JP2007231966A - Sintered hydrodynamic bearing manufacturing method - Google Patents
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本発明は、焼結軸受のうち、特に軸受表面あるいは動圧溝面を封孔した焼結動圧軸受の製造方法に関するものであり、精密回転を必要とする磁気ディスク装置や光ディスク装置のディスクドライブモータおよびレーザプリンター用ポリゴンミラーモータなどに用いられる焼結動圧軸受として好適である。 The present invention relates to a method of manufacturing a sintered dynamic pressure bearing having a sealed bearing surface or a dynamic pressure groove surface among sintered bearings, and more particularly to a magnetic disk device and a disk drive of an optical disk device that require precise rotation. It is suitable as a sintered dynamic pressure bearing used for motors and polygon mirror motors for laser printers.
情報機器に使用される上記モータは、高速性や高回転精度のほか、量産性、低コスト化および低騒音化が求められている。このような要求性能は、シャフトを支持する軸受に課せられており、最近では含油焼結軸受に動圧溝を設けた軸受が提案されている。磁気ディスク装置の例では、スピンドルモータに組み込まれる動圧軸受としてハウジングに焼結含油軸受を固定するとともに軸受に動圧発生用のヘリングボーン溝やスパイラル溝を設けた焼結動圧軸受が提案されている。 In addition to high speed and high rotational accuracy, the motors used in information equipment are required to be mass-productive, low in cost, and low in noise. Such required performance is imposed on the bearing that supports the shaft. Recently, a bearing in which a hydrodynamic groove is provided in an oil-impregnated sintered bearing has been proposed. As an example of a magnetic disk device, a sintered hydrodynamic bearing in which a sintered oil-impregnated bearing is fixed to a housing as a dynamic pressure bearing incorporated in a spindle motor and a herringbone groove or a spiral groove for generating dynamic pressure is provided on the bearing has been proposed. ing.
この種の焼結動圧軸受では、動圧作用をより高くするために、軸受のうち軸受面等の気孔を封鎖し、あるいは少なくする。この封孔としては、焼結動圧軸受を高密度に成形する方法以外に、軸受を各種のブラストやタンブラー処理で封孔したり、樹脂を焼結体の気孔内に含浸硬化して封孔する方法が採用される（特許文献１等）。また樹脂を焼結体の気孔内に含浸硬化して封孔する方法は、樹脂含浸、余剰樹脂の除去、樹脂硬化の手順で行われ、有機モノマー型含浸剤、有機ポリマー型含浸剤、溶剤カット型含浸剤、水性エマルジョン型含浸剤が使用される（特許文献２等）。さらに、樹脂を焼結体の気孔内に含浸し硬化させて封孔した後、焼結体を金型に入れ圧力を加える塑性加工処理により、樹脂の硬化収縮等に起因して生じる気孔内の隙間を縮小又は閉塞することも提案されている（特許文献３）。 In this type of sintered dynamic pressure bearing, in order to further increase the dynamic pressure action, pores such as the bearing surface of the bearing are blocked or reduced. In addition to the method of forming a sintered dynamic pressure bearing at a high density, the sealing is performed by sealing the bearing by various blasting or tumbling treatments, or by impregnating and hardening resin in the pores of the sintered body. The method to do is employ | adopted (patent document 1 grade | etc.,). The method of impregnating and curing the resin in the pores of the sintered body is performed by resin impregnation, removal of excess resin, and resin curing. Organic monomer type impregnating agent, organic polymer type impregnating agent, solvent cutting A mold impregnating agent and an aqueous emulsion impregnating agent are used (Patent Document 2, etc.). Furthermore, after the resin is impregnated into the pores of the sintered body and cured and sealed, the plastic body is put into the mold and pressure is applied, so that the pores generated due to the hardening shrinkage of the resin, etc. It has also been proposed to reduce or close the gap (Patent Document 3).
上記焼結動圧軸受を高密度に成形する方法は、原料粉末を圧縮成形する際の加圧力を大きくして行うが、成形体に蓄積する歪み量が大きく、寸法精度が悪くなるという問題がある。また再圧縮により寸法を矯正するとしても、素材が高密度であるため変形し難く、寸法を矯正しきれない。また、近年情報機器に使用される動圧軸受は小型化しており、軸受を各種のブラストやタンブラー処理で封孔する方法はメディアを軸受内部に供給し難く、また焼結軸受の端面および／または内径面に形成した動圧溝の形状が損なわれるという問題がある。 The method for forming the sintered dynamic pressure bearing at a high density is performed by increasing the applied pressure when the raw material powder is compression-molded, but there is a problem that the strain amount accumulated in the molded body is large and the dimensional accuracy is deteriorated. is there. Even if the dimensions are corrected by re-compression, the material is dense and hardly deformed, and the dimensions cannot be corrected. In recent years, hydrodynamic bearings used in information equipment have been downsized, and the method of sealing the bearings with various blasting and tumbling processes makes it difficult to supply media into the bearings, and the end surfaces of sintered bearings and / or There is a problem that the shape of the dynamic pressure groove formed on the inner diameter surface is impaired.
