JP2006348342A

JP2006348342A - Rolling support device

Info

Publication number: JP2006348342A
Application number: JP2005175196A
Authority: JP
Inventors: Takashi Sakaguchi; 尚坂口
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2005-06-15
Filing date: 2005-06-15
Publication date: 2006-12-28

Abstract

【課題】転がり疲れ寿命の長い転がり軸受を低コストで提供する。
【解決手段】内外輪１，２は、Ｃ：０．２〜１．２％、Ｓｉ：０．１５〜２．０％、Ｍｎ：０．２〜２．０％、Ｃｒ：０．５〜２．０％、Ｍｏ：２．０％以下、Ｖ：２．０％以下、Ｏ：１２ｐｐｍ以下、残部：Ｆｅ及び不可避不純物の鋼に浸炭又は浸炭窒化を含む熱処理を施して作製する。軌道面１ａ，２ａをなす表層部は、Ｎ＋Ｃ：０．７〜４．０％、γ_R：２０〜４０％、Ｈｖ６５０以上とする。ころ３は、Ｃ：０．２〜１．２％、Ｓｉ：０．４〜２．０％、Ｍｎ：０．２〜２．０％、Ｃｒ：０．５〜２．０％、Ｏ：１２ｐｐｍ以下、残部：Ｆｅ及び不可避不純物の鋼に浸炭窒化を含む熱処理を施して作製する。転動面３ａをなす表層部は、Ｎ：０．２０〜２．００％、Ｎ＋Ｃ：０．７〜４．０％、γ_R：２０〜２４％、Ｈｖ７００以上とし、転動面３ａの表面粗さは、軌道面１ａ，２ａより小さくする。
【選択図】図１PROBLEM TO BE SOLVED: To provide a rolling bearing having a long rolling fatigue life at a low cost.
SOLUTION: Inner and outer rings 1 and 2 are: C: 0.2 to 1.2%, Si: 0.15 to 2.0%, Mn: 0.2 to 2.0%, Cr: 0.5 to 2.0%, Mo: 2.0% or less, V: 2.0% or less, O: 12ppm or less, balance: Fe and inevitable impurities steel is subjected to heat treatment including carburizing or carbonitriding. The surface layer portions forming the raceway surfaces 1a and 2a are N + C: 0.7 to 4.0%, γ _R : 20 to 40%, and Hv650 or more. Roller 3 is C: 0.2-1.2%, Si: 0.4-2.0%, Mn: 0.2-2.0%, Cr: 0.5-2.0%, O: It is produced by subjecting steel of 12 ppm or less and the balance: Fe and inevitable impurities to heat treatment including carbonitriding. The surface layer portion forming the rolling surface 3a is N: 0.20 to 2.00%, N + C: 0.7 to 4.0%, γ _R : 20 to 24%, Hv 700 or more, and the surface of the rolling surface 3a The roughness is made smaller than the raceway surfaces 1a and 2a.
[Selection] Figure 1

Description

本発明は、転がり軸受、リニアガイド、ボールねじ等の転がり支持装置に関する。 The present invention relates to a rolling support device such as a rolling bearing, a linear guide, and a ball screw.

転がり支持装置の一例である転がり軸受は、高面圧下で繰り返し剪断応力を受けて使用されるため、この剪断応力に耐えて転がり疲れ寿命を確保する必要がある。このため、転がり軸受の軌道輪（内輪や外輪）及び転動体としては、高炭素クロム軸受鋼二種（ＳＵＪ２）に焼入れ及び焼戻し処理を施したり、肌焼鋼（ＳＣＲ４２０，ＳＣＭ４２０，ＳＡＥ４３２０Ｈ等）に浸炭又は浸炭窒化処理、焼入れ及び焼戻し処理を施すことにより、表面硬さをＨｖ６５０〜８００としたものが用いられている。 A rolling bearing, which is an example of a rolling support device, is used under repeated shear stress under high surface pressure, and therefore needs to withstand this shear stress to ensure a rolling fatigue life. For this reason, as the bearing rings (inner and outer rings) and rolling elements of the rolling bearing, high-carbon chromium bearing steel type 2 (SUJ2) is subjected to quenching and tempering treatment, or case-hardened steel (SCR420, SCM420, SAE4320H, etc.). Carburizing or carbonitriding treatment, quenching and tempering treatment are used to make the surface hardness Hv650-800.

近年、自動車，工作機械，一般産業機械，鉄鋼設備等の動力伝達機構や支持機構の高能率化及び小型化を実現するために、これらの機構で使用される転がり軸受は、高速条件，高荷重条件，高温条件等の苛酷な環境下で使用されることが多くなってきている。
特に、高荷重条件下で使用される転がり軸受では、軌道面に油膜が形成され難く、軌道輪と転動体との間に金属接触が生じて、その転がり面（軌道面や転動面）に大きな接線力が発生するため、表面損傷が起こり易い。また、高荷重条件下で使用される転がり軸受では、軌道輪と転動体との間にスキューによるすべりが生じ易く、軌道輪と転動体との間に繰り返し剪断応力や大きな接線力が発生するため、表面損傷が起こり易い。 In recent years, rolling bearings used in these mechanisms to achieve high efficiency and miniaturization of power transmission mechanisms and support mechanisms for automobiles, machine tools, general industrial machines, steel equipment, etc. It is increasingly used in harsh environments such as conditions and high temperature conditions.
In particular, in rolling bearings used under high load conditions, it is difficult to form an oil film on the raceway surface, and metal contact occurs between the raceway and the rolling element, and the rolling surface (the raceway surface or the rolling surface) is formed. Since a large tangential force is generated, surface damage is likely to occur. Also, in rolling bearings used under high load conditions, slip due to skew is likely to occur between the bearing ring and the rolling element, and repeated shear stress and large tangential force are generated between the bearing ring and the rolling element. Surface damage is likely to occur.

表面損傷による寿命低下は、上述した潤滑不足やすべりによって転がり面に大きな接線力が発生した場合に加えて、異物が混入された潤滑条件下（以下、「異物混入潤滑下」と記す。）で異物の噛み込みによって転がり面に圧痕が生じ、圧痕の縁に応力集中が発生した場合にも起こる。
このような表面損傷による寿命低下を防止するための技術として、特許文献１及び特許文献２に記載の技術が提案されている。 Life reduction due to surface damage occurs under the lubrication conditions in which foreign matter is mixed in addition to the case where a large tangential force is generated on the rolling surface due to insufficient lubrication or slip as described above (hereinafter referred to as “under foreign matter mixed lubrication”). This also occurs when an indentation is generated on the rolling surface due to the biting of foreign matter, and stress concentration occurs on the edge of the indentation.
As a technique for preventing a decrease in life due to such surface damage, techniques described in Patent Document 1 and Patent Document 2 have been proposed.

特許文献１では、少なくとも軌道輪を、質量比で、Ｃ含有率が０．８％以上１．２％以下、Ｓｉ含有率が０．４％以上１．０％以下、Ｃｒ含有率が０．２％以上１．２％以下、Ｍｎ含有率が０．８％以上１．５％以下の鋼からなる素材を所定形状に加工した後、浸炭窒化処理と、８３０〜８７０℃での焼入れ処理と、１６０〜１９０℃での焼戻し処理とを施すことで作製し、その表層部の残留オーステナイト量を２５体積％以上５０体積％以下とすることが提案されている。また、特許文献１には、異物混入下で優れた転がり疲れ寿命を得るために、表層部の残留オーステナイト量を２５体積％以上３０体積％以下として、特定の表面硬さを確保することが好ましいと記載されている。 In Patent Document 1, at least the race is in mass ratio, the C content is 0.8% to 1.2%, the Si content is 0.4% to 1.0%, and the Cr content is 0.00. After processing a material made of steel of 2% or more and 1.2% or less and a Mn content of 0.8% or more and 1.5% or less into a predetermined shape, carbonitriding and quenching at 830 to 870 ° C. And a tempering treatment at 160 to 190 ° C., and the amount of retained austenite in the surface layer portion is proposed to be 25% by volume or more and 50% by volume or less. Further, in Patent Document 1, it is preferable to secure a specific surface hardness by setting the amount of retained austenite in the surface layer part to 25 vol% or more and 30 vol% or less in order to obtain an excellent rolling fatigue life in the presence of foreign matter. It is described.

