JP5863335B2 - Friction stir welding method - Google Patents

Description

  The present invention relates to a friction stir welding method and is devised so that wear of a friction stir welding tool can be suppressed.

Friction Stir Welding (FSW: Friction Stir Welding) maintains the state where the pin is inserted into the workpiece and the pin is inserted into the workpiece while rotating the friction stir welding tool with the pin on the tip of the rotating rod. On the other hand, this is a joining method in which a rotating friction stir welding tool is moved laterally along the surface of an object to be joined to stir (plastic fluidize) the material softened by frictional heat.
This friction stir welding has an advantage that the metal structure is miniaturized and has excellent mechanical properties because the solid-phase joining is performed unlike ordinary fusion welding.

  Such friction stir welding is widely used for joining light metal materials (low melting point materials) such as aluminum, but in recent years, high strength materials (high melting point materials) such as steel, stainless steel, nickel base alloys, etc. Application studies have also begun on these joints.

  Friction stir welding can be applied to bonding in the atmosphere, etc., as well as bonding of objects to be bonded in liquids (liquid sodium, water, oil, etc.), cracks that have occurred in objects to be bonded in liquid, etc. Consideration of application has also begun when repairing.

  Here, the prior art which carries out friction stir welding of the base material (to-be-joined object) in a liquid is demonstrated, referring FIGS.

As shown in FIGS. 4 to 6, the friction stir welding tool 10 is configured by integrally including a pin 12 at the center of a shoulder surface 14 that is a distal end surface of a cylindrical rotating rod 11. The pin 12 is coaxial with the rotating rod 11 and protrudes from the center of the shoulder surface 14. A right thread groove 13 is formed on the peripheral surface of the pin 12.
A liquid (water, liquid sodium, or the like) 21 is stored in the liquid tank 20, and a base material 30 that is an object to be joined is immersed in the liquid 21.

  The procedure for friction stir welding of the base material 30 immersed in the liquid 21 with the friction stir welding tool 10 is as follows.

  As shown in FIG. 4, while rotating the friction stir welding tool 10 counterclockwise RL, the tip (lower end) of the pin 12 is brought into contact with the surface (upper surface) of the base material 30 and then pushed downward (lowered). Then, frictional heat is generated between the rotating pin 12 and the base material 30, and the base material 30 is softened by the frictional heat to become the plastic fluid material 31.

  Since the portion of the base material 30 that is in contact with the pin 12 and the periphery thereof are softened to become the plastic fluid material 31, the pin 12 of the friction stir welding tool 10 that is pushed downward while rotating counterclockwise RL is shown in FIG. As shown in FIG.

  In this way, the pin 12 of the friction stir welding tool 10 that is rotating counterclockwise RL is inserted into the base material 30, the pin 12 is completely buried in the base material 30, and the shoulder surface 14 is the surface position of the base material 30. Is reached, the descent of the friction stir welding tool 10 is stopped. Thereby, the insertion process to the base material 30 of the pin 12 is completed.

When the process of inserting the pin 12 into the base material 30 is completed, the friction stir welding tool 10 that is rotating left RL is maintained while maintaining the state where the pin 12 is inserted into the base material 30 as shown in FIG. Move sideways along the surface of 30.
At this time, the frictional heat generated between the shoulder surface 14 and the base material 30 is added to the frictional heat generated between the pin 12 and the base material 30, and the amount of generated heat increases rapidly. A large amount of the plastic fluid material 31 is generated.

The softened plastic fluid material 31 plastically flows in the rotational direction while being agitated by the rotation of the shoulder surface 14 and the pin 12.
Further, when the pin 12 in which the right screw groove 13 is formed rotates counterclockwise RL, an action similar to that of the screw pump is generated, and the soft plastic fluid material 31 is on the proximal end side (shoulder surface side) of the pin 12. To the tip side (lower end side) of the pin 12 and plastically flow in the axial direction and stirred.
As described above, the plastic flow material 31 (softened base material 30) softened by frictional heat plastically flows not only in the rotation direction but also in the axial direction, so that the stirring force is improved and the inside of the joint, particularly in the bottom portion, is improved. Generation of defects (such as cavities) is suppressed.

