Joint body and its manufacturing method, as well as bonding tool

Abstract

To provide a joint body which attains high efficiency and high reliability of joint of base materials to each other and, at the same time, can suppress deterioration of joint characteristics, a manufacturing method of the joint body as well as a joint tool.SOLUTION: A joint body includes a tabular first member, a second member overlapped on the first member in a plate thickness direction of the first member and a joint structure which joins the first member and a second member, the joint structure has a joint which joins the first member and the second member, and a deformation part which is provided on at least one side of the first member and the second member and is overlapped on the joint in a plate thickness direction, a shape of the main body of the joint is an annular shape along an edge of the joint structure when viewed from the plate thickness direction, a width of the main body part of the joint is 1 mm or more, is less than a half of the shortest size of the joint structure along the direction orthogonal in the plate thickness and, on at least a part in a region surrounded by the joint in the joint structure, the first member and the second member are overlapped to each other, however, are not joined.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a joined body, a method for manufacturing the same, and a joining tool. [Background technology]

[0002] In the manufacturing of industrial products, such as automobiles, research and development has been progressing in recent years into the possibility of using joined bodies (joints of dissimilar materials) made of not only the same metal type but also different metal types, such as metal and resin. The joints included in the joined structure of the base materials in a joined body of dissimilar materials are formed by known joining methods (e.g., resistance spot welding, friction stir welding, ultrasonic welding, etc.), but due to their structure, stress tends to concentrate at the joints. Here, the joined structure in a joined body of dissimilar materials tends to have weaker interfaces than the base materials. As a countermeasure to this tendency, for example, Patent Document 1 listed below discloses a friction stir welding tool used when friction stir welding metal and resin.

[0003] The friction stir welding tool disclosed in Patent Document 1 below has a substantially cylindrical base and a friction stir surface formed by the end face of the base, with a disk-shaped recess in the center of the friction stir surface. By providing such a disk-shaped recess in the base, it is said that the amount of frictional heat generated in the disk-shaped recess is reduced, thereby making it possible to uniformize the temperature at the interface to be welded. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2023-68730 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when forming a joint between overlapping base materials by friction stir welding, not only for dissimilar material joints, friction stirring is generally performed for at least several seconds from the viewpoint of joint strength. This forms a welded structure throughout the entire friction-stirred area. Depending on the type of base material, there is a concern that the joint strength (joint characteristics) of the welded structure may be reduced due to deformation of the base material caused by heat input to the base material during the formation of the welded structure. If the friction stir welding time is shortened to address this concern, the base materials may not be sufficiently joined, resulting in a decrease in the joint strength of the welded structure. This concern can arise not only when using friction stir welding, but also when using linear friction welding, friction stir spot welding, resistance spot welding, and other methods.

[0006] An object of one aspect of the present disclosure is to provide a joined body that can suppress deterioration of joint characteristics while realizing high efficiency in joining base materials, a manufacturing method thereof, and a joining tool. [Means for solving the problem]

[0007] To improve the joint characteristics of a joint structure between overlapping base materials, measures such as ensuring a sufficient joint area and extending the joining time are typically considered. However, simply increasing the joint area or extending the joining time can lead to reduced productivity (lower joining efficiency) of the joint structure. Furthermore, depending on the material contained in the base materials, extending the joining time may actually degrade the joint characteristics. In response to this, the inventors, after extensive research, discovered that when at least one of the members to be joined has a plate shape, the fracture characteristics of the edge region of the joint structure between the base materials significantly affect the joint characteristics. Based on this finding, the inventors further studied and found that the joint strength of an annular joint structure with a width of 1 mm or more formed along the contour of the intended joint area between the base materials is comparable to the joint strength of a joint structure formed over the entire intended joint area.

[0008] A joined body according to one aspect of the present disclosure, which was made based on the above-mentioned findings, comprises a plate-shaped first member, a second member overlapping the first member in the plate thickness direction of the first member, and a joining structure joining the first member and the second member, wherein the joining structure has a joint joining the first member and the second member, and a deformed portion provided on at least one of the first member and the second member and overlapping the joint in the plate thickness direction, wherein the shape of the main body of the joint is a ring shape that follows the edge of the joining structure when viewed from the plate thickness direction, the width of the main body of the joint is 1 mm or more and less than half the shortest dimension of the joining structure along a direction perpendicular to the plate thickness direction, and in at least a part of the area surrounded by the joint in the joining structure, the first member and the second member overlap in the plate thickness direction but are not joined.

[0009] According to this joined structure, the shape of the main body of the joint included in the joined structure is annular along the edge of the joined structure when viewed in the plate thickness direction. In at least a portion of the region surrounded by the joint in the joined structure, the first and second members overlap in the plate thickness direction but are not joined. This limits the areas of the first and second members that are heated compared to when a joint is formed throughout the entire joined structure. This reduces the time and joining area required to form the joint included in the joined structure, allowing for efficient joint formation. Furthermore, the width of the main body of the joint is 1 mm or more and less than half the shortest dimension of the joined structure along a direction perpendicular to the plate thickness direction. This allows for the joint strength of the joint to be comparable to that of when a joint is formed throughout the entire joined structure, even when an annular joint is formed in the joined structure. Therefore, according to one aspect of the present disclosure, a joined structure is provided that can achieve high efficiency in joining base materials while suppressing deterioration in joint characteristics.

[0010] The width of the main body of the joint may be 1.5 mm or more, which allows for better joint strength of the joining structure.

[0011] The shortest dimension of the joining structure may be 5 mm or more, in which case the joint strength of the joining structure can be set more favorably.

[0012] The first member and the second member may contain different materials. The first member may be a metal or alloy plate having a thickness of 0.2 mm to 5 mm, and the second member may contain resin. Even in these cases, deterioration of the joint properties of the joint due to heat input during the formation of the joining structure (particularly deterioration due to thermal damage to the second member) can be suppressed.

[0013] A manufacturing method for a joined body according to another aspect of the present disclosure includes a step of forming a joining structure that joins a plate-shaped first member and a second member that is overlapped on the first member in the plate thickness direction of the first member, wherein the joining structure has a joint that joins the first member and the second member, and a deformed portion that is provided on at least one of the first member and the second member and overlaps the joint in the plate thickness direction, wherein the shape of the main body of the joint is a ring shape that follows the edge of the joining structure when viewed from the plate thickness direction, the width of the main body of the joint is 1 mm or more and less than half the shortest dimension of the joining structure along a direction perpendicular to the plate thickness direction, and in at least a part of the area surrounded by the joint in the joining structure, the first member and the second member overlap in the plate thickness direction but are not joined.

