JP2005273471A - Rolling bearing - Google Patents
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Abstract
【課題】 冷媒を含有する冷凍機油潤滑下で稼動する圧縮機に用いる場合においても長寿命化を図ることができる転がり軸受を提供する。
【解決手段】 内輪１と外輪２との間に複数の転動体３が周方向に転動可能に配設されると共に、内輪１が嵌め合い機構によって固定され、且つ冷媒を含有する冷凍機油潤滑下で稼動する圧縮機に用いられる転がり軸受において、内輪１又は内外輪１，２に浸炭窒化処理を施し、更に、寸法安定化処理を施すことで心部の残留オーステナイト量を５体積％未満とし、且つ表面の残留オーステナイト量を５体積％以上とする。
【選択図】 図１PROBLEM TO BE SOLVED: To provide a rolling bearing capable of extending the life even when used for a compressor operating under lubrication with a refrigerator oil containing a refrigerant.
A plurality of rolling elements (3) are disposed between an inner ring (1) and an outer ring (2) so as to be able to roll in the circumferential direction, and the inner ring (1) is fixed by a fitting mechanism, and a refrigerator oil lubrication containing a refrigerant. In rolling bearings used in compressors operating below, the inner ring 1 or inner and outer rings 1, 2 are subjected to carbonitriding and further subjected to dimensional stabilization to reduce the amount of retained austenite in the core to less than 5% by volume. In addition, the amount of retained austenite on the surface is set to 5% by volume or more.
[Selection] Figure 1
Description
本発明は、例えばカーエアコンや冷凍機、給湯器等の圧縮機に用いられる転がり軸受の長寿命化に関する。 The present invention relates to extending the life of rolling bearings used in compressors such as car air conditioners, refrigerators, and water heaters.
カーエアコンや冷凍機、給湯器等の圧縮機は冷媒の圧縮機構として、スクロール方式や容量を可変できる斜板方式等があり、これらの圧縮機では冷媒を含有する冷凍機油潤滑下で転がり軸受が使用される。圧縮機はその機構上、潤滑油量が少ないことから、転がり軸受等の稼動部への潤滑量も少なく、潤滑状態が厳しい傾向にあり、さらに、潤滑油には冷媒が溶け込んでいるため、潤滑油の潤滑性能も低下する傾向にある。 Compressors for car air conditioners, refrigerators, water heaters, etc., have a scroll system and a swash plate system with variable capacity as a refrigerant compression mechanism. These compressors have rolling bearings under lubrication with refrigeration machine oil containing refrigerant. used. Since the compressor has a small amount of lubricating oil due to its mechanism, the amount of lubrication to the moving parts such as rolling bearings is small, the lubricating state tends to be severe, and the lubricant is dissolved in the lubricating oil. Oil lubrication performance also tends to decrease.
厳しい潤滑状態にある圧縮機に用いられる転がり軸受では、内外輪、転動体に摩耗損傷やはくり現象が発生する場合がある。
このような損傷に対して、表面に微小な凹凸を形成し、この凹凸の粗さを一定範囲内に抑えることにより軸受の寿命延長を図るようにしたものや（例えば特許文献１参照）、浸炭窒化処理により残留オーステナイト量と硬さとのバランスを適正化して軸受の長寿命化を図るようにしたもの（例えば特許文献２参照）等が提案されている。
In response to such damage, a minute unevenness is formed on the surface, and the roughness of the unevenness is suppressed within a certain range so as to extend the life of the bearing (see, for example, Patent Document 1), carburizing There have been proposed ones in which the balance between the amount of retained austenite and hardness is optimized by nitriding so as to extend the life of the bearing (see, for example, Patent Document 2).
ところで、潤滑油は転がり軸受及びその周辺機構を冷却する働きがあるが、圧縮機はその機構上、潤滑油量が少なく、しかも近年の機能向上や効率改善等でその使用条件は厳しくなり、結果として圧縮機自体の温度が上昇する傾向にあるため、使用条件によっては高い温度環境で転がり軸受が使用されることになる。
従って、嵌め合い機構によってシャフト類に固定される内輪はその使用温度によって寸法変化（経時変化）が加速されて膨張し、場合によってはクリープ現象が発生してしまう虞れがある。
By the way, the lubricating oil works to cool the rolling bearing and its peripheral mechanism, but the compressor has a small amount of lubricating oil due to its mechanism, and the usage conditions have become severe due to recent functional improvements and efficiency improvements, etc. As the temperature of the compressor itself tends to rise, the rolling bearing is used in a high temperature environment depending on the use conditions.
Therefore, the inner ring fixed to the shafts by the fitting mechanism is accelerated by a change in size (change over time) depending on the use temperature, and may expand in some cases.
しかしながら、上記特許文献１及び特許文献２においては、摩耗や損傷に対しての対策は開示されているが、使用温度環境を考慮した経時変化よるクリープ現象に対しての対策は開示も示唆もされておらず、従って、内輪が嵌め合い機構によって固定される転がり軸受としての長寿命化には更に改良の余地がある。
即ち、比較的高い温度で使用される圧縮機用の転がり軸受には、使用温度環境に起因する経時的な寸法変化に対する適切な処理を施すことが必要である。
However, although
That is, a rolling bearing for a compressor that is used at a relatively high temperature needs to be subjected to an appropriate treatment against a dimensional change over time caused by the operating temperature environment.
本発明はこのような技術的背景を鑑みてなされたものであり、適切な寸法安定化処理により表面の残留オーステナイト量を残しつつ、使用温度環境に起因する経時的な寸法変化を抑制することで、冷媒を含有する冷凍機油潤滑下で稼動する圧縮機に用いる場合においても長寿命化を図ることができる転がり軸受を提供することを目的とする。 The present invention has been made in view of such a technical background, and by suppressing the dimensional change over time caused by the operating temperature environment while leaving the amount of retained austenite on the surface by appropriate dimensional stabilization treatment. An object of the present invention is to provide a rolling bearing capable of extending the life even when used in a compressor operating under lubrication with a refrigerator oil containing a refrigerant.
