Hollow structure
Patent Information
- Authority / Receiving Office
- TH · TH
- Patent Type
- Applications
- Current Assignee / Owner
- KOTOBUKIYA FRONTE CO LTD
- Filing Date
- 2024-08-29
- Publication Date
- 2026-07-20
Smart Images
Figure 00000001_0000 
Figure 00000023_0000 
Figure 00000023_0001
Abstract
Description
hollow structure
[0001] The present invention relates to a hollow structure.
[0002] Conventionally, hollow structures have been known that include a core layer in which a plurality of cells, each having a polygonal cylindrical shape such as a hexagonal cylindrical shape or a cylindrical shape, are arranged in rows. Such hollow structures are lightweight and have a certain strength in the thickness direction of the layer due to the structure of the core layer, and therefore are widely used in interior and exterior components of automobiles, panel materials for containers, boxes, etc., building materials, etc.
[0003] Patent Document 1 describes a sandwich-type structural composite panel having such a core layer, the panel comprising: a first outer layer having a first outer surface; a second outer layer having a second outer surface; a core having a number of cavities positioned between the outer layers, the outer layers and the core being joined by press molding, with collapsed portions of the panel having reduced thickness forming a pattern of recesses on the second outer surface of the second outer layer; and a plurality of reinforcing supports bonded or joined to the second outer layer within the pattern of recesses, the reinforcing supports being held in their respective recesses without the need for additional supports in the storage area below the luggage compartment floor panel, and the reinforcing supports being sized, shaped, and arranged within the pattern of recesses to provide the panel with strength to resist deflection from loads in various positions and directions on the first outer surface.
[0004] U.S. Patent No. 8,808,834
[0005] In the composite panel described in Patent Document 1, the open end of the recess formed in the second outer surface remains open, so when a load is applied from the first outer surface, the open end of the recess opens up, resulting in a problem with the strength of the composite panel. Also, in order to hold the reinforcing support in the recess whose open end remains open, it is necessary to fix the reinforcing support to the second outer layer using adhesive or fasteners such as screws, which results in problems with the number of parts and manufacturing steps for the composite panel.
[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a hollow structure that can exhibit excellent strength while maintaining a light weight and that can be easily manufactured.
[0007] In order to achieve the above-mentioned object, the hollow structure of the present invention comprises a core layer in which cylindrical cells are arranged in multiple rows, the core layer being formed of a material containing resin and having a recess on one side of the core layer, a reinforcing member located within the recess of the core layer, and a retaining member located in contact with both the one side of the core layer and at least a portion of the exposed portion of the reinforcing member from the recess, wherein the core layer is welded to the reinforcing member at the bottom surface of the recess, and the retaining member is adhered to at least a portion of the exposed portion of the reinforcing member.
[0008] At least a part of the exposed portion of the reinforcing member from the recess may be a surface exposed from the recess when the reinforcing member is completely embedded in the recess, or may be a partial surface of the exposed portion from the recess when the reinforcing member is partially embedded in the recess. The adhesion between the holding member and the reinforcing member may be welding using a molten material of the holding member, or may be adhesion using an adhesive.
[0009] The reinforcing members may be H-shaped beams, L-shaped beams, square beams, triangular beams, round beams, or semicircular beams.
[0010] The one surface of the core layer and a surface of the reinforcing member exposed from the recess may be flush with each other.
[0011] The core layer may be welded to the reinforcing member at a sidewall portion of the recess.
[0012] The holding member may be a film.
[0013] The retaining member may be an additional core layer having a plurality of rows of cylindrical cells arranged therein.
[0014] The core layer may be arranged such that the cells of the core layer are adjacent to each other to form rows, each of the cells of the core layer having a closed surface at one end and an open end at the other end, with rows of cells arranged with the open ends facing one surface of the core layer and rows of cells arranged with the open ends facing the other surface of the core layer being arranged in alternate rows.
[0015] The hollow structure according to the present invention may further include an accessory member joined to the reinforcing member via the holding member.
[0016] Thus, according to the present invention, by welding the reinforcing member to the core layer at the bottom surface of the recess in the core layer and adhering at least a portion of the exposed portion of the reinforcing member from the recess with a retaining member, it is possible to provide a hollow structure that can exhibit excellent strength while maintaining a lightweight design and that can be easily manufactured.
