JP4243780B2 - Rolling bearing device for high-speed rotating equipment - Google Patents

Description

【００３７】
【化２】

【００３８】
【化３】

【００３９】
【化４】

【００４０】
【化５】

【００４１】
前記多孔質のＰＡＩ樹脂成形体からなる保持器は、特公平５−４３８８４号に示されるように、平均粒径が１５〜５０μｍに分級整粒したＰＡＩ樹脂粉末を加圧焼成して製造することができる。
前記焼結成形において、樹脂粉末の平均粒径や圧力などを所望に調整して、体積比５〜２０％の連通気孔を有するポーラスな構造の保持器を調製する。次いで、前記連通気孔に、詳しくは後述するが特定の潤滑油（基油：植物性不乾性油）を含浸し本発明の保持器（リテーナ）を製造する。
【００４２】
前記多孔質ＰＡＩ樹脂成形体からなる保持器（リテーナ）において、原料の樹脂粉末に１５μｍ未満の微小粒径の粉末が混入している場合、孔、即ち空間部が前記微小粉末により閉塞されてしまうので、製品の気孔率のバラツキを招来させる。このため、前記した分級整粒が必要となる。
また、逆に５０μｍを超える大きな粒径の粉末が混入する場合、粒子間の空隙が大きくなり、高速回転時の含浸油の保持率（保油率）が低下し、さらに保持器（リテーナ）の強度も低下するため、前記した大きな粒径の混入は好ましくない。
【００４３】
図４〜図５は、多孔質ＰＡＩ樹脂成形体からなる保持器（４４）の別の態様を説明する図である。
なお、図４は保持器（４４）の応用例である前記図２に示されるものとは別の構造の歯科用エアータービンハンドピースを説明する図である。なお、図４の歯科用エアータービンハンドピースの構造は、対応する前記図２より明らかであるため、説明は省略する。また、図には示していないが、軸受けにシールを付けたものであっても良い。
また、図５は、保持器（４４）の形状構造を説明する図であり、前記図３に対応する図である。図５において、（４４ａ）は保持器本体を示し、（４４ｂ）は穴部（気孔部）を示している。
【００４４】
本発明の保持器（リテーナ）の第二実施態様は、次の通りである。
本発明の保持器（リテーナ）の第二実施態様は、多孔質のＰＩ樹脂成形体で構成される。
【００４５】
前記多孔質のＰＩ樹脂成形体からなる保持器（リテーナ）は、前記ＰＡＩ樹脂の粉末の焼結成形と同様にして製造することができる。即ち、平均粒径が、１５〜５０μｍに分級整粒したＰＩ樹脂粉末を加圧焼結することにより、体積比５〜２０％の連通気孔の多孔質ＰＩ樹脂成形体を製造することができる。
【００４６】
前記第一の実施態様及び第二の実施態様においては、保持器（リテーナ）を、焼結成形して成形する方法を示したが、これに限定されず、例えば、以下の方法によって成形しても良い。
多孔質のマトリックス材を構成するＰＩ樹脂及び前記ＰＩ樹脂に近似する成形温度帯を有する他の耐熱性樹脂であって、かつ前記ＰＩ樹脂の共存下に溶媒で処理されると他の耐熱性樹脂だけが溶出される他の耐熱性樹脂を混合し、次にこの混合物を溶融成形して所望形状の保持器（リテーナ）に成形し、この成形した保持器から前記他の耐熱性樹脂のみを溶媒溶出させて多孔質の保持器（リテーナ）としても良い。
【００４７】
前記した保持器（リテーナ）の成形方法において、ＰＩ樹脂なる用語には前記したようにＰＡＩ樹脂も含まれる。
なお、前記した他の耐熱性樹脂の例としては、ポリエーテルサルフォン（ＰＥＳ）、ポリエーテルイミド（ＰＥＩ）、ポリアリレート（ＰＡＲ）、ポリサルフォン（ＰＳＦ）などが使用できる。また、前記した溶媒としては、塩化メチレン（ジクロロメタン）、クロロホルム、メチルエチルケトン、テトラヒドロラン、Ｎ−メチルピロリドン、Ｎ，Ｎ−ジメチルホルムアミドなどを使用することができる。
【００４８】
前記多孔質ＰＩ樹脂製の保持器（リテーナ）は、前記多孔質ＰＡＩ樹脂のものと比較して、潤滑油が切れた場合、溶融することがなく、軸受が使用不能とならないこと、またＰＩ樹脂は吸湿速度が遅く原料粉や成形品の管理が容易であること、などというメリットを有している。なお、前記した理由により後者のＰＡＩ樹脂は、溶融型樹脂として位置づけられるものである。
また、滅菌処理（オートクレーブ処理）においても、近年、特にＨＩＶの感染予防が求められ、従来の処理条件よりも更に厳しい条件下での処理（例えば、蒸気圧２．４kgf／cm² （235Pa）、温度１３５℃、時間５分）が求められているが、前記多孔質ＰＩ樹脂製の保持器（リテーナ）は、２００℃程度まで耐えることができる。
【００４９】
本発明の保持器（リテーナ）の第三実施態様は、次の通りである。
本発明の保持器（リテーナ）の第三実施態様は、連通気孔層とみなされる繊維層を有するフェノール樹脂成形体で構成される。この種の繊維層を有するフェノール樹脂成形体は、前記繊維層を利用して潤滑油を含浸させることができるものである。
本発明において、前記繊維層入りのフェノール樹脂成形体（以下、多孔質Ｐ・Ｒということがある。）は、前記多孔質ＰＩ／ＰＡＩ樹脂成形体（以下、多孔質ＰＩ／ＰＡＩ・Ｒということがある。）の場合の連通気孔による潤滑油の含浸機能とは異なるものの、繊維層（布）を介しての潤滑油の含浸機能を有する。このため、本発明において、用語の正確さは欠けるが前記繊維層（布）入りのフェノール樹脂成形体を気孔部（連通気孔部）を有する樹脂成形体であると位置づけしている。
【００５０】
この種のフェノール樹脂系の保持器（リテーナ）は、特開平６−１６５７９０号に示される方式などにより製造すればよい。
例えば、前記布入りフェノール樹脂成形体は、
(i).布を多重合巻きにしてパイプ状とし、これを真空状態に維持して布の間にフェノール樹脂を充填、硬化させて多孔質の筒状体とする方法、
(ii).フェノール樹脂を含浸した布を多重巻きにし、これを加熱圧縮して多孔質の筒状体とする方法、
などにより製造することができる。
前記布入りフェノール樹脂成形体の気孔率は、前記ＰＩ樹脂と同様のものでよく、体積比５〜２０％の多孔質のものを使用すればよい。
【００５１】
次に、本発明の高速回転機器用の転がり軸受装置における前記第三の特徴点である潤滑油成分、即ち、前記した特定の無機質ボール及び特定の多孔質成形体からなる保持器（リテーナ）に適用もしくは含浸される特定の潤滑油成分について、詳しく説明する。
【００５２】
本発明の第三の特徴点は、高速切削器（エアータービンハンドピース）などの高速回転機器用の転がり軸受装置、即ち、エアータービン翼が固定された回転軸を回動自在に支承する外輪、内輪、無機質ボールからなる転動体、及び耐熱合成樹脂製の多孔質保持器（リテーナ）からなる転がり軸受装置に対して、積極的に潤滑油を使用するという点にある。
なお、この種の４０万〜５０万ｒｐｍの高速回転機器の転がり軸受装置において、保持器（リテーナ）と潤滑油の使用を排除したり、あるいは水潤滑を採用して潤滑油の使用を排除する提案がなされているが、この面からみても本発明には特異性がある。
前記した潤滑油はいうまでもないことであるが、生体安全性や環境保全性、耐熱性（オートクレーブ処理による滅菌消毒が可能であること。）、高速回転の実現性、などの観点から所望のものが選択されなければならないことはいうまでもないことである。
本発明は、潤滑油として、従来のパラフィン油やフッ素化油のほかに、更なる高性能の潤滑系を実現するために従来技術にはみられない植物性の不乾性油を採用するものである。
このため、本発明の潤滑油の理解を助けるために、まず植物性不乾性油から説明する。
【００５３】
植物油は、大別すると下記の三種に分類することができる。
(i).不乾性油（Nondrying oil）
これは、薄層にして空気中で乾燥（酸化）しても膜状物（樹脂状固体）を形成しない油である。
この種の不乾性油は、分子中の二重結合が二以上（以下、多価という。）の不飽和脂肪酸の量が少なく、オレイン酸（１分子当り二重結合一個）のグリセリド（グリセリンエステル）が主成分であり、従って、ヨウ素価（油の不飽和度を示す尺度。Iodine value) は１００以下である。
この種の不乾性油の代表例は、オリーブ油、落花生油、オレイソル油などがある。
【００５４】
(ii).半乾性油（Semidrying oil）
これは、前記した不乾性油と後述する乾性油の中間的性質を示す油である。なお、ヨウ素価は１００〜１３０のものである。
この種の半乾性油の代表例は、菜種油、ゴマ油、綿実油などがある。
【００５５】
(iii).乾性油（Drying oil）
これは、薄層にして空気中で乾燥（酸化）すると膜（樹脂状固体）を形成する油である。この種の乾性油は、不飽和度の高い脂肪酸（例えば、リノール酸は二重結合が二個、リノレン酸は二重結合が三個ある。）のグリセリドからなり、これが空気中の酸素を吸収して、酸化重合して膜状物を容易に形成する。なお、前記乾性油のヨウ素価は、１３０以上のものである。
この種の乾性油の代表例は、アマニ油、桐油などがある。
【００５６】
前記した各種の植物油のうち、不乾性油は、薄層にして乾燥（酸化）しても膜状物（樹脂状固体）を生成しない油脂（高級脂肪酸のグリセリンエステル）であり、耐熱性（オートクレーブ処理により滅菌消毒が可能なこと）や耐久性に優れているため、歯科用エアータービンハンドピースなどの高速回転機器の転がり軸受装置用の潤滑油として好適なものである。
【００５７】
本発明は、歯科用エアータービンハンドピースなどの高速回転機器の転がり軸受装置用の潤滑油として、植物油のうちの不乾性油を採用するものである。以下、前記植物油の不乾性油として代表例であるオリーブ油（Olive Oil）について詳しく説明する。
【００５８】
オリーブ油は、オリーブ（Olea Europaea）の果実から製造される油脂（グリセリンエステル）であり、その成分は大別すると下記の３種に分類することができる。
(i).不飽和樹脂酸、
(ii).飽和樹脂酸、
(iii).各種の微量成分。
【００５９】
オリーブ油の不飽和樹脂酸は、一般に一価及び二価以上（多価）のもので構成される。
以下、オリーブ油の不飽和樹脂酸の種類と含有量を示す。
1).オレイン酸（一価）…………………５６．０〜８３．０％
ＣＨ₃（ＣＨ₂ ）₇ＣＨ＝ＣＨ（ＣＨ₂ ）₇ＣＯＯＨ
2).リノール酸（多価）………………… ３．５〜２０．０％
ＣＨ₃（ＣＨ₂ ）₄ＣＨ＝ＣＨＣＨ₂ＣＨ＝ＣＨ（ＣＨ₂ ）₇ＣＯＯＨ
3).パルミトオレイン酸（一価）……… ０．３〜３．５％
ＣＨ₃（ＣＨ₂ ）₅ＣＨ＝ＣＨ（ＣＨ₂ ）₇ＣＯＯＨ
4).リノレン酸（多価）………………… ０．０〜１．５％
ＣＨ₃ＣＨ₂ＣＨ＝ＣＨＣＨ₂ＣＨ＝ＣＨＣＨ₂ＣＨ＝ＣＨ（ＣＨ₂ ）₇ＣＯＯＨ
5).ガドレイン酸（一価）……………… ０．０〜０．０５％
ＣＨ₃（ＣＨ₂ ）₉ＣＨ＝ＣＨ（ＣＨ₂ ）₇ＣＯＯＨ
【００６０】
前記したように、オリーブ油は、一価の不飽和脂肪酸であるオレイン酸を多く含有するものである。また、オリーブ油は、リノール酸などの多価の不飽和脂肪酸を少量、含有している。
前記したように、多価の不飽和脂肪酸は酸化しやすいものであるが、オリーブ油は、後述するように微量成分としてトコフェロール類（ビタミンＥ）を含有しているため、前記トコフェロール類（ビタミンＥ）の抗酸化作用によりリノール酸などの多価不飽和脂肪酸の酸化劣化が防止され、オリーブ油全体は、耐酸化性に優れている。
【００６１】
次に、オリーブ油の飽和脂肪酸成分について説明する。
以下、オリーブ油の飽和脂肪酸の種類と含有量を示す。
(1).パルミチン酸 ＣＨ₃（ＣＨ₂ ）₁₄ＣＯＯＨ ……７．５〜２０．０％
(2).ステアリン酸 ＣＨ₃（ＣＨ₂ ）₁₆ＣＯＯＨ ……０．５〜３．５％
(3).ミリスチン酸 ＣＨ₃（ＣＨ₂ ）₁₂ＣＯＯＨ ……０．０〜０．０５％
(4).アラキジン酸 ＣＨ₃（ＣＨ₂ ）₁₈ＣＯＯＨ ……０．０〜０．０５％
(5).ベヘニン酸 ＣＨ₃（ＣＨ₂ ）₂₀ＣＯＯＨ ……０．０〜０．０５％
(6).リグノセリン酸 ＣＨ₃（ＣＨ₂ ）₂₂ＣＯＯＨ ……０．０〜０．０５％
前記したことから判るように、オリーブ油は高コレステロール血症の原因となる飽和脂肪酸の含有量が少ないものであるということができる。
【００６２】
次に、オリーブ油の各種微量成分について説明する。
以下、オリーブ油の各種微量成分の種類と前記成分の特性や機能について説明する。
▲１▼．不ケン化物
(a).ステロール類、
(b).炭化水素類
・スクアレン
・芳香族炭化水素（これは、固有の感覚的特性、即ち香りや風味を与える。）
(c).トコフェロール類（酸化防止機能）
・α−トコフェロール（ビタミンＥ）（黒変と重合防止）
・β、γ、δ−トコフェロール（重金属の存在によって起こる酸敗の防止）
(d).トリテルペン・アルコール類
・シクロ・アルテノール
・エルトロ・ジオール
(e).脂溶性のビタミン類
・ビタミンＡ、Ｄ（抗酸化作用）
▲２▼．燐脂質、葉緑素及び誘導体
(a).燐脂質
(b).葉緑素（抗酸化作用）
▲３▼．フェノール化合物
(a).フェノール化合物（抗酸化作用）
(b).ポリフェノール（抗酸化作用）
前記したことから判るように、オリーブ油は、他の不乾性油や乾性油と比較して、油脂の酸化に抗して作用する各種の微量成分の含有量が高く、耐熱性（オートクレーブ処理による滅菌消毒が可能である。）や耐久性に優れた潤滑油となるのである。
【００６３】
次に、本発明の歯科用エアータービンハンドピースなどの高速回転機器の転がり軸受装置用の潤滑油を構成し得る他の植物性不乾性油について、説明する。
(i).前記したオリーブ油以外の植物性不乾性油として、落花生油（Arachis Oil）がある。
落花生油は、落花生（Arachis Hypogaea）の種子に４０〜５０％含まれており、その種子から搾られて製造される。
(ii).前記したオリーブ油以外の植物性不乾性油として、オレイソル油がある。オレイソル油は、不乾性油ではないリノール酸（多価）を多く含有するヒマワリの突然変異種から製造される。今日、農業化学者の努力によりオレイン酸（一価の不飽和脂肪酸）を多く含む突然変異種のヒマワリを育てることに成功しており、この突然変異種からオレイソルと命名された油が製造されている。オレイソル油は、前記したオリーブ油と同様の不乾性油である。
【００６４】
本発明の歯科用エアータービンハンドピースなどの高速回転機器用の転がり軸受装置において、潤滑油として適用される前記植物性不乾性油と他の植物性半乾性油あるいは食用油との組成の違いを下記の表１に示す。表１において、オリーブ油、落花生油、及びオレイソル油は本発明の転がり軸受装置に有用な植物性不乾性油であり、他のものは比較対照の植物性半乾性油及び乾性油を示している。
なお、表１の注釈は、次の通りである。
(1).オレイン酸を主とし、パルミトオレイン酸を含む。
(2).リノール酸。
(3).リノレン酸。
(4).パルミチン酸、ステアリン酸、ラウリン酸、ミリスチン酸から成る。
表１中、（＊）印は、比較対照の植物油である。
【００６５】
【表１】

