JP2012031969A - Hub integrated shaft for fluid dynamic pressure bearing device, and method for manufacturing the same - Google Patents

Hub integrated shaft for fluid dynamic pressure bearing device, and method for manufacturing the same Download PDF

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JP2012031969A
JP2012031969A JP2010173652A JP2010173652A JP2012031969A JP 2012031969 A JP2012031969 A JP 2012031969A JP 2010173652 A JP2010173652 A JP 2010173652A JP 2010173652 A JP2010173652 A JP 2010173652A JP 2012031969 A JP2012031969 A JP 2012031969A
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hub
shaft
peripheral surface
outer peripheral
shaft portion
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Natsuhiko Mori
夏比古 森
Atsushi Hiraide
淳 平出
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NTN Corp
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NTN Toyo Bearing Co Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a hub integrated shaft that can sufficiently improve dimensional accuracy even with a thinned hub portion.SOLUTION: A method for manufacturing a hub integrated shaft includes: forming, by plastic machining a plate material, a roughly-shaped material 30 having a shaft portion 21 and a hub portion 22 integrally; and finishing by grinding, among the portions of the roughly-shaped material 30, at least the outer periphery 21b of the shaft portion 21 and a rotor mounting surface (the upper side end surface 22c1 of a flange part 22c) of the hub portion 22.

Description

本発明は、流体動圧軸受装置に用いられるハブ一体軸及びその製造方法に関する。   The present invention relates to a hub integrated shaft used in a fluid dynamic bearing device and a manufacturing method thereof.

流体動圧軸受装置は、軸受部材の内周面と軸部材の外周面との間のラジアル軸受隙間に生じる潤滑油の動圧作用により、軸部材を相対回転自在に支持するものである。流体動圧軸受装置は、優れた回転精度および静粛性を有するため、例えば、各種ディスク駆動装置(HDDの磁気ディスク駆動装置や、CD−ROM等の光ディスク駆動装置等)のスピンドルモータ用、レーザビームプリンタ(LBP)のポリゴンスキャナモータ用、あるいはプロジェクタのカラーホイールモータ用として好適に使用されている。   The fluid dynamic pressure bearing device supports a shaft member so as to be relatively rotatable by a dynamic pressure action of lubricating oil generated in a radial bearing gap between an inner peripheral surface of the bearing member and an outer peripheral surface of the shaft member. Since the fluid dynamic bearing device has excellent rotational accuracy and quietness, for example, for spindle motors of various disk drive devices (such as HDD magnetic disk drive devices and CD-ROM optical disk drive devices), laser beams, etc. It is suitably used for a polygon scanner motor of a printer (LBP) or a color wheel motor of a projector.

例えば特許文献1には、HDDのスピンドルモータに組み組まれる流体動圧軸受装置が示されている。この流体動圧軸受装置は、軸部材2と、内周に軸部材2を挿入した軸受スリーブ8と、軸部材2の上端外周に固定されたディスクハブ3とを備え、ディスクハブ3に情報記録媒体となるディスクDが搭載される。軸部材2が回転すると、軸部材2の外周面と軸受スリーブ8の内周面との間のラジアル軸受隙間に生じる油膜の圧力が高められ、この動圧作用により、軸部材2、ディスクハブ3、及びディスクDが一体となって回転支持される。   For example, Patent Document 1 discloses a fluid dynamic bearing device assembled in a spindle motor of an HDD. This fluid dynamic pressure bearing device includes a shaft member 2, a bearing sleeve 8 in which the shaft member 2 is inserted on the inner periphery, and a disk hub 3 fixed to the outer periphery of the upper end of the shaft member 2. A disk D as a medium is mounted. When the shaft member 2 rotates, the pressure of the oil film generated in the radial bearing gap between the outer peripheral surface of the shaft member 2 and the inner peripheral surface of the bearing sleeve 8 is increased, and this dynamic pressure action causes the shaft member 2 and the disk hub 3 to move. , And the disk D are integrally supported by rotation.

特開2009−299836号公報JP 2009-299836 A 特開平6−261489号公報Japanese Patent Laid-Open No. 6-261489

近年、ノートパソコン等の情報機器の薄型化及び軽量化が進み、これに組み込まれるHDDのスピンドルモータへの薄型化及び軽量化の要求が益々強くなっている。この要求に応えるべく、HDDのスピンドルモータ用の流体動圧軸受装置では、磁気ディスクを搭載するディスクハブの薄肉化が検討されている。しかし、ディスクハブを薄肉化すると、以下のような課題が生じる。   In recent years, information devices such as notebook personal computers have been made thinner and lighter, and the demand for thinner and lighter HDD spindle motors incorporated therein has been increasing. In order to meet this demand, in a fluid dynamic bearing device for a spindle motor of an HDD, it is considered to reduce the thickness of a disk hub on which a magnetic disk is mounted. However, when the disk hub is thinned, the following problems arise.

第一に、ディスクハブの薄肉化により、軸部材とディスクハブとの締結面積が縮小されるため、両者の締結強度が低下する恐れがある。例えば、締結部に接着剤を塗布すれば締結強度を高めることができるが、この場合、接着剤の材料コストがかかると共に、接着剤を塗布する工程を要することで製造コストがかかる。   First, since the fastening area between the shaft member and the disk hub is reduced by reducing the thickness of the disk hub, the fastening strength of the two may be reduced. For example, if an adhesive is applied to the fastening portion, the fastening strength can be increased. In this case, the material cost of the adhesive is increased, and the manufacturing cost is increased due to the need for the step of applying the adhesive.

第二に、ディスクハブの薄肉化により、軸部材とディスクハブとの嵌合面積が縮小されるため、両者の組付精度が低下する。これにより、軸部材の外周面に対するディスク搭載面の面精度(振れ精度など)が低下し、ディスクの回転精度の低下、ひいてはHDDのディスク読み取り精度の低下を招く恐れがある。   Secondly, since the fitting area between the shaft member and the disk hub is reduced by reducing the thickness of the disk hub, the assembling accuracy of the both decreases. As a result, the surface accuracy (runout accuracy, etc.) of the disk mounting surface with respect to the outer peripheral surface of the shaft member is lowered, and there is a possibility that the rotation accuracy of the disk is lowered, and consequently the disk reading accuracy of the HDD is lowered.

第三に、ディスクハブの薄肉化により、ブランク材の加工量が多くなる。例えば、ディスクハブを旋削加工で形成する場合、ブランク材からの削り量が多くなるため、多量の切り屑が発生する。このように切削量が多いと、材料コストが高くなると共に、工具の消耗が激しく工具のコストも高くなる。また、製品一個あたりの加工時間が長くなるため、所定のサイクルで製造するためには多くの旋削機を準備する必要があり、大規模な設備投資を要する。   Thirdly, the processing amount of the blank material increases due to the thinning of the disk hub. For example, when the disk hub is formed by turning, a large amount of chips are generated because the amount of cutting from the blank material increases. When the amount of cutting is large as described above, the material cost increases, and the tool is heavily consumed, resulting in an increase in the cost of the tool. Moreover, since the processing time per product becomes long, it is necessary to prepare a large number of turning machines in order to manufacture in a predetermined cycle, which requires a large-scale capital investment.

例えば、特許文献2には、丸棒から所定長さのブランク材(スラグ)を切断し、このブランク材に据え込み加工及び打ち抜き加工を施した後、鍛造押出によりハブ及び軸部を一体に製造する方法が示されている。このように、ディスクハブと軸部材を一体成形すれば、これらを別体に形成した後に固定する場合と比べて、両者の締結強度が高められる。また、ハブ及び軸部の一体品を鍛造により成形することで、旋削加工のように多量に切り屑が発生することがなく、材料の歩留まりを高めることができる。   For example, in Patent Document 2, a blank material (slag) having a predetermined length is cut from a round bar, and after the upsetting process and the punching process are performed on the blank material, the hub and the shaft portion are integrally manufactured by forging extrusion. How to do is shown. In this way, if the disk hub and the shaft member are integrally formed, the fastening strength between them can be increased as compared with the case where they are fixed after being formed separately. Further, by forming the integrated hub and shaft part by forging, a large amount of chips are not generated unlike turning, and the yield of the material can be increased.

しかし、上記特許文献2では、円柱状のブランク材を塑性加工してハブ一体軸を成形しているため、スラグから製品に至るまでの変形量が大きく、所望の寸法精度を得ることが難しい。特に、上記のようにハブを薄肉化すると、ブランク材からの変形量がさらに大きくなる上、ハブの剛性が小さくなるため、ハブ一体軸の寸法精度を高めることがさらに困難となる。このため、HDDのスピンドルモータに要求される寸法精度、特に軸部材の外周面に対するディスク搭載面の面精度が得られず、ディスクの回転精度の低下を招く恐れがある。   However, in Patent Document 2, a cylindrical blank material is plastically processed to form a hub integrated shaft. Therefore, the amount of deformation from the slag to the product is large, and it is difficult to obtain a desired dimensional accuracy. In particular, when the hub is thinned as described above, the amount of deformation from the blank material is further increased, and the rigidity of the hub is reduced, making it more difficult to increase the dimensional accuracy of the hub integrated shaft. For this reason, the dimensional accuracy required for the HDD spindle motor, in particular, the surface accuracy of the disk mounting surface with respect to the outer peripheral surface of the shaft member, cannot be obtained, and the rotational accuracy of the disk may be reduced.

