WO2022131514A1 - Method for anodizing aluminum - Google Patents

Abstract

One aspect of the present invention provides a method for anodizing aluminum, in which the occurrence of defects, such as burning or discoloration, can be prevented by firmly fastening an aluminum substrate to a rack. The method for anodizing aluminum according to an embodiment of the present invention comprises: processing a plurality of threaded holes in the surface of an aluminum substrate; fastening nuts and bolts to the plurality of holes; connecting an anodizing rack to the bolts; and anodizing the aluminum substrate connected to the rack by means of the bolts.

Description

How to anodize aluminum

The disclosed invention relates to a method of anodizing aluminum.

Anodizing treatment, also called anodizing method, is one of the surface treatment methods for light metals such as aluminum and magnesium which are widely used in industry.

In the case of aluminum alloys used in an atmospheric environment, most of them are anodized and then sealed to suppress corrosion. Applications of anodized aluminum alloy include building materials such as aluminum sashes, semiconductor equipment bodies and parts, automobile parts/body, aircraft bodies, machine parts, and kitchenware. Leisure goods, cell phone cases and electronic equipment cases, etc. are very diverse.

On the other hand, in the anodizing treatment, electricity must be applied, and it is common to apply electricity by bringing an aluminum substrate into contact with an anodizing rack. However, when the jig is not firmly in contact with the aluminum substrate, the aluminum substrate may fall off from the jig during the process, or the aluminum substrate may have poor burning or discoloration.

In order to solve the above problems, the present invention is to provide an aluminum anodizing method capable of preventing the occurrence of defects such as burning or color deviation by firmly fastening an aluminum substrate with a jig.

Aluminum anodizing method according to an embodiment of the present invention, processing a plurality of grooves in which a thread is formed on the surface of an aluminum substrate; fastening nuts and bolts to the plurality of grooves; connecting an anodizing fixture to the bolt; and performing anodizing on the aluminum substrate connected to the jig through the bolt.

In addition, the method may further include; determining the number and radius of the bolts and nuts so that the limit energization amount of the bolts and nuts is greater than the required amount of current applied during anodizing.

In addition, the bolt and the nut may be made of an aluminum alloy.

Also, the nut may have a circular cross-section.

In addition, performing the anodizing may include performing anodizing such that the applied current density per surface area of the nut in contact with the aluminum substrate is 1A/mm ² when the surface area of the aluminum substrate is 1 m ² or more. .

In addition, performing the anodizing, when the surface area of the aluminum substrate is less than 1 m ² Anodizing is performed so that the current density applied per surface area of the nut in contact with the aluminum substrate is 1.5A/mm ² It may include performing have.

In addition, the fastening of the nut and the bolt to the plurality of grooves may include fastening a bolt provided in a head having a threaded groove to the plurality of grooves.

In addition, connecting the anodizing jig to the bolt may include connecting the anodizing jig to the bolt by fastening the fastening bolt to the groove of the bolt.

In addition, the fastening bolt may be made of a titanium alloy.

In addition, the machining of the plurality of grooves in which the threads are formed on the surface of the aluminum substrate may include processing an even number of grooves to form a symmetry on the surface of the aluminum substrate.

In addition, the machining of the plurality of grooves in which the threads are formed on the surface of the aluminum substrate may include processing the plurality of grooves at positions spaced apart by 100 mm from the edge of the aluminum substrate.

In addition, the machining of the plurality of grooves in which the threads are formed on the surface of the aluminum substrate may include processing the plurality of grooves having a diameter of 2.0 to 3.0 mm on the surface of the aluminum substrate.

According to one embodiment of the present invention, it is possible to provide an aluminum anodizing method capable of preventing the occurrence of defects such as burning or color deviation by firmly fastening the aluminum substrate to the jig.

According to an example of the present invention, it is possible to provide an aluminum anodizing method capable of preventing the occurrence of defects such as burning or color deviation by firmly fastening an aluminum substrate to a jig.

1 is a flowchart illustrating an aluminum anodizing method according to an embodiment of the present invention.

