JP7679100B2 - METHOD FOR MANUFACTURING METAL STRUCTURE, AND METAL STRUCTURE - Google Patents

Description

The present invention relates to a method for manufacturing a metal structure and a metal structure.

A conventional metal structure includes a metal structure having a main body and a lid. A lid groove is formed in the main body. A concave groove is further formed in the bottom surface of the lid groove in the main body. The lid is fitted into the lid groove. The main body and the lid are joined around the lid groove. As a result, the space surrounded by the concave groove and the lid becomes an internal space and can be used as a flow path for a fluid. Such a metal structure can be used as a metal structure for heat transfer. The metal structure for heat transfer is placed, for example, so as to be in contact with or in close proximity to an object to be heat exchanged, heated, or cooled. For example, when heat is to be released from an object, a cooling medium is passed through the flow path, and heat is transferred from the object to the metal main body and the cooling medium, thereby releasing the heat from the object.

Patent Document 1 discloses a technology for joining a body part and a lid part around a lid groove by friction stir welding, with respect to a metal structure.

JP 2014-240706 A

The present invention aims to provide a method for manufacturing a metal structure and a metal structure that ensures design freedom while suppressing or preventing the occurrence of defects at joints and the complication of the manufacturing process.

The inventors have investigated the above-mentioned problems and have come to the following findings.

1(a) and (b) are cross-sectional views that show a schematic diagram of the joining of the main body 101 and the lid 102 by friction stir welding. Note that the cross-sectional view here refers to a cross-sectional view obtained by a plane perpendicular to the direction in which the internal space 103, which serves as a fluid flow path, extends.

As shown in Fig. 1(a), a relatively large horizontal distance GD is ensured between the joint portion between the main body 101 and the lid 102 (the position where the tip 105a of the tool 105 passes) and the internal space 103. As shown in Fig. 1(b), if the distance GD is short, the metal base material 103a may enter the internal space 103 during friction stir welding, which may cause defects in the joint portion. Therefore, either (i) or (ii) below is required.
(i) The metal structure is designed so that the distance GD is sufficiently secured.
(ii) A joining method other than friction stir welding is employed for a portion where it is difficult to ensure the distance GD.

When a design is made to ensure sufficient distance GD, as in (i) above, it becomes difficult to arrange the internal spaces 103 closely together, for example, and this causes a problem of limited freedom in designing the metal structure. On the other hand, when friction stir welding is combined with other joining methods, as in (ii) above, there is a problem of the manufacturing process becoming complicated.

2(a) and (b) are longitudinal cross-sectional views that show a schematic view of the joining of the main body 101 and the lid 102 by friction stir welding. Note that the longitudinal cross-sectional view referred to here is a cross-sectional view obtained by a plane parallel to the direction in which the internal space 103, which serves as a fluid flow path, extends. However, since FIGS. 2(a) and (b) are longitudinal cross-sectional views based on the position where the tool 105 passes, the internal space 103 is not shown.

2(a), the lid portion 102 is fitted into a lid groove (not shown) formed in the main body portion 101. The tool 105 of the friction stir device (not shown) has a cylindrical shape and a thin tip portion 105a. The tool 105 is inclined with respect to the vertical direction VD so that the tip portion 105a is located further forward in the traveling direction of the tool 105. The inclination angle D (advance angle) is preferably, for example, greater than 0 degrees and less than 5 degrees, and more preferably greater than 1 degree and less than 4 degrees. However, when the tool 105 is moved in the traveling direction PD while the tool 105 has the inclination angle D, the lid portion 102 may be deformed in such a way that it floats up in front of the traveling direction PD as shown in FIG. 2(b). The ease of such deformation and the amount of deformation increase in proportion to the size (i.e., load) of the tool 105. Therefore, when the thickness of the lid portion 102 is large, there is a problem that the lid portion 102 is easily deformed during friction stir welding, and the tool 105 of the friction stir welding device is easily damaged. Therefore, it is difficult to adopt a lid portion 102 with a large thickness, and the design freedom of the metal structure may be limited. In addition, when a lid portion 102 with a large thickness is adopted, if the tool 105 is made larger to ensure the mechanical strength of the tool 105, the joint area must be made larger, which further limits the design freedom of the metal structure. In addition, measures are required to prevent or suppress deformation of the lid portion 102, which creates a problem of the manufacturing process becoming complicated.

Based on the above findings, the inventor has completed the present invention. The following configurations can be adopted as embodiments of the present invention.

(1) A method for producing a metal structure, comprising the steps of:
The metal structure includes two metal members that are joined by friction stir welding in a state where the metal members are overlapped with each other in a vertical direction,
The two metal members are configured to be overlapped with each other in the vertical direction to form an assembly having an internal space between the two metal members, and the assembly has a discontinuous portion where the two metal members are in contact or close to each other without being joined at a position exposed to the internal space inside the assembly, so that the two metal members are discontinuous, and a non-joint portion where the two metal members are in contact or close to each other without being joined at a position not exposed to the internal space inside the assembly, so that the two metal members have a boundary with each other, and is physically continuous with the discontinuous portion, and the non-joint portion includes an upper portion where the two metal members are in contact or close to each other in the vertical direction without being joined, at a position shallower than the discontinuous portion with respect to an upper surface of the assembly as a reference, when the assembly is viewed in the vertical direction, and each of the discontinuous portion and the upper portion is formed so as to surround the internal space when the assembly is viewed in the vertical direction,
The manufacturing method includes:
a preparation step of preparing the two metal members;
an assembly step of forming the assembly by overlapping the two metal members in the vertical direction;
a joining process in which a tool for the friction stir welding is inserted from the upper surface of the assembly to a joining depth while rotating and moved along the upper portion as viewed in the vertical direction to form a joint in which the two metal members are joined, and the joint is formed so that the non-joint portion remains at an inner position communicating with the internal space via the discontinuous portion;
The weld depth is a depth at which the friction stir weld reaches the upper portion but does not reach the depth of the discontinuous portion.

