JPH11193823A - Rolling bearing - Google Patents
Rolling bearingInfo
- Publication number
- JPH11193823A JPH11193823A JP4639198A JP4639198A JPH11193823A JP H11193823 A JPH11193823 A JP H11193823A JP 4639198 A JP4639198 A JP 4639198A JP 4639198 A JP4639198 A JP 4639198A JP H11193823 A JPH11193823 A JP H11193823A
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- Prior art keywords
- graphite
- carburizing
- less
- life
- weight
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、並径サイズ以下で
素材の加工性および転がり寿命に優れた転がり軸受に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolling bearing having a size equal to or less than a diameter and having excellent workability and rolling life of a material.
【０００２】また、本発明は、比較的潤滑条件の厳しい
自動車等のトランスミッションなどで動力伝達を補佐す
る、主に針状ころを用いる転がり軸受に関する。[0002] The present invention also relates to a rolling bearing mainly using needle rollers for assisting power transmission in a transmission or the like of an automobile or the like having relatively harsh lubrication conditions.
【０００３】[0003]
【従来の技術】一般に、軸受用材料として高炭素クロム
軸受鋼（ＪＩＳ鋼種ＳＵＪ２）が使用されているが、転
がり軸受は高面圧下で繰り返しせん断応力を受けて使用
されるので、そのせん断応力に耐える転がり疲労寿命を
確保するために焼入・焼戻処理が施される。2. Description of the Related Art Generally, high carbon chromium bearing steel (JIS steel type SUJ2) is used as a bearing material. However, rolling bearings are used under repeated high shear stress under high surface pressure. Quenching and tempering treatments are performed to ensure the endurable rolling fatigue life.
【０００４】軸受鋼は熱処理後に十分な硬さを得るため
素材の炭素量やクロム量を多く含んでいるので、加工性
が悪く通常は球状化焼鈍を行ってから加工されるが、軸
受製造コストを下げるためにさらなる加工性の改善が要
望されている。[0004] Bearing steel contains a large amount of carbon and chromium in the raw material in order to obtain sufficient hardness after heat treatment. Therefore, the workability is poor and is usually processed after spheroidizing annealing. There is a demand for further improvement in workability in order to lower the workability.
【０００５】この要望に対し、特開平８−３６８９号公
報や特開平８−５３７３５号公報などには、軸受鋼の素
材の加工性を改善して製造コストを低く抑え、しかも転
がり寿命を延ばすことができる技術が開示されている。In response to this demand, JP-A-8-3689 and JP-A-8-53735 disclose improving the workability of a bearing steel material to reduce the production cost and prolong the rolling life. There is disclosed a technology that can do this.
【０００６】また、加工性、特に被削性に注目すると、
快削鋼としてイオウＳ添加を基本とするものや炭化物を
黒鉛化する黒鉛鋼などが知られているが、従来の黒鉛鋼
では軸受の完成品表面に大きな黒鉛粒が残ったり、表面
の硬さが不十分であったりして軸受に適用することは困
難であると考えられていた。その一方で、特開平２−２
７４８３７号公報や特開平８−２０８４１号公報などに
は軸受材料に黒鉛鋼を適用する技術が開示されている。Further, focusing on workability, especially machinability,
Known free-cutting steels are those based on the addition of sulfur S and graphite steels that graphitize carbides. However, conventional graphite steels leave large graphite grains on the finished bearing surface, It was thought that it was difficult to apply to a bearing because it was insufficient. On the other hand, Japanese Patent Laid-Open No. 2-2
JP-A-74837 and JP-A-8-20841 disclose techniques for applying graphite steel as a bearing material.
【０００７】一方、表面酸化がなく、効率の高い高温処
理が可能であり、高品質かつ低コストな真空浸炭法とし
て、特開平２−２２４５１号公報、特開平２−１２２０
６２号公報、特開平６−１７２９６０号公報、特開平８
−３２５７０１号公報などに開示された技術が知られて
いる。On the other hand, as a high-quality and low-cost vacuum carburizing method capable of performing high-temperature treatment with high efficiency without surface oxidation, Japanese Patent Application Laid-Open Nos.
62, JP-A-6-172960, JP-A-8
A technique disclosed in, for example, Japanese Unexamined Patent Publication No. 325701/1995 is known.
【０００８】また、従来、自動車などの車両に用いられ
るトロイダル形無段変速機は、ハウジング内に入力ディ
スク（３１）と出力ディスク（３２）とが同軸上に対向
して配置された構造を有する（図１５参照）。入力ディ
スク（３１）および出力ディスク（３２）を備えたトロ
イダル変速部の軸心部分には、入力軸（３３）が貫通さ
れている。入力ディスク（３１）および出力ディスク
（３２）の対向面はトロイダル面に形成されており、こ
のトロイダル面で形成されるトロイダルキャビティ内に
は運動伝達用のパワーローラ軸受（１６）、（１７）が
配設されている。また、入力軸（３３）の一端にはロー
ディングカム（１４）が設けられており、このローディ
ングカム（１４）はカムローラ（１５）を介して入力デ
ィスク（３１）に入力軸（３３）の動力（回転力）を伝
達する構造となっている。Conventionally, a toroidal type continuously variable transmission used for a vehicle such as an automobile has a structure in which an input disk (31) and an output disk (32) are arranged coaxially and opposed in a housing. (See FIG. 15). An input shaft (33) passes through an axial portion of the toroidal transmission unit including the input disk (31) and the output disk (32). Opposing surfaces of the input disk (31) and the output disk (32) are formed in a toroidal surface, and power roller bearings (16) and (17) for motion transmission are provided in a toroidal cavity formed by the toroidal surface. It is arranged. A loading cam (14) is provided at one end of the input shaft (33), and the loading cam (14) is connected to the input disk (31) via a cam roller (15) to drive the input shaft (33). Rotation force).
【０００９】このようなトロイダル形無段変速機とし
て、例えば特開昭６２−０３４１３８号公報や実開平２
−４９４１１号公報等に開示されたものが従来知られて
いる。また、入力ディスク、出力ディスクおよびパワー
ローラ軸受として、ＡＩＳＩ５２１００（ＪＩＳＳＵＪ
２，高炭素クロム軸受鋼相当）を使用したものが従来知
られている（ＮＡＳＡ Technical note NASA ATN D-8
362）。Such a toroidal-type continuously variable transmission is disclosed in, for example, Japanese Patent Application Laid-Open No.
Japanese Patent Application Laid-Open No. 49494/94 and the like are conventionally known. AISI 52100 (JIS SUJJ) is used as an input disk, an output disk and a power roller bearing.
2, using high carbon chromium bearing steel) (NASA Technical note NASA ATN D-8)
362).
【００１０】上記構成を有する従来のトロイダル形無段
変速機では、駆動した際、入力ディスクとパワーローラ
軸受との間に、および出力ディスクとパワーローラ軸受
との間に、例えば最大接触面圧が４Ｇｐａ程度にまで達
する高い接触圧力が生じる。In the conventional toroidal-type continuously variable transmission having the above-described structure, when driven, for example, a maximum contact surface pressure is generated between the input disk and the power roller bearing and between the output disk and the power roller bearing. High contact pressures, up to about 4 Gpa, occur.
【００１１】このため、入力ディスクおよび出力ディス
クのトラクション面およびパワーローラ軸受のトラクシ
ョン面に剥離が生じやすいという問題があった。For this reason, there has been a problem that the traction surface of the input disk and the output disk and the traction surface of the power roller bearing are easily peeled.
【００１２】また、パワーローラ軸受の軸受面も高圧面
となり、剥離することがあった。このため、高面圧下で
の転動疲労寿命に優れる高い表面硬度と、深い硬化層深
さを得ることができる製造方法が従来から要求されてい
た。Further, the bearing surface of the power roller bearing also becomes a high-pressure surface and may be peeled off. For this reason, there has been a demand for a manufacturing method capable of obtaining a high surface hardness excellent in rolling fatigue life under a high surface pressure and a deep hardened layer depth.
【００１３】これらの要求に対し、入力ディスク、出力
ディスクおよびパワーローラ軸受に使用される浸炭鋼お
よび中、高炭素鋼に浸炭処理または浸炭窒化処理を施す
ことで、転動疲労寿命の向上を図ることが行われている
（例えば、特開平７−７１５５５号公報、特開平７−２
０８５６８号公報）。[0013] In response to these requirements, the carburizing steel or medium and high carbon steel used for the input disk, the output disk, and the power roller bearing is subjected to carburizing or carbonitriding to improve the rolling fatigue life. (For example, JP-A-7-71555, JP-A-7-2
08568).
【００１４】また、入力ディスク、出力ディスクおよび
パワーローラ軸受のトラクション面に高接触面圧が加わ
ることに起因する繰り返し曲げ応力を、入力ディスク、
出力ディスクおよびパワーローラ軸受は受けることによ
り、疲労割れが生じやすいという問題があった。このた
め、転動疲労寿命に加え、曲げ疲労寿命の向上も要求さ
れていた。この疲労割れは、主に熱処理後に鋼材の表面
近傍に生じる粒界酸化に起因するものである。[0014] Further, the repetitive bending stress caused by the application of high contact surface pressure to the traction surfaces of the input disk, the output disk, and the power roller bearing,
The output disk and the power roller bearing have a problem that fatigue cracks are likely to occur when they are received. For this reason, in addition to the rolling fatigue life, an improvement in the bending fatigue life has been required. This fatigue crack is mainly caused by grain boundary oxidation occurring near the surface of the steel material after the heat treatment.
【００１５】高面圧下での曲げ疲労寿命を向上させるた
めに、従来のトロイダル形無段変速機用転動部材に対
し、浸炭および浸炭窒化処理によって生じた表面近傍の
粒界酸化を焼き入れ（硬化熱処理）後、旋削（研削）を
行って除去する方法、ショットピーニングを行い、表面
に大きな圧縮応力を発生させ、粒界酸化の欠点を改善さ
せる方法（例えば、特開平７−７１５５５号公報、特開
平７−２８６６４９号公報）、あるいは鋼材の化学成分
を限定することで熱処理時の粒界酸化層の成長を抑制す
る方法（例えば、特開平７−７１５５５号公報、特開平
７−７９３３７号公報）などの処置が施されていた。In order to improve the bending fatigue life under a high surface pressure, a conventional rolling member for a toroidal-type continuously variable transmission is quenched by grain boundary oxidation near the surface caused by carburizing and carbonitriding. After hardening heat treatment), turning (grinding) is performed, shot peening is performed, and a large compressive stress is generated on the surface to improve the defect of grain boundary oxidation (for example, Japanese Patent Application Laid-Open No. H7-171555, JP-A-7-286649) or a method of suppressing the growth of a grain boundary oxide layer during heat treatment by limiting the chemical composition of a steel material (for example, JP-A-7-71555, JP-A-7-79337) ).
【００１６】[0016]
【発明が解決しようとする課題】しかしながら、従来の
特開平８−３６８９号公報や特開平８−５３７３５号公
報などに開示された技術は、軸受鋼の加工性を改善した
程度であり、特に被削性に関しては快削鋼（イオウＳ添
加を基本とするものや黒鉛鋼など）と比べられる程のも
のではない。However, the techniques disclosed in Japanese Unexamined Patent Application Publication Nos. H8-3689 and H8-53735 have only improved the workability of bearing steel, and are particularly disadvantageous. The machinability is not as good as that of free-cutting steels (such as those based on sulfur S and graphite steel).
【００１７】また、快削鋼のうち、イオウＳ添加を基本
とするものは多量のイオウＳを多く含むので、非金属介
在物（ＭｎＳ）が多くなり清浄度が低下して十分な軸受
寿命が得られない。[0017] Of the free-cutting steels, those based on the addition of sulfur S contain a large amount of sulfur S. Therefore, non-metallic inclusions (MnS) increase, the cleanliness is reduced, and a sufficient bearing life is obtained. I can't get it.
【００１８】さらに、従来の特開平２−２７４８３７号
公報に開示された黒鉛鋼を適用する技術では、軸受の内
外輪１つ１つを熱処理する高周波焼入れを行っている
が、並径以下の軸受の生産を考慮すると、コストと生産
性が合致しない。また、軸受として使用するための寿命
評価が不十分であった。Further, in the technology using graphite steel disclosed in Japanese Patent Application Laid-Open No. Hei 2-274837, induction hardening is performed to heat-treat each of the inner and outer rings of the bearing. Considering the production of, cost and productivity do not match. Further, the life evaluation for use as a bearing was insufficient.
【００１９】またさらに、特開平８−２０８４１号公報
においても軸受寿命の評価が不十分であった。つまり、
転がり軸受の寿命にはクリーンな潤滑条件以外にも潤滑
剤に異物が混入したりして潤滑が不十分な場合を考慮す
る必要がある。本発明者等の市場調査では油俗潤滑条件
で使用されている並径以下の軸受の場合、そのほとんど
が潤滑油中に含まれる異物の噛み込みや潤滑不良による
軸受内での表面接触による表面起点タイプの疲労状況を
示していた。Furthermore, Japanese Patent Application Laid-Open No. 8-20841 also failed to sufficiently evaluate the bearing life. That is,
In addition to the clean lubrication conditions, it is necessary to consider the case where the lubrication is insufficient due to foreign matter entering the lubricant in addition to the clean lubrication conditions. According to the market research conducted by the inventors of the present invention, in the case of a bearing having a diameter equal to or less than that used in oily lubrication conditions, most of the surface contact due to foreign matter contained in the lubricating oil and surface contact in the bearing due to poor lubrication. It showed the starting type of fatigue.
【００２０】また、特にオートマチックトランスミッシ
ョン内ではその構造上、軸受への潤滑経路が複雑であ
り、十分に潤滑剤が供給されない場合があり、転がり軸
受は厳しい潤滑状態で使用される場合が多い。このた
め、軸受の転動接触部の油膜形成が不十分となり、転走
面にピーリング損傷や滑り摩耗が発生し、早期剥離や異
常振動等の不具合が発生してしまうことになる。In addition, especially in an automatic transmission, the lubrication path to the bearing is complicated due to its structure, the lubricant may not be supplied sufficiently, and the rolling bearing is often used under severe lubrication. For this reason, the formation of an oil film at the rolling contact portion of the bearing becomes insufficient, and peeling damage and sliding wear occur on the rolling surface, causing problems such as early peeling and abnormal vibration.
【００２１】さらに、一般的にはクリーン潤滑であると
考えられていたグリース潤滑条件でも、市場の使用状況
を詳しく調査すると表面起点タイプの疲労状況を示す場
合が多い。したがって、単に高荷重で転動疲労寿命を評
価するだけでなく、転がり軸受用の材料として必要な寿
命評価を行わなければならない。Further, even under grease lubrication conditions, which were generally considered to be clean lubrication, a detailed investigation of the conditions of use in the market often shows a surface starting type fatigue state. Therefore, it is necessary to evaluate not only the rolling fatigue life under a high load but also the life required as a material for a rolling bearing.
【００２２】一方、特開平２−２２４５１号公報や特開
平２−１２２０６２号公報に示すような一般的なプロパ
ン等の飽和炭化水素ガスを使用した真空浸炭や、特開平
６−１７２９６０号公報に示すようなプロパン等の飽和
炭化水素ガスと空気を混合する真空浸炭では、浸炭時の
炭素ポテンシャルの調整が困難で煤が過剰に発生してし
まう（村上弘二：「熱処理」第１７巻５号１９７７．１
０，Ｐ．２９８参照）。On the other hand, vacuum carburization using a saturated hydrocarbon gas such as general propane as disclosed in JP-A-2-22451 and JP-A-2-122620, and JP-A-6-172960. In the case of vacuum carburization in which a saturated hydrocarbon gas such as propane or the like is mixed with air, it is difficult to adjust the carbon potential during carburization and excessive soot is generated (Koji Murakami: "Heat Treatment" Vol. 17, No. 5, No. 1, 1977. 1
0, P. 298).
【００２３】本発明者等の実際の操業でも、煤が多量に
発生したり、浸炭濃度や浸炭深さのばらつきが多く、場
合によっては浸炭むらが発生していた。Even in the actual operation of the present inventors, a large amount of soot was generated, the carburizing concentration and the carburizing depth varied widely, and in some cases, uneven carburizing occurred.
【００２４】これに対し、特開平８−３２５７０１号公
報に示すような不飽和炭化水素ガスの１つであるアセチ
レンを使用した高真空での真空浸炭では、煤の発生もな
く、高い効率で高品質の処理が可能であり、穴の中も深
く均一に浸炭することが可能である。しかし、この真空
浸炭における材料との組合せによる効果や軸受機能への
影響等の調査までは行っていなかった。On the other hand, vacuum carburization in a high vacuum using acetylene, which is one of the unsaturated hydrocarbon gases, as disclosed in JP-A-8-325701, does not generate soot and has high efficiency and high efficiency. High quality treatment is possible, and it is possible to carburize deep and uniformly in the holes. However, no investigation has been made on the effects of the combination with materials in vacuum vacuum carburization or the effects on bearing functions.
【００２５】そこで、本発明は、素材を黒鉛化すること
で被削性を著しく向上させると共に、高真空で短時間の
浸炭を行うことで低コストでありながら、クリーン潤滑
や異物混入潤滑下で、さらにはピーリング損傷や滑り摩
耗に対して長寿命である転がり軸受を提供することを目
的とする。Therefore, the present invention significantly improves machinability by graphitizing a material, and performs low-cost carburizing by performing high-vacuum and short-time carburizing while maintaining clean lubrication and lubrication under contaminant contamination. Another object of the present invention is to provide a rolling bearing having a long service life against peeling damage and sliding wear.
【００２６】また一方、トロイダル形無段変速機に使用
される転動部材において、前述した浸炭または浸炭窒化
を行う場合、一般的にガス浸炭または浸炭窒化法が行わ
れており、この方法によって入出力ディスクやパワーロ
ーラ軸受の表面に圧縮応力を生じさせることができるも
のの、これらは高面圧環境下で使用されるので、深い硬
化層が必要となり、長時間の浸炭または浸炭窒化時間を
要することとなる。On the other hand, when the above-described carburizing or carbonitriding is performed on a rolling member used in a toroidal type continuously variable transmission, a gas carburizing or carbonitriding method is generally performed. Although it can generate compressive stress on the surface of the output disk and power roller bearings, they are used in a high surface pressure environment, so a deep hardened layer is required, and a long carburizing or carbonitriding time is required. Becomes
【００２７】さらに、浸炭性または浸炭窒化性ガスに長
時間さらされるため、これら入出力ディスク、パワーロ
ーラ軸受の表面に発生する割れの起点となり得る表面異
常層（粒界酸化層）が深くなってしまうという問題があ
った。Further, because of being exposed to a carburizing or carbonitriding gas for a long time, an abnormal surface layer (grain boundary oxide layer) which may be a starting point of cracks generated on the surface of these input / output disks and power roller bearings becomes deep. There was a problem that it would.