樹脂を用いて焼結体の気孔を封止する方法は、上記のような問題がなく、また製造効率が他の封孔方法に対して比較的良い。しかし、焼結体の気孔中に含浸された樹脂が硬化するときに収縮するため、液状樹脂の含浸量及び樹脂硬化の際の収縮率のバラツキにより、表面開口率又は封孔度合を安定化し難いという問題がある。特に流体として潤滑油等を用い、焼結動圧軸受を組み込んだ軸受ユニットに潤滑油を供給する場合、封孔度合いがばらつくと焼結動圧軸受の潤滑油吸収量がばらつくこととなり、最悪の場合、軸と軸受との間の潤滑油がなくなるため、個別に潤滑油の吸収度合いにより調整して供給しなければならなくなる。焼結動圧軸受の内部まで気孔全体に液状樹脂を含浸すれば潤滑油吸収量のばらつきを小さくすることはできるが、時間がかかるとともに吸収量を安定化することはできない。 The method of sealing the pores of the sintered body using a resin does not have the above-mentioned problems, and the production efficiency is relatively good compared to other sealing methods. However, since the resin impregnated in the pores of the sintered body shrinks when cured, it is difficult to stabilize the surface opening ratio or the degree of sealing due to variations in the amount of liquid resin impregnated and the shrinkage rate during resin curing. There is a problem. In particular, when lubricating oil is used as a fluid and lubricating oil is supplied to a bearing unit incorporating a sintered dynamic pressure bearing, if the degree of sealing varies, the amount of absorbed lubricating oil in the sintered dynamic pressure bearing varies, which is the worst. In this case, since there is no lubricating oil between the shaft and the bearing, it is necessary to individually adjust and supply the oil according to the degree of absorption of the lubricating oil. If the entire pores are impregnated with the liquid resin up to the inside of the sintered dynamic pressure bearing, the dispersion of the lubricating oil absorption amount can be reduced, but it takes time and the absorption amount cannot be stabilized.
上記課題を克服するため、特許文献３では樹脂の硬化収縮等に起因して生じる気孔内の隙間を塑性加工により封孔することを提案するが、工程が追加されることとなりコストの増加は免れない。また、工程の追加を避けるため樹脂含浸後の塑性加工工程と軸受内径面への動圧溝の形成工程を兼ねさせることも考えられるが、この場合には焼結体の気孔中で硬化した樹脂が焼結体の変形能を損ない精度良い動圧溝を形成することができない。 In order to overcome the above problems, Patent Document 3 proposes sealing the gaps in the pores caused by the curing shrinkage of the resin by plastic working, but an additional process is added and the increase in cost is avoided. Absent. Moreover, in order to avoid the addition of a process, it is possible to combine the plastic working process after impregnation with the resin and the process of forming the dynamic pressure groove on the inner diameter surface of the bearing. In this case, the resin cured in the pores of the sintered body However, the deformability of the sintered body is impaired and a dynamic pressure groove cannot be formed with high accuracy.
本発明は以上のような課題を解消すること、すなわち気孔内の隙間をより縮小し、又は閉塞した焼結動圧軸受を、少ない工程でかつ品質を低下させることなく安定した製造を可能にする焼結動圧軸受の製造方法を提供することを目的とし、潤滑油吸収がより少ない焼結動圧軸受を提供することを目的とする。 The present invention eliminates the above-described problems, that is, enables a stable production of a sintered hydrodynamic bearing with a reduced gap or closed pores in fewer steps and without reducing the quality. It aims at providing the manufacturing method of a sintered dynamic pressure bearing, and aims at providing a sintered dynamic pressure bearing with less lubricating oil absorption.
本発明の焼結動圧軸受の製造方法は、原料粉末を圧縮成形する成形工程と、前記成形工程により得られた成形体を焼結する焼結工程と、前記焼結工程により得られた多孔質焼結体の気孔に液状の樹脂を含浸し、前記液状の樹脂を気孔中で硬化して封孔処理する樹脂含浸工程と、を含む焼結動圧軸受の製造方法において、前記多孔質焼結体は、気孔率が５〜２０％であり、かつ２０質量％以上のＣｕを含有するとともに、前記液状の樹脂は、アクリル酸エステルまたはメタクリル酸エステルを主成分とし１.０質量％以下の有機過酸化物を含有する嫌気性樹脂のモノマーであることを特徴とする。 The method for producing a sintered hydrodynamic bearing according to the present invention includes a molding step of compression molding raw material powder, a sintering step of sintering a molded body obtained by the molding step, and a porous material obtained by the sintering step. A method for producing a sintered hydrodynamic bearing comprising: impregnating a liquid resin into pores of a porous sintered body, and impregnating the liquid resin with pores by curing the liquid resin in the pores. The bonded body has a porosity of 5 to 20% and contains 20% by mass or more of Cu, and the liquid resin has an acrylic acid ester or a methacrylic acid ester as a main component and is 1.0% by mass or less. It is a monomer of an anaerobic resin containing an organic peroxide.
また本発明の焼結動圧軸受は、焼結金属により構成され、軸受端面と軸受内径面の少なくとも一方に動圧を発生させる動圧溝が形成された焼結動圧軸受において、素材となる多孔質焼結体の気孔率が５〜２０％であり、前記多孔質焼結体の表面および表面近傍の気孔中に樹脂が含浸されて気孔が封止されているとともに、前記樹脂がアクリル酸エステルまたはメタクリル酸エステルを主成分とする嫌気性樹脂のポリマーであることを特徴とする。 The sintered hydrodynamic bearing of the present invention is a material in a sintered hydrodynamic bearing which is made of a sintered metal and has dynamic pressure grooves formed on at least one of the bearing end face and the bearing inner diameter face. The porosity of the porous sintered body is 5 to 20%, and the pores are sealed by impregnating the pores in the surface of the porous sintered body and in the vicinity of the surface, and the resin is acrylic acid. It is a polymer of an anaerobic resin mainly composed of ester or methacrylic acid ester.