2 is a view showing a longitudinal cross-section of a bolt and a nut according to an embodiment of the present invention.

3 is a perspective view of a bolt and a nut according to an embodiment of the present invention.

4 is a perspective view illustrating a groove, a bolt, and a nut of an aluminum substrate according to an embodiment of the present invention.

5 is a view illustrating a longitudinal cross-section in a state in which a bolt and a nut are fastened to an aluminum substrate according to an embodiment of the present invention.

6 is a perspective view illustrating a state in which a bolt and a nut are fastened to an aluminum substrate according to an embodiment of the present invention.

7 is a perspective view showing a part of the state in which the aluminum substrate and the jig are fastened according to an embodiment of the present invention.

8 is a perspective view illustrating a state in which an aluminum substrate and a jig are fastened according to an embodiment of the present invention.

Aluminum anodizing method according to an embodiment of the present invention, processing a plurality of grooves in which a thread is formed on the surface of an aluminum substrate; fastening nuts and bolts to the plurality of grooves; connecting an anodizing fixture to the bolt; and performing anodizing on the aluminum substrate connected to the jig through the bolt.

Like reference numerals refer to like elements throughout. This specification does not describe all elements of the embodiments, and general content in the technical field to which the present invention pertains or content that overlaps between the embodiments is omitted. The term 'part, module, member, block' used in this specification may be implemented in software or hardware, and according to embodiments, a plurality of 'part, module, member, block' may be implemented as one component, It is also possible for one 'part, module, member, block' to include a plurality of components.

Throughout the specification, when a part is "connected" to another part, it includes not only a direct connection but also an indirect connection, and the indirect connection includes connection through a wireless communication network. do.

Also, when a part "includes" a component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

Throughout the specification, when a member is said to be located "on" another member, this includes not only a case in which a member is in contact with another member but also a case in which another member exists between the two members.

Terms such as first, second, etc. are used to distinguish one component from another, and the component is not limited by the above-mentioned terms.

The singular expression includes the plural expression unless the context clearly dictates otherwise.

In each step, the identification code is used for convenience of description, and the identification code does not describe the order of each step, and each step may be performed differently from the specified order unless a specific order is clearly stated in the context. have.

Hereinafter, the working principle and embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a flowchart illustrating an aluminum anodizing method according to an embodiment of the present invention.

In the anodizing method, a uniform and thick oxide film is formed on the metal surface by immersing a metal such as aluminum in a liquid electrolyte and then applying an electric current using the metal as the anode and the auxiliary electrode as the cathode. It is an electrochemical process.

The anode means an electrode where oxidation reaction takes place, and is an electrode opposite to the cathode where the reduction reaction takes place. Oxidation refers to the chemical bonding of metal elements with oxygen. Therefore, electrochemically growing an oxide film using an oxidation reaction occurring on the surface with a metal as an anode in a solution is called anodic oxidation, that is, anodizing.

Most metals exist as oxides in nature. That is, in nature, the stable phase is an oxide, and the metal is not a stable phase but a metastable phase.

In order for the metastable metal to exist stably, a protective oxide film naturally formed on the metal surface is required. That is, the reason why a highly reactive metal such as aluminum can be used stably in the atmosphere is that a native oxide film is formed on the metal surface to protect the metal.

In general, the corrosion resistance of metals depends on how dense and chemically stable the natural oxide film formed on the metal surface. Anodizing is an electrochemical process that artificially grows the thickness of the surface oxide film to protect the metal when the natural oxide film is thin and does not exhibit sufficient corrosion resistance.

1, the anodizing method according to the disclosed embodiment connects the aluminum substrate 100 to the anodizing jig 130 (200 to 220), and performs anodizing on the aluminum substrate 100 connected to the jig 130 to do (230). A structure and a connection method for connecting the aluminum substrate 100 to the jig 130 will be described later, and a process of performing anodizing treatment on the aluminum substrate 100 connected to the jig 130 will be first described.

