JP2022139017A - honeycomb core - Google Patents

Abstract

To provide a honeycomb core capable of enhancing the strength of a curved surface honeycomb panel.SOLUTION: There is provided a honeycomb core in which, at least partially, a contour shape of each of a plurality of cells which is defined by cell walls on a side surface on one side of a thickness direction is a hexagon, and a contour shape of each of a plurality of cells defined by the cell walls on a side surface on the other side of the thickness direction is an X-shape. The cell wall is folded along a linear ridge line which extends from an apex of the hexagon toward a peak of the X-shape. Y ridge lines extend from each peak of the hexagon, where X: 8n+2k and Y: 2n+1 (n is a natural number and k is an integer of 0 or greater and 3 or smaller) are satisfied.SELECTED DRAWING: Figure 1

Description

The present invention relates to honeycomb cores.

Patent Document 1 discloses a core material for a curved honeycomb panel. The core material has a convex surface formed by a trapezoid with an upper base a and a lower base b (a<b), a concave surface of the same shape, and a concave surface positioned between the convex surface and the concave surface, with an upper base c and a lower base. An intermediate surface composed of a trapezoid whose bottom is d (c>d) alternately forms a continuous wavy shape, a + c = b + d, b ≠ d, and the upper edge of the convex surface or the concave surface and the upper surface of the intermediate surface θ ₁ is the angle formed by the edges, θ ₂ is the angle formed by the lower edge of the convex or concave surface and the lower edge of the intermediate surface, W 1 is the cell pitch in the circumferential direction on the outer surface of the curved honeycomb panel, and W ₁ is the outer surface of the curved honeycomb panel. θ ₁ and θ ₂ are given by the solution of the following equations, where H is the height between and the inner surface, and R is the radius of curvature of the inner surface.
a+c·cos θ ₁ =b+d·cos θ ₂
c·sin θ ₁ −d·sin θ ₂ =W ₁ ×H/(R+H)

Patent No. 3110232

About half or more of the core material is composed of the intermediate surface. The trapezoid forming the intermediate surface is a curved surface in which the upper base and the lower base are twisted. For this reason, it is difficult to increase the strength of the curved honeycomb panel (typically, the compressive strength in the thickness direction, the bending strength, etc.) above a certain level with the core material.

An object of the present invention is to provide a honeycomb core capable of improving the strength of a curved honeycomb panel.

In a honeycomb core according to an aspect of the present invention, at least a part of the plurality of cells defined by the cell walls on one side surface in the thickness direction has a hexagonal contour shape, and the other side surface in the thickness direction has a hexagonal contour shape. The contour shape of each of the plurality of cells defined by the cell walls on the side surface of is an X-gon. The cell walls are bent along linear ridges extending from the vertices of the hexagon to the vertices of the X-gon. Y edges extend from each vertex of the hexagon. However, X: 8n+2k, Y: 2n+1 (n is a natural number, k is an integer from 0 to 3)

According to the honeycomb core, the strength of the curved honeycomb panel can be improved.

1 is a perspective view of a honeycomb core according to a first embodiment; FIG. FIG. 2 is a bottom view showing the lower surface, which is a curved surface, of the honeycomb core of FIG. 1 in a state in which it is virtually unfolded into a plane; FIG. 2 is a top view showing the upper surface, which is a curved surface, of the honeycomb core of FIG. 1 in a state in which it is virtually unfolded into a plane; FIG. 2 is a perspective view of a block formed by laminating sheet materials that are materials of the honeycomb core of FIG. 1; FIG. 4 is an enlarged view of the upper edge of the cell wall in the V section of FIG. 3; FIG. 4 is a perspective view of a honeycomb core according to a second embodiment; FIG. 4 is a perspective view of a honeycomb panel to which a honeycomb core according to another embodiment is applied;

Honeycomb cores 1 according to some embodiments will be described below with reference to the drawings. L in each figure indicates the ribbon direction of the honeycomb core 1, and W indicates the expansion direction of the honeycomb core 1. As shown in FIG. In the following description, elements having the same functions are denoted by the same reference numerals, and overlapping descriptions are omitted.

The honeycomb core 1 has, for example, surface materials (not shown) adhered to both surfaces thereof to form a curved honeycomb panel having a sandwich structure. Therefore, it is also called a curved honeycomb core. The ribbon direction L and the spreading direction W are parallel to the curved surface formed by the surface of the curved honeycomb panel and perpendicular to each other. The thickness direction T of the honeycomb core 1 is perpendicular to the ribbon direction L and the extending direction W, and coincides with the thickness direction of the honeycomb panel. Hereinafter, one side in the thickness direction of the honeycomb core 1 is referred to as "lower side", the other side is referred to as "upper side", the side surface on one side in the thickness direction is referred to as "lower surface", and the side surface on the other side is referred to as "upper surface". Terms such as “downward” and “upward” are defined for the sake of convenience in describing the positional relationship of each element, and do not limit the actual mounting attitude of the honeycomb core 1 and the like.

The honeycomb core 1 is composed of, for example, cell walls 2 and a plurality of cells (spaces) 3 partitioned by the cell walls 2, as shown in FIG. Further, each of the plurality of cells 3 defined by the cell walls 2 on the lower surface _1L of the honeycomb core 1 has a hexagonal contour shape, and the plurality of cells 3 defined by the cell walls 2 on the upper surface _1U of the honeycomb core 1 is hexagonal. The contour shape of each cell 3 is an X-gon. Here, X is 8n+2k (n is a natural number, k is an integer from 0 to 3). The lower surface 1 _L of the honeycomb core 1 is a curved surface spanned by the lower edges 2 _L of the cell walls 2 , and the upper surface 1 _U is a curved surface spanned by the upper edges 2 _U of the cell walls 2 .

