JP2022052051A - Method of joining dissimilar metals - Google Patents

Abstract

To join two metal members of different types well by frictional agitation joining.SOLUTION: A method of joining dissimilar metals includes arranging a first metal member 10 and a second metal member 20 of different kinds from each other adjacently so as to create substantially no clearance, inserting an axially rotating rotary tool 30 its front side relative to the first metal member 10 so that the outer peripheral edge of the rotary tool 30 substantially coincides with a boundary 3 between the first metal member 10 and the second metal member 20, and moving the rotary tool 30 along the boundary 3 in that state, thereby joining the first metal member 10 and the second metal member 20 by frictional agitation. A reverse side pressing tool 40 for holding metal flowing due to the frictional agitation is provided so as to face the reverse sides of the first metal member 10 and the second metal member 20, and the reverse side pressing tool 40 is moved along the boundary 3 in synchronization with movement of the rotary tool 30.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for joining dissimilar metals by joining two metal members of different types by friction stir welding.

Friction stir welding is one of the joining techniques for members. Using a cylindrical rotary tool, the rotary tool is rotated and pressed against the joint between the members to be inserted for joining. A plurality of members are integrated by softening the member by the frictional heat generated when the rotary tool is penetrated and plastically flowing the periphery of the joint portion by the rotational force of the rotary tool.

Compared with arc welding, for example, such friction stir welding has the advantage that the heat effect of the joint can be suppressed and noise and dust are less generated because the member does not melt. Further, as compared with electron beam welding, there is an advantage that the device can be miniaturized because a vacuum is not required for the joining environment.

For example, when joining by butting the end faces of two aluminum plates, a rotary tool is inserted from directly above the joining line and the rotary tool is moved along the joining line to join the two plates. Is done.

As prior art documents relating to such friction stir welding, the applicant is aware of Patent Documents 1 and 2 below.

Japanese Unexamined Patent Publication No. 2007-136544 Japanese Patent No. 4599608

The above-mentioned Patent Document 1 relates to a technique for joining aluminum alloy plates by a friction joining method, and has the following description.
[0014]
Hereinafter, the present invention will be described with reference to FIGS. 1 to 3. In FIG. 1, the plates 10 and 20 are the first member and the second member, respectively, which are butted against each other. The materials of the plates 10 and 20 are aluminum alloys. The back surfaces of the plates 10 and 20 are mounted on a gantry (not shown).
[0015]
In this state, first, the overlay 30 is rotated while being pressed against the upper surface of the butt portion from above in a state of being in contact with the butt portion, and then relatively moved along the butt portion while being further rotated. The overlay material 30 is a round bar, and the material thereof is an aluminum alloy material similar to the plates 10 and 20. As a result, the build-up bead 35 is joined to the upper surface of the butted portion as the build-up material 30 moves.
[0023]
Next, as shown in FIGS. 4 to 6, the center pin 51 of the rotary tool 50 is inserted into the overlay bead 35 from above, and the members 10 and 20 are friction stir welded. At the time of friction stir welding, the bottom surface 53 of the large diameter portion provided on the upper part of the center pin 51 of the rotary tool 50 comes into contact with the overlay bead 35.
[0025]
Next, if necessary (when the upper surface is the outer surface of the device or when a smooth surface is required), the portion protruding from the surface of the members 10 and 20 of the friction stir welding bead 55 is removed by cutting. ..

The above-mentioned Patent Document 2 relates to a backing jig for friction stir processing, and has the following description.
[0023]
Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view for explaining an example of a friction stir welding method as the friction stir welding method of the present invention. In FIG. 1, reference numeral 10 is a backing jig, and a cement molded body is used as the backing jig 10.
[0028]
A method of performing friction stir welding (FSW) as the friction stir welding method of the present invention using the above-mentioned backing jig 10 will be described.
In FIG. 1, first, a thin layer body 20 having a smooth surface is arranged at a desired position on the backing jig 10. As the thin layer body 20 having a smooth surface, a metal foil such as a steel foil, an aluminum foil, a titanium foil, and a copper foil, and a ceramic sprayed film such as a metal or a metal oxide are preferably used, but the thin layer body 20 is not limited thereto. The thickness of the thin layer body 20 having a smooth surface is preferably about 0.05 to 1 mm in order to easily follow the surface of the backing jig 10. The metal foil may be referred to as a metal ribbon or a metal sheet.
[0031]
After that, a rotating tool 40 for joining (a tool 40 made of a hard tool steel having a shoulder portion 42 having a large diameter and a probe 41 at the tip thereof) that rotates at high speed at one end of the joining line 33 of the plate-shaped materials to be joined 31 and 32). The probe 41 is pressed and inserted with a strong force while rotating at high speed, and the tool 40 is moved to the other end along the joining line 33 while applying pressure by the shoulder portion 42 to generate frictional heat. Is plasticized and joined in a solid state. The tool is inserted from the normal direction of the surface near the joint portion of the material to be joined and is moved while maintaining the normal direction.

The above-mentioned Patent Document 1 relates to a technique for joining the same kind of metal (aluminum alloys). Disclosed is a method in which the boundary where two metal plates are butted and the rotation axis of a rotary tool are aligned with each other, and plastic flow is generated in both of the two metal plates that are butted together to be joined.

However, when an attempt is made to join dissimilar metals by the technique of Patent Document 1, two kinds of metals flow to each other on the opposite side in the joining portion, and the region becomes a non-uniformly mixed region. In regions where dissimilar metals are mixed, the mixed dissimilar metals may act as inclusions. Further, in such a region, voids are likely to occur due to metal scattering or the like due to vigorous plastic flow. Therefore, it may cause a decrease in joint strength over the entire joint. Moreover, even if an attempt is made to perform a non-destructive inspection of voids by ultrasonic waves, the mixed dissimilar metals become noise, and a decent inspection result cannot be obtained. The presence of such inclusions and voids may promote deterioration of the joint portion over time, which is a fatal problem in the joining technology that requires long-term reliability.