特許文献２では、少なくともころを、質量比で、Ｃ含有率が０．８％以上１．５％以下、Ｓｉ含有率が０．４％以上１．２％以下、Ｍｎ含有率が０．８％以上１．５％以下、Ｃｒ含有率が０．８％以上１．８％以下の鋼からなる素材を所定形状に加工した後、浸炭窒化処理と、焼入れ処理及び焼戻し処理とを施すことで作製し、表層部の残留オーステナイト量を２０％体積以上４０体積％以下とし、表面硬さをＨｖ７５０以上とすることが提案されている。
特開平７−１９００７２号公報特開２０００−２３４１４７号公報 In Patent Document 2, at least the rollers are in a mass ratio, the C content is 0.8% to 1.5%, the Si content is 0.4% to 1.2%, and the Mn content is 0.8. % After processing a material made of steel with a Cr content of 0.8% or more and 1.8% or less to a predetermined shape, followed by carbonitriding, quenching and tempering. It has been proposed that the amount of retained austenite in the surface layer portion is 20% to 40% by volume and the surface hardness is Hv 750 or more.
Japanese Patent Laid-Open No. 7-190072 JP 2000-234147 A

しかしながら、上述した特許文献１及び２に記載の技術では、表層部の残留オーステナイト量と硬さとをともに大きくすることで転がり疲れ寿命の向上を図っているため、製造コストを削減するという点でさらなる改善の余地がある。
また、特許文献１及び２に記載の軸受では、表面損傷による寿命低下が問題となる転動部材の寿命についてのみ考慮されており、それ以外の転動部材の寿命については考慮されていない。このため、寿命低下が問題となる転動部材の寿命のみを長くしても、それ以外の転動部材の寿命が不足して、装置全体の寿命を長くできない場合がある。
そこで、本発明は、これらの問題を解決するためになされたものであり、表面損傷が生じ易い環境下で使用されても、転がり疲れ寿命の長い転がり支持装置を低コストで提供することを課題としている。 However, in the techniques described in Patent Documents 1 and 2 described above, since the rolling fatigue life is improved by increasing both the amount of retained austenite and the hardness of the surface layer portion, it is further possible to reduce the manufacturing cost. There is room for improvement.
Further, in the bearings described in Patent Documents 1 and 2, only the life of the rolling member in which the life reduction due to surface damage is a problem is considered, and the life of other rolling members is not considered. For this reason, even if only the life of the rolling member in which the life reduction is a problem is lengthened, the life of the other rolling members may be insufficient and the life of the entire apparatus may not be lengthened.
Therefore, the present invention has been made to solve these problems, and it is an object to provide a rolling support device having a long rolling fatigue life at a low cost even when used in an environment in which surface damage is likely to occur. It is said.

このような課題を解決するために、本発明者は、第一部材及び第二部材の転がり疲れ寿命と、転動体の転がり疲れ寿命との相互バランスについて鋭意検討を重ねた結果、転がり支持装置全体として転がり疲れ寿命を長くできる第一部材部材及び第二部材と転動体との組合せを見出し、本発明を完成させた。 In order to solve such a problem, the present inventor conducted extensive studies on the mutual balance between the rolling fatigue life of the first member and the second member and the rolling fatigue life of the rolling element, and as a result, the entire rolling support device As a result, the first member and the combination of the second member and the rolling element capable of extending the rolling fatigue life were found, and the present invention was completed.

すなわち、本発明は、互いに対向する軌道面を有する第一部材及び第二部材と、前記第一部材及び前記第二部材の間に転動自在に配設され、前記軌道面に対する転動面を有する転動体と、を備え、前記転動体が転動することにより、前記第一部材及び前記第二部材のうち一方が他方対して相対運動する転がり支持装置において、前記第一部材及び前記第二部材は、Ｃ含有率が０．２質量％以上１．２質量％以下、Ｓｉ含有率が０．１５質量％以上２．０質量％以下、Ｍｎ含有率が０．２質量％以上２．０質量％以下、Ｃｒ含有率が０．５質量％以上２．０質量％以下、Ｍｏ含有率が２．０質量％以下、Ｖ含有率が２．０質量％以下、Ｏ含有率が１２ｐｐｍ以下、残部がＦｅ及び不可避不純物である鋼からなる素材を所定形状に加工した後、浸炭処理又は浸炭窒化処理を含む熱処理が施されて得られ、その軌道面をなす表層部は、Ｎ及びＣの合計含有率が０．７質量％以上４．０質量％以下で、残留オーステナイト量が２０体積％以上４０体積％以下で、硬さがＨｖ６５０以上であり、前記転動体は、Ｃ含有率が０．２質量％以上１．２質量％以下、Ｓｉ含有率が０．４質量％以上２．０質量％以下、Ｍｎ含有率が０．２質量％以上２．０質量％以下、Ｃｒ含有率が０．５質量％以上２．０質量％以下、Ｏ含有率が１２ｐｐｍ以下、残部がＦｅ及び不可避不純物である鋼からなる素材を所定形状に加工した後、浸炭窒化処理を含む熱処理が施されて得られ、その転動面をなす表層部は、Ｎ含有率が０．２０質量％以上２．００質量％以下で、Ｎ及びＣの合計含有率が０．８質量％以上４．０質量％以下で、残留オーステナイト量が２０体積％以上２４体積％以下で、硬さはＨｖ７００以上であるとともに、前記転動面の表面粗さ（Ｒａ）は、前記軌道面の表面粗さ（Ｒａ）よりも小さくなっていることを特徴とする転がり支持装置を提供する。 That is, this invention is arrange | positioned so that rolling is possible between the said 1st member and said 2nd member, and the 1st member and 2nd member which have mutually opposing track surface, The rolling surface with respect to the said track surface is provided. A rolling support device in which one of the first member and the second member moves relative to the other when the rolling body rolls, wherein the first member and the second member The member has a C content of 0.2 mass% to 1.2 mass%, an Si content of 0.15 mass% to 2.0 mass%, and an Mn content of 0.2 mass% to 2.0 mass%. Mass% or less, Cr content of 0.5 mass% or more and 2.0 mass% or less, Mo content of 2.0 mass% or less, V content of 2.0 mass% or less, O content of 12 ppm or less, After processing the material made of steel with the balance being Fe and inevitable impurities into a predetermined shape, The surface layer part that forms the raceway surface of the surface layer portion that is obtained by heat treatment or carbonitriding treatment has a total content of N and C of 0.7% by mass to 4.0% by mass, and the amount of retained austenite is 20% by volume or more and 40% by volume or less, the hardness is Hv650 or more, and the rolling element has a C content of 0.2% by mass or more and 1.2% by mass or less, and an Si content of 0.4% by mass or more 2.0 mass% or less, Mn content is 0.2 mass% or more and 2.0 mass% or less, Cr content is 0.5 mass% or more and 2.0 mass% or less, O content is 12 ppm or less, and the balance is After processing a material composed of Fe and steel, which is an unavoidable impurity, into a predetermined shape, it is obtained by heat treatment including carbonitriding, and the surface layer portion that forms the rolling surface has an N content of 0.20% by mass. More than 2.00% by mass and the total content of N and C is 0.8% by mass or more 0.0 mass% or less, the residual austenite amount is 20 volume% or more and 24 volume% or less, the hardness is Hv 700 or more, and the surface roughness (Ra) of the rolling surface is the surface roughness of the raceway surface. Provided is a rolling support device characterized by being smaller than (Ra).

なお、本発明において「転がり支持装置」とは、例えば、転がり軸受、ボールねじ、リニアガイドを指す。ここで、転がり支持装置が転がり軸受の場合には、第一部材及び第二部材は内輪及び外輪を指す。また、転がり支持装置がボールねじの場合には、第一部材及び第二部材はねじ軸及びナットを指す。さらに、転がり支持装置がリニアガイドの場合には、第一部材及び第二部材は案内レール及びスライダを指す。
また、本発明において「表層部」とは、表面から所定深さ（例えば、１μｍ）までの範囲を指す。 In the present invention, the “rolling support device” refers to, for example, a rolling bearing, a ball screw, and a linear guide. Here, when the rolling support device is a rolling bearing, the first member and the second member indicate an inner ring and an outer ring. When the rolling support device is a ball screw, the first member and the second member indicate a screw shaft and a nut. Furthermore, when the rolling support device is a linear guide, the first member and the second member indicate a guide rail and a slider.
In the present invention, the “surface layer portion” refers to a range from the surface to a predetermined depth (for example, 1 μm).

以下、本発明の数値限定の臨界的意義について説明する。
まず、転動部材（第一部材、第二部材、転動体）の素材をなす鋼について詳細に説明する。
〔Ｃ含有率：（転動部材全て）０．２〜１．２質量％〕
Ｃ（炭素）は、基地をマルテンサイト化することにより、強度を増加させる作用を有する。本発明においては、鋼からなる素材を所定形状に加工した後に浸炭窒化処理又は浸炭処理を含む熱処理が施されるため、転動部材の表層部にはＮ（窒素）やＣが添加される。
よって、転動部材の素材をなすＣ含有率は、転動部材の芯部に必要な強度を確保するために、いずれも０．２％以上とする。なお、転動部材の芯部を好ましい硬さＨｖ６５０以上にするために、素材をなすＣ含有率は、いずれも０．８％以上とすることが好ましい。一方、素材をなすＣ含有率が多過ぎると、製鋼時に粗大な炭化物が生成して、転がり疲れ寿命を低下させる場合がある。よって、転動部材の素材をなすＣ含有率は、いずれも１．２％以下とする。 Hereinafter, the critical significance of the numerical limitation of the present invention will be described.
First, the steel which makes the raw material of a rolling member (a 1st member, a 2nd member, a rolling element) is demonstrated in detail.
[C content: (all rolling members) 0.2 to 1.2% by mass]
C (carbon) has the effect of increasing the strength by converting the base into martensite. In the present invention, N (nitrogen) or C is added to the surface layer portion of the rolling member because a heat treatment including carbonitriding or carburizing is performed after a steel material is processed into a predetermined shape.
Therefore, in order to ensure the strength required for the core portion of the rolling member, the C content constituting the rolling member material is 0.2% or more. In addition, in order to make the core part of a rolling member into preferable hardness Hv650 or more, it is preferable that all the C content rate which makes a raw material shall be 0.8% or more. On the other hand, when there is too much C content which makes a raw material, a coarse carbide | carbonized_material will produce | generate at the time of steelmaking, and rolling fatigue life may be reduced. Accordingly, the C content constituting the rolling member is 1.2% or less.

