JP2012241728A - Sintered bearing and fluid dynamic pressure bearing device including the same - Google Patents
Sintered bearing and fluid dynamic pressure bearing device including the same Download PDFInfo
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- JP2012241728A JP2012241728A JP2011109307A JP2011109307A JP2012241728A JP 2012241728 A JP2012241728 A JP 2012241728A JP 2011109307 A JP2011109307 A JP 2011109307A JP 2011109307 A JP2011109307 A JP 2011109307A JP 2012241728 A JP2012241728 A JP 2012241728A
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- 239000012530 fluid Substances 0.000 title claims description 24
- 239000000843 powder Substances 0.000 claims abstract description 104
- 229910052751 metal Inorganic materials 0.000 claims abstract description 70
- 239000002184 metal Substances 0.000 claims abstract description 70
- 238000002844 melting Methods 0.000 claims abstract description 29
- 230000008018 melting Effects 0.000 claims abstract description 29
- 230000002093 peripheral effect Effects 0.000 claims description 28
- 239000002245 particle Substances 0.000 claims description 14
- 229910045601 alloy Inorganic materials 0.000 claims description 13
- 239000000956 alloy Substances 0.000 claims description 13
- 238000005245 sintering Methods 0.000 claims description 12
- 229910052802 copper Inorganic materials 0.000 claims description 10
- 229910052718 tin Inorganic materials 0.000 claims description 6
- 238000010304 firing Methods 0.000 claims description 4
- 239000011812 mixed powder Substances 0.000 claims description 4
- 239000012528 membrane Substances 0.000 claims 1
- 239000011148 porous material Substances 0.000 abstract description 13
- 238000005461 lubrication Methods 0.000 abstract description 6
- 238000005204 segregation Methods 0.000 abstract description 5
- 239000000463 material Substances 0.000 abstract description 2
- 229910017755 Cu-Sn Inorganic materials 0.000 description 15
- 229910017927 Cu—Sn Inorganic materials 0.000 description 15
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 15
- 239000003921 oil Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- 230000001050 lubricating effect Effects 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 229910052742 iron Inorganic materials 0.000 description 5
- 239000010687 lubricating oil Substances 0.000 description 5
- 238000004513 sizing Methods 0.000 description 5
- 238000002156 mixing Methods 0.000 description 4
- BGPVFRJUHWVFKM-UHFFFAOYSA-N N1=C2C=CC=CC2=[N+]([O-])C1(CC1)CCC21N=C1C=CC=CC1=[N+]2[O-] Chemical compound N1=C2C=CC=CC2=[N+]([O-])C1(CC1)CCC21N=C1C=CC=CC1=[N+]2[O-] BGPVFRJUHWVFKM-UHFFFAOYSA-N 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000000748 compression moulding Methods 0.000 description 3
- 229910017518 Cu Zn Inorganic materials 0.000 description 2
- 229910017752 Cu-Zn Inorganic materials 0.000 description 2
- 229910017943 Cu—Zn Inorganic materials 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 238000005422 blasting Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000004891 communication Methods 0.000 description 2
- TVZPLCNGKSPOJA-UHFFFAOYSA-N copper zinc Chemical compound [Cu].[Zn] TVZPLCNGKSPOJA-UHFFFAOYSA-N 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000010191 image analysis Methods 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 229910052725 zinc Inorganic materials 0.000 description 2
- 229910000967 As alloy Inorganic materials 0.000 description 1
- 229910000640 Fe alloy Inorganic materials 0.000 description 1
- 229910001096 P alloy Inorganic materials 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000007596 consolidation process Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/12—Structural composition; Use of special materials or surface treatments, e.g. for rust-proofing
- F16C33/128—Porous bearings, e.g. bushes of sintered alloy
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C17/00—Sliding-contact bearings for exclusively rotary movement
- F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
- F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
- F16C17/107—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure with at least one surface for radial load and at least one surface for axial load
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/06—Sliding surface mainly made of metal
- F16C33/12—Structural composition; Use of special materials or surface treatments, e.g. for rust-proofing
- F16C33/121—Use of special materials
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2204/00—Metallic materials; Alloys
- F16C2204/10—Alloys based on copper
- F16C2204/12—Alloys based on copper with tin as the next major constituent
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C2370/00—Apparatus relating to physics, e.g. instruments
- F16C2370/12—Hard disk drives or the like
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Connection Of Motors, Electrical Generators, Mechanical Devices, And The Like (AREA)
- Sliding-Contact Bearings (AREA)
- Powder Metallurgy (AREA)
Abstract
Description
本発明は、金属粉末の圧粉体を焼結して得られる焼結金属からなり、内周面にラジアル軸受面が形成された焼結軸受、及びこれを備えた流体動圧軸受装置に関する。 The present invention relates to a sintered bearing made of a sintered metal obtained by sintering a green compact of a metal powder and having a radial bearing surface formed on an inner peripheral surface, and a fluid dynamic pressure bearing device including the same.
焼結軸受は、内部気孔に潤滑油等の潤滑流体を含浸させて使用され、支持すべき軸との相対回転に伴い内部に含浸された潤滑流体が軸との摺動部に滲み出して流体膜を形成し、この流体膜を介して軸を回転支持するものである。焼結軸受は、その高回転精度および静粛性から、情報機器用のモータスピンドル等に組み込まれる流体動圧軸受として好ましく利用されている。 Sintered bearings are used with the internal pores impregnated with a lubricating fluid such as lubricating oil, and the lubricating fluid impregnated inside oozes into the sliding portion with the shaft as it rotates relative to the shaft to be supported. A film is formed, and the shaft is rotationally supported through the fluid film. Sintered bearings are preferably used as fluid dynamic bearings incorporated in motor spindles for information equipment because of their high rotational accuracy and quietness.
例えば特許文献１に示されている焼結軸受は、Ｃｕ粉末、ＳＵＳ粉末、Ｓｎ粉末等を所定の比率で混合し、所定の形状（多くは円筒状）に圧縮成形した後、焼結することにより形成される。このとき、比較的融点の低いＳｎ粉末は、焼結時に溶融した後固化することにより、Ｃｕ粉末やＳＵＳ粉末を結合するバインダーとして機能する。 For example, the sintered bearing shown in Patent Document 1 is a mixture of Cu powder, SUS powder, Sn powder, etc. at a predetermined ratio, compression-molded into a predetermined shape (mostly cylindrical), and then sintered. It is formed by. At this time, the Sn powder having a relatively low melting point functions as a binder for bonding the Cu powder and the SUS powder by solidifying after melting at the time of sintering.
