JP2002248583A - Method and device for friction stir working - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for friction stir working, which can reduce thermal damage even during long-time joining, and prevent deformation after the joining and the working and a joining defect associated with the deformation, and oxidation. SOLUTION: In the method for the friction stir working, a rotating tool 1, which is firmer in material properties than a workpiece, is inserted into the workpiece while rotated, and frictional heat generated between the rotating tool 1 and the workpiece makes the workpiece undergo the joining or the working in atmosphere or a liquid. The atmosphere or the liquid of a joining part 5 or a working part is constantly eliminated by a non-oxidizing gas 3 during the joining or the working.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel friction stir processing method and apparatus, and more particularly, to a friction stir processing method for preventing oxidation and deformation after processing and defects caused by processing and improving the quality of a processed part. Regarding the device.

[0002]

2. Description of the Related Art In a friction stir processing method, a rotary tool (metal rod) made of a material substantially harder than the material of a workpiece is inserted into a processing portion, and the rotary tool is moved while rotating or the workpiece is rotated. This is a method of joining or processing by moving frictionally by frictional heat generated between a rotary tool and a workpiece by moving the workpiece itself. This is disclosed in Japanese Patent Publication No. 7-505090 (EP06154).
80B1). That is, the method utilizes a plastic flow phenomenon caused by frictional heat between the rotating tool and the workpiece, and does not melt and weld the workpiece as in arc welding. For this reason, there are many advantages such as joining at a temperature lower than the melting point of the metal.

[0003]

The friction welding method disclosed in Japanese Patent Publication No. 7-505090 involves joining or processing by frictional heat generated by a problem between a rotary tool and a workpiece. The joining method is particularly suitable for aluminum alloys. However, when the workpieces are joined by the joining method, the following problems occur.

When the joining length of the workpiece is long or thick even in the case of aluminum alloy, or when copper or steel with high rigidity of the workpiece is joined or machined, the rotating tool and the workpiece are connected to each other. The friction heat increases. For this reason, deformation (strain) after joining or processing is increased, and defects accompanying the deformation are likely to occur. Further, since the temperature of the rotating tool increases, thermal damage frequently occurs.

[0005] When processing in the air or water by the friction stir processing method, air or moisture comes into direct contact with the surface of the joint and the processed part, so that the surface of the processed material is particularly severely oxidized, and the quality and aesthetic appearance of the product are poor. Will drop. This is particularly remarkable in the case of iron, titanium alloy, magnesium alloy, and zirconium alloy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a friction stir processing method and apparatus capable of preventing deformation after bonding and working and bonding defects due to deformation and oxidation, and reducing thermal damage even during long-time bonding. It is in.

[0007]

SUMMARY OF THE INVENTION According to the present invention, when joining or working in the air or liquid by friction stirring, the joining portion at the tip of the rotary tool or the vicinity of the working portion is shielded from air or moisture in the air. It can be achieved by covering with a shield tube, filling the inside of the shield tube with an inert gas, and joining or processing in such a state that it is always jetted to the joint or the processing portion during the joining or processing. On the other hand, when joining by friction stir processing in a coolant such as water, oil, gas, etc. as a joining or working in a liquid, a rotating tool and a shield tube that shields the coolant near the working part are used. It can be achieved by covering and joining or processing the shield material in a state filled with an inert gas.

According to the present invention, a rotating tool made of a material harder than the workpiece is inserted into the workpiece while rotating, and the workpiece is heated by frictional heat generated between the rotating tool and the workpiece. In a friction stir processing method of joining or processing in air or liquid, the atmosphere or liquid in the joint or processed part is always removed by a non-oxidizing gas during the joining or processing.

The present invention also provides a rotating tool, which is made of a material harder than the workpiece, is inserted into the workpiece while rotating the workpiece, and frictional heat generated between the rotating tool and the workpiece causes the workpiece to rotate. In the friction stir processing method of joining or processing objects in the atmosphere, the air or liquid of the joint or the processing part is always eliminated by a non-oxidizing gas during the joining or the processing, and the joint or the processing part is removed. The joining or processing may be performed while injecting a liquid refrigerant to the outside of the non-oxidizing gas for cooling.

Injecting the non-oxidizing gas onto the surface of the workpiece while covering the entire circumference of the insertion portion of the rotary tool, and injecting the liquid refrigerant at least one of before and after in the joining or processing direction. It is preferable to carry out in.

