 30 is not limited to an external position on the core body 20. The second reinforcing plate 70 can be engaged with the first reinforcing plate 30 at an internal position on the core body 20.

[0056] Furthermore, the second reinforcing plate 70 is not limited to cases where the cells 23 of the core body 20 have a 22-sided contour shape. The second reinforcing plate 70 can also be applied to a core body 20 in which the cells 23 have a contour shape such as a hexagon.

[0057] <Example 7> Figure 15 is a plan view showing the polygonal core structure 10 of the modified example 7.

[0058] The polygonal core structure 10 of Modification 7 differs from Modification 6 (see Figure 13) in that the first reinforcing plate 30 and the second reinforcing plate 70 have the same shape. The circles 44 on the uppermost first reinforcing plate 30 and the leftmost second reinforcing plate 70 in the figure indicate the positions of the slits.

[0059] With this configuration, since the first reinforcing plate 30 and the second reinforcing plate 70 have the same shape, the same mold can be used. This reduces the number of component types and contributes to cost reduction.

[0060] <Differentiation Example 8> Figure 16 is a plan view showing the polygonal core structure 10 of modified example 8.

[0061] The polygonal core structure 10 in Modification 8 differs from Modification 5 (see Figure 11) in that it has a frame 81 attached to it.

[0062] The polygonal core structure 10 of modified example 8 further includes a frame 81 surrounding the outer periphery of the core body 20 and the reinforcing plate 30, and connecting parts 82 and 83 that connect at least one of the core body 20 and the reinforcing plate 30 to the frame 81. The circle 82 in the figure indicates the connecting part between the core body 20 and the frame 81, and the circle 83 indicates the connecting part between the reinforcing plate 30 and the frame 81.

[0063] The outermost frame 81 is formed in a ring shape from a continuous material, eliminating any discontinuous sections. The material used to form the frame 81 can be metal, FRP, or the like. The joint 82 connects the core body 20 and the frame 81 by means of adhesive, welding, or mechanical joining with rivets. Similarly, the joint 83 connects the reinforcing plate 30 and the frame 81 by means of adhesive, welding, or mechanical joining with rivets.

[0064] With this configuration, the core body 20 is firmly supported by the reinforcing plate 30 and the frame 81. Therefore, when a compressive load is applied to the core body 20 and buckling failure occurs, the core body 20 is less likely to collapse. This further suppresses delamination between the joint surfaces 22. As a result, the strength and rigidity of the polygonal core structure 10 are improved, and the energy absorption efficiency is enhanced.

[0065] <Modification 9> Figure 17 is a perspective view showing the slits in the polygonal core structure 10 of the modified example 9.

[0066] The polygonal core structure 10 in modified example 9 has a modified slit shape.

[0067] In the modified example 9, the polygonal core structure 10 has a first slit 41 in the core body 20 and a second slit 42 in the reinforcing plate 30, both having grooves 41b and 42b that extend continuously to the end openings 41a and 42a. The width a of the end openings 41a and 42a is wider than the width b of the grooves 41b and 42b.

[0068] With this configuration, when engaging the core body 20 and the reinforcing plate 30, the end openings 41a and 42a are expanded, making it easier to fit the first slit 41 and the second slit 42, and improving the ease of assembly between the core body 20 and the reinforcing plate 30. As a result, the number of assembly steps for the core body 20 and the reinforcing plate 30 is reduced, contributing to cost reduction.

[0069] The end openings 41a and 42a have flat surfaces. The surfaces of the end openings 41a and 42a can be formed in an arc shape. When the surfaces of the end openings 41a and 42a are arc-shaped, the first slit 41 and the second slit 42 can be smoothly fitted together even if the end openings 41a and 42a come into contact with each other.

[0070] Although the polygonal core structure 10 of the present invention has been described above, the present invention is not limited to the configurations described in the embodiments and modifications described above, and can be modified as appropriate based on the claims.