In addition, the hardnesses of dissimilar metals often do not match, and the viscosities during plastic flow are also different. Therefore, when the rotary tool is inserted and moved at the boundary between metals having different hardness and viscosity, a force is generated in the direction orthogonal to the moving direction, and a large load is applied to the rotary tool. In addition, there is a problem that the metal having a higher viscosity during plastic flow adheres to the rotary tool.

Further, in the case of friction stir welding of two metal plates as in Patent Document 1, each metal plate installed on the substrate is fixed with a jig. At this time, if the rotary tool is deeply inserted to the bottom surface of the metal plate, the tip thereof reaches near the surface of the base material, and as a result, the metal plate is joined to the base material. For this reason, the rotary tool can only be inserted slightly away from the surface of the board. Then, the plastic flow becomes insufficient in the vicinity of the bases of both metal plates, and an unjoined region where the butt boundary is insufficiently joined is generated. Such an unbonded region can be removed by cutting by the thickness thereof, but an extra process is required for post-processing and material loss is large. The backing jig 10 of Patent Document 2 cannot prevent the occurrence of such an unjoined region.

The present invention has been made with the following object in order to solve the above problems.
It provides a method for joining dissimilar metals that can satisfactorily join two metal members of different types by a friction stir welding method.

The method for joining dissimilar metals according to claim 1 employs the following configuration in order to achieve the above object.
The first metal member and the second metal member of different types are arranged adjacent to each other so that there is substantially no gap.
An axially rotating rotary tool is inserted into the first metal member from the front side so that the outer peripheral edge of the rotary tool substantially coincides with the boundary between the first metal member and the second metal member.
A method for joining dissimilar metals by frictionally stirring the first metal member and the second metal member by moving the rotary tool along the boundary in that state.
There is a back side pressing tool for holding the metal flowing by the friction stir welding so as to face the back side of the first metal member and the second metal member.
The back side pressing tool is moved along the boundary in synchronization with the movement of the rotary tool.

As the method for joining dissimilar metals according to claim 2, the following configuration is adopted in addition to the configuration according to claim 1.
The rotary tool inserted from the front side into the first metal member is inserted so that the tip thereof reaches the back side.

As the method for joining dissimilar metals according to claim 3, in addition to the configuration according to claim 2, the following configuration is adopted.
The back side pressing tool is provided with an interference prevention space for preventing interference with the tip of the rotary tool.

As the method for joining dissimilar metals according to claim 4, in addition to the configuration according to any one of claims 1 to 3, the following configuration is adopted.
The back side pressing tool is gradually placed in a region facing the back side of the first metal member and the second metal member and straddling the boundary with the back side toward the rear in the moving direction of the back side pressing tool. There is a back slope that reduces the gap.

As the method for joining dissimilar metals according to claim 5, in addition to the configuration according to any one of claims 1 to 4, the following configuration is adopted.
The back side pressing tool is provided with back side bank-like portions for blocking the metal flowing by friction stir welding on both sides of the boundary facing the back side of the first metal member and the second metal member. There is.

As the method for joining dissimilar metals according to claim 6, in addition to the configuration according to any one of claims 1 to 5, the following configuration is adopted.
There is a front side pressing tool for holding the metal flowing by the friction stir welding so that the first metal member and the front side of the second metal member face each other.
The front pressing tool is moved along the boundary in synchronization with the movement of the rotating tool.

As the method for joining dissimilar metals according to claim 7, the following configuration is adopted in addition to the configuration according to claim 6.
The front side pressing tool is provided with a penetrating portion through which the rotating tool is inserted.

As the method for joining dissimilar metals according to claim 8, in addition to the configuration according to claim 6 or 7, the following configuration is adopted.
The front side pressing tool is gradually placed in a region facing the front side of the first metal member and the second metal member and straddling the boundary with the front side toward the rear in the moving direction of the front side pressing tool. A front slope with a small gap is provided.

As the method for joining dissimilar metals according to claim 9, in addition to the configuration according to any one of claims 6 to 8, the following configuration is adopted.
The front side pressing tool is provided with front side bank-shaped portions for blocking the metal flowing by friction stir welding on both sides of the boundary facing the front side of the first metal member and the second metal member. There is.

The method for joining dissimilar metals according to claim 10 adopts the following configuration in order to achieve the above object.
The first metal member and the second metal member of different types are arranged adjacent to each other so that there is substantially no gap.
An axially rotating rotary tool is inserted into the first metal member from the front side so that the outer peripheral edge of the rotary tool substantially coincides with the boundary between the first metal member and the second metal member.
A method for joining dissimilar metals by frictionally stirring the first metal member and the second metal member by moving the rotary tool along the boundary in that state.
There is a front side pressing tool for holding the metal flowing by the friction stir welding so that the first metal member and the front side of the second metal member face each other.
The front pressing tool is moved along the boundary in synchronization with the movement of the rotating tool.

As the method for joining dissimilar metals according to claim 11, in addition to the configuration according to claim 10, the following configuration is adopted.
The front side pressing tool is provided with a penetrating portion through which the rotating tool is inserted.

As the method for joining dissimilar metals according to claim 12, in addition to the configuration according to claim 10 or 11, the following configuration is adopted.
The front side pressing tool is gradually placed in a region facing the front side of the first metal member and the second metal member and straddling the boundary with the front side toward the rear in the moving direction of the front side pressing tool. A front slope with a small gap is provided.

