JP2003112272A - Friction stir welding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a friction stir welding method in which hollow cylindrical members are welded with each other without impairing any roundness of the hollow cylindrical members in their circumferential welding. SOLUTION: In welding the two hollow cylindrical members 3 and 4, a first probe 12 of a first rotary tool 1 and second probe 22 of a second rotary tool 2 are used, the pressing position of the first probe to a circumferential surface of the member and the pressing position of the second probe to a circumferential surface of the member are set to be in a plane orthogonal to the axes of the hollow cylinders at an angle of about 90 deg. therebetween. The members are welded with each other by moving the probes on the circumference of the members while being rotated. The pressure and the speed of rotation of the first and second probes are controlled to be same, respectively.

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 used for butt joining or lap joining of hollow cylindrical materials such as round pipes made of a material having plastic flowability such as metal and resin.

[0002]

2. Description of the Prior Art Two arranged in a butt state or a superposed state
The friction stir welding method for joining individual joining members is one of the solid-phase joining methods, in which a rotating probe is inserted into the abutting portion or overlapping portion of the joining member and the contact portion with this probe is rubbed. The probe is moved along the abutting portion or the superposed portion while being softened by heat and stirred, and then cooled and solidified to bond the both. That is, along with the movement of the probe, the softening and stirring portion receives the advancing pressure of the probe and is received by the passage groove of the probe, that is, the plastic flow is performed so as to wrap around in the backward direction of the advancing direction of the probe, and the friction heat is rapidly lost. It is cooled and solidified. This phenomenon is sequentially repeated as the probe moves, and finally both joining members are joined and integrated at the abutting portion or the overlapping portion.

Since such a friction stir welding method is a solid phase welding, there is no limitation on the kind of material of the welding member, and the welding method is more advantageous than the fusion welding methods such as MIG, TIG and laser welding. There are advantages such as little deformation due to thermal strain.

By the way, as a prior art, Japanese Patent No. 2792
A friction stir welding method according to Japanese Patent No. 233 is known.
In this method, one rotating probe pin is pressed against the joining portion of the joining member, and the material of the contact portion is plastically fluidized and agitated by frictional heat to join. This is effective because the roundness is secured when joining an object having rigidity against the pressing force of the probe pin which is a tool, for example, a solid round bar. However, when performing the circumferential welding of the hollow cylindrical material, the rigidity of the hollow cylindrical material is insufficient with respect to the pressing force of the tool, and the hollow cylindrical material is deformed into a flat shape, which reduces the roundness after joining. There was a problem.

To solve this problem, Japanese Patent Laid-Open No. 11-
The friction stir welding method disclosed in Japanese Patent No. 333572 is known. This method uses one receiving roller and two guide rollers each having a curved peripheral surface corresponding to the outer peripheral surface of the hollow cylindrical joining member, and uses three hollow cylindrical joining members to form the hollow cylindrical joining member.
While restraining from the direction, the probe is pressed against the joining member from the remaining one direction to perform friction stir welding.
That is, the shape of the hollow cylindrical joining member is to be held by using the restraint jig. However, in this known method, the circularity of the hollow cylindrical joining member is maintained because it is restrained by the restraint jig during welding, but immediately after joining, the temperature in the vicinity of the probe contact is higher than other parts. Therefore, there has been a problem that the roundness is slightly reduced due to cooling shrinkage after removing the restraint jig.

[0006]

Therefore, the present inventors have
In order to ensure the roundness of the hollow cylindrical joining member, it is considered necessary that the stress state of the joining member which is cylindrical at the time of joining can be kept symmetrical with respect to the cylinder axis, and the present invention has been achieved. is there. That is, the inventors of the present invention pay attention to the direction of the pressing force of the probe, and when the pressure is applied in only one direction, the hollow cylindrical joining member is crushed in the pressing direction and the joining member extends in the direction orthogonal to the pressing force. While it deforms to an elliptical shape, if the same amount of pressure is applied from two orthogonal directions, the stress state becomes symmetric with respect to the cylindrical axis, and deformation does not easily occur. It is a solution of points.