According to the manufacturing method of (1), in the joining step, a tool is inserted into the assembly so that the friction stir welding reaches the upper portion but does not reach the discontinuous portion. The upper portion is located at a position shallower than the discontinuous portion. Since the joint is formed at a shallow position, the tool is not inserted to a deep position. The load applied to the metal structure during joining can be reduced, and the size of the tool for friction stir welding can be suppressed or prevented. Deformation of the metal members can be suppressed or prevented. It becomes possible to use metal members with a large thickness. Since the distance between the tool insertion position and the internal space can be secured, it is possible to suppress or prevent the occurrence of a situation in which the metal base material flows into the internal space due to friction stir welding. In addition, a joint is formed by performing friction stir welding on the upper portion where the two metal members overlap vertically. Therefore, the occurrence of defects in the joint can be prevented.

As described above, the manufacturing method (1) can prevent defects from occurring while increasing the design freedom of the metal structure. In addition, the manufacturing method (1) makes it possible to join at a shallow position, making it easy to adopt friction stir welding. There is no need to combine friction stir welding with other joining methods, and a configuration that can be joined only by friction stir welding can be adopted. However, the joining of the two metal members in the metal structure (1) is not necessarily limited to friction stir welding. A joining method other than friction stir welding may be used in addition to friction stir welding. The adoption of the manufacturing method (1) improves the design freedom, makes it possible to adopt a structure that makes it easy to join two metal members, and reduces the disadvantages of combining joining methods.

(2) A manufacturing method according to (1), comprising the steps of:
In the joining step, the joined portion is formed such that the non-jointed portion has a portion extending in the vertical direction at the inner position.

According to the manufacturing method of (2), since the non-joint portion has a portion that extends vertically at the inner position, the distance between the non-joint portion and the joint portion can be secured in the vertical direction. Therefore, for example, the distance between the non-joint portion and the joint portion can be secured even if the horizontal distance between the non-joint portion and the joint portion is not sufficiently secured. As a result, for example, it is possible to arrange the internal spaces more densely. The occurrence of defects can be suppressed, and the design freedom can be improved while suppressing or preventing the manufacturing process from becoming complicated.

(3) A manufacturing method according to (1) or (2), comprising the steps of:
In the joining step, the joined portion is formed so that the non-jointed portion remains not only at the inner position but also at an outer position that does not communicate with the internal space.

According to the manufacturing method of (3), the joint is formed so that non-jointed portions remain on both sides of the joint (i.e., both the inner and outer positions). The occurrence of voids in the joint can be suppressed or prevented. As a result, it is possible to prevent defects in the metal structure, particularly defects in the internal space, while avoiding complication of the manufacturing process and improving the design freedom of the metal structure.

Note that since there is a joint between the outer non-joint portion (the non-joint portion remaining at the outer position) and the internal space, the outer non-joint portion does not communicate with the internal space. However, if the metal structure has another internal space, the outer non-joint portion may communicate with the other internal space. When viewed with the other internal space as a reference, the outer non-joint portion corresponds to an inner non-joint portion. The outer non-joint portion may also communicate with the outside of the metal structure.

(4) A manufacturing method according to any one of (1) to (3),
the upper portion is formed so as to surround the internal space at a position not overlapping with the internal space when the assembly is viewed in the vertical direction,
The discontinuous portion is formed so as to surround the internal space along an outer periphery of the internal space when the assembly is viewed in the vertical direction.

The manufacturing method (4) makes it possible to prevent defects in the metal structure, particularly defects in the internal space, while avoiding complication of the manufacturing process and improving the design freedom of the metal structure.

(5) A manufacturing method according to any one of (1) to (4),
The two metal members are a main body and a lid,
the main body portion has a shoulder portion formed to protrude toward the top surface of the assembly at a position corresponding to the upper portion when viewed in the vertical direction;
the cover portion has a bottomed groove formed to receive the shoulder portion when the cover portion is placed on the body portion,
The weld depth is a depth at which the friction stir weld reaches the shoulder portion but does not reach the depth of the discontinuous portion.

The manufacturing method (5) makes it possible to prevent defects in the metal structure, particularly defects in the internal space, while avoiding complication of the manufacturing process and improving the design freedom of the metal structure.

(6) A method for producing the product according to (5), comprising the steps of:
the body portion has a cover groove on a surface thereof into which the cover portion is fitted, and the shoulder portion is formed so as to protrude from a bottom surface of the cover groove toward the top surface of the assembly;
The lid portion has a shape that allows it to be fitted into the lid groove, and is configured so that the shoulder is received in the bottomed groove when the lid portion is fitted into the lid groove.

The manufacturing method (6) makes it possible to prevent defects in the metal structure, particularly defects in the internal space, while avoiding complication of the manufacturing process and improving the design freedom of the metal structure.

(7) The manufacturing method according to any one of (1) to (6),
The metal structure is a heat-transfer metal structure that is placed in contact with or in close proximity to an object to be heat-exchanged, heated, or cooled.

