JP2000205267A - Rolling bearing for information business equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing for information business equipment which has low torque, low torque variation, and excellent resistance against frettiong while it maintains a very high cleanness and a long lifetime (durability) in high speed operation. SOLUTION: A rolling bearing for information business equipment is equipped with rollers furnished at the surface with a dimple of 0.2-20 μm in diameter to serve as an oil sump and/or raceway rings whose raceway has a center line main roughness of 0.05-0.3 μm and uses a lubricating oil having a dynamic viscosity at 40 deg.C of 10-500 mm2/s or a lubricant consisting of a base oil. The lubricant is stored in the dimple of balls or on the raceways, and thereby rotational swings or raised torque likely in the conventional arrangement can be eliminated, and the lifetime in high speed operation can be prolonged and also a very high cleanness be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing for information office equipment, and more particularly to a laser beam printer (LB).
The present invention relates to improvements in rolling bearings used for information office equipment such as P) and polygon scanner motors of digital copiers, microprocessor unit motors of computers, actuators of magnetic disk drives (HDDs) and spindle motors.

[0002]

2. Description of the Related Art A common requirement for rolling bearings used in these information and office equipment is that an atmosphere of extremely high cleanliness can be maintained. For example, LB
For P mirrors, HDD heads, electronic computer parts, etc.
This is because if the lubricant evaporates or scatters from the rolling bearing and becomes a foreign substance and adheres, the sharpness of characters deteriorates and data writing / reading errors occur. Rolling bearings for information and office equipment have durability and durability that can maintain good vibration and acoustic characteristics even after long-term use.
Long life and low noise characteristics are also required. Further, it is also required that the torque is small, the fluctuation is small, and rotation unevenness, rotation runout and the like can be suppressed.

To meet such demands, rolling bearings made of ceramic rolling elements have been proposed. As this type of prior art, for example, Japanese Utility Model Publication No. 6-26742
Patent Document 2 (Patent Document 1)
728181 (conventional example 2). The former is a rolling bearing used for a fan motor for cooling an optical device or the like, and a rolling element in contact with steel inner and outer rings is made of ceramic. As a result, the amount of filled grease is reduced to 5 to 10 times the space volume between the inner and outer rings.
% And about 1/4 of the normal value, and sealing with a sealing plate is performed to prevent contamination of the lens of the optical system due to scattering of grease.

On the other hand, the latter is a rolling bearing for an LBP polygon scanner motor. The rolling element is formed of a ceramic material so that the raceway surfaces of the inner and outer rings and the surface of the rolling element are less likely to be roughened. In addition, the bearing life is increased, and good vibration characteristics and acoustic characteristics can be maintained even when used for a long time. This is because, in a normal ball bearing, small projections between the raceway surface of the bearing ring and the rolling element surface are liable to be fused by metal-metal contact at the rolling contact portion, so that the contact surface is easily worn. The life of the bearing is increased by making the contact portions of both of them ceramic-metal contact less likely to cause fusion wear.

[0005] Grease lubrication is used for lubricating the rolling bearings of Conventional Example 1 and Conventional Example 2. The biggest advantage of grease lubrication is that the sealing device is simpler,
However, oil lubrication is far superior in terms of lubrication performance. In particular, in the case of a laser beam polygon scanner motor, rotational fluctuation or uneven rotation affects the scanning performance of a laser beam. Therefore, high rotational accuracy and good friction torque performance (suppression of temperature rise) are required. Oil lubrication is more preferable because it can withstand the vibration and lower the bearing vibration and sound.

As an advantage that oil lubrication is superior to grease lubrication, the following literature also describes the following. The oil film thickness of grease lubrication is about 70% of the base oil viscosity, which is smaller than that of oil lubrication. In grease lubrication, much of the supplied grease is pushed out of the lubrication part, and at high speed, it is blown off by centrifugal force. Oil lubrication has a wider meniscus position and better lubrication efficiency than grease lubrication [Source: Author;
Ryo Aihara, Duncan Dowson, Lubrication Vol. 25, No. 4
No. (1980) pages 204 to 260 and No. 6 (1980) pages 379 to 286].

[0007]

In the case of Conventional Example 1, the amount of grease enclosed is set to 5 to 10% of the space volume,
It is to prevent environmental pollution in the equipment due to scattering of grease used for bearings, that is, to ensure cleanliness,
In the case of Conventional Example 2, the life of the roller bearing for the scanner motor can be increased by preventing the fusion wear, but since grease having a large torque change is used for the lubricant, There is a problem that it is difficult to sufficiently meet the demand for further improving the rotational fluctuation (torque fluctuation) and the friction torque performance (torque increase) of the high-speed rotation as compared with the related art.

As a countermeasure, it is conceivable to use lubricating oil instead of grease as a lubricant. However, when grease is simply changed to oil, the oil component involved in lubrication directly forms an oil film on the friction surface inside the bearing. Therefore, there is an advantage that the lubricating property is improved because of the low torque, but since the friction surface inside the bearing to which the lubricating oil is applied is smooth, it is difficult to store the lubricating oil on the friction surface. There is a problem that the lubricating oil runs out easily when used for a long time.

The present invention has been made in view of such problems of the prior art, and has a low torque and a low torque fluctuation while maintaining extremely high cleanliness and high-speed life (durability). It is an object of the present invention to provide a rolling bearing for information and office equipment having excellent fretting properties.

[0010]

Means for Solving the Problems The inventors of the present application have made the above mentioned
Ceramics used in conventional bearings
Since rolling elements are expensive, research and development are being conducted to reduce their cost.
In the process of _ThreeN_Four5 to the rolling element surface using
It was recognized that a depression of 12 μm had occurred. like this
The hollow is a defective product with conventional specifications
However, we checked the performance to make sure that it could be used.
Roller, better performance than without depression
Was. Therefore, the size at which the effect of this hollow appears
As a result of a study using data
I was able to identify something. In addition, this excellent property
It was found that the effect was due to the oil pool, and
A similar oil accumulation effect was found for the surface roughness.

Further, when this research was continued,
Bud is Si_ThreeN_FourNot limited to ZrO _Two, SiC, Al_Two
O_ThreeIt is clear that holds for
Series of parameters that vary the cavity diameter and lubricant viscosity using
Data test and the relationship with bearing performance
2. The results as shown in FIG. 3 were obtained. In addition, the oil
Regarding the effect of accumulation, when the material is ceramic balls,
Not only for cemented carbide, high-speed steel and normal bearing steel
We found that it could be used.

Further, in the bearing for a polygon scanner motor, good results obtained when a combination of a lubricating oil having a concave diameter of 0.2 to ²⁰ μm and a kinematic viscosity at 40 ° C. of 10 to 150 mm ² / s is obtained by using a microprocessor. It has also been found that a bearing for a unit and a bearing for a magnetic disk actuator can be similarly obtained. The present invention has been made based on these series of new facts.