As the method for joining dissimilar metals according to claim 13, in addition to the configuration according to any one of claims 10 to 12, the following configuration is adopted.
The front side pressing tool is provided with front side bank-shaped portions for blocking the metal flowing by friction stir welding on both sides of the boundary facing the front side of the first metal member and the second metal member. There is.

As the method for joining dissimilar metals according to claim 14, in addition to the configuration according to any one of claims 1 to 13, the following configuration is adopted.
The first metal member into which the rotary tool is inserted is a metal having a hardness lower than that of the second metal member.

As the method for joining dissimilar metals according to claim 15, in addition to the configuration according to any one of claims 1 to 13, the following configuration is adopted.
The first metal member into which the rotary tool is inserted is a metal having a melting point lower than that of the second metal member.

As the method for joining dissimilar metals according to claim 16, in addition to the configuration according to any one of claims 1 to 15, the following configuration is adopted.
A metal member of the same metal as the first metal member is arranged in advance in at least one of the interference prevention space of the back pressing tool, the back slope, and the front slope of the front pressing tool.

In the method for joining dissimilar metals according to claim 1, the first metal member and the second metal member are joined by friction stir welding. First, the first metal member and the second metal member of different types are arranged adjacent to each other so that there is substantially no gap. Then, the rotary tool that rotates around the axis is inserted into the first metal member from the front side so that the outer peripheral edge of the rotary tool substantially coincides with the boundary between the first metal member and the second metal member. do. Next, the dissimilar metals are joined by moving the rotary tool along the boundary in that state.
Further, in the present invention, there is a back side pressing tool for holding the metal flowing by friction stir welding so as to face the back side of the first metal member and the second metal member. Then, the back side pressing tool is moved along the boundary in synchronization with the movement of the rotary tool.
By inserting the rotary tool into the first metal member, plastic flow occurs only in the first metal member, and plastic flow hardly occurs in the second metal member. At this time, the back side pressing tool facing the back side of the first metal member and the second metal member is moved along the boundary in synchronization with the movement of the rotary tool. As a result, even if the metal is scattered due to the violent plastic flow, the metal flowing by the friction stir is pressed by the back side pressing tool, and as a result, the generation of voids can be significantly reduced. Therefore, it is possible to obtain an extremely good bonding state with few defects such as a mixture of two types of metals and voids. Therefore, non-destructive inspection by ultrasonic waves can be applied, and the reliability of the joint can be ensured.
Further, even if the rotary tool is deeply inserted close to the back side of both metal members, the metal flowing by the friction stir is pressed by the back side pressing tool, so that the unbonded region, which has been a problem in the past, hardly occurs. Therefore, post-processing by cutting becomes unnecessary, and material loss is small.
Further, by inserting the rotary tool only on the side of the first metal member, the vertical force applied to the rotary tool, which has been a problem in the past, can be greatly alleviated, and deterioration of the tool can be prevented. Further, since the rotary tool can be inserted only into the metal having a small viscosity during plastic flow, the adhesion of the metal to the rotary tool is suppressed. Therefore, it is possible to reduce the frequency of maintenance such as removing the metal adhering to the rotary tool and replacing the rotary tool.
According to the method for joining dissimilar metals of the present invention, two metal members of different types can be satisfactorily joined by a friction stir welding method.

The method for joining dissimilar metals according to claim 2 is to insert the rotary tool inserted from the front side into the first metal member so that the tip thereof reaches the back side.
Since the back side pressing tool presses the metal flowing by the tip of the rotary tool that has reached the back side, the unbonded region, which has been a problem in the past, hardly occurs. Therefore, post-processing by cutting becomes unnecessary, and material loss is small.

In the method of joining dissimilar metals according to claim 3, the back side pressing tool is provided with an interference prevention space for preventing interference with the tip of the rotary tool.
It is possible to prevent the tip of the rotary tool that has reached the back side from interfering with the back side pressing tool, and prevent damage to the rotating tool and the back side pressing tool.

In the method for joining dissimilar metals according to claim 4, the back side pressing tool moves the back side pressing tool to a region facing the back side of the first metal member and the second metal member and straddling the boundary. A back slope is provided in which the gap between the back side and the back side gradually decreases toward the rear in the direction.
When the back side pressing tool moves along the boundary in synchronization with the movement of the rotary tool, the metal flowing by the tip of the rotary tool that reaches the back side is caused by the back slope of the first. It is pushed back toward the back side of the metal member and the second metal member. Therefore, the scattering of metal is prevented and the generation of voids is greatly reduced. In addition, there is almost no unjoined region, which has been a problem in the past, post-processing by cutting is not required, and material loss is small.

In the method for joining dissimilar metals according to claim 5, the back side pressing tool uses the metal flowing by friction stirring on both sides of the boundary facing the back side of the first metal member and the second metal member. There is a backside bank for damming.
The backside bank-shaped portion blocks the metal flowing by the tip of the rotary tool that has reached the backside, thereby preventing the metal from scattering and significantly reducing the generation of voids.

In the method of joining dissimilar metals according to claim 6, the first metal member and the second metal member face each other, and a front side pressing tool for holding the metal flowing by frictional stirring exists. Then, the front side pressing tool is moved along the boundary in synchronization with the movement of the rotary tool.
Since the metal flowing by the friction stir is pressed by the front pressing tool, the generation of voids can be significantly reduced.

In the method for joining dissimilar metals according to claim 7, the front-side pressing tool is provided with a penetrating portion through which the rotating tool is inserted.
By pressing the flow of metal generated in the region around the rotary tool with the front pressing tool, the generation of voids can be significantly reduced.