The anodizing treatment for the aluminum substrate 100 is performed by immersing the aluminum substrate 100 that has undergone the first reforming process 10 for treating the surface of the aluminum substrate 100 and the first reforming process 10 in a sulfuric acid solution and applying a voltage The aluminum substrate 100 that has undergone an anodization process 20 for forming a film by applying a second reforming process 30 for treating the surface of the aluminum film that has undergone the anodization process 20, and a second reforming process 30 It includes a sealing process 40 for performing sealing (sealing) for the hole formed in the film. The aluminum alloy manufactured according to the aluminum anodizing method according to the disclosed embodiment may be applied to various products including refrigerators.

The first reforming process 10 according to the disclosed embodiment includes degreasing, water washing, etching, water washing, primary desmut, water washing, chemical polishing, water washing, secondary desmut, and water washing processes.

The degreasing process is a process for removing organic impurities present on the surface of the aluminum substrate 100 . In the degreasing process, organic impurities are removed by immersing the aluminum substrate 100 in 5 vol% of a neutral degreasing agent having a pH of 6 to 8 for 1 minute or more.

The water washing process is a process of washing the degreasing solution by immersing the aluminum substrate 100 that has undergone the degreasing process in industrial water for 30 seconds or more, and various known water washing processes may be employed.

In the etching process, impurities such as Fe, Mg, Si are removed by immersing the aluminum substrate 100 in a 10 vol% sodium hydroxide (NaOH) aqueous solution at 50° C. for 20 seconds.

The aluminum substrate 100 that has undergone the etching process is subjected to the above-described water washing process. A description of the water washing process is omitted since it is the same as the above-described water washing process.

On the surface of the aluminum substrate 100 that has undergone the etching process, components such as Mg, Cu, Si, and Mn, which are alloy components, are different from the etching rate of the base material to form black smut. The desmut process is a process of removing such smut generated on the surface of the aluminum substrate 100 that has undergone the etching process using nitric acid.

In the first desmut process, the aforementioned smut is removed by immersing the aluminum substrate 100 in 10 vol% nitric acid at 25° C. for 30 seconds.

The aluminum substrate 100 that has undergone the first desmut process is subjected to the above-described water washing process. A description of the water washing process is omitted since it is the same as the above-described water washing process.

The chemical polishing process is a process of lowering the roughness of the surface of the aluminum substrate 100 to impart gloss to the surface of the substrate 100 . In the chemical polishing process, the aluminum substrate 100 is deposited in a mixed acid of 80 vol% phosphoric acid and 20 vol% sulfuric acid at 100° C. for 10 seconds or more.

The aluminum substrate 100 that has undergone the chemical polishing process is subjected to the above-described water washing process. A description of the water washing process is omitted since it is the same as the above-described water washing process.

After the chemical polishing process, the aluminum substrate 100 that has undergone the water washing process is subjected to a secondary desmut process to remove the smut formed on the surface after the chemical polishing process. The secondary desmut process is the same as the above-described primary desmut process.

The aluminum substrate 100 that has undergone the secondary desmut process is subjected to the above-described water washing process. A description of the water washing process is omitted since it is the same as the above-described water washing process.

The aluminum substrate 100 that has undergone the above-described first reforming process 10 is subjected to an anodization process 20 for forming a film on the surface of the aluminum substrate 100 and a coloring process for imparting a color to the substrate 100 Thereafter, a sealing process 40 of sealing the hole of the coating film of the substrate 100 is performed.

A general anodizing method implements a desired color on the substrate 100 by forming a porous aluminum oxide film on the surface of the aluminum substrate 100 through an anodizing process, and penetrating a dye into the porous film through a coloring process.

In the aluminum anodizing method according to the disclosed embodiment, an anodizing process 20 of forming an aluminum oxide film on the surface of the aluminum substrate 100 that has undergone the above-described first reforming process 10 is performed.

When an anodic voltage is applied to aluminum in the anodization process 20, aluminum ions are generated by an ionization reaction at the metal/oxide film interface and pass through the film without damage to the oxide film and move toward the surface of the film in contact with the solution.

