JP3735296B2 - Friction stir welding equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a friction stir welding apparatus that generates plastic flow on butted surfaces of materials to be joined and joins them together.
[0002]
[Prior art]
In recent years, a friction stir welding (FSW) method has emerged as a new joining means that replaces welding and brazing of metal materials. This friction stir welding method is slidably contacted with a work piece while rotating a probe (rod-like protrusion) made of a material harder than a metal work piece as disclosed in, for example, Japanese Translation of PCT Publication No. 7-505090. Since the material of the workpiece is plastic fluidized by the frictional heat and pressure generated at the sliding contact portion, the probe is embedded in the workpiece and remains in this embedded state. It uses the fact that it can move in the work piece. Such a friction stir welding method is used as a method for joining relatively soft metals such as aluminum and aluminum alloys.
[0003]
Hereinafter, a conventional friction stir welding method will be briefly described with reference to the drawings. FIG. 4 is a perspective view showing an implementation state of friction stir welding, and FIG. 5 is an explanatory view showing a mechanism of friction stir welding.
For example, as shown in FIG. 4, when the probe 5 protruding from the rotary tool 4 is inserted into the joining line 3 where the joining surfaces of the metal plates 1 and 2 that are the workpieces are abutted with each other, the friction with the shoulder portion 6 occurs. The material of the metal plates 1 and 2 is softened by heat generation. For this reason, the probe 5 can be aligned with the joint line 3 and inserted into the joint, and the probe 5 thus placed in an embedded state is moved relative to the joint line 3 of the fixed metal materials 1 and 2. A softened region 7 (see FIG. 5) is generated around the probe 5.
[0004]
In the softening region 7, the materials of the two metal plates 1 and 2 plastically flowed on the front side of the probe 5 are stirred and kneaded while receiving pressure, and gradually move to the rear side of the probe 5. As a result, the plastic-flowing material loses frictional heat on the rear side and rapidly cools and hardens, so that the two metal plates 1 and 2 are joined together in a state where the materials are mixed and completely integrated.
Since the probe 5 is provided with the reverse screw 5a in the rotation direction, a downward plastic flow as indicated by an arrow in FIG. 5 occurs, so that a space (nest) having no material on the back side, which tends to be a lower temperature than the surface, etc. It is difficult to cause defects and poor fusion.
[0005]
In this case, the temperature at which the metal material plastically flows is considerably lower than the melting point, joining is in the category of solid-phase joining, the heat input to the metal material through the joining process is extremely small compared to welding and brazing, and solidification. Since there is no generation of stress due to shrinkage, there is an advantage that deformation or cracking due to thermal strain in the vicinity of the joint is unlikely to occur.
[0006]
Further, in the friction stir welding method described above, it is necessary to press the rotary tool 4 against the metal plates 1 and 2 in order to generate frictional heat at the time of joining. Therefore, the backing metal 8 is used to cope with the reaction force. ing. This backing metal 8 is installed in close contact with the back surfaces of the metal plates 1 and 2 to be joined, and acts from the rotary tool 4 side, for example, about 8000 to 18000 N, or a reaction force with a large applied pressure. Receive.
[0007]
In addition, the rotating tool 4A called a bobbin tool shown in FIG. 6 is provided with a pair of shoulder portions 6a and 6b that are spaced apart so as to sandwich both front and back surfaces of the metal plates 1 and 2 to be joined. Yes. In this case, since the probe 5 is provided between the pair of upper and lower shoulder portions 6a and 6b, it is possible to generate heat by friction on both surfaces of the joint portion, and the backside fusion failure is unlikely to occur.
[0008]
FIG. 7 is a plan view showing a configuration example of a friction stir welding apparatus that joins workpieces by the friction stir welding method described above.
In FIG. 7, reference numeral 10 in the drawing is a friction stir welding apparatus, 11 is a sliding main body, 12 is a main shaft (rotating shaft), 13 is a driving belt, 14 is a main shaft rotating motor, 15 is a ball screw, and 16 is a main shaft moving motor. It is.
[0009]
In the friction stir welding apparatus 10, the rotary tool 4 is attached to the tip end portion of the main shaft 12. The main shaft 12 is rotatably supported by the sliding main body 11, and rotates by obtaining a driving force from a main shaft rotating motor 14 via a driving belt 13.