That is, as will be described later, the inventors of the present invention have proposed a ball bearing for each application such as a polygon scanner motor of LBP, a microprocessor unit motor of a computer, an actuator motor of an HDD, etc. The present invention is made by summarizing a number of experiments by variously changing the depression and raceway surface roughness from the viewpoint of the effect that the "oil sump" has on the performance of the rolling bearing for information and office equipment. Reached. As mentioned above, the condition commonly required for information and office equipment is first the atmosphere with extremely high cleanliness.
For each equipment used, low torque, low torque fluctuation, durability, low noise, low dust generation, no fretting, etc. are required as the performance particularly required for the used bearing.

According to the present invention, when a rolling bearing containing a lubricant is used for an information office equipment requiring an extremely high cleanliness, the durability newly generated in order to secure the cleanliness. , Torque increase, torque fluctuation, fretting, etc. are intended to be solved by means different from the conventional one. FIG. 1 shows the relationship between the ball pit diameter and lubricating oil kinematic viscosity at 40 ° C. and bearing performance, FIG. 2 shows the relationship between raceway surface roughness and lubricating oil kinematic viscosity at 40 ° C. and bearing performance, and FIG. It is a summary of the results obtained by experiments on the relationship between the amount of the agent enclosed and the kinematic viscosity of the lubricating oil at 40 ° C. and the bearing performance, whereby the rolling bearing for information office equipment of the present invention which can satisfy the required performance is obtained. The characteristic range becomes clear.

That is, in order to achieve the above object,
The rolling bearing for information and office equipment according to the first aspect of the present invention has a rolling element provided with a recess having a diameter of 0.2 to 20 [mu] m on its surface and / or a raceway surface having a center line average roughness of 0.
With a raceway of 0.5 to 0.3 μm and 40 ° C.
Wherein a lubricant comprising a lubricating oil or a lubricating base oil having a kinematic viscosity of 10 to 500 mm ² / s is used.

Here, when the kinematic viscosity at 40 ° C. is 10 to 150 mm ² / s, the amount of the lubricant is 1% to 10% of the bearing space volume for oil lubrication, and the bearing space volume for grease lubrication. When the kinematic viscosity at 40 ° C. is 10 to 500 mm ² / s, both oil lubrication and grease lubrication can be 0.1% to less than 1% of the bearing space volume.

In particular, in the case of a deep groove ball bearing for a polygon scanner motor such as an LBP or a digital copier, the inner and outer rings are made of steel, and the balls are made of ceramics having a recess having a diameter of 0.2 to 20 μm on the surface. The lubricating oil having a kinematic viscosity at 40 ° C. of 10 to 150 mm ² / s can be applied to a friction surface in a bearing. In addition, if it is a rolling bearing for a microprocessor unit motor, its inner ring,
The outer ring is made of steel, the ball is made of ceramics having a depression of 0.2 to ²⁰ μm in diameter on its surface, and a grease containing a base oil of a lubricating oil having a kinematic viscosity at 40 ° C. of 10 to 150 mm ² / s is sealed. Things.

In the case of a rolling bearing for a head actuator of an HDD, in consideration of the fact that a lubricating oil film is difficult to be formed because of supporting the oscillating motion, the inner and outer rings are made of steel, and the ball has a diameter of 0 mm on its surface. Made of a ceramic having a depression of 2 to 20 μm, and the hardness of the ceramic is H
v1200 or more. Furthermore,
In a rolling bearing for a polygon scanner motor, a microprocessor unit motor, or a head actuator of an HDD, instead of using a ceramic ball having a depression having a diameter of 0.2 to 20 μm on its surface, an average of raceway surface center lines of inner and outer rings is used. Roughness 0.05-0.3μ
m and the kinematic viscosity at 40 ° C. of the lubricant is 10 to 15
A lubricating oil of 0 mm ² / s may be used.

The material of the ball at this time is not limited to ordinary bearing steel, but any material suitable for bearing rolling elements such as ceramics, cemented carbide, high-speed steel, etc. can be applied. As described above, the invention of the present application is to specify the pit diameter of the ball and the kinematic viscosity of the lubricating oil at 40 ° C., to define the raceway surface roughness and the kinematic viscosity of the lubricating oil at 40 ° C. Independently adopting at least one of the kinematic viscosities of the lubricating oil in the above, it is possible to secure the performance as a rolling bearing for information and office equipment, but it is particularly necessary to meet the content of the required performance. It is also possible to use any of the above-mentioned combinations in combination. For example, particularly when low dust generation is required, a further effect can be obtained by setting + or +. Also,
Especially when lubricating oil holding capacity is required, it is better to set to +, but when low dust generation is also required,
++ is more effective.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. First, as a first embodiment, L
A deep groove ball bearing for a polygon scanner motor such as a BP and a digital copying machine will be described. The following materials are used for components of the deep groove ball shaft for the polygon scanner motor. That is, for the inner ring and the outer ring, for example, steel such as bearing steel and martensitic stainless steel is used.

The balls include, for example, silicon nitride, zirconia,
Ceramics such as alumina and silicon carbide are used. For the retainer, a material having a lower specific gravity than steel or copper, such as a synthetic resin such as nylon or polyacetal, or a ceramic such as silicon carbide is used. The lubrication is oil lubrication. Examples of such lubricating oils include ester oils, synthetic hydrocarbon oils, ether oils, mineral oils, fluorine oils and the like.
A lubricating oil having a kinematic viscosity at 0 ° C. of 10 to 150 mm ² / s is used, and these are used alone or as a mixture. Such oil lubrication essentially has very little change in the torque of the bearing as compared with grease lubrication, so that there is no rotational fluctuation of the bearing.

The lubricating oil has a kinematic viscosity at 40 ° C. of 1
Since it is 0 to 150 mm ² / s, the bearing torque itself is very low. If the kinematic viscosity of the lubricating oil is less than 10 mm ² / s, the acoustic life of the bearing at high speeds will be short. On the other hand, 150 mm ² /
s, the bearing life is long and there is no run-out,
The bearing torque becomes too high. Therefore, the lubricating oil of the present embodiment has a kinematic viscosity at 40 ° C. of 10 to 150
It is specified in the range of mm ² / s.

Further, the ceramic ball of the ball bearing according to the present embodiment has a large number of depressions having a diameter of 0.2 to 20 μm (maximum diameter) formed on the surface thereof. FIG. 4 is a drawing of a microphotograph of a depression on the surface of a ceramic ball, and the size (diameter) of the depression is 0.2 to 2 μm. These depressions have a function of an oil reservoir for retaining the lubricating oil on the surface of the ceramic ball, so that the lubricating oil can be supplied for a long period of time and the bearing life can be prolonged. However, when the diameter is less than 0.2 μm, the effect of the oil sump is small. On the other hand, when the diameter exceeds 20 μm, the roughness and shape of the ball are deteriorated, resulting in a large sound and vibration value, which is unsuitable as a bearing for a polygon scanner motor. is there.