〔Ｓｉ含有率：（第一部材及び第二部材）０．１５〜２．０質量％，（転動体）０．４〜２．０質量％〕
Ｓｉ（ケイ素）は、鋼の焼戻し軟化抵抗性を強化し、疲労強度を増加させる作用を有するとともに、浸炭層や浸炭窒化層のＮ含有率やＣ含有率を安定して得る作用を有する。これらの作用を得るために、第一部材及び第二部材の素材をなすＳｉ含有率は、０．１５質量％以上とし、転動体の素材をなすＳｉ含有率は０．４質量％以上とする。
一方、素材をなすＳｉ含有率が多過ぎると、浸炭窒化処理時に浸炭窒化層の生成を阻害したり、切削性を低下させたりする場合がある。よって、転動部材の素材をなすＳｉ含有率は、いずれも２．０質量％以下とする。 [Si content: (first member and second member) 0.15 to 2.0 mass%, (rolling element) 0.4 to 2.0 mass%]
Si (silicon) has the effect of strengthening the temper softening resistance of steel and increasing the fatigue strength, and also has the effect of stably obtaining the N content and C content of the carburized layer and carbonitrided layer. In order to obtain these effects, the Si content forming the material of the first member and the second member is 0.15% by mass or more, and the Si content forming the material of the rolling element is 0.4% by mass or more. .
On the other hand, if the Si content constituting the material is too large, the formation of a carbonitriding layer may be hindered during the carbonitriding process, or the machinability may be reduced. Accordingly, the Si content constituting the rolling member is 2.0% by mass or less.

〔Ｍｎ含有率：（転動部材全て）０．２〜２．０質量％〕
Ｍｎ（マンガン）は、Ｓｉと同様に、浸炭層や浸炭窒化層のＮ含有率やＣ含有率を安定して得る作用を有するとともに、製鋼時の脱酸剤や脱硫剤としての作用を有する。これらの作用を得るために、転動部材の素材をなすＭｎ含有率は、いずれも０．２質量％以上とする。
また、Ｓｉに加えてＭｎを添加することにより、研磨取り代の多い形状の転動体であっても、その転動面をなす表層部に本発明範囲のＮ含有率を安定して確保できる。
一方、素材をなすＭｎ含有率が多過ぎると、鋼中に存在する非金属介在物が多くなり過ぎて転がり疲れ寿命が低下したり、素材の鍛造性や被削性当の機械加工性が低下したりする場合がある。よって、転動部材の素材をなすＭｎ含有率は、いずれも２．０質量％以下とする。 [Mn content: (all rolling members) 0.2 to 2.0 mass%]
Mn (manganese) has the effect of stably obtaining the N content and C content of the carburized layer and the carbonitrided layer, as well as Si, and also acts as a deoxidizer and desulfurizer during steelmaking. In order to obtain these effects, the Mn content constituting the rolling member is 0.2% by mass or more.
Further, by adding Mn in addition to Si, it is possible to stably secure the N content in the range of the present invention in the surface layer portion forming the rolling surface even if the rolling element has a shape with a large polishing allowance.
On the other hand, if the Mn content of the material is too large, the amount of non-metallic inclusions present in the steel will increase and the rolling fatigue life will decrease, and the forgeability and machinability of the material will decrease. There is a case to do. Therefore, the Mn content constituting the rolling member is 2.0% by mass or less.

〔Ｃｒ含有率：（転動部材全て）０．５〜２．０質量％〕
Ｃｒ（クロム）は、焼入れ性及び焼戻し軟化抵抗性を向上させるとともに、基地を強化して転がり疲れ寿命を長くする作用を有する。また、微細で高硬度の炭化物や炭窒化物を生成して、耐摩耗性を向上させる作用も有する。さらに、浸炭層又は浸炭窒化層のＣ含有率を安定して得ることで、浸炭窒化特性を向上させる作用も有する。これらの作用を得るために、転動部材をなす素材のＣｒ含有率は、いずれも０．５％以上とする。
一方、素材をなすＣｒ含有率が多過ぎると、その効果が飽和するだけでなく、表層部に不動態膜が形成されて浸炭窒化特性を阻害する場合があるため、転動部材の素材をなすＣｒ含有率は、いずれも２．０％以下とする。 [Cr content: (all rolling members) 0.5 to 2.0 mass%]
Cr (chromium) improves the hardenability and temper softening resistance, and has the effect of strengthening the base and extending the rolling fatigue life. Moreover, it has the effect | action which produces | generates the fine and high hardness carbide | carbonized_material and carbonitride, and improves abrasion resistance. Furthermore, it has the effect | action which improves a carbonitriding characteristic by obtaining C content rate of a carburized layer or a carbonitriding layer stably. In order to obtain these effects, the Cr content of the material constituting the rolling member is 0.5% or more.
On the other hand, if the Cr content constituting the material is too large, not only the effect is saturated, but also a passive film is formed on the surface layer portion, which may impair the carbonitriding characteristics. The Cr content is 2.0% or less in all cases.

〔Ｍｏ含有率：２．０質量％以下〕
Ｍｏ（モリブデン）は、基地に固溶して焼入れ性及び焼戻し軟化抵抗性を向上させる作用を有するとともに、微細で高硬度の炭窒化物を生成して、硬さを向上させ、かつ、疲労強度を向上させる作用を有する。これらの作用を得るために、第一部材及び第二部材の素材をなすＭｏ含有率は、０．５質量％以上とする。
しかしながら、Ｍｏを添加させるとコストが上昇するため、Ｍｏは第一部材及び第二部材のみに添加し、その上限値を２．００質量とする。 [Mo content: 2.0% by mass or less]
Mo (molybdenum) has the effect of improving the hardenability and temper softening resistance by forming a solid solution in the base, producing fine and high hardness carbonitrides, improving the hardness, and fatigue strength. It has the effect | action which improves. In order to obtain these effects, the Mo content constituting the material of the first member and the second member is 0.5 mass% or more.
However, since the cost increases when Mo is added, Mo is added only to the first member and the second member, and the upper limit is 2.00 mass.

〔Ｖ含有率：２．００質量％以下〕
Ｖ（バナジウム）は、高硬度な炭窒化物を生成して、硬さを向上させるとともに、熱処理時の結晶粒の成長を抑制する作用を有する。これらの作用を得るために、第一部材及び第二部材の素材をなすＶ含有率は、０．５質量％以上とする。
しかしながら、Ｖを添加させると、Ｍｏと同様にコストが上昇するため、Ｖは第一部材及び第二部材のみに添加し、その上限値を２．０質量％以下とする。 [V content: 2.00% by mass or less]
V (vanadium) has a function of generating high-hardness carbonitrides to improve hardness and to suppress the growth of crystal grains during heat treatment. In order to obtain these effects, the V content constituting the material of the first member and the second member is 0.5% by mass or more.
However, when V is added, the cost increases as in the case of Mo. Therefore, V is added only to the first member and the second member, and the upper limit is set to 2.0 mass% or less.

〔Ｏ含有率：（転動部材全て）１２ｐｐｍ以下〕
Ｏ（酸素）は、転がり疲れ寿命に悪影響を与える酸化物系非金属介在物を生成するため、その含有率を出来る限り少なくする必要がある。このため、転動部材の素材をなすＯ含有率は、いずれも１２ｐｐｍ以下、好ましくは９ｐｐｍ以下とする。 [O content: (all rolling members) 12 ppm or less]
O (oxygen) generates oxide-based non-metallic inclusions that adversely affect the rolling fatigue life, so the content must be reduced as much as possible. For this reason, the O content constituting the rolling member is 12 ppm or less, preferably 9 ppm or less.

〔不可避不純物について〕
本発明の第一部材及び第二部材に用いる鋼には、上述した元素以外に、例えばＰ（リン），Ｓ（硫黄），Ｎｉ（ニッケル），Ｃｕ（銅），Ａｌ（アルミニウム），Ｔｉ（チタン），Ｎｂ（ニオブ）等の不可避不純物が含まれていてもよいし、本発明の転動体に用いる鋼には、上述した不可避不純物に加えて、さらにＭｏやＶが含まれていてもよい。これらの元素は、コストの許す限り添加してもよいが、その添加量は合計で２．０質量％以下とすることが好ましい。 [About inevitable impurities]
In addition to the elements described above, the steel used for the first member and the second member of the present invention includes, for example, P (phosphorus), S (sulfur), Ni (nickel), Cu (copper), Al (aluminum), Ti ( Inevitable impurities such as titanium) and Nb (niobium) may be contained, and the steel used for the rolling element of the present invention may further contain Mo and V in addition to the above-described inevitable impurities. . These elements may be added as long as the cost permits, but the total addition amount is preferably 2.0% by mass or less.

