JP3353152B2 - Ceramic bearings - Google Patents
Ceramic bearingsInfo
- Publication number
- JP3353152B2 JP3353152B2 JP07171592A JP7171592A JP3353152B2 JP 3353152 B2 JP3353152 B2 JP 3353152B2 JP 07171592 A JP07171592 A JP 07171592A JP 7171592 A JP7171592 A JP 7171592A JP 3353152 B2 JP3353152 B2 JP 3353152B2
- Authority
- JP
- Japan
- Prior art keywords
- bearing
- ceramic
- surface pressure
- contact surface
- crack
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Landscapes
- Rolling Contact Bearings (AREA)
Description
【０００１】[0001]
【産業上の利用分野】この発明は、無潤滑状態で使用さ
れるセラミック軸受に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic bearing used without lubrication.
【０００２】[0002]
【従来の技術】機械的要素の重要な一部である軸受に対
する性能要求は年々過酷になってきており、たとえば、
工作機械主軸などにおける高速回転性能やガスタービン
などにおける高温耐熱性、さらに特殊環境下での耐腐食
性など種々の性能の向上が要求されている。これらの要
求に対して、軸受素材の面からはセラミックスが従来の
軸受鋼に比べて優れており、セラミック軸受が広く使用
されるようになってきている。2. Description of the Related Art Performance requirements for bearings, which are an important part of mechanical elements, are becoming severer year by year.
Improvements in various performances such as high-speed rotation performance in machine tool spindles and the like, high-temperature heat resistance in gas turbines and the like, and corrosion resistance under special environments are required. To meet these requirements, ceramics are superior to conventional bearing steels in terms of bearing material, and ceramic bearings have been widely used.
【０００３】[0003]
【発明が解決しようとする課題】しかしながら、セラミ
ックスは、上述のような優れた性能を持ち合わせている
反面、脆性材料であるがために信頼性が低く、その性能
が十分生かされていないのが現状である。とくに、無潤
滑状態で使用されるセラミック軸受は、摩擦係数が大き
いため、摺動面の先在亀裂が伝播し、これが破壊の起因
となるという問題がある。However, although ceramics have the above-mentioned excellent performance, they are brittle materials, so they have low reliability and their performance has not been fully utilized. It is. In particular, a ceramic bearing used in an unlubricated state has a large friction coefficient, so that there is a problem that a pre-existing crack on a sliding surface propagates and causes breakage.
【０００４】この発明の目的は、上記の問題を解決し、
無潤滑状態でも亀裂の発生を抑制できる信頼性の高いセ
ラミック軸受を提供することにある。An object of the present invention is to solve the above problems,
It is an object of the present invention to provide a highly reliable ceramic bearing that can suppress cracks even in a non-lubricated state.
【０００５】[0005]
【課題を解決するための手段】この発明によるセラミッ
ク軸受は、無潤滑状態で使用されるセラミック軸受であ
って、軸受の接触面圧および軸受を構成するセラミック
ス材料の摩擦係数が、セラミック材料表面の先在亀裂長
さから求められた接触面圧および摩擦係数の安全領域内
にあることを特徴とするものである。SUMMARY OF THE INVENTION A ceramic bearing according to the present invention is a ceramic bearing used in a non-lubricated state, wherein the contact surface pressure of the bearing and the friction coefficient of the ceramic material constituting the bearing are lower than the surface of the ceramic material. The contact surface pressure and the friction coefficient obtained from the pre-existing crack length are within a safe range.
【０００６】[0006]
【作用】軸受を構成するセラミックス材料における亀裂
（クラック）の伝播は、破壊力学における応力拡大係数
で論じられる。すなわち、引張り型亀裂開口モードにお
ける先在亀裂（材料の表面に最初から存在する微小な亀
裂）が進展して、その応力拡大係数が破壊靭性値を越え
たときに亀裂が不安定伝播し破壊に至る。破壊靭性値は
材料によって特有の値であり、応力拡大係数はセラミッ
クス材料表面の先在亀裂長さ、軸受の接触面圧および軸
受を構成するセラミックス材料の摩擦係数の関数にな
る。したがって、先在亀裂長さをパラメータとして、応
力拡大係数が破壊靭性値と等しくなるときの摩擦係数と
接触面圧の関係がこれらの直交座標上で１つの臨界曲線
として求められる。そして、この臨界曲線の一方の側
（接触面圧および摩擦係数が小さい側）が安全領域、反
対側（接触面圧および摩擦係数が大きい側）が危険領域
となり、接触面圧および摩擦係数が安全領域になるよう
にすることにより、亀裂の成長が抑制され、亀裂による
脆性破壊が抑制される。The propagation of a crack in a ceramic material constituting a bearing is discussed by a stress intensity factor in fracture mechanics. In other words, pre-existing cracks (small cracks existing on the surface of the material from the beginning) in the tensile crack opening mode propagate, and when the stress intensity factor exceeds the fracture toughness value, the cracks propagate unstably and cause fracture. Reach. The fracture toughness is a value specific to each material, and the stress intensity factor is a function of the length of the pre-existing crack on the ceramic material surface, the contact surface pressure of the bearing, and the coefficient of friction of the ceramic material constituting the bearing. Therefore, using the pre-existing crack length as a parameter, the relationship between the friction coefficient and the contact surface pressure when the stress intensity factor becomes equal to the fracture toughness value is obtained as one critical curve on these orthogonal coordinates. One side of this critical curve (the side where the contact surface pressure and friction coefficient is small) is a safety region, and the other side (the side where the contact surface pressure and friction coefficient is large) is a danger region, and the contact surface pressure and the friction coefficient are safe. By forming the region, crack growth is suppressed, and brittle fracture due to the crack is suppressed.