The sliding main body 11 is supported by a base (not shown) together with the spindle rotating motor 14. The sliding body 11 is slid in the direction of the arrow 17 together with the base by a ball screw 15 that is connected to the spindle moving motor 16 and rotates, and the shoulder 6 of the rotary tool 4 is applied to the surfaces of the metal plates 1 and 2 with a predetermined amount. It is designed to press with pressure.
In the friction stir welding apparatus 10 shown in FIG. 7, the rotating shaft 12 is disposed in the horizontal direction, but there is also an apparatus in which the rotating shaft 12 is disposed in the vertical direction.
[0010]
[Problems to be solved by the invention]
By the way, according to the above-described prior art, since the rotary tool 4 is driven uniaxially, there is a problem that it cannot cope with the plate thickness fluctuation.
That is, because the rotary tool 4 is driven to rotate by the main shaft 12 and is pressed against the surface of the metal plates 1 and 2 by the main shaft drive motor 16 and the ball screw 15, the backing metal 8 is required on the back surfaces of the metal plates 1 and 2. And For this reason, if the thickness of the metal plates 1 and 2 is varied, it is difficult to keep the applied pressure constant, and heating due to friction of the shoulder portion 6 and plastic flow of the softened region 7 are insufficient, resulting in poor fusion. Cheap.
And since a backing metal is required, there also exists a problem that it cannot apply to circumferential joining, such as a container which puts a large backing metal inside and carries out friction stir welding.
[0011]
Further, even when the bobbin tool 4A as shown in FIG. 6 is used, the upper and lower shoulder portions 6a and 6b are fixed in the axial direction and have a constant interval, and thus cannot cope with the thickness variation. In order to solve such a problem, a bobbin tool having a variable shaft length type in which the interval between the shoulder portions 6a and 6b is variable is desired.
However, the above-described single-axis drive configuration supports a variable-axis-length bobbin tool in which the upper and lower shoulders can be moved relative to each other in the axial direction and the rotational driving force between the shoulders must be transmitted. could not.
[0012]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a friction stir welding apparatus that can cope with variations in plate thickness and can be satisfactorily joined without poor fusion.
[0013]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems. The friction stir welding apparatus according to claim 1 is a friction stir welding apparatus that heats and agitates a joining portion of workpieces with a rotary tool and joins the workpieces without melting, and slides on a base fixed to a floor surface. A first slide base that is slidably installed; a second slide base that is slidably installed on the first slide base independently of the first slide base; and a first and a second shoulder portion for heating by frictional heat in contact on both surfaces, and a rotary shaft made of a shaft and outer shaft inside which is splined on the same axis connected to a drive source, said first The outer shaft is attached to one slide base, the inner shaft is attached to the second slide base, the first shoulder portion is connected to the outer shaft, and the second shoulder portion is connected to the inner shaft. And Serial first shoulder portion pressed against the surface, and is characterized in that it has configured to pressurize attract the second shoulder portion on the back surface.
[0014]
According to such a friction stir welding apparatus, the first shoulder portion is connected to the outer shaft attached to the first slide base , and the second shoulder portion is connected to the inner shaft attached to the second slide base. At the same time, the first shoulder portion is pressed against the surface to apply pressure, and the second shoulder portion is applied to the back surface to apply pressure, so that it is possible to support a rotary tool with variable shaft length. And it becomes possible to pressurize with a constant pressure from both sides by the second shoulder portion, and the backing metal becomes unnecessary.
[0015]
In the friction stir welding apparatus according to claim 1, it is preferable to perform load control by providing load detection means on each of the inner shaft and the outer shaft, so that even if there is a variation in the plate thickness, the friction stir welding apparatus can cope with it more reliably. The pressure can be kept constant.
[0016]
Further, in the friction stir welding apparatus described above, it is preferable that the rotary tool is provided with a fluid ejection port, and thereby, an atmosphere is controlled by injecting an inert gas around the joint portion, or the injected air is injected. It becomes possible to perform cooling by.
[0017]
Further, in the friction stir welding apparatus described above, it is preferable that the rotating shaft can be attached by selecting either the rotary tool or the plug welding tool. The hole can be filled by plug welding.
The drive source is preferably provided with a speed change mechanism corresponding to the difference between the rotational speed when the rotary tool is attached and the rotational speed when the plug welding tool is attached, and further provided with a brake mechanism capable of suddenly stopping the rotary shaft. Is preferred.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a friction stir welding apparatus according to the present invention will be described with reference to FIGS.
