JP2006045591A - Tapered roller bearing - Google Patents

Tapered roller bearing Download PDF

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JP2006045591A
JP2006045591A JP2004224628A JP2004224628A JP2006045591A JP 2006045591 A JP2006045591 A JP 2006045591A JP 2004224628 A JP2004224628 A JP 2004224628A JP 2004224628 A JP2004224628 A JP 2004224628A JP 2006045591 A JP2006045591 A JP 2006045591A
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roller
diameter side
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Kazuo Sekino
和雄 関野
Susumu Tanaka
進 田中
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NSK Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/34—Rollers; Needles
    • F16C33/36—Rollers; Needles with bearing-surfaces other than cylindrical, e.g. tapered; with grooves in the bearing surfaces
    • F16C33/366—Tapered rollers, i.e. rollers generally shaped as truncated cones
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/36—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers
    • F16C19/364—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers with tapered rollers, i.e. rollers having essentially the shape of a truncated cone
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2202/00—Solid materials defined by their properties
    • F16C2202/02—Mechanical properties
    • F16C2202/04—Hardness

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Heat Treatment Of Articles (AREA)
  • Rolling Contact Bearings (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide, at a low cost, a tapered roller bearing having a long service life even if used under debris contaminated lubrication. <P>SOLUTION: A roller 3 of the tapered roller bearing is produced by working a material composed of steel having a composition containing, by mass, 0.3 to 1.2% C, 0.4 to 2.0% Si, 0.2 to 2.0% Mn and 0.5 to 2.0% Cr into a prescribed shape and then applying carbonitriding treatment, quenching treatment and tempering treatment. With respect to the surface layer part constituting the rolling surface of the roller 3 and the sliding contact surface with a large diameter side flange part 10A: N content is controlled to 0.20 to 2.00 mass%; the total content of C and N is controlled to 1.20 to 3.00 mass%; hardness is controlled to Hv 750 to 900; and the amount of retained austenite is controlled to 5 to 20 vol.%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、円すいころ軸受に関する。   The present invention relates to a tapered roller bearing.

一般に、転がり軸受の転動体および内外輪としては、高炭素クロム軸受鋼二種（ＳＵＪ２）等の軸受鋼鋼材に焼入れおよび焼戻し処理を施して、表面硬さをＨＲＣ５８〜６２（Ｈｖ６５０〜７４０）程度に硬化させることにより、必要な転がり疲れ寿命が付与されたものが用いられている。
このような転がり軸受の定格疲れ寿命は、玉軸受では下記（１）式で算出され、ころ軸受では下記（２）式で算出される。
Ｌ1 ＝（Ｃ／Ｐ）3 ・・・（１）
Ｌ2 ＝（Ｃ／Ｐ）10/3 ・・・（２） Generally, as rolling elements and inner and outer rings of a rolling bearing, bearing steel materials such as high-carbon chromium bearing steel type 2 (SUJ2) are subjected to quenching and tempering treatment, and the surface hardness is about HRC58 to 62 (Hv650 to 740). A material having a necessary rolling fatigue life is obtained by being cured.
The rated fatigue life of such a rolling bearing is calculated by the following formula (1) for ball bearings, and is calculated by the following formula (2) for roller bearings.
L 1 = (C / P) 3 (1)
L 2 = (C / P) 10/3 (2)

但し、（１），（２）式中、Ｌ1 は玉軸受の定格疲れ寿命、Ｌ2 はころ軸受の定格疲れ寿命、Ｃは基本動定格荷重、Ｐは軸受荷重を示す。
近年、製鋼技術の飛躍的な進歩に伴い、鋼の清浄度が格段に向上したことによって、清浄な油浴潤滑下では、上記定格疲れ寿命を満足せずに早期に転がり疲れによる剥離が生じることはほとんどなくなってきている。しかしながら、自動車、農業機械、建設機械、鉄鋼機械のトランスミッション（変速機）、エンジン、および減速機等で使用される転がり軸受は、潤滑油中に金属の切粉、削り屑、バリ、および摩耗粉が混入する潤滑環境下（以下、「異物混入潤滑下」と記す。）で使用される場合が多い。このため、これらの用途の転がり軸受では、上述した定格疲れ寿命に達する前に表面起点型のフレーキング（以下、「表面起点型剥離」と記す。）が生じる場合がある。 In the equations (1) and (2), L 1 represents the rated fatigue life of the ball bearing, L 2 represents the rated fatigue life of the roller bearing, C represents the basic dynamic load rating, and P represents the bearing load.
In recent years, with the dramatic progress of steelmaking technology, the cleanliness of steel has been greatly improved, and under the clean oil bath lubrication, peeling due to rolling fatigue occurs early without satisfying the above rated fatigue life. Is almost gone. However, rolling bearings used in automobiles, agricultural machinery, construction machinery, steel machinery transmissions (transmissions), engines, reduction gears, etc. are made of metal chips, shavings, burrs, and wear powder in lubricating oil. It is often used in a lubrication environment (hereinafter referred to as “under foreign matter lubrication”). For this reason, in rolling bearings for these applications, surface-initiated flaking (hereinafter referred to as “surface-initiated delamination”) may occur before the above-described rated fatigue life is reached.

このような表面起点型剥離を抑制するために、特許文献１では、軌道輪および転動体の少なくとも一つについて、Ｃ含有率が０．２〜１．０質量％で、Ｃｒ、Ｍｏ、およびＶの合計含有率が１質量％以上の鋼からなる素材を所定形状に加工した後、浸炭窒化・硬化熱処理を施すことにより、その表面層に存在する炭窒化物の単位面積当たりの面積率を１０％以上とし、前記表面層に存在する最大炭窒化物径を３μｍ以下とし、前記表面層の残留オーステナイト量を２５〜４５体積％とし、前記表面層の表面硬さをＨｖ７５０以上とすることが提案されている。   In order to suppress such surface-origin type separation, Patent Document 1 discloses that at least one of the race ring and the rolling element has a C content of 0.2 to 1.0 mass%, Cr, Mo, and V After processing a material made of steel having a total content of 1% by mass or more into a predetermined shape, carbonitriding / hardening heat treatment is performed, so that the area ratio per unit area of carbonitride existing in the surface layer is 10 % Or more, the maximum carbonitride diameter existing in the surface layer is 3 μm or less, the amount of retained austenite of the surface layer is 25 to 45% by volume, and the surface hardness of the surface layer is Hv 750 or more. Has been.

また、特許文献２では、軌道輪および転動体の少なくとも一つについて、炭化物形成元素を含有し、転がり面をなす表面層の残留オーステナイト量（γR ）を２０〜４５体積％とし、平均粒径０．５〜１．５μｍの微細炭化物または炭窒化物の分散強化により、前記表面層の表面硬さ（Ｈｖ）を、前記残留オーステナイト量に対して下記（３）式の範囲内の合金鋼から構成することが提案されている。
−４．７×（γR ）＋９２０≦（Ｈｖ）≦−４．７×（γR ）＋１０２０・・・（３） Further, in Patent Document 2, at least one of the raceway and the rolling element contains a carbide-forming element, the amount of retained austenite (γ R ) of the surface layer forming the rolling surface is 20 to 45% by volume, and the average particle diameter By the dispersion strengthening of 0.5 to 1.5 μm fine carbide or carbonitride, the surface hardness (Hv) of the surface layer is reduced from the alloy steel within the range of the following formula (3) with respect to the amount of retained austenite. It has been proposed to configure.
−4.7 × (γ R ) + 920 ≦ (Hv) ≦ −4.7 × (γ R ) +1020 (3)

さらに、非特許文献１では、潤滑油中の異物による表面損傷とこの表面損傷を起点とするフレーキングの発生メカニズムや、残留オーステナイトによる圧痕縁への応力集中低減効果と寿命延長効果との関係について報告されている。
ところで、転がり軸受の一つである円すいころ軸受は、外周面に円すい凸面状の内輪軌道面を有する内輪と、内周面に円すい凹面状の外輪軌道面を有する外輪と、これらの両軌道面間に転動自在に配設される円すい形状の複数のころと、を備えている。そして、内輪の外周面端部には、ころの軸方向端面のうち大径側端面と対向する内側面を有する大径側鍔部と、小径側端面と対向する内側面を有する小径側鍔部と、が形成されている。 Furthermore, in Non-Patent Document 1, the relationship between the surface damage caused by foreign matter in the lubricating oil and the flaking occurrence mechanism starting from this surface damage, and the effect of reducing stress concentration on the indentation edge due to retained austenite and the life extension effect It has been reported.
By the way, a tapered roller bearing which is one of the rolling bearings includes an inner ring having a conical convex inner ring raceway surface on the outer peripheral surface, an outer ring having a conical concave outer ring raceway surface on the inner peripheral surface, and both of these raceway surfaces. And a plurality of conical rollers disposed so as to be freely rollable therebetween. And the outer peripheral surface end of the inner ring has a large-diameter side flange having an inner surface facing the large-diameter side end surface of the axial end surfaces of the rollers, and a small-diameter side flange having an inner surface facing the small-diameter side end surface And are formed.

