Method for manufacturing filet-joined component by using synchronous stir-joining, and synchronous stir-joining device for filet joining

Abstract

The present invention makes it possible to stably perform filet joining while easily and quickly suppressing roughness and disorder in a plastic flow part without requiring an auxiliary tool and with few constraints on joining conditions. This method for manufacturing a filet-joined component is characterized by including a filet joining step for filet-joining two members to be joined, and is characterized in that: the filet joining step is performed by a synchronous stir-joining device; the synchronous stir-joining device is provided with an output shaft, a driving mechanism configured to cause the output shaft to rotate, and a pin portion that is provided to the distal-end side of the output shaft, is configured to rotate due to rotation transmitted from the driving mechanism, and is inserted into the two members to be joined during synchronous stirring; the pin part has play between the output shaft and the pin part, the play enabling vibration of the pin part with respect to the output shaft; the play is a gap or substantially is a gap; the play is configured such that the pin part is free or substantially free with respect to the output shaft within the range of play; and in the filet joining step, the rotating pin part is inserted into the two members to be joined at an inner corner of a corner formed by the two members to be joined, thereby performing filet joining by synchronous stir-joining.

Description

Method for manufacturing parts that have been fillet welded by synchronous stir welding, and synchronous stir welding device for fillet welding

[0001] The present invention relates to synchronous stir welding (SSW), and more particularly to a method for manufacturing a part fillet welded by synchronous stir welding, and a synchronous stir welding apparatus for fillet welding.

[0002] Patent Documents 1 to 5 all relate to fillet welding using friction stir welding (FSW).

[0003] Patent Document 1 relates to a friction stir welding probe for preventing irregularities and defects that occur in fillet welding. A presser block shaped like an inverted isosceles triangular prism, a probe body, and a stir pin are used to perform friction stir welding on the fillet of the workpiece. The presser block supports the stir pin and also applies pressure to the plastic flow portion to prevent irregularities and deformation in the plastic flow portion.

[0004] Patent Document 2 relates to a tool for friction stir welding fillet portions of a pair of metal members. The tool is composed of a stir pin and a base block. The base block has a narrow body and a detachable shoulder. This structure allows for efficient replacement of worn parts of the tool, reducing overall costs. Similar to the presser block in Patent Document 1, the base block supports the stir pin and applies pressure to the plastic flow portion.

[0005] Patent Document 3 relates to a friction stir welding tool for performing fillet welding using friction stir welding. The friction stir welding tool includes a friction stir rotor and a friction stir stator. The friction stir rotor includes a friction stir probe and a friction stir main body. The friction stir rotor further includes a shoulder that connects the friction stir probe and the friction stir main body and slopes outward from the center of the friction stir main body 12. During friction stir welding, the rotating friction stir probe is pressed into the workpieces to stir the workpieces. The rotating shoulder is exposed through a slit in the friction stir stator and abuts against the workpieces to stir the workpieces. The friction stir stator is configured to stabilize the weld by applying pressure to the plastic flow portion. Both sides of the slit (i.e., both sides of the line contact position between the shoulder and the workpieces in the circumferential direction of the shoulder) are covered by the friction stir stator and spatially closed. The friction stir stator also stabilizes the weld by applying pressure to the plastic flow portion on both sides of the slit.

[0006] Patent Document 4 relates to a friction stir welding apparatus for performing friction stir welding on fillet portions. The friction stir welding apparatus is configured to perform friction stir welding with a stir shaft while applying pressure to a plastic flow portion with a fixed shoulder.

[0007] Patent Document 5 relates to a technique for friction stir welding a T-shaped structure. The T-shaped structure is constructed by butting a second workpiece against a first workpiece. The T-shaped structure has a first fillet and a second fillet on either side of the second workpiece. In this technique, the softened material on the first fillet side is supported by a fixed shoulder, so that the second workpiece is welded to the first workpiece while maintaining the shape of the fillet at the first fillet. Meanwhile, a pressure roller is pressed against the second fillet. This maintains the shape of the fillet at the second fillet.

[0008] As described above, the presser block in Patent Document 1, the base block in Patent Document 2, the friction stir stator in Patent Document 3, the fixed shoulder in Patent Document 4, and the fixed shoulder in Patent Document 5 are auxiliary tools dedicated to fillet welding by friction stir welding. This auxiliary tool is configured to move along the fillet portion together with the stirring pin to apply pressure by coming into contact with the friction stir welded joint when the rotating stirring pin moves along the fillet portion to perform friction stir welding on the fillet portion.

[0009] Japanese Patent Laid-Open No. 11-320128 Japanese Patent Laid-Open No. 2011-79031 Japanese Patent Laid-Open No. 2011-206786 Japanese Patent Laid-Open No. 2013-166159 Japanese Patent Laid-Open No. 2020-131256

[0010] The present invention aims to provide a method and apparatus that does not require auxiliary tools, is less subject to joining conditions, and enables stable fillet joining to be performed simply and quickly while suppressing roughness and disorder in the plastic flow zone.

[0011] The present inventors have conducted extensive research in light of the above-mentioned problems and have obtained the following findings.

[0012] In the past, in fillet joining using friction stir welding, joining methods have been developed with the idea of ​​using the above-mentioned auxiliary tool to suppress roughness and irregularities on the surface of the plastic flow zone. However, because the auxiliary tool moves while applying pressure to the plastic flow zone, there was a problem that drag marks, also known as galling, inevitably occurred in the plastic flow zone. Therefore, the auxiliary tool had to be designed to minimize the occurrence of galling. Specifically, the auxiliary tool had to be designed according to the shape and material of the joined parts, the shape of the inner corner, etc., resulting in the problem of requiring dedicated equipment such as the above-mentioned auxiliary tool.

[0013] In addition, to prevent galling, the auxiliary tool must be installed with high precision, which makes the installation itself difficult and time-consuming.Furthermore, since friction stir welding is performed while dragging the auxiliary tool, the welding speed cannot be increased, and when considering the prevention of galling in particular, there is the problem that further restrictions are placed on the welding speed.

[0014] In addition, friction stir welding tends to increase the temperature of the plastic flow zone. When friction stir welding is performed, the surface of the plastic flow zone is covered with an auxiliary tool, and the plastic flow zone is dragged by the auxiliary tool. Therefore, fillet welding by friction stir welding is particularly prone to temperature problems, and there are cases where restrictions are imposed on the materials of the workpieces to be joined and on the joining conditions such as the rotation speed and insertion depth of the stirring pin.

[0015] In response to this, the present inventors have changed their thinking from conventional thinking and attempted fillet joining by synchronous stir welding. Synchronous stir welding is a technique disclosed in, for example, Japanese Patent Nos. 7445355, 7526535, 7526536, and 7526537. The disclosures of Japanese Patent Nos. 7445355, 7526535, 7526536, and 7526537 are incorporated herein by reference.

[0016] As a result of the above trials, the inventors discovered that the ejection pressure of the plastic flow component in synchronous stir welding is sufficiently lower than that in friction stir welding, thereby suppressing the spread of flash. The inventors then discovered that fillet welding can be performed without using an auxiliary tool by utilizing the low ejection pressure of the plastic flow component in synchronous stir welding, and thus completed the present invention. This finding is completely different from the conventional friction stir welding described above. Furthermore, the above-mentioned patent publications do not disclose the low ejection pressure of the plastic flow component in synchronous stir welding, nor do they disclose fillet welding. In other words, the above-mentioned patent publications do not disclose or suggest the use of the low ejection pressure of the plastic flow component in synchronous stir welding for fillet welding. Therefore, even a person skilled in the art would not easily have arrived at this finding from the prior art. The present invention may employ the following configurations.

[0017] (1) A method for manufacturing a part that has been fillet welded by synchronous stir welding, the manufacturing method including a fillet joining step of fillet joining two workpieces, the fillet joining step being carried out by a synchronous stir welding apparatus, the synchronous stir welding apparatus including an output shaft, a drive mechanism configured to rotate the output shaft, and a pin portion provided at the tip of the output shaft and configured to rotate by rotation transmitted from the drive mechanism, the pin portion being inserted into the two workpieces during synchronous stirring, the pin portion having play between the output shaft and the pin portion that allows the pin portion to vibrate relative to the output shaft, the play being a gap or a substantial gap, and the pin portion being configured to be free or substantially free relative to the output shaft within the range of the play, the fillet joining step being a step of performing fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at an inner corner of a corner formed by the two workpieces.

[0018] According to manufacturing method (1), fillet welding is performed by synchronous stir welding, taking advantage of the low exhaust pressure of the plastic flow component produced by synchronous stir welding. Therefore, the spread of flash is suppressed. Therefore, roughness and irregularities in the surface of the plastic flow zone can be suppressed without the use of an auxiliary tool. Performing synchronous stir welding without the use of an auxiliary tool can suppress the occurrence of galling. Precise positioning of the auxiliary tool is not required, and synchronous stir welding can be performed quickly. Since there is no need to drag the auxiliary tool while performing synchronous stir welding, the welding speed can be increased. Since the increase in welding temperature can also be suppressed, there are fewer restrictions on welding conditions such as the material of the workpieces, the rotation speed of the stir pin, and the insertion depth. Therefore, according to manufacturing method (1), fillet welding can be performed easily and quickly, without the need for auxiliary tools and with fewer restrictions on welding conditions, while suppressing roughness and irregularities in the plastic flow zone.

[0019] Conventionally, as shown in Patent Documents 1 to 5, in fillet welding by friction stir welding, it was thought that roughness and irregularities on the surface of the plastic flow zone could not be suppressed unless an auxiliary tool with a fixed shoulder was used. Therefore, research and development was focused on the design and use of the auxiliary tool. The present invention overcomes this technical prejudice and makes it possible to suppress roughness and irregularities on the surface of the plastic flow zone without using an auxiliary tool.

[0020] In addition, in the past, auxiliary tools were used to suppress roughness and irregularities on the surface of the plastic flow zone, but as mentioned above, the use of auxiliary tools caused many problems. Suppressing roughness and irregularities on the surface of the plastic flow zone without using auxiliary tools has long been desired, but has been a technical challenge that has not been met with success. The present invention has resolved this technical challenge that has long been desired. The method for manufacturing parts fillet welded by synchronous stir welding can also be said to be a fillet welding method using synchronous stir welding.

