JP2003225777A - Friction stirring and joining tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a friction stirring and joining tool which has a prolonged service life and does not suffer any damage causing defective joining during the friction stirring and joining. <P>SOLUTION: A friction stirring and joining tool 10 comprises a columnar rotor 1 and a probe 2 which is concentrically protruded from the tip of the rotor 1. The probe 2 is a bar-shaped body which has a diameter smaller than that of the rotor 1 and is protruded from a bottom part 9 of the rotor 1 by a length equivalent to the thickness of a joining member. A thread 3 is formed on the outer circumferential surface of the probe 2. The thread 3 is not formed on a part of a root part 4, but a step is formed by differentiating the diameters of the root part 4 and the thread 3. The bottom part of the thread 3 is continuous to the root part 4. The connection part 5 of the rotor 1 to the probe 2 is radiused. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a friction stir welding tool, and more particularly to a friction stir welding tool used as a processing head when welding objects to be welded by the friction stir welding method.

[0002]

2. Description of the Related Art In recent years, a friction stir welding method has been used as a new welding means instead of welding or brazing of metal materials. This joining method is described in
As disclosed in Japanese Patent Publication, a probe made of a material harder than the objects to be joined is pressed between the objects to be joined while being rotated at high speed, and further inserted into the objects to be joined. And the pressure causes the materials to be joined to be plastically fluidized and agitated to join them.

FIG. 2 is a diagram showing an outline of the friction stirrer. The friction stir welding tool 20 includes a screw thread 3 at the tip of a cylindrical rotor 1 attached to a rotation drive unit (not shown).
The probe 2 having the above is concentrically projected. The probe 2 is installed above the abutting portion 7 of the joining members 6a and 6b, which are metal plates to be joined. A gap 7a is formed in the abutting portion 7 of the joining members 6a and 6b. The gap may be appropriately changed depending on the conditions such as the material of the joining member and the rotation speed of the probe, and may be closely attached.

FIG. 3 is a view showing a friction stir welding tool 20 as a processing head used in the conventional friction stir welding. The right half shows a sectional view and the left half shows a front view. The probe 2 is coaxially projected at the tip of the rotor 1 attached to the rotation drive unit (not shown).
A thread 3 is formed on the entire outer circumference of the probe 2. The thread 3 gradually becomes shallower toward the root 4 of the probe 2, and the thread 3 stops at the root 4 of the probe. Reference numeral 5 is a connecting portion between the rotor 1 and the probe 2 and has an acute angle. Reference numeral 9 indicates the bottom of the rotor 1.

Friction stir welding is performed as follows. The probe 2 is pressed against the abutting portion 7 of the end portions 6c of the joining members 6a and 6b while rotating in the direction of arrow R, and the probe 2
Is inserted until the bottom portion 9 of the rotor 1 contacts the upper surface of the abutting portion 7. A joining member 6a near a portion contacting the probe 2;
6b is plasticized by frictional heat. When the probe 2 is relatively moved in this state, the joining members 6a and 6b that have been plasticized on the front side of the probe 2 move to the rear side of the probe 2 while stirring and kneading, and the friction heat is lost on the rear side to rapidly. Cool to solidify. Therefore, the plasticized fluidized joining members 6a and 6b are agitated and kneaded to be joined in a completely integrated state. At this time, the bottom portion 9 of the rotor 1 presses the plasticized fluidized joining members 6a and 6b from above to flatten the surface of the joining portion 8. The arrow S indicates the moving direction of the probe.

In such friction stir welding, the temperature at which the joining member is plastically fluidized is considerably lower than the melting point of the joining member, and the heat input to the joining member during the joining process is
It has an advantage that it is less likely to be deformed or cracked due to thermal strain in the vicinity of the joint because it is much smaller than that in welding or brazing and no stress is generated due to solidification shrinkage.

[0007]

However, according to the probe used in the conventional friction stir welding, the thread formed on the probe is gradually shallowed toward the root, and the thread is stopped at the root of the probe. Therefore, at the point where the screw thread stops during friction stir welding, that is, the friction resistance with the member to be welded increases at the root of the probe, and the lifting of the member to be welded due to stirring causes the root of the probe to fatigue and a tool for friction stir welding. There is a problem of shortening the life as. Further, there is a problem that the member to be joined is likely to be adhered to the portion where the screw thread stops, the probe is damaged, and a joint failure due to the damage of the probe is likely to occur.

