Rotary member for friction stirring, joining device, and joining method

Abstract

The purpose of the present invention is to provide a rotary member for friction stirring capable of performing high-strength joining while suppressing occurrence of joining defects in friction stir welding. A rotary member for friction stirring provided in a joining device that performs friction stir welding of members to be joined, the rotary member for friction stirring being configured such that, in a state in which the rotary member for friction stirring is provided on an output shaft of a drive mechanism of the joining device so as to be rotated by rotation output from the drive mechanism, a play that enables vibration of a pin part inserted into the members to be joined during friction stirring with respect to the output shaft is generated between the output shaft and the pin part, and as a result of the play, the vibration of the pin part at the time of friction stirring has an amplitude and / or a frequency larger than that of the vibration of the output shaft.

Description

Friction stirring rotating member, joining device, and joining method

[0001] The present invention relates to a friction stir welding rotating member, a welding device, and a welding method for friction stir welding (FSW).

[0002] In Patent Document 1, the stirring pin is disposed on the main body so that it can rotate upon receiving rotational force from the main body and move axially along the rotating shaft. Furthermore, a first elastic member (e.g., a coil spring) is provided to bias the stirring pin toward the tip of the main body in the axial direction of the rotating shaft. Furthermore, the shoulder is disposed on the main body so that it can move independently of the stirring pin in the axial direction of the rotating shaft without receiving rotational force from the main body. Furthermore, a second elastic member is provided to bias the shoulder toward the tip of the main body in the axial direction of the rotating shaft. Even if the height of the workpieces changes while the stirring pin is being pressed into the workpieces at a constant height, the first elastic member deforms in accordance with the change in the height of the workpieces, thereby maintaining a constant insertion depth of the stirring pin (

[0041] ). The action of the first elastic member ensures that the stirring pin is inserted into the workpieces at a constant depth, thereby forming a plasticized region at a constant depth (

[0071] ). In this way, in the technique of Patent Document 1, the first elastic member biases the stirring pin toward the workpieces, and the stirring pin is inserted into the workpieces to a certain depth.

[0003] In Patent Document 2, the stirring pin and shoulder constitute an assembly. The assembly is rotatable relative to one another and is movable integrally in the axial direction of the rotating shaft. Furthermore, a first elastic member (e.g., a coil spring) is provided to bias the assembly toward the tip of the stirring pin in the axial direction of the rotating shaft. In the technology of Patent Document 2, the first elastic member also keeps the insertion depth of the stirring pin constant, and a plasticized region is formed at a constant depth (

[0033] ,

[0052] ).

[0004] In Patent Document 3, the rotary tool has a main body and a stirring member. The main body has a fixed portion that is attached to and fixed on a welding device, and a rotating shaft that transmits rotational force from the welding device. The stirring member has a stirring pin, is rotatably mounted upon receiving rotational force from the rotating shaft, and is mounted on the main body so as to be movable in the axial direction of the rotating shaft. Furthermore, an elastic member (coil spring) is provided that biases the stirring member toward the tip in the axial direction of the rotating shaft. In the technology of Patent Document 3, the elastic member also keeps the insertion depth of the stirring pin constant, and a plasticized region is formed at a constant depth (

[0035] ,

[0051] ).

[0005] In all of Patent Documents 1 to 3, the stirring pin is biased toward the workpieces to be joined by an elastic member (coil spring) and pressed against the workpieces to be joined, so that the insertion depth of the stirring pin is kept constant and a plasticized region is formed at a constant depth.

[0006] JP 2023-069370 A JP 2023-069371 A JP 2023-069372 A

[0007] With regard to friction stir welding, it is desired to provide a friction stir rotating member, a welding device, and a welding method that enable high-strength welding while suppressing the occurrence of welding defects.

[0008] An object of the present invention is to provide a friction stir rotating member, a welding device, and a welding method that enable high-strength welding while suppressing the occurrence of welding defects in friction stir welding.

[0009] The present inventors have conducted extensive research in light of the above-mentioned problems and have obtained the following findings.

[0010] Conventionally, in friction stir welding, the support structure for the stirring pin has been designed based on the design concept of how to perform friction stirring with the stirring pin in a stable state. To achieve this, external force has been forcibly applied to the stirring pin, such as how to urge the stirring pin toward the workpieces to stably press and insert the workpieces. In Patent Documents 1 to 3, the elastic member is also provided to keep the insertion amount of the stirring pin constant and form a plasticized region at a constant depth. Patent Documents 1 to 3 fall within the scope of conventional design concepts.

[0011] In response to this, the inventors have shifted their thinking from the conventional design concept and discovered that by passively vibrating the pin portion inserted into the workpieces at a larger amplitude and / or frequency than the base vibration by contacting the workpieces undergoing plastic flow, it is possible to achieve a high-strength joint while suppressing the occurrence of joint defects, and have completed the present invention. This finding is completely different from the conventional friction stir welding described above. Therefore, even a person skilled in the art would not have easily arrived at this finding from conventional friction stir welding technology. The present invention can employ the following configurations.

[0012] (1) A friction stirring rotating member provided in a joining device that performs friction stir welding of workpieces, wherein the friction stirring rotating member is provided on an output shaft of a drive mechanism provided in the joining device so as to rotate with rotation output from the drive mechanism, and the friction stirring rotating member generates play between the output shaft and a pin portion that is inserted into the workpieces during friction stirring, allowing the pin portion to vibrate relative to the output shaft, and the play causes the vibration of the pin portion to have a larger amplitude and / or frequency than the vibration of the output shaft during friction stirring.

[0013] The friction stirring rotating member (1) has play between the output shaft and the pin portion, which allows the pin portion to vibrate relative to the output shaft. The friction stirring rotating member is configured such that the play causes the vibration of the pin portion during friction stirring to have a greater amplitude and / or frequency than the vibration of the output shaft. The output shaft of the drive mechanism vibrates in conjunction with the transmission of rotation from the drive mechanism during friction stirring. This vibration is also referred to as base vibration. Base vibration is vibration that inevitably occurs during friction stirring. During friction stirring, the vibration of the pin portion has a greater amplitude and / or frequency than the base vibration. During friction stirring, the pin portion rotates within the play while moving to pass the plastically flowing workpieces rather than resisting them. This movement causes the vibration of the pin portion. In other words, the vibration of the pin portion is caused by the play. The vibration of the pin portion is not vibration caused by output from a drive source other than the drive mechanism. The vibration of the pin portion is unlikely to interfere with the plastic flow of the workpieces. Furthermore, the vibration of the pin portion can be synchronized with the plastic flow of the workpieces to be welded. This allows the vibration of the pin portion to amplify the plastic flow of the workpieces to be welded. This vibration of the pin portion can therefore perform high-strength welding while suppressing the occurrence of welding defects. Additionally, the tilt angle (advance angle) of the friction stir rotating member and the output shaft may be 0 degrees. Even with a tilt angle of 0 degrees, good friction stir welding can be achieved. Because the above-mentioned vibration of the pin portion can be achieved by play, a complex spindle mechanism is not required. The generation of excessive frictional heat can be suppressed. The generation of excessive friction applied to the pin portion can be suppressed. By vibrating the pin portion, the transmission of vibration from the downstream side of the play to the upstream side in the power transmission path from the drive mechanism to the pin portion can be suppressed. The load applied to the output shaft can be reduced.

