JP4453682B2 - Joining method and joining tool - Google Patents

Description

  The present invention relates to a joining method for friction stir welding in a state where two metal members having different melting points are overlapped, and a joining tool used therefor. In the present specification, “aluminum” includes an aluminum alloy.

When a direct melting method such as TIG or MIG welding is used in joining two metal members having different melting points, for example, an aluminum member and a copper member, an intermetallic compound is likely to be generated at the joint. In order to avoid this, a method such as friction welding, explosion welding or brazing is used for the joining.
However, when friction welding is used for joining the aluminum member and the copper member, the cross-sectional shape of the member to be joined is limited to a bar or a pipe. In addition, when explosion welding is used, the cross-sectional shape of the member to be joined is limited and the cost is increased. Furthermore, when brazing is used, there is a problem in that the quality of the bonded portion is not stable and the bonded product obtained when heated to a high temperature is easily deformed.

It has been proposed to use friction stir welding in order to solve the above problems and join an aluminum member having a different melting point and another metal member. For example, when a high-speed rotating probe is brought into contact with a joining portion where an aluminum member and a dissimilar metal member are overlapped, and the friction stir welding is performed and the friction stir welding is performed, the probe from the higher strength member side of the two members is used. There has been proposed a bonding method in which the two are brought into contact with each other (for example, see Patent Document 1).
However, this joining method has a problem that it is difficult to insert the probe in the vicinity of the overlapping portion, and the life of the joining tool including the probe is shortened, so that the process management is complicated and expensive.

Japanese Patent Laid-Open No. 10-137952 (pages 1 to 5, FIGS. 1 and 2) Japanese Patent Laid-Open No. 10-328855 (pages 1 to 5, FIGS. 1 and 2)

Also, a probe that hangs down from the center of the bottom surface of the cylindrical rotor that rotates the welding tool is inserted near the overlapped part where the aluminum member and copper member are overlapped, and the two members are softened by frictional heat and stirred. When joining, a joining method in which the probe is inserted from the soft aluminum member side has also been proposed (see, for example, Patent Document 2).
According to this joining method, since plasticization of a soft aluminum member is easy, the probe can be easily inserted, and the metals of both members can be smoothly agitated. Has the advantage of improving.

However, depending on the selection of the joining tool including the probe and the joining conditions, a defect may occur in the joint. That is, the heat input to the two members is caused by friction between these members and the probe and the bottom surface (shoulder). For this reason, the amount of heat input in the vicinity of the overlap portion increases near the bottom surface and decreases on the tip side of the probe. Therefore, when the probe is inserted from the soft aluminum member side, the hard copper member located near the tip of the probe Less heat input. As a result, the copper material is insufficiently flowed in the copper member, so that there is a problem that an internal defect (cavity) is generated at a position near the tip of the probe in the joint W.
On the other hand, if the number of rotations of the probe and the rotor is increased to increase the amount of heat input at the position near the tip of the probe, the amount of heat input to the aluminum member side is further increased and the flow resistance of the aluminum member is significantly reduced. As a result, there is a problem that a surface defect is caused by a part of the aluminum member leaking out from the vicinity of the bottom surface.

  The present invention solves the problems in the background art described above, and when joining metal members having different melting points to each other by friction stir welding, a joining method that can reliably obtain a sound joint having no defects inside or near the surface It is another object of the present invention to provide a joining tool used therefor.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-described problems, the present invention has been conceived by increasing the amount of heat input in the vicinity of the probe tip in the joining tool.
That is, the joining method according to the present invention (Claim 1) includes a first portion including a cylindrical main body and a probe base end projecting from the bottom surface thereof, a probe tip, the main body of the first portion, and the probe base. And a second part including a rotating shaft penetrating the axis of the end , and a joining method using a joining tool comprising first and second parts that are coaxial with each other and individually rotate, and having a melting point A step of superimposing a pair of metal members different from each other, a step of arranging the joining tool in the vicinity of the surface of the metal member on the low melting point side of the pair of metal members, and a first part of the body side of the joining tool By entering the vicinity of the overlapping portion of the pair of metal members with the rotation of the second portion on the probe tip side larger than the rotation number of and moving along the longitudinal direction of the overlapping portion, The pair of metal members Comprising of a step of friction stir welding along the overlapped portion, and wherein the.

According to this, since the number of rotations of the second portion including the probe tip portion in the joining tool is large, insufficient flow in the metal member on the high melting point side in contact with the vicinity of the tip of the second portion is eliminated . For this reason, it can approach to the calorific value in the metal member of the low temperature side which a 1st part contacts, or can make it the same .

Slave it, can be reliably formed a sound joint without internal defects or surface defects across the overlapped portion of the two metal members.

Further, the welding tool used before Symbol joining method (claim 2), the body of the first portion and the probe tip and the first portion including the probe base end portion projecting from the body and its bottom surface of the cylindrical And a second part including a rotating shaft penetrating the shaft center of the probe base end part, and a bearing disposed between the first part and the second part.

