Bonding method, bonded body, and bonding device

Abstract

An overlapping portion (30) of a first member (31) and a second member (32) is joined using a tool (1) and a rivet (5) for friction stir spot welding. The overlapping portion (30) is formed by disposing the first member (31) on the side into which the tool (1) is press fitted first, and disposing the second member (32) on the side into which the tool (1) is press fitted last. A friction stirred portion (4) is formed in the overlapping portion (30) by press fitting the tool (1) into the overlapping portion (30) and performing friction stirring. The rivet (5) is press fitted into the friction stirred portion (4) from the first member (31) side.

Description

[Technical field]

[0001] The present disclosure relates to a joining method for joining overlapping portions of two or more members by using friction stirring and a fastener, a joined body using the same, and a joining device used in the joining method. [Background technology]

[0002] Metallic members, resin members, thermoplastic resin members mixed with fiber reinforcement, etc. are used as components of structures such as aircraft, railroad cars, and automobiles. In manufacturing such structures, it may be necessary to join two or more members by overlapping them. Known joining methods include joining using fasteners such as rivets and joining using friction stir welding.

[0003] An example of a document disclosing a joining technique for fiber-reinforced thermoplastic resin members is Patent Document 1. Patent Document 1 discloses a method of joining the resin members using a self-piercing rivet by using a special lower mold for heat-treating the resin members.

[0004] However, even with the above-mentioned joining methods, there are cases where sufficient joining strength and joint quality cannot be obtained depending on the material of the parts to be joined. For example, when joining resin parts in which continuous fibers are impregnated with thermoplastic resin, the method of simply driving a self-piercing rivet may not deform the rivet enough to exert an anchor effect. In addition, even if a joint is formed by adopting a method of forcibly deforming the self-piercing rivet by using a special lower die, delamination may occur, resulting in a decrease in the strength of the base material and the appearance quality. Furthermore, a joint that relies only on friction stir welding may not be able to obtain sufficient peel strength. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5333584 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present disclosure is to provide a joining method capable of joining overlapping portions of two or more components more firmly than ever before, a joined body using the same, and a joining device used in the joining method. [Means for solving the problem]

[0007] A joining method according to one aspect of the present disclosure is a joining method using a friction stir welding tool and a fastener to join an overlapping portion formed including a first member on the tool side and a second member arranged below the first member, characterized in that the tool is pressed into the overlapping portion to perform friction stirring, thereby forming a friction stir portion in the overlapping portion, and the fastener is pressed into the friction stir portion from the first member side.

[0008] According to this joining method, a joint having excellent strength can be obtained by using both friction stir and the fastening body. That is, a friction stir portion into which the fastening body is later pressed is formed at the overlapping portion. In this friction stir portion, the constituent materials of the overlapping portion are kneaded by friction stirring and the constituent materials are softened. The fastening body can be easily pressed into such a friction stir portion. Therefore, the fastening effect of the fastening body can be easily exerted. For example, if the constituent materials are not softened sufficiently or if a reinforcing material or filler is present, it is difficult to deform the fastening body as intended. This difficulty is eliminated in the friction stir portion, so the fastening body can easily deform as it should by pressing. Therefore, a high-strength joint can be obtained.

[0009] A joint according to another aspect of the present disclosure is a joint of an overlapping portion formed to include a first member and a second member, the joint comprising: an overlapping portion where the first member is positioned at one end side in an overlapping direction and the second member is positioned at the other end side in the overlapping direction; a friction stir portion provided in the overlapping portion; and a fastener pressed into the friction stir portion.

[0010] With this welded body, a joining force is applied to the overlapping portion by the friction stir portion formed in the overlapping portion and the fastening body pressed into the friction stir portion. In other words, the first and second members can be firmly engaged with each other by the fastening effect of the fastening body, without relying solely on friction stir welding. Therefore, a welded body with excellent joining strength can be constructed.

[0011] A joining device according to yet another aspect of the present disclosure is a joining device for joining an overlapping portion formed including a first member and a second member, and includes a cylindrical pin member capable of moving back and forth in an axial direction, a cylindrical shoulder member positioned to cover the outer periphery of the pin member, rotating about the same axis as the pin member and capable of moving back and forth in the axial direction, and a fastener that is loaded into a storage space created by the rising of the pin member and is pressed into a friction stir portion formed in the overlapping portion by the pin member.

[0012] By using this joining device, the process from friction stirring at the overlapping portion to pressing in the fastener can be carried out smoothly on an assembly line. Effect of the Invention

[0013] According to the present disclosure, overlapping portions of two or more members can be firmly joined by using a combination of friction stir welding and a fastener. [Brief description of the drawings]

[0014] [Figure 1A] FIG. 1A is a schematic diagram showing the configuration of a double-action friction stir spot welding apparatus capable of carrying out the joining method according to the present disclosure. [Figure 1B] FIG. 1B is a cross-sectional view showing an example of loading a rivet into a tool. [Diagram 2] FIG. 2 is a diagram showing the configurations of a first member and a second member to be joined by the joining method. [Diagram 3] FIG. 3 is a diagram showing a process chart of the bonding method according to the first embodiment. [Figure 4]FIG. 4 is a cross-sectional view showing a state in which a preparation step of the bonding method is carried out. [Diagram 5] FIG. 5 is a cross-sectional view showing a state in which the overlapping portion forming step is carried out. [Figure 6A] FIG. 6A is a cross-sectional view showing a state in which a friction stir process is carried out. [Figure 6B] FIG. 6B is a cross-sectional view showing a state in which the friction stir process is carried out. [Figure 7A] FIG. 7A is a cross-sectional view showing a rivet driving process. [Figure 7B] FIG. 7B is a cross-sectional view showing a state in which a step of forming an interlock portion is carried out. [Figure 8A] FIG. 8A is a cross-sectional view of a bonded body formed by the bonding method. [Figure 8B] FIG. 8B is a cross-sectional view of a bonded body formed by the bonding method. [Figure 8C] FIG. 8C is a cross-sectional view of a bonded body formed by the bonding method. [Figure 9] Steps (A) to (D) in FIG. 9 are cross-sectional views showing the implementation status of the bonding method according to the second embodiment. [Figure 10] Steps (A) to (C) in FIG. 10 are cross-sectional views showing the implementation of the bonding method according to the second embodiment. [Figure 11A] FIG. 11A is a cross-sectional view showing a state in which the bonding method according to the third embodiment is carried out. [Figure 11B] FIG. 11B is a cross-sectional view showing a state in which the bonding method according to the third embodiment is carried out. [Figure 12A] FIG. 12A is a vertical cross-sectional view of a modified rivet. [Figure 12B] FIG. 12B is a cross-sectional view showing an implementation state of the bonding method according to the fourth embodiment. [Figure 12C] FIG. 12C is a cross-sectional view showing a state in which the bonding method according to the fourth embodiment is carried out. [Figure 13A] FIG. 13A is a cross-sectional view showing a state in which the bonding method according to the fifth embodiment is carried out. [Figure 13B]FIG. 13B is a cross-sectional view showing an implementation state of the bonding method according to the fifth embodiment. [Figure 13C] FIG. 13C is a cross-sectional view showing a state in which the bonding method according to the fifth embodiment is carried out. [Figure 14A] FIG. 14A is a cross-sectional view showing an implementation state of the bonding method according to the fifth embodiment. [Figure 14B] FIG. 14B is a cross-sectional view of a bonded body obtained according to the fifth embodiment. [Figure 15] FIG. 15 is a cross-sectional view showing a bonded body according to another modified example. [Figure 16] FIG. 16 is a cross-sectional view showing a bonded body according to another modified example. [Figure 17] 17(A) and (B) are perspective views of a cylindrical rivet and a pin member used in the joining method according to the sixth embodiment, and FIG. 17(C) is a cross-sectional view showing the joining method according to the sixth embodiment in practice. [Figure 18] 18(A) and (B) are perspective views of a cylindrical rivet and a pin member used in the joining method according to the seventh embodiment, and FIG. 18(C) is a cross-sectional view showing the preparation state of the joining method according to the seventh embodiment. [Figure 19] Steps (A) to (D) in FIG. 19 are cross-sectional views showing the implementation of the bonding method according to the seventh embodiment. [Figure 20A] FIG. 20A is a perspective view of a threaded rivet used in the joining method according to the eighth embodiment. [Figure 20B] FIG. 20B is a cross-sectional view showing a state in which the bonding method according to the eighth embodiment is carried out. [Figure 21] FIG. 21 is a cross-sectional view showing a bonded body according to another modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. The joining method according to the present disclosure can be applied to the manufacture of various joined bodies obtained by overlapping and spot-joining two or more structural members, such as plates, frames, exterior materials, or pillar-shaped materials, made of metal, thermoplastic resin, thermoplastic composite material, etc. The thermoplastic composite material is, for example, a composite material containing a fiber reinforcement such as carbon fiber. The manufactured joined body becomes, for example, a component of a structure such as an aircraft, a railway vehicle, or an automobile.

[0016] [Configuration of double-action friction stir spot welding device] First, with reference to Fig. 1A, a configuration example of a double-action friction stir spot welding apparatus M capable of executing the joining method according to the present disclosure will be described. The friction stir spot welding apparatus M includes a double-action friction stir spot welding tool 1, a tool drive unit 2 that drives the tool 1 to rotate and elevate, and a controller C that controls the operation of the tool drive unit 2. Note that although Fig. 1 shows directional indications of "up" and "down", this is for the convenience of explanation and is not intended to limit the actual direction in which the tool 1 is used.