FIG. 1 is a front view showing an example of the overall configuration of a friction stir welding apparatus. In FIG. 1, reference numeral 20 denotes a friction stir welding apparatus, 21 denotes a base, 22 denotes a pressing motor, 23 denotes a first guide rail, and 24 denotes a first. Slide base, 25 is a pulling motor, 26 is a second guide rail, 27 is a second slide base, 28 is a spindle rotation (tool drive) motor, 29 is a drive belt, 30 is a slide body, and 40 is a spindle (Rotary axis), 50 is a bobbin tool (rotary tool), and W is a workpiece.
[0019]
The base 21 is a member that supports the components of the friction stir welding apparatus 20 and is fixedly installed on the floor surface or the like.
On the upper surface of the base 21, a first guide rail 23 extending in the direction of a main shaft 40 described later is installed. The slider 24a of the first slide base 24 is engaged with the first guide rail 23, and the first slide base 24 is directed to the base 21 in the main axis direction indicated by an arrow in the drawing with the pressing motor 22 as a drive source. It is slidably supported. The sliding of the first slide base 24 is performed by rotational driving of a ball screw mechanism (not shown) that is connected to the drive shaft of the pressing motor 22 and is provided on the first slide base. This ball screw mechanism is provided with a load cell (not shown) as load detecting means. The pressing motor 22 is fixedly installed on the base 21.
[0020]
On the upper surface of the first slide base 24, a second guide rail 26 extending in the same direction as the first guide rail 23 and a sliding main body 30 described later are installed. Among these, the slider 27 a of the second slide base 27 is engaged with the second guide rail 26, and the second slide base 27 in the main shaft direction with respect to the first slide base 24 with the pulling motor 25 as a drive source. It is slidably supported. The sliding of the second slide base 27 is performed by rotational driving of a ball screw mechanism (not shown) that is connected to the drive shaft of the attracting motor 25 and is provided on the second slide base. This ball screw mechanism is provided with a load cell (not shown) as load detecting means. The attracting motor 25 is fixedly installed on the first slide base 24.
[0021]
On the upper surface of the second slide base 27, a driving mechanism for the main shaft 40, which includes a main shaft rotating motor 28, a driving belt 29, and the like, is installed. The main shaft 40 is rotatably supported by a bearing 31 and a sliding main body 30. A bobbin tool 50 is attached to one end of the main shaft 40, and the other end is connected to the main shaft rotation motor 28 via a drive belt 29.
As a result, the first slide base 24 and the second slide base 27 can be independently slid in the axial direction parallel to the main shaft 40 with respect to the base 21 fixed to the floor surface or the like.
[0022]
FIG. 2 is a cross-sectional view of the main part showing the internal structure of the bobbin tool 50 and the sliding main body 30 attached to the tip of the main shaft 40. In the figure, reference numeral 40 is a main shaft, 41 is an inner shaft, 42 is an outer shaft, 43 is a spline coupling portion, 50 is a bobbin tool, 51 is a front shoulder portion (first shoulder portion), and 52 is a back shoulder portion ( (Second shoulder portion) 53 is a connecting pin.
[0023]
The main shaft 40 includes an inner shaft 41 connected to the main shaft rotation motor 28 via the drive belt 29 and an outer shaft 42 splined to the inner shaft 41. The outer shaft 42 is a hollow shaft, and is connected to the inner shaft 41 inserted therein by a spline coupling portion 43. By adopting the spline coupling portion 43 as a connecting structure between the inner shaft 41 and the outer shaft 42, the inner shaft 41 and the outer shaft 42 can be moved relative to each other in the axial direction and can transmit a rotational force. It has become.
The main shaft 40 is also supported by a bearing 32 installed inside the sliding main body 30 in addition to the bearing 31 described above. The bearing 32 rotatably supports the outer periphery of the outer shaft 42, and the bearing 31 rotatably supports the outer periphery of the inner shaft 41. As a result, the spline-coupled main shaft 40 can rotate as a whole. ing.