The manufacturing method of (7) above can improve the design freedom of the metal structure, particularly the design freedom of the internal space, while preventing the occurrence of defects. By making the internal space a fluid flow path, for example, it is possible to realize a metal structure in which flow paths with excellent fluid sealing properties are densely arranged. In other words, a metal structure with excellent heat transfer properties can be realized due to high sealing properties and design freedom. In other words, the manufacturing method of (7) can produce a metal structure suitable for heat transfer.

(8) The metal structure according to any one of (1) to (6),
The metal structure is a hollow metal structure that is used in a state where the internal space is hollow.

The manufacturing method (8) above can improve the design freedom of the metal structure, particularly the design freedom of the internal space, while preventing the occurrence of defects. By making the internal space hollow, for example, it is possible to realize a metal structure in which cavities are densely arranged. In other words, it is possible to realize a hollow metal structure with a high degree of design freedom regarding the combination of the mechanical strength, weight, and size of the structure.

(9) A metal structure comprising:
The metal structure is
An internal space provided inside the metal structure;
a discontinuous portion in which two metal parts constituting a metal wall portion defining the internal space are in contact with or close to each other without being joined at a position exposed to the internal space, so that the two metal parts are discontinuous;
an inner non-joined portion formed at an inner position communicating with the internal space via the discontinuous portion, the inner non-joined portion being configured such that the two metal portions have a boundary by being in contact or close to each other without being joined at a position inside the metal structure that is not exposed to the internal space;
a joint portion that closes one end of the inner non-joined portion at a position not exposed to the internal space inside the metal structure so that a boundary between the two metal portions is indistinguishable or difficult to distinguish;
the joint lies in one or substantially one plane and is formed to enclose the interior space when viewed in a vertical direction perpendicular or substantially perpendicular to the plane;
The discontinuous portion is formed so as to surround the internal space when viewed in the vertical direction,
The inner non-joint portion has a portion that extends in the vertical direction such that the discontinuous portion and the joint portion are located at different heights in the vertical direction.

The metal structure of (9) can prevent defects in the metal structure, particularly defects in the internal space, while avoiding complication of the manufacturing process and improving the design freedom of the metal structure.

(10) The metal structure according to (9),
The metal structure further comprises:
The two metal parts are configured to have a boundary by being in contact or close to each other without being joined at a position inside the metal structure that is not exposed to the internal space, and have an outer non-jointed portion that is located at an outer position that does not communicate with the internal space and has one end closed by the joint.

The metal structure of (10) above is manufactured so that the inner non-jointed portion and the outer non-jointed portion are located on either side of the joint. This can suppress or prevent the occurrence of voids in the joint during manufacturing.

(11) The metal structure according to (9) or (10),
The metal structure is a heat-transfer metal structure that is placed in contact with or in close proximity to an object to be heat-exchanged, heated, or cooled.

The metal structure of (11) above can improve the design freedom of the metal structure, particularly the design freedom of the internal space, while preventing the occurrence of defects. By making the internal space a fluid flow path, for example, a metal structure can be realized in which flow paths with excellent fluid sealing properties are densely arranged. In other words, a metal structure with excellent heat transfer properties can be realized due to high sealing properties and design freedom. In other words, the metal structure of (11) is suitable for heat transfer.

(12) The metal structure according to (9) or (10),
The metal structure is a hollow metal structure that is used in a state where the internal space is hollow.

The manufacturing method (12) above can improve the design freedom of the metal structure, particularly the design freedom of the internal space, while preventing the occurrence of defects. By making the internal space hollow, for example, it is possible to realize a metal structure in which cavities are densely arranged. In other words, it is possible to realize a hollow metal structure with a high degree of design freedom regarding the combination of the mechanical strength, weight, and size of the structure.

The present invention ensures design freedom while suppressing or preventing the occurrence of defects at the joints and the complication of the manufacturing process.

1(a) and 1(b) are cross-sectional views that typically show how a body portion and a cover portion are joined by friction stir welding. 2(a) and 2(b) are cross-sectional views that typically show how the body and the cover are joined by friction stir welding. FIG. 3(a) is a plan view that shows a schematic diagram of the metal structure, and FIG. 3(b) is a cross-sectional view taken along line AA of FIG. 3(a). 4A to 4C are cross-sectional views illustrating a manufacturing process of a metal structure according to an embodiment. FIG. 4 is a cross-sectional view showing a schematic view of a main body and a lid during joining. FIG. 6(a) is a plan view showing a schematic diagram of a metal structure according to another embodiment, and FIGS. 6(b) to 6(e) are cross-sectional views showing the manufacturing process thereof, and correspond to the cross-sectional view taken along line B-B in FIG. 6(a). FIG. 7(a) is a cross-sectional view showing a schematic diagram of a body portion and a lid portion during joining in a conventional metal structure, and FIG. 7(b) is a cross-sectional view showing a schematic diagram of a body portion and a lid portion during joining in the embodiment. 8(a) and 8(b) are cross-sectional views that typically show a conventional metal structure, and FIGS. 8(c) and 8(d) are cross-sectional views that typically show a metal structure according to the embodiment. FIG. 11 is a cross-sectional view that illustrates a metal structure according to another embodiment. 10A to 10C are cross-sectional views that typically show a method for manufacturing a metal structure according to another embodiment.

<<Metal structure according to one embodiment>>
First, a metal structure 10 according to an embodiment will be described. Fig. 3(a) is a plan view that shows the metal structure 10. Fig. 3(b) is a cross-sectional view taken along line AA in Fig. 3(a).