上記のような焼結軸受の製造において、Ｓｎ粉末が溶融すると、Ｓｎ粉末があった場所に気孔が形成される。このとき、Ｓｎ粉末の粒径が大きかったり、混合粉末中でＳｎ粉末が偏析したりすると、Ｓｎ粉末の溶融により粗大な気孔が形成される。このような粗大な気孔が軸受の表面、特に軸受面に露出すると、潤滑流体が軸受面の表面開孔から内部に浸入しやすくなるため、摺動部に十分な流体膜が形成されず、潤滑不良が生じる恐れがある。特に、このような焼結軸受を流体膜の動圧作用で軸を支持する流体動圧軸受装置に用いると、軸の回転により圧力の高められた流体膜が軸受面の表面開孔から内部に抜けるいわゆる動圧抜けが生じ、十分な動圧作用が得られず、軸受性能が大きく低下する恐れがある。 In the manufacture of the sintered bearing as described above, when the Sn powder is melted, pores are formed at the place where the Sn powder was present. At this time, when the particle size of the Sn powder is large or the Sn powder is segregated in the mixed powder, coarse pores are formed by melting of the Sn powder. If such coarse pores are exposed on the bearing surface, especially the bearing surface, the lubricating fluid will easily enter the surface of the bearing surface from the surface, so that a sufficient fluid film will not be formed on the sliding part and lubrication will occur. Defects may occur. In particular, when such a sintered bearing is used in a fluid dynamic pressure bearing device that supports the shaft by the dynamic pressure action of the fluid film, the fluid film whose pressure is increased by the rotation of the shaft is introduced from the surface opening of the bearing surface to the inside. There is a possibility that so-called dynamic pressure loss occurs, a sufficient dynamic pressure action cannot be obtained, and the bearing performance is greatly deteriorated.
例えば、上記特許文献２に示されているように、Ｃｕ粉末の表面にＳｎを被覆させた粉末を使用すれば、Ｓｎの偏析を回避することができる。しかし、Ｓｎ被覆Ｃｕ粉末は、個々のＣｕ粉末にＳｎをメッキ等により被覆して製造されるため、被覆工程が必要となりコスト高を招く。また、Ｓｎを被覆する工程において、Ｃｕ粉末が小さすぎるとＳｎ同士がくっついてしまうため、Ｃｕ粉末を大きくせざるを得ず、その結果Ｓｎ被覆Ｃｕ粉末の粒径も大きくなる。このような粒径の大きいＳｎ被覆Ｃｕ粉末を用いると、組織が粗くなって内部気孔が増えるため、結局、上記と同様に潤滑不良や動圧作用の低下を招く恐れがある。 For example, as shown in Patent Document 2, Sn segregation can be avoided by using Sn powder coated on the surface of Cu powder. However, since the Sn-coated Cu powder is manufactured by coating Sn on each Cu powder by plating or the like, a coating process is required, resulting in high costs. Further, in the step of coating Sn, if the Cu powder is too small, Sn sticks to each other, so the Cu powder must be increased, and as a result, the particle size of the Sn-coated Cu powder also increases. When such a Sn-coated Cu powder having a large particle size is used, the structure becomes rough and the internal pores increase, and as a result, there is a risk of poor lubrication and a decrease in the dynamic pressure action as described above.
本発明の解決すべき課題は、焼結軸受に粗大な気孔が形成されることを防止し、潤滑不良や動圧作用の低下を防止することにある。 The problem to be solved by the present invention is to prevent coarse pores from being formed in a sintered bearing, and to prevent poor lubrication and a decrease in dynamic pressure action.
前記課題を解決するためになされた本発明は、金属粉末を圧縮成形して得られる圧粉体を焼結して得られる焼結金属からなり、内周面にラジアル軸受面が形成された焼結軸受であって、金属粉末が、主成分金属粉末と低融点金属粉末とを混合した混合粉を焼成して得られる部分合金化粉を含み、表面開孔の最大径を１００μｍ以下としたものである。 The present invention, which has been made to solve the above-mentioned problems, is made of a sintered metal obtained by sintering a green compact obtained by compression-molding a metal powder, and a sintered body having a radial bearing surface formed on the inner peripheral surface. Consolidation bearings in which the metal powder includes partially alloyed powder obtained by firing a mixed powder obtained by mixing the main component metal powder and the low melting point metal powder, and the maximum diameter of the surface opening is 100 μm or less It is.
部分合金化粉は、複数種の金属粉末を混合した混合粉を焼成することにより得られる。主成分金属と低融点金属との部分合金化粉は、主成分金属の粒子と低融点金属の粒子とが溶着した状態であり、両者の界面で部分的に合金化している。このような部分合金化粉を用いることで、圧縮成形金型に供給される金属粉末において低融点金属を均一に混合することができ、偏析を防止できる。また、粒径の小さい主成分金属粉末及び低融点金属粉末を用いて部分合金化粉を製造することで、粒径の小さい部分合金化粉（例えば粒径５０μｍ以下）を容易に得ることができる。このように、微細な部分合金化粉を用いることにより、焼結金属の組織を微細化できると共に、低融点金属の溶融により形成される気孔を減じることができ、その結果、焼結軸受の表面開孔の最大径を１００μｍ以下、好ましくは５０μｍ以下とすることができる。尚、表面開孔の最大径は、回転サイジングやショットブラスト等の封孔処理が施されていない部分において測定するものである。 The partially alloyed powder is obtained by firing a mixed powder obtained by mixing a plurality of types of metal powders. The partially alloyed powder of the main component metal and the low melting point metal is a state in which the main component metal particles and the low melting point metal particles are welded, and is partially alloyed at the interface between them. By using such a partially alloyed powder, the low melting point metal can be uniformly mixed in the metal powder supplied to the compression mold, and segregation can be prevented. In addition, by producing a partially alloyed powder using a main component metal powder and a low melting point metal powder having a small particle size, a partially alloyed powder having a small particle size (for example, a particle size of 50 μm or less) can be easily obtained. . Thus, by using fine partially alloyed powder, the structure of the sintered metal can be refined and the pores formed by melting of the low melting point metal can be reduced. As a result, the surface of the sintered bearing can be reduced. The maximum diameter of the openings can be 100 μm or less, preferably 50 μm or less. The maximum diameter of the surface opening is measured at a portion where the sealing treatment such as rotational sizing or shot blasting is not performed.
