Structure and method for manufacturing the structure

Abstract

To provide a technology that improves stiffness in a hollow structure.SOLUTION: A structure includes: a hollow tubular body part; and a stiffening member including a first stiffening part formed at an outside surface of the body part, a second stiffening part formed at an inside surface of the body part and a connection part penetrating a side surface of the body part and connecting the first stiffening part to the second stiffening part.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hollow structural body that constitutes a moving body such as a vehicle, or a structure such as a building. [Background technology]

[0002] Conventionally, a hollow structure having a space formed by, for example, an outer panel and an inner panel is used as a structure constituting an automobile. Various techniques for improving the rigidity of such a hollow structure have been proposed (for example, see Patent Documents 1 to 4). Patent Document 1 discloses a configuration in which a plurality of stiffening members made of resin are arranged in a space formed between an outer panel and an inner panel. Patent Document 2 discloses a configuration in which a stiffening member made of a foam material is arranged between a body frame member and an outer panel of a vehicle. Patent Document 3 discloses a body frame structure constituting the side of an automobile, in which a three-layer structure of metal, resin, and foam material is arranged in a closed space formed by an outer panel and an inner panel. Patent Document 4 discloses a configuration in which a tubular member connecting an upper surface side and a lower surface side is arranged as a stiffening member in an internal space of a hollow member in an automobile subframe structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-64569 A [Patent Document 2] JP 2018-8587 A [Patent Document 3] JP 2019-26168 A [Patent Document 4] JP 2020-83018 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is a demand for further improvement in the rigidity of hollow structures. Note that this issue is not limited to automobile structures, but is also a common issue for various moving objects, buildings, and other structures.

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to provide a technique for improving the rigidity of a hollow structure. [Means for solving the problem]

[0006] The present invention has been made to solve the above-mentioned problems, and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, there is provided a structure comprising: a hollow tubular main body, a stiffening member having a first stiffening portion formed on an outer surface of the main body, a second stiffening portion formed on an inner surface of the main body, and a connecting portion penetrating a side surface of the main body and connecting the first stiffening portion and the second stiffening portion.

[0008] According to this configuration, stiffening members are disposed both inside and outside the main body. The first stiffening member formed on the outer surface of the main body improves the second moment of area, thereby improving rigidity. The second stiffening member formed on the inner surface of the main body improves rigidity by preventing elastic buckling. Therefore, the rigidity can be further improved compared to a configuration in which stiffening members are provided only on either the outside or the inside of the hollow member. As a result, deformation of the structure when an external force is applied to the structure can be suppressed.

[0009] (2) In the structure of the above aspect, the shape of the stiffening member may be derived by topology optimization. In this way, the shape of the stiffening member can be made more appropriate, and the rigidity of the structure can be further improved.

[0010] (3) In the structure of the above aspect, the stiffening member may be joined to the main body without an adhesive. In this way, the number of manufacturing steps for the structure can be reduced, and manufacturing costs can be reduced, compared to a case in which the stiffening member is joined to the main body with an adhesive.

[0011] (4) In the structure of the above aspect, at least a part of the stiffening member may be a foamed body, which contributes to weight reduction.

[0012] (5) In the structure of the above aspect, the foam may be a metal foam, which can improve rigidity compared to a resin foam.

[0013] (6) According to another aspect of the present invention, there is provided a method for manufacturing a structure, comprising the steps of: preparing a hollow tubular main body having one or more through holes, forming cavities including the through holes of the main body on the outside and inside of the main body, pouring a fluid into the cavity, and solidifying the fluid poured into the cavity to form a stiffening member having a first stiffening part formed on the outside surface of the main body, a second stiffening part formed on the inside surface of the main body, and a connecting part that penetrates a side surface of the main body and connects the first stiffening part and the second stiffening part.

[0014] According to this manufacturing method, the stiffening member can be formed and joined to the main body portion at the same time, which reduces the number of manufacturing steps and reduces the manufacturing cost of the highly rigid structure compared to a manufacturing method in which a separately manufactured stiffening member is joined to the structure.