以上のような課題、すなわち、ハブを薄肉化したときの寸法精度の課題は、HDDのスピンドルモータに限らず、例えば、ポリゴンスキャナモータやカラーホイールモータに組み込まれる流体動圧軸受装置においても、同様に生じる。ただし、HDDのスピンドルモータ用の流体動圧軸受装置は、上記のように軽量化及び薄肉化の要求が強く、且つ、要求されるディスクの回転精度が高いため、上記の課題が特に顕著に発生する。   The above-mentioned problem, that is, the problem of dimensional accuracy when the hub is thinned, is not limited to the HDD spindle motor. For example, the same applies to a fluid dynamic pressure bearing device incorporated in a polygon scanner motor or a color wheel motor. To occur. However, the fluid dynamic pressure bearing device for the spindle motor of the HDD has a strong demand for weight reduction and thinning as described above, and the required rotational accuracy of the disk is high. To do.

本発明の解決すべき課題は、ハブを薄肉化した場合でも、寸法精度を十分に高めることが可能なハブ一体軸であって、特にHDDのスピンドルモータ用に適したハブ一体軸を得ることにある。   The problem to be solved by the present invention is to provide a hub integrated shaft capable of sufficiently increasing the dimensional accuracy even when the hub is thinned, and particularly to obtain a hub integrated shaft suitable for a spindle motor of an HDD. is there.

前記課題を解決するために、本発明は、外周面が、潤滑流体で満たされたラジアル軸受隙間に面する軸部と、軸部から外径に突出し、軸方向と直交する回転体搭載面を有するハブ部とを一体に備えた流体動圧軸受装置用のハブ一体軸であって、板材の塑性加工により軸部及びハブ部を一体成形した素形材のうち、軸部の外周面及びハブ部の回転体搭載面に研削仕上げが施されたハブ一体軸を提供する。   In order to solve the above problems, the present invention provides a shaft portion whose outer peripheral surface faces a radial bearing gap filled with a lubricating fluid, and a rotating body mounting surface that projects from the shaft portion to the outer diameter and is orthogonal to the axial direction. A hub-integrated shaft for a fluid dynamic pressure bearing device, which is integrally provided with a hub portion having a shaft portion, and an outer peripheral surface of the shaft portion and a hub among the shaped members in which the shaft portion and the hub portion are integrally formed by plastic processing of a plate material Provided is a hub-integrated shaft having a grinding finish on the rotating body mounting surface of the part.

このように、本発明のハブ一体軸は、板材の塑性加工により軸部及びハブ部を一体成形した素形材を用いて形成される。このようにハブ部及び軸部を一体成形することで、上述のように両者の締結強度が高められるため、ハブ部を薄肉化した場合でもハブ部と軸部とを強固に固定(一体化)することができる。また、素形材を板材から形成することで、ハブ部を薄肉化した場合でも塑性加工による変形量を抑えることができるため、素形材の寸法精度を高めることができる。   As described above, the hub integrated shaft of the present invention is formed by using a shaped material in which the shaft portion and the hub portion are integrally formed by plastic working of a plate material. By integrally forming the hub part and the shaft part in this way, the fastening strength between the two can be increased as described above, so that even when the hub part is thinned, the hub part and the shaft part are firmly fixed (integrated). can do. In addition, by forming the base material from a plate material, the amount of deformation due to plastic working can be suppressed even when the hub portion is thinned, so that the dimensional accuracy of the base material can be increased.

こうして得られた素形材のうち、特に精度が要求される箇所に研削仕上げを施される。具体的には、ラジアル軸受隙間に面する軸部の外周面と、回転体が搭載される回転体搭載面に研削仕上げが施される。これにより、回転体の回転精度が高められるため、例えばHDDのスピンドルモータ用の流体動圧軸受装置に要求される回転体(ディスク)の回転精度を満たすことができる。   Of the raw material thus obtained, a grinding finish is applied to a portion that requires particularly high accuracy. Specifically, the outer peripheral surface of the shaft part facing the radial bearing gap and the rotating body mounting surface on which the rotating body is mounted are ground. As a result, the rotational accuracy of the rotating body is enhanced, so that the rotational accuracy of the rotating body (disk) required for a fluid dynamic bearing device for an HDD spindle motor, for example, can be satisfied.

軸部の外周面はラジアル軸受隙間に面するため、特に優れた面精度で加工する必要がある。そこで、先にハブ部に研削仕上げを施した後、この高精度な研削仕上げ面を基準として軸部の外周面に研削仕上げを施せば、軸部の外周面の面精度がさらに高められる。   Since the outer peripheral surface of the shaft portion faces the radial bearing gap, it is necessary to process with particularly excellent surface accuracy. Therefore, if the hub portion is first ground and then the outer peripheral surface of the shaft portion is ground based on this highly accurate ground surface, the surface accuracy of the outer peripheral surface of the shaft portion can be further improved.

また、軸部の外周面及びハブ部の回転体搭載面を、それぞれ優れた寸法精度で加工したとしても、これらの相対的な位置精度(例えば振れ精度)が十分でないと、回転体の回転精度を十分に高めることができない恐れがある。そこで上記のように、研削仕上げが施されたハブ部の回転体搭載面を基準として軸部の外周面に研削仕上げを施せば、軸部の外周面に対する回転体搭載面の振れ精度を高めることができる。また、ハブ部の外周面にも研削仕上げを施す場合、回転体搭載面に加えて、研削仕上げが施されたハブ部の外周面を基準とすれば、軸部の外周面とハブ部との同軸度を高めることができる。尚、振れ精度、及び同軸度の定義は、JIS B 0021:1998による。   Moreover, even if the outer peripheral surface of the shaft portion and the rotating body mounting surface of the hub portion are processed with excellent dimensional accuracy, if the relative positional accuracy (for example, runout accuracy) is not sufficient, the rotational accuracy of the rotating body There is a risk that it cannot be raised sufficiently. Therefore, as described above, if the outer peripheral surface of the shaft part is ground with reference to the rotating body mounting surface of the hub part that has been ground, the runout accuracy of the rotating body mounting surface with respect to the outer peripheral surface of the shaft part can be improved. Can do. In addition, when grinding the outer peripheral surface of the hub portion, in addition to the rotating body mounting surface, if the outer peripheral surface of the hub portion that has been ground is used as a reference, the outer peripheral surface of the shaft portion and the hub portion The degree of coaxiality can be increased. The definition of runout accuracy and coaxiality is based on JIS B 0021: 1998.

軸部の外周面に対する回転体搭載面の振れ精度は、例えば5μm以下とすることが好ましい。また、回転体搭載面の平面度は、例えば1μm以下とすることが好ましい。   The deflection accuracy of the rotating body mounting surface with respect to the outer peripheral surface of the shaft portion is preferably 5 μm or less, for example. The flatness of the rotating body mounting surface is preferably set to 1 μm or less, for example.

軸部の外周面は、ラジアル軸受隙間を介して対向する軸受部材の内周面と接触摺動することがあるため、高い耐摩耗性が要求される。従って、軸部の外周面に表面硬化処理やコーティング処理を施して、耐摩耗性を高めることが好ましい。この場合、軸部の外周面に表面硬化処理やコーティング処理を施して耐摩耗性を高めてから、この面に研削仕上げを施せば、研削による疵を抑えることができる。また、軸部の外周面に研削仕上げを施してから、この面にコーティング処理を施せば、研削による疵をコーティングで覆うことができる。   Since the outer peripheral surface of the shaft portion may slide in contact with the inner peripheral surface of the bearing member facing through the radial bearing gap, high wear resistance is required. Therefore, it is preferable to increase the wear resistance by subjecting the outer peripheral surface of the shaft portion to surface hardening treatment or coating treatment. In this case, if surface hardening treatment or coating treatment is performed on the outer peripheral surface of the shaft portion to increase wear resistance, and grinding finish is applied to this surface, wrinkles due to grinding can be suppressed. Further, if grinding is performed on the outer peripheral surface of the shaft portion and then this surface is subjected to a coating treatment, the wrinkles by grinding can be covered with the coating.

上記のように、軸部の外周面には高い耐摩耗性が要求される。また、ハブ部は、回転体を搭載した状態で長期にわたり形状を維持する必要があるため、高い強度が要求される。これらの点から、上記のハブ一体軸はステンレス鋼で形成することが好ましい。ただし、ステンレス鋼は一般に成形性に乏しいため、上記のように板材からハブ部及び軸部を一体に有する素形材を成形するためには、ステンレス鋼の中でも比較的成形性に優れたフェライト系ステンレス鋼を用いることが好ましい。さらに、フェライト系ステンレス鋼にTiを0.05%以上配合すれば、延性を高めることができるため好ましい。   As described above, high wear resistance is required for the outer peripheral surface of the shaft portion. Moreover, since it is necessary to maintain a shape for a long time in the state which mounted the rotary body, the hub part requires high intensity | strength. From these points, the hub integrated shaft is preferably formed of stainless steel. However, since stainless steel is generally poor in formability, in order to form a shaped material integrally having a hub part and a shaft part from a plate material as described above, a ferritic series having relatively excellent formability among stainless steels. It is preferable to use stainless steel. Furthermore, it is preferable to add 0.05% or more of Ti to ferritic stainless steel because ductility can be improved.

