JP2003181656A - Friction stir welding device and friction stir welding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stir welding device which can realize good joining without fusion failure even when any backing strip is not used. <P>SOLUTION: In this friction stir welding device wherein a joint between metal plates 1, 2 is heated and stirred with a bobbin tool 40 and the metal plates 1, 2 are joined to each other in a non-fused state, the bobbin tool 40 includes a front side shoulder part 42 and a back side shoulder part 43 which are respectively heated by frictional heat in contact with both front and back sides of the metal plates 1, 2 while sandwiching both the sides therebetween. A hydraulic cylinder 61 is provided as pressing means which makes the back side shoulder part 43 movable to a rotating shaft direction and rotatably supports and presses the back side shoulder part 43 against the direction of the metal plates 1, 2. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction stir welding apparatus and a friction stir welding method in which a plastic flow is generated at the abutting surfaces of materials to be welded to integrally bond them.

[0002]

2. Description of the Related Art In recent years, friction stir welding (Frictio) has been used as a new welding means instead of welding or brazing of metal materials.
n Stir Welding (FSW) method has been introduced. This friction stir welding method is disclosed in
As disclosed in Japanese Patent No. 5090, when a probe (rod-shaped projection) made of a material harder than a metal workpiece is brought into sliding contact with the workpiece while rotating, friction generated at this sliding contact portion Since the material of the work piece is plasticized by heat and pressure, the probe is embedded in the work piece, and
The fact that it is possible to move inside the work piece in this embedded state is used. Such a friction stir welding method is used as a welding method for relatively soft metals such as aluminum and aluminum alloys.

A conventional friction stir welding method will be briefly described below with reference to the drawings. FIG. 3 is a perspective view showing an implementation state of friction stir welding, and FIG. 4 is an explanatory view showing a mechanism of friction stir welding. For example, as shown in FIG. 3, 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 as the workpieces are butted against each other while rotating, the friction with the shoulder portion 6 is generated. The heat causes the materials of the metal plates 1 and 2 to soften. Therefore, the probe 5 can be aligned with the joining line 3 and inserted into the joining portion, and thus the probe 5 in the embedded state can be relatively moved along the joining line 3 of the fixed metal materials 1 and 2. A softened region 7 (see FIG. 4) is formed around the probe 5.

In the softening region 7, the materials of the metal plates 1 and 2 that have plastically flowed on the front side of the probe 5 are agitated and kneaded while receiving pressure, and gradually move to the rear side of the probe 5. As a result, the plastically flowed material loses frictional heat on the rear side and rapidly cools and hardens, so that the metal plates 1 and 2 are joined together in a completely integrated state. By providing the probe 5 with the reverse screw 5a with respect to the rotation direction, downward plastic flow as shown by an arrow in FIG. 4 occurs, so that there is a material-free space (a nest) on the back surface side that tends to be lower than the surface temperature. Is less likely to cause defects and fusion defects.

In this case, the temperature at which the metal material plastically flows is much lower than the melting point, and the joining is in the category of solid-state joining.
The amount of heat input to the metal material during the joining process is extremely small compared to welding and brazing, and there is no stress due to solidification shrinkage, so there is an advantage that deformation and cracks due to thermal strain in the vicinity of the joint are less likely to occur. .

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 welding. Therefore, in order to cope with the reaction force, the backing plate 8 is used. Is used. 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, 8
It receives a reaction force of a large pressing force of about 000 to 18,000 N or more.

Further, the rotary tool 4A called a bobbin tool shown in FIG. 5 has a pair of shoulder portions 6a, 6b provided at a constant interval so as to sandwich both front and back surfaces of the metal plates 1, 2 to be joined. It is provided. In this case, since the probe 5 is provided between the pair of upper and lower shoulder portions 6a and 6b, friction heat can be generated on both surfaces of the joint portion, and defective fusion on the back surface side is unlikely to occur.

