JP2001252774A - Method of friction stir joining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of friction stir joining by which the range of an appropriate joining condition is expanded, the setting of a joining condition is made easier, and the range of the joinable materials is expanded. SOLUTION: In the method of a friction stir joining where the joining is carried out by relatively moving a rotating joining tool 10 which is in contact with a part 1 to be joined and the vicinity of joining members A and B, and by stirring the contact part of the joining tool 10 while the tool is softened by the heat generated by friction, the joining tool 10 is composed of a shoulder 21 which retains the part 1 to be joined and the vicinity and a stirring pin 31 whose part 32 projected from the end face 23 of the shoulder 21 is inserted into the part 1 to be joined. The pin 31 of the joining tool 10 and the shoulder 21 are independently rotated, and the joining is performed by setting the ratio of the peripheral rotating speed of the pin 31 to that of the shoulder 21 between 1 to 0.3 and 1 to 5.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction stir welding method for joining metal materials by frictional heat generated by contact rotation of a welding tool.

[0002]

2. Description of the Related Art In a friction stir welding method, which is one of the solid-state welding of metal members, a welding tool rotating at a high speed is brought into contact with a portion to be welded and its vicinity, and the welding member is softened by generated frictional heat. This is a method of joining by stirring. Since this friction stir welding method can be joined at a lower temperature than fusion welding or brazing, it has the advantage that there is little joining failure due to thermal deformation during joining and oxidation of the joined part, and it is applied to joining of members in various industrial fields. ing.

As shown in FIG. 4, a welding tool (50) conventionally used in the friction stir welding method is provided with a rotating shaft (52) on the tip end surface (52) of a large-diameter shoulder (51). A small-diameter pin (53) having Q) protrudes. Then, while inserting the pin (53) into the portion to be joined, pressing the joint with the tip surface (52) of the shoulder (51), and moving the joining tool (50) while inserting and rotating it to perform joining. . FIG. 4 shows an example of the production of a butt joint of flat plate-like joining members (A) and (B), where (1) shows a butt portion to be joined,
(2) is a joint portion joined by the joining tool (50).

[0004]

However, since the conventional joining tool (50) has the shoulder (51) and the pin (53) having different diameters in an integrated structure, the peripheral speed ratio of these is different from that of the diameter. Fixed at a ratio. Therefore, if the rotation speed is set to a low value, the stirring force of the joint (53) by the pin (53) becomes small, which may cause internal defects. Conversely, if the rotation speed is set to a high value, the peripheral speed of the shoulder (51) increases. There is a problem that excessive heat input may cause surface defects, and the range of appropriate joining conditions may be narrowed to make it difficult to set conditions. In particular, there is even a problem that good joining cannot be performed because difficult joining members cannot be set to appropriate joining conditions.

In view of the above-mentioned technical background, an object of the present invention is to provide a welding friction stir welding method capable of expanding a range of appropriate welding conditions, facilitating setting of welding conditions, and expanding types of members that can be welded. .

[0006]

According to the friction stir welding method of the present invention, the joining member (A)
(B) the rotating welding tool (10) is relatively moved in contact with the portion to be welded (1) and its vicinity,
In the friction stir welding method in which the contact portion of the welding tool (10) is agitated while being softened by the generated frictional heat, the welding tool (10) includes a shoulder (21) that presses a portion to be welded (1) and its vicinity. ) And the projected portion (32) of the shoulder (21) from the distal end surface (23) are to be joined (1).
The pin (31) of the welding tool (10) and the shoulder (21) are independently driven to rotate, and the pin (31) and the shoulder (21) are independently driven. ) Is set in the range of 1: 0.3 to 5.0 to perform the joining.

It is preferable that the shoulder (21) and the pin (31) of the joining tool (10) are rotationally driven in directions opposite to each other.

Further, a pin (31) of the joining tool (10)
Is preferably inserted into a through hole (22) formed in the shoulder (21) so as to be able to advance and retreat.

The friction stir welding method of the present invention can be applied to any metal material that is softened by frictional heat generated by the contact rotation of a welding tool, regardless of its composition. It can also be applied to the joining of dissimilar metal materials.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the friction stir welding method according to the present invention will be described with reference to an example of manufacturing a butt joint of flat plate-like joining members (A) and (B) shown in FIGS. .

