JP4340855B2 - Manufacturing method of dynamic pressure generating groove - Google Patents

Manufacturing method of dynamic pressure generating groove Download PDF

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JP4340855B2
JP4340855B2 JP2003116659A JP2003116659A JP4340855B2 JP 4340855 B2 JP4340855 B2 JP 4340855B2 JP 2003116659 A JP2003116659 A JP 2003116659A JP 2003116659 A JP2003116659 A JP 2003116659A JP 4340855 B2 JP4340855 B2 JP 4340855B2
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flange portion
dynamic pressure
shaft member
pressure generating
generating groove
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JP2004324684A (en
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康人 友近
武則 小村
高橋　　毅
健治 荻本
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JTEKT Corp
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JTEKT Corp
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Description

【０００１】
【発明の属する技術分野】
本発明は、軸にフランジ部を一体的に形成した軸部材と、これら軸部とフランジ部との間に僅かな隙間を設けたスリーブと、より成る動圧軸受において、前記フランジ表面に塑性加工により動圧発生用溝を形成する際の動圧発生用溝の製造方法、特に、引き抜き材を用いた軸部材のフランジ部とスリーブアキシャル面との間の隙間を殆ど均一とすることのできる動圧発生用溝の製造方法に関する。
【０００２】
【従来の技術】
動圧軸受として使用される軸部とフランジ部とを一体形成した軸部材は、旋削加工した後、フランジ部表面に形成する動圧発生用溝をプレス等により塑性加工して形成する場合がある。例えば、スピンドルモータには、動圧軸受が使用されることがあるが、この場合、回転軸に形成する円盤状軸受部材の表面の動圧軸受は、プレス加工によって製作される（特許文献１）。また、プレス加工等の塑性変形で動圧発生用溝を加工するとき、フランジ部の内側周囲を外側より一段低く形成し、外側周囲に動圧発生用溝を形成して加工時内側周囲が盛り上がるのを防止する製造方法も提案されている（特許文献２）。
【０００３】
【特許文献１】
特開平６−３３８１２５
【特許文献２】
特開平８−２１０３４５
【０００４】
【発明が解決しようとする課題】
プレス加工等の塑性加工で動圧発生用溝を形成する加工方法は、銅合金等の軟質材に対しては有効であるが、ステンレス鋼等のような硬質材でフランジ部の上下面に同一形状を安定的に形成するのは困難である。特に、冷間引き抜き加工材に塑性加工を施して安定的に動圧発生用溝を形成するのは難しい。
即ち、図８に示すように、冷間引き抜き加工材（以下、単に引き抜き材とする）から取り出した軸部２とフランジ部３とより成る軸部材１のフランジ部３の表面３ａ，３ｂにプレス加工等の塑性加工を施して動圧発生用溝を形成しても、これら軸部材１とスリーブとで形成された動圧軸受に適切な動圧が得られなくなるという現象があった。その原因は、引き抜き材に残留応力が存在しているため、旋削加工後に設計どおりプレス加工（塑性加工）しても（図９）、動圧発生溝４を形成した後フランジ部３が変形し（図１０参照、この逆方向の変形もあり得る）、スリーブ６との間の隙間５が設計どおりの正確な状態でなくなる（図１１参照）ことが大きな原因であると考えられる。尚、残留応力が存在する場合、これを除去するため焼鈍による方法も考えられる。しかし、焼鈍によると、材料が柔らかくなりすぎてプレス加工のような塑性加工による動圧発生用溝の形成は不可能である。また、スリーブ内周面やスラスト板等に動圧発生用溝を加工するのは煩雑でコストがかかり、安定的に同一の溝を形成するのは難しい。
【０００５】
この発明は、上記する課題に対処するためになされたものであり、引き抜き材を使用し内部に残留応力が存在し、動圧発生用溝を形成するための塑性加工後でも軸部とフランジ部とを一体とした軸部材とスリーブ内周面との間の隙間が意図したとおりの状態となる動圧軸受を得ることのできる動圧発生用溝の製造方法を提供することを目的としている。