[0014] The friction stirring rotating member itself may have play within the friction stirring rotating member. The friction stirring rotating member may be configured so that play occurs between the friction stirring rotating member and the output shaft when the friction stirring rotating member is attached to an output shaft. The friction stirring rotating member may not have a pin portion, but rather, a pin portion may be attached to the friction stirring rotating member so that play occurs between the friction stirring rotating member and the pin portion. The joining device is not limited to a dedicated friction stir welding device, and may be, for example, a machining center, a robot, a milling machine, a multi-tasking machine, a general-purpose machine, or a portable device large enough for a user to hold in their hand to perform friction stir welding. The control conditions (position, load, spindle load, heat, pressure, etc.) of the joining device or its auxiliary mechanisms are not particularly limited. The joining conditions (feed speed, rotation speed, joining temperature, advance angle) are also not particularly limited. The materials of the workpieces are not particularly limited. The workpieces may be the same material or different materials. In the embodiments described below, the play is provided by a key (a mating key or a fixed key), but this example is not limiting. The structure for providing the play is not particularly limited, and a conventionally known structure can be employed. In addition to a key, components for providing the play, such as bolts, pins, and spherical bodies, can be employed. The play itself may also be provided by the shape of the friction stirring rotating member itself. The friction stirring rotating member may be divided into multiple (e.g., two) components, and the play may be formed by the fit between adjacent components. The amplitude and frequency of the vibration are not particularly limited, and can be adjusted by changing the amount of play or the weight of the component downstream of the play in the power transmission path from the drive mechanism to the pin portion. For example, the weight can be changed by installing a weight. In the joining device, the drive mechanism includes a rotating machine. The rotating machine may be, for example, a rotating electric machine or an internal combustion engine. The drive mechanism may include a transmission that changes the rotational speed output from the rotating machine and outputs the rotation. The transmission may be a speed reducer or a speed increaser. When the drive mechanism includes a transmission, the output shaft of the transmission corresponds to the output shaft of the drive mechanism. When the drive mechanism does not include a transmission, the output shaft of the rotating machine corresponds to the output shaft of the drive mechanism.In one embodiment, the backlash and margin in the drive mechanism do not constitute play. In one embodiment, the play is provided downstream of the upstream edge of the output shaft of the drive mechanism in the power transmission path from the drive mechanism to the pin portion.

[0015] (2) The friction stirring rotating member of (1), wherein the friction stirring rotating member comprises: a rotating shaft portion provided on the output shaft; and a tip portion configured to rotate by rotation transmitted from the rotating shaft portion and located distal to the rotating shaft portion, the tip portion having the pin portion and a base end side portion provided on the base end side of the pin portion, or having a base end side portion that does not have the pin portion but is configured to allow the pin portion to be detachably attached, the play is provided between the rotating shaft portion and the tip portion so as to enable vibration of the pin portion relative to the rotating shaft portion, and the friction stirring rotating member is configured so that, due to the play, the vibration of the pin portion during friction stirring has a larger amplitude and / or frequency than the vibration of the rotating shaft portion.

[0016] The friction stirring rotating member (2) has play between the rotating shaft and the tip. Due to this play, the vibration of the pin during friction stirring has a larger amplitude and / or frequency than the vibration of the output shaft. This vibration is not generated by the output from a drive source other than the drive mechanism. This vibration is unlikely to interfere with the plastic flow of the workpieces. Furthermore, this vibration can amplify the plastic flow of the workpieces. Therefore, high-strength joining can be achieved while suppressing the occurrence of joining defects.

[0017] When the pin portion and the base end portion are integrally configured, the pin portion is the portion that enters the workpiece, and the base end portion is the portion provided on the base end side of the pin portion, and thus the pin portion and the base end portion can be distinguished. On the other hand, when the pin portion and the base end portion are separable, for example, when the pin portion is detachable from the base end portion, the pin portion and the base end portion can be physically distinguished. For example, the pin portion corresponds to the tool, and the base end portion corresponds to the collet. When the tip portion does not have a pin portion, the tip portion may be the base end portion itself, which is configured to detachably attach the pin portion.

[0018] (3) The friction stirring rotating member of (2), wherein the tip portion has a surface contact portion at a height on the base end side of the pin portion where it contacts the surface of the workpiece, and the ratio of the diameter of the surface contact portion to the diameter of the pin portion adjacent to the surface contact portion closer to the tip than the surface contact portion is 1.8 or less, and thus the tip portion is configured to have a shoulder with a width small enough to satisfy the ratio, or to have no shoulder.

[0019] As described above, the vibration generated by the pin due to play does not interfere with the plastic flow of the workpieces and can amplify the plastic flow of the workpieces. Since the friction stir rotating member (3) has a narrow shoulder or no shoulder at all, the area of ​​the shoulder that contacts the surface of the workpieces, covering the workpieces undergoing plastic flow, is reduced. This makes it less likely for the shoulder to interfere with plastic flow. As a result, the effect of the pin vibration, which is to both minimize and amplify plastic flow, can be more effectively achieved. Furthermore, if the rotating shoulder is narrow or absent, the amount of heat applied to the workpieces by the rotating shoulder is reduced, but the effect of the pin vibration enables effective plastic flow. As a result, friction stir welding can be performed at lower temperatures. Friction stir welding at low temperatures can reduce the impact of temperature on the workpieces. This reduces the occurrence of thermal deformation and stress, potentially improving the mechanical properties of the welded components compared to those after conventional friction stir welding. Furthermore, lowering the temperature of friction stir welding reduces energy consumption. It may also become possible to use materials that are difficult to weld at high temperatures as welded components.

