JP2000009147A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the service life of a rolling bearing in the state of suppressing the rise of manufacturing cost to a minimum by providing a coat of formed face of the bearing with a solid substrate layer for improving affinity between a coat and a coat formed face of the bearing, at a part in contact with the coat on the lower layer side than the coat. SOLUTION: A solution for obtaining coats 31 formed of a fluorine contained polymer with a functional group is prepared, and inner and outer rings 22, 23, a rolling element 24 and a cage 25 with substrate layers 30 already formed the individually dipped in this solution, but a rolling bearing 16 in the assembled state of these components is dipped and rotated several times to stick the coats 31 to the inner ring 22, outer ring 23, rolling element 24 and cage 25. The substrate layers 30 positioned in the lower layers of the coats 31 has affinity for the coats 31, so that the coats 31 can be formed concordantly with the substrate layer 30. Since the coats 31 are formed in a state of being fully concordant with the lower layers, partial coat break caused by the rotation of the rolling element 24 accelerating the wear of base material is hardly occurred.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing and, more particularly, to a rolling bearing most suitable for use in a vacuum environment, a clean environment, a corrosive environment, and the like where ordinary grease and oil cannot be used.

[0002]

2. Description of the Related Art As information equipment, there are provided a rotation mechanism such as a spindle shaft which is fixed through the center of rotation of an information recording disk, and a swing mechanism such as a swing arm for moving a head for recording and reproducing information. There is something. In such information equipment, for example, Japanese Patent Application Laid-Open
As shown in an information device described in JP-A-135515, a swing fulcrum shaft of a swing arm provided as a swing mechanism is supported by two radial rolling bearings.

[0003] The above-mentioned rolling bearing has the following disadvantages. That is, among the rotating mechanism or the swing mechanism, for example, in a rolling bearing used to support a swing arm as a swing mechanism, the swing arm is a movement that swings repeatedly within a predetermined angle range. In a rolling bearing to be supported, the rolling element may be dragged and slipped. Therefore, no matter how much lubricant is interposed between the rolling element and the bearing ring, the film of the lubricant is easily cut. Such breakage of the lubricant film causes direct contact between the rolling elements and the races, causing wear of the rolling elements and the races.

[0004] Further, if a large particle size is mixed in the interposed lubricant, a minute spike noise is generated from the rolling bearing, and the torque characteristic for the swinging motion of the swing arm becomes unstable. This is disadvantageous in that the head positioning accuracy during recording / reproducing is reduced.

[0005] Furthermore, leakage of the lubricant may occur, and if the leaked lubricant adheres to the surface of the information recording disk and is taken into the protective film of the information recording disk,
There was a problem that recording and reproduction were hindered.

On the other hand, the applicant of the present invention has disclosed in
As described in Japanese Patent Application Laid-Open No. 226446, for example, a coating made of a fluorine-containing polymer having a functional group is formed on at least the raceway surface of the bearing surface, and the coating functions as a lubricant. A rolling bearing that eliminates the problem has been proposed.

[0007]

However, a rolling bearing having a coating made of a fluorine-containing polymer having a functional group formed on at least the raceway surface of the bearing surface has the following problems. That is, when a metal or ceramic is used as a base material (an inner ring, an outer ring, a rolling element, or a cage) for forming a coating, the coating does not have a good affinity for the base material. , The coating (lubricant) is partially cut by the rotation of the rolling elements, and the wear of the base material is accelerated.
As a result, the durability performance of the rolling bearing was deteriorated.

On the other hand, the above-mentioned coating is formed in a state where ultrasonic vibration is applied to the base material and the coating raw material (for example, in a state where ultrasonic vibration is applied to the storage tank of the coating raw material liquid). By immersing the base material in the storage layer), it is conceivable to form a film by sufficiently adapting the coating to the base material having low affinity, thereby solving the above-mentioned inconvenience. However, it is necessary to newly provide a troublesome and effective device (ultrasonic vibration generating device) to the extent that ultrasonic vibration is newly added to the base material, and there has been a problem of increasing the manufacturing cost accordingly.