【００６６】
表１から、次の点が明らかである。
(i).植物性不乾性油は、酸化しにくい１価の不飽和脂肪酸が多い。
(ii).植物性不乾性油は、酸化しやすい２価〜３価の不飽和脂肪酸、即ち多価の不飽和脂肪酸が少ない。
(iii).植物性不乾性油は、抗酸化作用を有するトコフェロール類（ビタミンＥなど）の対多価不飽和脂肪酸比が高い。
【００６７】
本発明の歯科用エアータービンハンドピースなどの高速回転機器の転がり軸受装置用の潤滑油を構成し得る植物性不乾性油（オリーブ油、落花生油、オレイソル油など）において、遊離の脂肪酸（飽和、不飽和）の合計含有量が少ないほど、潤滑特性に優れている。
この点は、本発明者らの植物性不乾性油の潤滑特性の改善を検討している過程で見い出されたものであり、後述するように実証データにより裏付けされている。
【００６８】
前記した植物性不乾性油中の遊離した脂肪酸（以下、遊離脂肪酸ということがある。）について、以下に説明を加える。
一般に、油脂（牛脂、豚脂、バターなどの脂肪、及び菜種油、桐油、アマニ油などの脂肪油）は、高級脂肪酸のグリセリンエステルで構成されている。
即ち、本発明の転がり軸受装置に有用な植物性不乾性油において、各種の脂肪酸（飽和、不飽和）は、下式(1)で示されるエステルとして存在するものである。
脂肪酸の３分子＋グリセリンの１分子→トリグリセリドの１分子（エステル）…………(1)
【００６９】
しかしながら、前記植物性不乾性油中にはグリセリン（Grycerol, CH₂OH-CHOH-CH₂OH)と結合していない各種の脂肪酸（遊離脂肪酸）も含まれている。前記した遊離脂肪酸の合計含有量の度合を遊離酸度で示すと、この値が低いほど酸度が低くなり、かつ粘度も高粘度側にシフトするため、遊離酸度の低い植物性不乾性油は転がり軸受装置用潤滑油として耐久性に優れたものとなる。
前記した遊離酸度に基づいて、オリーブ油の品質を分類したのが下記の表２である。表２より高級なオリーブ油ほど遊離酸度が低く、後述するように優れた潤滑特性を示す（表３参照）。
なお、オリーブ油などの植物性不乾性油の遊離酸度を低くする方法としては、例えば、以下の方法を採用すればよい。即ち、オリーブ油に５〜１０％の水酸化ナトリウムを加えて加熱すると、けん化されてグリセリンと脂肪酸ナトリウム塩が生成し、生成したグリセリンは遊離脂肪酸とエステル結合する。その後、遠心分離などによって油脂分を分離除去すれば、遊離酸度の低いオリーブ油が得られる。
また、表２中、オリーブ油の各種グレード名は、アメリカのゴールデンイーグルオリーブプロダクツ社製のオリーブ油の商品名である。
【００７０】
【表２】