[0021] The "play" allows the pin portion to vibrate relative to the output shaft. The play allows the pin portion to be configured so that the vibration of the pin portion has a greater amplitude and / or frequency than the vibration of the output shaft during synchronous stirring. The output shaft of the drive mechanism vibrates in response to the transmission of rotation from the drive mechanism during synchronous stirring. This vibration is also referred to as base vibration. Base vibration is vibration that inevitably occurs during synchronous stirring. The pin portion can be configured so that the vibration of the pin portion has a greater amplitude and / or frequency than the base vibration during synchronous stirring. The pin portion can be configured to rotate within the play range during synchronous stirring while moving to deflect the plastically flowing workpieces rather than resisting the workpieces. 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. As a result, the vibration of the pin portion can amplify the plastic flow of the workpieces to be welded. This vibration of the pin portion can achieve high-strength welding while suppressing the occurrence of welding defects. In addition, the tilt angle (advance angle) of the output shaft may be 0 degrees. Even with a tilt angle of 0 degrees, good synchronous stir welding can be achieved. Since 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 on 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 on the output shaft can be reduced. Note that the above (1) utilizes the low exhaust pressure of the plastic flow component due to synchronous stir welding.

[0022] The synchronous stir welding apparatus is not limited to a dedicated synchronous stir welding apparatus, but may be, for example, a machining center, a robot, a milling machine, a multitasking machine, a general-purpose machine, or a portable apparatus large enough for a user to hold in his or her hand for synchronous stir welding. The control conditions (position, load, spindle load, heat, pressure, etc.) of the synchronous stir welding apparatus or its auxiliary mechanisms are also not particularly limited. The welding conditions (feed speed, rotation speed, welding temperature, advance angle) are also not particularly limited. The materials of the workpieces are not particularly limited. The workpieces may be made of the same or different materials. In the embodiments described below, the play is provided by a key (an interlocking 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, bolts, pins, spherical bodies, and other elements can be used to provide the play. Furthermore, the play itself may be provided by the shape of the synchronous stirring rotating member itself. The synchronous stirring rotating member may be divided into multiple members (e.g., two), and play may be formed by the fit between adjacent members. 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 member 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 motor or an internal combustion engine. The drive mechanism may include a transmission that changes the speed of rotation output from the rotating machine and outputs it. 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, neither backlash nor margin within the drive mechanism corresponds to 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.

[0023] The gap is the space between the output shaft and the pin. "Substantially in the gap" means that the gap may contain a liquid or an elastic body to the extent that the amplitude and / or frequency of the vibration of the pin during synchronous stirring can be made larger than the vibration of the output shaft.

[0024] "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 synchronous mixing 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 due to an elastic body or liquid, which will be described later.

[0025] (2) A manufacturing method according to (1), wherein the synchronous stir welding device comprises a rotating member for synchronous stirring that is provided on the output shaft and includes the pin portion or is configured so that the pin portion can be detachably attached, and the rotating member for synchronous stirring is configured so that, when provided on the output shaft, a play is generated between the output shaft and the pin portion that allows the pin portion to vibrate relative to the output shaft.

[0026] According to the manufacturing method (2), similar to the above (1), no auxiliary tools are required, the joining conditions are less restricted, and fillet joining can be performed simply and quickly, stably, while suppressing roughness and disorder in the plastic flow portion.

[0027] The play may be present within the synchronous stirring rotating member itself. The synchronous stirring rotating member may be configured so that play is generated between the synchronous stirring rotating member and the output shaft by attaching the synchronous stirring rotating member to the output shaft. The synchronous stirring rotating member may not have a pin portion, but may be configured so that play is generated between the synchronous stirring rotating member and the pin portion by attaching a pin portion to the synchronous stirring rotating member.

[0028] (3) In the manufacturing method of (1) or (2), the pin portion is configured such that, due to the play, the vibration of the pin portion during synchronous stirring has a larger amplitude and / or frequency than the vibration of the output shaft.

[0029] According to the manufacturing method (3), the discharge pressure of the plastic flow component due to synchronous stir welding can be kept low, so no auxiliary tools are required, there are fewer restrictions on the joining conditions, and fillet joining can be performed simply and quickly, stably while suppressing roughness and disorder in the plastic flow portion.

[0030] (4) In the manufacturing method of any one of (1) to (3), the pin portion is configured so that vibration of the pin portion is passively generated by contact with plastic flow components in the two workpieces within the range of play.

[0031] According to the manufacturing method of (4), during synchronous stirring, the pin portion rotates within the range of play while moving to deflect rather than resist the plastic flow component. This makes it possible to keep the discharge pressure of the plastic flow component during synchronous stir welding low, so that fillet welding can be performed simply and quickly, without requiring auxiliary tools and with little restriction on joining conditions, while suppressing roughness and disorder in the plastic flow component.

[0032] (5) In the manufacturing method of any one of (1) to (4), the pin portion 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.

[0033] According to the manufacturing method (5), the discharge pressure of the plastic flow components due to synchronous stir welding can be kept low, so no auxiliary tools are required, there are fewer restrictions on the joining conditions, and fillet joining can be performed simply and quickly, stably while suppressing roughness and disorder in the plastic flow portion.

[0034] 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 direction and the circumferential direction. In the case of (E) above, the pin portion is capable of vibrating at least in the axial direction and the radial direction. In the case of (F) above, the pin portion is capable of vibrating at least in the circumferential direction and the radial direction. In the case of (G) above, the pin portion is capable of vibrating in the axial direction, the circumferential direction, and the radial direction. The amount of play in any one direction is not particularly limited and varies depending on the size of the joining device, etc., 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, for example.

[0035] (6) In the manufacturing method of any one of (1) to (5), the fillet joining process is a process of performing fillet joining by synchronous stir welding without using an auxiliary tool, and the auxiliary tool is configured to apply pressure to plastic flow portions generated by synchronous stir welding in the two workpieces at the inner corner without rotating together with the pin portion.

[0036] According to the manufacturing method of (6), since an auxiliary tool is not used, the occurrence of galling can be suppressed. Synchronous stir welding can be performed quickly. The welding speed can be increased. The increase in welding temperature can be suppressed. There are few restrictions on welding conditions. Fillet welding can be performed simply and quickly, stably, while suppressing roughness and disorder in the plastic flow portion.

[0037] (7) In the manufacturing method of any one of (1) to (6), an expanded diameter portion is provided on the base end side of the pin portion so as to continue from the pin portion, and the expanded diameter portion is configured to satisfy at least one of the following two requirements: (i) the diameter is larger than that of the pin portion, and (ii) the diameter increases toward the base end side; and the fillet joining process is a process of performing fillet joining by inserting the rotating pin portion into the two workpieces at an inner corner of a corner formed by the two workpieces by synchronous stir welding, so as to satisfy either of the following requirements: (iii) a plastic flow portion generated in the two workpieces at the inner corner by synchronous stir welding does not come into line contact with a side surface of the expanded diameter portion, or (iv) the plastic flow portion comes into line contact with the expanded diameter portion in a manner that both sides of the line contact position between the plastic flow portion and the expanded diameter portion in the circumferential direction of the expanded diameter portion are spatially open.

[0038] In (iii), the plastic flow portion and the side surface of the enlarged diameter portion do not make line contact, creating an environmentally open space between them. In (iv), the spatially open space on both sides of the line contact position also creates an open space between them. Under such an environment, proper fillet welding cannot be performed using friction stir welding. Therefore, in Patent Documents 1 to 5, an auxiliary tool is used to perform friction stir welding in an environmentally closed state. As a result, many problems arise due to the auxiliary tool. In contrast, according to the manufacturing method in (7), fillet welding is performed using synchronous stir welding. Therefore, in either (iii) or (iv), even if an environmentally open space exists, roughness and irregularities in the plastic flow portion are more effectively suppressed, and a high-quality fillet welding with a good appearance and reduced defects can be performed stably. Compared to (iv), (iii) can perform a fillet welding with a better appearance and higher quality. Compared with (iii), (iv) can perform a high-quality fillet joint with a good appearance and reduced defects even under conditions where vibration occurs in the workpieces to be joined. In other words, it can be said to have higher stability.

[0039] The expanded diameter portion is provided so as to be continuous with the base end side of the pin portion, but if the diameter of the expanded diameter portion is larger than the diameter of the pin portion at the portion where the expanded diameter portion and the pin portion are continuous, a step will occur at the portion where the expanded diameter portion and the pin portion are continuous. The tip surface of the expanded diameter portion at this step corresponds to a shoulder. As described above, it is preferable that either (iii) or (iv) is satisfied, but the "shoulder (tip surface of the expanded diameter portion)" may or may not be in contact with the plastic flow portion. Synchronous stir welding can suppress the discharge pressure of plastic flow components during fillet welding, so the shoulder (tip surface of the expanded diameter portion) can be made small. For example, the ratio of the diameter of the shoulder (tip surface of the expanded diameter portion) to the diameter of the base end side of the pin portion may be 1.8 or less. In other words, the shoulder may be formed small enough to satisfy this ratio, or it may not be formed. It is not necessary. The area of ​​the shoulder in contact with the plastic flow portion is reduced. Plastic flow is less likely to be hindered by the shoulder. Synchronous stir welding can be performed at lower temperatures. Synchronous stir welding at low temperatures can reduce the effect of temperature on the workpieces. This can suppress the generation of thermal deformation and stress, potentially improving the mechanical properties of the workpieces. Furthermore, lowering the temperature of synchronous stir welding can reduce energy consumption. It may also become possible to use materials that are difficult to join at high temperatures as workpieces.

[0040] The ratio is not particularly limited, but is preferably 1.8 or less, more preferably 1.5 or less, even more preferably 1.3 or less, and particularly preferably 1.1 or less. This is because it is possible to prevent a situation in which a shoulder interferes with plastic flow. When the ratio is 1.0, no shoulder is formed. An embodiment in which no shoulder is formed is also one of the preferred embodiments of the synchronous stirring rotating member. The ratio may be, for example, less than 2.0. The ratio may be 2 or more. A fixed shoulder that does not rotate with the pin portion may be used as the shoulder, and the fixed shoulder corresponds to the auxiliary tool described above. Synchronous stir welding enables suitable fillet welding without the use of an auxiliary tool.