尚、表面開孔の最大径とは、焼結軸受の表面開孔部のうち、最も大きな開孔部の直径のことを言うが、必ずしも焼結軸受の全表面の開孔径を測定して最大径を求める必要は無く、焼結軸受の一部領域（例えば外周面の一部）の表面開孔径を測定し、このうちの最大の開孔部の直径を表面開孔の最大径としてもよい。具体的な測定方法としては、例えば、焼結軸受の表面を画像解析することにより表面開孔部を２値化し、個々の開孔部の画素数をカウントする。予め１画素の一辺長あるいは面積を設定し、この設定値から個々の開孔部の面積を求めることができる。この開孔部の面積を円の面積とみなすことで、開孔部の直径を算出することができる。従って、画像解析を行った領域の表面開孔部のうち、最大画素数の開孔部の直径を最大径とすることができる。 Incidentally, the maximum diameter of the surface opening means the diameter of the largest opening portion of the surface opening portion of the sintered bearing, but it is not necessarily measured by measuring the opening diameter of the entire surface of the sintered bearing. There is no need to determine the diameter, and the surface opening diameter of a part of the sintered bearing (for example, a part of the outer peripheral surface) may be measured, and the diameter of the largest opening part may be used as the maximum diameter of the surface opening. . As a specific measuring method, for example, the surface opening portion is binarized by image analysis of the surface of the sintered bearing, and the number of pixels of each opening portion is counted. One side length or area of one pixel is set in advance, and the area of each aperture can be obtained from this set value. By regarding the area of the aperture as the area of a circle, the diameter of the aperture can be calculated. Therefore, the diameter of the opening portion having the maximum number of pixels among the surface opening portions in the region where the image analysis is performed can be set as the maximum diameter.
低融点金属は、焼結温度（通常、７５０〜９５０℃程度）以下の温度で溶融する金属であればよく、例えば、Ｓｎ，Ｚｎ，Ａｌ，Ｐ等の金属が使用できる。また、主成分金属は、例えばＣｕ及びＦｅを使用することができる。例えば、主成分金属としてＣｕを用い、低融点金属としてＳｎを用いれば、Ｃｕ−Ｓｎ部分合金化粉の合金化部分で焼結金属表面の硬度を高めることができる。 The low melting point metal may be any metal that melts at a temperature equal to or lower than the sintering temperature (usually about 750 to 950 ° C.), and for example, a metal such as Sn, Zn, Al, and P can be used. Moreover, Cu and Fe can be used for a main component metal, for example. For example, if Cu is used as the main component metal and Sn is used as the low melting point metal, the hardness of the sintered metal surface can be increased at the alloyed portion of the Cu—Sn partially alloyed powder.
上記の焼結軸受は、軸受表面、特にラジアル軸受面の表面開孔を微細化することができるため、ラジアル軸受面からの潤滑流体の侵入を抑え、優れた動圧作用を得ることができる。特に、ラジアル軸受面にラジアル動圧発生部が形成された焼結軸受は、動圧作用を積極的に発生させて潤滑流体の圧力がより高められるため、本発明を適用して動圧抜けを防止することが望ましい。 Since the sintered bearing described above can reduce the surface opening of the bearing surface, particularly the radial bearing surface, it can suppress the intrusion of the lubricating fluid from the radial bearing surface and can obtain an excellent dynamic pressure action. In particular, a sintered bearing having a radial dynamic pressure generating portion formed on a radial bearing surface actively generates a dynamic pressure action to increase the pressure of the lubricating fluid. It is desirable to prevent.
上記の焼結軸受は、焼結軸受の内周に挿入された軸部材と、焼結軸受のラジアル軸受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流体膜で、軸部材を相対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に適用することができる。 The above-mentioned sintered bearing is a fluid film generated in a radial bearing gap between the shaft member inserted in the inner periphery of the sintered bearing and the radial bearing surface of the sintered bearing and the outer peripheral surface of the shaft member. The present invention can be applied to a fluid dynamic pressure bearing device including a radial bearing portion that is rotatably supported.
また、前記課題は、金属粉末の圧粉体を焼結して得られる焼結金属からなり、内周面にラジアル軸受面が形成された焼結軸受であって、金属粉末が、主成分金属及び低融点金属の合金からなる合金粉を含み、表面開孔の最大径を１００μｍ以下とした焼結軸受により解決することもできる。 The subject is a sintered bearing made of a sintered metal obtained by sintering a green compact of a metal powder, and having a radial bearing surface formed on an inner peripheral surface, wherein the metal powder is a main component metal. And a sintered bearing containing an alloy powder made of an alloy of a low melting point metal and having a maximum surface opening diameter of 100 μm or less.
このように、主成分金属及び低融点金属の合金粉を用いることで、部分合金化粉を用いた場合と同様に、低融点金属の偏析を防止できる。また、低融点金属が合金化することで、融点が上昇し、焼結温度により溶融しにくくなる。これにより、低融点金属が溶融して大きな気孔が形成されることがなく、その結果、焼結軸受の表面開孔の最大径を１００μｍ以下とすることができる。 Thus, by using the alloy powder of the main component metal and the low melting point metal, it is possible to prevent segregation of the low melting point metal as in the case of using the partially alloyed powder. In addition, when the low melting point metal is alloyed, the melting point rises and is difficult to melt depending on the sintering temperature. Thereby, the low melting point metal does not melt and large pores are formed, and as a result, the maximum diameter of the surface opening of the sintered bearing can be made 100 μm or less.
以上のように、本発明によれば、主成分金属と低融点金属との部分合金化粉あるいは合金粉を用いることで、焼結金属の表面開孔を微細化することができ、これにより潤滑不良や動圧作用の低下を防止することができる。 As described above, according to the present invention, by using a partially alloyed powder or alloy powder of a main component metal and a low-melting-point metal, the surface opening of the sintered metal can be refined, and lubrication is thereby achieved. It is possible to prevent defects and a decrease in dynamic pressure action.