[0008]

By the way, according to the above-mentioned conventional technique, the backing metal 8 is closely attached to the back side of the metal plates 1 and 2 to be bonded, because the pressure reaction force at the time of bonding is received. There is a need. Therefore, when the friction stir welding is applied to a part having a long joining line 3, it is necessary to install a large backing metal 8 capable of covering the distance that the rotary tool 4 moves along the joining line 3. It should be noted that unless the rotary tool 3 is pressed to apply pressure, there is a risk of defective fusion or a space free of material at the joint, which is not preferable.

When joining metal plates into a cylindrical shape, it is necessary to install a large backing metal 8 inside the cylinder. In particular, in a cylindrical shape such as a container having a narrow entrance / exit, it is impossible to install a jig such as a backing metal 8 which is large in size to withstand a reaction force, and therefore friction stir welding cannot be adopted. It is the actual situation. Further, if the metal plates 1 and 2 to be joined have a variation in plate thickness, the pressure applied by the rotary tool becomes non-uniform, so that the plastic flow in the softened region 7 becomes insufficient and fusion defects are likely to occur on the back surface side. I have a problem.
In the above-mentioned conventional bobbin tool 4A, since the upper and lower shoulder portions 6a and 6b are fixed in the axial direction and have constant intervals, it is not possible to cope with variations in plate thickness.

The present invention has been made in view of the above circumstances, and provides a friction stir welding apparatus and a friction stir welding method capable of performing good welding without defective fusion without using a backing metal. Has an aim.

[0011]

The present invention adopts the following means in order to solve the above problems. The friction stir welding apparatus according to claim 1, wherein in a friction stir welding apparatus that heats and stirs a welded portion of a workpiece with a rotating tool and welds the workpiece as it is in a non-melted state, the rotating tool has front and back surfaces of the workpiece. It has a shoulder part that contacts so as to sandwich it and heats it by frictional heat, the back side of the work piece of the shoulder part can be moved in the rotation axis direction, and the back side of the work piece of the shoulder part can be rotated. It is characterized in that a pressurizing means which is supported by and is pressed against the workpiece is provided.

According to such a friction stir welding apparatus, the rotary tool is provided with a shoulder portion which contacts the front and back surfaces of the workpiece so as to sandwich them and heats them by frictional heat. Is movable in the direction of the rotation axis, and the pressurizing means for rotatably supporting the back surface side of the workpiece of the shoulder portion and pressing the shoulder portion toward the workpiece is provided. The back surface side of the part of the work piece comes into close contact with the back surface of the work piece and functions as a backing plate. Further, since the shoulder portion enables heating from the back surface, the heat input efficiency can be improved. Further, since the back surface side of the shoulder portion is movable in the rotation axis direction, it is possible to cope with variations in plate thickness.

In the friction stir welding apparatus according to the first aspect of the present invention, it is preferable that the pressurizing means is provided with a pressurizing force detecting means, whereby the pressurizing force by the pressurizing means can be feedback-controlled.

In the friction stir welding apparatus according to the first or second aspect, it is preferable that the supporting means for rotatably supporting the back side of the workpiece in the shoulder portion is provided with a cooling means. It is possible to suppress the temperature rise of the member that rotatably supports the back surface side of the workpiece of the shoulder portion by being pressed by the means.

In the friction stir welding apparatus according to any one of claims 1 to 3, it is preferable that the workpiece be moved and welded to the rotary tool that rotates while being fixed at a predetermined position. In particular, it is more effective when joining workpieces that require a large backing metal.

A friction stir welding method according to a fourth aspect of the present invention is a friction stir welding method in which a joined portion of a workpiece is heated and agitated by a rotating tool to join the workpiece in an unmelted state, wherein the rotating tool is the workpiece. Provide a shoulder part that contacts both sides of the front and back and heats by frictional heat, and attach the shoulder part back side of the workpiece movably in the direction of the rotation axis and press it against the back side of the workpiece with a predetermined pressure It is characterized in that they are bonded while being pressed.