【００７１】
本発明の潤滑油の基油成分として、前記した植物性不乾性油のほかに、従来公知の鉱油系（天然系）または合成系の各種の基油成分を使用することができる。
この種の鉱油系または合成系の基油成分としては、鉱油（パラフィン油）、オレフィンオリゴマー、リン酸エステル、有機酸エステル、シリコーン油、ポリアルキレングリコールなどを例示することができる。
これらの基油成分は、前記した植物性不乾性油と比較して、生体安全性（生体為害性）や環境保全性（安全性）に劣るものの、高速回転機器の用途においては十分に使用することができるものである。
【００７２】
【発明の実施の形態】
以下、本発明を実施例により更に詳しく説明する。
特に、歯科用エアータービンハンドピースの転がり軸受装置において、本発明に係る非金属製の無機質ボールと多孔質の合成樹脂成形体で構成される保持器（リテーナ）を有する軸受部に対する潤滑油の潤滑効果と、従来公知のステンレス製ボールと非多孔質（バルク状、無孔質）の合成樹脂成形体で構成される保持器（リテーナ）を有する軸受部に対する潤滑油の潤滑効果を比較し、本発明の潤滑系の優位性を検討した。なお、前記多孔質の合成樹脂成形体で構成される保持器（リテーナ）を「ポーラス」、前記非多孔質の合成樹脂成形体で構成される保持器（リテーナ）を「バルク」と表記する場合がある。
従って、以下の説明において、
(1).ステンレス（ＳＵＳ）製転動体（ボール）とバルク状（無孔質）保持器（リテーナ）の組合わせのもの、
(2).ステンレス（ＳＵＳ）製転動体（ボール）と多孔質保持器（リテーナ）の組合わせのもの、及び、
(3).非金属製、例えば、窒化珪素、ジルコニア、パイレックスで製作した転動体（ボール）とバルク状（無孔質）保持器（リテーナ）の組合わせのもの、は本発明の比較対照例となるものである。
【００７３】
(i).試験に供した歯科用エアータービンハンドピースの全体構造：
本発明の実施例において試験に供した歯科用エアータービンハンドピース
（図１〜図２参照）の転がり軸受装置の構成は次の通りである。

の寸法を有する開放形のミニアチュア型玉軸受で冠型リテーナを有するもの
である。
【００７４】
(ii).給気圧、給気量の条件：
前記転がり軸受装置を歯科用エアータービンハンドピースに装着し、給気圧１．８ｋｇｆ／ｃｍ²、給気量２５リットル／分の条件で試験した。
【００７５】
(iii).保持器（リテーナ）の種類：
▲１▼．バルクＰＩ／ＰＡＩ・Ｒ………これは、ポリイミド（ＰＩ）系、またはポリアミドイミド（ＰＡＩ）系の無孔性（バルク状）のリテーナを意味する。即ち、本発明の先に説明した第一実施態様〜第三実施態様の保持器（リテーナ）とは異なる連通構造の気孔部を持たない構造の保持器（リテーナ）を示す。
なお、前記バルクＰＩ・Ｒは、デュポン社製のベスペルＳＰ−１をリテーナ形状に加工したものである。
また、前記バルクＰＡＩ・Ｒは、帝人アモコエンジニアリングプラスチックス社製のトーロン４２０３をリテーナ形状に加工したものである。
【００７６】
▲２▼．多孔質Ｐ・Ｒ………これは、布入りフェノール樹脂製の多孔質リテーナを意味する。即ち、このリテーナは、本発明の先に記載した第三実施態様の保持器（リテーナ）を示す。
前記多孔質Ｐ・Ｒは、パイプ状に多重巻きされた織布に対して真空状態で織布の間にフェノール樹脂を含浸し、加熱成形し、その後リテーナ形状に加工したものである。
【００７７】
▲３▼．多孔質ＰＩ／ＰＡＩ・Ｒ………これは、ポリアミド（ＰＩ）系またはポリアミドイミド（ＰＡＩ）系の多孔質のリテーナを意味する。
前記多孔質ＰＩ・Ｒは、宇部興産社製ＵＩＰ−Ｓを成形圧力４０００k gf／cm²（392MPa）で圧縮成形し、窒素雰囲気中で４００℃にて焼結し、これをリテーナ形状に加工したものである（気孔率：体積比約１３％）。
また、前記多孔質ＰＡＩ・Ｒは、米国アモコ社製トーロン４０００ＴＦを平均粒径２０μｍに分級整粒し、成形圧２８００kgf／cm²（274MPa）で圧縮成形し、次いで３００℃で焼結し、これをリテーナ形状に加工したものである（気孔率：体積比約１４％）。
【００７８】
Ａ．各種潤滑油の生体安全性、環境保全性、及び耐熱性の評価：
歯科用エアータービンハンドピース（図１〜図２参照）の転がり軸受装置を使用して、植物性不乾性油を主体とした潤滑系と、従来公知のパラフィン油とフッ素化オイルを主体とした潤滑系において、生体安全性、環境保全性、及び耐熱性（耐オートクレーブ；回）について試験をした。その結果を、下記の表３に示す。
【００７９】
表３における注釈は、次の通りである。
(1)＜耐熱性試験（耐オートクレーブ；回）＞
（株）モリタ製作所製のオートクレーブ装置「アルフィー」を使用し、耐オートクレーブ性を調べた。結果を歯科用エアータービンハンドピースの回転が不安定になり回転効率が１割（１０％、約４万ｒｐｍ）低下する時点までの回数で示す。
なお、前記試験は、転動体（ボール）の種類にあまり影響されないと考えられるため、ボールとして従来のステンレス製のものを使用し、給気圧１．８ｋｇｆ／ｃｍ²、給気量２５リットル／分で約４０万ｒｐｍの条件で試験した。また、オートクレーブ装置「アルフィー」での処理条件は、蒸気圧２．４kgf／cm²（235Pa）、温度１３５℃、時間５分である。
【００８０】
表３において、
(i).パラフィン油（流動パリフィン）は、既存歯科治療関連メーカー製スプレー剤を使用した。
(ii).フッ素化オイルは、イタリアのAusimontu Ｓ.Ｐ.Ａ社製ＦＯＭＢＬＩＮを使用した。
【００８１】
【表３】

【００８２】
Ｂ．各種潤滑油の潤滑性能の評価：
次に、歯科用エアータービンハンドピース（図１〜図２参照）の転がり軸受装置に対して各種の潤滑油を適用し、潤滑性能を評価した。
特に、植物性不乾性油（エキストラバージンオリーブ油）を潤滑油としたものにおいて、転動体（ボール）及び保持器（リテーナ）の構成の違いによる潤滑性能、即ち、(i)高速回転性能、(ii)回転耐久性の特性において、どのような効果が実現されるかを試験した。
【００８３】
前記(i)高速回転性能は、前記したように歯科用アータービンハンドピース（図１〜図２参照）に最初に潤滑油を適用し給気圧１．８ｋｇｆ／ｃｍ²、給気量２５リットル／分の条件で給気したときの回転数（×１０⁴）で評価した。
また、前記(ii)回転耐久時間は、前記(i)の状態から無給油で連続運転を行ない、回転が不安定になり回転数が１割（１０％、約４万ｒｐｍ）低下するまでの時間（hrs）で評価した。
【００８４】
結果を下記の表４に示す。
(イ).表中、ボールの欄の「ＳＵＳ」は、ステンレス製（ＳＵＳ４４０Ｃ）のボールベアリングを意味する。他のものは本発明の非金属製の無機質ボールを意味する。
(ロ).表中、リテーナの欄の「バルク」は、バルクＩＰ／ＰＡＩ・Ｒを意味する。また、「ポーラス」は、多孔質ＰＩ／ＰＡＩ・Ｒを意味する。更に、「フェノール」は、多孔質Ｐ・Ｒを意味する。
(ハ).表中、オイルの欄の「バイオオイル」は、エキストラバージンオリーブ油を意味する。また、「水」は水潤滑を意味する。
【００８５】
【表４】

