JP3896598B2 - Anodizing method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to the anodized how to form an anodic oxidation workpiece member of an aluminum-based.
[0002]
[Prior art]
As an alumite treatment method, conventionally, a treated member formed of an aluminum-based alloy having a treated surface and a container containing an alumite treatment liquid are used, and the treated member is immersed in the anodized treatment liquid. Thus, the member to be treated is an anode, a cathode for the anode is further provided, and an anodic oxide film is formed on the surface to be treated of the member to be treated by energization between the anode and the cathode. Further, as this alumite treatment method, high-speed alumite treatment is known in which current density is increased and high-speed treatment is performed.
[0003]
It is known that an anodized film formed by such an alumite treatment is hard and has excellent wear resistance. This anodized anodic oxide film has Al ₂ O ₃ as the main component and is said to have a porous pore layer (Revised 4th Edition Metal Handbook, The Japan Institute of Metals, December 20, 1982) ; Page 1313).
[0004]
[Problems to be solved by the invention]
By the way, when alumite treatment is performed, particularly when high-speed alumite treatment is performed, the anodic oxide film may become non-uniform and the surface roughness may deteriorate. In particular, it is generally considered that when the aluminum base material constituting the member to be processed contains Si particles, the anodic oxide film is likely to be non-uniform and the surface roughness is likely to be deteriorated. It is presumed that Si particles induce current density non-uniformity.
[0005]
In order to reduce the surface roughness of the anodized film, the present applicant has recently developed a method for improving the surface roughness by polishing the anodized film formed on the member to be processed with a grindstone. According to this method, the surface roughness of the anodized film can be reduced as compared with that before polishing.
However, in order to improve the surface roughness sufficiently, it is necessary to carry out finish polishing. Furthermore, since an expensive grinding wheel is used, the cost tends to be high. Moreover, since the clogging of the grindstone frequently occurs, the grindstone must be frequently replaced. Further, in the case of polishing with a grindstone, there is a limit to the increase in the processing speed with the grindstone, and the processing tends to be slow. Therefore, according to the method of polishing the anodized film with a grindstone, the price and productivity are not always sufficient.
[0006]
The present invention has been made in view of the above-described circumstances, and the problem of claims 1 and 2 is, of course, normal even when a high-speed alumite treatment is performed and the member to be treated contains Si. It is an object to provide an alumite treatment method that is advantageous for homogenization of an anodized film and uniformity of surface roughness even when the alumite treatment is performed and when the member to be treated does not contain Si. .
[0008]
[Means for Solving the Problems]
The present inventor has intensively developed an alumite treatment for forming an anodized film on a surface to be processed of an aluminum-based processed member, and is locally applied to the anodized film on the processed surface after or during the formation of the anodized film. It has been found that if a local compression process is applied by a strong compression body of a mechanical compression process means, the anodic oxide film can be made uniform and the surface roughness can be made uniform. It has been completed.
[0009]
The anodizing method of claim 1 is:
Using an aluminum-based processed member having a surface to be processed, a container for containing an alumite processing liquid, and a local compression processing means having a strong pressure member that applies local compression processing to the surface to be processed of the processed member,
In a state where the surface to be processed and the alumite treatment liquid are brought into contact with each other and the local compression processing means is set to the cathode, the member to be processed is energized to form an anodic oxide film on the surface to be processed. Implement the anodizing process to form,
During the formation of the anodic oxide film, local compression processing is applied to the anodic oxide film on the surface to be processed by the strong pressure member of the local compression processing means.
[0010]
The anodizing method of claim 2 is:
Using an aluminum-based processed member having a surface to be processed, a container for containing an alumite processing liquid, and a local compression processing means having a strong pressure member that applies local compression processing to the surface to be processed of the processed member,
In a state where the surface to be processed and the alumite treatment liquid are brought into contact with each other and the local compression processing means is set to the cathode, the member to be processed is energized to form an anodic oxide film on the surface to be processed. Implement the anodizing process to form,
During the formation of the anodic oxide film, a local compression process is applied to the anodic oxide film on the surface to be processed while rotating the high pressure member of the local compression processing means, and at least the surface layer portion of the pore layer of the anodic oxide film is bent. It is characterized by this.