Then, anions containing oxygen are formed by the decomposition of water on the surface of the film and move toward the inside of the film. When aluminum ions moving toward the surface of the film and anions moving inward of the film meet, aluminum oxide is formed and the film grows.

In the anodization process 20 according to the disclosed embodiment, the aluminum substrate 100 is immersed in 18 to 22 vol% sulfuric acid solution at 18 to 24° C. for 20 to 30 minutes, and a voltage of 13 to 17 V is applied to about 10 μm. A thick Al ₂ O ₃ film is formed.

The aluminum substrate 100 that has undergone the above-described anodization process is subjected to a second reforming process 30 . The second reforming process 30 includes washing with water, coloring, and washing with water.

The water washing process performed after the anodization process is performed by immersing the aluminum substrate 100 in industrial water for at least 60 seconds to clean the film solution of the anodization process remaining on the substrate 100 .

The aluminum substrate 100 that has undergone the water washing process is subjected to a coloring process that imparts a color to the substrate 100 . In the coloring process, 0.1 to 10 g/L of a dye having a weak negative charge is made into a solution of pH 5 to 6, and then deposited under 50° C. to impart a desired color to the aluminum substrate 100 .

A water washing process is performed to clean the surface of the aluminum substrate 100 that has undergone the coloring process. In the water washing process, the surface of the aluminum substrate 100 is cleaned by immersing the aluminum substrate 100 that has undergone the coloring process in industrial water for 30 seconds or more.

The aluminum anodizing method according to the disclosed embodiment performs a sealing process 40 for sealing the hole of the aluminum substrate 100 that has undergone the second reforming process 30 including the above-described water washing, coloring, and water washing processes.

In the sealing process 40, the aluminum substrate 100 is immersed in 5 vol% nickel acetate at 85 to 95° C. for 20 to 30 minutes to seal the hole in the film.

After the high-temperature sealing process (60) process, a water washing process (70) of washing the surface by immersion in industrial water for 30 seconds or more, and a drying process (80) of leaving it in an environment of 70 ° C or higher for 5 minutes or more to remove moisture can be rough

On the other hand, as described above, electricity must be applied to perform the anodizing treatment, but it is common to apply the jig by contacting the non-exterior surface, not the surface to be used as the exterior of the product later.

In general, a method of contacting a non-external surface of a product by processing a leaf spring steel having a tension of a certain level or more into a wedge shape is used. This method is applicable only when there is a structure or hole in the non-exterior surface of the product.

However, in the case of a large-area aluminum plate, since it is a smooth plate, there is no structure that can be mounted on the non-exterior surface, so it is common to fix it by pointing it on the side of the plate. However, in the case of a product whose side is also an exterior surface, there is a problem that the marks that the jig has contacted may come out on the exterior surface after anodizing.

In addition, during the anodizing process, air agitation is performed to ensure uniform quality of the product, but if the product and the jig are not in firm contact, dropout may occur during the process. There is a problem that may cause defects and the like.

As another method, there is a method of making a hole in the aluminum plate and contacting the jig, but this may also cause the same problem as the method described above.

As another method, electricity may be applied by directly welding an aluminum or stainless wire rod to the non-external surface. However, there is a problem in that productivity or economic feasibility is lowered because burning defects may occur on the exterior surface due to the welding heat during welding work, and not only the welding cost but also the cost of removing the welded wire rod after anodizing occurs.

Burning defects commonly occurring in the above-described methods may occur when the contact area between the product and the jig is insufficient. The amount of supplied current flows excessively beyond the limited current density that can be passed through the contact, and resistance heat is generated, which leads to a burning failure. In addition, if the contact area is insufficient, not only a burning defect but also a local color deviation defect may occur.

The embodiment disclosed herein provides an aluminum anodizing method capable of applying uniform electricity through a structure for effectively fastening a large-area aluminum plate having no structure to a non-exterior surface with a jig. Through this, the aluminum anodizing method according to the disclosed embodiment can prevent the occurrence of a burning defect or a color deviation defect.

