JP2000002249A - Roller bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend a service life and restrain an increase in a production cost as much as possible. SOLUTION: At a surface of a roller bearing on which a coating film 31 is formed, a liquidous substrate layer 30 is formed to improve the affinity between the film 31 and the surface. The film 31 is composed of fluoro-contained polymer having a functional group and is formed on at least a truck surface of a surface of the bearing. The layer 30 is provided at a portion below the film 31 and brought into contact with the film 31 so as to improve the affinity.

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, there is a problem that the manufacturing process is complicated by the addition of the ultrasonic vibration to the base material, and the manufacturing cost is increased 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 liquid 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, in the rolling bearing according to the first aspect, the underlayer is made of Si-
It is composed of a polymer material film having OH as a functional group.

With the above arrangement, 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.

[0014]

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 information equipment. 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 rotation center 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 projecting below the frame 1, and a stator (coil) 10 arranged below the rotor 9 in a non-contact and opposed 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 underlayer 30 made of a liquid layer 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). Is formed, and further, the underlayer 30 is formed.
On which a film 3 made of a fluoropolymer having a functional group is formed
1 is formed in a state having fluidity. Underlayer 30
Is made of a liquid material having a high affinity for the coating film 31, so that the coating film 31 can be easily attached to the underlayer 30 in the form of a film. The base layer 30 is made of a material having a high affinity for the base material, and is easily formed in a film on the base material.

The film 31 (including the underlayer 30) is
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
In addition to those mainly composed of silicon nitride (Si ₃ N ₄ ) using O ₄ ), alumina (Al ₂ O ₃ ), silicon carbide (SiC),
Zirconia (ZrO ₂ ), aluminum nitride (AlN), or the like can be used.

The retainer 25 is formed 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 protective film of the information recording disk 2 described above. 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 relatively high affinity for metals (for example, epoxy group, amino group, carboxyl group, hydroxyl group, mercapto group, isocyanate group, sulfone group or ester group). ,
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.

[0031]

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[0032]

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[0033]

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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 Ausimond 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 improves the affinity between the coating 31 and the base material, and has a high affinity for the coating 31 and the base material. It is composed of a liquid material. As a material of the underlayer 30 having such properties, specifically, there is GALDEN MF407 (trade name) manufactured by Ausimond.

In this embodiment, the underlayer 30 is a layer made of a material having a high affinity for both the coating 31 and the base material. If it is made of a material with high affinity for
As a result, the coating 31 becomes easily compatible with the underlayer 30.
It is possible to obtain effects such that film formation is facilitated and film breakage is less likely to occur.

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, an underlayer 30 having a high affinity for the coating 31 and the base material (the outer peripheral surface of the inner race 22, the inner peripheral surface of the outer race 23, the surface of the rolling elements 24, and the surface of the cage 25) is obtained. A solution is prepared, and the inner and outer rings 22, 2 are contained in the solution.
3. By immersing the rolling elements 24 and the retainers 25 individually or by immersing the rolling bearings 16 in an assembled state and rotating them several times,
2. Underlayer 3 on outer ring 23, rolling element 24 and cage 25
0 is attached (underlayer adhesion treatment).

Then, the entire rolling bearing 16 to which the underlayer 30 has been adhered is heated at 40 to 50 degrees Celsius for about 3 minutes to remove the solvent contained in the underlayer 30. Thus, the underlayer 30 having a thickness of about 0.5 μm is formed. (Underlayer drying treatment).

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

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 and the cage 24, on which the underlayer 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).

The solution prepared for the coating is, for example, FOMBLIN Z in a suitable diluting solvent (fluorine solvent SV9).
In 0), the fomblin concentration was diluted to 0.25 to 1.0 mass%.

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

In the structure and manufacturing method of the rolling bearing 16, a special treatment is performed by forming an underlayer 30 for improving the affinity between the coating 31 and the base material under the coating 31. Instead, the coating 31 can be formed on the base material (specifically, on the underlayer 30) in a state where the coating 31 is sufficiently adapted, and the manufacturing process is correspondingly simplified. In addition, since the base layer 30 can be formed only by immersing the base material in the material liquid of the base layer 30, the manufacturing process does not become complicated despite the newly added base layer 30.

Further, since the film 31 is formed in a state in which the film 31 is sufficiently adapted to the lower layer, partial film breakage due to rotation of the rolling element 24 which promotes abrasion of the base material is less likely to occur. 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.

Furthermore, 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 can be easily adapted to the base material. As a result, it is possible to reduce the thickness of the coating 31 that can obtain sufficient lubrication. Therefore, the coating 31
Since the film thickness can be reduced, dust generation factors are reduced and environmental pollution is less likely to occur.

When the base layer 30 or the coating 31 is to be locally adhered, unnecessary portions may be masked and immersed in the respective solutions or sprayed with the solutions.
Alternatively, the respective solutions may be injected into the locations where the rolling elements 24 exist between the inner and outer rings 22 and 23 by using a dropper or the like.

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.

With the above arrangement, it is possible to form the coating 31 at a suitable thickness on the parts of the rolling bearing 16 which are in contact with each other, and to remove the solvent 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 a fluidity because the functional group of the fluoropolymer adheres firmly to the surface to be adhered (the surface of the rolling bearing), but it is difficult for the film to be cut or dusted. 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, so that a minute spike noise unlike the related art is not 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.

Note that 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, it is possible to form a film with the coating being sufficiently adapted to the raceway surface without complicating the manufacturing process, thereby extending the life of the rolling bearing. Can be realized while minimizing the increase in manufacturing cost.

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.

[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 element 25 Cage 26 Seal 30 Base layer 31 Coating

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference)

Claims (2)

[Claims] 1. A rolling bearing having a coating made of a fluorine-containing polymer having a functional group formed on at least a raceway surface of a bearing surface, wherein a coating-forming surface of the bearing has a lower layer side than the coating. A rolling bearing, characterized in that a liquid underlayer for improving the affinity between the coating and the coating-forming surface is provided at a portion in contact with the coating. 2. The rolling bearing according to claim 1, wherein the underlayer is a polymer material film having Si—OH as a functional group.