[0014] According to this manufacturing method, the shape of the main body of the joint provided in the joining structure is annular along the edge of the joining structure when viewed in the plate thickness direction. In at least a portion of the region surrounded by the joint in the joining structure, the first and second members overlap in the plate thickness direction but are not joined. This limits the areas of the first and second members that are heated compared to when a joint is formed throughout the entire joining structure. This reduces the time and joining area required to form the joint in the joining structure, allowing for efficient joint formation. Furthermore, the width of the main body of the joint is 1 mm or more and less than half the shortest dimension of the joining structure along a direction perpendicular to the plate thickness direction. This allows for the joint strength of the joint to be comparable to that of when a joint is formed throughout the entire joining structure, even when an annular joint is formed in the joining structure. Therefore, according to another aspect of the present disclosure, a method for manufacturing a joined body is provided that can achieve high efficiency in joining base materials while suppressing deterioration in joint characteristics.

[0015] In the above process, the joined structure may be formed by friction stir welding or by laser irradiation. In either case, the joined structure can be formed.

[0016] A joining tool according to yet another aspect of the present disclosure is a joining tool for joining a plate-shaped first member and a plate-shaped second member that are overlapped on top of each other, and includes a base having a tip surface, a side extending along the outer peripheral edge of the tip surface, and a base end connected to the side, wherein the tip surface has a ring shape and the width of the tip surface is 1 mm or more, and a space is defined in the base that follows the inner peripheral edge of the tip surface and extends from the tip surface toward the base end in the axial direction of the base.

[0017] According to this welding tool, the tip surface has an annular shape, and the base defines a space that extends along the inner circumferential edge of the tip surface and from the tip surface toward the base end in the axial direction of the base. As a result, when the welding tool is used to join the first and second members, the space exists between the portion of the base that is different from the tip surface and the first or second member. Therefore, when joining the first and second members, only the tip surface can be brought into contact with the first or second member. Additionally, compared to when the tip surface has a flat shape, the portions of the first and second members heated by the welding tool are limited. This reduces the time and joining area required to form the joint structure joining the first and second members, thereby enabling efficient joint formation. Furthermore, the width of the tip surface is 1 mm or greater. As described above, this ensures sufficient joint strength for the annular joint structure formed between the first and second members, allowing the joint structure to be formed with high reliability. Therefore, according to yet another aspect of the present disclosure, it is possible to achieve high efficiency in joining base materials while suppressing deterioration in joint characteristics.

[0018] The width of the tip end surface may be 1.5 mm or more, which ensures good joint strength of the joint structure formed between the first member and the second member.

[0019] The base may have a recess surrounded by the tip surface when viewed from the axial direction and defining a space, and the distance between the tip surface and the bottom surface of the recess may be 0.2 mm or more in the axial direction. In this case, the strength of the base can be ensured while preventing contact between the bottom surface of the recess and the first or second member.

[0020] The bottom surface may be a plane corresponding to the entire area surrounded by the tip surface when viewed from the axial direction. In this case, when the welding tool is used to join the first member and the second member, only the tip surface can be reliably brought into contact with the first member or the second member.

[0021] The shortest dimension of the base along the direction perpendicular to the axial direction may be 5 mm or more, which ensures sufficient joining strength of the joining structure formed between the first member and the second member.

[0022] The welding tool may further include a protruding portion that protrudes from the base end portion in the axial direction, and the diameter of the protruding portion may be smaller than the diameter of the base portion. In this case, energy required to heat the welding tool can be reduced.

[0023] The base may have a cylindrical shape, in which case the energy required to heat the base can be reduced. [Effects of the Invention]

[0024] According to one aspect of the present disclosure, it is possible to provide a joined body that can suppress deterioration of joint characteristics while realizing high efficiency in joining base materials, a method for manufacturing the same, and a joining tool. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1(a) is a schematic plan view showing a bonded body according to an embodiment, FIG. 1(b) is a schematic cross-sectional view taken along line Ib-Ib in FIG. 1(a), and FIG. 1(c) is a schematic cross-sectional view taken along line Ic-Ic in FIG. 1(a). [Figure 2] 2(a) and 2(b) are each a schematic plan view showing a bonded body according to another example of the embodiment. [Figure 3]FIG. 3(a) is a schematic side view showing the welding tool according to the embodiment, and FIG. 3(b) is a schematic bottom view showing the welding tool according to the embodiment. [Figure 4] FIG. 4(a) is a diagram showing the results of a finite element method analysis of stress distribution during a peel test of the bonded body of the first reference example, and FIG. 4(b) is a diagram showing the results of a finite element method analysis of stress distribution during a peel test of the bonded body of the second reference example. [Figure 5] FIG. 5 shows the results of a simulation showing the relationship between the joint strength of the joint structure and the width of the joint. [Figure 6] Fig. 6(a) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 1, and Fig. 6(b) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 1. Fig. 6(c) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 4, and Fig. 6(d) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 4. [Figure 7] Fig. 7(a) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 5, and Fig. 7(b) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 5. Fig. 7(c) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 8, and Fig. 7(d) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 8. [Figure 8] FIG. 8 is a bar graph showing the average values ​​of the cross tensile strengths of Experimental Examples 1 to 8. [Figure 9] FIG. 9(a) is a graph showing the relationship between the area of ​​the bonded structure and the cross tensile strength, and FIG. 9(b) is a graph showing the relationship between the radius of the outer periphery of the annular portion and the cross tensile strength. [Figure 10] Figure 10(a) is an enlarged view of a key portion of the fracture surface of the first member in Experimental Example 9, Figure 10(b) is an enlarged view of a key portion of the fracture surface of the second member in Experimental Example 9, Figure 10(c) is an enlarged view of a key portion of the fracture surface of the first member in Experimental Example 12, and Figure 10(d) is an enlarged view of a key portion of the fracture surface of the second member in Experimental Example 12. [Figure 11] FIG. 11 is a bar graph showing the average values ​​of the tensile shear strength of Experimental Examples 9 to 14. DETAILED DESCRIPTION OF THE INVENTION

[0026] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In the following description, identical elements or elements having the same functions will be designated by the same reference numerals, and redundant explanations will be omitted. In this specification, the term "same" and similar words are not limited to "completely identical." Furthermore, since the drawings are intended to conceptually explain the embodiments, the dimensions and ratios of the depicted components may differ from the actual dimensions.

[0027] (zygote) The bonded structure according to this embodiment will be described below with reference to Figures 1(a) to 1(c) and Figures 2(a) and 2(b). Figure 1(a) is a schematic plan view showing the bonded structure according to this embodiment, Figure 1(b) is a schematic cross-sectional view taken along line Ib-Ib in Figure 1(a), and Figure 1(c) is a schematic cross-sectional view taken along line Ic-Ic in Figure 1(a). Figures 2(a) and 2(b) are each a schematic plan view showing a bonded structure according to another example of this embodiment.

[0028] 1(a) to 1(c), the joined body 1 is a structure including a first member 10, a second member 20 that is overlaid on the first member 10, and a joining structure 30 that joins the first member 10 and the second member 20. The joined body 1 is used, for example, as a part of an automobile, transportation equipment, etc. In this embodiment, a part of the first member 10 and a part of the second member 20 are overlaid on each other, but the present invention is not limited to this.