【００２８】また、ショットピーニングを行う方法で
は、ショットピーニングによって表面に大きな圧縮応力
が発生するため、粒界酸化の改善は図れるものの、表層
部、特に表面近傍にはマイクロクラックと称する微視亀
裂が発生することがあり、このマイクロクラックに繰り
返し応力が加わることで割れが発生するという新たな問
題があった。このため、ショットピーニングの後、粒界
酸化の除去の場合と同様に、表層部を研削してマイクロ
クラックを除去する工程が必要となり、ショットピーニ
ング工程を含めた全工程のコストアップとなってしま
う。In the method of performing shot peening, since a large compressive stress is generated on the surface by shot peening, grain boundary oxidation can be improved, but microcracks called microcracks are formed in the surface layer, especially near the surface. There is a new problem that cracks may occur when stress is repeatedly applied to the microcracks. For this reason, after the shot peening, as in the case of removing the grain boundary oxidation, a step of grinding the surface layer to remove micro cracks is required, which increases the cost of all the steps including the shot peening step. .
【００２９】本発明は、トロイダル形無段変速機の入力
ディスク、出力ディスクおよびパワーローラ軸受に剥
離、破損が発生することを防止すると共に、疲労割れを
防止し、高寿命で高い信頼性を得ることができる転動部
材を提供することを他の目的とする。The present invention prevents the input disk, the output disk, and the power roller bearing of the toroidal type continuously variable transmission from peeling and breaking, prevents fatigue cracking, and obtains a long life and high reliability. Another object of the present invention is to provide a rolling member that can be used.
【００３０】[0030]
【課題を解決するための手段】上記目的を達成するため
に、本発明者等は表面の黒鉛の粒径や面積率、表面層の
炭素および窒素の含有量に基づいて各種の寿命評価を行
い、高温かつ短時間の真空浸炭により黒鉛の粒径や面積
率を自在に調整することで本発明を成すに至った。In order to achieve the above object, the present inventors conducted various life evaluations based on the particle size and area ratio of graphite on the surface and the contents of carbon and nitrogen in the surface layer. The present invention has been accomplished by freely adjusting the particle size and area ratio of graphite by vacuum carburizing at a high temperature for a short time.
【００３１】かかる本発明の請求項１に記載の転がり軸
受は、内輪、外輪および転動体の少なくとも１つに浸炭
または浸炭窒化処理を行った素材が適用される転がり軸
受において、前記素材は、炭素０．４５〜０．９重量
％、シリコン０．５〜１．５重量％、マンガン０．３〜
１．５重量％およびクロム０．７重量％以下を含有し、
残りが鉄および不純物元素からなる合金であり、前記素
材に対して黒鉛化処理を行って微細黒鉛を析出させてお
き、完成品表面における黒鉛の面積率を５％以下とし、
平均粒径５μｍ以上の大形黒鉛粒が全黒鉛に対して面積
率で２％以下であり、かつ平均粒径２μｍ以下の微細黒
鉛粒が全黒鉛に対して面積率で５０％以上であり、完成
品表面層における炭素量および窒素量がそれぞれ０．９
〜１．４重量％および０．０１〜０．３重量％であるこ
とを特徴とする。The rolling bearing according to the first aspect of the present invention is a rolling bearing in which at least one of the inner ring, the outer ring, and the rolling element is made of a material subjected to a carburizing or carbonitriding process. 0.45-0.9% by weight, silicon 0.5-1.5% by weight, manganese 0.3-
1.5% by weight and not more than 0.7% by weight of chromium,
The remainder is an alloy consisting of iron and impurity elements, the material is subjected to a graphitization process to precipitate fine graphite, and the area ratio of graphite on the finished product surface is set to 5% or less,
Large graphite particles having an average particle size of 5 μm or more have an area ratio of 2% or less with respect to the total graphite, and fine graphite particles having an average particle size of 2 μm or less have an area ratio of 50% or more with respect to the total graphite, The carbon content and nitrogen content in the finished product surface layer are 0.9
To 1.4% by weight and 0.01 to 0.3% by weight.
【００３２】また、前記完成品表面における黒鉛の面積
率は３％以下であることがより好ましく、表面の硬さが
ＨＶ７００未満になることを防止する。Further, the area ratio of graphite on the surface of the finished product is more preferably 3% or less, and the hardness of the surface is prevented from being less than HV700.
【００３３】さらに、前記平均粒径２μｍ以下の微細黒
鉛粒は全黒鉛に対して面積率で７０％以上であることが
より好ましく、ピーリングタイプの寿命の低下を防ぐ。Further, the fine graphite particles having an average particle size of 2 μm or less are more preferably 70% or more in area ratio with respect to the total graphite, thereby preventing the life of the peeling type from being shortened.
【００３４】また、完成品表面層における窒素量は０．
０５〜０．２重量％であることがより好ましく、耐摩耗
性を向上し、研削性の低下を防止する。The amount of nitrogen in the surface layer of the finished product is 0.1.
It is more preferably from 0.5 to 0.2% by weight, which improves wear resistance and prevents a decrease in grindability.
【００３５】またさらに、不飽和炭化水素ガスの１つで
あるアセチレンを使用して、５Ｔｏｒｒ以下の高真空で
真空浸炭を行うことが好ましく、煤の発生が少なく、安
定した品質が得られる。Further, it is preferable to carry out vacuum carburization at a high vacuum of 5 Torr or less using acetylene which is one of unsaturated hydrocarbon gases, so that the generation of soot is small and stable quality is obtained.
【００３６】さらに、１Ｔｏｒｒ以下の高真空で浸炭を
行うことが好ましく、高真空である方が浸炭が安定する
傾向にある。Further, it is preferable to carry out carburizing at a high vacuum of 1 Torr or less. Carburizing tends to be more stable at a higher vacuum.
【００３７】また、浸炭温度は９５０℃を越えることが
好ましく、黒鉛の微細化を促進すると共にその面積を半
分以下にすることができる。The carburizing temperature is preferably higher than 950 ° C., which can promote the miniaturization of graphite and reduce the area thereof to half or less.
【００３８】さらに、素材の黒鉛面積率を１０％以上と
することが好ましく、冷間鍛造（加工）性を良好にする
ことができる。Further, the graphite area ratio of the raw material is preferably set to 10% or more, so that the cold forgeability (workability) can be improved.
【００３９】また、完成品の黒鉛面積率が２％以上４％
以下であることが好ましく、オートマチックトランスミ
ッション内で使用されている等、潤滑条件の厳しい場合
に微細な残留黒鉛粒が油溜まりとなり、潤滑条件が厳し
い中で潤滑を助ける効果を有する。The graphite area ratio of the finished product is 2% or more and 4% or more.
When the lubrication conditions are severe, such as when used in an automatic transmission, fine residual graphite particles become oil pools, and have an effect of assisting lubrication under severe lubrication conditions.
【００４０】また一方、本発明の転動部材は、入力軸に
設けられた入力ディスクと、出力軸に設けられた出力デ
ィスクと、前記入力ディスクおよび前記出力ディスクと
係合して前記入力軸の動力を前記出力軸に伝達するパワ
ーローラ軸受とを有するトロイダル形無段変速機におい
て、前記入力ディスク、前記出力ディスクおよび前記パ
ワーローラ軸受の少なくとも１つに使用される転動部材
は、炭素０．１５〜０．６５重量％を含む鋼合金を素材
とし、真空浸炭または真空浸炭窒化処理を行った後、研
削仕上げが施されたことを特徴とする。On the other hand, the rolling member of the present invention comprises an input disk provided on the input shaft, an output disk provided on the output shaft, and the input disk and the output disk engaged with the input disk. In a toroidal-type continuously variable transmission having a power roller bearing for transmitting power to the output shaft, a rolling member used for at least one of the input disk, the output disk, and the power roller bearing may have carbon. It is characterized in that a steel alloy containing 15 to 0.65% by weight is used as a raw material, and is subjected to vacuum carburizing or vacuum carbonitriding treatment, followed by grinding.
【００４１】また、トロイダル形無段変速機では、パワ
ーローラ軸受の構成要素である内輪および外輪、入力デ
ィスク、出力ディスクの転走面の表層部にそれぞれ２０
〜１５０Ｋｇｆ／ｍｍ2 の圧縮残留応力を発生させるこ
とが好ましい。Further, in the toroidal type continuously variable transmission, each of the inner race and the outer race, which are the components of the power roller bearing, the input disk and the output disk, is provided on the surface layer of the rolling surface.
It is preferred to generate a compressive residual stress of ~150Kgf / mm 2.
【００４２】さらに、真空浸炭処理では、９００℃〜１
０５０℃の温度領域で５Ｔｏｒｒ以下の炉内圧力にアセ
チレンを添加して浸炭を行うことが好ましい。Further, in the vacuum carburizing treatment, 900 ° C. to 1
It is preferable to carry out carburization by adding acetylene to a furnace pressure of 5 Torr or less in a temperature range of 050 ° C.
【００４３】また、真空浸炭窒化処理では、真空浸炭後
にアンモニア等の窒化性ガスを添加して浸炭窒化を行う
ことが好ましい。In the vacuum carbonitriding treatment, it is preferable to perform carbonitriding by adding a nitriding gas such as ammonia after vacuum carburizing.
【００４４】このようなトロイダル形無段変速機では、
熱処理方法として従来行ってきたガス浸炭およびガス浸
炭窒化を真空浸炭および真空浸炭窒化とすることで、表
面異常層（粒界酸化層）を生じさせないことから、パワ
ーローラ軸受、入力ディスクおよび出力ディスクの剥
離、破損の発生が防止されると共に、疲労割れが防止さ
れ、低コストで信頼性が高くなる。In such a toroidal type continuously variable transmission,
As a conventional heat treatment method, vacuum carburizing and vacuum carbonitriding of gas carburizing and gas carbonitriding do not cause an abnormal surface layer (grain boundary oxide layer). In addition to preventing peeling and breakage, fatigue cracking is prevented, and reliability is increased at low cost.
【００４５】これは以下に示す理由による。This is for the following reason.
【００４６】従来、行われてきたガス浸炭法およびガス
浸炭窒化法では、浸炭または浸炭窒化、および焼入れ硬
化処理時に使用される吸熱型雰囲気ガス（ＲＸガス）に
は微量のＣＯ2、Ｈ2Ｏが含まれている。このため、鋼材
表面層では、これらと鋼中のＳｉやＭｎ、Ｃｒとが反応
して表面異常層（粒界酸化層）が生じることが従来から
知られている。In the conventional gas carburizing method and gas carbonitriding method, trace amounts of CO 2 and H 2 O are contained in the endothermic atmosphere gas (RX gas) used during carburizing or carbonitriding and quenching and hardening. It is included. For this reason, it has been conventionally known that in the steel material surface layer, these react with Si, Mn, and Cr in the steel to form an abnormal surface layer (grain boundary oxide layer).
【００４７】このため、入出力ディスクやパワーローラ
軸受ではこれらを起点とする剥離や、応力集中により耐
疲労割れ寿命が低下してしまうので、粒界酸化層を除去
するための研削工程が必要となる。For this reason, in an input / output disk or a power roller bearing, the fatigue crack life is reduced due to peeling or stress concentration originating from them, so that a grinding step for removing the grain boundary oxide layer is required. Become.
【００４８】図１５の符号「ア」、「イ」の部分はトロ
イダル形無段変速機を駆動した際に最も繰り返し応力が
発生しやすい部分である。また、パワーローラ軸受では
図１５の符号「ウ」の部分がエッジ部であり、同様に応
力集中を受けやすい部分である。これらの部分は軌道面
ではない部分ではあるが、応力集中を避けるために、全
て研削加工が必要であった。The portions indicated by reference numerals "A" and "A" in FIG. 15 are portions where stress is most likely to be generated when the toroidal type continuously variable transmission is driven. Further, in the power roller bearing, a portion indicated by a symbol “U” in FIG. 15 is an edge portion, and is a portion that is similarly susceptible to stress concentration. Although these portions are not the raceway surfaces, all of them required grinding to avoid stress concentration.
【００４９】また、これらの入出力ディスクやパワーロ
ーラ軸受にショットピーニングを行うと、鋼材の表面近
傍が塑性変形して残留圧縮応力が生成することにより、
繰り返し曲げ応力等に伴う高い引っ張り応力に抗するの
で、耐疲労割れ特性を向上できる。When shot peening is performed on these input / output disks and power roller bearings, the vicinity of the surface of the steel material is plastically deformed and residual compressive stress is generated.
Since it resists high tensile stress caused by repeated bending stress and the like, fatigue crack resistance can be improved.
【００５０】しかしながら、この塑性変形部は局部疲労
を受けているため、その表層部に５〜１０μｍのマイク
ロクラックと称する微視亀裂が発生することもあり、こ
のマイクロクラックの周りに繰り返し応力が付与されて
割れが進展することもある。また、ショットピーニング
のままでは、鋼材表面に凹凸を生じさせ、この部分の応
力集中により、ここを起点として割れが生じる場合もあ
る。このため、耐疲労寿命向上のため、別途研削を行う
必要があった。However, since the plastically deformed portion has been subjected to local fatigue, a microcrack called a microcrack of 5 to 10 μm may be generated in the surface layer portion, and stress is repeatedly applied around the microcrack. In some cases, cracks may develop. Further, if the shot peening is used, irregularities are generated on the surface of the steel material, and cracks may be generated from this point as a starting point due to stress concentration in this portion. For this reason, it was necessary to separately perform grinding in order to improve fatigue life.
【００５１】しかしながら、本発明では、粒界酸化は生
じないことから、追加工程としてショットピーニング加
工を行う必要がなく、軌道面以外の不必要な研削を省略
することができ、コストダウンを図ることができる。However, in the present invention, since grain boundary oxidation does not occur, it is not necessary to perform shot peening as an additional step, unnecessary grinding other than the raceway surface can be omitted, and cost can be reduced. Can be.
【００５２】さらに、入出力ディスクやパワーローラ軸
受に本発明の転動部材を適用することで、表面層部（ケ
ース）と芯部（コア）との炭素濃度および窒素濃度に差
異を持たせることができ、ケースとコアとのマルテンサ
イト変態点をずらし、焼入れ、焼戻し後に入出力ディス
クやパワーローラ軸受の表面層に残留圧縮応力を生じさ
せ、表面の接線方向に生じる引っ張り応力によるマイク
ロ（微小）クラックの発生を抑制することで疲労寿命特
性を向上させることができる。Further, by applying the rolling member of the present invention to an input / output disk or a power roller bearing, the carbon concentration and the nitrogen concentration of the surface layer (case) and the core (core) are made different. After the quenching and tempering, a residual compressive stress is generated in the surface layer of the input / output disk and the power roller bearing, and a micro (micro) due to a tensile stress generated in a tangential direction of the surface. By suppressing the occurrence of cracks, fatigue life characteristics can be improved.
【００５３】さらに、入出力ディスクやパワーローラ軸
受の転走面の表層部に２０Ｋｇｆ／ｍｍ2以上の圧縮残
留応力を発生させることで、より入出力ディスクやパワ
ーローラ軸受の転がり寿命が向上し、一層長寿命なトロ
イダル形無段変速機が得られる。Further, by generating a compressive residual stress of 20 kgf / mm 2 or more on the surface layer of the rolling surface of the input / output disk or power roller bearing, the rolling life of the input / output disk or power roller bearing can be further improved. A toroidal-type continuously variable transmission having a longer life can be obtained.
【００５４】また、入出力ディスクやパワーローラ軸受
材料として、炭素濃度が０．１５重量％未満では、入出
力ディスクやパワーローラ軸受にかかる高面圧に耐えう
る硬化層深さを得るには、長時間の浸炭時間を要するこ
ととなり、生産性が悪化する。一方、０．６５重量％を
越えると、芯部の硬さが高くなり、大きく靭性が低下し
てしまう。このように、入出力ディスクやパワーローラ
軸受の材料としては、２０Ｋｇｆ／ｍｍ2以上の残留圧
縮応力を得るために、浸炭鋼あるいは中炭素鋼からな
り、炭素濃度Ｃは０．１５重量％以上０．６５重量％以
下であることが好ましい。If the carbon concentration of the input / output disk or power roller bearing material is less than 0.15% by weight, a hardened layer depth that can withstand the high surface pressure applied to the input / output disk or power roller bearing must be obtained. A long carburizing time is required, and productivity is deteriorated. On the other hand, when the content exceeds 0.65% by weight, the hardness of the core increases, and the toughness is greatly reduced. As described above, in order to obtain a residual compressive stress of 20 kgf / mm 2 or more, the material of the input / output disk and the power roller bearing is made of carburized steel or medium carbon steel, and the carbon concentration C is 0.15% by weight or more. It is preferably at most 0.65% by weight.
【００５５】真空浸炭法は減圧下の加熱室にワークを入
れ、その炉内に浸炭性のガスを直接添加して浸炭を行う
方法であるが、浸炭性ガスとしてプロパンやブタンが従
来から用いられていたが、浸炭に寄与しないガスが煤と
なって堆積し、治具寿命を低下させたり、ワークに付着
した場合、浸炭むらが発生して問題があった。The vacuum carburizing method is a method in which a workpiece is placed in a heating chamber under reduced pressure and carburizing gas is directly added to the furnace to perform carburizing. Propane or butane is conventionally used as a carburizing gas. However, when the gas that does not contribute to carburization is deposited as soot and reduces the life of the jig or adheres to the work, there is a problem that uneven carburization occurs.
【００５６】このため、本発明では、これらの問題を解
決させた９００℃〜１０５０℃の温度領域で５Ｔｏｒｒ
以下の炉内圧力にアセチレンを添加して浸炭を行う方法
が好ましい。５Ｔｏｒｒ以下の炉内圧力下では、アセチ
レンは浸炭性に寄与するだけのワークへの堆積となり、
その他浸炭性に寄与しないガスは炉外に排出されること
となり、浸炭むらが発生せず、治具寿命の向上について
も効果的な方法である。Therefore, according to the present invention, 5 Torr in a temperature range of 900 ° C. to 1050 ° C. in which these problems have been solved.
A method in which acetylene is added to the following furnace pressure to perform carburization is preferable. At a furnace pressure of 5 Torr or less, acetylene is deposited on the work only to contribute to carburization,
Other gases that do not contribute to carburizing properties are discharged outside the furnace, so that carburizing unevenness does not occur, and this is an effective method for improving the jig life.
【００５７】また、本発明では、９００℃〜１０５０℃
と高温での処理が可能であるので、ガス浸炭と比較して
炭素の拡散層が深くなり、短時間での処理が可能であ
る。さらに、真空浸炭方法では真空浸炭後にアンモニア
等の窒化性ガスを添加して浸炭窒化を行うことが好まし
い。Further, in the present invention, 900 ° C. to 1050 ° C.
And a high-temperature treatment are possible, so that the carbon diffusion layer is deeper than in the case of gas carburizing, and the treatment can be performed in a short time. Further, in the vacuum carburizing method, it is preferable to perform carbonitriding by adding a nitriding gas such as ammonia after vacuum carburizing.