[0012]
[Action]
According to the methods of claims 1 and 2, the alumite treatment step is performed in which the member to be treated is energized to form the anodized film on the surface to be treated of the member to be treated. After or during the formation of the anodic oxide film, a local compression process is applied to the anodized film on the surface to be processed by the high pressure member of the local compression processing means.
[0013]
According to the method of claim 1, at least the surface layer portion of the pore layer of the anodic oxide film is bent by the compression process by the local compression process, and the pore layer is subjected to the compression process while being subjected to the compression process. A form in which the surface layer portion is not substantially bent is included.
According to the method of claim 2, since the high pressure member of the local compression processing means is rotated, at least the surface layer portion of the pore layer of the anodized film is easily bent.
[0014]
According to the present invention , it is possible to exemplify a form in which the strong pressure roller protrudes radially outward from the peripheral wall of the base body by the biasing member during the local compression processing . Butt out the coercive roller is strongly pressed to the anodic oxide film of the processed surface of the member to be processed.
[0015]
【Example】
Examples of the present invention will be described below. This embodiment is a case where a member to be processed containing Si is subjected to high speed alumite treatment.
(Configuration of Example)
(apparatus)
First, the apparatus will be described. As shown in FIG. 1, a container 2 having a storage chamber 20 for storing an alumite treatment liquid 1 is provided. Further, a tank 3 in which the alumite treatment liquid 1 is stored in the tank chamber 30 is disposed. The tank 3 is provided with a cooling device 33 for maintaining the alumite treatment liquid 1 at a low temperature (for example, 5 ° C.).
[0016]
The holding member 21 of the container 2 holds a member to be processed 4 made of an aluminum alloy die-cast material. In this embodiment, the member 4 to be processed is used as a brake master cylinder which is a hydraulic component. The member 4 to be processed is integrally extended radially outward from the cylindrical body 45 having a suitable number of holes 43 in the peripheral wall 42, a bottom wall 46 that closes the lower end opening of the cylindrical body 45, and the cylindrical body 45. And has a flange 47. The cylindrical body 45 defines the hollow chamber 41. The hole 43 functions as an oil passage when the member to be processed 4 is used. The aluminum-based alloy forming the member to be processed 4 includes, for example, Si by weight of 5.0 to 15.0%, Mg of 0.25 to 0.6%, and Cu of 0.2% or less. ing. The aluminum-based alloy may be in a form that contains primary crystal Si particles in order to function as hard particles and ensure wear resistance, or a form that does not contain primary crystal Si particles. This is because the primary crystal Si particles are crystallized based on the Si content.
[0017]
In the hollow chamber 41 of the member to be processed 4, the burnish cylinder 50 of the burnishing apparatus 5 is inserted substantially coaxially with a ring-shaped gap 49.
Further, a supply path 37 that connects the tank 3 and the burnishing apparatus 5 is provided, and a pump 38 is disposed in the supply path 37. A discharge path 39 that connects the tank 3 and the discharge port 2 i of the container 2 is provided. When the pump 38 is operated, the alumite treatment liquid 1 in the tank 3 passes through the supply passage 37 and is supplied from the nozzle 37 h of the supply passage 37 to the inside of the burnish cylinder 50 of the burnishing apparatus 5. 50 d is supplied to the gap 49, passes through the hole 43 of the member to be processed 4, reaches the storage chamber 20 of the container 2, and further returns to the tank 3 through the discharge path 39. In this way, the alumite treatment liquid 1 circulates.
[0018]
As shown in FIGS. 2 and 3, the burnishing apparatus 5 is an apparatus that performs burnishing, which is one of the local compression processes. The burnish processing apparatus 5 includes a burnish cylinder 50 that functions as a base formed of a metal (for example, stainless steel) having corrosion resistance and conductivity with respect to the alumite treatment liquid, and a hard material that is rotatably held by the burnish cylinder 50. A strong pressure roller 52 as a strong pressure member formed of (for example, JIS SK material, SKD material, ceramic material, etc.) and the strong pressure roller 52 are protruded radially outward, that is, in the X1 direction from the opening 51 of the peripheral wall of the burnish cylinder 50. And an urging member 53. The burnish cylinder 50 is rotatable around its axis and movable in the vertical direction by a drive source (not shown).