[0029] The first member 10 and the second member 20 are joined together by the joining structure 30. Therefore, in the joined body 1, the first member 10 and the second member 20 are integrated with each other. The main surface 10a of the first member 10 and the main surface 20a of the second member 20 are in contact with each other. The main surface 10b of the first member 10 and the main surface 20b of the second member 20 each constitute the surface of the joined body 1. In this embodiment, the first member 10 and the second member 20 are plate-shaped and overlap each other in the plate thickness direction of the first member 10 and the second member 20, but this is not limited to this. It is sufficient that one of the first member 10 and the second member 20 is plate-shaped. In this case, the other of the first member 10 and the second member 20 is, for example, a bulk material. The thickness of at least one of the first member 10 and the second member 20 is, for example, 0.2 mm to 5 mm, although this is adjusted appropriately depending on the material. In this embodiment, each of the principal surfaces 10a and 20a is flat, but is not limited to this. At least one of the principal surfaces 10a and 20a may be a roughened surface, may have irregularities, or may have recesses formed thereon. In other words, a portion of the principal surface 10a overlaps the principal surface 20a in the plate thickness direction, but does not necessarily have to be in contact with the principal surface 20a. At least one of the principal surfaces 10a and 20a may have, for example, wavy irregularities.

[0030] The first member 10 and the second member 20 may each be, for example, a member having a metal phase that can be metallurgically joined (metal member), a member that does not contain metal (non-metal member), or a member that cannot be metallurgically joined but contains metal (composite member). The first member 10 and the second member 20 may contain the same material or different materials. That is, the joined body 1 may be a joined body of the same materials or a joined body of dissimilar materials. Examples of metals contained in the metal member or composite member include aluminum, iron, magnesium, copper, titanium, nickel, cobalt, niobium, zirconium, and silver. The metal member or composite member may include an alloy containing the above metals (e.g., aluminum alloy, steel such as carbon steel, nickel-chromium steel, titanium alloy, stainless steel, copper alloy, magnesium alloy, etc.). The non-metal member or composite member may include, for example, a non-metallic material such as a semiconductor, resin, or ceramics. The resin may be a thermoplastic resin such as polyamide, polycarbonate, polyacrylonitrile, polyetheretherketone, polyetheretherimide, or methacrylic resin, or a thermosetting resin such as epoxy resin, phenolic resin, polyester resin, vinylester resin, or polyimide resin. When the nonmetallic member or composite member contains a resin, the nonmetallic member or composite member may be formed from carbon fiber reinforced plastic (CFRP). In this case, the nonmetallic member or composite member may be formed from carbon fiber reinforced plastic (CFRTP) containing thermoplastic. In this embodiment, the first member 10 is a metal member or alloy member containing aluminum, and the second member 20 is a nonmetallic member or composite member containing thermoplastic resin (a plate-shaped member made of CFRTP).

[0031] The joining structure 30 is a portion of the joined body 1 where the first member 10 and the second member 20 are joined together. The joining structure 30 is formed when joining the first member 10 and the second member 20 that is placed on the first member 10. The joining structure 30 is formed, for example, by a metallurgical joining method. Examples of metallurgical joining methods include fusion joining methods such as laser welding and resistance spot welding, friction stir welding such as friction stir spot welding, rotary friction welding, linear friction welding, and solid-state joining methods such as solid-state diffusion welding. Alternatively, a fusion joining method using thermocompression bonding or a solid-state joining method such as forge welding may be employed. When the joining structure 30 is formed by the thermocompression bonding, friction stir welding, or rotary friction welding, for example, a joining tool 40 (see FIGS. 3(a) and 3(b)) described below may be used. To form the joining structure 30, for example, a joining material located between the first member 10 and the second member 20 may be used. The bonding material includes, but is not limited to, one or more of tin, silver, copper, aluminum, nickel, bismuth, indium, palladium, and lead. When the above-mentioned bonding material is used to bond the first member 10 and the second member 20, the bonding method is not limited to the metallurgical bonding method described above, and the first member 10 and the second member 20 may be bonded by, for example, heating using a hot plate or the like, atmospheric heat treatment, or the like.

[0032] In this embodiment, the first member 10 and the second member 20 are joined to each other at a portion of the joining structure 30. In other words, the first member 10 and the second member 20 are not joined over the entire joining structure 30. The shape of the joining structure 30 as viewed in the thickness direction is circular, but is not limited thereto. For example, as shown in FIGS. 2(a) and 2(b), the shape of the joining structure 30 as viewed in the thickness direction may be rectangular. In this case, the shape of the joint 31 is a rectangular ring shape. The shape of the joining structure 30 as viewed in the thickness direction may be elliptical, rod-shaped, polygonal, or the like. The larger the area of ​​the joining structure 30 as viewed in the thickness direction, the higher the joining strength between the first member 10 and the second member 20 tends to be. The longest dimension of the joining structure 30 as viewed in the thickness direction is appropriately adjusted depending on the shape, dimensions, materials, and desired joining strength of the first member 10 and the second member 20. From the viewpoint of the joining strength of the joint structure 30, the shortest dimension of the joint structure 30 along a direction perpendicular to the plate thickness direction is, for example, 5 mm. Therefore, the outer diameter of the joint structure 30 may be 5 mm or more. In one example, the outer diameter of the joint structure 30 is 5 mm or more and 50 mm or less. Note that hereinafter, a view from the plate thickness direction will be simply referred to as a plan view.

