JP2003089884A - Surface reforming method and device for workpiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a surface reforming layer having excellent mechanical characteristics, corrosion resistance, wear resistance, electrical characteristics, etc. SOLUTION: The surface of a base metal 1 of a workpiece is reformed by forming a coating layer 2 on the surface of the base metal 1, then inserting a rotary tool 3 to perform circulating motion into the workpiece from its surface and relatively moving the rotary tool 3 and the workpiece in this state, thereby frictionally agitating the coating layer 2 or the base metal 1 and the coating layer 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface modification method and apparatus used for improving the characteristics of a workpiece used in various industrial fields.

[0002]

2. Description of the Related Art Conventionally, thermal spraying, plating, diffusion permeation, physical vapor deposition, chemical vapor deposition have been used as methods for enhancing functions such as mechanical properties, corrosion resistance, abrasion resistance, and electrical conductivity of metals. Many surface modification methods have been used such as ion implantation and ion implantation.

[0003]

Each of these methods has advantages and disadvantages, but common problems are adhesion at the interface between the base material and the coating layer, pores existing in the coating layer, and the base material Thermal effects are a factor that hinders the application of products.

In order to solve these problems, the surface layer is reformed again by post-treatment such as laser heating.

However, in the case of laser heating or the like, when the heat input amount is increased to improve the adhesion, the base material is thermally affected or the coating layer is cracked, and conversely, when the heat input amount is small,
It is extremely difficult to optimize the construction conditions such as insufficient reforming, and it is hardly used in practice.

[0006]

Therefore, recently, inside the surface layer formed by a thermal spraying method, a plating method, a diffusion permeation treatment, a physical vapor deposition method, a chemical vapor deposition method, ion implantation, or the like,
Alternatively, it has been attempted to modify the surface layer and the base material again by friction stirring.

At present, friction stir is mainly used for joining plate materials. This friction stir welding method is disclosed, for example, in Japanese Patent No. 2712838.
As described in JP-A-9-508073 and JP-A-9-508073, a rotor that is harder than the work piece is brought into contact with the work piece, and the frictional heat and pressure generated thereby cause plastic fluidization of the work piece material. It is based on the fact that the rotor can be moved in an embedded state in the workpiece by causing it.

That is, when the rotor is moved along the butt joint line of the two plates, the two plates are agitated by the plastic flow generated in front of the moving rotor, and after the move, the plates are rapidly cooled. Solidify, and finally the two are completely integrated.

Further, it is also disclosed in Japanese Patent Laid-Open No. 2000-246114 that the friction stir is utilized for local surface modification. However, in the method disclosed in this publication, since the concave portion is formed in the base material and the powder of the modifying material is introduced into the concave portion, the modified portion is local, and the machining before the treatment is performed. There are problems such as being indispensable.

The present invention solves the above problems and provides a method and apparatus for modifying the surface of a work piece which has a very small heat effect on the base material and has a very high adhesion to the base material. To aim.

[0011]

In order to achieve the above object, the present invention is to carry out surface modification of a work piece by the following method and apparatus.

In the invention corresponding to claim 1, after forming a coating layer on the surface of a base material of a workpiece, a tool for circulating motion is inserted from the surface side of the workpiece, and in this state, the tool and the By moving the workpiece relative to each other, the coating layer or the base material and the coating layer are frictionally stirred to modify the surface of the base material.

According to a second aspect of the invention, in the method for modifying the surface of a workpiece according to the first aspect of the invention, the adhesion strength between the coating layer and the base material before friction stir processing is 10M.
Pa or higher.

According to a third aspect of the invention, in the surface modification method for a work piece according to the first aspect, the coating layer is formed by a thermal spraying method.

According to a fourth aspect of the present invention, in the surface modification method for a workpiece according to the third aspect of the invention, the velocity of the spray particles in the thermal spraying method is 500 m / s or more.