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に示すスピンドルモータは、ＨＤＤのディスク駆動装置に用いられ、軸部材２を回転自在に非接触支持する流体動圧軸受装置１と、軸部材２に装着されたディスクハブ３と、例えば半径方向のギャップを介して対向させたステータコイル４およびロータマグネット５とを備える。ステータコイル４はモータブラケット６の外周に取付けられ、ロータマグネット５は、ディスクハブ３の内周に取付けられる。ディスクハブ３は、その外周に磁気ディスクＤを一枚または複数枚（図１では２枚）保持する。このように構成されたスピンドルモータにおいて、ステータコイル４に通電するとロータマグネット５が回転し、これに伴ってディスクハブ３およびディスクハブ３に保持されたディスクＤが軸部材２と一体に回転する。 The spindle motor shown in FIG. 1 is used in a disk drive device of an HDD, and includes a fluid dynamic bearing device 1 that rotatably supports a shaft member 2 in a non-contact manner, a disk hub 3 mounted on the shaft member 2, and a radius, for example. A stator coil 4 and a rotor magnet 5 are provided to face each other with a gap in the direction. The stator coil 4 is attached to the outer periphery of the motor bracket 6, and the rotor magnet 5 is attached to the inner periphery of the disk hub 3. The disk hub 3 holds one or more magnetic disks D (two in FIG. 1) on the outer periphery thereof. In the spindle motor configured as described above, when the stator coil 4 is energized, the rotor magnet 5 rotates, and accordingly, the disk hub 3 and the disk D held by the disk hub 3 rotate integrally with the shaft member 2.
流体動圧軸受装置１は、図２に示すように、軸部材２と、有底筒状のハウジング７と、本発明の一実施形態に係る焼結軸受８と、シール部材９とを主な構成要素として構成されている。なお、以下の説明では、説明の便宜上、軸方向でハウジング７の閉塞側を下側、開口側を上側とする。 As shown in FIG. 2, the fluid dynamic bearing device 1 mainly includes a shaft member 2, a bottomed cylindrical housing 7, a sintered bearing 8 according to an embodiment of the present invention, and a seal member 9. It is configured as a component. In the following description, for convenience of description, the closed side of the housing 7 in the axial direction is defined as the lower side, and the opening side is defined as the upper side.
軸部材２は、例えばステンレス鋼等の金属材料で形成され、軸部２ａと、軸部２ａの下端に設けられたフランジ部２ｂとを備えている。軸部２ａは、円筒状の外周面２ａ１と、上方へ向けて漸次縮径したテーパ面２ａ２とを有する。軸部２ａの外周面２ａ１は焼結軸受８の内周に配され、テーパ面２ａ２はシール部材９の内周に配される。 The shaft member 2 is formed of a metal material such as stainless steel, for example, and includes a shaft portion 2a and a flange portion 2b provided at the lower end of the shaft portion 2a. The shaft portion 2a has a cylindrical outer peripheral surface 2a1 and a tapered surface 2a2 that is gradually reduced in diameter upward. The outer peripheral surface 2 a 1 of the shaft portion 2 a is disposed on the inner periphery of the sintered bearing 8, and the tapered surface 2 a 2 is disposed on the inner periphery of the seal member 9.
焼結軸受８は、略円筒状の焼結金属からなり、本実施形態では、主成分金属としてＣｕ及びＦｅを、低融点金属としてＳｎを有する焼結金属からなる。焼結軸受８の内周面８ａはラジアル軸受面として機能し、ラジアル軸受隙間の潤滑油に動圧作用を発生させるためのラジアル動圧発生部が形成される。本実施形態では、図３に示すように、焼結軸受８の内周面８ａの軸方向に離隔した２箇所に、ラジアル動圧発生部としてヘリングボーン形状の動圧溝８ａ１，８ａ２が形成される。上側の動圧溝領域では、動圧溝８ａ１が軸方向非対称形状に形成され、具体的には、丘部の軸方向略中央部に形成された帯状部分に対して、上側の溝の軸方向寸法Ｘ１が下側の溝の軸方向寸法Ｘ２よりも大きくなっている（Ｘ１＞Ｘ２）。下側の動圧溝領域では、動圧溝８ａ２が軸方向対称形状に形成される。以上に述べた上下動圧溝領域でのポンピング能力のアンバランスにより、軸部材２の回転中は、焼結軸受８の内周面８ａと軸部２ａの外周面との間に満たされた油が下方に押し込まれるようになる。 The sintered bearing 8 is made of a substantially cylindrical sintered metal. In the present embodiment, the sintered bearing 8 is made of a sintered metal having Cu and Fe as main component metals and Sn as a low melting point metal. The inner peripheral surface 8a of the sintered bearing 8 functions as a radial bearing surface, and a radial dynamic pressure generating portion for generating a dynamic pressure action on the lubricating oil in the radial bearing gap is formed. In this embodiment, as shown in FIG. 3, herringbone-shaped dynamic pressure grooves 8a1 and 8a2 are formed as radial dynamic pressure generating portions at two locations separated in the axial direction of the inner peripheral surface 8a of the sintered bearing 8. The In the upper dynamic pressure groove region, the dynamic pressure groove 8a1 is formed in an axially asymmetric shape, specifically, the axial direction of the upper groove with respect to the belt-like portion formed in the substantially central portion in the axial direction of the hill. The dimension X1 is larger than the axial dimension X2 of the lower groove (X1> X2). In the lower dynamic pressure groove region, the dynamic pressure groove 8a2 is formed in an axially symmetrical shape. The oil filled between the inner peripheral surface 8a of the sintered bearing 8 and the outer peripheral surface of the shaft portion 2a during the rotation of the shaft member 2 due to the unbalance of the pumping ability in the vertical dynamic pressure groove region described above. Will be pushed downward.