【００８６】
【発明の効果】
本発明の優位性は、前記表３〜表４から容易に理解することができる。
表３に示されるように、高速回転系の歯科用切削器（エアータービンハンドピース）などの高速回転機器に適用される潤滑油において、特に植物性不乾性油を主体とした潤滑油は、生体安全性（生体為害性）、環境保全性（安全性）、及び耐熱性（耐オートクレーブ）の点で総合的に優れていることがわかる。
また、フッ素化オイル系より安価であるため、経済性にも優れたものである。
更に、植物性として不乾性油以外の半乾性油や乾性油、及びパラフィン油（流動パラフィン）は、空気中１３５℃、１７５時間放置するテストにおいて、激しい色調変化が見られる。別言すれば、これら各種の油は、耐酸化性に劣るものである。なお、前記テストにおいて、オリーブ油及び落花生油などの不乾性油は色調変化を示さなかった。
【００８７】
また、本発明の高速回転系の歯科用エアータービンハンドピースに適用される植物性不乾性油を主体とした潤滑油は、微生物による分解が速く、排水の暫定水質基準（総理府令）から評価してみても従来の鉱油類より好ましいものである。なお、前記排水の暫定水質基準によれば、排水の許容限度は、従来の鉱油類は、５ｍｇ／リットルであるのに対し、植物油類は、３０ｍｇ／リットルである。
【００８８】
更に、表４に示されるように、本発明の転がり軸受装置、即ち、軸受部の転動体（ボール）と保持器（リテーナ）をそれぞれ非金属製の無機質ボールと多孔質合成樹脂成形体で構成した転がり軸受装置において、潤滑油として植物性不乾性油を使用した場合、従来の転がり軸受装置にはみられない格段の特性向上を実現することができる。
【００８９】
更にまた、本発明の非金属製の無機質ボールを用いた転がり軸受装置は、金属製のボールとレースを用いたものに比べて金属製のボールが金属製のレース上を走るような音がなく、また無孔質合成樹脂製のバルクリテーナを用いたものに比べて、極めて静かである（ノイズレス）という効果も享受することができる。
【図面の簡単な説明】
【図１】 本発明の第一実施態様による転がり軸受装置を備えている歯科用エアータービンハンドピースの斜視図である。
【図２】 図１の歯科用エアータービンハンドピースのヘッド部（Ｈ）とネック部（Ｎ）の断面図であり、前記ヘッド部（Ｈ）及びネック部（Ｎ）の構造を説明する図である。
【図３】 図２に示される保持器（４４）の斜視図である。
【図４】 本発明の第二実施態様による転がり軸受装置を備えている歯科用エアータービンハンドピースの断面図であり、前記図２に対応する図である。
【図５】 図４に示される保持器（４４）の断面図である。
【符号の説明】
Ａ ………… 歯科用エアータービンハンドピース
Ｈ ………… ヘッド部
Ｇ ………… グリップ部
Ｎ ………… グリップ部（Ｇ）のネック部
Ｂ ………… 切削工具
１ ………… ヘッド
１１ ………… チャンバー
１２ ………… ヘッド本体部
１３ ………… キャップ部
２ ………… タービンブレード
３ ………… タービンロータ軸
４ ………… 軸受部
４１ ………… 内輪
４２ ………… 外輪
４３ ………… 転動体（ボール）
４４ ………… 保持器（リテーナ）
４４ａ ………… 保持器本体
４４ｂ ………… 穴部（気孔部）
５ ………… 切削工具
６ ………… ネック部（Ｎ）の本体部
７ ………… 給気路
７１ ………… 給気口
８、９ ………… 排気路
８１、９１ ………… 排気口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rolling bearing device for a high-speed rotating device used in fields requiring high speed and high safety, such as for electronic equipment, medical use, food production, and aerospace equipment.
More specifically, the present invention ensures stable high-speed rotation and is high in a rolling bearing device which is a main component of high-speed rotary equipment such as a dental high-speed rotary cutter (dental air turbine handpiece). The present invention relates to a rolling bearing device that has biological safety and has durability that can withstand sterilization treatment (autoclave treatment) under high temperature and high pressure.
[0002]
[Prior art]
A high-speed rotating device, for example, a high-speed cutter for rotating a cutting tool at a high speed generally includes a rotating shaft that fixes and holds the cutting tool, a rotation driving device that rotationally drives the rotating shaft, and the rotation And a bearing portion that rotatably supports the shaft.
[0003]
As this type of high-speed cutter, for example, a medical dental high-speed cutter (air turbine handpiece) can be shown.
And the bearing part of the above-mentioned medical dental high-speed cutting machine (air turbine handpiece) has a ball bearing mechanism using a ball (rolling element) and an air bearing using a non-contact type air bearing. One having a mechanism is known.
In the industry, the ball (rolling element) in the ball bearing mechanism is generally made of metal, more specifically, stainless steel (martensitic stainless steel, SUS440C).
[0004]
For example, paying attention to a bearing mechanism of a dental air turbine handpiece, two types of air turbine handpieces are known: a ball bearing turbine type and an air bearing turbine type.
The former ball bearing turbine type is a high-speed rotating model of about 200 to 400,000 rpm, and the latter air bearing turbine type is an ultra-high-speed rotating type of about 300 to 500,000 rpm. It can be said.
The rotation speeds of the above-described ball bearing turbine type and air bearing turbine type models are general values. For example, the dental air turbine handpiece previously proposed by the present inventors (Japanese Patent Application No. 6-36404). US Patent No. 5,562,446) is of the ball bearing turbine type, but has high performance capable of realizing ultra-high speed rotation.
[0005]
Here, in order to help understanding of the prior art and the present invention, one application device to which the rolling bearing device of the present invention is applied, that is, the structure of a dental high-speed cutter (dental air turbine handpiece) will be described. To do.
[0006]
1-2 is a figure explaining the structure of a dental air turbine handpiece. 1 is a diagram (perspective view) for explaining the overall structure, and FIG. 2 is a diagram (cross-sectional view) for explaining the internal structure of the head part and the neck part.
[0007]
As shown in FIG. 1, a dental air turbine handpiece (A) includes a head part (H) having a cutting tool (B) (5) fixedly held on a rotor shaft (drive shaft) of an air turbine and a grip. It consists of part (G).
The neck portion (N) of the grip portion (G) is connected to the head (H) and supplies and discharges pressurized air to and from an air turbine disposed in the head portion (H). Inside.
[0008]
FIG. 2 shows the internal structure of the head portion (H) and the neck portion (N) of the dental air turbine handpiece (A).
As shown in the drawing, in the head portion (H), a turbine rotor shaft (3) having a turbine blade (2) at the peripheral portion is disposed inside the chamber (11) of the head (1), and the turbine The rotor shaft (3) is rotatably supported in the head (1) through a bearing portion (4).
The head (1) includes a head main body (12) and a cap (13). A bearing portion (4) for rotatably supporting the turbine rotor shaft (3) is disposed inside the head main body portion (12). The cutting tool (5) is fixedly held in the axial center hole of the turbine rotor shaft (3), and a therapeutic action is performed. A chuck (51) for gripping the cutting tool (5) in the axial hole is disposed on the peripheral side portion of the cutting tool (5).
The bearing portion (4) is composed of a ball bearing type composed of an inner ring (41), an outer ring (42), a rolling element (43) and a cage (44). In addition, you may arrange | position the well-known wave washer for improving the O-ring for shaft-shaft center, shaft rigidity, etc. in the outer periphery and side part of a bearing part (4). Further, as described above, the rolling element (43) is generally composed of a stainless steel (SUS440C) ball.
The neck portion (N) has an air supply passage (7) and an air supply port (n) for supplying pressurized air to the turbine blade (2) in which the neck main body portion (6) is disposed in the chamber (11). 71) and exhaust passages (8), (9) and exhaust ports (81), (91) for discharging the pressurized air in the chamber (11).
[0009]
In the internal structure of the dental air turbine handpiece (A) shown in FIG. 2, the air supply / exhaust means for pressurized air has been previously proposed by the present inventors (Japanese Patent Application No. 6-6). 36404, U.S. Patent No. 5,562,446), which is a new configuration that is not found in the prior art.
For this reason, in FIG. 2, in addition to the reference numerals for explaining the respective elements (members), other reference numerals (symbols) are also shown. Although explanation of these reference symbols (symbols) is omitted, the structure of a conventional dental air turbine handpiece can be easily understood from FIG.
The dental air turbine handpiece (A) having the air supply / exhaust means previously proposed by the present inventors shown in FIG. 2 does not belong to the category of handpieces incorporating a conventional rolling bearing device. However, as described above, it is possible to obtain an extremely high speed rotation and thus a large torque.
[0010]
Next, characteristics required for a high-speed rotating device such as the ball bearing type dental air turbine handpiece shown in FIG. 2 will be described.
For example, in the ball bearing type dental air turbine handpiece shown in FIG. 2, the bearing portion is constituted by a miniature type bearing portion, and the turbine rotor shaft rotates at a high speed of about 200 to 400,000 rpm. To do. For this reason, since the temperature inside a bearing part becomes high and the stress concerning a bearing part also becomes large, the structure of the structural member of a bearing part becomes important.
In addition, in the lubricating oil applied to the bearing portion used under the severe conditions described above, the management of the quality and characteristics is extremely important. In particular, lubricants that are excellent in characteristics such as oxidation resistance, high-speed rotation feasibility and long-term / stable maintenance performance are required.
[0011]
Furthermore, since the ball bearing type dental air turbine handpiece is used in the oral cavity, it is used by spraying or dripping lubricating oil onto the bearing portion immediately before use, in other words, an environment of lean lubrication. Under high pressure and high temperature treatment (also called autoclave treatment) for sterilization and disinfection, the treatment condition is, for example, a vapor pressure of 2.4 kgf / cm ² , Temperature 135 ° C., time 5 minutes. )
For this reason, what satisfies the above-mentioned conditions is requested | required as a rolling bearing apparatus used for the said dental air turbine handpiece. In particular, as a characteristic of rolling elements (balls) and cages (retainers), which are important components in a lubrication system, those satisfying the same conditions as described above are required.
[0012]
Conventionally, rolling elements (balls), which are important constituent elements of a rolling bearing device used in the above-described dental air turbine handpiece, are generally made of stainless steel (SUS440C) due to the severe usage environment described above. As described above. In addition, the cage (retainer) is made of a polyimide resin type or a phenol resin type having a fiber layer from the viewpoint of the required characteristics. However, as will be described later in detail, the conventional bearing device cannot exhibit sufficient characteristics.
[0013]
Next, the prior art will be described from the viewpoint of lubricating oil applied to a rolling bearing device of a high-speed rotating device.
In the industry, various lubricating oils are used or proposed as lubricating oils applied to rolling bearing devices of high-speed rotating equipment.
[0014]
For example, lubricating oil is widely supplied by spraying using chlorofluorocarbon or LPG, and refined mineral oils such as paraffin are widely known as lubricating oil.
The above-described lubricating oil is typically petroleum-based, and is prepared by fractionating and purifying petroleum into various fractions and blending additives such as antioxidants necessary for this.
In addition to the natural mineral oils, the base oil components of the lubricating oil described above are known to be synthetic, such as glycols, esters, and low molecular weight polyolefins.
[0015]
In addition, edible oils such as animal oils and vegetable oils are known to be used as lubricating oils for precision machines, machine tools, ship engines, and the like. However, the edible oil is generally used by blending 10 to 20% by weight with a mineral oil.
In addition, since the said edible oil has a problem in oxidation resistance, it is normal to use together with various oxidation stabilizers (antioxidant).
[0016]
Recently, in consideration of the above-mentioned severe use conditions of dental air turbine handpieces, impregnated with fluorinated oil which is excellent in heat resistance, and therefore can be sterilized (autoclaved) and excellent in lubricity. A dental air turbine handpiece having a retainer has been proposed in Japanese Patent Publication No. 5-43884 and Japanese Utility Model Laid-Open No. 7-10553.
The cage is made of a porous body obtained by sintering a polyimide resin powder.
The proposed dental air turbine handpiece has the characteristics that the fluorinated oil is inactive, has excellent heat resistance, chemical resistance and solvent resistance, and does not produce a solid deterioration product even when exposed to high temperatures. Therefore, it can be said that these characteristics are used for the retainer.
[0017]
Japanese Patent Laid-Open No. 6-165790 directly relates to a ball bearing crown type retainer (retainer) in a bearing device for a dental air turbine handpiece, which will be schematically described below. An embodiment of impregnating a lubricating oil is disclosed.
That is, in the dental air turbine handpiece disclosed in JP-A-6-165790, the ball bearing retainer (retainer) is:
(i) A crown-type cage in which a ball holding pocket is formed on one side of a synthetic resin cylinder having a cloth fiber layer inside, and a chamfered portion is formed on an opening side end surface of the pocket. And once
(ii) The lubricating oil was impregnated in the fiber layer of the cage,
It is characterized by.
The crown type cage (retainer) of the ball bearing disclosed in Japanese Patent Laid-Open No. 6-165790 improves the rotational balance by the configuration of (i), and the wear of the cage due to the contact between the cage and the outer ring and the rotational torque are reduced. This is to prevent the increase.