[0020] The ratio is not particularly limited, but is preferably 1.8 or less in the above (3). Furthermore, the ratio is more preferably 1.5 or less, even more preferably 1.3 or less, and particularly preferably 1.1 or less. This is because the occurrence of a situation in which the shoulder interferes with plastic flow can be suppressed. When the ratio is 1.0, the friction stir rotating element does not have a shoulder. A configuration without a shoulder is also a preferred embodiment of the friction stir rotating element. The ratio may be, for example, less than 2.0. In conventional friction stir welding, the ratio is, for example, 2 or more. The ratio may be 2 or more. By vibrating the shoulder together with the pin, the effect of preventing and amplifying plastic flow can be obtained. The shoulder may be configured not to rotate with the pin. Friction stir welding performed in a configuration in which the shoulder does not rotate with the pin is called Stationary Shoulder Friction Stir Welding (SSFSW). SSFSW allows for low heat input to the plastic flow zone (joint), thereby improving the mechanical properties, microstructure, and surface finish of the plastic flow zone. As described above, an embodiment with a small shoulder width or no shoulder allows friction stir welding to be performed at lower temperatures, and is therefore suitable for SSFSW. That is, when the friction stir rotating member has a shoulder, the shoulder may be configured to rotate together with the pin portion, or may be configured not to rotate together with the pin portion. A shoulder that does not rotate together with the pin portion may be installed on the friction stir rotating member or welding device as a separate unit from the friction stir rotating member. A shoulder that does not rotate together with the pin portion may be fixed to the friction stir rotating member or welding device in a manner that does not rotate at all, or may be configured to rotate separately from the pin portion.

[0021] (4) The friction stirring rotating member according to any one of (1) to (3), wherein the friction stirring rotating member is configured such that vibration of the pin portion is passively generated by contact with the workpieces undergoing plastic flow within the range of play.

[0022] In the friction stirring rotating member (4), the pin portion passively vibrates within the range of play due to contact with the plastically flowing workpieces. During friction stirring, the pin portion rotates within the range of play while moving to deflect rather than resist the plastically flowing workpieces. This movement passively generates vibration in the pin portion. Therefore, the vibration of the pin portion is unlikely to interfere with the plastic flow of the workpieces. Furthermore, this vibration can amplify the plastic flow of the workpieces. Therefore, high-strength joining can be achieved while suppressing the occurrence of joining defects.

[0023] (5) The friction stirring rotating member according to any one of (1) to (4), wherein the friction stirring rotating member is configured such that the pin portion vibrates in at least one of the axial direction, circumferential direction, and radial direction of the pin portion due to the play.

[0024] The friction stirring rotating member (5) can perform high-strength joining while suppressing the occurrence of joining defects by vibrating the pin portion toward at least one of the two sides.

[0025] When play is provided between the output shaft and the pin portion in the axial direction, the pin portion can vibrate in the axial direction. When play is provided in the circumferential direction, the pin portion can vibrate in the circumferential direction. When play is provided in the radial direction, the pin portion can vibrate in the radial direction. The play is provided in at least one of the axial, circumferential, and radial directions of the pin portion. For example, the following play can be provided between the output shaft and the pin portion: (A) play only in the axial direction; (B) play only in the circumferential direction; (C) play only in the radial direction; (D) a combination of axial play and circumferential play; (E) a combination of axial play and radial play; (F) a combination of circumferential play and radial play; or (G) a combination of circumferential play, circumferential play, and radial play. In the case of (A) above, the pin portion can vibrate at least in the axial direction. In the case of (B) above, the pin portion can vibrate at least in the circumferential direction. In the case of (C) above, the pin portion is capable of vibrating at least in the radial direction. In the case of (D) above, the pin portion is capable of vibrating at least in the axial and circumferential directions. In the case of (E) above, the pin portion is capable of vibrating at least in the axial and radial directions. In the case of (F) above, the pin portion is capable of vibrating at least in the circumferential and radial directions. In the case of (G) above, the pin portion is capable of vibrating in the axial, circumferential, and radial directions. Note that this paragraph describes the play provided between the output shaft and the pin portion. However, if the play is provided between the rotating shaft portion and the tip end, the "output shaft" in this paragraph can be read as "rotating shaft portion." The amount of play in either direction is not particularly limited and varies depending on the size of the joining device, but is preferably 0.0001 mm to 1 mm, more preferably 0.001 mm to 0.8 mm, and even more preferably 0.01 mm to 0.5 mm. Note that the axial direction is not necessarily limited to the vertical direction and can be determined by the arrangement of the workpieces and the pin portion.

[0026] (6) The friction stirring rotating member according to any one of (1) to (5), wherein the pin portion is configured to be free or substantially free relative to the output shaft within the range of play.

[0027] In the friction stirring rotating member (6), the pin portion is free or substantially free within the range of play, so that vibration of the pin portion occurs passively upon contact with the workpieces undergoing plastic flow, and has a larger amplitude and / or frequency than the base vibration. This vibration is less likely to interfere with the plastic flow of the workpieces. Furthermore, this vibration can amplify the plastic flow of the workpieces. This vibration enables high-strength joining while suppressing the occurrence of joining defects.

[0028] "Free" refers to a state in which there is no physical or mechanical constraint. "Substantially free" refers to a state in which the amplitude and / or frequency of the vibration of the pin portion during friction stirring is greater than the vibration of the output shaft, and within that range, constraint of the tip portion relative to the output shaft is permitted. The constraint is, for example, friction between adjacent members between the output shaft and the pin portion, or external stress caused by an elastic body or liquid, which will be described later.

[0029] (7) The friction stirring rotating member according to any one of (1) to (6), wherein the play is a gap or substantially a gap.

[0030] In the friction stirring rotating member of (7), the play is a gap or substantially a gap, so that the vibration of the pin portion occurs passively upon contact with the workpieces undergoing plastic flow, and has a larger amplitude and / or frequency than the base vibration. This vibration is less likely to interfere with the plastic flow of the workpieces. Furthermore, this vibration can amplify the plastic flow of the workpieces. This vibration enables high-strength joining while suppressing the occurrence of joining defects.

[0031] The gap is the space between the output shaft and the pin. "Substantially in the gap" means that the pin may have a liquid or an elastic body therein to the extent that the amplitude and / or frequency of the vibration of the pin during friction stirring can be made larger than the vibration of the output shaft.

[0032] (8) A joining device for friction stir welding of workpieces, the joining device comprising: a drive mechanism having an output shaft and configured to rotate the output shaft; and a pin portion configured to rotate by rotation transmitted from the drive mechanism and inserted into the workpieces during friction stirring, the pin portion having play between the output shaft and the pin portion to enable vibration of the pin portion relative to the output shaft, and configured such that vibration of the pin portion has a larger amplitude and / or frequency than vibration of the output shaft due to the play during friction stirring.