Therefore, an object of the present invention is to perform circumferential welding of a hollow cylindrical joining member without using a restraining jig,
An object of the present invention is to provide a friction stir welding method capable of joining a hollow cylinder without impairing the roundness.

[0008]

The present invention provides a friction stir welding method described in each of the claims as a means for solving the above-mentioned problems. The friction stir welding method according to claim 1 uses a first probe of a first rotating tool and a second probe of a second rotating tool to join two hollow cylindrical joining members. A position where the probe of 1 is pressed against the peripheral surface of the hollow cylindrical joining member,
The pressing position of the second probe against the peripheral surface of the hollow cylindrical joining member is approximately 9 on a plane orthogonal to the central axis of the hollow cylinder.
The angle is set to 0 °, and the first and second probes are joined together by rotating the first and second probes while moving on the circumference of the hollow cylindrical joining member. As a result, pressure is applied to the hollow cylindrical joining member by the first and second probes in two orthogonal directions, so that the stress state becomes substantially symmetrical with respect to the cylindrical axis, and deformation of the hollow cylindrical joining member can be prevented. .

According to the friction stir welding method of the second aspect, the first and second methods are provided.
The probe is pressed against the hollow cylindrical joint member with the same pressing force.
Since the same amount of pressing force is applied from the direction, the symmetry of the stress state with respect to the cylindrical axis becomes better, and the circularity of the hollow cylindrical joining member is maintained. According to the friction stir welding method of claim 3, the rotational speeds of the first and second probes are made substantially the same, whereby the first cylindrical portion of the hollow cylindrical member in contact with the first and second probes is rotated. The same frictional heat is generated at the part of the hollow cylindrical member that the two probes are in contact with, and the temperatures of both parts become equal. Therefore, the symmetry of the stress state with respect to the cylinder axis is maintained.

A friction stir welding method according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a friction stir welding method according to an embodiment of the present invention. First
The rotating tool 1 includes a cylindrical first rotating body 11 and a small-diameter pin-shaped first probe 12 that is integrally projected on an end axis of the first rotating body 11. Rotating body 1
The first probe 12 and the first probe 12 rotate together. The second rotary tool 2 also has the same structure as the first rotary tool 1, has a second rotary body 21 and a second probe 22, and both rotate integrally. The first and second rotating bodies 11 and 21 and the first and second probes 12 and 22 are heat-resistant and harder than the hollow cylindrical joining members 3 and 4 and can withstand frictional heat generated during joining. It is made of material.

The two hollow cylindrical joining members 3 and 4 are held by respective holding / rotating devices 5 and 6 in such a manner that their end faces abut each other. Holding / rotating device 5,
Reference numeral 6 has a holding mechanism such as a three-way chuck, and its shaft can be rotated by a driving device such as an electric motor. These holding / rotating devices 5 and 6 are naturally configured to rotate in synchronization.

The first rotary tool 1 and the second rotary tool 2, that is, the first probe 12 and the second probe 22 are on the peripheral surface of the hollow cylindrical joining members 3 and 4 and on the central axis of the hollow cylinder. In the plane orthogonal to the (cylindrical axis), they are arranged with their directions shifted by an angle of approximately 90 °. Further, the first and second rotary tools 1 and 2 each have a pressurizing device (not shown), and the joining portions of the hollow cylindrical joining members 3 and 4 by the first and second probes 12 and 22. The pressure applied to 30 can be changed.

The friction stir welding of the present invention constructed as described above is carried out as follows. The end portions of the two joining members 3 and 4 having a hollow cylindrical shape on the opposite side to the joining portion 30 are held by the holding / rotating devices 5 and 6, respectively.
The end faces of are brought into contact with each other to rotate both joint members 3 and 4 synchronously. Next, while rotating the first probe 12 of the first rotary tool 1 and the second probe 22 of the second rotary tool 2 which are arranged in directions different in angle by approximately 90 °, the hollow cylindrical joint member 3 , 4 are simultaneously pressed against the joints 30 on the circumference of the first and second probes 12, 22, and the first and second probes 12, 22 make one round of the outer circumference of the joint members 3, 4, and then the first and second rotary tools 1 , 2, that is, the first and second probes 12 and 22 are pulled up to complete the joining. Regarding the behavior of this joining, the joining is performed according to the same behavior as described in the related art.