The cell walls 2 are bent along linear ridgelines 4 extending from the vertices of the hexagons to the vertices of the X-gon. Y edges 4 extend from each vertex of the hexagon. Here, Y is 2n+1 (n is a natural number, k is an integer from 0 to 3). Therefore, X and Y have a relationship satisfying X=4Y+2k−4 (k is an integer from 0 to 3). The edges 4 do not intersect each other. Note that "extending from the apex of the hexagon to the apex of the X-gon" is not limited to the state in which the apex of the hexagon and the apex of the X-gon are connected by the edge line 4, but the apex of the hexagon and the apex of the X-gon This includes the state in which the edge line 4 extends along the connecting straight line segment. That is, "extending from the apex of the hexagon to the apex of the X-gon" includes the state in which the end of the edge line 4 does not reach either or both of the apex of the hexagon and the apex of the X-gon. The same applies to "extending from each vertex of a hexagon".

The thickness of the honeycomb core 1 is not particularly limited, but is, for example, about 3 mm to 20 mm. Also, the size of the cell 3 is not particularly limited, but for example, the maximum width is about 3 mm to 30 mm.

<First Embodiment>
In the first embodiment, as shown in FIGS. 1 to 3, the contour shape of each cell 3 defined by the upper edge _2U of the cell wall 2 on the upper surface _1U of the honeycomb core 1 is a 14-sided (n=1 , k=3). The outline shape of each cell 3 defined by the lower edge _2L of the cell wall 2 on the lower surface _1L of the honeycomb core 1 is hexagonal. Each edge line 4 of the cell wall 2 extends from the hexagonal vertex to each 14-sided vertex. Three ridge lines 4 extend from each vertex of the hexagon.

As shown in FIGS. 1 and 2, each hexagon has two first sides 5 parallel to the ribbon direction L and four second sides 6 not parallel to the ribbon direction L. As shown in FIGS. The cell wall 2 is divided by a ridgeline 4 into a _first flat portion P1, a _second flat portion P2 and a _third flat portion P3. The first plateau P1 defines a _first side 5 at its lower edge and the _second plateau P2 defines a second side 6 at its lower edge. The _third flat portion P3 is interposed between and connects the _first flat portion P1 and the _second flat portion P2.

As shown in FIG. 1, the shape of the _first flat portion P1 is a trapezoid in which the lower base B1L is longer than the upper base _B1U , and the shape of the _second flat portion P2 is such that the lower base _B2L is longer than the upper base _B1U . B A longer trapezoid than _2U . That is, the trapezoidal bottom B1L of the first flat portion P1 forms the _first side 5 of the hexagon, and the trapezoidal bottom _B2L of the _second flat portion P2 _forms the second side 6 of the hexagon. Eggplant. The trapezoidal upper base _B1U of the _first flat portion P1 and the trapezoidal upper base _B2U of the _second flat portion P2 are positioned on the upper edge _2U of the cell wall 2 and each form one side of the 14-sided polygon. . In the illustrated example, the trapezoid is an isosceles trapezoid, but the trapezoids of the _first flat portion P1 and the _second flat portion P2 are not limited to isosceles trapezoids.

The shape of the _third flat portion P3 is triangular. The triangle shares a vertex with a hexagon, and its base B3 is located on the upper edge _2U of the cell wall ₂ and forms one side of a 14-sided polygon. In this embodiment, one of the two sides of the _triangle of the _third flat portion P3 other than the base B3 forms the leg of the trapezoid of the _first flat portion P1, and the other forms the trapezoid of the _second flat portion P2. legs.

Focusing on _one cell 3, as shown in _FIG . , and eight _third plateaus P3. That is, each 14-sided polygon has two _first flat portions P1 at the trapezoidal upper base _B1U , four _second flat portions P2 at the trapezoidal upper base _B2U , and eight _third flat portions P3. The base of the _triangle is B3.

As the material of the honeycomb core 1, that is, the material of the cell walls 2, for example, sheet materials such as metal foil such as aluminum, fiber reinforced plastic (FRP) sheets, and paper materials can be used. The thickness of the sheet material is not particularly limited, but is, for example, about 0.01 mm to 0.5 mm.

As the material of the FRP sheet, for example, aramid fiber reinforced plastic (AFRP), carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP), etc. can be used. Examples of matrix resins that can be used include thermosetting resins such as epoxy resins, polyester resins, vinyl ester resins, and phenol resins, and thermoplastic resins such as polypropylene resins, polyamide resins, polycarbonate resins, and polyetherimide resins. can.

As the paper material, for example, kraft paper, mixed paper, or the like can be used. Examples of mixed paper include mixed paper made of synthetic fibers, carbon fibers, glass fibers, etc., and pulp fibers. The paper material may be imparted with water resistance, heat resistance, flame retardancy, noncombustibility, etc. by coating, impregnating, laminating, or the like with a synthetic resin such as an acrylic resin, a polyurethane resin, or a phenol resin.

The honeycomb core 1 can be manufactured by a well-known method such as a corrugating method, a stretching method, or a construction method using origami engineering. Hereinafter, as an example, a method of manufacturing the honeycomb core 1 made of an aluminum sheet by a stretching method will be described.

In this method, a block 7 as shown in FIG. 4 is prepared and expanded in the expansion direction W to obtain the honeycomb core 1 . The block 7 is a laminate formed by laminating a plurality of strip-shaped sheet materials 7a made of aluminum sheets.