[0017] The tool 1 is supported by a tool fixing part (not shown). The tool fixing part can be, for example, the tip of an articulated robot. A backup member 15 is arranged facing the lower end surface of the tool 1. At least two members to be joined are arranged between the tool 1 and the backup member 15. FIG. 1A shows an example in which an overlapping part 30, in which a part of a first member 31 made of a flat plate and a part of a second member 32 also made of a flat plate overlap each other in the vertical direction, is arranged between the tool 1 and the backup member 15. Such an overlapping part 30 is joined by a joining method that uses both friction stirring and a rivet 5 (fastening body), thereby forming a joined body 3 of the first member 31 and the second member 32. The overlapping part 30 may be one in which one or more members are further interposed between the first member 31 and the second member 32.

[0018] The tool 1 includes a pin member 11, a shoulder member 12, a clamp member 13, and a spring 14. The pin member 11 is a member formed in a cylindrical shape, and is arranged so that its axis extends in the vertical direction. The pin member 11 can rotate about the axis as a rotation axis R, and can move up and down in the vertical direction along the rotation axis R, that is, can move forward and backward. When the tool 1 is used, the rotation axis R is aligned with the point joining position W at the overlapping portion 30.

[0019] The shoulder member 12 is positioned so as to cover the outer periphery of the pin member 11. The shoulder member 12 is a cylindrical member having a hollow portion into which the pin member 11 is inserted. The axis of the shoulder member 12 is coaxial with the rotation axis R, which is the axis of the pin member 11. The shoulder member 12 can rotate around the same rotation axis R as the pin member 11, and can move up and down along the rotation axis R, that is, move forward and backward. The shoulder member 12 and the pin member 11 inserted in the hollow portion can move relatively in the direction of the rotation axis R while rotating together around the axis of the rotation axis R. In other words, the pin member 11 and the shoulder member 12 can not only simultaneously move up and down along the rotation axis R, but also independently move such that one moves down and the other moves up.

[0020] The clamp member 13 is a cylindrical member having a hollow portion into which the shoulder member 12 is inserted. The axis of the clamp member 13 is also coaxial with the rotation axis R. The clamp member 13 does not rotate about its axis, but can move up and down along the rotation axis R, that is, can move forward and backward. The clamp member 13 serves to surround the outer periphery of the pin member 11 or the shoulder member 12 when they perform friction stirring. The enclosure with the clamp member 13 prevents the friction stir material from scattering, and makes it possible to smoothly finish the friction stir spot welded portion.

[0021] The spring 14 is attached to the upper end side of the clamp member 13 and biases the clamp member 13 in a direction (downward) toward the overlapping portion 30. The clamp member 13 is attached to the tool fixing portion via the spring 14. The backup member 15 has a flat surface that abuts against the underside of the overlapping portion 30 to be joined. The backup member 15 is a backing member that supports the overlapping portion 30 when the pin member 11 or the shoulder member 12 is pressed into the overlapping portion 30. The clamp member 13 biased by the spring 14 presses the overlapping portion 30 against the backup member 15.

[0022] The tool driving unit 2 includes a rotation driving unit 21, a pin driving unit 22, a shoulder driving unit 23, and a clamp driving unit 24. The rotation driving unit 21 includes a motor, a driving gear, etc., and drives the pin member 11 and the shoulder member 12 to rotate around the rotation axis R. The pin driving unit 22 is a mechanism for moving the pin member 11 forward and backward along the rotation axis R. The pin driving unit 22 drives the pin member 11 so as to press the pin member 11 into the overlapping portion 30 and to retract the pin member 11 from the overlapping portion 30. The shoulder driving unit 23 is a mechanism for moving the shoulder member 12 forward and backward along the rotation axis R, and causes the shoulder member 12 to press into the overlapping portion 30 and to retract the shoulder member 12 from the overlapping portion 30. The clamp driving unit 24 is a mechanism for moving the clamp member 13 forward and backward along the rotation axis R. The clamp driving unit 24 moves the clamp member 13 toward the overlapping portion 30 and presses the overlapping portion 30 against the backup member 15. At this time, the biasing force of the spring 14 acts.

[0023] The controller C is composed of a microcomputer or the like, and executes a predetermined control program to control the operation of each part of the tool driving unit 2. Specifically, the controller C controls the rotation driving unit 21 to cause the pin member 11 and the shoulder member 12 to perform a required rotation operation. The controller C also controls the pin driving unit 22, the shoulder driving unit 23, and the clamp driving unit 24 to cause the pin member 11, the shoulder member 12, and the clamp member 13 to perform a required forward and backward movement operation.

[0024] The above-mentioned double-action friction stir spot welding tool 1 can be used in a pin-first process and a shoulder-first process. In the friction stir step of the pin-first process, the pin member 11 of the tool 1 is pressed into the overlapping portion 30 first to perform friction stir welding, while the shoulder member 12 is raised, i.e., retreated. In the subsequent backfilling step, the pin member 11 is raised and retreated, while the shoulder member 12 is lowered. On the other hand, in the friction stir step of the shoulder-first process, the shoulder member 12 of the tool 1 is pressed into the overlapping portion 30 first to perform friction stir welding, while the pin member 11 is raised, i.e., retreated. In the subsequent backfilling step, the shoulder member 12 is raised and retreated, while the pin member 11 is lowered.

[0025] In this embodiment, since joining is performed using both friction stir welding and the rivet 5, it is desirable to provide the friction stir spot welding apparatus M with a mechanism that can load the rivet 5 into the tool 1 in advance. Fig. 1B is a cross-sectional view showing an example of loading the rivet 5 into the tool 1. A supply opening 121 for supplying the rivet 5 into the hollow portion of the shoulder member 12 is provided near the upper end of the shoulder member 12. The friction stir spot welding apparatus M is provided with a supply mechanism (not shown) that continuously feeds the rivets 5 to the supply opening 121.

[0026] The pin driver 22 raises the lower end 11T of the pin member 11 above the height position of the supply opening 121. The shoulder driver 23 raises the shoulder member 12 to a position where the supply opening 121 is higher than the upper end 132 of the clamp member 13. After the rivet 5 is supplied from the supply opening 121 into the shoulder member 12, the pin member 11 is lowered. As shown diagrammatically near the lower end of the tool 1 in FIG. 1B, the rivet 5 is pressed down by the lower end 11T of the pin member 11 and driven into the overlap portion 30.

[0027] [Parts to be joined] 2 is a diagram showing the configuration of an overlapping portion 30 to be joined by the joining method of this embodiment. A first member 31 and a second member 32 are overlapped in the vertical direction to form the overlapping portion 30. The first member 31 has a thickness t1 in the overlapping direction. The second member 32 has a thickness t2 (t1=t2) that is the same as the thickness t1. t1 and t2 may be different thicknesses as long as they allow friction stir welding.

[0028] As described above, in the present disclosure, there is no particular limitation on the members to be joined, and members made of metal, thermoplastic resin, thermoplastic composite material, etc. can be selected. Of these, it is desirable that both the first member 31 and the second member 32 are molded bodies made of fiber-reinforced thermoplastic resin. Examples of molded bodies made of fiber-reinforced thermoplastic resin include molded bodies in which short fibers or long fibers as fiber reinforcement are mixed with thermoplastic resin, and molded bodies in which continuous fibers are aligned in a predetermined direction or woven fabric of continuous fibers is impregnated with thermoplastic resin.

[0029] Examples of thermoplastic resins that can be used as the constituent material of the first member 31 and the second member 32 include polypropylene (PP), polyethylene (PE), polyamide (PA), polystyrene (PS), polyaryletherketone (PEAK), polyacetal (POM), polycarbonate (PC), polyethylene terephthalate (PET), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), ABS resin, thermoplastic epoxy resin, etc. Examples of fiber reinforcing materials that can be used include carbon fiber, glass fiber, ceramic fiber, metal fiber, and organic fiber.

[0030] The first member 31 and the second member 32 may each be composed of a single fiber-reinforced thermoplastic resin molded body, but are preferably composed of a stack of multiple thin sheets. Fig. 2 shows an example in which molded bodies formed by laminating multiple layers of sheets in which a continuous fiber arrangement is impregnated with a thermoplastic resin, such as prepregs, are used as the first member 31 and the second member 32.

[0031] FIG. 2 shows a part of the sheet stack 33 constituting the first member 31. The sheet stack 33 includes a first sheet layer 33A, a second sheet layer 33B, and a third sheet layer 33C each made of a sheet impregnated with a thermoplastic resin in an array of continuous fibers. The first sheet layer 33A is a sheet having a thickness of about 0.1 mm to 0.5 mm in which a large number of continuous fibers 34 are arranged in a predetermined array direction and the array is impregnated with a thermoplastic resin to be integrated. The second sheet layer 33B and the third sheet layer 33C are also sheets similar to those described above, but the array directions of the continuous fibers 34 are mutually different. In this way, for example, by stacking three types of sheets in which the array directions of the continuous fibers 34 are different from each other in three axial directions in multiple layers, the first member 31 has pseudo-isotropy. The second member 32 is also a plate made of a multi-layer laminate of sheets similar to the first member 31.

[0032] As the continuous fibers 34, for example, carbon fibers, glass fibers, ceramic fibers, metal fibers, or organic fibers can be used. In Fig. 2, a sheet in which the continuous fibers 34 are arranged in one direction is illustrated, but a fabric-type sheet in which a woven fabric is formed using continuous fibers as warp and weft and then impregnated with a thermoplastic resin may also be used. Also, instead of the continuous fibers 34, a sheet or plate in which long fibers or short fibers having a length of about 2 mm to 20 mm are mixed with a thermoplastic resin may also be used.