本発明の焼結動圧軸受の製造方法によれば、焼結動圧軸受の表面および表面近傍の気孔中で含浸したモノマーが活性になり重合して気孔を封止するので、内部まで液状の樹脂を到達させる必要がなく短時間で封孔を行える。また、含浸時より気孔内部で硬化が始まるため収縮した隙間に新たにモノマーが含浸され封孔が確実かつ安定に行える。本発明の製造方法により得られる焼結動圧軸受は上記の作用により焼結体の気孔が封止されているので、流体として潤滑油等を用いる場合でも潤滑油の吸収がほとんどなく、また使用時に動圧の抜けがないという優れた効果を有する。 According to the method for manufacturing a sintered dynamic pressure bearing of the present invention, the monomer impregnated in the pores near the surface of the sintered dynamic pressure bearing becomes active and polymerizes to seal the pores. Sealing can be performed in a short time without having to reach the resin. Further, since the curing starts inside the pores from the time of impregnation, the monomer is newly impregnated into the contracted gap, and the sealing can be performed reliably and stably. Since the sintered dynamic pressure bearing obtained by the manufacturing method of the present invention has the pores of the sintered body sealed by the above-described action, there is almost no absorption of the lubricating oil even when lubricating oil is used as the fluid. Sometimes it has an excellent effect that there is no loss of dynamic pressure.
本発明の焼結動圧軸受の製造方法においては、樹脂含浸を行う多孔質焼結体として気孔率が５〜２０％のものを用いる。多孔質焼結体の気孔率が５％よりも小さい、すなわち多孔質焼結体の密度比が９５％以上の高密度であると、軸受内径面への動圧溝の形成が精度良く行えなくなる。一方、多孔質焼結体の気孔率が２０％よりも大きいと軸受の強度の低下が顕著となる。 In the method for producing a sintered dynamic pressure bearing of the present invention, a porous sintered body to be impregnated with a resin having a porosity of 5 to 20% is used. If the porosity of the porous sintered body is smaller than 5%, that is, if the density ratio of the porous sintered body is a high density of 95% or more, formation of dynamic pressure grooves on the inner diameter surface of the bearing cannot be performed with high accuracy. . On the other hand, if the porosity of the porous sintered body is larger than 20%, the strength of the bearing is significantly reduced.
また、本発明の焼結動圧軸受の製造方法においては、焼結体の気孔に含浸する液状の樹脂として、アクリル酸エステルまたはメタクリル酸エステルを主成分とし、１.０質量％以下の有機過酸化物を含有する嫌気性樹脂のモノマーを用いる。アクリル酸エステルまたはメタクリル酸エステルを主成分とする樹脂は潤滑油との反応性が低く、かつ適当な強度を有しているため、気孔を樹脂により封孔した焼結動圧軸受として潤滑油中で使用したとき、潤滑油と反応して潤滑特性を劣化させたり、樹脂が劣化して潤滑油中に剥離脱落することがないので好適である。
アクリル酸エステルまたはメタクリル酸エステルを主成分とする嫌気性樹脂のモノマーとは、嫌気性接着剤のモノマーとして公知であるアクリル酸またはメタクリル酸エステル、具体的にはポリグルコールジメタクリレート、エポキシアクリレート、エポキシメタクリレート、ウレタンアクリレート、ウレタンメタクリレート等のアクリル酸またはメタクリル酸エステルを含有し、必要によりその他のアクリル酸またはメタクリル酸エステルを含有するモノマーである。なお、本願においては、発明の効果を損なわない限り、これらのモノマー以外にも、嫌気性樹脂の改質を目的とするその他のモノマーを含有していても差し支えない。
In the method for producing a sintered dynamic pressure bearing of the present invention, the liquid resin impregnated in the pores of the sintered body is mainly composed of an acrylate ester or a methacrylate ester, and an organic solvent having a mass of 1.0% by mass or less. An anaerobic resin monomer containing an oxide is used. Resin mainly composed of acrylic acid ester or methacrylic acid ester has low reactivity with lubricating oil and has appropriate strength, so it can be used as a sintered hydrodynamic bearing with pores sealed with resin. When used in, it is preferable because it does not react with the lubricating oil to deteriorate the lubrication characteristics, or the resin does not deteriorate and peel off into the lubricating oil.
An anaerobic resin monomer mainly composed of acrylic acid ester or methacrylic acid ester is acrylic acid or methacrylic acid ester known as an anaerobic adhesive monomer, specifically polyglycol dimethacrylate, epoxy acrylate, epoxy It is a monomer containing acrylic acid or methacrylic acid ester such as methacrylate, urethane acrylate, urethane methacrylate, etc., and if necessary, containing other acrylic acid or methacrylic acid ester. In addition, in this application, as long as the effect of the invention is not impaired, in addition to these monomers, other monomers intended to modify anaerobic resins may be contained.