According to the present invention, a rotating tool having an insertion portion of a material harder than the workpiece and inserted into the workpiece and a shoulder portion having a larger diameter than the insertion portion is inserted into the workpiece while rotating. In a friction stir processing apparatus that joins or processes the workpiece in the air or liquid by frictional heat generated between the rotary tool and the workpiece, the rotary tool is configured to be connected to the atmosphere or liquid at a joint or processing part. In addition, the present invention is characterized in that the present invention is characterized in that the present invention is characterized in that the present invention provides an insertion portion of the material harder than the workpiece to the workpiece and a shoulder having a larger diameter than the insertion portion. A friction stir processing apparatus that inserts a rotary tool having a portion into a workpiece while rotating the workpiece, and joins or processes the workpiece in the atmosphere by frictional heat generated between the rotary tool and the workpiece. At The rotary tool is characterized in that it comprises a shielding means for eliminating the atmosphere of the joint or processing unit by a non-oxidizing gas, a liquid refrigerant injection means for injecting a liquid refrigerant to the outside of the shield means.

[0012] The shield means is provided on the rotary tool so as to cover the entire circumference of the shoulder portion of the rotary tool, and to spray the non-oxidizing gas onto the surface of the workpiece. It is preferable that the refrigerant injection means is provided at least one of before and after in the joining or processing direction.

[0013]

The rotary tool and the vicinity of the processing portion are covered with a shield tube, and the shield tube is joined or processed in a state filled with an inert gas. Can be shielded from For this reason, oxidation, embrittlement, hardening, etc. of a joined part and a processed part can be prevented.

On the other hand, when joining or processing in water or in a coolant such as oil or gas, the rotary tool and the vicinity of the processing portion are covered with a shield tube for shielding the coolant, and the inside of the shield tube is inactivated. By joining or processing in a state filled with the unidirectional gas, processing can be performed without directly contacting the coolant. Therefore, even in water, portions other than the joint and the processed portion can be efficiently cooled by the coolant without generating oxidation, embrittlement, hardening, etc. in the joined or processed portion. Therefore, the temperature and deformation of the processed member can be reduced. Further, thermal damage to the rotating tool can be reduced.

[0015]

(Embodiment 1) FIG. 1 is a sectional view showing an embodiment in which a joining material made of an aluminum alloy is friction stir welded in the air. When the rotating tool 1 is rotated, the thin portion is inserted into the joining portion 5 of the material 4 to be joined, and moves in a tangent / joining direction while rotating, thereby joining by friction heat and a plastic flow phenomenon of the joining material. Is done. In the present invention, in order to shield the air or moisture of the atmosphere from the vicinity of the rotating tool 1 and the joint, the rotating tool 1 is covered with a shield tube 2,
Joining is performed with argon gas 3 flowing through the shield tube 2. The tip of the rotary tool 1 is thinly processed. The diameter of this tip is 5 mm and the diameter of the thick part is 15 m
m. Here, a shield tube 2 covering the rotating tool 1
Is 50 mm larger than the outer diameter of the rotary tool.
The rotary tool 1 has an insertion portion made of tool steel or the like which is harder than the material 4 to be inserted into the material 4 to be joined, and a shoulder portion having the same material as the insertion portion and a larger diameter.

The shield tube 2 is 300
Since the temperature becomes higher than ℃, it is made by molding heat-resistant carbon fiber into a cloth. Argon gas is continuously flowed at the time of bonding and released into the atmosphere. Here, the internal pressure of the shield tube can be kept higher than the atmospheric pressure by adjusting the flow rate of the argon gas. by this,
Since the rotating tool 1 and the joint 5 can be shielded from the atmosphere, oxidation of the surfaces of the rotating tool 1 and the joint 5 can be prevented. further,
Thermal damage to the rotary tool 1 and deformation of the bonding material 4 after bonding can be reduced. The bonding material 4 used in this embodiment has a thickness 8
mm, width 500mm, length 5000mm aluminum alloy (JIS standard A5083), rotation speed of rotating tool is 1000rpm, moving speed is 3
00 mm / min and the flow rate of argon gas is 20 l / min.

(Embodiment 2) In this embodiment, a description will be given of a case where a magnesium alloy, a zirconium alloy, and an iron alloy are butt-joined in the air according to the present invention as in Embodiment 1. In order to shield the vicinity of the rotating tool and the joint from the air or moisture of the atmosphere in the same manner as in the first embodiment, the rotating tool and the vicinity of the joint are covered with a shield tube, and the joining is performed in a state in which argon gas flows in the shielding material. . As a result, it has been confirmed that any of the bonding materials can provide a good bonded body having no oxidation and no defects on the surface.