The lubricating oil of the present embodiment may further contain additives such as an antioxidant, a rust inhibitor, an antiwear agent, an extreme pressure agent, and a viscosity index improver. These may be any of known ones. Oil-lubricated ceramic ball deep groove ball bearings for polygon scanner motors can solve the problems of rotational runout and high torque associated with grease lubrication and can further extend the life at high speeds. (Examples) Hereinafter, the effects of the first embodiment of the present invention will be specifically described by comparative tests performed on examples and comparative examples. (A) Type of bearing used in the test: deep groove ball bearing (nominal number 695, dimensions are 5 mm inside diameter, 13 mm outside diameter, 4 mm width,
(Use of non-contact rubber seal) (b) Method of applying lubricating oil to bearing: The bearing was immersed in lubricating oil, then lifted up, and excess lubricating oil was removed with air. The amount of lubricating oil was set to 1% of the space volume in the bearing. (C) Test contents: c-1; Bearing durability test (acoustic test) Test apparatus: Bearing durability test apparatus shown in FIG. 5 A pair of upper and lower deep groove ball bearings (device under test) 2 mounted on the inner periphery of base 1 The rotation shaft 3 is supported via 2. A rotor 4 and a dummy mirror 5 are attached to the rotating shaft 3 so as to be integrally rotatable. Reference numeral 6 denotes a stator coil mounted on the outer periphery of the base 1, and 7 denotes a rotor magnet disposed on the inner periphery of the rotor 4. The lower ball bearing 2 is locked by a snap ring 8,
The upper ball bearing 2 is pressed by a preload spring 9 to apply a preload.

Bearing rotation speed: 20000 rpm (inner ring rotation) Axial load: 2 kgf Ambient temperature: 60 ° C. Criteria: After the bearing has been rotated for 3000 hours, the bearing is subjected to acoustic measurement using an Anderon meter, and Anderon before and after the bearing durability test The values were compared.

○: Anderon value 2.5 or less Pass ×: More than 2.5 Fail c-2; Torque test Bearing rotation speed: 9000 rpm Axial load: 2 kgf Temperature: Room temperature Judging criteria: Bearing torque value and torque fluctuation value It was measured.

Torque value ○: 8 × 10 ⁻³ N · m or less Pass ×: Over 8 × 10 ⁻³ N · m Fail Torque fluctuation value ○: 1 × 10 ⁻³ N · m or less Pass ×: 1 × 10 ^(-3 ) Test results: Test conditions and results of Examples 1 to 12 are shown in Table 1.

[0028]

[Table 1]

Table 2 shows the test conditions and results of Comparative Examples 1 to 13.
Shown in

[0030]

[Table 2]

FIG. 6 is a graph showing the results of an experiment performed on the ball bearing of Example 1 to determine the "relationship between the size of the hollow diameter of the ball and the acoustic, torque, and torque fluctuation values." From this figure, it can be seen that the size of the hollow diameter of the ball is 0.2 to 20.
It can be seen that it is better to define it in the range of μm. In FIG.
A graph of an experimental result for obtaining the “relationship between kinematic viscosity of lubricating oil and sound, torque value, and torque fluctuation value” performed on the ball bearing of Example 1 is shown. From this figure, it can be seen that the kinematic viscosity of the lubricating oil is 10
It can be seen that may be defined in the range of ~150mm ² / s.

As described above, according to the present embodiment, a deep groove for a polygon scanner motor is provided which eliminates rotational runout and high torque which have frequently occurred in the case of conventional grease lubrication and which has an extended life at high speed. It is clear that the ball bearing can be provided. Next, a rolling bearing for a microprocessor unit motor will be described as a second embodiment.

A microprocessor such as a personal computer is required to have low power consumption, high responsiveness, compactness, and the like. Accordingly, a rolling bearing used for a microprocessor unit motor incorporated in a personal computer is required to operate at high speed. It is required to maintain a long life and low noise while keeping the torque of the motor low. Conventional rolling bearings in this field use grease-filled steel bearings, but in the present embodiment, the inner and outer rings are made of steel, and the ball has a surface of 0.2 to 20 μm. It is made of hollow ceramics. The grease is sealed with a base oil having a kinematic viscosity of 40 ° C. and 10 to 150 mm ² / s.

The types of the steel material of the inner and outer rings and the ceramic material of the balls and the material of the retainer are the same as those described in the LBP ball bearing in the first embodiment. Examples of the lubricating base oil in grease as a lubricant include ester oil, synthetic hydrocarbon oil, ether oil, mineral oil and the like. The lubricating oil may contain a known oil such as an antioxidant seat, a rust preventive, and an oil agent, as long as the performance is not impaired. As the thickener, lithium stearate, lithium 12-hydroxystearate and the like are used.

The kinematic viscosity at 40 ° C. of the lubricant base oil is 10 m.
If it is less than m ² / s, the oil film thickness becomes thin and lubrication failure easily occurs, and the bearing life is shortened. On the other hand, when the kinematic viscosity is 15
If it exceeds 0 mm ² / s, the bearing torque becomes excessive. When lithium soap is used as the thickener, the sound of the bearing is very low and the life of the bearing is prolonged. The depression having a diameter of 0.2 to 20 μm on the surface of the ceramic ball causes an oil reservoir effect on the surface of the ceramic ball and can prolong the life of the bearing. However, if the diameter is less than 0.2 μm, the effect of the oil reservoir is small. On the other hand, if it exceeds 20 μm, the rolling surface (orbital surface) tends to be roughened, so that the life is shortened. Further, since the torque is not stable, the absolute value thereof is large, and the sound and vibration are large, it is not suitable as a rolling bearing for a microprocessor unit motor.

In the range of the hollow diameter of 0.5 to 15 μm, better durability life and lower torque characteristics were exhibited. (Examples) Hereinafter, the effects of the second embodiment of the present invention will be specifically described by comparative tests performed on examples and comparative examples. (A) Type of bearing used in the test: Deep groove ball bearing (No. 681X, dimensions are 1.5 m inside diameter)
m, outer diameter 4 mm, width 1.2 mm, Z seal used) (b) Grease filling amount in bearing: The filling amount of grease as a lubricant was 1% of the space volume in the bearing. (C) Test content: c-1; Torque test Test apparatus: The motor for the microprocessor unit shown in FIG. 8 was used for the bearing torque test. This motor is
Approximately the same configuration as the polygon scanner motor of the bearing durability test device shown in FIG. 5 (the same portions are denoted by the same reference numerals).
However, there is no dummy mirror 5 and a fan 10 is mounted on the outer periphery of the rotor 4 instead.

The torque was evaluated by measuring the number of revolutions at a constant voltage (30 V). Judgment criteria: ：: Revolutions of 6500 rpm or more Passed X: Revolutions of less than 6500 rpm Fail c-2: Bearing endurance test Test equipment: Same as the above torque test.