本発明者らは、冷媒を含有する冷凍機油潤滑下で稼働する圧縮機に用いられる転がり軸受について、圧縮機の潤滑状態を再現し、比較的高い温度雰囲気で試験を行い、摩耗や損傷の他にクリープの発生を含めて詳細に調査した結果、粗さや窒素濃度を向上させるだけでなく、使用温度環境に起因する経時的な寸法変化に対する適切な処理を施すことで、転がり軸受として寿命が向上することを知見し、本発明を完成するに至った。 The present inventors reproduced the lubrication state of a compressor and tested it in a relatively high temperature atmosphere for a rolling bearing used in a compressor operated under lubrication with a refrigeration machine oil containing a refrigerant. As a result of detailed investigation including the occurrence of creep, it not only improves the roughness and nitrogen concentration, but also improves the service life as a rolling bearing by applying appropriate treatment for dimensional changes over time due to the operating temperature environment. As a result, the present invention has been completed.
即ち、上記目的を達成するために、請求項１に係る発明は、内輪と外輪との間に複数の転動体が周方向に転動可能に配設されると共に、前記内輪が嵌め合い機構によって固定され、且つ冷媒を含有する冷凍機油潤滑下で稼動する圧縮機に用いられる転がり軸受において、
前記内輪又は前記内外輪に浸炭窒化処理を施し、更に、寸法安定化処理を施すことで心部の残留オーステナイト量を５体積％未満とし、且つ表面の残留オーステナイト量を５体積％以上としたことを特徴とする。
That is, in order to achieve the above object, according to the first aspect of the present invention, a plurality of rolling elements are disposed between the inner ring and the outer ring so as to roll in the circumferential direction, and the inner ring is fitted by a fitting mechanism. In a rolling bearing used for a compressor that is fixed and operates under lubrication with a refrigerator oil containing a refrigerant,
The inner ring or the inner and outer rings were subjected to carbonitriding, and further subjected to dimensional stabilization treatment so that the amount of retained austenite at the core was less than 5% by volume and the amount of retained austenite at the surface was at least 5% by volume. It is characterized by.
請求項２に係る発明は、請求項１において、前記内輪又は前記内外輪の成分が重量％で、Ｃ：０．２％以上０．７％以下、Ｓｉ：０．１５％以上１．０％以下、Ｍｎ：０．３％以上２．０％以下、Ｃｒ：１．０％以上２．０％以下とされ、浸炭窒化処理を施して仕上げ加工を行った後の前記内輪又は前記内外輪の完成品の表面の窒素濃度が０．１％以上で、且つ前記完成品の表面の炭素濃度と窒素濃度との和が１．１％以上であることを特徴とする。 According to a second aspect of the present invention, in the first aspect, the components of the inner ring or the inner and outer rings are in% by weight, C: 0.2% to 0.7%, Si: 0.15% to 1.0% Hereinafter, Mn: 0.3% or more and 2.0% or less, Cr: 1.0% or more and 2.0% or less, and the inner ring or the inner / outer ring after the carbonitriding process is performed and finishing is performed. The nitrogen concentration on the surface of the finished product is 0.1% or more, and the sum of the carbon concentration and the nitrogen concentration on the surface of the finished product is 1.1% or more.
本発明によれば、内輪又は内外輪に浸炭窒化処理を施し、更に、寸法安定化処理を施して心部の残留オーステナイト量を５体積％未満、且つ表面の残留オーステナイト量を５体積％以上とすることで、適切な寸法安定化処理により表面の残留オーステナイト量を残しつつ、使用温度環境に起因する経時的な寸法変化を抑制することができ、これにより、冷媒を含有する冷凍機油潤滑下で稼動する圧縮機に用いる場合においても長寿命化を図ることができる転がり軸受を提供することができる。 According to the present invention, the inner ring or the inner and outer rings are subjected to carbonitriding, and further subjected to dimensional stabilization treatment so that the amount of retained austenite at the core is less than 5% by volume, and the amount of retained austenite at the surface is 5% by volume or more. As a result, the dimensional change over time caused by the operating temperature environment can be suppressed while leaving the amount of retained austenite on the surface by an appropriate dimensional stabilization treatment. Even when used in an operating compressor, it is possible to provide a rolling bearing capable of extending the life.
以下、本発明の実施の形態の一例を図を参照して説明する。
図１は本発明の実施の形態の一例である転がり軸受を説明するための断面図、図２は心部の残留オーステナイト量と寸法膨張率との関係を示すグラフ図、図３は軌道面の表面窒素濃度と摩耗量との関係を示すグラフ図、図４は軌道面表面の炭素濃度＋窒素濃度と摩耗量との関係を示すグラフ図、図５は本発明の他の実施の形態である転がり軸受を説明するための断面図である。
Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view for explaining a rolling bearing as an example of an embodiment of the present invention, FIG. 2 is a graph showing the relationship between the amount of retained austenite at the core and the dimensional expansion coefficient, and FIG. FIG. 4 is a graph showing the relationship between the surface nitrogen concentration and the amount of wear, FIG. 4 is a graph showing the relationship between the carbon concentration of the raceway surface + nitrogen concentration and the amount of wear, and FIG. 5 is another embodiment of the present invention. It is sectional drawing for demonstrating a rolling bearing.