[0041] (8) The manufacturing method of (7), wherein the enlarged diameter portion is configured to satisfy at least the requirement of (ii), the taper angle of the enlarged diameter portion is equal to or smaller than the angle of the angle formed by the two workpieces, and the fillet joining process is a process of performing fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at the inner corner of the angle formed by the two workpieces so that a plastic flow portion generated in the two workpieces at the inner corner by synchronous stir welding does not come into contact with a side surface of the enlarged diameter portion.

[0042] According to the manufacturing method (8), fillet joining can be performed stably while more effectively suppressing roughness and disorder in the plastic flow portion.

[0043] (9) In the manufacturing method of any one of (1) to (8), the fillet joining process is a process of performing fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at an inner corner of the angle formed by the two workpieces and moving the pin portion along the inner corner.

[0044] According to the manufacturing method (9), fillet welding by excellent synchronous stir welding can be stably expanded as described above.

[0045] (10) The manufacturing method according to any one of (1) to (9), further comprising an arrangement step of arranging the two workpieces before the fillet joining step so that the two workpieces form the corner and the pin portion can be inserted into the two workpieces at the inner corner of the corner in the fillet joining step.

[0046] According to the manufacturing method of (10), before the fillet joining step, an arrangement step is performed in which two workpieces are arranged so as to satisfy the following two requirements (I) and (II): (I) The two workpieces form the corner; and (II) In the fillet joining step, the pin portions can be inserted into the two workpieces at the inner corners of the corner. This allows for smooth fillet joining by excellent synchronous stir welding as described above.

[0047] (11) A synchronous stir welding apparatus for fillet welding, comprising: an output shaft; a drive mechanism configured to rotate the output shaft; a pin portion provided on the tip side of the output shaft, configured to rotate by rotation transmitted from the drive mechanism, and inserted into the two workpieces during synchronous stirring; a holding mechanism that holds the two workpieces; and a moving mechanism that changes the relative position of the pin portion and the two workpieces, wherein the pin portion has play between the output shaft and the pin portion that allows the pin portion to vibrate relative to the output shaft, the play being a gap or a substantial gap, and the pin portion is configured to be free or substantially free relative to the output shaft within the range of the play, and the moving mechanism is configured to perform fillet welding by synchronous stir welding by inserting the rotating pin portion into the two workpieces at an inner corner of a corner formed by the two workpieces.

[0048] According to the synchronous stir welding apparatus of (11), fillet welding is performed by synchronous stir welding, taking advantage of the low exhaust pressure of the plastic flow component that occurs during synchronous stir welding. As a result, the synchronous stir welding apparatus of (11) does not require auxiliary tools, is less subject to restrictions on welding conditions, and can easily and quickly perform stable fillet welding while suppressing roughness and disorder in the plastic flow portion.

[0049] (12) The synchronous stir welding apparatus of (11) further comprises a rotating member for synchronous stirring that is provided on the output shaft and includes the pin portion, and the rotating member for synchronous stirring is configured to generate play between the output shaft and the pin portion when provided on the output shaft, allowing the pin portion to vibrate relative to the output shaft.

[0050] According to the synchronous stir welding device of (12), similarly to the above (11), no auxiliary tools are required, there is little restriction on the welding conditions, and fillet welding can be performed simply and quickly, stably while suppressing roughness and disorder in the plastic flow portion.

[0051] (13) The synchronous stir welding device according to (11) or (12), wherein the pin portion is configured such that, due to the play, the vibration of the pin portion during synchronous stirring has an amplitude and / or frequency greater than the vibration of the output shaft.

[0052] According to the synchronous stir welding device of (13), the discharge pressure of the plastic flow component due to synchronous stir welding can be kept low, so no auxiliary tools are required, there are fewer restrictions on the joining conditions, and fillet welding can be performed simply and quickly, stably while suppressing roughness and disorder in the plastic flow portion.

[0053] (14) The synchronous stir welding device according to any one of (11) to (13), wherein the pin portion is configured so that vibration of the pin portion is passively generated by contact with plastic flow components in the two workpieces within the range of play.

[0054] According to the synchronous stir welding device of (14), the discharge pressure of the plastic flow component due to synchronous stir welding can be kept low, so no auxiliary tools are required, there are fewer restrictions on the joining conditions, and fillet welding can be performed simply and quickly, stably while suppressing roughness and disorder in the plastic flow portion.

[0055] (15) The synchronous stir welding apparatus according to any one of (11) to (14), wherein the pin portion 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.

[0056] According to the synchronous stir welding device of (15), the discharge pressure of the plastic flow component due to synchronous stir welding can be kept low, so no auxiliary tools are required, there are fewer restrictions on the joining conditions, and fillet welding can be performed simply and quickly, stably while suppressing roughness and disorder in the plastic flow portion.

[0057] (16) The synchronous stir welding apparatus according to any one of (11) to (15), wherein the synchronous stir welding apparatus does not include an auxiliary tool configured to apply pressure to plastic flow portions generated by synchronous stir welding in the two workpieces at the inner corners without rotating together with the pin portion.

[0058] According to the synchronous stir welding apparatus of (16), since an auxiliary tool is not used, the occurrence of galling can be suppressed. Synchronous stir welding can be performed quickly. The welding speed can be increased. The increase in welding temperature can be suppressed. There are few restrictions on welding conditions. Fillet welding can be performed simply and quickly, stably, while suppressing roughness and disorder in the plastic flow portion.

[0059] (17) The synchronous stir welding device according to any one of (11) to (16), wherein an expanded diameter portion is provided on the base end side of the pin portion so as to continue from the pin portion, and the expanded diameter portion is configured to satisfy at least one of the following two requirements: (i) the diameter is larger than that of the pin portion, and (ii) the diameter increases toward the base end side; and the moving mechanism is configured to perform fillet welding by inserting the rotating pin portion into the two workpieces at the inner corner of the corner formed by the two workpieces by synchronous stir welding, so as to satisfy either of the following requirements: (iii) a plastic flow portion generated in the two workpieces at the inner corner by synchronous stir welding does not come into line contact with a side surface of the expanded diameter portion, or (iv) the plastic flow portion comes into line contact with the expanded diameter portion in a manner that both sides of the line contact position between the plastic flow portion and the expanded diameter portion in the circumferential direction of the expanded diameter portion are spatially open.

[0060] According to the synchronous stir welding apparatus of (17), fillet welding is performed by synchronous stir welding. Therefore, in either (iii) or (iv), even if an environmentally open space exists, roughness and disorder in the plastic flow zone can be more effectively suppressed, and a high-quality fillet welding having a good appearance and suppressed defects can be performed stably. (iii) can perform a fillet welding having a better appearance and a higher quality than (iv). (iv) can perform a fillet welding having a good appearance and suppressed defects even under conditions in which vibration occurs in the workpieces to be welded, compared to (iii). In other words, it can be said to be more stable.

[0061] (18) The synchronous stir welding device of (17), wherein the enlarged diameter portion is configured to satisfy at least the requirement of (ii), the taper angle of the enlarged diameter portion is equal to or smaller than the angle of the angle formed by the two workpieces, and the moving mechanism is configured to perform fillet welding by synchronous stir welding by inserting the rotating pin portion into the two workpieces at the inner corner of the angle formed by the two workpieces so that a plastic flow portion generated in the two workpieces at the inner corner by synchronous stir welding does not come into contact with a side surface of the enlarged diameter portion.

[0062] According to the synchronous stir welding apparatus of (18), fillet welding can be performed stably while more effectively suppressing roughness and disturbance in the plastic flow portion.

[0063] (19) The synchronous stir welding apparatus according to any one of (11) to (18), wherein the moving mechanism is configured to perform fillet welding by synchronous stir welding by moving the rotating pin portion along the inner corner formed by the two workpieces while the pin portion is inserted into the two workpieces at the inner corner of the angle.

[0064] According to the synchronous stir welding apparatus of (19), fillet welding by excellent synchronous stir welding can be stably expanded as described above.

[0065] (20) The synchronous stir welding apparatus according to any one of (11) to (19), wherein the holding mechanism is configured to position and hold the two workpieces so that the two workpieces form the corner and the moving mechanism can insert the pin portion into the two workpieces at the inner corner of the corner.

[0066] According to the synchronous stir welding apparatus of (20), fillet welding can be smoothly performed by excellent synchronous stir welding as described above.

[0067] (21) A part that is fillet welded by synchronous stir welding, manufactured by the manufacturing method of any one of (1) to (10) or the synchronous stir welding apparatus of any one of (11) to (20).

[0068] The part (21) is manufactured with high strength and good quality fillet joints, and can be suitably used for various applications.

[0069] (22) A part fillet-welded by synchronous stir welding according to (21), wherein the part fillet-welded by synchronous stir welding is applied to any one of automobiles, railway vehicles, aircraft, ships, and rockets.

[0070] The (22) part is manufactured with high strength and good quality fillet joints, making it particularly suitable for use in these harsh environments.

[0071] (23) A part fillet-welded by the synchronous stir welding of (21), wherein the part fillet-welded by the synchronous stir welding is applied to any one of an electrode part, an air conditioning device, a water-cooled or air-cooled power control unit, a water-cooled or air-cooled battery case, a door panel, a shock absorber, a suspension link, a waveguide, an antenna, a motor cover, a sake brewing tank, a vacuum device part, a sputtering target material, and an embedded heater.

[0072] The (23) part is manufactured with high strength and good quality fillet joints, making it particularly suitable for use in these harsh environments.

[0073] (24) A part fillet-joined by synchronous stir welding according to any one of (21) to (23), wherein the part fillet-joined by synchronous stir welding is a part manufactured by fillet-joining the two workpieces having different thicknesses by synchronous stir welding, or a part manufactured by fillet-joining the two workpieces made of different materials by synchronous stir welding.