In the method for joining dissimilar metals according to claim 8, the front-side pressing tool moves the front-side pressing tool to a region facing the front side of the first metal member and the second metal member and straddling the boundary. A front side slope is provided in which the gap between the front side and the front side gradually decreases toward the rear in the direction.
When the front-side pressing tool moves along the boundary in synchronization with the movement of the rotary tool, the metal flowing due to the insertion of the rotary tool becomes the first metal member and the first metal member due to the front-side slope. It is pushed back toward the front side of the metal member of 2. Therefore, the scattering of metal is prevented and the generation of voids is greatly reduced.

In the method for joining dissimilar metals according to claim 9, the front-side pressing tool uses the metal flowing by friction stirring on both sides of the boundary facing the front side of the first metal member and the second metal member. A front side bank-like part is provided for damming.
The front side bank-shaped portion blocks the metal that flows when the rotary tool is inserted, thereby preventing the metal from scattering and significantly reducing the generation of voids.

The method for joining dissimilar metals according to claim 10 is to join the first metal member and the second metal member by friction stir welding. First, the first metal member and the second metal member of different types are arranged adjacent to each other so that there is substantially no gap. Then, the rotary tool that rotates around the axis is inserted into the first metal member from the front side so that the outer peripheral edge of the rotary tool substantially coincides with the boundary between the first metal member and the second metal member. do. Next, the dissimilar metals are joined by moving the rotary tool along the boundary in that state.
In the present invention, there is a front side pressing tool for holding the metal flowing by friction stir welding by facing the first metal member and the front side of the second metal member. Then, the front side pressing tool is moved along the boundary in synchronization with the movement of the rotary tool.
By inserting the rotary tool into the first metal member, plastic flow occurs only in the first metal member, and plastic flow hardly occurs in the second metal member. At this time, the front-side pressing tool facing the front side of the first metal member and the second metal member is moved along the boundary in synchronization with the movement of the rotary tool. As a result, even if the metal is scattered due to the violent plastic flow, the metal flowing by the friction stir is pressed by the front pressing tool, and as a result, the generation of voids can be significantly reduced. Therefore, it is possible to obtain an extremely good bonding state with few defects such as a mixture of two types of metals and voids. Therefore, non-destructive inspection by ultrasonic waves can be applied, and the reliability of the joint can be ensured.
Further, by inserting the rotary tool only on the side of the first metal member, the vertical force applied to the rotary tool, which has been a problem in the past, can be greatly alleviated, and deterioration of the tool can be prevented. Further, since the rotary tool can be inserted only into the metal having a small viscosity during plastic flow, the adhesion of the metal to the rotary tool is suppressed. Therefore, it is possible to reduce the frequency of maintenance such as removing the metal adhering to the rotary tool and replacing the rotary tool.
According to the method for joining dissimilar metals of the present invention, two metal members of different types can be satisfactorily joined by a friction stir welding method.

In the method for joining dissimilar metals according to claim 11, the front-side pressing tool is provided with a penetrating portion through which the rotating tool is inserted.
By pressing the flow of metal generated in the region around the rotary tool with the front pressing tool, the generation of voids can be significantly reduced.

In the method for joining dissimilar metals according to claim 12, the front-side pressing tool moves the front-side pressing tool to a region facing the front side of the first metal member and the second metal member and straddling the boundary. A front side slope is provided in which the gap between the front side and the front side gradually decreases toward the rear in the direction.
When the front-side pressing tool moves along the boundary in synchronization with the movement of the rotary tool, the metal flowing due to the insertion of the rotary tool becomes the first metal member and the first metal member due to the front-side slope. It is pushed back toward the front side of the metal member of 2. Therefore, the scattering of metal is prevented and the generation of voids is greatly reduced.

In the method of joining dissimilar metals according to claim 13, the front-side pressing tool uses the metal flowing by friction stirring on both sides of the boundary facing the front side of the first metal member and the second metal member. A front side bank-like part is provided for damming.
The front side bank-shaped portion blocks the metal that flows when the rotary tool is inserted, thereby preventing the metal from scattering and significantly reducing the generation of voids.

In the method for joining dissimilar metals according to claim 14, the first metal member into which the rotary tool is inserted is a metal having a hardness lower than that of the second metal member.
Since the rotary tool is inserted only into the first metal member having a low viscosity during plastic flow, the adhesion of metal to the rotary tool can be suppressed, and the frequency of maintenance of the rotary tool can be reduced. In addition, the energy required to generate the plastic flow is small, which is advantageous in saving power.

In the method for joining dissimilar metals according to claim 15, the first metal member into which the rotary tool is inserted is a metal having a melting point lower than that of the second metal member.
If the melting point of the first metal member into which the rotary tool is inserted is higher, the second metal member, which is the mating material, begins to melt and joins when the temperature rises until the first metal member plastically flows. Defects and defects may occur. By using a metal having a melting point lower than that of the second metal member as the first metal member into which the rotary tool is inserted, it is possible to prevent the above-mentioned inconvenience from occurring.

The method for joining dissimilar metals according to claim 16 is a metal member of the same metal as the first metal member in at least one of the interference prevention space of the back pressing tool, the back slope, and the front slope of the front pressing tool. Is arranged in advance.
With the above configuration, as compared with the case where each of the above-mentioned portions is a space, it is not necessary to fill the first metal member therein, so that wall thinning can be avoided.

Here, in the present invention, the "front side" and "back side" simply indicate the relative positional relationship, and do not correspond to the "upper side" and "lower side" in the ground space.

It is a figure explaining the embodiment of the method of joining dissimilar metals of this invention. It is a figure explaining the positional relationship of a rotary tool, a front side pressing tool, and a back side pressing tool. It is a figure explaining the back side pressing tool. It is a figure explaining the front side pressing tool. It is a figure explaining the state which carries out the state of carrying out the method of joining dissimilar metals of the said embodiment.

Next, a mode for carrying out the present invention will be described.