  In Patent Document 1, when friction stir welding is performed in a liquid, a non-oxidizing gas such as argon gas is supplied to the bonding portion, thereby eliminating the liquid from the bonding portion and preventing the occurrence of oxidation. Technology is disclosed. However, no mention is made of reducing wear in the pin insertion process.

Japanese Patent Laid-Open No. 2002-245853

By the way, in the environment where the base material 30 is a high melting point material such as an iron-based material, and cooling (heat removal) of the base material 30 is performed by the surrounding liquid 21 as in the examples shown in FIGS. When performing friction stir welding, since the pin 12 of the friction stir welding tool 10 is inserted into the base material 30 in a state where the base material 30 is not sufficiently heated, the tool wear of the friction stir welding tool 10 is large, and the tool There is a problem that the lifetime is shortened.
Moreover, since the pin 12 in which the right thread groove 13 is formed is inserted while rotating counterclockwise, the frictional resistance becomes very large when inserted, and there is a problem that the tool wear of the friction stir welding tool 10 is remarkable.

  As shown in FIG. 6, when the friction stir welding tool 10 rotating left RL is moved laterally along the surface of the base material 30 while maintaining the state where the pin 12 is inserted into the base material 30, Since a large amount of frictional heat is generated between the pin 12 and the base material 30 and between the shoulder surface 14 and the base material 30, a large amount of plastic flow material 31 is generated, so that the frictional resistance applied to the pin 12 is reduced. To do. As a result, tool wear during lateral movement is small, and tool wear during lateral movement is not a problem.

  In view of the above-described conventional technology, the present invention provides a step of inserting a pin into an object to be joined (base material) particularly when performing friction stir welding using a friction stir welding tool in which a thread groove is formed on a pin. An object of the present invention is to provide a friction stir welding method that can reduce tool wear.

The configuration of the present invention for solving the above problems is as follows.
While rotating the friction stir welding tool provided with a pin having a thread groove formed on the tip surface of the rotating rod, the pin is inserted into the workpiece,
Then, while maintaining the state where the pin is inserted into the object to be bonded, in the friction stir welding construction method of moving laterally along the surface of the object to be bonded while rotating the friction stir welding tool,
The rotation direction of the friction stir welding tool is opposite to the rotation direction in which the plastic flow material is plastically flowed in the axial direction from the proximal end side to the distal end side of the pin by the rotation of the pin formed with the thread groove. Insert the pin into the workpiece while keeping the direction ,
Next, the rotation direction of the friction stir welding tool is the rotation direction in which the plastic flow material is plastically flowed along the axial direction from the proximal end side to the distal end side of the pin by the rotation of the pin formed with the thread groove. With the reverse rotation direction, the pin is once pulled out from the workpiece.
Next, the rotation direction of the friction stir welding tool is switched to a rotation direction in which the plastic flow material is plastically flowed along the axial direction from the proximal end side to the distal end side of the pin by rotation of the pin formed with the thread groove. Then, insert the pin into the workpiece again,
Next, the rotation direction of the friction stir welding tool is a rotation direction in which the plastic flow material is plastically flowed along the axial direction from the proximal end side to the distal end side of the pin by the rotation of the pin formed with the thread groove . While keeping the state that the pin is inserted into the object to be joined,
It is characterized by that.

  According to the present invention, in the friction stir welding method, when the pin is inserted into the workpiece, the rotation direction of the friction stir welding tool is set to the rotation of the pin formed with a screw groove (for example, a right screw groove). The rotation direction (right rotation) is opposite to the rotation direction in which the plastic flow material plastically flows along the axial direction from the base end side to the tip end side of the pin. Life span is extended.