本発明の実施の形態の一例である転がり軸受は、図１に示すように、内輪１と外輪２との間に転動体３としての複数の円筒ころが周方向に転動可能に配設された円筒ころ軸受であり、内輪１が嵌め合い機構によってシャフト類に固定されると共に、外輪２がハウジング等に嵌合され、且つ冷媒を含有する冷凍機油潤滑下で稼動する圧縮機に用いられる。
ここで、この実施の形態では、内輪１又は内外輪１，２に浸炭窒化処理を施し、更に、寸法安定化処理を施すことで心部の残留オーステナイト量を５体積％未満とし、且つ表面の残留オーステナイト量を５体積％以上としている。
これにより、適切な寸法安定化処理で表面の残留オーステナイト量を残しつつ、使用温度環境に起因する経時的な寸法変化を抑制して、冷媒を含有する冷凍機油潤滑下で稼動する圧縮機に用いる場合においても長寿命化が図れるようにしている。
As shown in FIG. 1, a rolling bearing which is an example of an embodiment of the present invention has a plurality of cylindrical rollers as rolling elements 3 disposed between an
Here, in this embodiment, the
As a result, while maintaining the amount of retained austenite on the surface with an appropriate dimensional stabilization treatment, the dimensional change over time caused by the operating temperature environment is suppressed, and the compressor is used for a compressor that operates under lubrication with refrigeration oil containing refrigerant. Even in such a case, the service life can be extended.
以下、数値限定の根拠を述べる。
［心部の残留オーステナイト量を５体積％未満］
残留オーステナイトの分解による軸受の寸法変化（経時変化）は心部の残留オーステナイト量に大きく依存する。寸法変化量は軸受内部に残留したオーステナイトの平均量で決まるため、心部の残留オーステナイト量はその軸受の平均残留オーステナイト量とほぼ等価値となる。
図２に心部の残留オーステナイト量と軸受の寸法膨張率との関係を示す。なお、鋼種は後段に表示する表３の実施例３４相当のものを用いた。
The basis for numerical limitations will be described below.
[Residual austenite content in the core is less than 5% by volume]
The dimensional change (change with time) of the bearing due to the decomposition of the retained austenite largely depends on the amount of retained austenite in the core. Since the amount of dimensional change is determined by the average amount of austenite remaining inside the bearing, the amount of retained austenite at the core is almost equivalent to the average amount of retained austenite of the bearing.
FIG. 2 shows the relationship between the amount of retained austenite at the core and the dimensional expansion coefficient of the bearing. In addition, the steel grade used the thing equivalent to Example 34 of Table 3 displayed in a back | latter stage.
図から心部の残留オーステナイト量が５体積％以上となると、寸法膨張率が加速的に増加してしまうことが判る。従って、使用温度環境に起因する軸受の経時的な寸法変化で発生するクリープ等の軸受損傷に対して寸法変化率を制御するためには、心部の残留オーステナイト量を制御することが必要となる。
本発明者らは、冷媒を含有する冷凍機油潤滑下での圧縮機の使用環境（温度、潤滑等）を再現して転がり軸受の評価試験を行った結果、心部の残留オーステナイト量が５体積％以上となるとクリープ損傷が発生してしまう虞れがあることを確認した。従って、心部の残留オーステナイト量は５体積％未満、好ましくは３体積％以下とする。
From the figure, it can be seen that when the amount of retained austenite at the core is 5% by volume or more, the dimensional expansion coefficient is accelerated. Therefore, it is necessary to control the amount of retained austenite in the core in order to control the dimensional change rate with respect to bearing damage such as creep caused by the dimensional change of the bearing over time due to the operating temperature environment. .
The inventors of the present invention reproduced the usage environment (temperature, lubrication, etc.) of the compressor under the lubrication of the refrigerating machine oil containing the refrigerant and conducted an evaluation test of the rolling bearing. As a result, the amount of retained austenite in the core was 5 volumes. It has been confirmed that creep damage may occur when the content exceeds 10%. Therefore, the amount of retained austenite in the core is less than 5% by volume, preferably 3% by volume or less.
［表面の残留オーステナイト量が５体積％以上］
上述の通り、冷媒を含有する冷凍機油潤滑下で用いられる転がり軸受では、潤滑状態が厳しいため摩耗や損傷が発生しやすい。そこで、表面の残留オーステナイト量を高めることにより表面損傷を防止して長寿命化を図る。
本発明者らは、冷媒を含有する冷凍機油潤滑下での圧縮機の使用環境（温度、潤滑等）を再現して転がり軸受の評価試験を行った結果、表面の残留オーステナイト量が５体積％未満となると表面損傷部位からはくりが発生してしまう虞れがあることを確認した。従って、表面の残留オーステナイト量は５体積％以上、好ましくは９体積％以上する。
[The amount of retained austenite on the surface is 5% by volume or more]
As described above, a rolling bearing used under lubrication with a refrigerating machine oil containing a refrigerant is likely to be worn or damaged because the lubrication state is severe. Therefore, surface damage is prevented by increasing the amount of retained austenite on the surface, thereby extending the life.
The inventors of the present invention reproduced the usage environment (temperature, lubrication, etc.) of the compressor under lubrication with refrigeration oil containing a refrigerant and conducted an evaluation test of the rolling bearing. As a result, the amount of retained austenite on the surface was 5% by volume. It was confirmed that there was a possibility that peeling would occur from the surface damaged part when the amount was less than 1. Therefore, the amount of retained austenite on the surface is 5% by volume or more, preferably 9% by volume or more.
次に、上記残留オーステナイトの特長を生かして軸受の寿命延長効果を更に高めるための限定条件を説明する。まず、軸受素材成分について数値限定の根拠を述べる。
［Ｃ含有量：０．２重量％以上０．７重量％以下］
本発明では転がり軸受に必要な硬さを得るために、浸炭窒化処理を行うが、素材の炭素量が０．２重量％未満になると熱処理生産性が悪化し、また、素材の炭素量が０．７重量％を超えると軸受心部の靭性が低下したり、寸法安定性を低下させる虞れがある。従って、本発明では、Ｃ含有量を０．２重量％以上０．７重量％以下とするのが好ましい。
Next, limiting conditions for further enhancing the effect of extending the life of the bearing by taking advantage of the characteristics of the retained austenite will be described. First, the grounds for limiting the numerical values of bearing material components will be described.
