JP7645707B2 - Structure and method for manufacturing the structure - Google Patents

Description

The present invention relates to hollow structures that form moving bodies such as vehicles and structures such as buildings.

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 have been proposed to improve the rigidity of such hollow structures (see, for example, Patent Documents 1 to 4). Patent Document 1 discloses a configuration in which multiple resin stiffening members are arranged in the space formed between the outer panel and the inner panel. Patent Document 2 discloses a configuration in which a foam stiffening member is arranged between a body frame member and the outer panel of the 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 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 the upper side and the lower side is arranged as a stiffening member in the internal space of a hollow member in an automobile subframe structure.

JP 2019-64569 A JP 2018-8587 A JP 2019-26168 A JP 2020-83018 A

However, there is a demand for further improvements in the rigidity of hollow structures. This issue is not limited to automobile structures, but is also a common issue for the structures of various moving objects, buildings, and other structures.

The present invention has been made to solve the above-mentioned problems, and aims to provide a technology that improves the rigidity of hollow structures.

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

(1) According to one aspect of the present invention, a structure is provided. The structure includes a hollow tubular main body, a first stiffening portion formed on the outer surface of the main body, a second stiffening portion formed on the inner surface of the main body, and a connecting portion that penetrates the side surface of the main body and connects the first stiffening portion and the second stiffening portion.

According to this configuration, the 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 the rigidity. The second stiffening member formed on the inner surface of the main body improves the 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.

(2) In the structure of the above configuration, 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.

(3) In the structure of the above form, 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 when the stiffening member is joined to the main body with an adhesive.

(4) In the structure of the above configuration, at least a portion of the stiffening member may be a foam. This can contribute to weight reduction.

(5) In the structure of the above form, the foam may be a metal foam. In this way, the rigidity can be improved compared to a resin foam.

(6) According to another aspect of the present invention, a method for manufacturing a structure is provided. The method for manufacturing a structure includes preparing a hollow tubular main body having one or more through holes, forming a cavity including the through hole 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 the side surface of the main body and connects the first stiffening part and the second stiffening part.

This manufacturing method allows the stiffening member to be formed and joined to the main body. Therefore, compared to a manufacturing method in which a separately manufactured stiffening member is joined to a structure, the manufacturing process can be reduced, and the manufacturing costs of a highly rigid structure can be reduced.

The present invention can be realized in various forms, for example, in the form of a moving body equipped with a structure, a structure equipped with a structure, etc.

FIG. 2 is an explanatory diagram illustrating a schematic external configuration of the structure of the first embodiment. FIG. 2 is an explanatory diagram illustrating a schematic configuration of a main body portion. FIG. 2 is an explanatory diagram illustrating a schematic external configuration of a stiffening member. 3 is an explanatory diagram illustrating a schematic external configuration of a first stiffening portion and a second stiffening portion. FIG. FIG. 4 is an explanatory diagram illustrating a schematic cross-sectional configuration of a stiffening member. FIG. 13 is an explanatory diagram of a method for deriving an optimal shape of a stiffening member. FIG. 11 is an explanatory diagram illustrating a schematic configuration of a structure according to a second embodiment. FIG. 13 is an explanatory diagram illustrating a schematic configuration of a structure according to a third embodiment.

First Embodiment
1 is an explanatory diagram that shows a schematic external configuration of a structure 100 of the 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 the structure 100 of this embodiment, one used as a body skeleton structure of a vehicle is exemplified.

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

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

The main body 10 can be made from a variety of materials, including metals such as iron, stainless steel, and aluminum, alloys, resin materials such as carbon fiber reinforced plastic, and wood.

Figure 3 is an explanatory diagram showing 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.

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

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 arranged 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 of the main body portion 10 and connects the first stiffening portion 21 and the second stiffening portion 22. As shown in FIGS. 3, 4, and 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.

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, taking into consideration the 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, etc. that are not foams may be used.

Next, a method for deriving the shape of the stiffening member 20 by topology optimization will be described with reference to FIG.
6A and 6B are explanatory diagrams 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 portion between the first body portion 11 and the third body portion 13. FIG. 6A 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 body portion 12.

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 acting on the entire structure 100. As boundary conditions, the lower end is constrained and a load is set at the upper end. Then, topology optimization is used to derive a shape that maximizes rigidity. This derives the shapes of the first stiffening portion 21 and the second stiffening portion 22 shown in Figure 4.

Next, a method for manufacturing the structure 100 will be described.
First, as shown in Fig. 2, a main body 10 (Fig. 2) having 16 through holes 10H formed therein is prepared. The main body 10 having the through holes 10H formed therein may be formed by arranging the first main body 11, the second main body 12, and the third main body 13, each having a through hole formed therein, so that the positions of the through holes are aligned. Alternatively, after inserting the end of the second main body 12 into the first main body 11 and the third main body 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.

Cavity-forming members that form a cavity including the 16 through holes 10H of the main body 10 are arranged on the outside and inside 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.

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, the stiffening member 20 is a metal foam, so 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 is.