[0015] The present invention can be realized in various aspects, for example, in the form of a moving body provided with a structure, a structure provided with a structure, etc. [Brief description of the drawings]

[0016] [Figure 1]FIG. 2 is an explanatory diagram illustrating a schematic external configuration of a structure according to the first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram illustrating a schematic configuration of a main body portion. [Diagram 3] FIG. 2 is an explanatory diagram illustrating a schematic external configuration of a stiffening member. [Figure 4] 3 is an explanatory diagram illustrating a schematic external configuration of a first stiffening part and a second stiffening part. FIG. [Diagram 5] FIG. 4 is an explanatory diagram illustrating a schematic cross-sectional configuration of a stiffening member. [Figure 6] FIG. 13 is an explanatory diagram of a method for deriving an optimal shape of a stiffening member. [Figure 7] FIG. 11 is an explanatory diagram illustrating a schematic configuration of a structure according to a second embodiment. [Figure 8] FIG. 13 is an explanatory diagram illustrating a schematic configuration of a structure according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] First Embodiment 1 is an explanatory diagram that shows a schematic external configuration of a structure 100 of a first embodiment. The structure 100 includes a main body portion 10 and a stiffening member 20. The main body portion 10 includes a first main body portion 11, a second main body portion 12, and a third main body portion 13, and the first main body portion 11 and the third main body portion 13 are connected by the second main body portion 12. As an example of the structure 100 of this embodiment, one used as a body skeleton structure of a vehicle is shown.

[0018] 2 is an explanatory diagram showing a schematic configuration of the main body 10. As shown in the figure, the main body 10 is formed into a hollow tube shape as a whole by connecting a first main body 11, a second main body 12, and a third main body 13. The main body 10 is formed into a double-open tube shape with both ends open. The first body portion 11, the second body portion 12, and the third body portion 13 are each formed in a hollow rectangular tube shape. As shown in the figure, the inner peripheral shapes of the first body portion 11 and the third body portion 13 and the outer peripheral shape of the second body portion 12 are approximately the same. One end of the second body portion 12 is inserted into the first body portion 11, and the other end of the second body portion 12 is inserted into the third body portion 13.

[0019] As shown in the figure, a through hole 10H penetrating the side surface of the first body portion 11 and the side surface of the second body portion 12 is formed in the first overlapping portion 14, which is a portion where the first body portion 11 and the second body portion 12 overlap. Similarly, a through hole 10H penetrating the side surface of the second body portion 12 and the side surface of the third body portion 13 is formed in the second overlapping portion 15, which is a portion where the second body portion 12 and the third body portion 13 overlap. Two through holes 10H are formed on each of the four side surfaces constituting the first overlapping portion 14, for a total of eight through holes. Similarly, two through holes 10H are formed on each of the four side surfaces constituting the second overlapping portion 15, for a total of eight through holes. In FIG. 2, in order to clearly illustrate the through holes 10H, four through holes 10H arranged on one side surface arranged in the foreground in FIG. 2 are illustrated, and the remaining through holes 10H are omitted from illustration.

[0020] The main body 10 can be formed from various materials, for example, metals such as iron, stainless steel, and aluminum, alloys, resin materials such as carbon fiber reinforced plastic, and wood.

[0021] 3 is an explanatory diagram that shows a schematic external configuration of the stiffening member 20. As shown in the figure, the stiffening member 20 includes a first stiffening portion 21 and a second stiffening portion 22.

[0022] Fig. 4 is an explanatory diagram that shows a schematic external configuration of the first stiffening portion 21 and the second stiffening portion 22. Fig. 5 is an explanatory diagram that shows a schematic cross-sectional configuration of the stiffening member 20. Fig. 5(a) shows the AA cross section in Fig. 2, and Fig. 5(b) shows the BB cross section in Fig. 2. Here, the AA cross section is a cross section that passes through the eight through holes 10H of the first overlapping portion 14, and the BB cross section is a cross section that passes through the eight through holes 10H of the second overlapping portion 15.