[0017] 12 is a cross-sectional view schematically showing an embodiment of a hollow structure according to the present invention. 13 is a perspective view schematically showing an example of a core layer of the hollow structure shown in FIG. 1. 14 is a cross-sectional view schematically showing another embodiment of a hollow structure according to the present invention. 15 is a cross-sectional view schematically showing another embodiment of a hollow structure according to the present invention. 16 is a cross-sectional view schematically showing another embodiment of a hollow structure according to the present invention. 17 is a cross-sectional view schematically showing another embodiment of a hollow structure according to the present invention. 18 is a cross-sectional view schematically showing another embodiment of a hollow structure according to the present invention. 19 is a cross-sectional view schematically showing another embodiment of a hollow structure according to the present invention. 20 is a cross-sectional view schematically showing an example of the hollow structure shown in FIG. 1 in which an accessory member is provided. 21 is a perspective view showing a manufacturing process of a core material used in the core layer of the hollow structure according to the present invention. 22 is a plan view schematically showing an example of a hollow structure according to the present invention using a core layer produced by the manufacturing process shown in FIG. 23. 24 is a perspective view schematically showing a core layer produced by the manufacturing process shown in FIG. 25. 26 is a cross-sectional view schematically showing the hollow structure of FIG. 26 along line A-A. FIG. 12 is a plan view schematically showing another example of a hollow structure according to the present invention, which uses a core layer produced in the manufacturing process shown in FIG. 11. FIG. 13 is a cross-sectional view schematically showing the hollow structure of FIG. 15 along line B-B. FIG. 14 is a schematic diagram illustrating a method for a bending test of a hollow structure according to the present invention. FIG. 15 is a schematic diagram illustrating a method for a bending test of a hollow structure according to the present invention. FIG. 16 is a graph showing measurement results of a bending test for examples and comparative examples of hollow structures according to the present invention. FIG. 17 is a graph showing measurement results of a bending test for examples and comparative examples of hollow structures according to the present invention.
[0018] An embodiment of a hollow structure according to the present invention will now be described with reference to the accompanying drawings, which are not intended to be drawn to scale unless otherwise specified.
[0019] As shown in FIG. 1 , the hollow structure of this embodiment includes a core layer 10 having cylindrical cells 20 arranged in multiple rows, a reinforcing member 50 located in a recess 23 formed in one surface 25 of the core layer 10, a retaining member 30 located in contact with both the surface 25 of the core layer 10 and an exposed surface 51 of the reinforcing member 50 from the recess 23, and, optionally, a skin layer 40 located in contact with the opposite surface 26 of the core layer. The core layer 10 may be a laminate including a core body 10C and two outer surface portions 10T, 10B located on either side of the core body 10C. The core layer 10 is welded to the reinforcing member 50 at the bottom of the recess 23. The retaining member 30 is bonded to the surface 25 of the core layer 10 and the exposed surface 51 of the reinforcing member 50, respectively.
[0020] The core body 10C is not particularly limited as long as it has cylindrical cells 20 arranged in multiple rows. The shape of the cells 20 can be, for example, a polygonal cylindrical shape such as a hexagonal cylindrical shape, or a cylindrical shape. The cells 20 are preferably arranged adjacent to each other in rows, and a core body 10C having hexagonal cylindrical cells 20 adjacent to each other as shown in FIG. 2 is particularly preferred. The core layer 10 is formed from a material containing a resin. Examples of resins include, but are not limited to, thermoplastic resins such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and polyvinyl chloride (PVC). Examples of resin-containing materials include composite materials of resin and fiber, and paper whose surface is coated (laminated) with resin. The materials of the core body 10C and the two outer surface portions 10T and 10B may be the same or different.
[0021] The thickness of the core layer 10 (the total thickness of the core body 10C and the two outer surface portions 10T and 10B) is not particularly limited, but is preferably in the range of 3 mm to 50 mm, more preferably in the range of 5 mm to 30 mm, from the viewpoint of the strength of the core layer 10. The basis weight (weight per unit area) of the core layer 10 is not particularly limited, but is preferably 400 g / m ２ to 4000 g / m ２ The range of 500 g / m ２ to 3000 g / m ２ The greater the thickness and basis weight of the core layer 10, the higher the strength of the core layer 10 generally becomes.
[0022] The basis weight of the core layer 10 can also be adjusted by the type of material of the core layer 10, the thickness of the core layer 10, the wall thickness of the cells 20, and the pitch between the cells 20 (the distance between the central axes of the cells). The wall thickness of the cells 20 is not particularly limited, but from the viewpoint of weight reduction, it is preferably in the range of 50 μm to 1000 μm, more preferably in the range of 100 μm to 500 μm. The pitch between the cells 20 is not limited thereto, but is preferably in the range of 2 mm to 20 mm, more preferably in the range of 3 mm to 15 mm, and even more preferably in the range of 4 mm to 10 mm.
[0023] The reinforcing member 50 is not particularly limited, and examples thereof include H-shaped members, L-shaped members, square or rectangular members, triangular members, and semicircular members. From the perspective of reducing the weight of the hollow structure, it is preferable to use H-shaped members, L-shaped members, and hollow members. The above-mentioned square members, triangular members, and semicircular members can be hollow members such as hollow square members called square pipes, hollow triangular members called triangular pipes, and hollow semicircular members called semicircular pipes. While FIG. 1 shows the reinforcing member 50 as a square pipe, FIG. 3 shows a case where an H-shaped member reinforcing member 50a is used, FIG. 4 shows a case where a semicircular pipe reinforcing member 50b is used, and FIG. 5 shows a case where a triangular pipe reinforcing member 50c is used.
