JP2022075629A - Manufacturing method for honeycomb structure and honeycomb structure - Google Patents

Abstract

To manufacture a honeycomb structure excellent in productivity and improved in characteristics.SOLUTION: A manufacturing method for a honeycomb structure, in which a plurality of corrugated sheets in which peaks and valleys are alternately formed are combined, includes: preparing a plurality of corrugated sheets having at least one of recesses extending along a thickness direction of the honeycomb structure in the peaks and projections extending along the thickness direction of the honeycomb structure in the valleys; and forming a honeycomb structure in which a plurality of cells are arranged including a pair of opposite partitions having a double wall structure, by combining the peaks and valleys of the corrugated sheets different from each other. In a honeycomb structure surface, each cell is surrounded by six other cells. In formation of the honeycomb structure, a space different from the cells is formed in at least a part of the partitions of the double wall structure, by using the recesses or the projections.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a method for manufacturing a honeycomb structure and a honeycomb structure.

The honeycomb structure, which is lightweight and can achieve high rigidity and high strength, is widely used for building materials and furniture, mainly for flying objects such as aircraft and spacecraft. The honeycomb structure (honeycomb core) mainly serves as a core material for structural sandwich panels, resists compressive force and out-of-plane shear force, and realizes a lightweight and highly rigid panel. It is also used as a shock absorber by crushing the hexagonal column in the axial direction. Further, the honeycomb structure has not only mechanical characteristics but also acoustic characteristics such as sound absorption and sound insulation, thermal characteristics such as heat insulation, and functional characteristics such as rectifying action. It is also used for design purposes due to the aesthetic beauty of the hexagonal tiling.

However, it is known that there is room for improvement in the compression characteristics, which is an important performance of the honeycomb structure (honeycomb core). For example, in Non-Patent Document 1, since the hexagonal cell wall buckles so as to be folded alternately because of the periodic and symmetrical structure due to the regular hexagonal tiling, the compressive strength is increased at this wavelength. It is shown that it will be decided.

Further, in Non-Patent Document 1, it is pointed out that the hexagonal cell is deformed into a saddle shape when bent due to the influence of a high Poisson's ratio, so that the flexibility is low. This can be a problem when creating curved sandwich panels such as rocket bodies. When creating curved panels, it is known that although a special honeycomb structure such as a flex core is used, it is more expensive than a normal honeycomb structure and its mechanical properties are lower than those of a normal honeycomb. Has been done.

Based on this background, a structure that increases the mechanical strength of the honeycomb structure is being studied. For example, Non-Patent Document 2 describes an improved honeycomb structure in which a cylinder is provided at the apex of a hexagonal cell.

Japanese Patent No. 6075006

Bitzer, T.N. Honeycomb technology: materials, design, manufacturing, applications and testing. Springer Science & Business Media, 1997. Chen, Jinxiang, et al. "The deformation mode and strengthening mechanism of compression in the beetle elytron plate." Materials & Design 131 (2017): 481-486. Kazuya Saito, et al. "A new manufacturing method for honeycomb structural materials that applies the mathematics of origami." Applied mathematics 28.1 (2018): 26-31.

However, since the improved honeycomb structure described in Non-Patent Document 2 has a new cylindrical structure at the intersection of the three cell walls, there is a problem that it can be manufactured only by using a 3D printer. That is, the improved honeycomb structure described in Non-Patent Document 2 has a shape that cannot be manufactured by the corrugated type or the spreading type, which is a known mass production method. Further, as another method for manufacturing the honeycomb structure, the origami method described in Non-Patent Document 3 and Patent Document 1 is also known, but the improved honeycomb structure described in Non-Patent Document 2 cannot be manufactured by the origami method. Is.

The present disclosure has been made in view of the above, and an object of the present invention is to provide a technique for manufacturing a honeycomb structure having excellent productivity and improved characteristics.

In order to achieve the above object, the method for manufacturing a honeycomb structure according to one embodiment of the present disclosure is a method for manufacturing a honeycomb structure in which a plurality of corrugated sheets in which peaks and valleys are repeatedly and alternately formed are combined. A plurality of the corrugates having at least one of a concave portion extending along the thickness direction of the honeycomb structure in the mountain portion and a convex portion extending along the thickness direction of the honeycomb structure in the valley portion. By preparing the sheets and combining the peaks and valleys of the corrugated sheets that are different from each other, a honeycomb in which a plurality of cells configured to include a pair of double-walled partition walls arranged facing each other are arranged. Including forming a structure, the cells are arranged to be surrounded by six other cells, respectively, on the honeycomb structure surface, and in forming the honeycomb structure, the concave portion or the convex portion. To form a space different from the cell in at least a part of the partition wall of the double wall structure.

The honeycomb structure according to one embodiment of the present disclosure is a honeycomb structure including a honeycomb structure in which a plurality of cells configured including a pair of double-walled partition walls arranged facing each other are arranged, and is a honeycomb structure surface. In, the cells are arranged to be surrounded by six other cells, respectively, and the partition wall of the double wall structure extends in the same direction, and the partition wall of the double wall structure extends in at least a part of the partition wall of the double wall structure. It has a space different from that of the cell between the structures.

According to the present disclosure, there is provided a technique for manufacturing a honeycomb structure having excellent productivity and improved characteristics.

