JP2020138203A - Manufacturing method of dissimilar metal bonded body - Google Patents

Abstract

To provide a manufacturing method of a dissimilar metal bonded body which makes it possible to perform good joining that can firmly join up to the bottom of a member even when joining dissimilar metal members.SOLUTION: A manufacturing method of a dissimilar metal bonded body according to the present invention is for butt-joining two members made of different metals together so as to be joined by friction stir welding, in which a recess is provided on a ground plane on which the two members of different metals are installed, the two members are installed so that the butt surface of the two members is arranged along the recess, and then a rotary tool is inserted so that an end of the rotary tool substantially matches the butt boundary.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a bonded body in which two different metals are bonded by friction stir welding.

Friction stir welding means that a cylindrical tool is rotated and pressed against a joint, so that the rotary tool penetrates into the joint of the members to be joined. Then, it is a joining method in which the members are softened by the generation of frictional heat and the plastic flow around the joint is promoted by the rotational force of the rotary tool to integrate the plurality of members.

For example, as compared with arc welding, the heat effect of the joint can be mitigated without melting the members. The generation of noise and dust can also be suppressed. Further, unlike electron beam welding, a vacuum is not required, so that the device can be miniaturized.

For example, when two plates made of aluminum or the like are joined by abutting their side surfaces, a rotary tool is inserted from directly above the joint line and the rotary tool is moved along the joint line to form the two plates. Plate materials can be joined (for example, Patent Document 1 and Patent Document 2).

Japanese Unexamined Patent Publication No. 9-35918 JP-A-2007-136544

When joining two metal plates, the plates are installed on the member installation tool and fixed with a fixing jig, etc. to join, but if the rotary tool is inserted to the bottom of the plate, the tip of the rotary tool Has reached the vicinity of the surface of the member fixture, and there is a problem that the plate material and the member fixture are joined. Therefore, the rotary tool can be inserted only slightly away from the surface of the member installer. Then, the plastic flow becomes insufficient near the bottom surface of the abutting portion of the two plate materials (that is, near the tip of the rotary tool), so that an unbonded region called a kissing bond as shown in FIG. 9 is generated. Finally, by removing only the thickness of this unbonded region by cutting or the like, two plates that are firmly joined as a whole can be obtained, but an unnecessary process such as cutting is required and Material loss also occurs.

In order to reduce the occurrence of this unjoined region as much as possible, as disclosed in Patent Document 1 or 2 described above, the rotating shaft of the rotary tool and the point where the two metal plates are joined are matched. It is processed in a state. However, when the two metals are dissimilar metals, the two metals flow to each other on the opposite side, resulting in a region in which the two metals are unevenly mixed. In such a region, defects such as voids often occur, and since different metals are mixed, non-destructive void inspection using ultrasonic waves or the like cannot be performed.
Furthermore, the two metals differ in hardness and viscosity during plastic flow. If a rotating tool is inserted into a boundary having different hardness and viscosity and moved along the boundary line, a large load is applied to the rotating tool, such as a force being applied in a direction orthogonal to the moving direction. In addition, there is a problem that a metal having a high viscosity during plastic flow adheres to the rotary tool.

The problems to be solved by the present invention are summarized below.
Friction stir welding is in the process of technological innovation, and there are issues that have not yet been solved or even fully recognized. The above-mentioned problem is one of such problems.
In particular, this problem becomes remarkable in joining dissimilar metals. That is, it is a critical issue that a kissing bond, which is a large unbonded portion, is generated near the bottom surface, but in addition, there is a possibility that the joint strength is lowered not only near the bottom surface but also over the entire joint portion. The cause is that there is a region where dissimilar metals are mixed over the entire joint. When dissimilar metals having different properties are mixed, defects such as voids that weaken the metal joint are likely to occur, so that the joint strength is lowered. Not only that, the presence of this defect may promote the deterioration of the joint over time, which is a fatal problem in the joint technology that requires long-term stability. The difficulty of performing non-destructive inspections also exacerbates the problem.
Despite the existence of such serious issues, no sufficiently effective countermeasures have been proposed at this time.

