JP4431244B2 - Method for machining dynamic pressure generating groove in hydrodynamic bearing - Google Patents

Method for machining dynamic pressure generating groove in hydrodynamic bearing Download PDF

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Publication number
JP4431244B2
JP4431244B2 JP2000054682A JP2000054682A JP4431244B2 JP 4431244 B2 JP4431244 B2 JP 4431244B2 JP 2000054682 A JP2000054682 A JP 2000054682A JP 2000054682 A JP2000054682 A JP 2000054682A JP 4431244 B2 JP4431244 B2 JP 4431244B2
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Prior art keywords
dynamic pressure
pressure generating
generating groove
peripheral surface
end surface
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JP2001241433A (en
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政喜 田上
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Seibu Electric and Machinery Co Ltd
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Seibu Electric and Machinery Co Ltd
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【０００１】
【発明の属する技術分野】
この発明は，流体の動圧を利用して回転軸を軸支持する動圧軸受において，動圧軸受面に形成される動圧発生溝の加工方法に関する。
【０００２】
【従来の技術】
従来，ポリゴンミラー，磁気ディスク，光ディスク等の回転体を低摩擦で回転駆動するために，空気軸受等の動圧軸受が用いられている。このような動圧軸受の一例が，特開平８−１９６０５６号公報に開示されている。この公報に開示の動圧軸受は，固定軸の外周面にはヘリングボーン型の動圧発生用溝が軸方向に２ブロックに分割して形成されており，固定軸の外側に，ロータの円筒胴部が回転可能に装着されている。固定軸の外周面と，ロータの円筒胴部の内面との間の空気動圧が形成されてラジアル軸受が形成されている。固定軸の軸端部から空気供給孔が軸方向に延びており，空気供給孔は２ブロックの動圧発生用溝の中間部分送給され，動圧発生用溝のポンピング作用によって軸方向に上下に流動されて外部側に排出されている。
【０００３】
上記のような動圧軸受の軸受面に動圧発生用の溝を形成する加工方法としては，エッチング，プレス，ブラスト，レーザ，転造等の加工方法が採用されている。一般的に多く用いられている方法は，転造工具による加工方法である。また，アルミニウムや真鍮のような非鉄金属に溝加工する場合には，切削工具（ダイヤバイト等）を用いて切削加工により溝成形される場合もある。
【０００４】
既出の特開平８−１９６０５６号公報に開示されている動圧軸受の軸受面に動圧発生用の溝を形成する切削加工は，動圧面を構成す軸体及び軸嵌合体が，被切削性に優れた真鍮，アルミニウム若しくはその合金から形成され，かつ動圧面及び動圧発生溝の双方を切削加工により形成することにより，面倒な転造やエッチングによることなく，動圧面及び動圧発生溝の双方を加工精度を落とすことなく良好に形成可能となるとともに，同一の切削加工機で着脱なしで形成することを図っている。
【０００５】
しかしながら，いずれの方法も，製作コストや加工精度の面で満足のいくものはない。現在，主流である転造工具を使用した転造溝加工においては，可能な加工形状は円弧溝形状のみである。転造工具は，一度摩耗すると再製作しなければならず，工具１本当たりの単価も高価であり，ワーク１個当たりのランニングコストが高い。また，動圧発生溝の溝深さは，±１μｍの公差が要求され，転造工具では，一度摩耗すれば使用不可能となるという問題点がある。
【０００６】
【発明が解決しょうとする課題】
ところで，最近，ハードディスクドライブ（ＨＤＤ）用の流体軸受部品は，ステンレス製素材が主流になっている。アルミニウム又はその合金のような硬度が比較的低い素材に対して適用される溝加工方法を，ステンレスからなる高硬度の軸受部品の溝加工にそのまま適用することはできない。