A dark gray area and a light gray area (see FIG. 4) of the block 7 are areas in which gaps provided with the adhesive Ad and gaps without the adhesive Ad are alternately arranged in the stacking direction. For example, in the dark gray area, the top surfaces of the odd-numbered layers and the bottom surfaces of the even-numbered layers are bonded with the adhesive Ad. On the other hand, the bottom surfaces of the odd-numbered layers and the top surfaces of the even-numbered layers are not bonded. In the light gray area, the bottom surfaces of the odd-numbered layers and the top surfaces of the even-numbered layers counted from the top are bonded with adhesive Ad, and the top surfaces of the odd-numbered layers and the bottom surfaces of the even-numbered layers are bonded together. It is not glued with.

In FIG. 4, broken lines indicate valley fold lines, and solid lines indicate mountain fold lines. In odd-numbered layers counted from the top, fold lines of the same kind are provided at the same positions as the uppermost sheet material 7a. Specifically, the polygonal line that is the boundary line of the dark gray area and the polygonal line that is positioned immediately adjacent thereto are the polygonal lines of the mountain fold. Also, the polygonal line that is the boundary line of the light gray area and the polygonal line that is positioned immediately adjacent thereto are the polygonal lines of the valley fold. On the other hand, in even-numbered layers counted from the top, folding lines of different types are provided at the same positions as the uppermost sheet material 7a. Specifically, the polygonal line that is the boundary line of the dark gray area and the polygonal line that is located immediately adjacent to it are the polygonal lines of the valley fold, and the polygonal line that is the boundary line of the light gray area and the polygonal line that is located immediately adjacent to it The polygonal line that forms the mountain fold is the polygonal line of the mountain fold.

Fold lines (also referred to as crease lines) are formed in advance at the positions of the fold lines of the sheet material 7a of each layer. The crease is not particularly limited as long as it causes the sheet material 7a to bend along the crease when the block 7 is stretched. For example, if the sheet material 7a is made of an aluminum sheet, the folds may be linear grooves formed on the surface of the sheet material 7a. Such grooves can be formed, for example, by pressing a cutting edge such as a ruled line cutting edge against the surface of the sheet material 7a.

In the stretching step, the blocks 7 are stretched by applying a tensile force to the blocks 7 in the stacking direction of the sheet materials 7a. The direction in which the tensile force acts at this time corresponds to the stretching direction W. As shown in FIG. When the block 7 is expanded, the dark gray and light gray regions of each sheet material 7a become the _first flat portion P1, and the other regions become the _second flat portion P2 and the third flat portion P. becomes ₃ . The crease formed in the sheet material 7a becomes the ridge line 4 of the cell wall 2. As shown in FIG. In addition, the non-bonded areas of the surfaces of the sheet materials 7a adjacent to each other in the stacking direction that face each other in the stacking direction expand in the spreading direction W to define the cells 3 .

A curved honeycomb panel having a sandwich structure can be obtained by adhering skin materials (not shown) to both surfaces of the obtained honeycomb core 1 . The material of the skin material is not particularly limited, and can be appropriately selected and used from, for example, those exemplified as the material of the sheet material 7a.

The adhesive Ad can be appropriately selected according to the materials of the honeycomb core 1 and skin material. Typical examples include thermoplastic resin adhesives such as vinyl acetate, thermosetting resin adhesives such as epoxy and polyurethane, and synthetic rubber adhesives such as nitrile rubber and butyl rubber. Note that the honeycomb core 1 and the skin material may be heat-sealed by heating or bonded with a solvent. A brazing material such as solder may be used.

The effects of the first embodiment will be described below.

(1) In this embodiment, the cell walls 2 are bent along straight ridgelines 4 extending from the vertices of the hexagon to the vertices of the 14-sided polygon. Three edges 4 extend from each vertex of the hexagon. Therefore, as shown in FIG. 1, the cell wall ₂ is always formed by the triangular third flat portion P between the _first trapezoidal flat portion P1 and the second trapezoidal flat portion P2 due to the ridge line 4. ₃ intervening. 5, the base B3 of the _third flat portion _P3 is interposed between the upper base _B1U of the _first flat portion P1 and the upper base _B2U of the _second flat portion P2. and connect them.

Therefore, according to the present embodiment, by appropriately adjusting the length L ₁ (see FIG. 5) of the upper base B _1U and the length L ₂ (see FIG. 5) of the upper base B _2U , the length of the base B ₃ The length L ₃ (see FIG. 5) and the position of the intersection between the base B ₃ and the upper base B _1U (or the upper base B _2U ) can be arbitrarily set. _In addition to the adjustment of the _lengths L ₁ and L ₂ , as indicated by the _two -dot chain line in FIG. The relative position of the upper base B _2U with respect to the upper base B _1U can also be arbitrarily set by adjusting the tilt angle.

That is, the present embodiment arbitrarily adjusts the relative position of the upper base B _2U to the upper base B _1U regardless of the azimuth angle of the upper base B _1U and the upper base B _2U (or independently of the azimuth angle). be able to. The “azimuth angle” _{means that each side (upper base B 1U ,} upper base B _2U , base B ₃ , etc.) is in the ribbon direction L or It is an angle formed with respect to the extension direction W.

Therefore, according to the present embodiment, the angle of the upper base _B1U with respect to the lower base _B1L of the _first flat portion P1 and the angle of the upper base _B2U with respect to the lower base _B2L of the _second flat portion P2 are maintained. Meanwhile, the relative position of the upper base B _2U with respect to the upper base B _1U can be arbitrarily adjusted. In other words, the upper base B _1U and the lower base B _1L and the upper base B _2U and the lower base B _2L are prevented from being in a twisted positional relationship, and the upper base B _1U and the upper base B _2U are arranged in the ribbon direction. It can be made to move toward and away from L, or to move toward and away from in the deployment direction W. That is, according to this embodiment, the curved honeycomb core 1 curved with a desired curvature can be formed without the cell walls 2 being greatly twisted. Further, according to the honeycomb core 1, since the cell walls 2 do not have curved surfaces that are greatly twisted, the strength of the curved honeycomb panel can be improved.