[0074] The excellent fillet joining by synchronous stir welding described above suppresses the occurrence of joining defects and enables high-strength joining. Therefore, high-quality fillet joining can be performed even on multiple plate materials of different thicknesses or on dissimilar materials. The resulting joined component is manufactured using high-strength, high-quality fillet joining. The dissimilar materials may be the following combinations: for example, a combination of dissimilar metals, a combination of resin and metal, a combination of metal casting and wrought metal, or a combination of ceramic and metal. Furthermore, at least one of the dissimilar materials may be the following: for example, a copper-aluminum dissimilar thin film material, a Ti-based material, an iron-based material, a chromium-based material, or rare metal joining. The rare metals referred to here may or may not include Ag and Au.

[0075] The present invention may further employ the following configurations. The following configurations are inherently or implicitly included in the present invention, but are described below for clarity. (22-1) A joined part according to (21) that is applied to a spacecraft, a special vehicle, a bicycle, a special defense vehicle, defense equipment, a linear motor, a linear motor car, and a drone. Examples of the spacecraft include artificial satellites, space stations, manned spacecraft, space probes, space telescopes, space cargo ships, space planes, and interplanetary probes. Examples of the special vehicles include self-propelled construction machinery such as truck cranes, trailer-mounted vehicles, and the like. Examples of the bicycles include city bicycles, electrically assisted bicycles, sports bikes, and specialized bicycles for off-road use or racing. The joined part according to (21) suppresses the occurrence of joining defects and provides high-strength joining, so the joined part according to (21) can be suitably used in applications under harsh environments such as those described in (22-1). (22-2) The joining part of (21) applied to facilities, devices, or equipment used in the following fields: food and beverage, liquid crystal / electronics / semiconductor, energy, power generation, batteries, solar cells, infrastructure, architecture, construction, medical care, vacuum, materials, equipment, machinery, metal / resin molding, home appliances, communications, IT, and digital. The joining part of (21) suppresses the occurrence of joining defects and provides high-strength joining, so the joining part of (21) can be suitably used in a wide range of fields, including those shown in (22-2). (23-1) The joining part of (21) applied to or configured as any one of the following: aluminum / aluminum alloy products, copper / copper alloy products, magnesium / magnesium alloy products, iron / iron alloy products, resin products, extrusion materials, drawing materials, casting materials, forging materials, thermal spray / injection materials, molding materials, metal products, dissimilar material joining products, thin film materials, bus bars, silver / silver alloy products, gold / gold alloy products, and titanium / titanium alloy products. (23-2) A joining part of (21) that is applied to any one of the following:Chambers, vacuum chambers, backing plates, water-cooled plates, temperature control plates, heat sinks, nozzles, valves, susceptors, ion implantation equipment, mobile phones, smartphones, chargers, capacitors, Wi-Fi devices, electrical appliances, household products, televisions, games, washing machines, refrigerators, clocks, digital watches, decorative members, accessories, tableware, knives, scissors, balls, glasses, bats, electronic devices, cameras. (23-3) Joining parts of (21) that are applied to any one of the following: Inverter cases, frames, bodies, suspension parts, doors, door panels, floor panels, ceiling panels, inner panels, outer panels, stack boxes, crank arms, waveguides, antennas, motors, gears, mufflers, electrical components, oil pans, motor covers, honeycomb panels, double skin panels, tailored materials, fuselage panels, wing parts, bridges, bridge beams, wheelchairs, turbines, blades, converters, battery pack housings, wheels, accelerators, brakes, drive shafts, bumpers, bumper beams, spoilers, crash boxes, saddles, crank cases, hoods, radomes, cladding materials, battery coil materials, rollers, bearings, beam guides, heat shields. (23-4) Joined parts of (21) that are applied to any one of the following: Gas tanks, gas generators, fuel tanks, liquor tanks, hydrogen tanks, gasoline tanks, nuclear containers, solvent tanks, sonar, thermal power generators, hydroelectric generators, wind power generators, nuclear power generators, ion implantation equipment, film deposition equipment, etching equipment, coating equipment, agricultural machinery, construction machinery, machine tools, industrial machinery, pumps and compressors, textile machinery, office machinery, superconducting devices, neutron devices, exposure equipment. (23-5) A joining part of (21) that is applied to any one of the following: syringes, catheters, medical equipment, stands, jigs, blades, scaffolding, sashes, exterior walls, interior walls, roofs, interior fittings, piping, chairs, desks, beds, sofas, cabinets. (23-6) A joining part of (21) that is applied to any one of the following: syringes, catheters, medical equipment, stands, jigs, blades, scaffolding, sashes, exterior walls, interior walls, roofs, interior fittings, piping, chairs, desks, beds, sofas, cabinets.Capacitors, dryers, fishing tackle (reels), musical instruments, microwave ovens, air conditioners, electric fans, computers, forklifts, tractors, excavators, bulldozers, robotic arms, flanges, caterpillar tracks, hydraulic cylinders, presses, suspensions, pedals, handlebars, guardrails, pipelines, engine blocks, transmissions, pantographs, fences, handrails, landing gear, railway rails, traffic lights, electronic signboards, railroad crossings, propeller shafts, ducts, ventilation fans, suitcases, attaché cases, stepladders, inductors, aluminum trays, bathtubs, support frames, cooling layers, distributors, combiners, in-flight leads, robotic arms, mechanical arms, housings, capsules, valves, detectors, missiles.

[0076] In the present invention, the following aspects can be adopted with regard to "play." While the following aspects are inherently or implicitly included in the present invention, they are described below for clarity. In the embodiments described below and the above description, the play is provided (I) using a member such as a key. However, (II) it may be provided by a fitting shape, or (III) it may be a combination of the aspects in (I) and (II) above. In the following description, it is assumed that, between the output shaft and the pin portion, member A on the output shaft side and member B on the pin portion side are adjacent to each other, and play is provided between member A and member B. Note that members A and B are not particularly limited. Furthermore, the configuration from the output shaft to the pin is not particularly limited, and may be output shaft-holder-collet-tool-pin, output shaft-holder-tool-pin, or output shaft-collet-tool-pin. The tool and pin may be integrated. The collet and holder may be integrated. The following example is applicable to any of these aspects. (I) Play provided using a connecting member such as a key. In this case, the connecting member is provided between members A and B. Members A and B may be located upstream (e.g., the output shaft and holder), in the middle (e.g., the holder and tool), or downstream (e.g., the tool and pin). Members such as a holder, collet, or tool may be divided between the output shaft side and the pin side, and a connecting member may be provided between these members to provide play. Furthermore, although a key is used as the connecting member in the embodiments described below and the above description, a pin or a bolt may also be used. The key is provided between the inner diameter side member and the outer diameter side member along the axial direction of the output shaft. That is, keyways are formed in each of the inner diameter side and outer diameter side members, and keys smaller than the keyways are provided in these keyways to provide play. The key is not particularly limited, and examples include parallel keys with a quadrangular (rectangular or square) cross section, wedge keys (triangular keys) tapered so that one end becomes thinner in the radial direction, crescent keys with a crescent-shaped cross section, round keys with a cylindrical cross section, oval keys, polygonal keys with pentagons or more, diamond keys, and other irregularly shaped keys (for example, T-shaped keys, fan-shaped keys), etc.The shape along the axial direction is not particularly limited, and examples include a straight key with a constant cross-sectional shape in the axial direction, a stepped key with a cross-sectional shape that changes stepwise in the axial direction, and a tapered key with a cross-sectional shape that changes gradually in the axial direction. Furthermore, a spherical body may be used as a connecting member instead of or in addition to a key. Multiple spherical bodies may be arranged side by side in a keyway (ball spline). A dimensional difference between the key and the keyway is provided in at least one of the radial, circumferential, and axial directions. This provides play that allows the pin portion to vibrate in that direction. The pin or bolt is provided so as to pass through both the inner diameter side member and the outer diameter side member along the radial direction of the output shaft. For example, play can be provided by forming a hole in one of the outer diameter side or inner diameter side member with a diameter larger than the diameter of the pin or bolt, and then installing the pin or bolt in the hole along the radial direction of the output shaft. A dimensional difference between the pin or bolt and the hole is provided in at least one of the radial, circumferential, and axial directions. This creates play that allows the pin portion to vibrate in that direction. (II) Play created by a fitting shape (spline): As with (I) above, the fit in this case may be located on any of the upstream, intermediate, and downstream sides. A member such as a holder, collet, or tool may be divided between the output shaft side and the pin portion side, and a fit may be formed between these members, thereby creating play. The spline may be provided over the entire circumferential direction, or may be provided over a portion of the circumferential direction. The spline shape is not particularly limited, and examples include a square spline (square groove), a round spline (round groove), a square spline (V groove), a sawtooth spline, an involute spline, and an involute serration. A dimensional difference between these fits is created in at least one of the radial, circumferential, and axial directions. This creates play that allows the pin portion to vibrate in that direction. (III) Play created by a combination of the above aspects (I) and (II): Play may be created by a combination of a connecting member and a fit. The play may be formed by any combination of the upstream side, the middle side, and the downstream side. Furthermore, the play may be formed by any combination of these.The play may be provided in multiple places.

[0077] According to the present invention, it is possible to perform fillet joining stably, easily and quickly, without requiring auxiliary tools, without being subject to restrictions on joining conditions, and while suppressing roughness and disorder in the plastic flow portion.

[0078] FIGS. 1(a) to 1(c) are cross-sectional views schematically illustrating a manufacturing method according to this embodiment, FIGS. 1(d) to 1(j) are cross-sectional views schematically illustrating the arrangement of two workpieces according to this embodiment, and FIGS. 1(k) to 1(p) are side views schematically illustrating a pin according to this embodiment. FIG. 2(a) is a cross-sectional view schematically illustrating a synchronous stirring rotating member according to a first embodiment, and FIG. 2(b) is a cross-sectional view taken along line A-A thereof. FIGS. 3(a) to 3(t) are cross-sectional views schematically illustrating synchronous stirring rotating members according to modifications. FIG. 4(a) is a cross-sectional view schematically illustrating a synchronous stirring rotating member according to a second embodiment, and FIG. 4(b) is a perspective view schematically illustrating a synchronous stirring rotating member according to a modification thereof. FIG. 5(a) is a cross-sectional view schematically illustrating a synchronous stirring rotating member according to a third embodiment, and FIGS. 5(b) and 5(c) are perspective views schematically illustrating synchronous stirring rotating members according to the modifications thereof.