【０００６】
【課題を解決するための手段】
即ち、この発明は上記する課題を提供するために、請求項１に記載の発明は、軸部とフランジ部とを形成した軸部材と、これら軸部とフランジ部との間に隙間を設けて該軸部材を嵌め入れたスリーブと、で構成される動圧軸受の前記フランジ部の表面に動圧発生用溝を塑性加工により形成する動圧発生用溝の製造方法において、
引き抜き方向の判明している引き抜き材から旋削加工により前記軸部材を形成するに際し、先ず寸法通りの軸部材を引き抜き材の引き抜き方向に沿って軸部を平行にして、軸部やフランジ部を切削加工して取り出し、
前記フランジ部の表面に動圧発生用溝を形成して該フランジ部の軸部の軸方向に直角な方向に対する傾斜角度、或いは、該フランジ部における中心側端部と外周端部との軸方向の位置の差を測定し、次にこの測定値をフィードバックして引き抜き材から軸部材を取り出し、フランジ部に塑性加工を施すことを特徴とするものである。
【０００７】
また、請求項２に記載の発明は、前記フランジ部は、内径部から外径部にかけて肉厚が薄くなるように形成したものであることを特徴とするものである。
【０００８】
また、請求項３に記載の発明は、前記フランジ部は、内径部から外径部にかけて肉厚が厚くなるように形成したものであることを特徴とするものである。
【０００９】
【発明の実施の形態】
以下、本発明の具体的な実施の形態について図面を参照して説明する。
図１は、本発明の第１の実施の形態の動圧発生用溝（以下、動圧溝とする）の製造方法を実施するに際して軸部材を取り出す前の引き抜き材を示す。この場合、引き抜き材Ｗは、先を細くした穴をもつダイス（工具）を通して素材を引き抜き、その断面積を減少させて製作したものである。この実施の形態では該引き抜き材Ｗを旋削加工を施して、Ｔ字形の軸部材１を取り出す。この軸部材１は、軸部２とフランジ部３とよりなるが、該フランジ部３の両面に、ヘリングボーン形やＶ字形或いは一部螺旋形の動圧溝をプレス加工（塑性加工）により形成する。
【００１０】
前記軸部材１のフランジ部３に動圧溝を形成するに際しては、先ず、図１に示すように、引き抜き材Ｗの表面に、目安として多数の細かい横線Ｘ，Ｘ，・・・と、縦線Ｙ，Ｙ，・・・を入れておき、これらの横線Ｘ，Ｘ，・・や縦線Ｙ，Ｙ，・・に沿って平行に軸部２やフランジ部３を旋削加工して図８に示したのと同様の軸部材１を形成する。これらのＸ，・・、Ｙ，・・は、後述するように、一旦、旋削加工して軸部材１を取り出しプレス加工（塑性加工）した後、図１０に示すように、のフランジ部の傾斜角度α或いは、軸２に対して直角方向と外周端部における高さの差ｄ（フランジ部３における下側面３ｂの中心側端部３ｃと外周端部３ｄとの軸方向の位置の差）を測定し、その数値をフィードバックして改めて旋削加工後プレス加工して正確な軸部材１を取り出すための目安とする。
【００１１】
次に、フランジ部３の両面に図９に示すように、プレス加工により動圧溝４，，４を形成した状態の軸部材１を製作する。この場合、前記軸部材１は、元の材料の引き抜き材Ｗ内に残留応力が生じているため、当初の図８に示す設計図通りの寸法とはならず、図１０に示すように、若干フランジ部３はある程度の角度（α）傾斜した状態となる。従って、予め動圧溝を形成する場合、プレス加工してこのようにフランジ部３がα傾斜することが判っていれば、この傾斜角度αをフィードバックして、図２に示すように、図１においてＴ字形の軸部材１を取り出すとき、逆方向にこの角度（α）分傾斜した状態で旋削加工してプレス加工すれば、加工後のフランジ部３は、図３（Ａ）に示すように、正確な状態の軸部材１とすることができる。従って、図３（Ｂ）に示すように、その表面に動圧溝４を形成したフランジ部３とスリーブ６との間の隙間５は、適正な隙間となる。
【００１２】
上記するように、フランジ部３の傾斜角度αは、通常、微小な角度であり、正確な角度が測定できない場合は、軸２に対して直角方向と外周端部における高さの差ｄ（フランジ部３における下側面３ｂの中心側端部３ｃと外周端部３ｄとの軸方向の位置の差）を測定し、その数値をフィードバックしても良い。
【００１３】
尚、正確な軸部材１を形成するにあたっては、元の引き抜き材Ｗの素材の種類（例えば、ステンレス鋼、炭素鋼等）、引き抜き方向及び素材メーカー等が明確になっていなければならない。蓋し、そのような素材情報が明確でないと、引き抜き後の内部の残留応力の状態（大きさや方向）旋削加工時の旋削方向が判らず、その都度、プレス加工後の変形状態を調査して旋削加工とプレス加工を繰り返さなければ正確な加工が出来ないからである。
【００１４】
次に、軸部材１に形成されるフランジ部３の上下面に傾斜を設ける場合について説明する。先ず、引き抜き材Ｗから旋削加工により軸部材１を取り出して、フランジ部３の内径部から外径部（外周端部）にかけて肉厚が薄くなるように形成する場合（第２の実施の形態）について説明する。