【０００７】[0007]
【実施例】以下、図面を参照して、この発明の実施例に
ついて説明する。Embodiments of the present invention will be described below with reference to the drawings.
【０００８】図１はセラミック・スラスト玉軸受の例を
示しており、２つの軌道輪(11)(12)およびこれらの間に
配置された複数の玉(13)はセラミックス、たとえば、Ｙ
２Ｏ３とＡｌ２Ｏ３を助剤としてＨＩＰ（熱間静水圧加
圧焼結法）で製造された窒化けい素セラミックスよりな
る。FIG. 1 shows an example of a ceramic thrust ball bearing, in which two races (11) and (12) and a plurality of balls (13) disposed therebetween are made of ceramic, for example, Y.
It is made of silicon nitride ceramics manufactured by HIP (Hot Isostatic Pressing Sintering Method) using 2 O 3 and Al 2 O 3 as assistants.
【０００９】この軸受は、接触面圧およびこれを構成す
るセラミックス材料の摩擦係数がセラミックス材料表面
の先在亀裂長さから求められた安全領域内にあるような
条件で使用される。次に、この安全領域の求め方につい
て説明する。This bearing is used under such a condition that the contact surface pressure and the friction coefficient of the ceramic material constituting the contact surface pressure are within the safety range determined from the length of the pre-existing crack on the ceramic material surface. Next, a method of obtaining the safety region will be described.
【００１０】上述のように、軸受を構成するセラミック
ス材料における亀裂の伝播は破壊力学における応力拡大
係数で論じられ、引張り型亀裂開口モードにおける先在
亀裂の応力拡大係数ＫＩが材料の破壊靭性値ＫＩＣを越
えたときに破壊に至る。先在亀裂長さｃの応力拡大係数
ＫＩは、次の式(1)で表わされる。[0010] As described above, the crack in the ceramic material constituting the bearing propagation discussed stress intensity factor in fracture mechanics, stress intensity factor of preexisting <br/> cracks in the tensile-type crack opening mode K I is material When the fracture toughness value exceeds K IC , fracture occurs. Stress intensity factor K I preexisting crack length c is expressed by the following equation (1).
【００１１】ＫＩ＝Ｙσ（πｃ）０．５ …(1) ここで、Ｙは亀裂形状に依存する定数、σは無限遠方で
作用する一様応力である（図２参照）。図２において、
(14)は軸受を構成するセラミックス材料、(14a)はその
表面、(15)は材料表面(14a)の先在亀裂である。また、
材料表面(14a)上の転がり方向をＸ軸、材料表面(14a)上
のＸ軸と垂直な方向をＹ軸、Ｘ軸およびＹ軸と垂直な材
料(14)の内部方向をＺ軸とした。K I = Yσ (πc) 0.5 (1) where Y is a constant depending on the crack shape, and σ is a uniform stress acting at infinity (see FIG. 2). In FIG.
(14) is a ceramic material constituting the bearing, (14a) is its surface, and (15) is a pre-existing crack on the material surface (14a). Also,
The rolling direction on the material surface (14a) is the X axis, the direction perpendicular to the X axis on the material surface (14a) is the Y axis, and the internal direction of the material (14) perpendicular to the X and Y axes is the Z axis. .