[0024] The material of the reinforcing member 50 is not particularly limited, but examples thereof include steel, aluminum, and stainless steel, from the viewpoint of strength and light weight.
[0025] The reinforcing member 50 is disposed so that its longitudinal direction extends perpendicular to the wall surfaces of the cells 20 of the core layer 10. The outer diameter of the reinforcing member 50 depends on the size of the cell layer 10. The outer diameter in the thickness direction of the cell layer 10 (hereinafter also referred to as "height") may be the same as the height, or preferably in the range of 50 to 98%, more preferably 90 to 98%, of the height. The length of the reinforcing member 50 may be substantially the same as the dimensions of the core layer 10 or may be shorter than that, and the length can be adjusted to suit the location where reinforcement of the hollow structure is desired. When the reinforcing member 50 is hollow, its thickness is not particularly limited, but from the viewpoint of weight reduction, it is preferably in the range of 1 to 5 mm, more preferably 1 to 2 mm.
[0026] 1 shows only one reinforcing member 50 for the core layer 10, multiple reinforcing members 50 may be disposed. The spacing between the reinforcing members 50 depends on the outer diameter of the reinforcing members 50, but is preferably one per 100 to 200 mm, and more preferably one per 100 to 160 mm on the surface 25 of the core layer 10, for example.
[0027] A recess 23 for accommodating the reinforcing member 50 is formed in the surface 25 of the core layer 10. The depth of the recess 23 is substantially the same as the height of the reinforcing member 50. The core layer 10 is welded to the reinforcing member 50 at the bottom of the recess 23 via a welding layer 24. The welding layer 24 is a molten material of the core layer 10, and is formed when the heated reinforcing member 50 is pressed against the surface 25 of the core layer 10 to embed the reinforcing member 50 in the core layer 10, and that portion of the core layer 10 is melted.
[0028] Therefore, the shape of the recess 23 in the core layer 10 is greatly influenced by the opposing shape of the reinforcing member 50. As shown in Figure 1, in the case of the reinforcing member 50 being a square pipe, the shape of the bottom surface of the recess 23 is approximately flat, and the flat bottom surface of the recess 23 and one side of the reinforcing member 50 are welded by the welding layer 24.
[0029] 3, in the case of the H-shaped reinforcing member 50a, the shape of the bottom surface of the recess 23a becomes approximately flat by pressing one of the two parallel sides thereof against the surface 25 of the core layer 10. As a result, the flat bottom surface of the recess 23 and one side of the reinforcing member 50a are welded by the welding layer 24a.
[0030] As shown in Figure 4, in the case of semicircular pipe reinforcing member 50b, a roughly semicircular groove is formed as recess 23b by pressing the circular portion thereof against surface 25 of core layer 10. The cells 20 of core layer 10 melt to an extent that reinforcing member 50b can be welded in the central portion of semicircular recess 23b, while only a portion of cells 20 melts in the outer peripheral portion of recess 23b. Therefore, the arc-shaped bottom surface of the central portion of recess 23b and the rounded tip portion of semicircular pipe reinforcing member 50b are welded by welding layer 24b.
[0031] 5, in the case of a triangular pipe reinforcing member 50c, a roughly V-shaped groove is formed as a recess 23c by pressing the corner of the reinforcing member 50c against the surface 25 of the core layer 10. In this case as well, it is only in the center of this V-shaped recess 23c that the cells 20 of the core layer 10 melt enough to weld the reinforcing member 50c, while only a portion of the cells 20 melts around the periphery of the recess 23c. Therefore, the V-shaped bottom surface of the center of the recess 23c and the corner of the triangular pipe reinforcing member 50c are welded by the welding layer 24c.
[0032] In this way, regardless of the shape of the reinforcing member 50 used, the reinforcing member 50 is welded to the bottom surface of the recess 23 of the core layer 10 by the welding layer 24, but because the core layer 10 has cylindrical cells 20 arranged in multiple rows, depending on the shape of the reinforcing member 50, the cells 20 on the side wall portion of the recess 23 of the core layer 10 may melt and be welded to the reinforcing member 50. This allows the reinforcing member 50 to be more firmly fixed within the recess 23 of the core layer 10.
[0033] The holding member 30 is preferably, for example, a film or a core layer, but is not limited thereto. FIG. 1 shows a case where the holding member 30 is a film. The material of the film is preferably, for example, a thermoplastic resin such as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), polyamide (PA), or polyvinyl chloride (PVC). The film may also have a structure in which multiple layers of different types of resin are laminated, or a structure in which multiple layers of the same type of resin are laminated.
