JP2006046531A - Thin rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin rolling bearing less liable to the generation of dust and outgas and lubricant leakage, superior in durability and maintenance-free. <P>SOLUTION: The thin rolling bearing 1 has a bearing sectional ratio of 0.2 or smaller. To each of the raceway surface 11a of an inner ring 11 and the raceway surface 12a of an outer ring 12, a lubricating coating is applied which is formed of a lubricant that fluororesin is mixed in base oil containing at least one type of fluorine oil, alkylated cyclopentane, polyphenyl ether and ester oil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thin wall rolling bearing.

Conventionally, thin rolling bearings used in semiconductor-related devices, robots, and the like are often used as open types, and some are used as sealed types. In addition, a thin wall rolling bearing means a bearing cross-sectional ratio α of 0.2 or less. The bearing section ratio α is defined by the following mathematical formula.
α = (D−d) / (2 × D _PW )
In the above formula, D is the bearing outer diameter, d is the bearing inner diameter, and D _PW is the center diameter of the rolling element of the bearing.

  Grease is mainly used to lubricate such thin-walled rolling bearings. However, in the case of open-type thin-walled rolling bearings, the grease existing on the raceway surface is retained inside the bearing by the cage and rolling elements when the bearing rotates. There was a risk of being pushed out from the pipe or leaking out due to centrifugal force. Further, even in the case of a sealed thin rolling bearing, there is a risk that grease may leak from between the seal lip and the outer diameter surface of the inner ring.

Therefore, Patent Document 1 discloses a thin-walled rolling bearing in which a solid lubricant is sealed inside to solve the above-described problems and make it maintenance-free.
JP 2003-329049 A

  However, in the case of using, as a lubricant, a product prepared by firing a mixture of a polymer material mainly composed of polyolefin and a lubricant, leakage of the lubricant hardly occurs, but the absolute amount of the lubricant component is Because there are many, there was a problem that a large amount of outgas was easily generated. Further, in the case of a solid lubricant, the lubricant is supplied when the lubricant comes into sliding contact with the rolling elements and the raceway surface. In addition, there is a problem that the amount of dust generation increases due to this sliding contact. Had.

When a lubricant film made of a solid lubricant such as molybdenum disulfide (MoS ₂ ), graphite, hexagonal boron nitride (h-BN), or fluorinated graphite is coated on the raceway surface, there is little outgas, but wear tends to occur. There was a risk that durability would be insufficient.
Accordingly, the present invention solves the above-mentioned problems of the prior art, is less likely to generate dust and outgas, and less likely to cause lubricant leakage, and is a thin-walled rolling bearing that has excellent durability and can be made maintenance-free. It is an issue to provide.

  In order to solve the above problems, the present invention has the following configuration. That is, the thin-walled rolling bearing of claim 1 according to the present invention includes an inner ring, an outer ring, and a plurality of rolling elements that are freely rollable between the inner ring and the outer ring, and a bearing sectional ratio is 0. In a thin rolling bearing of 2 or less, a base oil containing at least one of fluorine oil, alkylated cyclopentane, polyphenyl ether, and ester oil is provided on at least one of the raceway surface of the inner ring and the raceway surface of the outer ring. A lubricating film made of a lubricant mixed with a fluororesin is coated.

  If such a lubricating film is provided, contact between metals is suppressed during rolling operation of the rolling elements, and low dust generation and stable lubricity are exhibited. That is, since the lubricating film is made of a lubricant in which a fluororesin is mixed with a base oil, the lubricating oil (base oil) is not exhausted from the raceway surface, and stable lubricity is exhibited. In addition, surplus lubricating oil (base oil) is trapped in the fluororesin, so that it generates less dust and the lubricant does not leak easily. The fluororesin is more preferably powdered.

A thin-walled rolling bearing according to a second aspect of the present invention is the thin-walled rolling bearing according to the first aspect, wherein the lubricating film has a thickness of 0.1 μm to 10 μm.
In order to reduce the dust generation amount and the outgas amount, it is preferable that the lubricating film has a small film thickness, but in order to improve the durability of the thin rolling bearing, it is preferable that the film thickness is large. Considering the balance between the two, it is preferable that the thickness of the lubricating film is 0.1 μm or more and 10 μm or less.