1 and 2 are diagrams illustrating an embodiment of the method for joining dissimilar metals of the present invention.
FIG. 1 (A) is an exploded perspective view, and FIG. 1 (B) is a state seen from below.
2A is a top view, FIG. 2B is a cross-sectional view seen in the traveling direction of the tool, and FIG. 2C is a cross-sectional view seen in a direction orthogonal to the traveling direction of the tool.

〔Overview〕
In the method of joining dissimilar metals of the present embodiment, when the first metal member 10 and the second metal member 20, which are dissimilar metals to each other, are joined by friction stir welding, the rotary tool 30, the back side pressing tool 40, and the front side pressing are performed. Use tool 50. The rotary tool 30 is inserted into the first metal member 10 side and moved. The back side pressing tool 40 faces the back side of the first metal member 10 and the second metal member 20 and is moved in synchronization with the rotary tool 30. The front side pressing tool 50 faces the front side of the first metal member 10 and the second metal member 20 and is moved in synchronization with the rotary tool 30.

The movement of the rotary tool 30 causes a plastic flow in the first metal member 10, and the first metal member 10 and the second metal member 20 are joined by friction stir welding. The back side pressing tool 40 presses the metal on the back side that flows by friction stir welding, and the front side pressing tool 50 presses the metal on the front side that flows by friction stirring. As a result, the first metal member 10 and the second metal member 20 of different types are satisfactorily joined by friction stir welding.

[Basic process]
In the method of joining dissimilar metals of the present embodiment, the first metal member 10 and the second metal member 20 are joined by friction stir welding. The first metal member 10 and the second metal member 20 are dissimilar metals of different types from each other. The first metal member 10 and the second metal member 20 may be pure metal or alloy. In the illustrated example, the first metal member 10 and the second metal member 20 are rectangular plate members having the same thickness.

First, the first metal member 10 and the second metal member 20 are arranged adjacent to each other so that there is substantially no gap. In the illustrated example, the first metal member 10 and the second metal member 20, which are rectangular plates, are arranged so that their long sides face each other. The boundary 3 is formed at the point where the first metal member 10 and the second metal member 20 are butted against each other.

Next, the rotary tool 30 that rotates around the axis is attached to the first metal member 10 so that the outer peripheral edge of the rotary tool 30 substantially coincides with the boundary 3 between the first metal member 10 and the second metal member 20. On the other hand, insert from the front side. At this time, it is preferable that the rotary tool 30 is inserted so as to penetrate the thickness of the first metal member 10 and reach the back surface side at the tip.

Next, in that state, the rotary tool 30 is moved along the boundary 3. At this time, a plastic flow is generated in the first metal member 10 along the boundary 3, and the boundary 3 between the first metal member 10 and the second metal member 20 is joined by friction stir welding.

[Pressing operation]
In addition to the above-mentioned basic steps, on the back side of the first metal member 10 and the second metal member 20, the metal flowing by the friction stir welding is pressed by the back side pressing tool 40, and the first metal member 10 and the metal member 10 are pressed. On the front side of the second metal member 20, the metal flowing by friction stir welding is pressed by the front side pressing tool 50. The back side pressing tool 40 and the front side pressing tool 50 will be described later.

[Material of metal parts]
It is preferable that the first metal member 10 into which the rotary tool 30 is inserted is a metal having a hardness lower than that of the second metal member 20. By doing so, since the rotary tool 30 is inserted only into the first metal member 10 having a small viscosity during plastic flow, adhesion of metal to the rotary tool 30 is suppressed. In addition, the energy required to generate the plastic flow is small.

It is preferable that the first metal member 10 into which the rotary tool 30 is inserted is a metal having a melting point lower than that of the second metal member 20. By doing so, it is possible to prevent the occurrence of joint defects and defects. If the melting point of the first metal member 10 into which the rotary tool 30 is inserted has a higher melting point, the second metal member 20 which is a mating material melts when the temperature of the first metal member 10 becomes high until it plastically flows. There is a risk of joining defects and defects. By making the first metal member 10 into which the rotary tool 30 is inserted a metal having a melting point lower than that of the second metal member 20, the above-mentioned inconvenience can be prevented.

For example, an aluminum-based material can be used as the first metal member 10, and a copper-based material can be used as the second metal member 20. Of course, the present invention is not intended to be limited to the above combinations.

[Rotating tool 30]
The rotary tool 30 has a substantially columnar shape, and is inserted into the first metal member 10 from the surface side thereof. The rotary tool 30 is set to a length such that the tip of the rotary tool 30 penetrates the thickness of the first metal member 10 and reaches the back surface side. When the rotary tool 30 is inserted into the first metal member 10 and moves, plastic flow is generated in the first metal member 10. In the vicinity of the boundary 3 between the first metal member 10 and the second metal member 20, a plastic flow is generated in the first metal member 10, and the first metal member 10 and the second metal member 20 are formed. Be joined.

A reverse screw portion can be formed on the outer circumference of the rotary tool 30. The rotary tool 30 is lowered along the axial direction while being rotated in the screwing direction of the right-hand screw, and is inserted toward the first metal member 10. At this time, by providing the reverse screw portion 33, a stirring action is generated when the rotary tool 30 is penetrated into the metal, and the plastic flow can be promoted.

When the rotary tool 30 is inserted into the first metal member 10 from the front side thereof, the outer peripheral edge of the rotating rotary tool 30 is substantially aligned with the boundary 3. The outer peripheral edge is a rotation locus of the tool formed on the outermost side when the rotary tool 30 to be penetrated into the first metal member 10 is rotated.

Here, to make the outer peripheral edge of the rotary tool 30 substantially coincide with the boundary 3, specifically, from the state where the outer peripheral edge of the rotary tool 30 is separated from the boundary 3 by about 0.1 mm, the outer peripheral edge of the rotary tool 30 is used. Is each state until it crosses the boundary 3 and enters the second metal member 20 side. Under these conditions, good bonding can be obtained.

