JP7553382B2 - Manufacturing method of electroplated abrasive tools - Google Patents

Description

The present invention relates to a method for manufacturing electroplated abrasive tools.

Patent Document 1 describes an electroplated abrasive tool in which abrasive grains such as diamond or CBN are fixed to the surface of a base material (also called a base metal) made of an iron-based material by nickel plating. Patent Document 2 also describes a similar electroplated abrasive tool.

In recent years, the use of aluminum or aluminum alloys as the substrate has been considered in order to reduce weight. However, the bonding strength between the aluminum-based substrate and the plating layer for fixing the abrasive grains is insufficient, making it difficult to use an aluminum-based substrate.

Incidentally, as a method for roughening the surface of an aluminum-based material, for example, double zincate treatment is known, as described in Patent Document 3. In addition, a method different from zincate treatment is proposed as a method for roughening the surface of an aluminum-based material in Patent Document 4.

JP 2014-111302 A Japanese Unexamined Patent Publication No. 6-114739 Japanese Unexamined Patent Publication No. 61-148900 JP 2007-138224 A

When double zincate treatment is applied as a method for roughening aluminum-based substrates, the strongly alkaline treatment solution is not easy to handle, and partial plating is not possible when a strongly alkaline treatment solution is used. In electroplated abrasive tools, it is necessary to form a plating layer only on the portion where the abrasive grains are placed, and to prevent a plating layer from being formed on the mounting surface that abuts against the mating member. However, as mentioned above, double zincate treatment uses a strongly alkaline treatment solution, which makes masking difficult and makes partial plating impossible. Therefore, double zincate treatment cannot be applied to form a roughened surface of an aluminum-based substrate.

The present invention aims to provide a method for manufacturing an electroplated abrasive tool that uses aluminum or an aluminum alloy as a base material without the need for double zincate treatment, and that can increase the bonding strength between the base material and the plating layer that secures the abrasive grains.

The method for manufacturing an electroplated abrasive tool is a method for manufacturing an electroplated abrasive tool in which abrasive grains are fixed to the surface of a substrate, and includes a substrate roughening step in which the substrate surface made of aluminum or an aluminum alloy is brought into contact with an acidic solution that contains copper ions and dissolves aluminum or an aluminum alloy, thereby dissolving the substrate surface and replacing the substrate surface with copper as a replacement metal, a replacement metal selective etching step in which the replacement metal on the substrate surface is selectively etched using the acidic solution to expose the roughened surface of the substrate, a base plating step in which a base plating layer is formed on the roughened surface of the substrate, and an abrasive grain fixing step in which abrasive grains are arranged on the surface of the base plating layer and a fixed plating layer is formed to fix the abrasive grains.

An acidic solution is used in the substrate roughening process and the selective replacement metal etching process. This makes it possible to partially mask the surface of the substrate, allowing the substrate surface to be partially roughened. Furthermore, by roughening the surface of the aluminum or aluminum alloy substrate, the undercoat plating layer is engaged with the irregularities on the substrate surface. This increases the bonding strength between the substrate and the undercoat plating layer. Furthermore, a fixing plating layer for fixing the abrasive grains is formed on the surface of the undercoat plating layer, ensuring sufficient bonding strength between the plating layers. This increases the bonding strength between the substrate and the abrasive grains.

In this way, by using aluminum or an aluminum alloy for the substrate, the weight of the electroplated abrasive tool can be reduced. Since the surface of the substrate can be roughened using an acidic liquid instead of a strongly alkaline liquid, partial plating can be performed and handling is also improved. Furthermore, by roughening the surface of the substrate, the bonding strength between the substrate and the undercoat plating layer can be increased, and as a result, a high bonding strength between the substrate and the abrasive can be ensured.

FIG. 2 is a cross-sectional view of an electroplated abrasive tool. FIG. 2 is an enlarged cross-sectional view of a surface portion of an electroplated abrasive tool. 1 is a flowchart showing a method for manufacturing an electroplated abrasive tool. 1 is an enlarged view showing a surface portion of a substrate in a substrate roughening step, in which the two-dot chain line indicates the shape of the substrate before the substrate roughening step. FIG. 2 is an enlarged view showing a surface portion of a substrate in a selective replacement metal etching step. FIG. 4 is an enlarged view showing a surface portion of a substrate in a base plating step. FIG. 4 is an enlarged view showing a surface portion of the substrate in an abrasive grain arrangement step. FIG. 4 is an enlarged view showing a surface portion of a substrate in a temporary fixing plating process. 1 is a table showing the presence or absence of corrosion of the surface of a substrate when the thickness of an undercoat plating layer is changed.