The present invention has been made to solve the above-mentioned problems, and provides a method for producing a dissimilar metal bonded body that can obtain good bonding even when dissimilar metals are bonded.

The method for producing a dissimilar metal joint according to the present invention is to butt two members made of different metals and join them by friction stir welding.
A recess is provided in the ground plane on which the two members of different metals are installed, and the two members are installed so that the abutting surface of the two members is along the recess.
It is characterized in that the rotary tool is inserted so that the end portions of the rotary tool substantially coincide with the abutted boundary.

Further, the method for manufacturing a dissimilar metal joint according to the present invention is characterized in that the rotation center of the rotary tool is inserted into the member side made of the metal having the smaller hardness among the different metals. ..

Further, the method for manufacturing a dissimilar metal joint according to the present invention is characterized in that a metal member is installed in a recess provided on the ground plane.

The metal member installed in the recess provided on the ground plane is characterized in that it is a member having a lower melting point than either a metal having a lower hardness or a metal constituting the above two members.

In order to solve the above-mentioned serious problem, first, it was considered to suppress the occurrence of a region where dissimilar metals are mixed. That is, the joining was performed by shifting the ends of the rotary tools to the vicinity of the boundary between the two members butted against each other. As a result, it became possible to suppress the mixed region until it became sufficiently small, and a good bond with few defects such as voids was obtained above the two members. However, another unexpected problem arose. It is a new problem that the kissing bond, which is an unbonded portion, expands on the bottom surface portion. This is because the position of the rotary tool was shifted, so that the flow between the two members was restricted near the bottom surface where the rotary tool could not be inserted, and the unjoined or insufficiently joined area expanded to a position considerably higher than the bottom surface. Conceivable.
Therefore, the rotary tool can be inserted deeper by providing a recess on the ground plane. As a result, it was found that good bonding can be performed from the top surface to the bottom surface.

Not only good bonding was obtained, but also a secondary effect was obtained.
First, the rotating tool is inserted at a slight inclination for the purpose of reducing the resistance when moving the rotating tool along the abutting surface. As a result, deterioration of the rotary tool can be suppressed. However, if the rotary tool is tilted and inserted, the kissing bond will expand near the bottom surface. This is especially noticeable when joining dissimilar metals. Therefore, this problem was solved by allowing the rotary tool to be inserted deeper.
Further, in the joining of dissimilar metals, since the viscosity of each metal at the time of flow is different, a force is generated in the rotary tool in a direction orthogonal to the moving direction, and the deterioration of the rotary tool is likely to be accelerated. However, by shifting the position of the rotary tool and inserting it into only one metal, the vertical force applied to the rotary tool can be greatly alleviated and deterioration can be suppressed.
Since the rotary tool can be inserted only into the metal having a low viscosity during flow, the adhesion of the metal to the rotary tool can be suppressed. That is, the frequency of maintenance such as removing the attached metal can be reduced.

As described above, by "providing a recess on the ground contact surface" and "making the end of the rotating tool almost coincide with the abutted boundary", good bonding to the bottom surface was obtained even for dissimilar metals. Instead, the effect of reducing the burden on the rotary tool and improving maintainability was also obtained.

It is a schematic perspective view which shows the state before inserting the rotary tool at the time of joining two members in the manufacturing method of the dissimilar metal joint body which concerns on Embodiment 1 of this invention. FIG. 5 is a schematic perspective view showing a state in which a rotary tool is inserted when joining two members in the method for manufacturing a dissimilar metal joint according to the first embodiment of the present invention. FIG. 5 is a schematic perspective view showing a state in which a rotary tool is inserted and swept when joining two members in the method for manufacturing a dissimilar metal joint according to the first embodiment of the present invention. FIG. 5 is a schematic side view showing a state in which a rotary tool is inserted and swept when joining two members in the method for manufacturing a dissimilar metal joint according to the first embodiment of the present invention. It is a top view which shows the joint part in the manufacturing method of the dissimilar metal joint body which concerns on Embodiment 1 of this invention. FIG. 5 is a schematic perspective view showing a state in which a rotary tool is inserted and swept when joining two members in the method for manufacturing a dissimilar metal joint according to the second embodiment of the present invention. FIG. 5 is a schematic side view showing a state in which a rotary tool is inserted and swept when joining two members in the method for manufacturing a dissimilar metal joint according to the second embodiment of the present invention. It is a perspective view of the joined member after the joining is completed in the manufacturing method of the dissimilar metal joint body which concerns on Embodiment 1 of this invention. It is a reference figure, and is the side photograph which observed the kissing bond generated on the bottom surface side in the conventional manufacturing method of a dissimilar metal joint.