[0034] When the holding member 30 is a film, the thickness of the film is not particularly limited, but from the viewpoint of holding strength, the thickness is preferably in the range of 100 to 1000 μm, and more preferably in the range of 200 to 400 μm. The film may be breathable and have a plurality of openings therethrough, or may be non-breathable and have no such openings.
[0035] When the holding member 30 is a film, the film may be bonded to the exposed surface 51 from the recess 23 of the reinforcing member 50 and the surface 25 of the core layer 10 by heat welding, or may be bonded via an adhesive (not shown). Heat welding may be achieved by using the heat of the heated reinforcing member 50, or by heating the film holding member 30 after covering the exposed surface 51 of the reinforcing member 50 and the surface 25 of the core layer 10 with the film holding member 30.
[0036] The adhesive is not particularly limited, and examples thereof include epoxy and acrylic adhesives. Alternatively, the film may have a three-layer structure, with a central layer and two adhesive layers located on either side of the central layer. In this case, the adhesive layer is made of a material with a melting point lower than that of the material used for the central layer. For example, by using polyamide with a melting point of 190°C to 220°C for the central layer and polyethylene with a melting point of 90°C to 130°C for the adhesive layer, the heating temperature during lamination of the film to the core layer 10 can be set to approximately 150°C to 160°C. This allows the central layer to remain unmelted, and only the adhesive layer to melt, thereby firmly adhering to the core layer 10. In addition to polyamide, polypropylene is another resin with a melting point higher than that of polyethylene for the adhesive layer.
[0037] When the holding member 30 is a film, it is preferable that the reinforcing member 50 is completely embedded in the core layer 10, and the surface 25 of the core layer 10 and the exposed surface 51 of the reinforcing member 50 from the recess 23 are flush with each other. This allows the film holding member 30 to be easily adhered to both the surface 25 of the core layer 10 and the exposed surface 51 of the reinforcing member 50.
[0038] FIG. 6 shows a case where the holding member 30 is a core layer (hereinafter also referred to as an "additional core layer"). Note that in FIG. 6, the core layer 10 and the additional core layer 30A are each laminated bodies including a core body and two outer surface portions, but are shown as a single unit for brevity's sake. In the case of such a core layer holding member 30A, the reinforcing member 50 does not need to be entirely embedded in the core layer 10. For example, only half of the height of the reinforcing member 50 is embedded in the recess 23 of the core layer 10. The remaining half of the reinforcing member 50 is embedded in a recess 33 formed in the surface 35 of the core layer holding member 30A. The surface 25 of the core layer 10 and the surface 35 of the core layer holding member 30A are in contact with each other. One side of the reinforcing member 50 is welded to the bottom surface of the recess 23 of the core layer 10 by the welding layer 24. Similarly, the opposite side of the reinforcing member 50 is welded to the bottom surface of the recess 33 of the core layer holding member 30A by the welding layer 34.
[0039] This can be produced by pressing a heated reinforcing member 50 against the surface 25 of the core layer 10 to embed half of it, and then pressing the core layer holding member 30A against the reinforcing member 50 protruding from the surface 25 of the core layer 10, causing the heat of the reinforcing member 50 to melt the additional core layer cells 32 and form recesses 33 in the core layer holding member 30A, and then embedding the remaining half of the reinforcing member 50 in these recesses 33. The surface 25 of the core layer 10 and the surface 35 of the core layer holding member 30A may be bonded together with an adhesive or the like.
[0040] 6 shows a case where the reinforcing member 50 is half-embedded in the core layer 10, but this is not limiting, and for example, 25 to 49% of the height of the reinforcing member 50 can be embedded in the core layer 10. The remaining height of the reinforcing member 50 is embedded in the recess 33 of the holding member 30A of the core layer. Also, while FIG. 6 shows a case where a square pipe is used as the reinforcing member 50, the above-mentioned H-shaped member or a round material with a circular cross section, particularly a hollow round material called a round pipe, can also be used as the reinforcing member 50.
[0041] 6 shows a case in which one reinforcing member 50 is held between the recess 23 of the core layer 10 and the recess 33 of the core layer holding member 30A, but this is not limited thereto. As shown in FIG. 7, multiple reinforcing members 50 may be held between the core layer 10 and the core layer holding member 30A. In this case, one reinforcing member 50 is entirely embedded in the recess 23 of the core layer 10, and the exposed surface 51 of the reinforcing member 50 is flush with the surface 25 of the core layer 10. Furthermore, another reinforcing member 50A (hereinafter also referred to as the "additional reinforcing member") is entirely embedded in the recess 33 of the core layer holding member 30A, and the exposed surface 51A of the additional reinforcing member 50A is flush with the surface 35 of the core layer holding member 30A. The flush surfaces are in contact with each other, and the exposed surface 51 of the reinforcing member 50 embedded in the recess 23 of the core layer 10 is adhered to the surface 35 of the holding member 30A of the core layer, and the exposed surface 51A of the additional reinforcing member 50A embedded in the recess 33 of the holding member 30A of the core layer is adhered to the surface 25 of the core layer 10.