【００５８】[0058]
【発明の実施の形態】本発明の転がり軸受の実施の形態
について説明する。始めに、黒鉛鋼自体はかなり以前か
ら公知であるが、近年の黒鉛化処理技術の進歩により黒
鉛化処理時間の短縮や黒鉛粒の微細化が可能となってき
た（太田裕樹等（川崎製鐵）「材料とプロセス」Ｖｏ
ｌ．９，Ｐ４０６，１９９６、岩本隆等（川崎製鐵）
「材料とプロセス」Ｖｏｌ．９，Ｐ４０７，１９９
６）。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the rolling bearing according to the present invention will be described. Initially, graphite steels have been known for quite some time, but recent advances in graphitization technology have made it possible to shorten the graphitization time and reduce the size of graphite particles (Yuki Ota et al. (Kawasaki Steel Corp.) ) "Materials and Process" Vo
l. 9, P406, 1996, Takashi Iwamoto, etc. (Kawasaki Steel)
"Materials and Processes," Vol. 9, P407, 199
6).
【００５９】一方、本発明者等はこれらの黒鉛鋼を転が
り軸受用の材料に用いて種々の熱処理を行った結果、つ
ぎのような知見を得た。On the other hand, the present inventors have conducted various heat treatments using these graphite steels as materials for rolling bearings, and have obtained the following findings.
【００６０】（１）素地の炭化物をほとんど黒鉛化した
黒鉛鋼を通常の並径軸受に適用するずぶ焼入処理（８２
０〜８５０℃焼入）を行ったが、平均粒径で５μｍ以上
の大きな黒鉛粒は消失せず黒鉛のまま素地に残ってしま
う。つまり、黒鉛化した炭素Ｃが焼入処理だけでは十分
に素地に溶け込まず、軸受として必要な硬さが得られな
い。(1) A so-called quenching treatment (82) in which graphite steel in which the base carbide is almost graphitized is applied to a normal-diameter bearing.
(Quenching from 0 to 850 ° C.), but large graphite particles having an average particle size of 5 μm or more do not disappear and remain in the graphite as graphite. That is, the graphitized carbon C does not sufficiently dissolve into the base material only by the quenching treatment, and the hardness required for the bearing cannot be obtained.
【００６１】（２）素地の炭化物の一部を短時間で微細
に黒鉛化した場合でも、平均粒径で５μｍ以上の大きな
黒鉛粒では、通常の焼入処理で炭素Ｃが十分に素地に溶
け込まず、軸受として必要な硬さが得られにくい。さら
に、焼入温度を９００℃まで上げたが、大きな黒鉛粒の
溶込量に大差はなかった。(2) Even when a part of the carbide of the base material is finely graphitized in a short time, in the case of a large graphite particle having an average particle size of 5 μm or more, carbon C sufficiently dissolves into the base material by a normal quenching treatment. And it is difficult to obtain the required hardness as a bearing. Further, although the quenching temperature was increased to 900 ° C., there was no great difference in the penetration amount of large graphite particles.
【００６２】（３）浸炭または浸炭窒化処理を行った場
合、素地に炭素Ｃや窒素Ｎを侵入させることができ、焼
入後に十分な硬さが得られると共に、通常の浸炭の場
合、処理温度が９３０〜９６０℃と高いので、黒鉛粒が
小さくなる傾向を示した。(3) In the case of carburizing or carbonitriding, carbon C and nitrogen N can be made to penetrate into the substrate, and sufficient hardness can be obtained after quenching. Was as high as 930 to 960 ° C., and the graphite particles tended to be small.
【００６３】このように、黒鉛鋼に対して従来の軸受鋼
の焼入処理を行った場合、軸受としての十分な硬さが得
られにくい。また、黒鉛化により減少する炭素Ｃの量を
見越して素材の炭素Ｃの含有量を上げると、加工性が低
下したり、製鋼時に巨大炭化物が出現するおそれがあ
り、焼入後の心部靭性低下も懸念される。As described above, when the conventional hardening treatment of the bearing steel is performed on the graphite steel, it is difficult to obtain sufficient hardness as the bearing. Also, if the carbon C content of the material is increased in anticipation of the amount of carbon C that is reduced by graphitization, workability may decrease, or a large carbide may appear during steelmaking, and the core toughness after quenching. There is also concern about the decline.
【００６４】また、焼入温度を高くして黒鉛の溶込み量
を上げようとしても、その効果は小さく、浸炭処理温度
まで焼入温度を上げると、オーステナイト粒が粗大化
し、焼入後の表面組織も粗大化してしまうので、寿命や
強度が低下してしまう。つまり、黒鉛鋼に対しては通
常、軸受鋼で行っている焼入処理では軸受に十分な組織
や硬さが得られにくく、軸受として使用するためには浸
炭または浸炭窒化処理が不可欠である。Further, even if the quenching temperature is increased to increase the amount of graphite penetration, the effect is small. If the quenching temperature is increased to the carburizing temperature, the austenite grains are coarsened and the surface after quenching is increased. Since the structure is also coarsened, the life and strength are reduced. That is, it is difficult to obtain sufficient structure and hardness of the bearing by the quenching treatment usually performed on the graphite steel for the bearing steel, and the carburizing or carbonitriding treatment is indispensable for use as the bearing.
【００６５】さらに、黒鉛粒を微細に調整するために
は、長時間の処理や浸炭処理温度を高くしなければなら
ない。しかし、長い処理時間は処理コストの増加を招
き、また条件にもよるが、表面に初期セメンタイトが析
出しやすく、軸受寿命を低下させる。また、浸炭処理温
度を単純に高くすると、粒界酸化の発生が著しく、場合
によっては酸化膜が部分的に発生する。粒界酸化や酸化
膜は浸炭時に表面の炭素Ｃ濃度％を低下させたり、炭素
Ｃの拡散を阻害するので、浸炭深さが減少する傾向とな
る。また、通常のガス浸炭では１０００℃以上になる
と、熱損失によるヒータ容量の増大など設備の耐久性を
含め、ほとんど実用化することができない。Further, in order to finely adjust the graphite particles, a long-time treatment or a carburizing treatment temperature must be increased. However, a long treatment time leads to an increase in treatment cost and, depending on conditions, initial cementite is likely to precipitate on the surface, which shortens the bearing life. Further, when the carburizing temperature is simply increased, grain boundary oxidation is remarkably generated, and in some cases, an oxide film is partially generated. Grain boundary oxidation or an oxide film lowers the carbon C concentration% on the surface during carburization or inhibits the diffusion of carbon C, so that the carburization depth tends to decrease. Further, if the temperature exceeds 1000 ° C. in normal gas carburization, practical use of the gas cannot be practically achieved, including the durability of equipment such as an increase in heater capacity due to heat loss.
【００６６】そこで、高温で高真空な浸炭を黒鉛鋼に対
して施すことにより、黒鉛粒を微細に調整すると同時
に、短時間で必要な浸炭深さが得られるようにする。Therefore, by subjecting the graphite steel to high-temperature and high-vacuum carburization, the graphite grains can be finely adjusted, and at the same time, the required carburizing depth can be obtained in a short time.
【００６７】つぎに、素材の黒鉛量と被削性について調
査を行った結果を示す。図１は素材の黒鉛面積率と切削
工具寿命との関係を示す特性図である。少しでも黒鉛が
析出すれば、切削性が改善されることがわかった。つま
り、素材段階で若干の黒鉛析出があれば切削性は大幅に
改善できるのである。Next, the results of investigations on the graphite content and machinability of the raw material are shown. FIG. 1 is a characteristic diagram showing the relationship between the graphite area ratio of the material and the life of the cutting tool. It was found that even if a little graphite was precipitated, the machinability was improved. That is, if there is some graphite precipitation at the material stage, the machinability can be greatly improved.
【００６８】一方、市場での並径以下の軸受の使用状況
を考慮して表面起点タイプの損傷を再現するために、黒
鉛鋼に浸炭焼入処理したものの異物混入潤滑下で寿命評
価を行った結果を示す。図２は全黒鉛に対する５μｍ以
上の黒鉛の面積率と寿命との関係を示す特性図である。On the other hand, in order to reproduce the damage of the surface starting type in consideration of the use condition of bearings having a diameter equal to or less than that in the market, the life was evaluated under the lubrication mixed with foreign matter, which was obtained by carburizing and quenching graphite steel. The results are shown. FIG. 2 is a characteristic diagram showing the relationship between the area ratio of graphite of 5 μm or more to the total graphite and the life.
【００６９】軸受の完成品表面に５μｍ以上の大形黒鉛
が多くなると、寿命が低下することが分かった。短寿命
で破損した試験片を調査すると、５μｍ以上の黒鉛粒か
らクラックが発生し、クラック同士がつながって大きな
クラックとなり、これを起点としてはく離が発生してい
た。クリーン潤滑下の条件であっても、黒鉛粒が大きい
と黒鉛粒から発生したクラックを起点に短寿命ではく離
が発生することを確認した。It has been found that when the size of large graphite of 5 μm or more increases on the surface of the finished product of the bearing, the life is shortened. Examination of the short-life damaged test piece revealed that cracks were generated from graphite particles of 5 μm or more, the cracks were connected to each other to form a large crack, and peeling occurred from this as a starting point. It was confirmed that even under the condition of clean lubrication, if the graphite particles were large, flaking occurred in a short life from cracks generated from the graphite particles.
【００７０】このように、黒鉛鋼を軸受用鋼として使用
するために種々の実験を行った結果、並径以下の軸受で
行っている比較的短時間の熱処理では黒鉛鋼の黒鉛粒を
完全に溶け込ませることは不可能であることが分かっ
た。As described above, various experiments were conducted to use graphite steel as a bearing steel. As a result, it was found that the graphite grains of the graphite steel were completely removed by a relatively short-time heat treatment performed on a bearing having a diameter equal to or less than that. It turned out that it was not possible to blend in.
【００７１】したがって、ずぶ焼入処理では軸受として
の適用は困難であり、浸炭または浸炭窒化処理による炭
素Ｃ、窒素Ｎの付加が不可欠である。また、完成品表面
に大きな黒鉛粒を残すと、軸受としての適用は困難であ
り、黒鉛鋼を軸受用鋼として使用するためには、完成品
表面の黒鉛分布を必ず管理しなくてはならない。そし
て、黒鉛分布を精度良く、また短時間で効率よく管理す
るためには、高温で高真空な浸炭を行うことが好まし
い。Therefore, it is difficult to apply as a bearing in the soaking quenching process, and it is essential to add carbon C and nitrogen N by carburizing or carbonitriding. In addition, if large graphite particles are left on the surface of the finished product, it is difficult to apply it as a bearing. In order to use graphite steel as bearing steel, the distribution of graphite on the surface of the finished product must be controlled. In order to accurately and efficiently manage the graphite distribution in a short time, it is preferable to carry out carburization at high temperature and high vacuum.
【００７２】つぎに、軸受材料の合金成分の作用および
成分範囲の限定理由について説明する。Next, the action of the alloy components of the bearing material and the reasons for limiting the component ranges will be described.
【００７３】［炭素Ｃ：含有量］炭素Ｃは黒鉛鋼として
不可欠であり、素地をマルテンサイト化して軸受として
の硬さを得るための重要な元素である。浸炭や浸炭窒化
処理を行うことで、完成品表面層に適量の炭素Ｃや窒素
Ｎを得ることができるが、浸炭や浸炭窒化時間が増加す
ると製造コストが高くなるので、短時間の浸炭や浸炭窒
化で寿命に十分な硬さと硬化層深さが得られるように素
材の炭素量の下限を０．４５重量％とした。[Carbon C: Content] Carbon C is indispensable as graphite steel, and is an important element for converting the base material into martensite to obtain hardness as a bearing. By performing carburizing or carbonitriding treatment, an appropriate amount of carbon C or nitrogen N can be obtained on the surface layer of the finished product, but if the carburizing or carbonitriding time increases, the production cost increases. The lower limit of the carbon content of the material was set to 0.45% by weight so that the hardness and the hardened layer depth sufficient for the life could be obtained by nitriding.
【００７４】しかし、素材の炭素Ｃが０．９重量％以上
になると、加工性が低下したり、製鋼時に巨大炭化物や
偏析をなくすソーキングが必要となる。このような理由
から素材の炭素量は０．４５重量％〜０．９重量％とす
る。ただし、特に寿命と熱処理コストを厳密に考慮する
場合、短時間の熱処理でも十分な長寿命を得るために素
材の炭素量は０．７重量％以上であることが望ましい。However, when the carbon content of the raw material is 0.9% by weight or more, workability is deteriorated and soaking for eliminating giant carbide and segregation at the time of steel making is required. For these reasons, the carbon content of the material is set to 0.45% by weight to 0.9% by weight. However, when strictly considering the life and the heat treatment cost, the carbon content of the material is desirably 0.7% by weight or more in order to obtain a sufficient long life even with a short heat treatment.
【００７５】［シリコンＳｉ：含有量］素材の製鋼時に
脱酸剤として作用し、焼入性を向上させるとともに基地
マルテンサイトを強化し、軸受の寿命を延長するために
有効な元素である。また、鋼中のセメンタイトを不安定
にして黒鉛を促進さるために不可欠であり、その効果を
十分に出すためには最低０．５重量％は必要である。[Silicon Si: content] It is an element that acts as a deoxidizing agent during steelmaking of the material, improves hardenability, strengthens base martensite, and extends the life of the bearing. In addition, it is indispensable for destabilizing cementite in steel to promote graphite, and at least 0.5% by weight is necessary for achieving its effect sufficiently.
【００７６】しかし、Ｓｉ含有量が多くなると浸炭や浸
炭窒化処理の拡散層深さを低下させる傾向があり、通常
の鋼では０．５〜０．７％を越えるとその傾向が顕著に
なってくる。しかし、黒鉛化によってマトリックスのシ
リコンＳｉが低減するので、シリコンＳｉの上限を１．
５重量％以下とした。このような理由から素材のシリコ
ンＳｉ量は０．５重量％〜１．５重量％とする。However, as the Si content increases, the diffusion layer depth in carburizing or carbonitriding tends to decrease, and in ordinary steel, the tendency becomes remarkable when it exceeds 0.5 to 0.7%. come. However, since the graphitization reduces the silicon Si in the matrix, the upper limit of silicon Si is set to 1.
The content was 5% by weight or less. For this reason, the silicon Si content of the material is set to 0.5% by weight to 1.5% by weight.
【００７７】ただし、浸炭窒化処理を行う場合、シリコ
ンＳｉは窒素の拡散を阻害し、拡散層深さを低下させる
上に熱処理後の表面に窒素が濃化してしまい、結果とし
てその後の研削加工を著しく阻害する。黒鉛化によって
マトリックスのシリコンＳｉは低減するが、浸炭窒化処
理を行う場合、シリコンＳｉ含有量は１．０重量％以下
が望ましい。However, when carbonitriding is performed, silicon Si inhibits the diffusion of nitrogen, lowers the depth of the diffusion layer, and enriches the surface with nitrogen after heat treatment. Significantly inhibits. Although graphitization reduces silicon Si in the matrix, when carbonitriding is performed, the silicon Si content is desirably 1.0% by weight or less.
【００７８】［マンガンＭｎ：含有量］一般に焼入性を
向上させるためにはマンガンＭｎあるいはクロムＣｒを
添加するが、クロムＣｒは炭化物生成元素であるので、
添加したクロムＣｒすべてが基地の焼入性向上に機能せ
ず、またコストもマンガンＭｎの方が安い。熱処理で黒
鉛が全て溶け込まず焼入性が低下する場合があり、また
異物混入潤滑下での転がり寿命に有効な残留オーステナ
イト生成元素でもあるので、マンガンＭｎの含有量を最
低０．３重量％とする。[Manganese Mn: Content] In general, manganese Mn or chromium Cr is added to improve hardenability. However, since chromium Cr is a carbide-forming element,
All of the added chromium Cr does not function to improve the hardenability of the matrix, and the cost of manganese Mn is lower. The graphite may not be completely melted by the heat treatment and the hardenability may be reduced. In addition, since it is also a retained austenite forming element effective for rolling life under lubrication with contaminants, the content of manganese Mn should be at least 0.3% by weight. I do.
【００７９】しかし、マンガンＭｎを１．５重量％越え
て添加しても、その効果が飽和に達し、添加効果が上が
らないばかりか、マンガンＭｎはセメンタイトを安定さ
せる元素でもあり、黒鉛化処理時間が極端に長くなって
しまい、微量の黒鉛を析出させるためにも素材がコスト
アップしてしまう。この理由から素材のマンガンＭｎ量
は０．３重量％〜１．５重量％とする。ただし、素材の
黒鉛化をより短時間で行うために、マンガンＭｎ量は
１．０重量％以下であることが望ましい。However, even if manganese Mn is added in an amount exceeding 1.5% by weight, the effect reaches saturation and the effect of addition does not increase, and manganese Mn is also an element that stabilizes cementite. Becomes extremely long, and the cost of the material increases even in order to deposit a trace amount of graphite. For this reason, the manganese Mn content of the material is set to 0.3% by weight to 1.5% by weight. However, in order to graphitize the material in a shorter time, the amount of manganese Mn is desirably 1.0% by weight or less.
【００８０】［クロムＣｒ：含有量］クロムＣｒは焼入
性向上、焼戻軟化抵抗性向上など基地を強化する元素で
あり、軸受用の材料としては不可欠であるが、クロムＣ
ｒは特にセメンタイトを安定させる元素であり、添加量
によっては極端に黒鉛が析出しにくい。また、素材の炭
素量が多い場合、クロムＣｒ量が０．７重量％を越える
と、製鋼過程で巨大炭化物や偏析の生成を改良するため
にソーキングが必要となり、クロムＣｒの添加コストと
共に素材コストが上昇してしまう。[Chromium Cr: Content] Chromium Cr is an element that strengthens the matrix, such as improving hardenability and tempering softening resistance, and is indispensable as a material for bearings.
r is an element particularly stabilizing cementite, and graphite is extremely difficult to precipitate depending on the amount of addition. If the amount of carbon in the material is large, and if the amount of chromium exceeds 0.7% by weight, soaking is required to improve the formation of large carbides and segregation in the steelmaking process. Will rise.
【００８１】したがって、素材のクロムＣｒ量は０．７
重量％以下とする。黒鉛化処理時間の短縮や微量の黒鉛
を析出させるために、特にクロムＣｒ量は０．３重量％
以下であることが望ましい。Therefore, the chromium content of the material is 0.7
% By weight or less. In order to shorten the graphitization time and to precipitate a small amount of graphite, the chromium content is particularly 0.3% by weight.
It is desirable that:
【００８２】［残部Ｆｅおよび不可避不純物元素］黒鉛
の析出は黒鉛発生核の数によって処理時間や微細化が決
まってくる。核の数が多いほど黒鉛が微細化し、処理時
間も短縮できる。黒鉛発生核としてはボロン核ＢＮやア
ルミニウム核ＡｌＮなどがあり、ボロンＢやアルミニウ
ムＡｌの微量添加が有効であり、その他にもランタンＬ
ａやセリウムＣｅの添加も有効である。[Remainder Fe and inevitable impurity elements] The processing time and miniaturization of graphite deposition are determined by the number of graphite generating nuclei. The larger the number of nuclei, the finer the graphite, and the shorter the processing time. Examples of graphite generating nuclei include boron nuclei BN and aluminum nuclei AlN, and the addition of a small amount of boron B or aluminum Al is effective.