(2) In addition, in this embodiment, the cell walls 2 are bent along the straight ridge lines 4 . Therefore, the cell wall 2 is formed with a bent cross-sectional portion extending along the ridgeline 4 from the upper edge _2U to the lower edge _2L . The bent cross-sectional portion exhibits higher rigidity than the flat portion or the curved surface portion with respect to the load in its extending direction. Thus, according to the present embodiment, instead of the twisted curved surface, the cell wall 2 can be formed with a curved cross section extending from the upper edge _2U to the lower edge _2L . The strength and stiffness of T against the load can be increased.

(3) Furthermore, in the present embodiment, the shape of the _first flat portion P1 parallel to the ribbon direction L is a trapezoid in which the lower base _B1L is longer than the upper base _B1U . Therefore, the perimeter of the 14-sided polygon is longer than the perimeter of the hexagon. Therefore, according to the present embodiment, under predetermined conditions, the area of the upper end face (14-sided opening) of each cell 3 on the upper surface _1U of the honeycomb core 1 is equal to the area on the lower surface _1L of the honeycomb core 1. It can be made larger than the area of the lower end face (hexagonal opening) of each cell 3 . This makes it possible to form a curved honeycomb core 1 in which the area of the upper surface _1U is larger than the area of the lower surface _1L .

(4) In the core material of Patent Document 1, the upper base and lower base of the trapezoid forming the intermediate plane have a twisted positional relationship. On the intermediate surface, which is a curved surface, the intersection of the upper base of the intermediate surface and the upper base of the convex surface (hereinafter referred to as the first vertex) and the intersection of the lower base of the intermediate surface and the lower base of the concave surface (hereinafter referred to as the second vertex) A diagonal line connecting is a curve. Therefore, the linear distance between the first vertex and the second vertex is shorter than the length of the diagonal connecting the first vertex and the second vertex. Similarly, the diagonal line connecting the intersection of the upper base of the intermediate surface and the upper base of the concave surface (hereinafter referred to as the third vertex) and the intersection of the lower base of the intermediate surface and the lower base of the convex surface (hereinafter referred to as the fourth vertex) is , becomes a curve. Therefore, the straight line distance between the third vertex and the fourth vertex is shorter than the length of the diagonal connecting the third vertex and the fourth vertex. Therefore, the actual distance between the first and third vertices at both ends of the upper base is shorter than the designed distance (the length of the upper base). Also, the actual distance between the second and fourth vertices at both ends of the base is shorter than the designed distance (the length of the base). The absolute value of the difference between the actual distance and the design distance (the amount of decrease in the distance between the end points) is greater for the longer upper base than for the lower base.

In this way, the upper edge side of the core material shrinks more than the lower edge side due to the difference in the amount of decrease in the distance between the end points of the upper base and the lower base of the intermediate surface. Therefore, in the above core material, for example, when the outer surface of the honeycomb panel is given a curvature that is convex in the direction from the inner surface to the outer surface in the circumferential direction, in a direction perpendicular to the circumferential direction and parallel to the outer surface, A convex warpage occurs in the direction from the outer surface to the inner surface. That is, according to the core material of Patent Document 1, there is a problem that only a saddle-shaped curved honeycomb panel can be manufactured.

In contrast, in the present embodiment, the shape of the _first flat portion P1 parallel to the ribbon direction L is a trapezoid in which the lower base _B1L is longer than the upper base _B1U , and the shape of the first flat portion P1 parallel to the ribbon direction L is not parallel to the ribbon direction L. ₂ The shape of the flat portion P2 is a trapezoid in which the lower base _B2L is longer than the upper base _B2U . Therefore, as shown in FIG. 1, the shape of the portion of the upper end edge _2U of the cell wall 2 that connects the upper base _B1U and the upper base _{B2U (} the base B3 in this embodiment) is the shape of the cell wall 2 In the _three -dimensional space, the shape is closer to a straight line than the shape of the portion E3 corresponding to the portion of the lower edge _2L . That is, according to the present embodiment, the distance between the upper base B _1U and the upper base B _2U is defined by the region E ₁ of the lower base B _1L facing the upper base B 1U in the height direction of the trapezoid and the lower base B _1U . It can be made larger than the distance between the upper base B _2U of the base B _2L and the area E ₂ facing in the height direction of the trapezoid.

Thus, according to the present embodiment, the honeycomb core 1 is not curved convexly upward in both the ribbon direction L and the extending direction W, nor is it curved in either the ribbon direction L or the extending direction W. Only on the other side can it be curved convexly upwards. That is, the spherical or cylindrical honeycomb core 1 can be formed without the cell walls 2 being greatly twisted. Incidentally, the cylindrical honeycomb core 1 can also be formed into a hollow shaft shape by connecting, for example, in the circumferential direction.

Hereinafter, the above effect will be confirmed by simple calculation with reference to FIGS. 4 and 5. FIG. Here, the shape of the _first flat portion P1 and the _second flat portion P2 is assumed to be an isosceles trapezoid, and the shape of each cell 3 on the lower surface _1L of the honeycomb core 1 is assumed to be a regular hexagon. Further, as shown in FIG. 4, the angle of the _{first flat portion P1 with respect to the thickness direction T of the trapezoidal leg is θ 1 ,} and the angle of the _second flat portion P2 with respect to the thickness direction T of the trapezoidal leg is θ ₂ , the height of the trapezoid is H, and the length of one side of the hexagon is A. In this embodiment, 0<θ ₁ , θ ₂ .