Regarding the method for producing a dissimilar metal joint of the present invention, two good embodiments are disclosed below. These embodiments disclose examples of good manufacturing methods for satisfactorily carrying out the present invention, and the present invention is not specifically limited to the manufacturing methods shown in these embodiments.

Embodiment 1.
First, the joining operation when joining dissimilar metals will be described with reference to the drawings. FIG. 1 is a schematic perspective view showing a state before inserting the rotary tool 1b when joining two members. FIG. 2 is a schematic perspective view showing a state in which the rotary tool is inserted. FIG. 3 is a schematic perspective view showing a state in which the rotary tool is inserted and swept.

The method for producing a dissimilar metal joint according to the present embodiment is to butt two members 2 and 3 which are different metals and join them by friction stir welding, and the two members 2 and 3 which are different metals are joined. A recess 4a is provided on the ground contact surface of the member installation portion 4, and two members 2 and 3 are installed so that the butt surfaces of the two members 2 and 3 are along the recess 4a, and a rotary tool is provided at the butt boundary. The rotary tool 1b is inserted so that the ends of 1b are substantially aligned with each other.

The friction stir welding device insertion portion 1 for performing friction stir welding includes a shoulder portion 1a having a large rotational moment to generate a stable large torque and a rotary tool 1b. The rotary tool 1b is provided below the shoulder portion 1a with the central axis aligned with the shoulder portion 1a, and is a thin portion having a diameter of about several mm to 10 mm. The friction stir welding device insertion unit 1 rotates at, for example, about 1000 to 2000 rpm. Then, it descends in the direction of the white arrow in FIG. 1, that is, toward the lower members 2 and 3.

Then, as shown in FIG. 2, the rotary tool 1b is inserted into the members 2 and 3. At the time of insertion, the rotary tool 1b receives rotational resistance, but since the shoulder portion 1a has a large rotational moment, the rotary tool 1b is inserted into the members 2 and 3 with almost no reduction in the rotational speed.

After insertion, the friction stir welding device insertion portion 1 moves in the direction of the white arrow in FIG. That is, it moves along the abutting surface of the members 2 and 3. The state at the time of movement is shown in FIG. Joining 6 is performed at the portion where the rotary tool 1b has passed. When the rotary tool 1b moves to the end, the joining is completed. The moving speed varies depending on the thickness of the member, but when the thickness is 10 mm, the moving speed is about 150 mm to 250 mm per minute.

FIG. 4 is a schematic side view showing a state in which a rotary tool is inserted and swept when joining two members. It is a transmission view seen from the side surface direction on the right side of FIGS. 1 to 3. As can be seen from this figure, the friction stir welding device insertion portion 1 is tilted by about 3 ° with respect to the vertical direction (direction perpendicular to the member surface) shown by the dotted line. The lower part of the rotary tool 1b is tilted so as to protrude in the moving direction. As described above, there are two reasons why the friction stir welding device insertion portion 1 is slightly tilted.

The first reason is that the resistance during movement is reduced, and damage or deterioration of the rotary tool 1b can be suppressed.
The second reason is to prevent a part of the plastically fluidized member due to the rotation of the rotary tool 1b from popping out. In FIG. 4, a part of the plastically fluidized member pops out on the left side of the rotary tool 1b due to the tilting of the friction stir welding device insertion portion 1. This protrusion can be suppressed to some extent by the shoulder portion 1a.
However, if the friction stir welding device insertion portion 1 is tilted in this way, a slight dent may occur on the upper surface of the joint body, and depending on the purpose of use of the joint body, the friction stir welding device insertion portion 1 may be joined without being tilted. You may.