However, in the above-mentioned JP-A-6-165790, the specific structures of the rolling elements (balls) and the lubricating oil are unknown. Moreover, although the said Unexamined-Japanese-Patent No. 6-165790 is explaining that the aspect which injects edible oil in a housing is a prior art, the specific structure of edible oil here is unknown.
The present inventor believes that the lubricating oil disclosed in Japanese Patent Laid-Open No. 6-165790 does not deviate from the conventionally proposed lubricating oil in view of the technical level of the industry.
[0018]
Furthermore, Japanese Patent Laid-Open No. 6-212179 discloses that ceramic powder is mixed in the lubricating oil in order to reduce the number of times the lubricating oil is supplied to the bearing of the dental air turbine handpiece. This is a proposal based on the knowledge that if the ceramic powder is mixed in the lubricating oil, the holding life (lifetime) of the lubricating oil is improved.
[0019]
The various types of lubricating oils proposed so far have various problems to be improved in order to be applicable to high-speed rotating equipment such as medical dental air turbine handpieces having a rolling bearing mechanism. It is.
For example, the above-mentioned mineral oil or synthetic oil such as liquid paraffin, or lubricating oil blended with edible oil improves the high-speed rotation performance (realization of high-speed rotation and its long-term and stable maintenance), Or the point which should be improved including the reduction of the usage-amount is left from a viewpoint of biological harm and environmental conservation.
[0020]
Further, fluorinated oils such as perfluoropolyether (PFPE) and perfluoropolyalkylether (PFAE) proposed in the above Japanese Patent Publication Nos. 5-43884 and 7-10553 have heat resistance and chemical resistance. It is excellent as a lubricating oil for high-speed rotating equipment because it has excellent solvent resistance and does not produce a solid degradation product even when exposed to high temperatures. From this point of view, there are still points to be improved including reduction of the amount of use.
[0021]
Further, the above-mentioned JP-A-6-165790 discloses impregnation of a lubricating oil in a cage of a rolling bearing device constituted by a phenol resin molded body having a fiber layer, and as the lubricating oil Although the use of edible oil is suggested, as will be described in detail later, most edible oils are dry oil, and when the oil dries, it becomes a resinous solid, which is a durable lubricating oil for bearings. Is inappropriate.
[0022]
As described above, most edible oils are dry oils and are easily oxidized. Therefore, it is normal to use a synthetic antioxidant added to the edible oil. In an edible oil-based lubricating oil mainly composed of the drying oil and blended with an antioxidant, a reaction product of the antioxidant and a metal eluted from the bearing device system may be a biologically harmful substance. It must be noted.
[0023]
Japanese Patent Laid-Open No. 6-212179 is intended to mix ceramic powder into lubricating oil to improve the holding time (lifetime) of the lubricating oil and reduce the number of replenishments to the lubricating system. In a rotary medical dental cutter (air turbine handpiece), Retainer If the (retainer) or ball is scraped by the ceramic powder to elute metals harmful to the living body, or if the lubricating oil is reduced in a dilute lubricating environment, the bearing mechanism will be fatally damaged.
[0024]
As described above, the lubricating oil applied to the conventional rolling bearing device used in a high-speed rotating device, for example, a medical dental high-speed rotating device (air turbine handpiece),
(i). Biological safety (less harmful to the living body),
(ii) Environmental integrity (safety),
(iii). Heat resistance (can be sterilized by autoclaving),
(iv) Durability,
(v) .High speed rotation performance improvement,
If it evaluates from such aspects, it will leave problems.
[0025]
[Problems to be solved by the invention]
The present invention has been devised in view of the problems in the conventional rolling bearing device for high-speed rotating equipment.
The direct trigger of the present invention is the high performance, ultra-high speed rotation ball bearing turbine type dental air turbine handpiece previously proposed by the present inventors (Japanese Patent Application No. 6-36404, U.S. In contrast to Patent No. 5,562,446), there was no rolling bearing device having excellent characteristics.
The present inventor, in a rolling bearing device for high-speed rotating equipment, particularly about rolling elements (balls), a cage (retainer) that holds the rolling elements (balls), and lubricating oil, which are important components of the bearing mechanism, We have intensively studied measures to satisfy advanced requirements such as realizing higher speed rotation and improving durability under high speed rotation.
As a result, the present inventor employs inorganic balls such as crystallized glass and tempered glass instead of the conventional stainless steel rolling elements (balls), and sets the retainer (retainer) to a specific porous resin. When a specific lubricating oil, such as a vegetable non-drying oil, is applied to the cage (retainer) composed of a molded body and further composed of the inorganic ball and the porous resin molded body, it is unprecedented. We have found out that a lubrication system with special characteristics can be realized.
The present invention has been completed based on the above findings.
[0026]
The present invention can realize a higher rotational speed as a rolling bearing device in a high-speed cutting device such as a dental air turbine handpiece having a built-in rolling bearing mechanism, and has sufficient durability under high-speed rotation. Provides high-performance rolling bearing devices that have heat resistance that can withstand high temperatures and pressures such as autoclave sterilization, as well as excellent biosafety (harmful for living organisms) and environmental conservation (safety). is there.
In other words, the present invention is made of metal (stainless steel) as a conventional rolling element (ball) in a ball bearing type high-speed rotating device such as a medical dental high-speed cutting machine of 300,000 rpm or more, or even 400,000 rpm or more. Rolling, which is the main component of high-speed rotating equipment that can achieve a much higher rotational speed than steel ball bearings and can realize a durable lubrication system. A bearing device is provided.
[0027]
[Means for Solving the Problems]
Briefly, the present invention relates to a rolling bearing for a high-speed rotating device having a rolling bearing element composed of an outer ring, an inner ring, a rolling element, and a cage (retainer) for rotatably supporting a rotating shaft. In the device
(i). The rolling element is composed of a non-metallic inorganic ball, and
(ii). The cage (retainer) is composed of a porous synthetic resin molded body having a pore portion having a communication structure at least partially,
(iii) The rolling element and the cage (retainer) are lubricated with a lubricating oil,
The present invention relates to a rolling bearing device for high-speed rotating equipment.
[0028]
The technical configuration and embodiments of the present invention will be described in detail below.
[0029]
In the rolling bearing device for a high-speed rotating device of the present invention, the first feature is that the configuration of the rolling element (ball), which is the main component of the rolling bearing device, is changed from a conventional metal one to a non-metallic one. The point is to change to inorganic balls. The second feature point is that the retainer is constituted by a porous body made of a specific matrix material.
Furthermore, in the rolling bearing device for a high-speed rotating device of the present invention, the third feature is that a specific lubricating oil, such as a vegetable, is used for the rolling element (ball) and the cage (retainer) of the specific material described above. The bearing portion is configured by applying or impregnating lubricating oil such as non-drying oil.
As will be described below, the rolling bearing device for a high-speed rotating device of the present invention has the above-mentioned three characteristic points that function organically and exhibit excellent operational effects.
[0030]
Hereinafter, the technical configuration of the present invention will be described in the order of the first to third feature points of the present invention.
[0031]
First, the first feature point in the rolling bearing device for a high-speed rotating device of the present invention, that is, the configuration of a rolling element (ball) that is a main component of the rolling bearing device will be described.
As described above, in the prior art, the rolling elements (balls) of this type of rolling bearing device are generally made of stainless steel (for example, martensitic stainless steel, SUS440C).
However, in the present invention, a higher level of high-speed rotation is realized, low noise is achieved under high-speed rotation, wear due to contact with other members constituting the bearing portion under high-speed rotation is reduced, and under high-speed rotation From the viewpoint of low heat build-up and affinity with a vegetable non-drying oil which is a special lubricating oil described later, non-metallic inorganic balls are used instead of conventional stainless steel balls.
[0032]
As the non-metallic inorganic ball employed as the rolling element (ball) of the present invention, a non-oxidized ceramic material, an oxidized ceramic material, a heat-resistant glass material, or a crystallized glass material may be used. it can.
Non-oxidized ceramic materials include nitrides, carbides, borides, and the like.
As a specific example of the inorganic ball, silicon nitride (Si _Three N _Four ), Silicon carbide (SiC), boron nitride (BN), alumina (Al ₂ O _Three ), Zirconium oxide and zirconia (ZrO) ₂ ), Pyrex (produced by Corning Glass Works) and Telex (produced by Tokyo Shibaura Electric) belonging to heat-resistant glass materials, Neoceram (produced by Nippon Electric Glass Co., Ltd.) belonging to crystallized glass materials, and the like.
In the present invention, it should be understood that the inorganic balls include oxynitride materials having an intermediate composition between nitride and oxide, for example, sialon.
[0033]
Next, the second characteristic point of the rolling bearing device for high-speed rotating equipment of the present invention, that is, the configuration of a retainer that is another main component of the rolling bearing device will be described.
The cage (retainer) of the present invention is characterized in that it is composed of a porous synthetic resin molded body having a pore portion having a communication structure at least partially.
The first embodiment of the retainer of the present invention is as follows.
The first embodiment of the retainer of the present invention is composed of a porous polyimide resin molded body.
FIG. 3 shows a perspective view of a cage (44) made of the porous polyimide resin molded body. In the figure, (44a) shows a cage body, and (44b) shows a hole (a pore).
The cage (44) is applied to the ball bearing type dental air turbine handpiece described with reference to FIGS.
[0034]
In the cage constituted by the porous polyimide resin molded body of the present invention, the polyimide resin (hereinafter abbreviated as PI resin) is obtained by polycondensation of an aromatic carboxylic acid and an aromatic amine. Resin having an imide bond in the main chain (may be thermoplastic or thermosetting) with heat resistance, chemical resistance, mechanical properties, and electrical characteristics It is excellent.
In the present invention, the term PI resin should be understood to include a polyamideimide resin having an imide bond and an amide bond in the main chain (hereinafter abbreviated as PAI resin).
[0035]
In the present invention, commercially available PI resin and PAI resin that constitute the cage (retainer) can be used conveniently. For example, the following can be illustrated as the commercially available PI resin and PAI resin, including their chemical structural formulas.
(i) PI resin:
(1). P84-HT, manufactured by Ranging, Austria (hereinafter, represented by Chemical Formula 1. In Chemical Formula 1, R represents an alkylene group.)
(2). TI-3000 manufactured by Toray Industries, Inc. (shown below by chemical formula 2)
(3). UIP-S manufactured by Ube Industries, Ltd. (shown below by chemical formula 3)
(4) Vespel made by DuPont (shown below in chemical formula 2)
(5). Aurum manufactured by Mitsui Toatsu Chemical Co., Ltd. (shown below as chemical formula 4)
(6) Others include Meldin 8100,900 manufactured by Huron, USA.
(ii). PAI resin:
(1). Torlon 4000TF (produced by Amoco Co., Ltd., represented by the following chemical formula 5. In chemical formula 5, Ar represents a phenylene group).
[0036]
[Chemical 1]