(Embodiment 3) FIG. 2 is a perspective view showing an embodiment in which a cylindrical tube 6 made of an iron alloy manufactured by casting is subjected to friction stir processing while sprinkling water near the processing portion in the atmosphere. . The purpose of the present embodiment is to repair a bubble defect existing inside the cast alloy. Bubble defects existing inside the cylindrical tube 6 are agitated and compressed by the rotation of the rotary tool 1 and disappear. In order to shield the rotary tool 1 and the vicinity of the processing part from moisture, the rotary tool 1 is covered with a shield tube 2, and argon gas 3 is flowed into the shield tube 2, and argon gas 3 is applied to the surface of the processing part of the cylindrical tube 6. Process in the state of being sprayed. Further, in order to forcibly cool the vicinity of the processing part, the processing is performed while pouring water 7 near the processing part outside the argon gas 3.

The tip of the rotary tool 1 is processed to be thin, and the diameter of the tip is 5 mm and the diameter of the thick part is 15 mm. Here, the inner diameter of the shield tube 2 that covers the rotary tool 1 is 50 mm, which is slightly larger than the outer diameter of the rotary tool. The shield tube 2 is formed by molding heat-resistant carbon fiber into a cloth shape. The rotary tool 1 is processed by rotating and moving the cylindrical tube 6 after the thin portion is inserted into the processing portion in a rotated state.

The argon gas 3 is constantly flowed during processing,
It is released to the outside from the gap between the bonding material and the shield tube. By adjusting the flow rate of the argon gas 3, the pressure inside the shield tube 1 can be dynamically adjusted. Thereby, invasion of water from the outside in the vicinity of the processed portion can be shielded.

In this embodiment, the rotation speed of the rotary tool 1 is 1
OOOrpm, the moving speed of the cylindrical tube is 300mm / min. According to the present invention, oxidation of the surface of the casting alloy can be prevented, and a bubble defect existing inside the casting alloy can be repaired. Furthermore, since the rotating tool 1 and the vicinity of the joint can be efficiently cooled by the argon gas 3 and the water cooling 7, thermal damage to the rotating tool 1 and deformation of the cylindrical tube 6 after processing can be reduced.

(Embodiment 4) FIG. 3 is a cross-sectional view of a case where a superconducting coil in which a superconducting wire 8 made of an Nb-Ti alloy is embedded in a stabilizer 9 made of pure copper is joined in water 10. is there. Since the superconducting wire 8 of the Nb-Ti alloy loses superconducting properties at a temperature of 300 ° C. or higher, it must be joined at 30 ° C. or lower. For this reason, in this embodiment, friction stir welding is performed in the water tank 11 at 10 ° C.

In this embodiment, the rotary tool 1 is covered with a shield tube 2 made of a transparent acrylic tube, and is joined in water with an argon gas 3 flowing through the shield tube 2. The tip of the rotary tool 1 is processed to be thin, and the diameter of the tip is 2 mm and the diameter of the thick part is 6 mm. This thin portion is inserted into the butt joint of the copper stabilizing material 9 and moves in the joining line direction while rotating to be joined. Since the outer diameter of the rotating tool 1 is 6 mm, the inner diameter of the rotating tool 1. The shield tube 2 to cover is 15 m larger than the outer diameter of the rotating tool.
m.

The argon gas 3 is continuously flowed during the bonding, and is sequentially discharged into the water from the gaps on the surfaces of the shield tube 2 and the stabilizing material 9. Here, by adjusting the flow rate of the argon gas 3, the pressure in the shield tube 2 can be made higher than the external water pressure, so that no water enters the shield material 3. Therefore, since there is no contact with water in the vicinity of the joint, no oxidation of the surface of the pure copper as the stabilizing material is observed. In the present embodiment, the temperature of the rotating tool 1 is cooled to 300 ° C. or less, and the temperature near the superconducting wire 8 is cooled to 200 ° C. or less, so that the joining can be performed without impairing the superconducting characteristics. Furthermore, deformation after bonding can be reduced to 1/5 or less as compared with the case where the present invention is not carried out.
The rotation speed of the rotating tool is 100 rpm and the moving speed is 500 mm
/ min, the flow rate of argon gas is 30 liter / min.

(Embodiment 5) An embodiment in which each of a magnesium alloy, a zirconium alloy and an iron alloy as a joining material is friction stir welded in water will be described. In this embodiment, as in the fourth embodiment, the rotary tool and the joint are shielded from water in order to shield the vicinity of the rotary tool and the joint from water.Around the rotary tool and the joint are covered with a transparent acrylic shield tube, and argon gas is supplied into the shield tube. Join in the state. As a result, a good joined body having no oxidation and deformation on the surface of the joining material can be obtained.

