JP3981564B2 - Hydrodynamic bearing device and manufacturing method thereof - Google Patents

Hydrodynamic bearing device and manufacturing method thereof Download PDF

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JP3981564B2
JP3981564B2 JP2002042624A JP2002042624A JP3981564B2 JP 3981564 B2 JP3981564 B2 JP 3981564B2 JP 2002042624 A JP2002042624 A JP 2002042624A JP 2002042624 A JP2002042624 A JP 2002042624A JP 3981564 B2 JP3981564 B2 JP 3981564B2
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bearing
thrust
housing
thrust bearing
end surface
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JP2003239974A (en
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信好 山下
正明 戸田
栗村　　哲弥
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NTN Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C43/00—Assembling bearings
    • F16C43/02—Assembling sliding-contact bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
    • F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
    • F16C17/107—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure with at least one surface for radial load and at least one surface for axial load
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
    • F16C33/107—Grooves for generating pressure

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Sliding-Contact Bearings (AREA)
  • Mounting Of Bearings Or Others (AREA)
  • Powder Metallurgy (AREA)
  • Motor Or Generator Frames (AREA)
  • Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)

Description

【０００１】
【発明の属する技術分野】
本発明は、軸受隙間に生じる潤滑油の動圧作用で回転部材を非接触支持する動圧軸受装置に関する。この軸受装置は、情報機器、例えばＨＤＤ、ＦＤＤ等の磁気ディスク装置、ＣＤ−ＲＯＭ、ＣＤ−Ｒ／ＲＷ、ＤＶＤ−ＲＯＭ／ＲＡＭ等の光ディスク装置、ＭＤ、ＭＯ等の光磁気ディスク装置などのスピンドルモータ、レーザビームプリンタ（ＬＢＰ）のポリゴンスキャナモータ、あるいは電気機器、例えば軸流ファンなどの小型モータ用として好適である。
【０００２】
【従来の技術】
上記各種モータには、高回転精度の他、高速化、低コスト化、低騒音化などが求められている。これらの要求性能を決定づける構成要素の一つに当該モータのスピンドルを支持する軸受があり、近年では、この種の軸受として、上記要求性能に優れた特性を有する動圧軸受の使用が検討され、あるいは実際に使用されている。
【０００３】
例えば、ＨＤＤ等のディスク装置のスピンドルモータに組込まれる動圧軸受装置では、軸部材をラジアル方向に回転自在に非接触支持するラジアル軸受部と、軸部材をスラスト方向に回転自在に非接触支持するスラスト軸受部とが設けられ、これら軸受部として、軸受面に動圧発生用の溝（動圧溝）を有する動圧軸受が用いられる。ラジアル軸受部の動圧溝は、軸受スリーブの内周面又は軸部材の外周面に形成され、スラスト軸受部の動圧溝は、フランジ部を備えた軸部材を用いる場合、そのフランジ部の両端面、又は、これに対向する面（軸受スリーブの端面や、ハウジングに固定されるスラスト部材の端面等）にそれぞれ形成される。通常、軸受スリーブはハウジングの内周の所定位置に固定され、また、ハウジングの底部をスラスト部材で構成する場合は、該スラスト部材を位置決めするためのインロー部（段状の部位）をハウジングに設ける場合が多い（スラスト部材をインロー部に嵌め合わせることで、ハウジングに対するスラスト部材の位置決めを行う。）。さらに、ハウジングの内部空間に注油した潤滑油が外部に漏れるのを防止するために、ハウジングの開口部にシール部材を配設する場合が多い。
【０００４】
【発明が解決しようとする課題】