Accordingly, it is an object of the present invention to realize a longer life of a rolling bearing while minimizing an increase in manufacturing cost.

[0010]

The present invention achieves the above-mentioned object by the following means.

According to the first aspect of the present invention, the coating made of a fluoropolymer having a functional group is a rolling bearing formed on at least the raceway surface of the bearing surface, and the coating forming surface of the bearing is formed on the rolling bearing surface. A feature is that a solid underlayer for improving the affinity between the film and the surface on which the film is formed is provided below the film and in contact with the film.

According to a second aspect of the present invention, there is provided the rolling bearing according to the first aspect, wherein the underlayer is a film containing carbon as a main component.

According to a third aspect of the present invention, there is provided the rolling bearing according to the first or second aspect, wherein the underlayer has a multilayer structure.

By providing the above-described structure, the present invention has an effect that the coating can be formed in a state in which the coating is sufficiently adapted to the raceway surface without complicating the manufacturing process.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a longitudinal sectional view of a hard disk drive according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a half of a rolling bearing of the moving unit of FIG.

In FIG. 1, A indicates the entire hard disk drive as an information device. The components of the device will be described with reference to FIG. 1. 1 is a frame of the hard disk drive A, 2 is an information recording disk such as a magnetic disk or an optical disk disposed in a horizontal position inside the frame 1, 3 is an information recording disk 2 on the frame 1
A recording / reproducing head for recording / reproducing information on / from the information recording disk 2; and a moving unit 5 for moving the recording / reproducing head 4 to an arbitrary track of the information recording disk 2. Unit.

On the surface of the information recording disk 2, a protective film (not shown) is formed in a state having fluidity.
This protective film is generally made of perfluoropolyether (PFPE).

The spindle unit 3 has a spindle shaft 6 penetratingly fixed so as to protrude vertically from the center of rotation of the information recording disk 1, and a vertically protruding portion of the spindle shaft 6 rotatably with respect to the frame 1. The information recording disk 2 includes a pair of supporting rolling bearings 7 and 7 and a motor 8 for rotatingly driving the information recording disk 2.

The motor 8 includes a rotor (permanent magnet) 9 fixed to a lower end of the spindle shaft 6 protruding below the frame 1, and a stator (coil) 10 disposed below the rotor 9 in a non-contact manner. It is composed of Stator 1
Reference numeral 0 denotes a yoke 13 attached to a base 11 via an elastic body 12 such as a coil spring that resiliently urges the frame 1.

The moving unit 5 includes a swing arm 14 to which the recording / reproducing head 4 is attached, a head carriage shaft 15 fixed to the frame 1, and a head carriage shaft 1.
5 includes a pair of rolling bearings 16, 16 for swingably supporting the swing arm 14, and a motor 17 for swingably driving the swing arm 14.

The motor 17 includes a rotor (permanent magnet) 18 fixed to the lower end of the swing arm 14 and a stator (coil) 19 that is disposed below the rotor 18 in a non-contact and opposed manner.
It is composed of The stator 19 is attached to a yoke 21 mounted on the base 11 via an elastic body 20 such as a coil spring that elastically urges the frame 1.

As shown in FIG. 2, the pair of rolling bearings 16 provided in the moving unit 5 includes an inner ring 22, an outer ring 23, a spherical rolling element 24, a crown-shaped retainer 25, and a seal 26. And a deep groove type ball bearing.

Here, the solid underlayer 3 is formed on the outer peripheral surface of the inner race 22, the inner peripheral surface of the outer race 23, the surface of the rolling element 24, and the surface of the cage 25 (hereinafter collectively referred to as a base material).
0 is formed, and a coating 31 made of a fluoropolymer having a functional group is formed on the underlayer 30 in a state of having fluidity. The underlayer 30 is
It is made of a solid material having a high affinity for the coating 31, and it is easy to attach the coating 31 on the underlayer 30 in a film shape.

The coating 31 (including the base layer 30)
What is necessary is just to form in at least only the track surface of the inner / outer ring 22,23.