[0033] The joining device (8) has play between the output shaft and the pin portion, which allows the pin portion to vibrate relative to the output shaft. The joining device is configured so that the play causes the vibration of the pin portion to have a larger amplitude and / or frequency than the vibration of the output shaft during friction stirring. The output shaft vibrates in conjunction with the transmission of rotation from the drive mechanism during friction stirring. This vibration is similar to the base vibration described above. During friction stirring, the vibration of the pin portion has a larger amplitude and / or frequency than the base vibration. This vibration is generated by the play. This vibration is not generated by output from a drive source other than the drive mechanism. This vibration is unlikely to interfere with the plastic flow of the members to be joined. Furthermore, this vibration can amplify the plastic flow of the members to be joined. Therefore, high-strength joining can be performed while suppressing the occurrence of joining defects.

[0034] (9) A joining method for friction stir welding of workpieces by rotating a pin portion using rotation output from a drive mechanism and inserting the pin portion into workpieces, wherein, during friction stirring, vibrations having amplitudes and / or frequencies greater than base vibrations transmitted from the drive mechanism to the pin portion due to rotation of the drive mechanism are passively generated in the pin portion by contact with the workpieces undergoing plastic flow, and friction stirring is performed on the workpieces.

[0035] According to the joining method (9), the vibration of the pin portion is passively generated by contact with the workpieces undergoing plastic flow, and has a vibration and / or frequency greater than that of the base vibration. This vibration is less likely to interfere with the plastic flow of the workpieces. Furthermore, this vibration can amplify the plastic flow of the workpieces. This vibration enables high-strength joining while suppressing the occurrence of joining defects.

[0036] (10) A joining method for friction stir welding of workpieces by inserting a pin into workpieces while rotating the pin with rotation output from a drive mechanism, wherein the drive mechanism is feedback controlled so that the output of the drive mechanism changes in synchronization with or following the rotational fluctuation of the pin that occurs passively due to contact with the workpieces undergoing plastic flow, and friction stir welding is performed on the workpieces.

[0037] According to the joining method (10), the vibration of the pin is controlled by the drive mechanism so as to suppress or prevent the pin vibration from interfering with the plastic flow of the workpieces. This allows for freer plastic flow. Therefore, high-strength joining can be achieved while suppressing the occurrence of joining defects.

[0038] According to the present invention, it is possible to provide a friction stir rotating member, a welding device, and a welding method that enable high-strength welding while suppressing the occurrence of welding defects.

[0039] Fig. 1(a) is a cross-sectional view schematically showing a friction stirring rotating member according to one embodiment, and Fig. 1(b) is a cross-sectional view taken along line A-A thereof. Fig. 2(a) is a cross-sectional view schematically showing a pin portion and its vicinity of the friction stirring rotating member shown in Fig. 1(a), and Fig. 2(b) is a cross-sectional view schematically showing a pin portion and its vicinity of a rotary tool according to a comparative example. Figs. 3(a) to 3(t) are each a cross-sectional view schematically showing friction stirring rotating members according to modified examples.

[0040] FIG. 1( a) is a cross-sectional view schematically illustrating a friction stirring rotating member 1 according to one embodiment. FIG. 1( b) is a cross-sectional view taken along line A-A. In the figure, H, C, and T represent a holder, a collet, and a tool, respectively. AD, CD, and RD represent the axial direction, the circumferential direction, and the radial direction, respectively. These symbols may be omitted in other drawings, but are interpreted in the same manner as in this figure. Furthermore, in each figure, when adjacent members of the friction stirring rotating member 1 are hatched identically, this indicates that the members are fixed to each other. On the other hand, when different members are hatched differently, this indicates that the members are not fixed to each other. Furthermore, in each figure, the same components are designated by the same symbols.

[0041] The friction stirring rotating member 1 is provided in a joining device 3. The joining device 3 is a device that performs friction stir welding of workpieces 2. The joining device 3 has a drive mechanism 4. The friction stirring rotating member 1 is detachably attached to an output shaft 5 of the drive mechanism 4. The friction stirring rotating member 1 rotates together with the output shaft 5 so as not to be displaced relative to the output shaft 5.

[0042] The friction stirring rotating member 1 includes a metallic rotating shaft portion 10 and a metallic tip portion 20. The rotating shaft portion 10 corresponds to the holder H. The rotating shaft portion 10 has a generally cylindrical shape extending in the axial direction AD. The upper surface side of the rotating shaft portion 10 is fixed to the output shaft 5. The rotating shaft portion 10 has a bottomed hole on the lower surface of the rotating shaft portion 10 for receiving the tip portion 20. The bottomed hole is open downward. The tip portion 20 is provided within the bottomed hole.

[0043] The tip portion 20 has a pin portion 21 and a base end portion 22 provided on the base end side of the pin portion 21. The pin portion 21 corresponds to the tool T. The base end portion 22 corresponds to the collet C. The base end portion 22 has a generally cylindrical shape extending in the axial direction AD. The base end portion 22 has a bottomed hole on its underside for receiving the pin portion 21. The bottomed hole opens downward. The pin portion 21 is provided within the bottomed hole. The pin portion 21 is fixed to the base end portion 22 so as not to be displaced relative to the base end portion 22. The tip of the pin portion 21 is inserted into the workpiece 2 during friction stir welding, as shown in FIG. 1( a). In the figure, PF schematically indicates a plastic flow portion of the workpiece 2 during friction stir welding.

[0044] As shown in FIG. 1B , a plurality of grooves 25 are formed on the outer peripheral surface of the tip portion 20 at intervals in the circumferential direction CD. As shown in FIG. 1A , the grooves 25 are formed to extend in the axial direction AD. A rod-shaped metal fitting key 30 is provided in each groove 25. The inner portion of the fitting key 30 in the radial direction RD is recessed into the groove 25. The outer portion of the fitting key 30 in the radial direction RD is exposed outside the groove 25 in the radial direction RD. Grooves 15 are formed on the inner peripheral surface of the rotating shaft portion 10 at positions corresponding to the exposed portions of each fitting key 30. The length of the groove 15 in the circumferential direction CD is greater than the length of the fitting key 30 in the circumferential direction CD. Therefore, a play CP in the circumferential direction CD is generated within the groove 15. The play CP is provided between the rotating shaft portion 10 and the tip portion 20. The rotating shaft portion 10 is fixed to the output shaft 5, and the tip portion 20 includes a pin portion 21. Therefore, a play CP is provided between the output shaft 5 and the pin portion 21. The play CP is a gap or a substantial gap. The pin portion 21 is free or substantially free relative to the output shaft 5 within the range of the play CP. As shown in FIG. 1(b), the tip portion 20 is configured such that the play CP causes vibration CV in the circumferential direction CD relative to the rotating shaft portion 10 during friction stirring.