[0033] The joining structure 30 has a joint 31 that joins the first member 10 and the second member 20 to each other, and a deformation portion 32 that is provided on at least one of the first member 10 and the second member 20 and overlaps the joint 31 in the plate thickness direction. The joint 31 has a main body joining portion 31a (main body portion) and an auxiliary joining portion 31b. The main body joining portion 31a has a ring shape that follows the edge 30a of the joining structure 30 in a plan view, and is located, for example, between the main surface 10b of the first member 10 and the main surface 20b of the second member 20 in the plate thickness direction. The main body joining portion 31a is a portion that is formed by direct heat input, for example, using a joining tool 40 (see FIGS. 3(a) and 3(b)) described below, a laser, or the like, and overlaps the deformation portion 32 in the plate thickness direction. The width W1 of the main body joint 31a in plan view is 1 mm or more and less than half the shortest dimension of the joint structure 30 in a direction perpendicular to the plate thickness direction. The auxiliary joint 31b is formed by the flow and solidification of the molten second member 20 accompanying the formation of the main body joint 31a, and is joined to the main surface 10a of the first member 10. Furthermore, at least a portion of the auxiliary joint 31b does not overlap the deformed portion 32 in the plate thickness direction. The auxiliary joint 31b expands from the main body joint 31a in a direction perpendicular to the plate thickness direction. The size of the auxiliary joint 31b varies depending on the amount of flow of the molten second member 20. The amount of flow can vary, for example, depending on the insertion depth of a joining tool 40 (see FIGS. 3(a) and 3(b)), which will be described later, the heating time of the first member 10 and the second member 20, and the like. A portion of the auxiliary joint 31b is located inside the main body joint 31a in a plan view, and another portion of the auxiliary joint 31b is located outside the main body joint 31a in a plan view. Each of the portion and the other portion has a ring shape corresponding to the shape of the main body joint 31a, but is not limited to this. In this embodiment, the entire joint 31 in a plan view, i.e., the combined shape of the main body joint 31a and the auxiliary joint 31b, has a substantially ring shape. In addition, the portion of the auxiliary joint 31b is formed in a part of the area surrounded by the main body joint 31a. Therefore, in a plan view, the joint 31 is not formed in a part of the joint structure 30. In other words, in at least a part of the area 33 surrounded by the joint 31 in the joint structure 30, the first member 10 and the second member 20 overlap in the thickness direction but are not joined.In this embodiment, the first member 10 and the second member 20 are in contact but not joined in this portion. Furthermore, since the width W1 of the main body joint 31a is 1 mm or more, the joint strength of the joined structure 30 can be approximately the same as the joint strength when a joint is formed throughout the entire joined structure. From the perspective of the joint strength of the joined structure 30, the width W1 of the main body joint 31a may be 1.5 mm or more. In this case, the joint strength of the joined structure 30 can be substantially the same as the joint strength when a joint is formed throughout the entire joined structure. In this embodiment, the shape of the main body joint 31a is annular in plan view, but is not limited thereto. For example, as shown in FIGS. 2(a) and 2(b), the shape of the main body joint 31a may be rectangular in plan view. Alternatively, the shape of the main body joint 31a may be elliptical in plan view. In this embodiment, the width W1 of the main body joint 31a is constant, but is not limited thereto. In addition, the main body joint 31a does not have to have a ring shape that matches the edge 30a. As long as the main body joint 31a has a ring shape that overlaps the edge 30a, it can be said that the main body joint 31a has a ring shape that follows the edge 30a.

[0034] The deformation portion 32 is formed, for example, by pressing, deforming, softening, melting, or the like, of at least one of the first member 10 and the second member 20 when forming the joining structure 30 (particularly, the main body joint portion 31a of the joint 31). In plan view, the shape of the deformation portion 32 may be a ring shape similar to that of the main body joint portion 31a, or may be a ring shape different from that of the main body joint portion 31a. For example, due to deformation, flow, or the like of at least one of the first member 10 and the second member 20, the shape of the deformation portion 32 in plan view may differ from the shape of the main body joint portion 31a.

[0035] (Joining tool) The welding tool according to this embodiment will be described below with reference to Figures 3(a) and 3(b). Figure 3(a) is a schematic side view showing the welding tool according to this embodiment, and Figure 3(b) is a schematic bottom view showing the welding tool according to this embodiment.

[0036] As shown in FIGS. 3( a) and 3(b), the welding tool 40 is a member for welding a first member 10 and a second member 20 that are superimposed on each other. The welding tool 40, heated by an external device (not shown), is pressed against the first member 10 or the second member 20 to form a welded structure 30. The welded structure 30 can be formed by thermocompression bonding of the first member 10 and the second member 20 using the welding tool 40. The welding tool 40 may rotate when the welding tool 40 is heated and pressed against the first member 10 or the second member 20. In this case, the welded structure 30 can be formed by friction stir spot welding using the welding tool 40. From the viewpoints of heat resistance, wear resistance, and the like, the welding tool 40 can be made of, for example, tool steel, cemented carbide, ceramics, etc. Note that the external device can be, for example, a general-purpose welding robot to which the welding tool 40 can be attached.

[0037] The joining tool 40 has a base 50 having a tip surface 51, a side surface 52, and a base end 53, and a protrusion 60 protruding from the base end 53. The base 50 is a tip portion of the joining tool 40 that heats and presses the first member 10 or the second member 20, and has, for example, a columnar, frustum, or cylindrical shape. In this embodiment, the base 50 has a cylindrical shape and has a recess 54 surrounded by the tip surface 51 as viewed from the axial direction L of the base 50. When the joining tool 40 is used to form the joined structure 30, the size of the joined structure 30 is determined according to the dimensions of the base 50 as viewed from the axial direction L, although this depends on the heat and pressure time. From the viewpoint of the joining strength of the joined structure 30, the shortest dimension of the base 50 along a direction perpendicular to the axial direction L is 5 mm or more. In one example, the outer diameter A of the base 50 is 5 mm or more and 50 mm or less. The dimension of the base portion 50 along the axial direction L is not particularly limited, but from the viewpoint of durability and the like, it may be, for example, 10 mm or more.

[0038] The tip surface 51 is a portion that comes into contact with the first member 10 or the second member 20 when the joining tool 40 is used, and has a ring shape. The width W2 of the tip surface 51 is 1 mm or more, 1.5 mm or more, or 2 mm or more, and is less than half the outer diameter of the base portion 50. In the present embodiment, the shape of the tip surface 51 is a circular ring, but is not limited to this. The shape of the tip surface 51 may be an elliptical ring or a polygonal ring. In the present embodiment, the width W2 of the tip surface 51 is constant, but is not limited to this. From the standpoint of durability, etc., the side surface 52 extends along the outer circumferential edge 51a of the tip surface 51, but is not limited to this. The side surface 52 may be located outward from the outer circumferential edge 51a. In this case, the portion of the side surface 52 located closest to the tip end portion 53 is located closer to the base end portion 53 than the tip surface 51 in the axial direction L. The base end portion 53 is the portion of the base portion 50 closest to the protruding portion 60 in the axial direction L and is connected to the side surface 52. The outer diameter of the base end portion 53 narrows as it approaches the protruding portion 60 in the axial direction L, but is not limited to this. From the viewpoint of durability of the joining tool 40, the dimension of the base end portion 53 along the axial direction L is, for example, 1 mm or more and 5 mm or less.

[0039] The recess 54 is a portion recessed along the axial direction L and defined along the inner peripheral edge 51b of the tip surface 51 as viewed from the axial direction L. By providing the recess 54 in the welding tool 40, a space is defined in the base portion 50, which extends along the inner peripheral edge 51b of the tip surface 51 and from the tip surface 51 toward the base end 53 in the axial direction L. Due to the presence of this space, when the first member 10 and the second member 20 are joined using the welding tool 40, the first member 10 or the second member 20 can only come into contact with the tip surface 51 of the welding tool 40. The recess 54 has a bottom surface 54a that is surrounded by the tip surface 51 as viewed from the axial direction L and defines the space. The bottom surface 54a is the portion of the recess 54 that is located closest to the base end 53 in the axial direction L and is a plane that corresponds to the entire area surrounded by the tip surface 51 as viewed from the axial direction L. That is, only a flat surface corresponding to the bottom surface 54a is provided inside the tip surface 51 at the tip of the base 50.