Here, the inner and outer races 22, 23 and the rolling elements 24 are formed of a metal material. Examples of the metal material include high carbon chromium bearing steel such as JIS SUJ2. If corrosion resistance is required,
A martensitic stainless steel such as JIS SUS440C, for example, a metal material obtained by subjecting a precipitation hardening stainless steel such as JIS SUS630 to an appropriate hardening heat treatment is preferable. For light-load applications, for example, austenitic stainless steel such as JIS SUS304 can be used. Note that the rolling elements 24 can also be formed of a ceramic material. As the ceramic material, as a sintering aid, yttria (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ), and other materials such as aluminum nitride (A
1N), titanium oxide (TiO ₂ ), spinel (MgAl ₂
O ₄₎ others mainly composed of silicon nitride (Si ₃ N ₄₎ with alumina (Al ₂ O ₃₎ or silicon carbide (Si
C), zirconia (ZrO ₂ ), aluminum nitride (AlN)
Etc. can be used.

The retainer 25 is made of a synthetic resin material in addition to mild steel such as SPCC material. Examples of the synthetic resin material include a general polyamide resin (nylon 66) and a heat-resistant thermoplastic resin such as polytetrafluoroethylene (hereinafter abbreviated as PTFE) and ethylenetetrafluoroethylene (ETFE). Engineering plastics such as fluororesin, polyetheretherketone (PEEK), polyphenylenesulfide (PPS), polyethersulfone (PES), and nylon 46 can also be used. As the type of the retainer, a corrugated type, a machined type, or the like may be arbitrarily used in addition to the illustrated crown type.

The coating 31 made of a fluorine-containing polymer having a functional group has the same kind of components as the above-mentioned protective film of the information recording disk 2. As the fluorinated polymer, a fluoropolyether polymer or a polyfluoroalkyl polymer is preferable.

The fluoropolyether polymer is represented by —C _X F
A unit represented by the general formula _2X- O- (X is an integer of 1 to 4) is defined as a main structural unit, and each has a number average molecular weight of 10
Polymers having a molecular weight of 00 to 50,000 are exemplified.

Examples of the polyfluoroalkyl polymer include those represented by the following chemical formula 1.

The above-mentioned functional groups are preferably those having a relatively high affinity for metals (for example, epoxy groups, amino groups, carboxyl groups, hydroxyl groups, mercapto groups, isocyanate groups, sulfone groups or ester groups). ,
For example, those represented by the following chemical formulas 2 and 3 are exemplified. Such fluoropolymers may be used alone or in combination of two or more. In that case, it is desirable to consider that the combined groups react with each other to make the polymer higher in molecular weight so that a thin film having more excellent wear resistance is obtained.

[0032]

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[0033]

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[0034]

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More specifically, as the coating film 31, a mixture with perfluoropolyether (PFPE) or a derivative thereof, specifically, for example, a product name FOM manufactured by Audimond Co., Ltd.
BLIN-Z-DOL2000, FOMBLIN-Z-DOL4000, FOMBLIN-Z-DEAL4
000, FOMBLIN-Z-DIAC, etc. are preferably used. These examples all have a high concentration and an extremely low affinity for metals, and therefore, it is difficult to attach them as a film as they are. Then, the coating 31 is coated on the base material (the inner ring 2).
The base layer 30 is previously formed on the surface of the base material in order to securely adhere to the outer peripheral surface of the base member 2, the inner peripheral surface of the outer race 23, the surface of the rolling element 24, and the surface of the cage 25.

As described above, the underlayer 30 is for improving the affinity between the coating 31 and the base material, and is made of a solid material having a high affinity for the coating 31. As the underlayer 30 having such properties, there is a film containing carbon as a main component. In the present embodiment, the underlayer 30 is formed from a carbon film. The underlayer 30 may be a diamond-like carbon film other than the carbon film.

Next, the underlayer 30 and the coating 31 described above are formed.
An example of a method for forming the film will be described.