The metal structure 10 has an internal space 3, a discontinuous portion 3c, an inner non-joint portion 3d, a joint portion 3f, and an outer non-joint portion 3h.

The metal structure 10 is a plate-like body. As shown in FIG. 3(a), the metal structure 10 has a rectangular shape extending in the longitudinal direction (the vertical direction in FIG. 3(a)) in a plan view. As shown in FIG. 3(b), the metal structure 10 has a rectangular shape in a cross-sectional view. The metal structure 10 is configured to include a metal portion 1a and a metal portion 2a. The metal portion 1a and the metal portion 2a are joined to each other at a joint 3f. The metal structure 10 is made of copper. That is, the metal portion 1a and the metal portion 2a are made of copper. The metal constituting the metal structure 10 is not particularly limited. Examples of the metal include copper, aluminum, and an alloy containing at least one of these. Furthermore, the metal portion 1a and the metal portion 2a may be made of the same metal or different metals.

The internal space 3 is provided inside the metal structure 10. In a plan view, the internal space 3 has a shape that extends in the longitudinal direction (the up-down direction in FIG. 3(a)). The shape of the internal space is not particularly limited. The internal space may be U-shaped or zigzag-shaped. The number of internal spaces in one metal structure is not particularly limited, and may be one or more. The internal space 3 is defined by the metal wall portion 3b. The metal wall portion 3b is composed of a portion of the metal structure 10 that is exposed to the internal space 3. The metal wall portion 3b is composed of a portion composed of the metal portion 1a and a portion composed of the metal portion 2a. The metal portion 1a corresponds to the main body portion 1 described later. The metal portion 2a corresponds to the lid portion 2 described later. The metal portion 1a and the metal portion 2a are integrated by being joined at the joint portion 3f.

The discontinuous portion 3c is a portion configured such that the metal portion 1a and the metal portion 2a are discontinuous by being in contact or close to each other without being joined at a position where the metal portion 1a and the metal portion 2a are exposed to the internal space 3. The discontinuous portion 3c is formed so as to surround the internal space 3 when viewed in the vertical direction X.

The inner non-jointed portion 3d is a portion configured such that the metal portion 1a and the metal portion 2a have a boundary by contacting or approaching each other without being joined at a position not exposed to the internal space 3 of the metal structure 10, and is formed at an inner position communicating with the internal space 3 through the discontinuous portion 3c. That is, one end 3e of the inner non-jointed portion 3d is closed by the joint portion 3f, and the discontinuous portion 3c corresponds to the other end of the inner non-jointed portion 3d. The inner non-jointed portion 3d has a portion extending in the vertical direction X such that the discontinuous portion 3c and the joint portion 3f are located at different heights in the vertical direction X. The inner non-jointed portion 3d is located at an inner position of the joint portion 3f. The inner position of the joint portion 3f refers to a position that is relatively close to the internal space 3 and communicates with the internal space 3 through the discontinuous portion 3c. On the other hand, the outer position of the joint portion 3f refers to a position that is relatively far from the internal space 3 and does not communicate with the internal space 3.

The joint 3f is a portion that closes one end 3e of the inner non-joint portion 3d so that the boundary between the metal portion 1a and the metal portion 2a is indistinguishable or difficult to distinguish at a position that is not exposed to the internal space 3 of the metal structure 10. It is not necessary to strictly distinguish whether the boundary is indistinguishable or difficult to distinguish. The inflow and outflow of fluid can be blocked between the inner position and the outer position of the joint 3f. The joint 3f is located within one plane S. The plane S is a virtual plane. The vertical direction X refers to a direction that intersects the plane S perpendicularly or substantially perpendicularly. That is, the joint 3f is located at the same or substantially the same height (depth) in the vertical direction X. The plane S may have a width in the vertical direction X. The plane S including the joint 3f is included in the metal portion 2a. In other words, the joint 3f is formed in the metal portion 2a. Moreover, the joint 3f is formed so as to surround the internal space 3 when viewed in the vertical direction X, as shown in FIG. 3(a).

The outer non-jointed portion 3h is a portion configured such that the metal portion 1a and the metal portion 2a have a boundary by contacting or coming into close proximity with each other without being joined at a position not exposed to the internal space 3 of the metal structure 10, and is located at an outer position, with one end 3g closed by the joint portion 3f. The other end of the outer non-jointed portion 3h may be connected to the outside of the metal structure 10. If the metal structure 10 has another internal space 3, the other end of the outer non-jointed portion 3h may be connected to the other internal space 3. Depending on the structure of the metal structure, there may be no outer non-jointed portion at an outer position.

The internal space 3 is connected to the outside of the metal structure 10 via a through hole 3a formed in the metal part 2a. As shown in FIG. 3(a), two through holes 3a are formed in the metal part 2a. The through holes 3a are used, for example, as an inlet or outlet for a fluid such as a refrigerant. The number of through holes 3a is not particularly limited. There may be one through hole 3a or multiple through holes 3a. The through hole 3a is formed only in the metal part 2a, but may be formed only in the metal part 1a, or may be formed in both the metal part 1a and the metal part 2a.