【０００７】
更に，高硬度の素材を切削加工する方法として，ダイヤモンドを切削工具として用いることが考えられる。しかしながら，ステンレスを含む鉄系素材の切削にダイヤモンドを用いることは，一般切削の場合，ダイヤモンドの摩耗の進行が早く，使用に耐えるものでないとされるのが通説である。そこで，被切削材としてステンレス製である動圧発生用の流体軸受部品に，効率良く溝加工することが可能な加工方法が模索されている。
【０００８】
【課題を解決するための手段】
本発明の目的は，上記の課題を解決することであり，ステンレス素材からなる高硬度の軸受部品を，切削加工にて溝加工を行うことが可能な加工方法を提供することである。
【０００９】
この発明は，筒状外周面及び軸方向に面する端面を備えた軸体と，前記筒状外周面及び前記端面との間にそれぞれ動圧用の隙間を介して対向する筒状内周面及び対向端面を備え且つ前記軸体と相対回転する軸嵌合体とを具備し，前記軸体の前記筒状外周面及び前記端面，又は前記軸嵌合体の前記筒状内周面及び前記対向端面はそれぞれ周面用動圧発生溝が形成されたステンレス製筒状周面及び端面用動圧発生溝が形成されたステンレス製端面であることから成る動圧軸受における動圧発生溝の加工方法において，
前記軸嵌合体の前記周面用動圧発生溝と前記端面用動圧発生溝とをダイヤモンドから構成される複数の切削バイトによって続けて切削加工するにあたって，
前記軸嵌合体は回転するワーク保持体に保持された状態で前記軸嵌合体の回転中心の回りに回転させ，回転している前記軸嵌合体の前記対向端面に沿って前記切削バイトの端面溝加工用のダイヤモンド製バイトが移動して前記端面用動圧発生溝を加工し，続けて回転している前記軸嵌合体の軸方向に前記切削バイトの周面溝加工用のダイヤモンド製バイトが移動しつつ前記周面用動圧発生溝を加工することを特徴とする動圧軸受における動圧発生溝の加工方法に関する。
【００１０】
この動圧発生溝の加工方法によれば，ステンレス製筒状周面である軸体の外側筒状周面又は軸嵌合体の内側筒状周面，或いはステンレス製端面である軸体の端面と軸嵌合体の対向端面の溝切削加工には，ダイヤモンドが使用される。動圧発生溝の加工においては，回転しているワークである軸体，又は軸嵌合体に対してダイヤモンドから成る切削バイトを当てることによって，切削加工が行われる。軸体のステンレス製筒状周面である外側筒状周面とステンレス製端面である端面とに動圧発生溝を加工する場合，及び軸嵌合体のステンレス製筒状周面である内側筒状周面とステンレス製端面である対向端面においては，ダイヤモンドから構成される同じ切削バイトで周面用動圧発生溝と端面用動圧発生溝を続けて加工することもできる。
【００１１】
切削バイトに用いられているダイヤモンドは，摩耗しても研磨することにより再使用可能である。この加工においては，切削バイトに対するワークの周速が一般旋削の場合と比較して非常に低く設定されているため，切削加工に伴って切削バイトに発生する加工熱が少ない。従って，ダイヤモンドの炭素化が進行せず，ステンレス製素材への良好な溝加工が実現される。
【００１２】
【発明の実施の形態】
以下，添付図面を参照しつつ，この発明による動圧軸受における動圧発生溝の加工方法の実施例を説明する。図１はこの発明による動圧軸受における動圧発生溝の加工方法で製作される動圧軸受の軸嵌合体の一例を示す断面図，図２は図１に示す動圧軸受の軸嵌合体の底面図である。
【００１３】
図１に示す動圧軸受１の軸嵌合体２は，例えば，固定側として設けられてた軸嵌合体であり，筒状体３と，筒状体３の下端部おいて径方向に延びるフランジ部４とから構成されている。フランジ部４には，周方向に適宜の間隔で隔置して，取付け用の固着具（取付けボルト）が挿通される複数の取付け孔５が形成されている。筒状体３には，軸方向に貫通する筒状内周面６が形成されており，筒状内周面６には，想像線で示すように，軸体７が軸嵌合体２に対して相対回転自在に嵌合配置されている。この例では，筒状体３はステンレス製の素材から形成されているが，それに合わせて，軸体７もステンレス製とすることができる。
【００１４】
筒状体３の筒状内周面６は，軸体７の筒状外周面８と共に，動圧軸受１の周面用動圧面を構成しており，筒状内周面６と筒状外周面８との間には，動圧作動用の流体（例えば，空気）が介在する隙間９が形成されている。筒状体３がステンレス製であるので，筒状体３の筒状内周面６もステンレスの表面に形成されている。筒状内周面６には，更に，軸方向に隔置した２つの位置においてヘリングボーン型の周面用動圧発生溝１０，１１が形成されている。筒状内周面６自体も切削加工により形成されているが，周面用動圧発生溝１０，１１は，ダイヤモンドから製作された切削バイトによって形成されている。筒状内周面６の周面用動圧発生溝１０，１１間には，内径を僅かに大きくした逃げ部１２が形成されている。周面用動圧発生溝１０，１１は，軸嵌合体２が軸体７に対して回転するとき，隙間９内の流体によってラジアル方向の動圧を発生するので，軸嵌合体２は軸体７に対してラジアル方向に回転自在に支持される。なお，筒状内周面６及び動圧発生溝１０，１１には，適宜の表面処理を施すことが可能である。