According to a fifth aspect of the invention, in the method for modifying the surface of a workpiece according to the first aspect of the invention, the base material on which the coating layer is formed is used as a heating element, a combustion gas flame, a plasma flame, Friction stirring is performed while heating with either infrared lamp heating or high frequency heating.

According to a sixth aspect of the present invention, in the method for modifying the surface of a work piece according to the first aspect of the present invention, the periphery of a region where the tool is in contact with the work piece or the entire apparatus is Friction stir while shielding with an inert gas.

According to a seventh aspect of the present invention, in the method for modifying the surface of a work piece according to the first aspect of the present invention, the work piece, the tool, or the entire apparatus is placed in a vacuum container and the atmosphere is reduced. Modify the surface of the base metal with.

According to an eighth aspect of the invention, in the method for modifying the surface of a work piece according to the first aspect of the invention, the area around the area where the tool is in contact with the work piece or the entire apparatus is The base material surface is modified while blowing oxygen, nitrogen, or a mixed gas containing at least one of these.

According to a ninth aspect of the invention, in the method for modifying the surface of a workpiece according to the first aspect of the invention, the ratio of the thickness of the coating layer formed before friction stirring to the insertion depth of the tool is set. By friction stirring under the changed state, the surface modified layer having a different composition depending on the site is formed.

According to a tenth aspect of the present invention, in the method for modifying the surface of a workpiece according to the first aspect of the present invention, the coating layer has two or more layers whose thickness ratio is changed before friction stirring. The coating layer is composed of layers, and the surface-modified layer having different composition / characteristics is formed by friction stirring the coating layer.

The invention corresponding to claim 11 is provided with a thermal spraying mechanism for forming a coating layer on the surface of the base material by the thermal spraying method and a surface modification processing mechanism by the friction stir method. Further, while moving the surface modification treatment mechanism, a coating layer is formed on the surface of the base material by the thermal spraying treatment mechanism, and at the same time, the workpiece is surface-modified by the surface modification treatment mechanism.

According to a twelfth aspect of the invention, there is provided a thermal spray treatment mechanism which is movably supported in the vertical direction with respect to the base material and forms a coating layer on the surface of the base material by a thermal spraying method. Surface modification treatment for performing surface modification by a friction stir method on a workpiece integrally supported at a position and movably in a direction perpendicular to the base material and having a coating layer formed by the thermal spraying mechanism. A mechanism and a moving means for relatively moving the base material and both mechanisms.

In the invention corresponding to claim 13, a groove is machined on the outer circumference or the inner circumference of a cylindrical work piece or a cylindrical work piece, and the groove is covered with a hard material by a thermal spraying method. After filling, the workpiece is rotated while the rotary tool is inserted into the groove to form a wear resistant layer around the outer or inner groove.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing a first embodiment for explaining the surface modification method according to the present invention.

In FIG. 1, first, the coating layer 2 is formed on the surface of the base material 1 by any one of the thermal spraying method, the plating method, the diffusion permeation treatment, the physical vapor deposition method, the chemical vapor deposition method, and the ion implantation. Next, the rotary tool 3 is inserted from the surface side of the workpiece.

The rotary tool 3 performs a rotary motion, a translation motion, or a cyclic motion consisting of a combination thereof, but the rotary motion is most preferable because the device structure is simple and the load on the tool is small.

If a spiral groove is formed at the tip of the rotary tool 3, the material flows along the groove from a shallow portion to a deep portion or from a deep portion to a shallow portion. Therefore, the stirring of the material is realized more effectively.

Therefore, the grooved rotary tool 3 is applied to the coating layer 2
It is embedded while pressing its surface, and after being sufficiently heated by frictional heat, the rotary tool 3 and the workpiece are relatively moved. In the figure, the rotary tool 3 is translated. This time,
When the insertion depth of the rotary tool 3 is smaller than the film thickness,
It becomes possible to modify only the inside of the coating layer 2, and when the insertion depth exceeds the film thickness, it becomes possible to form the surface modified layer 4 in which the coating layer 2 and the base material 1 are agitated. Become.