The addition of a or cerium Ce is also effective.
【００８３】通常の軸受用鋼では熱処理後の結晶粒微細
化のために、アルミニウムＡｌの微量添加は必然的に行
われているので、黒鉛鋼においても軸受として使用する
場合、結晶粒調整のために０．０５重量％以下のアルミ
ニウムＡｌを添加する。さらなる黒鉛粒の微細化や黒鉛
処理時間の短縮を考えると、不純物元素としてボロンＢ
を０．００２重量％以下、ランタンＬａを０．０５重量
％以下、セリウムＣｅを０．０５重量％以下で少なくと
も１種以上添加することが望ましい。In ordinary bearing steel, a small amount of aluminum Al is inevitably added to refine the crystal grains after heat treatment. Therefore, when graphite steel is used as a bearing, it is necessary to adjust the crystal grains. Of aluminum Al in an amount of 0.05% by weight or less. Considering further miniaturization of graphite particles and shortening of graphite processing time, boron B is considered as an impurity element.
Of 0.002% by weight or less, 0.05% by weight or less of lanthanum La and 0.05% by weight or less of cerium Ce.
【００８４】［完成品表面の黒鉛の面積率を５％以下］
黒鉛は硬さが低いので、微細に析出させても、硬化熱処
理後に残留する黒鉛により硬さが低下してしまう。図３
は完成品表面の黒鉛の面積率と硬さとの関係を示す特性
図である。硬さはビッカースで測定し、測定荷重は１ｋ
ｇで行う。黒鉛面積率が高くなると、図４に示すように
黒鉛粒の上にビッカース圧痕が重なり硬さが低下してし
まう。図４は黒鉛粒の上にビッカース圧痕が重なった様
子を示す図である。さらに、黒鉛面積率が高くなると、
素地に固溶する炭素Ｃが低下してしまい硬さが低下す
る。[Area ratio of graphite on finished product surface is 5% or less]
Since graphite has a low hardness, even if it is finely precipitated, the hardness is reduced by graphite remaining after the curing heat treatment. FIG.
FIG. 4 is a characteristic diagram showing a relationship between graphite area ratio and hardness on the surface of a finished product. Hardness is measured by Vickers, measured load is 1k
g. When the graphite area ratio is increased, Vickers indentations are superimposed on graphite grains as shown in FIG. 4, and the hardness is reduced. FIG. 4 is a view showing a state in which Vickers indentations are superimposed on graphite particles. Furthermore, when the graphite area ratio increases,
The amount of carbon C dissolved in the base material decreases, and the hardness decreases.
【００８５】硬さが低下するとクリーンな潤滑条件でも
表面起点タイプの異物混入潤滑下でも寿命は低下する。
軸受として安定した寿命を得るためには、最低でも硬さ
はＨＶ７００以上必要であり、軸受として十分な硬さを
得るためには黒鉛面積率を５％以下にしなければならな
い。さらに長寿命を得るためには黒鉛面積率を３％以
下、さらに好ましくは１％以下にすることが望ましい。When the hardness is reduced, the life is shortened under both a clean lubrication condition and a lubrication mixed with foreign matter of a surface starting type.
To obtain a stable life as a bearing, the hardness must be at least HV700 or more, and to obtain sufficient hardness as a bearing, the graphite area ratio must be 5% or less. To obtain a longer life, the graphite area ratio is desirably 3% or less, more preferably 1% or less.
【００８６】［平均粒径５μｍ以上の黒鉛が全黒鉛に対
して面積率で２％以下］並径軸受を想定した市場での表
面起点タイプの損傷状態を再現するべく、異物混入潤滑
下での寿命と平均粒径５μｍ以上の黒鉛粒の面積率との
関係を調べたところ、軸受完成品表面の５μｍ以上の大
形黒鉛の全黒鉛に対する面積率が２％を越えると寿命が
極端に低下することが確認できた。その結果を図２に示
す。[Area of graphite having an average particle size of 5 μm or more is 2% or less in area ratio with respect to total graphite] In order to reproduce a damage state of a surface starting type in a market assuming a parallel diameter bearing, lubrication under contaminant contamination is performed. The relationship between the life and the area ratio of graphite particles having an average particle size of 5 μm or more was examined. When the area ratio of large graphite of 5 μm or more to the total graphite on the surface of the finished bearing product exceeded 2%, the life was extremely reduced. That was confirmed. The result is shown in FIG.
【００８７】短寿命で破損した試験片を調査すると、５
μｍ以上の大きな黒鉛粒を起点としてはく離が発生して
いることから平均粒径５μｍ以上の黒鉛が全黒鉛に対し
て面積率で２％以下とする。Investigation of the short-lived and damaged test piece revealed that
Since exfoliation has occurred starting from large graphite particles of μm or more, the area ratio of graphite having an average particle size of 5 μm or more to all graphite is set to 2% or less.
【００８８】［平均粒形２μｍ以下の黒鉛粒が全黒鉛に
対して面積率で５０％以上］黒鉛粒は浸炭や浸炭窒化処
理を施しても簡単には消失せず、熱処理によって多少小
さくなった黒鉛が完成品表面に残ってしまう。したがっ
て、残留黒鉛粒が大きいとクリーン潤滑寿命や異物潤滑
寿命が低下してしまう。しかし、この残留黒鉛粒を平均
粒径２μｍ以下に制御することで逆に潤滑油が保持され
易くなる。[Graphite particles having an average particle size of 2 μm or less have an area ratio of 50% or more with respect to the total graphite] The graphite particles did not easily disappear even after carburizing or carbonitriding, and were slightly reduced by the heat treatment. Graphite remains on the finished product surface. Therefore, if the residual graphite particles are large, the clean lubrication life and the foreign matter lubrication life will be reduced. However, by controlling the residual graphite particles to an average particle size of 2 μm or less, the lubricating oil is easily retained.
【００８９】市場での使用条件で潤滑油の供給が不足し
やすい箇所やグリース潤滑でのグリース劣化による潤滑
不足等が起こった場合に転がり軸受の接触部の油膜形成
が不十分となり、転動面にピーリング損傷や滑り摩耗な
どの表面損傷が発生する。When the lubricating oil supply is likely to be insufficient under the conditions of use in the market or when lubrication is insufficient due to grease deterioration due to grease lubrication, the oil film formation at the contact part of the rolling bearing becomes insufficient and the rolling surface In addition, surface damage such as peeling damage and sliding wear occurs.
【００９０】そこで、黒鉛鋼の残留黒鉛粒を小さく制御
すると、微少なピットと同様の効果で潤滑剤が保持され
易くなる。Therefore, when the residual graphite particles of the graphite steel are controlled to be small, the lubricant can be easily retained with the same effect as the minute pits.
【００９１】市場で発生する表面損傷を再現するべく、
微小異物混入潤滑下での寿命と平均粒径２μｍ以下の黒
鉛粒の面積率との関係を調べた結果を示す特性図を図５
に示す。残留黒鉛粒が大きくなると、その効果が低減し
てピーリングタイプの寿命が低下してしまう。To reproduce the surface damage that occurs in the market,
FIG. 5 is a characteristic diagram showing the result of examining the relationship between the life under lubrication mixed with minute foreign matter and the area ratio of graphite particles having an average particle size of 2 μm or less.
Shown in When the residual graphite particles become large, the effect is reduced and the life of the peeling type is shortened.
【００９２】このように、表面損傷に対して長寿命効果
を出すためには、完成品表面に平均粒径２μｍ以下の黒
鉛粒が全黒鉛に対して面積粒で５０％以上にする必要が
ある。さらに、十分な長寿命効果を得るためには７０％
以上が望ましい。As described above, in order to obtain a long life effect against surface damage, it is necessary that graphite particles having an average particle size of 2 μm or less on the surface of the finished product should be 50% or more by area of the total graphite. . Furthermore, in order to obtain a sufficient long life effect, 70%
The above is desirable.
【００９３】［５Ｔｏｒｒ以下の高真空で浸炭処理］黒
鉛粒を微細化するためには、浸炭処理温度を高くするこ
とが有効である。しかし、ガス浸炭で処理温度を単純に
高くすると、前述したように設備的な問題と粒界酸化や
酸化膜による浸炭深さの低減の問題がある。図６は同一
条件での通常のガス浸炭と真空浸炭との浸炭深さ比を浸
炭温度に対して示す特性図である。浸炭温度が高くなる
程、浸炭深さ比が大きくなり、１０５０℃以上ではガス
浸炭と比べて１．５倍以上の浸炭深さが真空浸炭におい
て得られる。[Carburizing at High Vacuum of 5 Torr or Less] To reduce the size of graphite particles, it is effective to increase the carburizing temperature. However, if the treatment temperature is simply increased by gas carburization, as described above, there are problems of equipment and problems of grain boundary oxidation and reduction of carburization depth due to an oxide film. FIG. 6 is a characteristic diagram showing the carburizing depth ratio between normal gas carburizing and vacuum carburizing under the same conditions with respect to the carburizing temperature. As the carburizing temperature increases, the carburizing depth ratio increases, and at 1050 ° C. or more, a carburizing depth 1.5 times or more as compared with gas carburizing can be obtained in vacuum carburizing.
【００９４】しかし、一般的なプロパン等を使用する真
空浸炭では、前述したように煤が多量に発生したり、浸
炭濃度や浸炭深さのばらつきが多く、場合によっては浸
炭むらが発生してしまう。However, in general vacuum carburization using propane or the like, as described above, a large amount of soot is generated, and the carburization concentration and the carburization depth vary widely, and in some cases, uneven carburization occurs. .
【００９５】そこで、本実施形態では、メタン、プロパ
ン等の飽和炭化水素ガスではなく、不飽和炭化水素ガス
の１つであるアセチレンを使用し、５Ｔｏｒｒ以下の高
真空で煤の発生が少なく、安定した品質が得られる真空
浸炭を行うことにする。Therefore, in this embodiment, acetylene which is one of unsaturated hydrocarbon gas is used instead of saturated hydrocarbon gas such as methane and propane, and soot generation is small at high vacuum of 5 Torr or less and stable. We will carry out vacuum carburization to obtain the desired quality.
【００９６】アセチレンはメタンやプロパン等の飽和炭
化水素ガスに比べて不安定であり、分解速度も早いの
で、２００〜４００Ｔｏｒｒ程度の真空度で行う一般的
な真空浸炭条件では、大量の煤が発生してしまうが、真
空度を上げて５Ｔｏｒｒ以下にすると、煤の発生が減少
し良好な処理が可能となる。Acetylene is unstable compared to saturated hydrocarbon gas such as methane and propane, and has a high decomposition rate. Therefore, a large amount of soot is generated under general vacuum carburizing conditions performed at a vacuum degree of about 200 to 400 Torr. However, if the degree of vacuum is increased to 5 Torr or less, the generation of soot is reduced, and good processing can be performed.
【００９７】つまり、高真空条件での、メタンやプロパ
ン等の飽和炭化水素ガスによる浸炭では製品表面での煤
の発生は減少するものの、ガスの分解が不十分となり、
浸炭する能力が極端に低下してしまうのに対し、高真空
条件での不飽和炭化水素ガスの１つであるアセチレンに
よる浸炭では煤の発生が減少しても、製品表面でのガス
の分解は確実に行われ、安定した浸炭層が得られる。図
７はアセチレン浸炭における真空度と浸炭深さ比との関
係を示す特性図である。In other words, carburization with a saturated hydrocarbon gas such as methane or propane under high vacuum conditions reduces the generation of soot on the product surface, but makes gas decomposition insufficient.
While the ability to carburize is greatly reduced, carburization with acetylene, one of the unsaturated hydrocarbon gases under high vacuum conditions, reduces the decomposition of gas on the product surface even if the generation of soot is reduced. It is performed reliably and a stable carburized layer is obtained. FIG. 7 is a characteristic diagram showing the relationship between the degree of vacuum and the carburization depth ratio in acetylene carburization.
【００９８】同図では、０．５Ｔｏｒｒでの浸炭深さを
値１とした場合の浸炭深さ比が示されているが、真空度
が５Ｔｏｒｒを越えて低くなると、煤の発生が激しくほ
とんど浸炭されず、場合によっては浸炭むらも発生す
る。[0098] In the figure, the carburization depth ratio when the carburization depth at 0.5 Torr is set to a value of 1 is shown. However, when the degree of vacuum exceeds 5 Torr, soot generation is intense and almost carburization occurs. In some cases, uneven carburization also occurs.
【００９９】一方、真空度を５Ｔｏｒｒ以下にすると、
煤の発生が減少して良好な浸炭が可能となる。さらに、
１Ｔｏｒｒ以下の高真空である場合、浸炭が安定する傾
向にあり、１Ｔｏｒｒ以下で真空浸炭を行うことが望ま
しい。On the other hand, when the degree of vacuum is set to 5 Torr or less,
Good carburization becomes possible by reducing the generation of soot. further,
In the case of a high vacuum of 1 Torr or less, carburization tends to be stable, and it is desirable to perform vacuum carburization at 1 Torr or less.
【０１００】図８は浸炭温度と２μｍ以下の黒鉛面積率
との関係を示す特性図である。高温浸炭による黒鉛粒の
微細化に関し、浸炭温度以外の同一条件で浸炭処理を行
いたい場合、全黒鉛面積率に対する２μｍ以下の黒鉛面
積率では、通常の浸炭温度である９５０℃を越えると、
黒鉛の微細化が促進されている。したがって、浸炭温度
は９５０℃を越えることが望ましい。FIG. 8 is a characteristic diagram showing the relationship between the carburizing temperature and the graphite area ratio of 2 μm or less. Regarding the miniaturization of graphite particles by high-temperature carburization, if carburizing is desired to be performed under the same conditions other than the carburizing temperature, if the graphite area ratio of 2 μm or less relative to the total graphite area ratio exceeds the normal carburizing temperature of 950 ° C.,
The miniaturization of graphite has been promoted. Therefore, it is desirable that the carburizing temperature exceeds 950 ° C.
【０１０１】このように、黒鉛鋼に５Ｔｏｒｒ以下の高
真空、高温の浸炭を行うことにより、黒鉛粒の微細化を
調整すると同時に、短時間で必要な浸炭深さが得られ
る。As described above, by subjecting graphite steel to high-vacuum and high-temperature carburization of 5 Torr or less, it is possible to adjust the fineness of graphite grains and at the same time obtain a required carburizing depth in a short time.
【０１０２】ここで、黒鉛鋼に高真空浸炭を施すことに
より、さらに黒鉛鋼の利用範囲が拡大される。図９は浸
炭温度と黒鉛残留率との関係を示す図である。９５０℃
を越えると、素材の黒鉛は微細化と共に半分以下の面積
になる。Here, by subjecting the graphite steel to high vacuum carburization, the range of use of the graphite steel is further expanded. FIG. 9 is a diagram showing the relationship between the carburizing temperature and the graphite residual ratio. 950 ° C
Is exceeded, the graphite of the material becomes less than half in area with miniaturization.
【０１０３】図１０は素材の黒鉛面積率に対する冷間加
工性を示す特性図である。冷間加工性を示す値として、
後述するように穴開け加工を行う金型が破損するまでの
加工個数（×１０3）が示されている。黒鉛を析出させ
ると、硬さの低下と黒鉛の潤滑作用により冷間加工が良
好となる。素材の黒鉛面積率が５％以上になると、その
効果が高くなり、１０％以上で最良の冷間加工性を示し
た。FIG. 10 is a characteristic diagram showing the cold workability with respect to the graphite area ratio of the material. As a value indicating cold workability,
As will be described later, the number of processed pieces (× 10 3 ) until the die for punching is broken is shown. When graphite is precipitated, the cold work becomes good due to the decrease in hardness and the lubricating action of graphite. When the graphite area ratio of the raw material was 5% or more, the effect was enhanced, and when it was 10% or more, the best cold workability was exhibited.
【０１０４】つまり、素材の段階で黒鉛を多量に析出さ
せると、高い炭素含有鋼であっても、切削性だけでなく
冷間加工にも優れた素材となるが、通常の浸炭温度では
黒鉛粒を微細化できず、黒鉛面積率も高くなってしま
う。In other words, if a large amount of graphite is precipitated at the raw material stage, even if the carbon content of the steel is high, the raw material is excellent not only in machinability but also in cold working. Cannot be miniaturized, and the graphite area ratio increases.
【０１０５】そこで、高真空で高温浸炭を施すことによ
り黒鉛粒の微細化が可能となり、優れた加工性により低
コストで高機能な軸受を提供することができる。Therefore, by performing high-temperature carburizing in a high vacuum, the graphite grains can be made finer, and a high-performance bearing can be provided at low cost due to excellent workability.
【０１０６】［完成品表面の炭素Ｃ：０．９重量％〜
１．４重量％］炭素は軸受に必要な硬さと残留オーステ
ナイトを得るために必要な元素であり、完全にクリーン
な潤滑条件であれは、炭素Ｃが０．８重量％前後でもあ
る程度の寿命が得られるが、市場を想定した使用条件で
長寿命を得るためには最低でも０．９重量％以上は必要
である。[Carbon C on surface of finished product: 0.9% by weight or more]
[1.4% by weight] Carbon is an element necessary for obtaining hardness and retained austenite necessary for bearings, and even under a completely clean lubricating condition, a certain life can be obtained even when carbon C is around 0.8% by weight. However, at least 0.9% by weight or more is required in order to obtain a long life under the use conditions assumed for the market.
【０１０７】しかし、炭素Ｃが１．４重量％を越える
と、研削加工性および寿命や強度を劣化させるＭ3Ｃな
どの巨大炭化物が多量に析出するおそれがある。このた
め、完成品表面の炭素Ｃは０．９重量％〜１．４重量％
とする。However, if the carbon C content exceeds 1.4% by weight, a large amount of large carbides such as M 3 C, which deteriorates the grinding workability and the life and strength, may be deposited. Therefore, carbon C on the surface of the finished product is 0.9% to 1.4% by weight.
And
【０１０８】［完成品表面の窒素Ｎ：０．３重量％以
下］窒素は残留オーステナイトの生成や焼戻抵抗性を向
上させるので、軸受の長寿命化や耐熱性や耐摩耗性を向
上させる元素である。しかし、その量が軸受完成表面で
０．３重量％を越えると、熱処理完了後の表面ではさら
に窒素量が高くなる傾向にあり、研削加工性が著しく低
下してしまう。このため、完成品表面の窒素は０．３％
重量以下とする。[Nitrogen N on the surface of the finished product: 0.3% by weight or less] Nitrogen improves the generation of retained austenite and improves the tempering resistance, so that it increases the life of the bearing and improves heat resistance and wear resistance. It is. However, if the amount exceeds 0.3% by weight on the finished surface of the bearing, the amount of nitrogen tends to be further increased on the surface after the heat treatment, and the grindability is significantly reduced. For this reason, the nitrogen on the finished product surface is 0.3%
Not more than weight.