焼結軸受８の下側端面８ｃはスラスト軸受面として機能する。焼結軸受８の下側端面８ｃには、スラスト軸受隙間の油膜に動圧作用を発生させるためのスラスト動圧発生部が形成される。本実施形態では、図９に示すように、焼結軸受８の下側端面８ｃにスラスト動圧発生部としてスパイラル形状の動圧溝８ｃ１が形成される。焼結軸受８の外周面８ｄには、円周方向等間隔の複数箇所（図示例では３箇所）に軸方向溝８ｄ１が形成される。焼結軸受８の外周面８ｄとハウジング７の内周面７ｃとを固定した状態で、軸方向溝８ｄ１は油の連通路として機能し、この連通路により軸受内部の圧力バランスを適正範囲内に保つことができる。 The lower end surface 8c of the sintered bearing 8 functions as a thrust bearing surface. A thrust dynamic pressure generating portion for generating a dynamic pressure action on the oil film in the thrust bearing gap is formed on the lower end surface 8 c of the sintered bearing 8. In the present embodiment, as shown in FIG. 9, a spiral-shaped dynamic pressure groove 8c1 is formed on the lower end face 8c of the sintered bearing 8 as a thrust dynamic pressure generating portion. On the outer peripheral surface 8d of the sintered bearing 8, axial grooves 8d1 are formed at a plurality of locations (three locations in the illustrated example) at equal intervals in the circumferential direction. In a state where the outer peripheral surface 8d of the sintered bearing 8 and the inner peripheral surface 7c of the housing 7 are fixed, the axial groove 8d1 functions as an oil communication passage, and this communication passage allows the pressure balance inside the bearing to be within an appropriate range. Can keep.
焼結軸受８は、金属粉末を圧縮成形して圧粉体を得る圧縮成形工程と、圧粉体を焼結して焼結体を得る焼結工程と、焼結体を所定寸法にサイジングするサイジング工程を経て製造される。本実施形態では、サイジング工程において動圧溝８ａ１，８ａ２，及び８ｃ１が成形される。 The sintered bearing 8 is a compression molding process for compressing metal powder to obtain a green compact, a sintering process for sintering a green compact to obtain a sintered body, and sizing the sintered body to a predetermined size. Manufactured through a sizing process. In the present embodiment, the dynamic pressure grooves 8a1, 8a2, and 8c1 are formed in the sizing process.
焼結軸受８の原料となる金属粉末は、Ｆｅ系粉末、Ｃｕ−Ｓｎ部分合金化粉、Ｃ粉末を所定の比率で混合したものが使用される。Ｆｅ系粉末とは、Ｆｅを主成分とする金属粉末であり、Ｆｅ単体の粉末の他、Ｆｅ合金粉末（例えばステンレス鋼粉末）を含む。各粉末の比率は、Ｃｕ及びＦｅが主成分である限り特に限定されないが、例えばＦｅ系粉末４０％、Ｃｕ−Ｓｎ部分合金化粉５８％、Ｃ粉末２％の比率で混合される。Ｃｕ−Ｓｎ部分合金化粉は、Ｃｕ粉末及びＳｎ粉末を別個に形成した後、これらの粉末を混合して焼成することにより得られる。このときのＣｕ粉末とＳｎ粉末との配合比率は、例えば１００:３とされる。こうして得られたＣｕ−Ｓｎ部分合金化粉は、Ｃｕ粉末にＳｎ粉末が溶着した状態となっており、両者の界面が部分的に合金化している。また、粒径の小さいＣｕ粉末及びＳｎ粉末を用いることで、微細なＣｕ−Ｓｎ部分合金化粉を容易に得ることができ、例えば粒径が５０μｍ以下のものを得ることができる。ただし、Ｃｕ−Ｓｎ部分合金化粉の粒径が小さすぎると、圧縮成形工程の金型内における粒子の流動性が悪くなり、成形性が低下するため、各粉末の粒径は４０μｍ以上であることが好ましい。 The metal powder used as the raw material of the sintered bearing 8 is a mixture of Fe-based powder, Cu—Sn partially alloyed powder, and C powder in a predetermined ratio. The Fe-based powder is a metal powder containing Fe as a main component, and includes Fe alloy powder (for example, stainless steel powder) in addition to powder of Fe alone. The ratio of each powder is not particularly limited as long as Cu and Fe are the main components. For example, the ratios of Fe-based powder 40%, Cu-Sn partially alloyed powder 58%, and C powder 2% are mixed. Cu-Sn partially alloyed powder is obtained by separately forming Cu powder and Sn powder, and then mixing and firing these powders. At this time, the blending ratio of the Cu powder and the Sn powder is, for example, 100: 3. The Cu—Sn partially alloyed powder thus obtained is in a state in which the Sn powder is welded to the Cu powder, and the interface between them is partially alloyed. Moreover, by using Cu powder and Sn powder with a small particle diameter, a fine Cu-Sn partial alloying powder can be obtained easily, for example, a particle diameter of 50 micrometers or less can be obtained. However, if the particle diameter of the Cu-Sn partially alloyed powder is too small, the fluidity of the particles in the mold in the compression molding step is deteriorated and the moldability is lowered, so the particle diameter of each powder is 40 μm or more. It is preferable.