1 (a) and 1 (b) are diagrams illustrating an example of the structure of the honeycomb structure according to one form. FIG. 2A shows an example of a mold for producing a corrugated sheet used for a conventional honeycomb structure, and FIGS. 2B and 2C are used for the honeycomb structure according to one form. It is a figure which shows the example of the mold which creates a corrugated sheet. 3 (a) to 3 (d) are views showing an example of a method for manufacturing a honeycomb structure by a corrugated method. 4 (a) to 4 (d) are views showing an example of a conventional method for manufacturing a honeycomb structure by an origami method. FIG. 5 is a diagram showing an example of an origami-type manufacturing method of the honeycomb structure according to the embodiment. FIG. 6 is a diagram showing an example of an origami-type manufacturing method of the honeycomb structure according to the embodiment. 7 (a) to 7 (c) are views showing an example of an origami-type manufacturing method of the honeycomb structure according to the embodiment. 8 (a) to 8 (c) are views for explaining an example of strength evaluation of the honeycomb structure. 9 (a) to 9 (c) are views for explaining an example of strength evaluation of the honeycomb structure. 10 (a) to 10 (c) are views for explaining an example of the honeycomb structure according to the modified example. 11 (a) to 11 (d) are views for explaining an example of the honeycomb structure according to the modified example.

Hereinafter, embodiments for carrying out the present disclosure will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted.

[Honeycomb structure]
FIG. 1 is a diagram showing a honeycomb structure according to one form. FIG. 1A is an overall view of the honeycomb structure, and FIG. 1B is a partially enlarged view thereof. In order to explain the honeycomb structure, the XYZ coordinate axes will be used. The honeycomb structure 1 is a structure having a honeycomb structure surface 10 extending along the XY plane, and the same shape as the honeycomb structure surface 10 appears in each cross section parallel to the XY plane along the Z-axis direction. In FIG. 1A, the honeycomb structure surface 10 is illustrated by a broken line. The honeycomb structure surface 10 is a surface corresponding to the main surface of the honeycomb structure 1.

The honeycomb structure 1 is composed of a combination of a plurality of corrugated sheets 20. The method for manufacturing the honeycomb structure 1 will be described later, but it is configured by laminating the corrugated sheets 20 to each other. The corrugated sheet 20 is a sheet having a long width direction, a longitudinal direction extending substantially in the X-axis direction, and a lateral direction extending in the Z-axis direction. The lateral direction of the corrugated sheet 20, that is, the width direction is the thickness direction of the honeycomb structure 1.

The honeycomb structure 1 has a first opening 11 and a second opening 12 as two types of openings on the honeycomb structure surface 10. The first opening 11 is a substantially hexagonal opening, and a pair of first partition walls 11a extending parallel to each other along the X-axis direction and a pair of first partition walls 11a provided so as to sandwich the first partition wall 11a and extending parallel to each other. It is a columnar space formed by two partition walls 11b and a pair of third partition walls 11c extending in parallel with each other. Since the pair of first partition walls 11a, the pair of second partition walls 11b, and the pair of third partition walls 11c have substantially the same length, the first opening 11 has a substantially regular hexagonal shape, but the second A part of the opening 12 is deformed due to the provision. Further, the first opening 11 is a basic space that repeatedly appears in the honeycomb structure 1, and may be called a cell. The shape of the cell is not limited to that based on a regular hexagon, and for example, a hexagon having different lengths on each side, a partially deformed hexagon, or the like may be used.

Each of the first openings 11 has a substantially hexagonal shape, but when focusing on one cell (first opening 11), each cell is arranged to be surrounded by six cells (another first opening 11). Has been done. The cells are separated from each other by the pair of first partition walls 11a, the pair of second partition walls 11b, and the pair of third partition walls 11c. Of these, the pair of first partition walls 11a has a double wall structure. That is, the two partition walls are overlapped.

A second opening 12 is provided near the center of the first partition wall 11a. The second opening 12 is a columnar space provided between two partition walls forming a double wall structure at a position that divides the first partition wall 11a. In the example shown in FIG. 1, the second opening 12 has a circular cross-sectional shape. By providing the second opening 12, in the first opening 11, a part of the first partition wall 11a protrudes inward (toward the center of the opening). As a result, the first opening 11 has a shape in which a part of the pair of first partition walls 11a is cut out.

In the honeycomb structure 1, the outer diameter of the second opening 12 may be smaller than the outer diameter of the first opening 11. As an example, the outer diameter of the second opening 12 may be less than about 50% with respect to the outer diameter of the first opening 11. The "outer diameter" of the first opening 11 and the second opening 12 can be set as the diameter of the circumscribed circle of the cross section of the opening when the opening has a shape obtained by partially deforming a regular polygon. .. Further, when it is not a regular polygon, the diameter of the smallest circle (minimum inclusion circle) including all the outer shapes of the openings can be set as the outer diameter.

The corrugated sheet 20 constituting the honeycomb structure 1 is shaped so as to form a half of the first opening 11 and a half of the second opening 12. Specifically, as shown in FIG. 1 (b), the corrugated sheet 20 has a wavy structure in which a plurality of peaks 21 and valleys 22 regularly repeat. The mountain portion 21 and the valley portion 22 are flat surfaces extending in the same direction (X-axis direction in FIG. 1B). Further, an inclined portion 23 is formed between the mountain portion 21 and the valley portion 22. As an example, the angle formed by the mountain portion 21 or the valley portion 22 and the inclined portion 23 is set to 120 °. However, this angle can be changed by the shape of the first opening 11.

Further, a recess 21a extending along the Z-axis direction is formed in the mountain portion 21 extending along the XZ plane. The recess 21a projects in the direction from the mountain portion 21 to the valley portion 22 when viewed from one corrugated sheet 20. Further, the concave portion 21a has a semicircular cross-sectional shape in the XY plane orthogonal to the Z-axis direction.

Similarly, in the valley portion 22 extending along the XZ plane, a convex portion 22a extending along the Z-axis direction is formed. The convex portion 22a protrudes in the direction from the valley portion 22 toward the mountain portion 21 when viewed with one corrugated sheet 20. Further, the convex portion 22a has a semicircular cross-sectional shape in the XY plane orthogonal to the Z-axis direction. The lengths of the mountain portion 21 and the valley portion 22 along the X-axis direction are the same, and the formation position of the concave portion 21a along the X-axis direction in the mountain portion 21 and the convex portion along the X-axis direction in the valley portion 22. The formation position of 22a is the same.