The through hole 3a is formed in the metal part 2a. As described above, the joint 3f is also formed in the metal part 2a. In this way, it is preferable that the through hole 3a and the joint 3f are formed in one metal part 2a and not in the other metal part 1a. This prevents the flow of fluid between the internal space 3 and the outside of the metal structure 10 through the metal part 1a. For example, when a fluid such as a refrigerant is passed through the internal space 3, leakage of the fluid from the metal part 1a is prevented. Therefore, the metal part 1a can be suitably used as a heat transfer surface that contacts or is close to an object to be heat exchanged, heated, or cooled. In this embodiment, the metal part 1a has a heat transfer surface, but the metal part 2a may have a heat transfer surface. In addition, it is preferable that the internal space 3 is sealed except for the through hole 3a by forming the joint 3f around the entire outer periphery of the internal space 3 as shown in FIG. 3(a). Note that the through hole 3a is not an essential configuration.

The use of the metal structure 10 is not particularly limited. For example, the metal structure 10 may be a hollow metal structure used with the internal space 3 being hollow. The metal structure 10 may also be a heat transfer metal structure installed in contact with or close to an object to be heat exchanged, heated, or cooled. The metal structure 10 has an internal space 3 with excellent sealing properties. That is, the main body 1 and the lid 2 joined to each other at the joint 3f can block the flow of fluid between the internal space 3 and the outside of the metal structure 10. The metal structure 10 can be suitably used so that the internal space 3 functions as a flow path or a reservoir for the fluid. The fluid is, for example, a gas or liquid. When the metal structure 10 is used as a heat transfer metal structure, the fluid is, for example, a heat transfer fluid such as a refrigerant.

<<Method of Manufacturing a Metal Structure According to an Embodiment>>
Next, a method for manufacturing the metal structure 10 according to an embodiment will be described with reference to FIGS.

<Preparation process>
First, in the preparation step, the main body 1 is prepared as shown in Fig. 4(a) and the lid 2 is prepared as shown in Fig. 4(b). The main body 1 and the lid 2 each correspond to a "metal member".

The main body 1 is made of a metal material. There are no particular limitations on the metal material, so long as it is a metal material that can undergo plastic flow by softening due to the frictional heat of friction stirring. Examples of the metal material include copper, aluminum, and alloys containing at least one of these. The main body 1 is a plate-like body. The main body 1 is a long, plate-like body. The shape of the main body 1 is not limited to a plate-like body.

As shown in FIG. 4(a), the main body 1 has a first defining surface 1d for defining the internal space 3. In this embodiment, the internal space 3 corresponds to the space within a groove formed in the main body 1. The first defining surface 1d corresponds to the surface of the groove formed in the main body 1. The internal space 3 is defined by the first defining surface 1d of the main body 1 and the second defining surface 2d of the lid 2 shown in FIG. 4(b). A shoulder 4 is formed on the outside of the first defining surface 1d, as shown in FIG. 4(a).

The lid portion 2 is made of a metal material. There are no particular limitations on the metal material, so long as it is a material that can undergo plastic flow by softening due to the frictional heat of friction stirring. Examples of the metal material include copper, aluminum, or an alloy containing at least one of these. The material of the lid portion 2 may be the same as or substantially the same as the material of the main body portion 1, or may be different from the material of the main body portion 1.

As shown in FIG. 4(b), the lid portion 2 has a second defining surface 2d that defines the internal space 3 together with the first defining surface 1d. As shown in FIG. 4(d), the lid portion 2 has a contact surface 2b that abuts against the outer surface 1b of the main body portion 1 when the lid portion 2 is placed on the main body portion 1. A bottomed groove 6 for receiving the shoulder portion 4 is formed on the contact surface 2b. The bottomed groove 6 is a bottomed groove. The cross-sectional shape of the bottomed groove 6 is rectangular. In this embodiment, the first defining surface 1d forms a recess and the second defining surface 2d is a flat surface. However, the first defining surface 1d may be a flat surface and the second defining surface 2d may form a recess. In addition, both the first defining surface 1d and the second defining surface 2d may have recesses.

<Assembly process>
In the assembly process, as shown in FIG. 4(c), the lid 2 is placed on the main body 1 so that the shoulder 4 of the main body 1 is received in the bottomed groove 6 of the lid 2. This forms an assembly 10a having an internal space 3. In the assembly 10a, the main body 1 is located at the bottom and the lid 2 is located at the top in the vertical direction. The assembly 10a has a discontinuous portion 3c and a non-joint portion 3n. The non-joint portion 3c is a portion configured such that the main body 1 and the lid 2 have a boundary with each other by contacting or approaching each other without being joined at a position exposed to the internal space 3 of the assembly 10a. The non-joint portion 3n is configured such that the main body 1 and the lid 2 have a boundary with each other by contacting or approaching each other without being joined at a position not exposed to the internal space of the assembly 10. The non-joint portion 3n is a boundary between the main body 1 and the lid 2. The non-jointed portion 3n is also physically connected to the discontinuous portion 3c, which is the boundary between the main body portion 1 and the lid portion 2. In the assembly 10a, the non-jointed portion 3n includes an upper portion 8. The upper portion 8 is a portion where the main body portion 1 and the lid portion 2 are not joined to each other and are in contact or close to each other in the vertical direction X at a position shallower than the discontinuous portion 3c with respect to the top surface 2c of the assembly 10a when the assembly 10a is viewed in the vertical direction X. The upper portion 8 is a portion where the shoulder portion 4 and the bottomed groove 6 overlap in the vertical direction X. The discontinuous portion 3c and the upper portion 8 are formed to surround the internal space 3 when the assembly 10a is viewed in the vertical direction X (see FIG. 3(a)).

