JPH06193637A - Rolling bearing - Google Patents

Abstract

PURPOSE:To obtain a rolling bearing excellent in durability, and unsusceptible to contamination by ambient environment even if it is used under conditions like vacuum, high moisture, and corrosive gas, by making either one of a roll surface and a rolling body of oxide group ceramics, and forming a carbon film containing amorphous carbon on the other surface. CONSTITUTION:In a full type angular rolling bearing not using any cage, roll surfaces 3, 4 are respectively provided on the opposite surfaces of an inner race 1 and an outer race 2, and a plurality of balls 5 serving as rolling bodies are incorporated between the roll surfaces 3, 4. SiC films 6 as intermediate layers are formed on the obverses of respective roll surfaces 3, 4, and DLC films 7 are formed on the obverses of the SiC films 6. And the balls 5 are made of oxide group ceramics like Al2O3, SiO2, ZrO2. Moreover, in place of this structure, the obverses of the balls 5 can be coated by the SiC film 6 and the DLC film 7, and the inner race 1 and the outer race 2 can be made of oxide group ceramics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing used in a special environment such as a vacuum or a high temperature condition, and more particularly to a lubricating structure between a rolling surface of a bearing ring and a rolling element.

[0002]

2. Description of the Related Art When a rolling bearing is used in an environment such as high vacuum, high temperature, or in corrosive gas, the lubricating oil or grease used for normal bearing lubrication causes oil to evaporate into the atmosphere. Conventionally, solid lubricants having a low vapor pressure, such as silver (Ag), molybdenum disulfide (MoS ₂ ), and lead (Pb), have been used because they may deteriorate the lubricating performance and pollute the use environment.

However, in a rolling bearing using Ag as a solid lubricant, wear powder is liable to be generated when used in a vacuum and its corrosion resistance is poor. There is a drawback to decrease.

Further, when MoS ₂ is used as a solid lubricant, abrasion powder is generated similarly to Ag, and when it is used under high temperature conditions, it causes thermal decomposition to generate a sulfur-based corrosive gas. There is a problem that it will occur and corrode peripheral equipment.

Further, when the bearing is lubricated with Pb,
Since the bearing is likely to vibrate and a large amount of lead wear powder is discharged, the vacuum equipment used may be contaminated.

Therefore, the present invention solves the above-mentioned problems and does not generate abrasion powder or corrosive gas even when used under conditions of vacuum, high temperature, corrosive gas, etc., and has durability that does not pollute the surrounding environment. The purpose of the present invention is to provide an excellent rolling bearing.

[0007]

In order to solve the above-mentioned problems, the present invention is a rolling bearing in which a rolling element is incorporated between rolling contact surfaces provided on two bearing rings. One of the moving bodies was formed of oxide ceramics, and the carbon film containing amorphous carbon was formed on the other surface.

The carbon film containing amorphous carbon is a film in which carbon is coated on a metal surface or the like, and carbon atoms are arranged like diamond crystals. Generally, a diamond-like carbon film,
Alternatively, it refers to a carbon film called an i-carbon film (hereinafter referred to as a DLC film). The DLC film can be coated on the raceway surface and the rolling elements by using various well-known thin film forming techniques such as an ion plating method, a plasma CVD method and an ion beam vapor deposition method. In addition, as a material for bearing rings and rolling elements, S
When using steel such as UJ2, SUS440C, M50, etc., an intermediate layer may be provided between the steel substrate and the DLC film in order to enhance the adhesion between them. The intermediate layer can be selected from ceramic-based coatings such as Si, SiC, and SiO ₂ , and these intermediate layers can also be formed by a well-known thin film forming technique like the DLC film.

On the other hand, as the oxide ceramics, A
l ₂ O ₃ , SiO ₂ , ZrO ₂ , mullite (Al ₂ O ₃
· SiO _2), may be selected from ceramics such as steatite (MgO · SiO _2).

[0010]

The above-mentioned DLC film and oxide-based ceramics are hard to each other, and the combination of the two makes it possible to obtain an extremely low friction coefficient at the contact portion, so that the generation of abrasion powder at the sliding portion is significantly reduced. can do.

Further, since the DLC film and the oxide ceramics can be used in vacuum and have excellent corrosion resistance, they are not corroded even when used in a corrosive gas atmosphere.
In addition, since the physical properties of DLC do not change up to the high temperature at which graphitization occurs, the lubricating performance can be stably maintained even under special conditions such as high temperature, high vacuum and corrosive environment.

[0012]

EXAMPLE FIG. 1 shows a rolling bearing of an example. This rolling bearing is a full-ball angular ball bearing that does not use a cage. Rolling surfaces 3 and 4 are provided on the facing surfaces of the inner ring 1 and the outer ring 2, respectively. It incorporates a plurality of balls 5 that are moving bodies.

An SiC film 6 as an intermediate layer is formed on the surface of each of the rolling surfaces 3 and 4, and D is formed on the surface of the SiC film 6.
The LC film 7 is formed.

The balls 5 are made of Al ₂ O ₃ and Si.
It is made of oxide ceramics such as O ₂ and ZrO ₂ .

In place of the above structure, the surface of the ball 5 is coated with the SiC film 6 and the DLC film 7, and the inner ring 1 and the outer ring 2 are coated.
May be formed of oxide-based ceramics.

Next, using the bearing having the structure shown in FIG. 1, a life test comparing the lubricating performance of the present invention with the conventional product will be described.