[C content: 0.2 wt% or more and 0.7 wt% or less]
In the present invention, carbonitriding is performed to obtain the hardness required for the rolling bearing. However, when the carbon content of the material is less than 0.2% by weight, the heat treatment productivity is deteriorated, and the carbon content of the material is 0. If it exceeds 0.7% by weight, the toughness of the bearing core may be reduced, or the dimensional stability may be reduced. Therefore, in the present invention, the C content is preferably 0.2 wt% or more and 0.7 wt% or less.
［Ｓｉ含有量：０．１５重量％以上１．０重量％以下］
Ｓｉは焼戻し抵抗性を高めるため、寸法経時変化に対して有効な元素である。また、転がり寿命に有効であり、焼入れ性も高める。その効果を得るためには、最低でも０．１５重量％は必要である。一方、Ｓｉは添加量に従いその効果を高めるが、１．０重量％を超えて必要以上に添加すると浸炭窒化時の粒界酸化層を増加させたり、浸炭窒化による拡散現象を妨げて浸炭窒化深さを低減させる虞れがある。従って、本発明では、Ｓｉ含有量を０．１５重量％以上１．０重量％以下とするのが好ましい。
[Si content: 0.15 wt% or more and 1.0 wt% or less]
Si increases the tempering resistance, and is therefore an effective element against dimensional change with time. It is also effective for rolling life and enhances hardenability. In order to obtain the effect, at least 0.15% by weight is necessary. On the other hand, Si increases its effect according to the amount added, but if it is added more than necessary exceeding 1.0% by weight, the grain boundary oxidation layer at the time of carbonitriding is increased or the diffusion phenomenon due to carbonitriding is hindered and the carbonitriding depth is increased. There is a risk of reducing the thickness. Therefore, in the present invention, the Si content is preferably 0.15 wt% or more and 1.0 wt% or less.
［Ｍｎ含有量：０．３重量％以上２．０重量％以下］
Ｍｎは焼入れ性を向上させる元素であり、転がり寿命にも有効である。その効果を得るためには、最低でも０．３重量％は必要である。Ｍｎは添加量に従いその効果を高めるが、２．０重量％を超えて添加すると、冷間加工性や熱間加工に悪影響を及ぼす傾向を示す。従って、本発明では、Ｍｎ含有量を０．３重量％以上２．０重量％以下とするのが好ましい。
[Mn content: 0.3 wt% to 2.0 wt%]
Mn is an element that improves hardenability and is also effective in rolling life. In order to obtain the effect, at least 0.3% by weight is necessary. Mn enhances its effect according to the amount added, but if added over 2.0% by weight, it tends to adversely affect cold workability and hot work. Therefore, in the present invention, the Mn content is preferably 0.3 wt% or more and 2.0 wt% or less.
［Ｃｒ含有量：１．０重量％以上２．０重量％以下］
Ｃｒは焼入れ性の向上、焼戻し軟化抵抗性の向上など基地を強化する元素であり、転がり寿命にも有効であるため、最低でも１．０重量％は必要である。―方、Ｃｒを２．０重量％を超えて必要以上に添加すると、製鋼過程で巨大炭化物が折出し、軸受の寿命を低下させる虞れがある。従って、本発明では、Ｃｒ含有量を１．０重量％以上２．０重量％以下とするのが好ましい。
[Cr content: 1.0 wt% or more and 2.0 wt% or less]
Cr is an element that strengthens the base such as improving hardenability and resistance to temper softening, and is effective in rolling life, so at least 1.0% by weight is necessary. -On the other hand, if more than 2.0% by weight of Cr is added more than necessary, giant carbides may break out during the steel making process, which may reduce the life of the bearing. Therefore, in this invention, it is preferable that Cr content shall be 1.0 to 2.0 weight%.
次に、浸炭窒化処理を施して仕上げ加工を行った後の内輪又は内外輪の完成品の品質に関する数値限定の根拠を述べる。
［完成品の内輪又は内外輪の軌道面表面の窒素濃度が０．１％以上］
冷媒を含有する冷凍機油潤滑下で用いられる転がり軸受では、潤滑状態が厳しいため摩耗や損傷が発生しやすい。そこで、上述の通り、表面の残留オーステナイト量を高めることにより表面損傷を防止して長寿命効果が得られる。一方、摩耗損傷に対しては、軌道面の表面窒素濃度が大きく影響する。
図３に軌道面の表面窒素濃度と軌道面摩耗量との関係を示す。なお、鋼種は後段に表示する表３の実施例３４相当のものを用いた。
Next, the grounds for numerical limitation regarding the quality of the finished product of the inner ring or the inner and outer rings after the carbonitriding process and finishing are described.
[Nitrogen concentration on the raceway surface of the finished inner ring or inner and outer rings is 0.1% or more]
Rolling bearings used under lubrication with refrigerating machine oil containing a refrigerant are likely to be worn and damaged due to severe lubrication. Therefore, as described above, by increasing the amount of retained austenite on the surface, surface damage can be prevented and a long life effect can be obtained. On the other hand, the surface nitrogen concentration on the raceway surface greatly affects wear damage.
FIG. 3 shows the relationship between the surface nitrogen concentration on the raceway surface and the amount of wear on the raceway surface. In addition, the steel grade used the thing equivalent to Example 34 of Table 3 displayed in a back | latter stage.
図から表面窒素濃度が０．１％以上になると、十分な耐摩耗性を示すのが判る。また、表面窒素濃度が０．１３％以上になるとより安定した耐磨耗性が得られ、更に、０．３％以上では殆ど摩耗しない。このため、本発明では、表面窒素濃度を好ましくは０．１３％以上、より好ましくは０．３％以上とする。
このように表面窒素濃度が高いほど耐摩耗性に対しては有利であるが、必要以上に窒素濃度を高くしようとすると、熱処理の生産性が低下することや、熱処理後の研削加工性が低下してしまう。また、耐摩耗性効果が飽和することも考慮して、好ましくは窒素濃度を０．５％以下とする。
From the figure, it can be seen that when the surface nitrogen concentration is 0.1% or more, sufficient wear resistance is exhibited. Further, when the surface nitrogen concentration is 0.13% or more, more stable wear resistance is obtained, and when it is 0.3% or more, there is almost no wear. Therefore, in the present invention, the surface nitrogen concentration is preferably 0.13% or more, more preferably 0.3% or more.