[0024]
The spline coupling portion 43 can maintain the strength necessary for transmitting the rotational force even when the inner shaft 41 and the outer shaft 42 are relatively moved in the axial direction within a predetermined range. In the illustrated example, the spline 43a on the inner shaft 41 side is set longer in the axial direction than the spline 43b on the outer shaft 42 side, and the short outer shaft side spline 43b is always connected to the spline 43a on the inner shaft 41 side over the entire length in the axial direction. It is designed to engage.
[0025]
The bobbin tool 50 includes an outer shaft coupling portion 50A having a front shoulder portion 51 and an inner shaft coupling portion 50B having a back shoulder portion 52. The bobbin tool 50 is a rotary tool that can be exchangeably attached to the main shaft 40.
The outer shaft coupling portion 50A is screwed onto the end portion of the outer shaft 42 so as to rotate integrally. A surface shoulder 51 is formed on the front end surface in the axial direction of the outer shaft connecting portion 50A, that is, the front end surface facing the workpiece W. In addition, a hollow portion 54 is formed in the outer shaft coupling portion 50A, and one end of the inner shaft 41 is inserted into the hollow portion 54. In the hollow portion 54, the inner shaft 41 does not engage with the outer shaft connecting portion 50A.
[0026]
Further, the outer shaft coupling portion 50A includes a communication hole 55 that allows the inside and the outside of the hollow portion 54 to communicate with each other. The communication hole 55 serves as a fluid outlet from which a fluid such as air or inert gas supplied from a supply source (not shown) is ejected toward the periphery of the friction stir joint of the workpiece W.
In general, air is used for the purpose of cooling, and an inert gas such as argon gas is used for controlling the atmosphere for the purpose of preventing oxidation.
[0027]
The inner shaft connecting portion 50 </ b> B is attached to the distal end portion of the inner shaft 41 via a connecting pin 53. In the inner shaft coupling portion 50B, a back surface side shoulder portion 52 is formed on the front end surface facing the workpiece W.
The connecting pin 53 is provided with a hexagonal bolt head 53 a at one end, and the other end is screwed into the inner shaft 41. The connecting pin 53 is provided with a probe portion 53b. The probe portion 53b is a portion that is embedded in the joint portion of the workpiece W and plastically fluidizes the material, and is formed in a region that is longer in the axial direction than the plate thickness of the workpiece W. The connecting pin 53 including the probe portion 53b is made of a material harder than the metal of the workpiece W.
[0028]
On the other hand, a hexagonal hole is formed at the other end of the inner shaft connecting portion 50B so as to engage with the bolt head 53a. The connecting pin 53 is inserted from the hexagonal hole, passes through the inner shaft connecting portion 50 </ b> B, the workpiece W, the pin through hole 56 and the hollow portion 54, and is screwed to the tip of the inner shaft 41. As a result, the bolt head 53a of the connecting pin 53 is accommodated in the hexagonal hole, and the rotation of the inner shaft 41 is transmitted to the connecting pin 53 via the screwing portion. Is transmitted to the internal connecting part 50B.
The rotational speed of the inner shaft connecting portion 50B is the same as that of the outer shaft connecting portion 50A because the inner shaft 41 and the outer shaft 42 are spline-coupled.
[0029]
Below, the effect is demonstrated about the friction stir welding apparatus 20 of the structure mentioned above.
The bobbin tool 50 attached to the main shaft 40 holds the workpiece W between the front shoulder portion 51 and the rear shoulder portion 52 and rotates using the main shaft rotation motor 28 as a drive source. At this time, if the pressing motor 22 is driven to move the first slide base 24 in an appropriate amount in the direction of the workpiece W (indicated by the white arrow 57 in FIG. 2), the workpiece W is removed from the surface shoulder 51. A desired pressure acts on the surface of the film. This applied pressure is feedback controlled so as to be constant based on the detected value of the load cell provided in the above-described ball screw mechanism.
[0030]
Further, when the pulling motor 25 is driven to move the second slide base 25 in the direction opposite to the workpiece W (indicated by the arrow 58 in FIG. 2), the workpiece from the back shoulder portion 52 is moved. A desired pressure is applied to the back surface of W. Similar to the surface side shoulder portion 51 described above, this applied pressure is feedback controlled so as to be constant based on the detected value of the load cell provided in the above-described ball screw mechanism.
[0031]
As a result, the workpiece W between the front shoulder portion 51 and the rear shoulder portion 52 receives a predetermined pressure from both the front and back surfaces and is heated almost uniformly, and the probe portion of the connecting pin 53 that rotates at the same rotational speed as the main shaft 40. Friction stir welding is performed by plastically fluidizing the material in the softened region where 53b is formed at the joint.
