JP3838273B2 - Rolling bearing and method for forming lubricating thin film of rolling bearing - Google Patents

Description

【００２３】
【化２】

【００２４】
【化３】

【００２５】
前述の薄膜５として、より詳しくは、パーフルオロポリエーテル（ＰＦＰＥ）あるいはその誘導体との混合物、具体的に例えばモンテカチーニ社の商品名フォンブリン（FONBLIN）Ｙスタンダード、フォンブリンエマルジョン（FE20、EM04など）またはフォンブリンＺ誘導体（FONBLIN Z DEAL、FONBLIN Z DIAC、FONBLIN Z DISOC、FONBLIN Z DOL、FONBLIN Z DOLTX2000、FONBLIN Z TETRAOLなど）が好適に用いられる。これら例示したものは、いずれも濃度が濃く、金属に対する親和性がきわめて悪いので、そのままでは膜状に付着させることが困難である。そのため、薄膜５の形成は、下記するような方法が適用される。なお、前述のフォンブリンＺ誘導体は、真空環境で用いると、真空排気系に対して害を及ぼす可能性があるので、使用環境を考慮するのが好ましい。
【００２６】
次に、前述の潤滑薄膜５の形成方法の一例を説明する。
【００２７】
（ａ） 内・外輪１，２、転動体３および保持器４をそれぞれ組み立てて転がり軸受Ａの完成状態としてから、この内・外輪１，２間で転動体３の存在する箇所において、用意した潤滑油をスポイドなどにより数滴、注入し、数回回転させることにより、潤滑油を膜状に内・外輪１，２、転動体３および保持器４の転動、摺動部位に被覆させる（供給処理）。この潤滑油の供給はスプレーより塗布してもよいし、また、潤滑油の貯溜槽に浸漬してもよい。ここで用意した潤滑油は、例えばフォンブリンエマルジョンＦＥ２０（フォンブリン濃度２０ｍａｓｓ％の）を適当な希釈溶媒でフォンブリン濃度を０．２５ｍａｓｓ％にまで希釈したものである。なお、前述の希釈溶媒は、メタノール溶液、アルコール溶液や水などの揮発性のものとすることができる。
【００２８】
（ｂ） 前記潤滑油を塗布した転がり軸受Ａの全体を４０〜５０度で約３分間加熱し、潤滑油に含むメタノール溶液など溶媒を除去する（乾燥処理）。
【００２９】
（ｃ） この後、軸受使用環境での雰囲気温度に応じて、例えば１５０〜３００度で１５〜３０分間、加熱する（仕上げ乾燥処理）。
【００３０】
なお、（ａ）、（ｂ）は必要に応じて数回繰り返すようにしてもよく、最終的には、潤滑薄膜５の膜厚を例えば０．２μｍ以下に設定する。
【００３１】
このようにすれば、転がり軸受Ａの構成要素において互いに接触する部位に潤滑薄膜５を好適な膜厚で形成することができる。そして、前述したように溶媒を除去しておけば、転がり軸受Ａの動作時の不要な発塵成分がなくなる。また、潤滑薄膜５の膜厚をきわめて薄く設定しているから、油成分による発塵もほとんどなくなる。さらに、最終の加熱処理により、使用環境での発塵をもなくせるようになる。
【００３２】
そして、上述した潤滑油について、▲１▼希釈濃度と転がり軸受における回転初期の発塵量との関係、▲２▼薄膜５を形成するときの供給処理および乾燥処理の繰返回数（ディッピング回数）と転がり軸受における回転初期の発塵量との関係、▲３▼誘導体分子の有無と発塵寿命との関係をそれぞれ調べているので、説明する。
【００３３】
この試験では、図２に示す装置を用いている。図中、５０，５０は試験対象となる転がり軸受、５１は回転軸、５２はケーシング、５３は磁性流体シール、５４は発塵個数計測装置（パーティクルカウンター）、５５は計測結果記録機（レコーダ）、５６は軸受ハウジング、５７はアキシャル荷重付加用のコイルバネである。
【００３４】
試験軸受５０は、呼び番号ＳＥ６０８（φ８×φ２２×７）で、内・外輪および転動体をＪＩＳ規格ＳＵＳ４４０Ｃ、保持器（波形タイプ）をＪＩＳ規格ＳＵＳ３０４としている。
【００３５】
試験条件は、下記のとおり。
【００３６】
・回転速度：２００ｒｐｍ
・荷重 ：アキシャル荷重（２０Ｎ，１００Ｎ）
・雰囲気 ：大気、クリーンベンチ内（クラス１０）
・環境温度：室温
・計測条件：粒子径０．１μｍ以上、０．３μｍ以上の発塵粒子数
▲１▼ 試験時間は、回転初期１０時間（ｈ）とする。潤滑油は、フォンブリンエマルジョンＦＥ２０のフォンブリン濃度（ｍａｓｓ％）を、“５”、“２”、“０．５”、“０．２５”の４段階に希釈溶媒（エチルアルコールまたは水）で希釈したものを用いている。薄膜５の形成方法は、前述した方法とする。但し、供給処理および乾燥処理を二回繰り返してから、仕上げ乾燥（１７０℃、１５分間）を施す。
【００３７】
結果は、下記表１に示すように、０．２５ｍａｓｓ％とした場合の発塵量が、他に比べて格段に少なくなっている。
【００３８】
【表１】