The rotation time at 6500 rpm or more at a constant voltage (30 V) was measured and evaluated. Atmospheric temperature 70 ° C Judgment criteria: １０: 10,000 hours or more Pass X: Less than 10,000 hours Fail (d) Test results: Table 3 shows test conditions and results of Examples 1 to 7 and Comparative Examples 1 to 7.

[0039]

[Table 3]

FIG. 9 is a graph showing the results of an experiment performed on the ball bearing of the first embodiment to determine the "relationship between the size of the hollow diameter of the ball and the number of revolutions and durability life". From this figure, it can be seen that it is better to define the size of the hollow diameter of the ball in the range of 0.2 to 20 μm. Hollow diameter 0.5-1
It is also clear that in the range of 5 μm, better low-torque characteristics and durability life can be obtained.

FIG. 10 is a graph showing the results of an experiment for obtaining the “relationship between the kinematic viscosity of the lubricating oil and the rotational speed and the durability life” performed on the ball bearing of the first embodiment. From this figure, 40 ° C
The kinematic viscosity of the lubricating base oil at 10 to 150 mm ² / s
It is understood that it is better to define the range as follows. As described above, according to the second embodiment, there is provided a rolling bearing for a microprocessor unit motor having improved life and torque at high speed compared to a conventional grease lubricated ceramic ball bearing. It is clear that the effect of being able to be achieved is achieved.

Subsequently, as a third embodiment, an HDD
The following describes the rolling bearing for an actuator. Rolling bearings for actuators of magnetic disk devices are required to have characteristics such as long life, low torque fluctuation, and low torque.
As a conventional rolling bearing in this field, there is a swing type using a ball bearing that supports a swing shaft, and a ball bearing filled with grease is used as the swing type bearing.

The present embodiment is to provide a rolling bearing for an actuator which maintains a longer life and suppresses a fluctuation in torque. The inner and outer rings are made of steel, and the ball has a surface of 0.2 to 0.2 mm. It is made of a ceramic having a depression of 20 μm, and the hardness of the ceramic is Hv1200 or more. The types of the steel material of the inner and outer rings and the ceramic material of the balls and the material of the cage in the ball bearing of the third embodiment are the same as those described in the ball bearings of the first and second embodiments. May be the same as In the case of a bearing that supports a rocking shaft, if all the components of the inner ring, outer ring, and balls are made of steel, the lubricating oil film is difficult to form due to the rocking motion, so it is easy to wear, causing fluctuations in the bearing torque and durability. There was also a problem with gender. If the ball is made of ceramics, the inner and outer rings made of steel and the dissimilar materials are combined, so that wear can be greatly reduced. As a result, the problem of torque fluctuation of the bearing can be solved and the service life can be extended. Since the surface of the ceramic ball has a recess having a diameter of 0.2 to 20 [mu] m having an oil reservoir effect, the life of the bearing can be further extended.

If the surface depression is less than 0.2 μm in diameter, the effect of the oil reservoir is small. On the other hand, if the diameter exceeds 20 μm, the torque fluctuation, sound, and vibration values become large, and it is unsuitable as an actuator ball bearing. Further, since stress concentrates on the edge of the depression on the surface of the ceramic ball, if the hardness of the ceramic is less than Hv1200, the ceramic is liable to be chipped, and the fragments thereof reduce the durability of the bearing.

The depression on the ball surface has a dimple effect. This will be described with reference to FIG. That is, FIG. 3A shows a case of a ball having no dent on the surface, and the lubricant flows away from the ball without flowing around to the back of the ball. However, in the case of FIG. 3B, since the surface of the ball has slight irregularities (dents), the flow of the lubricant is dragged by the ball and is not easily separated from the ball. Due to the flow wrapping around the back of the ball, running out of oil hardly occurs, which is effective as a measure against fretting.

As the lubrication of the ball bearing in the third embodiment, any type can be used as long as it can maintain the performance as a ball bearing for an actuator, such as grease lubrication, oil lubrication, and solid lubrication. (Examples) Hereinafter, the effects of the third embodiment of the present invention will be specifically described by comparative tests performed on examples and comparative examples. (A) Type of bearing used in the test: Deep groove ball bearing (No. SR1810, dimensions are 7.9 inner diameter)
(4 mm, outer diameter 12.7 mm, width 3.97 mm, use of non-contact rubber seal) (b) Lubrication of bearing: Grease lubrication was used, and the sealed amount was 1% of the space volume in the bearing. (C) Test content: c-1; Bearing outer ring swing test (fretting wear test) Test apparatus: A bearing outer ring swing test apparatus shown in FIG. 12 was used.

Oscillating motor 21 fixed to the lower surface of table 20
The swing cylinder 23 is attached to the swing shaft 22 so as to be swingable integrally. As for the test piece ball bearing 24, its outer ring is mounted on the inner peripheral surface of the swing cylinder 23, and the inner ring is mounted on the fixed shaft 25 inserted through the cylinder axis. The fixed shaft 25 is fixed to the table 20 by a column 26.

Swing angle: 8 degrees Swing frequency: 20 million times Axial load: 1 kgf Criteria: After the test, the bearing was disassembled and the inner ring was observed for wear. ：: No wear (wear depth less than 0.2 μm) Pass ×: Wear (wear depth 0.2 μm or more) Fail c-2: Bearing torque test Bearing rotation speed: 2 rpm Criteria: Torque value and torque of bearing Fluctuation values were measured.

Torque fluctuation ○: 1 × 10 ⁻³ N · m or less Pass ×: Over 1 × 10 ⁻³ N · m Fail (d) Test results: Examples 1 to 4 and Comparative Examples 1 to 4 Table 4 shows the test conditions and results.

[0050]

[Table 4]

From these results, according to the third embodiment, in the ball bearing for supporting the swinging shaft, the diameter of the ball bearing is 0.2 mm.
It can be seen that when the hardness of the ceramic ball having the depression of about 20 μm is defined as Hv1200 or more, good life and torque performance can be obtained. Next, as a fourth embodiment, an LBP deep groove ball bearing for a polygon scanner motor, which defines the raceway surface roughness of the raceway instead of providing a depression on the ball surface, will be described.

The deep groove ball shaft for a polygon scanner motor of this embodiment is different from that of the first embodiment.
No ball depression is formed. And the center line average roughness (Ra) of the raceway surface of the inner ring and the outer ring of the rolling bearing is 0.05 to
The track surface is coated with a lubricating oil having a kinematic viscosity at 40 ° C. of 10 to 150 mm ² / s.