このように、Ｃｕ−Ｓｎ部分合金化粉を用いることで、ＣｕとＳｎとを均一に混合することができるため、Ｓｎの偏析を防止できる。また、粒径の小さいＣｕ−Ｓｎ部分合金化粉を用いることで、焼結時にＳｎが溶融した場合でも、これにより形成される気孔は小さいため、焼結軸受８に粗大な気孔が形成されることを防止できる。従って、焼結軸受８の表面開孔、特にラジアル軸受面及びスラスト軸受面の表面開孔を微細化することができ、具体的には表面開孔の最大径を１００μｍ以下にすることができる。これにより、表面開孔からの潤滑流体の侵入を抑え、潤滑不良や動圧作用の低下を防止できる。特に、上記のようにラジアル動圧発生部やスラスト動圧発生部を設けた場合、ラジアル軸受隙間及びスラスト軸受隙間の潤滑流体の圧力が積極的に高められるため、焼結軸受８の表面開孔を小さくして動圧抜けを防止することが効果的である。尚、焼結軸受８のラジアル軸受面及びスラスト軸受面の表面開孔をさらに小さくするために、回転サイジングやショットブラスト等による封孔処理を施しても良い。また、表面開孔の最大径は０より大きければ良いが、成形性を考慮するとある程度内部気孔を残すことが好ましいため、気孔率が５％以上となる程度に設定される。 Thus, since Cu and Sn can be mixed uniformly by using Cu-Sn partially alloyed powder, segregation of Sn can be prevented. Further, by using Cu—Sn partially alloyed powder having a small particle size, even when Sn is melted during sintering, the pores formed thereby are small, so that coarse pores are formed in the sintered bearing 8. Can be prevented. Therefore, the surface opening of the sintered bearing 8, particularly the surface opening of the radial bearing surface and the thrust bearing surface can be miniaturized. Specifically, the maximum diameter of the surface opening can be made 100 μm or less. Thereby, intrusion of the lubricating fluid from the surface opening can be suppressed, and poor lubrication and a decrease in the dynamic pressure action can be prevented. In particular, when the radial dynamic pressure generating portion and the thrust dynamic pressure generating portion are provided as described above, the pressure of the lubricating fluid in the radial bearing gap and the thrust bearing gap is positively increased. It is effective to reduce the dynamic pressure to prevent the loss of dynamic pressure. In addition, in order to further reduce the surface opening of the radial bearing surface and the thrust bearing surface of the sintered bearing 8, a sealing process such as rotational sizing or shot blasting may be performed. In addition, the maximum diameter of the surface opening may be larger than 0, but it is preferable to leave the internal pores to some extent in consideration of moldability, so the porosity is set to be 5% or more.
ハウジング７は、内周に焼結軸受８が保持された筒状の側部７ａと、側部７ａの下端を閉塞する底部７ｂとを一体に有する。ハウジング７の底部７ｂの上側端面７ｂ１には、スラスト軸受隙間の油膜に動圧作用を発生させるためのスラスト動圧発生部として、例えばスパイラル形状の動圧溝が形成される（図示省略）。 The housing 7 integrally has a cylindrical side portion 7a in which the sintered bearing 8 is held on the inner periphery and a bottom portion 7b that closes the lower end of the side portion 7a. On the upper end surface 7b1 of the bottom 7b of the housing 7, for example, a spiral dynamic pressure groove is formed as a thrust dynamic pressure generating portion for generating a dynamic pressure action on the oil film in the thrust bearing gap (not shown).
シール部材９は、例えば樹脂材料や金属材料で環状に形成され、ハウジング７の側部７ａの上端部内周に配設される。シール部材９の内周面９ａは、軸部２ａの外周に設けられたテーパ面２ａ２と径方向に対向し、これらの間に下方へ向けて径方向寸法を漸次縮小したシール空間Ｓが形成される。このシール空間Ｓの毛細管力により、潤滑油が軸受内部側に引き込まれ、油の漏れ出しが防止される。本実施形態では、軸部２ａ側にテーパ面２ａ２を形成しているため、シール空間Ｓは遠心力シールとしても機能する。シール部材９で密封されたハウジング７の内部空間に充満した潤滑油の油面は、シール空間Ｓの範囲内に維持される。すなわち、シール空間Ｓは、潤滑油の体積変化を吸収できる容積を有する。 The seal member 9 is formed in an annular shape with, for example, a resin material or a metal material, and is disposed on the inner periphery of the upper end portion of the side portion 7 a of the housing 7. The inner peripheral surface 9a of the seal member 9 is opposed to the tapered surface 2a2 provided on the outer periphery of the shaft portion 2a in the radial direction, and a seal space S in which the radial dimension is gradually reduced downward is formed therebetween. The Due to the capillary force of the seal space S, the lubricating oil is drawn into the inside of the bearing, and oil leakage is prevented. In this embodiment, since the taper surface 2a2 is formed on the shaft portion 2a side, the seal space S also functions as a centrifugal force seal. The oil level of the lubricating oil filled in the internal space of the housing 7 sealed with the seal member 9 is maintained within the range of the seal space S. That is, the seal space S has a volume that can absorb the volume change of the lubricating oil.
上記構成の流体動圧軸受装置１において、軸部材２が回転すると、焼結軸受８の内周面８ａ（ラジアル軸受面）と軸部２ａの外周面２ａ１との間にラジアル軸受隙間が形成される。このラジアル軸受隙間に生じた油膜の圧力が、焼結軸受８の内周面８ａに形成された動圧溝８ａ１，８ａ２により高められ、この動圧作用により軸部２ａを回転自在に非接触支持する第１ラジアル軸受部Ｒ１および第２ラジアル軸受部Ｒ２が構成される。 In the fluid dynamic pressure bearing device 1 configured as described above, when the shaft member 2 rotates, a radial bearing gap is formed between the inner peripheral surface 8a (radial bearing surface) of the sintered bearing 8 and the outer peripheral surface 2a1 of the shaft portion 2a. The The pressure of the oil film generated in the radial bearing gap is increased by the dynamic pressure grooves 8a1 and 8a2 formed on the inner peripheral surface 8a of the sintered bearing 8, and the shaft portion 2a is rotatably supported in a non-contact manner by this dynamic pressure action. A first radial bearing portion R1 and a second radial bearing portion R2 are configured.
これと同時に、フランジ部２ｂの上側端面２ｂ１と焼結軸受８の下側端面８ｃ（スラスト軸受面）との間のスラスト軸受隙間、およびフランジ部２ｂの下側端面２ｂ２とハウジング７の底部７ｂの上側端面７ｂ１との間のスラスト軸受隙間に油膜が形成され、動圧溝の動圧作用により油膜の圧力が高められる。この動圧作用により、フランジ部２ｂを両スラスト方向に回転自在に非接触支持する第１スラスト軸受部Ｔ１および第２スラスト軸受部Ｔ２とが構成される。 At the same time, a thrust bearing gap between the upper end surface 2b1 of the flange portion 2b and the lower end surface 8c (thrust bearing surface) of the sintered bearing 8, and the lower end surface 2b2 of the flange portion 2b and the bottom portion 7b of the housing 7 are provided. An oil film is formed in the thrust bearing gap between the upper end surface 7b1 and the pressure of the oil film is increased by the dynamic pressure action of the dynamic pressure groove. By this dynamic pressure action, the first thrust bearing portion T1 and the second thrust bearing portion T2 are configured to support the flange portion 2b in a non-contact manner so as to be rotatable in both thrust directions.