At this time, the length L1 of the _upper base _B1U of the _first flat portion P1 is
L ₁ = A-2H tan θ ₁ (1)
_The length L2 of the upper base _B2U of the _second flat portion P2 is
L ₂ = A-2H tan θ ₂ (2)
The length L3 of the base _B3 of the _third flat portion _P3 is
L ₃ =H (tan θ ₁ +tan θ ₂ ) (3)
can be expressed as In this embodiment, since 0<L ₁ , L ₂ , the range of θ ₁ , θ ₂ is 0<θ ₁ , θ ₂ <tan ⁻¹ (A/ 2H) <90°.

In FIG. 5, when the azimuth angle is expressed as an angle with respect to the deployment direction W (clockwise is positive), the azimuth angle of the upper base _B1U of the _first flat portion P1 is 90°, and the azimuth angle of the upper base B1U of the _second flat portion P2 The azimuth angle of the base _B2U is ₃₀ °, and the azimuth angle of the base B3 of the _third flat portion P3 is α° (0°<α<90°). The black circle in FIG. 5 indicates the midpoint of the upper base _B1U of the trapezoid of the _first flat portion P1.

Then, the distance _LU in the ribbon direction L between the midpoints of the upper base _B1U of the _first flat portion P1 is
L _U = L ₁ + (1/2) L ₂ + 2L ₃ sinα (4)
The distance _WU in the extension direction W between the midpoints of the upper base _B1U of the _first flat portion P1 is
WU=(√3/ ₂ )L2+ _2L3cosα ( ₅ )
The distance L _L in the ribbon direction _L between the midpoints of the bottom B1L of the _first flat portion P1 is
L _L = (3/2) A (6)
The distance W _L in the extension direction W between the midpoints of the lower base _B1L of the _first flat portion P1 is
W _L = (√3/2) A (7)
can be expressed as

The difference ΔL between _LU and _LL is
ΔL = L _U - L _L (8)
Formula (8) is obtained from formulas (1) to (4) and (6) as
ΔL=H[2tan θ ₁ (sin α−1)+tan θ ₂ (2sin α−1)] (9)
can be expressed as On the other hand, the difference _ΔW between _WU and WL is
_{ΔW =} WU-WL (10)
Equation (10) is obtained from Equations (2), (3), (5), and (7) as
ΔW=H[2 tan θ ₁ cos α + tan θ ₂ (2 cos α−√3)] (11)
can be expressed as

A line segment connecting the midpoint of the upper base _B1U of the _first flat portion P1 and the midpoint of the lower base _B1L is defined as the central axis Ax of the _first flat portion P1, and the extension of the line segment is the honeycomb core 1. It shall pass through the center of curvature of the curved surface. ₅ and the central axis Ax of the _first flat portion P1 drawn in the lower side of FIG. 5 form an angle in three-dimensional space. is called a relative tilt angle.

Then, the component θ _L [rad] of the relative tilt angle in the ribbon direction L is
_θL = ΔL/H (12)
Substituting ΔL in equation (9) into this, we get
θ _L = 2 tan θ ₁ (sin α-1) + tan θ ₂ (2 sin α-1) (13)
can be expressed as

Further, the component θ _W [rad] of the relative tilt angle in the extending direction W is
θ _W = ΔW/H (14)
Substituting ΔW in equation (11) into this, we get
θ _W = 2 tan θ ₁ cos α + tan θ ₂ (2 cos α - √ 3) (15)
can be expressed as

First, the curvature in the expansion direction W when the curvature in the ribbon direction L of the honeycomb core 1 becomes zero is investigated. From equation (13),
tan θ ₁ = [(sin α−1/2)/(1−sin α)] tan θ ₂ (16)
is satisfied, θ _L =0 and the curvature in the ribbon direction L becomes zero. In addition, since 0<θ ₁ , θ ₂ <90°, the range of α in which Equation (16) holds is limited to 30°<α<90°.

At this time, the component θ _W in the extension direction W of the relative tilt angle is obtained by substituting equation (16) into equation (15),
θ _W = [(2 sin α−1) cos α/(1− sin α)+2 cos α−√3] tan θ ₂ (17)
can be expressed as Since 0<θ ₂ <90° and the range of α is 30°<α<90°, the right side of Equation (17) is always positive. That is, θ _W takes a positive value.

As described above, in this embodiment, when the relationship of formula (16) is satisfied, the honeycomb core 1 can be bent convexly upward in the expansion direction W while the curvature in the ribbon direction L of the honeycomb core 1 is zero.

Next, the curvature in the ribbon direction L when the curvature in the extending direction W of the honeycomb core 1 becomes zero is examined. From equation (15),
tan θ ₁ = [(√3/2−cos α)/cos α] tan θ ₂ (18)
is satisfied, θ _W =0 and the curvature in the spreading direction W becomes zero. In addition, since 0<θ ₁ , θ ₂ <90°, the range of α in which Equation (18) holds is limited to 30°<α<90°.

At this time, the component θL of the relative tilt angle in the ribbon direction _L is obtained by substituting equation (18) into equation (13),
θ _L = [(√3−2 cos α)(sin α−1)/cos α+(2 sin α−1)] tan θ ₂ (19)
can be expressed as Since 0<θ ₂ <90° and the range of α is 30°<α<90°, the right side of Equation (19) is always positive. That is, _θL takes a positive value.