According to such a friction stir welding method, the rotary tool is provided with a shoulder portion which comes into contact with the front and back surfaces of the workpiece so as to sandwich the workpiece and heats it by frictional heat. Is attached so that it can move in the direction of the rotation axis, and it is pressed against the back surface of the work piece with a predetermined pressure to join while pressing, so the back surface side of the work piece of the shoulder portion adheres to the back surface of the work piece and functions as a backing plate To do. In this case, in order to maintain the predetermined pressure, it is preferable to provide a pressing force detection means and perform feedback control of the detected value of the pressing force.

In the friction stir welding method according to the fifth aspect of the present invention, it is preferable that the rotary tool is rotated while being fixed at a predetermined position, and the workpiece is moved to perform the welding. It is more effective when joining the workpieces that require.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a friction stir welding apparatus and a friction stir welding method according to the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the main configuration of the friction stir welding apparatus. The joining lines of the metal plates 1 and 2 which are the workpieces are joined by the bobbin tool 40 of the rotary tool relatively moving while rotating while pressing the surface of the workpieces.

For example, as shown in FIG. 2, the bobbin tool 40 includes a cylindrical main body 41, a front surface side shoulder portion 42 formed on the lower end surface of the main body 41, and a rear surface side shoulder portion separate from the main body 41. It comprises a lower body 44 having 43 and a connecting pin 45 having a probe portion 45a made of a material harder than the metal of the workpiece.

The upper portion of the main body 41 is connected to a drive source (not shown) (electric motor, etc.) to rotate, and further receives a pressing force pressed toward the surface of the workpiece by an upper pressing means (not shown). There is. On the other hand, the lower main body 44 is arranged so that the back surface side shoulder portion 43 faces the front surface side shoulder portion 42 described above, and is integrated by a connecting pin 45 inserted in the arrow direction so as to penetrate the main body 41 from below. It Therefore, the lower body 44 can move in the axial direction along the connecting pin 45. A hexagonal hole 44a is provided on the lower surface of the lower body 44, and the peripheral lower surface serves as a pressing surface 44b.

The upper end of the connecting pin 45 is fixed to the main body 41 by a fixing pin 46 at a predetermined position. Also,
The lower end of the connecting pin 45 has a hexagonal bolt head 45b.
Is provided, and the bolt head 45b is attached to the lower body 4
It is stored in four hexagonal holes 44a. As a result, the rotation of the main body 41 is transmitted to the connecting pin 45 via the fixing pin 46,
Further, from the bolt head 45b of the connecting pin 45 to the hexagon socket 4
Since it is transmitted to the lower main body 44 via the 4a,
The bobbin tool 40 including the lower body 44, the lower body 44, and the connecting pin 45 rotates together at the same rotation speed. The bolt head 45 of the connecting pin 45
Instead of the rotational force transmission structure by b and the hexagonal hole 44a, for example, a spline connection that can move freely in the axial direction may be adopted.

The probe portion 45a such as a reverse screw provided on the connecting pin 45 is provided so as to cover the plate thickness of the workpiece sandwiched between the front surface side shoulder portion 42 and the back surface side shoulder portion 43. There is. Therefore, in order to increase versatility, the probe portion 4 that is long in the axial direction of the connecting pin 45 is used.
It is preferable to provide 5a so that it can cope with a wide range of plate thicknesses.

Lower body 44 of bobbin tool 40 described above
Are rotatably supported by a support member 50 such as a bearing. Further, below the support member 50, a pressure means 60 for pressing the lower body 44 toward the back surface side of the workpiece is provided. The support member 50 and the pressurizing means 60 are fixed by appropriate means at appropriate places on the frame member shown by imaginary lines in the figure.