【００３９】
▲２▼ 試験時間は、回転初期１０時間（ｈ）とする。供給処理および乾燥処理の繰り返し回数は、“４”、“３”、“２”、“１”の４段階としている。潤滑油は、前述の▲１▼で述べたもの（フォンブリンエマルジョンＦＥ２０のフォンブリン濃度を０．２５ｍａｓｓ％に希釈したもの）を用いる。
【００４０】
結果は、下記表２に示すように、繰り返し回数を２回以下とした場合の発塵量が、他に比べて格段に少なくなっている。
【００４１】
【表２】

【００４２】
上記▲２▼での繰り返し回数別の薄膜５それぞれの膜厚について、転動体の質量増加量に基づいて推定した。この場合、薄膜５を得た後で、転がり軸受を分解し、転動体の質量増加量を測定している。結果を、下記表３に示す。
【００４３】
【表３】

【００４４】
・膜の比重：１．８８ｇ／ｃｍ³
・転動体の表面積：０．４９５ｃｍ²
この結果と、上記▲１▼，▲２▼の結果とに鑑み、薄膜５の膜厚については０．２μｍ以下とするのが好ましいと言える。但し、０．２μｍ以下と言えどもあまり薄くしすぎると、金属材どうしの摺接部位における潤滑性が低下するおそれがあるので、０．２μｍ以下でその近傍に設定するのが好ましいと言える。
【００４５】
▲３▼ 試験時間を発塵寿命とするので、限定しない。発塵寿命は、二つの軸受５０，５０からの総発塵量が１０００個／０．１ｃｆ以上となる状況を、連続１０回測定した時点までの時間を計測している。なお、測定は６分間隔とする。
【００４６】
試験軸受は、三つの実施例品、比較品、従来品を用いている。実施例品は、フォンブリンエマルジョンＦＥ２０を希釈溶媒（エチルアルコールまたは水）でフォンブリン濃度を０．２５ｍａｓｓ％にまで希釈した潤滑油を用いており、同一仕様のものを三つ用いている。比較品は、フォンブリンＺ２５を希釈溶媒（ガルデンＳＶ９０）でフォンブリン濃度を０．２５ｍａｓｓ％にまで希釈した潤滑油を用いている。つまり、実施例品の潤滑油は誘導体を含み、比較品の潤滑油は誘導体を含まない。従来品は、内・外輪および保持器全面にコーティング膜を形成したものとする。このコーティング膜は、熱硬化性合成樹脂からなるバインダー中にポリテトラフルオロエチレン（ＰＴＦＥ）を分散混合したものである。
【００４７】
結果は、下記表４に示すように、アキシャル荷重を１００Ｎとした場合、実施例品が比較品および従来品に比べ、約１０倍と耐荷重性が大幅に向上しており、特に高荷重条件下で用いる場合に優位であると言える。ちなみに、従来品で用いたコーティング膜は、他の一般的な固体潤滑剤のコーティング膜に比べると発塵量が格段に少ない。このような結果が得られる理由は、本実施例品である潤滑薄膜５が流動性を有していて、内・外輪、転動体および保持器の摺接が常に潤滑油を介する状態となり、従来品である固体潤滑剤のコーティング膜のような剥離や欠落の他、摩耗が発生しないからと言える。
【００４８】
【表４】