ハブ部は、例えば、軸部から外径に延びる円盤部と、円盤部から軸方向に延びる円筒部と、円筒部から外径に延びる鍔部とを有する形状とすることができる。上記のハブ一体軸によれば、ハブ部の肉厚を薄肉化した場合でも、具体的にはハブ部の円盤部の軸方向の肉厚を軸部の軸方向寸法の20%以下とした場合でも、優れた寸法精度で形成することができる。   For example, the hub portion may have a shape including a disk portion extending from the shaft portion to the outer diameter, a cylindrical portion extending from the disk portion in the axial direction, and a flange portion extending from the cylindrical portion to the outer diameter. According to the hub integrated shaft described above, even when the hub portion is thin, specifically, when the axial thickness of the disc portion of the hub portion is 20% or less of the axial dimension of the shaft portion. However, it can be formed with excellent dimensional accuracy.

上記のようなハブ一体軸は、ハブ部を薄肉化した場合でも、寸法精度を十分に高くすることができるため、特に、HDDのスピンドルモータ用として好適に使用することができる。   Since the hub integrated shaft as described above can sufficiently increase the dimensional accuracy even when the hub portion is thinned, it can be suitably used particularly for an HDD spindle motor.

上記のハブ一体軸と、ハブ一体軸の軸部が内周に挿入された軸受部材と、軸部の外周面と軸受部材の内周面との間のラジアル軸受隙間に生じる流体膜でハブ一体軸を回転自在に支持するラジアル軸受部とを備えた流体動圧軸受装置は、軸方向寸法の小型化を図ることができ、且つ、優れた回転精度を有することができる。   The hub is integrated with the hub integrated shaft, the bearing member in which the shaft portion of the hub integrated shaft is inserted into the inner periphery, and the fluid film generated in the radial bearing gap between the outer peripheral surface of the shaft portion and the inner peripheral surface of the bearing member. A fluid dynamic pressure bearing device including a radial bearing portion that rotatably supports a shaft can reduce the size in the axial direction and can have excellent rotational accuracy.

以上のように、本発明のハブ一体軸は、板材を塑性加工することで、薄型且つ軽量で寸法精度の高い素形材が得られる。さらに、成形材の軸部の外周面及びハブ部の回転体搭載面に研削仕上げを施すことで、これらの面の精度を特に高めることができる。   As described above, the hub-integrated shaft of the present invention can be formed into a thin, lightweight, and high-dimensional accuracy shaped material by plastic processing of the plate material. Furthermore, the precision of these surfaces can be raised especially by giving grinding finishing to the outer peripheral surface of the axial part of a molding material, and the rotary body mounting surface of a hub part.

HDDのスピンドルモータを示す断面図である。It is sectional drawing which shows the spindle motor of HDD. 上記スピンドルモータに組み込まれ、本発明の実施形態に係るハブ一体軸を備えた流体動圧軸受装置の断面図である。It is sectional drawing of the fluid dynamic pressure bearing apparatus provided with the hub integrated shaft which is integrated in the said spindle motor and concerns on embodiment of this invention. 上記流体動圧軸受装置の軸受スリーブの断面図である。It is sectional drawing of the bearing sleeve of the said fluid dynamic pressure bearing apparatus. 上記流体動圧軸受装置のハウジングの上面図である。It is a top view of the housing of the said fluid dynamic pressure bearing apparatus. (a)〜(e)は、板材を塑性加工して、軸部及びハブ部を一体に有する素形材を成形する工程を示す断面図である。(A)-(e) is sectional drawing which shows the process of plastically processing a board | plate material and shape | molding the raw material which has a shaft part and a hub part integrally. 素形材のハブ部に研削仕上げを施す様子を示す断面図である。It is sectional drawing which shows a mode that grinding finishing is performed to the hub part of a base material. 素形材の軸部に研削仕上げを施す様子を示す断面図である。It is sectional drawing which shows a mode that a grinding finish is given to the axial part of an original shape material. 他の実施形態に係るハブ一体軸を備えた流体動圧軸受装置の断面図である。It is sectional drawing of the fluid dynamic pressure bearing apparatus provided with the hub integrated shaft which concerns on other embodiment.

以下、本発明の実施形態を図面に基づいて説明する。   Hereinafter, embodiments of the present invention will be described with reference to the drawings.

図1に、例えば2.5インチHDDのディスク駆動装置に用いられるスピンドルモータを示す。このスピンドルモータは、本発明の一実施形態に係るハブ一体軸9を回転自在に支持する流体動圧軸受装置1と、流体動圧軸受装置1が取り付けられたブラケット6と、半径方向のギャップを介して対向させたステータコイル4およびロータマグネット5とを備えている。ステータコイル4はブラケット6に取り付けられ、ロータマグネット5はハブ一体軸9にヨーク10を介して取り付けられる。ハブ一体軸9には、回転体としてのディスクDが所定の枚数(図示例では1枚)保持される。ステータコイル4に通電すると、ステータコイル4とロータマグネット5との間の電磁力でロータマグネット5が回転し、これによりハブ一体軸9及びディスクDが一体となって回転する。   FIG. 1 shows a spindle motor used in, for example, a 2.5-inch HDD disk drive device. This spindle motor includes a fluid dynamic pressure bearing device 1 that rotatably supports a hub integrated shaft 9 according to an embodiment of the present invention, a bracket 6 to which the fluid dynamic pressure bearing device 1 is attached, and a radial gap. And a stator magnet 4 and a rotor magnet 5 which are opposed to each other. The stator coil 4 is attached to the bracket 6, and the rotor magnet 5 is attached to the hub integrated shaft 9 via the yoke 10. The hub integrated shaft 9 holds a predetermined number of disks D (one in the illustrated example) as a rotating body. When the stator coil 4 is energized, the rotor magnet 5 is rotated by electromagnetic force between the stator coil 4 and the rotor magnet 5, whereby the hub integrated shaft 9 and the disk D are rotated together.

流体動圧軸受装置1は、図2に示すように、軸部2及びハブ部3を有するハブ一体軸9と、ハブ一体軸9を回転自在に支持する軸受部材とで構成される。本実施形態では、軸受部材が、内周にハブ一体軸9の軸部2を挿入した軸受スリーブ8と、内周に軸受スリーブ8を保持する有底筒状のハウジング7とで構成される。軸部2の下端には、抜け止め部材11が設けられる。尚、以下では、説明の便宜上、軸方向でハウジング7の開口側を上側、閉塞側を下側とする。   As shown in FIG. 2, the fluid dynamic bearing device 1 includes a hub integrated shaft 9 having a shaft portion 2 and a hub portion 3, and a bearing member that rotatably supports the hub integrated shaft 9. In the present embodiment, the bearing member includes a bearing sleeve 8 in which the shaft portion 2 of the hub integrated shaft 9 is inserted on the inner periphery, and a bottomed cylindrical housing 7 that holds the bearing sleeve 8 on the inner periphery. A retaining member 11 is provided at the lower end of the shaft portion 2. In the following, for convenience of explanation, the opening side of the housing 7 in the axial direction is the upper side and the closing side is the lower side.

ハブ一体軸9は、金属で形成され、例えば鉄系金属、特にステンレス鋼で形成される。ステンレス鋼は一般に延性が乏しいため、ステンレス鋼の中でも比較的延性に富んだフェライト系(例えば、SUS430)を使用することが好ましい。また、延性を高めるために、ステンレス鋼のCの含有量を0.2%以下とすることが好ましく、同じ目的でステンレス鋼にTiを重量比で0.05%以上配合することが好ましい。この他、例えば一般構造用鋼、アルミ合金、あるいはチタン合金等でハブ一体軸9を形成することもできる。   The hub integrated shaft 9 is made of metal, for example, iron-based metal, particularly stainless steel. Since stainless steel generally has poor ductility, it is preferable to use a ferritic material (for example, SUS430) that is relatively rich in ductility among stainless steels. Moreover, in order to improve ductility, it is preferable to make content of C of stainless steel 0.2% or less, and it is preferable to mix | blend Ti 0.05% or more by weight ratio with stainless steel for the same purpose. In addition, the hub integrated shaft 9 can be formed of, for example, general structural steel, aluminum alloy, titanium alloy, or the like.