本発明は上記の実施形態に限られない。例えば、上記の実施形態では、焼結軸受８の原料としてＣｕ−Ｓｎ部分合金化粉を用いた場合を示したが、この替わりにＣｕ−Ｓｎ合金粉を用いても良い。Ｃｕ−Ｓｎ合金粉は、例えばＣｕ及びＳｎを完全に溶融した状態で混合し、アトマイズ法により製造される。Ｃｕ−Ｓｎ合金粉を用いることで、Ｓｎを焼結軸受８に均一に拡散させることができる。また、Ｃｕ−Ｓｎ合金粉の個々の粒子は、ＣｕとＳｎが完全に合金化した状態となっているため、Ｓｎよりも融点が高くなっている。従って、焼結温度で溶融しにくくなる。以上により、Ｓｎの溶融により粗大な気孔が形成されることを防止できる。 The present invention is not limited to the above embodiment. For example, in the above embodiment, the case where Cu—Sn partially alloyed powder is used as the raw material of the sintered bearing 8 is shown, but Cu—Sn alloy powder may be used instead. Cu-Sn alloy powder is manufactured by, for example, an atomizing method in which Cu and Sn are mixed in a completely molten state. By using the Cu—Sn alloy powder, Sn can be uniformly diffused into the sintered bearing 8. Moreover, since the individual particles of the Cu—Sn alloy powder are in a state where Cu and Sn are completely alloyed, the melting point is higher than that of Sn. Therefore, it becomes difficult to melt at the sintering temperature. As described above, coarse pores can be prevented from being formed by melting of Sn.
また、以上の実施形態では、主成分金属としてＣｕ及びＦｅを用い、低融点金属としてＳｎを用いた場合を示しているが、これに限られない。例えば、主成分金属としてＣｕやＦｅを単独で用いる他、Ｆｅ系合金等を使用することもできる。また、低融点金属としてＺｎ，Ａｌ，あるいはＰを使用することもできる。これらの場合、部分合金化粉として、例えばＣｕ−Ｚｎ部分合金化粉を製造することができる。また、合金粉として、Ｃｕ−Ｚｎ合金粉や、Ｆｅ−Ｐ合金粉を製造することができる。 Moreover, although the case where Cu and Fe were used as a main component metal and Sn was used as a low melting metal was shown in the above embodiment, it is not restricted to this. For example, in addition to using Cu or Fe alone as the main component metal, an Fe-based alloy or the like can also be used. Moreover, Zn, Al, or P can also be used as the low melting point metal. In these cases, for example, Cu—Zn partially alloyed powder can be produced as the partially alloyed powder. Moreover, Cu-Zn alloy powder and Fe-P alloy powder can be manufactured as alloy powder.
また、以上の実施形態では、ラジアル動圧発生部として、ヘリングボーン形状の動圧溝が例示されているが、これに限らず、例えば、いわゆるステップ軸受や波型軸受、あるいは多円弧軸受を採用することもできる。また、焼結軸受８の内周面８ａ及び軸部材２の外周面２ａ１の双方を円筒面とし、ラジアル軸受部Ｒ１、Ｒ２として、動圧発生部を有しない、いわゆる真円軸受を採用することもできる。 In the above embodiment, a herringbone-shaped dynamic pressure groove is exemplified as the radial dynamic pressure generating portion. However, the present invention is not limited to this, and for example, a so-called step bearing, wave bearing, or multi-arc bearing is adopted. You can also In addition, both the inner peripheral surface 8a of the sintered bearing 8 and the outer peripheral surface 2a1 of the shaft member 2 are cylindrical surfaces, and so-called circular bearings having no dynamic pressure generating portions are employed as the radial bearing portions R1 and R2. You can also.
また、以上の実施形態では、スラスト動圧発生部として、スパイラル形状の動圧溝が例示されているが、これに限らず、例えばステップ軸受や波型軸受を採用することもできる。あるいは、スラスト軸受部Ｔ１、Ｔ２として、軸部材の端部を接触支持するピボット軸受を採用することもできる。この場合、焼結軸受８の下側端面８ｃはスラスト軸受面として機能しない。 Further, in the above embodiment, the spiral dynamic pressure groove is exemplified as the thrust dynamic pressure generating portion, but not limited to this, for example, a step bearing or a wave bearing can also be adopted. Or the pivot bearing which contacts and supports the edge part of a shaft member is also employable as thrust bearing part T1, T2. In this case, the lower end surface 8c of the sintered bearing 8 does not function as a thrust bearing surface.
また、以上の実施形態では、ラジアル動圧発生部及びスラスト動圧発生部がそれぞれ焼結軸受８の内周面８ａ、下側端面８ｃ、及びハウジング７の内底面７ｂ１に形成されているが、これらの面と軸受隙間を介して対向する面、すなわち軸部２ａの外周面２ａ１、フランジ部２ｂの上側端面２ｂ１及び下側端面２ｂ２に形成してもよい。 In the above embodiment, the radial dynamic pressure generating portion and the thrust dynamic pressure generating portion are formed on the inner peripheral surface 8a, the lower end surface 8c of the sintered bearing 8, and the inner bottom surface 7b1 of the housing 7, respectively. You may form in the surface which opposes these surfaces through a bearing clearance, ie, the outer peripheral surface 2a1 of the axial part 2a, the upper side end surface 2b1, and the lower side end surface 2b2 of the flange part 2b.
また、本発明の動圧軸受装置は、上記のようにＨＤＤ等のディスク駆動装置に用いられるスピンドルモータに限らず、光ディスクの光磁気ディスク駆動用のスピンドルモータ等、高速回転下で使用される情報機器用の小型モータ、レーザビームプリンタのポリゴンスキャナモータ等における回転軸支持用、あるいは電気機器の冷却用のファンモータとしても好適に使用することができる。 Further, the hydrodynamic bearing device of the present invention is not limited to the spindle motor used in the disk drive device such as the HDD as described above, but is used for information used under high-speed rotation, such as a spindle motor for driving a magneto-optical disk of an optical disk. It can also be suitably used as a fan motor for supporting a rotating shaft in a small motor for equipment, a polygon scanner motor of a laser beam printer, or for cooling an electrical equipment.