上記構成の動圧軸受装置は、ハウジング、軸受スリーブ、軸部材、スラスト部材、及びシール部材といった部品で構成され、情報機器の益々の高性能化に伴って必要とされる高い軸受性能を確保すべく、各部品の加工精度や組立精度を高める努力がなされている。特に、スラスト軸受隙間の大きさは、軸部材のフランジ部の軸方向寸法や両端面の面精度、スラスト軸受面となる軸受スリーブおよびスラスト部材の端面の面精度といった部品精度と、軸受スリーブとスラスト部材との間の軸方向スペースといった組立精度の影響を受けることから、所望値に管理するのが難しく、そのために、必要以上に高精度な部品加工や複雑な組立作業を強いられているのが実状である。一方、情報機器の低価格化の傾向に伴い、この種の動圧軸受装置に対するコスト低減の要求も益々厳しくなっている。
【０００７】
本発明の課題は、この種の動圧軸受装置におけるスラスト軸受隙間を簡易かつ精度良く設定することができる方法を提供することである。
【０００８】
【課題を解決するための手段】
上記課題を解決するため、本発明は、側部および底部を有するコップ状のハウジングと、ハウジングの内周に固定された軸受スリーブと、軸部およびフランジ部を有する軸部材と、軸受スリーブの内周面と軸部の外周面との間に設けられ、ラジアル軸受隙間に生じる潤滑油の動圧作用で軸部をラジアル方向に非接触支持するラジアル軸受部と、軸受スリーブの一端面とこれに対向するフランジ部の一端面との間に設けられ、スラスト軸受隙間に生じる潤滑油の動圧作用でフランジ部をスラスト方向に非接触支持する第１スラスト軸受部と、ハウジングの底部の内底面とこれに対向するフランジ部の他端面との間に設けられ、スラスト軸受隙間に生じる潤滑油の動圧作用でフランジ部をスラスト方向に非接触支持する第２スラスト軸受部とを備えた動圧軸受装置、の製造方法であって、ハウジングの内底面にフランジ部の他端面を当接させると共に、フランジ部の一端面に軸受スリーブの一端面を当接させ、フランジ部の一端面に軸受スリーブの一端面を当接させた状態で、軸受スリーブを、フランジ部と伴に、第１スラスト軸受部及び第２スラスト軸受部のスラスト軸受隙間の合計量に相当する寸法だけ、ハウジングに対して軸方向に相対移動させて、第１スラスト軸受部及び第２スラスト軸受部のスラスト軸受隙間を所定寸法に形成する構成を提供する。
【００１０】
上記構成において、ハウジングは金属製又は樹脂製とすることができる。前者の場合、マグネシウム等の金属粉末の射出成形、アルミ合金等のダイキャスト、金属板のプレス加工（板材又はパイプ材の絞り成形）等の型成形によりハウジングを形成することができる。また、後者の場合、樹脂の射出成形等の型成形によりハウジングを形成することができる。
【００１１】
第２スラスト軸受部を構成する動圧溝はハウジングの内底面およびフランジ部の他端面のうち一方に設ければよいが、ハウジングの内底面に設ける場合、該動圧溝を側部および底部と共に型成形により形成することができる。これにより、該動圧溝の別途加工を不要として、加工コストの低減を図ることができる。
【００１２】
ここで、上記の金属粉末の射出成形法は「メタル・インジェクション・モールディング」（ＭＩＭ：Metal Injection Molding）と呼ばれている。このＭＩＭ法は、一般に、金属粉末と樹脂バインダとを混練後、金型に射出して成形し、続いて脱脂してバインダを除いた成形体を焼結して完成品とする成形法であり（焼結後、必要に応じて後処理を行う。）、次のような特長を有している。すなわち、▲１▼複雑な形状の小物部品をニア・ネット・シェイプで形成することができ、▲２▼金型形状を転写し同一形状のものを量産することができ、▲３▼成型時の収縮率、脱脂・焼結時の収縮率などを見極めることにより、寸法精度の高い部品を生産することができ、▲４▼金型形状を転写するので、金型の仕上精度と同一の面精度（面粗度等）を確保することができ、▲５▼ステンレス鋼等の難加工材のニア・ネット・シェイプ化が可能である。
【００１３】
ハウジングを上記のＭＩＭ法で形成することにより、生産性が高まると共に、スラスト軸受面となる内底面の面粗度等を精度良く仕上げることができるので、加工コストの低減になる。また、成形金型の所要部位に動圧溝の形状を加工しておくことにより、内底面に動圧溝を成形と同時に形成（転写）することができるので、その後の動圧溝加工を不要として、加工コスト低減を図ることもできる。
【００１５】
例えば、スラスト部材を具備し、その位置設定をハウジングに設けたインロー部（段状の部位）で行う（スラスト部材をインロー部に嵌め合わせることで、ハウジングに対するスラスト部材の位置決めを行う。）構成では、ハウジングに対する軸受スリーブの位置決めを専用の治具で行う必要があるので、各部品を最終的に組立み合わせたとき、スラスト軸受隙間が、スラスト面（フランジ部の両端面、軸受スリーブおよびスラスト部材の端面）の面精度の影響を受ける。これに対して、本発明の構成では、ハウジングの内底面にフランジ部の他端面を当接させると共に、フランジ部の一端面に軸受スリーブの一端面を当接させた状態、すなわち第１スラスト軸受部及び第２スラスト軸受部のスラスト軸受隙間がゼロの状態から、フランジ部の一端面に軸受スリーブの一端面を当接させた状態で、軸受スリーブをフランジ部と伴に相対移動させて、軸受スリーブのハウジングに対する位置を設定するので、スラスト軸受隙間がスラスト面の面精度の影響を受けない。そのため、スラスト軸受隙間を精度良く形成することができ、これにより軸受性能の一層の向上を図ることができる。しかも、スラスト軸受隙間を精度良く形成するために、必要以上に高精度な部品加工や複雑な組立作業を行う必要がないので、動圧軸受装置の製造コスト低減にもなる。
【００１６】
上記構成において、軸受スリーブをハウジングに固定する手段として、エポキシ系接着剤等による接着、圧入、レーザビーム溶接（ハウジングの外径側から軸受スリーブの固定部位にレーザビームを照射する。あるいは、軸受スリーブの固定部位に直接レーザビームを照射する。）、高周波パルス接合、加締め等を採用することができる。
【００１７】