Since the lower end of the rotary tool 1b is provided with the recess 4a, the members 2 and 3 can be inserted through the members 2 and 3 in the thickness direction. Even if the members 2 and 3 are penetrated in the thickness direction, the surfaces of the members 2 and 3 and the member installation portion 4 are not joined due to the effect of the recess 4a.

It is not necessary for the rotary tool 1b to completely penetrate the members 2 and 3 in the thickness direction, and good joining can be achieved by inserting the rotary tool 1b so that the lower end of the rotary tool 1b comes into contact with the bottoms of the members 2 and 3.

FIG. 5 is a top view showing the joint portion 6. The dotted line represents the joint surface between the member 2 and the member 3, that is, the abutted boundary. The rotary tool is inserted so that the ends of the rotary tool 1b substantially coincide with this boundary. FIG. 5A shows a state in which the end portion of the rotary tool 1b is inserted into the member 2 by about 0.1 mm, and FIG. 5B shows a state in which the end portion of the rotary tool 1b does not enter the member 2 and is substantially a boundary. It is on the right side by about 0.1 mm from the position. Good joining is possible in both FIGS. 5A and 5B, and it is sufficient that the ends of the rotary tool 1b substantially coincide with the boundary in this way.

In both FIGS. 5A and 5B, the center of rotation of the rotary tool 1b is located in the member 3. The member in which the center of rotation of the rotary tool 1b is located is preferably a member having a low hardness. For example, when the member 2 is Cu and the member 3 is Al, the hardness of Al is smaller, and in that case, the rotation center of the rotary tool 1b is located in the member 3.

As described above, by locating most of the rotary tool 1b on the member side having a low hardness, the rotary tool 1b can be easily inserted and moved along the boundary, and deterioration of the rotary tool 1b can be suppressed.
Further, since most of the rotary tool 1b is located on the side of one member, it is possible to prevent the two members from flowing and expanding the mixed region. Further, a member having a high viscosity such as Cu adheres to the rotary tool 1b, which can be minimized. When a large amount of Cu adheres to the rotary tool 1b, it is necessary to cut and remove the Cu before the next joining, but there is an advantage that the work does not have to be performed. Since these effects become more remarkable when all of the rotary tools 1b are located on one member side, FIG. 5B is more desirable.
The recess 4a provided on the ground plane may have a width capable of covering the width direction of the joint portion 6. Then, when installing the two members 2 and 3, the joint portion 6 is taken into consideration in advance, and the planned center position of the joint portion 6 in the width direction and the center position of the recess 4a in the width direction substantially coincide with each other. It is preferable to install the two members 2 and 3 so that the abutting surfaces of the two members 2 and 3 are along the recess 4a.

On the other hand, the concern that most of the rotary tool 1b is located on one member side is that it becomes difficult to join the bottom side of the member. However, by providing the recess 4a, as shown in FIG. 4, the rotary tool 1b can be inserted deeply, good bonding to the bottom is possible, and the kissing bond observed in FIG. 9 does not occur. Can be joined.

Embodiment 2.
In the first embodiment, it is shown that good bonding is possible even with dissimilar metals by providing the recess 4a in the member installation portion 4.
In the present embodiment, it is shown below that good bonding can be obtained by providing a sacrificial material in the recess 4a.

The only difference from the first embodiment is that, as shown in FIG. 6, a sacrificial material is provided in the recess 4a. Further, the joining procedure and the like are the same as the procedure and the like shown in the first embodiment, and the description thereof will be omitted.

FIG. 7 is a view corresponding to FIG. 4 in the first embodiment, and is a schematic side view showing a state in which the rotary tool 1b is inserted and swept. A sacrificial material 5 is installed in the recess 4a.
At the time of joining, it is desirable that the tip of the rotary tool 1b touches or does not hit the surface of the sacrificial material 5, or is slightly inserted. In either case, as in the first embodiment, good joining can be performed up to the bottom of the members 2 and 3.