  The thin-walled rolling bearing of the present invention is less likely to generate dust and outgas, and less likely to leak a lubricant, and has excellent durability.

Embodiments of a thin-walled rolling bearing according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of a thin rolling bearing according to the present invention.
1 has an inner ring 11 having a raceway surface 11a on an outer peripheral surface, an outer ring 12 having a raceway surface 12a facing the raceway surface 11a on an inner peripheral surface, and a rolling motion between both raceway surfaces 11a and 12a. A plurality of rolling elements (balls) 13 that are freely arranged, and a cage 14 that holds the plurality of rolling elements 13 between the inner ring 11 and the outer ring 12 are provided. Moreover, this thin rolling bearing 1 has a bearing cross-sectional ratio α represented by the above-described mathematical formula of 0.2 or less.

Furthermore, at least one of the raceway surfaces 11a and 12a is a lubricating film made of a lubricant obtained by mixing a fluororesin with a base oil containing at least one of fluorine oil, alkylated cyclopentane, polyphenyl ether, and ester oil. (Not shown) is covered.
Since the thin rolling bearing 1 of the present embodiment is lubricated with the lubricating film as described above, dust generation and outgas hardly occur even without a seal or the like, and the lubricant does not easily leak. Furthermore, it has excellent durability and can be made maintenance-free. Therefore, it can be suitably used even in a vacuum environment and a clean environment. Moreover, since the rotational resistance of the bearing is extremely small as compared with the case where lubrication is performed using grease, high-precision rotational performance can be obtained.

In addition, it is preferable that a minimum necessary lubricating film is formed on the raceway surface of the inner ring, the raceway surface of the outer ring, the rolling surface of the rolling element, and the sliding portion of the cage. By doing so, it is possible to suppress dust generation due to scattering of excess lubricating oil (base oil). Further, if a lubricating oil (base oil) having a low vapor pressure is used, generation of outgas can be suppressed.
The type of fluororesin is not particularly limited, but polytetrafluoroethylene (hereinafter referred to as PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene / ethylene copolymer ( ETFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and polychlorotrifluoroethylene (PCTFE) are preferable. Among these, PTFE is most preferable.

Further, the fluororesin is more preferably in a powder form, and the particle size is preferably in the submicron order to the micron order. Further, the thickness of the lubricating film is not particularly limited, but is preferably 0.1 μm or more and 10 μm or less in consideration of the balance between dust generation and outgassing suppression and bearing durability.
Next, the base oil will be described. Examples of the fluorine oil include a fluoropolyether polymer and a polyfluoroalkyl polymer, and may further contain a derivative thereof (having a functional group).

  As the fluoropolyether polymer, a polymer having a repeating unit represented by the following chemical formula (I) is preferable. The number average molecular weight is preferably 1000 or more and 50000 or less. As the derivative of the fluoropolyether polymer, one in which a functional group having a high affinity for a metal is bonded to the above fluoropolyether polymer is preferable. Examples of functional groups include epoxy groups, amino groups, carboxyl groups, hydroxyl groups, mercapto groups, sulfone groups, and ester groups.

（Ｉ）

(I)

  In addition, examples of the polyfluoroalkyl polymer include those represented by the following chemical formula (II). Y in the formula is a functional group having a high affinity for the same metal as described above.

（II）

(II)

  As the polyfluoroalkyl polymer, in addition to those represented by the chemical formula (II), for example, those represented by the following chemical formulas (III) and (IV) can also be suitably used.

（III ）

(III)

（IV）

(IV)

  Examples of commercially available fluorine oils having such functional groups include Crytox 157FSL, 157FSM, 157FSH manufactured by DuPont, demnam modified products SA, SH, SY-3, SP manufactured by Daikin Industries, Ltd. Examples include Fomblin Z DEAL, Z DIAC, Z DISCO, Z DOL, and Z DOL TX2000 manufactured by Isorexis Corporation.