[0008] Therefore, an object of the present invention is to provide a tool for friction stir welding which can be expected to have a long service life and which is not damaged during friction stir welding.

[0009]

In order to achieve the above-mentioned object, the present invention provides the rotor according to the first aspect of the present invention, which is formed at the tip of the rotor and has a diameter smaller than that of the rotor. A friction stir welding tool consisting of a probe having a screw thread formed on the outer peripheral surface thereof, which is generated at a portion where the probe is inserted into a butt portion of a member to be joined while rotating and the probe is inserted. In a friction stir welding tool for plastically fluidizing and stirring a member by heat and pressure, the probe has a root portion formed to have a diameter smaller than the diameter of the screw thread. provide.

According to a second aspect of the present invention, there is provided a friction stir welding tool, wherein the thread has a valley portion which is continuous with a root portion.

According to a third aspect of the present invention, there is provided a friction stir welding tool, wherein the connecting portion between the rotor and the probe is formed in an arc shape.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a friction stir welding tool according to the present invention will be described.

FIG. 1 is a view showing a friction stir welding tool according to the present invention, in which the right half shows a sectional view and the left half shows a front view. The friction stir welding tool 10 is composed of a cylindrical rotor 1 and a probe 2 coaxially protruding from the tip of the rotor 1. The rotor 1 is connected to a drive unit of a rotary drive device (not shown).

The probe 2 is a rod-like member having a diameter smaller than that of the rotor 1 and protruding from the center of the bottom portion 9 of the rotor 1 to a length corresponding to the thickness of the joining member. 3 threads on the outer circumference of the probe
Are formed.

The thread 3 is not formed in the root portion 4. That is, the diameters of the root portion 4 and the screw thread 3 are different, and a step is provided. The root of the thread 3 is continuous with the root 4.

The connecting portion 5 between the rotor 1 and the probe 2 forms a radius (arc shape).

Joining of the joining members will be described with reference to FIG. The rotor 1 and the probe 2 projecting from the tip thereof are rotated in the direction of arrow R at high speed by a rotation drive unit (not shown), and the two joined members 6a, 6b are butted against each other.
The probe 2 is pressed against the abutting portion 7 of the end portion 6c, is inserted into the abutting portion 7, and the bottom portion 9 of the rotor 1 is brought into contact with the upper surfaces of the joining members 6a and 6b. In this state, the friction stir welding tool 20 is relatively moved along the abutting portion 7.

That is, the frictional heat generated by the rotation of the probe 2 and the bottom portion 9 of the rotating rotor 1 and the joining member 6
Friction heat generated by the contact with the upper surfaces of a and 6b causes the joining members 6a and 6b to plastically fluidize in the vicinity of the contact portion of the friction stir welding tool 20. Then, when the friction stir welding tool 20 is moved in the direction of the arrow S, the plasticized fluidized welding members 6a, 6b receive the advancing pressure of the probe 2 and are agitated and kneaded while being friction agitated welding tool 20.
After plastically flowing so as to wrap around in the direction of travel, the frictional heat is rapidly lost and the material solidifies by cooling. Therefore, the joining member 6
The a and 6b are agitated and kneaded to be joined in a completely integrated state. At this time, the joining members 6a and 6b that have been plastically fluidized by the bottom portion 9 of the rotor 1 are pressed from above and the surfaces of the joining portion 8 are leveled. Such a phenomenon is sequentially repeated with the movement of the friction stir welding tool, and finally the joining members 6a and 6b are joined and integrated at the abutting portion 7.

At this time, since the root portion 4 and the screw thread 3 are provided with a step with different diameters and the connecting portion 5 between the probe 2 and the rotor 1 forms a radius, At the time of friction stir welding, the welding members 6a and 6b are connected to the probe 2.
Of the joining members 6a, 6
b never rises. Therefore, it is possible to prevent stress from concentrating on the place where the screw thread 3 stops and the root portion 4 of the probe, so that the strength of the root portion 4 of the probe increases,
The tool life for friction stir welding is extended.