[0019]
A part of the strong pressure roller 52 protrudes from the opening 51 of the burnish cylinder 50. The strong pressure roller 52 has a conical tapered surface 52c, and the biasing member 53 has a conical tapered surface 53c having a taper angle corresponding to the tapered surface 52c. When the urging member 53 moves in the axial length direction, that is, in the direction of the arrow Y1, the tapered surface 53c of the urging member 53 presses the tapered surface 52c of the strong pressure roller 52, thereby causing the strong pressure roller 52 to move outward in the radial direction, that is, in the arrow X1 direction. Project a predetermined amount.
[0020]
As shown in FIG. 1, a rectifier 6 that functions as a power feeding device is provided. The member 4 to be processed is electrically connected to the anode terminal 60 of the rectifier 6 through a power supply line 61. Therefore, the member to be treated 4 functions as an anode during the alumite treatment. The burnish cylinder 50 of the burnishing apparatus 5 is electrically connected to the cathode terminal 64 of the rectifier 6 via a feeder line 65. Accordingly, the varnish cylinder 50 functions as a cathode during anodizing.
[0021]
(Method)
Next, a method according to the present embodiment will be described. As shown in FIG. 1, the member 4 to be processed is held in the holding portion 21 of the container 2, and the member 4 to be processed is immersed in the alumite treatment liquid 1 in the container 2. Thereby, the cylindrical body 45 of the to-be-processed member 4 and the alumite processing liquid 1 are made to contact. In this state, the burnish cylinder 50 of the burnishing apparatus 5 and the inner peripheral surface of the cylinder 45 of the member to be processed 4 face each other with the alumite treatment liquid.
[0022]
Further, in this state, the strong pressure roller 52 is retracted and the protruding amount of the strong pressure roller 52 is suppressed, and the strong pressure roller 52 and the cylindrical body 45 of the processing target member 4 are maintained in a non-contact state.
In this state, an alumite treatment is performed for a predetermined time by energizing between the cathode and the anode. As a result, an anodic oxide film is formed on the inner peripheral surface, which is the surface to be processed, of the cylindrical body 45 of the member 4 to be processed. In this case, the burnish cylinder 50 of the burnishing apparatus 5 that functions as a cathode is appropriately moved in the directions of arrows Y1 and Y2.
[0023]
In this embodiment, the current density applied to the cathode and the anode is increased to perform high speed anodization. Then, when the inner diameter of the cylindrical body 45 of the member to be processed 4 on which the anodized film is formed reaches a predetermined dimension, the alumite treatment is stopped.
The conditions for the alumite treatment in this example are as follows. That is, the current density is 50 to 300 A / dm ² , the time is 5 to 30 seconds, the alumite treatment liquid 1 is a sulfuric acid solution (about 10 to 30 vol%), and the treatment temperature of the alumite treatment liquid 1 is −10 ~ + 22 ° C.
[0024]
As a result of the alumite treatment, an anodic oxide film (film thickness 1 to 15 μm, hardness Hv 300 or less, surface roughness Rz 3.0 μm or less) is formed on the inner peripheral surface of the cylindrical body 45 of the member 4 to be processed.
Next, the strong pressure roller 52 is expanded radially outward, that is, in the direction of the arrow X1, while the varnish cylinder 50 of the burnishing apparatus 5 is rotated in one direction in the direction of the arrow C1, thereby locally compressing the anodic oxide film. Local compression processing, among the strong pressure roller 52 shown in FIG. 2, the outer diameter is achieved with a large large-diameter end portion 52f. Generally, the expansion amount of the strong pressure roller 52 is 10 to 50 μm, and the film compression rate is 5 to 15%. The film compressibility means [(thickness before processing−thickness after processing) / (thickness before processing)] × 100%.
[0025]
Thereby, the varnish processing which is an example of local compression processing is given to the anodic oxide film of the member 4 to be processed. At the time of such burnishing, the vanish cylinder 50 having the strong pressure roller 52 is appropriately moved along the axial length direction, that is, along the directions of the arrows Y1 and Y2. Thereby, the unevenness of the burnishing in the axial length direction of the burnish cylinder 50 is reduced or avoided. The burnishing is performed for a predetermined time. When the inner diameter of the cylindrical body 45 of the member 4 to be processed having the anodized film reaches a predetermined dimension, the burnishing process is stopped .
According to the present embodiment carried out such processes this anodic oxide film of the inner peripheral surface of the cylindrical body 45 of the member to be processed 4 is uniform, the surface roughness is small and Rz1.6～0.5Myuemu, surface roughness The degree was also good. Furthermore, the hardness of the anodic oxide film that has been burnished has also increased, and the wear resistance has been improved, making it more suitable as a sliding material.