With the rotary tool 30 inserted into the first metal member 10 from the front side thereof, the rotary tool 30 is moved along the boundary 3. The moving direction is along the boundary 3 and parallel to the upper surface where the first metal member 10 and the second metal member 20 are butted against each other and become flush with each other.

[Back side pressing tool 40]
FIG. 3 is a diagram illustrating the back side pressing tool 40. (A) is a plan view, (B) is a side view, (C) is a bottom view, (D) is a view from the moving direction, and (E) is a cross-sectional view seen from the side.

The back side pressing tool 40 is roughly block-shaped and is installed on a moving table (not shown).

The back side pressing tool 40 is present so as to face the back side of the first metal member 10 and the second metal member 20, and is moved along the boundary 3 in synchronization with the movement of the rotary tool 30. As a result, on the back side of the first metal member 10 and the second metal member 20, the metal flowing by the friction stir welding is pressed, and the surface after joining is flattened.

The back side pressing tool 40 is provided with an interference prevention space 41 for preventing interference with the tip of the rotary tool 30. In this example, the interference prevention space 41 is a recess formed on a surface facing the back side of the first metal member 10 and the second metal member 20.

By doing so, when the rotary tool 30 is inserted into the first metal member 10 from the front side and the tip reaches the back side, the tip of the rotary tool 30 and the back side pressing tool are used. Interference with 40 is prevented.

The back side pressing tool 40 is provided with a back side slope 42 in a region facing the back side of the first metal member 10 and the second metal member 20 and straddling the boundary 3. The back side slope 42 is provided so that the gap with the back side gradually becomes smaller toward the rear in the moving direction of the back side pressing tool 40. As a result, the back slope 42 gradually presses the metal that plastically flows when the back pressing tool 40 is moved in synchronization with the rotating tool 30.

The back side pressing tool 40 is provided with back side bank-shaped portions 43 on both sides of the boundary 3 facing the back side of the first metal member 10 and the second metal member 20. The back side bank-shaped portion 43 dams the metal flowing by the friction stir when the back side pressing tool 40 is moved in synchronization with the rotary tool 30.

The step between the back side bank-shaped portion 43 and the back side slope 42 is large in the front in the moving direction of the back side pressing tool 40, gradually decreases toward the rear, and finally becomes flush.

[Front side pressing tool 50]
FIG. 4 is a diagram illustrating the front side pressing tool 50. (A) is a plan view, (B) is a side view, (C) is a bottom view, (D) is a view from the moving direction, and (E) is a cross-sectional view seen from the side.

The front pressing tool 50 is roughly block-shaped and is installed on a moving table (not shown).

The front side pressing tool 50 is present so as to face the front side of the first metal member 10 and the second metal member 20, and is moved along the boundary 3 in synchronization with the movement of the rotary tool 30. As a result, on the front side of the first metal member 10 and the second metal member 20, the metal flowing by the friction stir welding is pressed, and the surface after joining is flattened.

The front side pressing tool 50 is provided with a penetrating portion 51 through which the rotary tool 30 is inserted. In this example, the penetration portion 51 is a through hole that opens to a surface facing the front side of the first metal member 10 and the second metal member 20.

By doing so, the metal that plastically flows around the rotary tool 30 can be effectively suppressed.

The front side pressing tool 50 is provided with a front side slope 52 in a region facing the front side of the first metal member 10 and the second metal member 20 and straddling the boundary 3. The front side slope 52 is provided so that the gap with the front side gradually becomes smaller toward the rear in the moving direction of the front side pressing tool 50. As a result, the front slope 52 gradually presses the metal that plastically flows when the front pressing tool 50 is moved in synchronization with the rotary tool 30.

The front side pressing tool 50 is provided with front side bank-shaped portions 53 on both sides of the boundary 3 facing the back side of the first metal member 10 and the second metal member 20. The front side bank-shaped portion 53 dams the metal flowing by the friction stir welding when the front side pressing tool 50 is moved in synchronization with the rotary tool 30.

The step between the front bank-shaped portion 53 and the front slope 52 is large in the front in the moving direction of the front pressing tool 50, gradually decreases toward the rear, and finally becomes flush.

[Implementation status]
FIG. 5 is a diagram illustrating a state in which the method for joining dissimilar metals according to the above embodiment is carried out.

The rotary tool 30 is rotated at, for example, about 1000 to 2000 rpm. The rotary tool 30 penetrates the thickness of the first metal member 10 and its tip is the interference prevention space 41.
It is inserted until it reaches. In this state, the rotary tool 30, the back side pressing member 40, and the front side pressing member 50 are moved along the boundary 3. The moving direction indicated by the arrow is parallel to the front side surface and the back side surface which are flush with each other by abutting the first metal member 10 and the second metal member 20. For example, if the thickness of the first metal member 10 and the second metal member 20 is 10 mm, the moving speed is about 150 to 250 mm per minute.