[0079] 1(a) to 1(c) are cross-sectional views illustrating a fillet joining process included in the manufacturing method according to this embodiment. In FIG. 1(c), AD, CD, and RD indicate the axial direction, circumferential direction, and radial direction, respectively. These directions are common to FIGS. 1(a) to 1(c).

[0080] The fillet joining process is a process of fillet joining two workpieces 2a, 2b, and targets the two workpieces 2a, 2b that are placed so as to form an angle α ( FIG. 1( a) ). The workpieces 2a, 2b are plate-like bodies. However, they are not limited to plate-like bodies. The angle α is typically a right angle or a substantially right angle. Here, "substantially" means that errors in the shape of the workpieces and errors during placement of the workpieces are allowed. The angle α is not particularly limited as long as it is less than 180°. The angle α is preferably 45° or more and 135° or less, more preferably 60° or more and 120° or less, and even more preferably 75° or more and 105° or less.

[0081] The fillet welding process is performed by a synchronous stir welding apparatus 3. As shown in FIGS. 2 to 5 , the synchronous stir welding apparatus 3 includes an output shaft 5, a drive mechanism 4, and a pin portion 21. The drive mechanism 4 is configured to rotate the output shaft 5. The pin portion 21 is provided on the tip side of the output shaft 5. The pin portion 21 is inserted into two workpieces 2a, 2b during synchronous stirring. The pin portion 21 has play AP, CP between the output shaft 5 and the pin portion 21, which allows the pin portion 21 to vibrate relative to the output shaft 5. The play AP, CP are gaps or substantial gaps. The play AP, CP allows the pin portion 21 to be free or substantially free relative to the output shaft 5 within the range of the play AP, CP. The pin portion 21 is configured to rotate by rotation transmitted from the drive mechanism 4. 1(b), the pin portion 21 is depicted, but neither the output shaft 5 nor the drive mechanism 4, nor the play AP and CP, is depicted. As shown in FIG. 1(b), the pin portion 21 is directed toward the inner corner of the angle α (the contact position of the two workpieces 2a and 2b).

[0082] An expanded diameter portion 24 is provided on the proximal end side of the pin portion 21 so as to continue from the pin portion 21. The expanded diameter portion 24 is configured to satisfy the above-mentioned (ii) of the two requirements that (i) the diameter is larger than that of the pin portion 21, and (ii) the diameter increases toward the proximal end side. The taper angle β of the expanded diameter portion 24 is 90°, which is the same as the angle α ( FIG. 1( b) ).

[0083] In the fillet joining process, the pin portion 21, which rotates in the circumferential direction CD around the axis CA, is inserted into the two workpieces 2a and 2b at the inner corner of the angle α formed by the two workpieces 2a and 2b, thereby performing fillet joining by synchronous stir welding (FIG. 1(c)).

[0084] As shown in FIG. 1( c), the pin portion 21 is inserted into the plastic flow portion PF. The side surface of the expanded diameter portion 24 is not in contact with the plastic flow portion PF. The side surface of the expanded diameter portion 24 is not in contact with either the workpieces 2a, 2b. As shown in FIGS. 2 to 5, the pin portion 21 is configured to have play between the output shaft 5 and the pin portion 21 to allow vibration AV and CV of the pin portion 21 relative to the output shaft 5. The vibration AV and CV of the pin portion 21 have a larger amplitude and / or frequency than the output shaft 5. The expanded diameter portion 24 may be configured not to contact the plastic flow portion PF or the workpieces 2a, 2b when the pin portion 21 is not vibrating AV and CV. The expanded diameter portion 24 may be configured not to contact the plastic flow portion PF or the workpieces 2a, 2b when the pin portion 21 is vibrating AV and CV. Fillet welding can be performed by moving the pin portion 21 in the direction along the inner corner of the angle α (from the front to the back in FIG. 1(c)) in the state shown in FIG. 1(c). This fillet welding is performed by synchronous stir welding, so no auxiliary tools are required, there are few restrictions on the welding conditions, and fillet welding can be performed simply and quickly, stably, while suppressing roughness and disorder in the plastic flow portion PF.

[0085] In the example shown in Figures 1(a) to 1(c), the two workpieces 2a and 2b are arranged to form a corner joint. However, the arrangement of the two workpieces 2a and 2b is not particularly limited. Examples include a T-shaped joint (Figure 1(d)) and a lap joint (Figure 1(e)). A backplate joint (Figure 1(f)) may also be used. Furthermore, the corner joint is not limited to the vertical abutment of the two workpieces 2a and 2b shown in Figures 1(a) to 1(c). For example, the two workpieces 2a and 2b may abut horizontally, as shown in Figure 1(g). Furthermore, as shown in Figures 1(h), 1(i), and 1(j), the abutment portions of the two workpieces 2a and 2b are machined and then fillet-joined, which also falls under the fillet joining process of the present invention. The machined shapes of the abutment portions are not limited to those shown in Figures 1(h), 1(i), and 1(j). In a backplate joint, fillet welding is performed on two workpieces 2a and 2b by synchronous stir welding, and fillet welding is performed on two workpieces 2b and 2c by synchronous stir welding. In this way, by combining fillet welding of two workpieces by synchronous stir welding, it is possible to manufacture a workpiece in which three or more workpieces are fillet welded by synchronous stir welding. Similarly, T-shaped joints as shown in FIG. 1(d) may be combined to form a cross joint. The fillet welding process is usually performed on two workpieces, but it may also be performed on three or more workpieces. Even when fillet welding of three or more workpieces by synchronous stir welding is performed, the process includes fillet welding of two workpieces by synchronous stir welding, and therefore falls under the category of a fillet welding process.

[0086] The manufacturing method according to this embodiment may further include, in addition to the fillet joining step, an arrangement step of arranging the two workpieces 2 a, 2 b. In the arrangement step, the two workpieces 2 a, 2 b are arranged so that they form an angle α, and in the fillet joining step, the pin portion 21 can be inserted into the two workpieces 2 a, 2 b at the inner corner of the angle α (see FIG. 1( a)). The manufacturing method according to this embodiment may further include other steps.

[0087] In the examples shown in Figures 1(a) to 1(f), plate-shaped bodies are used as the members to be joined. The members to be joined are typically plate-shaped. However, the external shape of the members to be joined is not limited to this example. From the perspective of external shape, examples of members to be joined include tubular bodies, rod-shaped bodies, bodies with specific cross-sectional shapes such as H-shaped, I-shaped, and L-shaped, polygonal bodies such as cubes and rectangular parallelepipeds, and tapered bodies. Plate-shaped bodies are not limited to flat bodies. Examples include curved plates, corrugated plates, perforated plates (punched plates), textured plates (embossed plates), grid-shaped plates (gratings), composite plates, tapered plates with varying thickness, and ribbed plates. The tubular and rod-shaped bodies are not limited to linear shapes and may also be curved. Furthermore, the members to be joined may be hollow or solid.

[0088] The shape of the pin portion 21 is not limited to the shapes shown in Figures 1(b) and 1(c). For example, shapes such as those shown in Figures 1(k) to 1(n) can be adopted.

[0089] In the synchronous stir welding apparatus 3 shown in Fig. 1(k), a multi-stage enlarged diameter portion 24 is provided on the base end side of the pin portion 21. The multi-stage enlarged diameter portion 24 is configured so that the enlarged diameter portion 24 closer to the base end has a larger diameter than the enlarged diameter portion 24 on the tip end side. Furthermore, each enlarged diameter portion 24 itself is configured so that the diameter increases as it approaches the base end. Although the taper angle β is larger than the angle α, the enlarged diameter portion 24 is configured so as not to come into contact with the two workpieces 2a, 2b during synchronous stirring.

[0090] In the synchronous stir welding apparatus 3 shown in FIG. 1( l ), ​​an expanded diameter portion 24 is provided on the base end side of the pin portion 21. The expanded diameter portion 24 is configured so that the diameter increases toward the base end, but does not have a step as shown in FIG. 1( k ). The taper angle β is smaller than the angle α, and the expanded diameter portion 24 is configured so that its side surfaces do not come into surface contact with the two workpieces 2 a, 2 b during synchronous stirring. Note that the workpieces 2 a, 2 b referred to here may be the plastic flow portion PF. That is, the side surfaces of the expanded diameter portion 24 are configured so that they do not come into surface contact with the plastic flow portion PF during synchronous stirring. Meanwhile, the pin portion 21 has a shoulder 23. The shoulder 23 is provided so as to be able to come into contact with the plastic flow portion PF. The shoulder 23 is formed so that the ratio of the diameter of the shoulder 23 to the diameter of the base end side of the pin portion 21 satisfies 1.8 or less.

[0091] In the synchronous stir welding apparatus 3 shown in Fig. 1(m), the pin portion 21 is configured to be longer than that of the synchronous stir welding apparatus 3 shown in Fig. 1(l). Furthermore, the expanded diameter portion 24 has a taper angle β larger than the angle α, but is configured so that its side surface does not come into line contact with the two workpieces 2a and 2b during synchronous stirring.

[0092] In the synchronous stir welding apparatus 3 shown in FIG. 1( n), the enlarged diameter portion 24 is thinner overall than in the synchronous stir welding apparatus 3 shown in FIG. 1( l), and the taper angle β is smaller than the angle α.

[0093] 1(a) to 1(n), the auxiliary tool as described above is not used. Even without using the auxiliary tool, excellent fillet welding can be performed by synchronous stir welding.

[0094] The above-described example corresponds to the above-described embodiment (iii), but the present invention can also employ the examples shown in Figures 1(o) and 1(p) as the above-described embodiment (iv). In this example, the plastic flow portion PF and the expansion portion 24 are in line contact with each other in a manner that both sides of the line contact position LC between the plastic flow portion PF and the side surface of the expansion portion 24 in the circumferential direction CD of the expansion portion 24 are spatially open. In this example, too, excellent fillet welding can be performed by synchronous stir welding without using an auxiliary tool.