[0033] The first member 31 and the second member 32 may be members made of the same material as in the above example, but may be members made of different materials. For example, one of the first member 31 and the second member 32 may be a molded body of a thermoplastic resin, and the other may be a molded body of a fiber-reinforced thermoplastic resin. In this case, it is desirable to use a molded body of a fiber-reinforced thermoplastic resin or a molded body in which continuous fibers are impregnated with a thermoplastic resin as the second member 32 located on the side where the pin member 11 or the shoulder member 12 of the tool 1 is finally pressed in. Alternatively, one of the first member 31 and the second member 32 may be a molded body of a specific thermoplastic resin or metal, and the other may be a molded body of a thermoplastic resin or metal different from the above.

[0034] As the rivet 5 illustrated in FIG. 1A as an example of the fastener, for example, a self-piercing rivet can be used. When the rivet 5 is driven into the overlapping portion 30, a part of the rivet 5 is deformed, and an engagement force is generated to integrate the first member 31 and the second member 32. As will be described in detail later, in this embodiment, the rivet 5 is driven into the region of the overlapping portion 30 that has been friction-stirred by the tool 1, and a part of the rivet penetrates into the base material portion that has not been friction-stirred, thereby generating the engagement force. There is no particular limitation on the material of the rivet 5, and a rivet made of a metal such as titanium, a thermoplastic resin, or a thermoplastic composite material can be used. Instead of a self-piercing rivet, various joining members, part of which can be deformed, may be used as the fastener.

[0035] [First embodiment of joining method] 3 is a diagram showing a process chart of the bonding method according to the first embodiment. The bonding method of the present embodiment is a method for bonding an overlapping portion 30 including a first member 31 and a second member 32, and includes the following steps S1 to S6. Step S1: A preparation step in which the rivet 5 to be driven is loaded into the tool 1 in advance. Step S2: An overlapping portion forming step of forming the overlapping portion 30 including the first member 31 and the second member 32. Step S3: A friction stir step in which the shoulder member 12 of the tool 1 is pressed into the overlapping portion 30 to perform friction stirring. Step S4: A riveting step in which the pin member 11 of the tool 1 presses the rivet 5 into the friction stir portion from the first member 31 side. Step S5: A step of deforming a part of the driven rivet 5 to form an interlocking portion. Step S6: Optionally, a step of crushing the rivet head.

[0036] Each of the above steps S1 to S6 will be specifically described below. FIG. 4 is a cross-sectional view showing the preparation step of the above step S1. FIG. 4 shows a longitudinal section of a rivet 5. The rivet 5 is made of a titanium alloy such as Ti-6Al-4V, and includes a head 51 and a shank 52 connected to the lower part of the head 51. The head 51 is made of a solid body and has a top surface 51H that receives a press-in force from the tool 1. The shank 52 includes an upper end 521 that is integrally connected to the head 51, and a lower end 522 that becomes a tip when driving into the overlapping portion 30. The shank 52 has a cylindrical hollow region 523 therein in order to provide it with easy deformation. The lower end 522 is also an opening edge of the hollow region 523, and has an annular edge shape.

[0037] On the tool 1 side, an operation for loading the rivet 5 is performed. Specifically, the controller C (FIG. 1) operates the pin driver 22 to raise the pin member 11, and creates an accommodation space H for the rivet 5 in the hollow portion of the shoulder member 12. That is, the lower end portion 11T of the pin member 11 is relatively raised by at least the height of the rivet 5 with respect to the lower end portion 12T of the shoulder member 12, and the accommodation space H is provided near the lower end opening of the shoulder member 12. Of course, the rivet 5 is selected to have an outer diameter smaller than the inner diameter of the hollow portion of the shoulder member 12. Thereafter, the rivet 5 is loaded into the accommodation space H. Note that the above preparation steps are premised on the application of the shoulder-first process to perform friction stir welding.

[0038] The tool 1 in the preparation step of step S1 described above takes the form of a joining device for implementing the joining method of this embodiment. This joining device is equipped with a pin member 11, a shoulder member 12, and a rivet 5 (fastened body) that is loaded into an accommodation space H created in the shoulder member 12 by the rise of the pin member and is pressed into the friction stir portion by the pin member 11.

[0039] 5 is a cross-sectional view showing the implementation status of the step S2 of forming the overlapping portion 30. In step S2, the first member 31 and the second member 32 are arranged so that the overlapping portion 30 is formed in a state where at least a portion of the first member 31 and the second member 32 overlap with each other in abutting relationship. In this embodiment, the overlapping portion 30 is illustrated in which a portion of the plate-shaped first member 31 is an upper member and a portion of the plate-shaped second member 32 is a lower member, and the two are overlapped vertically.

[0040] The tool 1 loaded with the rivet 5 is placed above the overlapping portion 30. That is, the first member 31 is placed on the side where the tool 1 is first pressed in, and the second member 32 is placed on the side where the tool 1 is last pressed in, thereby forming the overlapping portion 30. That is, the first member 31 is placed on the tool 1 side, and the second member 32 is placed below the first member. The bottom surface of the overlapping portion 30 is supported by the backup member 15. Note that, as will be illustrated in FIG. 15 later, the overlapping portion 30 may be formed by interposing one or more other members between the first member 31 and the second member 32.

[0041] Referring also to FIG. 2, the overlapping portion 30 has a mating surface BD where the joining surface 31A (lower surface) of the first member 31 and the joining surface 32A (upper surface) of the second member 32 are in direct contact with each other. In such a two-layer overlapping portion 30, friction stirring is performed by the tool 1 with the required spot joining position W as the axis, and the rivet 5 is pressed in. Therefore, the lower end surface of the tool 1 is abutted against the upper surface of the first member 31 with the rotation axis R (FIG. 1) of the tool 1 aligned with the spot joining position W. FIG. 5 shows a state where the lower end 12T of the shoulder member 12 and the lower end 13T of the clamp member 13 are in contact with the upper surface 30U of the overlapping portion 30. The clamp member 13 presses the overlapping portion 30 against the backup member 15 with the biasing force of the spring 14.

[0042] 6A and 6B are cross-sectional views showing the implementation status of the friction stir welding process in step S3. FIG. 6A shows a state in which the shoulder-first process is applied to the tool 1, and the shoulder member 12 is being pressed into the overlapping portion 30. When the above-mentioned alignment of the tool 1 with respect to the overlapping portion 30 is completed, the controller C controls the rotation drive unit 21 and the shoulder drive unit 23 to lower the shoulder member 12 while rotating it at high speed around the axis, and starts pressing the shoulder member 12 into the overlapping portion 30. Meanwhile, the controller C controls the pin drive unit 22 to retract the pin member 11 upward so that the resin material overflowing from the above-mentioned press-in can escape. The clamp member 13 is immobile. As a result, friction stirring is performed with the point joining position W as the center. Since the pin member 11 has already been moved upward to the extent that the accommodation space H is formed, the above-mentioned retraction operation of the pin member 11 may be omitted.

[0043] The press-in depth d of the shoulder member 12, which corresponds to the press-in depth of the tool, i.e., the amount of descent of the lower end portion 12T from the upper surface 30U, is set according to the thickness t1 of the first member 31 and the thickness t2 of the second member 32. The press-in depth d is set to a depth that penetrates at least the first member 31 and reaches a part of the second member 32. Note that, as will be described later with reference to FIG. 11A, the press-in depth d may be set to less than the thickness t1 of the first member 31.

[0044] When the shoulder member 12, rotating at high speed, is pressed into the overlapping portion 30, the material of the overlapping portion 30 is frictionally stirred in the pressed-in area of ​​the shoulder member 12. The material that overflows from the overlapping portion 30 due to the pressing of the shoulder member 12 is released into the hollow portion within the shoulder member 12. The frictional stirring softens the material in the pressed-in area, and a frictional stirring portion 4 is formed in the overlapping portion 30. In this frictional stirring portion 4, the continuous fibers 34 are broken and in a pulverized state. This makes it easier to drive and deform the rivet 5 in the following process.

[0045] 6B is a diagram showing the backfilling step of the overflowing material in the friction stir process of step S3. In the backfilling step, the shoulder drive unit 23 raises the shoulder member 12. If the pin member 11 has been raised, it is lowered. This action causes the softened material to flow into the region that was occupied by the vicinity of the lower end 12T of the shoulder member 12 in the friction stir section 4. Therefore, the material that has overflowed from the overlapping portion 30 is also backfilled in the press-fit region.

[0046] By the above step S3, a friction stir part 4 having a cylindrical side surface 41 with a depth d and a disk-shaped bottom surface 42 is formed in the overlapping part 30. While the material is softened in this friction stir part 4, the original hardness of the first member 31 and the second member 32 is maintained in the base material portion around the friction stir part 4, and the reinforcing structure by the continuous fibers 34 is also maintained.

[0047] 7A is a cross-sectional view showing the implementation status of the rivet driving step of step S4. Step S4 is a step of press-fitting the rivet 5 into the friction stir part 4 from the first member 31 side. In this embodiment, the friction stir spot welding tool 1 is used as the tool for press-fitting the rivet 5. Therefore, the joining method of this embodiment can be carried out without separately preparing a tool for driving the rivet 5.

[0048] Specifically, in the riveting process, the pin driver 22 lowers the pin member 11 to apply a pressure force to the head 51, and presses the rivet 5 into the overlapping portion 30. The rivet 5 is pre-loaded in the accommodation space H so that the top surface 51H of the head 51 faces the lower end 11T of the pin member 11. Therefore, when the pin member 11 lowers, the rivet 5 also lowers and enters the inside of the friction stir part 4 from the side of the lower end 522. It is desirable to perform the riveting process before the material of the friction stir part 4 hardens.