[0026]
According to the present embodiment, the surface layer side of the pore layer of the anodic oxide film is crushed by the rolling strong pressure roller 52. Therefore, when the surface roughness of the anodic oxide film is measured with a surface roughness meter, the surface roughness is measured. The peaks and valleys of the roughness line indicating the roughness can be easily flattened, and can contribute to the improvement of the surface roughness.
As described above, according to this example, the surface roughness of the anodic oxide film can be reduced and the surface roughness can be improved by the burnishing process. Processing can be executed.
[0027]
In addition, according to the present embodiment, the surface of the anodic oxide film is compared with the grindstone method because the anodic oxide film is crushed by the rolling high pressure roller 52 as compared with the grindstone grinding method. The roughness is also good, and there are no problems caused by the grindstone such as clogging of the grindstone and wear of the grindstone. Accordingly, it is possible to solve the problem that has occurred in the grinding wheel polishing method in which the grinding wheel must be frequently replaced.
[0028]
When the anodic oxide film subjected to the vanishing process was observed with an electron microscope (SEM), the surface layer side of the pore layer of the anodic oxide film was bent. This photograph is shown in FIG. In the lower part of the photograph in FIG. 4, the reference dimensions of 50000 times and 100 nm are written as magnifications. According to this photograph, it can be seen that the pore layer of the anodic oxide film is bent in the direction perpendicular to the axis with respect to the pore core of the pore of the pore layer.
[0029]
Furthermore, when the high-speed alumite treatment is performed during the formation of the anodic oxide film as in this embodiment, the current density is high, and therefore the temperature of the member to be treated 4 tends to be high due to Joule heat. In this case, problems such as “burn” occur. In this respect, in the present embodiment, the burnishing device 5 in which the strong pressure roller 52 is retracted is used, and the alumite treatment is performed while rotating the burnish cylinder 50 of the burnishing device 5, so that centrifugal force also acts on the alumite treatment liquid. In particular, a centrifugal force also acts on the anodized treatment liquid in the gap 49. Therefore, the anodized treatment liquid flows not only by the driving force of the pump 38 but also by the centrifugal force, which is advantageous in increasing the flow rate of the anodized treatment liquid. Therefore, the circulation property of the alumite treatment liquid is improved, which is advantageous for reducing the increase in the temperature of the member 4 to be treated, and for reducing or avoiding “burning”.
[0030]
Further, since the strong pressure roller 52 can be expected to function as an agitating blade during anodizing, the anodizing treatment liquid accommodated in the member to be treated 4 can be agitated to avoid local accumulation of the anodizing treatment liquid. In this sense, the circulation property of the alumite treatment liquid is improved, which is advantageous in reducing or avoiding “burning”.
[0031]
According to this embodiment, the burnish cylinder 50 of the burnishing apparatus 5 not only holds the strong pressure roller 52 but also functions as a cathode during anodizing. Immediate Chi, the bar burnishing device 5 can be achieved both anodized and burnishing process. Therefore, according to the present embodiment, when the member 4 to be processed is held integrally with the holding portion 21 of the container 2, both the alumite treatment and the burnishing can be achieved without removing the member 4 to be processed, and the workability is also good.
[0032]
Further, according to the present embodiment, the high pressure roller 52 performs processing while pressing the inner peripheral surface of the cylindrical body 45 of the member 4 to be processed, which is a method of processing by repeating local compression. Therefore, the processing force can be reduced as compared with a mode in which the entire anodic oxide film is processed at one time, which is advantageous in avoiding cracking of the anodic oxide film. Moreover, it is advantageous for downsizing the burnishing apparatus 5.
[0033]
Furthermore, according to the present embodiment, the surface layer side of the pore layer of the anodized film can be bent as described above, so that not only the surface roughness is improved but also the varnishing is expected to be used as the pore layer sealing treatment. it can. Therefore, when the member to be treated 4 is used, it is possible to reduce or avoid the intrusion that may cause corrosion from entering the pores of the pore layer, thereby contributing to the improvement of the corrosion resistance of the anodic oxide film.