[Effect of Embodiment]
In the method of joining dissimilar metals according to the above embodiment, the first metal member 10 and the second metal member 20 are joined by friction stir welding. First, the first metal member 10 and the second metal member 20 of different types are arranged adjacent to each other so that there is substantially no gap. Next, the rotary tool 30 that rotates around the axis is attached to the first metal member 10 so that the outer peripheral edge of the rotary tool 30 substantially coincides with the boundary 3 between the first metal member 10 and the second metal member 20. On the other hand, insert from the front side. Next, by moving the rotary tool 30 along the boundary 3 in that state, the dissimilar metals are joined.
Further, in the present embodiment, there is a back side pressing tool 40 for holding the metal flowing by the friction stir welding so as to face the back side of the first metal member 10 and the second metal member 20. Then, the back side pressing tool 40 is moved along the boundary 3 in synchronization with the movement of the rotary tool 30.
By inserting the rotary tool 30 into the first metal member 10, plastic flow occurs only in the first metal member 10, and plastic flow hardly occurs in the second metal member 20. At this time, the back side pressing tool 40 facing the back side of the first metal member 10 and the second metal member 20 is moved along the boundary 3 in synchronization with the movement of the rotary tool 30. As a result, even if the metal is scattered due to the violent plastic flow, the metal flowing by the friction stir is pressed by the back side pressing tool 40, and as a result, the generation of voids can be significantly reduced. Therefore, it is possible to obtain an extremely good bonding state with few defects such as a mixture of two types of metals and voids. Therefore, non-destructive inspection by ultrasonic waves can be applied, and the reliability of the joint can be ensured.
Further, even if the rotary tool 30 is deeply inserted close to the back side of both metal members, the metal flowing by the friction stir is pressed by the back side pressing tool 40, so that the unbonded region, which has been a problem in the past, is hardly generated. Therefore, post-processing by cutting becomes unnecessary, and material loss is small.
Further, by inserting the rotary tool 30 only on the side of the first metal member 10, the vertical force applied to the rotary tool 30, which has been a conventional problem, can be greatly alleviated, and deterioration of the tool can be prevented. Further, since the rotary tool 30 can be inserted only into the metal having a low viscosity during plastic flow, the adhesion of the metal to the rotary tool 30 is suppressed. Therefore, it is possible to reduce the frequency of maintenance such as removing the metal adhering to the rotary tool 30 and replacing the rotary tool 30.
According to the method for joining dissimilar metals of the present embodiment, two metal members of different types can be satisfactorily joined by a friction stir welding method.

In the method of joining dissimilar metals of the present embodiment, the rotary tool 30 inserted from the front side into the first metal member 10 is inserted so that the tip thereof reaches the back side.
Since the back side pressing tool 40 presses the metal flowing by the tip of the rotary tool 30 that has reached the back side, the unjoined region, which has been a problem in the past, is hardly generated. Therefore, post-processing by cutting becomes unnecessary, and material loss is small.

In the method of joining dissimilar metals of the present embodiment, the back side pressing tool 40 is provided with an interference prevention space 41 for preventing interference with the tip of the rotary tool 30.
It is possible to prevent the tip of the rotary tool 30 reaching the back side from interfering with the back side pressing tool 40, and to prevent damage to the rotary tool 30 and the back side pressing tool 40.

In the method of joining dissimilar metals of the present embodiment, the back side pressing tool 40 presses the back side in a region facing the back side of the first metal member 10 and the second metal member 20 and straddling the boundary 3. A back slope 42 is provided so that the gap between the tool 40 and the back side gradually decreases toward the rear in the moving direction of the tool 40.
When the back side pressing tool 40 moves along the boundary 3 in synchronization with the movement of the rotary tool 30, the metal flowing by the tip of the rotary tool 30 that has reached the back side is moved by the back slope 42. , It is pushed back toward the back side of the first metal member 10 and the second metal member 20. Therefore, the scattering of metal is prevented and the generation of voids is greatly reduced. In addition, there is almost no unjoined region, which has been a problem in the past, post-processing by cutting is not required, and material loss is small.

In the method of joining dissimilar metals of the present embodiment, the back side pressing tool 40 flows on both sides of the boundary 3 facing the back side of the first metal member 10 and the second metal member 20 by friction stirring. A backside bank-shaped portion 43 is provided for damming the metal.
The backside bank-shaped portion 43 blocks the metal flowing by the tip of the rotary tool 30 that has reached the backside, thereby preventing the metal from scattering and significantly reducing the generation of voids.

In the method of joining dissimilar metals of the present embodiment, there is a front side pressing tool 50 for holding the metal flowing by the friction stir by facing the front side of the first metal member 10 and the second metal member 20. Let me. Then, the front side pressing tool 50 is moved along the boundary 3 in synchronization with the movement of the rotary tool 30.
Since the metal flowing by the friction stir is pressed by the front pressing tool 50, the generation of voids can be significantly reduced.

In the method of joining dissimilar metals of the present embodiment, the front pressing tool 50 is provided with a penetrating portion 51 through which the rotating tool 30 is inserted.
By pressing the flow of metal generated in the region around the rotary tool 30 with the front side pressing tool 50, the generation of voids can be significantly reduced.

In the method of joining dissimilar metals of the present embodiment, the front side pressing tool 50 presses the front side in a region facing the front side of the first metal member 10 and the second metal member 20 and straddling the boundary 3. A front side slope 53 is provided so that the gap between the tool 50 and the front side gradually decreases toward the rear in the moving direction of the tool 50.
When the front-side pressing tool 50 moves along the boundary 3 in synchronization with the movement of the rotary tool 30, the metal that flows due to the insertion of the rotary tool 30 is caused by the front-side slope 53 to be the first. It is pushed back toward the front side of the metal member 10 and the second metal member 20. Therefore, the scattering of metal is prevented and the generation of voids is greatly reduced.

In the method of joining dissimilar metals of the present embodiment, the front side pressing tool 50 flows on both sides of the boundary 3 facing the front side of the first metal member 10 and the second metal member 20 by friction stirring. A front side bank-shaped portion 53 is provided for damming the metal.
The front side bank-shaped portion 53 blocks the metal that flows when the rotary tool 30 is inserted, thereby preventing the metal from scattering and significantly reducing the generation of voids.