軸部2は、ハブ一体軸9の軸心に設けられ、外径が2〜4mm程度に設定される。軸部2は、凹凸の無いストレートな円筒面状の外周面2aと、軸心に設けられた軸方向穴2bとを有する。本実施形態では、軸方向穴2bが軸部2を軸方向に貫通し、その内周面にネジ溝が形成されている。軸部2の下端部には、抜け止め部材11が設けられる。抜け止め部材11は、軸部2の下端部から外径に突出した円盤部11aと、円盤部11aの軸心から上方に延びた雄ネジ部11bとを有する。雄ネジ部11bは、軸部2の軸方向穴2bの下端にネジ固定される。円盤部11aは、軸受スリーブ8の下側端面8bとハウジング7の底部7bの上側端面7b1との軸方向間に配される。抜け止め部材11の円盤部11aと軸受スリーブ8の下側端面8bとが軸方向で係合することにより、軸部2の軸受スリーブ8からの抜け止めが行われる。   The shaft portion 2 is provided at the axis of the hub integrated shaft 9 and has an outer diameter of about 2 to 4 mm. The shaft portion 2 has a straight cylindrical outer peripheral surface 2a having no irregularities and an axial hole 2b provided in the shaft center. In the present embodiment, the axial hole 2b penetrates the shaft portion 2 in the axial direction, and a thread groove is formed on the inner peripheral surface thereof. A retaining member 11 is provided at the lower end of the shaft portion 2. The retaining member 11 includes a disk portion 11a that protrudes from the lower end portion of the shaft portion 2 to the outer diameter, and a male screw portion 11b that extends upward from the axis of the disk portion 11a. The male screw portion 11 b is screwed to the lower end of the axial hole 2 b of the shaft portion 2. The disk portion 11 a is arranged between the lower end surface 8 b of the bearing sleeve 8 and the upper end surface 7 b 1 of the bottom portion 7 b of the housing 7 in the axial direction. The disk portion 11a of the retaining member 11 and the lower end surface 8b of the bearing sleeve 8 are engaged in the axial direction, so that the shaft portion 2 is prevented from being detached from the bearing sleeve 8.

軸部2の外周面2aには、表面硬化処理又はコーティング処理、あるいはこれらの双方が施される。表面硬化処理としては、例えば真空焼入れ、真空浸炭処理、真空窒化処理、ガス軟窒化処理、あるいはイオン窒化処理等による表面硬化処理が挙げられる。コーティング処理としては、例えば無電解Niめっき、DLC、TiN、TiAlN、あるいはTiCによるコーティング処理が挙げられる。尚、ハブ一体軸9をステンレス鋼で形成する場合、上記のようにCの含有量を0.2%以下とすると、焼入れによる硬化処理が困難となるため、真空焼入れ以外の表面効果処理、あるいはコーティング処理を施すことが好ましい。尚、表面処理やコーティング処理は、軸部2の外周面2aだけでなく、他の領域、例えばスラスト軸受隙間に面するハブ部3の円盤部3aの下側端面3a1に施しても良い。あるいは、軸部2の外周面2aの耐摩耗性が十分であれば、表面効果処理やコーティング処理を省略してもよい。   The outer peripheral surface 2a of the shaft portion 2 is subjected to surface hardening treatment or coating treatment, or both. Examples of the surface hardening treatment include surface hardening treatment such as vacuum quenching, vacuum carburizing treatment, vacuum nitriding treatment, gas soft nitriding treatment, or ion nitriding treatment. Examples of the coating process include a coating process using electroless Ni plating, DLC, TiN, TiAlN, or TiC. When the hub integrated shaft 9 is formed of stainless steel, if the C content is 0.2% or less as described above, the hardening process by quenching becomes difficult, so surface effect treatment other than vacuum quenching, or A coating treatment is preferably performed. The surface treatment and the coating treatment may be performed not only on the outer peripheral surface 2a of the shaft portion 2, but also on other regions, for example, the lower end surface 3a1 of the disk portion 3a of the hub portion 3 facing the thrust bearing gap. Alternatively, if the wear resistance of the outer peripheral surface 2a of the shaft portion 2 is sufficient, the surface effect treatment or the coating treatment may be omitted.

ハブ部3は、軸部2の上端部から外径に延び、軸方向と直交する回転体搭載面(本実施形態ではディスク搭載面3d)を備えている。本実施形態のハブ部3は、ハウジング7の開口部を覆う円盤部3aと、円盤部3aの外周部から軸方向下方に延びた円筒部3bと、円筒部3bの下端部からさらに外径に延びた鍔部3cとで構成され、鍔部3cの上側端面にディスク搭載面3dが形成される。円筒部3bの外周面には、ディスク嵌合面3eが形成される。ディスクDをディスク嵌合面3eの外周に嵌合すると共に、ディスク搭載面3dの上に載置し、この状態で図示しないクランパによってディスクDの上面を押さえてディスク搭載面3d上に押し付けることにより、ディスクDがハブ部3に保持される。尚、軸部2の軸方向穴2bの上部は、クランパを固定するためのネジ穴として機能する。   The hub portion 3 includes a rotating body mounting surface (disk mounting surface 3d in the present embodiment) that extends from the upper end of the shaft portion 2 to the outer diameter and is orthogonal to the axial direction. The hub portion 3 of the present embodiment includes a disc portion 3a that covers the opening of the housing 7, a cylindrical portion 3b that extends downward in the axial direction from the outer peripheral portion of the disc portion 3a, and a further outer diameter from the lower end portion of the cylindrical portion 3b. The disc mounting surface 3d is formed on the upper end surface of the flange portion 3c. A disk fitting surface 3e is formed on the outer peripheral surface of the cylindrical portion 3b. The disc D is fitted on the outer periphery of the disc fitting surface 3e and placed on the disc mounting surface 3d. In this state, the upper surface of the disc D is pressed by the clamper (not shown) and pressed onto the disc mounting surface 3d. The disk D is held by the hub portion 3. In addition, the upper part of the axial direction hole 2b of the axial part 2 functions as a screw hole for fixing a clamper.

ハブ一体軸9は、詳細は後述するが、金属の板材の塑性加工で軸部2及びハブ部3を一体に有する素形材を形成し、この素形材の所定箇所に研削仕上げを施すことにより形成される。本実施形態では、潤滑油で満たされたラジアル軸受隙間に面する軸部2の外周面2aと、潤滑油で満たされたスラスト軸受隙間に面するハブ部3の円盤部3aの下側端面3a1と、ハブ部3のディスク搭載面3d及びディスク嵌合面3eとに研削仕上げが施される。軸部2の外周面2a及び円盤部3aの下側端面3a1は、ハブ部3の研削仕上げ面(ディスク搭載面3d及びディスク嵌合面3e)を基準として、研削仕上げが施されている。その結果、軸部2の外周面2aに対するディスク搭載面3dの振れ精度は5μm以下に設定され、軸部2の外周面2aに対するディスク嵌合面3eの同軸度は5μm以下に設定される。換言すれば、軸部2の外周面2aに対するディスク搭載面3d及びディスク嵌合面3eの寸法精度が上記の範囲内であれば、軸部2の外周面2aが、ディスク搭載面3d及びディスク嵌合面3eを基準として研削仕上げされていると推定することができる。   As will be described in detail later, the hub-integrated shaft 9 is formed by forming a shape material integrally having the shaft portion 2 and the hub portion 3 by plastic working of a metal plate material, and grinding a predetermined portion of the shape material. It is formed by. In the present embodiment, the outer peripheral surface 2a of the shaft portion 2 facing the radial bearing gap filled with lubricating oil and the lower end surface 3a1 of the disk portion 3a of the hub portion 3 facing the thrust bearing gap filled with lubricating oil. Then, the disc mounting surface 3d and the disc fitting surface 3e of the hub portion 3 are ground. The outer peripheral surface 2a of the shaft portion 2 and the lower end surface 3a1 of the disc portion 3a are ground with reference to the ground finish surface (the disc mounting surface 3d and the disc fitting surface 3e) of the hub portion 3. As a result, the deflection accuracy of the disc mounting surface 3d with respect to the outer peripheral surface 2a of the shaft portion 2 is set to 5 μm or less, and the coaxiality of the disc fitting surface 3e with respect to the outer peripheral surface 2a of the shaft portion 2 is set to 5 μm or less. In other words, if the dimensional accuracy of the disc mounting surface 3d and the disc fitting surface 3e with respect to the outer peripheral surface 2a of the shaft portion 2 is within the above range, the outer peripheral surface 2a of the shaft portion 2 is connected to the disc mounting surface 3d and the disc fitting surface. It can be estimated that the ground surface 3e is ground.