【００１５】
軸体７の軸方向を向く端面１３と，端面１３と対向する筒状体３の対向端面１４とは，共働して動圧軸受１の端面用動圧面を構成しており，端面１３と対向端面１４との間には，動圧作動用の流体（例えば空気）が介在する隙間１５が形成されている。筒状体３がステンレス製であるので，筒状体３の対向端面１４もステンレスの表面に形成されている。筒状体３の対向端面１４自体も切削加工により形成されているが，対向端面１４には，更に，環状の領域１６において周方向に隔置して複数の放射状に拡がった区域１７に，端面用動圧発生溝１８（一部のみ符号で指す）が形成されている。端面用動圧発生溝１８は，ダイヤモンドから製作された切削バイトによって周方向に対して傾斜して形成されている。軸嵌合体２が軸体７に対して回転するとき，端面用動圧発生溝１８は隙間１５内の流体によってスラスト方向の動圧を発生するので，軸嵌合体２は軸体７に対してスラスト方向に回転自在に支持される。なお，対向端面１４及び動圧発生溝１８には，適宜の表面処理を施すことができ，また，端面用動圧発生溝１８の溝形状は，周面用動圧発生溝１０，１１と同様に，ヘリングボーン型とすることもできる。
【００１６】
ダイヤモンドから製作された切削バイトによる切削加工においては，ワークである軸嵌合体２が回転されるが，その周速は，一般旋削時と比較して極端に低く設定されているので，切削加工に伴って発生する加工熱が非常に少ない。従って，ダイヤモンドの炭素化が進行せず，ステンレス製の素材に対して，良好な溝が加工を施すことができる。
【００１７】
上記の例では，軸嵌合体２の筒状内周面５にヘリングボーン型の周面用動圧発生溝１０，１１を形成し，軸嵌合体２の対向端面１４に端面用動圧発生溝１８を形成していたが，周面用動圧発生溝については，軸嵌合体２の筒状内周面６に形成する代わりに，軸体７の筒状外周面８に，又は軸嵌合体２の筒状内周面５と軸体７の筒状外周面８の双方に形成してもよい。また，端面用動圧発生溝については，軸嵌合体２の対向端面１４に形成する代わりに，軸体７の端面１３に，又は軸嵌合体２の対向端面１４と軸体７の端面１３の双方に形成してもよい。
【００１８】
この発明による動圧軸受における動圧発生溝の加工態様の一例の概略が，図３に示されている。図３に示す加工工程は，軸嵌合体２をワークとしてその筒状内周面６と端面１４とに施される切削加工を示しており，矢印に沿って移動する切削バイトにより切削加工が行われる。軸嵌合体２は，回転するワーク保持体２０に保持された状態で，軸嵌合体２の回転中心Ｃ−Ｃの回りにゆっくりと回転される。切削バイトＴ１は，荒加工用バイトであり，軸嵌合体２の対向端面１４に沿った方向に移動し更に筒状体２の内部へと移動して，対向端面１４と筒状内周面６との荒加工を行う。切削バイトＴ２は，端面溝加工用のダイヤモンド製バイトであり，軸嵌合体２の対向端面１４に沿って移動して端面用動圧発生溝１８を加工する。また，切削バイトＴ３は，周面溝加工用のダイヤモンド製バイトであり，軸嵌合体２の軸方向に移動しつつ周面用動圧発生溝１０，１１を加工する。最後に，切削バイトＴ４は，端面及び周面仕上げ用の切削バイトであり，軸嵌合体２の対向端面１４に沿った方向に移動し更に軸嵌合体２の筒状内周面６に沿って移動して，対向端面１４と筒状内周面６との仕上げ加工を行う。
【００１９】
【発明の効果】
この発明による動圧軸受における動圧発生溝の加工方法は，上記に説明した工程で行われるので，次のような効果が得られる。即ち，この発明による動圧軸受における動圧発生溝の加工方法によれば，ダイヤモンドから製作される切削バイトによって動圧発生溝を切削加工しているので，ダイヤモンドから製作される切削バイトの形状を溝形状に合わせることにより，様々な溝形状を有する動圧発生溝を容易に実現できる。また，ダイヤモンドから製作される切削バイトによる溝加工は，切削バイトが摩耗しても切削バイトを再研磨することで，切削バイトを再使用することが可能であり，再研磨費用も転造工具による製作費用の１／３〜１／５で済ますことができる。更に，±１μｍの公差が要求される動圧発生溝の溝深さに対して，ダイヤモンドから製作される切削バイトでは，機械の座標オフセットにて補正できるメリットがある。
【図面の簡単な説明】
【図１】 この発明による動圧軸受における動圧発生溝の加工方法によって製作された動圧軸受の一例を示す縦断面図である。
【図２】 図１に示す動圧軸受の底面図である。
【図３】 この発明による動圧軸受における動圧発生溝の加工態様を示す概略図である。
【符号の説明】
１ 動圧軸受
２ 軸嵌合体
６ 筒状内周面
７ 軸体
８ 筒状外周面
９ 隙間
１０，１１ 周面用動圧発生溝
１３ 端面
１４ 対向端面
１５ 隙間
１８ 端面用動圧発生溝