[0095] The synchronous stirring rotating member 1 according to the first to third embodiments will be described below with reference to Figures 2 to 5. The synchronous stirring rotating member 1 shown in Figures 2 to 5 can be employed in a synchronous stir welding apparatus 3, and the synchronous stir welding apparatus 3 can be used in a method for manufacturing parts that are fillet welded by synchronous stir welding.

[0096] First Embodiment FIG. 2( a ) is a cross-sectional view schematically illustrating a synchronous stirring rotating member 1 according to a first embodiment. FIG. 2( 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 reference numerals may be omitted in other figures, but are interpreted in the same manner as in this figure. Furthermore, in each figure, when adjacent components of the synchronous stirring rotating member 1 are hatched identically, this indicates that the components are fixed to each other. On the other hand, when different components are hatched differently, this indicates that the components are not fixed to each other. Furthermore, in each figure, the same components are designated by the same reference numerals.

[0097] The synchronous stirring rotating member 1 is provided in a synchronous stir welding apparatus 3. The synchronous stir welding apparatus 3 is an apparatus that performs fillet welding of two workpieces 2a and 2b by synchronous stir welding. The synchronous stir welding apparatus 3 has a drive mechanism 4. The synchronous stirring rotating member 1 is detachably attached to an output shaft 5 of the drive mechanism 4. The synchronous stirring rotating member 1 rotates together with the output shaft 5 so as not to be displaced relative to the output shaft 5.

[0098] The synchronous 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.

[0099] 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 workpieces 2a and 2b during synchronous stirring, as shown in FIG. 2(a). In the figure, PF schematically indicates the plastic flow portion of the workpieces 2a and 2b during synchronous stirring. The workpieces 2a and 2b are mounted on a trough-shaped support table (not shown) and fixed to the support table by a fixture (not shown) so as to form a corner joint as shown in FIGS. 1(a) to 1(c). A conventional fixture, such as a clamp, may be used as the fixture. The support table and fixture are examples of a holding mechanism included in the synchronous stir welding apparatus 3. A conventional holding mechanism, such as an L-shaped fixture or a multi-axis clamp, may be used as the holding mechanism. The holding mechanism may be mechanical or hydraulic, and is not particularly limited. The synchronous stir welding apparatus 3 also includes a moving mechanism (not shown) that moves the drive mechanism 4, together with the output shaft 5 and the synchronous stirring rotating member 1, along the inner corner of the angle α formed by the two workpieces 2a and 2b. This moving mechanism includes a pin 21 and moves the pin 21 of the two workpieces 2a and 2b. As the moving mechanism, for example, a conventionally known mechanism such as a gantry mechanism, a robotic arm, a lathe mechanism, a CNC machine, a track-type moving mechanism, or a pick-up and place mechanism can be used. Note that the two workpieces 2a and 2b may be moved instead of or together with the pin portion 21. Specifically, the moving mechanism may be configured to move a holding mechanism that holds the two workpieces 2a and 2b. As such a moving mechanism, a conventionally known moving mechanism such as a linear motion stage, an XY table, a multi-axis positioner, or a rotary table system can be used.

[0100] As shown in FIG. 2( b), 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. 2( a), 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, play CP is provided between the output shaft 5 and the pin portion 21. The play CP is a gap or substantially a 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. 2(b), the tip portion 20 is configured such that, due to the play CP, vibration CV is generated in the circumferential direction CD with respect to the rotating shaft portion 10 during synchronous stirring. The fitting keys 30 function as keys for transmitting rotational power from the drive mechanism from the rotating shaft portion 10 to the collet C.

[0101] Furthermore, the synchronous 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 relative to the output shaft 5 within the range of the play AP. As shown in FIG. 2(a), the pin portion 21 is configured such that, due to the play AP, vibration AV is generated in the axial direction AD relative to the output shaft 5 during synchronous stirring.

[0102] Within the plastic flow region PF, the rotation of the pin portion 21 causes plastic flow of the workpieces 2a and 2b. The pin portion 21 then comes into contact with the plastic flow component 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. As a result, passive vibrations AV and CV occur 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 2a and 2b, but can also synchronize with and amplify the plastic flow.

[0103] The pin portion 21 has a shoulder 23 at a height where it contacts the plastic flow portion PF. The ratio of the diameter of the shoulder 23 to the diameter of the pin portion 21 located directly below the shoulder 23 (the pin portion 21 adjacent to the shoulder 23 and closer to the tip of the shoulder 23) is 1.8 or less. As a result, the pin portion 21 has a shoulder 23 with a width narrow enough to satisfy the ratio ≦ 1.8.

[0104] Since the pin portion 21 has a narrow shoulder 23, the shoulder 23 is less likely to interfere with plastic flow. The effect of the vibrations AV and CV of the pin portion 21 (the effect of not interfering with plastic flow and amplifying it) can be more effectively obtained. Because the width of the shoulder 23 is small, the amount of heat generated during synchronous stirring is reduced, but effective plastic flow can be achieved due to the effect of the vibrations AV and CV of the pin portion 21. As a result, synchronous 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 interfere with plastic flow, and more amplified plastic flow can be achieved.

[0105] 3(a) to 3(t) are schematic cross-sectional views of modified examples of the synchronous stirring rotating member 1. The letters H, C, and T in 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 3(b) to 3(r), but are the same as in 3(a), 3(s), and 3(t).

[0106] [FIG. 3(a)] The synchronous 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 portion 22 and pin portion 21. The tip portion 20 is attached to the rotating shaft portion 10 by being inserted into a blind 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. 2(a) and 2(b), a fitting key 30 is provided between the rotating shaft portion 10 and the tip portion 20. As a result, the synchronous stirring rotating member 1 has play AP and CP between the rotating shaft portion 10 and the tip portion 20. The synchronous 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 synchronous stirring rotating member 1 is provided on the output shaft 5 via the holder H and the collet C.

[0107] [Fig. 3(b)] The synchronous 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 synchronous stirring rotating member 1 is provided on 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).

[0108] [Fig. 3(c)] The synchronous 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 synchronous stirring rotating member 1 is provided on the output shaft 5. Except for this point, the embodiment in Fig. 3(c) is the same as Figs. 3(a) and 3(b).

[0109] [FIG. 3(d)] The synchronous stirring rotating member 1 shown in FIG. 3(d) has a rotating shaft 10, an intermediate body 40, and a tip portion 20. The synchronous 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. 2) 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. 2) relative to the rotating shaft portion 10. As described above, 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. As described above, the synchronous stirring rotating member 1 as a whole has play AP, CP between the rotating shaft portion 10 and the tip portion 20.

[0110] [Fig. 3(e)] The synchronous 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 synchronous 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 a part of the tool T. The tip portion 20 corresponds to a 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).

[0111] [Fig. 3(f)] In the embodiment of Fig. 3(f), the synchronous 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. 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.

[0112] [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.

[0113] [Fig. 3(h)] In the embodiment of Fig. 3(h), the width of the shoulder 23 is wider than that of Fig. 2. The ratio is 2 or more. Because the shoulder 23 is integral with the pin portion 21, vibrations similar to those of the pin portion 21 occur in the shoulder 23. Therefore, even if the width of the shoulder 23 is wide, it is difficult to hinder the plastic flow of the workpieces 2a and 2b, and it is possible to amplify the plastic flow. 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.

[0114] [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. 2. The tips of the pin portions 21 in FIG. 2 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.

[0115] [Fig. 3(k)] In the embodiment of Fig. 3(k), the ratio is 1.0, and the synchronous stirring rotating member 1 does not have a shoulder. Since this synchronous stirring rotating member 1 does not have a rotating shoulder, synchronous stir welding can be achieved at a lower temperature.

[0116] [Figs. 3(l) and 3(m)] In the embodiment of Fig. 3(l), unlike Fig. 2, the synchronous stirring rotating member 1 has only play AP in the axial direction AD (see Fig. 2). Also, in the embodiment of Fig. 3(m), the synchronous stirring rotating member 1 has only play CP in the circumferential direction CD (see Fig. 2). In this way, the synchronous 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.

[0117] [FIG. 3(n)] In the embodiment of FIG. 3(n), the synchronous stirring rotating member 1 corresponds to the collet C and the tool T. The rotating shaft 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 portion 22 that are integrally formed with each other. The tip portion 20 is attached to the rotating shaft 10 by loosely fitting into a large-diameter, bottomed hole 17 provided on the underside of the rotating shaft 10. Because the diameter of the large-diameter, bottomed hole 17 is larger than the diameter of the base portion 22, a play RP in the radial direction RD (see FIG. 2) is provided around the base portion 22. A fixed key 31 is fixed to the outer surface of the base portion 22. A lateral through-hole 16 is provided in the rotating shaft 10 at a position corresponding to the fixed key 31. The lateral through-hole 16 provides a play CP in addition to the 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.

[0118] [FIG. 3(o)] In the embodiment shown in FIG. 3(o), the synchronous stirring rotating member 1 has a rotating shaft portion 10, an intermediate body 40, and a tip portion 20. The synchronous 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. 2) is provided around 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. 2) relative to the rotating shaft portion 10. As described above, the synchronous 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.

[0119] [Fig. 3(p)] In the embodiment of Fig. 3(p), unlike the embodiment of Fig. 2, the play AP, CP is not a gap, but is filled with a liquid 41 (e.g., lubricating oil). Such a synchronous stirring rotating member 1 can also achieve the vibration of the pin portion 21 described above. In other words, the play AP, CP is essentially a gap. The tip portion 20 is essentially free within the range of the play AP, CP.

[0120] [Fig. 3(q)] In the embodiment of Fig. 3(q), compared to the embodiment of Fig. 2, 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 synchronous stirring rotating member 1 can also achieve the vibration of the pin portion 21 described above. In other words, the play AP, CP is essentially an air gap. The tip portion 20 is essentially free within the range of the play AP, CP.

[0121] In the above example, the synchronous stirring rotating member 1 has the rotating shaft portion 10 and the tip portion 20, there is play between the rotating shaft portion 10 and the tip portion 20, and the tip portion 20 includes the pin portion 21. However, the synchronous stirring rotating member 1 is not limited to the above example, and the following aspects can be adopted, for example.