ところで、嫌気性樹脂は、前記モノマー中に過酸化物触媒を含有するもので、空気が遮断された状態で過酸化物触媒が金属イオンによって遊離基に変化し、この遊離基によってモノマーが重合して交差連結した強固な高分子を形成するものである。一方、大気中では一定の酸素の供給により安定しているため遊離基が生成せず、重合反応は開始されない。このような嫌気性樹脂において過酸化物触媒は、重合反応の開始剤として重要な意味を持つ。すなわち、過酸化物触媒が金属イオンと反応し易いものであると重合反応は活性に進行するが、金属イオンと反応し難いものであると重合反応は緩やかに進行することとなる。 By the way, the anaerobic resin contains a peroxide catalyst in the monomer, and the peroxide catalyst is converted into a free radical by a metal ion in a state where air is blocked, and the monomer is polymerized by the free radical. To form a cross-linked strong polymer. On the other hand, since it is stable in the atmosphere by the supply of constant oxygen, free radicals are not generated and the polymerization reaction is not started. In such anaerobic resins, the peroxide catalyst has an important meaning as an initiator for the polymerization reaction. That is, if the peroxide catalyst is easily reactive with metal ions, the polymerization reaction proceeds actively, but if it is difficult to react with metal ions, the polymerization reaction proceeds slowly.
この観点より本発明においては、過酸化物触媒として金属イオンと反応しやすい有機過酸化物を使用するとともに、含浸する多孔質焼結体として金属イオンを発生しやすいＣｕを２０質量％以上含有するものを組み合わせることを骨子とする。すなわち、本発明の焼結動圧軸受の製造方法においては、金属イオンと反応しやすい有機過酸化物を過酸化物触媒として０.１〜１.０質量％を含有する嫌気性樹脂のモノマーを、金属イオンを発生しやすいＣｕを２０質量％以上含有する多孔質焼結体の気孔中に含浸すると、嫌気性樹脂のモノマーは気孔内壁に取り囲まれることとなり、多量の金属イオンの供給を受けてモノマーの含浸初期より上記重合反応が活性に行われる。またモノマーは重合反応により収縮してポリマーとなるが、収縮した隙間にさらにモノマーが含浸されるため、封孔が確実に行える。 From this viewpoint, in the present invention, an organic peroxide that easily reacts with metal ions is used as a peroxide catalyst, and 20 mass% or more of Cu that easily generates metal ions is contained as a porous sintered body to be impregnated. The essence is to combine things. That is, in the method for producing a sintered hydrodynamic bearing according to the present invention, an anaerobic resin monomer containing 0.1 to 1.0% by mass using an organic peroxide that easily reacts with metal ions as a peroxide catalyst. When the pores of the porous sintered body containing 20% by mass or more of Cu, which easily generates metal ions, are impregnated, the anaerobic resin monomer is surrounded by the pore inner walls, and a large amount of metal ions is supplied. The polymerization reaction is carried out actively from the initial impregnation of the monomer. In addition, the monomer is shrunk by the polymerization reaction to become a polymer. However, since the monomer is further impregnated in the shrunk gap, the sealing can be reliably performed.
上記の反応の活性をより向上するため、過酸化物触媒は有機過酸化物の中でもハイドロパーオキサイド類を用いることが好ましい。ハイドロパーオキサイド類には、ｔ−ブチルハイドロパーオキサイド、クメンハイドロパーオキサイド、ジ−イソプロピルパーオキサイド、ｐ−メンタンハイドロパーオキサイド、１,１,３,３−テトラメチルブチルハイドロパーオキサイド、ベンゾイルパーオキサイド等があるが、これらのいずれも使用可能で、複数用いてもよい。 In order to further improve the activity of the above reaction, it is preferable to use hydroperoxides as the peroxide catalyst among organic peroxides. Hydroperoxides include t-butyl hydroperoxide, cumene hydroperoxide, di-isopropyl peroxide, p-menthane hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, benzoyl peroxide However, any of these can be used and a plurality of them may be used.
また、多孔質焼結体のＣｕ含有量は２０質量％以上で、上記反応を活性に行うことができるが、Ｃｕ含有量が４０質量％以上であるとより好ましい。さらにＣｕの添加形態については、３〜３０質量％の銅箔粉を用いることが推奨される。例えば鉄銅系の多孔質焼結体を製造する場合に、原料粉末に３〜３０質量％の銅箔粉を使用すると、銅箔粉が鉄粉表面に付着して鉄粉表面を覆う状態となる。このような原料粉末を成形、焼結して得られる多孔質焼結体では、気孔内壁に露出するＦｅの割合が大幅に低下して、金属イオンを発生し易いＣｕの露出量が増加するためＣｕ含有量が少なくてもＣｕイオンの供給量を増加することができ、上記の反応をより一層活性に行うことができる。ただし銅箔粉の使用は３質量％に満たないと鉄粉を被覆する効果に乏しく、３０質量％を超えて与えても鉄粉被覆の効果の向上がそれ以上は認められないのみならず、コスト増の一因となるため３〜３０質量％が適正な範囲である。 Moreover, although Cu content of a porous sintered compact is 20 mass% or more and the said reaction can be performed actively, it is more preferable in Cu content being 40 mass% or more. Furthermore, about the addition form of Cu, it is recommended to use 3-30 mass% copper foil powder. For example, when manufacturing a copper-sintered porous sintered body, if 3 to 30% by mass of copper foil powder is used as the raw material powder, the copper foil powder adheres to the iron powder surface and covers the iron powder surface. Become. In a porous sintered body obtained by molding and sintering such a raw material powder, the ratio of Fe exposed to the inner wall of the pores is greatly reduced, and the amount of exposed Cu that easily generates metal ions is increased. Even if there is little Cu content, the supply amount of Cu ion can be increased and said reaction can be performed much more actively. However, if the use of copper foil powder is less than 3% by mass, the effect of coating iron powder is poor, and even if it exceeds 30% by mass, the improvement of the effect of iron powder coating is not recognized any more, Since it becomes a cause of an increase in cost, 3-30 mass% is an appropriate range.