【００４９】
なお、実施例品と比較品とにおける回転初期１０時間の発塵量は、下記表５に示すように、ほとんど差がなかった。
【００５０】
【表５】

【００５１】
この▲３▼の結果より、薄膜５を形成する潤滑油としても、誘導体分子を含むものとするのが特に耐荷重性において優れることが判った。
【００５２】
以上▲１▼〜▲３▼の各試験における結果が示すように、薄膜５としては、使用潤滑油の性状、薄膜形成方法や生成後の膜厚などを、ある程度、特定することが、発塵性、耐荷重性において重要となることが判るであろう。
【００５３】
ところで、前述した潤滑油（フォンブリンエマルジョンＦＥ２０を希釈したもの）からなる薄膜５を形成した転がり軸受Ａにおいて、内・外輪１，２および転動体３を耐食性金属材料としたものの場合、偏荷重などが作用したりすると、はなはだしい場合に摺接部位において腐食が発生する可能性があると考えられる。というのは、偏荷重などが作用したときに、薄膜５の一部がかきとられてしまうと、内・外輪１，２および転動体３の表面（金属面上の酸化面）が露出することになって、ここで金属材どうしの凝着摩耗が発生するようになるが、このような凝着摩耗が発生すると、内・外輪１，２および転動体３の表面でも新生面（酸化されていない純粋の金属面）が露出することになるため、この新生面が潤滑油の成分中のフッ素と反応し、腐食されることが起こりうるのである。また、凝着摩耗時の触媒作用によりフッ素成分のガスを発生することも起こりうる。これに対して、転がり軸受Ａにおいて少なくとも転動体３をセラミックス材とすれば、前述したような凝着摩耗が発生せずに済むので、前述したような腐食やガス発生といった心配がなくなる。したがって、転がり軸受Ａの構成を、少なくとも転動体３についてセラミックス材で形成したものの方がすべて金属材とするものに比べて優れていると言える。
【００５４】
なお、本発明は上記実施例のみに限定されない。例えば、実施例では、軸受形式として深溝型玉軸受を引用しているが、その他の種類の転がり軸受に本発明を適用できる。
【００５５】
【発明の効果】
本発明の転がり軸受では、従来の固体潤滑剤のコーティング膜のような剥離や欠落の他、摩耗がない流動性を有する潤滑薄膜を用いるから、比較的大きなアキシャル荷重がかかる状況でも、軸受構成要素間での摺接が金属どうしの無潤滑の接触状態とならず、常に潤滑油を介して摺接する状態となり、発塵が格段に少なくなって潤滑性が格段に向上するようになる。このように、潤滑薄膜からの発塵だけでなく、軸受構成要素からの発塵を抑制できるとともに、動作安定性の向上に貢献できる。
【００５６】
したがって、例えば半導体製造過程のように高精度な加工が要求されるところに本発明の転がり軸受を用いると、清浄雰囲気を阻害しにくくなるので、半導体製造品の歩留まり向上に貢献できる。
【００５７】
特に、薄膜の膜厚を特定すると、発塵性と潤滑性との両方に関して優れた結果が得られるようになる。この膜厚については、薄膜を形成するベースとなる潤滑油を特定すれば、容易に設定できるようになる。
【００５８】
また、本発明の転がり軸受の潤滑薄膜形成方法では、油膜形成対象部位に、官能基を有する含フッ素重合体からなる潤滑油の薄膜を発塵とならない量でかつ潤滑作用を妨げない量として良好に付着させることができるから、発塵がほとんどなくて、しかも軸受構成要素間での潤滑作用を安定的に得ることができて、軸受の長寿命化を達成できるようになる。
【図面の簡単な説明】
【図１】本発明の一実施例にかかる転がり軸受の上半分の縦断面図。
【図２】同軸受の発塵量測定に用いる試験装置の概略図。
【符号の説明】
Ａ 転がり軸受
１ 内輪
２ 外輪
３ 転動体
４ 保持器
５ 潤滑薄膜[0001]
[Industrial application fields]
The present invention relates to a rolling bearing and a method for forming a lubricating thin film of the rolling bearing, and more particularly to a rolling bearing suitable for use in a vacuum environment, a clean environment, a corrosive environment, or the like where normal grease or oil cannot be used.
[0002]
[Prior art]
As the aforementioned environment, for example, a conveyance system arranged inside a semiconductor manufacturing apparatus can be cited. In such an environment, if grease is used as a lubricant for a rolling bearing, the oil content of the grease evaporates. This causes problems such as deterioration of the lubrication function and contamination of the usage environment.
[0003]
In such a case, conventionally, mainly at least one of the raceway surface of the raceway, the surface of the rolling element, or the pocket surface of the cage, soft metal such as gold, silver, lead, copper, carbon, molybdenum disulfide, etc. The solid lubricant is coated in the form of a film.
[0004]
[Problems to be solved by the invention]
By the way, in the coating film made of the above-described solid lubricant, the coating film is peeled off little by little by contact with the rolling element. However, although the dust generation state is at a lower level than when using grease, it is not suitable particularly in a clean environment. Is a level. In particular, the amount of dust generation increases under high load conditions.
[0005]
In addition, the applicant of the present application coats the bearing ring and the cage with a solid lubricant in which a fluorine-based resin is mixed in a binder. In this case, the dust generation is orders of magnitude higher than that of the conventional example. Can be reduced. However, even with a coating film, in a situation where a relatively large axial load is applied, dust generation due to abrasion is remarkably increased in addition to peeling and missing, and the dust generation life is shortened.