上記構成において、軸受スリーブの他端面の側に、ハウジングの内部空間をシールするシール手段を設けることができる。このシール手段は、シール部材をハウジングに固定することによって形成することができる。この場合、シール部材の固定手段として、エポキシ系接着剤等による接着、圧入、レーザビーム溶接（ハウジングの外径側からシール部材の固定部位にレーザビームを照射する。あるいは、シール部材の固定部位に直接レーザビームを照射する。）、高周波パルス接合、加締め等を採用することができる。
【００１８】
上記構成において、軸受スリーブは焼結金属で形成することができる。
【００２２】
【発明の実施の形態】
以下、本発明の実施形態について説明する。
【００２３】
図１は、この実施形態に係る動圧軸受装置１を組み込んだ情報機器用スピンドルモータの一構成例を示している。このスピンドルモータは、ＨＤＤ等のディスク駆動装置に用いられるもので、軸部材２を回転自在に非接触支持する動圧軸受装置１と、軸部材２に装着されたディスクハブ３と、例えば半径方向のギャップを介して対向させたモータステータ４およびモータロータ５とを備えている。ステータ４はケーシング６の外周に取付けられ、ロータ５はディスクハブ３の内周に取付けられる。動圧軸受装置１のハウジング７は、ケーシング６の内周に装着される。ディスクハブ３には、磁気ディスク等のディスクＤが一又は複数枚保持される。ステータ４に通電すると、ステータ４とロータ５との間の励磁力でロータ５が回転し、それによって、ディスクハブ３および軸部材２が一体となって回転する。
【００２４】
図２は、動圧軸受装置１を示している。この動圧軸受装置１は、ハウジング７と、軸受スリーブ８と、軸部材２と、シール部材１０とを構成部品して構成される。
【００２５】
軸受スリーブ８の内周面８ａと軸部材２の軸部２ａの外周面２ａ１との間に第１ラジアル軸受部Ｒ１と第２ラジアル軸受部Ｒ２とが軸方向に離隔して設けられる。また、軸受スリーブ８の下側端面８ｃと軸部材２のフランジ部２ｂの上側端面２ｂ１との間に第１スラスト軸受部Ｓ１が設けられ、ハウジング７の底部７ｃの内底面７ｃ１とフランジ部２ｂの下側端面２ｂ２との間に第２スラスト軸受部Ｓ２が設けられる。尚、説明の便宜上、ハウジング７の開口部７ａの側を上側、底部７ｃの側を下側として説明を進める。
【００２６】
図４（ａ）に示すように、ハウジング７は、例えば、マグネシウム等の金属粉末からＭＩＭ法でコップ状に形成され、円筒状の側部７ｂと、底部７ｃとを一体に備えている。側部７ｂの上端は開口部７ａになっている。また、第２スラスト軸受部Ｓ２のスラスト軸受面となる、底部７ｃの内底面７ｃ１には、例えば図４（ｂ）に示すようなヘリングボーン形状の動圧溝７ｃ２が形成される。この動圧溝７ｃ２は、側部７ｂおよび底部７ｃと共にＭＩＭ法の金型で成形（成形金型で転写）されたものである。尚、動圧溝の形状として、スパイラル形状や放射溝形状等を採用しても良い。
【００２７】
軸部材２は、例えば、ステンレス鋼等の金属材で形成され、軸部２ａと、軸部２ａの下端に一体又は別体に設けられたフランジ部２ｂとを備えている。
【００２８】
軸受スリーブ８は、例えば、焼結金属からなる多孔質体、特に銅を主成分とする燒結金属の多孔質体で円筒状に形成され、接着、圧入、レーザビーム溶接、高周波パルス接合等の適宜の手段により、ハウジング７の内周の所定位置に固定される。軸受スリーブ８の上側端面８ｂはシール部材１０に当接している。
【００２９】
この焼結金属で形成された軸受スリーブ８の内周面８ａには、第１ラジアル軸受部Ｒ１と第２ラジアル軸受部Ｒ２のラジアル軸受面となる上下２つの領域が軸方向に離隔して設けられ、該２つの領域には、例えば図３（ａ）に示すようなヘリングボーン形状の動圧溝８ａ１、８ａ２がそれぞれ形成される。尚、動圧溝の形状として、スパイラル形状や軸方向溝形状等を採用しても良い。
【００３０】
また、第１スラスト軸受部Ｓ１のスラスト軸受面となる、軸受スリーブ８の下側端面８ｃには、例えば図３（ｂ）に示すようなスパイラル形状の動圧溝８ｃ１が形成される。尚、動圧溝の形状として、ヘリングボーン形状や放射溝形状等を採用しても良い。
【００３１】
軸部材２の軸部２ａは軸受スリーブ８の内周面８ａに挿入され、フランジ部２ｂは軸受スリーブ８の下側端面８ｃとハウジング７の内底面７ｃ１との間の空間部に収容される。
【００３２】
シール部材１０は、接着、圧入、レーザビーム溶接、高周波パルス接合等の適宜の手段によりハウジング７の開口部７ａに固定され、その内周面１０ａは、軸部２ａの外周面２ａ１と所定のシール空間を介して対向する。そして、シール部材１０で密封されたハウジング７の内部空間に潤滑油が給油される。
【００３３】
軸部材２の回転時、軸受スリーブ８の内周面８ａのラジアル軸受面となる領域（上下２箇所の領域）は、それぞれ、軸部２ａの外周面２ａ１とラジアル軸受隙間を介して対向する。また、軸受スリーブ８の下側端面８ｃのスラスト軸受面となる領域はフランジ部２ｂの上側端面２ｂ１とスラスト軸受隙間を介して対向し、ハウジング７の内底面７ｃ１のスラスト軸受面となる領域はフランジ部２ｂの下側端面２ｂ２とスラスト軸受隙間を介して対向する。そして、軸部材２の回転に伴い、上記ラジアル軸受隙間に潤滑油の動圧が発生し、軸部材２の軸部２ａが上記ラジアル軸受隙間内に形成される潤滑油の油膜によってラジアル方向に回転自在に非接触支持される。これにより、軸部材２をラジアル方向に回転自在に非接触支持する第１ラジアル軸受部Ｒ１と第２ラジアル軸受部Ｒ２とが構成される。同時に、上記スラスト軸受隙間に潤滑油の動圧が発生し、軸部材２のフランジ部２ｂが上記スラスト軸受隙間内に形成される潤滑油の油膜によって両スラスト方向に回転自在に非接触支持される。これにより、軸部材２をスラスト方向に回転自在に非接触支持する第１スラスト軸受部Ｓ１と第２スラスト軸受部Ｓ２とが構成される。
【００３４】
