Spacer and hard disk drive device
阅读说明:本技术 间隔件和硬盘驱动器装置 (Spacer and hard disk drive device ) 是由 高野正夫 于 2018-08-31 设计创作,主要内容包括:在硬盘驱动器装置的装配时、根据需要在将磁盘和间隔件从硬盘驱动器装置中抽出时,为了抑制由把持夹具所致的间隔件的抽出的失败,使间隔件的外周端面的表面粗糙度Rz为1.5μm以上。(When the disk and the spacer are extracted from the hard disk drive device as needed during assembly of the hard disk drive device, the surface roughness Rz of the outer peripheral end face of the spacer is set to 1.5 μm or more in order to suppress failure of extraction of the spacer by the holding jig.)
1. A spacer which is an annular spacer provided in a hard disk drive device so as to be in contact with a magnetic disk,
the surface roughness Rz of the outer peripheral end surface of the spacer is 1.5 [ mu ] m or more.
2. The spacer according to claim 1, wherein the surface roughness Rz of the outer peripheral end face is 20 μm or less.
3. The spacer according to claim 1 or 2, wherein a groove extending along an outer periphery of the spacer is formed at the outer peripheral end face.
4. The spacer according to any one of claims 1 to 3, wherein the degree of skewness of the outer peripheral end surface is 1.2 or less.
5. The spacer of any of claims 1-4, wherein the spacer is comprised of glass.
6. The spacer according to any one of claims 1 to 5, wherein a conductive film is formed on a surface of the spacer.
7. A hard disk drive device comprising the spacer of any one of claims 1 to 6.
8. The hard disk drive device according to claim 7, wherein 8 or more magnetic disks are mounted.
Technical Field
The present invention relates to an annular spacer provided in a hard disk drive device for magnetic recording so as to be in contact with a magnetic disk, and a hard disk device using the spacer.
Background
With the recent rise of cloud computing, many hard disk drive devices (hereinafter, referred to as HDD devices) have been used in data centers for cloud computing to increase the storage capacity. Accordingly, it is desired that each HDD device have a larger storage capacity than ever before.
In a conventional magnetic disk, the flying distance of a magnetic head with respect to the magnetic disk is extremely small, and many magnetic disks are mounted on an HDD device. Therefore, it is considered to increase the number of magnetic disks mounted in the HDD device.
In the HDD device, an annular spacer for holding the magnetic disks apart from each other is provided between the magnetic disks in the HDD device. The spacer has a function of disposing the disks at predetermined positions with high accuracy without bringing the disks into contact with each other. On the other hand, since the spacer is in contact with the disk, foreign matter such as particles may be generated from the spacer due to friction between the disk and the spacer in the contact. In this case, the long-term reliability of the HDD device is easily lost due to the action of the generated particles. Therefore, it is desirable to reduce the generation of particles at the interface of the disk and the spacer.
As such a spacer, a spacer in which a surface of the spacer is etched with an etching solution and then a conductive coating film is formed on the surface of the spacer is known (patent document 1).
It is said that the generation of fine particles can be greatly reduced thereby.
Disclosure of Invention
Problems to be solved by the invention
When such a spacer and a magnetic disk are assembled in an HDD device, inner holes of the magnetic disk and the spacer are alternately inserted into a spindle of the HDD device, the magnetic disk and the spacer are stacked, and then the magnetic disk and the spacer are pressed from the spindle direction and assembled in the HDD device. In addition, in order to extract a specific magnetic disk found to have a defect in a performance test or the like from the assembled HDD device, the stacked magnetic disks and the spacer are sequentially extracted. At this time, the disk and the spacer are gripped by a gripping jig of the assembling apparatus, and are assembled or extracted.
In the HDD device to be mounted, since the disk and the spacer are pressed strongly in the spindle direction to be in close contact with each other, when the spacer in close contact with the disk is extracted, it may be difficult for the gripping jig of the mounting device to grip the outer peripheral end face of the spacer and extract the spacer. That is, the spacer that adheres to the disk may be difficult to peel off from the disk (hereinafter, this non-peeling case is simply referred to as a pull-out failure).
In addition, when the spacer is not extracted by the gripping jig, friction is generated between the outer peripheral end surface of the spacer and the gripping jig, and therefore foreign matter such as fine particles (granules) may be generated due to the friction.
In particular, when an attempt is made to increase the number of disks to be mounted on the HDD device, the number of spacers between the disks also increases. Therefore, since the number of extracted spacers is increased and the number of spacers that adhere to the disk is also increased, when attempting to extract the spacers by using the gripping jig, the extraction failure of the spacers is more likely to occur, and the generation of particles that cause a reduction in the long-term reliability of the HDD device is likely to occur.
Accordingly, an object of the present invention is to provide a spacer and an HDD device that can suppress a failure in extracting the spacer by a gripping jig when a disk and the spacer are extracted from the HDD device as needed in the assembly of the HDD device.