続いて、上述した鋼からなる素材に対して施す熱処理について詳細に説明する。
〔転動部材の熱処理について〕
まず、上述した鋼からなる素材を、鍛造又は切削により転動部材の所定形状に加工した後、混合ガス（例えば、ＲＸガス＋エンリッチガス＋アンモニアガス）を導入した炉内で、所定時間加熱保持することにより浸炭窒化処理を行う。なお、第一部材及び第二部材は、上述した浸炭窒化処理の代わりに、混合ガス（例えば、ＲＸガス＋エンリッチガス）を導入した炉内で、所定時間加熱保持することによる浸炭処理を行ってもよい。 Then, the heat processing performed with respect to the raw material which consists of steel mentioned above is demonstrated in detail.
[About heat treatment of rolling members]
First, the above-mentioned steel material is processed into a predetermined shape of the rolling member by forging or cutting, and then heated and held for a predetermined time in a furnace in which a mixed gas (for example, RX gas + enrich gas + ammonia gas) is introduced. Thus, carbonitriding is performed. The first member and the second member are subjected to a carburizing process by heating and holding for a predetermined time in a furnace in which a mixed gas (for example, RX gas + enriched gas) is introduced instead of the carbonitriding process described above. Also good.

この浸炭処理や浸炭窒化処理は、転動部材の転がり面（第一部材及び第二部材の各軌道面や、転動体の転動面）をなす表層部に、それぞれ本発明範囲のＮやＣを付与できる条件で行う。
転動部材の転がり面をなす表層部に存在するＮは、経時変化に影響を及ぼす耐圧痕性や耐摩耗性を向上させることにより、転動部材の転がり疲れ寿命を長くする作用を有する。このため、第一部材及び第二部材に対しても浸炭窒化処理を施して、その軌道面をなす表層部にＮを存在させることが好ましい。
この作用を得るために、第一部材及び第二部材の軌道面をなす表層部のＮ含有率は０．１０質量％以上とし、転動体の転動面をなす表層部のＮ含有率は０．２０質量％以上、好ましくは０．４０質量％以上とする。 This carburizing treatment or carbonitriding treatment is carried out on the surface layer portions forming the rolling surfaces of the rolling members (the raceway surfaces of the first member and the second member, and the rolling surfaces of the rolling elements), respectively. Is performed under the condition that can be applied.
N existing in the surface layer portion forming the rolling surface of the rolling member has the effect of extending the rolling fatigue life of the rolling member by improving the pressure scar resistance and wear resistance that affect the change with time. For this reason, it is preferable to subject the first member and the second member to carbonitriding so that N is present in the surface layer portion forming the raceway surface.
In order to obtain this effect, the N content of the surface layer portion forming the raceway surface of the first member and the second member is 0.10% by mass or more, and the N content of the surface layer portion forming the rolling surface of the rolling element is 0. 20% by mass or more, preferably 0.40% by mass or more.

一方、転動部材の転がり面をなす表層部に存在するＮが多過ぎると、表層部におけるＣｒの枯渇化により脆弱な窒化層が形成されて、表層部の硬さが低下したり、転がり疲れ寿命が低下したりするとともに、切削性が著しく劣化する場合がある。よって、第一部材及び第二部材の軌道面をなす表層部のＮ含有率は０．５０質量％以下とし、転動体の転動面をなす表層部のＮ含有率は２．００質量％以下、好ましくは１．５０質量％以下、より好ましくは１．００質量％以下とする。 On the other hand, if there is too much N present in the surface layer portion that forms the rolling surface of the rolling member, a brittle nitride layer is formed due to the depletion of Cr in the surface layer portion, and the hardness of the surface layer portion decreases or rolling fatigue occurs. In some cases, the service life is shortened and the machinability is remarkably deteriorated. Therefore, the N content of the surface layer portion forming the raceway surface of the first member and the second member is 0.50 mass% or less, and the N content of the surface layer portion forming the rolling surface of the rolling element is 2.00 mass% or less. , Preferably 1.50% by mass or less, more preferably 1.00% by mass or less.

また、転動部材の転がり面をなす表層部に存在するＣは、転動部材の転がり面をなす表層部に本発明範囲内の硬さを付与する作用を有する。このため、第一部材及び第二部材の軌道面をなす表層部のＣ含有率は０．６質量％以上として、その軌道面をなす表層部のＮ及びＣの合計含有率を０．７質量％以上とする。また、転動体の転動面をなす表層部のＣ含有率は０．６質量％以上として、その転動面をなす表層部のＮ及びＣの合計含有率を０．８質量％以上とする。 Moreover, C which exists in the surface layer part which makes the rolling surface of a rolling member has the effect | action which provides the hardness within the range of this invention to the surface layer part which makes the rolling surface of a rolling member. For this reason, the C content of the surface layer portion forming the raceway surface of the first member and the second member is 0.6% by mass or more, and the total content of N and C of the surface layer portion forming the track surface is 0.7 mass%. % Or more. Further, the C content of the surface layer part forming the rolling surface of the rolling element is 0.6% by mass or more, and the total content of N and C of the surface layer part forming the rolling surface is 0.8% by mass or more. .

一方、転動部材の転がり面をなす表層部のＣ含有率が多過ぎると、粗大な炭化物が析出して、転動部材の転がり疲れ寿命が低下する場合がある。よって、第一部材及び第二部材の軌道面をなす表層部のＣ含有率は２．５質量％以下として、その軌道面をなす表層部のＮ及びＣの合計含有率を４．０質量％以下とする。また、転動体の転動面をなす表層部のＣ含有率は２．５質量％以下、好ましくは２．０質量％以下として、その転動面をなす表層部のＮ及びＣの合計含有率を４．０質量％以下とする。 On the other hand, if the C content of the surface layer portion forming the rolling surface of the rolling member is too large, coarse carbides may precipitate, and the rolling fatigue life of the rolling member may be reduced. Therefore, the C content of the surface layer portion forming the raceway surface of the first member and the second member is 2.5 mass% or less, and the total content of N and C of the surface layer portion forming the raceway surface is 4.0 mass%. The following. Further, the C content of the surface layer part forming the rolling surface of the rolling element is 2.5% by mass or less, preferably 2.0% by mass or less, and the total content of N and C in the surface layer part forming the rolling surface Is 4.0 mass% or less.

なお、第一部材及び第二部材の軌道面をなす表層部の残留オーステナイト量と、転動体の転動面をなす表層部の残留オーステナイト量とが略同一である場合には、第一部材及び第二部材よりも、転動体の転がり疲れ寿命を長くするために、転動体の転動面をなす表層部のＮ含有率を、第一部材及び第二部材の軌道面をなす表層部のＮ含有率よりも多くすることが好ましい。 When the amount of retained austenite in the surface layer portion that forms the raceway surface of the first member and the second member and the amount of retained austenite in the surface layer portion that forms the rolling surface of the rolling element are substantially the same, the first member and In order to increase the rolling fatigue life of the rolling element as compared to the second member, the N content of the surface layer part forming the rolling surface of the rolling element is set to N of the surface layer part forming the raceway surface of the first member and the second member. It is preferable to make it larger than the content rate.

次に、焼入れ処理を行った後、焼戻し処理を行う。
この焼入れ処理及び焼戻し処理は、転動部材の転がり面をなす表層部に、それぞれ本発明範囲の残留オーステナイト量及び硬さを付与できる条件で行う。
転動部材をなす転がり面をなす表層部に存在する残留オーステナイト量は、転がり面に形成された圧痕縁への応力集中を低減させる作用を有する。この作用を得るために、転動部材の各表層部に存在する残留オーステナイト量は、２０体積％以上とする。 Next, after quenching, tempering is performed.
This quenching process and tempering process are performed under conditions that allow the surface layer portion forming the rolling surface of the rolling member to have a retained austenite amount and hardness within the scope of the present invention, respectively.
The amount of retained austenite present in the surface layer portion forming the rolling surface forming the rolling member has an action of reducing stress concentration on the indentation edge formed on the rolling surface. In order to obtain this effect, the amount of retained austenite present in each surface layer portion of the rolling member is 20% by volume or more.