The honeycomb structure 1 is formed by combining the corrugated sheets 20 described above. Specifically, the honeycomb structure 1 is formed by facing the mountain portion 21 and the valley portion 22 between the corrugated sheets 20 adjacent to each other along the Y-axis direction and integrating (for example, laminating) them. Is formed. In the example shown in FIG. 1B, for example, two corrugated sheets 20A and 20B are arranged at positions where the valley portion 22 of the corrugated sheet 20A and the mountain portion 21 of the corrugated sheet 20B face each other. In this state, the valley portion 22 and the mountain portion 21 facing each other are bonded together. As a result, a substantially hexagonal space is formed by the mountain portion 21 of the corrugated sheet 20A and the valley portion 22 of the corrugated sheet 20B. This space corresponds to the first opening 11.

At this time, since the concave portion 21a formed in the mountain portion 21 and the convex portion 22a formed in the valley portion 22 are separated from each other, a space is formed between the concave concave portion 21a and the convex portion 22a facing each other. There is. This space corresponds to the second opening 12.

The mountain portion 21 of the corrugated sheet 20A is integrated with the valley portion 22 of the corrugated sheet 20C arranged on the opposite side of the corrugated sheet 20B. Further, the valley portion 22 of the corrugated sheet 20B is integrated with the mountain portion of the corrugated sheet 20D arranged on the opposite side of the corrugated sheet 20A. By combining the plurality of corrugated sheets 20 in this way, the first opening 11 and the second opening 12 are repeatedly formed between the corrugated sheets 20 and the adjacent corrugated sheets 20, and the honeycomb structure surface 10 is formed. As described above, the second opening 12 is formed in the first partition wall 11a on which the two corrugated sheets 20 are superposed in the honeycomb structure 1. That is, the first partition wall 11a has a double wall structure. In other words, it can be said that all the double wall structures extend in the same direction (in the example shown in FIG. 1 in the X-axis direction) on the honeycomb structure surface 10 of the honeycomb structure 1.

The shape of the second opening 12 is not particularly limited, and may be, for example, a quadrangle. In the case of a quadrangle, the concave portion 21a and the convex portion 22a may be formed so that the cross-sectional shape is not a semicircular shape but a mountain shape having an apex in the center.

[Manufacturing method of honeycomb structure]
Next, two methods will be described as a method for manufacturing the honeycomb structure 1 with reference to FIGS. 2 to 7.

(First method: corrugated type)
As a first method, a so-called corrugated manufacturing method will be described with reference to FIGS. 2 and 3. In the corrugated type, a plurality of corrugated sheets 20 are prepared, and these are integrated by adhesion or the like to form the honeycomb structure 1.

The corrugated sheet 20 can be formed, for example, by press-molding a flat sheet material with the mold shown in FIG. 2.

FIG. 2A is an example of a mold 90 for forming a honeycomb structure having a honeycomb structure surface in which conventional regular hexagons are repeatedly arranged, and each of the two upper molds 91 and the lower mold 92. The flat surfaces 93 and 94 forming the mountain portion 21 and the valley portion 22 and the inclined surface 95 forming the inclined portion between them are provided. On the other hand, the mold 80 shown in FIGS. 2 (b) and 2 (c) has flat surfaces 83 and 84 constituting the mountain portion 21 and the valley portion 22 in the upper mold 81 and the lower mold 82, respectively. An inclined surface 85 forming an inclined portion between them is provided. Further, the flat surface 83 forming the mountain portion 21 is provided with an uneven portion 83a that deforms the sheet material into a shape corresponding to the concave portion 21a, and the flat surface 84 forming the mountain portion 21 corresponds to the convex portion 22a. An uneven portion 84a that deforms the sheet material into the formed shape is provided.

First, as shown in FIG. 3A, the corrugated sheet 20 is formed by sandwiching the sheet material 20X between the upper mold 81 and the lower mold 82 and press-molding the sheet material 20 by the upper mold 81 and the lower mold 82. It is formed. The method for forming the corrugated sheet 20 is not limited to press molding, and a general method for forming the corrugated sheet 20 can be used. Specifically, a corrugated roll may be used, or it may be formed by vacuum forming or the like. Further, the entire sheet material does not have to be molded at one time, and the sheet may be partially molded while being fed.

Next, as shown in FIG. 3 (b), a plurality of corrugated sheets 20 are arranged in one direction (vertical direction in the example of FIG. 3 (b)), and a mountain portion is formed between the corrugated sheets 20 and the adjacent corrugated sheets 20. 21 and the valley portion 22 are arranged so as to face each other. In this state, as shown in FIG. 3C, the honeycomb structure 1 is formed by integrating (for example, laminating) the mountain portions 21 and the valley portions 22 arranged in close proximity to each other. The integrated mountain portion 21 and valley portion 22 form a first partition wall 11a having a double wall structure.

At this time, as shown in FIG. 3C, the concave portion 21a formed in the mountain portion 21 and the convex portion 22a formed in the valley portion 22 face each other in a region other than the concave portion 21a of the mountain portion 21. By integrating the valley portion 22 with the region other than the convex portion 22a so as to face each other, a space corresponding to the second opening 12 formed by the opposing concave portion 21a and the convex portion 22a is formed. That is, the second opening 12 is formed between the two partition walls of the double wall structure. A space corresponding to the first opening 11 is formed between the mountain portion 21 and the valley portion 22, which are not integrated, that is, between the mountain portion 21 and the valley portion 22 arranged in a separated state.

Further, as shown in FIG. 3D, a plurality of corrugated sheets 20 are laminated while arranging the mountain portions 21 and the valley portions 22 so as to face each other between the adjacent corrugated sheets 20. The mountain portion 21 and the valley portion 22 arranged close to each other are integrated. As a result, a honeycomb structure as shown in FIG. 1 having two types of openings, a first opening 11 and a second opening 12, is formed.