【０１０９】ここで、軸受用鋼には浸炭または浸炭窒化
処理を施すが、浸炭処理でも鋼材には摩耗特性を向上さ
せる程ではないが、若干の窒素を固溶する。その量は合
成成分にもよるが０．０２重量％前後であり、最低でも
０．０１重量％以上固溶する。したがって、完成品表面
の窒素Ｎは０．０１重量％〜０．３重量％とする。Here, the bearing steel is subjected to a carburizing or carbonitriding treatment. However, even though the carburizing treatment does not improve the wear characteristics of the steel material, a slight amount of nitrogen is dissolved in the steel material. The amount depends on the synthetic component, but is about 0.02% by weight, and forms a solid solution of at least 0.01% by weight. Therefore, the nitrogen N on the surface of the finished product is set to 0.01% by weight to 0.3% by weight.
【０１１０】ただし、浸炭窒化処理では、浸炭処理に比
べて窒素の固溶による組織強化、炭窒化物の微細析出に
よる寿命特性向上および耐熱性や耐摩耗性の向上が得ら
れる。その効果を得るために、窒素は最低０．０５重量
％以上必要である。また、窒素はその含有量が０．２重
量％を越えると、Ｍ4Ｎ等の窒化物が析出し、耐摩耗性
が向上する反面、研削性は低下していく傾向にある。つ
まり、浸炭窒化処理を行う場合、完成表面の窒素量は
０．０５重量％〜０．２重量％とすることが望ましい。However, in the carbonitriding treatment, the structure is strengthened by solid solution of nitrogen, the life property is improved by fine precipitation of carbonitride, and the heat resistance and the wear resistance are improved as compared with the carbonitriding treatment. To obtain this effect, nitrogen must be at least 0.05% by weight or more. If the content of nitrogen exceeds 0.2% by weight, nitrides such as M 4 N are precipitated and the wear resistance is improved, but the grindability tends to decrease. That is, when carbonitriding is performed, the amount of nitrogen on the finished surface is desirably 0.05% by weight to 0.2% by weight.
【０１１１】以上示した軸受材料の合金成分の作用およ
び成分範囲の限定理由により、本実施形態における転が
り軸受は、内輪、外輪および転動体の少なくとも１つに
浸炭または浸炭窒化処理を行った素材が適用される転が
り軸受において、素材は、炭素０．４５〜０．９重量
％、シリコン０．５〜１．５重量％、マンガン０．３〜
１．５重量％およびクロム０．７重量％以下を含有し、
残りが鉄および不純物元素からなる合金であり、この素
材に対して黒鉛化処理を行って微細黒鉛を析出させてお
き、不飽和炭化水素ガスを使用した５Ｔｏｒｒ以下の高
真空で浸炭を行うことで、完成品表面における黒鉛の面
積率を５％以下とし、平均粒径５μｍ以上の大形黒鉛粒
が全黒鉛に対して面積率で２％以下であり、かつ平均粒
径２μｍ以下の微細黒鉛粒が全黒鉛に対して面積率で５
０％以上であり、完成品表面層における炭素量および窒
素量がそれぞれ０．９〜１．４重量％、０．０１〜０．
３重量％であることを特徴とする。[0111] Due to the above-mentioned effects of the alloy components of the bearing material and the limitation of the component range, the rolling bearing of the present embodiment is made of a material in which at least one of the inner ring, the outer ring and the rolling elements is subjected to carburizing or carbonitriding. In the rolling bearing to be applied, the materials are carbon: 0.45 to 0.9% by weight, silicon: 0.5 to 1.5% by weight, manganese 0.3 to 0.9%.
1.5% by weight and not more than 0.7% by weight of chromium,
The remainder is an alloy consisting of iron and impurity elements. This material is graphitized to precipitate fine graphite, and then carburized in a high vacuum of 5 Torr or less using an unsaturated hydrocarbon gas. The area ratio of graphite on the surface of the finished product is set to 5% or less, and the large graphite particles having an average particle size of 5 μm or more have an area ratio of 2% or less to the total graphite and the fine graphite particles having an average particle size of 2 μm or less. Is 5 in area ratio to total graphite
0% or more, and the amount of carbon and the amount of nitrogen in the finished product surface layer are 0.9 to 1.4% by weight and 0.01 to 0. 0%, respectively.
3% by weight.
【０１１２】[0112]
【実施例】転がり軸受の実施例について説明する。本実
施例の転がり軸受は黒鉛粒の平均粒径や面積率に特徴を
有するものであり、黒鉛粒の面積率を直接測定するため
に、素材の断面および軸受の完成品表面の組織を電子顕
微鏡で撮影し、画像解析装置によってその電子顕微鏡画
像の素地から黒鉛粒だけを取り出す。そして、その形
状、面積、個数などを測定して各黒鉛粒をその面積から
円形に換算した平均粒径や面積率を算出する。被検面積
は各鋼種毎に１視野を０．１ｍｍ2 （電子顕微鏡２００
倍）として５０視野調査した結果である。An embodiment of a rolling bearing will be described. The rolling bearing of the present embodiment is characterized by the average particle size and area ratio of graphite particles.In order to directly measure the area ratio of graphite particles, the cross-section of the material and the structure of the finished product surface of the bearing are measured by an electron microscope. And only the graphite particles are taken out of the electron microscope image base by the image analysis device. Then, the shape, the area, the number, and the like are measured, and the average particle diameter and the area ratio of each graphite particle converted from the area into a circle are calculated. The test area is 0.1 mm 2 for one field of view for each steel type (electron microscope 200
This is the result of 50 field-of-view surveys as (fold).
【０１１３】ここで、電子顕微鏡は日本電子社製ＪＳＭ
−Ｔ２２０Ａであり、画像解析装置はカールツァィス社
製ＩＢＡＳ２０００である。Here, the electron microscope is JSM manufactured by JEOL Ltd.
-T220A, and the image analyzer is IBAS2000 manufactured by Carl Zeiss.
【０１１４】［ソーキング処理有無］試料素材のビレッ
ト断面をマクロおよびミクロ組織で調査し、寿命に有害
な巨大炭化物や濃厚な縞状偏析の有無を確認した。材料
成分およびソーキング処理の有無を調査した結果を表１
に示す。[Presence / absence of soaking treatment] The cross section of the billet of the sample material was examined by macro and micro structure, and it was confirmed whether or not there was a giant carbide harmful to the service life or dense striped segregation. Table 1 shows the results of an investigation on the material components and the presence or absence of soaking treatment.
Shown in
【０１１５】[0115]
【表１】 本実施例は炭素Ｃ重量％とクロムＣｒ重量％を適量に調
整することでソーキング処理を必要としない。比較例の
鋼種Ｋ２３、Ｋ２８およびＳＵＪ２は炭素Ｃ重量％やク
ロムＣｒ重量％が高いので、ソーキング処理が必要であ
ると判断した。[Table 1] In this embodiment, the soaking treatment is not required by adjusting the carbon C weight% and the chromium Cr weight% to appropriate amounts. Since the steel types K23, K28 and SUJ2 of the comparative examples were high in carbon C weight% and chromium Cr weight%, it was determined that soaking treatment was necessary.
【０１１６】［被削性試験］ 切削工具寿命： 切削機械：高速旋盤 工具 ：Ｐ１０（ＪＩＳ Ｂ ４０５３） 切り込み速度：２００〜２５０ｍ／ｍｉｎ 送り量：０．２〜０．３ｍｍ／ｒｅｖ 切り込み深さ：１．０〜１．５ｍｍ ＪＩＳ Ｂ ４０１１のバイト切削試験法にしたがっ
て、上記条件で各試料を切削し、バイトの逃げ面摩耗量
が０．２ｍｍに達するまでを工具寿命とした。[Machinability test] Cutting tool life: Cutting machine: High-speed lathe Tool: P10 (JIS B 4053) Cutting speed: 200 to 250 m / min Feeding amount: 0.2 to 0.3 mm / rev Cutting depth: 1.0 to 1.5 mm According to the cutting tool test method of JIS B 4011, each sample was cut under the above conditions, and the tool life was defined as the flank wear amount of the cutting tool reaching 0.2 mm.
【０１１７】表２および図１に素材の黒鉛量と被削性の
関係を調査した結果を示す。同一鋼種Ｋ１を用いて黒鉛
化処理条件を変えることにより、素材の黒鉛面積率を変
化させた。素材の状態ですこしでも黒鉛が析出すれば、
切削性が改善される。Table 2 and FIG. 1 show the results of investigation on the relationship between the graphite content of the material and the machinability. The graphite area ratio of the raw material was changed by changing the graphitization treatment conditions using the same steel type K1. If graphite precipitates even a little in the state of the material,
The machinability is improved.
【０１１８】[0118]
【表２】 ［黒鉛化処理］軸受は素材の段階で黒鉛化処理を行い、
素材に黒鉛粒を析出させることで被削性を飛躍的に向上
させる。図１１は黒鉛化処理条件を示す図である。黒鉛
化処理条件は素材をＡ１変態点以下の温度で長時間保持
するものである。本実施例では６８０〜７１０℃の範囲
で処理時間を変えることで黒鉛面積率や黒鉛粒の調整を
行った。[Table 2] [Graphization treatment] The bearing is graphitized at the material stage,
Machinability is dramatically improved by depositing graphite particles on the material. FIG. 11 is a diagram showing graphitization treatment conditions. The graphitization condition is to maintain the material at a temperature below the A1 transformation point for a long time. In this example, the graphite area ratio and the graphite particles were adjusted by changing the treatment time in the range of 680 to 710 ° C.
【０１１９】［熱処理条件］本実施例における熱処理条
件を以下に示す。[Heat treatment conditions] The heat treatment conditions in this example are shown below.
【０１２０】熱処理条件：Ａ 温度９３０℃以上９６０℃以下で０．５〜１時間、吸熱
形ガス雰囲気で導入する吸熱形ガス流量に対してエンリ
ッチガス０．３％〜０．７％、Ｃｐ（カーボンポテンシ
ャル）値＝０．９〜１．２％の条件で浸炭を行い、処理
温度を８４０℃以上９００℃以下まで下げてから焼入を
行う。Heat treatment conditions: A temperature of 930 ° C. or higher and 960 ° C. or lower for 0.5 to 1 hour, 0.3% to 0.7% of enriched gas, Cp ( Carburizing is performed under the condition of (carbon potential) = 0.9 to 1.2%, and the quenching is performed after the treatment temperature is lowered to 840 ° C. or more and 900 ° C. or less.
【０１２１】熱処理条件：Ｂ 温度９２０℃以上９５０℃以下で０．５〜１時間の短時
間で吸熱形ガス雰囲気で導入する吸熱形ガス流量に対し
てエンリッチガス０．３％〜０．７％、アンモニアガス
３〜１０％の条件で浸炭窒化を行い、処理温度を８４０
℃以上９００℃以下まで下げてから焼入を行う。Heat treatment conditions: B enriched gas 0.3% to 0.7% with respect to the endothermic gas flow introduced in the endothermic gas atmosphere in a short time of 0.5 to 1 hour at a temperature of 920 ° C. to 950 ° C. , Carbonitriding under the condition of 3 to 10% ammonia gas, and treatment temperature of 840
Quenching is performed after the temperature is lowered to not less than 900 ° C and not more than 900 ° C.
【０１２２】熱処理条件：Ｃ 温度８４０℃以上９００℃未満で０．５〜１時間の短時
間、吸熱形ガス雰囲気で導入する吸熱形ガス流量に対し
てエンリッチガス０．３％〜０．７％、アンモニアガス
３〜１０％の条件で浸炭窒化を行い、そのままダイレク
トに焼入を行う。Heat treatment condition: C temperature 840 ° C. or higher and lower than 900 ° C., 0.5 to 1 hour, enriched gas 0.3% to 0.7% with respect to the heat absorbing gas flow introduced in the heat absorbing gas atmosphere for a short time of 0.5 to 1 hour. Then, carbonitriding is performed under the condition of 3 to 10% ammonia gas, and quenching is performed directly.
【０１２３】熱処理条件：Ｄ 温度９３０℃以上９６０℃以下で３〜５時間、Ｃｐ値＝
０．９〜１．２％の条件で通常浸炭処理を行い、処理温
度を８４０℃以上９００℃以下まで下げてから焼入を行
う。Heat treatment condition: D temperature 930 ° C. or more and 960 ° C. or less for 3 to 5 hours, Cp value =
Carburizing is usually performed under the conditions of 0.9 to 1.2%, and the quenching is performed after the processing temperature is lowered to 840 ° C or more and 900 ° C or less.
【０１２４】熱処理条件：Ｅ 温度９３０℃以上９６０℃以下で５〜７時間でＣｐ値＝
１．３％以上の高濃度浸炭処理を行い、処理温度を８４
０℃以上９００℃以下まで下げてから焼入を行う。Heat treatment conditions: E temperature 930 ° C. or more and 960 ° C. or less, Cp value in 5 to 7 hours =
Carbide treatment with high concentration of 1.3% or more is performed, and the treatment temperature is 84
Quenching is performed after the temperature is reduced to 0 ° C or more and 900 ° C or less.
【０１２５】熱処理条件：Ｆ 温度８３０℃以上８６０℃以下で０．５〜１時間保持し
た後、焼入を行う。Heat treatment conditions: After holding at an F temperature of 830 ° C. or more and 860 ° C. or less for 0.5 to 1 hour, quenching is performed.
【０１２６】熱処理条件：Ｇ 温度９３０℃以上〜９６０℃以下で０．５〜１時間、炉
内圧力が０．３〜０．７Ｔｏｒｒになるように、真空中
に適量のアセチレンを直接導入して分解ガス雰囲気によ
る浸炭を行い、浸炭終了後に炉内を２００Ｔｏｒｒ以上
に復圧し、処理温度を８４０℃以上〜９００℃以下まで
下げてから焼入れを行う。Heat treatment conditions: G A suitable amount of acetylene is directly introduced into a vacuum at a temperature of 930 ° C. to 960 ° C. for 0.5 to 1 hour and a furnace pressure of 0.3 to 0.7 Torr. Carburization is performed in a decomposed gas atmosphere, and after the carburization is completed, the pressure in the furnace is restored to 200 Torr or more, and the quenching is performed after the treatment temperature is reduced to 840 to 900 ° C.
【０１２７】熱処理条件：Ｈ 温度９８０℃以上〜１０５０℃以下で０．５〜１時間、
真空炉中にアセチレンを炉内容積に対して０．１〜０．
５％直接導入し、炉内圧力が０．３〜０．７Ｔｏｒｒに
なる条件で分解ガス雰囲気による浸炭を行い、浸炭終了
後に炉内を２００Ｔｏｒｒ以上に復圧し、処理温度を８
４０℃以上〜９００℃以下まで下げてから焼入れを行
う。Heat treatment conditions: H temperature 980 ° C. or higher and 1050 ° C. or lower for 0.5 to 1 hour,
Acetylene was placed in a vacuum furnace at 0.1 to 0.1% with respect to the furnace volume.
5% was directly introduced, and carburization was performed in a decomposition gas atmosphere under the condition that the furnace pressure was 0.3 to 0.7 Torr. After the carburization was completed, the furnace pressure was restored to 200 Torr or more, and the processing temperature was set to 8
After quenching, the temperature is lowered from 40 ° C. or more to 900 ° C. or less.
【０１２８】本実施例では浸炭や浸炭窒化を短時間で行
うように素材の炭素量を多く設定しているので、コスト
と長寿命が同時に得られる熱処理条件Ａ、Ｂ、Ｃを用い
る。ただし、熱処理条件Ｄの通常浸炭処理を行えば、当
然長寿命が得られる。また、熱処理条件Ｆは通常の焼入
処理であるが、硬さを得るために浸炭または浸炭窒化処
理の後に２次焼入処理として使用される場合がある。一
方、５Ｔｏｒｒ以下の高真空で浸炭を行う場合、条件
Ｇ、Ｈを用いた。In this embodiment, since the amount of carbon in the material is set to be large so that carburizing or carbonitriding can be performed in a short time, heat treatment conditions A, B, and C that simultaneously provide a long life and cost are used. However, if the normal carburizing treatment under the heat treatment condition D is performed, a long life is naturally obtained. The heat treatment condition F is a normal quenching process, but may be used as a secondary quenching process after carburizing or carbonitriding to obtain hardness. On the other hand, when carburizing was performed in a high vacuum of 5 Torr or less, conditions G and H were used.
【０１２９】焼戻処理は全処理共通であり、１６０〜２
００℃で２時間の焼戻しを行った。ただし、２次焼入処
理を行う場合、浸炭または浸炭窒化処理の後に焼戻は行
わない。The tempering process is common to all processes.
Tempering was performed at 00 ° C. for 2 hours. However, when performing the secondary quenching treatment, tempering is not performed after the carburizing or carbonitriding treatment.
【０１３０】表３に完成品表面の黒鉛面積率が２〜４％
になるような黒鉛化処理を行い、その後、硬化熱処理し
た時の黒鉛化処理時間と素材の被削性を評価した結果を
示す。Table 3 shows that the graphite area ratio of the finished product surface is 2 to 4%.
The graph shows the results of evaluation of the graphitization treatment time and the machinability of the raw material when a graphitization treatment was performed and hardening heat treatment was performed thereafter.
【０１３１】[0131]
【表３】 本実施例のほとんどは５〜１０時間の黒鉛化処理で十分
に被削性が良好となる黒鉛を析出させることができる。
ただし、Ｎｏ．２３，２８ではマンガンＭｎやクロムＣ
ｒの添加量が多く１５時間処理となってしまう。そのた
め、前述したように黒鉛化を短時間で行うためにマンガ
ンＭｎの含有量は１．０重量％以下、クロムＣｒの含有
量は０．６重量％以下とすることが望ましい。[Table 3] In most of the present examples, graphite having satisfactory machinability can be precipitated by graphitization treatment for 5 to 10 hours.
However, no. For 23 and 28, manganese Mn and chromium C
The addition amount of r is large, resulting in processing for 15 hours. Therefore, as described above, in order to perform graphitization in a short time, the content of manganese Mn is desirably 1.0% by weight or less, and the content of chromium Cr is desirably 0.6% by weight or less.
【０１３２】一方、比較例のＮｏ．３３ではシリコンＳ
ｉの添加量が少なく、Ｎｏ．３６，３７ではマンガンＭ
ｎやクロムＣｒの添加量が多過ぎるので、黒鉛化処理時
間が長くなり、素材コストが上がるため被削性向上によ
るコストダウン効果が失われてしまう。また、黒鉛化処
理を行わないＳＵＪ２は被削性が悪い。On the other hand, in Comparative Example No. 33 is silicon S
i. Manganese M for 36 and 37
If the amount of addition of n or chromium Cr is too large, the graphitization process time is prolonged, and the material cost is increased, so that the cost reduction effect due to the improvement in machinability is lost. SUJ2 without graphitization has poor machinability.
【０１３３】表４および図３に完成品表面の黒鉛面積率
と表面硬さの関係を示す。Table 4 and FIG. 3 show the relationship between the graphite area ratio on the finished product surface and the surface hardness.