Here, the material of the base material 1 is not particularly limited as long as it is a work piece or a resin, but in the case of a work piece, aluminum having a lower melting point is more likely to cause plastic flow. It is most easily applied to magnesium, copper and their alloys.

As the material of the coating layer 2, it is possible to apply a work piece or a resin, but it is easier to apply the material having a lower melting point as in the base material.

By the way, the adhesion strength between the coating layer 2 and the base material 1 has a great influence on the properties (particularly the porosity) of the surface layer after friction stirring.

FIG. 2 is a graph showing the relationship between the adhesion strength between the coating layer 2 and the base material 1 and the porosity. As is clear from this figure, when the adhesion strength is 10 MPa or less, the base material and the coating layer are peeled off during frictional stirring, and the resulting pores are present, making it impossible to form a good surface layer. Especially 3M
When it was Pa or less, peeling of the coating layer occurred and the processing itself was impossible. On the other hand, when the adhesion strength between the coating layer 2 and the base material 1 is 10 MPa or more, the porosity in the surface layer becomes small, and a film having an excellent structure can be formed.

As the method of forming the surface layer before frictional stirring, as described above, the slurry method, the thermal spraying method, the plating method,
There are methods such as diffusion permeation treatment, physical vapor deposition method, chemical vapor deposition method, and ion implantation. Among them, the thermal spraying method is easy to form a thick film and has a wide selection of coating materials.
It is considered to be suitable for surface modification because of the relatively high adhesion strength between the base material and the coating layer. Furthermore, because there are easily deformable parts such as pores and laminated interfaces inside the coating layer, a good film can be formed after friction stirring even if the amount of deformation of the material itself is small. It can be said that the thermal spraying method is also suitable for the surface modification method of the present invention.

FIG. 3 shows that after the coating layer is formed by using several kinds of thermal spraying methods having different sprayed particle velocities, friction stirring is performed.
It is a graph which shows the result of having observed and quantified the defect inside the formed surface layer with an optical microscope.

As can be seen from this graph, even in the thermal spraying method, the particle velocity using a high-speed combustion flame is 500 m.
Since the average value of the amount of defects in the surface layer is lower than 10% when the high-speed spraying method of / s or more is used, it is clear that the high-speed spraying method is suitable as the spraying method used for the surface treatment. .

Therefore, in the present embodiment, the adhesion strength between the coating layer 2 and the base material 1 before the friction stir processing is 10 MPa or more, and the velocity of the spray particles having a small defect rate in the surface layer is 500 m / s or more. The coating layer is formed using the thermal spraying method.

According to such a surface modification method, it is possible to form a surface film which is less affected by the heat of the base material and has an extremely high adhesion to the base material.

In the above-described embodiment, the work is carried out while shielding the rotary tool 3 around the region in contact with the workpiece or the entire apparatus with an inert gas such as argon, helium or a mixed gas thereof. You may do it.

Further, the workpiece, the tool, or the entire apparatus may be put in a vacuum container and the work may be carried out under a reduced pressure atmosphere.

FIG. 4 is a block diagram showing an example of an apparatus for modifying the coating layer on the surface of the base material in vacuum.

In FIG. 4, the work piece 14 is fixed on the movable bed 12 in the vacuum container 13 and moves in translation. On the other hand, the rotary tool 3 is connected to a motor 10, which is vertically movable by a vertical drive mechanism 11.

In this case, in order to precisely control the machining amount, it is possible to provide a tool positioning mechanism or a tool load control mechanism using a load cell.

Reference numeral 15 in the figure denotes a vacuum pump for vacuuming the inside of the vacuum container 13.

FIG. 5 shows the construction of the above-mentioned surface modification.
It is a graph which shows the comparison result of the amount of impurities which remain in the inside of a film by the usual method, the method using a shield gas, and the construction in vacuum.

As is clear from this graph, according to the method of shielding with an inert gas, the amount of impurities inside the film mainly composed of oxide is remarkably reduced, and a film with excellent characteristics is formed. Is possible.

