JP2000205277A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rolling bearing allowing establishment of the torque stability and enhancement of the abrasive resistance. SOLUTION: Diamondlike carbon films 5 are formed at least either of the raceways of bearing rings 1 and 2 and the surface of rolling elements 3, wherein the surface roughness of the carbon films 5 is set under 0.005 μm by Ra (center line mean roughness). Because the carbon films 5 are made flat and smooth as much as practicable in the mentioned manner, the rolling characteristics of the rolling elements 3 can be stabilized, and wear in the eventual slippage of rolling element can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a rolling bearing. This rolling bearing is used for various devices arranged in, for example, vacuum, high temperature, clean atmosphere, and the like.

[0002]

2. Description of the Related Art In a rolling bearing used in the above-mentioned environment, a soft lubricant such as gold, silver, copper, lead, or a solid lubricant such as graphite or molybdenum disulfide is applied to the surface of a raceway or a rolling element. Is coated.

[0003]

In the above-mentioned rolling bearing, it is pointed out that the rolling resistance of the rolling element is large and the rotational torque becomes unstable because the solid lubricant is relatively soft and has a rough surface. At the same time, it is pointed out that the solid lubricant has a short life because the solid lubricant is easily worn by the rolling and sliding operations of the rolling elements.

[0004] Accordingly, it is an object of the present invention to stabilize the rotational torque and improve the wear resistance of a rolling bearing.

[0005]

According to a first aspect of the present invention, there is provided a rolling bearing, wherein a diamond-like carbon film is formed on at least one of a raceway surface of a raceway and a rolling element surface. Has a surface roughness Ra (center line average roughness) of 0.005 μm
It is set as follows.

In the rolling bearing according to the second aspect of the present invention, the hardness of the diamond-like carbon film according to the first aspect is as follows.
Hv (Vickers hardness test) is set to 2000 or more.

As described above, in the present invention, since the race and the rolling element come into contact with each other via the extremely smooth diamond-like carbon film, the rolling resistance of the rolling element is reduced, and even if the rolling element slips. Wear of the diamond-like carbon film is suppressed.

In particular, when the hardness of the relatively hard diamond-like carbon film is increased to a required level or more, the rolling resistance of the rolling element is further reduced.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on embodiments shown in the drawings.

FIG. 1 is a longitudinal sectional view of an upper half of a rolling bearing according to an embodiment of the present invention. In the figure, A indicates the entire rolling bearing, and illustrates a type called a deep groove ball bearing. The rolling bearing A includes an inner ring 1 and an outer ring 2.
, A spherical rolling element 3 and a wave-shaped cage 4.

The above-mentioned inner and outer rings 1 and 2 and the rolling elements 3 are formed of various metal materials. Examples of the metal material include a martensitic stainless steel such as JIS standard SUS440C, and a metal material obtained by subjecting a precipitation hardening type stainless steel such as JIS standard SUS630 to an appropriate hardening heat treatment. Steel and the like. In addition, as a material of the retainer 4, an austenitic stainless steel such as JIS SUS304 or the like can be used.

Of these, diamond-like carbon (Dia) is provided on the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2.
(Month Like Carbon: DLC) film 5 is formed. This DLC film 5 is formed, for example, by chemical vapor deposition (C
VD), plasma CVD, ion beam formation, ionization vapor deposition, or the like.

[0013] If, in the case of forming the DLC film 5 by CVD, for example the carbon source or its mixed gas of hydrogen, and the like, such as CH _4, a suitable amount of inert gas as a carrier gas as needed In addition, this is 1 to 10 ^-3 Torr
It circulates to target parts heated to about 200 to 1100 ° C. at about r. As a result, carbon is attached to the target component, and the DLC film 5 is generated. At this time, the thickness of the DLC film 5 is controlled to, for example, about 0.1 to 1 μm, and the surface roughness is Ra (center line average roughness).
Is controlled to 0.005 μm, and the hardness is controlled to 2000 or more by Hv (Vickers hardness test). Note that DL
When the C film 5 is partially formed on the target component, masking may be appropriately performed.

In particular, when the base material is the above-described metal material, the carbon of the DLC film 5 is bonded to the carbon contained in the base material itself. Has extremely high adhesion to the base material. In addition, since the bonding force between the carbon atoms constituting the DLC film 5 is strong, the DLC film 5 itself is less likely to be worn or damaged. Further, since the DLC film 5 is hardened to the above-mentioned level to make the surface smooth, the rolling resistance of the rolling elements 3 is reduced, the rolling operation becomes extremely smooth, and the DLC film 5 is hardly worn.

The roughness and hardness of the DLC film are DL
It can be changed by adjusting the pressure, temperature, type of gas, applied voltage and the like of the molding atmosphere at the time of forming the C film.

FIG. 4 shows the relationship between the surface roughness of the DLC film and the coefficient of friction. This data is D
Four kinds of samples having different compositions were prepared by changing various conditions at the time of forming the LC film, and the surface roughness Ra was determined for each of the samples.
And the friction coefficient μ were measured. The coefficient of friction μ
Was measured by pressing a steel or aluminum ball against a disk coated with a DLC film as shown in FIG. To stabilize the rotational torque as a rolling bearing, the friction coefficient μ needs to be 0.7 or less.
Therefore, when the surface roughness Ra of the DLC film is set to 0.005 μm or less, the friction coefficient μ becomes 0.7 or less, the frictional resistance is small, and the rotation torque can be stabilized. If the surface roughness of the raceway surface and the rolling elements is less than 0.005 μm, the hardness of the DLC film is high, so that the contact partner surface is significantly worn and the life of the bearing is shortened. further,
When the hardness of the DLC film is Hv2000 or more, the wear resistance is improved, and the life of the bearing can be further improved.