A wide corrugated sheet 20 is formed using a plurality of wide (deep) sheet materials, and a thick block-shaped honeycomb structure is formed from the corrugated sheet, and then along the honeycomb structure surface. Honeycomb structure 1 may be formed by slicing.

(Second method: origami type)
Next, by providing a slit in one large sheet and further bending it, it is possible to form the honeycomb structure 1 in which a plurality of corrugated sheets 20 are connected. A method of forming the honeycomb structure 1 by using this method will be described.

First, with reference to FIG. 4, a method of creating a honeycomb structure composed of only a general regular hexagon using an origami method (origami method, Kirigami honeycomb) will be described.

First, as shown in FIG. 4A, a large sheet material 30X is prepared, and a plurality of mountain fold lines and valley fold lines extending in one direction (W-axis direction in FIG. 4A) are formed. prepare. The mountain fold line is set so that two mountain fold lines and two valley fold lines are alternately provided along the L-axis direction orthogonal to the W-axis direction. The intervals c'of the mountain fold lines and the valley fold lines are evenly spaced as shown in FIG. 4 (a).

Further, a slit extending in the L-axis direction is formed. The slit includes a slit s1 connecting the valley fold lines sandwiching the two valley fold lines and a slit s2 connecting the valley fold lines sandwiching the two valley fold lines.
The slits s1 connecting the valley fold lines sandwiching the two mountain fold lines are repeatedly provided along the L-axis direction. Further, a mountain fold line is provided along the slit s1 along the L-axis direction. On the other hand, the slit s2 connecting the mountain fold lines sandwiching the two valley fold lines is also repeatedly provided along the L-axis direction. Further, a valley fold line is provided along the slit s2 along the L-axis direction.

The mountain fold line including the slit s1 and the valley fold line including the slit s2 are alternately provided along the W-axis direction. Further, the distance between the mountain fold line including the slit s1 along the W-axis direction and the valley fold line including the slit s2 is made equal. As a result, as shown in FIG. 4A, the distance between the adjacent slits in the W-axis direction between the mountain fold line and the valley fold line adjacent in the L-axis direction is d', whereas it is d'. Between the mountain fold lines adjacent to each other in the L-axis direction or between the valley fold lines, the distance between the adjacent slits in the W-axis direction is 2d'.

Next, the sheet material 30X is bent along the mountain fold line and the valley fold line extending in the W-axis direction formed on the sheet material 30X. As a result, as shown in FIG. 4B, the sheet material 30X has a corrugated sheet-like shape in which flat peaks 31 and flat valleys 32 appear alternately along the L-axis direction. ..

Next, the sheet material 30X is bent along the mountain fold line and the valley fold line extending in the L-axis direction provided on the sheet material 30X. As the fold lines extending in the L-axis direction, mountain fold lines and valley fold lines are alternately provided, so that the fold lines are bent in a zigzag manner as shown in FIG. 4 (c). At this time, the portions provided with the slits s1 and s2 are deformed so as to be separated from each other (so that the slits open) at the time of bending. As a result, as shown in FIG. 4D, the slit s1 formed along the mountain fold line forms the end of the hexagonal opening in the upper part of the drawing, and the slit formed along the mountain fold line. s2 forms the end of the hexagonal opening in the upper part of the figure. The end faces of the slits s1 and s2 appear on a pair of main faces (honeycomb structure faces) in the honeycomb structure 1. When the sheet material 30X is bent in a zigzag manner using the mountain fold line extending along the slit s1 and the valley fold line extending along the slit s2, the valley portions 32 sandwiching the mountain fold line come into contact with each other and at the same time. The mountain portions 31 that sandwich the valley fold line come into contact with each other. By integrating these, it is possible to form a honeycomb structure having only a regular hexagonal opening.

On the other hand, when the honeycomb structure 1 according to the present embodiment is manufactured, the difference is that the shapes corresponding to the above-mentioned concave portions 21a and the convex portions 22a are added as compared with the method for forming the honeycomb structure shown in FIG. ..

First, as shown in FIG. 5, a large sheet material 40X is prepared, and a plurality of mountain fold lines L1 and valley fold lines L2 extending in one direction (W-axis direction in FIG. 5) are provided. The mountain fold line is set so that the two mountain fold lines L1 and the two valley fold lines L2 are alternately provided along the L-axis direction orthogonal to the W-axis direction. The area between the two mountain fold lines L1 becomes a mountain portion 41 after being formed into a corrugated plate shape, and the area between the two valley fold lines L2 becomes a valley portion 42. However, the mountain portion 41 and the valley portion 42 are different from the mountain portion 21 and the valley portion 22 in the corrugated sheet 20 used in the corrugated system. That is, a part of the mountain portion 41 in the sheet material 40X corresponds to the mountain portion 21 of the corrugated sheet 20, while the other region corresponds to the valley portion 22. This is due to bending the sheet material 40X in a zigzag manner.

Further, a region a1 to be a concave portion 41a is provided between the two mountain fold lines L1, and a region a2 to be a convex portion 42a is provided between the two valley fold lines L2. This point is different from the example shown in FIG.

In the example shown in FIG. 4A, the widths of the mountain fold line and the valley fold line are basically the same (c'), but in the example shown in FIG. Since a2 is added, the distance c1 between the two mountain fold lines L1 or the valley fold line L2 becomes larger than the distance c2 between the mountain fold line and the valley fold line. However, the distance c2 may be set so that the distance between the two mountain fold lines L1 or the two valley fold lines L2 is c2 after the concave-convex shape of the concave portion 41a or the convex portion 42a is formed.

Next, a slit extending in the L-axis direction is formed in the sheet material 40X. The slit includes a slit s1 connecting the valley fold lines L2 sandwiching the two valley fold lines L1 and a slit s2 connecting the valley fold lines L1 sandwiching the two valley fold lines L2. Further, the point that the slits s3 and s4 on the same straight line as the slit s1 or the slit s2 and on the region a1 or a2 are provided is a part different from the example shown in FIG.