Ｔ１〜Ｔ４ 切削バイト[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for machining a dynamic pressure generating groove formed on a dynamic pressure bearing surface in a dynamic pressure bearing that supports a rotating shaft by utilizing the dynamic pressure of fluid.
[0002]
[Prior art]
Conventionally, a dynamic pressure bearing such as an air bearing has been used to rotationally drive a rotating body such as a polygon mirror, a magnetic disk, or an optical disk with low friction. An example of such a dynamic pressure bearing is disclosed in JP-A-8-196056. In the dynamic pressure bearing disclosed in this publication, a herringbone type dynamic pressure generating groove is formed on an outer peripheral surface of a fixed shaft by dividing it into two blocks in the axial direction. The torso is rotatably mounted. A radial bearing is formed by forming an air dynamic pressure between the outer peripheral surface of the fixed shaft and the inner surface of the cylindrical body portion of the rotor. An air supply hole extends in the axial direction from the shaft end of the fixed shaft, and the air supply hole is fed in an intermediate portion of the dynamic pressure generating groove of the two blocks. Are discharged to the outside.
[0003]
As a processing method for forming a dynamic pressure generating groove on the bearing surface of the dynamic pressure bearing as described above, a processing method such as etching, pressing, blasting, laser, rolling or the like is employed. The most commonly used method is a processing method using a rolling tool. In addition, when a groove is formed in a non-ferrous metal such as aluminum or brass, the groove may be formed by cutting using a cutting tool (such as a diamond tool).
[0004]
Cutting that forms a groove for generating dynamic pressure on the bearing surface of a hydrodynamic bearing disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 8-196056 is based on the following. By forming both the dynamic pressure surface and the dynamic pressure generating groove by cutting, the dynamic pressure surface and the dynamic pressure generating groove can be formed without troublesome rolling or etching. Both can be formed satisfactorily without lowering the machining accuracy, and are designed to be formed without detachment with the same cutting machine.