Hereinafter, with reference to FIGS. 2 to 7 , a solid coupling structure between the aluminum substrate 100 and the jig 130 will be described in detail.

2 is a view showing a longitudinal cross-section of the bolt and the nut 110 according to an embodiment of the present invention. 3 is a perspective view of a bolt and a nut 110 according to an embodiment of the present invention. 4 is a perspective view illustrating a groove, a bolt, and a nut of an aluminum substrate according to an embodiment of the present invention. 5 is a view showing a longitudinal cross-section in a state in which the bolt and the nut 110 are fastened to the aluminum substrate 100 according to an embodiment of the present invention. 6 is a perspective view of a state in which the bolt and the nut 110 are fastened to the aluminum substrate 100 according to an embodiment of the present invention. 7 is a perspective view illustrating a part of the state in which the aluminum substrate 100 and the jig 130 are fastened according to an embodiment of the present invention. 8 is a perspective view illustrating a state in which the aluminum substrate 100 and the jig 130 are fastened according to an embodiment of the present invention.

In the aluminum anodizing method according to the disclosed embodiment, a plurality of grooves 101 in which threads are formed on the surface of an aluminum substrate 100 are processed (200), and a nut 110 and bolts 120 are formed in the plurality of processed grooves 101. ) and connecting the jig 130 to the aluminum substrate 100 by fastening the 210, and the fastening bolt 140 and the fastening nut 150 to the female screw 123 formed in the head portion of the bolt 120. (220). The above-described anodizing treatment is performed on the aluminum substrate 100 to which the jig 130 is connected ( 230 ).

First, for coupling of the jig 130 , a plurality of grooves 101 in which threads are formed on the surface of the aluminum substrate 100 are machined. When the aluminum substrate 100 is later applied to a product such as a refrigerator, the surface of the aluminum substrate 100 on which the plurality of grooves 101 are formed is formed on a non-external surface rather than an exterior surface shown to a user.

As the aluminum substrate 100, an aluminum alloy of 5000 series or 6000 series may be used, and the thickness of the aluminum substrate 100 is 3.0 mm or more.

The groove 101 formed on the surface of the aluminum substrate 100 is formed to have a diameter of 2.0 to 3.0 mm, and the thread may be processed to form two or more threads.

The number of grooves 101 may be set to an even number in order to stably fasten with the jig 130 , and the arrangement of the grooves 101 may also be provided to be symmetrical for stable fastening with the jig 130 . Also, the groove 101 may be formed to be spaced apart from the edge of the aluminum substrate 100 by an interval of about 100 mm.

The bolt 120 and the nut 110 fastened to the groove 101 of the above-described aluminum substrate 100 may be made of a 1000 series or 6000 series aluminum alloy. The diameter of the male screw 121 of the bolt 120 and the diameter of the female screw of the nut 110 may be manufactured to match the diameter of the aforementioned groove 101 (refer to FIG. 5 ). As shown in FIG. 3 , the nut 110 may be formed to have a circular cross-section, so that marks generated on the non-appearance surface after anodizing have no directionality.

As shown in Figure 2, the bolt 120 is formed with a male screw 121 fastened to the groove 101 of the aluminum substrate 100 on one side, and the head portion on the opposite side is used to fasten the jig 130 later. A female screw 123 into which the fastening bolt 140 is inserted is formed.

As shown in FIG. 5 , the length of the male screw 121 of the bolt 120 is such that a gap does not occur when the bolt 120 and the nut 110 are fastened to the groove 101 of the aluminum substrate 100 , the nut It may be determined to match the sum of the thickness of 110 and the depth of the groove 101 of the aluminum substrate 100 . For example, the length of the male screw 121 of the bolt 120 may be 5.0 mm, the thickness of the nut 110 is 3.0 mm, and the depth of the groove 101 formed in the aluminum substrate 100 is 2.0 mm. can be

The number of bolts 120 and nuts 110 and the radius of the nut 110 in contact with the aluminum substrate 100 are compared with the limit energization amount of the bolt 120 and the nut 110 and the amount of current actually required during anodizing treatment. can be decided.