<Joining process>
The joining process is performed on the assembly 10a as shown in FIG. 5. In the joining process, the main body 1 and the cover 2 are joined by friction stir welding. A tool 5 of a friction stir device (not shown) is used in the joining process. The tool 5 is made of a material with high heat resistance and wear resistance. The tool 5 is a cylindrical body having a tapered tip 5a at its tip. The tool 5 is controlled by a drive device provided in the friction stir device so as to move while rotating. Specifically, the tool 5 can move up and down relative to the main body 1 and the cover 2 and move parallel to the main body 1 and the cover 2 while rotating. The up and down movement is a movement in the vertical direction X. The parallel movement is a movement perpendicular to the vertical direction X. The tip 5a of the tool 5 has a spiral screw groove (not shown) on the outer circumferential surface.

In the joining process, the tool 5 is inserted from the upper surface 2c of the assembly 10a to the joining depth in the lid portion 2 while rotating. The upper surface 2c of the assembly 10a corresponds to the surface opposite to the contact surface 2b in the lid portion 2. FIG. 5 shows the state in which the tool 5 is inserted to the joining depth while rotating. The joining depth is a depth at which the friction stir welding depth WD reaches the shoulder portion 4 received in the bottomed groove 6 but does not reach the outer surface 1b (discontinuous portion 3c). In other words, the joining depth is set so that the friction stir welding depth WD satisfies depth SD≦WD<depth OD. As shown in FIG. 5, the depth SD is the depth from the upper surface 2c of the lid portion 2 to the shoulder portion 4. The depth OD is the depth from the upper surface 2c of the lid portion 2 to the outer surface 1b (discontinuous portion 3c). At this time, the joining portion 3f is formed so that the non-joint portion 3n remains in an inner position communicating with the internal space 3 via the discontinuous portion 3c. As a result, the non-jointed portion 3n remains as an inner non-jointed portion 3d (see FIG. 3(b)). Furthermore, the non-jointed portion 3n also remains as an outer non-jointed portion 3h (see FIG. 3(b)). The width of the shoulder portion 4 (upper portion 8) is not particularly limited and may be greater than or less than the width of the tip 5a of the tool 5. The shoulder portion 4 protrudes upward from the outer surface 1b, but has a height that does not reach the surface 1s of the main body portion 1.

In this manner, while the tool 5 is inserted to the joining depth WD while rotating, the tool 5 is moved along the shoulder 4 (see FIG. 3(a)) in a plan view. The metal material of the top of the shoulder 4 and the bottom of the bottomed groove 6 is stirred and integrated while being fluidized in a solid phase by frictional heat. This joins the top of the shoulder 4 and the bottom of the bottomed groove 6. As a result, the body 1 and the lid 2 are joined. This produces a metal structure 10 formed by friction stir welding the body 1 and the lid 2. In this embodiment, since the tool 5 does not reach the depth of the internal space 3, the horizontal distance GD between the upper part 8 (the position where the tip 5c of the tool 5 passes) and the internal space 3 can be shortened. The distance GD in this embodiment is shorter than the distance GD in FIG. 1(a).

The manufacturing method of the metal structure 10 may include steps other than the preparation step, the assembly step, and the joining step. For example, the manufacturing method of the metal structure 10 may include a step for positioning the main body 1 and the lid 2 between the assembly step and the joining step. The positioning may be performed by a mechanical means such as a clamping means. The positioning may be performed by forming a plurality of joints by friction stir welding at intervals. The joints may be point-like or may be linear having a predetermined length. In addition, in the positioning step, a plurality of point-like joints may be formed, followed by a plurality of linear joints. In addition, after the joining step, a flattening process may be performed to remove burrs generated in the joining step. Furthermore, as described with reference to FIG. 2, the tool 5 may be tilted in the joining step.

<<Other embodiments>>
Next, other embodiments will be described. Figure 6(a) is a plan view showing a metal structure 10 according to another embodiment, and Figures 6(b) to 6(e) are cross-sectional views showing the manufacturing process thereof, which correspond to the cross-sectional view along line B-B in Figure 6(a). The same reference numerals are used to designate the same components as those in the embodiments of Figures 3 to 5.

As shown in FIG. 6(a), in the metal structure 10 according to this embodiment, two lids 2 are provided for one main body 1. One main body 1 and two lids 2 correspond to "metal members". In this way, the metal structure may be configured to include three or more metal members. In addition, in the metal structure 10 according to this embodiment, one lid 2 and one main body 1 correspond to "two metal members joined by friction stir welding in a state where they are stacked vertically on each other", and the other lid 2 and one main body 1 also correspond to "two metal members joined by friction stir welding in a state where they are stacked vertically on each other". In this way, the metal structure may have multiple combinations that correspond to "two metal members".

As shown in FIG. 6(a), the metal structure 10 is a rectangular plate-like body extending in the longitudinal direction (the vertical direction in the figure). The metal structure 10 has multiple (two) internal spaces 3. Each internal space 3 is independent of the others. Each internal space 3 has a shape extending in the longitudinal direction. Each internal space 3 is parallel to each other.

The manufacturing method of this embodiment will be explained using Figures 6(a) to (e).

First, in the preparation process, one main body 1 and two lids 2 are prepared as shown in Figures 6(a) and (b).

The main body 1 has two lid grooves 7 on the surface 1s of the main body 1. The lid grooves 7 have a shape that extends in the longitudinal direction, as shown in FIG. 6(a). The bottom surface of the lid groove 7 corresponds to the outer surface 1b, as shown in FIG. 6(b). A shoulder 4 is formed on the outer surface 1b. As shown in FIGS. 6(a) and (b), the shoulder 4 is formed along the side edge of the recessed groove (internal space 3) and protrudes from the surface of the lid groove 7 (external surface 1b). The bottom surface of the recessed groove corresponds to the first defining surface 1d.