The workpiece W is supported by a feeding device (not shown) and moved in a desired direction along the joining line.
[0032]
Now, during the above-described friction stir welding, when the plate thickness varies in the workpiece W, the distance between the shoulder portions 51 and 52 varies, so the applied pressure varies. However, in the friction stir welding apparatus 20 described above, the front shoulder 51 that presses and presses the surface of the workpiece W and the back shoulder 52 that attracts and presses the back of the workpiece W are mutually connected in the axial direction. Since it can move independently, the applied pressure can be kept constant following the plate thickness variation.
[0033]
That is, the variable axis length bobbin tool 50 in which the interval between the shoulder portions 51 and 52 is variable can be used. Therefore, when the inner shaft 41 is attracted in the direction of the arrow 58, the connecting pin 53 can freely slide in the axial direction of the pin through hole 56 of the outer shaft connecting portion 50A, and the spline coupling portion 43 has the direction of the arrow 58. Since the inner shaft 41 attracted to the outer shaft 42 and the outer shaft 42 pressed in the direction of the white arrow 57 can freely move relative to each other in the axial direction while maintaining the transmission of the rotational force, the thickness of the workpiece W can be varied. It is possible to follow and maintain a constant pressure.
At this time, if feedback control is performed using the detected value of the load cell, the desired pressure can be more accurately maintained.
[0034]
Further, during the above-described friction stir welding, if the air is ejected from the communication hole 55 to the periphery of the joint portion of the workpiece W, particularly toward the joint completion portion, the joint completion portion can be cooled in a shorter time.
Further, during the above-described friction stir welding, if an inert gas is ejected from the communication hole 55 to the vicinity of the joint portion of the workpiece W, oxidation at the joint portion can be prevented and a good joint portion can be formed.
[0035]
By the way, in the friction stir welding described above, a hole remains at the end of the joint by pulling out the connecting pin 53 from the workpiece W after the joining is completed. This hole may be cut and removed together with surrounding members, but can also be filled by plug welding or the like.
Therefore, as shown in FIG. 3, a plug welding tool 60 is attached instead of the bobbin tool 50 attached to the tip of the main shaft 40.
[0036]
The plug welding tool 60 is pushed into the hole 62 while rotating the plug 61 held at the tip, and the contact surface (the outer peripheral surface of the plug 61 and the inner peripheral surface of the hole) is softened by frictional heat and reaches the welding temperature. Stop rotation. At this time, a backing metal 63 is required on the back side of the workpiece W to receive the pressure of the plug 61.
Note that the backing metal 63 in this case may be a relatively small one that is slightly larger than the probe portion 53b, unlike the above-described friction stir welding backing metal.
[0037]
Therefore, if the plug welding tool 60 is attached to the main shaft 40 of the friction stir welding apparatus 20 described above, the plug 61 can be rotated while pressing in the direction of the white arrow 57 shown in FIGS. That is, the outer shaft connecting portion 50A, the inner shaft connecting portion 50B, and the connecting pin 53 may be removed from the main shaft 40 of FIG. 2, and the plug welding tool 60 may be screwed onto the outer shaft 42 and attached.
Since the plug welding tool 60 is a known tool, detailed description thereof is omitted.
[0038]
As described above, if either the bobbin tool 50 or the plug welding tool 60 can be selected as a tool to be attached to the main shaft 40, the friction stir welding apparatus 20 can fill the remaining holes after the friction stir welding and the friction stir welding. Both plug welding operations can be performed. In addition, since the main shaft 40 can be shared, if the tool is replaced as it is after the friction stir welding and plug welding is performed, it is not necessary to newly perform operations such as centering.
Since there is a large difference between the spindle rotational speed when performing plug welding and the spindle rotational speed when performing friction stir welding, an appropriate speed change mechanism is provided in the spindle rotary motor 28 to cope with this rotational speed difference. In addition, since it is necessary to stop the rotation immediately after reaching the welding temperature in plug welding, it is preferable to provide a brake mechanism that can be selectively used.
[0039]
The configuration of the present invention is not limited to the above-described embodiment, and may be appropriately changed within a range not departing from the gist of the present invention, such as application to a friction stir welding apparatus in which the main shaft is arranged in the vertical direction. be able to.