[0042] Here, the recess 23 of the core layer 10 may be a portion that is lower than the surface 25 of the core layer 10. The recess 23 is not limited to a case where the entire periphery of the recess 23 is on the surface 25 of the core layer 10. For example, the recess 23 may be formed at an edge or corner of the core layer 10. For example, as shown in FIG. 8 , a recess 23d may be formed at the edge of the core layer 10. In this case, one side of an L-shaped reinforcing member 50d is flush with the surface 25 of the core layer 10 and is bonded to the holding member 30, and the tip of the other side of the L-shaped reinforcing member 50d is welded to the bottom surface of the recess 23d of the core layer 10 by an adhesive layer 24d. This configuration allows the reinforcing member 50d to be disposed at the edge or corner of the core layer 10, which is weaker in strength, thereby further improving the strength of the hollow structure.
[0043] Although Figure 8 shows the case where an L-shaped reinforcing member 50d is used at the end of the core layer 10, this is not limited to this. As shown in Figure 9, even if a reinforcing member 50 made of a square pipe is used, the reinforcing member 50 can be similarly placed in the recesses 23d at the ends or corners of the core layer 10, thereby improving the strength of the hollow structure.
[0044] Furthermore, an accessory member may be joined to the reinforcing member 50 via a holding member 30. An example of an accessory member is a hook 52, as shown in FIG. 10 . The hook 52 is an accessory member for suspending the hollow structure 100 to move or fix it. By joining the hook 52 to the reinforcing member 50, even if the hollow structure 100 is moved or fixed by the hook 52, the hook 52 can be prevented from easily coming off the hollow structure 100. It is preferable that the hook 52 is joined to the reinforcing member 50 via the holding member 30 by fastening with a rivet 53, for example. Other examples of such accessory members for hollow structures include belts and hanging hardware.
[0045] The surface layer 40 is a layer that becomes the surface when the hollow structure of this embodiment is used. The material of the surface layer 40 is not limited to these, but it is preferable to use various nonwoven fabrics such as spunbond, spunlace, or needlepunch using resins such as polyethylene terephthalate (PET), polypropylene (PP), and polyethylene (PE).
[0046] As described above, the core layer 10 is not particularly limited as long as it is a core layer in which commonly used cylindrical cells are arranged in multiple rows, but it is preferable to use a core layer having the structure described below.
[0047] 11 is a perspective view showing a manufacturing process of a core material that will become the core layer 10A. The manufacturing method of this core material is described in detail in International Publication No. WO 2006 / 053407, which is incorporated herein by reference.
[0048] As shown in FIG. 11 , this core material 1 is formed by thermoforming a flat material sheet using a roller (not shown) with a predetermined shape, resulting in plastic deformation without substantially cutting the sheet. The core material 1 is a material containing resin. Examples of suitable resins include, but are not limited to, thermoplastic resins such as polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET). Resin-containing materials may also include composite materials of resin and fiber, or paper whose surface is coated (laminated) with resin. In this embodiment, a case where a thermoplastic resin is used will be described. The thickness of the material sheet is not limited to, but is preferably in the range of 0.05 mm to 0.50 mm, and the thickness of the core material 1 after thermoforming is approximately the same.
[0049] The core material 1 has a three-dimensional structure in which peaks 11 and valleys 12 are alternately arranged in the width direction X perpendicular to the manufacturing direction Y. Each peak 11 is composed of two side surfaces 13 and a top surface 17 therebetween, and each valley 12 is composed of two side surfaces 13 shared with adjacent peaks 11 and a bottom surface 14 therebetween. In this embodiment, the peaks 11 are described as having a trapezoidal shape as shown in Fig. 11, but the present invention is not limited to this and may have a polygonal shape such as a triangle or a rectangle, or a curved shape such as a sinusoidal curve or an arch shape.
[0050] The core material 1 has the above-described three-dimensional structure formed continuously in the manufacturing direction Y. That is, as shown in Fig. 11, a plurality of peaks 11a, 11b, 11c, and 11d are formed continuously in the manufacturing direction Y. Similarly, valleys 12 are formed continuously. The connections between the peaks 11 and the connections between the valleys 12 are formed by alternately repeating two types of connection methods.
[0051] In the first connection method, as shown in FIG. 11 , the top surfaces 17b, 17c of two adjacent peaks 11b, 11c are connected via trapezoidal peak connection surfaces 15b, 15c, respectively, at a first widthwise folding line X1. The peak connection surface 15 is formed at a right angle to the top surface 17. In this first widthwise folding line X1, the bottom surfaces 14b, 14c of two adjacent valleys are directly connected. In the second connection method, as shown in FIG. 11 , the bottom surfaces 14a, 14b (or 14c, 14d) of two adjacent valleys are connected via trapezoidal valley connection surfaces 16a, 16b (or 16c, 16d), respectively, at a second widthwise folding line X2. The valley connection surface 16 is formed at a right angle to the bottom surface 14. At this second folding line X2 in the width direction, the top surfaces 12a, 12b (or 12c, 12d) of two adjacent mountain portions are directly connected to each other.