この実施形態の動圧軸受装置１は、例えば、図５〜図８に示すような態様で組立てる。
【００３５】
まず、図５に示すように、軸部材２に軸受スリーブ８を装着し、ハウジング７の内周に挿入する。尚、軸受スリーブ８はハウジング７の内周に圧入しても良い。
【００３６】
つぎに、図６に示すように、軸受スリーブ８を軸部材２と伴に下方に推し進めて、フランジ部２ｂの下側端面２ｂ２をハウジング７の内底面７ｃ１に当接させ、同時に、軸受スリーブ８の下側端面８ｃをフランジ部２ｂの上側端面２ｂ１に当接させる。この状態が、スラスト軸受隙間ゼロ（第１スラスト軸受部Ｓ１および第２スラスト軸受部Ｓ２のスラスト軸受隙間がゼロ）の状態である。尚、軸部材２を先にハウジング７の内周に挿入し、その後、軸受スリーブ８を軸部材２に装着すると共にハウジング７の内周に挿入（又は圧入）して、図６に示す状態を達成しても良い。
【００３７】
つぎに、図７に示すように、ハウジング７の開口部７ａにシール部材１０を挿入（又は圧入）して、軸受スリーブ８の上側端面８ｂに当接させる。
【００３８】
つぎに、図８に示すように、軸部材２を軸受スリーブ８およびシール部材１０と伴に、第１スラスト軸受部Ｓ１のスラスト軸受隙間（大きさをδ１とする。）と第２スラスト軸受部Ｓ２のスラスト軸受隙間（大きさをδ２とする。）の合計量に相当する寸法δ（δ＝δ１＋δ２）だけ、ハウジング７に対して軸方向（同図では上方）に相対移動させる。そして、軸受スリーブ８およびシール部材１０をその位置でハウジング７に固定すると、所定のスラスト軸受隙間δ（δ＝δ１＋δ２）が形成される。尚、シール部材１０は、所定のスラスト軸受隙間δ（δ＝δ１＋δ２）を形成した後、ハウジング７の開口部７ａに挿入（又は圧入）しても良い。
【００３９】
上記の方法によれば、動圧軸受装置１の各構成部品を実際に組み合わせてスラスト軸受隙間ゼロの状態を一旦実現し、その状態から、ハウジング７と軸受スリーブ８とを軸方向に所定量相対移動させてスラスト軸受隙間を形成するので、上記の軸方向相対移動量δ（δ＝δ１＋δ２）を管理するだけで、スラスト面（８ｃ、７ｃ１、２ｂ１、２ｂ２）の面精度、フランジ部２ｂの軸方向寸法精度等の影響を受けることなく、スラスト軸受隙間を精度良く形成することができる。
【００４０】
【発明の効果】
本発明によれば、部品精度の影響を受けることなく、スラスト軸受隙間を精度良くかつ簡易に設定することができる。これにより、部品の加工コストや組立コストを低減することができる。
【図面の簡単な説明】
【図１】本発明の実施形態に係る動圧軸受装置を有するスピンドルモータの断面図である。
【図２】本発明の実施形態に係る動圧軸受装置を示す断面図である。
【図３】軸受スリーブの断面図｛図３（ａ）｝、下側端面を示す図｛図３（ｂ）｝である。
【図４】ハウジングの断面図｛図４（ａ）｝、内底面の平面図｛図４（ｂ）｝である。
【図５】図２に示す動圧軸受装置の組立工程を示す断面図である。
【図６】図２に示す動圧軸受装置の組立工程を示す断面図である。
【図７】図２に示す動圧軸受装置の組立工程を示す断面図である。
【図８】図２に示す動圧軸受装置の組立工程を示す断面図である。
【符号の説明】
１ 動圧軸受装置
２ 軸部材
２ａ 軸部
２ｂ フランジ部
２ｂ１ 上側端面
２ｂ２ 下側端面
７ ハウジング
７ｂ 側部
７ｃ 底部
７ｃ１ 内底面
８ 軸受スリーブ
８ａ 内周面
８ｂ 上側端面
８ｃ 下側端面
１０ シール部材
Ｒ１ 第１ラジアル軸受部
Ｒ２ 第２ラジアル軸受部
Ｓ１ 第１スラスト軸受部
Ｓ２ 第２スラスト軸受部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrodynamic bearing device that supports a rotating member in a non-contact manner by the hydrodynamic action of lubricating oil generated in a bearing gap. This bearing device is a spindle of information equipment such as magnetic disk devices such as HDD and FDD, optical disk devices such as CD-ROM, CD-R / RW and DVD-ROM / RAM, and magneto-optical disk devices such as MD and MO. It is suitable for a motor, a polygon scanner motor of a laser beam printer (LBP), or an electric device such as a small motor such as an axial fan.
[0002]
[Prior art]
In addition to high rotational accuracy, the various motors are required to have high speed, low cost, low noise, and the like. One of the components that determine the required performance is a bearing that supports the spindle of the motor, and in recent years, as this type of bearing, the use of a hydrodynamic bearing having characteristics excellent in the required performance has been studied. Or it is actually used.