この円すいころ軸受では、内外輪の相対回転に伴ってころが転動することにより、ころの大径側端面と大径側鍔部の内側面とが摺接し、この摺接面でスラスト荷重を支持するようになっている。よって、円すいころ軸受は、玉軸受と比較して高剛性で高負荷容量ではあるが、トルクが大きくなるため、例えば高速回転域等の苛酷な条件下で使用される場合には、前記摺接面に焼付きが生じ易いという問題がある。   In this tapered roller bearing, the roller rolls as the inner and outer rings rotate relative to each other, so that the large-diameter side end surface of the roller and the inner side surface of the large-diameter side collar portion are in sliding contact with each other, and a thrust load is applied to the sliding contact surface. It comes to support. Therefore, the tapered roller bearing has higher rigidity and higher load capacity than the ball bearing, but the torque is increased. Therefore, when the tapered roller bearing is used under severe conditions such as a high-speed rotation range, the sliding contact is performed. There is a problem that seizure is likely to occur on the surface.

特許文献３には、内輪、外輪、およびころの少なくとも一つについて、Ｃ含有率が０．２〜０．５質量％、Ｍｎ含有率が０．５〜１．２質量％、Ｃｒ含有率が０．５〜２．０質量％である鋼からなる素材を所定形状に加工した後、浸炭または浸炭窒化処理と、焼入れ処理と、焼戻し処理とを施すことにより、軌道面および／または転動面の表層部のＣ含有率を０．７〜１．２質量％とし、前記表層部の残留オーステナイト量を２０．０〜４０．０体積％とし、前記表層部の硬さをＨｖ７００以上とすることが記載されている。
特開平５−７８８１４号公報 特開平４−２６７５２号公報 特開２００２−２１３４６１号公報 ”Ｔｈｅ Ｄｅｖｅｌｏｐｍｅｎｔ ｏｆ Ｂｅａｒｉｎｇ Ｓｔｅｅｌｓ ｆｏｒ Ｌｏｎｇ Ｌｉｆｅ Ｒｏｌｌｉｎｇ Ｂｅａｒｉｎｇｓ Ｕｎｄｅｒ Ｃｌｅａｎ Ｌｕｎｂｒｉｃａｔｉｏｎ”，ＡＳＴＥＭ−ＳＴＰ１１９５（１９９３），ｐ１９９〜２１０ In Patent Document 3, C content is 0.2 to 0.5 mass%, Mn content is 0.5 to 1.2 mass%, and Cr content is about at least one of the inner ring, the outer ring, and the roller. After processing a material made of steel of 0.5 to 2.0% by mass into a predetermined shape, carburizing or carbonitriding, quenching, and tempering are performed, so that the raceway surface and / or rolling surface The C content of the surface layer portion is 0.7 to 1.2% by mass, the amount of retained austenite of the surface layer portion is 20.0 to 40.0% by volume, and the hardness of the surface layer portion is Hv 700 or more. Is described.
Japanese Patent Laid-Open No. 5-78814 JP-A-4-26752 JP 2002-213461 A "The Development of Bearing Steels for Long Life Rolling Bears Under Clean Lubrication", ASTEM-STP1195 (1993), p199-210.

ところで、近年、省エネルギー化を目的として、輸送機器や構造物の軽量化や鉄鋼材料のさらなる高強度化が求められてきている。また、装置の高性能化や低トルク化に伴って、潤滑環境が苛酷になってきている。さらに、装置の低コスト化も求められている。
しかしながら、上述した特許文献１および特許文献２に記載の軸受には、異物混入潤滑下での表面起点型剥離を抑制するという点でさらなる改善の余地がある。 By the way, in recent years, for the purpose of energy saving, it has been required to reduce the weight of transportation equipment and structures and to further increase the strength of steel materials. In addition, the lubrication environment has become severe as the performance of the apparatus and the torque are reduced. Furthermore, cost reduction of the apparatus is also demanded.
However, the bearings described in Patent Document 1 and Patent Document 2 described above have room for further improvement in terms of suppressing surface-origin type separation under the contamination with foreign matter.

また、上述した特許文献３に記載の軸受には、ころと大径側鍔部との摺接面での焼付きを抑制するという点でさらなる改善の余地がある。
さらに、上述した特許文献３に記載の軸受を異物混入潤滑下で使用する場合には、ころだけでなく軌道輪も強化しないと、転がり面の表面起点型剥離を抑制することは難しい。よって、この特許文献３に記載の軸受には、低コストで寿命を長くするという点でもさらなる改善の余地がある。
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、特に、異物混入潤滑下で使用しても寿命の長い円すいころ軸受を低コストで提供することを課題としている。 Further, the bearing described in Patent Document 3 described above has room for further improvement in terms of suppressing seizure on the sliding contact surface between the roller and the large-diameter side flange.
Furthermore, when the bearing described in Patent Document 3 described above is used under foreign matter-mixed lubrication, it is difficult to suppress surface-origin separation of the rolling surface unless not only the rollers but also the races are reinforced. Therefore, the bearing described in Patent Document 3 has room for further improvement in terms of extending the life at low cost.
The present invention has been made to solve these problems. In particular, it is an object of the present invention to provide a tapered roller bearing having a long life even at a low cost even when used under a foreign matter mixed lubrication.

このような課題を解決するために、本発明は、内輪と、外輪と、前記内輪および外輪の間に転動自在に配設された円すい形状の複数のころと、を備え、前記内輪の外周面端部には、前記ころの軸方向端面のうち大径側端面と摺接する内側面を有する大径側鍔部が形成されている円すいころ軸受において、前記ころは、Ｃ含有率が０．３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、浸炭窒化処理と、焼入れ処理と、焼戻し処理とがこの順に施されて得られ、その転がり面および前記大径側鍔部との摺接面をなす表層部は、Ｎ含有率が０．２０質量％以上２．００質量％以下、ＣおよびＮの合計含有率が１．２０質量％以上３．００質量％以下、硬さがＨｖ７５０以上Ｈｖ９００以下、残留オーステナイト量が５体積％以上２０体積％以下となっていることを特徴とする円すいころ軸受を提供する。
なお、前記表層部とは、表面から所定深さ（例えば、ころの最大径の２％の深さ）までの範囲を指す。 In order to solve such a problem, the present invention includes an inner ring, an outer ring, and a plurality of conical rollers disposed so as to roll between the inner ring and the outer ring, and an outer periphery of the inner ring. In the tapered roller bearing in which a large diameter side flange having an inner surface that is in sliding contact with the large diameter side end surface of the axial end surface of the roller is formed at the surface end portion, the roller has a C content of 0. 3 mass% or more and 1.2 mass% or less, Si content is 0.4 mass% or more and 2.0 mass% or less, Mn content is 0.2 mass% or more and 2.0 mass% or less, and Cr content is 0. After processing a material composed of steel of 5 mass% or more and 2.0 mass% or less into a predetermined shape, carbonitriding treatment, quenching treatment, and tempering treatment are performed in this order, and the rolling surface and The surface layer portion that forms the sliding contact surface with the large-diameter side flange portion has an N content of 0.20% by mass or more. 0% by mass or less, the total content of C and N is 1.20% by mass or more and 3.00% by mass or less, the hardness is Hv 750 or more and Hv 900 or less, and the amount of retained austenite is 5% by volume or more and 20% by volume or less. A tapered roller bearing is provided.
The surface layer portion refers to a range from the surface to a predetermined depth (for example, a depth of 2% of the maximum diameter of the roller).