軸受スリーブ8は、金属材料で円筒状に形成され、本実施形態では、例えば銅を主成分とする焼結金属で形成される。軸受スリーブ8の内周面8aには、例えば図3に示すように、軸方向に離隔した2つの領域に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。図中に網掛けで示す領域は、動圧溝8a1,8a2の間に形成された丘部であり、動圧溝8a1,8a2よりも一段高くなっている(すなわち内径向きに突出している)。図示例では、上側の動圧溝8a1は軸方向非対称に形成されており、具体的には、軸方向中央部mより上側の領域の軸方向寸法X1が、下側の領域の軸方向寸法X2よりも大きくなっている(X1>X2)。下側の動圧溝8a2は軸方向対称に形成されている。軸受スリーブ8の外周面8dには、軸方向溝8d1が軸方向全長にわたって形成され、例えば3本の軸方向溝8d1が円周方向に等配される。   The bearing sleeve 8 is formed of a metal material in a cylindrical shape, and in this embodiment, is formed of, for example, a sintered metal containing copper as a main component. For example, as shown in FIG. 3, herringbone-shaped dynamic pressure grooves 8 a 1 and 8 a 2 are formed on the inner peripheral surface 8 a of the bearing sleeve 8 in two regions separated in the axial direction. A region indicated by hatching in the figure is a hill formed between the dynamic pressure grooves 8a1 and 8a2, and is one step higher than the dynamic pressure grooves 8a1 and 8a2 (that is, protrudes toward the inner diameter). In the illustrated example, the upper dynamic pressure groove 8a1 is formed asymmetrically in the axial direction. Specifically, the axial dimension X1 of the region above the axial center part m is the axial dimension X2 of the lower region. (X1> X2). The lower dynamic pressure groove 8a2 is formed symmetrically in the axial direction. An axial groove 8d1 is formed over the entire length in the axial direction on the outer peripheral surface 8d of the bearing sleeve 8. For example, three axial grooves 8d1 are equally arranged in the circumferential direction.

ハウジング7は、例えば樹脂の射出成形で形成され、図2に示すように、側部7a及び底部7bを一体に有する有底円筒状に形成される。側部7aの円筒状内周面7a1には、軸受スリーブ8の外周面8dが隙間接着、圧入、接着剤介在下の圧入等により固定される。ハウジング7の側部7aの上端面7a2は、例えば図4に示すように複数の動圧溝7a20をスパイラル形状に配列した領域が形成される。ハウジング7の側部7aの外周の上端には、図2に示すように、上方に向かって漸次拡径するテーパ状のシール面7a3が形成される。このテーパ状のシール面7a3は、ハブ部3の円筒部3bの内周面3b1との間に、上方に向けて半径方向寸法が漸次縮小した環状のシール空間Sを形成する。シール空間Sは、ハブ一体軸9の回転時、スラスト軸受部Tのスラスト軸受隙間の外径側と連通している。このシール空間Sの毛細管力により、ハウジング7の内部に充満された潤滑油の漏れ出しを防止する。   The housing 7 is formed by, for example, resin injection molding, and is formed in a bottomed cylindrical shape integrally having a side portion 7a and a bottom portion 7b as shown in FIG. The outer peripheral surface 8d of the bearing sleeve 8 is fixed to the cylindrical inner peripheral surface 7a1 of the side portion 7a by gap bonding, press-fitting, press-fitting with an adhesive interposed therebetween, or the like. On the upper end surface 7a2 of the side portion 7a of the housing 7, for example, a region in which a plurality of dynamic pressure grooves 7a20 are arranged in a spiral shape is formed as shown in FIG. At the upper end of the outer periphery of the side portion 7a of the housing 7, as shown in FIG. 2, a tapered seal surface 7a3 that gradually increases in diameter upward is formed. This tapered seal surface 7a3 forms an annular seal space S whose radial dimension is gradually reduced upward with respect to the inner peripheral surface 3b1 of the cylindrical portion 3b of the hub portion 3. The seal space S communicates with the outer diameter side of the thrust bearing gap of the thrust bearing portion T when the hub integrated shaft 9 rotates. The capillary force of the seal space S prevents the lubricating oil filled in the housing 7 from leaking out.

上記構成のハブ一体軸9、軸受スリーブ8、ハウジング7、及び抜け止め部材11を組み付けた状態で、軸受スリーブ8の内部気孔を含めたハウジング7の内部の空間に潤滑油を充満させることにより、図2に示す流体動圧軸受装置1が完成する。このとき、潤滑油の油面はシール空間Sの内部に保持される。   By filling the space inside the housing 7 including the internal pores of the bearing sleeve 8 with the hub integrated shaft 9, the bearing sleeve 8, the housing 7, and the retaining member 11 assembled as described above, The fluid dynamic bearing device 1 shown in FIG. 2 is completed. At this time, the oil level of the lubricating oil is held inside the seal space S.

ハブ一体軸9が回転すると、軸受スリーブ8の内周面8aと軸部2の外周面2aとの間にラジアル軸受隙間が形成される。そして、動圧溝8a1,8a2により上記ラジアル軸受隙間に満たされた潤滑油の圧力が高められ、この圧力(動圧作用)によりハブ一体軸9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R1,R2が構成される。   When the hub integrated shaft 9 rotates, a radial bearing gap is formed between the inner peripheral surface 8 a of the bearing sleeve 8 and the outer peripheral surface 2 a of the shaft portion 2. Then, the pressure of the lubricating oil filled in the radial bearing gap is increased by the dynamic pressure grooves 8a1 and 8a2, and the radial bearing that supports the hub integrated shaft 9 rotatably in the radial direction by this pressure (dynamic pressure action). Portions R1 and R2 are configured.

これと同時に、ハブ部3の円盤部3aの下側端面3a1とハウジング7の側部7aの上端面7a2との間にスラスト軸受隙間が形成される。そして、動圧溝7a20により上記スラスト軸受隙間に満たされた潤滑油の圧力が高められ、この圧力(動圧作用)によりハブ一体軸9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Tが構成される。   At the same time, a thrust bearing gap is formed between the lower end surface 3 a 1 of the disk portion 3 a of the hub portion 3 and the upper end surface 7 a 2 of the side portion 7 a of the housing 7. Then, the pressure of the lubricating oil filled in the thrust bearing gap is increased by the dynamic pressure groove 7a20, and the thrust bearing portion T for supporting the hub integrated shaft 9 rotatably in the thrust direction in a non-contact manner by this pressure (dynamic pressure action). Is configured.

このとき、軸受スリーブ8の外周面8dに形成された軸方向溝8d1により、潤滑油が流通可能な連通路が形成される。この連通路により、ハウジング7の内部に満たされた潤滑油に局部的な負圧が発生する事態を防止できる。特に本実施形態では、図3に示すように、軸受スリーブ8の内周面8aに形成された上側の動圧溝8a1が軸方向非対称な形状に形成されているため、ハブ一体軸9の回転に伴ってラジアル軸受隙間の潤滑油が下方に押し込まれ、上記の連通路を介して潤滑油が循環し、これにより局部的な負圧の発生を確実に防止できる。   At this time, the axial groove 8d1 formed in the outer peripheral surface 8d of the bearing sleeve 8 forms a communication path through which lubricating oil can flow. This communication path can prevent a local negative pressure from being generated in the lubricating oil filled in the housing 7. In particular, in the present embodiment, as shown in FIG. 3, the upper dynamic pressure groove 8a1 formed in the inner peripheral surface 8a of the bearing sleeve 8 is formed in an axially asymmetric shape, so that the rotation of the hub integrated shaft 9 is performed. Along with this, the lubricating oil in the radial bearing gap is pushed downward, and the lubricating oil circulates through the communication path, thereby reliably preventing the generation of local negative pressure.

以下、ハブ一体軸9の製造方法について説明する。   Hereinafter, a method for manufacturing the hub integrated shaft 9 will be described.

ハブ一体軸9は、板材を塑性加工して軸部2及びハブ部3を一体に有する素形材を形成する素形材成形工程と、この素形材の所定箇所に研削仕上げを施す研削仕上げ工程とを経て形成される。   The hub-integrated shaft 9 is formed by molding a plate material to form a shaped material integrally having the shaft portion 2 and the hub portion 3, and a grinding finish for grinding a predetermined portion of the shaped material. It is formed through a process.

(1)素形材成形工程
素形材形成工程では、まず、図5(a)に示すように、金属(例えば、Tiを0.5%以上含んだフェライト系ステンレス鋼)の板材20を準備する。例えば、本実施形態のような2.5インチHDDのスピンドルモータ用のハブ一体軸9の場合、板材の厚さは1mm程度とされる。
(1) Shaped Material Forming Process In the shaped material forming process, first, as shown in FIG. 5 (a), a metal (for example, ferritic stainless steel containing 0.5% or more of Ti) plate material 20 is prepared. To do. For example, in the case of the hub integrated shaft 9 for the spindle motor of the 2.5 inch HDD as in this embodiment, the thickness of the plate material is about 1 mm.

そして、図5(b)に示すように、冷間の塑性加工(深絞り加工)により板材20の軸心を下方に突出させ、軸部21を成形する。このとき、図示しない金型で軸部21を押し込んで突出させるため、軸部21の軸心には軸方向穴21aが成形される。   And as shown in FIG.5 (b), the axial center of the board | plate material 20 is protruded below by cold plastic working (deep drawing process), and the axial part 21 is shape | molded. At this time, an axial hole 21 a is formed in the shaft center of the shaft portion 21 in order to push the shaft portion 21 to protrude by a mold (not shown).

次に、図5(c)に示すように、冷間の塑性加工(プレス加工)により軸部21の周囲にハブ部22を成形する。具体的には、軸部21から外径に延びる円盤部22aと、円盤部22aの外径端から下方に延びる円筒部22bと、円筒部22bの下端から外径に延びる鍔部22cとが成形される。このとき、鍔部22cの上側端面22c1の内径端には、環状の凹部(逃げ部)22c10が同時に成形される。   Next, as shown in FIG.5 (c), the hub part 22 is shape | molded around the axial part 21 by cold plastic working (press work). Specifically, a disk part 22a extending from the shaft part 21 to the outer diameter, a cylindrical part 22b extending downward from the outer diameter end of the disk part 22a, and a flange part 22c extending from the lower end of the cylindrical part 22b to the outer diameter are formed. Is done. At this time, an annular recess (relief portion) 22c10 is simultaneously formed at the inner diameter end of the upper end surface 22c1 of the flange portion 22c.