(1. Types of electroplated abrasive tools)
Electrodeposited abrasive tools include electrodeposited wheels and electrodeposited dressers, and are tools in which abrasive grains are fixed to the surface of a substrate by electroplating.

An electroplated wheel (also called an electroplated grinding wheel) is a tool for grinding metal workpieces, in which abrasive grains (e.g., superabrasive grains) such as diamond or CBN are fixed to the surface of a substrate. An electroplated wheel has, for example, a configuration in which multiple abrasive grains are fixed to the outer peripheral surface of a disk-shaped substrate, or a configuration in which multiple abrasive grains are fixed to the axial end surface on the outer peripheral side of a disk-shaped substrate. However, the substrate is not limited to being disk-shaped, and can be formed into any shape, and the position at which the abrasive grains are arranged can also be set arbitrarily. In addition, the multiple abrasive grains are fixed to the surface of the substrate by a plating layer. The plating layer is, for example, nickel plating.

An electroplated dresser is, for example, a tool for dressing or truing the surface of a grinding wheel. Like an electroplated wheel, an electroplated dresser is a tool in which multiple superabrasive grains such as diamonds are fixed to the surface of a substrate by a plating layer. The substrate of an electroplated dresser may be disk-shaped or may be any shape other than disk-shaped. For example, an electroplated rotary dresser has multiple abrasive grains fixed to the outer peripheral surface of a disk-shaped substrate by a plating layer.

(2. Configuration of Electrodeposited Abrasive Tool 1)
The configuration of an electrodeposited abrasive tool 1 will be described with reference to Fig. 1. The electrodeposited abrasive tool 1 includes a substrate 10, abrasive grains 20, and a plating layer 30.

The substrate 10 is made of aluminum or an aluminum alloy. The substrate 10 is formed, for example, in a disk shape, with a through hole formed in the center. The inner circumferential surface of the through hole constitutes the mounting surface 11 for mounting the electroplated abrasive tool 1 to a mating member (as shown in the figure). The mounting surface 11 of the electroplated abrasive tool 1, i.e., the inner circumferential surface of the through hole, is the portion where the substrate 10 is exposed and comes into direct contact with the mating member. In other words, the mounting surface 11 is a surface that is not plated or the like.

The outer peripheral surface of the substrate 10 may be formed into any shape. In FIG. 1, the outer peripheral surface of the substrate 10 is formed into a cylindrical outer peripheral surface. Alternatively, the outer peripheral surface of the substrate 10 may be formed into a mountain shape or the like in the axial cross section.

The abrasive grains 20 are superabrasive grains such as diamond or CBN. The abrasive grains 20 are fixed to the surface of the substrate 10. In the electroplated abrasive tool 1 shown in FIG. 1, the abrasive grains 20 are fixed to the outer peripheral surface of the substrate 10.

The plating layer 30 is a layer for fixing the abrasive grains 20 to the surface of the substrate 10 by electrochemical deposition. The plating layer 30 is bonded to the surface of the substrate 10 and also to the surface of the abrasive grains 20. The plating layer 30 is, for example, nickel plating.

(3. Detailed configuration of the surface of the electroplated abrasive tool 1)
The detailed configuration of the surface of the electrodeposited abrasive tool 1 will be described with reference to Fig. 2. As described above, the electrodeposited abrasive tool 1 includes the substrate 10, the abrasive grains 20, and the plating layer 30. The surface 10a of the substrate 10 is roughened to have an uneven shape as shown in Fig. 2. In particular, the roughened surface 10a of the substrate 10 has a large uneven shape, and the large uneven shape has even smaller uneven shapes on the surface. In other words, the roughened surface 10a of the substrate 10 has an undercut shape in the vertical direction of Fig. 2 due to the small uneven shapes.

The plating layer 30 comprises a base plating layer 31 and a fixed plating layer 32. The base plating layer 31 is plated with a plating material on the roughened surface 10a of the substrate 10. The base plating layer 31 has a predetermined thickness H from the convex end (the portion corresponding to the maximum height) of the unevenness of the roughened surface 10a of the substrate 10. In other words, the base plating layer 31 completely covers the convex portions of the unevenness of the roughened surface 10a of the substrate 10, and is completely embedded in the concave portions of the unevenness of the roughened surface 10a. In other words, the base plating layer 31 completely covers the roughened surface 10a of the substrate 10, and there is no portion where the roughened surface 10a is exposed.