The slits s1 connecting the valley fold lines L2 sandwiching the two mountain fold lines L1 are repeatedly provided along the L-axis direction. Further, a mountain fold line L3 is provided along the slit s1 along the L-axis direction. Further, the slit s3 is provided on the same straight line as the slit s1 and the mountain fold line. The slit s3 is formed at a position where the slit s1 and the mountain fold line intersect the region a2.

On the other hand, the slit s2 connecting the mountain fold lines sandwiching the two valley fold lines is also repeatedly provided along the L-axis direction. Further, a valley fold line is provided along the slit s2 along the L-axis direction. Further, the slit s3 is provided on the same straight line as the slit s2 and the valley fold line. The slit s3 is formed at a position where the slit s2 and the valley fold line intersect the region a1.

The mountain fold line including the slits s1 and s3 and the valley fold line including the slits s2 and s4 are alternately provided along the W-axis direction. Further, the distance between the mountain fold line including the slit s1 along the W-axis direction and the valley fold line including the slit s2 is made equal.

Next, the sheet material 40X is bent along the mountain fold line L1 and the valley fold line L2 formed on the sheet material 40X in the W-axis direction. As a result, as shown in FIG. 6, the sheet material 40X is in a corrugated state in which flat peaks 41 and flat valleys 42 appear alternately along the L-axis direction. At this time, by bending the sheet material 20X at both ends of the regions a1 and a2 and bending the regions a1 and a2 in a curved shape, a groove-shaped concave portion 41a is formed from the region a1 and a convex portion 42a is formed from the region a2. Will be done.

Next, the sheet material 40X is bent along the mountain fold line L3 and the valley fold line L4 formed on the sheet material 40X in the L-axis direction. As the fold lines extending in the L-axis direction, the mountain fold lines L3 and the valley fold lines L4 are alternately provided, so that the fold lines are bent in a zigzag manner as shown in FIG. 7 (a). At this time, the portions provided with the slits s1 to s4 are deformed so as to be separated from each other at the time of bending. FIG. 7A shows a state in which the slits s1 and s3 are deformed while the slits are widened (while the slits are open).

When the bending angle is further increased, as shown in FIGS. 7 (b) and 7 (c), the convex portions 42a separated by the slits 3 face each other. As a result, as shown in FIG. 7 (c), the two convex portions 42a are deformed so as to form the second opening 12 in the honeycomb structure 1. Further, as a result of being bent along the mountain fold line L3, the valley portions 42 overlap each other, and these form the first partition wall 11a having a double wall structure.

Further, the two mountain portions 41 separated by the slit s1 face each other to form an opening 11 in the honeycomb structure 1.

Although the enlarged view is not shown in FIG. 7, the slits s2 and s4 are also deformed so as to form the openings 11 and 12 in the same manner as the slits s1 and s3. That is, as the sheet material 40X is bent, the slit expands and deforms. Then, the recesses 41a separated by the slit s3 face each other. As a result, the two recesses 41a are deformed to form the second opening 12. On the other hand, the two valley portions 42 separated by the slits 2 face each other to form the opening 11 in the honeycomb structure 1.

As shown in FIG. 7 (c), after bending the sheet material 40X along the mountain fold lines and valley fold lines overlapping the slits s1 to S4, the abutting portions (mountain portions 41 to each other or valley portions 42 to each other) are integrated. Then, the honeycomb structure 1 is completed. In this way, the honeycomb structure 1 can be formed by an origami method in which the sheet material 40X is bent and formed.

In the above procedure, the procedure for creating a corrugated sheet (see FIG. 6) in which the slits s1 to s4 are formed is shown in the procedure of bending and molding the sheet material 40X into which the slits s1 to s4 are introduced. It is not limited to this procedure. For example, the sheet material 40X may be first formed into a corrugated plate shape shown in FIG. 6 by using a method such as press molding, and then a slit may be formed at a predetermined position by a laser processing machine or the like.

[Characteristics of honeycomb structure]
The four features of the honeycomb structure 1 described above will be described. These features are advantages over the honeycomb structures known so far.

(First feature)
The first feature is that it can be easily manufactured by using a corrugated type or origami type device among the existing mass production methods. As described in the first method described above, in the corrugated type, the honeycomb structure 1 is formed by processing a conventional press mold, bender, or the like so as to form a shape corresponding to the concave portion 21a and the convex portion 22a. Can be manufactured. Further, also in the origami type described by the second method, the honeycomb structure is formed by adding the function of forming the concave portion 41a and the convex portion 42a and adding the slits s3 and s4 to the region to the conventional device. Body 1 can be manufactured.

As described above, it is possible to realize the honeycomb structure 1 by improving a part of the method for producing the honeycomb structure 1 composed of only the conventional regular hexagonal openings.

(Second feature)

The second feature of the honeycomb structure 1 is that the mechanical properties are improved.

The honeycomb structure 1 has a small opening in addition to the regular hexagonal opening, similar to the improved honeycomb structure described in Non-Patent Document 2. Such a minute columnar structure improves the compressive strength. As the compressive strength increases, the amount of energy absorbed when exposed to external pressure also increases. Therefore, the honeycomb structure 1 also improves the shock absorption performance.

The compressive strength of the honeycomb structure 1 is based on the assumption that the peripheral conditions of the rectangular plates constituting each side of the honeycomb structure surface 10 are simple support on four sides, and the unidirectional uniform compressive load of the rectangular plate is used. It is calculated by considering the buckling due to, and is specifically expressed by the following formula (1).