本発明の円すいころ軸受では、上述した特定の鋼からなる素材をころの形状に加工した後、以下に示す熱処理を施すことで、その転がり面および大径側鍔部との摺接面をなす表層部の残留オーステナイト量と、硬さと、Ｎ含有率およびＣ含有率とを特定した。これにより、円すいころ軸受のころとして必要な転がり疲れ寿命が得られるとともに、ころの転がり面に表面起点型剥離が生じ難くなり、且つ、ころの大径側鍔部との摺接面に焼付きが生じ難くなる。   In the tapered roller bearing of the present invention, after the above-mentioned material made of the specific steel is processed into a roller shape, the following heat treatment is performed to form a sliding contact surface with the rolling surface and the large-diameter side flange. The amount of retained austenite, hardness, N content and C content in the surface layer portion were specified. As a result, the rolling fatigue life required for the roller of the tapered roller bearing can be obtained, and the surface-initiated peeling is less likely to occur on the rolling surface of the roller, and the sliding contact surface with the large-diameter side flange portion of the roller is seized. Is less likely to occur.

以下、本発明の各数値限定の理由と、熱処理方法について説明する。
〔Ｃ含有率：０．３質量％以上１．２質量％以下〕
Ｃ（炭素）は、鋼に必要な強度と寿命を付与する作用を有する。Ｃ含有率が少な過ぎると、円すいころ軸受のころとして必要な強度が得られないだけでなく、浸炭窒化処理を行う際に、ころの転がり面および大径側鍔部との摺接面として必要な硬化層深さを得るための熱処理時間が長くなり、生産コストが増大する。このため、Ｃ含有率は０．３質量％以上、好ましくは０．６質量％以上とする。
一方、Ｃ含有率が多過ぎると、製鋼時に巨大な炭化物が生成されて、その後の焼入れ特性や転がり疲れ寿命に悪影響を及ぼすだけでなく、ヘッダー加工性が低下してコストの上昇を招く。よって、Ｃ含有率は１．２質量％以下とする。 Hereinafter, the reason for limiting each numerical value of the present invention and the heat treatment method will be described.
[C content: 0.3 mass% or more and 1.2 mass% or less]
C (carbon) has the effect | action which provides the intensity | strength and lifetime which are required for steel. If the C content is too small, not only the strength required for the roller of a tapered roller bearing will not be obtained, but also necessary for the rolling surface of the roller and the sliding contact surface with the large-diameter side flange when performing carbonitriding. The heat treatment time for obtaining a hardened layer depth becomes longer and the production cost increases. For this reason, C content rate is 0.3 mass% or more, Preferably it is 0.6 mass% or more.
On the other hand, if the C content is too high, huge carbides are produced during steelmaking, which not only adversely affects the subsequent quenching characteristics and rolling fatigue life, but also reduces the header workability and causes an increase in cost. Therefore, the C content is set to 1.2% by mass or less.

〔Ｓｉ含有率：０．４質量％以上２．０質量％以下〕
Ｓｉ（ケイ素）は、製鋼時に脱酸剤としての作用を有するとともに、基地であるマルテンサイトを強化し、且つ、焼戻し軟化抵抗性を高め、転がり疲れ寿命を向上させる作用を有する。また、浸炭窒化処理を行う際に、前記表層部に必要なＮ含有率と残留オーステナイト量を付与する作用も有する。これらの作用を得るために、Ｓｉ含有率は０．４質量％以上、好ましくは０．５質量％以上とする。
一方、Ｓｉ含有率が多過ぎると、ヘッダー加工性および被削性等が低下するだけでなく、浸炭窒化処理特性が低下して、必要な硬化層深さが得られず、前記表層部のＮ含有率、ＣおよびＮの合計含有率および残留オーステナイト量を本発明の範囲内に出来なくなる。よって、Ｓｉ含有率は２．０質量％以下、好ましくは１．５質量％以下とする。 [Si content: 0.4% by mass or more and 2.0% by mass or less]
Si (silicon) has an effect as a deoxidizer during steelmaking, strengthens martensite as a base, enhances temper softening resistance, and improves rolling fatigue life. Moreover, when performing a carbonitriding process, it also has the effect | action which provides N content rate and residual austenite amount which are required for the said surface layer part. In order to obtain these effects, the Si content is 0.4% by mass or more, preferably 0.5% by mass or more.
On the other hand, if the Si content is too high, not only the header workability and machinability are degraded, but also the carbonitriding properties are degraded, and the required hardened layer depth cannot be obtained. The content, the total content of C and N, and the amount of retained austenite cannot be within the scope of the present invention. Therefore, the Si content is 2.0% by mass or less, preferably 1.5% by mass or less.

〔Ｍｎ含有率：０．２質量％以上２．０質量％以下〕
Ｍｎ（マンガン）は、Ｓｉと同様に、製鋼時に脱酸剤としての作用を有する他、焼入れ性を向上させ、且つ、転がり疲れ寿命に有効な残留オーステナイト量の生成を促進する作用を有する。これらの作用を得るために、Ｍｎ含有率は０．２質量％以上とする。
一方、Ｍｎ含有率が多過ぎると、ヘッダー加工性および被削性が低下するだけでなく、熱処理後に多量の残留オーステナイトが存在して、良好な転がり疲れ寿命が得られなくなる。よって、Ｍｎ含有率は２．０質量％以下、好ましくは０．７質量％以下とする。 [Mn content: 0.2% by mass or more and 2.0% by mass or less]
Similar to Si, Mn (manganese) has an effect as a deoxidizer during steelmaking, and also has an effect of improving hardenability and promoting the generation of residual austenite amount effective for rolling fatigue life. In order to obtain these effects, the Mn content is set to 0.2% by mass or more.
On the other hand, if the Mn content is too high, not only the header workability and machinability are lowered, but also a large amount of retained austenite is present after the heat treatment, so that a good rolling fatigue life cannot be obtained. Therefore, the Mn content is 2.0% by mass or less, preferably 0.7% by mass or less.

〔Ｃｒ含有率：０．５質量％以上２．０質量％以下〕
Ｃｒ（クロム）は、基地に固溶して、焼入れ性および焼戻し軟化抵抗性を向上させる作用を有する。また、Ｃｒは、高硬度の微細な炭化物または炭窒化物を形成して、円すいころ軸受のころとして必要な硬さを付与するとともに、熱処理時の結晶粒の粗大化を抑制し、転がり疲れ寿命を向上させる作用も有する。これらの作用を得るために、Ｃｒ含有率は０．５質量％以上、好ましくは１．３質量％以上とする。
一方、Ｃｒ含有率が多過ぎると、製鋼時に巨大な炭化物が生成されて、その後の焼入れ特性や転がり疲れ寿命に悪影響を及ぼすだけでなく、ヘッダー加工性および被削性が低下して生産コストの上昇を招く。よって、Ｃｒ含有率は２．０質量％以下、好ましくは１．６質量％以下とする。 [Cr content: 0.5% by mass or more and 2.0% by mass or less]
Cr (chromium) dissolves in the matrix and has the effect of improving the hardenability and temper softening resistance. In addition, Cr forms fine carbides or carbonitrides with high hardness to give the necessary hardness as a roller for tapered roller bearings, suppresses coarsening of crystal grains during heat treatment, and rolling fatigue life It also has an effect of improving. In order to obtain these effects, the Cr content is 0.5 mass% or more, preferably 1.3 mass% or more.
On the other hand, if the Cr content is too high, huge carbides are produced during steelmaking, which not only adversely affects the subsequent quenching characteristics and rolling fatigue life, but also reduces the workability of the header and the machinability. Invite rise. Therefore, the Cr content is 2.0% by mass or less, preferably 1.6% by mass or less.