[0045] Furthermore, the friction stirring rotating member 1 has a play AP in the axial direction AD between the rotating shaft portion 10 and the tip portion 20. In other words, the play AP is provided between the output shaft 5 and the pin portion 21. The play AP is a gap or a substantial gap. The pin portion 21 is free or substantially free with respect to the output shaft 5 within the range of the play AP. As shown in FIG. 1( a), the pin portion 21 is configured such that, due to the play AP, vibration AV is generated in the axial direction AD with respect to the output shaft 5 during friction stirring.

[0046] FIG. 2(a) is a cross-sectional view that schematically shows the pin portion 21 and its vicinity of the friction stirring rotating member 1 shown in FIG. 1(a).

[0047] The vibrations AV and CV of the pin portion 21 have a larger amplitude and / or frequency than those of the output shaft 5 (see FIG. 1(a)). The two-dot chain line in FIG. 2(a) shows the pin portion 21 when the vibrations AV and CV are occurring within the plastic flow portion PF.

[0048] Region Q is the region within the workpieces 2 that is affected by the vibrations AV and CV of the pin portion 21. That is, in region Q, the rotation of the pin portion 21 causes plastic flow in the workpieces 2. The pin portion 21 then comes into contact with the workpieces 2, which are undergoing plastic flow, within the range of the play AP and CP. The pin portion 21 is free or substantially free within the range of the play AP and CP. Therefore, passive vibrations AV and CV are generated in the pin portion 21. Because the vibrations AV and CV of the pin portion 21 are passive, they are not only unlikely to interfere with the plastic flow of the workpieces 2, but can also synchronize with and amplify the plastic flow.

[0049] The pin portion 21 has a surface contact portion 24 at a height where it comes into contact with the surface of the workpiece 2. The ratio (diameter SD / diameter PD) of the diameter SD of the surface contact portion 24 to the diameter PD of the pin portion 21 located directly below the surface contact portion 24 (the pin portion 21 that is closer to the tip of the surface contact portion 24 and adjacent to the surface contact portion 24) is 1.8 or less. As a result, the pin portion 21 has a shoulder 23 that is narrow enough to satisfy the ratio (diameter SD / diameter PD) ≦ 1.8.

[0050] Region P is a region near the surface of the workpieces 2. The pin portion 21 has a narrow shoulder 23, which makes it less likely that the shoulder 23 will impede plastic flow. The effect of the vibrations AV and CV of the pin portion 21 (the effect of not impeding plastic flow and amplifying it) can be more effectively achieved. Because the width of the shoulder 23 is small, the amount of heat generated during friction stirring is reduced, but the effect of the vibrations AV and CV of the pin portion 21 makes it possible to achieve effective plastic flow. As a result, friction stir welding can be performed at a lower temperature. In other words, because the width of the shoulder 23 is small, the shoulder 23 is less likely to impede plastic flow, and more amplified plastic flow can be achieved in region P.

[0051] 2B is a cross-sectional view schematically showing a pin portion and its vicinity of a rotary tool 1′ according to a comparative example (prior art). The techniques disclosed in Patent Documents 1 to 3 correspond to this comparative example (prior art).

[0052] During friction stirring, the rotary tool 1' is biased downward by an elastic member (not shown). In the figure, F represents a biasing force. The biasing force F presses the rotary tool 1' against the workpieces 2', maintaining a constant insertion amount of the rotary tool 1' into the workpieces 2' within the plastic flow region PF'. The pin portion 21' does not generate vibrations AV and CV as shown in FIG. 2(a). Region Q' corresponds to region Q in FIG. 2(a). In region Q', even though the workpieces 2' undergo plastic flow around the pin portion 21', the pin portion 21' is biased downward by the biasing force F and remains in its position. As a result, the stationary pin portion 21' may hinder the plastic flow of the workpieces 2. Furthermore, the stationary pin portion 21' does not have the effect of amplifying the plastic flow of the workpieces 2.

[0053] In the rotary tool 1', the ratio (diameter SD' / PD') is 2 or more. The pin portion 21' has a wide shoulder 23'. In addition, the shoulder 23' is urged downward by the urging force F and pressed against the workpieces 2'. Therefore, in the region P', the shoulder 23' hinders plastic flow. Furthermore, because the width of the shoulder 23' is large, a large amount of heat is generated during friction stir welding, making it difficult to perform friction stir welding at low temperatures.

[0054] Figures 3(a) to 3(t) are schematic cross-sectional views of friction stirring rotating members 1 according to modified examples. The letters H, C, and T in Figures 3(a), 3(s), and 3(t) indicate a holder, a collet, and a tool, respectively. For convenience, the letters H, C, and T are omitted in Figures 3(b) to 3(r), but are the same as in Figures 3(a), 3(s), and 3(t).

[0055] [FIG. 3(a)] The frictional stirring rotating member 1 shown in FIG. 3(a) corresponds to the tool T as a whole, with the rotating shaft portion 10 corresponding to a part of the tool T and the tip portion 20 corresponding to a part of the tool T. The tip portion 20 has an integrally formed base end side portion 22 and pin portion 21. The tip portion 20 is attached to the rotating shaft portion 10 by being inserted into a bottomed hole provided on the underside of the rotating shaft portion 10. The underside of the rotating shaft portion 10 forms a shoulder 23. As shown in FIGS. 1(a) and 1(b), a fitting key 30 is provided between the rotating shaft portion 10 and the tip portion 20. As a result, the frictional stirring rotating member 1 has play AP and CP between the rotating shaft portion 10 and the tip portion 20. The frictional stirring rotating member 1 is attached to a collet C. A holder H and a collet C are fixedly provided on the output shaft 5, and the friction stirring rotating member 1 is provided on the output shaft 5 via the holder H and the collet C.

[0056] [Fig. 3(b)] The friction stirring rotating member 1 shown in Fig. 3(b) corresponds to the collet C and the tool T, the rotating shaft portion 10 corresponds to the collet C and a part of the tool T, and the tip portion 20 corresponds to a part of the tool T. The friction stirring rotating member 1 is attached to the output shaft 5 via a holder H. Except for this point, the embodiment in Fig. 3(b) is the same as Fig. 3(a).

