JP2001079763A - Pellet for grinding wheel dresser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pellet for a grinding wheel dresser to make a grinding wheel capable of further reducing fine waviness of a polished article. SOLUTION: This pellet 2 is used for a grinding wheel dresser to carry out setting of a grinding wheel of a surface polishing machine. In this case, it is possible to make the grinding wheel capable of further reducing fine waviness of a polished article by using diamond abrasive grains of size of #800-#1500 for a pellet 1. Additionally, it is favourable that the diamond abrasive grains are contained in density of 1.5-3.0 carats per one cubic centimeter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellet for a grinding wheel dresser used for dressing a grinding wheel of a plane polishing machine.

[0002]

2. Description of the Related Art In a magnetic disk drive used in a computer, a magnetic disk, which is a donut-shaped disk-shaped recording medium, rotates at a high speed, and signals are recorded by a magnetic head floating above it in a hydrodynamic manner.・ Playback is performed. Therefore, high surface flatness is required for magnetic disks. Conventionally, in order to improve such surface flatness, a polishing process of a magnetic disk substrate has been improved,
Improvements have been made to the annealing process of a magnetic disk substrate, and to the uniformity of a magnetic film and the like laminated on a magnetic disk substrate. In particular, for a magnetic disk using an aluminum alloy substrate, high-precision polishing using a plane polisher is performed in order to increase the surface flatness of the aluminum alloy substrate. The plane polishing machine used at this time sets the aluminum alloy substrate to be polished between the disk-shaped grinding wheels arranged vertically, and the rotation of the upper and lower grinding wheels and the revolution of the aluminum alloy substrate cause the aluminum alloy substrate to rotate. This is a device for polishing both front and back surfaces of a substrate.

[0003] The grindstone used is a disk-shaped one in which a plurality of fan-shaped grindstone pieces in which abrasive grains are mixed with resin such as PVA are arranged. Since the flatness of the polished surface of the grindstone decreases with an increase in the amount of the polishing treatment, there is a problem that the surface flatness of the aluminum alloy substrate to be polished is reduced and an aluminum alloy substrate of sufficient quality cannot be obtained. is there. Therefore, dressing of a grindstone has been conventionally performed. The dressing of the grindstone is a method of using a grindstone dresser in which a large number of disc-shaped pellets, which are diamond grindstones, are arranged and setting the grindstone dresser in a plane polishing machine to restore the flatness of the grindstone on the upper and lower surfaces.

Conventionally, such a grinding wheel dressing has been disclosed in Japanese Patent Application Laid-Open No. H10-329004.
Instead of providing a plurality of disc-shaped pellets, a technique for improving the flatness of a grindstone using a grindstone dresser having one ring-shaped pellet has been disclosed.

[0005]

However, the above-mentioned method has been studied with respect to a large undulation on a grindstone which causes polishing unevenness between a plurality of aluminum alloy substrates set in a plane polishing machine. It has not been possible to sufficiently reduce minute surface irregularities (hereinafter, also referred to as "small undulations") on a grindstone, which cause a reduction in surface flatness in one aluminum alloy substrate.

[0006] Such minute undulations on the grindstone cause the surface flatness of the polished magnetic disk substrate to be reduced, causing small undulations on the magnetic disk substrate.
As a result, there is a possibility that a problem that high-speed rotation of the magnetic disk is suppressed may occur.

Accordingly, the present invention provides a pellet for a dresser of a grindstone to be set in a plane polisher so that a micro waviness of a magnetic disk substrate to be polished can be further reduced.

[0008]

According to a first aspect of the present invention, there is provided a pellet used for a grindstone dresser for dressing a grindstone of a flat-surface polisher, wherein diamond grains having a grain size of # 800 to # 1500 are used. It is characterized by being used.