[0005]
However, none of these methods is satisfactory in terms of production cost and processing accuracy. Currently, the only possible machining shape for rolling grooving using the mainstream rolling tools is the arc groove shape. Rolled tools must be remanufactured once worn, the unit price per tool is expensive, and the running cost per workpiece is high. Further, the groove depth of the dynamic pressure generating groove is required to have a tolerance of ± 1 μm, and there is a problem that a rolling tool cannot be used once it is worn.
[0006]
[Problems to be solved by the invention]
By the way, recently, a stainless steel material has become mainstream as a fluid bearing part for a hard disk drive (HDD). The grooving method applied to a material having a relatively low hardness such as aluminum or an alloy thereof cannot be directly applied to the grooving of a high-hardness bearing part made of stainless steel.
[0007]
Furthermore, it is conceivable to use diamond as a cutting tool as a method of cutting a material having high hardness. However, it is generally accepted that the use of diamond for cutting ferrous materials, including stainless steel, does not endure the use of diamond because of its rapid wear. In view of this, a machining method capable of efficiently grooving a hydrodynamic bearing component for generating dynamic pressure, which is made of stainless steel as a workpiece, is being sought.
[0008]
[Means for Solving the Problems]
An object of the present invention is to solve the above-described problems and to provide a machining method capable of grooving a high-hardness bearing component made of a stainless steel material by cutting.
[0009]
This invention includes a shaft having an end surface facing the cylinder Jogaishu surface and axial, cylindrical inner peripheral surface facing each through a gap of the dynamic pressure between the cylindrical outer peripheral surface and the end face and A shaft fitting body provided with an opposing end surface and rotating relative to the shaft body, the cylindrical outer peripheral surface and the end surface of the shaft body, or the cylindrical inner peripheral surface and the opposing end surface of the shaft fitting body, In the method of processing a dynamic pressure generating groove in a dynamic pressure bearing comprising a stainless steel cylindrical peripheral surface formed with a peripheral surface dynamic pressure generating groove and a stainless steel end surface formed with an end surface dynamic pressure generating groove , respectively.
In cutting and the shaft fitting said end face for dynamic pressure generating groove and the circumferential surface for hydrodynamic grooves coalescence followed by a plurality of cutting tool consisting of a diamond,
The shaft fitting body is rotated around the rotation center of the shaft fitting body while being held by a rotating work holding body, and the end face groove of the cutting bit is along the opposite end face of the rotating shaft fitting body A diamond bit for machining moves to process the dynamic pressure generating groove for the end face, and a diamond bit for machining the peripheral groove of the cutting bit moves in the axial direction of the rotating shaft fitting. In particular, the present invention relates to a method for processing a dynamic pressure generating groove in a dynamic pressure bearing, wherein the peripheral surface dynamic pressure generating groove is processed .
[0010]
According to this machining method of the dynamic pressure generating groove, the outer cylindrical peripheral surface of the shaft body which is a stainless steel cylindrical peripheral surface, the inner cylindrical peripheral surface of the shaft fitting body, or the end surface of the shaft body which is a stainless steel end surface Diamond is used for the groove cutting of the opposite end face of the shaft fitting. In the machining of the dynamic pressure generating groove, cutting is performed by applying a cutting tool made of diamond to a rotating shaft or a shaft fitting. When machining dynamic pressure generating grooves on the outer cylindrical peripheral surface that is the stainless steel cylindrical peripheral surface of the shaft body and the end surface that is the stainless steel end surface, and the inner cylindrical shape that is the stainless steel cylindrical peripheral surface of the shaft fitting body On the opposing end surface, which is the peripheral surface and the stainless steel end surface, the peripheral surface dynamic pressure generating groove and the end surface dynamic pressure generating groove can be continuously processed with the same cutting tool made of diamond.
