JPH07259867A - Solid lubrication rolling bearing - Google Patents

Abstract

PURPOSE:To provide a solid lubrication rolling bearing usable suitably to a device with the clean atmosphere required for a semiconductor manufacturing device or the like and usable even in a vacuum condition by decreasing generation of dust. CONSTITUTION:A rolling bearing 1 sis constituted by turnably holding a plurality of rollers 4 through a cage 5 between inner/outer rings 2, 3. The cage 5 is obtained by compounding 1 to 3vol.% at least one kind of grain Cr, Fe, Ni, Nb of 50mum or less mean grain size sintered and molded in a fluororesin. According to rotating the rolling bearing 1, lubricant grains, scraped off from the cage 5, are transfer moved to raceway surfaces of the inner/outer rings 2, 3, pocket internal peripheral surface of the cage 5 and a rolling surface of the roller, to form a lubricating film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid lubrication rolling bearing, and more particularly to a solid lubrication rolling bearing which is suitable for use in semiconductor manufacturing equipment and other equipment that requires a clean atmosphere and which can be used even in a vacuum state.

[0002]

2. Description of the Related Art A rolling bearing having a structure that uses oil or grease as a lubricant can withstand high speed rotation and a large load because of its excellent lubricity, but on the other hand, oil and grease scatter as the bearing rotates, Alternatively, it has the drawback that it cannot be used when it is exposed to a vacuum condition or a device that requires a clean environment such as a clean room or semiconductor manufacturing device, because it pollutes the external environment of the bearing due to vaporization due to temperature rise. There is.

Therefore, in a clean room, a semiconductor manufacturing apparatus, or a vacuum state, a bearing having a solid lubricating film formed on the raceway surface or the surface of the rolling element is used. As the solid lubricating film, soft metals such as gold, silver and lead, layered compounds such as molybdenum disulfide and tungsten disulfide, fluororesins and the like are generally used. Among these lubricating films, gold, silver, lead and fluorocarbon resin are gradually scraped off from the original film-forming surface by the frictional force generated by the rotation of the bearing, and the wear particles scraped off against each other. Lubrication is performed by transferring to a surface and forming a thin film on the surface.

On the other hand, molybdenum disulfide and tungsten disulfide are layered and have a cleavage plane by themselves, and the cleavage plane gradually wears to exhibit lubricity. Further, the cage is made of a material containing a fluororesin, and the fluororesin particles generated by the sliding contact between the cage and the rolling elements as the bearing rotates are used to remove the fluororesin particles from the bearing inner and outer ring raceways and the cage. A lubrication method is also adopted in which lubrication is performed by transferring to the inner peripheral surface of the pocket and the rolling surface of the rolling element.

[0005]

By the way, in recent years, various electronic devices such as semiconductor devices have tended to be miniaturized and highly integrated, and accordingly, a minute amount of particles (particles).
Has a great influence on the performance and reliability of the product. For this reason, there is a tendency for the demand for low dust generation to increase more and more for bearings used in a clean environment such as semiconductor manufacturing equipment.

However, all of the above solid lubricating films exhibit a self-sacrificing type lubricating action, and therefore the generation of wear particles is unavoidable, and the above requirements cannot be fully met. In the fluororesin cage, the lubricant particles containing the fluororesin are generated due to the sliding contact between the cage and the rolling elements, and the lubricant particles form a transition lubrication film, which causes frictional wear of the cage material. Properties affect the metastasis. That is, when a material that easily wears is used, the lubricant particles are excessively supplied, which not only causes dust generation but also the bearing particles may be locked due to the lubricant particles being caught. On the other hand, if a material that does not easily wear is used, the transfer lubrication film will not be formed and lubrication will be insufficient, and the raceways of the inner and outer rings of the bearing and the rolling surfaces of the rolling elements will wear and cause dust generation. .

Further, especially in the semiconductor manufacturing equipment, the bearing is often used at a relatively low speed, which results in low P.
It is necessary to select a material that can form a transition lubrication film under the V value (load / velocity product) and from the initial stage of rotation, but a satisfactory material has not yet been obtained. Therefore, the present invention is capable of forming a transition lubrication film even at a relatively low PV value and in the initial stage of rotation, is less likely to generate dust, and can be suitably used for an apparatus that requires a clean atmosphere such as a semiconductor manufacturing apparatus. An object of the present invention is to provide a solid lubricating rolling bearing that can be used even in a vacuum state.