Further, if the work is carried out in vacuum, the amount of impurities remaining inside the film can be further reduced.

The degree of vacuum at this time is 13 kPa.
Since the amount of impurities is remarkably suppressed when it is (100 Torr) or less, it is desirable to set it to this value or less.

By thus placing the work piece and the rotary tool in vacuum, the amount of residual impurities in the film is greatly reduced as compared with the use of the shield gas, but continuous processing cannot be performed in vacuum. It is preferable to use these in accordance with the intended use in consideration of the fact that it is expensive.

FIG. 6 is a schematic view showing a second embodiment for explaining the surface modification method according to the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Now let's talk about the differences.

In this embodiment, as shown in FIG. 6, frictional stirring is performed by the rotary tool 3 while heating the surface of the workpiece by heating with the infrared lamp 5.

In this case, the heating portion has to move to the periphery of the stirring section according to the movement of the rotary tool 3. Therefore, when the workpiece moves, the driving mechanism of the heating source is not necessary, but when the position of the rotary tool 3 itself moves, the rotary tool 3 and the infrared lamp 5 are integrated, or It is necessary to move the heating source itself by its own moving mechanism.

If the base material 1 is a material having a relatively high melting point such as an iron-based material, it is difficult to heat it until frictional heating alone causes plastic flow, and the load on the rotary tool 3 is large. Become.

By externally heating the surface of the workpiece by the infrared lamp 5 as in the present embodiment, the life of the rotary tool 3 is significantly improved.

As an external heating method, in addition to heating by an infrared lamp, any one of a heating element, combustion gas flame, plasma flame, high frequency heating, or a combination of two or more methods can be used. It can be used properly depending on the application.

Further, it is not always necessary to perform local heating, and the whole may be heated using an electric furnace or the like.

FIG. 7 is a schematic diagram showing a third embodiment for explaining the surface modification method according to the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Now let's talk about the differences.

In this embodiment, a gas cylinder 8 filled with argon as an inert gas and a gas cylinder 9 filled with oxygen as a reactive gas are used as shown in FIG.
Argon gas and oxygen gas are supplied from these gas cylinders 8 and 9 to the nozzle 6 through a valve 10 and a regulator, and the rotary tool 3 supplies a mixed gas of an inert gas and a reaction gas through the nozzle 6 to the workpiece. The gas atmosphere 7 is formed by ejecting the gas atmosphere 7 around the region in contact with the.

In the above embodiment, nitrogen gas may be used as the reaction gas instead of oxygen.

FIG. 8 is a graph showing the comparison of the hardness of the surface layer formed by the normal construction in which oxygen or nitrogen is blown around the friction stirrer and that when it is not blown.

As is clear from this graph, the hardness is improved by 1.5 times or more by spraying oxygen and nitrogen, as compared with the case where the work is performed in the atmosphere. This is because the blowing of oxygen or nitrogen causes the oxides and nitrides formed on the surface during friction stir to be entrained and mixed into the surface layer, and these compounds increase the hardness and wear resistance. It is considered to have improved.

By controlling the mixing ratio of the argon gas and the oxygen gas, it is possible to change the amount of the reaction layer contained in the surface modification layer according to the site of the workpiece, and Different coatings can be realized in one step.

In each of the above embodiments, a coating layer is formed on the surface of the base material, and a rotary tool is inserted through the coating layer into the base material and friction stirring is performed to form the surface modification layer. However, the surface modification layer may be formed by the following method.

(1) The ratio of the thickness of the coating layer formed before frictional stirring to the insertion depth of the tool used for frictional stirring is changed to form a surface layer having a different composition depending on the site.

FIG. 9 is a graph showing the relationship between film thickness and hardness.