本発明の効果を確認するために、本発明の実施例に係る焼結軸受と、比較例に係る焼結軸受とを製作した。実施例に係る焼結軸受は、Ｃｕ粉末及びＣｕ―Ｓｎ部分合金化粉を含む混合金属粉末で形成したものである。一方、比較例に係る焼結軸受は、Ｃｕ粉末及びＳｎ粉末を含む混合金属粉末で形成したものである。実施例に係る焼結軸受の表面には、図５に示すように、直径が１００μｍを超えるような粗大気孔は形成されていない（図示例では最大径が約５０μｍ以下）。一方、比較例に係る焼結軸受の表面には、図６に示すように、直径が１００μｍを超える粗大気孔が形成されている。尚、図５及び図６の写真のうち、黒色部分が表面開孔を表している。 In order to confirm the effect of the present invention, a sintered bearing according to an example of the present invention and a sintered bearing according to a comparative example were manufactured. The sintered bearing according to the example is formed of mixed metal powder including Cu powder and Cu—Sn partially alloyed powder. On the other hand, the sintered bearing which concerns on a comparative example is formed with the mixed metal powder containing Cu powder and Sn powder. On the surface of the sintered bearing according to the example, as shown in FIG. 5, no rough atmospheric holes having a diameter exceeding 100 μm are formed (the maximum diameter is about 50 μm or less in the illustrated example). On the other hand, as shown in FIG. 6, rough air holes having a diameter exceeding 100 μm are formed on the surface of the sintered bearing according to the comparative example. In the photographs of FIGS. 5 and 6, the black portion represents the surface opening.
上記の実施例及び比較例に係る焼結軸受を用いて軸振れ試験を行った。具体的には、各焼結軸受の内周に軸部材を挿入し、軸部材を所定の回転数（例えば１００００ｒ／ｍｉｎ）で回転させ、軸部材の所定の軸方向位置（例えば、焼結軸受から突出した軸部材のうち、焼結軸受の端面から１０ｍｍの軸方向位置）における外周面の振れ量を測定した。軸部材には外径に突出したロータを固定し、ロータの円周方向１箇所にアンバランスを付与するためのウエイトを設けた。このウエイトによるアンバランス量、すなわち、ウエイトの重さ（ｇ）と軸心からの半径方向距離（ｃｍ）との積を変化させ、アンバランス量に対する軸部材の振れ量（μｍ）を測定した。その結果、図７に示すように、実施例に係る焼結軸受は比較例に係る焼結軸受よりも軸部材の振れ量が小さく、且つ、アンバランス量が大きいほど振れ量の差は広がった。この試験結果から、本発明の実施例に係る焼結軸受は、比較例に係る焼結軸受よりも軸部材の支持能力に優れていることが明らかとなった。 An axial runout test was performed using the sintered bearings according to the above-described Examples and Comparative Examples. Specifically, a shaft member is inserted into the inner periphery of each sintered bearing, the shaft member is rotated at a predetermined rotational speed (for example, 10000 r / min), and a predetermined axial position of the shaft member (for example, a sintered bearing) Among the shaft members protruding from the outer peripheral surface, the deflection amount of the outer peripheral surface at an axial position of 10 mm from the end face of the sintered bearing was measured. A rotor projecting to the outer diameter was fixed to the shaft member, and a weight for imparting unbalance to one place in the circumferential direction of the rotor was provided. The unbalance amount due to the weight, that is, the product of the weight weight (g) and the radial distance (cm) from the shaft center was changed, and the deflection amount (μm) of the shaft member relative to the unbalance amount was measured. As a result, as shown in FIG. 7, the sintered bearing according to the example has a smaller amount of shaft member deflection than the sintered bearing according to the comparative example, and the larger the unbalance amount, the wider the difference in the amount of deflection. . From this test result, it was clarified that the sintered bearing according to the example of the present invention is superior in supporting ability of the shaft member than the sintered bearing according to the comparative example.
１ 流体動圧軸受装置
２ 軸部材
３ ディスクハブ
４ ステータコイル
５ ロータマグネット
６ モータブラケット
７ ハウジング
８ 焼結軸受
８ａ 内周面（ラジアル軸受面）
８ａ１，８ａ２ 動圧溝（ラジアル動圧発生部）
８ｃ 下側端面（スラスト軸受面）
８ｃ１ 動圧溝（スラスト動圧発生部）
９ シール部材
Ｄ ディスク
Ｒ１，Ｒ２ ラジアル軸受部
Ｔ１，Ｔ２ スラスト軸受部
Ｓ シール空間
DESCRIPTION OF SYMBOLS 1 Fluid dynamic pressure bearing apparatus 2 Shaft member 3 Disc hub 4 Stator coil 5 Rotor magnet 6 Motor bracket 7 Housing 8 Sintered bearing 8a Inner peripheral surface (radial bearing surface)
8a1, 8a2 Dynamic pressure groove (Radial dynamic pressure generator)
8c Lower end surface (thrust bearing surface)
8c1 Dynamic pressure groove (Thrust dynamic pressure generator)
9 Seal member D Disc R1, R2 Radial bearing portion T1, T2 Thrust bearing portion S Seal space
Claims (7)
金属粉末が、主成分金属粉末及び低融点金属粉末の混合粉末を焼成して得られる部分合金化粉を含み、表面開孔の最大径を１００μｍ以下とした焼結軸受。 A sintered bearing made of sintered metal obtained by sintering a green compact of a metal powder, and having a radial bearing surface formed on the inner peripheral surface,
A sintered bearing in which the metal powder includes a partially alloyed powder obtained by firing a mixed powder of a main component metal powder and a low melting point metal powder, and the maximum diameter of the surface opening is 100 μm or less.
金属粉末が、主成分金属及び低融点金属の合金からなる合金粉を含み、表面開孔の最大径を１００μｍ以下とした焼結軸受。 A sintered bearing made of sintered metal obtained by sintering a green compact of a metal powder, and having a radial bearing surface formed on the inner peripheral surface,
A sintered bearing in which the metal powder includes an alloy powder composed of an alloy of a main component metal and a low melting point metal, and the maximum diameter of the surface opening is 100 μm or less.
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