The support member 50 includes a first bearing 51 that receives a load in the axial direction of the connecting pin 45 that also functions as a rotation shaft, and a second bearing 52 that supports the outer peripheral surface of the lower body 44. . In addition, the above-mentioned first and second
Cooling chambers 53a, 53b, 53c are provided around the bearings 51, 52 as cooling means. In these cooling chambers 53a, 53b, 53c, a medium such as cooling water introduced from the cooling water introduction pipe 54 and flowing out from the drain pipe 55 circulates to remove the heat generated in the bearing sliding portion and rise in temperature. Can be suppressed. The cooling water introduction pipe 54 and the drainage pipe 55 are provided with flexible pipes that absorb vertical movement at appropriate places. The first bearing 51 and the second bearing 52 may be fluid bearings, for example, and in this case, the cooling means may be omitted.

As the pressurizing means 60, for example, a hydraulic cylinder 61 is used. The hydraulic cylinder 61 is installed so that the piston rod 62 projects upward and the tip 63 pushes up the pressing surface 44 b of the lower body 44. In the illustrated example, the first bearing 51 is installed at the upper end of the tip 63. A load cell 70 is provided below the hydraulic cylinder 60 as a pressing force detecting means. The load cell 70 is a sensor for detecting the pressing force of the pressurizing means 60 and performing feedback control so as to maintain the pressing force at a predetermined value.

Hereinafter, the friction stir welding method of the present invention will be described together with the operation of the friction stir welding apparatus having the above-described structure. In the friction stir welding method of the present invention, the workpiece side is fixed relative to the friction stir welding apparatus that is fixedly installed on the workpiece side along the joining line that joins the joining surfaces of the metal plates 1 and 2 to be the workpiece. Move to. The metal plates 1 and 2 of the workpiece
Are each fixed to a known feeding device.

In the bobbin tool 40, when the joining is started from the outside of the ends of the workpieces, the lower main body 44 is previously attached to the main body 41.
Attach it to. After that, the outer peripheral surface of the lower body 44 is rotatably supported by the second bearing 52, and further, the first bearing 5 attached to the tip portion 63 of the piston 61.
1 is brought into contact with the pressing surface 44b. Then, the front surface side shoulder portion 42 is pressed against the surface of the work piece, and the piston 61 is operated to press the back surface side shoulder portion 43 against the back surface of the work piece, so that the end portion of the work piece is moved to both shoulder parts 42, 43. It is clamped on the forward side. In this sandwiched state, the probe portion 45a of the connecting pin 45 is set so as to match at least the plate thickness portion of the workpiece.

When the bobbin tool 40 is rotated from this state to start joining, the bobbin tool 40 is rotated while being pressed (pressed) by the workpiece, and the bobbin tool 40 is rotated between the probe portion 45a and the shoulder portions 42 and 43. The frictional heat generated softens the materials of the metal plates 1 and 2. Therefore, when the feeding device that fixes the workpiece is operated, the probe portion 45a is embedded in the material along the joint portion. Then, by further moving the workpiece relatively, a softened region 7 (see FIG. 4) is generated, and the material that has plastically flowed in front of the probe portion 45a is agitated and kneaded while receiving pressure from both shoulder portions 42 and 43. , And gradually shifts to the rear side of the probe portion 45a.

As a result, the plastically flowed material is rapidly cooled and hardened on the rear side of the probe portion 45a where there is no frictional heat, so that the metal plates 1 and 2 are completely joined together in a state where the materials are mixed. At this time, the metal plates 1 and 2 to be the workpieces
The joint portion is heated by frictional heat under pressure from the shoulder portions 42 and 43 on both front and back surfaces. Therefore, since the back surface side shoulder portion 43 pressurizes the back surface side of the workpiece, the backing metal required in the conventional apparatus is not necessary. In addition, the temperature difference between the front and back sides of the workpiece is less than that in conventional one-sided heating, and the heat input efficiency is also improved.

Therefore, even if the backing metal is not used, the material mixing and the material distribution in the joint portion are uniform, and in particular, the fusion failure on the back surface, which has been a problem in the conventional one-sided heating, cannot be performed, and the inside of the joint portion cannot be formed. The quality can be improved. That is, stable and highly reliable bonding becomes possible.