By controlling the insertion depth of the tool based on the relationship between the coating thickness before the stirring treatment and the Vickers hardness of the coating after the stirring treatment shown in this graph, a surface layer having a different composition depending on the site is formed. You can

For example, for a portion requiring sufficient abrasion resistance, the hard material coating layer before the stirring treatment should be thicker, and conversely, for a portion requiring softness of the material. By forming a thin film and then performing friction stir processing, it is possible to form parts in a single process according to the required characteristics that change for each part of the product.

(2) A coating layer consisting of two or more layers is formed before frictional stirring, the thickness ratio of each layer is changed, and after frictional stirring, a surface layer having different composition and characteristics is formed depending on the site.

FIG. 10 is a graph showing the relationship between the thickness ratio of the two-layer film thickness before the stirring treatment and the Vickers hardness of the film after the stirring treatment.

By controlling the composition and film thickness of each layer based on the relationship shown in this graph, a coating layer having various compositions and characteristics can be realized on one component in one step.

Further, in each of the above-described embodiments, the description has been made on the premise that the coating layer is formed on the surface of the base material, but the coating layer may be a thermal spraying method, a plating method, a diffusion permeation treatment, a physical vapor deposition method, a chemical vapor deposition method. It goes without saying that it also includes those in which a surface modification layer is formed on the surface of the base material using either the vapor deposition method or the ion implantation.

Next, an embodiment of the surface modification device according to the present invention will be described.

FIG. 11 is a block diagram showing an example of a surface reforming apparatus equipped with a thermal spraying mechanism and a friction stirrer mechanism.

In FIG. 11, the base material 1 is placed on a table 19 which is movable in the direction of the arrow shown. Further, the spray gun 1 is mounted via a vertical movement mechanism 11a attached to the rear end of the base 18 in the base material moving direction of the gantry 18 arranged directly above the base material 1.
6 is supported, and the motor 10 is supported via a vertical movement mechanism 11b attached to the front end of the base 18 in the direction of movement of the base material. The rotary tool 3 is attached to the rotary shaft of the motor 10.

In the surface reforming device having such a structure,
The coating layer 2 is formed on the surface of the base material by the thermal spray gun 16 supported by the vertical movement mechanism 11a so as to be vertically movable. The coating layer 2 is heated by the thermal spray frame 17 at a high temperature and is supported by the vertical mechanism 11b. A rotary tool 3 driven to rotate by 10 is inserted into the coating layer 2 and the base material 1 to perform surface modification.

Therefore, the forming process of the coating layer 2 and the friction stir processing of the coating layer 2 can be carried out at the same time, and the coating film heated at high temperature by the thermal spraying frame 17 is transferred to the friction stirring process as it is. No heating device is required, and it can be realized as a device suitable for equipment for continuously processing a particularly long flat plate.

As described above, it is possible to use basically the same drive mechanism for the workpiece by thermal spraying and the drive mechanism for the workpiece in the friction stir processing. It is possible to construct a highly reliable device and reduce the cost of the device itself. Further, by performing the friction stirring immediately after the thermal spraying, it is possible to reduce the load on the rotary tool in the friction stirring by utilizing the heat at the time of thermal spraying and to improve the productivity.

FIG. 12 is a flow chart showing an implementation process for explaining a method of manufacturing a structural component by applying the surface modification method according to the present invention.

In FIG. 12, first, in (1), a preliminary groove 21 is formed on the upper circumference of the cylindrical work piece 20.
After that, in (2), the spray gun 16 is arranged so as to face the spare groove 21 in a direction orthogonal to the spare groove 21, and the workpiece 20 is rotated around its central axis to the peripheral portion including the spare groove 21 by the spray method. The surface coating layer 2 is formed.

The thermal spray gun 16 does not necessarily have to be arranged in a direction orthogonal to the preliminary groove 21, but can be tilted at about 45 ° and can be constructed separately in two steps up and down, and can be changed according to requirements. Is.

Next, in (3), the rotary tool 3 is inserted from the surface of the coating layer corresponding to the preliminary groove, and the surface coating layer and the base material are frictionally stirred to form an alloyed layer in the preliminary groove portion.