[0052] In this way, the core material 1 has multiple three-dimensional structures (peaks 11, valleys 12) connected via connection regions (peak connection surfaces 15, valley connection surfaces 16), and the core layer of the vibration-damping material of the present invention is formed by folding the connection regions. Specifically, the core material 1 is folded along the first folding line X1 in a mountain fold such that the bottom surfaces 14b, 14c of two adjacent valleys overlap each other via their back surfaces, and the angle between the peak connection surfaces 15b, 15c of the two adjacent peaks is 180 degrees. The core material 1 is folded along the second folding line X2 in a valley fold such that the top surfaces 17a, 17b (or 17c, 17d) of the two adjacent peaks overlap each other, and the angle between the valley connection surfaces 16a, 16b (or 16c, 16d) of the two adjacent valleys is 180 degrees. The core layer 10A obtained by folding the core material 1 in this manner is shown in FIGS.
[0053] As shown in Fig. 12, the core layer 10A includes a plurality of rows of approximately hexagonal cylindrical cells 20, with cells 20A, 20C, and 20E formed from two adjacent peaks and cells 20B and 20D formed from two adjacent valleys arranged in every other row. The dashed line 18 in Fig. 12 indicates the surface that was previously the back surface of the core material and generally represents the inner walls of the approximately hexagonal cylindrical cells 20.
[0054] Each of the cells 20A, 20C, and 20E formed from the ridges has six cell sidewalls forming a substantially hexagonal cylindrical shape, and these cell sidewalls are formed from two top surfaces 17 and four side surfaces 13 of the cell material. Furthermore, each of the cells 20A, 20C, and 20E has a substantially hexagonal cylindrical closing surface 21A, 21C, and 21E that closes the cell end at one surface 10a (the front surface in FIG. 12 ) of the core layer 10A, and each of these one-side closing surfaces 21A, 21C, and 21E is formed by two trapezoidal ridge connection surfaces 15 of the cell material. Furthermore, each of the cells 20A, 20C, and 20E has a substantially hexagonal open end 22A, 22C, and 22E at the cell end at the other surface 10b, which is the opposite surface of the core layer 10A. The open ends 22A, 22C, 22E allow the internal spaces of the cells 20A, 20C, 20E to communicate with the outside.
[0055] Each of the cells 20B, 20D formed from the valleys also has six cell sidewalls forming a substantially hexagonal cylindrical shape. These cell sidewalls are formed from two bottom surfaces 14 and four side surfaces 13 of the cell material. Furthermore, each of the cells 20B, 20D has open ends 22B, 22D that open into a substantially hexagonal shape at the cell end on the surface 10a of the core layer 10A. These open ends 22B, 22D connect the internal spaces of the cells 20B, 20D to the outside. Furthermore, each of the cells 20B, 20D has closed surfaces 21B, 21D that are substantially hexagonal cylindrical and close the cell end on the other surface 10b, the opposite side of the core layer 10A. These closed surfaces 21B, 21D are each formed by two trapezoidal valley connection surfaces 16 of the cell material.
[0056] In this way, the core layer 10A has one-side closed surfaces 21A, 21C, and 21E formed from the peaks of the cell material in every other row at the cell ends of one surface 10a, and has other-side closed surfaces 21B and 21D formed from the valleys of the cell material in a different row of cells at the cell ends of the other surface 10b, but unless otherwise specified, both the one-side closed surfaces 21 and the other-side closed surfaces 21 perform substantially the same function.
[0057] 13, in the core layer 10A, each cell 20 has a closed surface 21 at one end and an open end 22 at the other end, and rows of cells 20 in which the open ends 22 face one surface of the core layer and rows of cells 20 in which the open ends 22 face the other surface of the core layer are arranged in alternate rows. When such a core layer 10A is used, the reinforcing member 50 can be accommodated in the recess, and the reinforcing member 50 can be welded by a partially melted adhesive layer, as described above. A preferred arrangement of the reinforcing member 50 in this core layer 10A will be described below.
[0058] As shown in Figures 12 and 14, the reinforcing member 50 is preferably disposed on the core layer 10A so that its longitudinal direction is aligned with the direction in which the closed faces 21 or open ends 22 of the cells 20 are adjacently aligned on one side of the core layer 10A (the Y direction in Figure 12). This reinforces the high-rigidity side of the core layer 10A and strengthens the side bridged by the reinforcing member 50. Also, as shown in Figures 12 and 14, the reinforcing member 50 is preferably disposed inside a row of cells in the core layer 10A. This increases the surface area installed on the longitudinal cross section of the core layer 10A, thereby improving rigidity. In this case, the reinforcing member 50 is preferably pressed against the surface 25 of the core layer 10A at the open ends 22 of the cells 20. This increases the contact area with the bottom surface of the core layer 10A, thereby more firmly securing the reinforcing member 50.