[0057] [Fig. 3(c)] The friction stirring rotating member 1 shown in Fig. 3(c) corresponds to the holder H, collet C, and tool T, the rotating shaft portion 10 corresponds to the holder H, collet C, and part of the tool T, and the tip portion 20 corresponds to part of the tool T. The friction stirring rotating member 1 is provided on an output shaft 5. Except for this point, the embodiment in Fig. 3(c) is the same as Fig. 3(a) and Fig. 3(b).

[0058] [FIG. 3(d)] The frictional stirring rotating member 1 shown in FIG. 3(d) has a rotating shaft 10, an intermediate body 40, and a tip portion 20. The frictional stirring rotating member 1 corresponds to the collet C and the tool T. The rotating shaft 10 corresponds to the collet C. The intermediate body 40 corresponds to a part of the tool T. The tip portion 20 corresponds to a part of the tool T. The tip portion 20 is attached to the intermediate body 40 by being inserted into a bottomed hole provided on the underside of the approximately cylindrical intermediate body 40. The underside of the intermediate body 40 forms a shoulder 23. A fitting key 30 is provided between the intermediate body 40 and the tip portion 20. However, in the example shown in FIG. 3(d), the fitting key 30 provides play CP but not play AP. The tip portion 20 can vibrate in the circumferential direction CD (see FIG. 1) relative to the intermediate body 40. The intermediate body 40 is attached to the rotating shaft portion 10 by being inserted into a bottomed hole provided on the underside of the rotating shaft portion 10. This provides play AP between the rotating shaft portion 10 and the intermediate body 40. The intermediate body 40 is vibrable in the axial direction AD (see FIG. 1 ) relative to the rotating shaft portion 10. In this way, the play AP, CP provided between the rotating shaft portion 10 and the tip portion 20 does not necessarily have to be formed by the rotating shaft portion 10 and the tip portion 20. An intermediate body 40 that can be individually displaced relative to each of the rotating shaft portion 10 and the tip portion 20 may be interposed between the rotating shaft portion 10 and the tip portion 20. In this way, the friction stirring rotating member 1 as a whole has play AP, CP between the rotating shaft portion 10 and the tip portion 20.

[0059] [Fig. 3(e)] The friction stirring rotating member 1 shown in Fig. 3(e) has a rotating shaft portion 10, an intermediate body 40, and a tip portion 20, similar to Fig. 3(d). The friction stirring rotating member 1 corresponds to the holder H, the collet C, and the tool T. The rotating shaft portion 10 corresponds to the holder H. The intermediate body 40 corresponds to the collet C and part of the tool T. The tip portion 20 corresponds to part of the tool T. In the embodiment of Fig. 3(e), the position of the play AP differs from that of Fig. 3(d).

[0060] [Fig. 3(f)] In the embodiment of Fig. 3(f), the friction stirring rotating member 1 corresponds to the holder H, the collet C, and the tool T. The rotating shaft portion 10 corresponds to the holder H. The intermediate body 40 corresponds to the collet C. The tip portion 20 corresponds to the tool T. A fitting key 30 is provided between the intermediate body 40 and the tip portion 20, thereby providing a play CP between the intermediate body 40 and the tip portion 20. A play AP is provided between the rotating shaft portion 10 and the intermediate body 40.

[0061] [Fig. 3(g)] In the embodiment of Fig. 3(g), unlike Fig. 3(f), a fitting key 30 is provided between the rotating shaft portion 10 and the intermediate body 40, thereby providing play CP between the rotating shaft portion 10 and the intermediate body 40. Play AP is provided between the intermediate body 40 and the tip portion 20.

[0062] [Fig. 3(h)] In the embodiment of Fig. 3(h), the width of the shoulder 23 is wider than that of Fig. 1. The ratio is 2 or more. Because the shoulder 23 is integral with the pin portion 21, the shoulder 23 also generates vibrations similar to those of the pin portion 21. Therefore, even if the width of the shoulder 23 is wide, it is difficult to hinder the plastic flow of the workpieces 2, and it is possible to amplify the plastic flow. In this respect, the embodiment of Fig. 3(h) differs from the comparative example shown in Fig. 2(b). As mentioned above, the shoulder 23 may be separate from the pin portion 21 and configured not to rotate together with the pin portion 21.

[0063] [FIGS. 3(i) and 3(j)] The shapes of the tips of the pin portions 21 in the embodiments of FIG. 3(i) and FIG. 3(j) are different from those in FIG. 1. The tips of the pin portions 21 in FIG. 1 have a tapered truncated cone shape (a truncated cone shape in which the tip side is thinner than the base end side), whereas the tips of the pin portions 21 in FIG. 3(i) have a tapered inverted truncated cone shape (a truncated cone shape in which the tip side is thicker than the base end side). The tips of the pin portions 21 in FIG. 3(j) have a cylindrical shape. As such, the shape of the tips of the pin portions 21 is not particularly limited. Various shapes can be adopted as the shape of the pin portions 21.

[0064] [Fig. 3(k)] In the embodiment of Fig. 3(k), the ratio is 1.0, and the friction stir rotating member 1 does not have a shoulder. Because this friction stir rotating member 1 does not have a rotating shoulder, friction stir welding can be achieved at a lower temperature.

[0065] [Figures 3(l) and 3(m)] In the embodiment of Figure 3(l), unlike Figure 1, the frictional stirring rotating member 1 has only play AP in the axial direction AD (see Figure 1). In addition, in the embodiment of Figure 3(m), the frictional stirring rotating member 1 has only play CP in the circumferential direction CD (see Figure 1). In this way, the frictional stirring rotating member 1 may have play in only one direction among the axial direction AD, the circumferential direction CD, and the radial direction RD.

[0066] [FIG. 3(n)] In the embodiment of FIG. 3(n), the friction stirring rotating member 1 corresponds to the collet C and the tool T. The rotating shaft portion 10 corresponds to the collet C. The tip portion 20 corresponds to the tool T. The tip portion 20 has a pin portion 21 and a base end portion 22 that are integrally formed with each other. The tip portion 20 is attached to the rotating shaft portion 10 by being loosely fitted into a large-diameter, bottomed hole 17 provided on the underside of the rotating shaft portion 10. Because the diameter of the large-diameter, bottomed hole 17 is larger than the diameter of the base end portion 22, play RP in the radial direction RD (see FIG. 1) is provided around the base end portion 22. A fixed key 31 is fixed to the outer surface of the base end portion 22. A lateral through-hole 16 is provided in the rotating shaft portion 10 at a position corresponding to the fixed key 31. The lateral through-hole 16 provides play CP as well as play RP. That is, the tip portion 20 has play CP and play RP between it and the rotating shaft portion 10. The tip portion 20 is vibrable relative to the rotating shaft portion 10 in the circumferential direction CD and the radial direction RD.