In this case, when the first probe 12 of the first rotary tool 1 is pressed, the joining members 3 and 4 are crushed in the pressing direction and tend to extend in the circumferential direction.
Due to the pressurization of the second probe 22 of the second rotary tool 2 which is orthogonal to the stress, a stress is generated to cancel the deformation of the first rotary tool 1 due to the pressurization. The stress state becomes symmetric, and it is possible to join without impairing the roundness of the original cylindrical shape.

Incidentally, in order to cancel the stress by the first probe 12 of the first rotary tool 1 to make a cylindrical axially symmetric stress state, the second probe 22 of the second rotary tool 2 is in contact with the joint. It is necessary that the temperature and the pressing force of the part of the member are equal to the temperature and the pressing force of the part of the joining member with which the first probe 12 is in contact, and for that purpose, the first probe 12 and the second It is necessary to generate heat and generate rotational stress by making the pressing force of the probe 22 equal and making the first probe 12 and the second probe 22 have the same rotational speed to perform bonding. Further, by doing so, the temperature and cooling process in the vicinity of the probes 12 and 22 become equal, and the symmetry of the stress state is maintained.
As in the method disclosed in Japanese Patent No. 333572, it is possible to avoid the problem that the circularity of the hollow cylindrical shape is slightly lowered due to cooling shrinkage.

FIG. 2 shows a preferred joint shape adopted in the friction stir welding method of the present invention. (A) is a butt joint, (b) is a lap joint, and (c) is a spigot joint. Shows. Further, as the material of the joining member of the present invention, a metal having a plastic fluidity, for example, aluminum, copper, steel and its alloys / casting materials and die casting materials,
Examples thereof include resins having plastic flowability.

[0017]

As described above, in the friction stir welding method of the present invention, the accuracy of the roundness of the welded member after welding is good, and therefore, it is suitable for joining the welded members that are used in rotation. . Further, in the present invention, since the restraint jig is not required over the entire circumference of the joining member, space saving and weight saving of equipment can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a friction stir welding method according to an embodiment of the present invention.

FIG. 2 is a view exemplifying a joint shape of a joint member adopted in the friction stir welding method of the present invention, where (a) is a butt joint, (b) is a lap joint, and (c) is a spigot joint. Shows.

[Explanation of symbols] 1 ... 1st rotation tool 11 ... 1st rotating body 12 ... First probe 2 ... 2nd rotation tool 21 ... Second rotating body 22 ... Second probe 3, 4 ... Joining member 5, 6 ... Holding / rotating device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mutsumi Yoshino             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 4E067 AA01 AA19 BG00 DC07 EC06

Claims (3)

[Claims] 1. A circular cylinder of a hollow cylinder in which a probe of a rotating tool is brought into contact with a joint portion of two hollow cylindrical joint members, and the contact portion with the probe is softened and agitated by frictional heat while the probes are in contact with each other. In a friction stir welding method in which a welded portion is welded by relatively moving along a circumferential direction, a first probe of a first rotary tool and a second probe of a second rotary tool are used, and the first probe is used. The pressing position of the probe on the peripheral surface of the hollow cylindrical joint member and the pressing position of the second probe on the peripheral surface of the hollow cylindrical joint member,
An angle of about 90 ° is set on a plane orthogonal to the central axis of the hollow cylinder, and while rotating the first and second probes, the hollow cylindrical joint member is moved on the circumference of the two hollow cylinders. A friction stir welding method characterized by joining cylindrical joining members. 2. The friction stir welding method according to claim 1, wherein the first and second probes are pressed against the hollow cylindrical joining member with substantially the same pressing force. 3. The friction stir welding method according to claim 1, wherein the rotation speeds of the first and second probes are substantially the same.