【０１３４】[0134]
【表４】 黒鉛面積率が５％を越えると、図４に示すようにビッカ
ース圧痕に黒鉛粒が重なることで、急激に硬さが低下し
てしまう。Ｋ１以外の鋼種でも同様に５％を越えると急
激に硬さが低下する。[Table 4] When the graphite area ratio exceeds 5%, as shown in FIG. 4, graphite particles overlap with Vickers indentations, so that the hardness is rapidly reduced. Similarly, when the steel type other than K1 exceeds 5%, the hardness rapidly decreases.
【０１３５】［研削試験］ 砥石：ＷＡ１００ 研削液：ソリュブルタイプ 砥石周速：２８００〜３０００ｍ／ｍｉｎ 上記条件で転がり軸受の内輪軌道面に相当するサンプル
を砥石で研削し、砥石の形状くずれおよび目詰まりの状
態を観察し、砥石のドレスを行うまでに研削したサンプ
ル数（研削個数）を調査した。[Grinding test] Grinding wheel: WA100 Grinding fluid: Soluble type Grinding wheel peripheral speed: 2800 to 3000 m / min Under the above conditions, a sample corresponding to the inner ring raceway surface of a rolling bearing is ground with a grinding stone, and the shape of the grinding stone is deformed and clogged. Was observed, and the number of samples (grinding number) ground before dressing of the grindstone was investigated.
【０１３６】［クリーン寿命試験］「特殊鋼便覧」第一
版（電気製鋼研究所編、理工学社、１９６９年５月２５
日発行）第１０〜２１頁記載のスラスト型軸受鋼寿命試
験機を用いて各サンプルにフレーキングが発生した時点
までの累積応力繰り返し回数（寿命）を調査してワイブ
ルプロットを作成し、各ワイブル分布の結果から各々の
寿命Ｌ１０を求めた。[Clean Life Test] "Special Steel Handbook" First Edition (edited by Electric Steel Research Institute, Rigakusha, May 25, 1969)
Using a thrust-type bearing steel life tester described on pages 10 to 21 to investigate the cumulative number of stress repetitions (life) up to the point at which flaking occurred in each sample, to create a Weibull plot, Each life L10 was determined from the distribution results.
【０１３７】 試験面圧：最大５２００ＭＰａ 回転数：３０００Ｃ．Ｐ．Ｍ 潤滑油：＃６８タービン油 表５に浸炭および浸炭窒化処理を行い、場合によっては
二次焼入を行った時の表面炭素Ｃ量％、窒素Ｎ量％と研
削性およびクリーン寿命評価結果を示す。尚、素材でソ
ーキングが必要なＫ２３、Ｋ２８、ＳＵＪ２および黒鉛
化処理時間が長いＫ２４、Ｋ２７の５鋼種については寿
命評価を行わない。Test contact pressure: maximum 5200 MPa Rotational speed: 3000C. P. M Lubricating oil: # 68 turbine oil Table 5 shows the results of the evaluation of grindability and clean life with surface carbon C content% and nitrogen N content% after carburizing and carbonitriding and, in some cases, secondary quenching. Show. The service life is not evaluated for the five steel types K23, K28, SUJ2, which require soaking as materials, and K24, K27, which have a long graphitization time.
【０１３８】[0138]
【表５】 本実施例のＮｏ．４８〜９２では表面窒素量が０．３重
量％以下になり、研削性が良好であり、クリーン潤滑下
で長寿命を示した。ただし、本実施例の鋼種であって
も、シリコンＳｉの添加量が多いＫ９およびマンガンＭ
ｎやクロムＣｒの添加量が多いＫ１４、Ｋ１９を比較的
低い温度で浸炭窒化を行う熱処理条件Ｃでは、表面の窒
素量が０．３重量％を越えて研削性が低下してしまう比
較例をＮｏ．１０４，１０５，１０６に示した。このた
め、前述したように浸炭窒化処理を行う場合、シリコン
Ｓｉ含有量は１．０重量％以下が望ましい。[Table 5] No. of this embodiment. In the case of 48 to 92, the amount of surface nitrogen was 0.3% by weight or less, the grindability was good, and a long life was exhibited under clean lubrication. However, even in the case of the steel type of this embodiment, K9 and manganese M containing a large amount of silicon Si were added.
Under the heat treatment condition C in which carbonizing and nitriding of K14 and K19 with a large addition amount of n and chromium Cr are performed at a relatively low temperature, the nitrogen amount on the surface exceeds 0.3% by weight and the grindability decreases. No. 104, 105 and 106. Therefore, when carbonitriding is performed as described above, the silicon Si content is desirably 1.0% by weight or less.
【０１３９】一方、素材の炭素量が下限より少ないＫ２
２にコストを考慮した短時間熱処理Ａ，Ｂ，Ｃを施す
と、表面炭素量が０．９重量％以下となり寿命が低下し
てしまうＮｏ．９３，９４，９５の比較例を示す。ま
た、素材のシリコンＳｉ量が上限を越えるＫ２５に短時
間熱処理Ａ，Ｂ，Ｃを施しても拡散深さが低く寿命が低
下してしまうＮｏ．９６，９７，９８の比較例を示す。
さらに、素材のマンガンＭｎ量が下限より低いＫ２６に
短時間熱処理Ａ，Ｂ，Ｃを施しても焼入性が不足して十
分な硬さが得られず寿命が低下するＮｏ．９９，１０
０，１０１の比較例を示す。On the other hand, if the carbon content of the material is smaller than the lower limit, K2
No. 2, when the short-time heat treatments A, B, and C are performed in consideration of the cost, the surface carbon content becomes 0.9% by weight or less and the life is shortened. 93, 94 and 95 show comparative examples. Further, even if short-time heat treatments A, B, and C are performed on K25 in which the amount of silicon Si exceeds the upper limit, the diffusion depth is low and the life is shortened. 96, 97 and 98 show comparative examples.
Furthermore, even if the heat treatments A, B, and C are applied to K26 in which the manganese Mn content of the material is lower than the lower limit, hardenability is insufficient, sufficient hardness cannot be obtained, and the life is shortened. 99,10
The comparative example of 0,101 is shown.
【０１４０】また、本実施例の鋼種Ｋ１に高濃度浸炭熱
処理Ｅを施したＮｏ．１０２では初期の多量析出により
寿命が低下し、通常の焼入を行う熱処理Ｆを施したＮ
ｏ．１０３では黒鉛粒が素材に溶け込まず、素材の炭素
量が不足し、十分な硬さが得られず寿命が低下する。In addition, the steel type K1 of this example was subjected to the high-concentration carburizing heat treatment No. In No. 102, the life was shortened due to the initial large amount of precipitation, and N was subjected to heat treatment F for performing normal quenching.
o. In 103, the graphite particles do not dissolve in the material, the carbon content of the material is insufficient, sufficient hardness cannot be obtained, and the life is shortened.
【０１４１】［異物混入潤滑下寿命］スラスト型軸受鋼
寿命試験機を用いて、転動体にはＳＵＪ２ボールを用
い、各サンプルにフレーキングが発生した時点までの累
積応力繰り返し回数（寿命）を調査してワイブルプロッ
トを作成し、各ワイブル分布の結果から各々の寿命Ｌ１
０を求めた。[Life under lubrication mixed with foreign matter] Using a thrust-type bearing steel life tester, using SUJ2 balls as rolling elements, the number of cumulative stress repetitions (life) until the occurrence of flaking in each sample was investigated. To create a Weibull plot, and from the results of each Weibull distribution, each life L1
0 was determined.
【０１４２】 試験面圧：最大４９００ＭＰａ 回転数：３０００Ｃ．Ｐ．Ｍ． 潤滑油：＃６８タービン油 混入異物： 組成：ステンレス系粉 硬さ：ＨＲＣ５０ 粒径：６５〜１２０μｍ 混入量：潤滑油中に３００ｐｐｍ ［ピーリング寿命］スラスト型軸受鋼寿命試験機を用い
て転動体にはＳＵＪ２ボールを用い、各サンプルにピー
リングが発生し、さらにフレーキングに至った時点まで
の累積応力繰り返し回数（寿命）を調査してワイブルプ
ロットを作成し、各ワイブル分布の結果から各々の寿命
Ｌ１０を求めた。Test surface pressure: Maximum 4900 MPa Rotational speed: 3000C. P. M. Lubricating oil: # 68 Turbine oil Contaminated foreign matter: Composition: Stainless steel powder Hardness: HRC50 Particle size: 65 to 120 μm Contaminated amount: 300 ppm in lubricating oil [Peeling life] For rolling elements using a thrust type bearing steel life tester Used a SUJ2 ball to investigate the cumulative number of stress repetitions (life) until peeling occurred in each sample and further to flaking to create a Weibull plot, and from the results of each Weibull distribution, each life L10 I asked.
【０１４３】 試験面圧：最大４５００ＭＰａ 回転数：３０００Ｃ．Ｐ．Ｍ． 潤滑油：＃６８タービン油 混入異物： 組成：ステンレス系粉 硬さ：ＨＲＣ５８ 粒径：３０μｍ 混入量：潤滑油中に１０００ｐｐｍ つぎに、市場での実際の損傷を再現する表面損傷タイプ
の異物混入潤滑下寿命と市場の軸受表面に微細なはく離
が発生するピーリング損傷を再現するピーリング寿命評
価結果を表６および一部を図２と図５に示す。尚、浸炭
および浸炭窒化処理で深さ不足や研削性が悪いＫ２５に
ついては異物混入潤滑下およびピーリング寿命評価を行
わない。Test surface pressure: maximum 4500 MPa Revolution: 3000 C. P. M. Lubricating oil: # 68 turbine oil Contaminated foreign matter: Composition: stainless steel powder Hardness: HRC58 Particle size: 30 μm Contaminated amount: 1000 ppm in lubricating oil Next, surface damage type foreign matter mixed lubrication that reproduces actual damage in the market Table 6 shows the results of the peeling life evaluation which reproduces the lower life and peeling damage in which minute peeling occurs on the bearing surface in the market, and FIGS. 2 and 5 show a part thereof. For K25 with insufficient depth or poor grinding properties due to carburizing and carbonitriding, the evaluation of the lubrication under foreign substances and the peeling life are not performed.
【０１４４】[0144]
【表６】 本実施例では黒鉛粒をコントロールし、微細化すること
で異物混入潤滑下およびピーリング寿命が良好である。
ただし、本実施例の鋼種であっても、平均粒径５μｍ以
上の大形黒鉛粒が全黒鉛に対して面積率で２％を越える
と異物混入潤滑下寿命が低下するＮｏ．１６１，１６２
や平均粒径２μｍ以下の微細黒鉛粒が全黒鉛に対して面
積率で５０％より低いと、ピーリング寿命が低下するＮ
ｏ．１６３，１６４，１６５を示した。[Table 6] In the present embodiment, by controlling and miniaturizing the graphite particles, the lubrication under the contamination with foreign matters and the peeling life are good.
However, even in the case of the steel type of this example, when the large graphite particles having an average particle size of 5 μm or more exceed 2% in the area ratio with respect to the total graphite, the life under lubrication with foreign matter decreases. 161,162
If the fine graphite particles having an average particle diameter of 2 μm or less are less than 50% in area ratio with respect to the total graphite, the peeling life is reduced.
o. 163, 164, and 165.
【０１４５】一方、素材の炭素量か下限より少ないＫ２
２をコストを考慮した短時間熱処理Ｂを施すと、表面炭
素Ｃの含有量が０．９重量％以下となり各種寿命が低下
してしまうＮｏ．１６６の比較例を示す。また、素材の
マンガンＭｎ量が下限より低いＫ２６に短時間熱処理Ｂ
を施しても焼入性が不足して十分な硬さが得られず各種
寿命が低下するＮｏ．１６７の比較例を示す。On the other hand, the carbon content of the material or K2 less than the lower limit
No. 2 is subjected to short-time heat treatment B in consideration of cost, the content of surface carbon C becomes 0.9% by weight or less, and various lifespans are shortened. 166 shows a comparative example. In addition, a short-time heat treatment B
No. 3, hardenability is insufficient and sufficient hardness is not obtained even if the steel is subjected to No. 3 to shorten the life of various types. 167 shows a comparative example.
【０１４６】また、本実施例の鋼種Ｋ１に高濃度浸炭熱
処理Ｅを施したＮｏ．１６８では、初期の多量析出によ
り各種寿命が低下する。通常の焼入を行う熱処理Ｆを施
したＮｏ．１６９では黒鉛粒が素材に溶け込まず、素材
の炭素量が不足して十分な硬さが得られず各種寿命が低
下する。In addition, the steel type K1 of this example was subjected to the high-concentration carburizing heat treatment No. In 168, various lifetimes are reduced due to the initial large amount of precipitation. No. 1 which was subjected to heat treatment F for performing normal quenching. In the case of 169, the graphite particles do not dissolve in the material, the carbon content of the material is insufficient, sufficient hardness cannot be obtained, and the various lifespans are reduced.
【０１４７】つぎに、素材の黒鉛量を高くして冷間加工
性を向上させ、熱処理で黒鉛粒を微細化する実施例を示
す。黒鉛を効率良く微細化するには、高温で浸炭する方
法が有効であるが、通常のガス浸炭では効率が悪い。Next, there will be described an embodiment in which the amount of graphite in the raw material is increased to improve the cold workability, and the graphite particles are refined by heat treatment. In order to efficiently reduce the size of graphite, a method of carburizing at a high temperature is effective, but the efficiency is low with ordinary gas carburizing.
【０１４８】［浸炭深さ比調査］通常ガス浸炭を比較例
とし、アセチレン浸炭を実施例とする浸炭深さ比を調査
する際、次の条件でそれぞれ浸炭処理を行った。[Carburizing Depth Ratio Investigation] When investigating the carburizing depth ratio using normal gas carburizing as a comparative example and acetylene carburizing as an example, carburizing treatment was performed under the following conditions.
【０１４９】通常ガス浸炭：吸熱型ガス雰囲気 導入する吸熱型ガス流量に対しエンリッチガス０．３％
〜０．７％、Ｃｐ値＝０．９〜１．２％の条件で３時間
浸炭を行い、処理温度を８４０℃以上〜９００℃以下ま
で下げてから焼入れを行う。Normal gas carburizing: Endothermic gas atmosphere 0.3% of enriched gas with respect to the endothermic gas flow introduced
Carburizing is performed for 3 hours under conditions of ０．７0.7% and Cp value = 0.9-1.2%, and quenching is performed after the treatment temperature is lowered to 840 ° C. or more and 900 ° C. or less.
【０１５０】アセチレン浸炭：真空炉中にアセチレンを
炉内容積に対して０．１〜０．５％直接導入し、炉内圧
力＝０．３〜０．７Ｔｏｒｒの条件で３時間浸炭を行
い、浸炭終了後に炉内を２００Ｔｏｒｒ以上に復圧し、
処理温度を８４０℃以上〜９００℃以下まで下げてから
焼入れを行う。Acetylene carburization: Acetylene was directly introduced into a vacuum furnace at 0.1 to 0.5% of the furnace volume, and carburized at a furnace pressure of 0.3 to 0.7 Torr for 3 hours. After carburizing is completed, the pressure inside the furnace is restored to 200 Torr or more,
The quenching is performed after the treatment temperature is lowered from 840 ° C to 900 ° C.
【０１５１】浸炭深さ比は、断面の炭素Ｃ濃度％の勾配
を測定し、素材の炭素量になるまでの深さを浸炭深さと
し、アセチレン浸炭深さを通常ガス浸炭深さで割った値
である。なお、炭素Ｃ濃度％の勾配の測定はＥＰＭＡ
（電子プローブマイクロアナライザ、島津製作所製ＥＰ
ＭＡ−１６００）を用いて行われた。その結果を図６に
示す。浸炭温度が高くなる程、浸炭深さ比が大きくな
り、１０５０℃以上では、アセチレン浸炭深さは通常ガ
ス浸炭深さの１．５倍以上となる。The carburizing depth ratio is a value obtained by measuring the gradient of the carbon C concentration% of the cross section, taking the depth until the carbon content of the material becomes the carburizing depth, and dividing the acetylene carburizing depth by the normal gas carburizing depth. It is. In addition, the measurement of the gradient of the carbon C concentration% is performed by EPMA.
(Electron probe microanalyzer, EP manufactured by Shimadzu Corporation
MA-1600). FIG. 6 shows the result. As the carburizing temperature increases, the carburizing depth ratio increases. At 1050 ° C. or higher, the acetylene carburizing depth is usually 1.5 times or more the gas carburizing depth.
【０１５２】しかし、アセチレンはメタンやプロパン等
の飽和炭化水素ガスに比べて不安定であり、分解速度も
早いので、２００〜４００Ｔｏｒｒ程度の真空度で行う
一般的な真空浸炭条件では、大量の煤が発生してしまう
ので、真空度を上げ、５Ｔｏｒｒ以下で処理しなければ
ならない。However, acetylene is unstable compared with saturated hydrocarbon gas such as methane and propane, and has a high decomposition rate. Therefore, under general vacuum carburizing conditions performed at a vacuum degree of about 200 to 400 Torr, a large amount of soot is produced. Therefore, it is necessary to increase the degree of vacuum and process at 5 Torr or less.
【０１５３】［真空度と浸炭深さ調査］真空度と浸炭深
さとの関係を調査する際、次の条件でアセチレン浸炭を
行った。[Investigation of Degree of Vacuum and Carburizing Depth] When investigating the relationship between the degree of vacuum and the carburizing depth, acetylene carburizing was performed under the following conditions.
【０１５４】アセチレン浸炭：真空炉中にアセチレン炉
内容積に対して０．１〜０．５％直接導入し、浸炭処理
温度＝９８０〜１０５０℃の条件で０．５〜１時間浸炭
を行い、浸炭終了後に炉内を２００Ｔｏｒｒ以上に復圧
し、浸炭温度を８４０℃以上〜９００℃以下まで下げて
から焼入れを行う。Acetylene carburization: 0.1 to 0.5% of the volume in the acetylene furnace is directly introduced into a vacuum furnace, and carburization is performed for 0.5 to 1 hour at a carburization temperature of 980 to 1050 ° C. After the carburization is completed, the pressure in the furnace is restored to 200 Torr or more, and the quenching is performed after the carburization temperature is reduced to 840 ° C to 900 ° C.
【０１５５】図７にアセチレン浸炭における真空度と浸
炭深さ比（浸炭性能）との関係を示す。０．５Ｔｏｒｒ
での浸炭深さを値１とした場合の浸炭深さ比を示した
が、真空度が５Ｔｏｒｒを越えて低くなると、煤の発生
が激しく、ほとんど浸炭されず、場合によっては浸炭む
らが発生する。一方、真空度を５Ｔｏｒｒ以下にする
と、煤の発生が減少して良好な処理が可能となる。さら
に、１Ｔｏｒｒ以下の高真空である方が浸炭が安定する
傾向にあり、１Ｔｏｒｒ以下での真空浸炭が望ましい。
浸炭深さ比は前述と同様に測定された。FIG. 7 shows the relationship between the degree of vacuum and the carburizing depth ratio (carburizing performance) in acetylene carburizing. 0.5 Torr
The carburization depth ratio when the carburization depth was set to a value of 1 was shown. However, when the degree of vacuum became lower than 5 Torr, soot generation was severe, almost no carburization occurred, and in some cases, uneven carburization occurred. . On the other hand, when the degree of vacuum is set to 5 Torr or less, the generation of soot is reduced, and good processing can be performed. Furthermore, carburization tends to be more stable at a high vacuum of 1 Torr or less, and vacuum carburization at 1 Torr or less is desirable.