As shown in FIG. 6(c), each of the two lid parts 2 has a shape that allows it to be fitted into the lid groove 7 as a whole. The lid part 2 has a bottomed groove 6 on the contact surface 2b. The contact surface 2b refers to the surface of the lid part 2 that comes into contact with the main body part 1 when the lid part 2 is fitted into the lid groove 7. The bottomed groove 6 has a shape that allows it to receive the shoulder part 4. It is preferable that the bottomed groove 6 is formed so that no gap is created when the shoulder part 4 is received.

Next, in the assembly process, as shown in FIG. 6(d), each lid portion 2 is placed on the main body portion 1 so that it fits into the lid groove 7 of the main body portion 1. Multiple (two) internal spaces 3 are defined by one main body portion 1 and two lid portions 2. One internal space 3 is defined for each lid portion 2. The numerical relationship between the main body portion 1, lid portions 2, and internal spaces 3 is not limited to these examples and can be set as appropriate. As a result, an upper portion 8 is generated between the main body portion 1 and the lid portion 2, where the shoulder portion 4 and the bottomed groove 6 overlap in the vertical direction X. The upper portion 8 is located shallower than the discontinuous portion 3c in the vertical direction X.

Next, in the joining process, as shown in FIG. 6(e), friction stir welding is performed on the upper portion 8 to form the welded portion 3f. The friction stir welding reaches the upper portion 8 but does not reach the discontinuous portion 3c.

Through the above steps, a metal structure 10 having two internal spaces 3 is manufactured.

According to this embodiment, multiple internal spaces that are independent of each other and closely arranged can be formed within the metal structure, ensuring a wide degree of design freedom. Furthermore, according to this embodiment, even when a thick plate-like body is used as the lid portion 2, a wide degree of design freedom can be ensured. This point will be explained with reference to Figures 7(a) and 7(b).

In Figures 7(a) and (b), the thickness OD of the lid portion 2 is large. Specifically, the thickness OD is larger than the thickness T of the main body portion 1.

Figure 7(a) is a cross-sectional view showing a schematic of the body 1 and lid 2 during welding in a conventional metal structure. The depth to which the tip 5a of the tool 5 is inserted, i.e., the welding depth, is set so that the friction stir welding depth WD satisfies WD ≥ depth OD. Since the tip 5a of the tool 5 is inserted deeply, there is a risk of significant deformation of the lid 2. In addition, in order to suppress or prevent a decrease in the airtightness of the internal space 3 due to such deformation, it is necessary to ensure a wide distance GD between the tip 5a of the tool 5 and the internal space 3 in the horizontal direction.

Figure 7 (b) is a cross-sectional view showing a schematic diagram of the main body and lid during welding according to the embodiment. The welding depth is set so that the friction stir welding depth WD satisfies depth SD ≤ WD < depth OD. Since the tip 5a of the tool 5 is not inserted deeply, the risk of significant deformation of the lid 2 can be reduced or prevented. As a result, the distance GD can be set narrow. Along with the degree of freedom in designing the internal space, a wide degree of freedom in designing the thickness of the metal member can also be ensured.

Next, the shape of the non-jointed portion will be explained using Figures 8(a) to (d).

Figure 8(a) is an explanatory diagram of a conventional method for manufacturing a metal structure. Figure 8(b) is an explanatory diagram of a conventional metal structure. As shown in Figure 8(a), in the assembly 110a, the contact surface between the main body 101 and the lid 102 is flat. The tip 105a of the tool 105 is inserted into the lid 102 and reaches the main body 101. After joining, as shown in Figure 8(b), the discontinuous portion 103c, the inner non-joint portion 103d, the joint portion 103f, and the outer non-joint portion 103h are located at the same height.

8(c) is an explanatory diagram of a manufacturing method of a metal structure according to an embodiment. FIG. 8(d) is an explanatory diagram of a metal structure according to an embodiment. As shown in FIG. 8(c), in the assembly 10a, the main body 1 has a shoulder 4. The lid 2 has a bottomed groove 6 for receiving the shoulder 4. Therefore, the upper portion 8 where the shoulder 4 and the bottomed groove 6 overlap vertically is located higher than the discontinuous portion 3c in the vertical direction X. After joining, as shown in FIG. 8(d), the inner non-joined portion 3d and the outer non-joined portion 3h have portions that extend vertically. As a result, the joint 3f is located higher than the discontinuous portion 3c. As a result, the horizontal distance between the joint 3f and the internal space 3 in FIG. 8(d) is shorter than the horizontal distance between the joint 103f and the internal space 103 in FIG. 8(b).

Figure 9 is a cross-sectional view that shows a schematic diagram of a metal structure 10 according to another embodiment. The metal structure 10 shown in Figure 9 has multiple internal spaces 3. The main body 1 has multiple shoulders 4. The shoulders 4 are configured to separate adjacent internal spaces 3. The lid 2 has multiple bottomed grooves 6. Each bottomed groove 6 is configured to receive a shoulder 4.

In the metal structure 10 shown in FIG. 9, when the central internal space 3 is used as a reference, the inner non-joint portion 3d, the joint portion 3f, and the outer non-joint portion 3h are connected in order from the discontinuous portion 3c at the top right, and the outer non-joint portion 3h is connected to the discontinuous portion 3c located at the top left of the right internal space 3. Here, the outer non-joint portion 3h does not communicate with the central internal space 3.