[0008]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have blended fluororesin particles with at least one kind of metal particles of Cr, Fe, Ni and Nb. By sinter-molding this into a cage, the amount of dust generated by the rotation of the bearing is extremely smaller than that of the conventional solid lubricating film or fluororesin alone, and it is superior to the conventional one. The inventors have found that lubrication performance can be obtained, and have completed the present invention. That is, according to the present invention, in a rolling bearing in which a plurality of rolling elements are rotatably held via a retainer between an outer race and an inner race, the retainer is C
It is made of a fluororesin in which metal particles selected from at least one of r, Fe, Ni, and Nb are dispersed. Further, the compounding amount of the metal particles is preferably 1 to 30% by volume with respect to the fluororesin.

[0009]

[Operation] In the lubrication system of the present invention, as in the case of the conventional solid lubricating film or fluororesin, as the bearing rotates, the cage and rolling elements make sliding contact with each other to generate lubricant particles. The agent particles transfer to the inner and outer rings of the bearing and the rolling surface of the raceway to perform lubrication. At that time, the reason why the dust generation amount is reduced is presumed to be as follows. When metal deposition is performed on the surface of the fluororesin, fluorine atoms are removed from the surface of the fluororesin, and a mixture of metal fluoride and an unsaturated group or an organometallic complex is formed as an intermediate to allow cross-linking. It is known that the energy increases and the adhesiveness increases (Takaomi Satokawa; “Functional Fluorine Polymer” page 65, Nikkan Kogyo Shimbun).

Therefore, in the present invention as well, it is fully conceivable that the same phenomenon as described above will occur depending on the temperature condition (about 300 to 400 ° C.) during sintering and molding. As a result, at the interface between the fluororesin particles and the Cr, Fe, Ni, Nb particles, a region having a high cohesive energy and a large adhesive force is generated, and therefore, the resin containing this highly adhesive portion is transferred. Due to the excellent adhesiveness of this transfer lubrication film, it is easily retained on the raceways of the inner and outer rings of the bearing and the transfer surfaces of the rolling elements for a long period of time, and as a result, the inner and outer rings that are the main cause of dust generation It is considered that abrasion between the raceway surface and the transfer surface of the rolling element is prevented, the mechanical strength of the cage is increased, and dust generation due to abrasion of the cage is suppressed.

The fluororesin used in the present invention is not particularly limited, and may be polytetrafluoroethylene (hereinafter referred to as PTFE).
Abbreviated), polytrifluoroethylene, polytrifluorochloroethylene, hexafluoropropylene, polyvinyl fluoride, a well-known fluororesin such as polyvinylidene fluoride homopolymer or copolymer can be used. A homopolymer of PTFE is preferable, and for example, a fluororesin commercially available under the registered trade name of "Teflon (DuPont, USA)" or "Polyflon (Daikin Industries, Ltd.)" can be preferably used.

The metal particles blended with the fluororesin are C
r, Fe, Ni, Nb, which may be used alone or as a mixture. Metal particles have an average particle size of 5
It is preferably 0 μm or less, and further 1 to 20 μm
Is preferred. When the average particle size is 50 μm or more, the dispersibility when blended with the fluororesin is poor and uniform wear characteristics cannot be obtained. And these metal particles are mix | blended with the ratio of 1 to 30 volume% with respect to fluororesin. When the content is 1% by volume or less, the effect of improving the film-forming property and adhesion of the above-mentioned transition lubricating film is small, while when it exceeds 30% by volume, the original lubricity of the fluororesin cannot be sufficiently exhibited.

The cage according to the present invention is obtained by blending the fluororesin particles and a predetermined amount of metal particles, filling the mixture in a molding die and sinter molding. The sintering conditions at this time are not particularly limited, and may be the same as the sintering conditions for the fluororesin alone. In addition, various fillers may be added to the cage so long as the lubrication performance is not impaired. For example, for the purpose of enhancing mechanical strength and improving moldability, minerals such as calcium carbonate, talc, and mica, inorganic whiskers such as potassium titanate whiskers and aluminum borate whiskers, glass fibers and asbestos, quartz wool, Inorganic fibers such as metal fibers and those braided into cloth, carbon black, graphite powder, carbon fibers,
Organic fibers such as aramid fibers and polyester fibers, various thermoplastic resins, and the like can be added in appropriate amounts. Further, for the purpose of improving thermal conductivity, carbon fiber, metal fiber, graphite powder, ZnO powder, etc. may be added.