Further, unlike the fixed type bobbin tool 4A (see FIG. 5), the lower body 44 having the rear surface side shoulder portion 43 is configured to be movable in the rotation axis direction. Even if there is a thickness variation, it is possible to follow and pressurize. At this time, since the load cell 70 detects the pressing force, for example, when the plate thickness changes and the pressing force also changes, feedback control is performed using this detected value as described below.

For example, when the plate thickness becomes thin and the pressing force decreases, the amount of oil supplied to the hydraulic cylinder 61 is increased to push up the piston rod 62, and the operation is performed so as to maintain a predetermined pressing force. As a result, since the lower main body 44 is pushed up and moves along the connecting pin 45, the back surface side shoulder portion 43 can maintain a predetermined pressing force and maintain close contact with the workpiece.

On the contrary, when the plate thickness becomes thick and the pressurizing force rises, the amount of oil in the hydraulic cylinder 61 is reduced to lower the piston rod 62 and the predetermined pressurizing force is maintained. As a result, the lower main body 44 and the piston rod 62 move downward by an amount corresponding to the increase in the plate thickness, and the back surface side shoulder portion 43 can maintain a predetermined pressing force and maintain close contact with the workpiece.

By feedback-controlling the pressure applied to the hydraulic cylinder 61 in this manner, it becomes possible to cope with the variation in the plate thickness of the workpiece, which also improves the internal quality and stabilizes the reliability. It is possible to achieve high bonding. In addition to the feedback control of the back surface side shoulder portion 43 described above, the pressing force of the main body 41
For example, the well-known control of moving the main body 41 in the vertical direction based on the result of detecting the surface height variation of the portion to be joined by laser measurement or the like may be used together. It is possible to further stabilize the quality and improve the reliability.

By the way, in the above-mentioned embodiment, in the ordinary friction stir welding, the cooling means for introducing the cooling water is provided for the purpose of cooling the first and second bearings 51 and 52 in which the temperature rise becomes a problem. However, the pressing force and rotation speed,
Depending on the conditions such as the material and type of the bearing itself, the cooling means may not be required. Further, the load cell 70 provided as the pressing force detecting means may not be provided if the hydraulic pressure of the hydraulic cylinder 61 can be kept constant, such as when the plate thickness of the workpiece does not vary or is extremely small.

In the friction stir welding apparatus and the friction stir welding method described above, the side of the workpiece is moved, but it is also possible to move the welding apparatus while fixing the side of the workpiece. However, compared with the case of moving the friction stirrer side provided with the pressurizing means 60 such as the hydraulic cylinder 61 that gives a large pressure, when the workpiece side is moved and joined, the operation is easy and the device configuration is improved. Is also preferable because it is easy.

The structure of the present invention is not limited to the above-mentioned embodiment, and can be appropriately modified within the scope of the present invention.

[0039]

According to the friction stir welding apparatus and the friction stir welding method of the present invention described above, the following effects can be obtained. According to the friction stir welding apparatus of the present invention as set forth in claim 1, the rotary tool is provided with a shoulder portion which comes into contact with the front and back surfaces of the workpiece so as to sandwich them and heats them by frictional heat. Since the back surface side of the work piece is movable in the rotation axis direction, and the back surface side of the work piece of the shoulder portion is rotatably supported and the pressing means is provided to press the work piece in the direction of the work piece, the pressing means is provided. The back surface side of the work piece of the shoulder portion pressed by is closely attached to the back surface of the work piece and functions as a backing plate. Therefore, the conventional backing plate is not required, and if the work piece is moved, a mechanism for driving the lower main body of the rotary tool to rotate and pressurize it is sufficient.

Further, since the shoulder portion enables heating from the back surface of the processed portion, the heat input efficiency is improved by heating from both the front and back surfaces, and the temperature difference in the softened region can be reduced. Therefore, the entire joint is uniformly fused, and the fusion failure caused by the temperature difference is eliminated, so that the internal quality of the joint can be improved. Therefore, it is possible to increase the feeding speed of the work piece to speed up the friction stir welding and shorten the working time.