The present invention relates to a friction stir welding tool, particularly to a root portion of a probe, and the thread of the probe may be cylindrical or conical. Further, the height and pitch of the screw threads formed on the probe surface are not particularly limited. Further, the materials of the joining member and the friction stir welding tool are not limited.

When the joining members 6a and 6b are joined, the joining is started from the end portion 6c of the joining member as described above, but the joining can be similarly performed even if it is started from an arbitrary portion.

[0022]

EXAMPLE A friction stir welding test was conducted using the friction stir welding tool and the friction stirrer described above.

The joining member is a 6063 Al alloy, 2024
An Al alloy and copper (Cu) were used as joints of the same material, the plate thickness of each joint member was 4 mm, and the joint length of the joints was 400 mm.

Further, the friction stir welding tool is common to SKD61, which has high hot strength and good wear resistance. The diameter of the rotor was 25 mm, the length of the probe was 4 mm, the diameter of the thread of the probe was 6 mm, and the diameter of the root of the probe was changed as shown in Table 1. Insertion depth of probe is 4mm, rotation speed is 1300r
pm and the moving speed were 400 mm / min.

As a comparative example, the friction stir welding tool shown in the conventional example was used. That is, the outer circumference of the probe is
A thread is formed on the entire surface, and the thread gradually becomes shallower toward the root of the probe, and the thread stops at the root of the probe.

A plurality of joints were manufactured by the above method, and the total joint length until the joint failure occurred was measured to evaluate the life of the probe. The results are shown in Table 1. The presence / absence of bonding failure was evaluated by an internal quality inspection by an X-ray transmission test and a visual appearance quality inspection.

[0027]

[Table 1] If you compare the total length of joints until a joint failure occurs,
The friction stir welding tool according to the present invention has a
It is about twice as long, and it can be seen that the service life of the friction stir welding tool according to the present invention is remarkably extended.
That is, it is considered that the life of the friction stir welding tool is extended because stress is not concentrated on the probe, which is particularly susceptible to damage, of the probe, which is susceptible to damage.

[0028]

As described above, according to the friction stir welding tool of the present invention, since the root portion of the probe is formed to have a diameter smaller than the diameter of the screw thread, damage that causes welding failure during friction stir welding is achieved. Do not receive In addition, because the connecting portion between the rotor and the probe is formed in an arc shape, it does not suffer fatigue,
The tool life for friction stir welding can be expected to be extended.

[Brief description of drawings]

FIG. 1 is a diagram showing a friction stir welding tool according to the present invention.

FIG. 2 is a diagram showing an outline of a friction stir welding apparatus.

FIG. 3 is a view showing a conventional friction stir welding tool.

[Explanation of symbols]

1 rotor 2 probes 3 screw threads 4 root 5 connection 6a Joining member 6b Joining member 6c end 7 Butt 7a gap 8 joints 9 Rotor bottom 10 Friction stir welding tool 20 Friction stir welding tool

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Sumio Ono             3550 Kidayomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Shinshin             Within the corporation (72) Inventor Masaki Okano             3550 Kidayomachi, Tsuchiura City, Ibaraki Prefecture Hitachi Shinshin             Within the corporation F-term (reference) 4E067 AA05 AA07 BG00 CA01

Claims (3)

[Claims] 1. A friction stir welding tool comprising a rotor and a probe formed at the tip of the rotor, having a smaller diameter than the rotor, and having a thread formed on the outer peripheral surface thereof. In a friction stir welding tool that inserts the probe into a butt portion of a member to be joined while rotating, and plastically fluidizes and stirs the member by heat and pressure generated at the inserted portion, the probe has a root portion thereof. Is formed to have a diameter smaller than the diameter of the thread, the friction stir welding tool. 2. The tool for friction stir welding according to claim 1, wherein the thread has a root portion which is continuous with a root portion. 3. The rotor and the probe, wherein the connecting portion is formed in an arc shape.
The described friction stir welding tool.