[0011]
Diamonds used for cutting tools can be reused by polishing even if worn. In this machining, since the peripheral speed of the workpiece with respect to the cutting bit is set to be very low compared with the case of general turning, less machining heat is generated in the cutting bit along with the cutting. Therefore, the carbonization of diamond does not proceed and good grooving of stainless steel material is realized.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a method for machining a dynamic pressure generating groove in a dynamic pressure bearing according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of a shaft fitting body of a fluid dynamic bearing manufactured by the method of machining a dynamic pressure generating groove in the fluid dynamic bearing according to the present invention, and FIG. 2 shows a shaft fitting body of the fluid dynamic bearing shown in FIG. It is a bottom view.
[0013]
A shaft fitting body 2 of the hydrodynamic bearing 1 shown in FIG. 1 is, for example, a shaft fitting body provided as a fixed side, and a tubular body 3 and a flange extending in the radial direction at the lower end portion of the tubular body 3 Part 4. The flange portion 4 is formed with a plurality of mounting holes 5 through which fixing tools (mounting bolts) for mounting are inserted at appropriate intervals in the circumferential direction. The cylindrical body 3 is formed with a cylindrical inner peripheral surface 6 penetrating in the axial direction. On the cylindrical inner peripheral surface 6, as shown by an imaginary line, the shaft body 7 is located with respect to the shaft fitting body 2. And are arranged to be relatively rotatable. In this example, the cylindrical body 3 is made of a stainless steel material, but the shaft body 7 can be made of stainless steel accordingly.
[0014]
The cylindrical inner peripheral surface 6 of the cylindrical body 3 and the cylindrical outer peripheral surface 8 of the shaft body 7 constitute the dynamic pressure surface for the peripheral surface of the hydrodynamic bearing 1. The cylindrical inner peripheral surface 6 and the cylindrical outer peripheral surface A gap 9 is formed between the surface 8 and a fluid for operating dynamic pressure (for example, air). Since the cylindrical body 3 is made of stainless steel, the cylindrical inner peripheral surface 6 of the cylindrical body 3 is also formed on the stainless steel surface. The cylindrical inner peripheral surface 6 is further formed with herringbone type peripheral surface dynamic pressure generating grooves 10 and 11 at two positions spaced apart in the axial direction. The cylindrical inner peripheral surface 6 itself is also formed by cutting, but the peripheral surface dynamic pressure generating grooves 10 and 11 are formed by a cutting tool made of diamond. Between the peripheral surface dynamic pressure generating grooves 10 and 11 of the cylindrical inner peripheral surface 6, a relief portion 12 having a slightly larger inner diameter is formed. Since the circumferential surface dynamic pressure generating grooves 10 and 11 generate a radial dynamic pressure by the fluid in the gap 9 when the shaft fitting body 2 rotates with respect to the shaft body 7, the shaft fitting body 2 is a shaft body. 7 is supported rotatably in the radial direction. The cylindrical inner peripheral surface 6 and the dynamic pressure generating grooves 10 and 11 can be subjected to appropriate surface treatment.
[0015]
The end surface 13 facing the axial direction of the shaft body 7 and the facing end surface 14 of the cylindrical body 3 facing the end surface 13 cooperate to constitute a dynamic pressure surface for the end surface of the fluid dynamic bearing 1. A gap 15 is formed between the opposed end face 14 and a fluid for operating dynamic pressure (for example, air). Since the cylindrical body 3 is made of stainless steel, the opposed end surface 14 of the cylindrical body 3 is also formed on the stainless steel surface. The opposed end surface 14 itself of the cylindrical body 3 is also formed by cutting. However, the opposed end surface 14 is further provided with a plurality of radially expanded areas 17 spaced circumferentially in the annular region 16. A working dynamic pressure generating groove 18 (only a part is indicated by a symbol) is formed. The end surface dynamic pressure generating groove 18 is formed to be inclined with respect to the circumferential direction by a cutting tool made of diamond. When the shaft fitting body 2 rotates with respect to the shaft body 7, the end face dynamic pressure generating groove 18 generates a dynamic pressure in the thrust direction by the fluid in the gap 15. It is supported rotatably in the thrust direction. The opposing end surface 14 and the dynamic pressure generating groove 18 can be subjected to appropriate surface treatment, and the shape of the end surface dynamic pressure generating groove 18 is the same as that of the peripheral surface dynamic pressure generating grooves 10 and 11. In addition, it can be a herringbone type.