多孔質焼結体の内部では上記のように重合反応が活性に進行して気孔が封止されるが、多孔質焼結体の表面は内部に比して表面積が小さいため金属イオンの供給量が乏しく、上記重合反応が表面では進行し難いため、含浸槽より多孔質焼結体を取り出した後、水洗して表面に付着した樹脂を容易に除去することができる。 Inside the porous sintered body, the polymerization reaction proceeds actively as described above, and the pores are sealed. However, since the surface of the porous sintered body has a smaller surface area than the inside, the supply amount of metal ions Since the polymerization reaction hardly proceeds on the surface, the porous sintered body can be taken out of the impregnation tank and then washed with water to easily remove the resin adhering to the surface.
上記の重合反応を適正な範囲で活性に行うためには、嫌気性樹脂に添加する有機過酸化物は０.１質量％以上とする必要がある。０.１質量％に満たないと重合反応が活性にならず、気孔の封止が不十分となる。一方、１.０質量％を超えて添加すると、上記反応が活性になりすぎて、樹脂による気孔の封止が多孔質焼結体の表層のごく浅い領域のみに止まるため、封孔が破れ易くなるとともに、多孔質焼結体の表面で樹脂が固化して余剰の樹脂分の除去が困難になる。 In order to perform the above polymerization reaction in an appropriate range, the organic peroxide added to the anaerobic resin needs to be 0.1% by mass or more. If it is less than 0.1% by mass, the polymerization reaction will not be active, and the pores will be insufficiently sealed. On the other hand, when the amount exceeds 1.0% by mass, the above reaction becomes too active, and pore sealing by the resin stops only in a very shallow region of the surface layer of the porous sintered body, so that the sealing is easily broken. At the same time, the resin is solidified on the surface of the porous sintered body, and it becomes difficult to remove excess resin.
上記の嫌気性樹脂モノマーの多孔質焼結体の気孔への含浸は真空含浸法を用いる（特許文献２）。すなわち、含浸槽内の嫌気性樹脂モノマー中に多孔質焼結体を浸漬し、含浸槽を減圧して多孔質焼結体の気孔中の空気を除去した後、大気圧まで復帰させてモノマーを気孔中に吸引させることで含浸する方法、および、含浸槽内のステージ上に多孔質焼結体を載置して含浸槽内を減圧し多孔質焼結体の気孔中の空気を除去し、次いでステージ全体を降下させて含浸槽内の嫌気性樹脂モノマー中に多孔質焼結体を浸漬した後、大気圧まで復帰させてモノマーを気孔中に吸引することにより含浸する方法等の真空含浸法が適用される。この時、大気圧まで復帰した後さらに加圧してもよい。ここで、上記の重合反応を活性に行うためには多孔質焼結体を含浸槽に浸漬した後の減圧度を２０Ｐａ以下として行うことが好ましい。上記のように嫌気性樹脂は酸素の供給が遮断されることで重合反応が開始されるものであるから、減圧時の圧力が高いとその分酸素が供給されるので重合反応が進行し難く、強固な気孔の封止が行えなくなる。 A vacuum impregnation method is used to impregnate the pores of the porous sintered body with the anaerobic resin monomer (Patent Document 2). That is, the porous sintered body is immersed in the anaerobic resin monomer in the impregnation tank, the impregnation tank is decompressed to remove air in the pores of the porous sintered body, and then returned to atmospheric pressure to restore the monomer. A method of impregnating by sucking into the pores, and placing the porous sintered body on the stage in the impregnation tank to reduce the pressure in the impregnation tank and removing air in the pores of the porous sintered body; Then, the entire stage is lowered and the porous sintered body is immersed in the anaerobic resin monomer in the impregnation tank, and then returned to atmospheric pressure, and the monomer is impregnated by sucking it into the pores. Applies. At this time, the pressure may be further increased after returning to atmospheric pressure. Here, in order to perform the above polymerization reaction actively, it is preferable that the degree of vacuum after dipping the porous sintered body in the impregnation tank is 20 Pa or less. As described above, the anaerobic resin starts the polymerization reaction by shutting off the supply of oxygen, so if the pressure during decompression is high, oxygen is supplied accordingly, so the polymerization reaction is difficult to proceed. It becomes impossible to seal the pores firmly.
樹脂含浸後は表面の余剰の樹脂を洗浄して除去するが、その後樹脂を含浸した多孔質焼結体を加熱することにより含浸した樹脂を完全に硬化することが効果的である。すなわち、上記のように気孔は含浸時に封孔されるが、金属イオンが供給される気孔内壁から先に樹脂が硬化するため、硬化後収縮した隙間に新たに含浸されたモノマーの一部には先に硬化した樹脂により金属イオンが届かずモノマーのまま残留する虞があるため、洗浄後加熱し残留したモノマーをも硬化させることにより気孔の封止がより一層確実なものとなる。このとき過酸化物触媒として有機過酸化物を用いたものは、反応が活性に行えるため、樹脂硬化のための加熱温度も低くて済み、室温から加熱温度まで昇温する間の樹脂の熱膨張に伴う未硬化モノマーの吹き出しが少なくなるという利点も有する。 After the resin impregnation, the excess resin on the surface is washed away and it is effective to completely cure the impregnated resin by heating the porous sintered body impregnated with the resin thereafter. That is, as described above, the pores are sealed when impregnated, but the resin hardens first from the inner wall of the pores to which metal ions are supplied. Since the metal ions do not reach by the previously cured resin and may remain as a monomer, the pores can be sealed more reliably by heating after washing and curing the remaining monomer. At this time, those using organic peroxide as the peroxide catalyst can react actively, so the heating temperature for curing the resin can be low, and the thermal expansion of the resin during the temperature rise from room temperature to the heating temperature. There is also an advantage that blowout of uncured monomer associated with is reduced.