The lubricating oil used in this case includes ester oil, synthetic hydrocarbon oil, ether oil, mineral oil and the like. The oil-lubricated deep groove ball shaft for a polygon scanner motor according to the fourth embodiment is different from the grease lubrication bearing of the polygon scanner motor of the conventional example 2 in that the rotational runout and high torque which are likely to occur in connection with the grease lubrication are different. Can be solved, and the life at high speed can be further extended. Also, the center line average roughness (Ra) of the raceway surface of the inner ring and the outer ring is set to 0.
By setting the thickness to a range of from 0.5 to 0.3 μm, the unevenness on the raceway surface has an oil reservoir effect, which greatly contributes to prolonging the bearing life.

The track surface roughness is 0.05 μm.
If it is less than m, the effect of the oil reservoir is too small. On the other hand, 0.3μ
If it exceeds m, torque fluctuation, sound, and vibration values become large, making it unsuitable as a bearing for a polygon scanner motor. Oil lubrication does not cause rotational runout because the change in bearing torque is very small compared to grease lubrication. When the kinematic viscosity of the lubricating oil is 10 to 150 mm ² / s (40 ° C.), the torque value is very low. In the present embodiment, this is actively used. The kinematic viscosity is 10 mm ² /
If it is less than s, the acoustic life of the bearing at high speed becomes short. On the other hand, if the kinematic viscosity exceeds 150 mm ² / s, the bearing life is long and there is no run-out, but the bearing torque increases.

The lubricating oil may contain additives such as antioxidants, rust inhibitors, antiwear agents, extreme pressure agents, and viscosity index improvers, all of which may be known. (Examples) Hereinafter, the effects of the fourth embodiment of the present invention will be specifically described by comparative tests performed on examples and comparative examples. (A) Type of bearing used in the test: Deep groove ball bearing (nominal number 695, dimensions 5 mm in inner diameter, 13 mm in outer diameter, 4 mm in width, using non-contact rubber seal) (b) Lubrication of bearing: immerse bearing in lubricating oil Then, it was lifted and blown with air to remove excess lubricating oil. (C) Test content: c-1; Bearing durability test (acoustic test) Bearing rotation speed: 20,000 rpm (inner ring rotation) Axial load: 2 kgf Ambient temperature: 60 ° C Judging criteria: After rotating the bearing for 3000 hours, use an Anderon meter The bearing was subjected to acoustic measurement, and the anderon values before and after the bearing durability test were compared.

Anderon value ○: 2.5 or less Pass ×: More than 2.5 Fail c-2; Torque test Bearing rotation speed: 9000 rpm Axial load; 2 kgf Temperature; Room temperature Judgment criteria: It was measured.

Torque value ○: 8 × 10 ⁻³ N · m or less Pass ×: Over 8 × 10 ⁻³ N · m Fail Torque fluctuation value ○: 1 × 10 ⁻³ N · m or less Pass ×: 1 × 10 ^(-3 ) Test results: Tables 5 and 6 show test conditions and results of Examples 1 to 4 and Comparative Examples 1 to 4.

[0058]

[Table 5]

[0059]

[Table 6]

From these results, according to the ball bearing for oil-lubricated polygon scanner motor of the fourth embodiment, the center line average roughness (Ra) of the inner and outer races is 0.05 to 0.3 μm, and It is understood that by applying a lubricating oil having a kinematic viscosity at 10 ° C. of 10 to 150 mm ² / s, the effect of solving rotational runout and high torque frequently occurring in conventional grease lubrication can be obtained.

Next, as a fifth embodiment, there is provided a rolling bearing for a microprocessor unit motor, in which a raceway surface roughness of a race ring is defined instead of providing a depression on a ball surface, and lubrication is performed with grease. An oil-lubricated one will now be described. In the deep groove ball bearing for a microprocessor unit motor according to this embodiment, unlike the second embodiment, no depression is formed on the surface of the ball. Then, lubricating oil having a center line average roughness (Ra) of the raceway surfaces of the inner ring and the outer ring of the rolling bearing of 0.05 to 0.3 μm and a kinematic viscosity at 40 ° C. of 10 to 150 mm ² / s is applied to the raceway surface. It has been applied.

The lubricating oil that can be used in this case is the same as that of the fourth embodiment. The oil-lubricated deep groove ball shaft for a microprocessor unit motor according to the fifth embodiment not only avoids the problems of rotational runout and high torque that are likely to occur in connection with grease lubrication, but also increases the life at high speeds. There is an advantage that can be extended. By defining the center line average roughness (Ra) of the raceway surface of the inner ring and the outer ring to be 0.05 to 0.3 μm, the surface of the raceway has an oil reservoir effect on unevenness,
This greatly contributes to extending the life of the bearing.

Thus, the average roughness of the raceway plane center line is
If it is less than 0.05 μm, the effect of the oil reservoir is too small. one
On the other hand, if it exceeds 0.3 μm, torque fluctuation, sound and vibration values are large.
And the bearings for the microprocessor unit motor
Is inappropriate. As mentioned earlier, oil lubrication is
Very little change in bearing torque compared to lease lubrication
And the kinematic viscosity of the lubricating oil is 10
150mm^Two/ S (40 ° C), the torque value is very
Low. However, the kinematic viscosity is 10 mm ^TwoHigher than / s
The acoustic life of the bearing at high speed is shortened. On the other hand, when the kinematic viscosity is 1
50mm^Two/ S, the bearing life is long and there is no run-out
However, the bearing torque increases.

The lubricating oil additive has been described in the fourth embodiment. (Examples) Hereinafter, the effects of the fifth embodiment of the present invention will be specifically described by comparative tests performed on examples and comparative examples. (A) Type of bearing used in the test: Deep groove ball bearing (nominal number 681X, dimensions 1.5 m inside diameter)
(b) Outer diameter 4mm, width 1.2mm) (b) Bearing lubrication: Lubricating oil is measured by a micro-syringe to 1% of the bearing space volume and discharged onto rolling elements with the inner ring, outer ring and rolling elements assembled. did. (C) Test contents: c-1; Bearing durability test The motor for the microprocessor unit shown in FIG. 8 was used for the bearing durability test. 6500 at constant voltage (30V)
The rotation time at rpm or higher was measured.

Atmospheric temperature: 70 ° C. Judgment criteria Bearing rotation time ○: 10,000 hours or more Passed: less than 10,000 hours Fail c-2: Torque test In the torque test, the same motor as in the above bearing durability test was used. The evaluation was performed by measuring the number of revolutions at a constant voltage (30 V).

Judgment Criteria Bearing rotation ６: 6500 rpm or more Pass ×: Less than 6500 rpm Fail (d) Test results: The test conditions and results of Examples 1 to 8 are also shown in Table 5 above. The test conditions and results of Comparative Examples 1 to 8 are also shown in Table 6 above.

According to the results, according to the oil-lubricated microprocessor unit ball bearing for the motor of the fifth embodiment, the center line average roughness (Ra) of the raceway surface of the inner and outer rings is 0.05 to 0.05%.
0.3 μm, and the kinematic viscosity at 40 ° C. is 10 to 150
It can be seen that by applying the lubricating oil of mm ² / s, the problems of rotational runout and high torque associated with grease lubrication can be avoided and the effect of extending the life at high speed can be obtained.