一方、転動部材をなす転がり面をなす表層部に存在する残留オーステナイト量が多過ぎると、経時変化に影響を及ぼす耐圧痕性や耐摩耗性が低下したり、切削性が低下したりするため、転動体の経時変化を抑制することで、転動体と第一部材及び第二部材との間の摩擦を低減する効果が十分に得られなくなる。よって、第一部材及び第二部材の軌道面をなす表層部に存在する残留オーステナイト量は４０体積％以下とし、転動体の転動面をなす表層部に存在する残留オーステナイト量は２４体積％以下とする。 On the other hand, if the amount of retained austenite present in the surface layer portion that forms the rolling surface of the rolling member is excessive, the pressure resistance and wear resistance that affect the change over time may decrease, or the machinability may decrease. By suppressing the temporal change of the rolling elements, the effect of reducing the friction between the rolling elements and the first member and the second member cannot be sufficiently obtained. Therefore, the amount of residual austenite existing in the surface layer part forming the raceway surface of the first member and the second member is 40% by volume or less, and the amount of residual austenite existing in the surface layer part forming the rolling surface of the rolling element is 24% by volume or less. And

次に、転動体に対しては、ショットピーニング処理やバレルピーニング処理等のピーニング処理を施すことが好ましい。このピーニング処理は、転動体の転動面をなす表層部の残留オーステナイト量をさらに低減させるとともに、前記表層部の硬さをさらに向上できるため、転動体の経時変化をさらに抑制するために有効である。また、転動体に対してピーニング処理を施すことにより、転動体の半価幅も増加するため、転動体の転がり疲れ寿命も長くできる。
なお、転動面の圧縮応力が１０００ＭＰａを超えると、マイクロクラック等が発生して転がり疲れ寿命が低下する場合があるため、転動面の圧縮応力は１０００ＭＰａ以下となる条件で、ピーニング処理を行うことが好ましい。 Next, the rolling elements are preferably subjected to peening treatment such as shot peening treatment and barrel peening treatment. This peening treatment is effective in further reducing the amount of retained austenite in the surface layer part forming the rolling surface of the rolling element and further improving the hardness of the surface layer part, and further suppressing the temporal change of the rolling element. is there. Moreover, since the half-value width of a rolling element increases by performing a peening process with respect to a rolling element, the rolling fatigue life of a rolling element can also be lengthened.
Note that if the rolling surface compressive stress exceeds 1000 MPa, microcracks or the like may occur and the rolling fatigue life may decrease, so the peening treatment is performed under the condition that the rolling surface compressive stress is 1000 MPa or less. It is preferable.

次に、研削仕上げ加工を施して、転動体の転動面における表面粗さ（Ｒａ）を、第一部材及び第二部材の軌道面における表面粗さ（Ｒａ）よりも小さくなるようにする。これにより、潤滑不足やすべりによって転がり面に発生する接線力が低減し、表面損傷が生じ難くなる。
一方、転動体の転動面における表面粗さ（Ｒａ）を、第一部材及び第二部材の軌道面における表面粗さ（Ｒａ）よりも大きくすると、第一部材及び第二部材の転がり疲れ寿命が、転動体の転がり疲れ寿命よりも大幅に短くなるため、転がり支持装置全体の転がり疲れ寿命が著しく低下する。 Next, grinding finish processing is performed so that the surface roughness (Ra) on the rolling surface of the rolling element is smaller than the surface roughness (Ra) on the raceway surface of the first member and the second member. As a result, the tangential force generated on the rolling surface due to insufficient lubrication or slippage is reduced, and surface damage is less likely to occur.
On the other hand, if the surface roughness (Ra) on the rolling surface of the rolling element is larger than the surface roughness (Ra) on the raceway surface of the first member and the second member, the rolling fatigue life of the first member and the second member. However, since it is significantly shorter than the rolling fatigue life of the rolling elements, the rolling fatigue life of the entire rolling support device is significantly reduced.

本発明の転がり支持装置によれば、第一部材及び第二部材の転がり疲れ寿命と、転動体の転がり疲れ寿命との相互バランスを考慮して、転動体の残留オーステナイト量を低減し、且つ、表面窒素濃度を増加させたことにより、転動体の経時変化を抑制し、転動体と第一部材及び第二部材との間の摩擦を低減できるため、表面損傷による寿命低下を低コストで抑制できる。よって、表面損傷が生じ易い環境下で使用した場合でも、転がり疲れ寿命の長い転がり支持装置を低コストで提供できる。 According to the rolling support device of the present invention, considering the mutual balance between the rolling fatigue life of the first member and the second member and the rolling fatigue life of the rolling element, the amount of retained austenite of the rolling element is reduced, and By increasing the surface nitrogen concentration, the rolling element can be prevented from changing over time, and the friction between the rolling element and the first member and the second member can be reduced. . Therefore, even when used in an environment where surface damage is likely to occur, a rolling support device having a long rolling fatigue life can be provided at a low cost.

以下、本発明の実施形態について図面を参照しながら説明する。
＜第１実施形態＞
本実施形態では、図１に示す呼び番号Ｌ４４６４９の円錐ころ軸受（外径：５０．２９２ｍｍ，内径：２６．９８８ｍｍ，幅：１４．２２４ｍｍ）を、以下に示す方法で作製した。この円錐ころ軸受は、図１に示すように、内輪（第一部材）１と、外輪（第二部材）２と、内輪１及び外輪２の各軌道面１ａ，２ａ間に転動自在に配設された円錐状の複数のころ（転動体）３と、保持器４と、からなる。また、ころ３の大径側端面３ｂは、内輪１の大径側端部に形成された鍔部１０で保持されている。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<First Embodiment>
In this embodiment, a tapered roller bearing (outer diameter: 50.292 mm, inner diameter: 26.988 mm, width: 14.224 mm) having the identification number L44649 shown in FIG. 1 was produced by the following method. As shown in FIG. 1, this tapered roller bearing is disposed between an inner ring (first member) 1, an outer ring (second member) 2, and raceway surfaces 1 a and 2 a of the inner ring 1 and the outer ring 2 so as to be able to roll. It comprises a plurality of conical rollers (rolling elements) 3 and a cage 4. Further, the large diameter side end surface 3 b of the roller 3 is held by a flange portion 10 formed at the large diameter side end portion of the inner ring 1.

ころ３は、以下の手順で作製した。
まず、表１に示す各構成の鋼からなる素材を所定形状に加工した後、表１に示す各方法の熱処理を施した。
ここで、表１に「浸炭窒化焼入れ→焼戻し」で示す熱処理は、以下に示す条件で行った。まず、混合ガス（Ｒｘガス＋プロパンガス＋アンモニアガス）の雰囲気下で、アンモニアガスの流量を混合ガス全体の２〜９％とした条件下において、８３０〜８６０℃で４〜６時間保持することにより浸炭窒化を行った後、油焼入れを行った。次に、表１に示す各温度で２時間保持することにより焼戻しを行った。 The roller 3 was produced by the following procedure.
First, after processing the raw material which consists of steel of each structure shown in Table 1 into a predetermined shape, the heat processing of each method shown in Table 1 was given.
Here, the heat treatment shown in Table 1 as “carbonitriding quenching → tempering” was performed under the following conditions. First, in an atmosphere of a mixed gas (Rx gas + propane gas + ammonia gas), hold at 830 to 860 ° C. for 4 to 6 hours under the condition that the flow rate of ammonia gas is 2 to 9% of the total mixed gas. Then, carbonitriding was performed, followed by oil quenching. Next, tempering was performed by holding at each temperature shown in Table 1 for 2 hours.

また、表１に「浸炭窒化焼入れ→焼戻し→ショットピーニング」で示す熱処理は、以下に示す条件で行った。まず、上述と同様の浸炭窒化処理を行った後、油焼入れを行った。次に、表１に示す各温度で２時間保持することにより焼戻しを行った。次に、ころ３の転動面３ａに対して、ショット粒として、平均粒径が０．５０〜０．５４ｍｍで、表面硬さがＨＲＣ６１の鋼球を使用して、６０〜１２０ｍ／ｓのショット投射速度でショットピーニング処理を行った。 Moreover, the heat treatment shown in Table 1 as “carbonitriding quenching → tempering → shot peening” was performed under the following conditions. First, after carbonitriding similar to that described above, oil quenching was performed. Next, tempering was performed by holding at each temperature shown in Table 1 for 2 hours. Next, using a steel ball having an average particle diameter of 0.50 to 0.54 mm and a surface hardness of HRC61 as a shot grain with respect to the rolling surface 3a of the roller 3, the surface diameter is 60 to 120 m / s. The shot peening process was performed at the shot projection speed.

さらに、表１に「焼入れ→焼戻し」で示す熱処理は、以下に示す条件で行った。まず、Ｒｘガス雰囲気中において、８３０〜８６０℃で０．５〜１時間保持した後、油焼入れを行った。次に、１８０℃で２時間保持することにより焼戻しを行った。
次に、研削等の仕上げ加工を施して、転動面３ａの表面粗さ（Ｒａ）を０．０６μｍとなるように調整した。また、ころ３の軸方向端面における研磨取り代は、大径側端面３ｂ及び小径側端面３ｃでそれぞれ５０μｍずつとした。 Furthermore, the heat treatment shown in Table 1 as “quenching → tempering” was performed under the following conditions. First, in an Rx gas atmosphere, after holding at 830 to 860 ° C. for 0.5 to 1 hour, oil quenching was performed. Next, tempering was performed by holding at 180 ° C. for 2 hours.
Next, a finishing process such as grinding was performed to adjust the surface roughness (Ra) of the rolling surface 3a to 0.06 μm. Further, the grinding allowance on the axial end surface of the roller 3 was set to 50 μm for each of the large-diameter side end surface 3b and the small-diameter side end surface 3c.