According to the present invention, the pellet contains # 80
Since diamond abrasive grains having a particle size of 0 to # 1500 are used, the grindstone polished by the grindstone dresser provided with the pellets has its own minute waviness, and the minute wrinkles of the magnetic disk substrate as the object to be polished are reduced. The swell can be reduced.

According to a second aspect of the present invention, in the pellet for a grinding wheel dresser according to the first aspect, the diamond abrasive grains are contained at a density of 1.5 to 3.0 carats per cubic centimeter. Has features.

According to the present invention, the diamond abrasive grains
Since it is contained at a density of 1.5 to 3.0 carats per cubic centimeter, the grindstone polished by the grindstone dresser equipped with these pellets has a small undulation of its own, and the magnetic disk to be polished is The minute waviness of the substrate can be further reduced.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

FIG. 1 is a front view showing an example of a grindstone dresser 1 on which a pellet for a grindstone dresser (hereinafter referred to as “pellet 2”) of the present invention is arranged, and is used for dressing a grindstone of a plane polishing machine. Things. In the grindstone dresser 1, the pellets 2 play a role in sharpening the grindstone of the plane polishing machine.

The pellet 2 is mainly composed of diamond abrasive grains and a binder. The size of the pellet 2 is
The size of the grinding wheel dresser 1 on which the pellets 2 are arranged,
For example, in the grindstone dresser 1 shown in FIG.
A disk-shaped pellet 1 having a thickness of about 5 mm and a thickness of about 5 mm can be used.

The binder forms the base material of the pellets 2, and serves to fix the uniformly dispersed diamond abrasive grains in the pellets 2. Examples of the binder include commonly used metal bonds, resinoid bonds, vitrify bonds, and electrodeposited bonds. In the present invention, a Cu—Sn alloy that is one of the metal bonds can be preferably used.

The diamond abrasive grains are fixed in the pellets 2 by a binder and exist uniformly dispersed therein, and play a role of polishing the surface of the grinding stone. As the diamond abrasive, those having a particle size in the range of # 800 to # 1500 are used, and those having a particle size of # 1000 to # 1500 are more preferably used. The pellets 2 made of diamond abrasive grains having such a particle size range can reduce the waviness of the grinding wheel surface, so that the surface roughness of the magnetic disk substrate polished by such a whetstone is reduced, and the micro waviness is reduced. It can contribute to the improvement of the surface flatness. Note that the fine waviness here is almost synonymous with the surface roughness, and the center line average roughness (Ra) obtained by the surface roughness measurement specified in JIS B0601, and the pitch between the peaks of the obtained curve. And so on.
A small undulation means that the obtained center line average roughness (Ra) is small, and the pitch between the peaks of the obtained curve is small. A large undulation means that the obtained center line average roughness is small. (Ra) is large, and the pitch between the peaks of the obtained curve is also large.

If the particle size of the diamond abrasive grains is less than # 800, the fine waviness of the grinding wheel after dressing cannot be reduced, and the fine waviness of the magnetic disk substrate polished by such a whetstone must be sufficiently reduced. Can not. On the other hand, when the grain size of the diamond abrasive grains exceeds # 1500, the fine waviness of the grinding wheel after dressing can be sufficiently reduced, and the fine waviness of the magnetic disk substrate polished with such a whetstone is sufficiently reduced. However, since the diamond abrasive grains to be used are extremely fine, it causes an increase in cost and causes an economic problem. Therefore, in terms of technical effect, # 1500
However, in consideration of economy, the range of # 800 to # 1500 is practically preferable. When the pellet 2 composed of the diamond abrasive grains having the above-mentioned particle size range is used for the grindstone dresser 1, the minute waviness of the grindstone polished by the grindstone dresser 1 can be reduced. As a result, by using such a grindstone, Further, it is possible to reduce the minute waviness of the aluminum alloy substrate for a magnetic disk which is the object to be polished, and to further improve the surface flatness.