[0016]
In cutting with a cutting tool made of diamond, the shaft fitting 2 that is a workpiece is rotated, but its peripheral speed is set to be extremely low compared to general turning. Very little processing heat is generated. Therefore, the carbonization of diamond does not proceed, and a good groove can be processed on a stainless steel material.
[0017]
In the above example, the herringbone type peripheral surface dynamic pressure generating grooves 10 and 11 are formed on the cylindrical inner peripheral surface 5 of the shaft fitting body 2, and the end surface dynamic pressure generating grooves are formed on the opposing end surface 14 of the shaft fitting body 2. 18, the circumferential surface dynamic pressure generating groove is formed on the cylindrical outer peripheral surface 8 of the shaft body 7 or on the shaft fitting body instead of being formed on the cylindrical inner peripheral surface 6 of the shaft fitting body 2. You may form in both the cylindrical inner peripheral surface 5 of 2 and the cylindrical outer peripheral surface 8 of the shaft body 7. FIG. Further, the end surface dynamic pressure generating groove is not formed on the opposed end surface 14 of the shaft fitting body 2 but on the end surface 13 of the shaft body 7 or between the opposed end surface 14 of the shaft fitting body 2 and the end surface 13 of the shaft body 7. You may form both.
[0018]
FIG. 3 shows an outline of an example of a machining mode of the dynamic pressure generating groove in the dynamic pressure bearing according to the present invention. The machining process shown in FIG. 3 shows a cutting process performed on the cylindrical inner peripheral surface 6 and the end surface 14 using the shaft fitting body 2 as a workpiece, and the cutting process is performed by a cutting tool moving along an arrow. Is called. The shaft fitting body 2 is slowly rotated around the rotation center CC of the shaft fitting body 2 while being held by the rotating work holder 20. The cutting tool T1 is a roughing tool, and moves in a direction along the opposing end face 14 of the shaft fitting body 2 and further moves into the cylindrical body 2 so that the opposing end face 14 and the cylindrical inner peripheral face 6 are moved. And roughing. The cutting tool T2 is a diamond tool for end face groove processing, and moves along the opposing end face 14 of the shaft fitting 2 to process the end face dynamic pressure generating groove 18. Further, the cutting tool T3 is a diamond tool for processing the peripheral groove, and processes the peripheral surface dynamic pressure generating grooves 10 and 11 while moving in the axial direction of the shaft fitting 2. Finally, the cutting tool T4 is a cutting tool for finishing the end face and the peripheral surface, and moves in a direction along the opposed end surface 14 of the shaft fitting body 2 and further along the cylindrical inner peripheral surface 6 of the shaft fitting body 2. It moves and finishes the opposing end surface 14 and the cylindrical inner peripheral surface 6.
[0019]
【The invention's effect】
Since the method for processing the dynamic pressure generating groove in the dynamic pressure bearing according to the present invention is performed in the steps described above, the following effects can be obtained. That is, according to the method of machining a dynamic pressure generating groove in a hydrodynamic bearing according to the present invention, the dynamic pressure generating groove is cut by a cutting bit manufactured from diamond, so that the shape of the cutting bit manufactured from diamond is changed. By adjusting to the groove shape, a dynamic pressure generating groove having various groove shapes can be easily realized. In addition, grooving with a cutting tool manufactured from diamond allows the cutting tool to be reused by re-polishing the cutting tool even if the cutting tool is worn, and the re-grinding cost is also determined by a rolling tool. This can be done for 1/3 to 1/5 of the production cost. Furthermore, with respect to the groove depth of the dynamic pressure generating groove that requires a tolerance of ± 1 μm, a cutting tool manufactured from diamond has an advantage that it can be corrected by a machine coordinate offset.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of a dynamic pressure bearing manufactured by a method of processing a dynamic pressure generating groove in a dynamic pressure bearing according to the present invention.