引き抜き材Ｗから旋削加工により軸部材１を取り出して、フランジ部３の内径部から外径部（外周端部）にかけて肉厚が薄くなるように形成する場合、前記軸部材１の上側面３ａと下側面３ｂの肉厚部と上下の外周端部の上下の軸２に対して直角方向に対するそれぞれの高さの差を、図４（Ａ）に示すように、ｈ，ｈとしてプレス加工すると、該軸部材１の内部には残留応力が生じているため、当初の設計予定通りの（ｈ，ｈ）とはならず、図４（Ｂ）に示すように、ｈ1 、ｈ2 で且つｈ1 ＜ｈ2 となる。即ち、上側面３ａと下側面３ｂとは内部の残留応力の分布状態が異なっているので同一とはならない。
【００１５】
次に、図５（Ａ）に示すように、引き抜き材Ｗから旋削加工により軸部材１を取り出すとき、上側面３ａと下側面３ｂの肉厚部と外周端部のそれぞれのフランジ部３の上下の軸２に対して直角方向に対する高さの差を、ｈ1 、ｈ2 とし且つｈ1 ＞ｈ2 となるようにする。そして、この状態でプレス加工により動圧溝４，４を形成すると、図５（Ｂ）に示すように、動圧溝４，４を形成した後のフランジ部３の上側面３ａと下側面３ｂの肉厚部と外周端部のそれぞれの上下の軸２に対する直角方向に対する高さの差は、ほぼ同じｈ、ｈとなる。
【００１６】
上記するように、プレス加工のような塑性加工をしてみてフランジ部３の上下面３ａ、３ｂの端部の軸２に対して直角方向に対する高さの差がｈ1 、ｈ2 で且つｈ1 ＜ｈ2 となることが判れば、図１において、Ｔ字形の軸部材１を取り出すとき、これらの高さの差（ｈ1 ，ｈ2 ）をフィードバックして、図５（Ａ）に示すよう逆方向に、予め高さの差を設けて旋削加工する。即ち、軸部材１を旋削加工して取り出すとき、上側面３ａと下側面３ｂの肉厚部と外周端部のそれぞれの高さをｈ1 ，ｈ2 とし且つｈ1 ＞ｈ2 とすれば、図５（Ｂ）に示すように、プレス加工後のフランジ部３の上下面３ａ、３ｂのの肉厚部と外周端部のそれぞれの軸２に対して直角方向に対する高さの差がほぼｈ、ｈとなる軸部材１を得ることができる。
【００１７】
次に、軸側材１に形成されるフランジ部３に傾斜を設ける場合であって、フランジ部３の上下面３ａ，３ｂは、内径部から外径部（外周端部）にかけて肉厚が厚くなるように形成する場合（第３の実施の形態）について説明する。
引き抜き材Ｗから旋削加工により軸部材１を取り出して、フランジ部３の内径部から外径部（外周端部）にかけて肉厚が厚くなるように形成する場合、前記軸部材１の上側面３ａと下側面３ｂの肉厚部と外周端部のそれぞれの高さを差を図６（Ａ）に示すように、ｊ，ｊとしてプレス加工すると、該軸部材１の内部には残留応力が生じているため、この場合も当初の設計予定通りの（ｊ，ｊ）とはならず、図６（Ｂ）に示すように、若干フランジ部３の上下の軸２に対して直角方向に対する高さの差は、ｊ1 ，ｊ2 で且つｊ1 ＜ｊ2 となる。即ち、上側面と下側面とは残留応力の分布状態が異なっているので同一とはならない。
【００１８】
次に、引き抜き材Ｗから旋削加工により軸部材１を取り出すとき、上側面３ａと下側面３ｂの肉厚部と外周端部のそれぞれのフランジ部３の上下の軸２に対して直角方向に対する高さの差を、ｊ1 、ｊ2 とし且つｊ1 ＞ｊ2 となるようにする。そして、この状態でプレス加工により動圧溝４，４を形成すると、図７（Ｂ）に示すように、動圧溝４，４を形成した後のフランジ部３の上側面３ａと下側面３ｂの肉厚部と外周端部のそれぞれの上下の軸２に対する直角方向に対する高さの差は、ほぼ同じｊ、ｊとなる。
【００１９】
従って、この場合も塑性加工してみてフランジ部３の上下面３ａ、３ｂの端部の軸２に対して直角方向に対する高さの差がｊ1 ，ｊ2 となることが判れば、図１において、Ｔ字形の軸部材１を取り出すとき、これらの高さの差（ｊ1 ，ｊ2 ）をフィードバックして、図７（Ａ）に示すよう逆方向に、予め高さの差を設ければ良い。即ち、軸部材１を旋削加工して取り出すとき、上側面３ａと下側面３ｂの肉厚部と外周端部のそれぞれの高さがｊ1 ，ｊ2 て且つｊ1 ＞ｊ2 とすれば、図７（Ｂ）に示すように、プレス加工後のフランジ部３の上下面３ａ、３ｂのの肉厚部と外周端部のそれぞれの軸２に対して直角方向に対する高さの差がほぼｊ、ｊとなる軸部材１を得ることができる。
【００２０】
本発明の実施の形態においては、軸部材１がＴ字形の場合について説明したが、勿論、軸部２の途中の周囲にフランジ部３を形成した軸部材であっても良い。
また、フランジ部３の上面３ａのみ或いは下面３ｂのみに傾斜を設けたり、動圧発生用溝４を形成する場合にも適用することができる。更に、Ｔ字形の軸部材１では、図に示すように、Ｔ字形の頂点中央部には、凹部３ｃを形成してあるが、この頂点中央部が面一の水平の平面状態であっても良い。
【００２１】
表１は、本発明の動圧発生用溝の製造方法において、特に、第３の実施の形態において、実際に引き抜き材Ｗ（ステンレス材）から旋削加工により軸部２とフランジ部３とより成る軸部材１を取り出し、軸部材１の上側面３ａと下側面３ｂの肉厚部と外周端部のそれぞれの高さを差を図６（Ａ）に示すように、プレス加工前にｊ1 ，ｊ2 の値をそれぞれ３回製作し、プレス加工後の値を測定した結果を示す表である。
【表１】

Figure 0004340855