[0006]
In addition, if the coating film is peeled off or missing as described above, the lubricating action between the bearing components decreases, making it easier to adhere, such as contact between metals, and promoting wear of the bearing components. For example, there is a problem in terms of life.
[0007]
Further, in an environment where corrosive gas exists, as described above, the coating film is peeled off and the bearing components at the missing portion are corroded.
[0008]
Accordingly, an object of the present invention is to suppress dust generation and improve lubricity in a rolling bearing so that a long life can be achieved.
[0009]
[Means for Solving the Problems]
The rolling bearing of the present invention is a rolling bearing in which the inner and outer rings are made of metal, and a lubricating thin film made of a fluoropolymer having a functional group is formed on at least the raceway surface thereof. The thin film has fluidity, and is formed of a lubricating oil obtained by diluting a mixture of perfluoropolyether (PFPE) and a derivative thereof with a diluting solvent .
[0011]
In addition, it is preferable to set the above-mentioned thin film in the vicinity of 0.2 μm or less. The thin film in this case can be formed of a lubricating oil obtained by diluting a mixture with perfluoropolyether (PFPE) or a derivative thereof to 0.25 mass% with a diluent solvent.
[0012]
The method for forming a lubricating film having fluidity of a rolling bearing according to the present invention includes a perfluoropolyether (PFPE) formed on at least rolling and sliding portions of each element in a rolling bearing assembled with inner and outer rings, rolling elements and a cage. ) And a derivative thereof mixture with a diluent solvent, and a step of adhering in a film form, and a step of removing the mixture contained therein by heating the film-form lubricant.
[0013]
[Action]
In the rolling bearing of the present invention, as a lubricating element, a lubricating thin film having fluidity that does not cause wear, in addition to peeling and missing, like a coating film of a conventional solid lubricant. Moreover, since this lubricating thin film is not in the form of enclosing lubricating oil inside the rolling bearing as in the prior art, there is no fear of external leakage thereof.
[0014]
In such a lubricating thin film of the present invention, even when a relatively large axial load is applied, the sliding contact between each component does not become a non-lubricated contact state between the metals, and always stops on the entire surface of the component. Since the state of adhesion is maintained, the rolling and sliding of each bearing component is always performed via the lubricating oil, and in particular, the lubricating action between the rolling elements is stably maintained. Become.
[0015]
In particular, when the film thickness of the thin film is specified, excellent results regarding both dust generation and lubricity can be obtained. About this film thickness, if the lubricating oil used as the base which forms a thin film is specified, it will become easy to set.
[0016]