〔鋼のその他の構成成分について〕
本発明で使用する鋼は、上述した元素に加えて、Ｃｒと同様の作用を有するＭｏ（モリブデン）やＶ（バナジウム）等の炭化物形成促進元素を、素材費の上昇や加工性の低下によるコスト上昇を招かない範囲で含有してもよい。ＭｏやＶの含有率は、合計で４．０質量％以下とすることが好ましい。
また、本発明で使用する鋼において、上述した必須成分（Ｃ，Ｓｉ，Ｍｎ，Ｃｒ）および選択的に含有させるＭｏやＶ以外は、実質的にＦｅ（鉄）からなるが、不可避不純物として、Ｓ（硫黄），Ｐ（リン），Ａｌ（アルミニウム），Ｔｉ（チタン），Ｏ（酸素）等が含有されていてもよい。これらの元素は、表面起点型の破損に対して特に際立った抑制効果はないと言われているが、鋼の品質が著しく悪い場合には、これらが起点となって内部起点型の破損が生じる。このため、不可避不純物の含有率は、コストの著しい上昇を招かない範囲で、ＪＩＳ Ｇ ４８０５に規定された高炭素クロム軸受鋼の清浄度規制を満たす品質レベルとする。 [About other components of steel]
In addition to the above-described elements, the steel used in the present invention includes elements for promoting the formation of carbides such as Mo (molybdenum) and V (vanadium), which have the same effect as Cr. You may contain in the range which does not cause a raise. The total content of Mo and V is preferably 4.0% by mass or less.
Further, in the steel used in the present invention, except for the essential components (C, Si, Mn, Cr) and Mo and V to be selectively contained, the steel is substantially composed of Fe (iron). S (sulfur), P (phosphorus), Al (aluminum), Ti (titanium), O (oxygen) and the like may be contained. These elements are said to have no particularly remarkable inhibitory effect on surface-origin type breakage, but if the quality of the steel is extremely poor, these originate as internal origin-type breakages. . For this reason, the content of inevitable impurities is set to a quality level that satisfies the cleanliness regulations for high carbon chrome bearing steel defined in JIS G 4805 without causing a significant increase in cost.

〔表層部のＮ含有率：０．２０質量％以上２．００質量％以下〕
Ｎ（窒素）は、基地に固溶して、前記表層部に必要な強度を付与するとともに、前記表層部に必要な残留オーステナイトを存在させる作用を有する。また、Ｎは、窒化物や炭窒化物を形成して、摩擦・摩耗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、前記表層部のＮ含有率は０．２０質量％以上、好ましくは０．５０質量％以上とする。一方、前記表層部のＮ含有率が多過ぎると、窒化物や炭窒化物の析出量が増大して、前記表層部に必要な残留オーステナイトを存在させられなくなるとともに、焼入れ性が低下して十分な耐疲労性が得られなくなる。よって、前記表層部のＮ含有率は２．００質量％以下とする。 [N content of surface layer: 0.20 mass% or more and 2.00 mass% or less]
N (nitrogen) dissolves in the matrix and imparts the necessary strength to the surface layer portion, and also has the effect of causing the necessary retained austenite to exist in the surface layer portion. N also has the effect of improving the friction and wear characteristics by forming nitrides and carbonitrides. In order to obtain these effects, the N content of the surface layer portion is 0.20% by mass or more, preferably 0.50% by mass or more. On the other hand, when the N content of the surface layer portion is too large, the amount of nitride and carbonitride deposited increases, making it impossible to cause the retained austenite to exist in the surface layer portion, and the hardenability is sufficiently reduced. Fatigue resistance cannot be obtained. Therefore, the N content of the surface layer is set to 2.00% by mass or less.

〔表層部のＣおよびＮの合計含有率：１．２０質量％以上３．００質量％以下〕
Ｃ（炭素）は、Ｎと同様に、前記表層部に必要な強度と残留オーステナイト量を付与するとともに、摩擦・摩耗特性を向上させる作用を有する。この作用を得るために、前記表層部のＣ含有率は、ＣおよびＮの合計含有率で１．２０質量％以上、好ましくは１．５０質量％以上となるようにする。一方、前記表層部のＣ含有率が多過ぎると、巨大な炭化物が生成されて、転がり疲れ寿命が低下する。よって、前記表層部のＣ含有率は、ＣおよびＮの含有率で３．００質量％以下となるようにする。 [Total content of C and N in the surface layer portion: 1.20 mass% or more and 3.00 mass% or less]
C (carbon), like N, imparts the necessary strength and the amount of retained austenite to the surface layer portion, and has the effect of improving the friction and wear characteristics. In order to obtain this effect, the C content of the surface layer portion is 1.20% by mass or more, preferably 1.50% by mass or more in terms of the total content of C and N. On the other hand, when there is too much C content rate of the said surface layer part, a huge carbide | carbonized_material will be produced | generated and rolling fatigue life will fall. Therefore, the C content of the surface layer portion is 3.00% by mass or less in terms of the C and N content.

〔表層部の残留オーステナイト量：５体積％以上２０体積％以下〕
前記表層部に存在する残留オーステナイトは、転がり面に生じた圧痕に起因する応力集中を緩和する作用を有する。この作用を得るために、前記表層部の残留オーステナイト量は５体積％以上、好ましくは８体積％以上とする。一方、前記表層部の残留オーステナイト量が多過ぎると、ころに表面起点型剥離が生じ難くなるが、耐疲労特性が得られなくなったり、表面硬さが低下したりするため、上述した接線力を小さくすることによる寿命延長効果が得られなくなる。よって、前記表層部の残留オーステナイト量は２０体積％以下とする。 [Amount of retained austenite in the surface layer: 5% by volume or more and 20% by volume or less]
The retained austenite existing in the surface layer portion has an action of relaxing stress concentration caused by the indentation generated on the rolling surface. In order to obtain this effect, the amount of retained austenite in the surface layer portion is 5% by volume or more, preferably 8% by volume or more. On the other hand, if the amount of retained austenite in the surface layer portion is too large, surface-originated peeling is less likely to occur on the roller, but fatigue resistance characteristics cannot be obtained, or surface hardness is reduced. The life extension effect by making it small cannot be obtained. Therefore, the amount of retained austenite in the surface layer portion is set to 20% by volume or less.

〔表層部の硬さ：Ｈｖ７５０以上Ｈｖ９００以下〕
前記表層部の硬さは、異物の噛み込みによる圧痕の発生を抑制することにより、圧痕縁に作用する接線力の増大を抑制するために、Ｈｖ７５０以上とする。一方、前記表層部が硬過ぎると、十分な残留オーステナイト量が確保できなくなったり、かえって靱性が低下する場合もあるため、前記表層部の硬さはＨｖ９００以下とする。 [Hardness of surface layer part: Hv750 or more and Hv900 or less]
The hardness of the surface layer portion is set to Hv 750 or more in order to suppress an increase in tangential force acting on the indentation edge by suppressing generation of indentation due to the biting of foreign matter. On the other hand, if the surface layer portion is too hard, a sufficient amount of retained austenite may not be ensured, or the toughness may be lowered. Therefore, the hardness of the surface layer portion is set to Hv 900 or less.

〔熱処理について〕
まず、上述した特定の鋼からなる線材（素材）にヘッダー加工および粗施削加工等を施すことにより、所定形状に加工した後、混合ガス（ＲＸガス＋エンリッチガス＋アンモニアガス）を導入した炉内で数時間加熱保持することにより、浸炭窒化処理を行う。
この浸炭窒化処理は、焼入れ後の前記表層部の残留オーステナイト量および硬さを本発明の範囲内にできるように、ＮとＣを基地組織に固溶させるとともに、焼入れ後の前記表層部に摩耗・摩擦低減効果の高い窒化物や炭窒化物を析出分散させることを目的として行われる。 [About heat treatment]
First, a furnace in which a mixed gas (RX gas + enrich gas + ammonia gas) is introduced after processing the wire rod (raw material) made of the specific steel described above into a predetermined shape by performing header processing, rough machining processing, or the like The carbonitriding process is performed by heating and holding for several hours.
This carbonitriding process causes N and C to be dissolved in the base structure so that the amount of retained austenite and hardness of the surface layer portion after quenching can be within the scope of the present invention, and wears to the surface layer portion after quenching. -It is performed for the purpose of precipitating and dispersing nitrides and carbonitrides having a high friction reducing effect.