As described above, in the present embodiment, the honeycomb core 1 can be curved convexly upward in the ribbon direction L while the curvature in the extending direction W of the honeycomb core 1 is set to zero when the relationship of formula (18) is satisfied.

Next, conditions under which both the curvature in the ribbon direction L and the curvature in the extending direction W of the honeycomb core 1 are positive will be investigated. Comparing the coefficient of tan θ ₂ on the right side of equation (16) and the coefficient of tan θ ₂ on the right side of equation (18), in the range of 30°<α<90°,
0<(√3/2-cosα)/cosα<(sinα-1/2)/(1-sinα) (20)
always holds. That is, the coefficient of tan θ ₂ on the right side of equation (16) is always greater than the coefficient of tan θ ₂ on the right side of equation (18).

Therefore, in the range of 30°<α<90°, in Equation (16), the left side is larger than the right side, that is,
tan θ ₁ > [(sin α−1/2)/(1−sin α)] tan θ ₂ (21)
If θ ₁ and θ ₂ are selected so as to satisfy
tan θ ₁ > [(√3/2−cos α)/cos α] tan θ ₂ (22)
always holds. Therefore, if θ ₁ and θ ₂ are selected so as to satisfy equation (21), from equations (13) and (15),
0< _θL and 0< _θW
holds.

As described above, in the present embodiment, the honeycomb core 1 can be curved convexly upward in both the ribbon direction L and the extending direction W when the relationship of formula (21) is satisfied.

(5) Further, according to the present embodiment, when manufacturing a curved honeycomb core, it is not necessary to trim the sheet material in advance into a curved shape to match the curvature of the curved honeycomb panel. Therefore, the material yield can be greatly improved compared to the conventional honeycomb core structure.

Several modifications of the first embodiment will be described below. Only the configuration different from the first embodiment will be described in each modification.

In the first modification, the shape of the _first flat portion P1 may be triangular. In this case, the base of the triangle forms the first side ₅ of the hexagon, and the sides other than the base form the sides other than the base B3 of the triangle of the _third flat portion P3. Also, the apex is positioned on the upper edge _2U of the cell wall 2 .

In the second modification, any _two of the four second flat portions P2 of the cell wall 2 surrounding one cell 3 may have a triangular shape. In this case, the base of the triangle forms the second side ₆ of the hexagon, and the sides other than the base form the sides other than the base B3 of the triangle of the _third flat portion P3. Also, the apex is positioned on the upper edge _2U of the cell wall 2 .

In the first and second modifications, the contour shape of each cell 3 defined by the upper edge _2U of the cell wall 2 on the upper surface _1U of the honeycomb core 1 is a dodecagon (n=1, k=2). Each edge line 4 of the cell wall 2 extends from the vertex of the hexagon to each vertex of the dodecagon, and three ridge lines 4 extend from each vertex of the hexagon.

In a third modification, all four of the four _second flat portions P2 of the cell wall 2 surrounding one cell 3 may be triangular in shape. In this case, the base of the triangle forms the second side ₆ of the hexagon, and the sides other than the base form the sides other than the base B3 of the triangle of the _third flat portion P3. Also, the apex is positioned on the upper edge _2U of the cell wall 2 .

In this modification, the contour shape of each cell 3 defined by the upper edge _2U of the cell wall 2 on the upper surface _1U of the honeycomb core 1 is a decagon (n=1, k=1). Each ridgeline 4 of the cell wall 2 extends from the apex of the hexagon to each apex of the decagon, and three ridgelines 4 extend from each apex of the hexagon.

A fourth modification may be a combination of the first modification and the second modification. That is, both the shape of the two _first flat portions P1 and the shape of the _two second flat portions P2 may be triangles. In this modification, the contour shape of each cell 3 defined by the upper edge _2U of the cell wall 2 on the upper surface _1U of the honeycomb core 1 is a decagon (n=1, k=1). Each ridgeline 4 of the cell wall 2 extends from the apex of the hexagon to each apex of the decagon, and three ridgelines 4 extend from each apex of the hexagon.

The fifth modified example may be a combination of the first modified example and the third modified example. That is, both the shape of the two _first flat portions P1 and the shape of the four _second flat portions P2 may be triangular. In this modification, the contour shape of each cell 3 defined by the upper edge _2U of the cell wall 2 on the upper surface _1U of the honeycomb core 1 is an octagon (n=1, k=0). Each edge line 4 of the cell wall 2 extends from the vertex of the hexagon to each vertex of the octagon, and three ridge lines 4 extend from each vertex of the hexagon.

As described above, in the first to fifth modifications, one or both of the shape of the _first flat portion P1 and the shape of the _second flat portion P2 are triangular. The triangular first flat portion P ₁ (or the second flat portion P ₂ ) is a trapezoidal first embodiment in which the length of the upper base B _1U (or the length of the upper base B _2U ) is infinitely close to zero. substantially equal to the first plateau P ₁ (or the second plateau P ₂ ) of the morphology. Therefore, according to the first to fifth modifications, for the same reason as in the first embodiment, the same effect as in the first embodiment can be obtained. The triangles of the _first flat portion P1 and the _second flat portion P2 in the first to fifth modifications are not limited to isosceles triangles.

Although n=1 in the first embodiment and the first to fifth modifications, n may be an integer of 2 or more in the sixth modification. For example, the third flat portion P3 in the first embodiment and the first to fifth modifications connects the vertex of the _triangle of the _third flat portion P3 and the (n− ₁ ) points on the base B3. It may be divided into n fourth flat portions by (n−1) ridgelines 4 . Each of the n fourth flat portions has a triangular shape. Each triangle shares a vertex with a hexagon and its base lies on the upper edge 2 _U of the cell wall 2 .