[0067] [FIG. 3(o)] In the embodiment shown in FIG. 3(o), the friction stirring rotating member 1 has a rotating shaft portion 10, an intermediate body 40, and a tip portion 20. The friction stirring rotating member 1 corresponds to the holder H, collet C, and tool T. The rotating shaft portion 10 corresponds to the holder H. The intermediate body 40 corresponds to the collet C. The tip portion 20 corresponds to the tool T. The tip portion 20 has a pin portion 21 and a base end portion 22 that are integrally formed with each other. The tip portion 20 is attached to the intermediate body 40 by loosely fitting into a large-diameter, bottomed hole 17 provided on the underside of the intermediate body 40. Because the diameter of the large-diameter, bottomed hole 17 is larger than the diameter of the base end portion 22, play RP in the radial direction RD (see FIG. 1) is provided around the periphery of the base end portion 22. A fixing key 31 is fixed to the outer surface of the base end portion 22. A lateral through-hole 16 is provided in the intermediate body 40 at a position corresponding to the fixed key 31. The lateral through-hole 16 provides a play CP as well as a play RP. That is, the tip portion 20 has a play CP and a play RP between it and the intermediate body 40. The tip portion 20 can vibrate in the circumferential direction CD and the radial direction RD relative to the intermediate body 40. The intermediate body 40 is attached to the rotating shaft portion 10 by being inserted into a bottomed hole provided on the underside of the rotating shaft portion 10. This provides a play AP between the rotating shaft portion 10 and the intermediate body 40. The intermediate body 40 can vibrate in the axial direction AD (see FIG. 1 ) relative to the rotating shaft portion 10. As described above, the friction stirring rotating member 1 has play AP, CP, and RP between the rotating shaft portion 10 and the tip portion 20. Therefore, the tip portion 20 can vibrate in all directions, including the axial direction AD, the circumferential direction CD, and the radial direction RD, relative to the rotating shaft portion 10.

[0068] [Fig. 3(p)] In the embodiment of Fig. 3(p), unlike the embodiment of Fig. 1, the play AP, CP are not gaps, but are filled with a liquid 41 (e.g., lubricating oil). Such a friction-stirring rotating member 1 can also achieve the vibration of the pin portion 21 as described using Fig. 2(a), and is clearly different from the embodiment of Fig. 2(b). In other words, the play AP, CP are essentially gaps. The tip portion 20 is essentially free within the range of the play AP, CP.

[0069] [Fig. 3(q)] In the embodiment of Fig. 3(q), compared to the embodiment of Fig. 1, an elastic body 42 (e.g., an O-ring) is provided in the play AP between the rotating shaft portion 10 and the tip portion 20. Such a friction stirring rotating member 1 can also achieve vibration of the pin portion 21 as described using Fig. 2(a), and is clearly different from the embodiment of Fig. 2(b). In other words, the play AP, CP are essentially gaps. The tip portion 20 is essentially free within the range of the play AP, CP.

[0070] In the above example, a description has been given of a case in which the friction stirring rotating member 1 has a rotating shaft portion 10 and a tip portion 20, there is play between the rotating shaft portion 10 and the tip portion 20, and the tip portion 20 includes a pin portion 21. However, the friction stirring rotating member 1 is not limited to the above example, and the following aspects can be adopted, for example.

[0071] [Fig. 3(r)] In the embodiment of Fig. 3(r), the frictional stirring rotating member 1 corresponds to the collet C and the tool T. The frictional stirring rotating member 1 is configured as a single unit as a whole, and has a pin portion 21 and a shoulder 23. The frictional stirring rotating member 1 is configured to be attached to a holder H, thereby generating play AP between the frictional stirring rotating member 1 and the holder H. Due to the play AP, the frictional stirring rotating member 1 including the pin portion 21 vibrates in the axial direction AD relative to the output shaft 5 during frictional stirring.

[0072] [FIG. 3(s)] In the embodiment of FIG. 3(s), the frictional stirring rotating member 1 corresponds to the holder H. The frictional stirring rotating member 1 has a bottomed hole on its underside into which the collet C and tool T are inserted. The collet C and tool T are detachably attached to the frictional stirring rotating member 1 by inserting the collet C and tool T into the bottomed hole. The frictional stirring rotating member 1 does not have a pin portion. The pin portion is included in the tool T. The frictional stirring rotating member 1 has a bottomed hole on its upper surface for receiving an output shaft 5. The output shaft 5 is inserted into the bottomed hole, and the frictional stirring rotating member 1 is attached to the output shaft 5. The frictional stirring rotating member 1 is configured to generate play AP between the output shaft 5 and the frictional stirring rotating member 1 when attached to the output shaft 5. As a result, play AP is generated between the output shaft 5 and the pin portion of the tool T during frictional stirring. The play AP allows the pin portion to vibrate relative to the output shaft 5.

[0073] [FIG. 3(t)] In the embodiment shown in FIG. 3(t), the frictional stirring rotating member 1 has a rotating shaft portion 10 and a tip portion 20. The frictional stirring rotating member 1 corresponds to the holder H. The rotating shaft portion 10 is the upper portion of the holder H and is attached to the output shaft 5. The tip portion 20 is the lower portion of the holder H and is configured to rotate by rotation transmitted from the rotating shaft portion 10 and is located more distal than the rotating shaft portion 10. The tip portion 20 is configured to detachably attach a collet C and a tool T. That is, the tip portion 20 does not have a pin portion, but has a base end portion 22 configured to detachably attach a pin portion. Plays AP and CP are provided between the rotating shaft portion 10 and the tip portion 20 to allow vibration of the pin portion relative to the rotating shaft portion 10. Note that the frictional stirring rotating member 1 is not limited to the above example. The friction stirring rotating member 1 only needs to be configured so as to create play between the output shaft 5 and the pin portion 21 when attached to the output shaft 5, and does not necessarily have to be based on the distinction between the parts of the holder H, collet C, and tool T.