Means for solving the problems
One aspect of the present invention is a spacer which is an annular spacer provided in a hard disk drive device so as to be in contact with a magnetic disk.
The surface roughness Rz of the outer peripheral end surface of the spacer is 1.5 [ mu ] m or more.
The surface roughness Rz of the outer peripheral end surface is preferably 20 μm or less.
Preferably, the outer peripheral end surface is formed with a groove extending along the outer periphery of the spacer.
The skewness of the outer peripheral end surface is preferably 1.2 or less.
The skewness is more preferably 0.5 or less, and still more preferably 0 or less.
The spacer is preferably made of glass.
Preferably, a conductive film is formed on at least a main surface of the spacer in contact with the magnetic disk.
Another embodiment of the present invention relates to a hard disk drive device including the above spacer.
In this case, the hard disk drive device preferably mounts 8 or more magnetic disks.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the spacer and the HDD device described above, when the magnetic disk and the spacer are extracted from the HDD device as needed, the extraction failure of the spacer by the gripping jig can be suppressed.
Drawings
Fig. 1 is an external perspective view of a spacer according to an embodiment.
Fig. 2 is a diagram illustrating the arrangement of the spacer and the magnetic disk according to one embodiment.
Fig. 3 is a main sectional view illustrating an example of the structure of the HDD device with a spacer incorporated therein according to the embodiment.
Detailed Description
The spacer of the present invention will be described in detail below.
Fig. 1 is an external perspective view of a
As for the
As shown in fig. 2, the
The
The inner
The
Here, Ra, Rz, skewness, which will be described as surface roughness parameters hereinafter, are in accordance with JIS B0601-2001. Ra is arithmetic mean roughness and Rz is maximum height. The surface roughness is calculated from data measured by a stylus surface roughness meter using a stylus, for example. Note that a stylus having a tip radius of curvature of 2 μm and a cone angle of 60 ° may be used as the stylus. As for other measurement/calculation parameters, the measurement length may be 80 μm, the measurement resolution (pitch) may be 0.1 μm, the scanning speed may be 0.1 mm/sec, the sampling length value (Ls) of the low-pass filter may be 2.5 μm, and the sampling length value (Lc) of the high-pass filter may be 80 μm.
In the case of measuring the surface roughness parameter using a stylus, the stylus scans in the thickness direction of the
As the value of the surface roughness parameter, for example, 5 measurements may be performed on the surface of the portion to be evaluated, and the average value of the obtained 5 values may be used.
The outer
The reason why the surface roughness Rz of the outer
When the surface roughness Rz is larger than 20 μm, the surface of the holding jig is ground by the surface irregularities of the outer
When the surface roughness Rz is less than 2.0 μm, even if the drawing fails, particles may be generated due to strong friction during drawing. Therefore, Rz is more preferably 2.0 μm or more.
According to one embodiment, the outer
The groove width is preferably 10 μm or more on average in terms of ensuring a friction force so that no failure in extraction occurs. On the other hand, if the groove is too large, burrs are likely to be generated on the convex ridge lines between the grooves. As described in detail later, when the burr is present, particles are likely to be generated during the holding. Therefore, the groove width is preferably 300 μm or less on average. The average value of the groove width can be roughly calculated from the number of grooves in a range of a predetermined length in the thickness direction of the outer
For the purpose of preventing the
According to one embodiment, the skewness Sk, which is a parameter for determining the shape of the surface irregularities of the outer
When the groove (streak) is formed on the outer
The skewness Sk is a parameter obtained by dividing the cubic average of the measurement data of the surface roughness by the cube of the root-mean-square height of the measurement data of the surface roughness and performing dimensionless transformation. The skewness Sk is evaluated for the target of the projection shape and the valley shape of the surface roughness, and has a positive value and a negative value, and a positive value of the skewness Sk indicates a surface irregularity in which the steeper projection shape is larger and the shallower valley shape is larger, and a negative value of the skewness Sk indicates a surface irregularity in which the steeper valley shape is larger and the smoother projection shape is larger.
By providing the surface irregularities having the skewness and the surface roughness Rz within the predetermined ranges, the frictional force between the gripping jig of the mounting apparatus and the outer
According to one embodiment, a conductive film such as a metal film is preferably formed on the surface of the
When the conductive film is formed on the
The thickness of the conductive film is preferably such that the conductive film has an electrical conductivity that allows static electricity to escape to the outside, and is, for example, 0.01 to 10 μm. When such a conductive film is formed on the outer
Such a
The
In this case, it is preferable to use glass having a coefficient of thermal expansion substantially equal to that of the glass substrate of the
The raw material of the
The method of grinding and/or polishing the end face is not particularly limited, and grinding or polishing can be performed using, for example, a shaped grindstone (Gross-shaped grindstone) containing diamond abrasive grains of #80 to # 1000.