[0049] 7B is a cross-sectional view showing the implementation status of the interlock portion forming step S5. In step S5, after the rivet 5 reaches the second member 32, the rivet 5 is deformed to cause a part of the rivet 5 to enter the base material portion around the friction stir portion 4 in the second member 32, thereby forming the interlock portion 53. In this embodiment, the cylindrical shaft portion 52 is deformed into a bell shape with an expanded lower end portion 522, and the expanded lower end portion 522 is pressed into the base material portion, thereby forming the interlock portion 53.

[0050] As the pin member 11 continues to press the rivet 5 down from the state shown in Fig. 7A, the lower end 522 of the rivet 5 eventually reaches the bottom surface 42 of the friction stir section 4. The area below the bottom surface 42 is the base material and has not been softened. In addition, the overlapping section 30 is supported at a position directly below the bottom surface 42 by the backup member 15. Furthermore, near the lower end 522 of the shank 52, the inner diameter of the hollow region 523 gradually increases, and a tapered process is applied so that the lower end 522 becomes sharp.

[0051] Therefore, when the pin member 11 continues to press the rivet 5 after reaching the bottom surface 42, the shank 52 is deformed into a bell shape as shown in FIG. 7B. That is, the lower end 522 not only passes the bottom surface 42 and is pressed into the base material portion below the friction stir portion 4, but also expands in the radial direction and passes the side circumferential surface 41 and is pressed into the base material portion on the side of the friction stir portion 4. Of these, the portion that passes the side circumferential surface 41 and is pressed into the base material portion becomes the interlock portion 53 that exerts an anchor effect in the up-down direction, which is the peeling direction between the first member 31 and the second member 32. The deformation of the shank 52 of the rivet 5 may occur before reaching the second member 32. For example, the deformation may be such that the shank 52 gradually starts expanding and deforming in the area of ​​the first member 31 after being pressed into the friction stir portion 4, and further expands and deforms after reaching the bottom surface 42.

[0052] Step S6, which is performed as necessary, is a step of crushing head 51 of rivet 5. In step S6, a downward pressing force is further applied to head 51 from the state of FIG. 7B. At the completion of step S5, head 51 is in a state in which it protrudes upward from upper surface 30U of overlapping portion 30. The radial size of head 51 is also in a state in which it is smaller than upper end portion 521 of shaft portion 52. The pressing force is applied to such head 51, and it is deformed so as to expand in diameter to a size that engages with the upper surface of friction stirring portion 4 or a size that engages with upper surface 30U of overlapping portion 30 (first member 31).

[0053] As the tool used to crush head 51 in step S6, tool 1 can be used as is. In this case, pin member 11 is further lowered from the state shown in Fig. 7B, and shoulder member 12 is raised to ensure a deformation margin for head 51. Alternatively, another press tool capable of crushing head 51 may be used.

[0054] According to the joining method of the first embodiment described above, the overlapping portion 30 can be joined with excellent joining strength by using the rivet 5 in combination with friction stirring by the tool 1. That is, the friction stirring portion 4 into which the rivet 5 will be pressed in later is formed in the overlapping portion 30. In this friction stirring portion 4, the constituent materials of the first member 31 and the second member 32 are kneaded by friction stirring and the constituent materials are softened.

[0055] In such a friction stir part 4, factors that inhibit the deformation of the rivet 5 are alleviated. For example, if the constituent materials are not softened sufficiently or if a reinforcing material or filler is present, it becomes difficult to deform the rivet 5 as intended. Since this difficulty is eliminated in the friction stir part 4, the rivet 5 is more likely to deform as intended by press-fitting, and the lower end 522 of the shank 52 of the rivet 5 can be smoothly inserted into the base material portion of the second member 32. Therefore, the interlock part 53 is reliably formed, and a high-strength joined body 3 can be obtained.

[0056] In particular, in this embodiment, as shown in FIG. 2, the first member 31 and the second member 32 are made of a sheet stack 33 in which thermoplastic resin sheets containing continuous fibers 34 as reinforcing fibers are stacked in multiple layers. When such members are joined by press-fitting a rivet 5, the continuous fibers 34 may become entangled and hinder the deformation of the rivet 5, and an interlock portion 53 in which the rivet 5 exerts an anchor effect on the overlapping portion 30 may not be formed. However, according to the above joining method, the rivet 5 is driven into the friction stir portion 4 in which the continuous fibers 34 are broken by friction stirring and the thermoplastic resin is softened. Therefore, the rivet 5 exerts its original deformation within the friction stir portion 4, and the lower end portion 522 can be easily inserted into the base material portion around the friction stir portion 4. Therefore, an interlock portion 53 exerting an anchor effect can be formed.

[0057] Moreover, the tool 1 for friction stir spot welding is used as is to press the rivet 5 into the friction stir portion 4. Therefore, there is no need to separately prepare a dedicated tool for driving the rivet 5. Furthermore, with the rivet 5 loaded in advance into the tool 1, friction stirring is performed by the shoulder member 12, and then the rivet 5 is pressed in by the pin member 11. Therefore, the process from friction stirring to pressing in the rivet 5 can be carried out smoothly on an assembly line.

[0058] [Conjugate structure] Fig. 8A is a cross-sectional view showing a bonded body 3 of a first member 31 and a second member 32 produced by the bonding method of the present embodiment. The bonded body 3 shown here corresponds to the state after completion of step S5 shown in Fig. 7B, that is, the state before step S6 is performed.

[0059] The joint 3 includes an overlapping portion 30, a friction stir portion 4, a rivet 5, and an interlock portion 53. The overlapping portion 30 is formed so that the first member 31 is disposed on the upper side, i.e., on one end side in the overlapping direction, and the second member 32 is disposed on the lower side, i.e., on the other end side in the overlapping direction. The friction stir portion 4 is provided in the overlapping portion 30, and is formed so as to penetrate the first member 31 in the vertical direction and reach a part of the second member 32. The rivet 5 is driven so as to be embedded in the friction stir portion 4. The portion that actually enters the friction stir portion 4 is the shaft portion 52 of the rivet 5. As described above, the shaft portion 52 has a bell-shaped shape in which the inner diameter gradually increases from the upper end portion 521 to the lower end portion 522.

[0060] The interlock portion 53 is a deformed portion near the lower end portion 522, which is the lower end region of the shaft portion 52, and protrudes radially outward from the side peripheral surface 41 of the friction stirring portion 4 of the second member 32 and penetrates into the base material portion around the side peripheral surface 41. When viewed in the up-down direction, the interlock portion 53 penetrates into the base material portion below the bottom surface 42. The hollow region 523 of the shaft portion 52 is filled with the friction stirred material.

[0061] According to the joint 3 having the above structure, first, a joining force is applied to the overlapping portion 30 by the friction stir portion 4. That is, the friction stir portion 4 penetrates the first member 31 and reaches a depth of about the upper half of the second member 32, and contributes as a joining element between the first member 31 and the second member 32. Furthermore, a joining force is applied to the overlapping portion 30 by the interlock portion 53 of the rivet 5. The interlock portion 53 is in a mode in which it penetrates from the friction stir portion 4 into the base material portion of the second member 32 present on the side of the side peripheral surface 41. Therefore, the friction stir portion 4 into which the rivet 5 is driven and the base material portion can be firmly engaged by the anchor effect exerted by the interlock portion 53, without relying only on friction stir welding. Therefore, the joint 3 of this embodiment has excellent joining strength.

[0062] 8B is a cross-sectional view showing the joint 3 constructed through the rivet head crushing step in step S6 described above. Head 51, to which a press-in force is applied in the driving step in step S4, is crushed and deformed into a rolled, approximately circular plate shape. This head 51 has a flange 54 that engages with the upper surface of friction stir part 4. Head 51 originally has a smaller diameter than shank 52, but is deformed to a larger diameter than shank 52 by the crushing step in step S6. This portion that extends radially outward from shank 52 is flange 54. The lower surface of flange 54 abuts against the upper surface of friction stir part 4.

[0063] According to the joined body 3 having such a flange 54, the friction stir parts 4 are sandwiched between the interlock part 53 and the flange 54. That is, a structure is realized in which the interlock part 53, which exerts a strong anchor effect by being pressed into the base material part of the second member 32, serves as a holding base point and the flange 54 engages the upper surface of the friction stir parts 4. Therefore, the fixation of the friction stir parts 4 to the overlapping part 30 is improved, and a joined body 3 with excellent stability can be obtained.

[0064] FIG. 8C is a cross-sectional view showing the joint 3 produced through the crushing step of step S6. The head 51 shown here is rolled to a larger diameter than that shown in FIG. 8B. The flange 54A of the head 51 has a size that exceeds the friction stir portion 4 and engages with the upper surface of the first member 31 at the periphery of the friction stir portion 4. With the joint 3 having such a flange 54A, the friction stir portion 4 is sandwiched between the interlock portion 53 that has entered the base material portion of the second member 32 and the flange 54A that engages with the upper surface of the base material portion of the first member 31. Therefore, the fixation of the friction stir portion 4 to the overlapping portion 30 is further improved, and a joint 3 with excellent stability can be obtained.

[0065] [Second embodiment of joining method] 9 and 10 are cross-sectional views sequentially showing the implementation status of the joining method according to the second embodiment. The difference from the first embodiment is that step S1 in Fig. 3, which is a preparation step of loading the rivet 5 to be driven into the tool 1 in advance, is not executed. This has the advantage of increasing the degree of freedom in the friction stir operation using the tool 1 and the operation of pressing in the rivet 5.