[0040] The distance D between the tip surface 51 and the bottom surface 54a in the axial direction L is, for example, equal to or greater than the recessed amount of the recess 54 (i.e., equal to or greater than the insertion amount of the joining tool 40 into the first member 10). In one example, when joining the first member 10 and the second member 20 using the joining tool 40, only the tip surface 51 of the joining tool 40 is brought into contact with the first member 10 or the second member 20. In this embodiment, since the second member 20 contains a thermoplastic resin, the insertion amount of the joining tool 40 into the first member 10 is approximately 0.2 mm to 0.3 mm. Therefore, the distance D may be equal to or greater than 0.2 mm, or equal to or greater than 0.3 mm. In cases where both the first member 10 and the second member 20 are metal members, the insertion amount of the joining tool 40 into the first member 10 may exceed 0.3 mm. Therefore, from the viewpoint of usability for various types of joining, the distance D may be 0.5 mm or more, 0.8 mm or more, 1 mm or more, 1.2 mm or more, 1.5 mm or more, or 1.6 mm or more.

[0041] The protrusion 60 is, for example, a portion of the welding tool 40 that is attached to an external device, and has, for example, a columnar or cylindrical shape. In the axial direction of the base 50, the protrusion 60 is located downstream of the base 50. In a direction perpendicular to the axial direction L, the diameter of the protrusion 60 is smaller than the diameter of the base 50, but is not limited to this. From the standpoint of durability, for example, the outer diameter of the protrusion 60 may be 50% or more of the outer diameter of the base 50. The outer diameter of the protrusion 60 may be the same as or larger than the outer diameter of the base 50. When the outer diameter of the protrusion 60 is the same as the outer diameter of the base 50, the base end 53 may not be provided. When the outer diameter of the protrusion 60 is larger than the outer diameter of the base 50, the base end 53 widens as it approaches the protrusion 60 in the axial direction L. When the base 50 and the protrusion 60 each have a cylindrical shape, the inner diameter of the base 50 may be the same as the inner diameter of the protrusion 60 .

[0042] An example of a method for manufacturing a bonded structure 1 using a welding tool 40 is described below. In this welding method, first, the first member 10 and the second member 20 are overlapped. At this time, the overlapped first member 10 and the second member 20 are fixed on a stage or the like. Next, a heated welding tool 40 is pressed against the overlapped first member 10 or the second member 20 along the plate thickness direction. To prevent damage to the first member 10 and the second member 20, the load applied to the welding tool 40 is, for example, 0.5 kN to 1.0 kN, and the pressing time of the welding tool 40 is, for example, 0.1 seconds to 3.0 seconds, although this depends on the materials of the first member 10 and the second member 20. When the welding tool 40 presses the first member 10 or the second member 20, the welding tool 40 may rotate in the circumferential direction. In this case, friction stir spot welding is performed using the welding tool 40. The rotation speed of the welding tool 40 is, for example, 500 rpm to 5000 rpm, 1000 rpm to 4000 rpm, or 1500 rpm to 3500 rpm. By pressing and rotating the welding tool 40, the welding tool 40 is inserted into the main surface 10b of the first member 10, and the first member 10 and the second member 20 are heated. This melts the portion of the main surface 20a of the second member 20 that overlaps with the welding tool 40 and its surroundings, forming a main welding portion 31a and an auxiliary welding portion 31b. This completes the formation of a welding structure 30 (see FIG. 1 ) that joins the first member 10 and the second member 20. Furthermore, a deformed portion 32 is formed in at least one of the first member 10 and the second member 20 due to the pressing force of the welding tool 40.

[0043] The effects of the bonded structure according to this embodiment will be described below with reference to FIGS. 4(a) and 4(b). FIG. 4(a) is a diagram showing the results of a finite element method analysis of stress distribution during a peel test of the bonded structure of the first reference example, and FIG. 4(b) is a diagram showing the results of a finite element method analysis of stress distribution during a peel test of the bonded structure of the second reference example. Here, the first reference example is a bonded structure of an aluminum plate and a carbon fiber reinforced resin plate in which an annular joint is formed along the outer periphery of the bonded structure, as in this embodiment. The second reference example is a bonded structure of an aluminum plate and a carbon fiber reinforced resin plate in which a joint is formed throughout the entire bonded structure. In each of the first and second reference examples, a cross tension test was performed as the peel test for the bonded structure, and the radius r of the bonded structure was set to 15 mm. In the first reference example, the width of the annular joint was set to 2 mm.

[0044] As shown in Figures 4(a) and (b), in both Reference Example 1 and Reference Example 2, the region requiring the highest stress during peeling of the bonded structure is the outer periphery of the bonded structure. The stress in this region is approximately 500 MPa. Furthermore, in both Reference Example 1 and Reference Example 2, the stress required during peeling of the bonded structure decreases as the distance from the outer periphery approaches the center of the bonded structure. In both Reference Example 1 and Reference Example 2, the maximum stress at a location approximately 1 mm from the outer periphery to the center of the bonded structure was approximately 100 MPa. Additionally, in both Reference Example 1 and Reference Example 2, the stress at a location approximately 2 mm from the outer periphery to the center of the bonded structure was approximately 0 MPa. Furthermore, in Reference Example 2, the stress required at the center of the bonded structure during peeling of the bonded structure was significantly smaller than the stress required at the outer periphery of the bonded structure. Therefore, in the second reference example, if the outer peripheral edge of the joint structure were to peel off, it would be understood that the aluminum plate and the carbon fiber reinforced resin plate would easily peel off.

[0045] Figure 5 shows simulation results showing the relationship between the joint strength of a joint structure and the width of the joint. Figure 5 shows simulation results showing the relationship between the width of a circular joint formed in a joint between an aluminum plate and a carbon fiber reinforced resin plate and cross tensile tests and tensile shear tests. In Figure 5, the horizontal axis represents the width of the main joint portion of the joint, and the vertical axis represents the cross tensile strength or tensile shear strength. Graph 61 shows the simulation results of a cross tensile test when the radius r of the joint structure is 7.5 mm. Graph 62 shows the simulation results of a tensile shear test when the radius r of the joint structure is 7.5 mm. Graph 63 shows the simulation results of a cross tensile test when the radius r of the joint structure is 15 mm. Graph 64 shows the simulation results of a tensile shear test when the radius r of the joint structure is 15 mm.

[0046] As shown in Figure 5, when the width of the main body joint of the joint is 2 mm or more, the cross tensile test results and tensile shear test results are almost constant regardless of the size of the joint, and are almost identical to the results when the joint is formed throughout the entire joint. Furthermore, when the width of the main body joint of the joint is 1 mm or more, the cross tensile test results and tensile shear test results are each 80% or more of the maximum value regardless of the size of the joint. From these results, it can be said that regardless of the size of the joint, when the width of the main body joint of the joint along the outer edge of the joint is 1 mm or more, the cross tensile strength and tensile shear strength are similar to those when the joint is formed throughout the entire joint.