Further, it is preferable that the diamond abrasive grains are contained in the pellets 2 at a density of 1.5 to 3.0 carats per cubic centimeter. The pellets 2 in which diamond abrasive grains are dispersed at such a density can further reduce the waviness of the whetstone surface, so that the surface roughness of the magnetic disk substrate polished by such whetstones is reduced, and the fine waviness is further reduced. This contributes to the improvement of the surface flatness.

If the density of the diamond abrasive grains is less than 1.5 carats per cubic centimeter, it is not possible to sufficiently reduce the waviness of the whetstone after dressing, and the fine wrinkles of the magnetic disk substrate polished by such whetstones will not be obtained. The swell cannot be reduced sufficiently. At this time, the density of the diamond abrasive grains is preferably as high as possible. However, in practice, it is preferable to set the upper limit to 3.0 carats or less per cubic centimeter from the limit of the binding performance of the binder for fixing the diamond abrasive grains. When the density of the diamond abrasive grains exceeds 3.0 carats per cubic centimeter, the diamond abrasive grains are not sufficiently fixed by the binder, and may be ragged and peeled off.

Note that the density of diamond abrasive grains is generally represented by a degree of concentration, and a degree of concentration of 100 corresponds to 4.4 carats. One carat is 200mg of diamond abrasive
1.5 to 3.0 carats per cubic centimeter (concentration 34.1 to 68.2)
Range corresponds to diamond abrasive grains in the range of 300-600 mg.

As shown in FIG. 1, a plurality of the pellets 2 for a grinding wheel dresser of the present invention are used at a predetermined position of the grinding wheel dresser 1. The grindstone dresser 1 can contribute to reducing the surface roughness of the polished grindstone and eliminating minute waviness on the grindstone. By using the grindstone in which the minute waviness is sufficiently eliminated in this way, the surface flatness of the aluminum alloy substrate for a magnetic disk, which is the object to be polished, can be further improved.

[0022]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. (Example 1) Diamond abrasive grains having a grain size of # 1000 (average grain diameter: about 7-14 µm) were used, and the content of the diamond abrasive grains was adjusted to 2.2 carats per cubic centimeter (concentration degree The particles were adjusted so as to be uniformly dispersed at a density of 50), and diamond abrasive grains were fixed with a Cu-Sn alloy binder to produce pellets. FIG. 2 is a micrograph (× 60) of the dispersed state of diamond abrasive grains dispersed in the pellet. In this pellet, the diamond abrasive grains were dispersed in the binder at a much finer pitch than in Comparative Example 1 described later.
The obtained pellets of the present invention were disk-shaped with a diameter of 16 mm and a thickness of 5 mm, and were arranged as shown in FIG. 1 to produce a grindstone dresser. (Comparative Example 1) A diamond abrasive having a particle size of # 600 (average particle size: about 20 to 30 µm) was used, and the content of the diamond abrasive was set to 0.88 carats per cubic centimeter (concentration degree Adjustment was performed so that the particles were uniformly dispersed at the density of 20), and diamond abrasive grains were fixed with a binder of a Cu-Sn alloy to produce pellets. FIG. 3 is a micrograph (× 60) of the dispersed state of the diamond abrasive grains dispersed in the pellet. In this pellet, the diamond abrasive grains were dispersed in the binder at a larger pitch than in Example 1 described above. The obtained conventional-type pellets were disk-shaped with a diameter of 16 mm and a thickness of 5 mm, and were arranged as shown in FIG. 1 to produce a grinding wheel dresser. (Polishing Result) Using the grindstone dresser manufactured in Example 1 and the grindstone dresser manufactured in Comparative Example 1, a used grindstone having a roughly rough surface was polished. Thereafter, the surface morphology and surface roughness of the aluminum alloy magnetic disk substrate polished by the grindstone were measured.