この表１に示すように、引き抜き材から旋削加工により取り出した軸部材１は、その残留応力の影響を考慮して、フィードバックしてフランジ部３を形成すれば、軸部２とフランジ部３とが ほぼ正確な直角度を有する軸部材１とすることができることが判明した。
【００２２】
【発明の効果】
以上、詳述したように、本発明の動圧発生用溝の製造方法によれば、ステンレス鋼や炭素鋼等の引き抜き材を使用する場合、内部に残留応力が存在してプレス加工のような塑性加工により動圧発生用溝を加工した後の軸とフランジ部とを一体とした軸部材とスリーブ内周面との間の隙間が意図したとおりの正確な動圧軸受を得ることができる。また、本発明の製造方法によれば、スリーブやスラスト板等に動圧発生用溝の煩雑な加工が不要となる。更に、軸に設けたフランジ部の上下両面に同時に同じ動圧発生用溝を加工することができるので工程数を低減することができる。また、軸に設けたフランジ部の上下両面に動圧発生用溝を加工する場合、同じ形状の動圧発生用溝が安定的に得られるので、組立完了後の精度が良くなり、不良品発生率も低下しその分製造コストを低減することができる。
【図面の簡単な説明】
【図１】本発明の動圧発生用溝の製造方法を実施するに際して軸部材を取り出す前の冷間引き抜き加工材を示す図である。
【図２】Ｔ字形の軸部材を取り出すとき、予めプレス加工した結果を考慮して逆方向に生じた歪の角度分傾斜した状態で旋削加工した軸部材を示す図である。
【図３】図３（Ａ）は、予めプレス加工した結果を考慮して逆方向に生じた歪の角度分傾斜した状態で旋削加工した軸部材をプレス加工した状態の軸部材を示す図であり、図３（Ｂ）は、この軸部材をスリーブに嵌め入れた状態の断面図である。
【図４】引き抜き材から取り出した軸部材のフランジ部の内径部から外径部（外周端部）にかけて肉厚が薄くなるように形成する場合であって、図４（Ａ）は、プレス加工前の状態を示す一部断面図であり、図４（Ｂ）は、付パス加工後の状態を示す一部断面図である。
【図５】引き抜き材から取り出した軸部材のフランジ部の内径部から外径部（外周端部）にかけて肉厚が薄くなるように形成する場合であって、図５（Ａ）は、プレス加工前の状態を示す一部断面図であり、図５（Ｂ）は、プレス加工後の状態を示す一部断面図である。
【図６】引き抜き材から取り出した軸部材のフランジ部の内径部から外径部（外周端部）にかけて肉厚が厚くなるように形成する場合であって、図６（Ａ）は、プレス加工前の状態を示す一部断面図であり、図６（Ｂ）は、付パス加工後の状態を示す一部断面図である。
【図７】引き抜き材から取り出した軸部材のフランジ部の内径部から外径部（外周端部）にかけて肉厚が厚くなるように形成する場合であって、図７（Ａ）は、プレス加工前の状態を示す一部断面図であり、図７（Ｂ）は、プレス加工後の状態を示す一部断面図である。
【図８】冷間引き抜き加工材から旋削加工により取り出した軸部とフランジ部からなるＴ字形の軸部材を示す図である。
【図９】冷間引き抜き加工材から旋削加工により取り出した軸部材のフランジ部に動圧発生用溝を形成するためのプレス加工する状態を示す図である。
【図１０】冷間引き抜き加工材から旋削加工により取り出した軸部材のフランジ部に動圧発生用溝を形成するためプレス加工した状態を示す図である。
【図１１】冷間引き抜き加工材から旋削加工により取り出した軸部材のフランジ部に動圧発生用溝を形成した後この軸部材をスリーブに嵌め入れた状態の動圧軸受の断面図を示す図である。
【符号の説明】
１ 軸部材
２ 軸部
３ フランジ部
４ 動圧発生用溝[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrodynamic bearing comprising a shaft member in which a flange portion is integrally formed on a shaft, and a sleeve having a slight gap between the shaft portion and the flange portion, and plastic processing is performed on the flange surface. The method for manufacturing the dynamic pressure generating groove when forming the dynamic pressure generating groove by the above-mentioned method, in particular, the movement that can make the gap between the flange portion of the shaft member using the drawing material and the sleeve axial surface almost uniform. The present invention relates to a method for manufacturing a pressure generating groove.