[0074] 1( a) and 1(b) , a welding device 3 including a friction stirring rotating member 1 is shown. The welding device 3 includes a drive mechanism 4 including an output shaft 5 and a pin portion 21. The pin portion 21 has play AP and CP between the output shaft 5 and the pin portion 21, which enable vibration AV and CV of the pin portion 21 relative to the output shaft 5. Due to the play AP and CP, the welding device 3 has vibrations AV and CV of the pin portion 21 during friction stirring that have a larger amplitude and / or frequency than the vibration (base vibration) of the output shaft 5. While the welding device 3 of this embodiment includes a friction stirring rotating member 1 having play AP and CP, the welding device 3 does not necessarily need to include a friction stirring rotating member 1 as long as there is play between the output shaft 5 and the pin portion 21.

[0075] 1( a) and 1(b) , which can be performed by the above-described welding apparatus 3. In this welding method, the pin portion 21 is rotated by rotation output from the drive mechanism 4, and the pin portion 21 is inserted into the workpieces 2, thereby performing friction stir welding of the workpieces 2. In this welding method, friction stir welding is performed on the workpieces 2 in a state in which vibrations having a larger amplitude and / or frequency than base vibrations transmitted from the drive mechanism 4 to the pin portion 21 by the rotation of the drive mechanism 4 are passively generated in the pin portion 21 by contact with the workpieces 2 that are undergoing plastic flow during friction stir welding.

[0076] In a welding method according to another embodiment, the pin portion 21 is inserted into the workpieces 2 while being rotated by rotation output from the drive mechanism 4, thereby performing friction stir welding of the workpieces 2. In this welding method, friction stir welding is performed on the workpieces 2 while feedback controlling the drive mechanism 4 so that the output of the drive mechanism 4 changes in synchronization with or following the rotational fluctuation of the pin portion 21 that occurs passively due to contact with the workpieces 2 that undergo plastic flow. The rotational fluctuation can be detected by a conventionally known rotational speed sensor such as a resolver or encoder.

[0077] Furthermore, the numerical values, materials, structures, shapes, etc. described in the above-described embodiments are merely examples, and different numerical values, materials, structures, shapes, etc. may be used as necessary. Furthermore, in the above-described embodiments, the friction stirring rotating member 1 is located on top, the workpieces 2 are located on the bottom, and the friction stirring rotating member 1 and the workpieces 2 face each other in the vertical direction. That is, the axial direction is the same as the vertical direction. However, the axial direction does not necessarily have to be the same as the vertical direction. The axial direction is not particularly limited and may be, for example, horizontal. Furthermore, when the axial direction is the vertical direction, the friction stirring rotating member may be located on the bottom and the workpieces to be welded may be located on the top. Furthermore, the axial direction does not necessarily have to be fixed. When a joining device is configured by installing a friction stirring rotating member in the above-described portable device, the axial direction may change during operation.

[0078] Friction stirring rotating member: 1 Workpiece to be joined: 2 Joining device: 3 Drive mechanism: 4 Output shaft (of drive mechanism): 5 Rotating shaft portion: 10 Groove: 15 Lateral through-hole: 16 Large diameter bottomed hole: 17 Tip portion: 20 Pin portion: 21 Base end side portion: 22 Shoulder: 23 Surface contact portion: 24 Groove: 25 Fitting key: 30 Fixed key: 31 Intermediate body: 40 Liquid: 41 Elastic body: 42

Claims

1. A friction stirring rotating member provided in a joining device for friction stir welding of workpieces, wherein the friction stirring rotating member, when provided on an output shaft of a drive mechanism provided in the joining device so as to rotate by rotation output from the drive mechanism, generates play between the output shaft and a pin portion inserted into the workpieces during friction stirring, which allows the pin portion to vibrate relative to the output shaft, and the play causes the vibration of the pin portion to have a larger amplitude and / or frequency than the vibration of the output shaft during friction stirring.

2. The frictional stirring rotating member according to claim 1, comprising: a rotating shaft portion provided on the output shaft; and a tip portion configured to rotate by rotation transmitted from the rotating shaft portion and located further tip than the rotating shaft portion, the tip portion having the pin portion and a base end side provided on the base end side of the pin portion, or having a base end side portion not having the pin portion but configured to allow the pin portion to be detachably attached, the play being provided between the rotating shaft portion and the tip portion so as to enable vibration of the pin portion relative to the rotating shaft portion, the frictional stirring rotating member being configured such that, due to the play, vibration of the pin portion during frictional stirring has a larger amplitude and / or frequency than vibration of the rotating shaft portion.

3. A friction stirring rotating member as described in claim 2, wherein the pin portion has a surface contact portion at a height where it contacts the surface of the workpiece, and the ratio of the diameter of the surface contact portion to the diameter of the pin portion adjacent to the surface contact portion closer to the tip than the surface contact portion is 1.8 or less, whereby the pin portion is configured to have a shoulder with a width small enough to satisfy the ratio, or to have no shoulder.

4. The friction stirring rotating member according to any one of claims 1 to 3, wherein the vibration of the pin portion is generated passively by contact with the joined members undergoing plastic flow within the range of play.

5. The friction stirring rotating member according to any one of claims 1 to 4, wherein the friction stirring rotating member is configured so that vibration of the pin portion occurs in at least one of the axial direction, circumferential direction and radial direction of the pin portion due to the play.

6. The friction stirring rotating member according to any one of claims 1 to 5, wherein the pin portion is configured to be free or substantially free relative to the output shaft within the range of play.

7. The friction stirring rotating member according to any one of claims 1 to 6, wherein the play is a gap or substantially a gap.

8. A joining device for friction stir welding of workpieces, comprising: a drive mechanism having an output shaft and configured to rotate the output shaft; and a pin portion configured to rotate by rotation transmitted from the drive mechanism and inserted into the workpieces during friction stirring, the pin portion having play between the output shaft and the pin portion to enable vibration of the pin portion relative to the output shaft, the play being configured so that vibration of the pin portion during friction stirring has a larger amplitude and / or frequency than vibration of the output shaft.

9. A joining method in which a pin portion is rotated by the rotation output from a drive mechanism and the pin portion is inserted into the workpiece to perform friction stir welding of the workpieces, wherein during friction stirring, friction stirring is performed on the workpieces in a state in which vibrations having a larger amplitude and / or frequency than a base vibration transmitted to the pin portion from the drive mechanism by the rotation of the drive mechanism are passively generated in the pin portion by contact with the workpieces undergoing plastic flow.

10. A joining method in which a pin portion is rotated by rotation output from a drive mechanism and the pin portion is inserted into the workpiece to perform friction stir welding of the workpieces, wherein the friction stir is performed on the workpieces while performing feedback control of the drive mechanism so that the output of the drive mechanism changes in synchronization with or following the rotational fluctuation of the pin portion that occurs passively due to contact with the workpieces undergoing plastic flow.

Images