The carburization depth ratio was measured as described above.
【０１５６】［熱処理による黒鉛粒微細化および黒鉛面
積率削減］熱処理による黒鉛粒微細化および黒鉛面積率
削減を調査する際、次の条件でアセチレン浸炭を行っ
た。[Refinement of Graphite Grains and Reduction of Graphite Area Ratio by Heat Treatment] When investigating the refinement of graphite particles and reduction of graphite area ratio by heat treatment, acetylene carburization was performed under the following conditions.
【０１５７】アセチレン浸炭：真空炉中にアセチレン炉
内容積に対して０．１〜０．５％直接導入し、炉内圧力
＝０．３〜０．７Ｔｏｒｒの条件で０．５〜１時間浸炭
を行い、浸炭終了後に炉内を２００Ｔｏｒｒ以上に復圧
し、浸炭温度を８４０℃以上〜９００℃以下まで下げて
から焼入れを行う。Acetylene carburization: Directly introduced into a vacuum furnace at 0.1 to 0.5% of the internal volume of the acetylene furnace, and carburized at a furnace pressure of 0.3 to 0.7 Torr for 0.5 to 1 hour. After the carburization is completed, the pressure in the furnace is restored to 200 Torr or more, and the carburizing temperature is reduced to 840 ° C. to 900 ° C. before quenching.
【０１５８】図８にアセチレン浸炭で処理温度を変えた
場合の全黒鉛面積率に対する２μｍ以下の黒鉛面積率を
示す。通常の浸炭温度である９５０℃を越えると、黒鉛
の微細化が効果的に促進されている。したがって、浸炭
温度は９５０℃を越えることが望ましい。FIG. 8 shows the graphite area ratio of 2 μm or less with respect to the total graphite area ratio when the treatment temperature is changed by acetylene carburization. When the temperature exceeds 950 ° C., which is a normal carburizing temperature, the miniaturization of graphite is effectively promoted. Therefore, it is desirable that the carburizing temperature exceeds 950 ° C.
【０１５９】図９にアセチレン浸炭で処理温度を変えた
場合の浸炭温度と黒鉛残留率との関係を示す。通常の浸
炭温度である９５０℃を越えると、黒鉛残留率は５０％
以下となり、素材の黒鉛は微細化されると共に半分以下
の面積になる。FIG. 9 shows the relationship between the carburizing temperature and the graphite residual ratio when the treatment temperature was changed by acetylene carburizing. Exceeding the normal carburizing temperature of 950 ° C, the graphite residual rate becomes 50%
Below, and the graphite of the raw material is miniaturized and has an area of less than half.
【０１６０】［素材の黒鉛面積率と冷間加工性］素材の
黒鉛面積率と冷間加工性の調査では、オートマチックト
ランスミッション内で使用されているピンタイプの軸受
（ころ軸受）の内輪に相当するピンの潤滑用の穴加工で
評価が行われた。図１２は冷間加工性の評価（５段加工
前の状態）を行った試験片であるピンの加工穴を示す断
面図である。ピン１０は直径φ１０ｍｍ、長さ３０ｍｍ
のサイズを有している。そして、下記に示す５段の冷間
加工で４段目まで作られたピンの断面図を示している。
その中心には直径φ３ｍｍの加工穴１０ａ、１０ｂがあ
いており、長さ５ｍｍの未貫通部１０ｃがある。[Graphic Area Ratio of Material and Cold Workability] In the investigation of the graphite area ratio and cold workability of the material, it corresponds to the inner ring of a pin type bearing (roller bearing) used in an automatic transmission. The evaluation was performed in drilling holes for pin lubrication. FIG. 12 is a cross-sectional view showing a machined hole of a pin which is a test piece for which cold workability was evaluated (before five-stage working). Pin 10 is 10mm in diameter and 30mm in length
It has the size of And the sectional view of the pin made to the 4th stage by the following 5 stages of cold working is shown.
At the center thereof, there are processing holes 10a and 10b having a diameter of 3 mm, and a non-penetrating portion 10c having a length of 5 mm.
【０１６１】 加工機：坂村機械製作所製、ＮＦ−５５０ 段数：５段加工（穴開け３段加工） 加工速度：１００〜１５０個／分 加工能力：２６０ｔｏｎ 潤滑剤：杉村科学製、Ｍ−１９００ 金型材質：Ｖ２０（ＪＩＳ Ｂ ４０５３） 冷間加工性の評価は加工機を連続で運転し、５段目で未
貫通部１０ｃを貫通させる工程での金型が破損するまで
の加工数で行われた。その結果を図１０に示す。金型は
穴開けように突き出たパンチが被加工材１０ｂに食い込
み、抜く時にかかる引張り力で破損する場合が多く、黒
鉛を析出させると、硬さの低下と黒鉛の潤滑作用により
冷間加工性が良好となる。図１０に示すように、素材の
黒鉛面積率が５％以上になると、その効果が高くなり、
１０％以上で最良の加工性を示した。Processing machine: NF-550, manufactured by Sakamura Kikai Seisakusho Co., Ltd. Number of steps: 5 steps (drilling 3 steps) Processing speed: 100 to 150 pieces / min. Processing capacity: 260 ton Lubricant: Sugimura Science, M-1900 gold Mold material: V20 (JIS B 4053) The cold workability is evaluated based on the number of processes until the die is broken in the process of operating the processing machine continuously and penetrating the unpenetrated portion 10c at the fifth stage. Was. The result is shown in FIG. In a mold, a punch protruding like a hole cuts into the workpiece 10b and is often damaged by a tensile force applied when the punch is pulled out. When graphite is deposited, the hardness is reduced and the workability of the graphite is reduced due to the lubricating action of the graphite. Is good. As shown in FIG. 10, when the graphite area ratio of the material is 5% or more, the effect is enhanced,
The best workability was exhibited at 10% or more.
【０１６２】［ピーリング損傷や滑り摩耗での寿命評
価］ピーリング損傷や滑り摩耗での寿命評価では、オー
トマチックトランスミッション内で使用されているピン
タイプの軸受（ころ軸受）の内輪に相当するピンに対
し、実際の使用条件を想定した潤滑条件の厳しい試験を
行った。図１３は試験片であるピンのピーリング損傷や
滑り摩耗での寿命評価試験を行う様子を示す図である。
同図（Ａ）に示すように、ころ軸受８は針状ころ９が周
囲に配設された内輪としての試験片であるピン１０を有
し、駆動輪１１に対して試験荷重が外輪１２に加えられ
た状態で接触している。駆動輪１１が回転すると、それ
に伴って外輪１２は摺動回転を行う。[Evaluation of Life due to Peeling Damage or Sliding Wear] In the evaluation of life due to peeling damage or sliding wear, a pin corresponding to the inner ring of a pin type bearing (roller bearing) used in an automatic transmission is evaluated. A rigorous test of lubrication conditions was performed assuming actual use conditions. FIG. 13 is a diagram illustrating a state in which a life evaluation test is performed on a pin as a test piece due to peeling damage or sliding wear.
As shown in FIG. 1A, the roller bearing 8 has a pin 10 which is a test piece as an inner ring around which a needle roller 9 is disposed. It is in contact with it being added. When the drive wheel 11 rotates, the outer wheel 12 performs sliding rotation accordingly.
【０１６３】また、同図（Ｂ）に示すようにピン１０の
中心軸方向およびそれと直交する方向には油路１０ａ、
１０ｃが形成されており、潤滑油は油路１０ａの両端か
ら流入して油路１０ｃへと流出する。このような寿命評
価試験での試験条件はつぎの通りである。As shown in FIG. 17B, the oil passage 10a extends in the direction of the center axis of the pin 10 and in the direction perpendicular thereto.
The lubricating oil flows from both ends of the oil passage 10a and flows out to the oil passage 10c. The test conditions in such a life evaluation test are as follows.
【０１６４】 試験荷重：６０００Ｎ 回転速度：８０００ｒｐｍ 潤滑条件：潤滑油、トヨタ自動車製、キャッスルオート
フルードＤ−II、強制潤滑供給方法（１００ｍｌ／分） 試験結果を表７および図１４に示す。図１４は完成品の
黒鉛面積率に対するピン回転Ｌ１０寿命との関係を示す
特性図である。Test load: 6000 N Rotation speed: 8000 rpm Lubrication condition: lubricating oil, manufactured by Toyota Automobile, Castle Auto Fluid D-II, forced lubrication supply method (100 ml / min) The test results are shown in Table 7 and FIG. FIG. 14 is a characteristic diagram showing the relationship between the graphite area ratio of the finished product and the pin rotation L10 life.
【０１６５】[0165]
【表７】 本実施例では、素材の黒鉛を多めに析出させることで冷
間鍛造（加工）性良好とし、高真空で浸炭を行うことで
効果的に黒鉛粒を微細化することによりピーリング損傷
や滑り摩耗で長寿命が得られる。[Table 7] In the present embodiment, the cold forging (working) property is improved by precipitating a large amount of graphite of the material, and the graphite particles are effectively refined by carburizing in a high vacuum to thereby reduce peeling damage and sliding wear. Long life can be obtained.
【０１６６】一方、素材の黒鉛面積率が５％未満である
比較例としてのＮＯ．２０２、２０３、２０４、２０
５、２０６は冷間鍛造性が低下してしまい、また、比較
例としてのＮＯ．２０７、２０８は素材の黒鉛面積率を
１０％以上とし、冷間鍛造性が良好でも、熱処理条件に
よっては完成品の黒鉛面積率が１０％を越えると、硬さ
の低下や黒鉛粒の粗大化によりピーリング損傷や滑り摩
耗での寿命が低下してしまう。On the other hand, as a comparative example in which the graphite area ratio of the material was less than 5%, NO. 202, 203, 204, 20
Nos. 5 and 206 have poor cold forgeability, and NO. In 207 and 208, the graphite area ratio of the material is 10% or more. Even if the cold forgeability is good, depending on the heat treatment conditions, if the graphite area ratio of the finished product exceeds 10%, the hardness decreases and the graphite grains become coarse. As a result, the life due to peeling damage and sliding wear is reduced.
【０１６７】さらに、図１４に示すように、完成品の黒
鉛面積率が５％以下でピーリング損傷や滑り摩耗が長寿
命となるが、４％以下で寿命が安定する。一方、完成品
の黒鉛面積率が１％未満になると、寿命が低下する傾向
を示した。これは、微細な残留黒鉛粒が潤滑条件の厳し
い中で油溜まりとなって潤滑を助ける効果が得られなく
なるからである。したがって、オートマチックトランス
ミッション内で使用されている等の潤滑条件の厳しい場
合、完成品の黒鉛面積率が２％以上４％以下であること
が望ましい。Further, as shown in FIG. 14, when the graphite area ratio of the finished product is 5% or less, the peeling damage and the sliding wear are long, but when the graphite area ratio is 4% or less, the life is stabilized. On the other hand, when the graphite area ratio of the finished product was less than 1%, the life tended to decrease. This is because the fine residual graphite particles form an oil reservoir under severe lubrication conditions, and the effect of assisting lubrication cannot be obtained. Therefore, when lubrication conditions are severe such as those used in automatic transmissions, it is desirable that the graphite area ratio of the finished product is 2% or more and 4% or less.
【０１６８】このように本実施例では、素材を黒鉛化す
ることで被削性を著しく向上させると共に、並径サイズ
の軸受が実際に使用されている状況やオートマチックト
ランスミッション内で実際に使用されている軸受を再現
して評価し、軸受完成品表面の黒鉛粒をコントロールす
ることにより、クリーン潤滑や異物混入潤滑下やピーリ
ング発生に対して長寿命である軸受を安価に提供するこ
とができる。As described above, in this embodiment, the machinability is remarkably improved by graphitizing the material, and at the same time, the bearing having the same diameter is actually used or the bearing is actually used in the automatic transmission. By reproducing and evaluating the bearings and controlling the graphite particles on the surface of the finished bearings, it is possible to provide a low-cost bearing that has a long life under clean lubrication, lubrication with contaminants, and peeling.
【０１６９】次に、トロイダル形無段変速機に適用され
る転動部材について説明する。図１５はトロイダル形無
段変速機の構造を示す断面図である。トロイダル形無段
変速機は、ハウジング内に入力ディスク３１と出力ディ
スク３２とが同軸上に対向して配置された構造を有す
る。入力ディスク３１および出力ディスク３２を備えた
トロイダル変速部の軸心部分には、入力軸３３が貫通さ
れている。Next, a rolling member applied to the toroidal type continuously variable transmission will be described. FIG. 15 is a sectional view showing the structure of the toroidal type continuously variable transmission. The toroidal-type continuously variable transmission has a structure in which an input disk 31 and an output disk 32 are coaxially arranged in a housing. An input shaft 33 passes through an axial portion of the toroidal transmission unit including the input disk 31 and the output disk 32.
【０１７０】この入力軸３３の一端にはローディングカ
ム１４が設けられており、このローディングカム１４は
カムローラ１５を介して入力ディスク３１に入力軸３３
の動力（回転力）を伝達する構造となっている。[0170] A loading cam 14 is provided at one end of the input shaft 33. The loading cam 14 is connected to the input disk 31 via the cam roller 15 by the input shaft 33.
This is a structure that transmits the power (rotational force) of the motor.
【０１７１】入力ディスク３１および出力ディスク３２
は略同一形状で対称に配置されており、それらの対向面
は協働して軸方向断面で略半円形となるようにトロイダ
ル面に形成されている。Input disk 31 and output disk 32
Are arranged symmetrically in substantially the same shape, and their opposing surfaces are formed in a toroidal surface so as to cooperate to form a substantially semicircular cross section in the axial direction.
【０１７２】そして、入力ディスク３１および出力ディ
スク３２のトロイダル面で形成されるトロイダルキャビ
ティ内に、入力ディスク３１および出力ディスク３２に
接して一対の運動伝達用のパワーローラ軸受１６、１７
が配設されている。パワーローラ軸受１６、１７はスラ
スト軸受２３を有する。In a toroidal cavity formed by the toroidal surfaces of the input disk 31 and the output disk 32, a pair of power roller bearings 16 and 17 for transmitting motion are in contact with the input disk 31 and the output disk 32.
Are arranged. The power roller bearings 16 and 17 have a thrust bearing 23.
【０１７３】また、パワーローラ軸受１６、１７は、枢
軸１８、１９を介してトラニオン２０、２１に回転自在
に枢着され、かつ入力ディスク３１および出力ディスク
３２のトロイダル面の中心となるピボット軸Ｏを中心と
して傾転自在に支持されている。The power roller bearings 16 and 17 are rotatably connected to the trunnions 20 and 21 via pivots 18 and 19, respectively, and are pivot shafts O serving as centers of toroidal surfaces of the input disk 31 and the output disk 32. It is supported so that it can tilt around the center.
【０１７４】入力ディスク３１および出力ディスク３２
と、パワーローラ軸受１６、１７との接触面には粘性摩
擦抵抗の大きい潤滑油が供給され、入力ディスク３１に
入力される動力を潤滑油膜およびパワーローラ軸受１
６、１７を介して出力ディスク３２に伝達する構造とな
っている。Input disk 31 and output disk 32
The lubricating oil having a large viscous friction resistance is supplied to the contact surfaces of the power roller bearings 16 and 17, and the power input to the input disk 31 is transferred to the lubricating oil film and the power roller bearing 1.
The structure is such that the signal is transmitted to the output disk 32 via the channels 6 and 17.
【０１７５】入力ディスク３１および出力ディスク３２
は、ニードル２５を介して入力軸３３と独立した状態
（入力軸３３の回転動力に直接影響されない状態）とな
っている。出力ディスク３２には入力軸３３と平行に配
設され、かつアンギュラ軸受２２を介してハウジングに
回転自在に支持された出力軸２４が設けられている。Input disk 31 and output disk 32
Are in a state independent of the input shaft 33 via the needle 25 (a state not directly affected by the rotational power of the input shaft 33). The output disk 32 is provided with an output shaft 24 disposed parallel to the input shaft 33 and rotatably supported by the housing via an angular bearing 22.
【０１７６】このトロイダル形無段変速機では、入力軸
３３の動力がローディングカム１４に伝達される。この
動力の伝達により、ローディングカム１４が回転する
と、この動力がカムローラ１５を介して入力ディスク３
１に伝達され、入力ディスク３１が回転する。入力ディ
スク３１の回転により発生した動力は、パワーローラ軸
受１６、１７を介して出力ディスク３２に伝達される。
出力ディスク３２は出力軸２４と一体となって回転す
る。In this toroidal type continuously variable transmission, the power of the input shaft 33 is transmitted to the loading cam 14. When the loading cam 14 is rotated by the transmission of the power, the power is transmitted to the input disk 3 via the cam roller 15.
1 and the input disk 31 rotates. The power generated by the rotation of the input disk 31 is transmitted to the output disk 32 via the power roller bearings 16 and 17.
The output disk 32 rotates integrally with the output shaft 24.
【０１７７】変速時、２つのトラニオン２０、２１をピ
ボット軸Ｏを中心に軸方向に微小距離移動させる。すな
わち、このトラニオン２０、２１の軸方向移動により、
パワーローラ軸受１６、１７の回転軸と、入力ディスク
３１および出力ディスク３２の軸との交差が外れる。こ
のため、パワーローラ軸受１６、１７が、入力ディスク
３１および出力ディスク３２の曲面上を傾転し、その結
果、速度比が変わり、減速または増速が行われる。At the time of shifting, the two trunnions 20 and 21 are moved a small distance in the axial direction about the pivot axis O. That is, by the axial movement of the trunnions 20, 21,
The intersections between the rotation axes of the power roller bearings 16 and 17 and the axes of the input disk 31 and the output disk 32 are out of alignment. For this reason, the power roller bearings 16 and 17 tilt on the curved surfaces of the input disk 31 and the output disk 32, and as a result, the speed ratio changes, and the speed is reduced or increased.
【０１７８】［実施例］疲労寿命試験は、図１５に示す
トロイダル形無段変速機３０のパワーローラ軸受１６、
１７の内輪１６ａ、１７ａおよび外輪１６ｂ、１７ｂ、
入力ディスク３１および出力ディスク３２と同様の構造
のもので行われた。[Example] The fatigue life test was performed on the power roller bearing 16 of the toroidal type continuously variable transmission 30 shown in FIG.
17 inner rings 16a, 17a and outer rings 16b, 17b,
The test was performed with the same structure as the input disk 31 and the output disk 32.
【０１７９】図１６は試験片を製作する際の種々の熱処
理条件を示す図である。表８に示すそれぞれの材料を用
い、図１６に示す各熱処理を行った後、一部の試験片に
はショットピーニングを行い、表９および表１０に示す
ような１７種類の試験片を製作する。FIG. 16 is a diagram showing various heat treatment conditions when producing a test piece. After performing the respective heat treatments shown in FIG. 16 using the respective materials shown in Table 8, shot peening is performed on some of the test pieces to produce 17 types of test pieces as shown in Tables 9 and 10. .