Finally, by forming a groove in the alloyed layer in (4), a groove having excellent wear resistance can be formed.

As described above, in the method of manufacturing a structural part to which the surface modification method according to the present invention is applied, a groove is machined on the outer periphery of a cylindrical work piece, and the groove is coated and filled with a hard material by a thermal spraying method. After that, the workpiece is rotated while the rotary tool 3 is inserted into the groove to form a wear resistant layer around the groove.

Conventionally, in a groove portion such as a piston ring groove portion of an automobile piston, good adhesion cannot be obtained even if thermal spray coating is performed from the surface, which has been a major obstacle to application of the thermal spray method.

However, when the friction stir processing as described above is performed using the surface modification method of the present invention, an excellent film can be formed even in the concave portion. For example, in the case of automobile pistons, A significant improvement in engine life and vehicle fuel economy is achieved.

The groove to be formed first may have a width or depth larger or smaller than the groove finally required, but the base material and the coating layer are agitated after processing to a smaller size. After that, it is preferable that the modified layer is machined to a predetermined size because the modified layer has high adhesion.

Although the cylindrical work piece has been described above, the wear stirring process can be performed on the inner circumferential groove portion formed on the cylindrical work piece in the same manner as described above.

[0089]

As described above, according to the present invention, it is possible to form a surface-modified layer having excellent mechanical properties, corrosion resistance, abrasion resistance, electrical properties, etc. It is possible to provide a surface modification method and apparatus that can be improved in each step as compared with the characteristics of a film formed by a film method.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment for explaining a surface modification method according to the present invention.

FIG. 2 is a graph showing the relationship between the adhesion strength between the coating layer and the base material and the porosity.

FIG. 3 is a graph showing the results of observing and quantifying defects inside the formed surface layer with an optical microscope after forming a coating layer using several types of thermal spraying methods with different sprayed particle velocities and then performing frictional stirring.

FIG. 4 is a configuration diagram showing an example of an apparatus for modifying a coating layer on the surface of a base material in a vacuum.

FIG. 5 is a graph showing a comparison result of the amount of impurities remaining inside the film by a normal method, a method using a shield gas, and an application in vacuum.

FIG. 6 is a schematic diagram showing a second embodiment for explaining the surface modification method according to the present invention.

FIG. 7 is a schematic diagram showing a third embodiment for explaining the surface modification method according to the present invention.

FIG. 8 is a graph showing a comparison of hardness of a surface layer formed by spraying oxygen or nitrogen around the friction stirrer part and a surface layer formed by normal construction without spraying.

FIG. 9 is a graph showing the relationship between film thickness and hardness.

FIG. 10 is a graph showing the relationship between the thickness ratio of the two-layer film thickness before the stirring treatment and the Vickers hardness of the coating after the stirring treatment.

FIG. 11 is a configuration diagram showing an embodiment of a surface modification device according to the present invention.

FIG. 12 is a flowchart showing an implementation process for explaining a method for manufacturing a structural component by applying the surface modification method according to the present invention.

[Explanation of symbols]

1 ... Base material 2 ... Clothes layer 3 ... Tool 4 ... Surface modification layer 5 ... Infrared lamp 6 ... Nozzle 7 ... Shield gas 8 ... Argon gas cylinder 9 ... Oxygen gas cylinder 10 ... Motor 11, 11a, 11b ... Vertical drive mechanism 12 ... Rollaway bed 13 ... Vacuum container 14 ... Workpiece 15 ... Vacuum pump 16 ... Thermal spray gun 17 ... Thermal spray frame 18 ... Device stand 20 ... Cylindrical work piece 21 ... Spare groove

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masayuki Ishikawa             2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa               Toshiba Keihin Office (72) Inventor Toshiaki Fuse             2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa               Toshiba Keihin Office F-term (reference) 4E067 AA05 AA06 AA07 BG00 DA00                       DA17 DB01 DB03 DB05 DC04                       DC07 EA00                 4K031 AA02 AB03 AB04 AB05 AB07                       AB08 AB09 DA01 EA03 FA03                       FA10 FA11                 4K044 AA01 BA01 BB02 BC01 BC02                       BC14 CA11 CA62 CA64 CA67                       CA71