[0047] In the joined body 1 manufactured by the manufacturing method according to the present embodiment based on the above findings, the shape of the main body joint portion 31a of the joint 31 included in the joined structure 30 is a ring shape along the edge 30a of the joined structure 30 in a plan view. In at least a portion of the region 33 surrounded by the joint 31 in the joined structure 30, the first member 10 and the second member 20 overlap in the thickness direction but are not joined. This limits the portions of the first member 10 and the second member 20 that are heated compared to when a joint is formed throughout the entire joined structure. This reduces the time and joining area required to form the joint 31 included in the joined structure 30. This reduces the thermal energy and time required to form the joint 31, allowing for efficient formation of the joint 31. Additionally, unnecessary damage to the first member 10 and the second member 20 during the formation of the joint 31 can be prevented, thereby suppressing deterioration of the joint characteristics. Furthermore, the width W1 of the main body joining portion 31a of the joint 31 is 1 mm or more and is less than half the shortest dimension of the joining structure 30 along the direction perpendicular to the plate thickness direction. As a result, even when an annular joint 31 is formed in the joining structure 30, the joint strength of the joint 31 can be made to the same extent as when a joint is formed over the entire joining structure.

[0048] In addition, according to the welding tool 40 of this embodiment, the tip surface 51 has an annular shape, and a space is defined in the base portion 50, which runs along the inner peripheral edge 51b of the tip surface 51 and extends from the tip surface 51 toward the base end portion 53 in the axial direction L. As a result, when the welding tool 40 is used to join the first member 10 and the second member 20, the space exists between a portion of the base portion 50 different from the tip surface 51 and the first member 10 or the second member 20. Therefore, when the first member 10 and the second member 20 are joined, only the tip surface 51 can be brought into contact with the first member 10 or the second member 20. Therefore, by joining the first member 10 and the second member 20 using the welding tool 40, the above-mentioned effects can be achieved.

[0049] Furthermore, when performing friction stir welding or the like using the welding tool 40, the annular joint 31 can be formed even if a high load is not applied to the first member 10. Therefore, unintended deformation of the first member 10 and the second member 20 can be suppressed, and damage to the tip surface 51 of the welding tool 40 can also be suppressed.

[0050] The joined body, the manufacturing method thereof, and the joining tool according to the present disclosure are as described in the following [1] to

[15] , and have been described in detail based on the above embodiments.

[0051] [1] A plate-shaped first member; a second member that is overlapped on the first member in a plate thickness direction of the first member; a joining structure that joins the first member and the second member; Equipped with The joining structure includes a joint that joins the first member and the second member, and a deformation portion that is provided in at least one of the first member and the second member and overlaps the joint in the plate thickness direction, The shape of the main body of the joint is a ring shape along the edge of the joining structure when viewed from the plate thickness direction, The width of the main body of the joint is 1 mm or more and is less than half the shortest dimension of the joint structure along a direction perpendicular to the plate thickness direction, In the joining structure, the first member and the second member are in contact with each other but are not joined in at least a part of the area surrounded by the joint. zygote. [2] The joined body according to [1], wherein the width of the main body of the joint is 1.5 mm or more. [3] The bonded structure according to [1] or [2], wherein the shortest dimension of the bonded structure is 5 mm or more. [4] The bonded body according to any one of [1] to [3], wherein the first member and the second member contain different materials. [5] The first member is a metal plate or an alloy plate having a thickness of 0.2 mm or more and 5 mm or less, The bonded body according to [4], wherein the second member includes a resin. [6] A method for manufacturing a joined body, comprising a step of forming a joining structure that joins a plate-like first member and a second member that is overlapped on the first member in a plate thickness direction of the first member, The joining structure includes a joint that joins the first member and the second member, and a deformation portion that is provided in at least one of the first member and the second member and overlaps the joint in the plate thickness direction, The shape of the main body of the joint is a ring shape along the edge of the joining structure when viewed from the plate thickness direction, The width of the main body of the joint is 1 mm or more and is less than half the shortest dimension of the joint structure along a direction perpendicular to the plate thickness direction, In the joining structure, the first member and the second member are in contact with each other but are not joined in at least a part of the area surrounded by the joint. A method for manufacturing a bonded body. [7] The method for manufacturing a joined body according to [6], wherein the joining structure is formed by friction stir welding. [8] The method for producing a bonded body according to [6], wherein the bonded structure is formed by laser irradiation in the step. [9] A joining tool for joining a plate-shaped first member and a plate-shaped second member that are overlapped with each other, a base portion having a tip surface, a side surface extending along an outer periphery of the tip surface, and a base end portion connected to the side surface; The tip surface has an annular shape, The width of the tip surface is 1 mm or more, A space is defined in the base portion, the space extending along an inner peripheral edge of the tip surface and from the tip surface toward the base end portion in the axial direction of the base portion. Joining tool.

[10] The joining tool according to [9], wherein the width of the tip surface is 1.5 mm or more.

[11] The base portion has a recess that is surrounded by the tip end surface when viewed from the axial direction and defines the space, The welding tool according to [9] or

[10] , wherein the distance between the tip surface and the bottom surface of the recess in the axial direction is 0.2 mm or more.

[12] The joining tool according to

[11] , wherein the bottom surface is a plane corresponding to the entire area surrounded by the tip surface when viewed from the axial direction.

[13] The joining tool according to any one of [9] to

[12] , wherein the shortest dimension of the base along a direction perpendicular to the axial direction is 5 mm or more.

[14] Further provided is a protruding portion protruding from the base end portion in the axial direction, The welding tool according to any one of [9] to

[13] , wherein the diameter of the protruding portion is smaller than the diameter of the base portion.

[15] The joining tool according to any one of [9] to

[14] , wherein the base portion has a cylindrical shape.

[0052] However, one aspect of the present disclosure is not limited to the above embodiment and the above [1] to

[15] . One aspect of the present disclosure can be further modified within the scope of its gist. For example, in the above embodiment, the second member includes a thermoplastic resin, but this is not limited thereto. For example, each of the first member and the second member may be a metal member or may not include a resin. In these cases, an auxiliary joint portion may not be formed when forming the joint. [Example]

[0053] The present disclosure will be explained in more detail by the following examples, but the present disclosure is not limited to these examples.

[0054] (Experimental Example 1) A rectangular plate-shaped first member (long side: 150 mm, short side: 50 mm, thickness: 1.6 mm) made of aluminum alloy (A6061-T6) and a rectangular plate-shaped second member (long side: 150 mm, short side: 50 mm, thickness: 3 mm) made of CFRTP (polyplastic resin pellets, model number: PA6-CF40-01(L9)) were prepared. Next, the first member and the second member were overlapped so that the long sides of the first member and the long sides of the second member were perpendicular to each other. The first member and the second member were overlapped so that the centers of the first member and the second member were aligned. Next, a welding tool (made of SKH51, tip surface width: 1 mm, tip diameter: 25 mm, recess depth: 1.6 mm) shown in Figures 3(a) and (b) was pressed against the overlapping portion of the first member and the second member. The welding tool was pressed against the first member with a load of 1 kN while rotating in the circumferential direction. Therefore, the first member and the second member were joined by the friction stir welding method using the above-mentioned joining tool. The contact time between the first member and the joining tool (i.e., the joining time between the first member and the second member) was 0.1 seconds. As a result, a sample for a cross tension test was prepared in which the first member and the second member were joined together by an annular joint.