That is, the number of bolts 120 and the nut 110 and the radius of the nut 110 may be determined so that the limit energization amount of the bolt 120 and the nut 110 is higher than the actual required current amount. Here, the actual required current may be determined as a value increased by 20% from the theoretical required current. This is considering that the actual required current is higher than the theoretical required current when considering the resistance value of the process equipment.

If the limiting current of the bolt 120 and the nut 110 is lower than the actual required current, poor burning or color deviation may occur due to resistance heat. Therefore, the limit energization amount of the bolt 120 and the nut 110 should be higher than the actual required current amount. The limit energization amount may be calculated by multiplying the total contact area between the bolt 120 and the nut 110 and the aluminum substrate 100, the appropriate current density, and the energization efficiency.

The appropriate current density that can conduct electricity per unit area in the bolt 120 and the nut 110 is set to 1.0 A/mm ² when the surface area of the aluminum substrate 100 is 1 m ² or more, and 1.5 A/mm ² when less than 1 m ² is set to This is because the smaller the area, the higher the current efficiency and the higher the current density.

The total contact area, which can be regarded as a variable in the calculation of the limiting current, is the product of the contact area between the bolt 120 and the nut 110 and the aluminum substrate 100 and the number of the bolt 120 and the nut 110 Since it is calculated as , it can be seen that the radius and number of the bolt 120 and the nut 110 that determine the contact area are factors that determine the limiting energization amount.

The relationship between the required current amount, the appropriate current density, the number of bolts 120 and nuts 110 and the surface area in the table below can be determined by the following formula (1).

(1) Surface area (㎟) =

Table 1 below shows whether defects occur according to the limiting current and required current of the bolt 120 and the nut 110 .

	Actual amount of current required	bolt/nut							Exterior
		Material	Count (EA)	radius (mm)	contact area (㎟/EA)	Appropriate current density (A/㎟)	energization efficiency (%)	limit current (A)
Comparative Example 1	739	aluminum	6	5.0	78.5	1.0	90	424	NG (burning, color deviation)
Comparative Example 2	739	aluminum	8	5.0	78.5	1.0	90	565	NG (burning, color deviation)
Example 1	739	aluminum	8	7.5	176.7	1.0	90	1272	Good

As shown in Table 1, according to Example 1, when the radius of the bolt 120 and the nut 110 is 7.5 mm and the number is 8, the limiting current is greater than the actual required current, so the appearance has poor burning or color deviation. It can be seen that no defects appear. On the other hand, it can be seen that in Comparative Examples 1 and 2, when the limiting current supply amount is smaller than the actual required current amount, there is a burning defect or a color deviation defect in the appearance. Accordingly, the number of bolts 120 and nuts 110 is preferably at least 8, and the number of corresponding grooves 101 is also preferably 8.

The bolt 120 and the nut 110 may be fastened to the groove 101 of the aluminum substrate 100 as shown in FIGS. 4 to 6 .

When the bolt 120 and the nut 110 are fastened to the groove 101 of the aluminum substrate 100, as shown in FIGS. 7 and 8, the aluminum substrate 100 to which the bolt 120 and the nut 110 are fastened. ) is fastened to the jig 130 .

A hole may be provided in the jig 130 so that the fastening bolt 140 fastened to the female screw 123 formed in the head portion of the bolt 120 can be inserted. That is, the fastening bolt 140 for connecting the jig 130 to the aluminum substrate 100 is passed through the hole of the fastening nut 150 and the jig 130 and is fastened to the head portion female screw 123 of the bolt 120 . By doing so, the jig 130 may be connected to the aluminum substrate 100 .

When the jig 130 is connected to the aluminum substrate 100 using the fastening bolt 140 and the fastening nut 150 in this way, a fastening structure as shown in FIG. 8 is formed. In FIG. 8 , the eight above-described fastening structures are shown on the non-external surface of the aluminum substrate 100 .