The fixed plating layer 32 is plated on the surface of the base plating layer 31 and bonds the base plating layer 31 and the abrasive grains 20. The fixed plating layer 32 includes a temporary fixed plating layer 32a and a permanent fixed plating layer 32b. The temporary fixed plating layer 32a is a plating layer for temporarily fixing the abrasive grains 20 to the surface of the base plating layer 31. The temporary fixed plating layer 32a is preferably made of the same plating material as the base plating layer 31, for example, nickel plating. This increases the bond strength between the base plating layer 31 and the temporary fixed plating layer 32a.

The fixed plating layer 32b is a plating layer formed on the surface of the temporary fixed plating layer 32a. The fixed plating layer 32b bonds the abrasive grains 20 to the temporary fixed plating layer 32a, and serves to firmly bond the abrasive grains 20 to the base plating layer 31. The fixed plating layer 32b may be made of the same plating material as the temporary fixed plating layer 32a, for example nickel plating. The thicknesses of the temporary fixed plating layer 32a and the fixed plating layer 32b are appropriately changed depending on the size of the abrasive grains 20.

(4. Manufacturing method of electroplated abrasive tool 1)
The manufacturing method of the electroplated abrasive tool 1 will be described with reference to Figs. 3 to 8. First, as a preliminary step, the surface of the substrate 10 is masked except for the portion where the abrasive grains 20 are to be disposed. Next, the surface of the substrate 10 is degreased, and then washed with water (S1: degreasing step, S2: water washing step). The degreasing step uses an alkaline liquid such as caustic soda, sodium phosphate, or a mixture of other liquids. For example, the degreasing step involves contacting the substrate 10 with an aqueous solution of sodium hydroxide at a concentration of 0.25 mol/L at a temperature of 50°C. The treatment time is 60 seconds.

Next, a process of roughening the surface of the substrate 10 is carried out, followed by rinsing with water (S3: substrate roughening process, S4: water rinsing process). The substrate roughening process is a treatment for dissolving the surface of the substrate 10 and replacing the surface of the substrate 10 with copper. In the substrate roughening process, the substrate 10 is brought into contact with an acidic solution that contains copper ions and dissolves aluminum or an aluminum alloy.

Here, the acidic solution has, for example, a hydrochloric acid concentration of 0.1 mol/L to 5.0 mol/L and a copper ion concentration of 0.004 mol/L to 1.0 mol/L. In the substrate roughening process, the substrate 10 is brought into contact with the acidic solution at a temperature of 30°C to 80°C. The treatment time is 30 sec to 20 min.

The substrate roughening process results in the surface portion of the substrate 10 becoming as shown in FIG. 4. That is, in the substrate roughening process, the surface of the substrate 10 is dissolved and formed into an uneven shape (relatively large unevenness). Furthermore, in the substrate roughening process, the dissolved aluminum on the surface of the substrate 10 is replaced with copper as a replacement metal, and copper 40 precipitates on the surface of the substrate 10. As shown diagrammatically in FIG. 4, the surface of the substrate 10 has a large uneven shape, and copper 40, indicated by a circle, precipitates on the large uneven surface.

Next, copper 40 as a replacement metal on the surface of the substrate 10 is selectively etched using an acidic solution to expose the roughened surface 10a of the substrate 10, which is then washed with water (S5: replacement metal selective etching step, S6: water washing step). In the replacement metal selective etching step, the substrate 10 after the substrate roughening step (S3) is brought into contact with an acidic solution that preferentially dissolves copper 40 as a replacement metal over the substrate 10, thereby dissolving copper as a replacement metal while preventing the substrate 10 from dissolving.

Here, the acid solution used in the selective replacement metal etching process is a strong acid such as hydrochloric acid, sulfuric acid, or nitric acid. For example, the acid solution uses sodium persulfate with a concentration of 0.2 mol/L to dissolve copper as the replacement metal. The processing time is 60 seconds.

By the selective replacement metal etching process, the roughened surface 10a of the substrate 10 becomes as shown in FIG. 5. That is, the roughened surface 10a of the substrate 10 is represented by the boundary between the substrate 10 and the copper, which is the replacement metal, on the surface of the substrate 10 shown in FIG. 4. Therefore, the roughened surface 10a of the substrate 10 has a large uneven shape due to the dissolution of the substrate 10, and the surface of the large uneven shape further has a small uneven shape due to the selective replacement metal etching. In other words, the roughened surface 10a of the substrate 10 has an undercut shape in the vertical direction of FIG. 5 due to the small uneven shapes.

Next, it is determined whether the substrate roughening process (S3) and the replacement metal selective etching process (S5) have been performed a preset number of times (S7). The preset number of times is set to, for example, once or twice, but may be three or more times. If the preset number of times has not been reached (S7: No), the process returns to S3, and the substrate roughening process (S3) and the replacement metal selective etching process (S5) are performed again.