ここで、アンモニアガスは処理温度が高くなる程分解し易くなる。アンモニアガスが分解し易くなると、混合ガス中の残留アンモニアガスの濃度が小さくなり、前記表層部に本発明の範囲内のＮ含有率が得られなくなる。一方、処理温度が低くなると、基地組織に十分な炭素や窒素を固溶させることができないため、前記表層部に耐疲労特性と本発明の範囲内の残留オーステナイト量が得られなくなる。よって、浸炭窒化処理は、雰囲気温度８２０〜８５０℃程度で行うことが好ましい。   Here, the ammonia gas is easily decomposed as the processing temperature increases. If the ammonia gas is easily decomposed, the concentration of the residual ammonia gas in the mixed gas becomes small, and the N content within the range of the present invention cannot be obtained in the surface layer portion. On the other hand, if the treatment temperature is lowered, sufficient carbon and nitrogen cannot be dissolved in the matrix structure, so that fatigue resistance and the amount of retained austenite within the scope of the present invention cannot be obtained in the surface layer portion. Therefore, the carbonitriding process is preferably performed at an ambient temperature of about 820 to 850 ° C.

次に、焼入れ処理を行った後、マルテンサイト組織の安定化のために２００〜２６０℃程度の焼戻し処理を行う。次に、研削加工およびバレル加工等を行うことにより、所望の形状とするとともに、ころの転がり面および大径側鍔部との摺接面になる大径側端面を以下に示す表面粗さに仕上げる。
また、本発明の円すいころ軸受において、前記ころの転がり面の表面粗さを、算術平均粗さＲａで０．１２μｍ以下、好ましくは０．１０μｍ以下とすることにより、異物混入潤滑下における寿命をさらに長くできる。 Next, after performing a quenching process, a tempering process of about 200 to 260 ° C. is performed to stabilize the martensite structure. Next, by carrying out grinding and barrel processing, etc., the desired surface shape is obtained, and the large-diameter side end surface that becomes the sliding contact surface with the rolling surface of the roller and the large-diameter side flange is reduced to the surface roughness shown below. Finish.
Further, in the tapered roller bearing of the present invention, the surface roughness of the rolling surface of the roller is 0.12 μm or less, preferably 0.10 μm or less in terms of arithmetic average roughness Ra. It can be longer.

ここで、前記ころの表面粗さ（Ｒａ）が０．１２μｍを超えると、圧痕の盛り上がり部において、金属接触が生じ、ころと内外輪との間に作用する接線力が大きくなるため、十分な寿命延長効果が得られなくなる。
さらに、本発明の円すいころ軸受において、前記大径側鍔部の内側面の表面粗さσ1 と前記ころの大径側端面の表面粗さσ2 との合成粗さσ＝√( σ1 2＋σ2 2）を、算術平均粗さ（Ｒａ）で０．１５μｍ以下とすることにより、ころと大径側鍔部との摺接面の焼付き寿命をさらに長くできる。
ここで、前記合成粗さ（Ｒａ）が０．１５μｍを超えると、金属接触し易くなって、耐焼付き性が低下する。 Here, when the surface roughness (Ra) of the roller exceeds 0.12 μm, metal contact occurs at the bulge portion of the indentation, and the tangential force acting between the roller and the inner and outer rings is increased. Life extension effect cannot be obtained.
Further, in the tapered roller bearing of the present invention, the combined roughness σ = √ (σ 1 of the surface roughness σ 1 of the inner surface of the large-diameter side flange and the surface roughness σ 2 of the large-diameter end surface of the roller. 2 + σ 2 2 ) is 0.15 μm or less in terms of arithmetic average roughness (Ra), the seizure life of the sliding contact surface between the roller and the large-diameter side flange can be further extended.
Here, when the said synthetic roughness (Ra) exceeds 0.15 micrometer, it will become easy to contact a metal and seizure resistance will fall.

本発明の円すいころ軸受によれば、ころを構成する鋼からなる素材と、その転がり面および大径側鍔部との摺接面をなす表層部のＮ含有率，ＣおよびＮの合計含有率，残留オーステナイト量，硬さとを特定することにより、ころ自身のみならず、内外輪の表面起点型剥離も抑制できるとともに、ころと大径側鍔部との摺接面での焼付きを抑制できる。よって、異物混入潤滑下で使用した場合でも、寿命を長くできる。
また、ころを変えるだけで円すいころ軸受の寿命を長くできるため、装置の低コスト化も実現できる。 According to the tapered roller bearing of the present invention, the N content of the surface layer part that forms the sliding contact surface between the rolling material and the large-diameter side flange, and the total content of C and N By specifying the amount of retained austenite and hardness, not only the roller itself but also the surface-origin separation of the inner and outer rings can be suppressed, and seizure on the sliding contact surface between the roller and the large-diameter side flange can be suppressed. . Therefore, the life can be extended even when used under the contamination with foreign matter.
Further, since the life of the tapered roller bearing can be extended by simply changing the roller, the cost of the apparatus can be reduced.

以下、本発明の実施形態を図面を参照しながら説明する。
本実施形態では、図１に示す呼び番号Ｌ４４６４９／６１０の円すいころ軸受（外径：５０．２９２ｍｍ，内径：２６．９８８ｍｍ，幅：１４．２２４ｍｍ）を以下のようにして作製した。
この円すいころ軸受は、図１に示すように、内輪１と、外輪２と、円すい形状の複数のころ３と、保持器４と、からなる。内輪１の外周面端部には、大径側鍔部１０Ａと小径側鍔部１０Ｂとが形成されている。ころ３は、大径側鍔部１０Ａの内側面１０ａに案内されながら両軌道面１ａ，２ａ間を転動する。また、ころ３の大径側端面３ａと大径側鍔部１０Ａの内側面１０ａとは、ころ３の転動に伴って摺接するようになっている。 Embodiments of the present invention will be described below with reference to the drawings.
In the present embodiment, a tapered roller bearing (outer diameter: 50.292 mm, inner diameter: 26.988 mm, width: 14.224 mm) having an identification number L44649 / 610 shown in FIG. 1 was produced as follows.
As shown in FIG. 1, the tapered roller bearing includes an inner ring 1, an outer ring 2, a plurality of tapered rollers 3, and a cage 4. A large-diameter side flange portion 10A and a small-diameter side flange portion 10B are formed at the outer peripheral surface end of the inner ring 1. The roller 3 rolls between both raceway surfaces 1a and 2a while being guided by the inner surface 10a of the large-diameter side flange portion 10A. Further, the large-diameter side end surface 3 a of the roller 3 and the inner surface 10 a of the large-diameter side flange portion 10 </ b> A come into sliding contact with the rolling of the roller 3.