[0023] As shown in FIG. 5, the first stiffening portion 21 is formed on the outer surface 10o of the main body portion 10, and the second stiffening portion 22 is formed on the inner surface 10i of the main body portion 10. The first stiffening portion 21 and the second stiffening portion 22 are connected by a connecting portion 23 disposed in the through hole 10H of the main body portion 10. That is, the stiffening member 20 has the first stiffening portion 21 formed on the outer surface 10o of the main body portion 10, the second stiffening portion 22 formed on the inner surface 10i of the main body portion 10, and the connecting portion 23 that penetrates the side surface of the main body portion 10 and connects the first stiffening portion 21 and the second stiffening portion 22. As shown in FIG. 3, FIG. 4, and FIG. 5, the stiffening member 20 of this embodiment has an irregular and complex shape. As will be described later, the shape of the stiffening member 20 of this embodiment is a shape derived by topology optimization.

[0024] In this embodiment, the stiffening member 20 is a metal foam. In other words, the entire stiffening member 20 in this embodiment is a metal foam. As the metal, various metals such as iron, stainless steel, aluminum, and alloys can be used. As the metal, it is preferable to use an aluminum alloy in consideration of its melting point, specific gravity, rigidity, and the like. In other embodiments, foams of materials other than metals, such as resin foams and ceramic foams, may be used. Also, solid metals, resins, ceramics, and the like that are not foams may be used.

[0025] Next, a method for deriving the shape of the stiffening member 20 by topology optimization will be described with reference to FIG. 6 is an explanatory diagram of a method for deriving the optimal shape of the stiffening member 20. In this embodiment, a shape is derived that maximizes the rigidity of the second body portion 12, which is the joint between the first body portion 11 and the third body portion 13. FIG. 6(a) shows the translational forces (Fx, Fy, Fz) generated on the end face of the second body portion 12. 6(b) illustrates the design domain of the inside and the outer periphery of the second main body portion 12.

[0026] First, the load (translational force and moment T) generated on the end face of the second main body portion 12 is calculated from the force applied to the entire structure 100. As boundary conditions, the lower end is constrained and a load is set at the upper end. Then, a shape that maximizes rigidity is derived by topology optimization. As a result, the shapes of the first stiffening portion 21 and the second stiffening portion 22 shown in FIG. 4 are derived.

[0027] Next, a method for manufacturing the structure 100 will be described. First, as shown in Fig. 2, a main body portion 10 (Fig. 2) having 16 through holes 10H formed therein is prepared. The main body portion 10 having the through holes 10H formed therein may be formed by arranging the first main body portion 11, the second main body portion 12, and the third main body portion 13, each having a through hole formed therein, so that the positions of the through holes are aligned. Alternatively, after inserting the end portion of the second main body portion 12 into the first main body portion 11 and the third main body portion 13, each having no through holes formed therein, a through hole penetrating the first overlapping portion 14 and the second overlapping portion 15 may be formed.

[0028] Cavity-forming members that form a cavity including the 16 through-holes 10H of the main body 10 are disposed on the outer and inner sides of the main body 10. The cavity-forming members are formed so that the shape of the gap between the cavity-forming members and the main body 10 becomes the shape derived by the above-mentioned topology optimization. In this embodiment, the cavity-forming members are formed from a metal plate material.

[0029] The stiffening member 20 can be shaped by pouring a fluid into the formed cavity and solidifying the fluid poured into the cavity. In this embodiment, as described above, since the stiffening member 20 is a metal foam, the fluid is a metal fluid mixed with a foaming material. In this way, the metal foam can be formed after filling the cavity with the metal fluid. Note that in this embodiment, the cavity-forming member (metal plate material) is removed after the fluid has solidified. In other embodiments, the cavity-forming member may be left as it is.