[0122] [Fig. 3(r)] In the embodiment of Fig. 3(r), the synchronous stirring rotating member 1 corresponds to the collet C and the tool T. The synchronous stirring rotating member 1 is configured as an integral whole and has a pin portion 21 and a shoulder 23. The synchronous stirring rotating member 1 is configured to be attached to a holder H, thereby generating play AP between the synchronous stirring rotating member 1 and the holder H. Due to the play AP, during synchronous stirring, the synchronous stirring rotating member 1 including the pin portion 21 vibrates in the axial direction AD relative to the output shaft 5.

[0123] [FIG. 3(s)] In the embodiment of FIG. 3(s), the synchronous stirring rotating member 1 corresponds to the holder H. The synchronous 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 synchronous stirring rotating member 1 by inserting the collet C and tool T into the bottomed hole. The synchronous stirring rotating member 1 does not have a pin portion. The pin portion is included in the tool T. The synchronous stirring rotating member 1 has a bottomed hole on its top surface for receiving the output shaft 5. The synchronous stirring rotating member 1 is attached to the output shaft 5 by inserting the output shaft 5 into the bottomed hole. The synchronous stirring rotating member 1 is configured to generate play AP between the output shaft 5 and the synchronous 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 synchronous stirring. The play AP allows the pin portion to vibrate relative to the output shaft 5.

[0124] [FIG. 3(t)] In the embodiment shown in FIG. 3(t), the rotating member 1 for synchronous stirring has a rotating shaft portion 10 and a tip portion 20. The rotating member 1 for synchronous stirring 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 distal to the rotating shaft portion 10. The tip portion 20 is configured to detachably mount 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 mount 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 rotating member 1 for synchronous stirring is not limited to the above example. The rotating member 1 for synchronous stirring is only required to be configured so as to generate 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, the collet C, and the tool T.

[0125] <Synchronous Stir Welding Apparatus> The synchronous stir welding apparatus according to the first embodiment is a synchronous stir welding apparatus 3 including a synchronous stirring rotating member 1, as shown in FIGS. 2( a) and 2(b). The synchronous stir welding apparatus 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, allowing vibration AV and CV of the pin portion 21 relative to the output shaft 5. Due to the play AP and CP, the vibration AV and CV of the pin portion 21 during synchronous welding have a larger amplitude and / or frequency than the vibration (base vibration) of the output shaft 5. The synchronous stir welding apparatus 3 of this embodiment includes a synchronous stirring rotating member 1 having play AP and CP. However, the synchronous stir welding apparatus 3 does not necessarily need to include a synchronous stirring rotating member 1, as long as there is play between the output shaft 5 and the pin portion 21. Note that the synchronous stir welding apparatus is used for fillet welding. The synchronous stir welding apparatus may be dedicated to fillet welding, but does not necessarily have to be dedicated to fillet welding.

[0126] 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 pin portion 21 is located at the top, the workpieces 2 (2a, 2b, etc.) are located at the bottom, and the pin portion 21 and the workpieces 2 (2a, 2b, etc.) face each other in the vertical direction. Specifically, in the example shown in FIG. 1, the pin portion 21 is inclined, and in the examples shown in FIGS. 2 to 5, the pin portion 21 faces vertically. In either case, the pin portion 21 faces vertically. 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 vertical, the synchronous stirring rotating member may be located at the bottom and the workpieces may be located at the top. Furthermore, the axial direction does not necessarily have to be fixed. When a synchronous stir welding apparatus is configured by installing a synchronous stirring rotating member in the portable apparatus described above, the axial direction may be changed during operation.

[0127] 4(a) is a cross-sectional view showing a schematic diagram of a synchronous stirring rotating member according to a second embodiment. In the second embodiment, unless otherwise specified, the same reference numerals as in the first embodiment are used for components corresponding to those in the first embodiment, and the description thereof will be omitted.

[0128] The synchronous stirring rotating member 1 according to the second embodiment has a fall prevention structure 50 that prevents the pin portion 21 from falling off the output shaft 5. The fall prevention structure 50 is configured to prevent the tool T, including the pin portion 21, from falling off the rotating shaft 10 together with the collet C. The fall prevention structure 50 includes a fall prevention member 50A having a pin portion insertion hole 50B formed therein, a fall prevention member mounting member 10C, and a step portion T1, which will be described later. The fall prevention member 50A has a flat plate shape. The fall prevention member 50A is fixed to the rotating shaft 10 by the fall prevention member mounting member 10C. The pin portion insertion hole 50B is smaller than at least the maximum diameter of the collet C and has a size that allows the pin portion 21 to be exposed to the outside. The fall prevention structure 50 is configured such that the step portion T1, formed by the difference in outer diameter between the collet C and the tool T, engages with the pin portion insertion hole 50B, thereby preventing the tool T from falling off. That is, the fall-off prevention structure 50 ensures that the tool T is exposed to the outside through the pin insertion hole 50B, allowing the pin 21 to be positioned at the intended joining position of the workpieces 2a and 2b (e.g., the intended joining line position along the inner corner of the angle formed by the abutted workpieces 2a and 2b), while preventing the tool T from falling off due to the provision of clearance CP. Such falling-off of the tool T is primarily due to gravity, which is the weight of the tool T, including the pin 21. This problem tends to become more pronounced when the tool T is configured to be detachable and replaceable. Furthermore, from the perspective of joining quality, it is preferable to provide clearance AP between the pin 21 and the output shaft 5 to the extent that the tool T, including the pin 21, can fall off together with the collet C from the rotating shaft 10, rather than providing clearance AP between the pin 21 and the output shaft 5 to the extent that the pin 21 does not fall off. However, as the clearance AP increases, the risk of the tool T falling off increases. Such a risk may be reduced by filling the slack AP portion with a fire-resistant hydraulic oil such as a water-glycol-based hydraulic oil, depending on the viscosity of the hydraulic oil; however, in this embodiment, the weight of the collet C and tool T, which are integrally joined, is relatively heavy, and the viscosity of the hydraulic oil alone is insufficient to support that weight.Furthermore, when the synchronous stirring rotating member 1 is installed in a robot-type joining device as described below, centrifugal force and inertial force are applied to the synchronous stirring rotating member 1 when the synchronous stirring rotating member 1 is rotated, pivoted, and / or moved by a robot arm, further increasing the likelihood of the tool T falling off. However, the fall-off prevention structure 50 can prevent the tool T from falling off. Note that the structure of the fall-off prevention structure 50 is not limited to this embodiment. The fall-off prevention member mounting member 10C is a screw, but is not particularly limited thereto. Furthermore, the fall-off prevention member 50A may have a cap shape with a threaded inner periphery, while a corresponding threaded outer periphery of the rotating shaft portion 10 may have a corresponding threaded outer periphery. This allows the fall-off prevention member 50A to be fixed to the rotating shaft portion 10 without using the fall-off prevention member mounting member 10C. This embodiment will be described in the following modified example. Furthermore, the provision of the play AP as in the present invention has the advantage of facilitating the replacement of the tool T. In particular, when a general user or an operator unfamiliar with handling replaces the tool T, the tool T can be easily grasped and removed by hand and replaced with a new tool without the need for a dedicated tool replacement device.

[0129] <Modification of the Second Embodiment> Figure 4(b) is a perspective view schematically illustrating a synchronous stirring rotating member 1 according to a modification of the second embodiment. In this modification, unless otherwise specified, components corresponding to those in the above-described embodiment are denoted by the same reference numerals as in the above-described embodiment, and their description is omitted. In the synchronous stirring rotating member 1 according to this modification, the collet C and tool T, which are integrally formed with each other, are inserted together with the fitting key 30 into a bottomed hole formed in the rotating shaft portion 10 through the distal end opening 10A of the rotating shaft portion 10, thereby attaching the collet C and tool T to the distal end opening 10A of the rotating shaft portion 10. The drop-out prevention structure 50 includes a drop-out prevention member 50A and a step portion T1. The drop-out prevention member 50A is configured such that the diameter r of the pin insertion hole 50B formed in the drop-out prevention member 50A and the outer shape R of the collet C satisfy the relationship r<R. The tip of the tool T, together with the collet C integrally formed with the tool T, is prevented from sinking into the rotating shaft portion 10, and the tip of the tool T is exposed to the outside through the pin insertion hole 50B. As described above, the fall-off prevention member 50A and the rotating shaft portion 10 are fixed to each other by their respective thread grooves, which can prevent the fall-off prevention member 50A and the rotating shaft portion 10 from separating during synchronous stir welding. Note that the structure for fixing the fall-off prevention member 50A to the rotating shaft portion 10 is not limited to this example. Furthermore, the tool T is configured so that its outer diameter is smaller than the diameter r of the pin insertion hole 50B. This allows the tool T attached to the collet C to be separated from the collet C and removed from the fall-off prevention member 50A through the pin insertion hole 50B by gripping and rotating it. Another tool T can also be attached to the collet C through the pin insertion hole 50B. Therefore, only the tool T can be replaced. In this embodiment, the tool T and the collet C can be separated, but the tool T and the collet C may also be integrally configured so as not to be separated. In this case, the fall-off prevention member 50A is removed from the rotating shaft portion 10, and the collet C and the tool T are replaced. The synchronous stirring rotating member 1 shown in Figures 4(a) and (b) has a tip-insertion type fall-off prevention structure 50 into which the collet C and the tool T are inserted from the tip side, but the synchronous stirring rotating member is not limited to these examples.The synchronous stirring rotating member may have a rear end insertion type fall-off prevention structure in which the collet C and tool T are inserted from the rear end side, as shown in FIGS. 5(a) to 5(c).