In the above mathematical formula (1), Ec, ν, and σy are Young's modulus, Poisson's ratio, and yield stress of the materials constituting the honeycomb structure 1, respectively. Further, t is the thickness of the sheet (foil thickness), and a is the width of the rectangular plate. In the honeycomb structure 1 described above, the columnar structure constituting the periphery of the second opening 12 reinforces the central portion of the rectangular plate constituting the honeycomb structure 1. Therefore, the width of the effective rectangular plate used in the mathematical formula (1) is halved or less. Further, from the mathematical formula (1), it can be seen that the compressive strength increases in proportion to the square of the reciprocal 1 / a of the width of the rectangular plate. Here, of the six rectangular plates forming the periphery of the regular hexagonal opening 11 which is the basic structure in the honeycomb structure 1, only two are reinforced by the second opening 12. Therefore, assuming that two of the six rectangular plates that bear the compressive force have four times the strength due to the formation of the second opening 12, the compressive strength of the honeycomb structure 1 as a whole is determined. Theoretically, it is expected to grow up to about twice. Further, considering that the width of the rectangular plate (a in the mathematical formula (1)) is almost the same, the honeycomb structure 1 is reinforced at the end of the rectangular plate like the improved honeycomb structure described in Non-Patent Document 2. The honeycomb structure 1 is expected to have a higher reinforcing effect than the case of introducing the opening for the honeycomb structure 1.

The results of evaluating the compressive strength of the honeycomb structure 1 using a paper sample will be described with reference to FIG.

Prepare 0.25 mm thick paper, and make the honeycomb structure 1 so that the cell size of the opening 11 (distance between the opposite sides of the hexagon) is 30 mm and the second opening 12 is a quadrangle with a side of 5 mm. Created (see also Figure 10). The size of the honeycomb structure surface was 90 mm × 150 mm, and the thickness (height; depth with respect to the honeycomb structure surface; length in the Z-axis direction in FIG. 1) of the honeycomb structure 1 was 15 mm. Further, in the honeycomb structure 1 used as the test piece, 13 substantially hexagonal openings 11 and 12 quadrangular second openings 12 were provided.

The test piece of the above honeycomb structure 1 was installed in a material testing machine (manufactured by Shimadzu Corporation; model number: SHIMADZU AG-X Plus 20kN) shown in FIG. 8 (a) under the condition of a test speed of 1.0 mm / min. , Compressive strength was measured.

Table 1 shows the results of compressive strength and energy absorption. Further, FIG. 8B shows a measurement result (load displacement curve) of the relationship between the displacement amount and the reaction force. As a comparison target, the measurement results relating to a normal honeycomb structure (w / o hollows) in which the second opening 12 is not provided are also shown.

表１に示すように、第２開口１２を有するハニカム構造体１（w/ hollows）の場合、通常のハニカム構造体（w/o hollows）と比較して、圧縮強度が２１．８％上昇し、エネルギー吸収量は４６．２％上昇した。

As shown in Table 1, in the case of the honeycomb structure 1 (w / hollows) having the second opening 12, the compressive strength is increased by 21.8% as compared with the normal honeycomb structure (w / o hollows). , Energy absorption increased by 46.2%.

The reason why the value does not increase from the value estimated based on the formula (1) is that the compressive strength is easily affected by the initial fraud, and the measurement using a simple test piece does not sufficiently exhibit the performance. It seems to be because. It is expected that more precise tests will show even higher performance.

Further, as shown in FIG. 8B, it was also confirmed that the honeycomb structure 1 having the second opening 12 (with the columnar structure) had a smoother load change on the load displacement curve. It is considered that this is because the honeycomb structure 1 described in the above embodiment buckles at a shorter wavelength than the normal honeycomb structure. That is, since the load does not decrease even during buckling, it is presumed that more energy is absorbed and the impact absorption effect is enhanced. FIG. 8C shows a buckled state of the honeycomb structure 1. In the honeycomb structure 1, since the buckling of the second opening 12 proceeds at a fine wavelength, it is presumed that it is possible to absorb more energy.

In the preliminary test, an increase in compressive rigidity was also observed. It is presumed that this is because the columnar reinforcing structure by the second opening 12 suppressed the buckling in the nonlinear elastic mode. Further, since the out-of-plane shear rigidity and strength considered to be important for the honeycomb structure 1 are also inversely proportional to the cell size of the opening in the honeycomb structure, the honeycomb structure 1 having the small second opening 12 is strengthened. Be expected.

(Third feature)
The third feature of the honeycomb structure 1 is that the flexibility is improved. Conventionally, as a special honeycomb core for a curved sandwich panel, a structure having a lower Poisson's ratio and showing a zero or a negative value is effective, and an over-expanded core, a flex core, or the like is used.

On the other hand, when the honeycomb structure 1 is loaded along the extending direction (X-axis direction) of the side on which the second opening 12 is formed as shown in FIG. 9A, FIG. 9B and FIG. As shown in FIG. 9 (c), the second opening 12 is collapsed so as to expand toward the Y-axis direction intersecting the X-axis direction. On the other hand, the honeycomb structure 1 itself is not deformed so as to spread in the Y-axis direction. Therefore, in the honeycomb structure 1, the Poisson's ratio of zero can be realized by the deformation of the second opening 12. Therefore, it can be expected to improve the flexibility as well as the over-expanded core (butterfly type honeycomb; Re-entrant type honeycomb). It should be noted that such a feature cannot be expected in the improved honeycomb structure described in Non-Patent Document 2. Further, the honeycomb structure 1 is advantageous in that the flexibility is improved while preventing the decrease in strength and rigidity, unlike the existing honeycomb core for curved surfaces which has been known conventionally.

(Fourth feature)
The fourth feature of the honeycomb structure 1 is the improvement of the design by changing the cross-sectional shape of the second opening 12.