[0003]
For example, in a hydrodynamic bearing device incorporated in a spindle motor of a disk device such as an HDD, a radial bearing portion that supports a shaft member in a non-contact manner in a radial direction and a shaft member is supported in a non-contact manner in a thrust direction. A thrust bearing portion is provided, and a dynamic pressure bearing having a dynamic pressure generating groove (dynamic pressure groove) on the bearing surface is used as these bearing portions. The dynamic pressure groove of the radial bearing portion is formed on the inner peripheral surface of the bearing sleeve or the outer peripheral surface of the shaft member, and the dynamic pressure groove of the thrust bearing portion uses both ends of the flange portion when a shaft member having a flange portion is used. It is formed on a surface or a surface facing the surface (an end surface of the bearing sleeve, an end surface of a thrust member fixed to the housing, etc.). Usually, the bearing sleeve is fixed at a predetermined position on the inner periphery of the housing, and when the bottom portion of the housing is constituted by a thrust member, an inlay portion (stepped portion) for positioning the thrust member is provided in the housing. There are many cases (the thrust member is positioned with respect to the housing by fitting the thrust member to the inlay portion). Furthermore, in order to prevent the lubricating oil injected into the internal space of the housing from leaking to the outside, a seal member is often provided at the opening of the housing.
[0004]
[Problems to be solved by the invention]
The hydrodynamic bearing device having the above-described configuration is composed of parts such as a housing, a bearing sleeve, a shaft member, a thrust member, and a seal member, and ensures high bearing performance required as the performance of information equipment increases. Therefore, efforts are being made to increase the processing accuracy and assembly accuracy of each part. In particular, the size of the thrust bearing gap includes the axial dimensions of the flange portion of the shaft member, the surface accuracy of both end surfaces, the bearing sleeve that becomes the thrust bearing surface and the surface accuracy of the end surface of the thrust member, the bearing sleeve and the thrust. Because it is affected by the assembly accuracy such as the axial space between the members, it is difficult to manage it to the desired value. For this reason, it is compelling to process parts with higher precision and complex assembly work than necessary. It's real. On the other hand, with the trend toward lower prices of information equipment, the demand for cost reduction for this type of hydrodynamic bearing device has become increasingly severe.
[0007]
An object of the present invention is to provide a method capable of easily and accurately setting a thrust bearing gap in this type of hydrodynamic bearing device.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a cup-shaped housing having side portions and a bottom portion, a bearing sleeve fixed to the inner periphery of the housing, a shaft member having a shaft portion and a flange portion, and an inner portion of the bearing sleeve. A radial bearing portion that is provided between the peripheral surface and the outer peripheral surface of the shaft portion, and that supports the shaft portion in a non-contact manner in the radial direction by the dynamic pressure action of lubricating oil generated in the radial bearing gap, and one end surface of the bearing sleeve and A first thrust bearing portion provided between one end surfaces of the opposing flange portions and supporting the flange portions in a non-contact manner in the thrust direction by a dynamic pressure action of lubricating oil generated in a thrust bearing gap; and an inner bottom surface of a bottom portion of the housing; A second thrust bearing portion provided between the other end surface of the flange portion facing this and supporting the flange portion in the thrust direction in a non-contact manner by the dynamic pressure action of lubricating oil generated in the thrust bearing gap. Dynamic pressure bearing device, a method of manufacturing, is brought into contact with the other end surface of the flange portion on the inner bottom surface of the housing, is brought into contact with one end face of the bearing sleeve on one end surface of the flange portion, one end surface of the flange portion With the one end surface of the bearing sleeve in contact with the bearing sleeve, the bearing sleeve is attached to the housing by a dimension corresponding to the total amount of the thrust bearing clearance of the first thrust bearing portion and the second thrust bearing portion together with the flange portion. A configuration is provided in which the thrust bearing gap between the first thrust bearing portion and the second thrust bearing portion is formed in a predetermined dimension by relatively moving in the axial direction .
[0010]
In the above configuration, the housing can be made of metal or resin. In the former case, the housing can be formed by molding such as injection molding of metal powder such as magnesium, die casting of aluminum alloy or the like, press working of a metal plate (drawing molding of a plate material or pipe material), and the like. In the latter case, the housing can be formed by molding such as resin injection molding.
[0011]
The dynamic pressure groove constituting the second thrust bearing portion may be provided on one of the inner bottom surface of the housing and the other end surface of the flange portion. When the dynamic pressure groove is provided on the inner bottom surface of the housing, the dynamic pressure groove is formed together with the side portion and the bottom portion. It can be formed by molding. This eliminates the need for separate processing of the dynamic pressure grooves, and can reduce processing costs.
[0012]
Here, the above-described metal powder injection molding method is called “metal injection molding” (MIM). This MIM method is generally a molding method in which a metal powder and a resin binder are kneaded and then injected and molded into a mold, followed by degreasing and sintering the molded body from which the binder has been removed to obtain a finished product. (After sintering, post-treatment is performed as necessary.), It has the following features. In other words, (1) small parts with complicated shapes can be formed with near net shapes, (2) mold shapes can be transferred and mass-produced with the same shapes, and (3) molding By determining the shrinkage rate, shrinkage rate during degreasing and sintering, etc., it is possible to produce parts with high dimensional accuracy. (4) Since the mold shape is transferred, the same surface accuracy as the finish accuracy of the mold (Roughness, etc.) can be ensured, and (5) near-net-shape of difficult-to-work materials such as stainless steel can be made.