When the joining is completed, as shown in FIG. 8, the sacrificial material 5 may be joined to the bottom surfaces of the members 2 and 3. In this case, all the sacrificial material 5 may be cut by cutting. Since the sacrificial material 5 has a smaller area than the members 2 and 3, it can be easily scraped off.

The sacrificial material may be a metal of the same type as any of the member 2 and the member 3. Alternatively, a material having a melting point lower than that of either the member 2 or the member 3 may be used.
For example, when the member 2 is Cu (melting point 1085 ° C.) and the member 3 is Al (melting point 660 ° C.), for example, brass may be used as the sacrificial material 5. In particular, when the ratio of Zn was increased to bring the melting point to about 700 ° C. to 800 ° C., the members 2 and 3 were not joined, and the processing of cutting and removing the sacrificial material was unnecessary. In this way, if a sacrificial material made of a material having a melting point lower than that of any one of the members 2 and 3 is used, the two types of joining members can be firmly joined to the bottom, while these members and the sacrificial material are joined. In many cases, it is possible to realize a favorable situation of not doing so.

Although the reason for this is not clear, the low melting point material tends to flow due to the rotation of the rotary tool 1b and easily escapes to the periphery. For this reason, even if they are joined, the connection will have many defects, and as a result, it is highly possible that they will not be joined.

<Summary of the present invention>
As described above, in the two embodiments, a method for manufacturing a dissimilar metal joint body capable of performing good bonding that can be firmly bonded to the bottom of the member even when dissimilar metal members are bonded has been described in detail.

The features of the method for producing a dissimilar metal joint according to the present invention are listed below.
First, even when joining different types of metal members, they can be firmly joined up to the bottom of the members. That is, good bonding without so-called kissing bonds is possible from the top to the bottom.

Second, each of the two metal members stirs with each other, and no region of heterogeneity is created. Therefore, defects such as voids are unlikely to occur in the vicinity of the joint, and the presence or absence of voids can be easily inspected by a non-destructive test using ultrasonic waves or the like.

Thirdly, the load applied to the rotary tool is small, and deterioration of the tool can be suppressed. In addition, adhesion of highly viscous metal to rotary tools can be suppressed.

1 Friction stir device insertion part 1a Shoulder part 1b Rotating tool (probe part)
2 Member A
3 Member B
4 Member installation part 4a Recess 5 Sacrificial material 6 Joined part

The first method for producing a dissimilar metal joint according to the present invention is to butt two members made of different metals and join them by friction stir welding.
A recess is provided in the ground plane on which the two members of different metals are installed, and the two members are installed so that the abutting surface of the two members is along the recess.
It is characterized in that the rotary tool is inserted so that the end portions of the rotary tool substantially coincide with the abutted boundary.
The second method for producing a dissimilar metal joint according to the present invention is a method for producing a dissimilar metal joint in which two members made of different metals are butted against each other and joined by friction stir welding.
On the ground plane on which the two members of different metals are installed, the metal member is installed along the abutting surface of the two members.
It is characterized in that the rotary tool is inserted so that the ends of the rotary tool are substantially aligned on the abutted boundary surface.

Claims (4)

A method for manufacturing a dissimilar metal joint in which two members made of different metals are butted against each other and joined by friction stir welding.
A recess is provided in the ground plane on which the two members of different metals are installed, and the two members are installed so that the abutting surface of the two members is along the recess.
A method for manufacturing a dissimilar metal joint, which comprises inserting a rotary tool so that the ends of the rotary tool are substantially aligned on the abutted interface. The method for manufacturing a dissimilar metal joint according to claim 1, wherein the rotation center of the rotary tool is inserted into the member side made of the metal having the smaller hardness among the different metals. The method for manufacturing a dissimilar metal joint according to claim 1 or 2, wherein a metal member is installed in a recess provided on the ground plane. 3. The metal member installed in the recess provided on the ground contact surface is a member having a lower melting point than either a metal having a lower hardness or a metal constituting the two members. The method for producing a dissimilar metal joint according to.