In this test, the inner ring 1 and the outer ring 2 are S
It is formed of US440C, and the rolling surfaces 3 and 4 have a SiC film 6 having a thickness of about 0.1 μm and a DLC having a thickness of about 0.5 μm.
The film 7 was formed. The both films 6 and 7 were formed by the ion beam evaporation method. The test bearing used had an inner diameter of 8 mm, an outer diameter of 22 mm and a width of 7 mm.

In the test, as shown in FIG. 2, a ball 5 made of ZrO ₂ (Example 1) and Al ₂ O ₃ (Example 2) were prepared. A material having SUS440C (Comparative Example 1) was prepared. In addition, as another comparative example, one in which an Ag film is ion-plated on the rolling surfaces of the inner and outer rings (Comparative Example 2) and Mo
A sputtered S ₂ film (Comparative Example 3) (the ball material of each of Comparative Examples 2 and 3 was SUS440C) was formed.

In the test, the inner rotor is supported by two test bearings in a vacuum chamber, and the inner rotor is driven by the outer rotor to rotate the inner rotor, and the thrust load is applied to each test bearing. In addition, the friction torque of the test bearing was measured by the speed ratio between the inner rotor and the outer rotor. The test conditions are the number of revolutions of the internal rotor is 2500 rpm,
With a thrust load of 10 N, the friction torque of the two test bearings measured at room temperature and a vacuum degree of 10 ^-4 Pa or less was 1 N.
・ When it reached cm, it was judged as the end of life.

The test results are shown in the graph of FIG. As shown in these results, the rolling surface of the DLC film and SUS440C
Comparative Example 1 in which the above balls were combined had the shortest life, while the ion plated product of Ag film (Comparative Example 2) and the sputtering product of MoS ₂ film (Comparative Example 3) had a slightly longer life.
Still, it did not reach 200 hours. On the other hand, D
LC film and ZrO ₂ ball, or DLC film and Al ₂ O ₃
The life of Examples 1 and 2 in which the above balls are combined is 1 respectively.
It was 100 hours or longer and 860 hours or longer, showing extremely high durability relative to the comparative example.

On the other hand, FIG. 3 shows the structure of the sliding member used in the friction test conducted to evaluate the optimum ceramic material to be combined with the DLC film.

The sliding member 11 is a DL member formed on the surface of a disc 12 made of SUS440C with an intermediate SiC film 13 interposed therebetween.
The C film 14 is covered. The formation of each coating 13, 14 is
It was performed in the same vacuum chamber by the ion beam evaporation method.

In the friction test, as shown in FIG. 4, with respect to the sliding member 11, a ball as a rolling element was made of ZrO ₂ (Example 3) and Al ₂ O ₃ was used ( Example 4), SUS440C (Comparative Example 4), Si ₃ N ₄ (Comparative Example 5), and SiC (Comparative Example 6) were prepared. The sliding member 11 was made to slide on the DLC film 14 under a predetermined load, and the friction coefficient at that time was measured.

The test conditions are a load of 1.47 N (initial surface pressure 6
30 MPa) with a sliding speed of 1.0 m / S and a load of 0.49 N (initial surface pressure of 430 MPa) with a sliding speed of 0.2 m / S.
In each case, the degree of vacuum was 10 ⁻⁴ Pa or less, and the measurement was performed at room temperature.

The graph of FIG. 4 shows the results of the friction test. As a result, the friction coefficient of Comparative Example 4 in which the ball material was SUS440C showed the highest value of 0.4 to 0.5, whereas that of Examples 1 and 2 in which the ball material was oxide ceramics. Friction coefficient is 0.1 under two loading conditions
The following very small values were shown.

On the other hand, the friction coefficient of Comparative Example 5 or 6 in which the ball material is Si ₃ N ₄ or SiC which is the non-oxide ceramic 8 shows a high value of 0.4 or more as in Comparative Example 4 above. , There was a big difference with the oxide ceramics.

This is because, in the combination of the DLC film and the non-oxide ceramics or steel, some kind of solid-phase reaction occurs in the sliding portion and a kind of adhesion phenomenon occurs to increase the friction coefficient. It is presumed that the DLC film and the oxide ceramics have a low friction coefficient because they do not cause adhesion, and the combination of the DLC film and the oxide ceramics exhibits the best lubrication performance. It is shown.

[0028]

As described above, according to the present invention, the rolling surface and the rolling elements of the rolling bearing are combined with the DLC film and the oxide ceramics which are hard and which can obtain a very low friction coefficient.
The generation of wear debris during operation can be significantly reduced and the surrounding environment is not polluted. In addition, the DLC film and oxide-based ceramics have stable physical properties even in vacuum, high temperature, and corrosive environment, and their performance does not deteriorate. Therefore, even when used in the above special environment, they have excellent durability and lubrication performance. Can be maintained stable.

[Brief description of drawings]

FIG. 1 is a sectional view showing a rolling bearing according to an embodiment.

FIG. 2 is a graph showing the results of a life test using the above bearing.

FIG. 3 is a sectional view showing a sliding member used in a friction test.

FIG. 4 is a graph showing the results of a friction test.

[Explanation of symbols]

 1 Inner ring 2 Outer ring 3, 4 Rolling surface 5 Ball 6 SiC film 7 DLC film 11 Sliding member 13 SiC film 14 DLC film

Claims (1)

[Claims] 1. A rolling bearing in which a rolling element is incorporated between rolling surfaces provided on two bearing rings, wherein one of the rolling surface and the rolling element is made of oxide ceramics and the other surface is formed. , A rolling bearing characterized by forming a carbon film containing amorphous carbon.