【００１２】重ね合わせの原理から、無限遠方で作用す
る一様応力σは亀裂まわりの応力に置き換えることがで
き、次の式(2)に示すように接触面圧ｐとこの接触面圧
で無次元化された最大主応力の最大値σ０（μ）の積で
表わされる。From the principle of superposition, the uniform stress σ acting at infinity can be replaced by the stress around the crack. As shown in the following equation (2), the contact surface pressure p and the contact surface pressure It is expressed by the product of the maximum value σ 0 (μ) of the dimensioned maximum principal stress.
【００１３】σ＝ｐσ０（μ） …(2) σ０（μ）は摩擦係数μをパラメータとしており、ハミ
ルトンの応力解析式から次の式(3)で表わすことができ
る。Σ = pσ 0 (μ) (2) σ 0 (μ) uses the friction coefficient μ as a parameter and can be expressed by the following equation (3) from Hamilton's stress analysis equation.
【００１４】 σ０（μ）＝μ（４＋ν）π／８＋（１−２ν）／３ …(3) ここで、νはポアソン比であり、これは材料定数である
ので、図３に示すように、σ０（μ）は摩擦係数μの一
次関数となる。なお、図３には、窒化けい素セラミック
スの場合の摩擦係数μと最大主応力の最大値との関係を
示している。Σ 0 (μ) = μ (4 + ν) π / 8 + (1-2ν) / 3 (3) where ν is a Poisson's ratio, which is a material constant, and as shown in FIG. Σ 0 (μ) is a linear function of the friction coefficient μ. FIG. 3 shows the relationship between the coefficient of friction μ and the maximum value of the maximum principal stress in the case of silicon nitride ceramics.
【００１５】亀裂の不安定伝播の境界条件は応力拡大係
数ＫＩが材料の破壊靭性値ＫＩＣと等しくなることであ
り、したがって、これは次の式(4)で表わされる。The boundary condition for unstable propagation of a crack is that the stress intensity factor K I equals the fracture toughness value K IC of the material, and is therefore expressed by the following equation (4).
【００１６】 ＫＩ＝ＫＩＣ＝Ｙｐσ０（μ）（πｃ）０．５ …(4) このときのｐが臨界面圧となり、これは次の式(5)のよ
うに表わされる。K I = K IC = Ypσ 0 (μ) (πc) 0.5 (4) In this case, p is a critical surface pressure, which is represented by the following equation (5).
【００１７】 ｐ＝ＫＩＣ／Ｙσ０（μ）（πｃ）０．５ …(5) 式(5)より、先在亀裂長さｃをパラメータとして、臨界
面圧ｐを摩擦係数μで表わすことができる。このように
して表わした摩擦係数μと臨界面圧ｐとの関係が図４に
示されている。同図において、横軸は摩擦係数μ、縦軸
は接触面圧ｐを表わしており、曲線Ｐ１、Ｐ２およびＰ
３は先在亀裂長さｃが０．１、０．５および１．０μｍ
の場合の臨界面圧を示している。そして、各曲線Ｐ１、
Ｐ２およびＰ３より図の左下側（接触面圧および摩擦係
数の小さい側）が安全領域、反対の各曲線Ｐ１、Ｐ２お
よびＰ３より図の右上側（接触面圧および摩擦係数の大
きい側）が危険領域となっている。P = K IC / Yσ 0 (μ) (πc) 0.5 (5) From the equation (5), using the pre-existing crack length c as a parameter, expressing the critical surface pressure p by a friction coefficient μ. Can be. FIG. 4 shows the relationship between the friction coefficient μ and the critical surface pressure p thus expressed. In the figure, the horizontal axis represents the friction coefficient μ, and the vertical axis represents the contact surface pressure p, and the curves P 1 , P 2 and P
3 has a pre-existing crack length c of 0.1, 0.5 and 1.0 μm
Shows the critical surface pressure in the case of. And each curve P 1 ,
The lower left side of Fig than P 2 and P 3 (contact surface pressure and smaller in coefficient of friction) is safe area, in FIG from the curves P 1, P 2 and P 3 on the opposite upper right side (the contact surface of the pressure and friction coefficient The larger side is the danger area.
【００１８】軸受に使用されるセラミックス材料が決ま
れば、先在亀裂長さがわかり、先在亀裂長さがわかれ
ば、図４のような関係から安全領域がわかり、摩擦係数
および接触面圧がこの安全領域内になるような条件で軸
受が使用される。If the ceramic material to be used for the bearing is determined, the pre-existing crack length is known, and if the pre-existing crack length is known, the safety area is known from the relationship shown in FIG. bearing Ru is used in such conditions become safe area.
【００１９】上記の軸受は、上記のように求められた安
全領域内で使用されるので、摩擦係数および接触面圧が
臨界条件に達することがなく、したがって、亀裂の生成
が抑制される。Since the bearing described above is used within the safety region determined as described above, the coefficient of friction and the contact surface pressure do not reach critical conditions, and thus the generation of cracks is suppressed.