[0055] (Experimental Example 2) A sample for the cross tension test was prepared in the same manner as in Experimental Example 1, except that the joining time between the first member and the second member was 0.5 seconds.

[0056] (Experimental Example 3) A sample for the cross tension test was prepared in the same manner as in Experimental Example 1, except that the joining time between the first member and the second member was 1 second.

[0057] (Experimental Example 4) A sample for the cross tension test was prepared in the same manner as in Experimental Example 1, except that the joining time between the first member and the second member was 3 seconds.

[0058] (Experimental Example 5) A sample for the cross tension test was prepared in the same manner as in Experimental Example 1, except that the width of the tip face of the joining tool was 2 mm.

[0059] (Experimental Example 6) A sample for a cross tension test was prepared in the same manner as in Experimental Example 5, except that the joining time between the first member and the second member was 0.5 seconds.

[0060] (Experimental Example 7) A sample for the cross tension test was prepared in the same manner as in Experimental Example 5, except that the joining time between the first member and the second member was 1 second.

[0061] (Experimental Example 8) A sample for the cross tension test was prepared in the same manner as in Experimental Example 5, except that the joining time between the first member and the second member was 3 seconds.

[0062] Three samples were prepared for each of Experimental Examples 1 to 8. Next, the cross tensile strength of each sample was measured according to the method described in JIS Z 3137:1999. Then, the average value of the cross tensile strength was calculated for each of Experimental Examples 1 to 8. Furthermore, for each of Experimental Examples 1 to 8, fracture surface observation was carried out after the cross tensile test. Then, for each of Experimental Examples 1 to 8, the area of ​​the joint (i.e., the bonding area between the first member and the second member) viewed from the overlapping direction of the first member and the second member was measured.

[0063] FIG. 6(a) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 1, and FIG. 6(b) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 1. FIG. 6(c) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 4, and FIG. 6(d) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 4. FIG. 7(a) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 5, and FIG. 7(b) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 5. FIG. 7(c) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 8, and FIG. 7(d) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 8. As shown in FIGS. 6(a) to 6(d) and 7(a) to 7(d), a joint that was an annular weld mark (annular portion) was confirmed in all of Experimental Examples 1 to 8. That is, it was confirmed that the joint had a ring shape in all of Experimental Examples 1 to 8. Furthermore, in Experimental Example 8, a main joint portion and an auxiliary joint portion surrounding it were confirmed.

[0064] Figure 8 is a bar graph showing the average cross tensile strengths of Experimental Examples 1 to 8. In Figure 8, the horizontal axis represents the joining time, and the vertical axis represents the cross tensile strength. Therefore, at 0.1 seconds on the horizontal axis, the left bar represents the average cross tensile strength of Experimental Example 1, and the right bar represents the average cross tensile strength of Experimental Example 5. As shown in Figure 8, there was no significant difference in cross tensile strength between Experimental Examples 1 and 5, Experimental Examples 2 and 6, Experimental Examples 3 and 7, and Experimental Examples 4 and 8. In particular, the cross tensile strengths of Experimental Examples 1 to 3 and 5 to 7 were almost unchanged. This suggests that forming an annular joint can shorten the joining time. In addition, although the cross tensile strength of Experimental Example 4 was higher than that of the other Experimental Examples, no tendency for the cross tensile strength to increase with increasing joining time was observed. Therefore, it is inferred that the cross tensile strength between the first and second members tends to be determined by the outer diameter of the joint rather than the joint area.

[0065] In addition, the average cross tensile strengths of Experimental Examples 1 to 8 were compared with the cross tensile strength of samples for cross tensile tests prepared using the same method as Experimental Example 1, except that a comparative joining tool without a recess (i.e., a conventionally used joining tool with a flush tip surface) was used. When the comparative joining tool was used, the average cross tensile strength of the samples in which the first and second components were joined for 5 seconds was similar to the average cross tensile strength of Experimental Example 5. Note that friction stir welding using the comparative joining tool typically requires a joining time of several seconds or more. These results confirm that good joint strength can be obtained in a significantly shorter joining time than when using a conventional friction stir welding tool.

[0066] To verify the validity of the above-mentioned trends, a comparison was made with a sample (comparison sample) for a cross-tensile test in which the first and second members were welded using a different welding tool from those used in Experimental Examples 1 to 8. This comparative sample was fabricated using the same method as Experimental Examples 1 to 8, except that the surface of the welding tool that contacted the first member was flat. Therefore, in the comparison sample, a joint was formed over the entire welded structure. Below, we show the relationship between the area of ​​the welded structure and the cross-tensile strength, as well as the relationship between the outer diameter of the annular portion (joint) and the cross-tensile strength. The area of ​​the welded structure corresponds to the sum of the welded area of ​​the joint and the area enclosed by the joint (the area where the first and second members overlap but are not joined). Figure 9(a) is a graph showing the relationship between the area of ​​the welded structure and the cross-tensile strength. In Figure 9(a), the horizontal axis represents the area of ​​the welded structure, and the vertical axis represents the cross-tensile strength. Figure 9(b) is a graph showing the relationship between the radius of the outer periphery of the annular portion and the cross-tensile strength. In Figure 9(b), the horizontal axis represents the radius of the outer periphery of the annular portion, and the vertical axis represents the cross tensile strength. In Figures 9(a) and 9(b), the open circles represent the measurement results for Experimental Examples 1 to 8, and the closed circles represent the measurement results for the comparative sample. As shown in Figure 9(a), when the area of ​​the joint structure is approximately the same, the joint strength when the joint is annular and formed along the outer periphery of the joint structure is not significantly different from the joint strength when the joint is formed over the entire joint structure. Therefore, it can be seen that the correlation between the outer diameter of the joint and the cross tensile strength is significantly higher than the correlation between the joint area of ​​the joint in the joint structure and the cross tensile strength. From these results, it can be inferred that the cross tensile strength between the first and second members tends to be determined by the outer diameter of the joint rather than the joint area.

[0067] (Experimental Example 9) A square plate-shaped first member (long side: 100 mm, short side: 30 mm, thickness: 1.6 mm) made of aluminum alloy (A6061-T6) and a square plate-shaped second member (long side: 100 mm, short side: 30 mm, thickness: 3 mm) made of CFRTP (polyplastic resin pellets, model number: PA6-CF40-01(L9)) were prepared. Next, the first member and the second member were overlapped with each other. At this time, the first member and the second member were overlapped with each other so that a portion of the long side (30 mm) of the first member and the long side of the second member were aligned and overlapped. Next, the welding tool used in Experimental Example 1 above was pressed against the overlapping portion of the first member and the second member. At this time, the welding tool was pressed against the first member with a load of 500 N while rotating in the circumferential direction. Thus, the first member and the second member were joined by a friction stir welding method using the welding tool. The contact time between the first member and the joining tool (i.e., the joining time between the first member and the second member) was 0.5 seconds. As a result, a sample for the tensile shear test was created in which the first member and the second member were joined to each other by an annular joint formed along the outer periphery of the joining structure.

