JPH11173332A - Rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rolling bearing suitable to be used under a vacuum and high-temperature environment, by forming at least one component, out of components having a contact surface creating rolling or sliding friction, by SiC material. SOLUTION: This bearing is composed of an inner ring 1 fittedly mounted on a rotating spindle, an outer ring 3 fitted to a housing 2, plural balls 4 interposed between the rings 1 and 3, and a cage 5 for retaining the balls 4 at constant intervals in a circular periphery. The ring 3 is formed of carbon-added SiC material(SiC ceramic), and the ring 1 and the balls 4 and the cage 5 are formed of martensite system stainless steel e.g. SUS440C and SUS304, etc., respectively. The ring 3 composed of SiC having self-lubricity can fulfill a role as a lubricant supply source, thereby eliminating the use of the lubricant such as PIFE. Consequently in this bearing, the anxiety of lubricity lowering, due to the high-temperature deterioration of the lubricant, can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing suitable for use in a special environment in which a fluid lubricant such as grease or oil cannot be used, particularly in a high temperature and vacuum environment.

[0002]

2. Description of the Related Art For example, in the field of semiconductor manufacturing, the line width of a circuit pattern becomes finer and the layered structure (two-story structure) tends to be increased as the degree of integration of semiconductors increases. In such cases, wafers are being processed at higher temperatures (about 500 ° C.). Therefore, the bearings in the wafer transfer system
The temperature is expected to rise to about 00 ° C, which is favorable for characteristics such as a decrease in lubricity due to high temperature deterioration of the lubricant, creep of the raceway due to thermal expansion of the housing, durability of the bearing, and low dust generation. There is concern about the occurrence of phenomena that have no effect.

At present, as a rolling bearing suitable for use in a high-temperature, vacuum environment as described above, there is known a rolling bearing in which bearing components such as an inner ring and an outer ring are formed of a polyimide resin or a copna resin (Japanese Patent Laid-Open Publication No. Heisei (Kokai) No. HEI 9-26186). No. 7-279973, JP-A-8-184321
No.).

[0004]

The polyimide resin and the copna resin are excellent in heat resistance and abrasion resistance and have good self-lubricating properties, so that they exhibit an excellent effect in terms of lubricity.

However, since these bearings use a resin material having a mechanical strength inferior to metal as a structural member, there is an anxiety in terms of strength against an impact load or the like. Also,
Generally, the resin material absorbs water (however, the water absorption of the polyimide resin is low). Therefore, when used in a vacuum or high-temperature environment, there is a possibility that the water absorption may cause outgas and contaminate the surrounding environment.

Accordingly, an object of the present invention is to provide a rolling bearing suitable for use in a vacuum or high-temperature environment by securing sufficient strength against an impact load or the like and preventing or suppressing water absorption.

[0007]

SUMMARY OF THE INVENTION According to the present invention, among components having a contact surface that generates rolling friction or sliding friction,
At least one component was formed from a SiC material.

[0008] SiC (silicon carbide) material is excellent in heat resistance and load resistance, does not absorb water, and has a small decrease in strength even at high temperatures. Therefore, a rolling bearing suitable for use in vacuum and high temperature environments is provided. can do. In addition, since SiC is layered and has good self-lubricating properties, there is no concern that lubricating properties will decrease due to high-temperature deterioration of the lubricant.

If carbon is dispersed as an additive in the SiC material, conductivity can be ensured. The addition amount of carbon is preferably about 20%. A bearing to which carbon is added is suitable as a rolling bearing for a liquid crystal panel manufacturing facility requiring conductivity.

[0010]

Embodiments of the present invention will be described below.

In the embodiment shown in FIG. 1, the present invention is applied to a deep groove ball bearing. This bearing is incorporated in a wafer transfer system of a sputtering apparatus in a semiconductor manufacturing process, and is provided with an inner ring 1 fitted on a rotating shaft (not shown).
, An outer ring 3 fitted to the housing 2, an inner / outer ring 1,
It comprises a plurality of balls 4 interposed between the three, and a retainer 5 for holding the balls 4 at equal circumferential intervals. The outer ring 3 is formed of a carbon-added SiC material (SiC ceramic: hereinafter simply referred to as SiC) (manufactured by Kao Corporation). Inner ring 1 and ball 4 are martensitic stainless steel, for example, SUS440C, and retainer 5 is SUS304.
And so on.

In this bearing, since the outer ring 3 made of SiC having self-lubricating properties serves as a lubricant supply source, it is not necessary to use a lubricant such as PTFE. That is, the lubricating powder (wear powder) of SiC scraped off from the raceway surface of the outer ring 3 by contact with the ball 4 is transferred to the surface of the ball 4, the raceway surface of the inner ring 1, and the pocket wall surface of the retainer 5 and rolled. Since the adhesion coating is formed, the lubrication between the inner ring 1 and the ball 4 and between the ball 4 and the retainer 5 are sufficiently performed. Therefore, in this bearing, there is no fear that the lubricity is reduced due to the high temperature deterioration of the lubricant. In addition, since SiC is a material having excellent wear resistance, excessive lubricating powder that does not form a transfer film is unlikely to be generated, and low dust generation. Of course, since it is a ceramic, the load resistance can be greatly improved as compared with a resin material.