In the above-described rolling bearing A, since the smooth and hard DLC film 5 is formed at a required portion of the bearing component, the operation of the rolling bearing A can be stabilized for a long time and the service life can be extended. Will be able to achieve.
Moreover, since such a rolling bearing A is excellent in use without lubrication, it can be suitably used for semiconductor manufacturing equipment which is in a vacuum, high temperature and clean atmosphere, or equipment which is arranged in the same atmosphere. .

It should be noted that the present invention is not limited to only the above embodiment, and various applications and modifications are conceivable.

(1) In the above embodiment, a deep groove ball bearing is cited as a bearing type, but the present invention can be applied to other types of rolling bearings.

(2) In the above embodiment, the DLC film 5 is formed only on the inner and outer rings 1 and 2, but may be formed only on the rolling element 3 as shown in FIG. As shown in FIG. 3, it can be formed on all of the bearing components 1-4. Further, in the above embodiment, the DLC film 5 is formed on the outer peripheral surface of the inner ring 1 and the inner peripheral surface of the outer ring 2, but it can be formed only on the raceway surface or on the entire outer surface. When the DLC film 5 is formed on the holder 4, it may be formed on the entire surface or only on the inner surface of the pocket. In particular, when the DLC film 5 is formed on all of the bearing components 1 to 4, it can be made to withstand use in a corrosive environment, so that, for example, a general metal material without using a base material as a corrosion-resistant material As a result, cost can be reduced.

(3) The rolling bearing A in the above embodiment may be coated with a fluorine-based lubricant.
In this case, the wettability of the fluorine-based lubricant inside the bearing with respect to the DLC film 5 becomes extremely good. Therefore, even if the rolling elements 3 slip, even if the sliding of the rolling elements 3 occurs, the surfaces of the inner and outer rings 1 and 2 and the rolling elements 3 The lubricating oil film is hardly interrupted, and the lubricity can be improved. In this case, the DLC film 5 may contain fluorine. In this case, due to the fluorine contained in the film, the wettability of the fluorine-based lubricant used inside the bearing is further improved, and the lubricating oil film is hardly interrupted.
In order to obtain such a DLC film 5 containing fluorine, the DLC film 5 may be mixed with a gas supplied by the CVD method in the above embodiment, or the DLC film 5 may be formed after the DLC film 5 is formed. It is conceivable to perform the treatment in a plasma fluorine atmosphere.

(4) In the rolling bearing A in the above embodiment, the rolling element 3 can 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 (AlN),
Besides silicon nitride (Si ₃ N ₄ ) using titanium oxide (TiO ₂ ) and spinel (MgAl ₂ O ₄ ),
Alumina (Al ₂ O ₃ ), silicon carbide (SiC), zirconia (ZrO ₂ ), aluminum nitride (AlN), and the like can be used. Further, the retainer 4 can be formed of a synthetic resin material. In that case, it is preferable that the shape of the retainer 4 be a crown shape or a hollow shape.
As the synthetic resin material, in addition to a thermoplastic resin having heat resistance, for example, a TPI (thermoplastic polyimide) resin filled with 5 to 10 wt% of PTFE (polytetrafluoroethylene) and 10 to 20 wt% of graphite,
Fluorinated resins such as polytetrafluoroethylene (hereinafter abbreviated as PTFE) and ethylene tetrafluoroethylene (ETFE) and polyetheretherketone (PE)
EK), polyphenylene sulfide (PPS), polyether sulfone (PES), polyether nitrile (PEN), polyamide imide (PAI), nylon 4
6, engineering plastics and the like. Reinforcing fibers such as glass fibers may be appropriately added to these resins.

(5) In the above embodiment, the rolling bearing A
Although an open type without a sealing device is illustrated as an example, a device with a sealing device may be mounted.

[0024]

In the rolling bearing according to the first and second aspects of the present invention, a smooth diamond-like carbon film is formed at the contact portion between the raceway ring and the rolling element, so that the rolling between the raceway ring and the rolling element is reduced. The friction coefficient at the time of sliding can be reduced, which contributes to longer life, such as stabilization of rotational torque and improvement of wear resistance.

In particular, if the hardness of the originally hard diamond-like carbon film is increased to a required level or more as in the second aspect of the present invention, further stabilization of rotational torque and further improvement of wear resistance can be achieved. Become like

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an upper half of a rolling bearing according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of an upper half of a rolling bearing according to another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of an upper half of a rolling bearing according to still another embodiment of the present invention.

FIG. 4 is a graph showing a correlation between the surface roughness of a DLC film and a coefficient of friction.

FIG. 5 is a diagram showing a method for measuring a friction coefficient of a DLC film.

[Explanation of symbols]

 A Rolling bearing 1 Inner ring 2 Outer ring 3 Rolling element 4 Cage 5 DLC film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J101 AA02 AA32 AA42 AA54 AA62 BA10 BA50 BA53 BA54 BA70 DA05 EA05 EA06 EA31 EA33 EA34 EA36 EA37 EA42 EA43 EA44 EA47 EA53 EA78 FA08 FA31 FA60 GA57

Claims (2)

[Claims] 1. A diamond-like carbon film is formed on at least one of the raceway surface of a bearing ring and a rolling element surface, and the surface roughness of the diamond-like carbon film is Ra (center line average roughness). A rolling bearing set to 0.005 μm or less. 2. The rolling bearing according to claim 1, wherein the hardness of the diamond-like carbon film is set to 2000 or more by Hv (Vickers hardness test).