[0066] Step (A) in FIG. 9 shows the implementation status of the process of forming the overlapping portion 30. The overlapping portion 30 is formed by overlapping the first member 31 and the second member 32 in the vertical direction with the first member 31 and the second member 32 in contact with each other. The tool 1 is disposed on the upper surface 30U side of the overlapping portion 30. The first member 31 is disposed on the side where the tool 1 is first pressed in, and the second member 32 is disposed on the side where the tool 1 is last pressed in. The lower surface of the overlapping portion 30 is supported by the backup member 15. The lower end portions 12T and 13T, which are the lower end surfaces of the tool 1, are in contact with the upper surface 30U of the overlapping portion 30. The clamp member 13 presses the overlapping portion 30 against the backup member 15 with the biasing force of the spring 14 shown in FIG. 1A.

[0067] Step (B) in Fig. 9 shows a state in which friction stir welding is being performed on the overlapping portion 30 by the shoulder-first process. The shoulder member 12 is pressed into the overlapping portion 30 to perform friction stir welding. Meanwhile, the pin member 11 is retracted upward to allow material overflowing from the overlapping portion 30 to escape. The pressing depth of the lower end portion 12T of the shoulder member 12 is set to a depth that penetrates the first member 31 and reaches approximately the middle of the second member 32 in the thickness direction.

[0068] This friction stir process may be performed by a pin-first process. Step (C) in Fig. 9 shows a state in which friction stir is applied to the overlapping portion 30 by the pin-first process. The pin member 11 is pressed into the overlapping portion 30 to perform friction stir welding. Meanwhile, the shoulder member 12 is retracted upward to allow the material overflowing from the overlapping portion 30 to escape. The pressing depth of the lower end portion 11T of the pin member 11 is set to a depth that similarly penetrates the first member 31 and reaches approximately the middle of the second member 32 in the thickness direction.

[0069] Step (D) in Fig. 9 shows a state in which the backfilling step in the friction stir process is performed following the press-fitting of the shoulder member 12 in step (B). The lower end 12T of the shoulder member 12 pressed into the overlapping portion 30 and the lower end 11T of the pin member 11 retracted upward are each returned to the height position of the upper surface 30U. As a result, the friction stir portion 4 having a side peripheral surface 41 and a bottom surface 42 is formed in the overlapping portion 30. When the pin-first process in step (C) is applied, the pin member 11 is raised and the shoulder member 12 is lowered in the backfilling step.

[0070] Step (A) in Fig. 10 shows a step of setting the rivet 5 in the tool 1. Both the pin member 11 and the shoulder member 12 of the tool 1 are raised by the height of the rivet 5. The rivet 5 is accommodated in the cylindrical space inside the clamp member 13 created by this. In other words, the rivet 5 is disposed below the pin member 11, or between the lower part of the pin member 11 and the shoulder member 12 and the upper surface of the friction stir part 4.

[0071] Step (B) in Fig. 10 shows a state in which the step of driving the rivet 5 and the step of forming the interlock portion 53 are being performed. Both the pin member 11 and the shoulder member 12 are lowered, and the lower ends 11T, 12T press down on the top surface 51H of the rivet 5. The shank 52 of the rivet 5 enters the friction stir portion 4, and the interlock portion 53 penetrates into the base material portion of the second member 32 that exists around the friction stir portion 4.

[0072] Step (B) in Fig. 10 can be substituted by step (C) in Fig. 10. Step (C) in Fig. 10 shows a state in which only the shoulder member 12 is lowered to press down the rivet 5. Although not shown, only the pin member 11 may be lowered to press down the rivet 5. Furthermore, in the driving step, instead of using the tool 1, another press tool may be used. Note that it is desirable to perform the step of driving the rivet 5 and the step of forming the interlock portion 53 after the friction stir portion 4 is formed and before the friction stir portion 4 solidifies.

[0073] [Third embodiment of joining method] 11A and 11B are cross-sectional views sequentially showing the implementation of the joining method according to the third embodiment. In the above first and second embodiments, an example was shown in which the friction stir portion 4 is formed at a press-in depth d that penetrates the first member 31 and reaches a part of the second member 32. As long as the rivet 5 reaches the second member 32 and forms the interlock portion 53, the friction stir portion 4 does not necessarily have to reach the second member 32. In the third embodiment, an example is shown in which a friction stir portion 4A is formed within the thickness range of the first member 31 in the friction stir step of step S3 in FIG. 3.

[0074] As shown in FIG. 11A, a friction stir portion 4A is formed at a press-in depth d1 in the overlapping portion 30 between the first member 31 and the second member 32. The press-in depth d1 is slightly smaller than the thickness of the first member 31, and the friction stir portion 4A is formed only in the region of the first member 31. In other words, the side peripheral surface 41A and the bottom surface 42A of the friction stir portion 4A are within the thickness range of the first member 31. However, the bottom surface 42A is located close to the upper surface of the second member 32, and the base material portion of the second member 32 is present around the friction stir portion 4A. FIG. 11A shows a state in which a rivet 5 is pressed into such a friction stir portion 4A by lowering the pin member 11 of the tool 1.

[0075] FIG. 11B shows a state where the interlock portion forming step of step S5 is completed. As the rivet 5 is pressed into the friction stir portion 4A from the state of FIG. 11A, the lower end 522 of the shank 52 of the rivet 5 eventually reaches the bottom surface 42A of the friction stir portion 4A. As the rivet 5 is pressed into the second member 32, the lower end 522 passes the bottom surface 42A and enters the second member 32, and expands in the radial direction. As a result, the shank 52 is deformed into a bell shape with the lower end 522 expanded in diameter, and an interlock portion 53 is formed that is pressed into the base material portion of the second member 32 that is not friction stirred. The interlock portion 53 exerts an anchor effect in the peeling direction between the first member 31 and the second member 32.

[0076] [Fourth embodiment of joining method] In the above embodiment, an example was shown in which the head 51 of the rivet 5 is subjected to the crushing step shown in step S6 of Fig. 3 to form the flange 54. Alternatively, a rivet 5 may be used that is provided with a portion corresponding to the flange 54 in advance. The fourth embodiment illustrates this aspect.

[0077] 12A is a vertical cross-sectional view of a rivet 5A used in the fourth embodiment. The rivet 5A comprises a head 51A and a shank 52. An upper end 521 of the shank 52 is connected to the head 51A, and a lower end 522 forms the open end of the cylindrical shank 52. Unlike the rivet 5 shown in FIG. 4, the diameter of the head 51A is larger than the diameter of the shank 52. This large diameter portion becomes the flange 54A that engages with the upper surface of the friction stirring part 4.

[0078] 12B and 12C are cross-sectional views showing the implementation of the joining method according to the fourth embodiment. FIG. 12B is a cross-sectional view showing a state where the step of forming overlapping portion 30 in step S2 has been completed. In tool 1, pin member 11 is raised, and rivet 5A is housed in advance in the hollow portion of shoulder member 12. Head 51A of rivet 5A has an outer diameter slightly smaller than the inner diameter of the hollow portion of shoulder member 12. Thereafter, shoulder member 12 is pressed into overlapping portion 30, and friction stir portion 4 is formed.

[0079] 12C is a cross-sectional view showing the implementation status of the interlock portion forming step S5. Pin member 11 is lowered and head 51A is pressed down. Shank 52 of rivet 5A is pressed into friction stir portion 4 and deformed into a bell shape. As a result, interlock portion 53 is formed at the lower end of shank 52, which is pressed into the base material portion of second member 32. Then, tool 1 is removed from overlapping portion 30.

[0080] The joined body 3 formed by the fourth embodiment has substantially the same form as the joined body 3 shown in Fig. 8B. That is, the lower surface of the flange portion 54A, which is a portion of the head 51A that has a larger diameter than the shaft portion 52, abuts against the upper surface of the friction stir portion 4. This results in a joined body 3 having a joining mode in which the friction stir portion 4 is sandwiched between the interlock portion 53 and the flange portion 54A. According to the fourth embodiment, the rivet head crushing step in step S6 can be omitted.

[0081] [Fifth embodiment of joining method] The fifth embodiment shows an example of a joining method in which the rivet 5A illustrated in the fourth embodiment is used and build-up processing is performed on the head 51A. Figures 13A to 13C and 14A are cross-sectional views showing the joining method according to the fifth embodiment in practice. In the fifth embodiment, a tool 1A is used in which a chamfered portion 131 is provided on the inner peripheral edge of the lower end portion 13T of the clamp member 13.

[0082] 13A is a cross-sectional view showing the completed state of the process of forming the overlapping portion 30 between the first member 31 and the second member 32. The pin member 11 is raised and the tool 1A is in contact with the upper surface of the overlapping portion 30 with the rivet 5A accommodated in advance in the hollow portion of the shoulder member 12. As a result of the chamfered portion 131 being formed on the lower end portion 13T of the clamp member 13, an annular space exists on the outer periphery of the lower end portion 12T of the shoulder member 12.

[0083] Fig. 13B shows the friction stir welding process using the tool 1A. The shoulder member 12 is pressed into the overlapping portion 30 to form the friction stir portion 4A. Here, an example is shown in which the lower end portion 12T of the shoulder member 12 penetrates the first member 31 and is pressed into the upper layer portion of the second member 32. Fig. 13C shows a state in which the shoulder member 12 is retracted from the overlapping portion 30 to perform the backfilling process of the friction stir portion 4A, and then the pin member 11 is lowered to perform the rivet driving process of pressing the rivet 5A into the friction stir portion 4A.