[0013]
By forming the housing by the above-described MIM method, productivity is increased and surface roughness of the inner bottom surface serving as the thrust bearing surface can be finished with high accuracy, thereby reducing processing costs. Also, by processing the shape of the dynamic pressure groove in the required part of the molding die, the dynamic pressure groove can be formed (transferred) on the inner bottom at the same time as molding, so subsequent dynamic pressure groove processing is unnecessary As a result, the processing cost can be reduced.
[0015]
For example, in a configuration in which a thrust member is provided and its position is set by an inlay portion (stepped portion) provided in the housing (the thrust member is positioned with respect to the housing by fitting the thrust member to the inlay portion). Because the bearing sleeve needs to be positioned with respect to the housing with a dedicated jig, the thrust bearing gaps are the thrust surfaces (the two end surfaces of the flange portion, the bearing sleeve and the thrust member) when the parts are finally assembled. It is affected by the surface accuracy of the edge surface. On the other hand, in the configuration of the present invention, the other end surface of the flange portion is brought into contact with the inner bottom surface of the housing, and the one end surface of the bearing sleeve is brought into contact with one end surface of the flange portion, that is, the first thrust bearing. The bearing sleeve is moved relative to the flange portion in a state where the thrust bearing gap between the first and second thrust bearing portions is zero and the one end surface of the bearing sleeve is in contact with the one end surface of the flange portion. because setting a position relative to the housing of the sleeve, the thrust bearing gap is not affected by the surface accuracy of the thrust face. For this reason, the thrust bearing gap can be formed with high accuracy, thereby further improving the bearing performance. In addition, in order to form the thrust bearing gap with high accuracy, it is not necessary to perform parts processing or complicated assembly work with higher precision than necessary, so that the manufacturing cost of the hydrodynamic bearing device can be reduced.
[0016]
In the above configuration, as means for fixing the bearing sleeve to the housing, bonding with an epoxy adhesive, press-fitting, laser beam welding (laser beam is irradiated to the fixing portion of the bearing sleeve from the outer diameter side of the housing, or the bearing sleeve. The laser beam is directly irradiated to the fixed part of the substrate.), High-frequency pulse bonding, caulking, etc. can be employed.
[0017]
In the above configuration, sealing means for sealing the internal space of the housing can be provided on the other end face side of the bearing sleeve. This sealing means can be formed by fixing the sealing member to the housing. In this case, as a means for fixing the seal member, bonding with an epoxy adhesive or the like, press-fitting, laser beam welding (irradiating a laser beam to a fixing portion of the sealing member from the outer diameter side of the housing. Direct laser beam irradiation), high-frequency pulse bonding, caulking, etc. can be employed.
[0018]
In the above configuration, the bearing sleeve can be formed of sintered metal.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
[0023]
FIG. 1 shows a configuration example of a spindle motor for information equipment incorporating a fluid dynamic bearing device 1 according to this embodiment. This spindle motor is used in a disk drive device such as an HDD, and includes a hydrodynamic bearing device 1 that rotatably supports a shaft member 2 in a non-contact manner, a disk hub 3 mounted on the shaft member 2, and a radial direction, for example. The motor stator 4 and the motor rotor 5 are provided to face each other through the gap. The stator 4 is attached to the outer periphery of the casing 6, and the rotor 5 is attached to the inner periphery of the disk hub 3. The housing 7 of the hydrodynamic bearing device 1 is mounted on the inner periphery of the casing 6. The disk hub 3 holds one or more disks D such as magnetic disks. When the stator 4 is energized, the rotor 5 is rotated by the exciting force between the stator 4 and the rotor 5, whereby the disk hub 3 and the shaft member 2 are rotated together.
[0024]
FIG. 2 shows the hydrodynamic bearing device 1. The hydrodynamic bearing device 1 is configured by constituting a housing 7, a bearing sleeve 8, a shaft member 2, and a seal member 10.
[0025]
Between the inner peripheral surface 8a of the bearing sleeve 8 and the outer peripheral surface 2a1 of the shaft portion 2a of the shaft member 2, the first radial bearing portion R1 and the second radial bearing portion R2 are provided apart from each other in the axial direction. A first thrust bearing portion S1 is provided between the lower end surface 8c of the bearing sleeve 8 and the upper end surface 2b1 of the flange portion 2b of the shaft member 2, and the inner bottom surface 7c1 and the flange portion 2b of the bottom portion 7c of the housing 7 are provided. A second thrust bearing portion S2 is provided between the lower end surface 2b2. For convenience of explanation, the description will proceed with the opening 7a side of the housing 7 as the upper side and the bottom 7c side as the lower side.
[0026]
As shown in FIG. 4A, the housing 7 is formed in a cup shape by a MIM method from, for example, metal powder such as magnesium, and integrally includes a cylindrical side portion 7b and a bottom portion 7c. The upper end of the side portion 7b is an opening 7a. Further, for example, a herringbone-shaped dynamic pressure groove 7c2 as shown in FIG. 4B is formed on the inner bottom surface 7c1 of the bottom portion 7c, which is the thrust bearing surface of the second thrust bearing portion S2. The dynamic pressure groove 7c2 is formed with the MIM method mold (transferred with the mold) together with the side portion 7b and the bottom portion 7c. In addition, you may employ | adopt spiral shape, a radiation groove shape, etc. as a shape of a dynamic pressure groove.