その後、図5(d)に示すように、軸部21の先端部(下端部)を切断除去し、軸方向穴21aを軸部21の下端に開口させる。これと共に、軸部21の軸方向穴21aの内周面にネジ溝を形成する。   Thereafter, as shown in FIG. 5 (d), the tip end portion (lower end portion) of the shaft portion 21 is cut off and the axial hole 21 a is opened at the lower end of the shaft portion 21. At the same time, a thread groove is formed on the inner peripheral surface of the axial hole 21 a of the shaft portion 21.

最後に、図5(e)に示すように、ハブ部22の鍔部22cと板材20とを切り離し、軸部21及びハブ部22を有する素形材30を板材20から分離する。   Finally, as shown in FIG. 5 (e), the flange portion 22 c of the hub portion 22 and the plate material 20 are separated, and the base material 30 having the shaft portion 21 and the hub portion 22 is separated from the plate material 20.

このように素形材30を板材20から形成することで、素形材30の肉厚はおおよそ均一になっている。具体的には、軸部21の径方向の肉厚、ハブ部22の円盤部22aの軸方向の肉厚、円筒部22bの径方向の肉厚、及び、鍔部22cの軸方向の肉厚が、おおよそ均一になっている。詳しくは、上記の塑性加工により絞られて軸方向に延びる箇所(軸部21及び円筒部22b)の肉厚は、軸方向と直交する方向の面(円盤部22a及び鍔部22c)の肉厚よりも若干薄くなっている。例えば、1mm程度の板材20を用いて素形材30を形成する場合、円盤部22a及び鍔部22cの肉厚が約0.8mmであるのに対し、軸部21及び円筒部22bの肉厚は約0.5mmとなる。すなわち、本実施形態では、板材20から素形材30を得るときの肉厚の変化量が50%以下となっている。このように、板材20からの変形量が比較的小さいことで、素形材30を精度良く塑性加工することができる。   By forming the base material 30 from the plate material 20 in this way, the thickness of the base material 30 is approximately uniform. Specifically, the radial thickness of the shaft portion 21, the axial thickness of the disk portion 22a of the hub portion 22, the radial thickness of the cylindrical portion 22b, and the axial thickness of the flange portion 22c. However, it is almost uniform. Specifically, the thickness of the portion (the shaft portion 21 and the cylindrical portion 22b) that is squeezed by the plastic processing and extends in the axial direction is the thickness of the surface (the disk portion 22a and the flange portion 22c) in the direction orthogonal to the axial direction. Is slightly thinner. For example, when the base material 30 is formed using the plate material 20 of about 1 mm, the thickness of the disk portion 22a and the flange portion 22c is about 0.8 mm, whereas the thickness of the shaft portion 21 and the cylindrical portion 22b. Is about 0.5 mm. That is, in the present embodiment, the amount of change in thickness when the base material 30 is obtained from the plate material 20 is 50% or less. Thus, since the deformation amount from the plate material 20 is relatively small, the base material 30 can be plastically processed with high accuracy.

(2)研削仕上げ工程
上記のようにして成形した素形材30の所定箇所に、研削仕上げが施される。尚、図6及び図7に示す研削仕上げ工程では、素形材30の軸方向を水平にして加工を行っているが、素形材30の各部位には上記と同様の名称を付している。
(2) Grinding finishing process Grinding finishing is performed on a predetermined portion of the shaped material 30 formed as described above. In the grinding finishing process shown in FIG. 6 and FIG. 7, the machining is performed with the axial direction of the shaped material 30 being horizontal, and the same name as above is given to each part of the shaped material 30. Yes.

まず、素形材30のハブ部22の所定箇所に研削仕上げが施される。具体的には、図6に示すように、素形材30の軸部21の軸方向穴21aに回転センタ41、42を装着して素形材30を回転自在に支持すると共に、ハブ部22の鍔部22cの下側端面22c2をバッキングプレート43で支持する。そして、バッキングプレート43を回転駆動して素形材30を軸部21を中心に回転させ、この状態でアンギュラ砥石44を素形材30に接触させる。詳しくは、アンギュラ砥石44を、鍔部22cの上側端面22c1(ディスク搭載面に相当)、円筒部22bの外周面22b1(ディスク嵌合面に相当)、及び、円盤部22aの上側端面22a1の外周部に同時に当接させ、これらの面を同時研削する。このとき、鍔部22cの上側端面22c1の内径端に逃げ部22c10が設けられているため、アンギュラ砥石44を、鍔部22cの上側端面22c1及び円筒部22bの外周面22b1に密着させることができる。   First, a grinding finish is applied to a predetermined portion of the hub portion 22 of the raw material 30. Specifically, as shown in FIG. 6, rotation centers 41 and 42 are attached to the axial holes 21 a of the shaft portion 21 of the shaped material 30 to rotatably support the shaped material 30, and the hub portion 22. The lower end surface 22c2 of the collar portion 22c is supported by the backing plate 43. Then, the backing plate 43 is rotationally driven to rotate the base material 30 around the shaft portion 21, and the angular grindstone 44 is brought into contact with the base material 30 in this state. Specifically, the angular grindstone 44 is made up of the upper end surface 22c1 (corresponding to the disc mounting surface) of the flange portion 22c, the outer peripheral surface 22b1 (corresponding to the disc fitting surface) of the cylindrical portion 22b, and the outer periphery of the upper end surface 22a1 of the disc portion 22a. At the same time, these surfaces are ground simultaneously. At this time, since the escape portion 22c10 is provided at the inner diameter end of the upper end surface 22c1 of the flange portion 22c, the angular grindstone 44 can be brought into close contact with the upper end surface 22c1 of the flange portion 22c and the outer peripheral surface 22b1 of the cylindrical portion 22b. .

次に、図7に示すように、ハブ部22の研削仕上げ面(図中に点線で示す)を基準として、軸部21の外周面21bと、ハブ部22の円盤部22aの下側端面22a2の外周部(スラスト軸受隙間に面する領域)とに研削仕上げを施す。例えば、ハブ部22の円盤部22aの上側端面22a1の外周部をマグネットチャック51で吸着支持すると共に、円筒部22bの外周面22b1をシュー52で摺動支持する。この状態で、マグネットチャック51を回転駆動して素形材30を軸部21を中心に回転させ、軸部21の外周面21bに砥石53を当接させると共に、円盤部22aの下側端面22a2の外周部に砥石54を当接させ、これらの面を研削する。   Next, as shown in FIG. 7, the outer peripheral surface 21 b of the shaft portion 21 and the lower end surface 22 a 2 of the disc portion 22 a of the hub portion 22 with reference to the ground finish surface of the hub portion 22 (shown by a dotted line in the drawing). The outer peripheral portion (region facing the thrust bearing gap) is ground. For example, the outer peripheral portion of the upper end surface 22 a 1 of the disk portion 22 a of the hub portion 22 is attracted and supported by the magnet chuck 51, and the outer peripheral surface 22 b 1 of the cylindrical portion 22 b is slidably supported by the shoe 52. In this state, the magnet chuck 51 is rotationally driven to rotate the shaped member 30 around the shaft portion 21 so that the grindstone 53 is brought into contact with the outer peripheral surface 21b of the shaft portion 21 and the lower end surface 22a2 of the disk portion 22a. The grindstone 54 is brought into contact with the outer peripheral portion of the steel plate, and these surfaces are ground.

このように、高精度に加工されたハブ部22の研削仕上げ面を基準として、軸部21の外周面21bに研削仕上げを施すことで、この面を高精度に加工することができる。特に、ディスク搭載面3dに相当する鍔部22cの上側端面22c1を基準として、軸部21の外周面21bを研削することで、これらの面の相対的な面精度(例えば振れ精度)を高精度に設定することができる。本実施形態では、軸部21の外周面21bを研削する際に、鍔部22cの上側端面22c1を直接支持するのではなく、円盤部22aの上側端面22a1の外周部をマグネットチャック51で支持している(図7参照)。円盤部22aの上側端面22a1の外周部と、鍔部22cの上側端面22c1とは同時研削されているため、これらの面の平行度は極めて高精度に設定される。従って、図7に示すように円盤部22aの上側端面22a1の外周部をマグネットチャック51で支持することで、鍔部22cの上側端面22c1を間接的に基準とすることができる。もちろん、可能であれば、鍔部22cの上側端面22c1をマグネットチャック51で吸着支持し、この面を直接的に基準としてもよい。   Thus, by grinding the outer peripheral surface 21b of the shaft portion 21 with reference to the ground finish surface of the hub portion 22 processed with high accuracy, this surface can be processed with high accuracy. In particular, by grinding the outer peripheral surface 21b of the shaft portion 21 with reference to the upper end surface 22c1 of the flange portion 22c corresponding to the disk mounting surface 3d, the relative surface accuracy (for example, runout accuracy) of these surfaces is high. Can be set to In the present embodiment, when the outer peripheral surface 21b of the shaft portion 21 is ground, the upper end surface 22c1 of the flange portion 22c is not directly supported, but the outer peripheral portion of the upper end surface 22a1 of the disk portion 22a is supported by the magnet chuck 51. (See FIG. 7). Since the outer peripheral portion of the upper end surface 22a1 of the disk portion 22a and the upper end surface 22c1 of the flange portion 22c are ground simultaneously, the parallelism of these surfaces is set with extremely high accuracy. Therefore, as shown in FIG. 7, by supporting the outer peripheral portion of the upper end surface 22a1 of the disk portion 22a with the magnet chuck 51, the upper end surface 22c1 of the flange portion 22c can be indirectly used as a reference. Of course, if possible, the upper end surface 22c1 of the flange 22c may be attracted and supported by the magnet chuck 51, and this surface may be directly used as a reference.