The relationship between the amount of lubricating oil enclosed and the bearing performance in a ball bearing for an oil lubricated microprocessor unit motor will be described below. (A) Lubricating Oil Enclosure Amount and Oil Particle Scattering State The number of scattered particles having a size of 0.3 μm or more at room temperature was measured using a dust amount measuring test apparatus shown in FIG. That is, a microprocessor unit motor (same as that shown in FIG. 8) incorporating a ball bearing is sealed in the container 30 and rotated at a rated speed while flowing clean air from one port. In this state, for each air volume of 0.01 cf volume, the number of scattered particles of 0.3 μm or more contained therein was measured using a particle counter connected to the outlet side, and the number was measured.
The scattering amount after one minute was obtained.

FIG. 14A shows the result of this experiment. It can be seen from the figure that when the amount of lubricating oil exceeds 10% of the bearing space volume, the number of scattered particles increases significantly. (B) Lubricating oil filling amount and torque A torque measurement test was performed for various lubricating oil filling amounts,
The result shown in FIG. 14B was obtained. If the amount of lubricating oil is increased by a certain amount or more, the torque increases, and as a result, the rotation speed attained decreases. When it exceeds 10% of the space volume in the bearing, it does not reach the set rotational speed of 6500 rpm. However, when the lubricating oil filling amount was less than 1% of the bearing space volume, the set rotation speed was reached even when the viscosity of the lubricant (40 ° C.) became larger than 150 mm ² / s.

As a result of further pursuing a test in consideration of this point, when the lubricating oil filling amount is 0.1% or more and less than 1%, the lubricant viscosity (40 ° C.) is up to 500 mm ² / s, and the durability, torque, It was found that all conditions of torque fluctuation and low dust generation were satisfied. In addition, if the encapsulation amount is less than 0.1%, lubrication becomes insufficient even if the viscosity of the lubricant increases, and the durability is not satisfied. (C) Lubricating Oil Filling Amount and Durability A bearing durability test was performed with various amounts of lubricating oil filling, and the results shown in FIG. 14 (c) were obtained. If the lubricating oil filling amount is small, the lubricating property is deteriorated, so that the durability time is shortened. If it is less than 0.1% of the bearing space volume, the required endurance time of 10,000 hours cannot be satisfied.

From the results of FIGS. 14 (a) to 14 (c), it is necessary to set the lubricating oil filling amount to be 0.1 to 10% of the bearing space volume. It can be said that the preferable range of the lubricating oil filling amount is in the range of 0.25 to 5%. In addition, in the case of grease lubrication, it is necessary to set the filling amount to 0.1 to 5% of the bearing space volume in order to reduce the influence of torque fluctuation due to the grease fluidity.

The lubricating oil filling amount and the torque value in (B) are described in Lubrication Vol. 32, No. 5, (1987) 331-33.
As shown on page 334, if the surface roughness is too small, the rolling viscous resistance increases, so that it is desirable to have a certain degree of roughness, and reducing the amount of lubricating oil reduces the lubricating oil stirring resistance and the rolling viscous resistance. There is also an effect, and the present invention in which the raceway surface roughness and the lubricating oil filling amount are specified also contributes to the effect of reducing the torque.

Here, the amount of lubricating oil charged is determined by measuring a specified amount with a micro syringe or a pump capable of measuring an extremely small amount of lubricating oil, and sprinkling the rolling element with the inner ring, outer ring, and rolling element assembled, and sprinkling the bearing. Is preferably a method of rotating several times. Further, when the lubricating oil is applied as a thin film in order to reduce the amount of the lubricating oil scattered, the lubricating oil is diluted with a solvent and the bearing is immersed therein. Alternatively, in order to avoid adhesion of lubricating oil to the outside of the bearing, solvent-diluted lubricating oil is applied on the raceway surface and rolling surface inside the bearing and then dried,
There is also a method of applying a lubricating oil. However, the method of sealing the lubricating oil in the bearing is not limited to this, and may be set in consideration of mass production in accordance with required performance.

Next, as a sixth embodiment, a rolling bearing for an actuator of an HDD, in which a raceway surface roughness of a race ring is defined instead of providing a depression on a ball surface, and lubrication is performed not by grease but by oil The lubrication will be described. HDD of this embodiment (especially swing arm)
Unlike the third embodiment, the actuator ball bearing has no depression formed on the ball surface. Then, the center line average roughness (Ra) of the raceway surface of the inner ring and the outer ring of the bearing
Is 0.05 to 0.3 μm, and the raceway surface, ball surface,
The lubricating oil composed of a fluoropolymer is applied to at least one location of the cage.

The HDD has a short existence period for one model, and a new model (a reduction in power, a high response, a high accuracy,
Are being developed one after another. Along with this, the motor output has been reduced and a HDD actuator unit with lower torque is desired. However, since the stirring resistance is large in the conventional grease lubrication, the torque is reduced by reducing the amount of grease. Had been managing. However, the reduction in grease amount reduces torque,
If the torque variation is reduced, other bearing functions such as durability performance may be affected.

Further, the conventional grease has a disadvantage that the fluctuation of the torque is large and not constant, so that the positioning of the magnetic head and the control during the seek operation are complicated. Further, in the conventional HDD, the gap (flying height) between the magnetic head portion and the magnetic disk is set to a certain extent so that even if a small amount of foreign matter adheres to the magnetic disk, it does not cause a catastrophic failure. However, recently, the flying height is only about 100 nm. Therefore, in the conventional grease, a head crash may occur due to the fact that the base oil, additives, and the like gradually evaporate and get on the airflow in the HDD and adhere to the magnetic disk. To cope with this, it is necessary to further reduce the outgassing of the lubricant.

The sixth embodiment is intended to solve such a problem of the conventional grease lubricated HDD. That is, unlike the third embodiment, the ball bearing for the actuator unit of the HDD of this embodiment has no depression formed on the ball surface. Instead, the center line average roughness (Ra) of the inner and outer raceways of the rolling bearing is adjusted to 0.05 to 0.3 μm, and a lubricating oil made of a fluoropolymer is used as a lubricant. Oil is applied to at least one of the bearing inner ring raceway surface, outer ring raceway surface, rolling elements, and holding.

According to the ball bearing for the actuator unit motor of the HDD of this embodiment, a lubricating oil of low outgas and high fluidity made of a fluoropolymer having a low vapor pressure is sealed in the inside of the bearing. It is possible to provide an actuator unit having a small torque, a good lubricating performance (fretting resistance performance) without localization of the lubricant, a head crash being prevented, and a long life.