Thus, the higher the surface nitrogen concentration, the better the wear resistance, but if you try to increase the nitrogen concentration more than necessary, the heat treatment productivity decreases and the grindability after heat treatment decreases. Resulting in. In consideration of saturation of the wear resistance effect, the nitrogen concentration is preferably 0.5% or less.
［完成品の内輪又は内外輪の軌道面表面の炭素濃度と窒素濃度との和が１．１％以上］
軌道面の表面窒素濃度は軌道面摩耗量に影響するが、窒素濃度だけでは摩耗を制御しきれない場合がある。図４に軌道面表面の炭素濃度＋窒素濃度と軌道面摩耗量との関係を示す。なお、鋼種は後段に表示する表３の実施例３４相当のものを用いた。
図から窒素濃度が十分でも、軌道面表面の炭素濃度＋窒素濃度の値が１．１％未満になると、摩耗に有効な炭窒化物の析出が不十分となり、耐摩耗性が低下してしまうのが判る。従って、軌道面表面の炭素濃度と窒素濃度との和は１．１％以上必要となり、また、軌道面表面の炭素濃度と窒素濃度との和が１．２％以上になるとより安定した耐摩耗性が得られるため、好ましくは１．２％以上とする。
[The sum of carbon concentration and nitrogen concentration on the raceway surface of the finished inner ring or inner / outer ring is 1.1% or more]
The surface nitrogen concentration on the raceway affects the amount of wear on the raceway, but the wear may not be controlled by the nitrogen concentration alone. FIG. 4 shows the relationship between the carbon concentration + nitrogen concentration on the raceway surface and the amount of raceway wear. In addition, the steel grade used the thing equivalent to Example 34 of Table 3 displayed in a back | latter stage.
From the figure, even if the nitrogen concentration is sufficient, if the value of carbon concentration + nitrogen concentration on the raceway surface is less than 1.1%, the precipitation of carbonitride effective for wear becomes insufficient and the wear resistance decreases. I understand. Accordingly, the sum of the carbon concentration and the nitrogen concentration on the raceway surface must be 1.1% or more, and if the sum of the carbon concentration and the nitrogen concentration on the raceway surface is 1.2% or more, more stable wear resistance can be obtained. Therefore, the content is preferably 1.2% or more.
一方、軌道面表面の炭素濃度と窒素濃度との和が大きいほど耐摩耗性に対しては有利であるが、必要以上に炭素濃度と窒素濃度との和が大きいと初析炭化物がネット状に発生して寿命が低下する虞れがあることや、耐摩耗性効果が飽和することから、好ましくは、炭素濃度と窒素濃度との和を１．８％以下とする。
なお、本発明は上記実施の形態に限定されるものではなく、本発明の要旨を逸脱しない範囲において適宜変更可能である。
例えば、上記実施の形態では、転がり軸受として円筒ころ軸受を例に採ったが、これに限定されず、例えば図５に示すように、内輪１１と外輪１２との間に転動体１３としての複数の玉が周方向に転動可能に配設された玉軸受やその他の転がり軸受に本発明を適用してもよいのは勿論である。
On the other hand, the larger the sum of the carbon concentration and the nitrogen concentration on the raceway surface, the better the wear resistance. However, if the sum of the carbon concentration and the nitrogen concentration is larger than necessary, the pro-eutectoid carbide becomes a net shape. Preferably, the sum of the carbon concentration and the nitrogen concentration is set to 1.8% or less because there is a possibility that the life may be shortened and the wear resistance effect is saturated.
In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.
For example, in the above embodiment, a cylindrical roller bearing is taken as an example of the rolling bearing, but the present invention is not limited to this. For example, a plurality of rolling
本実施例では、一般的な深溝玉軸受（６２０６）を用い、圧縮機で用いられる冷媒を含有する冷凍機油潤滑下で比較的高い温度で寿命評価試験を行った。内外輪の素材については表３に示す。転動体の素材はＳＵＪ２を使用し、内外輪と転動体の熱処理は、浸炭窒化後に焼入れ焼戻し処理を行う浸炭窒化焼入れ処理を施している。
ここで、本発明では、焼入れ後の焼戻し処理条件が重要で、軸受の寸法経時変化を考慮した適切な焼戻し条件の設定か必要となる。なお、熱処理後は研削仕上げ加工を施している。
In this example, a general deep groove ball bearing (6206) was used, and a life evaluation test was performed at a relatively high temperature under lubrication with a refrigerator oil containing a refrigerant used in a compressor. The materials for the inner and outer rings are shown in Table 3. SUJ2 is used as the material for the rolling elements, and the inner and outer rings and the rolling elements are subjected to a carbonitriding and quenching process in which a quenching and tempering process is performed after carbonitriding.
Here, in the present invention, the tempering conditions after quenching are important, and it is necessary to set appropriate tempering conditions in consideration of the dimensional change of the bearing over time. In addition, after heat processing, the grinding finishing process is given.
評価試験は日本精工株式会社製の深溝玉軸受寿命試験機を用いて寿命評価を行った。圧縮機で用いられる冷媒を含有する冷凍機油潤滑環境を再現するために、冷凍機油に白灯油を混合した潤滑油を使用し、必要に応じてヒータで加熱した。
寿命試験は各条件で５個行い、試験時間は計算寿命に相当するとして、内外輪軌道面の摩耗測定を行った。また、はくりの発生状況及び試験後の内輪内径の膨張量及びクリープ状態を観察して記録した。
The evaluation test was performed using a deep groove ball bearing life tester manufactured by NSK Ltd. In order to reproduce the refrigerating machine oil lubrication environment containing the refrigerant used in the compressor, a lubricating oil in which white kerosene was mixed with the refrigerating machine oil was used and heated with a heater as necessary.