また、ディスク嵌合面3eに相当する円筒部22bの外周面22b1をシュー52で支持することで、この面を基準として軸部21の外周面21bを研削することができるため、これらの面の相対的な面精度(例えば同軸度)を高精度に設定することができる。   Further, since the outer peripheral surface 22b1 of the cylindrical portion 22b corresponding to the disc fitting surface 3e is supported by the shoe 52, the outer peripheral surface 21b of the shaft portion 21 can be ground on the basis of this surface. Relative surface accuracy (for example, coaxiality) can be set with high accuracy.

以上のように、素形材30の所定箇所に研削仕上げを施すことにより、軸部2及びハブ部3を有するハブ一体軸9(図2参照)が形成される。このハブ一体軸9の軸部2の外周面2aに、必要に応じて表面硬化処理あるいはコーティング処理が施される。尚、表面硬化処理あるいはコーティング処理を、上記の研削仕上げ工程に先立って行えば、研削による疵を抑えることができる。また、上記の研削仕上げ工程の後にコーティング処理を施せば、研削による疵をコーティングで覆うことができる。また、表面硬化処理及びコーティング処理の双方を施してもよく、例えば軸部2の外周面2aに表面硬化処理を施した後、上記の研削仕上げ工程を行い、さらにこの面にコーティング処理を施してもよい。   As described above, the hub integrated shaft 9 (see FIG. 2) having the shaft portion 2 and the hub portion 3 is formed by performing grinding finishing on a predetermined portion of the shaped member 30. The outer peripheral surface 2a of the shaft portion 2 of the hub integrated shaft 9 is subjected to surface hardening treatment or coating treatment as necessary. Note that if surface hardening treatment or coating treatment is performed prior to the above-described grinding finishing step, wrinkles due to grinding can be suppressed. Moreover, if a coating process is performed after said grinding finishing process, the grinding | polishing wrinkles can be covered with a coating. Further, both surface hardening treatment and coating treatment may be performed. For example, after the surface hardening treatment is performed on the outer peripheral surface 2a of the shaft portion 2, the above-described grinding finishing process is performed, and further this surface is coated. Also good.

本発明は、上記の実施形態に限られない。以下、本発明の他の実施形態を説明するが、上記の実施形態と同様の機能を有する箇所には同一の符号を付して重複説明を省略する。   The present invention is not limited to the above embodiment. Hereinafter, although other embodiment of this invention is described, the same code | symbol is attached | subjected to the location which has the same function as said embodiment, and duplication description is abbreviate | omitted.

上記の実施形態では、図6及び図7に示すように、素形材30のハブ部22のディスク搭載面(鍔部22cの上側端面22c1)及びディスク嵌合面(円筒部22bの外周面22b1)に研削仕上げを施し、これらの面を基準として軸部21の外周面21bに研削仕上げを施しているが、これに限られない。例えば、研削仕上げを施したディスク搭載面のみを基準として、軸部21の外周面21bに研削仕上げを施してもよい。   In the above embodiment, as shown in FIGS. 6 and 7, the disk mounting surface (the upper end surface 22c1 of the flange portion 22c) of the hub portion 22 and the disk fitting surface (the outer peripheral surface 22b1 of the cylindrical portion 22b) of the shaped member 30. ), And the outer peripheral surface 21b of the shaft portion 21 is ground with reference to these surfaces. However, the present invention is not limited to this. For example, the outer peripheral surface 21b of the shaft portion 21 may be ground with reference to only the disk mounting surface that has been ground.

また、流体動圧軸受装置1の構成は上記に限られない。例えば、図8に示す流体動圧軸受装置1は、軸部2に設けられた軸方向穴2bの下端を閉じ、軸部2の下端の抜け止め部を省略した点で、上記の実施形態と異なる。このように、軸部2の下端の抜け止め部を省略することで、流体動圧軸受装置1の軸方向寸法が縮小され、スピンドルモータのさらなる薄型化が可能となる。この実施形態では、抜け止め部材11はハウジング7の外部に設けられる。具体的には、ハブ部3の円筒部3bの下端に環状の抜け止め部材11を固定している。この抜け止め部材11が、ハウジング7のテーパ状シール面7a3の下方に設けられた肩面7a4と軸方向で係合することにより、軸部2の軸受スリーブ8からの抜け止めが行われる。   The configuration of the fluid dynamic bearing device 1 is not limited to the above. For example, the fluid dynamic bearing device 1 shown in FIG. 8 is the same as the above embodiment in that the lower end of the axial hole 2b provided in the shaft portion 2 is closed and the retaining portion at the lower end of the shaft portion 2 is omitted. Different. Thus, by omitting the retaining portion at the lower end of the shaft portion 2, the axial dimension of the fluid dynamic bearing device 1 is reduced, and the spindle motor can be further reduced in thickness. In this embodiment, the retaining member 11 is provided outside the housing 7. Specifically, an annular retaining member 11 is fixed to the lower end of the cylindrical portion 3 b of the hub portion 3. The retaining member 11 is engaged with a shoulder surface 7a4 provided below the tapered seal surface 7a3 of the housing 7 in the axial direction, so that the shaft portion 2 is prevented from being detached from the bearing sleeve 8.

また、上記の実施形態では、ハブ部3の円盤部3aの下側端面3a1がスラスト軸受隙間に面しているが、この面がスラスト軸受隙間に面さない構成としてもよい。この場合、ハブ部3の下側端面3a1の研削仕上げを省略してもよい。   In the above-described embodiment, the lower end surface 3a1 of the disk portion 3a of the hub portion 3 faces the thrust bearing gap. However, the surface may not face the thrust bearing gap. In this case, the grinding finish of the lower end surface 3a1 of the hub portion 3 may be omitted.

また、上記の実施形態では、ハウジング7の外周面とハブ部3の内周面3b1との間にシール空間Sを形成しているが、シール空間Sの場所はこれに限られない。例えば、図示は省略するが、ハウジングの内周面の上端部にシール部材を固定し、このシール部材の内周面と軸部の外周面との間にシール空間を形成することもできる。   In the above embodiment, the seal space S is formed between the outer peripheral surface of the housing 7 and the inner peripheral surface 3b1 of the hub portion 3, but the location of the seal space S is not limited to this. For example, although not shown, a seal member can be fixed to the upper end portion of the inner peripheral surface of the housing, and a seal space can be formed between the inner peripheral surface of the seal member and the outer peripheral surface of the shaft portion.

また、上記の実施形態では、潤滑流体が潤滑油である場合を示しているが、これに限らず、例えば磁性流体や空気等の流体を使用することも可能である。   In the above embodiment, the lubricating fluid is a lubricating oil. However, the present invention is not limited to this. For example, a fluid such as a magnetic fluid or air can be used.

また、上記の実施形態では、本発明に係るハブ一体軸9をHDDのスピンドルモータ用の流体動圧軸受装置に組み込んだ例を示しているが、これに限られない。例えば、ポリゴンスキャナモータ用の流体動圧軸受装置や、カラーホイールモータ用の流体動圧軸受装置に本発明のハブ一体軸を適用することもできる。   In the above embodiment, an example in which the hub integrated shaft 9 according to the present invention is incorporated in a fluid dynamic bearing device for an HDD spindle motor is shown, but the present invention is not limited to this. For example, the hub integrated shaft of the present invention can be applied to a fluid dynamic pressure bearing device for a polygon scanner motor or a fluid dynamic pressure bearing device for a color wheel motor.