[0084] 14A shows a state in which the pin member 11 is further lowered to advance the press-fitting of the rivet 5A into the friction stir portion 4A, and the diameter of the lower end 522 of the shank 52 is expanded to form an interlock portion 53. At this time, the lower end 12T of the shoulder member 12, which was at the same height as the upper surface 30U of the overlapping portion 30, is raised by a predetermined height. This action fills the space in the chamfered portion 131 with the softened material of the friction stir portion 4A.

[0085] FIG. 14B is a cross-sectional view of a joint 3A obtained by the joining method of the fifth embodiment described above. The joint 3A includes a friction stir part 4A having a padding part 43. The padding part 43 is at the same height as the head 51A of the rivet 5A and covers the side periphery of the head 51A. The padding part 43 may be at a different height from the head 51A of the rivet 5A. The outer peripheral part of the padding part 43 has a tapered shape that follows the shape of the C-chamfer of the chamfered part 131. According to the joint 3A, the padding part 43 engages with the upper surface 30U of the overlapping part 30. Therefore, a structure in which breakage is unlikely to occur between the side peripheral surface 41 of the friction stir part 4A and the base material part of the overlapping part 30 can be achieved.

[0086] [Sixth embodiment of joining method] In the sixth embodiment, an example using a low-cost, simple cylindrical rivet is shown. Figures 17(A) and 17(B) are perspective views of a cylindrical rivet 5C and a pin member 11A used in the joining method according to the sixth embodiment, respectively. Figure 17(C) is a cross-sectional view showing the joining method according to the sixth embodiment in practice.

[0087] The cylindrical rivet 5C (fastened body) is a cylindrical rivet with a constant inner diameter before being pressed into the friction stirring part 4. The pin member 11A has an annular groove 11G capable of accommodating a part of the cylindrical rivet 5C at its lower end 11T. The annular groove 11G opens to the lower end surface of the pin member 11A and extends a predetermined length in the axial direction of the pin member 11A, and has a groove width capable of accommodating the cylindrical rivet 5C with a small gap.

[0088] The cylindrical rivet 5C, which has a simple cylindrical shape, can be easily processed and inexpensively procured, which can contribute to reducing the cost of friction stir welding. On the other hand, the cylindrical rivet 5C is not divided into a head 51 and a shaft 52, as in the above-mentioned rivet 5. For this reason, there is a concern that the position of the curvature starting point where the press-in tip side of the cylindrical rivet 5C expands and deforms may become unstable. If the curvature starting point is unstable, the expansion may be insufficient or buckling may occur, resulting in a problem in which a good interlock portion 53 is not formed.

[0089] In view of the above-mentioned problems, in the sixth embodiment, the pin member 11A is lowered to press the cylindrical rivet 5C into the friction stirring portion 4 while the upper region of the cylindrical rivet 5C is fitted into the annular groove 11G. As shown in FIG. 17(C), the upper region of the cylindrical rivet 5C is treated as the fitted portion 5C1 and the lower region is treated as the press-fit portion 5C2. Then, with the fitted portion 5C1 fitted into the annular groove 11G, the pin member 11A is lowered to press the press-fit portion 5C2 into the friction stirring portion 4. The axial length of the fitted portion 5C1 may be about 1 / 4 to 1 / 2 the total length of the cylindrical rivet 5C. During press-fitting, the upper edge of the cylindrical rivet 5C abuts against the inner wall of the annular groove 11G.

[0090] The fitted portion 5C1 of the cylindrical rivet 5C is supported by fitting into the annular groove 11G, and is therefore an area that does not deform. On the other hand, the press-fit portion 5C2 is in a state where it protrudes from the lower end 11T, and is therefore not supported, and is an area where it can deform. In this case, the stress is most concentrated at the boundary between the fitted portion 5C1 and the press-fit portion 5C2, and the boundary becomes the curvature starting point 5C3. That is, as shown by the dotted line in FIG. 17(C), the press-fit portion 5C2 deforms so as to expand from the curvature starting point 5C3. After the press-fit, the pin member 11A is separated from the overlapping portion 30, and the fitted portion 5C1 protruding from the friction stir portion 4 is crushed by an appropriate tool so as to expand radially outward.

[0091] According to the sixth embodiment, the cost of forming the friction stir welded portion can be reduced because a simple cylindrical rivet 5C is used. Even when a cylindrical rivet 5C is used, the point at which the press-fit portion 5C2 is curved can be stabilized at the curve starting point 5C3. Therefore, the interlock portion 53 can be reliably formed.

[0092] [Seventh embodiment of joining method] In the seventh embodiment, an example is shown in which a mechanically weak point portion that becomes the curvature starting point when the rivet itself is pressed into the friction stir part 4 is formed. Figures 18(A) and (B) are perspective views of a cylindrical rivet 5D and a pin member 11B, respectively, used in the joining method according to the seventh embodiment. Figure 18(C) is a cross-sectional view showing the preparation state of the joining method according to the seventh embodiment.

[0093] The cylindrical rivet 5D (fastening body) is a cylindrical rivet with a constant inner diameter like the cylindrical rivet 5C of the sixth embodiment, but differs in that it has an annular thin-walled portion that becomes a mechanically weak point. The cylindrical rivet 5D has a fitting portion 5D1 (second portion) and a press-fit portion 5D2 (first portion) made of a cylinder having a predetermined first thickness, and a ring groove 5D3 (annular thin-walled portion) that is provided between the fitting portion 5D1 and the press-fit portion 5D2 and has a second thickness that is thinner than the first thickness.

[0094] The pin member 11B used in the seventh embodiment includes a body portion 111, a tip portion 112, and a step portion 113. The body portion 111 is a cylindrical body having an outer diameter slightly smaller than the inner diameter of the shoulder member 12. The tip portion 112 is connected to the lower end of the body portion 111 and is a cylindrical body having a smaller diameter than the body portion 111. The outer diameter of the tip portion 112 is slightly smaller than the inner diameter of the cylindrical rivet 5D. The step portion 113 is a tapered slope provided at the boundary between the body portion 111 and the tip portion 112.

[0095] As shown in FIG. 18(C), the fitting portion 5D1 of the cylindrical rivet 5D is a portion that is fitted onto the tip portion 112 of the pin member 11B. On the other hand, the press-fit portion 5D2 is a portion that is not held by the tip portion 112 and is pressed into the friction stir portion 4 of the overlapping portion 30. The position of the ring groove 5D3 is at a height that is approximately equal to the lower end portion 11T of the pin member 11B when the fitting portion 5D1 is fitted onto the tip portion 112. In this embodiment, a groove having a V-shaped longitudinal section is exemplified as the ring groove 5D3. The ring groove 5D3 may be any specific form as long as it is a thin-walled portion that can reduce the mechanical strength compared to other portions of the cylindrical rivet 5D. In the preparation stage for joining, the pin member 11B is raised so that the cylindrical rivet 5D can be accommodated in the hollow portion of the shoulder member 12, and the fitting portion 5D1 is fitted onto the tip portion 112.

[0096] Steps (A) to (D) in FIG. 19 are cross-sectional views showing the implementation of the joining method according to the seventh embodiment. Step (A) in FIG. 19 shows a state in which friction stir welding is being performed on overlapping portion 30. Shoulder member 12 is pressed into overlapping portion 30 and rotated about its axis to form friction stir portion 4. Step (B) in FIG. 19 shows a pushing-in step of cylindrical rivet 5D. After shoulder member 12 is raised to backfill the friction stir material, pin member 11B is lowered. This operation causes press-in portion 5D2 of cylindrical rivet 5D to be pressed into friction stir portion 4. Press-in portion 5D2 is expanded and deformed with ring groove 5D3 as the curvature starting point. The lower end of press-in portion 5D2 enters second member 32 around friction stir portion 4 to form interlock portion 53D.

[0097] Steps (C) and (D) in FIG. 19 show the process of expanding the fitting portion 5D1. From the state of step (B), only the shoulder member 12 is raised to a position higher than the upper end of the fitting portion 5D1. This releases the support of the outer peripheral surface of the fitting portion 5D1. After that, when the pin member 11B is slightly lowered, the step portion 113 presses the upper end of the fitting portion 5D1. This action imparts a bending tendency of the expanding deformation to the fitting portion 5D1, as shown in step (C), with the ring groove 5D3 as the curvature starting point. Due to the bending tendency, the upper edge of the fitting portion 5D1 faces the lower end portion 12T of the shoulder member 12.

[0098] 19, the shoulder member 12 is lowered while the clamp member 13 is raised. This operation causes the fitting portion 5D1 to be largely expanded and deformed without being hindered by the clamp member 13. When the shoulder member 12 is further lowered, the outer circumferential surface of the fitting portion 5D1 comes into contact with the upper surface 30U of the overlapping portion 30. As a result, the fitting portion 5D1 forms a flange portion having a larger diameter than the friction stir portion 4. Therefore, a joined body 3 can be formed in which the friction stir portion 4 is sandwiched between the interlock portion 53D and the fitting portion 5D1.

[0099] According to the seventh embodiment, a cylindrical rivet 5D is used, so the cost of forming the friction stir welded portion can be reduced. In addition, the press-fit portion 5D2 and the fitting portion 5D1 can be deformed and expanded from the ring groove 5D3, so that the curvature starting point can be stabilized and damage such as cracking can be prevented from occurring in the rivet 5D. As a modification of the seventh embodiment, a simple cylindrical rivet without the ring groove 5D3 may be used.

[0100] [Eighth embodiment of joining method] In the eighth embodiment, an example is shown in which a rivet is used like a stud bolt. Fig. 20A is a perspective view of a threaded rivet 5E (fastened body) used in the fastening method according to the eighth embodiment, and Fig. 20B is a cross-sectional view showing the state of implementation of the fastening method according to the eighth embodiment.