[0130] Third Embodiment FIG. 5A is a cross-sectional view schematically illustrating a synchronous stirring rotating member 1 according to a third embodiment. In the third embodiment, components corresponding to those in the above-described embodiments are denoted by the same reference numerals as in the above-described embodiments, and their description is omitted unless otherwise specified. The synchronous stirring rotating member 1 according to the third embodiment includes a fall-off prevention portion 50A' formed integrally with the rotating shaft portion 10, instead of the above-described fall-off prevention member 50A. The fall-off prevention portion 50A' includes a pin insertion hole 50B. A rear hole 10E is formed at the rear end of the rotating shaft portion 10. A tool T and a collet C, which are integrally formed with each other, are inserted through the rear hole 10E together with a fitting key 30. Furthermore, a closing member 100 is provided to close the rear hole 10E from the rear. Corresponding thread grooves are formed in the closing member 100 and the rotating shaft portion 10, and the closing member 100 is fixed to the rotating shaft portion 10 by these thread grooves. This makes it possible to prevent the tool T and collet C from falling off and to keep the tip of the tool T exposed at all times while ensuring the play AP. In this embodiment, the fall-off prevention structure 50 includes a fall-off prevention portion 50A′, a step portion T1, and a closing member 100.

[0131] <Modification of the Third Embodiment> Figures 5(b) and (c) are perspective views schematically illustrating a synchronous stirring rotating member according to a modification of the third embodiment. In this modification, unless otherwise specified, components corresponding to those in the above-described embodiment are denoted by the same reference numerals as in the above-described embodiment, and their description is omitted. In the synchronous stirring rotating member 1 according to Figures 5(b) and 5(c), similar to the synchronous stirring rotating member 1 according to Figure 5(a), an integrally formed tool T and collet C are inserted into a rear hole 10E from the rear end side, and the rear hole 10E is closed by a closing member 100. The fastening structure of the closing member 100 is not limited to a screw structure. For example, any structure may be employed, such as a forced fit, or drilling a locking screw insertion hole penetrating the outer periphery of the rotating shaft portion 10 and fastening it with a headless screw.

[0132] Synchronous stirring rotating member: 1 Workpieces to be welded: 2a, 2b, 2c Synchronous stir welding apparatus: 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 Expanded diameter portion: 24 Groove: 25 Fitting key: 30 Fixing key: 31 Intermediate body: 40 Liquid: 41 Elastic body: 42

Claims

1. A method for manufacturing a fillet-welded part, the method comprising: a fillet joining step of fillet-welding two workpieces, the fillet joining step being carried out by a synchronous stir welding apparatus, the synchronous stir welding apparatus comprising: an output shaft; a drive mechanism configured to rotate the output shaft; and a pin portion provided at the tip of the output shaft and configured to rotate by rotation transmitted from the drive mechanism and inserted into the two workpieces during synchronous stirring, the pin portion having play between the output shaft and the pin portion that enables the pin portion to vibrate relative to the output shaft, the play being a gap or a substantial gap, and the pin portion being configured such that the pin portion is free or substantially free relative to the output shaft within the range of the play, and the fillet joining step being a step of performing fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at an inner corner of a corner formed by the two workpieces.

2. The manufacturing method described in claim 1, wherein the synchronous stir welding apparatus comprises a synchronous stirring rotating member that is attached to the output shaft and includes the pin portion or is configured to allow the pin portion to be detachably attached, and the synchronous stirring rotating member is configured, when attached to the output shaft, to generate play between the output shaft and the pin portion that enables the pin portion to vibrate relative to the output shaft.

3. A manufacturing method as described in claim 1 or 2, wherein the pin portion is configured such that, due to the play, the vibration of the pin portion during synchronous stirring has an amplitude and / or frequency greater than the vibration of the output shaft.

4. A manufacturing method as described in any one of claims 1 to 3, wherein the pin portion is configured so that vibration of the pin portion is passively generated by contact with plastic flow components in the two joined members within the range of play.

5. A manufacturing method as described in any one of claims 1 to 4, wherein the pin portion 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. A manufacturing method as claimed in any one of claims 1 to 5, wherein the fillet joining process is a process of performing fillet joining by synchronous stir welding without using an auxiliary tool, and the auxiliary tool is configured not to rotate together with the pin portion but to apply pressure to the plastic flow portion generated by synchronous stir welding in the two workpieces at the inner corner.

7. A manufacturing method according to any one of claims 1 to 6, wherein an expanded diameter portion is provided on the base end side of the pin portion so as to be continuous from the pin portion, and the expanded diameter portion is configured to satisfy at least one of the two requirements of (i) having a larger diameter than the pin portion, and (ii) having a diameter that increases toward the base end side, and the fillet joining process is a process of performing fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at an inner corner of a corner formed by the two workpieces so as to satisfy either of the requirements of (iii) a plastic flow portion generated in the two workpieces at the inner corner by synchronous stir welding does not come into line contact with a side surface of the expanded diameter portion, or (iv) the plastic flow portion comes into line contact with the expanded diameter portion in a state in which both sides of a line contact position between the plastic flow portion and the expanded diameter portion in the circumferential direction of the expanded diameter portion are spatially open.

8. A manufacturing method as claimed in claim 7, wherein the enlarged diameter portion is configured to satisfy at least the requirement (ii), the taper angle of the enlarged diameter portion is equal to or smaller than the angle of the corner formed by the two workpieces, and the fillet joining process is a process of performing fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at the inner corner of the corner formed by the two workpieces so that a plastic flow portion generated in the two workpieces at the inner corner by synchronous stir welding does not come into contact with a side of the enlarged diameter portion.

9. A manufacturing method according to any one of claims 1 to 8, wherein the fillet joining process is a process for performing fillet joining by synchronous stir welding by inserting the rotating pin portion into the inner corner of the angle formed by the two workpieces and moving the pin portion along the inner corner.

10. A manufacturing method according to any one of claims 1 to 9, further comprising a positioning step of positioning the two workpieces before the fillet joining step so that the two workpieces form the corner and so that in the fillet joining step, the pin portion can be inserted into the two workpieces at the inner corner of the corner.

11. A synchronous stir welding apparatus for fillet joining, comprising: an output shaft; a drive mechanism configured to rotate the output shaft; a pin portion provided at the tip side of the output shaft and configured to rotate by rotation transmitted from the drive mechanism and inserted into the two workpieces during synchronous stirring; a holding mechanism for holding the two workpieces; and a moving mechanism for changing the relative position of the pin portion and the two workpieces, wherein the pin portion has play between the output shaft and the pin portion that enables the pin portion to vibrate relative to the output shaft, the play being a gap or substantially a gap, and the pin portion is configured to be free or substantially free relative to the output shaft within the range of the play, and the moving mechanism is configured to perform fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at an inner corner of a corner formed by the two workpieces.

12. The synchronous stir welding apparatus according to claim 11, further comprising a rotating member for synchronous stirring that is provided on the output shaft and includes the pin portion, and the rotating member for synchronous stirring is configured, when provided on the output shaft, to generate play between the output shaft and the pin portion that enables vibration of the pin portion relative to the output shaft.

13. A synchronous stir welding apparatus as claimed in claim 11 or 12, wherein the pin portion is configured such that, due to the play, vibration of the pin portion during synchronous stirring has an amplitude and / or frequency greater than vibration of the output shaft.

14. A synchronous stir welding device as claimed in any one of claims 11 to 13, wherein the pin portion is configured so that vibration of the pin portion is passively generated by contact with plastic flow components in the two workpieces within the range of play.

15. A synchronous stir welding device as set forth in any one of claims 11 to 14, wherein the pin portion 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.

16. A synchronous stir welding device as claimed in any one of claims 11 to 15, which does not include an auxiliary tool configured to apply pressure to the plastic flow portion generated by synchronous stir welding of the two workpieces at the inner corner without rotating together with the pin portion.

17. The synchronous stir welding device according to any one of claims 11 to 16, wherein an expanded diameter portion is provided on the base end side of the pin portion so as to be continuous from the pin portion, and the expanded diameter portion is configured to satisfy at least one of two requirements: (i) the diameter is larger than that of the pin portion, and (ii) the diameter increases toward the base end side; and the moving mechanism is configured to perform fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at the inner corner of a corner formed by the two workpieces so as to satisfy either of the requirements: (iii) a plastic flow portion generated in the two workpieces at the inner corner by synchronous stir welding does not come into line contact with a side surface of the expanded diameter portion, or (iv) the plastic flow portion comes into line contact with the expanded diameter portion in a state in which both sides of a line contact position between the plastic flow portion and the expanded diameter portion in the circumferential direction of the expanded diameter portion are spatially open.

18. The synchronous stir welding apparatus according to claim 17, wherein the enlarged diameter portion is configured to satisfy at least the requirement (ii), the taper angle of the enlarged diameter portion is equal to or smaller than the angle of the angle formed by the two workpieces, and the moving mechanism is configured to perform fillet joining by synchronous stir welding by inserting the rotating pin portion into the two workpieces at the inner corner of the angle formed by the two workpieces so that a plastic flow portion generated in the two workpieces at the inner corner by synchronous stir welding does not come into contact with a side of the enlarged diameter portion.

19. A synchronous stir welding device as claimed in any one of claims 11 to 18, wherein the moving mechanism is configured to perform fillet welding by synchronous stir welding by moving the rotating pin portion along an inner corner formed by the two workpieces while the pin portion is inserted into the two workpieces at the inner corner.

20. A synchronous stir welding apparatus as described in any one of claims 11 to 19, wherein the holding mechanism is configured to position and hold the two workpieces so that the two workpieces form the corner and the moving mechanism is capable of inserting the pin portion into the two workpieces at the inner corner of the corner.

21. A part which has been fillet-welded by synchronous stir welding, manufactured by the manufacturing method according to any one of claims 1 to 10 or by the synchronous stir welding apparatus according to any one of claims 11 to 20.

22. A part fillet-welded by synchronous stir welding as claimed in claim 21, wherein the part fillet-welded by synchronous stir welding is applied to any one of automobiles, railway cars, aircraft, ships and rockets.

23. A part fillet-joined by synchronous stir welding as claimed in claim 21, which is applied to any one of electrode parts, air conditioning equipment, water-cooled or air-cooled power control units, water-cooled or air-cooled battery cases, door panels, shock absorbers, suspension links, waveguides, antennas, motor covers, brewing tanks, vacuum device parts, sputtering target materials and embedded heaters.

24. A part fillet-joined by synchronous stir welding according to any one of claims 21 to 23, which is a part manufactured by fillet-joining the two workpieces having different thicknesses by synchronous stir welding, or a part manufactured by fillet-joining the two workpieces made of different materials by synchronous stir welding.

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