A life test was performed under each condition, and the wear on the inner and outer ring raceways was measured on the assumption that the test time corresponds to the calculated life. Further, the state of occurrence of peeling, the amount of expansion of the inner ring inner diameter after the test and the creep state were observed and recorded.
熱処理条件、試験条件及び摩耗測定条件は次の通りである。
（熱処理条件）
内外輪は８７０〜９５０°Ｃで４〜８時間の浸炭窒化処理を行う。浸炭窒化処理の雰囲気はＲＸガス流量で１５〜２０ｍ3 ／時間、カーボンポテンシャルコントロールで０．９〜１．３％、ＮＨ3 流量で０．１〜０．８ｍ3 ／時間とした。
なお、本発明の実施例では浸炭窒化後に放冷を行う２次焼入れを施したが、浸炭窒化後にダイレクト焼入れを行っても、鋼種や浸炭窒化条件によっては同じ効果が得られる。
本発明の実施例の内外輪の焼戻し条件は寸法安定性と長寿命が同時に得られる条件として、２３０〜３００°Ｃで９０〜１８０分とし、比較例では１８０〜２２０°Ｃで９０〜１８０分とした。
The heat treatment conditions, test conditions, and wear measurement conditions are as follows.
(Heat treatment conditions)
The inner and outer rings are carbonitrided at 870 to 950 ° C. for 4 to 8 hours. Atmosphere carbonitriding treatment 15-20 meters 3 / time, RX gas flow, 0.9 to 1.3% carbon potential control, was 0.1~0.8m 3 / time, NH 3 flow rate.
In the examples of the present invention, secondary quenching is performed in which cooling is performed after carbonitriding, but the same effect can be obtained depending on the steel type and carbonitriding conditions even if direct quenching is performed after carbonitriding.
The tempering conditions of the inner and outer rings of the examples of the present invention are 90 to 180 minutes at 230 to 300 ° C., and 90 to 180 minutes at 180 to 220 ° C. in the comparative example, as conditions for obtaining dimensional stability and long life at the same time. It was.
転動体の熱処理は８３０〜８５０°Ｃで２〜４時間の浸炭窒化処理を行った後に、ダイレクトに焼入れを行う。浸炭窒化処理の雰囲気はＲＸガス流量で１５〜２０ｍ3 ／時間、カーボンポテンシャルコントロールで０．９〜１．３％、ＮＨ3 流量で０．１〜０．３ｍ3 ／時間とした。焼入れ油温は６０〜１２０°Ｃで、焼戻し条件は１８０〜２２０°Ｃで９０〜ｌ８０分とした。
但し、本実施例では、内外輪の長寿命効果を確認しやすくするために、転動体に浸炭窒化処理を施したが、ずぶ焼入れや浸炭処理の転動体を用いても同様の効果が得られる。
The rolling element is heat-treated at 830 to 850 ° C. for 2 to 4 hours after carbonitriding and then directly quenched. Atmosphere carbonitriding treatment 15-20 meters 3 / time, RX gas flow, 0.9 to 1.3% carbon potential control, was 0.1~0.3m 3 / time, NH 3 flow rate. The quenching oil temperature was 60 to 120 ° C., and the tempering conditions were 180 to 220 ° C. and 90 to 80 minutes.
However, in this example, in order to make it easy to confirm the long life effect of the inner and outer rings, carbonitriding treatment was performed on the rolling elements, but the same effect can be obtained even if rolling elements of sub-quenching or carburizing treatment are used. .
（試験条件）
使用軸受：６２０６深溝玉軸受
試験荷重：５０００Ｎ
回転数 ：３０００ｍｉｎ-1
潤滑油 ：ＰＡＧ油＋白灯油（６０〜９０％混合）
試験温度：１４０〜１６０°Ｃ
試験時間：計算寿命相当（２００時間）
（摩耗測定条件）
内外輪軌道面の摩耗量は走行部と非走行部との段差をForm Talysurf Series S5 （Taylor Hobson 製）で溝Ｒを平面に補正して測定した。内外輪軌道面を軸方向に各５箇所測定して摩耗深さの最大値を代表値とし、同一条件の軸受を５個測定して代表値の平均を軌道面摩耗量としている。また、はくり等の損傷が発生した場合は損傷部以外を測定した。
(Test conditions)
Bearing used: 6206 deep groove ball bearing Test load: 5000N
Number of revolutions: 3000 min -1
Lubricating oil: PAG oil + white kerosene (60-90% mixed)
Test temperature: 140-160 ° C
Test time: Calculated life equivalent (200 hours)
(Wear measurement conditions)
The amount of wear on the inner and outer raceway surfaces was measured by correcting the level difference between the running part and the non-running part with Form Talysurf Series S5 (manufactured by Taylor Hobson) and making the groove R flat. The inner and outer ring raceway surfaces are measured at five locations in the axial direction, the maximum value of the wear depth is taken as a representative value, and five bearings under the same conditions are measured, and the average of the representative values is taken as the raceway wear amount. Moreover, when damage, such as peeling, occurred, other than the damaged part was measured.
次に、内外輪の軌道面表面の窒素濃度及び炭素濃度は、試験軸受と同じ位置に同一材質の分析用試験片を配置して浸炭窒化処理を行い、試験軸受の研削加工による取代分を取除いた位置で発光分光分析機ＰＤＡ５５００II（島津製作所製）により求めた。従って、同一鋼種で同一熱処理を施した軸受は同じ窒素濃度及び炭素濃度として評価している。
表１に内外輪の軌道面表面の残留オーステナイト量と心部の残留オーステナイト量を変えて試験し、試験後のはくり及びクリープを評価した結果を示す。なお、内外輪の素材は表３の実施例３４の鋼種を適用して、焼戻しによる寸法安定化条件を変えたもので、軌道面表面の窒素濃度は０．１５％で、軌道面表面の窒素濃度と炭素濃度との和は１．３２％である。
Next, the nitrogen concentration and carbon concentration on the raceway surface of the inner and outer rings are carbonitrided by placing an analytical test piece of the same material at the same position as the test bearing, and the balance of grinding by grinding the test bearing is taken. The emission spectrophotometer PDA5500II (manufactured by Shimadzu Corporation) was obtained at the removed position. Therefore, bearings of the same steel type and subjected to the same heat treatment are evaluated as the same nitrogen concentration and carbon concentration.