Here, the roughened surface 10a of the substrate 10 after the selective replacement metal etching process after the specified number of times has an arithmetic mean roughness Ra (JIS B 0031:2003, ISO 1302:2002) of 1 μm or more, or a maximum height Rz (JIS B 0031:2003, ISO 1302:2002) of 10 μm or more. Furthermore, the roughened surface 10a of the substrate 10 after the selective replacement metal etching process after the specified number of times has an arithmetic mean roughness Ra of 1 μm or more and 6 μm or less (1 to 6 μm), or a maximum height Rz of 10 μm or more and 35 μm or less (10 to 35 μm).

After the specified number of times is reached (S7: Yes), a desmutting process is performed, followed by rinsing with water (S8: desmutting process, S9: rinsing process). The desmutting process removes smut adhering to the roughened surface 10a of the substrate 10. The desmutting process is performed, for example, using 10% Top Desmut N-20 (manufactured by Okuno Chemical Industries Co., Ltd.) at room temperature for a treatment time of 12 to 24 hours.

Next, a base plating layer 31 is formed on the roughened surface 10a of the substrate 10 (S10: base plating step). The base plating layer 31 is, for example, nickel plating. In the base plating step, as shown in FIG. 6, a base plating layer 31 having a thickness H from the convex end of the unevenness of the roughened surface 10a of the substrate 10 is formed. Here, the thickness H of the base plating layer 31 is at least 6 μm, and preferably 8 μm or more. Therefore, the base plating layer 31 is embedded in the recesses of the roughened surface 10a of the substrate 10, and further completely covers the convex end and the recesses.

Here, known electroplating is applied to form the undercoat plating layer 31 with a thickness H of 6 μm or more. Furthermore, by employing electroplating, the undercoat plating layer 31 made of nickel plating can be formed on the roughened surface 10a of the substrate 10 without replacing the roughened surface 10a of the substrate 10 with nickel. In other words, the undercoat plating layer 31 is physically anchored to the roughened surface 10a of the substrate 10. Therefore, the undercoat plating layer 31 has a high bonding strength to the substrate 10 due to the anchor effect. Note that electroless plating may be used to form the undercoat plating layer 31 with a thickness H of 6 μm or more.

Next, as shown in FIG. 7, the abrasive grains 20 are arranged on the surface of the base plating layer 31 (S11: abrasive grain arrangement process, abrasive grain fixing process). Next, as shown in FIG. 8, a temporary fixed plating layer 32a is formed to fix the abrasive grains 20 to the base plating layer 31 (S12: temporary fixed plating process, abrasive grain fixing process). The thickness of the temporary fixed plating layer 32a is set according to the size of the abrasive grains 20. The temporary fixed plating layer 32a is, for example, nickel plating. In other words, by using the same type of plating material for the temporary fixed plating layer 32a as the base plating layer 31, high bonding strength with the base plating layer 31 can be ensured. In addition, the temporary fixed plating layer 32a is formed by electroplating because it needs a thickness to hold the abrasive grains 20.

Next, as shown in FIG. 2, a permanent fixed plating layer 32b is formed on the surface of the temporary fixed plating layer 32a (S13: permanent fixed plating process, abrasive grain fixing process). The thickness of the permanent fixed plating layer 32b is set according to the size of the abrasive grain 20. The permanent fixed plating layer 32b is nickel plated, just like the temporary fixed plating layer 32a. In other words, by using the same type of plating material for the permanent fixed plating layer 32b as for the temporary fixed plating layer 32a, high bonding strength with the temporary fixed plating layer 32a can be ensured. In addition, electroless plating is preferably applied to the permanent fixed plating layer 32b. In this manner, the electroplated abrasive grain tool 1 is manufactured.

(5. Evaluation)
The thickness H of the undercoat plating layer 31 was changed, and an evaluation was performed to check the presence or absence of corrosion on the surface of the substrate 10. The thickness H (shown in FIG. 6) of the undercoat plating layer 31 was set to 2.0 μm, 4.0 μm, 6.0 μm, 8.0 μm, and 10.0 μm. The corrosion of the substrate 10 was evaluated based on the presence or absence of black stains on the surface of the substrate 10.

The results are shown in FIG. 9. That is, when the thickness H of the base plating layer 31 was 2.0 μm and 4.0 μm, corrosion was confirmed. On the other hand, when the thickness H of the base plating layer 31 was 6.0, 8.0, and 10.0 μm, corrosion was not confirmed. That is, by making the thickness H of the base plating layer 31 at least 6.0 μm, corrosion can be suppressed. Preferably, by making the thickness H of the base plating layer 31 8.0 μm or more, corrosion can be reliably suppressed. Note that the thicker the thickness H of the base plating layer 31, the longer the processing time and processing costs required. Therefore, it is preferable to make the thickness H of the base plating layer 31, for example, 10.0 μm or less.