[0040]
【The invention's effect】
The friction stir welding apparatus of the present invention described above has the following effects. According to the friction stir welding apparatus of the first aspect of the present invention, the first shoulder portion is connected to the outer shaft attached to the first slide base portion, and the second shaft is connected to the inner shaft attached to the second slide base portion. The first shoulder portion is pressed against the surface and pressurized, and the second shoulder portion is attracted and pressurized against the back surface, so that the first and second shoulder portions It is possible to apply pressure from both sides, and a bobbin tool with variable shaft length can also be used, which realizes sufficient heating and plastic flow in the softened area without a backing metal, and there is no poor fusion Good friction stir welding can be performed. For this reason, it becomes possible to sufficiently cope with friction stir welding when a large backing metal cannot be used, such as circumferential welding of a container.
[0041]
Also, by providing feedback control by providing load detection means on the inner shaft and outer shaft respectively, even if the workpiece has a variation in plate thickness, the applied pressure is kept constant, and a good friction stir weld with no poor fusion Can be more reliably formed.
In addition, by providing a fluid spout on the rotary tool, it is possible to control the atmosphere by injecting an inert gas around the joint, or to cool by the injected air, and there is no poor fusion In addition to the more reliable formation of the friction stir joint, it is possible to prevent discoloration due to oxidation.
[0042]
In addition, since either one of the rotary tool and the plug welding tool can be selected and attached, the hole at the end portion generated after the friction stir welding can be filled by plug welding with one apparatus.
[Brief description of the drawings]
FIG. 1 is a front view showing an embodiment of a friction stir welding apparatus according to the present invention.
2 is a cross-sectional view of a main part showing a peripheral structure of a spindle and a bobbin tool in FIG.
FIG. 3 is a diagram showing a configuration example in a state in which a plug welding tool is attached to a tip end of a main shaft.
FIG. 4 is a perspective view showing an implementation state of friction stir welding.
FIG. 5 is an explanatory view showing a mechanism of friction stir welding.
FIG. 6 is a front view showing a conventional bobbin tool (rotary tool).
FIG. 7 is a plan view showing a configuration example of a conventional friction stir welding apparatus.
[Explanation of symbols]
20 friction stir welding device 21 base 22 pressing motor 23 first guide rail 24 first slide base 25 pulling motor 26 second guide rail 27 second slide base 28 spindle rotation (tool drive) motor 30 sliding body 40 Spindle (Rotating shaft)
41 Inner shaft 42 Outer shaft 43 Spline joint 50 Bobbin tool (rotary tool)
50A Outer shaft connecting portion 50B Inner shaft connecting portion 51 Surface shoulder portion (first shoulder portion)
52 Back shoulder (second shoulder)
53 Connecting pin 54 Hollow portion 55 Communication hole (fluid outlet)
60 Plug welding tool 61 Plug W Workpiece

Claims (4)

In a friction stir welding apparatus that heats and agitates the joints of workpieces with a rotary tool and joins them without melting,
A first slide base slidably installed on a base fixed to the floor;
A second slide base that is slidably installed on the first slide base independently of the first slide base;
First and second shoulder portions that contact the front and back surfaces of the workpiece to be heated by frictional heat, and an inner shaft and an outer shaft that are connected to a drive source and splined on the same axis. A rotating shaft comprising
The outer shaft is attached to the first slide base, and the inner shaft is attached to the second slide base,
Connecting the first shoulder portion to the outer shaft and connecting the second shoulder portion to the inner shaft;
A friction stir welding apparatus, wherein the first shoulder portion is pressed against the surface and pressurized, and the second shoulder portion is attracted and pressed against the back surface.   The friction stir welding apparatus according to claim 1, wherein feedback control is performed by providing load detection means on each of the inner shaft and the outer shaft.   The friction stir welding apparatus according to claim 1 or 2, wherein a fluid ejection port is provided in the rotary tool. The rotating shaft can be mounted by selecting either the rotating tool or the plug welding tool ,
The drive source is provided with a speed change mechanism corresponding to a difference between a rotational speed when the rotary tool is attached and a rotational speed when the plug welding tool is attached and / or a brake mechanism capable of suddenly stopping the rotary shaft. The friction stir welding apparatus according to any one of claims 1 to 3.

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