According to which this, the second portion including a pulp lobe tip put the welding tool can be rotated at a high speed than the first part consisting of the body and probe base end portion. For this reason, the insufficient flow in the metal member on the high melting point side is easily eliminated by the second portion. Therefore, it is possible to reliably form a sound joint having no internal defects and no surface defects across the overlapping portions of the two metal members described above.

The friction stir welding is a method in which two metal members are softened and joined in a solid state, and an intermetallic compound is not formed in the joint, and a thermally affected part is also generated in the vicinity of the joint. Absent. Thus, as described above, the reason why the two metal members are set to the low melting point side and the high melting point side is that the softening point (softening temperature range) has a similar relationship according to the melting points. Therefore, the low melting point side and the high melting point side can also be expressed as a soft side and a hard side, a low strength side and a high strength side, or a high hardness side and a low hardness side at the same heating temperature.
In addition, a tool formed from a hard metal or alloy having a melting point higher than that of the two metal members is used as the joining tool.

In the following, the best mode for carrying out the present invention will be described.
1 to 4 relate to a joining method of the present invention and a joining tool 20 used therefor.
As shown in FIGS. 1 and 2 , the joining tool 20 (corresponding to claim 2 ) is made of, for example, high speed steel, and has a cylindrical base body 21 and a probe base end portion 22 protruding from the center of the bottom surface 21 a. A first portion 20 a including the probe base end portion 22, a probe tip portion 24 coaxial with the probe base end portion 22, and a rotary shaft 26 penetrating the shaft hole 23 of the main body 21 and the probe base end portion 22. 20b and a plurality of bearings 28 disposed between the first portion 20a and the second portion 20b. The first portion 20a and the second portion 20b are individually connected to a dedicated drive source such as a motor. A heat-resistant sealing material 29 is disposed near the outer end between the first and second portions 20a and 20b.

3, 4 relates to the bonding how using the bonding tool 20.
As shown in FIGS. 3 and 4, an aluminum alloy material (low melting point side metal member) 1 and oxygen-free copper (high melting point side metal member) 2 are overlapped and restrained to form a superposed portion 4. In addition, the joining tool 20 is disposed near the surface of the aluminum alloy material 1 so as to be inclined in the direction opposite to the moving direction. At this time, while the second portion 20b is rotated at a rotation speed larger than that of the first portion 20a, a pushing force of 1 to 30 kN is applied to the joining tool 20, and the second portion 20b is inserted toward the vicinity of the overlapping portion 4, and the joining is performed. The tool 20 is moved rightward in FIG. 4 at a moving speed of 50 mm to 2 meters / min.

  As described above, the aluminum alloy material 1 is brought into contact with the bottom surface 21a of the main body 21 and the probe base end portion 22 in the first portion 20a to generate friction and generate plasticity and fluidity. The two parts 20b come into contact with the probe tip 24 to generate friction and generate plasticity and fluidity. As a result, the aluminum alloy material 1 and the oxygen-free copper 2 are agitated with each other, and a joining portion W is formed in which both metals are solidified in a mixed state as the joining tool 20 is separated. On the other hand, the oxygen-free copper 2 is in frictional contact with the probe tip 24 of the second portion 20b, and the calorific value increases in accordance with the increase in the number of rotations, so that the lack of flow can be resolved. As a result, a sound joint W having no internal defects (cavities) can be formed along the overlapping portion 4.

Here, specific examples of the joining method will be described together with comparative examples.
Four sets of oxygen-free copper 2 having the same size as the aluminum alloy material 1 made of JIS: A6063 and having a length of 200 mm × width of 100 mm × thickness of 5 mm were prepared.
Further, a first portion 20a formed of a high-speed steel and having a main body 21 having a diameter of 20 mm, a probe base end portion 22 having a diameter of 9 mm and a length of 3 mm, a probe tip portion 24 having the same diameter and length, and a rotating shaft 26 is used. The joining tool 20 including the second portion 20b was prepared. Further, a joining tool having a general form in which the tool body and the probe are integrated is prepared separately.
As shown in FIGS. 3 and 4, each set of aluminum alloy material 1 and oxygen-free copper 2 are overlapped and restrained to form a superposed portion 4, and near the surface of the aluminum alloy material 1. The joining tool 20 and the joining tool having a general form are arranged individually and inclined in the same manner as described above.

The first and second portions 20a and 20b of the welding tool 20 inclined by 5 ° from the surface side of the three sets of aluminum alloy materials 1 to the opposite side to the moving direction are individually rotated at the number of revolutions shown in Table 4, and the indentation pressure is 12 It was inserted under the same conditions of 0.5 kN and a moving speed of 200 mm / min, and moved along the overlapping portion 4 as shown in FIGS. The joint part W obtained by these was made into Examples 1-3.
On the other hand, it was inserted from the surface side of the remaining set of aluminum alloy material 1 under the same conditions as described above except that the joining tool of the general form was used and the rotational speed was the same as that of the first portion 20a. And it was made to move along the superposition | polymerization part 4, and the obtained junction W was made into the comparative example.
Each joint part W of Examples 1-3 and the comparative example was cut | disconnected, the exposed cross section was observed visually, and the presence or absence of the defect was investigated. The results are shown in Table 1.