First, the base layer 30 made of a carbon film is applied to the coating 31 and the base material (the outer peripheral surface of the inner ring 22, the inner peripheral surface of the outer ring 23, the surface of the rolling element 24, and the surface of the cage 25).
To form The thickness of the underlying layer 30 to be formed is suitably 1 μm or less. Such an underlayer 30 is formed by, for example, sputtering.

Next, a solution for obtaining a coating 31 made of a fluorine-containing polymer having a functional group is prepared, and the inner and outer rings 22, 23, the rolling elements 24, the cage 24, and the retainer 30 on which the base layer 30 has been formed are prepared in this solution. The coating 31 is adhered to the inner ring 22, the outer ring 23, the rolling elements 24 and the retainer 25 by immersing the rolling bearings 25 individually or by immersing the rolling bearings 16 in a state where they are assembled and rotating them several times. (Coating treatment). At this time, since the underlayer 30 located below the coating 31 has an affinity for the coating 31,
The coating 31 is formed with good conformity to the underlayer 30.

The solution prepared for the coating is, for example, FOMBLIN Z DOL2000 (of a molecular weight of 2) of FOMBLIN Z DOL.
000) with an appropriate diluting solvent (fluorinated solvent SV9)
0D) to increase the fomblin concentration from 0.25 to 1.0 mass%
It was diluted to.

The entire rolling bearing 16 to which the liquid film is adhered is heated at 40 to 50 degrees Celsius for about 3 minutes to remove the solvent contained in the liquid film (drying treatment).

Thereafter, in consideration of the ambient temperature in the environment in which the bearing is used, heating is performed, for example, at 120 to 180 degrees Celsius for 15 to 60 minutes (finish drying treatment).

In the structure and manufacturing method of the rolling bearing 16, a relatively simple and expensive device for forming the underlayer 30 having a high affinity with the coating 31 under the coating 31 is not required. Just by adding a process, coating 3
1 can be sufficiently blended with the base material. for that reason,
The increase in manufacturing cost due to the step of newly adding the coating 31 (the step of forming the underlayer 30) is minimized.

Further, since the film 31 is formed in a state in which the film 31 is sufficiently adapted to the lower layer, the film is less likely to be partially cut due to the rotation of the rolling element 24 which promotes abrasion of the base material. I have. Further, even if the coating film is partially cut off, the underlayer 3 is located between the rolling element 24 and the raceway surface.
Since 0 is interposed, the rolling element 24 does not directly contact the raceway surface, and the rolling element 24 and the raceway surface are hardly worn.

Further, the coating 3 located on the outermost layer of the base material
When 1 is separated from the base material by the rolling operation of the rolling element 24, it becomes dust, which is inconvenient when the bearing is used in a clean environment. However, in this rolling bearing 16, the underlayer 3
By providing 0, the coating 31 was easily adapted to the base material, and as a result, the thickness of the coating 31 capable of obtaining sufficient lubrication could be reduced. Therefore, as the film thickness of the coating film 31 becomes thinner, the factor of dust generation is reduced and environmental pollution is less likely to occur.

When the underlayer 30 or the coating 31 is locally formed, the underlayer 30 or the coating 31 is formed by masking unnecessary portions and then forming the underlayer 30 or the coating 31.
Can be formed locally without forming unnecessary portions.

Further, the above-mentioned coating adhesion processing and coating drying processing may be repeated several times as necessary, and finally, the thickness of the coating 31 is set to, for example, 0.2 μm or less. However, the properties of the solution to be used, the method of forming the thin film, the thickness of the film after formation, and the like may be appropriately set.

As described above, it is possible to form the coating 31 with a suitable film thickness on the parts that come into contact with each other in the components of the rolling bearing 16, and if the solvent is removed as described above. In addition, unnecessary dust generation during the operation of the rolling bearing 16 is eliminated. Further, since the thickness of the coating film 31 can be set extremely small, dust generation due to the oil component is almost eliminated.

The coating 31 has fluidity because the functional group of the fluoropolymer adheres firmly to the surface to be adhered (the surface of the rolling bearing). And the frictional resistance is extremely small. In addition, the coating 31 has the same type of components as a protective film (not shown) attached to the information recording disk 2, and these coatings 31 and the protective film have a non-uniform particle size like a conventional fluorine-based grease. Contains no thickener or ions for homogenous dispersion of the thickener.