また上記のモノマーの残留を防ぐため、一般の嫌気性接着剤で用いられているような１質量％以下の有機金属化合物からなる硬化促進剤を併用してもよい。この場合には気孔内壁で硬化収縮した隙間に新たなモノマーが含浸されてもモノマー中の有機金属化合物の金属イオンによりモノマーが重合硬化できるようになる。ただし過剰な有機金属化合物の添加は上記のモノマー含浸時の重合反応を過剰に引き起こすため、その添加は１質量％以下に止めるべきである。用いられる有機金属化合物としてはジメチル銅酸リチウム、ジアセチルアセトン銅、炭化カルシウム、フェニルリチウム等が挙げられる。 Further, in order to prevent the monomer from remaining, a curing accelerator composed of an organic metal compound of 1% by mass or less as used in a general anaerobic adhesive may be used in combination. In this case, the monomer can be polymerized and cured by the metal ions of the organometallic compound in the monomer, even if a new monomer is impregnated in the gap which has been cured and shrunk on the pore inner wall. However, the addition of an excessive organometallic compound causes an excessive polymerization reaction during the above-mentioned monomer impregnation, so the addition should be stopped to 1% by mass or less. Examples of the organometallic compound used include lithium dimethylcuprate, diacetylacetone copper, calcium carbide, and phenyllithium.
なお本願において嫌気性樹脂はモノマーの他に、前記の有機過酸化物および好ましくは硬化促進剤を配合するが、本発明の効果を損なわない範囲で、これ以外に有機および／または無機充填剤、粘度調節剤、安定剤などの添加剤を配合することができる。 In the present application, the anaerobic resin contains the above-mentioned organic peroxide and preferably a curing accelerator in addition to the monomer, but within the range not impairing the effects of the present invention, other organic and / or inorganic fillers, Additives such as viscosity modifiers and stabilizers can be blended.
以上の樹脂含浸工程は、動圧溝を成形する時に実施して、後に寸法調整および動圧溝形成の再圧工程を行わない場合は焼結工程の後に行えばよい。しかし、焼結工程の後に再圧工程を行う場合には、多孔質焼結体の気孔中で硬化した樹脂が焼結体の変形能を低下させて、再圧工程の効果が得難くなることから、樹脂含浸工程は寸法調整および動圧溝形成の再圧工程の後に行う必要がある。 The above resin impregnation step is performed when the dynamic pressure groove is formed, and may be performed after the sintering step when the dimensional adjustment and the dynamic pressure groove formation re-pressing step are not performed later. However, when the re-pressing process is performed after the sintering process, the resin hardened in the pores of the porous sintered body reduces the deformability of the sintered body, making it difficult to obtain the effect of the re-pressing process. Therefore, the resin impregnation step needs to be performed after the dimensional adjustment and the repressurization step for forming the dynamic pressure groove.
以上の本発明の焼結動圧軸受の製造方法により得られる焼結動圧軸受は、表面および表面近傍の気孔中にアクリル酸エステルまたはメタクリル酸エステルを主成分とする嫌気性樹脂のポリマーが含浸硬化されて気孔が強固かつ確実に封孔され、潤滑油を流体として用いた流体動圧軸受として、動圧の抜けおよび潤滑油の吸収がない優れたものとなる。 The sintered hydrodynamic bearing obtained by the method for producing a sintered hydrodynamic bearing of the present invention is impregnated with a polymer of an anaerobic resin mainly composed of an acrylate ester or a methacrylate ester in the pores near the surface. As a fluid dynamic pressure bearing using the lubricating oil as a fluid, it is excellent in that it does not lose its dynamic pressure and absorbs the lubricating oil.
原料粉末として、鉄粉、電解銅粉、銅箔粉、錫粉、黒鉛粉を用意し、表１に示す配合割合で添加混合して原料粉末を調製した後、内径２.５ｍｍ、外径７ｍｍ、高さ５ｍｍの軸受形状に密度比８５％になるよう圧縮成形し、アンモニア分解ガス雰囲気中７７０℃で３０分保持して焼結を行い、次いで寸法調整再圧工程と、軸受内径面に五円弧形状の動圧形状を付与する動圧溝形成再圧工程を施し多孔質焼結体２２個を製造した。 As raw material powder, iron powder, electrolytic copper powder, copper foil powder, tin powder, and graphite powder were prepared, and added and mixed at the mixing ratio shown in Table 1 to prepare the raw material powder, and then an inner diameter of 2.5 mm and an outer diameter of 7 mm. , Compression molded to a bearing shape of 5 mm in height to a density ratio of 85%, held in an ammonia decomposition gas atmosphere at 770 ° C. for 30 minutes for sintering, and then subjected to dimensional adjustment re-pressing step, Twenty-two porous sintered bodies were manufactured by applying a dynamic pressure groove forming / repressing step to give an arc-shaped dynamic pressure shape.