Claims (13)

[Claims] 1. A coating layer is formed on the surface of a base material of a workpiece, and then a tool for circulating movement is inserted from the surface side of the workpiece, and the tool and the workpiece are relatively moved in this state. By doing so, the coating layer or the base material and the coating layer are frictionally stirred to modify the surface of the base material. 2. The method for modifying the surface of a work piece according to claim 1, wherein the adhesion strength between the coating layer and the base material before friction stir processing is 10 MPa or more. Surface modification method. 3. The method for modifying the surface of a work piece according to claim 1, wherein the coating layer is formed by a thermal spraying method. 4. The method for modifying the surface of a work piece according to claim 3, wherein the velocity of the spray particles in the thermal spraying method is 500 m / s or more. 5. The method for surface modification of a work piece according to claim 1, wherein the base material on which the coating layer is formed is formed by any one of a heating element, a combustion gas flame, a plasma flame, an infrared lamp heating, and a high frequency heating. A method for modifying the surface of a workpiece, wherein friction stirring is performed while heating. 6. The method for modifying a surface of a work piece according to claim 1, wherein the periphery of a region where the tool is in contact with the work piece or the entire apparatus is friction agitated while being shielded by an inert gas. A method for modifying the surface of a workpiece, comprising: 7. The method for modifying the surface of a work piece according to claim 1, wherein the work piece, the tool, or the entire apparatus is placed in a vacuum container and the base material surface is modified under a reduced pressure atmosphere. A method for modifying the surface of a workpiece, comprising: 8. The method for modifying a surface of a work piece according to claim 1, wherein oxygen or nitrogen or at least one of the periphery of a region where the tool is in contact with the work piece or the entire apparatus is used. A method for modifying the surface of a workpiece, which comprises modifying the surface of a base material while spraying a mixed gas containing titanium. 9. The method for surface modification of a work piece according to claim 1, wherein the friction stirring is performed in a state where the ratio of the thickness of the coating layer formed before the friction stirring and the insertion depth of the tool is changed. A method for modifying the surface of a workpiece, which comprises forming a surface modification layer having a different composition depending on the site. 10. The method for modifying the surface of a work piece according to claim 1, wherein the coating layer is composed of two or more layers having different layer thickness ratios before friction stirring, and the coating layer is friction stirred. By doing so, a surface modification layer having a composition / characteristic that differs depending on the site is formed. 11. A base metal or thermal spray treatment mechanism and a surface modification treatment mechanism comprising a thermal spray treatment mechanism for forming a coating layer on the surface of the base metal by a thermal spraying method and a surface modification treatment mechanism by a friction stir method. A surface reforming method for a workpiece, wherein a coating layer is formed on the surface of the base material by the thermal spraying treatment mechanism while moving the workpiece, and at the same time surface modification is performed on the workpiece by the surface reforming treatment mechanism. . 12. A thermal spraying treatment mechanism which is movably supported in a vertical direction with respect to a base material and forms a coating layer on the surface of the base material by a thermal spraying method, and integrally and at a position adjacent to the thermal spraying treatment mechanism. A surface modification treatment mechanism which is movably supported in the vertical direction with respect to the base material, and which performs a surface modification by a friction stir method on the workpiece on which the coating layer is formed by the thermal spraying treatment mechanism; A surface reforming apparatus for a workpiece, comprising: a moving unit that relatively moves these two mechanisms. 13. A rotary tool is formed by machining a groove on the outer circumference or the inner circumference of a cylindrical work piece, or on the outer circumference or inner circumference of a cylindrical work piece, and coating and filling the groove section with a hard material by a thermal spraying method. A method of processing a structural part, characterized in that the workpiece is rotated while being inserted into the groove to form an abrasion resistant layer around the outer peripheral or inner peripheral groove.