In the method of joining dissimilar metals of the present embodiment, the first metal member 10 into which the rotary tool 30 is inserted is made of a metal having a hardness lower than that of the second metal member 20.
Since the rotary tool 30 is inserted only into the first metal member 10 having a low viscosity during plastic flow, adhesion of metal to the rotary tool 30 can be suppressed, and the frequency of maintenance of the rotary tool 30 can be reduced. In addition, the energy required to generate the plastic flow is small, which is advantageous in saving power.

In the method of joining dissimilar metals of the present embodiment, the first metal member 10 into which the rotary tool 30 is inserted is made of a metal having a melting point lower than that of the second metal member 20.
If the melting point of the first metal member 10 into which the rotary tool 30 is inserted has a higher melting point, the second metal member 20 which is a mating material melts when the temperature of the first metal member 10 becomes high until it plastically flows. There is a risk of joining defects and defects. By making the first metal member 10 into which the rotary tool 30 is inserted a metal having a melting point lower than that of the second metal member 20, the above-mentioned inconvenience can be prevented.

[Modification example]
In the method of joining dissimilar metals of the above embodiment, the first metal member 10 is provided on at least one of the interference prevention space 41 of the back side pressing tool 40, the back side slope 42, or the front side slope 52 of the front side pressing tool 50. A metal member of the same kind of metal as the above can be arranged in advance.
By doing so, it is not necessary to fill the first metal member 10 as compared with the case where each of the above-mentioned points is a space, so that wall thinning can be avoided.

[Other variants]
Although the above has described a particularly preferable embodiment of the present invention, the present invention is not limited to the illustrated embodiment and can be modified into various embodiments, and the present invention includes various modified examples. The purpose is to do.

3: Boundary 10: First metal member 20: Second metal member 30: Rotating tool 40: Back side pressing tool 41: Interference prevention space 42: Back side slope 43: Back side bank-shaped part 50: Front side pressing tool 51: Penetration part 52: Front slope 53: Front bank

Claims (16)

The first metal member and the second metal member of different types are arranged adjacent to each other so that there is substantially no gap.
An axially rotating rotary tool is inserted into the first metal member from the front side so that the outer peripheral edge of the rotary tool substantially coincides with the boundary between the first metal member and the second metal member.
A method for joining dissimilar metals by frictionally stirring the first metal member and the second metal member by moving the rotary tool along the boundary in that state.
There is a back side pressing tool for holding the metal flowing by the friction stir welding so as to face the back side of the first metal member and the second metal member.
A method for joining dissimilar metals, which comprises moving the back pressing tool along the boundary in synchronization with the movement of the rotary tool. The method for joining dissimilar metals according to claim 1, wherein the rotary tool inserted from the front side into the first metal member is inserted so that the tip thereof reaches the back side. The method for joining dissimilar metals according to claim 2, wherein the back side pressing tool is provided with an interference prevention space for preventing interference with the tip of the rotary tool. The back side pressing tool is gradually placed in a region facing the back side of the first metal member and the second metal member and straddling the boundary with the back side toward the rear in the moving direction of the back side pressing tool. The method for joining dissimilar metals according to any one of claims 1 to 3, wherein a back slope having a small gap is provided. The back side pressing tool is provided with back side bank-like portions for blocking the metal flowing by friction stir welding on both sides of the boundary facing the back side of the first metal member and the second metal member. The method for joining dissimilar metals according to any one of claims 1 to 4. There is a front side pressing tool for holding the metal flowing by the friction stir welding so that the first metal member and the front side of the second metal member face each other.
The method for joining dissimilar metals according to any one of claims 1 to 5, wherein the front pressing tool is moved along the boundary in synchronization with the movement of the rotary tool. The method for joining dissimilar metals according to claim 6, wherein the front-side pressing tool is provided with a penetration portion through which the rotary tool is inserted. The front-side pressing tool is gradually placed in a region facing the front side of the first metal member and the second metal member and straddling the boundary with the front side toward the rear in the moving direction of the front-side pressing tool. The method for joining dissimilar metals according to claim 6 or 7, wherein a front slope having a small gap is provided. The front-side pressing tool is provided with front-side bank-shaped portions for blocking the metal flowing by friction stir welding on both sides of the boundary facing the front side of the first metal member and the second metal member. The method for joining dissimilar metals according to any one of claims 6 to 8. The first metal member and the second metal member of different types are arranged adjacent to each other so that there is substantially no gap.
An axially rotating rotary tool is inserted into the first metal member from the front side so that the outer peripheral edge of the rotary tool substantially coincides with the boundary between the first metal member and the second metal member.
A method for joining dissimilar metals by frictionally stirring the first metal member and the second metal member by moving the rotary tool along the boundary in that state.
There is a front side pressing tool for holding the metal flowing by the friction stir welding so that the first metal member and the front side of the second metal member face each other.
A method for joining dissimilar metals, which comprises moving the front pressing tool along the boundary in synchronization with the movement of the rotating tool. The method for joining dissimilar metals according to claim 10, wherein the front-side pressing tool is provided with a penetration portion through which the rotary tool is inserted. The front-side pressing tool is gradually placed in a region facing the front side of the first metal member and the second metal member and straddling the boundary with the front side toward the rear in the moving direction of the front-side pressing tool. The method for joining dissimilar metals according to claim 10 or 11, wherein a front slope having a small gap is provided. The front-side pressing tool is provided with front-side bank-shaped portions for blocking the metal flowing by friction stir welding on both sides of the boundary facing the front side of the first metal member and the second metal member. The method for joining dissimilar metals according to any one of claims 10 to 12. The method for joining dissimilar metals according to any one of claims 1 to 13, wherein the first metal member into which the rotary tool is inserted is a metal having a hardness lower than that of the second metal member. The method for joining dissimilar metals according to any one of claims 1 to 13, wherein the first metal member into which the rotary tool is inserted is a metal having a melting point lower than that of the second metal member. 2. The method for joining dissimilar metals according to any one of the above.

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