1 流体動圧軸受装置
2 軸部
2a 外周面
2b 軸方向穴
3 ハブ部
3a 円盤部
3b 円筒部
3c 鍔部
3d ディスク搭載面
3e ディスク嵌合面
4 ステータコイル
5 ロータマグネット
6 ブラケット
7 ハウジング
8 軸受スリーブ
9 ハブ一体軸
10 ヨーク
11 抜け止め部材
20 板材
21 軸部
22 ハブ部
22a 円盤部
22b 円筒部
22c 鍔部
30 素形材
31 軸部
32 ハブ部
41 回転センタ
43 バッキングプレート
44 アンギュラ砥石
51 マグネットチャック
52 シュー
53 砥石
54 砥石
D ディスク
R1,R2 ラジアル軸受部
S シール空間
T スラスト軸受部
DESCRIPTION OF SYMBOLS 1 Fluid dynamic pressure bearing apparatus 2 Shaft part 2a Outer peripheral surface 2b Axial hole 3 Hub part 3a Disk part 3b Cylindrical part 3c Eaves part 3d Disk mounting surface 3e Disk fitting surface 4 Stator coil 5 Rotor magnet 6 Bracket 7 Housing 8 Bearing sleeve 9 Hub integrated shaft 10 Yoke 11 Retaining member 20 Plate material 21 Shaft portion 22 Hub portion 22a Disk portion 22b Cylindrical portion 22c Ridge portion 30 Material 31 Shaft portion 32 Hub portion 41 Rotating center 43 Backing plate 44 Angular whetstone 51 Magnet chuck 52 Shoe 53 Grinding wheel 54 Grinding wheel D Disc R1, R2 Radial bearing part S Seal space T Thrust bearing part

Claims (16)

外周面が、潤滑流体で満たされたラジアル軸受隙間に面する軸部と、軸部から外径に突出し、軸方向と直交する回転体搭載面を有するハブ部とを一体に備えた流体動圧軸受装置用のハブ一体軸であって、
板材の塑性加工により軸部及びハブ部を一体成形した素形材のうち、少なくとも軸部の外周面及びハブ部の回転体搭載面に研削仕上げが施されたハブ一体軸。
Fluid dynamic pressure with an outer peripheral surface integrally provided with a shaft portion facing a radial bearing gap filled with a lubricating fluid and a hub portion having a rotating body mounting surface that projects from the shaft portion to the outer diameter and is orthogonal to the axial direction A hub integrated shaft for a bearing device,
A hub-integrated shaft in which at least the outer peripheral surface of the shaft portion and the rotating body mounting surface of the hub portion are ground and finished out of the shaped material in which the shaft portion and the hub portion are integrally formed by plastic processing of the plate material.
研削仕上げが施されたハブ部の回転体搭載面を基準として、軸部の外周面に研削仕上げが施された請求項1記載のハブ一体軸。   The hub integrated shaft according to claim 1, wherein the outer peripheral surface of the shaft portion is subjected to grinding finish with reference to the rotating body mounting surface of the hub portion subjected to grinding finish. ハブ部の外周面にも研削仕上げが施され、研削仕上げが施されたハブ部の外周面及び回転体搭載面を基準として、軸部の外周面に研削仕上げが施された請求項1記載のハブ一体軸。   The outer peripheral surface of the hub portion is also ground and the outer peripheral surface of the shaft portion is ground with reference to the outer peripheral surface of the hub portion and the rotating body mounting surface subjected to the grinding finish. Hub integrated shaft. 軸部の外周面に対する回転体搭載面の振れ精度が5μm以下である請求項1〜3の何れかに記載のハブ一体軸。   The hub integrated shaft according to any one of claims 1 to 3, wherein a deflection accuracy of the rotating body mounting surface with respect to the outer peripheral surface of the shaft portion is 5 µm or less. 回転体搭載面の平面度が1μm以下である請求項1〜4の何れかに記載のハブ一体軸。   The hub integrated shaft according to any one of claims 1 to 4, wherein the flatness of the rotating body mounting surface is 1 µm or less. 軸部の外周面に表面硬化処理又はコーティング処理が施された請求項1〜5の何れかに記載のハブ一体軸。   The hub-integrated shaft according to any one of claims 1 to 5, wherein the outer peripheral surface of the shaft portion is subjected to surface hardening treatment or coating treatment. 表面硬化処理又はコーティング処理が施された軸部の外周面に、研削仕上げが施された請求項6記載のハブ一体軸。   The hub integrated shaft according to claim 6, wherein the outer peripheral surface of the shaft portion that has been subjected to surface hardening treatment or coating treatment is ground. 研削仕上げが施された軸部の外周面にコーティング処理が施された請求項6記載のハブ一体軸。   The hub-integrated shaft according to claim 6, wherein the outer peripheral surface of the shaft portion that has been ground is coated. Tiを0.05%以上含むフェライト系ステンレス鋼で形成された請求項1〜8の何れかに記載のハブ一体軸。   The hub integrated shaft according to any one of claims 1 to 8, wherein the hub integrated shaft is formed of a ferritic stainless steel containing 0.05% or more of Ti. ハブ部が、軸部から外径に延びる円盤部と、円盤部から軸方向に延びる円筒部と、円筒部から外径に延びる鍔部とを有する請求項1〜9の何れかに記載のハブ一体軸。   The hub according to any one of claims 1 to 9, wherein the hub portion includes a disk portion extending from the shaft portion to the outer diameter, a cylindrical portion extending from the disk portion in the axial direction, and a flange portion extending from the cylindrical portion to the outer diameter. Integral shaft. ハブ部の円盤部の軸方向の肉厚が、軸部の軸方向寸法の20%以下である請求項10記載のハブ一体軸。   The hub-integrated shaft according to claim 10, wherein the axial thickness of the disk portion of the hub portion is 20% or less of the axial dimension of the shaft portion. HDDのスピンドルモータ用として用いられる請求項1〜11の何れかに記載のハブ一体軸。   The hub integrated shaft according to any one of claims 1 to 11, which is used for a spindle motor of an HDD. 請求項1〜12の何れかに記載のハブ一体軸と、ハブ一体軸の軸部が内周に挿入された軸受部材と、軸部の外周面と軸受部材の内周面との間のラジアル軸受隙間に生じる流体膜でハブ一体軸を回転自在に支持するラジアル軸受部とを備えた流体動圧軸受装置。   The hub integrated shaft according to any one of claims 1 to 12, a bearing member in which a shaft portion of the hub integrated shaft is inserted into an inner periphery, and a radial between an outer peripheral surface of the shaft portion and an inner peripheral surface of the bearing member A fluid dynamic bearing device including a radial bearing portion that rotatably supports a hub integrated shaft by a fluid film generated in a bearing gap. 外周面が、潤滑流体で満たされたラジアル軸受隙間に面する軸部と、軸部から外径に突出し、軸方向と直交する回転体搭載面を有するハブ部とを一体に備えた流体動圧軸受装置用のハブ一体軸を製造するための方法であって、
板材を塑性加工することにより、軸部及びハブ部を一体に有する素形材を成形する工程と、素形材の軸部の外周面及びハブ部の回転体搭載面に研削仕上げを施す工程とを有するハブ一体軸の製造方法。
Fluid dynamic pressure with an outer peripheral surface integrally provided with a shaft portion facing a radial bearing gap filled with a lubricating fluid and a hub portion having a rotating body mounting surface that projects from the shaft portion to the outer diameter and is orthogonal to the axial direction A method for manufacturing a hub integrated shaft for a bearing device, comprising:
A step of forming a shaped material integrally having a shaft portion and a hub portion by plastic processing of a plate material; a step of grinding the outer peripheral surface of the shaft portion of the shaped material and the rotating body mounting surface of the hub portion; A method of manufacturing a hub-integrated shaft.
ハブ部の回転体搭載面に研削仕上げを施した後、この回転体搭載面を基準として軸部の外周面に研削仕上げを施す請求項14記載のハブ一体軸の製造方法。   The method for manufacturing a hub-integrated shaft according to claim 14, wherein after the grinding body is finished on the rotating body mounting surface of the hub portion, the outer peripheral surface of the shaft portion is ground with reference to the rotating body mounting surface. ハブ部の回転体搭載面及び外周面に研削仕上げを施した後、この回転体搭載前及び外周面を基準として軸部の外周面に研削仕上げを施す請求項14記載のハブ一体軸の製造方法。   The hub integrated shaft manufacturing method according to claim 14, wherein after grinding is applied to the rotating body mounting surface and the outer peripheral surface of the hub portion, the outer peripheral surface of the shaft portion is subjected to grinding finishing before mounting the rotating body and the outer peripheral surface as a reference. .
JP2010173652A 2010-08-02 2010-08-02 Hub integrated shaft for fluid dynamic pressure bearing device, and method for manufacturing the same Pending JP2012031969A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107225451A (en) * 2017-06-14 2017-10-03 无锡贺邦汽车配件有限公司 A kind of automobile hub polishing burnishing device
JP2021083174A (en) * 2019-11-15 2021-05-27 アイシン・エィ・ダブリュ株式会社 Rotor manufacturing method
JP2021083189A (en) * 2019-11-15 2021-05-27 アイシン・エィ・ダブリュ株式会社 Rotor manufacturing method

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107225451A (en) * 2017-06-14 2017-10-03 无锡贺邦汽车配件有限公司 A kind of automobile hub polishing burnishing device
JP2021083174A (en) * 2019-11-15 2021-05-27 アイシン・エィ・ダブリュ株式会社 Rotor manufacturing method
JP2021083189A (en) * 2019-11-15 2021-05-27 アイシン・エィ・ダブリュ株式会社 Rotor manufacturing method
JP7404800B2 (en) 2019-11-15 2023-12-26 株式会社アイシン Rotor manufacturing method

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