Table 1 shows the results of testing by changing the amount of retained austenite on the surface of the raceway surface of the inner and outer rings and the amount of retained austenite at the core, and evaluating the peel and creep after the test. The material of the inner and outer rings was obtained by applying the steel type of Example 34 in Table 3 and changing the dimensional stabilization condition by tempering. The nitrogen concentration on the raceway surface was 0.15%, and the nitrogen on the raceway surface was The sum of the concentration and the carbon concentration is 1.32%.
また、表１〜表３におけるはくり及びクリープの○、△、×の評価は次の通りである。 はくりに関して○印は２００時間走行後に内外輪及び転動体に何の損傷もない良好な状態を示し、×印ははくりが発生した状態を示す。△印でははくりは発生していないが、内外輪軌道面及び転動体表面に温度上昇により発生する着色が見られる状態を示す。なお、はくりが発生した×印の軸受にも着色が見られることから、はくりが発生する前兆現象として着色が発生すると考えられる。 Moreover, evaluation of (circle), (triangle | delta), and x of peeling and creep in Table 1-Table 3 is as follows. Regarding peeling, a circle indicates a good state in which there is no damage to the inner and outer rings and the rolling elements after traveling for 200 hours, and a cross indicates a state where peeling has occurred. In the case of Δ, no peeling is generated, but the inner and outer ring raceway surfaces and the rolling element surfaces are colored due to temperature rise. In addition, since coloring is seen also in the bearing of x mark | fever which the peeling generate | occur | produced, it is thought that coloring generate | occur | produces as a precursor phenomenon that a peeling generate | occur | produces.
クリープに関して○印は２００時間走行後に内輪の嵌め合いに問題がない状態を示し、×印は内輪が膨張して嵌め合いが緩み、クリープが発生した状態を示す。△印ではクリープは発生していないが、内輪の嵌め合いが緩みかけたことが原因で内輪内径面にフレッチング現象と思われる着色が見られる状態を示す。なお、クリープが発生した内輪内径面は着色を超えて金属凝着が発生していた。 Regarding the creep, a circle indicates a state where there is no problem in the fitting of the inner ring after traveling for 200 hours, and a mark X indicates a state where the inner ring expands and the fitting loosens, and a creep occurs. In the case of Δ, no creep has occurred, but the inner ring inner surface is colored such that it seems to be fretting due to loosening of the inner ring. In addition, the inner ring inner diameter surface where creep occurred occurred and metal adhesion occurred beyond the coloring.
表１から判るように、軌道表面の残留オーステナイト量が本発明範囲外の比較例３は試験後の観察ではくりが発生し、また、心部の残留オーステナイト量が本発明範囲外の比較例１，２は残留オーステナイトの分解により、内輪が膨張して軸との嵌め合いが緩んで滑ってしまうクリープ現象が発生した。
これに対し、本発明の実施例１〜７では試験後の軸受は摩耗やはくり及びクリープによる損傷は全くないか、あっても極めて軽微であり、長寿命が得られる結果となった。
As can be seen from Table 1, Comparative Example 3 in which the amount of retained austenite on the surface of the raceway was outside the range of the present invention was punctured by observation after the test, and Comparative Example 1 in which the amount of retained austenite at the core was outside the range of the present invention. 2 and 2 due to the decomposition of retained austenite, a creep phenomenon occurred in which the inner ring expanded and the fit with the shaft loosened and slipped.
On the other hand, in Examples 1 to 7 of the present invention, the bearings after the test were not damaged at all due to wear, peeling, and creep, but were very slight, and a long life was obtained.
なお、表面の残留オーステナイト量が低めの値となる実施例１，２，３では試験後の軌道表面に温度上昇による着色が確認された。従って、軌道表面の残留オーステナイト量は９体積％以上が好ましい。また、心部の残留オーステナイト量が多めの実施例７では、内輪の内径面にクリープは発生していなかったが、フレッチング現象と思われる着色が見られた。従って、心部の残留オーステナイト量は３体積％以下が好ましい。 In Examples 1, 2, and 3 in which the amount of retained austenite on the surface was a low value, coloring due to a temperature increase was confirmed on the track surface after the test. Therefore, the amount of retained austenite on the raceway surface is preferably 9% by volume or more. Further, in Example 7 in which the amount of retained austenite in the core was large, creep did not occur on the inner diameter surface of the inner ring, but coloring that seems to be a fretting phenomenon was observed. Therefore, the amount of retained austenite in the core is preferably 3% by volume or less.
次に、表２に内外輪の軌道面表面の残留オーステナイト量、心部の残留オーステナイト量、窒素濃度、炭素濃度及び窒素濃度と炭素濃度との和を変えて試験し、試験後のはくり及びクリープを評価した結果を示す。なお、内外輪の素材は表３の実施例３４の鋼種を適用して、焼戻しによる寸法安定化条件を変えると共に、浸炭窒化条件を制御して窒素濃度や炭素濃度を変化させた。 Next, Table 2 is tested by changing the amount of retained austenite on the surface of the raceway surface of the inner and outer rings, the amount of retained austenite of the core, the nitrogen concentration, the carbon concentration, and the sum of the nitrogen concentration and the carbon concentration. The result of creep evaluation is shown. In addition, the steel grade of Example 34 of Table 3 was applied to the material of the inner and outer rings, the dimensional stabilization conditions by tempering were changed, and the carbonitriding conditions were controlled to change the nitrogen concentration and the carbon concentration.