The fastening bolt 140 and the fastening nut 150 for fastening the jig 130 to the bolt 120 may be made of a titanium alloy.

As described above, the bolt 120 and the nut 110 are fastened to the groove 101 of the aluminum substrate 100 , and the jig 130 is fastened to the bolt 120 using the fastening bolt 140 and the fastening nut 150 . ) by connecting the jig 130 and the aluminum substrate 100, the aluminum substrate 100 and the jig 130 may be firmly coupled. Accordingly, it is possible to prevent the problem of the aluminum substrate 100 falling off from the jig 130 during the anodizing process.

In addition, since the aluminum plate manufactured according to the disclosed embodiment is firmly fastened during the process and an electric current can be applied uniformly, the jig 130 fastening marks, burning defects, and color deviation defects do not occur on the exterior. Accordingly, it is possible to manufacture a refrigerator door using an aluminum plate having a uniform appearance quality without local color deviation.

The disclosed embodiments have been described with reference to the accompanying drawings as described above. A person of ordinary skill in the art to which the published embodiment belongs will understand that the disclosed embodiment may be implemented in a form different from the disclosed embodiment without changing the technical spirit or essential features of the published embodiment. The disclosed embodiments are illustrative and should not be construed as limiting.

According to the present invention, it is possible to provide an aluminum anodizing method capable of preventing the occurrence of defects such as burning or color deviation.

Claims (12)

1. processing a plurality of grooves in which threads are formed on the surface of the aluminum substrate;

   fastening nuts and bolts to the plurality of grooves;

   connecting an anodizing fixture to the bolt;

   Aluminum anodizing method comprising; performing anodizing on the aluminum substrate connected to the jig through the bolt.
2. According to claim 1,

   Determining the number and radius of the bolts and nuts so that the limit energization amount of the bolts and nuts is greater than the required amount of current applied during anodizing; aluminum anodizing method further comprising.
3. According to claim 1,

   The bolt and nut is an aluminum anodizing method made of an aluminum alloy.
4. According to claim 1,

   The nut is an aluminum anodizing method having a circular cross-section.
5. The method of claim 1,

   Performing the anodizing is,

   When the surface area of the aluminum substrate is 1 m ² or more, performing anodizing so that the current density applied per surface area of the nut in contact with the aluminum substrate is 1 A/mm ² ; Aluminum anodizing method comprising a.
6. According to claim 1,

   Performing the anodizing is,

   When the surface area of the aluminum substrate is less than 1 m ² , performing anodizing so that the current density applied per surface area of the nut in contact with the aluminum substrate is 1.5 A/mm ² ; Aluminum anodizing method comprising a.
7. According to claim 1,

   Fastening the nuts and bolts to the plurality of grooves,

   An aluminum anodizing method comprising; fastening a bolt provided in a head having a threaded groove to the plurality of grooves.
8. 8. The method of claim 7,

   Connecting the anodizing jig to the bolt is,

   An aluminum anodizing method comprising a; fastening a fastening bolt to the groove of the bolt to connect the anodizing jig to the bolt.
9. 9. The method of claim 8,

   The fastening bolt is an aluminum anodizing method made of a titanium alloy.
10. According to claim 1,

    Processing a plurality of grooves in which threads are formed on the surface of the aluminum substrate,

    Aluminum anodizing method comprising; processing an even number of grooves to form a symmetry on the surface of the aluminum substrate.
11. According to claim 1,

    Processing a plurality of grooves in which threads are formed on the surface of the aluminum substrate,

    Aluminum anodizing method comprising; processing the plurality of grooves at a position spaced 100 mm from the edge of the aluminum substrate.
12. According to claim 1,

    Processing a plurality of grooves in which threads are formed on the surface of the aluminum substrate,

    Aluminum anodizing method comprising; processing the plurality of grooves having a diameter of 2.0 to 3.0 mm on the surface of the aluminum substrate.

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