Further, in the method for forming a lubricating thin film of a rolling bearing according to the present invention, the lubricating thin film made of a fluoropolymer having a functional group is applied to the oil film forming target portion with a film thickness excellent in both dust generation and lubricity. It is possible to form well.
[0017]
【Example】
Hereinafter, 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.
[0018]
In the figure, A is a rolling bearing such as a deep groove ball bearing, 1 is an inner ring, 2 is an outer ring, 3 is a spherical rolling element, 4 is a corrugated cage made of press, and 5 is a thin film of lubricating oil.
[0019]
Specifically, the inner / outer rings 1, 2, rolling elements 3 and cage 4 are made of a corrosion resistant material. Examples of the corrosion resistant material include a metal material obtained by subjecting a martensitic stainless steel such as JIS standard SUS440C to a suitable hardening heat treatment to a precipitation hardening type stainless steel such as JIS standard SUS630. In light load applications, for example, austenitic stainless steel such as JIS standard SUS304 may be used.
[0020]
The corrosion resistant material for the inner / outer rings 1 and 2 and the rolling element 3 can be a ceramic material in addition to a metal material. As the ceramic material, yttria (Y ₂ O ₃ ) and alumina (Al ₂ O ₃ ) are used as sintering aids, and aluminum nitride (AlN), titanium oxide (TiO ₂ ), spinel (MgAl ₂ O), as appropriate. ₄ ) In addition to silicon nitride (Si ₃ N ₄ ) mainly used, alumina (Al ₂ O ₃ ), silicon carbide (SiC), zirconia (ZrO ₂ ), aluminum nitride (AlN), etc. are used. be able to. In addition to the JIS standard SUS304, for example, brass or titanium material is suitably used for the retainer 4, but a synthetic resin material can also be used. Examples of the synthetic resin material include fluorine-based resins such as polytetrafluoroethylene (hereinafter abbreviated as PTFE) and ethylenetetrafluoroethylene (ETFE), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), and polyether. Engineering plastics such as Sulphone (PES) and nylon 46 can also be used. Reinforcing fibers such as glass fibers may be added to these resins. As a type of the cage 4, in addition to the corrugated shape, a crown shape or a hollow shape can be used.
[0021]
The lubricating thin film 5 is made of a fluorine-containing polymer having a functional group, and is coated on the rolling and sliding portions of the inner / outer rings 1 and 2, the rolling element 3 and the cage 4 as shown in the figure. The fluoropolymer is preferably a fluoropolyether polymer or a polyfluoroalkyl polymer. The fluoropolyether polymer includes a unit represented by a general formula -C _X F _2X -O- (where X is an integer of 1 to 4) as a main structural unit, and each of the polymers has a number average molecular weight of 1000 to 50000 To do. Examples of the polyfluoroalkyl polymer include those represented by the following chemical formula 1. The functional group described above is preferably one having a high affinity for metals (for example, an epoxy group, amino group, carboxyl group, hydroxyl group, mercapto group, isocyanate group, sulfone group or ester group). , 3 are listed. Such fluorine-containing polymers may be used alone or in combination of two or more. In that case, it is desirable to consider that the combined groups react with each other to increase the molecular weight of the polymer so that a thin film with higher wear resistance can be obtained.
[0022]
[Chemical 1]