[0101] The threaded rivet 5E is made of a cylindrical body and includes a threaded portion 5E1 with a thread groove and a press-fit portion 5E2 that is press-fitted into the overlapping portion 30. The threaded portion 5E1 is disposed on one end side of the threaded rivet 5E, and serves as a portion that protrudes from the overlapping portion 30. A nut 55 that can be screwed into the thread groove of this threaded portion 5E1 is prepared in advance as a fixing member.

[0102] The threaded rivet 5E is, for example, similar to the above-described embodiment, with the press-fit portion 5E2 pressed into the overlapping portion 30 using a friction stir spot welding tool 1. This press-fitting causes the press-fit portion 5E2 to expand and deform, forming an interlock portion 53E. Thereafter, the nut 55 is screwed onto the threaded portion 5E1 protruding from the upper surface 30U of the overlapping portion 30 via a spring washer 561 and a flat washer 562.

[0103] The flat washer 562 is selected to have an outer diameter larger than the diameter of the friction stir portion 4 and an inner diameter that allows the threaded portion 5E1 to be loosely fitted therein. When the nut 55 is fastened, the flat washer 562 is pressed against the upper surface 30U of the overlapping portion 30 via the spring washer 561. Therefore, a joined body 3 can be formed in which the friction stir portion 4 is sandwiched between the interlock portion 53E and the flat washer 562. The spring washer 561 and the flat washer 562 may be omitted. In this case, it is desirable to use a nut having a diameter larger than the diameter of the friction stir portion 4 as the nut 55.

[0104] According to the eighth embodiment, the threaded rivet 5E is press-fitted into the friction stir portion 4 so that the threaded portion 5E1 protrudes from the overlapping portion 30, and the nut 55 is fastened to the threaded portion 5E1. Therefore, the locking effect of the interlock portion 53E is superimposed on the locking effect of the fastening of the nut 55, and the overlapping portion 30 can be joined more firmly.

[0105] [Other variations] Although the embodiment of the present disclosure has been described above, the present disclosure is not limited to the above embodiment. For example, the following modified embodiments are possible.

[0106] (1) In the above embodiment, an example has been shown in which the overlapping portion 30 is formed of two layers, the first member 31 and the second member 32. The overlapping portion 30 may be formed of three or more layers. Fig. 15 is a cross-sectional view showing a bonded body 3B according to a modified example. The bonded body 3B is made of a four-layer laminate of the first member 31, the second member 32, and the third member 35 and the fourth member 36 interposed therebetween.

[0107] The first member 31 is disposed in the top layer, which is the side into which the tool 1 is first pressed in friction stirring, and the second member 32 is disposed in the bottom layer, which is the side into which the tool 1 is last pressed in. The friction stir part 4B is formed to penetrate the first member 31, the third member 35, and the fourth member 36, and to reach a depth of about half of the second member 32. The rivet 5B has an interlock part 53 near the lower end of the shank 52, which penetrates into the base material part of the second member 32. In addition, the flange part 54B engages with the upper surface of the first member 31.

[0108] (2) In order to increase the bending rigidity and peel strength of the joint to be friction stir welded, the layers of the members constituting the overlapping portion 30 may be bonded in advance by a fastening means such as fusion or adhesion before friction stir welding. When the overlapping portion 30 is formed of three or more layers, at least one of the layers is bonded in advance. FIG. 21 is a cross-sectional view showing an example of a joint 3D in which one of the layers of the overlapping portion 30 is previously fixed before friction stir welding. The joint 3D is a three-layer laminate of a first member 31, a second member 32, and a third member 35 interposed therebetween. A joint 38 is provided between the third member 35 and the second member 32 to previously integrate them. The friction stir portion 4F penetrates the first member 31 and the third member 35 and reaches a depth of about half of the second member 32. The rivet 5F has an interlock portion 53F near the lower end of the shaft portion 52F, and enters the base material portion of the second member 32. The head portion 51F is exposed on the upper surface of the friction stirring portion 4F.

[0109] When forming the overlapping portion 30 for the joint 3D, a joint 38 is provided between the upper surface of the second member 32 and the lower surface of the third member 35, and the two are joined together. The joint 38 can be formed by various fusion methods, such as ultrasonic fusion and heat fusion, or by a bonding method using an adhesive or the like. The joint 38 may be provided on the entire mating surfaces of the second member 32 and the third member 35, or may be provided in a dotted or striped pattern. Friction stirring and driving of the rivets 5F after the formation of the overlapping portion 30 can be performed in the same manner as in the above-mentioned embodiment.

[0110] The joint 38 may be provided on the mating surface between the first member 31 and the third member 35, or on both the mating surface between the first member 31 and the third member 35 and the mating surface between the second member 32 and the third member 35. The formation of the joint 38 allows the members to be integrated in advance, thereby increasing the bending rigidity and peel strength of the completed joint 3D. The same applies when the overlapping portion 30 is formed of four or more layers. In the overlapping portion 30 of four or more layers, three or more mating surfaces are generated between the members. Among these, at least one mating surface is bonded in advance. In particular, it is desirable to bond the members so that they are consolidated into two, a member (group) including the member of the top layer and a member (group) including the member of the bottom layer. When the overlapping portion 30 is formed of two layers, the first member 31 and the second member 32, the joint 38 can be provided between those layers. In this case, the peel strength between the first member 31 and the second member 32 is increased.

[0111] (3) In the above embodiment, an example has been shown in which the double-action friction stir spot welding tool 1 is used as the tool for forming the friction stir portion 4. Instead of this, a friction stir line welding tool, a single-action friction stir spot welding tool, or another friction stir welding tool may be used as the tool.

[0112] (4) In the above embodiment, an example was shown in which interlock portion 53 formed by shank 52 of rivet 5 has a larger diameter than friction stir portion 4 (for example, Figs. 8A to 8C). That is, an example was shown in which lower end 522 of shank 52 is expanded radially outward beyond side circumferential surface 41 of friction stir portion 4. Interlock portion 53 is not limited to the aspect of the above embodiment as long as it exerts an anchor effect on the base material portion of second member 32.

[0113] 16 is a cross-sectional view showing a joint 3C according to another modified example. A rivet 5A is press-fitted into the friction stir portion 4C formed in the overlapping portion 30. The shank 52 of the rivet 5A penetrates exclusively below the friction stir portion 4C. The shank 52 is deformed into a bell shape, and an interlock portion 53 is formed with a lower end 522 press-fitted into the base material portion of the second member 32. However, the interlock portion 53 remains in an area radially inward of the side peripheral surface 41 of the friction stir portion 4C. Even with this type of interlock portion 53, it is possible to achieve a sufficient anchor effect.

[0114] [Inventions included in the above embodiments] A joining method according to one aspect of the present disclosure is a joining method using a friction stir welding tool and a fastener to join an overlapping portion formed including a first member on the tool side and a second member arranged below the first member, in which the tool is pressed into the overlapping portion to perform friction stirring, thereby forming a friction stir portion in the overlapping portion, and the fastener is pressed into the friction stir portion from the first member side.

[0115] In the above joining method, it is preferable to form an interlock portion by inserting a part of the fastener into the second member after the fastener is pressed in. According to this joining method, a joined body in which the first member and the second member are firmly engaged can be obtained by the anchor effect of the interlock portion.

[0116] In the above joining method, it is preferable to deform the fastener after the start of the press-fitting and to cause a part of the fastener to enter the second member present around the friction stir portion, thereby forming the interlock portion. In the friction stir portion, factors inhibiting the deformation of the fastener are alleviated, so that the fastener can be easily deformed as intended. According to the above joining method, the interlock portion can be reliably formed by the deformation of the fastener.

[0117] In the above-mentioned joining method, it is preferable that the friction stir portion is formed so as to penetrate the first member and reach a part of the second member. According to this aspect, it is possible to more reliably form an interlock portion in the second member.

[0118] In the above welding method, it is preferable that the fastener is pressed into the friction stir part using the tool. According to this welding method, the welding method can be performed without separately preparing a tool for driving the fastener.

[0119] In the above-mentioned joining method, it is desirable to use as the tool a double-acting friction stir spot joining tool including a cylindrical pin member that rotates about an axis and can move back and forth in the axial direction, and a cylindrical shoulder member that is positioned to cover the outer periphery of the pin member, rotates about the same axis as the pin member and can move back and forth in the axial direction, and to press the fastener into the friction stir portion by lowering the pin member or the shoulder member.

[0120] According to this joining method, the pin member or shoulder member of the tool is used to perform friction stirring and press-fitting of the fastened body, which increases the degree of freedom in the friction stirring operation and the press-fitting operation of the fastened body.

[0121] In the above-mentioned joining method, it is preferable to raise the pin member to create an accommodation space within the shoulder member, load the fastener into the accommodation space in advance, press the shoulder member into the overlapping portion to perform the friction stirring, and then lower the pin member to press in the fastener.

[0122] According to this joining method, the fastener is loaded in the tool in advance, friction stir is performed by the shoulder member, and then the fastener is pressed in by the pin member. Therefore, the process from friction stir to press-in of the fastener can be carried out smoothly on an assembly line.

[0123] In the above-mentioned joining method, the pin member or the shoulder member may be pressed into the overlapping portion to perform the friction stir welding, the fastener may be disposed below the pin member or between the pin member and the shoulder member and the friction stir portion, and the pin member or the shoulder member may be lowered to press in the fastener. This joining method can increase the degree of freedom in the friction stir welding operation and the press-in operation of the fastener.