そして、得られたころ３のうち破壊検査用のサンプルを用いて、転動面３ａをなす表層部（表面から１μｍの深さまでの部分）のＮ含有率（質量比）及びＣ含有率（質量比）と、前記表層部の残留オーステナイト量（体積比）と、前記表層部の硬さ（Ｈｖ）とを、以下に示す方法でそれぞれ測定した。これらの結果は、「Ｎ含有率」、「Ｎ＋Ｃ含有率」、「γ_R」、及び「硬さ」として、表１に併せて示した。
なお、前記表層部のＮ含有率及びＣ含有率は、電子線マイクロアナライザ (ＥＰＭＡ）を用いて測定した。また、前記表層部の残留オーステナイト量は、Ｘ線回折装置を用いて測定した。さらに、前記表層部の硬さは、ＪＩＳＺ２２４４に規定されたビッカース硬さ試験法を用いて測定した。 And the N content rate (mass ratio) and C content rate (mass) of the surface layer part (part from the surface to the depth of 1 micrometer) which make the rolling surface 3a using the sample for a destructive inspection among the obtained rollers 3. Ratio), the amount of retained austenite (volume ratio) of the surface layer portion, and the hardness (Hv) of the surface layer portion were measured by the following methods. These results are also shown in Table 1 as “N content”, “N + C content”, “γ _R ”, and “hardness”.
In addition, N content rate and C content rate of the said surface layer part were measured using the electron beam microanalyzer (EPMA). The amount of retained austenite in the surface layer was measured using an X-ray diffractometer. Furthermore, the hardness of the surface layer portion was measured using a Vickers hardness test method defined in JIS Z 2244.

内輪１及び外輪２は、以下に示す手順で作製した。
まず、ＪＩＳ鋼種である高炭素クロム軸受鋼二種（ＳＵＪ２）からなる素材を所定形状に加工した後、８３０〜８６０℃で０．５〜１時間保持した後に油焼入れを施した後、１８０℃で２時間保持することによる焼戻しを施すことにより、軌道面１ａ，２ａをなす表層部（表面から１μｍの深さまでの部分）の硬さをＨｖ６８０以上とし、前記表層部の残留オーステナイト量を９体積％とした。 The inner ring 1 and the outer ring 2 were produced by the following procedure.
First, after processing the raw material which consists of 2 types of high carbon chromium bearing steel (SUJ2) which is a JIS steel type into predetermined shape, after hold | maintaining at 830-860 degreeC for 0.5 to 1 hour, after oil quenching, 180 degreeC The surface layer part (part from the surface to a depth of 1 μm) forming the raceway surfaces 1a and 2a has a hardness of Hv680 or more, and the amount of retained austenite in the surface layer part is 9 volumes. %.

次に、これらに研削等の仕上げ加工を施して、各軌道面１ａ，２ａの表面粗さ（Ｒａ）を、ころ３の転動面３ａの表面粗さ（Ｒａ）よりも大きな０．１５μｍとなるように調整した。
このようにして得られた内輪１及び外輪２と、ころ３とを用いて、円錐ころ軸受を組み立てた。そして、この円錐ころ軸受を、表面損傷が生じ易い異物混入潤滑下で使用することを想定した以下の条件で運転させることにより、円錐ころ軸受の寿命試験を行った。 Next, finish processing such as grinding is performed on these, and the surface roughness (Ra) of each raceway surface 1a, 2a is 0.15 μm, which is larger than the surface roughness (Ra) of the rolling surface 3a of the roller 3. It adjusted so that it might become.
A tapered roller bearing was assembled using the inner ring 1 and the outer ring 2 and the roller 3 obtained in this manner. A life test of the tapered roller bearing was performed by operating the tapered roller bearing under the following conditions assuming that the tapered roller bearing is used under the contamination with foreign matters that are likely to cause surface damage.

この寿命試験は、内輪１、外輪２、及びころ３のいずれかの転がり面（軌道面１ａ，２ａや転動面３ａ）に剥離（フレーキング）が生じるまで内輪１を回転させることで行い、寿命試験開始から剥離が生じるまでの回転時間を寿命とした。また、この寿命試験は、各サンプルにおいてそれぞれ３０回行った。この結果は、各サンプル毎にワイブル分布関数に基づいてＬ₁₀寿命を算出し、Ｎｏ．１７のＬ₁₀寿命を１とした時の比として、表１に併せて示した。また、表１には、この寿命試験の結果、ころ３に剥離が生じた割合を併せて示した。
〔寿命試験条件〕
荷重比（Ｐ／Ｃｒ）：０．４６
回転速度：４５００ｍｉｎ^-1
潤滑油：♯６８タービン油
異物：（組成）Ｆｅ₃Ｃ
（硬さ）ＨＶ８７０
（粒径）７４〜１４７μｍ
（混入量）潤滑油中に３００ｐｐｍとなるように混入 This life test is performed by rotating the inner ring 1 until peeling (flaking) occurs on any of the rolling surfaces (the raceway surfaces 1a, 2a and the rolling surface 3a) of the inner ring 1, the outer ring 2, and the roller 3, The rotation time from the start of the life test to the occurrence of peeling was defined as the life. In addition, this life test was performed 30 times for each sample. This result is obtained by calculating the L ₁₀ life for each sample based on the Weibull distribution function. 17 of L ₁₀ life as a ratio when a 1, also shown in Table 1. Table 1 also shows the rate at which the roller 3 peeled as a result of this life test.
[Life test conditions]
Load ratio (P / Cr): 0.46
Rotational speed: 4500 min ^-1
Lubricating oil: ♯68 turbine oil foreign matter :( composition) Fe ₃ C
(Hardness) HV870
(Particle size) 74-147 μm
(Mixed amount) Mixed in the lubricating oil to 300ppm

表１に示すように、Ｎｏ．１，Ｎｏ．１３〜Ｎｏ．１６の円錐ころ軸受では、ころ３の転動面３ａをなす表層部の残留オーステナイト量が少なくなる程、ころ３の剥離率が増加し、寿命が長くなっていることが分かる。
この理由としては、本実施形態の内輪１及び外輪２ところ３との組合せの場合、ころ３の転がり疲れ寿命が内輪１及び外輪２の転がり疲れ寿命よりも長いため、円錐ころ軸受の寿命は内輪１及び外輪２の転がり疲れ寿命に影響を受けるからであると考えられる。 As shown in Table 1, no. 1, No. 1 13-No. In the 16 tapered roller bearings, it can be seen that as the amount of retained austenite in the surface layer portion forming the rolling surface 3a of the roller 3 decreases, the peeling rate of the roller 3 increases and the life becomes longer.
The reason for this is that, in the case of the combination of the inner ring 1 and the outer ring 2 and 3 in this embodiment, the rolling fatigue life of the roller 3 is longer than the rolling fatigue life of the inner ring 1 and outer ring 2, and therefore the life of the tapered roller bearing is This is considered to be because the rolling fatigue life of 1 and the outer ring 2 is affected.

また、表１に示すように、Ｎｏ．１〜Ｎｏ．９の円錐ころ軸受では、ころ３の転動面３ａをなす表層部のＮ含有率が多くなる程、寿命が長くなる傾向が見られた。
さらに、Ｎｏ．１０〜Ｎｏ．１２の円錐ころ軸受では、ころ３の転動面３ａにピーニング処理を施すことにより、同一鋼種を用いて作製され、且つ、同一のＮ含有率及びＮ＋Ｃ含有率としたＮｏ．２〜Ｎｏ．４の円錐ころ軸受よりも寿命が長くなっていることが分かる。 As shown in Table 1, No. 1-No. In the tapered roller bearing of No. 9, there was a tendency that the longer the N content in the surface layer portion forming the rolling surface 3a of the roller 3, the longer the life.
Furthermore, no. 10-No. In the 12 tapered roller bearings, the rolling surface 3a of the roller 3 is peened, so that it is manufactured using the same steel type and has the same N content and N + C content. 2-No. It can be seen that the life is longer than that of the No. 4 tapered roller bearing.

以上の結果から、内輪１及び外輪２を本発明構成のＳＵＪ２からなる素材で構成し、且つ、軌道面１ａ，２ａをなす表層部を本発明構成外（Ｎ含有率：０％，Ｎ＋Ｃ含有率：１．０％，残留オーステナイト量：９体積％，硬さ：Ｈｖ６８０）とした場合においては、ころ３の転動面３ａをなす表層部の残留オーステナイト量やＮ含有率を多くすることにより、表面損傷が生じ易い異物混入潤滑下で使用した円錐ころ軸受の寿命が長くなる傾向があることが分かった。 From the above results, the inner ring 1 and the outer ring 2 are made of a material made of SUJ2 of the present invention, and the surface layer portion forming the raceway surfaces 1a and 2a is outside the structure of the present invention (N content: 0%, N + C content) : 1.0%, amount of retained austenite: 9% by volume, hardness: Hv680), by increasing the amount of retained austenite and N content in the surface layer portion forming the rolling surface 3a of the roller 3, It was found that the life of tapered roller bearings used under lubrication with foreign matter that is prone to surface damage tends to be longer.