In the sixth modification, the contour shape of each cell 3 defined by the upper edge _2U of the cell wall 2 on the upper surface _1U of the honeycomb core 1 is a (8n+2k) polygon. Each edge line 4 of the cell wall 2 extends from the vertex of the hexagon to each vertex of the (8n+2k) polygon, and from each vertex of the hexagon, (2n+1) edge lines 4 extend.

In the first embodiment and the first to fifth modifications, even if the _third flat part P3 is divided into n fourth flat parts, the azimuth angle of the upper base _B1U and the upper base _B2U , and the relative position of the upper base B _2U to the upper base B _1U can be arbitrarily adjusted. Also in the sixth modification, the perimeter of the (8n+2k) polygon is longer than the perimeter of the hexagon. Furthermore, the shape of the portion connecting the upper base _B1U and the upper base _B2U of the upper edge _2U of the cell wall 2 is still the same as the portion E corresponding to that portion of the lower edge _2L of the cell wall 2. It is more linear in 3D space than the shape of ₃ . Therefore, according to the sixth modification, for the same reasons as those of the first embodiment and the first to fifth modifications, the same effects as those can be obtained.

Next, honeycomb cores 1 according to second and third embodiments and other embodiments will be described. In the description of each embodiment below, only the configurations that are different from the preceding embodiments and modifications (hereinafter referred to as the preceding embodiments and the like) will be described, and the elements having the same functions as the elements already described in the preceding embodiments and the like will be described. Elements are denoted by the same reference numerals, and descriptions thereof are omitted.

<Second embodiment>
In the second embodiment, as shown in FIG. 6, the shape of the _first flat portion P1 in the first embodiment shown in FIGS. 1 to 5 is made rectangular.

Since the second embodiment has at least the configurations described in (1), (2), and (5) above, it is possible to obtain the effects described in (1), (2), and (5) above.

(6) According to the second embodiment, the shape of the _first flat portion P1 of the cell wall 2 parallel to the ribbon direction L is rectangular, so that the perimeter of the 14-sided polygon is the perimeter of the hexagon. can be made equal to Therefore, under predetermined conditions, the honeycomb core 1 can be curved upwardly convexly in one of the ribbon direction L and the extending direction W, and curved downwardly convexly in the other direction. That is, according to the second embodiment, the honeycomb core 1 can be formed in a saddle shape without causing the cell walls 2 to be greatly twisted.

The effect of (6) above is confirmed using the simple calculation formula described above. Now, since the shape of the _first flat portion P1 is a rectangle, θ1= ₀ . At this time, equations (13) and (15) are
θ _L = tan θ ₂ (2 sin α-1) (23)
θ _W = tan θ ₂ (2 cos α-√3) (24)
becomes. Multiplying both sides of equations (23) and (24) yields
θ _L θ _W = (2 sin α-1) (2 cos α-√3) tan ² θ ₂ (25)

Examining the sign on the right side of equation (25), _first , since 0<θ2,
0<tan ² θ ₂ (26)
In addition, the following relationship holds within the range of 0°<α<90°.
(2sinα-1) (2cosα-√3) ≤ 0 (equals hold at α = 30°) …(27)
Therefore, from equations (25), (26) and (27),
θ _L θ _W ≤ 0 (equals are established at α = 30°) (28)
holds.

That is, in the second embodiment (θ ₁ =0, 0<θ ₂ ), in the range of 0°<α<90° (excluding α=30°), the component θ _L of the relative tilt angle in the ribbon direction L is The sign and the sign of the component θ _W in the spreading direction W are always opposite. Therefore, in the second embodiment, as described in (6) above, the honeycomb core 1 is curved upwardly convexly in either the ribbon direction L or the extending direction W, and is curved downwardly convexly in the other direction. can be made

In addition, in the sixth modified example of the first embodiment, the second to third modified examples of the first embodiment, and the sixth modified example thereof, the shape of the _first flat portion P1 is rectangular. However, for the same reason as above, the same effect as in the second embodiment can be obtained.

<Third Embodiment>
In the third embodiment, the shape of the _second flat portion P2 in the first embodiment shown in FIGS. 1 to 5 is made rectangular.

Since the third embodiment has at least the configurations described in (1), (2), (3), and (5) above, it is possible to obtain the effects described in (1), (2), (3), and (5) above. can be done.

(7) Further, according to the third embodiment, the honeycomb core 1 can be curved upwardly convexly in one of the ribbon direction L and the extending direction W, and curved downwardly convexly in the other direction. That is, according to the third embodiment, the honeycomb core 1 can be formed in a saddle shape without causing large twists in the cell walls 2 .

(8) Further, according to the third embodiment, the absolute value of the ratio of the component θL in the ribbon direction _L to the component θW in the extension direction _W of the relative displacement angle is smaller than that in the second embodiment. of honeycomb core 1 can be formed. In other words, according to the third embodiment, when the curvature in the ribbon direction L is the same as in the second embodiment, the saddle-shaped honeycomb core 1 having a larger curvature in the extending direction W can be formed. can be done. Alternatively, a saddle-shaped honeycomb core 1 having a smaller curvature in the ribbon direction L can be formed when the curvature in the spreading direction W is the same.

The effects of (7) and (8) above are confirmed using the above-described simple calculation formula. Now, since the shape of the _second flat portion P2 is rectangular, θ2 ₌ 0. At this time, equations (13) and (15) are
θ _L = 2 tan θ ₁ (sin α-1) (29)
θ _W = 2 tan θ ₁ cos α (30)
becomes. Multiplying both sides of equations (29) and (30) yields
θ _L θ _W = 4 cos α (sin α - 1) tan ² θ ₁ (31)

Examining the sign on the right side of equation (31), _first , since 0<θ1,
0<tan ² θ ₁ (32)
In addition, the following relationship holds within the range of 0°<α<90°.
cosα(sinα−1)<0 (33)
Therefore, from equations (31), (32) and (33),
θ _L θ _W <0 (34)
holds.