[0023]
[Chemical 2]

[0024]
[Chemical 3]

[0025]
More specifically, the thin film 5 is a mixture of perfluoropolyether (PFPE) or a derivative thereof, specifically, for example, Montecatini's trade name FONBLIN Y standard, fomblin emulsion (FE20, EM04, etc.) Alternatively, fomblin Z derivatives (FONBLIN Z DEAL, FONLIN Z DIAC, FONLIN Z DISOC, FONLIN Z DOL, FONLIN Z DOLTX2000, FONLIN Z TETRAOL, etc.) are preferably used. All of these exemplified substances have a high concentration and extremely low affinity for metals, so that it is difficult to attach them as they are. Therefore, the following method is applied to form the thin film 5. In addition, since the above-mentioned fomblin Z derivative may be harmful to the vacuum exhaust system when used in a vacuum environment, it is preferable to consider the usage environment.
[0026]
Next, an example of a method for forming the lubricating thin film 5 will be described.
[0027]
(A) After the inner and outer rings 1 and 2, the rolling elements 3 and the cage 4 are assembled to complete the rolling bearing A, the rolling elements 3 are prepared between the inner and outer rings 1 and 2. By injecting a few drops of lubricating oil with a spoid or the like and rotating it several times, the lubricating oil is coated on the inner and outer rings 1 and 2, the rolling elements 3 and the cage 4 on the rolling and sliding portions in a film shape ( Supply processing). The supply of the lubricating oil may be applied by spraying or may be immersed in a lubricating oil reservoir. The lubricating oil prepared here is, for example, fomblin emulsion FE20 (fomblin concentration 20 mass%) diluted with an appropriate diluent solvent to a fomblin concentration of 0.25 mass%. In addition, the above-mentioned dilution solvent can be volatile, such as a methanol solution, an alcohol solution, or water.
[0028]
(B) The entire rolling bearing A coated with the lubricating oil is heated at 40 to 50 degrees for about 3 minutes to remove a solvent such as a methanol solution contained in the lubricating oil (drying process).
[0029]
(C) Thereafter, heating is performed at 150 to 300 degrees for 15 to 30 minutes, for example, according to the ambient temperature in the bearing use environment (finish drying treatment).
[0030]
Note that (a) and (b) may be repeated several times as necessary. Finally, the thickness of the lubricating thin film 5 is set to 0.2 μm or less, for example.
[0031]
If it does in this way, the lubricating thin film 5 can be formed in the suitable film thickness in the site | part which mutually contacts in the component of the rolling bearing A. If the solvent is removed as described above, unnecessary dust generation components during the operation of the rolling bearing A are eliminated. Moreover, since the film thickness of the lubricating thin film 5 is set to be extremely thin, there is almost no dust generation due to the oil component. Furthermore, the final heat treatment can eliminate dust generation in the environment of use.
[0032]
For the above-mentioned lubricating oil, (1) the relationship between the dilution concentration and the amount of dust generated at the beginning of rotation in the rolling bearing, (2) the number of repetitions of supply processing and drying processing (number of dippings) when forming the thin film 5 The relationship between the amount of dust generated at the beginning of rotation in the rolling bearing and the relationship between the presence / absence of derivative molecules and the life of dust generation will be described.
[0033]
In this test, the apparatus shown in FIG. 2 is used. In the figure, 50 and 50 are rolling bearings to be tested, 51 is a rotating shaft, 52 is a casing, 53 is a magnetic fluid seal, 54 is a dust generation number measuring device (particle counter), and 55 is a measurement result recorder (recorder). , 56 is a bearing housing, and 57 is a coil spring for adding an axial load.
[0034]
The test bearing 50 has a nominal number SE608 (φ8 × φ22 × 7), the inner / outer rings and rolling elements are JIS standard SUS440C, and the cage (waveform type) is JIS standard SUS304.
[0035]
The test conditions are as follows.
[0036]
・ Rotation speed: 200rpm
・ Load: Axial load (20N, 100N)
・ Atmosphere: Air, inside clean bench (Class 10)
-Ambient temperature: room temperature-Measurement conditions: Number of dust particles with a particle size of 0.1 μm or more, 0.3 μm or more (1) The test time is 10 hours (h) at the beginning of rotation. Lubricating oil has a fomblin concentration (mass%) of fomblin emulsion FE20 in four stages of “5”, “2”, “0.5”, and “0.25” with a diluent solvent (ethyl alcohol or water). Diluted one is used. The method for forming the thin film 5 is the method described above. However, after supplying and drying are repeated twice, finish drying (170 ° C., 15 minutes) is performed.
[0037]
As a result, as shown in Table 1 below, the amount of dust generated when 0.25 mass% is set is significantly smaller than the others.
[0038]
[Table 1]