[0014]

EXAMPLES The present invention will be described in detail based on examples. However, the present invention is not limited to the following examples. FIG. 1 is a sectional view of an essential part showing a solid lubrication rolling bearing according to the present invention. The rolling bearing 1 has a plurality of rolling elements 4 arranged between an inner ring 2 and an outer ring 3, and a cage 5 holds the rolling elements 4 at equal intervals along the circumference of the bearing 1. .

(Examples 1 to 4 and Comparative Examples 1 to 7) The present invention is characterized in that the cage 5 is formed of a fluororesin containing metal particles. Therefore, Table 1 below
As shown in (1), the fluororesin was changed to PTFE, the kind of metal particles and the compounding amount thereof were changed to prepare the cage 5, and the dust generation amount was measured by the dust test apparatus shown in FIG.
The average particle size of the metal particles is 10 μm or less, and glass fiber (GF) is added to increase the mechanical strength.
8% by volume was compounded.

[0016]

[Table 1]

In the dust test apparatus, the test bearing 6
Are mounted in pairs in the housing 8 via the spring 7, and are rotated by the rotation introducing machine 9 with a magnetic fluid seal. The dust generated from the test bearing 6 due to the rotation is collected in a funnel 10 provided at the lower part of the device, and then sent to a light scattering type particle counter 11 to count the number of dust particles. The above test conditions are as follows.・ Test bearing 708C ・ Axial load 9.8N ・ Rotation speed 300rpm ・ Atmosphere In the air

The test results are also shown in Table 1. The cages (Examples 1 to 4) in which the fluorine resin (PTFE) was mixed with 7% by volume of each metal particle of Cr, Fe, Ni, and Nb were used. Compared with the cage (Comparative Examples 1 to 4) in which the particles (Mo, W, Ta, Ti) were mixed in the same amount and the cage containing no metal (Comparative Example 5), the initial rotation of the bearing and continuous rotation for 600 hours were performed. It can be seen that the amount of dust generation is extremely small in any of the latter cases. Further, the relationship between the amount of metal particles and the amount of dust generation was examined using a Cr-containing fluororesin as an example. When the amount of Cr was 0.5% by volume (Comparative Example 6)
Also, in the case of the same 31% by volume (Comparative Example 7), it is understood that the amount of dust generation is extremely larger than that in the case of mixing 7% by volume of Cr (Example 1). From this, the optimum blending amount of the above-mentioned metal particles was confirmed.

[0019]

According to the present invention, the fluororesin particles contain C
By mixing at least one kind of metal particles of r, Fe, Ni, and Nb, and sintering and molding the metal particles into a cage, the crystallinity of the fluororesin increases at the interface between the fluororesin and the metal particles. As a result, the film formability and adhesion of the transition lubrication film are improved, the lubrication film is easily formed even in the initial stage of rotation of the bearing, and the mechanical strength of the fluororesin itself is increased. Generation of dust from the cage is also suppressed, and high lubricity and low dust generation can be realized for the entire bearing. Further, since the lubricant particles are continuously generated in association with the rotation of the bearing, it is possible to maintain a stable lubricating action even during long-term use. Therefore, the environment outside the bearing is not polluted, and the bearing can be suitably used for a semiconductor manufacturing apparatus or the like that requires a clean atmosphere, and can also be used in a vacuum state.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts showing an embodiment of a solid lubrication rolling bearing according to the present invention.

FIG. 2 is a schematic view showing a dust test apparatus used in the present invention.

[Explanation of symbols]

 1 Rolling Bearing 2 Inner Ring 3 Outer Ring 4 Rolling Element 5 Cage 6 Test Bearing 7 Spring 8 Housing 9 Rotation Introducer with Magnetic Fluid Seal 10 Rot 11 Particle Counter

Claims (2)

[Claims] 1. A rolling bearing in which a plurality of rolling elements are rotatably held between an outer ring and an inner ring via a cage, wherein the cage is made of at least one of Cr, Fe, Ni, and Nb. A solid lubricating rolling bearing, which is made of a fluororesin in which selected metal particles are dispersed. 2. The compounding amount of the metal particles is 1 to 30% by volume with respect to the fluororesin.
The solid lubricating rolling bearing described.