The center line average roughness (R
By adjusting both a) to be in the range of 0.05 to 0.3 μm, the unevenness on the raceway surface has an oil reservoir effect, which greatly contributes to prolonging the bearing life. If the raceway surface roughness is less than 0.05 μm, the amount of lubricating oil stored in the surface roughness (unevenness) portion is too small, and the bearing durability is reduced. On the other hand, if the roughness exceeds 0.3 μm, the roughness becomes larger than the oil film thickness, and wear occurs, which reduces bearing durability and increases torque and torque fluctuation. By using the fluoropolymer as the lubricant in the range of the raceway surface roughness of the present embodiment, it is possible to reduce the torque and the torque fluctuation while maintaining the durability performance required for the actuator unit.

[0080] As the skilled fluoropolymer, fluoropolyether polymer or its derivatives are preferable, -C _X F
_2X —O— (X is an integer of 1 to 14) as a main structural unit,
A polymer having an average molecular weight of 1,000 to 15,000 is preferred. Considering lubrication performance and torque performance, the average molecular weight is 3
It can be said that 000 or more and 13000 or less are more preferable. Specifically, perfluoroalkyl polyether (PFP
E) as a side chain structure

[0081]

Embedded image

Also, as a linear structure

[0083]

Embedded image

The following can be mentioned. A polymer having an average molecular weight of 3,000 or more perfluoroalkyl polyether has a high viscosity index and a low pour point, so that good lubricating properties can be obtained in a wide temperature range. Specifically, for example, as the side chain structure, Krytox 143, Krytox GPL, Krytox 1500, and AUSIMO manufactured by DUPONT
Examples include Fomblin Y Standard manufactured by NNT and Barielta J Fluid manufactured by NOK Cruiba. As the straight-chain structure, Demnum of Daikin Industries, and Fomblin Z of AUSIMONNT are preferably used. Among them, Kleitex 143 has a side chain structure.
AB, Krytox GPL105, the linear structure of Demnum S100 had good lubricity (fretting resistance). In particular, a perfluoroalkyl polyether having a linear structure has excellent evaporation characteristics and lubrication characteristics and can be suitably used.

Further, as derivatives of the fluoropolyether polymer, those having a modified structure in which a functional group isocyanate group, hydroxyl group, carboxyl group, or ester group is introduced into both terminal groups of the linear and side chain structures are mentioned. Can be For example, a functional isocyanate group OCNC ₆ H ₃ (C
As the isocyanate-modified derivative having a linear structure obtained by introducing H ₃ ) NHCO,

[0086]

Embedded image

The following can be mentioned. In the case of alcohol modification, a functional group having a hydroxyl group HO—CH ₂ , HO—CH
₂ CHOCH ₂ OCH ₂ —CF ₂ , HO— (CH ₂ CH ₂ —
O), such as _n -CH ₂ CF ₂ it can be mentioned. In addition, -COOH is used for carboxyl group modification, and -COOR is used for ester modification. Further, different types of terminal functional groups may be used in combination.

Further, those in which the above-mentioned functional group is introduced into only one terminal group of the fluoropolyether polymer having a linear or side chain structure are also preferably used. Among them, those having a structure in which a carboxyl group is introduced at one end have a strong polarity and are well adsorbed on the metal surface, and thus exhibit good lubrication performance. Specifically, for example, Fomblin Z derivative of AUSIMONNT and Krytox 157 of DUPONT are suitable, and in particular, Krytox 157FS
M had good lubricity (fretting resistance).

These fluoropolyether polymers are:
Polymers having different average molecular weights or functional groups can be arbitrarily mixed, and by adjusting the viscosity or adding fluoropolyether having a functional group to perfluoropolyether, the wettability to metal is improved. It is also possible.
The amount of fluoropolyether polymer enclosed inside the bearing is
From the viewpoint of reducing the number of scattered particles described above, it is preferable to set the volume to 0.1 to 10% of the internal space volume of the bearing. If the filling amount exceeds 10% of the bearing space volume, the number of scattered particles becomes extremely large and the torque becomes excessive. Conversely, if the amount of the bearing internal space is less than 0.1, the lubricating property is deteriorated and the durability time is shortened. Further, in consideration of wear resistance (fretting resistance) and leakage of lubricating oil, the amount of the fluoropolyether polymer to be enclosed is preferably 0.25 to 5%.

The method for applying oil is not particularly limited. However, as described above, it is desirable to use a method in which the amount is determined by a micro syringe or a pump and sprinkled on a rolling element of the assembled bearing to make several rotations. Further, the above-mentioned method may be employed such as diluting the lubricating oil in a solvent and immersing the bearing therein, or applying the solvent-diluted lubricating oil on the bearing inner race surface and the rolling surface and then drying. (Examples) Hereinafter, the effects of the sixth embodiment of the present invention will be specifically described by tests performed on examples. (A) Type of bearing used in the test: Deep groove ball bearing (call number SR1810, dimensions are 7.
(94 mm, outer diameter 12.7 mm, width 3.97 mm, use of non-contact rubber seal) (b) Lubrication of bearing: The following lubricating oil was measured with a micro syringe and supplied to the rolling elements of the bearing.

The lubricating oil of the present example was Demnum S100 (kinematic viscosity at 40 ° C. is 100 mm ² / s) as linear PFPE.
And the Krytox 143AB (same 85 mm ² / s) as a side chain PFPE, the Krytox 157FSL (the 140 mm ² / s) as a modified fluoropolymer, turbine oil 100 as mineral oil (the 100 mm ² / s),
Each was used. (C) Test content: c-1; Bearing outer ring swing test (fretting durability test) Test apparatus: A bearing outer ring swing test apparatus shown in FIG. 12 was used.

Oscillation angle: 8 degrees Oscillation frequency: 30 Hz Preload (Fa): 1 kgf Criteria: The relationship between the raceway surface roughness and the number of times of fretting durability when the amount of lubricating oil is fixed at about 1% of the bearing space volume. I asked.

The center line average roughness of the raceway surface of the inner and outer rings is set to 0.1
The relationship between the amount of lubricating oil enclosed and the number of times of fretting durability when μm was constant was determined. In each case, the torque fluctuation was observed over time, and the number of times the torque fluctuation appeared near the swing angle ± 4 degrees was defined as the number of times of fretting durability. Number of times of fretting durability ○: 20 million times or more Passed: Less than 20 million times Fail The results of the test are shown in FIGS. 15 and 16.

FIG. 15 shows the relationship between the track surface center line average roughness and the number of times of fretting durability. Irrespective of the type of oil, the roughness is the lower limit in this embodiment of 0.05
It can be seen that when the value is less than μm and when the value exceeds the upper limit value of 0.3 μm, the number of times of fretting durability does not reach 20 million times, and the test is rejected. FIG. 16 shows the relationship between the amount of lubricating oil charged and the number of times of fretting durability. As the lubricating oil, Demnum S100 of linear PFPE was used. When the lubricating oil filling amount was less than the lower limit of 0.1% in the present embodiment, the lubricating property deteriorated, and the number of times of fretting durability did not reach 20 million times, so that the specimen was rejected. On the other hand, when it exceeds the upper limit of 10%, it has been found that the leakage of the lubricating oil is large and is not suitable for practical use despite the fretting durability number exceeding 20 million times.