(Embodiment 6) In this embodiment, the thickness is 40 mm and the width is 10 mm.
A case in which a bubble defect existing inside an aluminum alloy (JIS standard ADC1O) made by casting of 0 mm and length of 500 is repaired in water by the present invention will be described. Bubble defects existing in the aluminum alloy are eliminated because the inside of the alloy is agitated and compressed by the rotation of the rotating tool. In this embodiment, the rotary tool is covered with a shield tube made by molding a metal fiber into a cloth shape, and is repaired in water with nitrogen gas flowing through the shield tube. Since the outer diameter of the rotary tool in this embodiment is 30 mm, the inner diameter of the shield tube covering the rotary tool is 50 mm larger than the outer diameter of the rotary tool.

Here, since the pressure in the shield can be maintained higher than the water pressure in water by adjusting the flow rate of the argon gas, no water enters the shield tube. Accordingly, since there is no contact with water in the vicinity of the processed portion, no oxidation is observed on the surface of the aluminum alloy and the inside after the repair. Further, the deformation after the repair can be reduced to 1/10 or less as compared with the case where the present invention is not carried out. Further, since the rotating tool is also forcibly cooled by the nitrogen gas, the temperature of the rotating tool can be kept at 300 ° C. or less. Therefore, there is no thermal damage to the rotating tool. The aluminum alloy repaired by the present invention can be applied as a part for a white moving vehicle.

(Embodiment 7) In this embodiment shown in FIG. 4, a case in which a minute crack existing near the surface of a cylindrical stainless steel container having a thickness of 50 mm, a height of 6000 mm and a diameter of 5000 mm is repaired in water. explain. Crack defect 13 occurring on the surface of the stainless steel 12, the crack 13 is formed by the rotating tool.
By the rotation and movement of 1, the crack is agitated and compressed and disappears. As shown in FIG. 4, the rotating tool 1 is made of stainless steel 1
2 are arranged in a horizontal (horizontal) direction with respect to the cross section.
The shield tube 2 covering the rotary tool 1 is made of heat-resistant transparent glass. The shield tube 2 is in the shape of a trumpet whose tip end is widened.

Thus, the processing state during the processing can be observed. The crack is repaired in water with the argon gas 3 flowing in the shield tube 2. Since the outer diameter of the rotary tool 1 in this embodiment is 15 mm, the inner diameter of the shield tube 2 covering the rotary tool 1 is 50 mm larger than the outer diameter of the rotary tool. The argon gas 3 is continuously flown into the shield tube 2 and is sequentially discharged into water from a gap between the shield tube 2 and the stainless alloy surface 12. Here, a pressure sensor, a temperature sensor, a humidity sensor, and a CCD camera for observing a processing state are arranged in the shield tube.
Thereby, physical information and visual observation of the processing state in the processing process can be obtained.

For example, when the water depth of the rotary tool 1 changes in the water, the pressure inside the shield tube can always be kept higher than the water pressure by adjusting the flow rate of the argon gas. Therefore, there is no intrusion of water into the shield tube. Therefore, there is no contact with water in the vicinity of the crack, and no oxidation and defects are seen in the stainless steel and the inside after repair. In addition, the temperature of the rotating tool is 30
There is no thermal damage for a long time because it is cooled below 0 ° C. In the present invention, not only the rotating tool but also a drive mechanism for rotating and moving the rotating tool and a part of the control mechanism are covered with the shield tube, and a mechanism for preventing water from entering is provided. Further, the friction stir processing apparatus, the water shield mechanism, and the starting mechanism are mounted on a robot that can move up and down, left and right, and can repair or join a defect inside the equipment for a reactor and a ship efficiently underwater. .

(Embodiment 8) An example in which the present invention is applied to repair of a crack in a steam turbine blade will be described. FIG. 5 is a perspective view showing a case where a crack in a steam turbine blade is repaired by a friction stir processing method. The crack defect 13 generated near the surface of the turbine blade 14 is eliminated by agitating and compressing the crack portion by rotation and movement of the rotary tool 1. The shield tube 2 covering the rotary tool 1 is made of heat-resistant transparent glass. Thereby, the processing state during the processing can be observed. Cracks are repaired in the atmosphere with the argon gas 3 flowing through the shield tube 2. The shield tube 2 is in the shape of a trumpet whose tip is widened.