[0034]
Further, according to this embodiment, when another substance such as a colored substance is attached to the pores of the pore layer, it can be expected that the anodized film is subjected to a sealing process by applying a burnishing process. In addition, when a colored substance is attached to the pores of the pore layer, it is advantageous for reducing or avoiding the detachment of the colored substance attached to the pores of the pore layer due to the sealing action accompanying the burnishing. In terms of meaning, it can contribute to prevention of fading in the anodic oxide film.
[0035]
In addition, according to the present embodiment, the burnishing is performed on the anodized film of the member to be treated 4 in the alumite treatment liquid, which is a liquid, so that the frictional heat during the burnishing is reduced and the lubricity is ensured. It is advantageous, and therefore advantageous for good vanishing .
According to the embodiment noted above, the anodic oxide film is formed on the member to be processed 4 at A Rumaito process, then subjected to burnishing processing was discontinued anodized, further followed discontinued again anodized to burnishing processing in in you laminating an anodic oxide film on the member to be processed 4. Alternatively, a anodic oxide film may be formed on the member 4 to be processed by anodizing, and the anodized film being formed may be burnished.
[0036]
In the above example, the anodic oxide film immersed in the alumite treatment solution is burnished. However, the present invention is not limited to this, and the member to be treated 4 is taken out from the container 2 into the outside air during the burnishing. Among them, the anodic oxide film may be burnished.
According to the above-described embodiment, the high-speed alumite process is performed. However, the present invention is not limited to this, and a normal alumite process may be used. Furthermore, although the sulfuric acid solution is used as the alumite treatment liquid, the present invention is not limited to this, and a known alumite treatment liquid such as an oxalic acid solution or a chromic acid solution may be adopted.
[0037]
In the above-described example, the anodized film is formed on the inner peripheral surface of the cylindrical body 45 of the member 4 to be processed. However, the anodized film is formed on the outer peripheral surface of the cylindrical body 45 and the anodized film formed on the outer peripheral surface. The film may be strongly pressed by the strong pressure roller 52. In this case, the diameter of the burnish cylinder 50 of the burnishing apparatus 5 is larger than the diameter of the cylinder 45 of the member to be processed 4, and the outer peripheral surface of the cylinder 45 of the object to be processed 4 is the burnish cylinder of the burnishing apparatus 5. Surround with 50. Furthermore, an anodized film may be formed on both the inner peripheral surface and the outer peripheral surface of the cylindrical body 45 of the member 4 to be processed.
[0038]
Furthermore, although the substantially cylindrical strong pressure roller 52 having a taper is used as the strong pressure body, the present invention is not limited to this, and a spherical strong pressure body may be used.
5 and 6 show a modification of the burnishing apparatus. The varnish processing apparatus 80 shown in FIG. 5 includes a varnish cylinder 81, a strong pressure roller 82 held by the varnish cylinder 81, a rotary body 83 provided in the burnish cylinder 81, and a rotary body 83. And a hammer 84. As the rotating body 83 rotates, the hammer 84 strikes the strong pressure roller 82 to project outward in the radial direction of the burnish cylinder 81, so that the anodic oxide film on the inner peripheral surface of the cylindrical body 45 of the member 4 is locally Repeated compression process.
[0039]
According to the example in FIG. 6, an anodized film is formed on the inner peripheral surface of the cylindrical body 45 of the member to be processed 4, and the outer diameter is a minute amount larger than the inner diameter of the cylindrical body 45 of the member to be processed 4. A sphere 88 made of a hard material having the above is used. Since the spherical body 88 is forcibly press-fitted into the cylindrical body 45 of the member 4 to be processed, the anodized film on the inner peripheral surface of the cylindrical body 45 of the member 4 to be processed is subjected to compression processing.
[0040]
In each of the above examples, a varnish processing device that performs varnish processing as a local compression processing means is adopted, but is not limited thereto, and in some cases, a rotary forging device that forges while rotating a strong pressure body, A rotary swaging apparatus can also be employed.
In the above example, the basic shape of the member to be processed 4 is a cylindrical shape, but is not limited to this, and may be a flat plate shape, a disk shape, or a lump shape.
[0041]
In addition, the present invention is not limited to the embodiments described above and shown in the drawings, and can be appropriately selected as necessary within the scope not departing from the gist.
(Appendix)
The following technical idea can also be grasped from the embodiment described above.
The method according to claim 1, wherein the local compression processing is performed in a liquid such as an alumite treatment liquid.