表２から判るように、軌道表面の残留オーステナイト量が本発明範囲外の比較例６は試験後の観察ではくりが発生していた。また、心部の残留オーステナイト量が本発明範囲外の比較例４，５は残留オーステナイトの分解により、内輪が膨張して軸との嵌め合いが緩んで滑ってしまうクリープ現象が発生した。
これに対し、本発明の実施例８〜３２では試験後の軸受は摩耗やはくり及びクリープによる損傷は全くないか、あっても極めて軽微であり、長寿命が得られる結果となった。特に、軌道面表面の窒素濃度が０．１％以上で徐々に耐摩耗性の向上効果が高まり、０．１３％以上になるとより安定した耐摩耗性が得られ、さらに、０．３％以上では殆ど摩耗しないのが判る（図３参照）。
また、軌道面表面の窒素濃度と炭素濃度との和が１．１％以上で徐々に耐摩耗性の向上効果が高まり、１．２％以上になるとより安定した耐摩耗性が得られるのが判る（図４参照）。
次に、表３に内外輪の鋼種を変えて試験し、試験後のはくり及びクリープを評価した結果を示す。
As can be seen from Table 2, in Comparative Example 6 in which the amount of retained austenite on the surface of the raceway was outside the range of the present invention, cracking occurred in observation after the test. Further, in Comparative Examples 4 and 5 in which the amount of retained austenite at the core was outside the range of the present invention, a creep phenomenon occurred in which the inner ring expanded due to decomposition of the retained austenite and the fitting with the shaft loosened and slipped.
On the other hand, in Examples 8 to 32 of the present invention, the bearings after the test were not damaged at all by wear, peeling, and creep, and even if they were very slight, a long life was obtained. In particular, when the nitrogen concentration on the raceway surface is 0.1% or more, the effect of improving the wear resistance is gradually increased, and when it is 0.13% or more, more stable wear resistance is obtained. Then, it can be seen that there is almost no wear (see FIG. 3).
Further, when the sum of the nitrogen concentration and the carbon concentration on the raceway surface is 1.1% or more, the effect of improving the wear resistance is gradually increased, and when it is 1.2% or more, more stable wear resistance is obtained. You can see (see Figure 4).
Next, Table 3 shows the results of testing by changing the steel type of the inner and outer rings and evaluating the peeling and creep after the test.
表３は全て本発明例である実施例３３〜４４を示しており、十分な耐摩耗性、長寿命、耐クリープ性能が得られているが、内外輪の材料成分が重量％で、Ｃ：０．２％以上０．７％以下、Ｓｉ：０．１５％以上１．０％以下、Ｍｎ：０．３％以上２．０％以下、Ｃｒ：１．０％以上２．０％以下の範囲内とされた実施例３３〜４１に関しては本発明の効果を更に有効にすることが確認できた。 Table 3 shows Examples 33 to 44 which are all examples of the present invention, and sufficient wear resistance, long life and creep resistance performance are obtained. However, the material composition of the inner and outer rings is% by weight, and C: 0.2% to 0.7%, Si: 0.15% to 1.0%, Mn: 0.3% to 2.0%, Cr: 1.0% to 2.0% It was confirmed that the effects of the present invention were made more effective with respect to Examples 33 to 41 within the range.
１ 内輪
２ 外輪
３ 転動体
1
Claims (2)
前記内輪又は前記内外輪に浸炭窒化処理を施し、更に、寸法安定化処理を施すことで心部の残留オーステナイト量を５体積％未満とし、且つ表面の残留オーステナイト量を５体積％以上としたことを特徴とする転がり軸受。 A compressor in which a plurality of rolling elements are disposed between an inner ring and an outer ring so as to be able to roll in the circumferential direction, and the inner ring is fixed by a fitting mechanism, and is operated under refrigerating machine oil lubrication containing refrigerant. In the rolling bearing used,
The inner ring or the inner and outer rings were subjected to carbonitriding, and further subjected to dimensional stabilization treatment so that the amount of retained austenite at the core was less than 5% by volume and the amount of retained austenite at the surface was at least 5% by volume. Rolling bearing characterized by
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| JP2004084473A JP2005273471A (en) | 2004-03-23 | 2004-03-23 | Rolling bearing |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2004084473A JP2005273471A (en) | 2004-03-23 | 2004-03-23 | Rolling bearing |
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| JP2005273471A true JP2005273471A (en) | 2005-10-06 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007321816A (en) * | 2006-05-30 | 2007-12-13 | Nsk Ltd | Rolling bearing |
| JP2008150672A (en) * | 2006-12-18 | 2008-07-03 | Nsk Ltd | Rolling shaft |
| JP2008223104A (en) * | 2007-03-14 | 2008-09-25 | Nsk Ltd | Rolling shaft |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1068419A (en) * | 1996-06-17 | 1998-03-10 | Nippon Seiko Kk | Rolling bearing |
| JPH11100643A (en) * | 1997-09-25 | 1999-04-13 | Ntn Corp | Rolling bearing |
| JP2002339975A (en) * | 2001-05-15 | 2002-11-27 | Nsk Ltd | Ball bearings for scroll compressors |
-
2004
- 2004-03-23 JP JP2004084473A patent/JP2005273471A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1068419A (en) * | 1996-06-17 | 1998-03-10 | Nippon Seiko Kk | Rolling bearing |
| JPH11100643A (en) * | 1997-09-25 | 1999-04-13 | Ntn Corp | Rolling bearing |
| JP2002339975A (en) * | 2001-05-15 | 2002-11-27 | Nsk Ltd | Ball bearings for scroll compressors |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007321816A (en) * | 2006-05-30 | 2007-12-13 | Nsk Ltd | Rolling bearing |
| JP2008150672A (en) * | 2006-12-18 | 2008-07-03 | Nsk Ltd | Rolling shaft |
| JP2008223104A (en) * | 2007-03-14 | 2008-09-25 | Nsk Ltd | Rolling shaft |
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