[0027]
The shaft member 2 is formed of a metal material such as stainless steel, for example, and includes a shaft portion 2a and a flange portion 2b provided integrally or separately at the lower end of the shaft portion 2a.
[0028]
The bearing sleeve 8 is formed, for example, in a cylindrical shape with a porous body made of sintered metal, particularly a sintered body made of sintered metal mainly composed of copper, and appropriately used for bonding, press-fitting, laser beam welding, high-frequency pulse bonding, and the like. By this means, the housing 7 is fixed at a predetermined position on the inner periphery. The upper end surface 8 b of the bearing sleeve 8 is in contact with the seal member 10.
[0029]
On the inner peripheral surface 8a of the bearing sleeve 8 formed of this sintered metal, two upper and lower regions serving as radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2 are provided apart in the axial direction. In these two regions, for example, herringbone-shaped dynamic pressure grooves 8a1 and 8a2 as shown in FIG. 3A are formed. In addition, as the shape of the dynamic pressure groove, a spiral shape, an axial groove shape, or the like may be adopted.
[0030]
In addition, a spiral-shaped dynamic pressure groove 8c1 as shown in FIG. 3B, for example, is formed on the lower end surface 8c of the bearing sleeve 8 serving as the thrust bearing surface of the first thrust bearing portion S1. In addition, as a shape of the dynamic pressure groove, a herringbone shape, a radiation groove shape, or the like may be adopted.
[0031]
The shaft portion 2 a of the shaft member 2 is inserted into the inner peripheral surface 8 a of the bearing sleeve 8, and the flange portion 2 b is accommodated in a space portion between the lower end surface 8 c of the bearing sleeve 8 and the inner bottom surface 7 c 1 of the housing 7.
[0032]
The seal member 10 is fixed to the opening 7a of the housing 7 by an appropriate means such as adhesion, press-fitting, laser beam welding, and high-frequency pulse bonding, and the inner peripheral surface 10a thereof has a predetermined seal with the outer peripheral surface 2a1 of the shaft portion 2a. Opposing through space. Then, lubricating oil is supplied to the internal space of the housing 7 that is sealed with the seal member 10.
[0033]
When the shaft member 2 rotates, the regions (two upper and lower regions) of the inner peripheral surface 8a of the bearing sleeve 8 are opposed to the outer peripheral surface 2a1 of the shaft portion 2a via the radial bearing gap. Further, the region serving as the thrust bearing surface of the lower end surface 8c of the bearing sleeve 8 faces the upper end surface 2b1 of the flange portion 2b via the thrust bearing gap, and the region serving as the thrust bearing surface of the inner bottom surface 7c1 of the housing 7 is the flange. It faces the lower end surface 2b2 of the portion 2b via a thrust bearing gap. As the shaft member 2 rotates, the dynamic pressure of the lubricating oil is generated in the radial bearing gap, and the shaft portion 2a of the shaft member 2 is rotated in the radial direction by the lubricating oil film formed in the radial bearing gap. It is supported non-contact freely. Thus, the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft member 2 in a non-contact manner so as to be rotatable in the radial direction are configured. At the same time, the dynamic pressure of the lubricating oil is generated in the thrust bearing gap, and the flange portion 2b of the shaft member 2 is rotatably supported in both thrust directions by the oil film of the lubricating oil formed in the thrust bearing gap. . Thereby, the first thrust bearing portion S1 and the second thrust bearing portion S2 that support the shaft member 2 in a non-contact manner so as to be rotatable in the thrust direction are configured.
[0034]
The hydrodynamic bearing device 1 of this embodiment is assembled in a manner as shown in FIGS.
[0035]
First, as shown in FIG. 5, the bearing sleeve 8 is mounted on the shaft member 2 and inserted into the inner periphery of the housing 7. The bearing sleeve 8 may be press-fitted into the inner periphery of the housing 7.
[0036]
Next, as shown in FIG. 6, the bearing sleeve 8 is pushed downward together with the shaft member 2, and the lower end surface 2b2 of the flange portion 2b is brought into contact with the inner bottom surface 7c1 of the housing 7. At the same time, the bearing sleeve 8 The lower end surface 8c is brought into contact with the upper end surface 2b1 of the flange portion 2b. This state is a state in which the thrust bearing gap is zero (the thrust bearing gap between the first thrust bearing portion S1 and the second thrust bearing portion S2 is zero). The shaft member 2 is first inserted into the inner periphery of the housing 7, and then the bearing sleeve 8 is mounted on the shaft member 2 and inserted (or press-fitted) into the inner periphery of the housing 7, and the state shown in FIG. May be achieved.
[0037]
Next, as shown in FIG. 7, the seal member 10 is inserted (or press-fitted) into the opening 7 a of the housing 7 and brought into contact with the upper end surface 8 b of the bearing sleeve 8.
[0038]
Next, as shown in FIG. 8, the shaft member 2 together with the bearing sleeve 8 and the seal member 10, the thrust bearing gap (size is δ1) of the first thrust bearing portion S 1 and the second thrust bearing portion. The shaft is moved relative to the housing 7 in the axial direction (upward in the figure) by a dimension δ (δ = δ1 + δ2) corresponding to the total amount of the thrust bearing gap (size is δ2) in S2. When the bearing sleeve 8 and the seal member 10 are fixed to the housing 7 at that position, a predetermined thrust bearing gap δ (δ = δ1 + δ2) is formed. The seal member 10 may be inserted (or press-fitted) into the opening 7a of the housing 7 after forming a predetermined thrust bearing gap δ (δ = δ1 + δ2).