C-2: Bearing Torque Test The inner ring of the bearing was rotated at a low speed, and the torque of the outer ring of the bearing was measured. Bearing rotation speed: 2 rpm Criteria: The amount of lubricating oil was kept constant at about 1% of the bearing space volume, and the raceway roughness with respect to the average rotation torque was evaluated.

An average rotation torque of 0.5 g · cm or less was regarded as acceptable. The results of the test are shown in FIG. The figure shows linear PFPE
In the case of Demnum S100, there was no significant difference depending on the test lubricant. This is because the influence of the difference in kinematic viscosity is reduced due to the low rotation speed. For example, Krytox 1
57FSM (kinematic viscosity at 40 ° C. is 290 mm ² / s) also satisfies the criteria for the fretting durability test and torque test in the above test. Viscosity 10-3
The range of application can be extended up to a lubricating oil of 00 mm ² / s. If the track surface center line average roughness exceeds the upper limit of 0.3 μm in the present embodiment, the torque value is rejected.

C-3: Evaporation loss test 1 g of the test lubricating oil was weighed into a petri dish (diameter 30 mm).
It was kept in a thermostat at 120 ° C. for 24 hours, and the amount of decrease in the lubricating oil was measured. The test results are shown in FIG. In the case of Demnum S100, Krytox 143AB, Krytox 157FSL, and Krytox 157FSM, the evaporation amount was 0.1% by weight or less even after 24 hours, but in the case of mineral oil turbine oil 100, In this case, the evaporation rate becomes 0.1 in about 9 hours.
% By weight. From this result, when it is required that the amount of evaporation during use is required to be small, any one of a fluoropolymer such as a linear PFPE, a side chain PFPE, or a modified fluoropolymer having excellent evaporation characteristics is used as a lubricating oil. It is better to use.

According to the sixth embodiment, a fluorine-containing polymer is sealed in the inside of a ball bearing for supporting a swinging shaft in an HDD actuator unit, and the center line average roughness of the raceway surface groove of the inner ring and the outer ring. (Ra) 0.05-0.3μ
By using a value of m, it is possible to achieve a low torque, a low torque fluctuation, a low outgassing, and an effect that a highly reliable and high-performance actuator unit can be obtained.

Note that each of the above embodiments is based on LBP, HD
D and the case of bearings for microprocessor unit motors have been described, but the rolling bearings of the present invention are not limited to these applications, but also have excellent lubricant holding power, scattering amount, torque, acoustic characteristics, etc. It can be applied to any application that requires cleanliness and no environmental pollution. In the above-described embodiment, an example of application to a vertical motor has been described. However, the present invention is not limited to a vertical motor and can be applied to a horizontal motor. However, it is more effective when used in a vertical form. This is because, when used in a vertical position, almost half of the contact portion between the ball and the raceway faces downward and the lubricating oil falls in the direction outside the bearing,
This is because the lubricating oil tends to decrease. On the other hand, in a horizontal installation, the raceway groove serves as a dam to prevent the leakage of the lubricating oil to the outside of the bearing, so that the amount of the lubricating oil is not so reduced as in the case of the vertical type. Further, in the vertical type, since the weight of the cage is almost loaded on the ball, lubrication of the contact portion is important. From these points, the effect of the present invention is more remarkably different from the conventional example in the case of the vertical type.

In the rolling bearing of the present invention, the depression on the surface of the rolling element and the center line average roughness of the raceway surfaces of the inner and outer races may be used together.

[0101]

As described above, according to the first aspect of the present invention, while maintaining extremely high cleanliness and high-speed life (durability), low torque, low torque fluctuation and fretting resistance are achieved. In addition, it is possible to provide an excellent rolling bearing for information office equipment.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a setting range of a recess diameter of a ball surface and a viscosity of a lubricating oil in a bearing of the present invention.

FIG. 2 is a diagram illustrating a setting range of a track surface center line average roughness and a lubricating oil viscosity in the bearing of the present invention.

FIG. 3 is a diagram illustrating a setting range of a lubricating oil filling amount and a lubricating oil viscosity in a bearing of the present invention.

FIG. 4 is an enlarged view showing an example of a depression on the surface of a ceramic ball.

FIG. 5 is a sectional view of a bearing durability test apparatus.

FIG. 6 is a diagram showing the relationship between the size of the ball depression diameter and the acoustic, torque, and torque fluctuation values in the ball bearing of the present invention.

FIG. 7 is a diagram showing a relationship between kinematic viscosity of lubricating oil and sound, torque value, and torque fluctuation value in the ball bearing of the present invention.

FIG. 8 is a sectional view of a motor for a microprocessor unit.

FIG. 9 is a diagram showing the relationship between the size of the hollow diameter of the ball of the bearing, the number of revolutions of the bearing, and the durability life.

FIG. 10 is a graph showing the relationship between the kinematic viscosity of the lubricating oil of the bearing, the rotational speed of the bearing, and the durability life.

FIG. 11 is a view for explaining the effect of the depression of the ball of the bearing;
(A) shows a case without a dent, and (b) shows a case with a dent.

FIG. 12 is a sectional view of a bearing outer ring swing test apparatus.

FIG. 13 is a cross-sectional view of a test device for measuring the amount of generated dust of a bearing.

14A and 14B are diagrams showing the relationship between the amount of lubricating oil sealed in the bearing and the bearing performance, wherein FIG. 14A shows the number of dust particles, FIG.
(C) is a diagram showing the endurance time.

FIG. 15 is a view showing the relationship between the average roughness of the raceway surface center line and the number of times of fretting durability of a bearing using a lubricating oil composed of a fluoropolymer.

FIG. 16 is a diagram showing the relationship between the amount of lubricating oil enclosed in a bearing using a lubricating oil made of a fluoropolymer and the number of times of fretting durability.

FIG. 17 is a diagram showing a relationship between a track surface center line average roughness and an average rotation torque of a bearing using a lubricating oil made of a fluoropolymer.

FIG. 18 is a diagram showing an evaporation rate of a lubricating oil comprising a fluoropolymer.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J101 AA02 AA42 AA54 AA62 BA04 BA10 BA50 BA55 BA70 EA03 EA06 EA36 EA37 EA42 EA43 EA44 EA67 FA32 FA35 FA60 GA53

Claims (1)

[Claims] A center line average roughness of a rolling element and / or a raceway surface provided with a recess having a diameter of 0.2 to 20 μm is 0.0
For information office equipment, comprising a bearing ring having a diameter of 5 to 0.3 μm and using a lubricant comprising a lubricating oil or a lubricating base oil having a kinematic viscosity at 40 ° C. of 10 to 500 mm ² / s. Rolling bearing.