[0002]
[Prior art]
A shaft member integrally formed with a shaft portion and a flange portion used as a hydrodynamic bearing may be formed by turning a dynamic pressure generating groove formed on the surface of the flange portion by plastic working after turning. . For example, a dynamic pressure bearing may be used for the spindle motor. In this case, the dynamic pressure bearing on the surface of the disk-shaped bearing member formed on the rotating shaft is manufactured by press working (Patent Document 1). . Also, when machining the dynamic pressure generating groove by plastic deformation such as press working, the inner periphery of the flange is formed one step lower than the outer side, and the dynamic pressure generating groove is formed around the outer periphery, and the inner periphery rises during processing. A manufacturing method for preventing this has also been proposed (Patent Document 2).
[0003]
[Patent Document 1]
JP-A-6-338125
[Patent Document 2]
JP-A-8-210345
[0004]
[Problems to be solved by the invention]
Forming grooves for generating dynamic pressure by plastic working such as press working is effective for soft materials such as copper alloy, but it is the same on the upper and lower surfaces of the flange part with a hard material such as stainless steel. It is difficult to form the shape stably. In particular, it is difficult to form a dynamic pressure generating groove stably by plastic working the cold drawn material.
That is, as shown in FIG. 8, press is applied to the surfaces 3a and 3b of the flange portion 3 of the shaft member 1 composed of the shaft portion 2 and the flange portion 3 taken out from the cold drawn material (hereinafter simply referred to as a drawn material). Even if plastic working such as machining is performed to form the dynamic pressure generating groove, there is a phenomenon that an appropriate dynamic pressure cannot be obtained in the dynamic pressure bearing formed by the shaft member 1 and the sleeve. The reason for this is that residual stress is present in the drawn material. Therefore, even after press working (plastic working) as designed after turning (FIG. 9), the flange 3 is deformed after the formation of the dynamic pressure generating groove 4. (Refer to FIG. 10, there may be a deformation in the opposite direction.) The gap 5 between the sleeve 6 and the sleeve 6 is not as accurate as designed (see FIG. 11). In addition, in order to remove this when residual stress exists, the method by annealing is also considered. However, by annealing, the material becomes too soft, and it is impossible to form a dynamic pressure generating groove by plastic working such as press working. Further, it is complicated and expensive to process the dynamic pressure generating groove on the sleeve inner peripheral surface, the thrust plate, or the like, and it is difficult to stably form the same groove.
[0005]
The present invention has been made in order to cope with the above-described problems, and a shaft portion and a flange portion are used even after plastic working for forming a dynamic pressure generating groove by using a drawn material and having a residual stress inside. It is an object of the present invention to provide a method of manufacturing a dynamic pressure generating groove that can obtain a dynamic pressure bearing in which a gap between a shaft member and a sleeve inner peripheral surface is in an intended state.
[0006]
[Means for Solving the Problems]
In other words, in order to provide the above-described problem, the invention according to the first aspect provides a shaft member in which a shaft portion and a flange portion are formed, and a gap is provided between the shaft portion and the flange portion. In the manufacturing method of the dynamic pressure generating groove, the dynamic pressure generating groove is formed by plastic working on the surface of the flange portion of the dynamic pressure bearing constituted by the sleeve fitted with the shaft member,
When the shaft member is formed by turning from a drawn material whose drawing direction is known , first the shaft member according to the dimension is made parallel to the drawing direction of the drawn material, and the shaft portion and the flange portion are cut. Processed and taken out,
A groove for generating dynamic pressure is formed on the surface of the flange portion , and an inclination angle with respect to a direction perpendicular to the axial direction of the shaft portion of the flange portion, or the axial direction between the center side end portion and the outer peripheral end portion of the flange portion The difference between the positions is measured, the measured value is fed back, the shaft member is taken out from the drawn material, and the flange portion is plastically processed.
[0007]
The invention according to claim 2 is characterized in that the flange portion is formed so as to become thinner from the inner diameter portion to the outer diameter portion.
[0008]
The invention according to claim 3 is characterized in that the flange portion is formed so as to increase in thickness from an inner diameter portion to an outer diameter portion.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a drawing material before a shaft member is taken out when a method for producing a dynamic pressure generating groove (hereinafter referred to as a dynamic pressure groove) according to a first embodiment of the present invention is carried out. In this case, the drawing material W is manufactured by drawing a material through a die (tool) having a tapered hole and reducing its cross-sectional area. In this embodiment, the drawing material W is turned to take out the T-shaped shaft member 1. The shaft member 1 is composed of a shaft portion 2 and a flange portion 3, and herringbone, V-shaped, or partially helical dynamic pressure grooves are formed on both surfaces of the flange portion 3 by press working (plastic working). To do.