The joining tool (10) shown in these figures is inserted into a large-diameter cylindrical shoulder (21) and a through hole (22) formed at the center of the shoulder (21) so as to be able to advance and retreat. And a small diameter pin (31). Since the rotation direction and rotation speed of the shoulder (21) and the pin (31) are controlled independently of each other, the forward / reverse rotation speed ratio and the rotation speed ratio, in other words, the peripheral speed ratio, can be freely set. can do. The pin (31) is connected to the shoulder (2
The length of the protruding portion (32) from the distal end surface (23) of (1) can be freely adjusted, and the insertion depth into the to-be-joined portion (1), which is the to-be-joined portion, can be adjusted.

Then, the shoulder (21) and the pin (31) of the welding tool (10) are rotated by the drive device (not shown) in the set rotation direction and rotation speed, respectively, and the two welding members ( A) Insert the protruding portion (32) of the pin (31) into the butting portion (1) of (B), and press the vicinity of the butting portion (1) with the tip end surface (23) of the shoulder (21). The joining tool (10) is moved along the butting portion (1) in this state. The frictional heat generated by the rotation of the pin (31) or the frictional heat generated by the sliding of the tip surface (23) of the shoulder (21) and the upper surfaces of the two joining members (A) and (B) causes the pin (31) to move. ) In the vicinity of the contact portion, the joining members (A) and (B) are softened and agitated by the rotation of the pin (31). Then, with the movement of the welding tool (10), the softening and agitating portion wraps backward in the traveling direction of the welding tool (10) so as to fill the groove for passing the pin (31) by receiving the advance pressure of the pin (31). After the plastic flow, the frictional heat is quickly lost and the solidification is achieved by cooling. This phenomenon is sequentially repeated with the movement of the joining tool (10), and finally, both joining members (A)
(B) is joined and integrated at the butting portion (1). In the figure, (2) is a joint portion joined by the joining tool (10).

In the present invention, the peripheral speed ratio of the rotation of the pin (31) and the shoulder (21) of the welding tool (10) is 1:
The range is 0.3 to 5.0. The peripheral speed ratio is 1: 0.3
If the peripheral speed of the shoulder (21) is too low, the amount of heat input by the rotation of the shoulder (21) is insufficient, the material is not sufficiently softened, and the stirring efficiency by the rotation of the pin (31) deteriorates, and the joint (2) Internal defects are likely to occur. On the other hand, 1: 5.
If it exceeds 0, the amount of heat input due to the rotation of the shoulder (21) becomes excessive, so that a surface defect is likely to occur in the joint (2), or the range of heat influence is widened, and in any case, it becomes difficult to make a good joint. By setting the peripheral speed ratio within the above range, not only good joining is achieved, but also good joining can be performed even when the moving speed of the joining tool (10) is increased, so that the joining time is shortened. You. In addition, since the pins (31) and the shoulders (21) are driven independently, it is easy to set conditions for good joining. A preferred lower limit of the peripheral speed ratio is 1: 2.0, and a preferred upper limit is 1: 3.0.

Further, the pin (31) and the shoulder (21)
Are independently driven, it is possible to select these rotation directions in either the forward direction or the reverse direction. In the reverse rotation, the plastic flow of the softened portion is close to a turbulent flow, and the crystal structure is refined. As a result, the strength and elongation of the joint are improved, and a better joint is achieved.

Further, since the pin (31) can advance and retreat in the through hole (22) of the shoulder, the protruding portion (23) of the shoulder (21) from the distal end surface (23) according to the thickness of the portion to be joined. 32) The length can be adjusted appropriately. For example, FIG. 3 shows a member (C) in which the depth of the bonding interface changes in the bonding direction.
The example of manufacture of the lap joint by (D) is shown. In this case, if the length of the protruding portion (32) of the pin (31) is increased while the welding tool (10) is rotated and moved in the welding direction, welding can be performed in a series of operations.

[0016]

EXAMPLE Using a welding tool (10) shown in FIG. 1, butt joints were manufactured under different welding conditions shown in Table 1.

In each of the joining examples, the joining members (A) and (B) are made of 6N01-T5 and have a thickness of 4 mm and a width of 10 mm.
An aluminum alloy flat plate having a length of 0 mm and a length of 500 mm was subjected to a joining test at a joining distance of 500 mm.