＜第２実施形態＞
上述した円錐ころ軸受の内輪１及び外輪２を、以下に示す手順で作製した。
まず、表２に示す各構成の鋼からなる素材を内輪１及び外輪２の各形状に加工した後、表２に示す各方法で熱処理を施した。
なお、表２に「浸炭窒化焼入れ→焼戻し」で示す熱処理は、以下に示す条件で行った。まず、混合ガス（Ｒｘガス＋プロパンガス＋アンモニアガス）の雰囲気下で、アンモニアガスの流量を混合ガス全体の２〜９％とした条件下において、８３０〜８６０℃で５〜１０時間保持することにより浸炭窒化を行った後、油焼入れを行った。次に、１５０〜２００℃で２時間保持することにより焼戻しを行った。 Second Embodiment
The inner ring 1 and the outer ring 2 of the tapered roller bearing described above were produced by the following procedure.
First, after processing the material which consists of steel of each structure shown in Table 2 into each shape of the inner ring | wheel 1 and the outer ring | wheel 2, it heat-processed by each method shown in Table 2. FIG.
In addition, the heat treatment shown in Table 2 as “carbonitriding quenching → tempering” was performed under the following conditions. First, in an atmosphere of a mixed gas (Rx gas + propane gas + ammonia gas), hold at 830 to 860 ° C. for 5 to 10 hours under the condition that the flow rate of ammonia gas is 2 to 9% of the total mixed gas. Then, carbonitriding was performed, followed by oil quenching. Next, tempering was performed by holding at 150 to 200 ° C. for 2 hours.

また、表２に「浸炭焼入れ→焼戻し」で示す熱処理は、以下に示す条件で行った。まず、混合ガス（Ｒｘガス＋プロパンガス）の雰囲気下において、８４０〜８８０℃で５〜１０時間保持することにより浸炭を行った後、油焼入れを行った。次に、１５０〜２００℃で２時間保持することにより焼戻しを行った。
次に、これらに研削等の仕上げ加工を施して、各軌道面１ａ，２ａの表面粗さ（Ｒａ）を、０．１５μｍに調整した。また、内輪１及び外輪２の各軸方向端面における研磨取り代は、それぞれ１５０μｍずつとした。 Further, the heat treatment shown in Table 2 as “carburizing quenching → tempering” was performed under the following conditions. First, in a mixed gas (Rx gas + propane gas) atmosphere, carburization was performed by holding at 840 to 880 ° C. for 5 to 10 hours, followed by oil quenching. Next, tempering was performed by holding at 150 to 200 ° C. for 2 hours.
Next, these were subjected to finish processing such as grinding, and the surface roughness (Ra) of each of the raceway surfaces 1a and 2a was adjusted to 0.15 μm. Further, the polishing allowance at each axial end surface of the inner ring 1 and the outer ring 2 was set to 150 μm.

そして、得られた内輪１及び外輪２のうち破壊検査用のサンプルを用いて、上述と同様の方法で軌道面１ａ，２ａをなす表層部（表面から１μｍの深さまでの部分）のＮ含有率（質量比）及びＣ含有率（質量比）と、前記表層部の残留オーステナイト量（体積比）と、前記表層部の硬さ（Ｈｖ）と、をそれぞれ測定した。これらの結果は、「Ｎ含有率」、「Ｎ＋Ｃ含有率」、「γ_R」、及び「硬さ」として、表２に併せて示した。
このようにして得られた内輪１及び外輪２と、第１実施形態で作製した各構成のころ３と、を表２に示すように組み合わせて、円錐ころ軸受を組み立てた。
そして、この円錐ころ軸受を上述と同様の条件で運転させることにより、円錐ころ軸受の寿命試験を行った。この結果は、表１に示すＮｏ．１７のＬ₁₀寿命を１とした時の比として、表２に併せて示した。 Then, using the sample for destructive inspection among the obtained inner ring 1 and outer ring 2, the N content of the surface layer part (the part from the surface to a depth of 1 μm) forming the raceway surfaces 1a and 2a by the same method as described above. (Mass ratio) and C content (mass ratio), the amount of retained austenite (volume ratio) of the surface layer portion, and the hardness (Hv) of the surface layer portion were measured. These results are shown together in Table 2 as “N content”, “N + C content”, “γ _R ”, and “hardness”.
The inner ring 1 and the outer ring 2 thus obtained and the rollers 3 having the respective configurations produced in the first embodiment were combined as shown in Table 2 to assemble a tapered roller bearing.
And the life test of the tapered roller bearing was done by operating this tapered roller bearing on the conditions similar to the above-mentioned. This result is shown in No. 1 shown in Table 1. 17 of L ₁₀ life as a ratio when a 1, also shown in Table 2.

表２に示すように、本発明構成の内輪１及び外輪２と、本発明構のころ３とを用いたＮｏ．２１〜Ｎｏ．３３の円錐ころ軸受では、本発明構成の内輪１及び外輪２と、本発明構成外のころ３とを用いたＮｏ．３４〜Ｎｏ．３８の円錐ころ軸受ころ３よりも、寿命が長くなっていることが分かる。
このうち、内輪１及び外輪２に対して浸炭窒化処理を含む熱処理を施したＮｏ．２１〜Ｎｏ．２９の円錐ころ軸受では、内輪１及び外輪２に対して浸炭処理を含む熱処理を施したＮｏ．３０〜Ｎｏ．３２の円錐ころ軸受よりも、寿命が長くなっていることが分かる。 As shown in Table 2, No. 1 using the inner ring 1 and outer ring 2 of the present invention structure and the roller 3 of the present invention structure. 21-No. In the No. 33 tapered roller bearing, No. 3 using the inner ring 1 and the outer ring 2 having the configuration of the present invention and the roller 3 having the configuration other than the present invention. 34-No. It can be seen that the lifetime is longer than that of the 38 tapered roller bearing rollers 3.
Among these, No. 1 was subjected to heat treatment including carbonitriding on the inner ring 1 and the outer ring 2. 21-No. In the tapered roller bearing of No. 29, the inner ring 1 and the outer ring 2 were subjected to heat treatment including carburization No. 30-No. It can be seen that the lifetime is longer than that of the 32 tapered roller bearing.

また、Ｎｏ．３３の円錐ころ軸受では、内輪及び外輪２の軌道面１ａ，２ａをなす表層部のＮ含有率が、ころ３の転動面３ａをなす表層部のＮ含有率よりも多くなっているため、ころ３の剥離率が大幅に増大していることが分かる。この結果から、ころ３の摩擦低減効果を十分に得るとともに、研削コストを低減させるためには、ころ３の転動面３ａをなす表層部のＮ含有率を、内輪１及び外輪２の軌道面１ａ，２ａをなす表層部のＮ含有率よりも多くすればよいことが分かる。 No. In the 33 tapered roller bearing, the N content of the surface layer portion forming the raceway surfaces 1a and 2a of the inner ring and the outer ring 2 is larger than the N content rate of the surface layer portion forming the rolling surface 3a of the roller 3, It can be seen that the peeling rate of the roller 3 is greatly increased. From this result, in order to sufficiently obtain the friction reducing effect of the roller 3 and to reduce the grinding cost, the N content of the surface layer portion forming the rolling surface 3a of the roller 3 is set to the raceway surfaces of the inner ring 1 and the outer ring 2. It turns out that it should just increase more than N content rate of the surface layer part which makes 1a and 2a.

一方、表２に示すように、Ｎｏ．３４〜Ｎｏ．３７の円錐ころ軸受では、表１に示す結果とは異なり、ころ３の転動面３ａをなす表層部の残留オーステナイト量が少なくなる程、ころ３の剥離率が大幅に増加して、寿命が短くなっていることが分かる。
この理由としては、本実施形態の内輪１及び外輪２ところ３との組合せの場合、内輪１及び外輪２の転がり疲れ寿命がころ３よりも長いため、円錐ころ軸受の寿命が、ころ３の転がり疲れ寿命に影響を受けるからであると考えられる。 On the other hand, as shown in Table 2, no. 34-No. In the tapered roller bearing of 37, unlike the results shown in Table 1, as the amount of retained austenite in the surface layer portion forming the rolling surface 3a of the roller 3 decreases, the peeling rate of the roller 3 increases significantly, and the life is shortened. You can see that it is getting shorter.
The reason for this is that in the case of the combination of the inner ring 1 and the outer ring 2 and 3 of the present embodiment, the rolling fatigue life of the inner ring 1 and the outer ring 2 is longer than that of the roller 3, so that the life of the tapered roller bearing is reduced. This is thought to be due to the influence of fatigue life.

また、Ｎｏ．３４の円錐ころ軸受では、ころ３の剥離率が１０％であるにも係わらず、寿命が短くなっていることが分かる。この結果から、ころ３の転動面３ａをなす表層部の残留オーステナイト量が多過ぎると、ころ３の経時変化が増加して、内輪１及び外輪２との間の摩擦低減効果が十分に得られないことが分かる。
さらに、Ｎｏ．３７の円錐ころ軸受では、ころ３の転動面３ａをなす表層部のＮ含有率が本発明範囲よりも少ないため、寿命が短くなっていることが分かる。 No. It can be seen that in the 34 tapered roller bearing, the life is shortened although the peeling rate of the roller 3 is 10%. From this result, if the amount of retained austenite in the surface layer portion forming the rolling surface 3a of the roller 3 is too large, the change with time of the roller 3 increases, and a sufficient friction reducing effect between the inner ring 1 and the outer ring 2 is obtained. I can't understand.
Furthermore, no. In the 37 tapered roller bearing, the N content of the surface layer portion forming the rolling surface 3a of the roller 3 is less than the range of the present invention, so that the life is shortened.