[0010]
When forming the dynamic pressure grooves in the flange portion 3 of the shaft member 1, first, as shown in FIG. 1, a large number of fine horizontal lines X, X,. Lines Y, Y,... Are inserted, and the shaft portion 2 and the flange portion 3 are turned in parallel along the horizontal lines X, X,... And the vertical lines Y, Y,. A shaft member 1 similar to that shown in FIG. These X,..., Y,... Are inclined as shown in FIG. 10 after turning the shaft member 1 and press-working (plastic working). The angle α or the height difference d between the direction perpendicular to the shaft 2 and the outer peripheral end (the difference in axial position between the center side end 3c of the lower surface 3b and the outer peripheral end 3d of the flange 3). The measured value is fed back and used as a standard for taking out the accurate shaft member 1 by pressing after turning again.
[0011]
Next, as shown in FIG. 9, the shaft member 1 in which the dynamic pressure grooves 4, 4 are formed on both surfaces of the flange portion 3 by pressing is manufactured. In this case, since the residual stress is generated in the drawing material W of the original material, the shaft member 1 does not have the dimensions according to the original design drawing shown in FIG. The flange part 3 will be in the state inclined to a certain angle ((alpha)). Therefore, when the dynamic pressure groove is formed in advance, if it is known that the flange portion 3 is inclined by α by pressing as described above, the inclination angle α is fed back, as shown in FIG. When the T-shaped shaft member 1 is taken out in FIG. 3A, the flange portion 3 after processing is processed as shown in FIG. The shaft member 1 can be in an accurate state. Therefore, as shown in FIG. 3B, the gap 5 between the flange portion 3 and the sleeve 6 having the dynamic pressure groove 4 formed on the surface thereof is an appropriate gap.
[0012]
As described above, the inclination angle α of the flange portion 3 is usually a minute angle, and when an accurate angle cannot be measured, the height difference d between the direction perpendicular to the shaft 2 and the outer peripheral end portion (flange) The difference in axial position between the center side end 3c and the outer peripheral end 3d of the lower surface 3b of the portion 3 may be measured, and the numerical value may be fed back.
[0013]
In forming the accurate shaft member 1, the material type (for example, stainless steel, carbon steel, etc.) of the original drawing material W, the drawing direction, the material manufacturer, etc. must be clear. If the material information is not clear, the state of residual stress after pulling (size and direction), the turning direction during turning cannot be determined, and in each case, the deformation state after press working should be investigated. This is because accurate machining cannot be performed unless turning and pressing are repeated.
[0014]
Next, the case where an inclination is provided in the upper and lower surfaces of the flange part 3 formed in the shaft member 1 is demonstrated. First, when the shaft member 1 is taken out from the drawn material W by turning and formed so that the thickness decreases from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion 3 (second embodiment). Will be described.
When the shaft member 1 is taken out from the drawn material W by turning and formed so that the thickness decreases from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion 3, the upper surface 3 a of the shaft member 1 When the difference in height with respect to the direction perpendicular to the upper and lower shafts 2 of the thick portion of the lower side surface 3b and the upper and lower outer peripheral ends is pressed as h and h, as shown in FIG. Residual stress is generated inside the shaft member 1, so that it does not become (h, h) as originally planned, but h 1 , h 2 and h as shown in FIG. 1 a <h 2. That is, the upper side surface 3a and the lower side surface 3b are not the same because the distribution state of the internal residual stress is different.
[0015]
Next, as shown in FIG. 5 (A), when the shaft member 1 is taken out from the drawn material W by turning, the upper and lower sides of the flange portions 3 of the thick portions and the outer peripheral end portions of the upper side surface 3a and the lower side surface 3b. The height difference in the direction perpendicular to the axis 2 is set to h 1 and h 2 and h 1 > h 2 . When the dynamic pressure grooves 4 and 4 are formed by pressing in this state, as shown in FIG. 5B, the upper side surface 3a and the lower side surface 3b of the flange portion 3 after the formation of the dynamic pressure grooves 4 and 4 are formed. The difference in height with respect to the direction perpendicular to the upper and lower shafts 2 of the thick wall portion and the outer peripheral edge portion is substantially the same h.
[0016]
As described above, when plastic working such as press working is performed, the height difference in the direction perpendicular to the axis 2 at the ends of the upper and lower surfaces 3a, 3b of the flange portion 3 is h 1 , h 2 and h If it is found that 1 <h 2 , when the T-shaped shaft member 1 is taken out in FIG. 1, the height difference (h 1 , h 2 ) is fed back and shown in FIG. 5 (A). In the opposite direction, turning is performed in advance with a difference in height. That is, when the shaft member 1 is turned and taken out, if the heights of the thick part and the outer peripheral end part of the upper side surface 3a and the lower side surface 3b are h 1 and h 2 and h 1 > h 2 , As shown in FIG. 5 (B), the height difference in the direction perpendicular to the axis 2 of the thick part and the outer peripheral end part of the upper and lower surfaces 3a, 3b of the flange part 3 after the press work is almost h. , H can be obtained.