[0059] 15 and 16, the reinforcing member 50 may be disposed on the core layer 10A so that the longitudinal direction of the reinforcing member 50 is perpendicular to the direction in which the closed faces 21 or the open ends 22 of the cells 20 are adjacently arranged in a row on one side of the core layer 10A (the X direction in FIG. 15). Also, as shown in FIGS. 15 and 16, it is preferable to dispose the reinforcing member 50 so that it contacts the wall surfaces of the cells 20 of the core layer 10A. This increases the contact area between the reinforcing member 50 and the core layer 10A, which is expected to increase rigidity.
[0060] Examples and comparative examples of the present invention will be described below.
[0061] As Example 1, a hollow structure shown in Fig. 1 was fabricated. First, a core layer (material: polypropylene (PP) resin, core layer thickness: 20 mm, cell pitch Pcy: 9.6 mm) having the structure shown in Fig. 13 was prepared. In addition, a square pipe (material: stainless steel, outer diameter: 19 mm × 19 mm, thickness: 1.0 mm) was prepared as a reinforcing member, and a film (material: polypropylene (PP) film, thickness: 350 µm) was prepared as a holding member.
[0062] The square pipe was then heated to a temperature of approximately 300°C and pressed against one surface of the core layer. The contacting portion of the core layer was melted to form a recess, and the square pipe was pressed against the recess until it was completely embedded in the recess. That is, the one surface of the core layer and the exposed surface of the square pipe were flush with each other. The melted resin in the recess of the core layer also welded the bottom of the recess to the square pipe. The square pipe was pressed against the core layer so that its longitudinal direction was aligned with the direction in which the open ends or closed faces of the cells were adjacently aligned in a row on one surface of the core layer (the Y direction in Figure 12). Next, a film was placed over the flush one surface of the core layer and the exposed surface of the square pipe. The film was then heated to approximately 170°C, and the film was welded to one surface of the core layer and the exposed surface of the square pipe. The hollow structure (Example 1) thus fabricated was subjected to a bending test to evaluate its strength.
[0063] The bending test was performed using a three-point bending test in accordance with JIS K7171. A universal testing machine (Instron Japan Co., Ltd., Model No. 5965) was used for the bending test. The test specimen measured 50 mm wide and 150 mm long. As shown in FIGS. 17 and 18 , a test specimen 100S was supported at two fulcrums on a support stand 61, and a load was applied to the center of the support stand using an indenter 62. Measurements were performed in two cases: one in which the square pipe 50S of the test specimen 100S was positioned in the center of the two fulcrums on the support stand 61, as shown in FIG. 17 , and the other in which the square pipe 50S of the test specimen 100S was positioned across the two fulcrums on the support stand 61, as shown in FIG. 18 . In the former case, the test specimen was fabricated so that the square pipe extended in the width direction of the test specimen, and in the latter case, the square pipe extended in the longitudinal direction of the test specimen. The test results for the former are shown in Figure 19, and the test results for the latter are shown in Figure 20. The test conditions were a test speed of 50 mm / min, a test measurement interval of 0.1 s, a support distance of 100 mm, and a displacement at the end of the test of 40 mm.
[0064] As Example 2, a hollow structure shown in FIG. 6 was fabricated. The hollow structure was fabricated in the same manner as Example 1, except that the core layer was 10 mm thick, the square pipe was half-embedded in the recess of the core layer, a core layer (hereinafter referred to as the "additional core layer") of the same thickness as the core layer was used as a retaining member (the total thickness of the core layer and the additional core layer was 20 mm), and the additional core layer was also melted by the heat of the square pipe to form a recess, while the square pipe was half-embedded in the recess and welded to the additional core layer. The additional core layer was also pressed against the square pipe so that its longitudinal direction was aligned with the direction in which the open ends or closed faces of the cells were adjacently aligned in a row on one side of the additional core layer (the Y direction in FIG. 12 ). The hollow structure (Example 2) fabricated in this manner was subjected to a bending test in the same manner as Example 1. The results are also shown in FIGS. 19 and 20 .
[0065] Furthermore, for comparison, a hollow structure (comparative example) was fabricated in the same manner as in Example 1, except that no film was used as a holding member. A bending test was also carried out on this comparative example in the same manner as in Example 1. The results are shown in Figures 19 and 20.