The block diagram which shows the friction stir welding construction method of this invention. The block diagram which shows the friction stir welding construction method of this invention. The block diagram which shows the friction stir welding construction method of this invention. The block diagram which shows the conventional friction stir welding construction method. The block diagram which shows the conventional friction stir welding construction method. The block diagram which shows the conventional friction stir welding construction method.

  Hereinafter, embodiments of the present invention will be described in detail based on examples.

  An embodiment of the present invention for friction stir welding of a base material (a workpiece) in a liquid will be described with reference to FIGS.

As shown in FIGS. 1 to 3, the friction stir welding tool 10 is configured by integrally including a pin 12 at the center of a shoulder surface 14 that is a distal end surface of a cylindrical rotating rod 11. The pin 12 is coaxial with the rotating rod 11 and protrudes from the center of the shoulder surface 14. A right thread groove 13 is formed on the peripheral surface of the pin 12.
A liquid (water, liquid sodium, or the like) 21 is stored in the liquid tank 20, and a base material 30 that is an object to be joined is immersed in the liquid 21.

  The procedure of the present invention in which the base material 30 immersed in the liquid 21 is friction stir welded by the friction stir welding tool 10 will be described as follows.

  As shown in FIG. 1, in this embodiment, the friction stir welding tool 10 is not rotated left RL but rotated right RR, and the tip (lower end) of the pin 12 is brought into contact with the surface (upper surface) of the base material 30. Push down (lower). Then, frictional heat is generated between the rotating pin 12 and the base material 30, and the base material 30 is softened by the frictional heat to become the plastic fluid material 31.

  The portion of the base material 30 that is in contact with the pin 12 and the periphery thereof are softened to become the plastic fluid material 31, so that the pin 12 of the friction stir welding tool 10 that is pushed downward while rotating right RR is shown in FIG. As shown in FIG.

In this embodiment, as shown in FIGS. 1 and 2, when the pin 12 is inserted into the base material 30, the pin 12 in which the right screw groove 13 is formed is rotated to the right RR. The pin 12 of the stir welding tool 10 can be easily inserted (entered) into the base material 30, the frictional resistance is reduced, and tool wear is suppressed.
That is, when the pin 12 is inserted into the base material 30, the rotational direction of the friction stir welding tool 10 causes the plastic flow material 31 to plastically flow along the axial direction from the proximal end side to the distal end side of the pin 12. Tool wear is suppressed by setting the rotation direction (right rotation RR) opposite to the rotation direction (left rotation RL).

  In this way, the pin 12 of the friction stir welding tool 10 rotating in the clockwise direction RR is inserted into the base material 30, the pin 12 is completely buried in the base material 30, and the shoulder surface 14 is the surface position of the base material 30. Is reached, the descent of the friction stir welding tool 10 is stopped. Thereby, the insertion process to the base material 30 of the pin 12 is completed.

When the process of inserting the pin 12 into the base material 30 is completed, the rotation direction of the friction stir welding tool 10 is switched from the right rotation RR to the left rotation RL.
That is, the rotation direction of the friction stir welding tool 10 is switched to the rotation direction (left rotation RL) in which the plastic flow material 31 is plastically flowed along the axial direction from the proximal end side to the distal end side of the pin 12.

  Note that the rotation direction of the friction stir welding tool 10 is switched by reversing the rotation direction of the motor that rotationally drives the friction stir welding tool 10 or the reverse rotation gear to the transmission mechanism that transmits the rotational force to the friction stir welding tool 10. This is carried out by biting the reverse rotation gear.

When the rotation direction of the friction stir welding tool 10 is switched from the right rotation RR to the left rotation RL, as shown in FIG. 3, the friction stirrer rotating left RL while maintaining the state where the pin 12 is inserted into the base material 30 is maintained. The joining tool 10 is moved laterally along the surface of the base material 30.
At this time, the frictional heat generated between the shoulder surface 14 and the base material 30 is added to the frictional heat generated between the pin 12 and the base material 30, and the amount of generated heat increases rapidly. A large amount of the plastic fluid material 31 is generated.