[0017]
Next, in the case where the flange portion 3 formed on the shaft side member 1 is inclined, the upper and lower surfaces 3a and 3b of the flange portion 3 are thick from the inner diameter portion to the outer diameter portion (outer peripheral end portion). A case of forming in such a manner (third embodiment) will be described.
When the shaft member 1 is taken out from the drawn material W by turning and formed so as to increase in thickness from the inner diameter portion to the outer diameter portion (outer peripheral end portion) of the flange portion 3, As shown in FIG. 6 (A), when the thickness of the lower surface 3b and the outer peripheral end are different from each other by pressing j and j, residual stress is generated inside the shaft member 1. Therefore, in this case as well, (j, j) as originally planned is not achieved, and as shown in FIG. The difference is j 1 , j 2 and j 1 <j 2 . That is, the upper side surface and the lower side surface are not the same because the residual stress distribution is different.
[0018]
Next, when the shaft member 1 is taken out from the drawn material W by turning, the height of the upper surface 3a and the lower surface 3b with respect to the upper and lower shafts 2 of the upper and lower shafts 2 of the flange portions 3 at the outer peripheral ends is high. The difference in height is j 1 , j 2 and j 1 > j 2 . When the dynamic pressure grooves 4 and 4 are formed by pressing in this state, as shown in FIG. 7B, the upper side surface 3a and the lower side surface 3b of the flange portion 3 after the formation of the dynamic pressure grooves 4 and 4 are formed. The difference in height with respect to the direction perpendicular to the upper and lower axes 2 of the thick wall portion and the outer peripheral edge portion is substantially the same j and j.
[0019]
Accordingly, in this case as well, if it is found that the difference in height with respect to the direction perpendicular to the shaft 2 at the ends of the upper and lower surfaces 3a and 3b of the flange portion 3 becomes j 1 and j 2 , FIG. When the T-shaped shaft member 1 is taken out, the height difference (j 1 , j 2 ) is fed back to provide a height difference in the reverse direction in advance as shown in FIG. It ’s fine. That is, when the shaft member 1 is turned and taken out, if the heights of the thick portion and the outer peripheral end of the upper side surface 3a and the lower side surface 3b are j 1 and j 2 and j 1 > j 2 , As shown in FIG. 7B, the difference in height in the direction perpendicular to the axis 2 of the thick part and the outer peripheral end part of the upper and lower surfaces 3a, 3b of the flange part 3 after the press work is substantially j. , J can be obtained.
[0020]
In the embodiment of the present invention, the case where the shaft member 1 is T-shaped has been described. Of course, a shaft member in which the flange portion 3 is formed around the shaft portion 2 may be used.
Further, the present invention can also be applied to a case where only the upper surface 3 a or only the lower surface 3 b of the flange portion 3 is inclined or the dynamic pressure generating groove 4 is formed. Further, in the T-shaped shaft member 1, as shown in the drawing, a concave portion 3 c is formed at the center of the vertex of the T-shape, but even if the center of the vertex is in a flat horizontal state. good.
[0021]
Table 1 shows the manufacturing method of the dynamic pressure generating groove according to the present invention, and in particular, in the third embodiment, the shaft portion 2 and the flange portion 3 are actually formed from the drawing material W (stainless steel) by turning. the shaft member 1 is taken out, the difference between the respective heights of the thick portion and the outer peripheral edge portion of the side surface 3a and the lower surface 3b on the shaft member 1, as shown in FIG. 6 (a), j 1 before pressing, j 2 values were produced 3 times respectively, a table showing the results of measuring the value after pressing.
[Table 1]
Figure 0004340855
As shown in Table 1, when the shaft member 1 taken out from the drawn material by turning is fed back to form the flange portion 3 in consideration of the effect of the residual stress, the shaft portion 2 and the flange portion 3 It has been found that the shaft member 1 having an almost accurate squareness can be obtained.
[0022]
【The invention's effect】
As described above in detail, according to the method for producing a dynamic pressure generating groove of the present invention, when a drawing material such as stainless steel or carbon steel is used, there is a residual stress inside, and the like It is possible to obtain an accurate hydrodynamic bearing as intended by the gap between the shaft member integrated with the shaft and the flange portion after processing the dynamic pressure generating groove by plastic working and the inner peripheral surface of the sleeve. Further, according to the manufacturing method of the present invention, complicated processing of the dynamic pressure generating groove on the sleeve, the thrust plate, or the like is not required. Furthermore, since the same dynamic pressure generating groove can be processed simultaneously on the upper and lower surfaces of the flange portion provided on the shaft, the number of steps can be reduced. Also, when dynamic pressure generating grooves are machined on both the upper and lower surfaces of the flange part provided on the shaft, the same shape of dynamic pressure generating grooves can be stably obtained, so the accuracy after assembly is completed and defective products are generated. The rate is also reduced, and the manufacturing cost can be reduced accordingly.
[Brief description of the drawings]
FIG. 1 is a view showing a cold drawn material before a shaft member is taken out when a method for producing a dynamic pressure generating groove according to the present invention is carried out.