[0039]
(2) The test time is the initial 10 hours (h) of rotation. The supply process and the drying process are repeated four times: “4”, “3”, “2”, and “1”. As the lubricating oil, the one described in the above item (1) (one obtained by diluting the fomblin concentration of the fomblin emulsion FE20 to 0.25 mass%) is used.
[0040]
As a result, as shown in Table 2 below, the amount of dust generated when the number of repetitions is 2 or less is much smaller than the others.
[0041]
[Table 2]

[0042]
The thickness of each thin film 5 according to the number of repetitions in the above (2) was estimated based on the mass increase of the rolling elements. In this case, after obtaining the thin film 5, the rolling bearing is disassembled, and the mass increase of the rolling elements is measured. The results are shown in Table 3 below.
[0043]
[Table 3]

[0044]
-Specific gravity of the film: 1.88 g / cm ³
・ Surface area of rolling element: 0.495 cm ²
In view of this result and the above results (1) and (2), it can be said that the thickness of the thin film 5 is preferably 0.2 μm or less. However, even if it is 0.2 μm or less, if it is too thin, the lubricity at the sliding contact portion between the metal materials may be lowered. Therefore, it can be said that it is preferable to set it in the vicinity of 0.2 μm or less.
[0045]
(3) Since the test time is the dust generation life, there is no limitation. The dust generation life is measured by measuring the time until the time when the total dust generation amount from the two bearings 50, 50 is 1000 pieces / 0.1 cf or more is continuously measured 10 times. Measurements are made every 6 minutes.
[0046]
Three test products, comparative products, and conventional products are used as test bearings. The example product uses lubricating oil obtained by diluting fomblin emulsion FE20 with a diluting solvent (ethyl alcohol or water) to a fomblin concentration of 0.25 mass%, and three oils having the same specifications are used. As a comparative product, a lubricating oil in which Fomblin Z25 is diluted with a diluting solvent (Galden SV90) to a fomblin concentration of 0.25 mass% is used. That is, the lubricating oil of the example product contains a derivative, and the lubricating oil of the comparative product does not contain a derivative. In the conventional product, a coating film is formed on the inner and outer rings and the entire cage surface. This coating film is obtained by dispersing and mixing polytetrafluoroethylene (PTFE) in a binder made of a thermosetting synthetic resin.
[0047]
As shown in Table 4 below, when the axial load is 100 N, the load resistance of the example product is about 10 times that of the comparative product and the conventional product, and especially in high load conditions. It can be said that it is superior when used below. Incidentally, the coating film used in the conventional product has much less dust generation than the coating film of other general solid lubricants. The reason why such a result is obtained is that the lubricating thin film 5 as the product of this example has fluidity, and the sliding contact between the inner and outer rings, the rolling elements and the cage is always via the lubricating oil. It can be said that there is no abrasion as well as exfoliation and missing like a solid lubricant coating film.
[0048]
[Table 4]

[0049]
In addition, as shown in Table 5 below, there was almost no difference in the amount of dust generated in the example product and the comparative product in the initial 10 hours of rotation.
[0050]
[Table 5]