The outer diameter of the rotary tool 1 in this embodiment is lOm
m, the inner diameter of the shield member 3 covering the rotating tool 1 is 40 mm larger than the outer diameter of the rotating tool. The argon gas 3 is continuously flowed into the shield tube U, and is sequentially discharged into the atmosphere from a gap between the shield tube 2 and the surface of the turbine blade 14. Here, by adjusting the flow rate of the argon gas, the pressure in the shield tube can always be kept higher than the atmospheric pressure. Therefore, there is no invasion of air or moisture in the atmosphere into the shield tube 2. Therefore, since there is no contact with air or water near the cracked portion, surface oxidation near the processed portion can be prevented. Further, since the temperature of the rotating tool is cooled below 300 ° C., there is no thermal damage for a long time. In this embodiment, the friction stir processing apparatus, the shield mechanism, and the drive mechanism are attached to a robot that can move up and down, left and right, and move along the surface shape of the turbine blade. This object can also be achieved by fixing the processing device and moving the turbine blade by attaching it to a mobile robot.

[0033]

According to the present invention, it is possible to prevent deformation after bonding and processing and bonding defects due to the deformation, and to prevent deterioration of properties such as oxidation, embrittlement, and hardening of the processed material. Furthermore, in the processing of highly oxidizable metals such as zirconium alloys, titanium alloys, and magnesium alloys, it is possible to prevent oxidation after processing in water. On the other hand, since the rotating tool can be cooled efficiently, thermal damage can be reduced even during long-time joining.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an embodiment of the present invention.

FIG. 3 is a sectional view showing an embodiment of the present invention.

FIG. 4 is a perspective view showing an embodiment of the present invention.

FIG. 5 is a perspective view showing an embodiment of the present invention.

[Explanation of symbols]

1 ... rotating tool, 2 ... shield tube, 3 ... argon gas, 4 ...
Joining material, 5: weld, 6: cylindrical tube, 7: water, 8: superconducting wire, 9: copper stabilizer, 10: water, 11: container, 13: crack, 14
... Steam turbine blades.

Claims (8)

[Claims] 1. A rotating tool made of a material harder than a workpiece is inserted into the workpiece while rotating, and the workpiece is exposed to the atmosphere by frictional heat generated between the rotating tool and the workpiece. Alternatively, in a friction stir processing method of joining or processing in a liquid, a non-oxidizing gas is used to eliminate the atmosphere or liquid in a joint or a processed part during the joining or processing. 2. A rotating tool made of a material harder than a workpiece is inserted into the workpiece while rotating, and the workpiece is exposed to the atmosphere by frictional heat generated between the rotating tool and the workpiece. In the friction stir processing method of joining or processing at the same time, the atmosphere or liquid of the joining part or the processing part is always eliminated by a non-oxidizing gas during the joining or processing, and the non-oxidizing A friction stir processing method wherein the joining or processing is performed while injecting and cooling a liquid refrigerant to the outside of the gas. 3. The friction stir processing method according to claim 1, wherein the non-oxidizing gas is sprayed onto the surface of the workpiece while covering the entire periphery of the insertion portion of the rotary tool. 4. The friction stir processing method according to claim 2, wherein the injection of the liquid refrigerant is performed at least one of before and after the joining or processing direction. 5. A rotary tool having an insertion portion of a material harder than the workpiece and inserted into the workpiece and a shoulder portion having a larger diameter than the insertion portion is inserted into the workpiece while rotating. In a friction stir processing apparatus that joins or processes the workpiece in the air or liquid by frictional heat generated between the workpiece and the workpiece, the rotating tool removes air or liquid from the joint or the processing section. A friction stir processing apparatus comprising a shield means for eliminating by an oxidizing gas. 6. A rotary tool having a portion harder than the workpiece inserted into the workpiece and a shoulder having a larger diameter than the insertion portion is inserted into the workpiece while rotating. In a friction stir processing apparatus that joins or processes the workpiece in the atmosphere by frictional heat generated between the workpiece and the workpiece, the rotating tool eliminates the atmosphere of the joint or the processing section by a non-oxidizing gas. A friction stir processing apparatus, comprising: a shield means for performing liquid cooling; and a liquid refrigerant injection means for injecting a liquid refrigerant outside the shield means. 7. The rotating tool according to claim 6, wherein the shielding means is provided on the rotating tool so as to cover the entire circumference of the shoulder portion of the rotating tool and inject the non-oxidizing gas to the surface of the workpiece. A friction stir processing apparatus. 8. A friction stir processing apparatus according to claim 6, wherein said liquid refrigerant injection means is provided in at least one of before and after the joining or processing direction.