In this manufacturing method, the cavity formed by the cavity-forming member and the main body 10 includes the through hole 10H. That is, the cavity formed on the outside of the main body 10 and the cavity formed on the inside of the main body 10 are connected by the through hole 10H of the main body 10. Therefore, for example, when a fluid is poured into the cavity formed on the outside of the main body 10, the fluid flows into the cavity on the inside of the main body 10 through the through hole 10H. The connection part 23 is formed by the fluid that has flowed into the through hole 10H solidifying. That is, when the entire cavity is filled with the fluid and solidified, the stiffening member 20 in which the first stiffening part 21 and the second stiffening part 22 are connected by the connection part 23 is completed. In addition, according to this manufacturing method, the fluid filled in the cavity solidifies, 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 a structure 100 in which the body portion 10 and the stiffening member 20 are integrated without using adhesive. In other words, it is possible to omit 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.

As described above, according to the structure 100 of this embodiment, the stiffening members 20 are disposed both inside and outside the main body 10. The first stiffening members 21 formed on the outer surface 10o of the main body 10 improve the second moment of area, thereby improving the rigidity. The second stiffening members 22 formed on the inner surface 10i of the main body 10 improve the 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 a hollow member. As a result, deformation of the structure 100 when an external force is applied to the structure 100 can be suppressed.

In addition, 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 to form a shape in which the main body part 10 and the stiffening member 20 are integrated.

The shape of the stiffening member 20 in this embodiment is derived by topology optimization, so that the shape with the highest rigidity 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 rigidity of the structure 100.

The stiffening member 20 in this embodiment is a metal foam, so it can be made lighter than a solid metal body and has higher rigidity than a resin foam.

In addition, 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. In other words, according to this manufacturing method, the main body 10 and the stiffening member 20 can be joined without using adhesive. Therefore, compared to a manufacturing method in which a separately manufactured stiffening member is joined to the structure using adhesive, it is possible to reduce the manufacturing process and reduce the manufacturing cost of a highly rigid structure.

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 fluid by pouring the fluid into the cavity on the outside of the main body 10. This makes it easier to manufacture the stiffening member 20.

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 cross section taken along CC in 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.

The structure 100A of this embodiment has two stiffening members 20A. One of the two stiffening members 20A is formed 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 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 metal foam bodies, as in the first embodiment. The outer cavity forming member 24 and the inner cavity forming member 25 are formed of metal plate material. That is, a part of the stiffening member 20A of this embodiment is a foam body. The shape of the stiffening member 20A in this embodiment was determined without using an optimization method.

The structure 100A of this embodiment is manufactured by the same method as the manufacturing method 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 left as they are after the fluid is solidified.

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

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 the outer cavity forming member 24 and the inner cavity forming member 25 can be easily formed.

Third Embodiment
Fig. 8 is an explanatory diagram that shows a schematic configuration of a structure 100B of the third embodiment. Fig. 8(a) shows a side view of the structure 100B, and Fig. 8(b) shows a cross section taken along line D-D in 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.

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 from a metal plate material. That is, a portion 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.

The structure 100B of this embodiment is formed 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 located, and in this manner, the rigidity of the structure 100 can be appropriately improved.

The stiffening member 20B of this embodiment is also easy to form because of its simple shape. In addition, the outer cavity forming member 24B and the inner cavity forming member 25B are easy to form because of the simple shape of the cavity.

<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.

- In the above embodiment, a configuration in which the first body 11 and the third body 13 are connected via the second body 12 is exemplified as the main body 10, but the configuration of the main body 10 is not limited to the above embodiment. For example, it may be configured to connect four or more hollow tubular members, or it may be a single hollow tubular member. Even when the main body 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.

- In the above embodiment, a linear structure 100 is illustrated, but the shape of the structure is not limited to a linear shape and may be curved or bent.

- The cross-sectional shape of the structure 100 is not limited to the above embodiment. For example, it can 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 in parts.

- In the above embodiment, an example was shown in which the structure 100 is formed into a tube shape that is open at both ends, but this is not limited to this. For example, it may be formed into a one-sided tube shape with one end open and the other end closed, or it may be formed into a both-ended tube shape with both ends closed.

- In the first embodiment described above, an example was shown in which the shape of the stiffening member 20 was 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.

- In the above embodiment, a configuration in which the stiffening member is joined to the main body portion without adhesive is exemplified, but the stiffening member may be joined to the main body portion via adhesive.

- In the above embodiment, an example is 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. If they are formed separately, they may be formed from different materials.

- The manufacturing method of the structure is not limited to the above embodiment. For example, a preformed reinforcing member may be joined 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.

- 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 portion on the inner surface 10i of the main body portion 10. In this way, the cavity-forming member can be easily removed after the stiffening member is formed.

- In the above embodiment, the structure is exemplified as a body frame structure for a vehicle, but the present invention can be applied to structures for various moving objects such as aircraft and trains, and structures for buildings and other structures.

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 do not 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. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

REFERENCE SIGNS LIST 10...Main body portion 10H...Through hole 10i...Inner surface 10o...Outer surface 11...First main body portion 12...Second main body portion 13...Third main body portion 14...First overlapping portion 15...Second overlapping portion 20, 20A, 20B...Stiffening member 21, 21A, 21B...First stiffening portion 22, 22A, 22B...Second stiffening portion 23...Connection portion 24, 24B...Outer cavity forming member 24I...Injection port 25, 25B...Inner cavity forming member 100, 100A, 100B...Structure

Claims (6)

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.
Struct. 2. The structure of claim 1,
The shape of the stiffening member is derived by topology optimization.
Struct. The structure according to claim 1 or 2,
The stiffening member is joined to the main body without an adhesive.
Struct. 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.
Struct. 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.
Struct. 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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