また、嫌気性樹脂としてポリグリコールジメタクリレートを主成分とし、過酸化物触媒としてクメンハイドロパーオキサイドを０.８質量％含有するヘンケル社製ＰＭＳ−５０Ｅ（商品名）を用意した（以降、発明例と称す）。また比較のため嫌気性樹脂として特許文献１に記載されているレジノール９０Ｃ（商品名：ヘンケル社製）、すなわち、ポリグリコールジメタクリレートを主成分とし有機過酸化物の替わりにアゾ化合物（２,２−アゾビス（２−メチルブチロニトリル））を０.３質量％含有する樹脂を用意した（以降、比較例と称す）。これらの嫌気性樹脂のモノマーで満たした含浸槽に上記により作製した多孔質焼結体を各々１１個づつ浸漬し、含浸槽を１３Ｐａに減圧して１分間保持し、次いで７３５ｋＰａに加圧して多孔質焼結体の気孔中に嫌気性樹脂のモノマーを含浸した。その後、硬質焼結体の表面に付着した嫌気性樹脂のモノマーを洗浄除去し、発明例については５０℃、比較例については９０℃の温水中に保持（いずれも樹脂メーカ推奨温度）して樹脂の硬化を行った。
樹脂含浸工程により得られた試料から組織観察用に各々１個の試料を取り除き、残りの発明例１０個、比較例１０個の試料についてステンレス製の有底形状ハウジングに圧入し、潤滑油を注入した。
Moreover, Henkel PMS-50E (trade name) containing polyglycol dimethacrylate as a main component as an anaerobic resin and 0.8% by mass of cumene hydroperoxide as a peroxide catalyst was prepared (hereinafter, invention examples) Called). For comparison, Resinol 90C (trade name: manufactured by Henkel) described in Patent Document 1 as an anaerobic resin, that is, an azo compound (2, 2) containing polyglycol dimethacrylate as a main component instead of an organic peroxide. A resin containing 0.3% by mass of azobis (2-methylbutyronitrile) was prepared (hereinafter referred to as a comparative example). 11 pieces of each of the porous sintered bodies produced as described above are immersed in an impregnation tank filled with these anaerobic resin monomers, and the impregnation tank is decompressed to 13 Pa and held for 1 minute, and then pressurized to 735 kPa and porous. The pores of the sintered material were impregnated with an anaerobic resin monomer. Thereafter, the anaerobic resin monomer adhering to the surface of the hard sintered body is washed and removed, and the resin is retained in warm water at 50 ° C. for the inventive example and 90 ° C. for the comparative example (both are recommended by the resin manufacturer) Was cured.
Remove one sample each for tissue observation from the sample obtained by the resin impregnation step, press the remaining 10 samples of the invention and 10 samples of the comparative example into the bottomed housing made of stainless steel, and inject lubricating oil. did.
これらの試料について潤滑油の吸収の有無を確認したところ、発明例の試料１０個についてはいずれも潤滑油の吸収は認められなかった。一方、比較例の試料１０個については全てに潤滑油の吸収が認められ、またその吸収量についてもばらつきが認められた。 When the presence or absence of absorption of lubricating oil was confirmed for these samples, no absorption of lubricating oil was observed for any of the 10 samples of the inventive examples. On the other hand, the absorption of the lubricating oil was recognized in all of the 10 samples of the comparative examples, and variations were also observed in the amount of absorption.
組織観察用の発明例および比較例の試料について切断、研磨して断面の封孔状態を顕微鏡により観察したところ、発明例の試料については、表面および表面近傍の気孔は樹脂で封孔されていたが、試料内部の気孔には樹脂が含浸されていなかった。一方、比較例の試料では試料全体の気孔が樹脂で満たされており、内部の気孔まで樹脂が含浸されていた。 The samples of the inventive examples and comparative examples for tissue observation were cut and polished, and the sealed state of the cross section was observed with a microscope. As for the samples of the inventive examples, the surface and the pores in the vicinity of the surface were sealed with resin. However, the pores inside the sample were not impregnated with resin. On the other hand, in the sample of the comparative example, the pores of the entire sample were filled with the resin, and the resin was impregnated to the internal pores.
これらの結果より、過酸化物触媒として有機過酸化物を用いた場合は、重合反応が活性で、含浸初期より重合反応が生じた結果、試料内部の気孔まで樹脂が含浸されなかったものと考える。またこの活性な反応により、気孔の封止が確実かつ強固に行われ潤滑油の吸収がなかったものと考える。一方、有機過酸化物触媒の替わりにアゾ化合物を用いた場合は重合反応が緩やかで、このため内部まで樹脂が含浸されたものと考える。またこのような緩やかな反応の結果、樹脂の硬化が遅れ、洗浄後の加熱で初めて全体の樹脂が硬化する結果、樹脂の硬化収縮にともなって気孔に隙間が生じて潤滑油を吸収するものと考える。 From these results, it is considered that when organic peroxide is used as the peroxide catalyst, the polymerization reaction is active, and as a result of the polymerization reaction from the beginning of the impregnation, the resin was not impregnated to the pores inside the sample. . Further, it is considered that the pores are surely and firmly sealed by this active reaction and the lubricating oil is not absorbed. On the other hand, when an azo compound is used instead of the organic peroxide catalyst, the polymerization reaction is slow, and it is considered that the resin is impregnated to the inside. In addition, as a result of such a slow reaction, the resin is delayed in curing, and the entire resin is cured only after heating after washing. As a result of the resin being cured and contracted, voids are generated in the pores to absorb the lubricating oil. Think.