  According to the results of Table 1, no internal defects occurred in the joints W of Examples 1 to 3, whereas the joint W of the comparative example had a coarse internal defect (cavity of about 0.2 mm). ) Was discovered. In other words, in Examples 1 to 3, the second portion 20b having a large rotational speed in the welding tool 20 sufficiently performed plastic flow even in the oxygen-free copper 2 and did not cause insufficient flow. On the other hand, in the comparative example, the single probe rotates in the aluminum material 1 and the oxygen-free copper 2 at the same rotation speed (700 rpm) and stirs them. Presumed to have occurred. From the above Examples 1 to 3, the superiority of the bonding method of the present invention will be easily understood.

5 and 6 show a joining tool 20 'of a reference form (corresponding to claim 3).
As shown in FIGS. 5 and 6, the joining tool 20 ′ includes a first portion 20 a including a cylindrical main body 21, a rotating shaft 26 that penetrates the axial hole 23 of the main body 21, and a probe positioned at the tip thereof. 25, and a plurality of bearings 28 disposed between the first portion 20a and the second portion 20b.
The first and second portions 20a and 20b are individually connected to a dedicated drive source such as a motor, and a heat-resistant sealing material is provided near the outer end between the first and second portions 20a and 20b. 29 is arranged.

  Even when the above-described joining tool 20 'is used, the rotational speed of the second portion 20b including the probe 25 is made larger than that of the first portion 20a of the main body 21, so as shown in FIGS. The amount of heat input due to friction increases, and plasticity and fluidization are reliably performed in the copper member 2 on the high melting point side. On the other hand, since the rotation speed of the first portion 20a is reduced, the low melting point side aluminum alloy material 1 in contact with the bottom surface 21a of the main body 21 can be prevented from melting due to excessive frictional heat generation. Therefore, the joining method (Claim 1) for forming a sound joined portion W is also possible with the joining tool 20 '.

FIG. 7 shows a cross section of a welding tool 20 ″ of a different reference form.
As shown in FIG. 7, the joining tool 20 ″ includes a first portion 20 a including an outer peripheral portion of a columnar main body 21, a large-diameter rotating shaft 26 that penetrates an axial center hole 23 of the main body 21, and a bottom surface 27 thereof. A second portion 20b including a probe 25 projecting coaxially from the central portion, and a plurality of bearings 28 disposed between the first portion 20a and the second portion 20b are included.The first and second portions. 20a and 20b are also individually connected to a dedicated drive source such as a motor, and a heat-resistant seal material 29 is disposed near the outer end between the first and second portions 20a and 20b.
Even when the welding tool 20 ″ as described above is used, it is possible to obtain the same operation and effect in the welding tool 20 as in the welding tool 20 ′.

The present invention is not limited to the embodiments and examples described above.
For example, the metal member on the low melting point side and the high melting point side in the present invention has a difference in melting point or softening point between them of 100 ° C. or higher, or a difference in strength such as tensile strength at the same heating temperature. If it is 100 N or more, or if the difference in hardness is 30 Hv or more, the combination of different metals and their alloys can be applied to the same type of metal alloys as well as the base.
In addition, the overlapping portion of the pair of metal members on the low melting point side and the high melting point side includes the stepped portions of both members or a male / female fitting portion, and is not limited to a straight shape in a plan view. A polymer part that is bent in the middle and a polymer part that curves are also included.

The side view which shows the joining tool of this invention. Sectional drawing of the said joining tool. Schematic which shows the joining method of this invention using the said joining tool. Schematic which shows the said joining method at a different angle. The side view which shows the joining tool of a reference form. Sectional drawing of the said joining tool. Sectional drawing similar to the above which shows the joining tool of a different reference form.

Explanation of symbols

1. Aluminum alloy material (low melting point metal member)
2 ………………………… Oxygen-free copper (metal member on the high melting point side)
4 ………………………… Overlapping part 2 0 …………………………… Joint tool 20a …………………… First part 20b …………………… Second Part 21 ………………………… Body 22 ………………………… Probe proximal end 24 ……………………… Probe distal end 26 ……………………… Rotation Shaft 28 ………………………… Bearing

Claims (2)

A first portion including a cylindrical main body and a probe base end projecting from the bottom surface thereof; a probe front end; and a rotation shaft penetrating the axis of the first portion main body and the probe base end. A joining method using a joining tool comprising first and second parts that are coaxial with each other and individually rotate.
Superimposing a pair of metal members having different melting points;
Placing the joining tool near the surface of the low melting point metal member of the pair of metal members;
The joining tool is allowed to enter the vicinity of the overlapping portion of the pair of metal members with rotation in which the rotation speed of the second portion on the probe tip side is larger than the rotation speed of the first portion on the main body side. A step of friction stir welding the pair of metal members along the overlapping portion by moving along the longitudinal direction of
The joining method characterized by the above-mentioned. A joining tool used in the joining method according to claim 1 ,
A first portion including a cylindrical main body and a probe base end projecting from the bottom surface thereof;
A second portion including a probe tip and a rotation shaft penetrating the main body of the first portion and the axis of the probe base end;
A bearing disposed between the first part and the second part,
A joining tool characterized by that.

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