Further, since the back surface side of the shoulder portion is movable in the direction of the rotation axis, it is possible to cope with the variation in the plate thickness of the workpiece, and the predetermined pressurizing force is maintained to improve the internal quality of the joint portion. There is also an improving effect. In particular, when the pressurizing means includes a pressurizing force detecting means, the pressurizing force detected by the pressurizing means can be feedback-controlled and maintained at a predetermined value, so that the internal quality of the joint is stable. And more reliable bonding is possible. Further, since the supporting means for rotatably supporting the back side of the workpiece of the shoulder portion is provided with the cooling means, the back side of the workpiece of the shoulder portion is rotatably supported while being pressed by the pressing means. It is possible to suppress an increase in temperature of a member such as a bearing, which improves the durability and reliability of the device.

According to the friction stir welding method of the fourth aspect, the rotary tool is provided with a shoulder portion that contacts the workpiece so as to sandwich the front and back surfaces of the workpiece and heats it by frictional heat, and the workpiece of the shoulder portion is provided. The back side is attached so that it can move in the direction of the rotation axis, and it is pressed against the back side of the work piece with a predetermined pressure to bond it while applying pressure. Function as
The rotary tool can be rotated while being fixed at a predetermined position, and the workpieces can be moved and joined.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing an embodiment of a friction stir welding apparatus according to the present invention.

2 is a perspective view showing the bobbin tool structure of FIG. 1. FIG.

FIG. 3 is a perspective view showing an implementation state of friction stir welding.

FIG. 4 is an explanatory diagram showing a mechanism of friction stir welding.

FIG. 5 is a front view showing a conventional bobbin tool (rotary tool).

[Explanation of symbols]

1, 2 metal plate (workpiece) 3 joining line 40 bobbin tool (rotary tool) 41 body 42 Front shoulder 43 Back side shoulder 44 Lower body 44a Hexagon socket 44b Pressing surface 45 connecting pin 45a probe part 45b bolt head 46 fixed pin 50 Support member 51 first bearing 52 Second bearing 53a, 53b, 53c Cooling chamber 60 Pressurizing means 61 hydraulic cylinder 62 piston rod 63 Tip 70 load cell (force detection means)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiromasa Kamei             2-8-19 Niihama, Arai-cho, Takasago-shi, Hyogo             Takaryo Engineering Co., Ltd. F-term (reference) 4E067 AA05 BG00 CA02 CA03 EC01

Claims (6)

[Claims] 1. A heating tool for heating a joint of workpieces
In a friction stir welding apparatus that stirs and joins without melting, a rotary tool is provided with a shoulder portion that contacts the front and back surfaces of the workpiece so as to sandwich them and heats by frictional heat. A friction stirrer characterized in that the back side of the object is movable in the rotation axis direction, and the pressurizing means for rotatably supporting the back side of the workpiece of the shoulder portion and pressing the shoulder toward the workpiece is provided. Joining device. 2. The friction stir welding apparatus according to claim 1, wherein the pressurizing unit includes a pressing force detecting unit. 3. The friction stir welding apparatus according to claim 1, wherein the support means for rotatably supporting the back side of the workpiece of the shoulder portion includes a cooling means. 4. The friction stir welding apparatus according to claim 1, wherein the workpiece is moved and welded to the rotary tool that rotates in a state of being fixed at a predetermined position. . 5. A rotary tool heats the joint of the workpieces.
In a friction stir welding method of stirring and joining as it is in a non-melted state, the rotating tool is provided with a shoulder portion that contacts and heats by frictional heat so that both sides of the workpiece are sandwiched, A friction stir welding method, characterized in that the back side of the object is movably attached in the direction of the rotation axis, and the back surface of the workpiece is pressed at a predetermined pressure and bonded while being pressurized. 6. The friction stir welding method according to claim 5, wherein the rotary tool is rotated while being fixed at a predetermined position, and the workpiece is moved and welded.