円すいころ軸受のころ３は、以下のようにして作製した。
まず、表１に示す各含有率のＣ，Ｓｉ，Ｍｎ，Ｃｒを含む鋼からなる線材（素材）に、ヘッダー加工および粗施削加工を施すことにより、ころの形状に加工した。
次に、これらに表１に示す各方法の熱処理を施した。次に、これらに研削仕上げ加工および超仕上げ加工を施すことにより、ころ３の外周面（転がり面）と大径側端面３ａの表面粗さ（Ｒａ）を調節した。表１に示す「合成粗さ」とは、ころ３の大径側端面３ａの表面粗さσ1 （Ｒａ）と大径側鍔部１０Ａの内側面１０ａの表面粗さσ2 （Ｒａ）とから算出した合成粗さσ＝√（σ1 2＋σ2 2）を示す。 The roller 3 of the tapered roller bearing was produced as follows.
First, a wire rod (raw material) made of steel containing C, Si, Mn, and Cr of each content shown in Table 1 was processed into a roller shape by performing header processing and rough cutting processing.
Next, heat treatment of each method shown in Table 1 was performed on them. Next, the surface roughness (Ra) of the outer peripheral surface (rolling surface) of the roller 3 and the large-diameter side end surface 3a was adjusted by subjecting them to grinding finishing and super finishing. “Synthetic roughness” shown in Table 1 means the surface roughness σ 1 (Ra) of the large-diameter end face 3a of the roller 3, the surface roughness σ 2 (Ra) of the inner surface 10a of the large-diameter flange portion 10A, and The composite roughness σ = √ (σ 1 2 + σ 2 2 ) calculated from

なお、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、ＲＸガス＋エンリッチガス＋アンモニアガスの雰囲気中において、８３０℃で３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、１６０〜２４０℃の範囲の所定温度で２時間保持することにより焼戻しを行った。
また、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、８４０℃で０．５時間保持した後、油焼入れを行った。次に、１６０℃で２時間保持することにより焼戻しを行った。 The heat treatment shown in Table 1 as “carbonitriding → quenching → tempering” was performed under the following conditions. First, carbonitriding was performed by holding at 830 ° C. for 3 hours in an atmosphere of RX gas + enrich gas + ammonia gas, followed by oil quenching. Next, tempering was performed by holding at a predetermined temperature in the range of 160 to 240 ° C. for 2 hours.
Further, the heat treatment shown in Table 1 as “quenching → tempering” was performed under the following conditions. First, in an RX gas atmosphere, oil quenching was performed after holding at 840 ° C. for 0.5 hour. Next, tempering was performed by holding at 160 ° C. for 2 hours.

さらに、表１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、ＲＸガス＋エンリッチガスの雰囲気中において、８４０℃で３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、１６０℃で２時間保持することにより焼戻しを行った。
このようにして得られたころ３において、その転がり面および大径側端面３ａ（大径側鍔部１０Ａとの摺接面））をなす表層部（表面から５０μｍの深さ部分）のＮ含有率およびＣ含有率 (質量比）を、電子線マイクロアナライザ (ＥＰＭＡ）により測定した。この結果を、表１に併せて示した。 Furthermore, the heat treatment shown in Table 1 as “carburization → quenching → tempering” was performed under the following conditions. First, carburization was performed by holding at 840 ° C. for 3 hours in an RX gas + enrich gas atmosphere, and then oil quenching was performed. Next, tempering was performed by holding at 160 ° C. for 2 hours.
In the roller 3 obtained in this manner, the N content of the surface layer portion (depth portion of 50 μm from the surface) forming the rolling surface and the large-diameter side end surface 3a (sliding contact surface with the large-diameter side flange portion 10A). The ratio and the C content (mass ratio) were measured by an electron beam microanalyzer (EPMA). The results are also shown in Table 1.

また、前記表層部の残留オーステナイト量γR ( 体積比）を、Ｘ線回折装置により測定した。この結果を、表１に併せて示した。
さらに、前記表層部の硬さ（Ｈｖ）を、荷重９．８Ｎを加えた条件下でビッカース硬度計を用いて測定した。この結果を、表１に併せて示した。
このようにして得られた円すいころ軸受のころ３と、ＳＵＪ２製で焼入れおよび焼戻しが施された内輪１および外輪２と、冷間圧延鋼板（ＳＰＣＣ）製のプレス保持器４とを用いて、円すいころ軸受を組み立てた。なお、内輪１は、大径側鍔部１０Ａの内側面１０ａの表面粗さ（Ｒａ）が０．０８〜０．２０μｍに調整されたものを用いた。 Further, the amount of retained austenite γ R (volume ratio) of the surface layer portion was measured with an X-ray diffractometer. The results are also shown in Table 1.
Furthermore, the hardness (Hv) of the surface layer portion was measured using a Vickers hardness tester under a condition where a load of 9.8 N was applied. The results are also shown in Table 1.
Using the roller 3 of the tapered roller bearing thus obtained, the inner ring 1 and the outer ring 2 made of SUJ2 and quenched and tempered, and the press cage 4 made of cold-rolled steel plate (SPCC), Tapered roller bearings were assembled. In addition, the inner ring | wheel 1 used what the surface roughness (Ra) of the inner surface 10a of 10 A of large diameter side collar parts was adjusted to 0.08-0.20 micrometers.

次に、これらの円すいころ軸受を用いて、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寿命試験を行った。なお、この試験は、内輪１、外輪２、およびころ３の少なくとも一つにフレーキングが発生するまで行い、このフレーキングが発生するまでの累積応力繰り返し回転数を寿命として測定した。
異物混入潤滑下での寿命試験の結果は、各サンプルについてそれぞれ１０回の寿命試験を行い、ワイブル分布関数に基づくＬ10寿命を計算して、Ｎｏ．２０のＬ10寿命を１とした時の比を、表１に併せて示した。また、この試験結果から、図２に示すように、ころ３の前記表層部のＮ含有率と異物混入潤滑下での寿命との関係を示すグラフを作成した。さらに、この試験結果から、図４に示すように、ころ３の転がり面の表面粗さと異物混入潤滑下での寿命との関係を示すグラフを作成した。 Next, using these tapered roller bearings, a life test was performed under the following conditions assuming use under the contamination with foreign matter. This test was performed until flaking occurred in at least one of the inner ring 1, the outer ring 2, and the roller 3, and the cumulative stress repetition rotational speed until the occurrence of flaking was measured as the life.
As a result of the life test under the foreign matter mixed lubrication, each sample was subjected to 10 life tests, and the L 10 life based on the Weibull distribution function was calculated. The ratio when set to 1 20 L 10 life, also shown in Table 1. Moreover, from this test result, as shown in FIG. 2, the graph which shows the relationship between N content rate of the said surface layer part of the roller 3, and the lifetime under foreign material mixing lubrication was created. Furthermore, from this test result, as shown in FIG. 4, a graph showing the relationship between the surface roughness of the rolling surface of the roller 3 and the life under lubrication with foreign matters was prepared.

〔異物混入潤滑下での寿命試験条件〕
荷重比（Ｐ／Ｃｒ）：０．４３
回転速度：４０００ｍｉｎ-1
潤滑油：♯６８タービン油
混入異物：（組成）Ｆｅ3 Ｃ
（硬さ）Ｈｖ８７０
（粒径）７４〜１４７μｍ
（混入量）潤滑油中に３００ｐｐｍとなるように混入 [Life test conditions under lubrication with foreign substances]
Load ratio (P / Cr): 0.43
Rotational speed: 4000 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

次に、上述した円すいころ軸受について、以下の条件で焼付き試験を行った。この焼付き試験は、潤滑油を供給しつつ所定時間内輪１を運転した後潤滑油の供給を停止し、さらに内輪１を回転させることにより行った。なお、この試験は、トルクが急上昇するまでの時間を焼付き寿命として測定した。
焼付き寿命試験の結果は、各サンプルについてそれぞれ５回の焼付き試験を行い、ワイブル分布関数に基づくＬ10寿命を計算して、比較例であるＮｏ．２０のＬ10寿命を１とした時の比を、表１に併せて示した。また、この試験結果から、図３に示すように、ころ３の前記表層部のＮ含有率と焼付き寿命との関係を示すグラフを作成した。さらに、この試験結果から、図５に示すように、ころ３の大径側端面３ａおよび大径側鍔部１０Ａの内側面１０ａの合成粗さと焼付き寿命との関係を示すグラフを作成した。
〔焼付き寿命試験条件〕
スラスト荷重：４０００Ｎ
回転速度：６０００ｍｉｎ-1
潤滑油：ギア油（４０℃における動粘度：１８０ｍｍ2 ／ｓ）
給油停止前の潤滑油供給量：４８０ｃｃ／ｍｉｎ Next, a seizure test was performed on the tapered roller bearing described above under the following conditions. This seizure test was performed by operating the inner ring 1 for a predetermined time while supplying the lubricating oil, then stopping the supply of the lubricating oil, and further rotating the inner ring 1. In this test, the time until the torque suddenly increased was measured as the seizure life.
As a result of the seizure life test, each sample was subjected to 5 seizure tests, and the L 10 life based on the Weibull distribution function was calculated. The ratio when set to 1 20 L 10 life, also shown in Table 1. Moreover, from this test result, as shown in FIG. 3, the graph which shows the relationship between N content rate of the said surface layer part of the roller 3, and a seizure lifetime was created. Furthermore, from this test result, as shown in FIG. 5, a graph showing the relationship between the combined roughness of the large-diameter end face 3a of the roller 3 and the inner surface 10a of the large-diameter side flange 10A and the seizure life was prepared.
[Seizure life test conditions]
Thrust load: 4000N
Rotational speed: 6000 min -1
Lubricating oil: gear oil (kinematic viscosity at 40 ° C .: 180 mm 2 / s)
Lubricating oil supply before stopping oil supply: 480 cc / min