  Moreover, as perfluoropolyether (PFPE) oil which is a kind of fluoropolyether polymer, commercially available products can be used. For example, S-65, S-100, S manufactured by Daikin Industries, Ltd. -200, Fomblin Z-25, Z-60, 40/11 manufactured by Solvay Solexis, Krytox 16140 manufactured by DuPont, and the like.

  Further, as the alkylated cyclopentane, for example, tri (2-octyldodecyl) cyclopentane (for example, Synthetic Oil 2001A manufactured by Nye Lubricants), tri-n-octylcyclopentane, tetra-n-octylcyclopentane, penta- Examples thereof include n-octylcyclopentane, tri-n-nonylcyclopentane, penta-n-decylcyclopentane, penta-n-dodecylcyclopentane, and tetra-2-ethylhexylcyclopentane. Since such an alkylated cyclopentane has a low vapor pressure even in a vacuum, even when the thin-walled rolling bearing of the present invention is used in a vacuum, the base oil hardly evaporates and has a low outgas.

Furthermore, examples of the polyphenyl ether include tetraphenyl ether, pentaphenyl ether, alkyl diphenyl ether, monoalkyl triphenyl ether, monoalkyl tetraphenyl ether, and dialkyl tetraphenyl ether. Since such polyphenyl ether has a low vapor pressure and excellent heat resistance, the thin-walled rolling bearing of the present invention can be used in a vacuum or in a high temperature environment.
Furthermore, as ester oil, NyeTorr5101 made from Nye Lubricants is mention | raise | lifted, for example.

  For the inner ring 11, the outer ring 12, the rolling element 13, and the cage 14, any metal material that is generally used as a bearing material can be used without any problem. For example, a material obtained by subjecting a corrosion-resistant metal material such as martensitic stainless steel such as JIS standard SUS440C or precipitation hardening stainless steel such as JIS standard SUS630 to appropriate curing heat treatment. For light load applications, those obtained by subjecting austenitic stainless steel such as JIS standards SUS304 and SUS316 or a titanium alloy to surface hardening treatment are suitable.

  The retainer 14 is preferably made of brass, titanium, or the like in addition to the above metal material, but can also be made of a resin material. Examples of the resin material include fluorine resins such as PTFE and ETFE, and engineering plastics such as polyether ether ketone resin (PEEK), polyphenylene sulfide resin (PPS), polyether sulfone resin (PES), and polyamide resin.

These resin materials may contain a fibrous filler that improves mechanical strength, heat resistance, dimensional stability, and the like. The type of fibrous filler is not particularly limited. For example, aluminum borate whisker, potassium titanate whisker, carbon whisker, aramid fiber, aromatic polyimide fiber, liquid crystalline polyester fiber, graphite whisker, glass fiber, Examples thereof include carbon fiber, boron fiber, silicon carbide whisker, silicon nitride whisker, alumina whisker, aluminum nitride whisker, and wollastonite.
The type of the cage is not particularly limited, and may be a corrugated cage, a crown-shaped cage, a machined cage, or the like. The retainer 14 may not be provided.

  In addition, this embodiment shows an example of this invention, Comprising: This invention is not limited to this embodiment. For example, in the present embodiment, a deep groove ball bearing has been described as an example of a thin rolling bearing, but the present invention can be applied to various types of rolling bearings. For example, radial rolling bearings such as angular contact ball bearings, self-aligning ball bearings, cylindrical roller bearings, tapered roller bearings, needle roller bearings, and self-aligning roller bearings, and thrust types such as thrust ball bearings and thrust roller bearings This is a rolling bearing.

〔Example〕
The present invention will be described more specifically with reference to the following examples. A rolling bearing (Example) having almost the same configuration as the thin-walled rolling bearing 1 described above and a conventional thin-walled rolling bearing (comparative example) filled with fluorine grease were prepared, and their dust generation properties were evaluated and compared. . In addition, the thin-walled rolling bearing of an Example and a comparative example is the Nippon Steel Seiko Co., Ltd. designation number NBX15206 (inner diameter d: 152.4mm, outer diameter D: 165.1mm, width: 6.35mm, the center diameter of a rolling element) D _PW : 158.75 mm).