Next, the peel strength of the undercoat plating layer 31 relative to the surface roughness of the roughened surface 10a of the substrate 10 was evaluated. Specifically, the copper ion concentration of the acidic solution in the substrate roughening process, the concentration of hydrochloric acid, etc. were adjusted to change the surface roughness of the roughened surface 10a of the substrate 10. The arithmetic mean roughness Ra was set to 0.5, 1, 3, 6, and 9 μm. When the arithmetic mean roughness Ra was 0.5 μm and 9 μm, the anchor effect was weak and the peel strength of the undercoat plating layer 31 was small. When the arithmetic mean roughness Ra was 1 to 6 μm, a predetermined peel strength could be ensured.

As another index, the maximum height Rz was set to 5, 10, 15, 20, 25, 30, 35, 40, 45, and 50 μm. When the maximum height Rz was 5 μm or more and 40 μm or more, the anchor effect was weak and the peel strength of the undercoat plating layer 31 was small. When the maximum height Rz was 10 to 35 μm, the specified peel strength could be ensured.

(6. Effects)
In the substrate roughening step S3 and the selective replacement metal etching step S5, an acidic solution is used. Therefore, it is possible to partially mask the surface of the substrate 10, and the surface of the substrate 10 can be partially roughened. Furthermore, by roughening the surface of the aluminum or aluminum alloy substrate 10, the undercoat plating layer 31 is engaged with the unevenness of the surface of the substrate 10. Therefore, the bonding strength between the substrate 10 and the undercoat plating layer 31 is increased. In addition, a fixing plating layer 32 for fixing the abrasive grains 20 is formed on the surface of the undercoat plating layer 31, and the bonding strength between the plating layers can be sufficiently secured. Therefore, the bonding strength between the substrate 10 and the abrasive grains 20 can be increased.

In this way, by using aluminum or an aluminum alloy for the substrate 10, the weight of the electroplated abrasive tool 1 can be reduced. Since the surface of the substrate 10 can be roughened using an acidic liquid instead of a strongly alkaline liquid, partial plating can be performed and handling is also improved. Furthermore, by roughening the surface of the substrate 10, the bonding strength between the substrate 10 and the undercoat plating layer 31 can be increased, and as a result, a high bonding strength between the substrate 10 and the abrasive grains 20 can be ensured.

1: Electrodeposited abrasive tool, 10: Substrate, 10a: Roughened surface, 11: Mounting surface, 20: Abrasive, 30: Plating layer, 31: Base plating layer, 32: Fixed plating layer, 32a: Temporary fixed plating layer, 32b: Main fixed plating layer, 40: Copper (replacement metal) S3: Substrate roughening process, S5: Replacement metal selective etching process, S11-S13: Abrasive fixing process

Claims (4)

A method for manufacturing an electroplated abrasive tool having abrasive grains fixed to a surface of a substrate, comprising the steps of:
A substrate roughening step in which the substrate made of aluminum or an aluminum alloy is contacted with an acidic solution containing copper ions and dissolving aluminum or an aluminum alloy, thereby dissolving the surface of the substrate and replacing the surface of the substrate with copper as a replacement metal;
a selective etching step of selectively etching the replacement metal on the surface of the base material using an acidic liquid to expose the roughened surface of the base material;
a base plating step of forming a base plating layer on the roughened surface of the base material;
an abrasive grain fixing step of disposing abrasive grains on a surface of the undercoat plating layer and forming a fixing plating layer for fixing the abrasive grains;
A method for manufacturing an electroplated abrasive tool comprising the steps of: The method for manufacturing an electroplated abrasive tool according to claim 1, wherein the undercoat plating step forms the undercoat plating layer having a thickness of at least 6 μm from the convex ends of the unevenness of the roughened surface of the substrate by electroplating or electroless plating. The method for manufacturing an electroplated abrasive tool according to claim 1 or 2, wherein the roughened surface of the substrate has an arithmetic mean roughness Ra (JIS B 0031:2003, ISO 1302:2002) of 1 μm or more, or a maximum height Rz (JIS B 0031:2003, ISO 1302:2002) of 10 μm or more. The method for manufacturing an electroplated abrasive tool according to any one of claims 1 to 3, wherein the undercoat plating layer and the fixed plating layer are nickel plating.

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