[0124] In the above joining method, it is desirable that the fastener has a head to which a pressure force is applied, and after forming the interlock portion, the head of the fastener is deformed to form a flange portion that engages with an upper surface of the friction stir portion or an upper surface of the first member on the periphery of the friction stir portion.

[0125] According to this joining method, the friction stir part is sandwiched between the interlock part and the flange part. That is, the interlock part, which exerts a strong anchor effect by being pressed into the base material part of the second member, serves as a holding point, and a structure is realized in which the flange part engages the upper surface of the friction stir part. Therefore, the fixation of the friction stir part to the overlapping part is improved, and a joined body with excellent stability can be obtained.

[0126] The above joining method may include a step of previously bonding at least one of the layers of the members constituting the overlapping portion, prior to friction stir welding with the tool.

[0127] According to this joining method, the components of the overlapping portion are already joined before friction stir welding, so that the bending rigidity and peel strength of the joined body can be further increased.

[0128] A joint according to another aspect of the present disclosure is a joint of an overlapping portion formed to include a first member and a second member, the joint comprising: an overlapping portion in which the first member is positioned at one end in the overlapping direction and the second member having a second thickness is positioned at the other end in the overlapping direction; a friction stir portion provided in the overlapping portion; and a fastener pressed into the friction stir portion.

[0129] In the above-mentioned joined body, it is preferable that the fastener has an interlocking portion in which a part of the fastener is inserted into the second member. With this joined body, the first member and the second member can be firmly joined by the anchor effect of the interlocking portion.

[0130] In the above-mentioned joined body, it is preferable that the friction stir part is formed so as to penetrate the first member and reach a part of the second member. According to this aspect, in addition to the joining force of the interlock part, the joining force of the friction stir part can also be applied to the overlapping part.

[0131] In the above-mentioned joined body, it is preferable that the second member or both the first member and the second member are made of a fiber-reinforced thermoplastic resin. In particular, it is preferable that at least the second member is made of a molded body in which continuous fibers are impregnated with a thermoplastic resin.

[0132] When joining members made of thermoplastic resin containing reinforcing fibers, particularly continuous fibers, by pressing in a fastener, the fibers may hinder the deformation of the fastener, and the fastener may not be able to exert an anchoring effect on the overlapping portion. However, with the above-mentioned joint, the fastener is driven into the friction stir portion where the fibers are cut by friction stirring and the thermoplastic resin is softened. Therefore, the fastener is more likely to deform as it should within the friction stir portion. As a result, an interlock portion that exerts an excellent anchoring effect is formed.

[0133] In the above-mentioned joint, it is preferable that the fastener is a self-pierce rivet having a head and a shank connected to the head and having a hollow area therein, and the interlock portion is formed by a deformed portion of the lower end area of ​​the shank. With this joint, a joint having excellent strength can be constructed by using a self-pierce rivet which is widely used for various overlapping parts.

[0134] In the above-mentioned joint, it is desirable that the fastener has a head to which a pressure force is applied during the driving, and that the head has a flange portion that engages with an upper surface of the friction stir portion or an upper surface of the first member on the periphery of the friction stir portion.

[0135] With this joint, the friction stir part is sandwiched between the interlock part and the flange part. That is, a structure is realized in which the flange part engages the upper surface of the friction stir part, with the interlock part exerting an anchor effect as a holding base point. Therefore, the fixation of the friction stir part to the overlapping part is improved, and a joint with excellent stability can be obtained.

[0136] In the above bonded structure, the overlapping portion may be an overlapping portion formed between the first member and the second member by interposing one or more other members. This bonded structure can provide high bonding strength to a bonded structure made of three or more layers of overlapping members.

Claims

1. A joining method for joining an overlapping portion including a first member on the tool side and a second member disposed below the first member, by using a friction stir welding tool and a fastener, the method comprising: The tool is pressed into the overlapping portion to perform friction stirring, thereby forming a friction stir portion in the overlapping portion; The fastening body is press-fitted into the friction stir portion from the first member side.

2. The bonding method according to claim 1 , A joining method comprising the steps of: after the fastener is pressed in, inserting a portion of the fastener into the second member to form an interlock portion.

3. The joining method according to claim 2, A joining method comprising: deforming the fastener after the start of the press-fitting; and causing a part of the fastener to penetrate into the second member present around the friction stir portion, thereby forming the interlock portion.

4. The bonding method according to any one of claims 1 to 3, The friction stir portion is formed to penetrate the first member and reach a part of the second member.

5. The bonding method according to any one of claims 1 to 4, The joining method further comprises using the tool to press the fastener into the friction stir portion.

6. The joining method according to claim 5, The tools include: A cylindrical pin member that rotates about an axis and is movable back and forth in the axial direction; a cylindrical shoulder member that is positioned so as to cover the outer periphery of the pin member, rotates around the same axis as the pin member, and is movable back and forth in the axial direction; The joining method includes pressing the fastener into the friction stir portion by lowering the pin member or the shoulder member.

7. The joining method according to claim 6, The pin member is raised to create an accommodation space in the shoulder member, and the fastener is pre-loaded into the accommodation space; The shoulder member is pressed into the overlapping portion to perform the friction stirring. The fastener is pressed into place by lowering the pin member.

8. The joining method according to claim 7, A cylindrical rivet is used as the fastening body, As the pin member, a pin member having an annular groove formed on a lower end surface thereof capable of accommodating a part of the cylindrical rivet is used, a joining method in which the pin member is lowered to press-fit the cylindrical rivet while the upper region of the cylindrical rivet is fitted into the annular groove.

9. The joining method according to claim 7, As the fastening body, a cylindrical rivet having a fitting portion that is fitted onto the pin member and a press-fit portion that is press-fitted into the overlapping portion is used, As the pin member, a pin member having a tip portion capable of fitting the fitting portion thereon is used, a joining method including: with the fitting portion fitted onto the tip portion, lowering the pin member to press-fit the press-fit portion; and then lowering the shoulder member to expand and deform the fitting portion.

10. The joining method according to claim 6, The pin member or the shoulder member is pressed into the overlapping portion to perform the friction stirring. The fastening body is disposed below the pin member, or between the pin member and the shoulder member and the friction stir portion; The fastener is press-fitted by lowering the pin member or the shoulder member.

11. The bonding method according to claim 2 or 3, The fastening body has a head to which a press-fitting force is applied, A joining method, comprising: forming the interlock portion; and then deforming the head of the fastener to form a flange portion that engages with an upper surface of the friction stir portion or an upper surface of the first member on the periphery of the friction stir portion.

12. The bonding method according to any one of claims 1 to 11, As the fastening body, a threaded rivet having a threaded portion having a thread groove and a press-fit portion to be press-fitted into the overlapping portion is used, a fastening member that can be screwed into the thread groove is attached to the threaded portion after the press-fit portion is press-fitted into the friction stir portion.

13. The bonding method according to any one of claims 1 to 12, The joining method includes a step of pre-bonding at least one of the layers of the members constituting the overlapping portion before friction stirring with the tool.

14. A joint body of an overlapping portion formed including a first member and a second member, an overlapping portion where the first member is disposed on one end side in an overlapping direction and the second member is disposed on the other end side in the overlapping direction; A friction stir portion provided in the overlapping portion; A fastening body press-fitted into the friction stir portion, The first member and the second member have the friction stir portion and a base material portion, A joint, wherein the fastener has an interlock portion in which a part of the fastener is inserted into the base material portion.

15. The joint body according to claim 14, The friction stir portion is formed so as to penetrate the first member and reach a part of the second member.

16. The joint body according to claim 14 or 15, The second member, or both the first member and the second member, are made of a fiber-reinforced thermoplastic resin.

17. The joint body according to claim 16, A bonded body, wherein at least the second member is made of a molded body in which continuous fibers are impregnated with a thermoplastic resin.

18. The joint body according to claim 14, the fastening body is a self-pierce rivet including a head and a shank portion connected to the head and including a hollow region therein, The interlock portion is formed by a deformed portion of a lower end region of the shaft portion.

19. The joint body according to any one of claims 14 to 18, The fastening body has a head to which a press-fitting force is applied during the press-fitting, The head portion has a flange portion that engages with an upper surface of the friction stir portion or an upper surface of the first member at a periphery of the friction stir portion.

20. The joint body according to any one of claims 14 to 18, The fastened body is a cylindrical rivet having a constant inner diameter before being pressed into the friction stir portion.

21. The joint body according to any one of claims 14 to 18, The fastening body is a cylindrical rivet, and is a joint having a first portion that is pressed into the overlapping portion, a second portion that is expanded and deformed after the first portion is pressed into the overlapping portion, and a ring-shaped thin-walled portion provided between the first portion and the second portion.

22. The joint body according to any one of claims 14 to 21, A joint, wherein the overlapping portion is an overlapping portion formed between the first member and the second member with one or more other members interposed therebetween.

23. The joint body according to any one of claims 14 to 22, The fastener has a threaded portion having a thread groove and a press-fit portion that is press-fitted into the overlapping portion, The assembly further comprises a fastening member attached to the threaded portion by being screwed into the thread groove.

24. A joining device that joins an overlapping portion formed including a first member and a second member, A cylindrical pin member that is movable back and forth in an axial direction; a cylindrical shoulder member that is positioned so as to cover an outer periphery of the pin member, that rotates about the same axis as the pin member, and that is movable back and forth in the axial direction; a fastening body that is loaded into an accommodation space created by the lifting of the pin member and is pressed into a friction stir portion formed in the overlapping portion by the pin member; A joining device comprising:

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