As described above, in the honeycomb structure 1, the case where the shape of the honeycomb structure surface 10 of the second opening 12 is circular has been described, but the second opening 12 may have another shape such as a quadrangle. 10 (a) and 10 (b) show a case where the second opening 12 is a quadrangle. By changing the shapes of the concave portion 21a and the convex portion 22a in the corrugated sheet 20, the shape of the second opening 12 can be changed. In the case of the corrugated type, as shown in FIG. 10C, by changing the shape of the uneven portions 83a and 84a in the mold from a semicircular shape to a triangular shape having vertices, the concave portions 21a and the convex portions 22a in the corrugated sheet are formed. The shape of the second opening 12 can be changed by combining these.

FIG. 11 shows an example in which the shape of the second opening 12 is changed as compared with the honeycomb structure 1. The honeycomb structure 1A shown in FIG. 11A is an enlarged shape of the second opening 12. In the honeycomb structure 1A, the second opening 12 is formed in a region of more than half of the length of the peak portion 21 and the valley portion 22 of the corrugated sheet 20 forming the double wall structure.

The honeycomb structure 1B shown in FIG. 11B is a modification of the shape of the second opening 12, and is designed to have a hexagonal shape. The shape of the second opening 12 can be changed by changing the shapes of the concave portion 21a and the convex portion 22a in the corrugated sheet 20. The shape of the second opening 12 is not limited to the above-mentioned circle, quadrangle, and hexagon. Further, in the above embodiment, the case where the concave portion 21a and the convex portion 22a have symmetrical shapes is shown, but by making the shapes of the concave portion 21a and the convex portion 22a different from each other, the shape of the second opening 12 can be changed. It can be changed further.

The honeycomb structure 1C shown in FIG. 11C shows a configuration in which the second opening 12 is provided only for a part of the mountain portion 21 and the valley portion 22 of the corrugated sheet 20 forming the double wall structure. .. For example, in the corrugated sheet 20E, the valley portion 22 is provided with the convex portion 22a, while the mountain portion 21 is not provided with the concave portion 21a. On the other hand, in the corrugated sheet 20F, the concave portion 21a is provided in the mountain portion 21, while the convex portion 22a is not provided in the valley portion 22. When these two types of corrugated sheets 20E and 20F are alternately arranged and integrated so that the mountain portion 21 provided with the concave portion 21a and the valley portion 22 provided with the convex portion 22a face each other, the first The double wall portion in which the two openings 12 are formed and the double wall portion in which the second opening 12 is not formed are alternately provided. In the case of such a configuration, the shape of the first opening 11 also differs depending on the presence or absence of the second opening 12. For example, the first opening 11 formed by arranging the double walls on which the second opening 12 is not formed so as to face each other has a regular hexagonal shape. On the other hand, the first opening 11 formed by arranging the double walls on which the second opening 12 is formed facing each other is deformed from a regular hexagon by the shape of the second opening 12. The second opening 12 does not have to be provided in all the portions of the double wall structure, and may be provided only in a part thereof.

The honeycomb structure 1D shown in FIG. 11D is obtained by further modifying the shape of the second opening 12 so as to have a cross shape. The shape of the second opening 12 can be changed by changing the shapes of the concave portion 21a and the convex portion 22a in the corrugated sheet 20.

In this way, the shape of the second opening 12 can be variously changed. Further, the number of the second openings 12 can be changed as appropriate. As an example, a plurality of second openings 12 may be provided in a portion where the mountain portion 21 and the valley portion 22 constituting one double wall structure are integrated.

[others]
The second opening 12 does not have to be provided in all of the first partition wall 11a, and may be provided only in a part thereof.

Further, the position and size of the second opening 12 of the first partition wall 11a can be appropriately changed, but as shown in FIG. 1 and the like, the second partition wall 11a is located near the center of the second partition wall 11a. When the opening 12 is provided, the strength of each portion can be made uniform to some extent, so that when the energy of compression is received in the Z-axis direction, it is possible to prevent the load from being biased. From the viewpoint of equalizing the strength, if the second opening 12 having the same shape is provided at the same position (for example, near the center) in all the first partition walls 11a, the bias of the load received on the honeycomb structure surface 10 is reduced. can do.

However, for the purpose of enhancing the design, the arrangement of the second openings 12 is not evenly arranged, and the positions where the second openings 12 are provided and the positions where the second openings 12 are not provided as in the honeycomb structure 1C shown in FIG. 11 (c). It may be configured to bias. Further, the shapes of the plurality of second openings 12 may be different from each other.

Further, the configuration for providing the second opening 12 can be appropriately changed. For example, in the above embodiment, the opening in which the concave portions 21a and / or the convex portions 22a face each other with basically the same shape (symmetry) is described, but the concave portions 21a and / or the convex portions 22a having different shapes face each other. The second opening 12 may be formed by allowing the second opening 12. The second opening 12 may be formed by providing the concave portion 21a only in the integrated mountain portion 21 forming the double wall structure or providing the convex portion 22a only in the valley portion 22. That is, each of the second openings 12 may be formed by the unevenness formed on one of the two corrugated sheets forming the double wall structure, and the configuration thereof can be appropriately changed.

Further, in the honeycomb structure 1 described in the above embodiment, the case where the second partition wall 11b and the third partition wall 11c are flat has been described, but the partition wall may be deformed, for example, the honeycomb structure surface 10. In the above, unevenness may be provided so that the second partition wall 11b and the third partition wall 11c are not straight.

[Additional Notes]
The method for manufacturing a honeycomb structure according to one embodiment of the present disclosure is a method for manufacturing a honeycomb structure in which a plurality of corrugated sheets in which peaks and valleys are repeatedly and alternately formed are combined, and the honeycomb is formed in the peak. To prepare a plurality of the corrugated sheets having at least one of a recess extending along the thickness direction of the structure and a convex portion extending along the thickness direction of the honeycomb structure in the valley portion. By combining the peaks and valleys of the corrugated sheets that are different from each other, a honeycomb structure in which a plurality of cells composed of a pair of double-walled partition walls arranged facing each other are arranged is formed. In the honeycomb structure surface, the cells are arranged to be surrounded by six other cells, respectively, and in forming the honeycomb structure, the concave portion or the convex portion is used to form the double. At least a part of the partition wall of the wall structure forms a space different from the cell.