[0030] In this manufacturing method, the cavity formed by the cavity-forming member and the main body portion 10 includes the through hole 10H. That is, the cavity formed on the outside of the main body portion 10 and the cavity formed on the inside of the main body portion 10 are connected by the through hole 10H of the main body portion 10. Therefore, for example, when a fluid is poured into the cavity formed on the outside of the main body portion 10, the fluid flows into the cavity on the inside of the main body portion 10 through the through hole 10H. The fluid that has flowed into the through hole 10H solidifies to form the connection portion 23. That is, when the entire cavity is filled with the fluid and solidified, the stiffening member 20 in which the first stiffening portion 21 and the second stiffening portion 22 are connected by the connection portion 23 is completed. Furthermore, according to this manufacturing method, the fluid filled in the cavity is solidified, thereby bonding the first body portion 11 and the second body portion 12, and the second body portion 12 and the third body portion 13, and bonding the stiffening member 20 to the body portion 10. Therefore, it is possible to manufacture the structure 100 in which the body portion 10 and the stiffening member 20 are integrated without using an adhesive. In other words, the bonding process between the first body portion 11 and the second body portion 12, and the second body portion 12 and the third body portion 13, and the bonding process between the stiffening member 20 and the body portion 10 can be omitted.

[0031] As described above, according to the structure 100 of this embodiment, the stiffening members 20 are disposed both inside and outside the main body portion 10. The first stiffening member 21 formed on the outer surface 10o of the main body portion 10 improves the second moment of area, thereby improving rigidity. The second stiffening member 22 formed on the inner surface 10i of the main body portion 10 improves rigidity by preventing elastic buckling. Therefore, it is possible to further improve rigidity compared to a configuration in which stiffening members are provided only on either the outside or the inside of a hollow member. As a result, when an external force is applied to the structure 100, When the structure 100 is broken, deformation of the structure 100 can be suppressed.

[0032] Furthermore, since the first stiffening part 21 and the second stiffening part 22 are connected by a connection part 23 that penetrates the side of the main body part 10, the first stiffening part 21 and the second stiffening part 22 can be positioned at an appropriate position relative to the main body part 10, so that a shape in which the main body part 10 and the stiffening member 20 are integrated can be formed.

[0033] The shape of the stiffening member 20 in this embodiment is derived by topology optimization, so that the shape with the highest stiffness can be derived when the volume of the stiffening member is constant. Therefore, the stiffening member 20 can be shaped to have a shape that maximizes the stiffness of the structure 100.

[0034] The stiffening member 20 of this embodiment is a foamed metal body, and therefore can be made lighter in weight than a solid metal body, and can have higher rigidity than a foamed resin body.

[0035] Furthermore, according to the manufacturing method of the structure of this embodiment, the stiffening member 20 can be formed and joined to the main body 10. That is, according to this manufacturing method, the main body 10 and the stiffening member 20 can be joined without using an adhesive. Therefore, compared to a manufacturing method in which a separately manufactured stiffening member is joined to the structure using an adhesive, it is possible to reduce the manufacturing process and reduce the manufacturing cost of the highly rigid structure.

[0036] In addition, since the cavity on the outside of the main body 10 and the cavity on the inside of the main body 10 are connected by the through hole 10H of the main body 10, the entire cavity can be filled with the fluid by pouring the fluid into the cavity on the outside of the main body 10. This makes it possible to easily manufacture the stiffening member 20.

[0037] <Second embodiment> Fig. 7 is an explanatory diagram that shows a schematic configuration of a structure 100A of a second embodiment. Fig. 7(a) shows a side view of the structure 100A, and Fig. 7(b) shows a CC cross section of Fig. 7(a). The structure 100A of this embodiment differs from the structure 100 of the first embodiment in the shape and configuration of the stiffening member 20A. In the following embodiments, the same components as those of the first embodiment are denoted by the same reference numerals, and the preceding description is to be referred to.

[0038] The structure 100A of this embodiment has two stiffening members 20A. One of the two stiffening members 20A is formed so as to cover substantially the entire outer surface 10o and inner surface 10i of the first overlapping portion 14. The other stiffening member 20A is formed so as to cover substantially the entire outer surface 10o and inner surface 10i of the second overlapping portion 15. The stiffening member 20A also has a first stiffening portion 21A, a second stiffening portion 22A, a connecting portion 23, an outer cavity forming member 24, and an inner cavity forming member 25. The first stiffening portion 21A, the second stiffening portion 22A, and the connecting portion 23 are made of a metal foam, as in the first embodiment. The outer cavity forming member 24 and the inner cavity forming member 25 are made of a metal plate material. That is, a part of the stiffening member 20A of this embodiment is made of a foam. The shape of the stiffening member 20A in this embodiment is determined without using an optimization method.