【００２０】[0020]
【発明の効果】この発明のセラミック軸受によれば、上
述のように、亀裂の生成を抑制して、亀裂による脆性破
壊を抑制することができ、したがって、無潤滑状態での
セラミック軸受の信頼性を向上させることができる。According to the ceramic bearing of the present invention, as described above, the generation of cracks can be suppressed, and brittle fracture due to cracks can be suppressed. Therefore, the reliability of the ceramic bearing in a non-lubricated state can be suppressed. Can be improved.
【図１】この発明の実施例を示すセラミック・スラスト
玉軸受の縦断面図である。FIG. 1 is a longitudinal sectional view of a ceramic thrust ball bearing showing an embodiment of the present invention.
【図２】セラミックス材料の表面部分および先在亀裂を
示す説明図である。FIG. 2 is an explanatory view showing a surface portion and a pre-existing crack of a ceramic material.
【図３】摩擦係数と最大主応力の最大値との関係を示す
グラフである。FIG. 3 is a graph showing a relationship between a coefficient of friction and a maximum value of a maximum principal stress.
【図４】摩擦係数と接触面圧との臨界条件を示すグラフ
である。FIG. 4 is a graph showing a critical condition between a friction coefficient and a contact surface pressure.
(1)(2) 軌道輪 (3) 玉 (4) セラミックス材料 (4a) セラミックス材料表面 (5) 初期亀裂 (1) (2) Track ring (3) Ball (4) Ceramic material (4a) Ceramic material surface (5) Initial crack
───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭62−56620（ＪＰ，Ａ) 特開 昭64−91031（ＪＰ，Ａ) 特開 昭62−153729（ＪＰ，Ａ) 特開 平１−184439（ＪＰ，Ａ) 特開 昭63−8532（ＪＰ，Ａ) 特開 昭61−258141（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) F16C 19/00 - 19/56 F16C 33/30 - 33/60 C04B 35/00 G01N 3/00 - 3/62 ──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-56620 (JP, A) JP-A-64-91031 (JP, A) JP-A-62-153729 (JP, A) JP-A-1- 184439 (JP, A) JP-A-63-8532 (JP, A) JP-A-61-258141 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) F16C 19/00-19 / 56 F16C 33/30-33/60 C04B 35/00 G01N 3/00-3/62
Claims (1)
あって、軸受の接触面圧および軸受を構成するセラミッ
クス材料の摩擦係数が、セラミック材料表面の先在亀裂
長さから求められた接触面圧および摩擦係数の安全領域
内にあることを特徴とするセラミック軸受。1. A ceramic bearing used in a non-lubricated state, wherein a contact surface pressure of the bearing and a friction coefficient of a ceramic material constituting the bearing are determined from a pre-existing crack length of the ceramic material surface. A ceramic bearing characterized by being within the safe range of pressure and coefficient of friction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07171592A JP3353152B2 (en) | 1992-03-27 | 1992-03-27 | Ceramic bearings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP07171592A JP3353152B2 (en) | 1992-03-27 | 1992-03-27 | Ceramic bearings |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05272541A JPH05272541A (en) | 1993-10-19 |
| JP3353152B2 true JP3353152B2 (en) | 2002-12-03 |
Family
ID=13468506
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP07171592A Expired - Fee Related JP3353152B2 (en) | 1992-03-27 | 1992-03-27 | Ceramic bearings |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3353152B2 (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61258141A (en) * | 1985-05-11 | 1986-11-15 | Kawasaki Steel Corp | Fatigue precrack detecting method for fracture touchness test piece |
| JPS6256620A (en) * | 1985-09-05 | 1987-03-12 | Nippon Seiko Kk | rolling bearing |
| JPS62153729A (en) * | 1985-12-27 | 1987-07-08 | Saginomiya Seisakusho Inc | Fracture toughness test method |
| JPS638532A (en) * | 1986-06-30 | 1988-01-14 | Kawasaki Steel Corp | Fatigue pre-crack formation device for fracture toughness test pieces |
| JPH0616001B2 (en) * | 1987-10-02 | 1994-03-02 | 日本たばこ産業株式会社 | Non-destructive inspection method and device for rolling bearing |
| JPH01184439A (en) * | 1988-01-19 | 1989-07-24 | Nippon Steel Corp | Foreknowing method for generation of crack of product made of jointing ceramics and metal |
-
1992
- 1992-03-27 JP JP07171592A patent/JP3353152B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH05272541A (en) | 1993-10-19 |
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