Figure 2006045591
Figure 2006045591

表１に示すように、ころ３を本発明の構成 (鋼中のＣ，Ｓｉ，Ｍｎ，Ｃｒの含有率と、前記表層部のＮ含有率，Ｃ＋Ｎ含有率，残留オーステナイト量，硬さ）とした発明例Ｎｏ．１〜１９では、ころ３を本発明の構成外とした比較例Ｎｏ．２０〜２８と比べて、異物混入潤滑下での寿命が長くなっていた。また、発明例Ｎｏ．１〜１９の焼付き寿命は、比較例Ｎｏ．２０〜２８と同程度か、より長くなっていた。   As shown in Table 1, the roller 3 is composed of the present invention (content of C, Si, Mn, Cr in steel, N content of the surface layer, C + N content, residual austenite content, hardness) and Invention Example No. In Comparative Examples Nos. 1 to 19 in which the roller 3 is outside the configuration of the present invention. Compared with 20-28, the lifetime under the foreign matter mixed lubrication was longer. In addition, Invention Example No. The seizure life of 1 to 19 is comparative example No. It was about the same as 20-28 or longer.

図２に示すように、ころ３の表層部のＮ含有率を０．２０質量％以上としたＮｏ．１〜１９では、異物混入潤滑下での寿命がＮｏ．２０の１．６１倍以上となっていることが分かる。ここで、Ｎｏ．２３〜２５では、ころ３の表層部のＮ含有率が０．２０質量％以上であるが、異物混入潤滑下での寿命が十分に得られなかった。これは、ころ３の表層部の硬さおよび残留オーステナイト量が本発明の範囲外であったためであると考えられる。   As shown in FIG. 2, the N content of the surface layer portion of the roller 3 is 0.20% by mass or more. Nos. 1 to 19 have a life of No. It turns out that it is 1.61 times or more of 20. Here, no. In Nos. 23 to 25, the N content of the surface layer portion of the roller 3 was 0.20% by mass or more, but the life under the contamination with foreign matters was not sufficiently obtained. This is presumably because the hardness of the surface layer portion of the roller 3 and the amount of retained austenite were outside the scope of the present invention.

図３に示すように、ころ３の表層部のＮ含有率を０．２質量％以上としたＮｏ．１〜１９では、焼付き寿命がＮｏ．２０の１．５倍以上となっていることが分かる。ここで、Ｎｏ．２３，２５では、ころ３の表層部のＮ含有率が０．２０質量％以上であったが、十分な焼付き寿命が得られなかった。これは、ころ３の表層部の硬さおよび残留オーステナイト量が本発明の範囲外であったためであると考えられる。
本発明例のうちＮｏ．１７では、ころ３の転がり面の表面粗さ（Ｒａ）が０．１２μｍを超えていたため、ころ３の転がり面の表面粗さ（Ｒａ）が本発明の範囲内であるＮｏ．１〜１６，１８と比べて、異物混入潤滑下での寿命が短かった。 As shown in FIG. 3, the N content of the surface layer portion of the roller 3 is 0.2% by mass or more. 1 to 19, the seizure life was No. It turns out that it is 1.5 times or more of 20. Here, no. In Nos. 23 and 25, the N content of the surface layer of the roller 3 was 0.20% by mass or more, but a sufficient seizure life could not be obtained. This is presumably because the hardness of the surface layer portion of the roller 3 and the amount of retained austenite were outside the scope of the present invention.
Among the examples of the present invention, No. No. 17, since the surface roughness (Ra) of the rolling surface of the roller 3 exceeded 0.12 μm, the surface roughness (Ra) of the rolling surface of the roller 3 was within the scope of the present invention. Compared with 1 to 16 and 18, the life under foreign matter mixed lubrication was short.

図４に示すように、ころ３の転がり面の表面粗さ（Ｒａ）を０．１２μｍ以下としたＮｏ．１〜１６，１８では、異物混入潤滑下での寿命がＮｏ．２０の１．９０倍以上となっていることが分かる。
ここで、Ｎｏ．２０，２２〜２７では、ころ３の転がり面の表面粗さ（Ｒａ）が０．１２μｍ以下であるが、異物混入潤滑下での寿命が十分に得られなかった。これは、ころ３の表層部のＮ含有率，残留オーステナイト量，硬さのいずれかが本発明の範囲外であったためであると考えられる。 As shown in FIG. 4, the surface roughness (Ra) of the rolling surface of the roller 3 is 0.12 μm or less. In Nos. 1 to 16 and 18, the life under the foreign matter mixed lubrication is No. It turns out that it is 1.90 times or more of 20.
Here, no. In Nos. 20 and 22 to 27, the surface roughness (Ra) of the rolling surface of the roller 3 was 0.12 μm or less, but the life under lubrication mixed with foreign matter was not sufficiently obtained. This is considered to be because any of the N content, the retained austenite amount, and the hardness of the surface layer portion of the roller 3 was outside the scope of the present invention.

また、本発明例のうちＮｏ．１８，１９では、ころ３の大径側端面３ａと大径側鍔部１０Ａの内側面１０ａとの合成粗さ（Ｒａ）が０．１５μｍを超えていたため、素材として同じ鋼を用いて転がり面をなす表層部の構成および合成粗さを本発明の範囲内としたＮｏ．１５と比べて、焼付き寿命が短かった。   Of the examples of the present invention, No. 18 and 19, since the combined roughness (Ra) of the large-diameter side end surface 3a of the roller 3 and the inner surface 10a of the large-diameter flange portion 10A exceeded 0.15 μm, the rolling surface using the same steel as the material The composition of the surface layer portion and the synthetic roughness are within the scope of the present invention. Compared with 15, the seizure life was short.

図５に示すように、ころ３の大径側端面３ａと大径側鍔部１０Ａの内側面１０ａとの合成粗さ（Ｒａ）が０．１５μｍ以下のＮｏ．１〜１７では、焼付き寿命がＮｏ．２０の１．５倍以上となっていた。
ここで、Ｎｏ．２０，２２〜２８では、合成粗さ（Ｒａ）が０．１５μｍ以下であるが、焼付き寿命が十分に得られなかった。これは、ころ３の表層部のＮ含有率，残留オーステナイト量，硬さのいずれかが本発明の範囲外であったためであると考えられる。 As shown in FIG. 5, the composite roughness (Ra) between the large-diameter side end surface 3a of the roller 3 and the inner surface 10a of the large-diameter side flange 10A is No. 0.15 μm or less. 1 to 17, the seizure life was No. It was 1.5 times or more than 20.
Here, no. In 20, 22 to 28, the synthetic roughness (Ra) was 0.15 μm or less, but the seizure life was not sufficiently obtained. This is considered to be because any of the N content, the retained austenite amount, and the hardness of the surface layer portion of the roller 3 was outside the scope of the present invention.