[0039] The structure 100A of this embodiment is manufactured by a method similar to that of the structure of the first embodiment. The outer cavity-forming member 24, the inner cavity-forming member 25, and the main body 10 (including the through hole 10H) form a cavity into which a fluid is poured. The outer cavity-forming member 24 forms an injection port 24I through which the fluid is poured. In forming the stiffening member 20A, the fluid poured from the injection port 24I passes through the through hole 10H and flows into the inner cavity formed by the inner cavity-forming member 25. In the manufacturing method of the structure of this embodiment, the outer cavity-forming member 24 and the inner cavity-forming member 25 are fixed to the fluid fixing member 10H. After conversion, it is left as it is.

[0040] The reinforcing member 20A of this embodiment is formed to cover almost the entire outer surface 10o and inner surface 10i of the first overlapping portion 14 and the second overlapping portion 15 in the main body portion 10, thereby appropriately improving the rigidity of the structure 100.

[0041] The stiffening member 20A of this embodiment has a simple shape and can be easily formed. In addition, the shape of the cavity is simple, so that the outer cavity forming member 24 and the inner cavity forming member 25 can be easily formed.

[0042] <Third embodiment> Fig. 8 is an explanatory diagram that shows a schematic configuration of a structure 100B of a third embodiment. Fig. 8(a) shows a side view of the structure 100B, and Fig. 8(b) shows a DD cross section of Fig. 7(a). The structure 100B includes a stiffening member 20B instead of the stiffening member 20 of the first embodiment. The stiffening member 20B has a different shape and configuration from the stiffening member 20 of the first embodiment.

[0043] The stiffening member 20B is formed so as to cover substantially the entire outer surface 10o and inner surface 10i of the portion of the main body 10 where the second main body 12 is disposed. The stiffening member 20B also has a first stiffening portion 21B, a second stiffening portion 22B, two connecting portions 23, an outer cavity forming member 24B, and an inner cavity forming member 25B. The first stiffening portion 21B, the second stiffening portion 22B, and the connecting portion 23 are metal foams, as in the first embodiment. The outer cavity forming member 24B and the inner cavity forming member 25B are formed of a metal plate material. That is, a part of the stiffening member 20B of this embodiment is a foam. The structure 100B of this embodiment can be manufactured in the same manner as in the second embodiment.

[0044] The structure 100B of this embodiment is formed so as to cover almost the entire outer surface 10o and inner surface 10i of the portion of the main body portion 10 where the second main body portion 12 is located, and in this manner, the rigidity of the structure 100 can be appropriately improved.

[0045] The stiffening member 20B of this embodiment also has a simple shape and can be easily formed. In addition, the outer cavity forming member 24B and the inner cavity forming member 25B can be easily formed because the cavity has a simple shape.

[0046] <Modifications of the embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit and scope of the invention. For example, the following modifications are also possible.

[0047] In the above embodiment, the configuration in which the first body portion 11 and the third body portion 13 are connected via the second body portion 12 is exemplified as the main body portion 10, but the configuration of the main body portion 10 is not limited to the above embodiment. For example, the main body portion may be configured to have four or more hollow tubular members connected, or may be a single hollow tubular member. Even when the main body portion is a single hollow tubular member, the rigidity of the structure can be improved by providing a stiffening member at a location where the load is concentrated, such as a bent portion.

[0048] In the above embodiment, a linear structure 100 is exemplified, but the shape of the structure is not limited to a linear shape, and may be curved or bent.

[0049] The cross-sectional shape of the structure 100 is not limited to the above embodiment. For example, it may be formed into various shapes such as various convex polygons such as a triangle, a pentagon, a hexagon, etc., various concave polygons, a circle, etc. In addition, the cross-sectional shape, thickness, etc. of the structure may differ partially.

[0050] In the above embodiment, the structure 100 is formed in a tubular shape with both ends open, but this is not limiting. For example, the structure may be formed in a one-side closed tubular shape with one end open and the other end closed, or in a both-side closed tubular shape with both ends closed.