[0037]
[Chemical formula 2]

[0038]
[Chemical 3]

[0039]
[Formula 4]

[0040]
[Chemical formula 5]

[0041]
The cage made of the porous PAI resin molded body is manufactured by pressurizing and firing PAI resin powder classified and sized to have an average particle size of 15 to 50 μm, as shown in Japanese Patent Publication No. 5-43884. Can do.
In the sintering molding, the average particle diameter and pressure of the resin powder are adjusted as desired to prepare a porous structure cage having continuous vents with a volume ratio of 5 to 20%. Next, although described in detail later, the above-mentioned continuous ventilation hole is impregnated with a specific lubricating oil (base oil: vegetable non-drying oil) to produce the retainer of the present invention.
[0042]
In the cage (retainer) made of the porous PAI resin molded body, when a powder having a fine particle diameter of less than 15 μm is mixed in the raw material resin powder, the holes, that is, the spaces are blocked by the fine powder. As a result, the porosity of the product varies. For this reason, the above-described classification and sizing is necessary.
On the other hand, when a powder having a large particle size exceeding 50 μm is mixed, the gap between the particles becomes large, the retention rate (oil retention rate) of the impregnating oil during high-speed rotation is reduced, and the retainer (retainer) Since the strength is also lowered, the above-mentioned large particle size is not preferable.
[0043]
4-5 is a figure explaining another aspect of the holder | retainer (44) which consists of a porous PAI resin molding.
FIG. 4 is a view for explaining a dental air turbine handpiece having a structure different from that shown in FIG. 2, which is an application example of the cage (44). In addition, since the structure of the dental air turbine handpiece of FIG. 4 is clear from the corresponding FIG. 2, description is abbreviate | omitted. Further, although not shown in the figure, the bearing may be provided with a seal.
FIG. 5 is a view for explaining the shape structure of the cage (44), and corresponds to FIG. In FIG. 5, (44a) shows a cage body, and (44b) shows a hole (a pore).
[0044]
A second embodiment of the retainer of the present invention is as follows.
The 2nd embodiment of the holder | retainer (retainer) of this invention is comprised with a porous PI resin molding.
[0045]
The cage (retainer) made of the porous PI resin molded body can be manufactured in the same manner as the sintering molding of the PAI resin powder. That is, by pressure-sintering PI resin powder with an average particle size of 15 to 50 μm and classified, a porous PI resin molded body having continuous air holes with a volume ratio of 5 to 20% can be manufactured.
[0046]
In the first embodiment and the second embodiment, the method of sintering and forming the retainer (retainer) has been shown. However, the method is not limited to this. For example, the cage is formed by the following method. Also good.
PI resin constituting a porous matrix material and other heat resistant resin having a molding temperature range similar to the PI resin, and other heat resistant resin when treated with a solvent in the presence of the PI resin The other heat-resistant resin from which only the resin is eluted is mixed, then the mixture is melt-molded and molded into a retainer having a desired shape, and only the other heat-resistant resin is solvent-solved from the molded cage. It is good also as a porous cage | basket (retainer) by making it elute.
[0047]
In the above-described method for forming a retainer, the term PI resin includes PAI resin as described above.
Examples of the other heat-resistant resins described above include polyethersulfone (PES), polyetherimide (PEI), polyarylate (PAR), and polysulfone (PSF). As the above-mentioned solvent, methylene chloride (dichloromethane), chloroform, methyl ethyl ketone, tetrahydrolane, N-methylpyrrolidone, N, N-dimethylformamide and the like can be used.
[0048]
The cage made of porous PI resin (retainer) is not melted when the lubricating oil runs out as compared with that of the porous PAI resin, and the bearing is not unusable. Has the advantage that the moisture absorption rate is slow and the raw powder and molded product can be easily managed. For the reasons described above, the latter PAI resin is positioned as a molten resin.
Also, in sterilization (autoclave treatment), in recent years, especially HIV infection prevention has been demanded, and treatment under conditions more severe than conventional treatment conditions (for example, vapor pressure 2.4 kgf / cm). ² (235 Pa), temperature 135 ° C., time 5 minutes) are required, but the porous PI resin retainer can withstand up to about 200 ° C.
[0049]
A third embodiment of the retainer of the present invention is as follows.
A third embodiment of the cage of the present invention (retainer) is constituted by a phenol resin molded body having a fiber layer regarded as a continuous vent layer. A phenol resin molded article having this type of fiber layer can be impregnated with lubricating oil using the fiber layer.
In the present invention, the phenol resin molded body containing the fiber layer (hereinafter sometimes referred to as porous P · R) is referred to as the porous PI / PAI resin molded body (hereinafter referred to as porous PI / PAI · R). In this case, the function of impregnating the lubricating oil through the fiber layer (cloth) is different. For this reason, in the present invention, although the terminology is not accurate, the phenolic resin molded body containing the fiber layer (cloth) is positioned as a resin molded body having pores (continuous ventilation holes).
[0050]
This type of phenolic resin cage (retainer) may be manufactured by the method disclosed in JP-A-6-165790.
For example, the cloth-containing phenol resin molding is
(i). A method in which the cloth is made into a multi-polymerized winding to form a pipe, which is maintained in a vacuum state and filled with a phenolic resin between the cloths and cured to form a porous cylindrical body,
(ii) a method of making a cloth impregnated with a phenol resin into multiple wraps, and heating and compressing the cloth into a porous cylindrical body,
Etc. can be manufactured.
The porosity of the cloth-containing phenol resin molding may be the same as that of the PI resin, and a porous material having a volume ratio of 5 to 20% may be used.
[0051]
Next, the lubricating oil component which is the third characteristic point in the rolling bearing device for high-speed rotating equipment of the present invention, that is, the retainer made of the specific inorganic ball and the specific porous molded body described above. The specific lubricating oil component to be applied or impregnated will be described in detail.
[0052]
A third feature of the present invention is a rolling bearing device for a high-speed rotating device such as a high-speed cutting machine (air turbine handpiece), that is, an outer ring that rotatably supports a rotating shaft to which an air turbine blade is fixed, The lubricating oil is positively used for the rolling bearing device composed of the inner ring, the rolling element composed of inorganic balls, and the porous retainer made of heat-resistant synthetic resin.
In addition, in this type of rolling bearing device for a high-speed rotating machine with a speed of 400,000 to 500,000 rpm, the use of a retainer and lubricating oil is eliminated, or the use of lubricating oil is eliminated by employing water lubrication. Proposals have been made, but the present invention is also unique from this aspect.
Needless to say, the above-described lubricating oil is desired from the viewpoint of biological safety, environmental conservation, heat resistance (can be sterilized by autoclaving), feasibility of high-speed rotation, and the like. It goes without saying that things have to be selected.
In addition to conventional paraffin oil and fluorinated oil, the present invention employs a vegetable non-drying oil not found in the prior art in order to realize a higher performance lubricating system. is there.
For this reason, in order to help understanding of the lubricating oil of the present invention, the vegetable non-drying oil will be described first.
[0053]
Vegetable oils can be roughly classified into the following three types.
(i) .Nondrying oil
This is an oil that does not form a film (resin-like solid) even if it is made into a thin layer and dried (oxidized) in air.
This kind of non-drying oil has a small amount of unsaturated fatty acid having two or more double bonds in the molecule (hereinafter referred to as polyvalent), and glycerin (glycerin ester) of oleic acid (one double bond per molecule). ) Is the main component, and therefore the iodine value (a measure of the degree of unsaturation of the oil; Iodine value) is 100 or less.
Typical examples of this type of non-drying oil include olive oil, peanut oil, and oleicol oil.
[0054]
(ii). Semidrying oil
This is an oil having intermediate properties between the above-described non-drying oil and the drying oil described later. The iodine value is 100 to 130.
Typical examples of this type of semi-drying oil include rapeseed oil, sesame oil, and cottonseed oil.
[0055]
(iii). Drying oil
This is an oil that forms a film (resin-like solid) when made into a thin layer and dried (oxidized) in air. This type of drying oil consists of glycerides of highly unsaturated fatty acids (eg linoleic acid has two double bonds and linolenic acid has three double bonds), which absorbs oxygen in the air Then, the film is easily formed by oxidative polymerization. The drying oil has an iodine value of 130 or more.
Typical examples of this type of drying oil include linseed oil and tung oil.
[0056]
Of the various vegetable oils described above, non-drying oil is fat (glycerin ester of higher fatty acid) that does not form a film (resin-like solid) even when dried (oxidized) into a thin layer, and is heat resistant (autoclave). Since it can be sterilized and disinfected by treatment) and has excellent durability, it is suitable as a lubricating oil for rolling bearing devices of high-speed rotating devices such as dental air turbine handpieces.
[0057]
The present invention employs non-drying oil among vegetable oils as lubricating oil for rolling bearing devices of high-speed rotating equipment such as dental air turbine handpieces. Hereinafter, olive oil (Olive Oil) which is a representative example of the non-drying oil of the vegetable oil will be described in detail.
[0058]
Olive oil is an oil (glycerin ester) produced from the fruit of olive (Olea Europaea), and its components can be roughly classified into the following three types.
(i) Unsaturated resin acid,
(ii) a saturated resin acid,
(iii) Various trace components.
[0059]
The unsaturated resin acid of olive oil is generally composed of monovalent and divalent (polyvalent) acids.
Hereinafter, the kind and content of the unsaturated resin acid of olive oil are shown.
1). Oleic acid (monovalent) ... 56.0-83.0%
CH _Three (CH ₂ ) ₇ CH = CH (CH ₂ ) ₇ COOH
2) Linoleic acid (polyvalent) ……………… 3.5-20.0%
CH _Three (CH ₂ ) _Four CH = CHCH ₂ CH = CH (CH ₂ ) ₇ COOH
3). Palmitooleic acid (monovalent) ……… 0.3-3.5%
CH _Three (CH ₂ ) _Five CH = CH (CH ₂ ) ₇ COOH
4) .Linolenic acid (polyvalent) ……………… 0.0-1.5%
CH _Three CH ₂ CH = CHCH ₂ CH = CHCH ₂ CH = CH (CH ₂ ) ₇ COOH
5) .Gadoleic acid (monovalent) ……………… 0.0-0.05%
CH _Three (CH ₂ ) ₉ CH = CH (CH ₂ ) ₇ COOH
[0060]
As described above, olive oil contains a large amount of oleic acid, which is a monovalent unsaturated fatty acid. Olive oil also contains a small amount of polyunsaturated fatty acids such as linoleic acid.
As described above, polyunsaturated fatty acids are easily oxidized, but since olive oil contains tocopherols (vitamin E) as a minor component as described later, the tocopherols (vitamin E) The antioxidant action of polyunsaturated fatty acids such as linoleic acid is prevented from oxidative deterioration, and the olive oil as a whole is excellent in oxidation resistance.
[0061]
Next, the saturated fatty acid component of olive oil will be described.
The types and contents of saturated fatty acids in olive oil are shown below.
(1) Palmitic acid CH _Three (CH ₂ ) ₁₄ COOH: 7.5-20.0%
(2). Stearic acid CH _Three (CH ₂ ) ₁₆ COOH ...... 0.5-3.5%
(3) .Myristic acid CH _Three (CH ₂ ) ₁₂ COOH ...... 0.0-0.05%
(4) .Arachidic acid CH _Three (CH ₂ ) ₁₈ COOH ...... 0.0-0.05%
(5). Behenic acid CH _Three (CH ₂ ) ₂₀ COOH ...... 0.0-0.05%
(6) Lignoceric acid CH _Three (CH ₂ ) _{twenty two} COOH ...... 0.0-0.05%
As can be seen from the foregoing, olive oil can be said to have a low content of saturated fatty acids that cause hypercholesterolemia.
[0062]
Next, various trace components of olive oil will be described.
Hereinafter, the types of various trace components of olive oil and the characteristics and functions of the components will be described.
(1). Unsaponifiable matter
(a) sterols,
(b) .Hydrocarbons
・ Squalene
Aromatic hydrocarbons (which give inherent sensory characteristics, ie scent and flavor)
(c). Tocopherols (antioxidation function)
・ Α-Tocopherol (vitamin E) (blackening and polymerization prevention)
・ Β, γ, δ-tocopherol (prevention of rancidity caused by the presence of heavy metals)
(d) .Triterpenes and alcohols
・ Cycloartenol
・ Eltro Diol
(e). Fat-soluble vitamins
・ Vitamin A, D (antioxidant action)
(2). Phospholipids, chlorophyll and derivatives
(a) Phospholipid
(b) .Chlorophyll (antioxidant action)
(3). Phenolic compounds
(a). Phenolic compounds (antioxidant action)
(b). Polyphenol (antioxidant action)
As can be seen from the above, olive oil has a high content of various trace components that act against the oxidation of fats and oils compared to other non-drying oils and drying oils, and is heat resistant (sterilized by autoclaving). It can be disinfected.) And is a durable lubricant.
[0063]
Next, other vegetable non-drying oils that can constitute lubricating oil for rolling bearing devices of high-speed rotating equipment such as the dental air turbine handpiece of the present invention will be described.
(i). Plant non-drying oils other than the above-mentioned olive oil include arachis oil.
Peanut oil is contained in 40-50% of seeds of peanuts (Arachis Hypogaea), and is squeezed from the seeds.
(ii) Oleysol oil is a vegetable non-drying oil other than the olive oil described above. Oleysol oil is produced from a sunflower mutant that is rich in linoleic acid (polyvalent) that is not non-drying oil. Today, with the efforts of agricultural chemists, we have succeeded in growing a sunflower, a mutant that is rich in oleic acid (monounsaturated fatty acid), and an oil named Oleisol was produced from this mutant. Yes. Oleysol oil is a non-drying oil similar to the olive oil described above.
[0064]
In a rolling bearing device for a high-speed rotating device such as a dental air turbine handpiece of the present invention, the difference in composition between the vegetable non-drying oil applied as a lubricating oil and other vegetable semi-drying oil or edible oil. It is shown in Table 1 below. In Table 1, olive oil, peanut oil, and oleisol oil are vegetable non-drying oils useful for the rolling bearing device of the present invention, and others indicate comparative vegetable semi-drying oils and drying oils.
The annotations in Table 1 are as follows.
(1) Mainly containing oleic acid and containing palmitooleic acid.
(2) Linoleic acid.
(3) Linolenic acid.
(4). Consists of palmitic acid, stearic acid, lauric acid and myristic acid.
In Table 1, (*) marks are vegetable oils for comparison.
[0065]
[Table 1]