As a result, the operation of the rolling bearing 16 for supporting the recording / reproducing head 4 becomes extremely smooth, and no minute spike noise as in the prior art is generated. Record
The positioning accuracy of the reproducing head 4 is improved. Further, even if the dust component from the coating 31 is incorporated into the protective film of the information recording disk 2, since the protective film of the information storage disk 2 and the dust component of the coating 31 are the same component, It does not hinder the recording and reproduction of information on the recording disk 2.

In the embodiment described above, the underlayer 3
0 has a single-layer structure, but as shown in FIG. 3, an underlayer 3 having a multilayer structure in which a lower layer 30a and an upper layer 30b are laminated.
It may be 0 '. In this case, a new effect of improving the adhesive force and the abrasion resistance can be obtained. Further, the underlayer 30 may have a multilayer structure of three or more layers.

The present invention is not limited to the above embodiment, and various applications and modifications are conceivable.

(1) The rolling bearing of the present invention can be applied not only to the hard disk drive described in the above embodiment but also to a rolling bearing incorporated in a device having a precision rotation mechanism. .

(2) In the above embodiment, a deep groove ball bearing is cited as the rolling bearing 16 for supporting the swing arm of the moving unit 5. However, the present invention can be applied to various types of rolling bearings. it can.

(3) In the above embodiment, the base layer 30 and the coating 31 are formed on the rolling bearing 16 for supporting the swing arm of the moving unit 5, but the rolling bearing 7 of the spindle unit 3 is similarly formed. The underlayer 30 and the coating 31 may be formed. In this case, it is possible to contribute to improvement of the rotation accuracy of the information recording disk 2.

[0056]

As described above, according to the present invention, a film can be formed in a state in which the film is sufficiently adapted to the raceway surface without using a troublesome and expensive device, so that the rolling bearing has a long service life. This was achieved while minimizing the increase in manufacturing costs.

Further, since the film can be formed in a state in which the film is easily conformable, the film thickness capable of obtaining sufficient lubrication can be reduced. Therefore, as the film thickness can be reduced, dust generation factors are reduced and environmental pollution is less likely to occur.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a configuration of a hard disk drive device incorporating a rolling bearing according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration of the rolling bearing according to the embodiment.

FIG. 3 is a cross-sectional view illustrating a configuration of a rolling bearing according to a modified example of the present invention.

[Explanation of symbols]

A Hard Disk Drive 1 Frame 2 Information Storage Disk 3 Spindle Unit 4 Recording / Reproducing Head 5 Moving Unit 6 Spindle 7 Rolling Bearing 8 Motor 9 Rotor 10 Stator (Motor 8) 11 Base 12 Elastic Body (Yoke 13) 13 Yoke 14 Swing arm 15 Head carriage shaft 16 Rolling bearing 17 Motor 18 Rotor 19 Stator 20 Elastic body 21 Yoke 22 Inner ring 23 Outer ring 24 Rolling body 25 Cage 26 Seal 30 Underlayer 30 'Underlayer 30a Lower layer 30b Upper layer 31 Coating

Continued on the front page F term (reference) 3J101 AA01 AA32 AA62 AA63 BA55 CA15 CA33 CA34 DA05 EA03 EA06 EA33 EA36 EA37 EA42 EA43 EA44 EA47 EA78 FA31 FA44 GA53 5D068 AA01 BB01 CC12 EE19 GG21 5B109 BB15 BB15 BB15 BB15

Claims (3)

[Claims] 1. A rolling bearing in which a coating comprising a fluoropolymer having a functional group is formed on at least a raceway surface of a bearing surface, wherein a coating forming surface of the bearing is on a lower side of the coating. A solid underlayer for improving the affinity between the film and the surface on which the film is formed is provided at a portion in contact with the film. 2. The rolling bearing according to claim 1, wherein the underlayer is a film containing carbon as a main component. 3. The rolling bearing according to claim 1, wherein the underlayer has a multilayer structure.