[0051]
From the results of (3), it was found that the lubricating oil for forming the thin film 5 is particularly excellent in load resistance when it contains derivative molecules.
[0052]
As shown in the results of the above tests (1) to (3), as the thin film 5, it is necessary to specify the properties of the lubricating oil used, the thin film forming method, the film thickness after generation, etc. to some extent. It will be understood that it is important in the performance and load resistance.
[0053]
By the way, in the case where the inner and outer rings 1 and 2 and the rolling element 3 are made of a corrosion-resistant metal material in the rolling bearing A in which the thin film 5 made of the above-described lubricating oil (diluted Fomblin emulsion FE20) is formed, an uneven load or the like It is considered that there is a possibility that corrosion will occur at the sliding contact site in extreme cases. This is because, when a part of the thin film 5 is scraped off when an unbalanced load is applied, the inner and outer rings 1 and 2 and the surface of the rolling element 3 (oxidized surface on the metal surface) are exposed. In this case, adhesion wear between the metal materials occurs. When such adhesion wear occurs, the surfaces of the inner and outer rings 1 and 2 and the rolling element 3 are also regenerated (not oxidized). Since the pure metal surface is exposed, this new surface can react with the fluorine in the components of the lubricating oil and be corroded. In addition, it is possible that a fluorine component gas is generated by the catalytic action during adhesion wear. On the other hand, if at least the rolling element 3 is made of a ceramic material in the rolling bearing A, it is possible to avoid the above-mentioned adhesive wear, so that there is no need to worry about corrosion or gas generation as described above. Therefore, it can be said that the configuration of the rolling bearing A is superior to that in which at least the rolling element 3 is made of a ceramic material compared to a metal material.
[0054]
In addition, this invention is not limited only to the said Example. For example, in the embodiments, a deep groove type ball bearing is cited as the bearing type, but the present invention can be applied to other types of rolling bearings.
[0055]
【The invention's effect】
In the rolling bearing according to the present invention, a lubricating thin film having fluidity without wear as well as peeling and missing like a coating film of a conventional solid lubricant is used. Therefore, even in a situation where a relatively large axial load is applied, the bearing component The sliding contact between them does not become a non-lubricated contact state between the metals, but is always in a sliding contact state via the lubricating oil, so that dust generation is remarkably reduced and the lubricity is remarkably improved. In this way, not only the dust generation from the lubricating thin film but also the dust generation from the bearing components can be suppressed, and the operation stability can be improved.
[0056]
Therefore, for example, when the rolling bearing of the present invention is used where high-precision processing is required as in the semiconductor manufacturing process, it is difficult to inhibit the clean atmosphere, which can contribute to the improvement of the yield of semiconductor manufactured products.
[0057]
In particular, when the film thickness of the thin film is specified, excellent results regarding both dust generation and lubricity can be obtained. About this film thickness, if the lubricating oil used as the base which forms a thin film is specified, it will become easy to set.
[0058]
In the method for forming a lubricating thin film of a rolling bearing according to the present invention, the lubricating oil thin film made of a fluorine-containing polymer having a functional group is used as an amount that does not generate dust and does not interfere with the lubricating action at the oil film forming target site. Therefore, there is almost no dust generation, and a lubricating action between the bearing components can be stably obtained, so that the life of the bearing can be extended.
[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 schematic view of a test apparatus used for measuring the dust generation amount of the bearing.
[Explanation of symbols]
A Rolling bearing 1 Inner ring 2 Outer ring 3 Rolling element 4 Cage 5 Lubrication thin film

Claims (3)

In a rolling bearing in which inner and outer rings are made of metal, and a lubricating thin film made of a fluoropolymer having a functional group is formed on at least the raceway surface thereof,
A rolling bearing , wherein the thin film is formed of a lubricating oil obtained by diluting a mixture of perfluoropolyether (PFPE) and a derivative thereof with a diluting solvent, and the thin film has fluidity .   The rolling bearing according to claim 1, wherein a thickness of the thin film is set to 0.2 μm or less. In a rolling bearing in which inner and outer rings, rolling elements and cages are assembled, lubricating oil obtained by diluting a mixture of perfluoropolyether (PFPE) and a derivative thereof with a diluting solvent is provided at least on the rolling and sliding portions of each element. A process of adhering to a film,
Heating the film-like lubricating oil to remove the mixture contained therein;
A method for forming a lubricating film having fluidity of a rolling bearing, comprising:

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