2 is a bottom view of the hydrodynamic bearing shown in FIG. 1. FIG.
FIG. 3 is a schematic view showing a machining mode of a dynamic pressure generating groove in the dynamic pressure bearing according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dynamic pressure bearing 2 Shaft fitting body 6 Cylindrical inner peripheral surface 7 Shaft body 8 Cylindrical outer peripheral surface 9 Crevice 10,11 Circumferential surface dynamic pressure generating groove 13 End surface 14 Opposing end surface 15 Clearance 18 End surface dynamic pressure generating groove T1- T4 cutting tool

Claims (1)

筒状外周面及び軸方向に面する端面を備えた軸体と，前記筒状外周面及び前記端面との間にそれぞれ動圧用の隙間を介して対向する筒状内周面及び対向端面を備え且つ前記軸体と相対回転する軸嵌合体とを具備し，前記軸体の前記筒状外周面及び前記端面，又は前記軸嵌合体の前記筒状内周面及び前記対向端面はそれぞれ周面用動圧発生溝が形成されたステンレス製筒状周面及び端面用動圧発生溝が形成されたステンレス製端面であることから成る動圧軸受における動圧発生溝の加工方法において，
前記軸嵌合体の前記周面用動圧発生溝と前記端面用動圧発生溝とをダイヤモンドから構成される複数の切削バイトによって続けて切削加工するにあたって，
前記軸嵌合体は回転するワーク保持体に保持された状態で前記軸嵌合体の回転中心の回りに回転させ，回転している前記軸嵌合体の前記対向端面に沿って前記切削バイトの端面溝加工用のダイヤモンド製バイトが移動して前記端面用動圧発生溝を加工し，続けて回転している前記軸嵌合体の軸方向に前記切削バイトの周面溝加工用のダイヤモンド製バイトが移動しつつ前記周面用動圧発生溝を加工することを特徴とする動圧軸受における動圧発生溝の加工方法。A shaft body having a cylindrical outer peripheral surface and an end surface facing in the axial direction, and a cylindrical inner peripheral surface and a facing end surface that are opposed to each other through a gap for dynamic pressure between the cylindrical outer peripheral surface and the end surface, respectively. A shaft fitting body that rotates relative to the shaft body, and the cylindrical outer peripheral surface and the end surface of the shaft body, or the cylindrical inner peripheral surface and the opposed end surface of the shaft fitting body are for peripheral surfaces, respectively. In the method of machining a dynamic pressure generating groove in a dynamic pressure bearing comprising a stainless steel cylindrical peripheral surface in which a dynamic pressure generating groove is formed and a stainless steel end surface in which a dynamic pressure generating groove for an end surface is formed.
In cutting and the shaft fitting said end face for dynamic pressure generating groove and the circumferential surface for hydrodynamic grooves coalescence followed by a plurality of cutting tool consisting of a diamond,
The shaft fitting body is rotated around the rotation center of the shaft fitting body while being held by a rotating work holding body, and the end face groove of the cutting bit is along the opposite end face of the rotating shaft fitting body A diamond bit for machining moves to process the dynamic pressure generating groove for the end face, and a diamond bit for machining the peripheral groove of the cutting bit moves in the axial direction of the rotating shaft fitting. A method for machining a dynamic pressure generating groove in a hydrodynamic bearing, wherein the circumferential dynamic pressure generating groove is machined.
JP2000054682A 2000-02-29 2000-02-29 Method for machining dynamic pressure generating groove in hydrodynamic bearing Expired - Fee Related JP4431244B2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111917258A (en) * 2020-08-31 2020-11-10 阜南县特立电子有限公司 Lower shell shaft pressing equipment for direct-current brushless motor and shaft pressing method thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102005061853A1 (en) * 2005-12-23 2007-07-05 Minebea Co., Ltd. spindle motor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111917258A (en) * 2020-08-31 2020-11-10 阜南县特立电子有限公司 Lower shell shaft pressing equipment for direct-current brushless motor and shaft pressing method thereof

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