これらの結果から、内輪１及び外輪２を本発明構成の鋼からなる素材で構成し、且つ、軌道面１ａ，２ａをなす表層部を本発明の構成（Ｎ含有率：０．１０〜０．５０％，Ｎ＋Ｃ含有率：０．７〜４．０％，残留オーステナイト量：２０〜４０％，硬さ：Ｈｖ６５０以上）とした場合において、ころ３の転動面３ａをなす表層部のＮ含有率及び残留オーステナイト量を特定しないと、表面損傷が生じ易い異物混入潤滑下で使用した円錐ころ軸受の寿命を長くできないことが分かった。 From these results, the inner ring 1 and the outer ring 2 are made of a material made of steel of the present invention, and the surface layer portion forming the raceway surfaces 1a, 2a is the structure of the present invention (N content: 0.10-0. 50%, N + C content: 0.7 to 4.0%, residual austenite amount: 20 to 40%, hardness: Hv 650 or more) N content in the surface layer portion forming the rolling surface 3a of the roller 3 It has been found that unless the rate and the amount of retained austenite are specified, the life of the tapered roller bearing used under the contamination with foreign matters that are liable to cause surface damage cannot be extended.

図２は、表２に示す結果に基づいて、ころ３の転動面３ａをなす表層部の残留オーステナイト量と、ころ３の転がり疲れ寿命及びころ３と組み合わせる本発明構成の内輪１及び外輪２の転がり疲れ寿命との関係を、模式的に示す図である。
図２に示す結果より、内輪１及び外輪２の転がり疲れ寿命と、ころ３の転がり疲れ寿命との相互バランスを考慮して、軌道面１ａ，２ａ及び転動面３ａをなす表層部の残留オーステナイト量を本発明範囲に特定することにより、表面損傷の生じ易い異物混入潤滑下で使用した円錐ころ軸受の寿命を長くできることが分かる。 2 shows, based on the results shown in Table 2, the amount of retained austenite in the surface layer portion forming the rolling surface 3 a of the roller 3, the rolling fatigue life of the roller 3, and the inner ring 1 and outer ring 2 of the present invention combined with the roller 3. It is a figure which shows typically the relationship with rolling fatigue life of.
From the results shown in FIG. 2, considering the mutual balance between the rolling fatigue life of the inner ring 1 and the outer ring 2 and the rolling fatigue life of the roller 3, the retained austenite of the surface layer portion forming the raceway surfaces 1a, 2a and the rolling surface 3a. By specifying the amount within the range of the present invention, it can be seen that the life of the tapered roller bearing used under the contamination with foreign matters that are likely to cause surface damage can be extended.

＜第３実施形態＞
上述した表２に示すＮｏ．２３の構成で作製し、その転動面３ａの表面粗さ（Ｒａ）を０．１０μｍ，０．２０μｍ，０．２５μｍにそれぞれ調整したころ３を用意した。
そして、これらのころ３と、上述した表２に示すＮｏ．２３の内輪１及び外輪２（各軌道面１ａ，２ａの表面粗さが０．１５μｍ）とを用いて、円錐ころ軸受を組み立てた。そして、この円錐ころ軸受を上述と同様の条件で運転させて、円錐ころ軸受の寿命試験を行った。 <Third Embodiment>
No. shown in Table 2 above. The roller 3 was prepared with the configuration of No. 23, and the surface roughness (Ra) of the rolling surface 3a was adjusted to 0.10 μm, 0.20 μm, and 0.25 μm, respectively.
And these roller 3 and No. shown in Table 2 mentioned above. A tapered roller bearing was assembled using 23 inner rings 1 and outer rings 2 (the surface roughness of each raceway surface 1a, 2a was 0.15 μm). The tapered roller bearing was operated under the same conditions as described above, and a life test of the tapered roller bearing was performed.

この結果、ころ３の転動面３ａの表面粗さ（Ｒａ）を０．１０〜０．２５μｍにそれぞれ調整したころ３を用いた円錐ころ軸受では、ころ３の転動面３ａの表面粗さ（Ｒａ）を０．０６μｍとした表２に示すＮｏ．２３の場合（Ｎｏ．１７の７．５倍の寿命）よりも、寿命が短くなっていた。具体的には、ころ３の転動面３ａの表面粗さ（Ｒａ）を０．１０μｍとした場合にはＮｏ．１７の６．１倍の寿命が得られ、同様に、０．２０μｍとした場合にはＮｏ．１７の３．２の寿命が得られ、０．２５μｍとした場合にはＮｏ．１７の２．１倍の寿命が得られた。 As a result, in the tapered roller bearing using the roller 3 in which the surface roughness (Ra) of the rolling surface 3 a of the roller 3 is adjusted to 0.10 to 0.25 μm, the surface roughness of the rolling surface 3 a of the roller 3. No. shown in Table 2 where (Ra) is 0.06 μm. The service life was shorter than the case of 23 (7.5 times the life of No. 17). Specifically, when the surface roughness (Ra) of the rolling contact surface 3a of the roller 3 is 0.10 μm, No. A life of 6.1 times as long as that of No. 17 was obtained. No. 17 3.2 was obtained. A lifetime 2.1 times that of 17 was obtained.

以上の結果より、ころ３の転動面３ａの表面粗さ（Ｒａ）が、内輪１及び外輪２の軌道面１ａ，２ａの表面粗さ（Ｒａ）よりも大きくなると、円錐ころ軸受の寿命が大幅に短くなることが分かった。よって、円錐ころ軸受の寿命を長くするためには、ころ３の転動面３ａの表面粗さ（Ｒａ）を、内輪１及び外輪２の軌道面１ａ，２ａの表面粗さ（Ｒａ）よりも小さくする必要があることが分かった。 From the above results, when the surface roughness (Ra) of the rolling surface 3a of the roller 3 is larger than the surface roughness (Ra) of the raceway surfaces 1a and 2a of the inner ring 1 and the outer ring 2, the life of the tapered roller bearing is increased. It turned out to be significantly shorter. Therefore, in order to prolong the life of the tapered roller bearing, the surface roughness (Ra) of the rolling surface 3a of the roller 3 is set to be larger than the surface roughness (Ra) of the raceway surfaces 1a and 2a of the inner ring 1 and the outer ring 2. I found it necessary to make it smaller.

本発明の転がり軸受の一例として円錐ころ軸受を示す断面図である。It is sectional drawing which shows a tapered roller bearing as an example of the rolling bearing of this invention. ころの転動面をなす表層部の残留オーステナイト量と、ころの転がり疲れ寿命及び内外輪の転がり疲れ寿命と、の関係を示すグラフである。It is a graph which shows the relationship between the amount of retained austenite of the surface layer part which makes the rolling surface of a roller, the rolling fatigue life of a roller, and the rolling fatigue life of an inner and outer ring.

Explanation of symbols

１内輪
１ａ内輪軌道面
２外輪
２ａ外輪軌道面
３ころ（転動体）
３ａ転動面
１０鍔部 DESCRIPTION OF SYMBOLS 1 Inner ring 1a Inner ring raceway surface 2 Outer ring 2a Outer ring raceway surface 3 Roller (rolling element)
3a Rolling surface
10 Buttocks

Claims

A first member and a second member having raceways facing each other, and a rolling element which is disposed between the first member and the second member so as to be freely rollable and has a rolling surface with respect to the raceway. A rolling support device in which one of the first member and the second member moves relative to the other by rolling the rolling element;
The first member and the second member have a C content of 0.2% by mass to 1.2% by mass, an Si content of 0.15% by mass to 2.0% by mass, and a Mn content of 0. .2% by mass to 2.0% by mass, Cr content of 0.5% by mass to 2.0% by mass, Mo content of 2.0% by mass or less, and V content of 2.0% by mass or less The O content is 12 ppm or less, and after the material made of steel with the balance being Fe and inevitable impurities is processed into a predetermined shape, the heat treatment including carburizing or carbonitriding is performed,
The surface layer portion forming the raceway surface has a total content of N and C of 0.7% to 4.0% by mass, a residual austenite amount of 20% to 40% by volume, and a hardness of Hv650 or more. And
The rolling element has a C content of 0.2% by mass to 1.2% by mass, an Si content of 0.4% by mass to 2.0% by mass, and a Mn content of 0.2% by mass to 2%. 0.0% by mass or less, Cr content of 0.5% by mass or more and 2.0% by mass or less, O content of 12ppm or less, and after processing a material made of steel with the balance being Fe and inevitable impurities into a predetermined shape, Obtained by heat treatment including carbonitriding,
The surface layer portion forming the rolling surface has an N content of 0.20% by mass or more and 2.00% by mass or less, and a total content of N and C is 0.8% by mass or more and 4.0% by mass or less. The amount of retained austenite is 20 vol% or more and 24 vol% or less, and the hardness is Hv700 or more,
The rolling support device characterized in that a surface roughness (Ra) of the rolling surface is smaller than a surface roughness (Ra) of the raceway surface.

The rolling element is obtained by processing a material made of the steel into a predetermined shape and then performing a carbonitriding process, a quenching process, a tempering process, and a peening process in this order. The rolling support device according to claim 1.

In the case where the first member and the second member are obtained by performing a heat treatment including a carbonitriding treatment after processing the material made of the steel into a predetermined shape,
The rolling support device according to claim 1 or 2, wherein the N content of the surface layer portion forming the rolling surface is greater than the N content of the surface layer portion forming the raceway surface.