FIG. 4A shows the profile of the surface morphology of the magnetic disk substrate obtained when the grindstone dresser prepared in Example 1 was used. FIG. 4B shows the profile prepared in Comparative Example 1. 4 is a profile of a surface morphology of a magnetic disk substrate obtained when a grindstone dresser is used. As is clear from these, the surface morphology of the magnetic disk substrate obtained using the grindstone dresser manufactured in Example 1 was the same as that of the magnetic disk substrate obtained using the grindstone dresser manufactured in Comparative Example 1. It can be seen that the surface is flatter than the surface morphology, and it is clear that the surface flatness is improved.

FIG. 5A shows the profile of the surface roughness of the magnetic disk substrate obtained when the grindstone dresser manufactured in Example 1 was used, and FIG. 5B shows Comparative Example 1. 4 is a profile of the surface roughness of a magnetic disk substrate obtained when the grindstone dresser manufactured in step 1 was used. As is clear from these, the magnetic disk substrate obtained using the grindstone dresser manufactured in Example 1 is more than the magnetic disk substrate obtained using the grindstone dresser manufactured in Comparative Example 1. It is clear that both the center line average roughness (Ra) and the pitch are small, and the fine waviness is improved.

As shown in FIG. 2 and FIG. 3, the difference between the minute undulations is based on the size of the diamond abrasive grains dispersed in the pellets and the dispersion state, that is, the difference in pitch between the diamond abrasive grains. Conceivable. In other words, by changing the particle size and density of the diamond abrasive particles dispersed in the pellet, the fine waviness of the grindstone surface polished by the grindstone dresser on which the pellet is arranged is improved, and the surface is polished with the improved grindstone. It is considered that this reduces the undulation on the surface of the magnetic disk substrate.

[0026]

As described above, # 800 to # 15
Since the grinding wheel dresser on which the pellets of the present invention having the diamond abrasive grains of 00 are arranged reduces the surface roughness of the grinding wheel to reduce minute undulations, the aluminum alloy substrate for a magnetic disk polished with such a grinding stone has small undulations. And its surface flatness is improved. As a result, it is possible to contribute to the manufacture of a high quality magnetic disk. Further, the grinding wheel dresser on which the pellets of the present invention in which the diamond abrasive grains are fixed at a density of 1.5 to 3.0 carats per cubic centimeter is arranged to further reduce the surface roughness of the grinding wheel and to reduce minute waviness. Therefore, it is possible to further reduce the minute waviness of the magnetic disk substrate to be polished.

[Brief description of the drawings]

FIG. 1 is a plan view showing an example of a grinding wheel dresser on which pellets for the grinding wheel dresser of the present invention are arranged.

FIG. 2 is a micrograph (× 60) of a dispersed state of diamond abrasive grains dispersed in the pellet for a grinding wheel dresser of the present invention.

FIG. 3 is a photomicrograph (× 60) of a conventional grinding stone dresser pellet in a state of dispersion of diamond abrasive grains dispersed in the pellet.

FIG. 4 shows the profile of the surface morphology of a magnetic disk substrate made of an aluminum alloy, which is obtained by polishing a grindstone with the prepared grindstone dresser and then polished by the grindstone, using the pellet of the present invention (a) and the conventional pellet Is compared with (b) in the case of using.

FIG. 5 shows the profile of the surface roughness of a magnetic disk substrate made of an aluminum alloy, which is obtained by polishing a grindstone with a prepared grindstone dresser and then polished by the grindstone, using the pellet of the present invention (a) and the conventional one. This is a comparison between the case where pellets are used and the case (b).

[Explanation of symbols]

 1 Abrasive dresser 2 Pellet 3 Diamond abrasive 4 Binder

Claims (2)

[Claims] 1. A pellet used for a grinding wheel dresser for sharpening a grinding wheel of a plane polishing machine, wherein the pellets are diamond abrasive grains having a grain size of # 800 to # 1500. Pellet for whetstone dresser. 2. A pellet for a grinding wheel dresser according to claim 1, wherein said diamond abrasive grains are contained at a density of 1.5 to 3.0 carats per cubic centimeter.