On the other hand, when the right internal space 3 is used as a reference, the inner non-jointed portion 3d, the jointed portion 3f, and the outer non-jointed portion 3h are connected in order from the upper left discontinuous portion 3c, and the outer non-jointed portion 3h is connected to the discontinuous portion 3c located in the upper right of the central internal space 3. Here, the outer non-jointed portion 3h does not communicate with the right internal space 3.

In this way, the outer non-jointed portion 3h when viewed from one internal space 3 as a reference may correspond to the inner non-jointed portion 3d when viewed from the adjacent internal space 3 as a reference.

The metal structure 10 shown in FIG. 9 is configured so that adjacent internal spaces 3 are separated only by shoulder portions 4. This allows the metal structure 10 to have multiple internal spaces 3 arranged more densely. Greater design freedom can be achieved.

Figure 10 is a cross-sectional view that shows a schematic diagram of a manufacturing method of a metal structure 10 according to another embodiment. In the assembly 10a shown in Figure 10, the upper portion 8 is located at a higher position in the vertical direction X than the discontinuous portion 3c. The upper portion 8 is where the main body portion 1 and the lid portion 2 overlap in the vertical direction. At the inner position of the upper portion 8, the non-joint portion 3n extends downward and communicates with the internal space 3 via the non-joint portion 3c. On the other hand, at the outer position of the upper portion 8, the non-joint portion 3n extends upward and communicates with the outside of the assembly 3c. In this way, the upper portion 8 forms a step.

In the example shown in FIG. 10, friction stir welding is performed by inserting the tip 5a of the tool 5 into the non-joint portion 3n extending upward together with the upper portion 8. Therefore, in the example shown in FIG. 10, an outer non-joint portion is not generated. In this way, an outer non-joint portion does not necessarily have to be generated. By performing friction stir welding on the stepped upper portion 8, airtightness can be improved. Furthermore, when there is a non-joint portion extending upward as shown in FIG. 10, airtightness can be further improved by performing friction stir welding so that at least the non-joint portion remains as an outer non-joint portion.

Furthermore, the numerical values, materials, structures, shapes, etc. given in the above-mentioned embodiments and examples are merely examples, and numerical values, materials, structures, shapes, etc. different from these may be used as necessary.

1 Main body portion 1a Metal portion 1b Outer surface 1d First defining surface 2 Lid portion 2a Metal portion 2b Contact surface 2c Upper surface 2d Second defining surface 3 Internal space (recess)
3a Through hole 3b Metal wall 3c Discontinuous part 3d Inner non-joint part 3e (Inner non-joint part) One end 3f Joint part 3g (Outer non-joint part) One end 3h Outer non-joint part 3n Non-joint part 4 Shoulder part 5 Tool 5a Tip part 6 Bottomed groove 7 Cover groove 10 Metal structure 10a Assembly

Claims (5)

A metal structure,
The metal structure is a plate-like body and includes a plate-like main body portion and a plate-like lid portion that are stacked vertically on each other ,
The plate-shaped body portion has an outer surface of the plate-shaped body portion, a shoulder portion protruding from the outer surface, and a first defining surface,
The plate-shaped cover portion has a contact surface that contacts the outer surface, a bottomed groove formed to receive the shoulder portion, and a second defining surface,
The metal structure is
an internal space defined by the first boundary surface and the second boundary surface within the metal structure;
a discontinuous portion in which the plate-shaped main body portion and the plate-shaped lid portion are in contact with or close to each other without being joined to each other at a position exposed to the internal space, and which is formed so as to surround the internal space when viewed in the vertical direction ;
an inner non-joined portion formed at an inner position communicating with the internal space via the discontinuous portion, the inner non-joined portion being configured such that the plate-shaped main body portion and the plate-shaped lid portion have a boundary by being in contact or close to each other without being joined at a position inside the metal structure that is not exposed to the internal space;
a joining portion that closes one end of the inner non-joined portion at a position that is not exposed to the internal space inside the metal structure so that the boundary between the plate-shaped main body portion and the plate-shaped lid portion is indistinguishable or difficult to distinguish,
The joint is
A metal structure characterized in that, when viewed in the vertical direction, the shoulder protruding from the outer surface of the plate-shaped main body and the bottomed groove of the plate-shaped lid portion are formed in the upper portion where they overlap in the vertical direction, so as to surround the internal space, and are located in one or substantially one plane at a depth that does not reach either the depth of the discontinuous portion or the depth of the internal space , thereby causing the inner non-joint portion to have a portion extending in the vertical direction such that the joint portion is at a higher position than the discontinuous portion in the vertical direction. The metal structure according to claim 1 ,
The metal structure further comprises:
A metal structure characterized in that the plate-shaped main body portion and the plate-shaped lid portion are configured to have a boundary by being in contact or close to each other without being joined at a position inside the metal structure that is not exposed to the internal space, and has an outer non-jointed portion located at an outer position that does not communicate with the internal space, one end of which is closed by the joint. The metal structure according to claim 1 ,
The first defining surface and the second defining surface are
the first demarcated surface is concave and the second demarcated surface is flat;
the first boundary surface is flat and the second boundary surface is recessed; or
A metal structure, wherein both the first and second defined surfaces have a recess. The metal structure according to claim 1 or 2,
The metal structure is a heat transfer metal structure that is placed in contact with or in close proximity to an object to be heat exchanged, heated or cooled. The metal structure according to claim 1 or 2,
The metal structure is a hollow metal structure used in a state where the internal space is hollow.