  First, the thin-walled rolling bearing of the embodiment will be described. Assemble the inner ring, outer ring, rolling elements, and cage to make a rolling bearing, and degrease and clean. Then, a lubricant, which will be described later, is supplied to the vicinity of the rolling element with a dropper or the like, and the rolling bearing is rotated several times to slide the inner ring raceway surface, the outer ring raceway surface, the rolling element rolling surface, and the cage sliding. Apply lubricant to the area. The method for attaching the lubricant is not limited to the coating method as described above, and the lubricant may be attached by a spray method or a dipping method.

  When the rolling bearing coated with the lubricant is heated at 100 to 140 ° C. for 30 minutes to remove the diluted solvent contained in the lubricant, the inner ring raceway surface, the outer ring raceway surface, the rolling element rolling surface, and the cage A lubricating film made of a lubricant is formed on the sliding portion. In addition, it is preferable to perform a baking process because the amount of outgas can be further reduced. The conditions for the baking treatment are, for example, a pressure of 10 Pa or less, a temperature of 100 ° C. or more, and a treatment time of 4 hours or more.

  Next, the lubricant used for the thin-walled rolling bearing of the example will be described. The lubricant was prepared by mixing 60 parts by mass of tri (2-octyldodecyl) cyclopentane (Synthetic Oil 2001A manufactured by Nye Lubricants) with 40 parts by mass of PTFE powder having a particle size of 1 μm or less, and 1 part by mass of this mixture and hexane. , 99 parts by mass of a diluting solvent such as Asahi Clin AK-225 (Asahi Glass Co., Ltd.). As the PTFE powder, a dispersion in which PTFE powder is dispersed in a solvent (DuPont's dry film RA / IPA) is used. used.

Next, a dust generation evaluation method will be described. The thin-walled rolling bearings of the example and the comparative example were assembled in an apparatus as shown in FIG.
Axial load: 18N
Moment load: 1 N · m
Actuator swing angle: -60 ° to + 60 °
Actuator swing speed: 40 cycles / min
The test results are shown in the graph of FIG. In addition, the numerical value of the dust generation amount shown in the graph is shown as a relative value when the dust generation amount of the thin rolling bearing of the embodiment is 1. As can be seen from the graph, the thin-walled rolling bearing of the example had an extremely low dust generation amount of 1/20 compared with the thin-walled rolling bearing of the comparative example in which fluorine grease was sealed.

  Since the thin-walled rolling bearing of the present invention can be suitably used even in a vacuum environment and a clean environment, it can be suitably used for, for example, transport devices and transport robots of semiconductor manufacturing equipment, liquid crystal panel manufacturing equipment, hard disk manufacturing equipment, etc. It is.

It is a longitudinal cross-sectional view which shows one Embodiment of the thin rolling bearing which concerns on this invention. It is the schematic explaining the structure of the apparatus which evaluates dust generation property. It is a graph which shows the evaluation result of dust generation property.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thin rolling bearing 11 Inner ring 11a Raceway surface 12 Outer ring 12a Raceway surface 13 Rolling element

Claims (2)

In a thin-walled rolling bearing comprising an inner ring, an outer ring, and a plurality of rolling elements arranged so as to be able to roll between the inner ring and the outer ring, and having a bearing sectional ratio of 0.2 or less,
At least one of the raceway surface of the inner ring and the raceway surface of the outer ring comprises a lubricant in which a fluororesin is mixed with a base oil containing at least one of fluorine oil, alkylated cyclopentane, polyphenyl ether, and ester oil. Thin-walled rolling bearing characterized by covering with a lubricating film.   The thin-walled rolling bearing according to claim 1, wherein the lubricating film has a thickness of 0.1 μm to 10 μm.

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