In the embodiment shown in FIG. 2, both the inner ring 1 and the outer ring 3 are formed of SiC. Lubricity is further improved as compared with that shown in FIG. Since SiC in which carbon is dispersed has good electric conductivity, it is most suitable for a place where electric conduction is required between the shaft and the housing 2.

In the embodiment shown in FIG. 3, the ball 4 is made of SiC.
And is most preferable in terms of lubricity.

In the embodiment shown in FIG. 4, both the inner race 1 and the outer race 3 are made of SiC, and the cage 5 is eliminated to form a full ball. In order to ensure heat resistance, the ball 4 is preferably formed of stainless steel or ceramic. Since the number of balls 4 can be increased,
The load resistance is improved. Reference numerals 1a and 3a denote grooves for inserting the balls 4 into the raceway surfaces of the inner and outer races 1 and 3 and are provided on both the outer diameter surface of the inner race 1 and the inner diameter surface of the outer race 3. This configuration may be used in combination with the configuration shown in FIGS.

Although the above is the embodiment of the ball bearing, it goes without saying that the same characteristics can be obtained for the roller bearing.

FIG. 5 shows a rolling bearing (product of the present invention) shown in FIG. 3 and a conventional resin rolling bearing (ball formed of polyimide or copna resin), and a ball made of silicon nitride (Si ₃ N ₄ ). The results of a durability test of the formed bearing are shown. The rotation speed was 50 rpm, and the radial load was 3
kgf is loaded.

As shown in the figure, the product of the present invention exhibited ten times or more the durability of the bearing incorporating the same ceramic Si ₃ N ₄ ball, and exhibited the same characteristics as the resin rolling bearing.

Similar to a rolling bearing for a semiconductor manufacturing facility,
Rolling bearings for liquid crystal panel manufacturing facilities are used in high-temperature, vacuum environments. FIG. 7 is a conceptual diagram of an in-line device in a liquid crystal panel manufacturing facility. The chamber of the in-line apparatus is composed of a plurality of tanks. In the case shown in FIG. 1A, four tanks of an air / vacuum tank 21, a heating tank 22, a processing tank 23, and a cooling tank 24 are provided. Each tank is partitioned by a gate valve (not shown) so as to be openable and closable, and a pair of rails 25 runs in each tank. As shown in FIG. 2B, the rail 25 is for guiding the wheels 26a of the transport device 26, and the transport device 26 driven by appropriate driving means is connected to the rail 25.
To move downstream in each tank. A liquid crystal panel 27 before processing is hung on a table 26b of the transport device 26, and a predetermined process is performed while the liquid crystal panel 27 passes through each tank with the transport device 26. The rolling bearing is used, for example, for the drive unit of the transfer device 26, the support portion of the wheel 26a, and the like. Conventionally, the rolling bearing in this portion uses silver as a solid lubricant. This is because the formation of the Si film on the glass substrate is performed by plasma CVD, and therefore, in addition to lubricity and durability, which are inherent functions of the lubricant, conductivity as an earth circuit is required.

As described above, the rolling bearing (with carbon added) according to the present invention has conductivity, heat resistance, corrosion resistance, and excellent lubricity and durability. It is also suitable as a bearing for manufacturing equipment. However, the present invention is not limited to this, and the same effect can be obtained with ceramics containing a conductive solid lubricant.

FIG. 6 shows that the ball 4 is made of Si as shown in FIG.
The results of endurance tests performed on a deep groove ball bearing formed with C (the present invention: bearing A) and a deep groove ball bearing with a silver coating formed on the surface of the ball 4 (bearing B) are shown. This endurance test
The two test bearings with their shafts supported were tested at room temperature and vacuum of 10 ^-5.
Torr or less, thrust load 10N, rotation speed 2500rpm
And the time when the sum of the friction torques of the two test bearings reached 10 ^-2 Nm was determined as the life. As is clear from FIG. 6, it was found that the bearing A exhibited four times or more the durability as compared with the bearing B.

[0022]

As described above, according to the present invention, since the component having the contact surface that generates rolling friction or sliding friction is formed of SiC material, the load resistance can be improved as compared with the conventional resin bearing. Thus, sufficient durability can be ensured against an impact load. Further, since the SiC material does not absorb water, outgassing is less generated and the surrounding environment is not polluted. Therefore, it is possible to provide a rolling bearing having excellent heat resistance and durability in a special environment where a fluid lubricant such as grease cannot be used, particularly in a vacuum or high-temperature environment.

If carbon is dispersed as an additive in the SiC material, conductivity can be ensured. At this time, C
The conductivity can be arbitrarily changed by changing the amount of addition. This bearing is also suitable for use in liquid crystal panel manufacturing equipment.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing another embodiment of the present invention.

FIG. 4 is a cross-sectional view showing another embodiment of the present invention.

FIG. 5 is a diagram showing the results of a durability test.

FIG. 6 is a diagram showing the results of a durability test.

FIG. 7A is a perspective view of an inline device in a liquid crystal panel manufacturing facility, and FIG. 7B is a perspective view of a transfer device in the inline device.

[Explanation of symbols]

 1 inner ring 3 outer ring 4 ball 5 cage

Claims (3)

[Claims] 1. A rolling bearing, wherein at least one of the components having a contact surface that generates rolling friction or sliding friction is made of a SiC material. 2. The rolling bearing according to claim 1, wherein the SiC material is obtained by dispersing carbon as an additive. 3. The rolling bearing according to claim 2, which is used for a liquid crystal panel manufacturing facility.