The method according to claim 1, wherein the member to be treated contains primary crystal Si particles.
○ The local compression processing means has a base made of a conductive material immersed in an alumite treatment solution, the base faces the surface to be treated of the member to be treated, and functions as a cathode during the alumite treatment. The apparatus according to claim 3.
A member made of an aluminum alloy that includes an anodic oxide film and in which the pore layer of the anodic oxide film is bent in a direction perpendicular to the axis with respect to the pore core of the pore of the pore layer.
-A member made of an aluminum alloy having an anodized film having a pore layer whose surface layer portion is locally compressed at least.
-An aluminum-based processed member having a sliding surface, a container for containing an alumite treatment liquid, and a local compression processing means having a strong pressure member that applies local compression processing to the sliding surface of the processed member. Using the alumite treatment step of forming an anodic oxide film on the sliding surface of the member to be processed by energizing the member to be processed while the sliding surface of the member to be processed and the alumite treatment liquid are in contact with each other A method for producing a sliding member, wherein a local compression process is applied to the anodic oxide film on the sliding surface by a strong pressure member of a local compression process means after or during the formation of the anodized film.
[0042]
【The invention's effect】
According to the methods of claims 1 and 2, even when a high-speed alumite treatment is performed, even when a member to be treated contains Si, of course, even when a normal alumite treatment is performed, Even when the processing member does not contain Si, the anodic oxide film becomes uniform, the surface roughness of the anodic oxide film becomes small, and the surface roughness becomes a good value.
[0043]
According to the method of claims 1 and 2, the high pressure roller body is processed while pressing the surface to be processed of the member to be processed, so to speak, it is a method of processing by repeating local compression. Therefore, the processing force can be reduced as compared with the case of processing the whole of the anodic oxide film at one time, which is advantageous for avoiding cracking of the anodic oxide film, and also for reducing the size of the local compression processing means.
[0044]
According to the method of claim 2, since the local compression processing is performed while rotating the high pressure body of the local compression processing means, it is advantageous for bending the surface layer side of the pore layer of the anodized film, A function as a process can also be expected. Therefore, when another substance is adhered to the pore layer, it is advantageous to reduce or avoid the substance from falling off the pores of the pore layer.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically showing an apparatus used in an embodiment.
FIG. 2 is a longitudinal sectional view of a main part of the burnishing device.
FIG. 3 is a cross-sectional view of a main part of the burnishing device.
FIG. 4 is a photomicrograph showing the metal structure in the pore layer of the anodized film.
FIG. 5 is a cross-sectional view schematically showing a state in which a member to be processed is burnished by a burnishing apparatus according to another example.
FIG. 6 is a longitudinal sectional view schematically showing a state in which a member to be processed is burnished by a burnishing apparatus according to another example.
[Explanation of symbols]
In the figure, 1 is an alumite treatment liquid, 2 is a container, 38 is a pump, 4 is a member to be treated, 45 is a cylindrical body, 5 is a varnish processing device (local compression processing means), 52 is a high pressure roller (high pressure body), Reference numeral 53 denotes an urging member.

Claims (2)

Using an aluminum-based processed member having a surface to be processed, a container for containing an alumite processing liquid, and a local compression processing means having a strong pressure member that applies local compression processing to the surface to be processed of the processed member,
In a state where the surface to be processed of the member to be processed and the alumite treatment liquid are in contact with each other and the local compression processing means is set to the cathode, the surface to be processed is energized to the member to be processed. An anodizing process to form an anodic oxide film on the
An alumite treatment method comprising applying a local compression process to the anodized film on the surface to be processed by a strong pressure member of the local compression process means during the formation of the anodized film. Using an aluminum-based processed member having a surface to be processed, a container for containing an alumite processing liquid, and a local compression processing means having a strong pressure member that applies local compression processing to the surface to be processed of the processed member,
In a state where the surface to be processed of the member to be processed and the alumite treatment liquid are in contact with each other and the local compression processing means is set to the cathode, the surface to be processed is energized to the member to be processed. An anodizing process to form an anodic oxide film on the
During the formation of the anodized film, a local compression process is applied to the anodized film on the surface to be processed while rotating the high pressure member of the local compressing means, and at least the surface layer portion of the pore layer of the anodized film An alumite treatment method characterized by forming a curve.

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