[0068] (Experimental Example 10) A sample for the tensile shear test was prepared in the same manner as in Experimental Example 9, except that the joining time between the first member and the second member was 1 second.

[0069] (Experimental Example 11) A sample for the tensile shear test was prepared in the same manner as in Experimental Example 9, except that the joining time between the first member and the second member was 3 seconds.

[0070] (Experimental Example 12) A sample for the tensile shear test was prepared in the same manner as in Experimental Example 9, except that the joining tool used in Experimental Example 5 was used.

[0071] (Experimental Example 13) A sample for the tensile shear test was prepared in the same manner as in Experimental Example 12, except that the joining time between the first member and the second member was 1 second.

[0072] (Experimental Example 14) A sample for the tensile shear test was prepared in the same manner as in Experimental Example 12, except that the joining time between the first member and the second member was 3 seconds.

[0073] Three samples were prepared for each of Experimental Examples 9 to 14. The tensile shear strength of each sample was then measured according to the method described in JIS Z 3137:1999. The average tensile shear strength was calculated for each of Experimental Examples 9 to 16. Furthermore, for each of Experimental Examples 9 to 16, fracture surfaces were observed after the tensile shear test.

[0074] FIG. 10(a) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 9, and FIG. 10(b) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 9. FIG. 10(c) is an enlarged view of a main portion of the fracture surface of the first member in Experimental Example 12, and FIG. 10(d) is an enlarged view of a main portion of the fracture surface of the second member in Experimental Example 12. As shown in FIGS. 10(a) to 10(d), it was confirmed that the joint shape was annular in both Experimental Examples 9 and 12. However, in both Experimental Examples 9 and 12, deformation was also observed around the annular portion formed in the second member. As described above, the first and second members in Experimental Examples 9 to 14 were smaller than the first and second members in Experimental Examples 1 to 8. Therefore, the heat dissipation performance of Experimental Examples 9 to 14 was inferior to that of Experimental Examples 1 to 8. For this reason, it is presumed that the deformation of the second member in Experimental Examples 9 and 12 was larger than the deformation of the second member in Experimental Examples 4 and 5.

[0075] FIG. 11 is a bar graph showing the average tensile shear strength values ​​for Experimental Examples 9 to 14. In FIG. 11, the horizontal axis represents joining time, and the vertical axis represents tensile shear strength. Therefore, at "0.5 seconds" on the horizontal axis in FIG. 11, the left bar represents the average tensile shear strength value for Experimental Example 9, and the right bar represents the average tensile shear strength value for Experimental Example 12. As shown in FIG. 11, no significant difference in tensile shear strength was observed between Experimental Examples 9 and 12, Experimental Examples 10 and 13, and Experimental Examples 11 and 14. While there was a tendency for tensile shear strength to increase in Experimental Examples 9 to 11, this tendency was not observed in Experimental Examples 12 to 14. All of Experimental Examples 9 to 14 exhibited sufficient tensile shear strength. This suggests that shortening joining time is possible by forming an annular joint. [Explanation of symbols]

[0076] 1...joint, 10...first member, 10a...main surface, 10b...main surface, 20...second member, 20a...main surface, 20b...main surface, 30...joining structure, 30a...edge, 31...joint, 32...deformed portion, 33...area, 40...joining tool, 50...base, 51...tip surface, 51a...outer peripheral edge, 51b...inner peripheral edge, 52...side, 53...base end, 54...recess, 54a...bottom surface, 60...protrusion, A...outer diameter, D...spacing, W1, W2...width

Claims

1. a plate-shaped first member; a second member overlapped on the first member in a plate thickness direction of the first member; a joining structure that joins the first member and the second member; Equipped with The joining structure includes a joint that joins the first member and the second member, and a deformation portion that is provided in at least one of the first member and the second member and overlaps the joint in the plate thickness direction, The shape of the main body of the joint is a ring shape along the edge of the joining structure when viewed from the plate thickness direction, The width of the main body of the joint is 1 mm or more and is less than half the shortest dimension of the joint structure along a direction perpendicular to the plate thickness direction, In the joining structure, in at least a part of a region surrounded by the joint, the first member and the second member overlap in the plate thickness direction but are not joined. zygote.

2. 2. The joined body of claim 1, wherein the width of the body of the joint is 1.5 mm or greater.

3. The joined body according to claim 1 or 2, wherein the shortest dimension of the joined structure is 5 mm or more.

4. The bonded structure according to claim 1 , wherein the first member and the second member contain different materials.

5. the first member is a metal plate or an alloy plate having a thickness of 0.2 mm or more and 5 mm or less, The joined body according to claim 4 , wherein the second member includes a resin.

6. A method for manufacturing a joined body, the method comprising: forming a joining structure that joins a plate-like first member and a second member that is overlapped on the first member in a plate thickness direction of the first member; The joining structure includes a joint that joins the first member and the second member, and a deformation portion that is provided in at least one of the first member and the second member and overlaps the joint in the plate thickness direction, The shape of the main body of the joint is a ring shape along the edge of the joining structure when viewed from the plate thickness direction, The width of the main body of the joint is 1 mm or more and is less than half the shortest dimension of the joint structure along a direction perpendicular to the plate thickness direction, In the joining structure, in at least a part of a region surrounded by the joint, the first member and the second member overlap in the plate thickness direction but are not joined. A method for manufacturing a bonded body.

7. The method for manufacturing a joined body according to claim 6 , wherein the joining structure is formed by friction stir welding in the step.

8. The method for manufacturing a bonded body according to claim 6 , wherein the bonded structure is formed by laser irradiation in the step.

9. A joining tool for joining a plate-shaped first member and a plate-shaped second member that are overlapped with each other, a base portion having a tip surface, a side surface extending along an outer periphery of the tip surface, and a base end portion connected to the side surface; The tip surface has an annular shape, The width of the tip surface is 1 mm or more, A space is defined in the base portion, the space extending along an inner peripheral edge of the tip surface and from the tip surface toward the base end portion in the axial direction of the base portion. Joining tool.

10. The joining tool according to claim 9 , wherein the width of the tip surface is 1.5 mm or more.

11. the base portion has a recess that is surrounded by the tip end surface when viewed from the axial direction and defines the space, The welding tool according to claim 9 or 10, wherein a distance between the tip surface and a bottom surface of the recess in the axial direction is 0.2 mm or more.

12. The welding tool according to claim 11 , wherein the bottom surface is a plane corresponding to the entire area surrounded by the tip surface when viewed from the axial direction.

13. The joining tool according to claim 9 or 10, wherein the shortest dimension of the base along a direction perpendicular to the axial direction is 5 mm or more.

14. Further provided is a protrusion protruding from the base end portion in the axial direction, The joining tool according to claim 9 or 10, wherein the diameter of the protrusion is smaller than the diameter of the base.

15. The joining tool according to claim 9 or 10, wherein the base portion has a cylindrical shape.

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