[0051] In the above first embodiment, an example has been shown in which the shape of the stiffening member 20 is derived using topology optimization as an optimization method, but the shape of the stiffening member may be derived using other optimization methods. For example, various optimization methods such as numerical optimization and shape optimization can be used.

[0052] In the above embodiment, the stiffening member is joined to the main body portion without an adhesive. However, the stiffening member may be joined to the main body portion with an adhesive.

[0053] In the above embodiment, an example has been shown in which the first stiffening portion 21, the second stiffening portion 22, and the connecting portion 23 are integrally connected, but the first stiffening portion 21, the second stiffening portion 22, and the connecting portion 23 may be formed separately and joined together. When formed separately, they may be formed from different materials.

[0054] The manufacturing method of the structure is not limited to the above embodiment. For example, a preformed reinforcing member may be bonded to the main body portion via an adhesive. Also, for example, the first stiffening portion and the second stiffening portion 22 may be provided on the main body portion 10 by fitting together via a connecting portion.

[0055] In manufacturing the structure, the cavity-forming member that forms the cavity is not limited to the above embodiment. In particular, a collapsible cavity-forming member, such as a sand core or salt core, may be used as the cavity-forming member for forming the second stiffening member on the inner surface 10i of the main body 10. In this way, the cavity-forming member can be easily removed after the stiffening member is formed.

[0056] In the above embodiment, the structure is exemplified as a body skeleton structure of a vehicle, but the present invention can be applied to structures for various moving bodies such as aircraft and trains, and structures for buildings and other structures.

[0057] The present invention has been described above based on the embodiments and modifications, but the above-mentioned embodiments of the invention are intended to facilitate understanding of the present invention and are not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit and scope of the claims, and the present invention includes equivalents thereof. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate. [Explanation of symbols]

[0058] 10...Main body 10H...Through hole 10i…Inner surface 10o…outer surface 11...First body part 12...Second body part 13…Third body part 14…First overlapping section 15…Second overlapping section 20, 20A, 20B... Stiffening members 21, 21A, 21B...1st stiffening section 22, 22A, 22B…Second stiffening section 23…Connection 24, 24B...Outer cavity forming member 24I…Inlet 25, 25B…Inner cavity forming member 100, 100A, 100B…Structure

Claims

1. A structure comprising: A hollow tubular body portion; a stiffening member including a first stiffening portion formed on an outer surface of the main body portion, a second stiffening portion formed on an inner surface of the main body portion, and a connecting portion penetrating a side surface of the main body portion and connecting the first stiffening portion and the second stiffening portion; Equipped with The main body portion is A first body portion having a hollow tubular shape and a second body portion having a hollow tubular shape, one end of the second body portion being inserted into the first body portion, the first stiffening portion and the second stiffening portion are formed in a portion where the first main body portion and the second main body portion overlap, The first body portion and the second body portion are joined by the stiffening member. structure.

2. 2. The structure of claim 1, The shape of the stiffening member is derived by topology optimization. structure.

3. The structure according to claim 1 or 2, The stiffening member is joined to the main body without an adhesive. structure.

4. A structure according to any one of claims 1 to 3, The first stiffening portion is formed in an annular shape along an outer surface of the main body portion, The second stiffening portion is formed in an annular shape along an inner surface of the main body portion. structure.

5. A structure according to any one of claims 1 to 4, The first stiffening portion and the second stiffening portion are metal foams; The stiffening member is Further comprising a metal plate material covering each of the first stiffening portion and the second stiffening portion. structure.

6. A method for manufacturing a structure, comprising the steps of: Providing a hollow tubular body, the body having one or more through holes; A cavity forming member is disposed on the outer side and the inner side of the main body portion to form a cavity including the through hole of the main body portion; Flowing a fluid into the cavity; By solidifying the fluid poured into the cavity, a stiffening member is formed having a first stiffening portion formed on an outer surface of the main body portion, a second stiffening portion formed on an inner surface of the main body portion, and a connecting portion penetrating a side surface of the main body portion and connecting the first stiffening portion and the second stiffening portion. A method for manufacturing a structure.

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