The joining tool (10) is provided with a pin (3) having a diameter of 2 mm in a through hole (22) of a shoulder (21) having a diameter of 12 mm.
1) is inserted and the protrusion (32) of the pin (31) from the tip surface (23) of the shoulder (21) is adjusted to 3.8 mm, and only the rotation speed and the rotation direction are changed. . In Table 1, the rotation speed of the shoulder was set such that the peripheral speed ratio between the pin (31) and the shoulder (21) had the value shown in Table 1 based on the rotation speed of the pin. Conventional example 1
3) "Coaxial drive" is pin (31) and shoulder (21)
Are driven in the same direction at the same rotation speed. The welding speed is the moving speed of the welding tool (10).

For each joint joined under the conditions of Table 1,
Whether or not joining was possible was determined by observing the appearance, and the elongation and strength of the joint were measured by a conventional method with respect to the joint that was well joined in appearance. The elongation of the joining members (A) and (B) themselves is 12%, and the strength is 280 MPa. These evaluation results are also shown in Table 1.

[0020]

[Table 1]

From the results shown in Table 1, by setting the peripheral speed ratio between the pin (31) of the welding tool (10) and the shoulder (21) within a predetermined range, good friction stir welding can be performed and the welding speed can be improved. I confirmed that I can do it. In addition, it was confirmed that by rotating the pin (31) and the shoulder (21) in opposite directions, the elongation and strength of the joint can be improved and the properties of the base material can be approximated.

[0022]

As described above, according to the present invention, the rotating welding tool is relatively moved in contact with the portion to be joined of the joining member and the vicinity thereof, and the joining tool is brought into contact by the generated frictional heat. In the friction stir welding method in which a part is softened and agitated and joined, as the welding tool, a shoulder that presses a part to be welded and a vicinity thereof, and a stirrer in which a protruding part from a distal end surface of the shoulder is inserted into the part to be welded And a pin for driving the pin and the shoulder independently of each other, so that their rotational peripheral speed ratio is 1: 0.3 to 5.0 irrespective of the diameter of the pin and the shoulder. The friction stir welding can be performed satisfactorily by setting it freely within a preferable range of welding. Since the pin and the shoulder are driven independently, the setting range of the rotational peripheral speed ratio suitable for the joining member is expanded, the setting of the appropriate joining condition becomes easy, and the setting of the appropriate condition in the past was difficult. Good friction stir welding can also be performed on the joining members.

Further, by rotating the shoulder and the pin of the welding tool in directions opposite to each other, the plastic flow of the softened portion becomes close to a turbulent flow, and the crystal structure is refined. As a result, the strength and elongation of the joint are improved, and a better joint is achieved.

In the case where the pin of the welding tool is inserted into a through hole formed in the shoulder so as to be able to advance and retreat, the length of the projecting portion from the distal end surface of the shoulder may be adjusted according to the thickness of the portion to be welded. The size can be appropriately adjusted, and one joining tool can be applied to various joining members.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a friction stir welding method according to the present invention.

FIG. 2 is a longitudinal sectional view of a welding tool.

FIG. 3 is a longitudinal sectional view showing another embodiment of the friction stir welding method according to the present invention.

FIG. 4 is a perspective view showing a conventional friction stir welding method.

[Explanation of symbols]

 A, B, C, D ... joining member 1 ... butting part (planned joining part) 10 ... joining tool 21 ... shoulder 22 ... through hole 23 ... tip surface 31 ... pin 32 ... projecting part

Claims (3)

[Claims] 1. A rotating welding tool (10) is relatively moved in contact with a portion to be welded (1) of a welding member (A) (B) and the vicinity thereof, and welding is performed by frictional heat generated. In a friction stir welding method in which a contact portion of a tool (10) is stirred while being softened, the welding tool (10) comprises: a shoulder (21) for holding a portion to be welded (1) and its vicinity; Two
A protruding portion (32) of the tip surface (23) of (1) comprises a stirring pin (31) inserted into the portion to be welded (1), and a pin (31) of the welding tool (10) and a shoulder. (21) are independently driven to rotate, and bonding is performed by setting the rotational peripheral speed ratio between the pin (31) and the shoulder (21) in the range of 1: 0.3 to 5.0. Characteristic friction stir welding method. 2. A shoulder (21) of the joining tool (10).
The pin and the pin are rotationally driven in directions opposite to each other.
3. The friction stir welding method according to 1. 3. The friction stirrer according to claim 1, wherein the pin (31) of the welding tool (10) is inserted into a through hole (22) formed in the shoulder (21) so as to be able to advance and retreat. Joining method.