That is, in the third embodiment (0<θ ₁ , θ ₂ =0), in the range of 0°<α<90°, the sign of the component θL in the ribbon direction _L and the component θ The sign of _W is always reversed. Therefore, in the third embodiment, as described in (7) above, the honeycomb core 1 is curved upwardly convexly in either the ribbon direction L or the extending direction W, and is curved downwardly convexly in the other direction. can be made

Next, the ratio of the component θL in the ribbon direction _L and the component θW in the spreading direction _W of the relative tilt angle will be examined. The ratio R ₃ in the third embodiment is obtained from equations (29) and (30) as
R ₃ = θ _L / θ _W = (sinα-1)/cosα (35)
On the other hand, the ratio R ₂ in the second embodiment is obtained from equations (23) and (24) as
R ₂ = θ _L / θ _W = (2sinα-1)/(2cosα-√3) (36)
can be expressed as
Comparing the magnitudes of R ₂ and R ₃ in the range of 0°<α<90° (excluding α=30°), R ₂ <R ₃ <0 from equations (35) and (36).

Therefore, according to the third embodiment, as described in (8) above, the absolute value of the ratio of the component θL in the ribbon direction _L to the component θW in the extension direction _W of the relative displacement angle is the same as that in the second embodiment. A saddle-shaped honeycomb core 1 smaller than that of .

In addition, in the sixth modification of the first embodiment, the first modification of the first embodiment, and the sixth modification thereof, even if the shape of the _second flat portion P2 is rectangular, the above-described For the same reason as above, the same effect as in the third embodiment can be obtained.

<Other embodiments>
As a honeycomb core 1 according to another embodiment, there is a combination of two or more embodiments selected from the preceding embodiments.

Further, in a honeycomb core 1 according to another embodiment, there is a conventional planar honeycomb core 1 that includes the preceding embodiment and the like in part. For example, as shown in FIG. 7, in the honeycomb panel 10, the first embodiment or its modification is applied to the region 11 having a cylindrical shape, and the first embodiment or its modification is applied to the region 12 having a spherical shape. Modifications may be applied. Also, the second embodiment, third embodiment, or modifications thereof may be applied to the region 13 having a saddle shape.

In the above embodiments and modifications, the plurality of hexagons defined by the cell walls 2 on the lower surface _1L of the honeycomb core 1 do not necessarily have to be congruent. Also, the plurality of X- _gons defined by the cell walls 2 on the upper surface 1U of the honeycomb core 1 may not necessarily be congruent. Furthermore, the hexagon does not have to be a regular hexagon.

The above embodiments and modifications are merely examples described to facilitate understanding of the invention. The technical scope of the invention is not limited to the specific technical matters disclosed in the above embodiments and modifications, but also includes various modifications, alterations, alternative techniques, etc. that can be easily derived therefrom.

1 honeycomb core, 1 _L lower surface (side surface on one side in thickness direction), 1 _U upper surface (side surface on other side in thickness direction)
2 cell wall, 2 _L lower edge (edge on one side in thickness direction), 3 cell, 4 ridgeline, 5 first side P ₁ first flat portion, B _1L lower base (base on one side in thickness direction), B _1U upper base (base on the other side in the thickness direction)
P ₂ second flat part, B _2L lower base (base on one side in thickness direction), B _2U upper base (base on other side in thickness direction)
L ribbon direction, T thickness direction

Claims (5)

A honeycomb core comprising cell walls and a plurality of cells partitioned by the cell walls, wherein at least part of the honeycomb core comprises:
Each of the plurality of cells defined by the cell walls on one side surface in the thickness direction of the honeycomb core has a hexagonal contour shape,
Each of the plurality of cells defined by the cell walls on the side surface of the honeycomb core on the other side in the thickness direction has an X-sided contour shape,
The cell walls are bent along linear ridges extending from the vertices of the hexagon to the vertices of the X-gon,
The honeycomb core, wherein Y ridges extend from each vertex of the hexagon.
However, X: 8n+2k, Y: 2n+1 (n is a natural number, k is an integer from 0 to 3) The hexagon has a first side parallel to the ribbon direction of the honeycomb core,
The cell wall includes a first flat portion defining the first side at the edge on one side in the thickness direction,
2. The shape of the first flat portion is a trapezoid whose base on one side in the thickness direction is longer than the base on the other side in the thickness direction, or a triangle whose base is on one side in the thickness direction. The honeycomb core described in . the hexagon has a second side that is not parallel to the ribbon direction of the honeycomb core;
The cell wall includes a second flat portion defining the second side at the edge on one side in the thickness direction,
2. The shape of the second flat portion is a trapezoid whose base on one side in the thickness direction is longer than the base on the other side in the thickness direction, or a triangle whose base is on one side in the thickness direction. The honeycomb core described in . the hexagon has a second side that is not parallel to the ribbon direction of the honeycomb core;
The cell wall includes a second flat portion defining the second side at the edge on one side in the thickness direction,
The honeycomb core according to claim 2, wherein the shape of the second flat portion is rectangular. The hexagon has a first side parallel to the ribbon direction of the honeycomb core,
The cell wall includes a first flat portion defining the first side at the edge on one side in the thickness direction,
The honeycomb core according to claim 1, wherein the shape of the first flat portion is rectangular.

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