[0071] The following embodiments are also included in the scope of the present invention: a polygonal core structure 10 according to any one of claims 3 to 7 having the features of claim 8; a polygonal core structure 10 according to any one of claims 3 to 8 having the features of claim 9; a polygonal core structure 10 according to any one of claims 3 to 9 having the features of claim 10. [Explanation of Symbols]

[0072] 10 Polygonal Core Structures 20-core main unit 21 Corrugated board 22 Joint surface 22a end 23 cells 26 Small column part 27 Closed space 30 Reinforcement plate (first reinforcement plate) 31 sides 41 First slit 41a End opening 41b Slot hole 42 Second slit 42a End opening 42b Slot hole 43 The third slit 50 Adhesives 61. First inflection point 62. Second inflection point 63. Third inflection point 64. First inflection point 65. Second inflection point 66. Third inflection point 70 Other reinforcing plates (second reinforcing plate) 81 Frame 82 Joint 83 Joint L Ribbon direction W Extension direction

Claims

1. A core body having multiple corrugated plates with a continuous uneven shape, and multiple polygonal cells formed by joining the overlapping joint surfaces of adjacent corrugated plates, A polygonal core structure having a reinforcing plate that engages with the core body, spanning across adjacent cells in the extension direction of the core body.

2. The core body has a first slit in at least one of the partition walls that divides the cell, which is different from the joining surface. The reinforcing plate has a second slit at a position corresponding to the first slit, The polygonal core structure according to claim 1, wherein the core body and the reinforcing plate are engaged by the first slit and the second slit fitting together.

3. The polygonal core structure according to claim 2, wherein the reinforcing plate has a surface in contact with the partition wall in which the first slit is formed.

4. The polygonal core structure according to claim 2, wherein the reinforcing plate has a surface extending parallel to the direction of extension.

5. The core body has a cylindrical shape including a plurality of planar portions extending along the axial direction, When viewed in a cross-section perpendicular to the axial direction of the core body, the cell has a 14-sided contour shape. The contour shape is defined as having a first inflection point shared by three adjacent cells among the plurality of cells, The two cells that are adjacent to each other in an oblique direction with respect to the ribbon direction share a second inflection point and a third inflection point, The polygonal core structure according to claim 2, wherein the plurality of planar portions of the core body have partition walls bent along ridges extending in the axial direction from each of the second and third inflection points.

6. The core body has a cylindrical shape including a plurality of planar portions extending along the axial direction, When viewed in a cross-section perpendicular to the axial direction of the core body, the cell has a 14-sided contour shape. The contour shape is defined as having a first inflection point shared by three adjacent cells among the plurality of cells, Two cells adjacent to each other in a direction diagonally with respect to the ribbon direction share a second inflection point adjacent to the first inflection point and a third inflection point adjacent to the second inflection point, The second and third inflection points are located parallel to the ribbon direction. The plurality of planar portions of the core body have partition walls that are bent along ridges extending in the axial direction from each of the second and third inflection points, The core body has the first slit in the partition wall, The polygonal core structure according to claim 2, wherein the reinforcing plate has a surface extending parallel to the extension direction and engages with the partition wall of the core body.

7. The core body has a cylindrical shape including a plurality of planar portions extending along the axial direction, Viewed in a cross-section perpendicular to the axial direction of the core body, the cell has a 22-sided contour shape. The contour shape is defined as having a first inflection point shared by three adjacent cells among the plurality of cells, Two cells adjacent to each other in a direction diagonally with respect to the ribbon direction share a fourth inflection point adjacent to the first inflection point, a second inflection point adjacent to the fourth inflection point, and a third inflection point adjacent to the second inflection point, The second and third inflection points are located parallel to the ribbon direction. The plurality of planar portions of the core body have partition walls that are bent along ridges extending in the axial direction from each of the second and third inflection points, The core body has the first slit in the partition wall, The polygonal core structure according to claim 2, wherein the reinforcing plate has a surface extending parallel to the extension direction and engages with the partition wall of the core body.

8. It further has other reinforcing plates extending in the direction of the ribbon, The polygonal core structure according to claim 2, wherein the other reinforcing plate has a third slit that engages with the reinforcing plate.

9. The frame surrounding the core body and the outer periphery of the reinforcing plate, The polygonal core structure according to claim 2, further comprising a connecting portion that connects at least one of the core body and the reinforcing plate to the frame.

10. The first slit of the core body and the second slit of the reinforcing plate have grooves that extend continuously to the end opening. The polygonal core structure according to claim 2, wherein the width of the end opening is wider than the width of the groove.

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