The diamond abrasive grains may be fixed to the grindstone using metal or resin. The end face polishing may be performed using a polishing brush provided with a bristle material such as nylon. These end face processing can be performed by bringing the ring-shaped glass as a workpiece before the
When the groove in the circumferential direction is formed, burrs may be generated on the ridge line of the projection between the grooves. In particular, the roughness increases with the formation of larger grooves, and burrs are more likely to be generated. In the grinding process using the formed grindstone, the time for which the pressing force of the grindstone is zero is set at the final stage of the process, and the pressing force is reduced or the time for which the pressing force is applied is shortened in the brush polishing, or a soft brush is used, whereby the burrs can be removed appropriately while maintaining the overall groove shape. In the case of forming the groove, it is preferable that the groove is roughly formed by grinding with a mold grindstone, and then the groove shape is finely finished by end face grinding. However, if the end face grinding is excessively performed, the grooves may be ground off, and thus care is required. Note that the degree of flash has a strong correlation with the skewness Sk in the surface roughness parameter. The larger the size of the burr and the higher the frequency of occurrence of the burr, the more the skewness Sk tends to increase. Thus, the skewness Sk can be controlled by optimizing grinding and polishing while observing the value of the skewness Sk.
In addition, chemical polishing may also be performed using an etching solution containing hydrofluoric acid or fluorosilicic acid.
By appropriately combining these grinding methods and polishing methods, an outer peripheral end face having a desired surface shape can be formed.
After grinding and/or polishing the outer
The size of the
(Experimental example)
In order to confirm the effect of the
The abrasive grain size of the formed grindstone was changed in order to produce various surface irregularities on the outer
The spacers of
The specification of Rz of the outer peripheral end face of the spacer made of glass and the evaluation results thereof are shown in table 1 below.
In addition, after 10 assembly and removal operations, particles adhering to all disk surfaces were counted by visual observation using a spotlight in a dark room. 4 grades of grade 1-4 were evaluated according to the number of particles. The smaller the grade, the smaller the particle count. Although the
Grade 1: the number of particles is 0-5
Grade 2: the number of the particles is 6-10
Grade 3: the number of the particles is 11-15
Grade 4: the number of the particles is more than 16
The specification of Rz of the outer peripheral end face of the spacer made of glass and the evaluation results thereof are shown in table 2 below.
[ Table 1]
Rz [ mu ] m of peripheral end face]
Presence or absence of drawing
Sample
1
1
Is provided with
1.2
Is provided with
1.5
Is free of
Sample No. 4
2.0
Is free of
Sample No. 5
2.5
Is free of
Sample No. 6
5
Is free of
Sample 7
10
Is free of
Sample 8
15
Is free of
Sample 9
20
Is free of
25
Is free of
Sample 11
30
Is free of
[ Table 2]
Rz [ mu ] m of peripheral end face]
Number of
Sample
3
1.5
Sample No. 4
2.0
Sample No. 5
2.5
Sample No. 6
5
Sample 7
10
Sample 8
15
Sample 9
20
25
Sample 11
30
The manufactured spacers of
The main surfaces of the magnetic disks before the start and after the completion of 10 operations were scanned by a laser type surface defect analyzing apparatus, and the particles increased by taking the difference were counted. For groups (
Grade A: the index is 100% or less.
Grade B: the index is more than 100-110%.
Grade C: the index is more than 110-130%.
Note that, even in the level C, the level can be used without any problem in practical use.
Table 3 shows the specifications of Rz and skewness Sk on the outer peripheral end face of the spacer and the evaluation results thereof.
[ Table 3]
Rz [ mu ] m of peripheral end face]
Skewness Grade
Sample
12
20
1.5
C
Sample 13
20
1.2
Sample
14
20
0.5
B
Sample 15
20
0.0
(Standard)
20
-1.0
A
Sample 17
10
1.5
C
Sample 18
10
1.2
B
Sample 19
10
0.5
B
Sample 20
10
0.0
(Standard)
Sample 21
10
-1.0
A
Sample 22
2.0
1.5
C
Sample 23
2.0
1.2
B
Sample 24
2.0
0.5
B
Sample 25
2.0
0.0
(Standard)
Sample 26
2.0
-1.0
A
As is clear from table 1, the spacer can be reliably extracted by setting the surface roughness Rz of the outer peripheral end face to 1.5 μm or more.
As is clear from table 2, it is preferable to reduce the number of particles by setting the surface roughness Rz of the outer peripheral end face to 20 μm or less, from the viewpoint of securing the long-term reliability of the HDD device.
As is clear from table 3, it is preferable to reduce the number of particles by setting the skewness Sk to 1.2 or less, from the viewpoint of ensuring the long-term reliability of the HDD device. It is also found that the skewness Sk is more preferably 0 or less.
In
Although the spacer and the hard disk drive device of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and examples, and it is needless to say that various improvements and modifications can be made without departing from the scope of the present invention.
Description of the symbols
1 spacer
2 peripheral end face
3 inner peripheral end face
4 major surface
5 magnetic disk
10 hard disk drive device
12 electric machine
14 spindle
16 upper end chuck
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