[0066] As shown in Fig. 19, the hollow structure of Example 1, which used a film as a retaining member, and the hollow structure of Example 2, which used an additional core layer as a retaining member, retained the square pipe in the core layer even when subjected to a load of approximately 200 N, resulting in a bending displacement of 25 mm caused by the indenter. On the other hand, the hollow structure of Comparative Example, which did not use a retaining member, lost the square pipe welded to the recess in the core layer when subjected to a load of approximately 20 N.
[0067] 20, when the square pipe 50S of the test piece 100S was placed in the testing machine so that it crossed two fulcrums of the support stand 61, all of the hollow structures of Examples 1 and 2 and the Comparative Example were able to withstand a load of 1000 N or more without being significantly deflected due to the rigidity of the square pipe. The bending displacement of Examples 1 and 2 was about 0.5 mm, while that of the Comparative Example was about 2.5 mm, which is slightly different, and this can be assumed to be because the reinforcing material was not flush with the bottom surface.
[0068] Although the embodiments and examples of the present invention have been described above, the present invention is not limited to these embodiments and examples, and various modifications and changes can be made within the scope of the claims.
[0069] The method for manufacturing a hollow structure according to the present invention can be described as follows: [1] to [8]. [1] A method for manufacturing a hollow structure, comprising: heating a reinforcing member; pressing the heated reinforcing member against one surface of a core layer having cylindrical cells arranged in a plurality of rows to form a recess in the surface of the core layer, embedding at least a portion of the reinforcing member in the recess, and welding the core layer and the reinforcing member at the bottom of the recess; and arranging a holding member so as to contact both the one surface of the core layer and at least a portion of the exposed portion of the reinforcing member from the recess, and bonding the holding member to at least a portion of the exposed portion of the reinforcing member. [2] The method for manufacturing a hollow structure according to [1], wherein the reinforcing member is an H-shaped member, an L-shaped member, a hollow rectangular member, a hollow triangular member, a hollow round member, or a hollow semicircular member. [3] The method for manufacturing a hollow structure according to [1], wherein the one surface of the core layer and the surface of the reinforcing member exposed from the recess are flush with each other. [4] The method for manufacturing a hollow structure according to [1], wherein the core layer and the reinforcing member are welded together at the sidewall of the recess of the core layer. [5] The method for manufacturing a hollow structure according to [1], wherein the holding member is a film. [6] The method for manufacturing a hollow structure according to [1], wherein the holding member is an additional core layer in which cylindrical cells are arranged in multiple rows. [7] The method for manufacturing a hollow structure according to [1], wherein the cells of the core layer are adjacent to each other to form rows, each cell of the core layer having a closed face at one end and an open end at the other end, with rows of cells in which the open ends face one surface of the core layer and rows of cells in which the open ends face the other surface of the core layer being arranged in alternate rows. [8] The method for manufacturing a hollow structure according to [1], further comprising a step of joining a hanger to the reinforcing member via the holding member.
[0070] DESCRIPTION OF SYMBOLS 1 Core material 10 Core layer 10C Core body 11 Peak portion 12 Valley portion 13 Side portion 14 Bottom portion 15 Peak portion connection surface 16 Valley portion connection surface 17 Top surface 18 Back surface of core material 20 Cell 21 Closed surface 22 Open end 23 Recess 24 Welding layer 25 Surface of core layer 26 Opposite surface of core layer 30 Retaining member 33 Recess 34 Welding layer 40 Skin layer 50 Reinforcing member 51 Exposed surface 52 Hook (accessory member) 53 Rivet 61 Support base 62 Indenter 100 Hollow structure
Claims
DEPCT691. A hollow structure composed of a core layer in which a number of rows of tubular cells are arranged internally, constructed from a resin-containing material, with an indentation on one surface of the core layer, a reinforcing element placed inside the indentation of the core layer, and a fixing element placed in contact with both one surface of the core layer and at least part of the protruding portion of the reinforcing element, the protruding portion extending from the indentation, where the core layer is bonded to the reinforcing element on the underside of the indentation, and the fixing element is bonded to at least part of the protruding portion of the reinforcing element.
2. A hollow structure according to claim 1, where the core layer is bonded to the reinforcing element on the lateral walls of the indentation.
3. A hollow structure according to claim 1 or 2, where one surface of the core layer and the protruding portion of the reinforcing element lie on the same plane, the protruding portion extending from the indentation. 4.
5. Hollow structure under claim 1 or 2, where the reinforcing element is an H-shaped element, L-shaped element, rod-shaped element, triangular element, circular element, or semicircular element.
6. Hollow structure under claim 1 or 2, where the reinforcing element is retained as a film.
7. Hollow structure under claim 1 or 2, where the cells of the core layer are adjacent and form rows, where each cell of the core layer has a closed surface at one end and an open surface at the other end, and where the rows of cells with open surfaces are arranged facing one surface of the core layer and the rows of cells with open surfaces are arranged facing the other surface of the core layer in alternating rows.
8. Hollow structure under claim 1 or 2, further incorporated with fastening elements connected to the reinforcing element via retaining elements.