The plurality of corrugated sheets are the corrugated sheets having a width corresponding to the thickness of the honeycomb structure, and in forming the honeycomb structure, the mountain portions and the valley portions of the corrugated sheets that are different from each other are combined. The plurality of corrugated sheets are arranged so that the mountain portion of one of the corrugated sheets and the valley portion of the other corrugated sheet face each other, and the mountain portion and the valley portion are integrated. The honeycomb structure may be formed by forming the honeycomb structure.

The plurality of corrugated sheets are prepared as a sheet material in which a plurality of the corrugated sheets having a width corresponding to the thickness of the honeycomb structure are connected in one direction, and forming the honeycomb structure is the sheet material. By bending the sheet material along the bending line extending along the one direction, the corrugated sheet including the concave portion or the convex portion is formed into a corrugated plate shape to which the corrugated sheet is connected, and the sheet material is orthogonal to the one direction. The alternately arranged mountain fold lines and valley fold lines include bending the corrugated sheet material in a zigzag manner, and slits are formed along the mountain fold lines and the valley fold lines. By bending the sheet material in a zigzag manner while opening the slits, a partition wall having a double wall structure may be formed in a state where a part of the adjacent corrugated sheets is connected to each other.

The honeycomb structure according to one embodiment of the present disclosure is a honeycomb structure including a honeycomb structure in which a plurality of cells configured including a pair of double-walled partition walls arranged facing each other are arranged, and is a honeycomb structure surface. In, the cells are arranged to be surrounded by six other cells, respectively, and the partition wall of the double wall structure extends in the same direction, and the partition wall of the double wall structure extends in at least a part of the partition wall of the double wall structure. It has a space different from that of the cell between the structures.

The space may have a circular cross-sectional shape on the honeycomb structure surface.

The space may be formed by separating both of the partition walls forming the double wall structure from each other.

The space may be provided in the vicinity of the center of the partition wall of the double wall structure.

The partition wall having the double wall structure may be formed by bending one sheet.

1,1A-1D ... Honeycomb structure, 10 ... Honeycomb structure surface, 11 ... First opening (cell), 11a ... First partition wall, 11b ... Second partition wall, 11c ... Third partition wall, 12 ... Second opening, 20 , 20A-20F ... Corrugated sheet, 20X ... Sheet material, 21 ... Mountain part, 21a ... Concave, 22 ... Valley part, 22a ... Convex part, 23 ... Inclined part, 30X ... Sheet material, 31 ... Mountain part, 32 ... Valley Part, 40X ... Sheet material, 41 ... Mountain part, 41a ... Recessed part, 42 ... Valley part, 42a ... Convex part.

Claims (8)

It is a manufacturing method of a honeycomb structure that combines a plurality of corrugated sheets in which peaks and valleys are repeatedly and alternately formed.
A plurality of the corrugated sheets having at least one of a recess extending along the thickness direction of the honeycomb structure in the mountain portion and a convex portion extending along the thickness direction of the honeycomb structure in the valley portion. To prepare and
By combining the peaks and valleys of the corrugated sheets that are different from each other, a honeycomb structure in which a plurality of cells composed of a pair of double-walled partition walls arranged facing each other are arranged is formed.
Including
On the honeycomb structure surface, the cells are arranged so as to be surrounded by six other cells, respectively.
A method for manufacturing a honeycomb structure, in which a space different from the cell is formed in at least a part of a partition wall of the double wall structure by using the concave portion or the convex portion in forming the honeycomb structure. The plurality of corrugated sheets are the corrugated sheets having a width corresponding to the thickness of the honeycomb structure.
In forming the honeycomb structure, the peaks and valleys of the corrugated sheets that are different from each other are combined, and the peaks on one corrugated sheet and the valleys on the other corrugated sheet face each other. The method for manufacturing a honeycomb structure according to claim 1, wherein the plurality of corrugated sheets are arranged and the mountain portion and the valley portion are integrated to form the honeycomb structure. The plurality of corrugated sheets are prepared as a sheet material in a state in which a plurality of the corrugated sheets having a width corresponding to the thickness of the honeycomb structure are connected in one direction.
Forming the honeycomb structure is
By bending the sheet material along a bending line extending along the one direction of the sheet material, the corrugated sheet including the concave portion or the convex portion is formed into a corrugated sheet shape to which the corrugated sheet is connected.
It includes bending the corrugated sheet material in a zigzag manner by means of mountain fold lines and valley fold lines that are orthogonal to each other and are arranged alternately.
Slits are formed along the mountain fold line and the valley fold line.
The honeycomb structure according to claim 1, wherein the sheet material is bent in a zigzag manner while opening the slit to form a partition wall having a double wall structure in a state where a part of the adjacent corrugated sheets is connected to each other. Production method. A honeycomb structure including a honeycomb structure in which a plurality of cells composed of a pair of double-walled partition walls arranged facing each other are arranged.
In the honeycomb structure surface, the cells are arranged to be surrounded by six other cells, respectively.
The partition wall of the double wall structure extends in the same direction and extends in the same direction.
A honeycomb structure having a space different from that of the cell between the double wall structures in at least a part of the partition wall of the double wall structure. The honeycomb structure according to claim 4, wherein the space has a circular cross-sectional shape on the honeycomb structure surface. The honeycomb structure according to claim 4 or 5, wherein the space is formed by separating both of the partition walls forming the double wall structure from each other. The honeycomb structure according to any one of claims 4 to 6, wherein the space is provided near the center of the partition wall of the double wall structure. The honeycomb structure according to any one of claims 4 to 7, wherein the partition wall having the double wall structure is formed by bending one sheet.

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