[0066]
From Table 1, the following points are clear.
(i). Vegetable non-drying oils are rich in monovalent unsaturated fatty acids that are difficult to oxidize.
(ii). Vegetable non-drying oils are low in divalent to trivalent unsaturated fatty acids, that is, polyunsaturated fatty acids, which are easily oxidized.
(iii) Plant non-drying oils have a high ratio of polyunsaturated fatty acids to tocopherols (such as vitamin E) having an antioxidant action.
[0067]
In plant non-drying oils (olive oil, peanut oil, oleicol oil, etc.) that can constitute lubricating oil for rolling bearing devices of high-speed rotating equipment such as dental air turbine handpieces of the present invention, free fatty acids (saturated, non-saturated, The smaller the total content of (saturated), the better the lubricating properties.
This point was found in the process of improving the lubrication characteristics of the plant non-drying oil of the present inventors, and is supported by demonstration data as described later.
[0068]
The free fatty acid (hereinafter sometimes referred to as free fatty acid) in the above-described vegetable non-drying oil will be described below.
In general, fats and oils (fats such as beef tallow, pork tallow and butter, and fat oils such as rapeseed oil, tung oil and linseed oil) are composed of glycerin esters of higher fatty acids.
That is, in the vegetable non-drying oil useful for the rolling bearing device of the present invention, various fatty acids (saturated and unsaturated) exist as esters represented by the following formula (1).
3 molecules of fatty acid + 1 molecule of glycerin → 1 molecule of triglyceride (ester) (1)
[0069]
However, glycerin (Grycerol, CH ₂ OH-CHOH-CH ₂ Various fatty acids not bound to (OH) (free fatty acids) are also included. When the degree of the total content of free fatty acids described above is expressed in terms of free acidity, the lower the value, the lower the acidity and the viscosity also shifts to the higher viscosity side. Therefore, vegetable non-drying oil with low free acidity is a rolling bearing. It is excellent in durability as a lubricant for equipment.
Table 2 below classifies the quality of olive oil based on the above-mentioned free acidity. The higher the olive oil than Table 2, the lower the free acidity, and the better lubricating properties as described later (see Table 3).
In addition, as a method of lowering the free acidity of vegetable non-drying oil such as olive oil, for example, the following method may be employed. That is, when 5-10% sodium hydroxide is added to olive oil and heated, it is saponified to produce glycerin and a fatty acid sodium salt, and the produced glycerin is ester-bonded to a free fatty acid. Then, if oil and fat are separated and removed by centrifugation or the like, olive oil having a low free acidity can be obtained.
In Table 2, various grade names of olive oil are trade names of olive oil manufactured by Golden Eagle Olive Products, Inc. of the United States.
[0070]
[Table 2]

[0071]
As the base oil component of the lubricating oil of the present invention, various conventionally known mineral oil-based (natural) or synthetic base oil components can be used in addition to the above-described vegetable non-drying oil.
Examples of this type of mineral oil or synthetic base oil component include mineral oil (paraffin oil), olefin oligomers, phosphate esters, organic acid esters, silicone oils, polyalkylene glycols, and the like.
Although these base oil components are inferior to the above-mentioned plant non-drying oils in terms of biosafety (biological hazards) and environmental conservation (safety), they are sufficiently used for high-speed rotating equipment. It is something that can be done.
[0072]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to examples.
In particular, in a rolling bearing device of a dental air turbine handpiece, lubrication of lubricating oil to a bearing portion having a cage (retainer) composed of a non-metallic inorganic ball and a porous synthetic resin molded body according to the present invention. Compared to the effect of this, the lubrication effect of the lubricating oil on the bearing part having a cage (retainer) composed of a conventionally known stainless steel ball and a non-porous (bulk, non-porous) synthetic resin molded body The superiority of the lubricating system of the invention was studied. When the cage (retainer) composed of the porous synthetic resin molded body is referred to as “porous”, and the cage (retainer) composed of the non-porous synthetic resin molded body is referred to as “bulk”. There is.
Therefore, in the following description:
(1). Combination of stainless steel (SUS) rolling element (ball) and bulk (nonporous) cage (retainer),
(2) Combination of stainless steel (SUS) rolling element (ball) and porous cage (retainer), and
(3). Non-metallic, for example, a combination of rolling elements (balls) and bulk (nonporous) cages (retainers) made of silicon nitride, zirconia, pyrex, etc. is a comparative example of the present invention. It will be.
[0073]
(i). Overall structure of the dental air turbine handpiece subjected to the test:
Dental air turbine handpiece subjected to the test in Examples of the present invention
The configuration of the rolling bearing device (see FIGS. 1 and 2) is as follows.