The softened plastic fluid material 31 plastically flows in the rotational direction while being agitated by the rotation of the shoulder surface 14 and the pin 12.
Further, when the pin 12 in which the right screw groove 13 is formed rotates counterclockwise RL, an action similar to that of the screw pump is generated, and the soft plastic fluid material 31 is on the proximal end side (shoulder surface side) of the pin 12. To the tip side (lower end side) of the pin 12 and plastically flow in the axial direction and stirred.
As described above, the plastic flow material 31 (softened base material 30) softened by frictional heat plastically flows not only in the rotation direction but also in the axial direction, so that the stirring force is improved and the inside of the joint, particularly in the bottom portion, is improved. Generation of defects (such as cavities) is suppressed.

  Moreover, as shown in FIG. 3, when the friction stir welding tool 10 rotating left RL is moved laterally along the surface of the base material 30 while maintaining the state where the pin 12 is inserted into the base material 30, Since a large amount of frictional heat is generated between the pin 12 and the base material 30 and between the shoulder surface 14 and the base material 30, a large amount of plastic flow material 31 is generated, so that the frictional resistance applied to the pin 12 is reduced. To do. As a result, tool wear during lateral movement is small, and tool wear during lateral movement is not a problem.

  As described above, in this embodiment, the friction stir welding tool 10 in which the right screw groove 13 is formed in the pin 12 is rotated to the left at the time of lateral movement, but is rotated to the right at the time of insertion. Wear can be suppressed and the tool life can be extended.

  When the pin 12 has a left thread groove, the friction stir welding tool 10 is rotated counterclockwise during insertion, and the friction stir welding tool 10 is rotated clockwise during lateral movement, thereby reducing tool wear during insertion. Suppressing and extending tool life.

In addition, it is desirable to perform switching of the rotation direction of the friction stir welding tool 10 continuously (immediately).
However, for example, when the right screw groove 13 is formed in the pin 12, after the insertion process is completed while rotating clockwise, the friction stir welding tool 10 is once extracted while rotating clockwise, and then the rotation direction is rotated counterclockwise. After switching to, the insertion process is performed again, and if the base material 30 is sufficiently heated by the start of lateral movement (by providing a waiting time, etc.) and then moved laterally, the rotation direction is switched. Need not be performed continuously.

DESCRIPTION OF SYMBOLS 10 Friction stir welding tool 11 Rotating rod 12 Pin 13 Right-hand thread groove 14 Shoulder surface 20 Liquid tank 21 Liquid 30 Base material (to-be-joined)
31 Plastic flow material

Claims (1)

While rotating the friction stir welding tool provided with a pin having a thread groove formed on the tip surface of the rotating rod, the pin is inserted into the workpiece,
Then, while maintaining the state where the pin is inserted into the object to be bonded, in the friction stir welding construction method of moving laterally along the surface of the object to be bonded while rotating the friction stir welding tool,
The rotation direction of the friction stir welding tool is opposite to the rotation direction in which the plastic flow material is plastically flowed in the axial direction from the proximal end side to the distal end side of the pin by the rotation of the pin formed with the thread groove. Insert the pin into the workpiece while keeping the direction ,
Next, the rotation direction of the friction stir welding tool is the rotation direction in which the plastic flow material is plastically flowed along the axial direction from the proximal end side to the distal end side of the pin by the rotation of the pin formed with the thread groove. With the reverse rotation direction, the pin is once pulled out from the workpiece.
Next, the rotation direction of the friction stir welding tool is switched to a rotation direction in which the plastic flow material is plastically flowed along the axial direction from the proximal end side to the distal end side of the pin by rotation of the pin formed with the thread groove. Then, insert the pin into the workpiece again,
Next, the rotation direction of the friction stir welding tool is a rotation direction in which the plastic flow material is plastically flowed along the axial direction from the proximal end side to the distal end side of the pin by the rotation of the pin formed with the thread groove . While keeping the state that the pin is inserted into the object to be joined,
A friction stir welding method characterized by that.

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