以上より、鉄銅系の焼結動圧軸受の気孔の封止を嫌気性樹脂を含浸して行う場合、過酸化物触媒として有機過酸化物を用いたものは、含浸初期より重合反応を活性に行え、樹脂による気孔の封止を確実かつ強固に行えることが確認された。 From the above, when sealing pores of ferrous sintered hydrodynamic bearings by impregnating with anaerobic resin, those using organic peroxide as the peroxide catalyst activated the polymerization reaction from the beginning of impregnation. It was confirmed that the pores can be reliably and firmly sealed with the resin.
本発明の製造方法により得られる焼結軸受は、特に軸受表面あるいは動圧溝面を封孔した焼結動圧軸受であり、精密回転を必要とする磁気ディスク装置や光ディスク装置のディスクドライブモータおよびレーザプリンター用ポリゴンミラーモータなどに用いられる焼結動圧軸受として好適である。
The sintered bearing obtained by the manufacturing method of the present invention is a sintered dynamic pressure bearing in which a bearing surface or a dynamic pressure groove surface is sealed, and a magnetic disk device that requires precision rotation, a disk drive motor of an optical disk device, It is suitable as a sintered dynamic pressure bearing used for a polygon mirror motor for a laser printer or the like.
Claims (5)
前記多孔質焼結体は、気孔率が５〜２０％であり、かつ２０質量％以上のＣｕを含有するとともに、前記液状の樹脂は、アクリル酸エステルまたはメタクリル酸エステルを主成分とし、０.１〜１.０質量％の有機過酸化物を含有する嫌気性樹脂のモノマーであることを特徴とする焼結動圧軸受の製造方法。 A molding process for compression molding raw material powder, a sintering process for sintering the molded body obtained by the molding process, and a liquid resin is impregnated in the pores of the porous sintered body obtained by the sintering process. In a method for producing a sintered dynamic pressure bearing, including a resin impregnation step of curing and sealing the liquid resin in pores,
The porous sintered body has a porosity of 5 to 20% and contains 20% by mass or more of Cu, and the liquid resin is mainly composed of acrylic acid ester or methacrylic acid ester, and has a content of 0. A method for producing a sintered hydrodynamic bearing, wherein the monomer is an anaerobic resin monomer containing 1 to 1.0% by mass of an organic peroxide.
The method for producing a sintered dynamic pressure bearing according to any one of claims 1 to 4, wherein the raw material powder contains 3 to 30% by mass of copper foil powder.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012070383A1 (en) * | 2010-11-25 | 2012-05-31 | Ntn株式会社 | Race ring for rolling bearing, and rolling bearing |
| JP2013002524A (en) * | 2011-06-15 | 2013-01-07 | Ntn Corp | Fluid dynamic bearing device |
| WO2015045813A1 (en) * | 2013-09-24 | 2015-04-02 | Ntn株式会社 | Sintered metal bearing and fluid-dynamic bearing device provided with said bearing |
| CN113560578A (en) * | 2021-08-11 | 2021-10-29 | 苏州中耀科技有限公司 | Forming method of temporary metal mold |
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| JPH02160881A (en) * | 1987-12-25 | 1990-06-20 | Toagosei Chem Ind Co Ltd | Adhesive composition |
| JPH09266227A (en) * | 1996-03-28 | 1997-10-07 | Matsushita Electric Ind Co Ltd | Bonding method of electronic parts |
| JPH1162948A (en) * | 1997-08-18 | 1999-03-05 | Ntn Corp | Dynamic pressure air bearing |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02160881A (en) * | 1987-12-25 | 1990-06-20 | Toagosei Chem Ind Co Ltd | Adhesive composition |
| JPH09266227A (en) * | 1996-03-28 | 1997-10-07 | Matsushita Electric Ind Co Ltd | Bonding method of electronic parts |
| JPH1162948A (en) * | 1997-08-18 | 1999-03-05 | Ntn Corp | Dynamic pressure air bearing |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2012070383A1 (en) * | 2010-11-25 | 2012-05-31 | Ntn株式会社 | Race ring for rolling bearing, and rolling bearing |
| JP2012127492A (en) * | 2010-11-25 | 2012-07-05 | Ntn Corp | Race ring for rolling bearing, and rolling bearing |
| JP2013002524A (en) * | 2011-06-15 | 2013-01-07 | Ntn Corp | Fluid dynamic bearing device |
| WO2015045813A1 (en) * | 2013-09-24 | 2015-04-02 | Ntn株式会社 | Sintered metal bearing and fluid-dynamic bearing device provided with said bearing |
| JP2015064019A (en) * | 2013-09-24 | 2015-04-09 | Ntn株式会社 | Sintered metal bearing and fluid dynamic pressure bearing device including the same |
| US10415573B2 (en) | 2013-09-24 | 2019-09-17 | Ntn Corporation | Fluid-dynamic bearing device provided with a sintered metal bearing and a fan motor provided with the fluid-dynamic bearing device |
| CN113560578A (en) * | 2021-08-11 | 2021-10-29 | 苏州中耀科技有限公司 | Forming method of temporary metal mold |
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