Open-type miniature ball bearings with dimensions and having crown type retainers
It is.
[0074]
(ii). Air pressure and air supply conditions:
The rolling bearing device is mounted on a dental air turbine handpiece, and the supply air pressure is 1.8 kgf / cm. ² The test was performed under the condition of an air supply amount of 25 liters / minute.
[0075]
(iii) Type of retainer:
(1). Bulk PI / PAI · R This means a non-porous (bulk) retainer of polyimide (PI) type or polyamideimide (PAI) type. That is, the retainer (retainer) having a communicating structure different from the retainers (retainer) of the first embodiment to the third embodiment described above of the present invention and having no pore portion is shown.
The bulk PI · R is obtained by processing Vespel SP-1 manufactured by DuPont into a retainer shape.
Further, the bulk PAI · R is obtained by processing Torlon 4203 manufactured by Teijin Amoco Engineering Plastics into a retainer shape.
[0076]
(2). Porous P · R: This means a porous retainer made of cloth-containing phenolic resin. That is, this retainer shows the retainer (retainer) of the third embodiment described above of the present invention.
The porous P · R is obtained by impregnating a woven fabric wound in a pipe shape with a phenol resin between the woven fabric in a vacuum state, thermoforming, and then processing into a retainer shape.
[0077]
(3). Porous PI / PAI · R This means a polyamide (PI) -based or polyamide-imide (PAI) -based porous retainer.
For the porous PI · R, UIP-S manufactured by Ube Industries, Ltd. is molded at a pressure of 4000 kgf / cm. ² This is compression molded at (392 MPa), sintered at 400 ° C. in a nitrogen atmosphere, and processed into a retainer shape (porosity: volume ratio of about 13%).
In addition, the porous PAI.R is classified by classifying Torlon 4000TF manufactured by Amoco USA into an average particle size of 20 μm, and a molding pressure of 2800 kgf / cm. ² (274 MPa) compression molded, then sintered at 300 ° C., and processed into a retainer shape (porosity: volume ratio of about 14%).
[0078]
A. Evaluation of biological safety, environmental conservation, and heat resistance of various lubricants:
Using a rolling bearing device for a dental air turbine handpiece (see FIGS. 1 and 2), a lubrication system mainly composed of vegetable non-drying oil and lubrication mainly composed of conventionally known paraffin oil and fluorinated oil The system was tested for biosafety, environmental conservation, and heat resistance (autoclave resistance; times). The results are shown in Table 3 below.
[0079]
The annotations in Table 3 are as follows.
(1) <Heat resistance test (autoclave resistance; times)>
The autoclave resistance was examined using an autoclave device “Alfie” manufactured by Morita Manufacturing Co., Ltd. A result is shown by the number of times until the rotation of the dental air turbine handpiece becomes unstable and the rotation efficiency decreases by 10% (10%, about 40,000 rpm).
In addition, since it is thought that the said test is not influenced so much by the kind of rolling element (ball), the thing made from the conventional stainless steel is used as a ball | bowl, and supply pressure is 1.8 kgf / cm. ² The test was conducted under the condition of about 400,000 rpm with an air supply rate of 25 liters / minute. The processing conditions in the autoclave device “Alfie” are as follows: the vapor pressure is 2.4 kgf / cm. ² (235 Pa), temperature 135 ° C., time 5 minutes.
[0080]
In Table 3,
(i) For paraffin oil (liquid parifin), an existing dental treatment related manufacturer spray was used.
(ii) FOMBLIN manufactured by Ausimontu SPA, Italy was used as the fluorinated oil.
[0081]
[Table 3]

[0082]
B. Evaluation of lubrication performance of various lubricants:
Next, various lubricating oils were applied to the rolling bearing device of the dental air turbine handpiece (see FIGS. 1 to 2) to evaluate the lubricating performance.
In particular, in the case of using vegetable non-drying oil (extra virgin olive oil) as the lubricating oil, the lubricating performance due to the difference in the configuration of the rolling element (ball) and the cage (retainer), that is, (i) high-speed rotation performance, (ii ) It was tested what effect was achieved in the characteristics of rotational durability.
[0083]
As described above, (i) the high-speed rotation performance is achieved by first applying lubricating oil to the dental arturbine handpiece (see FIGS. 1 to 2) and supplying air pressure of 1.8 kgf / cm. ² , The number of rotations when air is supplied at a supply rate of 25 liters / minute (× 10 ^Four ).
In addition, the (ii) rotation endurance time is the period from the state (i) until continuous operation without oiling until the rotation becomes unstable and the rotation speed decreases by 10% (10%, about 40,000 rpm). Evaluation was made in terms of time (hrs).
[0084]
The results are shown in Table 4 below.
(A) In the table, “SUS” in the ball column means a stainless steel (SUS440C) ball bearing. Others refer to the non-metallic inorganic balls of the present invention.
(B) In the table, “Bulk” in the retainer column means bulk IP / PAI · R. “Porous” means porous PI / PAI · R. Furthermore, “phenol” means porous P · R.
(C) In the table, “bio oil” in the oil column means extra virgin olive oil. “Water” means water lubrication.
[0085]
[Table 4]

[0086]
【The invention's effect】
The superiority of the present invention can be easily understood from Tables 3 to 4.
As shown in Table 3, in lubricating oil applied to high-speed rotating equipment such as a high-speed rotating dental cutter (air turbine handpiece), especially lubricating oil mainly composed of vegetable non-drying oil is It turns out that it is excellent in terms of safety (harmful to human body), environmental conservation (safety), and heat resistance (autoclave resistance).
In addition, since it is cheaper than fluorinated oils, it is excellent in economic efficiency.
Further, semi-drying oils other than non-drying oils, dry oils, and paraffin oils (liquid paraffins) as plants have a drastic change in color tone in a test that is left in air at 135 ° C. for 175 hours. In other words, these various oils are inferior in oxidation resistance. In the test, non-drying oils such as olive oil and peanut oil showed no color change.
[0087]
In addition, the lubricating oil mainly composed of vegetable non-drying oil applied to the high-speed rotating dental air turbine handpiece of the present invention is rapidly decomposed by microorganisms, and evaluated based on the provisional water quality standard (Prime Ministerial Ordinance) of wastewater. It is more preferable than conventional mineral oils. According to the provisional water quality standard for waste water, the allowable limit of waste water is 5 mg / liter for conventional mineral oils, whereas it is 30 mg / liter for vegetable oils.
[0088]
Furthermore, as shown in Table 4, the rolling bearing device of the present invention, that is, the rolling elements (balls) and the cages (retainers) of the bearing part are composed of non-metallic inorganic balls and porous synthetic resin molded bodies, respectively. In such a rolling bearing device, when vegetable non-drying oil is used as the lubricating oil, it is possible to realize a remarkable improvement in characteristics that is not seen in the conventional rolling bearing device.
[0089]
Furthermore, the rolling bearing device using the non-metallic inorganic ball of the present invention has no sound that the metal ball runs on the metal race as compared to the one using the metal ball and the race. In addition, an effect of being extremely quiet (noiseless) can be obtained as compared with a bulk retainer made of nonporous synthetic resin.
[Brief description of the drawings]
FIG. 1 is a perspective view of a dental air turbine handpiece provided with a rolling bearing device according to a first embodiment of the present invention.
2 is a cross-sectional view of a head portion (H) and a neck portion (N) of the dental air turbine handpiece of FIG. 1, and is a view for explaining the structure of the head portion (H) and the neck portion (N). is there.
FIG. 3 is a perspective view of the retainer (44) shown in FIG.
FIG. 4 is a cross-sectional view of a dental air turbine handpiece provided with a rolling bearing device according to a second embodiment of the present invention, and corresponds to FIG.
FIG. 5 is a cross-sectional view of the cage (44) shown in FIG.
[Explanation of symbols]
A ............ Dental Air Turbine Handpiece
H ………… Head
G: Grip part
N ............ Neck part of grip part (G)
B ............ Cutting tool
1 ………… Head
11 ………… Chamber
12 ………… Head body
13 ............ Cap part
2 ………… Turbine blade
3 ………… Turbine rotor shaft
4 ………… Bearing
41 ………… Inner ring
42 ………… Outer ring
43 ………… Rolling element (ball)
44 ………… Retainer
44a ............ Main body of cage
44b ............ Hole (pore)
5 ………… Cutting tool
6 ............ Neck (N) body
7 ………… Air supply path
71 ………… Air supply port
8, 9 ............ Exhaust passage
81, 91 ............ Exhaust port

Claims (9)

In a rolling bearing device for a high-speed rotating device having a rolling bearing element composed of an outer ring, an inner ring, a rolling element, and a cage (retainer) for rotatably supporting at least a rotating shaft lubricated with lubricating oil ,
(i). The rolling elements are made of non-metallic inorganic balls, and
(ii). The cage (retainer) is composed of a porous synthetic resin molded body having a pore portion having a communication structure at least in part,
(iii). The lubricating oil contains at least 60% by weight of at least one monounsaturated fatty acid containing one unsaturated bond per molecule and a polyunsaturated unsaturated compound having at least two unsaturated bonds per molecule. Composed of a lubricating oil composed of vegetable non-drying oil containing 30% by weight or less of fatty acid ,
A rolling bearing device for high-speed rotating equipment. The rolling bearing device for high-speed rotating equipment according to claim 1, wherein the non-metallic inorganic balls constituting the rolling elements are made of non-oxidized ceramic material, oxidized ceramic material, heat-resistant glass, or crystallized glass. . A porous synthetic resin molded body having a pore portion of a communication structure constituting a cage (retainer) ,
(1). A polyimide resin molded body having a pore portion with a porosity of 5 to 20% by volume, or
(2). A phenolic resin molded article having a fiber layer with a porosity of 5 to 20% by volume as the pores of the communication structure,
The rolling bearing device for a high-speed rotating device according to claim 1 , wherein the rolling bearing device is selected from. The rolling bearing device for a high-speed rotating device according to claim 3, wherein the polyimide resin molded body having pores having a communication structure is prepared by sintering and molding a resin powder body. Vegetable non-drying oils, the content of tocopherols rolling bearing device for a high-speed rotating equipment of claim 1 wherein composed of 10 wt% or less. Vegetable non-drying oils, olive oil, peanut oil, and the rolling bearing device for a high-speed rotating equipment of claim 1 wherein at least one of those selected from the group consisting of Oreisoru oil. Vegetable non-drying oils, saturated unbound glycerin and unsaturated fatty acid content (free fatty acids) is for high-speed rotation apparatus according to the sixth claims consists of those 5 wt% or less Rolling bearing device. A high-speed rotating device has a rolling bearing element composed of an outer ring, an inner ring, a rolling element, and a heat-resistant resin cage (retainer) for rotatably supporting a rotating shaft to which an air turbine blade is fixed. The rolling bearing device for a high-speed rotating device according to claim 1 . The rolling bearing device for a high-speed rotating device according to claim 8, wherein the high-speed rotating device is a ball bearing type medical dental air turbine handpiece .

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