FIG. 2 is a view showing a shaft member that is turned in a state where the T-shaped shaft member is tilted by an angle of distortion generated in the reverse direction in consideration of a result of pre-pressing when the T-shaped shaft member is taken out.
FIG. 3A is a diagram showing a shaft member in a state in which a shaft member that has been turned in a state inclined by an angle of strain generated in the reverse direction in consideration of the result of pre-pressing is pressed. FIG. 3B is a cross-sectional view of the shaft member fitted into the sleeve.
FIG. 4 shows a case where the thickness is reduced from the inner diameter portion to the outer diameter portion (outer end portion) of the flange portion of the shaft member taken out from the drawn material, and FIG. FIG. 4B is a partial cross-sectional view showing the state after the pass process with the attached pass.
FIG. 5 shows a case where the thickness is reduced from the inner diameter portion to the outer diameter portion (outer end portion) of the flange portion of the shaft member taken out from the drawn material, and FIG. FIG. 5B is a partial cross-sectional view showing a previous state, and FIG. 5B is a partial cross-sectional view showing a state after press working.
FIG. 6 shows a case where the thickness is increased from the inner diameter portion to the outer diameter portion (outer end portion) of the flange portion of the shaft member taken out from the drawn material, and FIG. FIG. 6B is a partial cross-sectional view showing the state after the pass process with the attached pass.
FIG. 7 shows a case where the thickness is increased from the inner diameter portion to the outer diameter portion (outer end portion) of the flange portion of the shaft member taken out from the drawn material, and FIG. FIG. 7B is a partial cross-sectional view showing a previous state, and FIG. 7B is a partial cross-sectional view showing a state after press working.
FIG. 8 is a view showing a T-shaped shaft member including a shaft portion and a flange portion taken out from a cold drawn material by turning.
FIG. 9 is a diagram showing a state in which press working is performed to form a dynamic pressure generating groove in the flange portion of the shaft member taken out from the cold drawn material by turning.
FIG. 10 is a view showing a state in which a dynamic pressure generating groove is formed in a flange portion of a shaft member taken out from a cold drawn material by turning.
FIG. 11 is a cross-sectional view of a hydrodynamic bearing in a state where a dynamic pressure generating groove is formed in a flange portion of a shaft member taken out from a cold drawn material by turning and the shaft member is fitted into a sleeve. It is.
[Explanation of symbols]
1 Shaft member 2 Shaft portion 3 Flange portion 4 Dynamic pressure generating groove

Claims (3)

軸部とフランジ部とを形成した軸部材と、これら軸部とフランジ部との間に隙間を設けて該軸部材を嵌め入れたスリーブと、で構成される動圧軸受の前記フランジ部の表面に動圧発生用溝を塑性加工により形成する動圧発生用溝の製造方法において、
引き抜き方向の判明している引き抜き材から旋削加工により前記軸部材を形成するに際し、先ず寸法通りの軸部材を引き抜き材の引き抜き方向に沿って軸部を平行にして、軸部やフランジ部を切削加工して取り出し、
前記フランジ部の表面に動圧発生用溝を形成して該フランジ部の軸部の軸方向に直角な方向に対する傾斜角度、或いは、該フランジ部における中心側端部と外周端部との軸方向の位置の差を測定し、次にこの測定値をフィードバックして引き抜き材から軸部材を取り出し、フランジ部に塑性加工を施すことを特徴とする動圧発生用溝の製造方法。The surface of the flange portion of the hydrodynamic bearing comprising: a shaft member having a shaft portion and a flange portion; and a sleeve in which a gap is provided between the shaft portion and the flange portion and the shaft member is fitted therein In the manufacturing method of the dynamic pressure generating groove, the dynamic pressure generating groove is formed by plastic working.
When the shaft member is formed by turning from a drawn material whose drawing direction is known , first the shaft member according to the dimension is made parallel to the drawing direction of the drawn material, and the shaft portion and the flange portion are cut. Processed and taken out,
A groove for generating dynamic pressure is formed on the surface of the flange portion , and an inclination angle with respect to a direction perpendicular to the axial direction of the shaft portion of the flange portion, or the axial direction between the center side end portion and the outer peripheral end portion of the flange portion A method for producing a dynamic pressure generating groove, characterized in that a difference in position is measured, then the measured value is fed back, a shaft member is taken out from the drawn material, and the flange portion is plastically processed. 前記フランジ部は、内径部から外径部にかけて肉厚が薄くなるように形成したものである請求項１に記載の動圧発生用溝の製造方法。  The method for producing a dynamic pressure generating groove according to claim 1, wherein the flange portion is formed so as to be thinned from an inner diameter portion to an outer diameter portion. 前記フランジ部は、内径部から外径部にかけて肉厚が厚くなるように形成したものである請求項１に記載の動圧発生用溝の製造方法。  The method for manufacturing a dynamic pressure generating groove according to claim 1, wherein the flange portion is formed so as to increase in thickness from an inner diameter portion to an outer diameter portion.
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