以上の結果から、円すいころ軸受のころ３を本発明の構成 (鋼中のＣ，Ｓｉ，Ｍｎ，Ｃｒの含有率と、前記表層部のＮ含有率，Ｃ＋Ｎ含有率，残留オーステナイト量，硬さ）とすることにより、異物混入潤滑下での寿命および焼付き寿命をともに長くできることが分かった。
また、上述した構成に加えて、円すいころ軸受のころ３の転がり面の表面粗さ（Ｒａ）を特定することにより、異物混入潤滑下での寿命をさらに長くできることが分かった。
さらに、上述した構成に加えて、円すいころ軸受のころ３の大径側端面３ａと大径側鍔部１０Ａの内側面１０ａとの合成粗さ（Ｒａ）を特定することにより、円すいころ軸受の焼付き寿命をさらに長くできることが分かった。 From the above results, the roller 3 of the tapered roller bearing has the structure of the present invention (content of C, Si, Mn, Cr in steel, N content of the surface layer, C + N content, residual austenite content, hardness. It was found that the life and seizure life under lubrication mixed with foreign substances can be increased.
Moreover, in addition to the structure mentioned above, it turned out that the life under foreign material mixing lubrication can be further extended by specifying the surface roughness (Ra) of the rolling surface of the roller 3 of a tapered roller bearing.
Furthermore, in addition to the above-described configuration, by specifying the combined roughness (Ra) of the large-diameter side end surface 3a of the roller 3 of the tapered roller bearing and the inner surface 10a of the large-diameter flange portion 10A, the tapered roller bearing It was found that the seizure life can be further extended.

本発明の円すいころ軸受の一例を示す断面図である。It is sectional drawing which shows an example of the tapered roller bearing of this invention. ころの表層部のＮ含有率と、異物混入潤滑下での寿命との関係を示すグラフである。It is a graph which shows the relationship between N content rate of the surface layer part of a roller, and the lifetime under foreign material mixing lubrication. ころの表層部のＮ含有率と、焼付き寿命との関係を示すグラフである。It is a graph which shows the relationship between N content rate of the surface layer part of a roller, and a seizure lifetime. ころの転がり面の表面粗さと、異物混入潤滑下での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 surface roughness of the rolling surface of a roller, and the lifetime under foreign material mixing lubrication. ころの大径側端面および大径側鍔部の内側面の合成粗さと、焼付き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 synthetic | combination roughness of the large diameter side end surface of a roller, and the inner surface of a large diameter side collar part, and a seizure lifetime.

符号の説明Explanation of symbols

１ 内輪
２ 外輪
３ ころ
３ａ 大径側端面
１０ 鍔部
１０Ａ 大径側鍔部
１０ａ 内側面 DESCRIPTION OF SYMBOLS 1 Inner ring 2 Outer ring 3 Roller 3a Large diameter side end surface 10 ridge part 10A Large diameter side ridge part 10a Inner side surface

Claims (3)

内輪と、外輪と、前記内輪および外輪の間に転動自在に配設される円すい形状の複数のころと、を備え、前記内輪の外周面端部には、前記ころの軸方向端面のうち大径側端面と摺接する内側面を有する大径側鍔部が形成されている円すいころ軸受において、
前記ころは、Ｃ含有率が０．３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、浸炭窒化処理と、焼入れ処理と、焼戻し処理とがこの順に施されて得られ、
その転がり面および前記大径側鍔部との摺接面をなす表層部は、Ｎ含有率が０．２０質量％以上２．００質量％以下、ＣおよびＮの合計含有率が１．２０質量％以上３．００質量％以下、硬さがＨｖ７５０以上Ｈｖ９００以下、残留オーステナイト量が５体積％以上２０体積％以下となっていることを特徴とする円すいころ軸受。 An inner ring, an outer ring, and a plurality of tapered rollers disposed between the inner ring and the outer ring so as to be freely rollable, and an outer peripheral surface end portion of the inner ring includes an axial end surface of the roller. In the tapered roller bearing in which the large-diameter side flange having an inner surface that is in sliding contact with the large-diameter side end surface is formed,
The roller has a C content of 0.3% by mass or more and 1.2% by mass or less, a Si content of 0.4% by mass or more and 2.0% by mass or less, and a Mn content of 0.2% by mass or more. After processing a material made of steel having 0 mass% or less and Cr content of 0.5 mass% or more and 2.0 mass% or less into a predetermined shape, carbonitriding treatment, quenching treatment, and tempering treatment are performed in this order. Obtained and given
As for the surface layer part which makes the sliding surface with the rolling surface and the said large diameter side collar part, N content rate is 0.20 mass% or more and 2.00 mass% or less, and the total content rate of C and N is 1.20 mass. A tapered roller bearing having a hardness of Hv 750 or more and Hv 900 or less and a residual austenite amount of 5 volume% or more and 20 volume% or less. 前記ころの転がり面の表面粗さは、算術平均粗さ（Ｒａ）で０．１２μｍ以下となっていることを特徴とする請求項１に記載の円すいころ軸受。   2. The tapered roller bearing according to claim 1, wherein a surface roughness of the rolling surface of the roller is an arithmetic average roughness (Ra) of 0.12 μm or less. 前記大径側鍔部の内側面の表面粗さσ1 と前記ころの大径側端面の表面粗さσ2 との合成粗さσ＝√( σ1 2＋σ2 2）は、算術平均粗さ（Ｒａ）で０．１５μｍ以下となっていることを特徴とする請求項１または２に記載の円すいころ軸受。 The combined roughness σ = √ (σ 1 2 + σ 2 2 ) of the surface roughness σ 1 of the inner surface of the large diameter side flange and the surface roughness σ 2 of the large diameter end surface of the roller is the arithmetic average roughness The tapered roller bearing according to claim 1 or 2, wherein the thickness (Ra) is 0.15 µm or less.
JP2004224628A 2004-07-30 2004-07-30 Tapered roller bearing Pending JP2006045591A (en)

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007297663A (en) * 2006-04-28 2007-11-15 Ntn Corp Carbo-nitriding process, method for manufacturing machine part, and machine part
JP2008255399A (en) * 2007-04-03 2008-10-23 Nsk Ltd Rolling bearing
JP2010185548A (en) * 2009-02-13 2010-08-26 Nsk Ltd Rolling bearing
JP2011508073A (en) * 2007-12-20 2011-03-10 ポスコ Steel wire for bearing, method for producing steel wire for bearing, heat treatment method for bearing, and soaking diffusion treatment method for bearing and cast slab for bearing
GB2512838A (en) * 2013-04-08 2014-10-15 Skf Ab Bearing component formed from steel alloy
EP3009698A4 (en) * 2013-06-10 2017-10-04 NTN Corporation Tapered roller bearing
RU2800436C1 (en) * 2022-08-29 2023-07-21 Федеральное государственное бюджетное образовательное учреждение высшего образования "Российский государственный аграрный университет - МСХА имени К.А. Тимирязева" (ФГБОУ ВО РГАУ - МСХА имени К.А. Тимирязева) Method for manufacturing a billet for a cutting blade tool for agricultural excavation equipment from high-strength steel

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007297663A (en) * 2006-04-28 2007-11-15 Ntn Corp Carbo-nitriding process, method for manufacturing machine part, and machine part
US8128761B2 (en) 2006-04-28 2012-03-06 Ntn Corporation Carbonitriding method, machinery component fabrication method, and machinery component
JP2008255399A (en) * 2007-04-03 2008-10-23 Nsk Ltd Rolling bearing
JP2011508073A (en) * 2007-12-20 2011-03-10 ポスコ Steel wire for bearing, method for producing steel wire for bearing, heat treatment method for bearing, and soaking diffusion treatment method for bearing and cast slab for bearing
US9593389B2 (en) 2007-12-20 2017-03-14 Posco Steel wire rod for bearing steel, manufacturing method of steel wire rod for bearing steel, heat treatment method of steel bearing, steel bearing and soaking method of bearing steel
JP2010185548A (en) * 2009-02-13 2010-08-26 Nsk Ltd Rolling bearing
GB2512838A (en) * 2013-04-08 2014-10-15 Skf Ab Bearing component formed from steel alloy
EP3009698A4 (en) * 2013-06-10 2017-10-04 NTN Corporation Tapered roller bearing
US9816557B2 (en) 2013-06-10 2017-11-14 Ntn Corporation Tapered roller bearing
RU2800436C1 (en) * 2022-08-29 2023-07-21 Федеральное государственное бюджетное образовательное учреждение высшего образования "Российский государственный аграрный университет - МСХА имени К.А. Тимирязева" (ФГБОУ ВО РГАУ - МСХА имени К.А. Тимирязева) Method for manufacturing a billet for a cutting blade tool for agricultural excavation equipment from high-strength steel

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