[0039]
According to the above method, the components of the hydrodynamic bearing device 1 are actually combined to temporarily realize a state where the thrust bearing clearance is zero, and from this state, the housing 7 and the bearing sleeve 8 are relatively moved in the axial direction by a predetermined amount. Since the thrust bearing gap is formed by moving, the surface accuracy of the thrust surface (8c, 7c1, 2b1, 2b2), the shaft of the flange portion 2b can be managed only by managing the axial relative movement amount δ (δ = δ1 + δ2). The thrust bearing gap can be formed with high accuracy without being affected by the dimensional accuracy.
[0040]
【The invention's effect】
According to the present invention , the thrust bearing gap can be accurately and easily set without being affected by the component accuracy. Thereby, the processing cost and assembly cost of components can be reduced .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a spindle motor having a hydrodynamic bearing device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a fluid dynamic bearing device according to an embodiment of the present invention.
3 is a cross-sectional view of the bearing sleeve {FIG. 3 (a)} and a view of the lower end face {FIG. 3 (b)}.
4 is a cross-sectional view {FIG. 4 (a)} of a housing and a plan view {FIG. 4 (b)} of an inner bottom surface.
5 is a cross-sectional view showing an assembly process of the fluid dynamic bearing device shown in FIG. 2;
6 is a cross-sectional view showing an assembly process of the hydrodynamic bearing device shown in FIG. 2;
7 is a cross-sectional view showing an assembly process of the hydrodynamic bearing device shown in FIG. 2;
8 is a cross-sectional view showing an assembly process of the hydrodynamic bearing device shown in FIG. 2;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing apparatus 2 Shaft member 2a Shaft part 2b Flange part 2b1 Upper end surface 2b2 Lower end surface 7 Housing 7b Side portion 7c Bottom portion 7c1 Inner bottom surface 8 Bearing sleeve 8a Inner peripheral surface 8b Upper end surface 8c Lower end surface 10 Seal member R1 1st 1 radial bearing portion R2 second radial bearing portion S1 first thrust bearing portion S2 second thrust bearing portion

Claims (1)

側部および底部を有するコップ状のハウジングと、該ハウジングの内周に固定された軸受スリーブと、軸部およびフランジ部を有する軸部材と、前記軸受スリーブの内周面と前記軸部の外周面との間に設けられ、ラジアル軸受隙間に生じる潤滑油の動圧作用で前記軸部をラジアル方向に非接触支持するラジアル軸受部と、前記軸受スリーブの一端面とこれに対向する前記フランジ部の一端面との間に設けられ、スラスト軸受隙間に生じる潤滑油の動圧作用で前記フランジ部をスラスト方向に非接触支持する第１スラスト軸受部と、前記ハウジングの底部の内底面とこれに対向する前記フランジ部の他端面との間に設けられ、スラスト軸受隙間に生じる潤滑油の動圧作用で前記フランジ部をスラスト方向に非接触支持する第２スラスト軸受部とを備えた動圧軸受装置、の製造方法であって、
前記ハウジングの内底面に前記フランジ部の他端面を当接させると共に、前記フランジ部の一端面に前記軸受スリーブの一端面を当接させ、
前記フランジ部の一端面に前記軸受スリーブの一端面を当接させた状態で、前記軸受スリーブを、前記フランジ部と伴に、前記第１スラスト軸受部及び第２スラスト軸受部のスラスト軸受隙間の合計量に相当する寸法だけ、前記ハウジングに対して軸方向に相対移動させて、前記第１スラスト軸受部及び第２スラスト軸受部のスラスト軸受隙間を所定寸法に形成することを特徴とする動圧軸受装置の製造方法。A cup-shaped housing having side portions and a bottom portion, a bearing sleeve fixed to the inner periphery of the housing, a shaft member having a shaft portion and a flange portion, an inner peripheral surface of the bearing sleeve, and an outer peripheral surface of the shaft portion A radial bearing portion that supports the shaft portion in a non-contact manner in the radial direction by the dynamic pressure action of lubricating oil generated in a radial bearing gap, and one end surface of the bearing sleeve and the flange portion facing the radial bearing portion. A first thrust bearing portion provided between the first end surface and supporting the flange portion in a thrust non-contact manner by a dynamic pressure action of lubricating oil generated in a thrust bearing gap, and an inner bottom surface of the bottom portion of the housing and opposite thereto A second thrust bearing portion provided between the other end surface of the flange portion and supporting the flange portion in the thrust direction in a non-contact manner by a dynamic pressure action of lubricating oil generated in a thrust bearing gap. Dynamic bearing device having a method of manufacturing,
While contacting the other end surface of the flange portion to the inner bottom surface of the housing, contact one end surface of the bearing sleeve to one end surface of the flange portion,
In a state where one end surface of the bearing sleeve is in contact with one end surface of the flange portion, the bearing sleeve, together with the flange portion, has a thrust bearing gap between the first thrust bearing portion and the second thrust bearing portion. The dynamic pressure is characterized in that a thrust bearing gap between the first thrust bearing portion and the second thrust bearing portion is formed in a predetermined dimension by moving relative to the housing in the axial direction by a dimension corresponding to the total amount. Manufacturing method of bearing device.
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JP2005321089A (en) * 2004-04-09 2005-11-17 Ntn Corp Dynamic pressure bearing device
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