【０１８０】また、入力ディスクおよび出力ディスクの
トラクション面となる部分については研削仕上げを行う
（研磨後、超仕上げ）。Further, a portion to be a traction surface of the input disk and the output disk is ground and finished (after polishing, super finished).
【０１８１】[0181]
【表８】 [Table 8]
【０１８２】[0182]
【表９】 [Table 9]
【０１８３】[0183]
【表１０】 （熱処理条件Ｉ）熱処理条件Ｉでは、温度が９３０〜９
６０℃の真空雰囲気下の炉内に試験片を入れ、均熱後ア
セチレンを０．５Ｔｏｒｒまで導入して圧力制御を行い
ながら浸炭を行い、引き続き真空下で拡散処理を行い、
合わせて２０〜３０時間の処理を行った（浸炭処理）
後、放冷（または焼入れ）を行い、次に温度が８４０〜
８６０℃の真空下で０．５〜１時間熱処理した後、オイ
ルクエンチを行い、次に温度が１６０〜１８０℃の大気
中で２時間加熱した後、冷却する（焼戻し）。[Table 10] (Heat treatment condition I) In the heat treatment condition I, the temperature was 930 to 9
The test piece was placed in a furnace under a vacuum atmosphere at 60 ° C., and after soaking, acetylene was introduced to 0.5 Torr and carburizing was performed while controlling the pressure, followed by diffusion treatment under vacuum,
A total of 20 to 30 hours of treatment (carburizing treatment)
After that, it is allowed to cool (or harden),
After heat treatment under vacuum at 860 ° C. for 0.5 to 1 hour, oil quenching is performed, and then heating is performed in air at a temperature of 160 to 180 ° C. for 2 hours, followed by cooling (tempering).
【０１８４】（熱処理条件II）熱処理条件IIでは、温度
が９３０〜９６０℃のＲＸガス、エンリッチガス、アン
モニア（ＮＨ3）ガス雰囲気で２０〜３０時間熱処理
（浸炭窒化処理）した後、放冷を行い、次に温度が８４
０〜８６０℃のＲＸガス雰囲気で０．５〜１時間熱処理
した後、オイルクエンチを行い、次に温度が１６０〜１
８０℃の大気中で２時間加熱した後、冷却する（焼戻
し）。(Heat treatment condition II) In heat treatment condition II, after heat treatment (carbonitriding treatment) for 20 to 30 hours in an atmosphere of RX gas, enriched gas, and ammonia (NH 3 ) gas at a temperature of 930 to 960 ° C. And then at 84
After heat-treating for 0.5 to 1 hour in an RX gas atmosphere at 0 to 860 ° C, oil quenching is performed,
After heating in the air at 80 ° C. for 2 hours, it is cooled (tempering).
【０１８５】（熱処理条件III）熱処理条件IIIでは、温
度が９３０〜９６０℃のＲＸガスおよびエンリッチガス
雰囲気で２０〜３０時間熱処理（浸炭処理）した後、放
冷を行い、次に温度が８４０〜８６０℃のＲＸガス雰囲
気で０．５〜１時間熱処理した後、オイルクエンチを行
い、次に温度が１６０〜１８０℃の大気中で２時間加熱
した後、冷却する（焼戻し）。(Heat Treatment Condition III) In heat treatment condition III, after heat treatment (carburizing treatment) in an atmosphere of RX gas and enriched gas at a temperature of 930 to 960 ° C. for 20 to 30 hours, cooling is carried out, and then a temperature of 840 to 840 ° C. After heat treatment in an RX gas atmosphere at 860 ° C. for 0.5 to 1 hour, oil quenching is performed, and then heating is performed in air at a temperature of 160 to 180 ° C. for 2 hours, followed by cooling (tempering).
【０１８６】（熱処理条件IV）熱処理条件IVでは、温度
が８４０〜８６０℃のＲＸガス雰囲気で０．５〜１時間
熱処理した後、オイルクエンチを行い、次に温度が１６
０〜１８０℃の大気中で２時間加熱した後、冷却する
（焼戻し）。(Heat Treatment Condition IV) In heat treatment condition IV, after heat treatment in an RX gas atmosphere at a temperature of 840 to 860 ° C. for 0.5 to 1 hour, oil quenching is performed, and
After heating in the air at 0 to 180 ° C. for 2 hours, it is cooled (tempering).
【０１８７】次に、表９に示したそれぞれの試験片のう
ち、１４種類（実施例１〜７、比較例１〜６、従来例
１）について残留応力（Ｋｇｆ／ｍｍ2）を測定した。
この結果を表９に合わせて示した。ここで、残留応力の
値でマイナス（−）は圧縮を示し、プラス（＋）は引っ
張りを示す。さらに、表９に示す１４種類の試験片につ
いて熱処理後の黒皮状態でミクロ組織観察を行い、最表
面付近の粒界酸化層を観察し、その深さを求めた。Next, among the test pieces shown in Table 9, the residual stress (Kgf / mm 2 ) was measured for 14 types (Examples 1 to 7, Comparative Examples 1 to 6, and Conventional Example 1).
The results are shown in Table 9. Here, in the value of the residual stress, minus (-) indicates compression and plus (+) indicates tension. Further, microstructure observation was performed on the 14 kinds of test pieces shown in Table 9 in a black scale state after the heat treatment, a grain boundary oxide layer near the outermost surface was observed, and the depth was obtained.
【０１８８】また、表８に示す３種類の材料（Ｂ、Ｄ、
Ｅ）を用い、熱処理後にショットピーニング処理を追加
実施した３種類の試験片（比較例７、８、９）を製作し
たものを、前述の表１０に示した。In addition, three types of materials (B, D,
Table 10 shows three types of test pieces (Comparative Examples 7, 8, and 9) in which shot peening was additionally performed after the heat treatment using E).
【０１８９】上記試験片（実施例１〜７、比較例１〜
９、従来例１）を用い、寿命評価を下記条件で行った。The test pieces (Examples 1 to 7, Comparative Examples 1 to 7)
9, the life was evaluated under the following conditions using Conventional Example 1).
【０１９０】［調査条件］ 入力軸の回転数 ４０００ｒｐｍ 入力トルク ３９２Ｎ・ｍ 使用オイル 合成潤滑油 オイル温度 １００℃ 寿命の評価は、それぞれの試験片で構成されるパワーロ
ーラ軸受の外輪、入力ディスクおよび出力ディスクのい
ずれかに剥離が発生するまでの時間、あるいはパワーロ
ーラ軸受の外輪、入力ディスクおよび出力ディスクのい
ずれかに疲労割れが発生するまでの時間をもって決定さ
れた。[Survey conditions] Revolution of input shaft 4000 rpm Input torque 392 N · m Oil used Synthetic lubricating oil Oil temperature 100 ° C. The life was evaluated by the outer ring, input disk and output of the power roller bearing composed of each test piece. It was determined by the time until peeling occurred on any of the disks or the time until fatigue cracking occurred on any of the outer ring of the power roller bearing, the input disk, and the output disk.
【０１９１】また、試験中、上記転動部材に剥離等が発
生した場合、転動部材を新規なものと入れ替えて試験を
続行した。また、試験は１００時間で打ち切りとした。
これらの結果を表９に合わせて示した。In the case where peeling or the like occurred in the rolling member during the test, the rolling member was replaced with a new one, and the test was continued. The test was terminated after 100 hours.
The results are shown in Table 9.
【０１９２】表９より熱処理に真空浸炭処理を行った材
料Ｂ、Ｃ、Ｄ、Ｅ、Ｆ、Ｇのいずれにおいても熱処理後
の黒皮状態では粒界酸化層は認められず、疲労割れ寿命
が１００Ｈｒを越えても剥離、破損は生じなかった（実
施例１〜６）。Table 9 shows that in any of the materials B, C, D, E, F, and G, which were subjected to vacuum carburizing for the heat treatment, no grain boundary oxide layer was observed in the black scale state after the heat treatment, and the fatigue crack life was increased. No peeling or breakage occurred even when it exceeded 100 hours (Examples 1 to 6).
【０１９３】しかしながら、上記と同じ材料を用いた熱
処理において、ガス浸炭およびガス浸炭窒化を行ったも
のでは、熱処理後の黒皮状態で粒界酸化層が認められ、
疲労割れ寿命は短くなっていることが分かる（比較例１
〜６）。However, in the case of performing gas carburizing and gas carbonitriding in the heat treatment using the same material as described above, a grain boundary oxide layer was observed in a black scale state after the heat treatment.
It can be seen that the fatigue crack life is shortened (Comparative Example 1)
~ 6).
【０１９４】これらはいずれの場合も、図１５に示すデ
ィスクの「ア」部分または「イ」部分から破損してお
り、起点は粒界酸化層からであった。In each case, the disk was broken from the "A" portion or the "A" portion of the disk shown in FIG. 15, and the starting point was from the grain boundary oxide layer.
【０１９５】また、材料Ｈを用いて真空浸炭を行ったも
の（実施例７）では、熱処理後の黒皮状態で粒界酸化層
が認められず、疲労割れ寿命は上記ガス浸炭またはガス
浸炭窒化を行った比較例よりは長かったものの、「ア」
部分および「イ」部分からディスクが破損した。In the case of vacuum carburizing using the material H (Example 7), no grain boundary oxide layer was observed in the black scale state after the heat treatment, and the fatigue crack life was determined by the gas carburizing or gas carbonitriding. Although it was longer than the comparative example,
The disk was damaged from the part and the "a" part.
【０１９６】これは、実施例１〜６（材料Ｂ〜Ｇ）では
その炭素量（０．１５〜０．６５重量％）と、浸炭され
た表面層部の炭素量（０．８〜１．２重量％）との差に
より表面に２０Ｋｇｆ／ｍｍ2以上の圧縮残留応力が生
じていたが、材料Ｈ（炭素量０．７重量％）を用いた実
施例７の場合、圧縮残留応力が２０Ｋｇｆ／ｍｍ2未満
であったことにより、疲労割れ寿命が短くなった。This is because, in Examples 1 to 6 (materials B to G), the carbon content (0.15 to 0.65% by weight) and the carbon content of the carburized surface layer portion (0.8 to 1. 2% by weight), a compressive residual stress of 20 kgf / mm 2 or more was generated on the surface. In the case of Example 7 using the material H (0.7% by weight of carbon), the compressive residual stress was 20 kgf / mm 2. / Mm 2 , the fatigue crack life was shortened.
【０１９７】また、ＳＵＪ２を材料に用いた従来例１で
は、熱処理雰囲気にＲＸガスを使用しており、ガス浸炭
やガス浸炭窒化に比べて熱処理時間は短いため、深さは
短くなるものの、粒界酸化層が生じてしまい、さらには
ずぶ焼き鋼のため、表面には圧縮残留応力が生じないこ
とから疲労割れ寿命は非常に短い結果となることが分か
る。寿命は「ア」部からディスクが破損したのに加え、
パワーローラ軸受の外輪も接触面に剥離を起こした。Further, in the conventional example 1 using SUJ2 as a material, RX gas is used as a heat treatment atmosphere, and the heat treatment time is shorter than that of gas carburizing or gas carbonitriding. Since a boundary oxide layer is formed, and furthermore, since the steel is baking steel, no compressive residual stress is generated on the surface, it can be seen that the fatigue crack life is very short. As for the life, in addition to the disk being damaged from the "A" part,
The outer ring of the power roller bearing also peeled off on the contact surface.
【０１９８】表１０には、表８の３種類の材料Ｂ、Ｄ、
Ｅを用い、ガス浸炭窒化を行った試験片について熱処理
後に入力ディスク、出力ディスクおよびパワーローラ軸
受の内輪、外輪にショットピーニング処理を行った比較
例７〜９の寿命試験結果が、同材料を用いて真空浸炭処
理を行った上記実施例１〜３と共に示されている。Table 10 shows that the three types of materials B, D, and
The life test results of Comparative Examples 7 to 9 in which shot peening was performed on the inner and outer rings of the input disk, output disk, and power roller bearing after heat treatment of the test piece subjected to gas carbonitriding using E, using the same material, Along with the above Examples 1 to 3 in which a vacuum carburizing treatment was performed.
【０１９９】ガス浸炭窒化を行った試験片（比較例７〜
９）においても、ショットピーニング処理を行うことで
疲労割れ寿命は１００時間（Ｈｒ）以上と長くなること
が分かる。しかしながら、真空浸炭処理を行った実施例
と比較すると、ショットピーニングを行うことでコスト
アップとなってしまう。Test pieces subjected to gas carbonitriding (Comparative Examples 7 to
Also in 9), it can be seen that the fatigue crack life is increased to 100 hours (Hr) or more by performing the shot peening treatment. However, compared to the embodiment in which the vacuum carburizing treatment is performed, the cost is increased by performing the shot peening.
【０２００】このように、トロイダル形無段変速機の入
力ディスク、出力ディスクおよびパワーローラ軸受の内
輪、外輪にアセチレン真空浸炭を行うことで、表面の粒
界酸化を防止でき、繰り返し曲げ応力がかかることによ
る疲労割れが生じやすいということで問題となっていた
上記部品の割れ強度を安価に向上させることができる。
また、ショットピーニングを行う必要がなくなる。As described above, by performing acetylene vacuum carburization on the input and output disks of the toroidal type continuously variable transmission and the inner and outer rings of the power roller bearings, it is possible to prevent the surface from intergranular oxidation and to apply bending stress repeatedly. Therefore, the crack strength of the above-mentioned parts, which has been a problem because fatigue cracks are easily caused, can be improved at low cost.
Also, it is not necessary to perform shot peening.
【０２０１】尚、トロイダル形無段変速機では、アセチ
レン真空浸炭法を用いた場合を示したが、アセチレンを
用いずに粒界酸化の少ない真空浸炭法および真空焼入れ
でも同様にトロイダル形無段変速機の入出力ディスク、
パワーローラ軸受の長寿命、コスト低減に効果がある。In the toroidal type continuously variable transmission, the case where the acetylene vacuum carburizing method is used is shown. Machine input / output disk,
Effective for long life and cost reduction of power roller bearings.
【０２０２】また、アセチレン真空浸炭後、窒化ガスを
供給し、炭素の拡散に続いて窒化を行うアセチレン浸炭
窒化法で行っても、粒界酸化を防止し、上記と同様の効
果がある。[0202] Further, even if the acetylene carbonitriding method in which a nitriding gas is supplied after acetylene vacuum carburizing and nitriding is performed after carbon diffusion is performed, grain boundary oxidation is prevented, and the same effect as described above can be obtained.
【０２０３】[0203]
【発明の効果】本発明の請求項１に記載の転がり軸受に
よれば、内輪、外輪および転動体の少なくとも１つに浸
炭または浸炭窒化処理を行った素材が適用される転がり
軸受において、前記素材は、炭素０．４５〜０．９重量
％、シリコン０．５〜１．５重量％、マンガン０．３〜
１．５重量％およびクロム０．７重量％以下を含有し、
残りが鉄および不純物元素からなる合金であり、前記素
材に対して黒鉛化処理を行って微細黒鉛を析出させてお
き、完成品表面における黒鉛の面積率を５％以下とし、
平均粒径５μｍ以上の大形黒鉛粒が全黒鉛に対して面積
率で２％以下であり、かつ平均粒径２μｍ以下の微細黒
鉛粒が全黒鉛に対して面積率で５０％以上であり、完成
品表面層における炭素量および窒素量がそれぞれ０．９
〜１．４重量％および０．０１〜０．３重量％であるの
で、素材を黒鉛化することで被削性を著しく向上させる
と共に、高真空で短時間の浸炭を行うことで低コストで
ありながら、クリーン潤滑や異物混入潤滑下で、さらに
はピーリング損傷や滑り摩耗に対して長寿命である転が
り軸受を提供することができる。According to the rolling bearing according to the first aspect of the present invention, in the rolling bearing, at least one of the inner ring, the outer ring, and the rolling element is subjected to a carburizing or carbonitriding process. Is carbon 0.45 to 0.9 wt%, silicon 0.5 to 1.5 wt%, manganese 0.3 to
1.5% by weight and not more than 0.7% by weight of chromium,
The remainder is an alloy consisting of iron and impurity elements, the material is subjected to a graphitization process to precipitate fine graphite, and the area ratio of graphite on the finished product surface is set to 5% or less,
Large graphite particles having an average particle size of 5 μm or more have an area ratio of 2% or less with respect to the total graphite, and fine graphite particles having an average particle size of 2 μm or less have an area ratio of 50% or more with respect to the total graphite, The carbon content and nitrogen content in the finished product surface layer are 0.9
Since the content is about 1.4% by weight and 0.01% to 0.3% by weight, the machinability is remarkably improved by graphitizing the material, and the carburizing is performed at high vacuum for a short time to reduce the cost. In spite of this, it is possible to provide a rolling bearing that has a long service life under clean lubrication or lubrication mixed with foreign matters, and also against peeling damage and sliding wear.
【図１】素材の黒鉛面積率と切削工具寿命との関係を示
す特性図である。FIG. 1 is a characteristic diagram showing a relationship between a graphite area ratio of a material and a life of a cutting tool.
【図２】全黒鉛に対する５μｍ以上の黒鉛の面積率と寿
命との関係を示す特性図である。FIG. 2 is a characteristic diagram showing a relationship between an area ratio of graphite of 5 μm or more to total graphite and life.
【図３】完成品表面の黒鉛の面積率と硬さとの関係を示
す特性図である。FIG. 3 is a characteristic diagram showing a relationship between graphite area ratio and hardness on a finished product surface.
【図４】黒鉛粒の上にビッカース圧痕が重なった様子を
示す図である。FIG. 4 is a view showing a state in which Vickers indentations are superimposed on graphite particles.
【図５】微小異物混入潤滑下での寿命と平均粒径２μｍ
以下の黒鉛粒の面積率との関係を示す特性図である。FIG. 5: Life under lubrication mixed with minute foreign matter and average particle diameter of 2 μm
FIG. 4 is a characteristic diagram showing a relationship with the following area ratio of graphite particles.
【図６】同一条件での通常のガス浸炭と真空浸炭との浸
炭深さ比を浸炭温度に対して示す特性図である。FIG. 6 is a characteristic diagram showing a carburizing depth ratio between normal gas carburizing and vacuum carburizing under the same conditions with respect to carburizing temperature.
【図７】アセチレン浸炭における真空度と浸炭深さ比と
の関係を示す特性図である。FIG. 7 is a characteristic diagram showing a relationship between a degree of vacuum and a carburization depth ratio in acetylene carburization.
【図８】浸炭温度と２μｍ以下の黒鉛面積率との関係を
示す特性図である。FIG. 8 is a characteristic diagram showing a relationship between a carburizing temperature and a graphite area ratio of 2 μm or less.
【図９】浸炭温度と黒鉛残留率との関係を示す図であ
る。FIG. 9 is a graph showing the relationship between carburizing temperature and graphite residual ratio.
【図１０】素材の黒鉛面積率に対する冷間加工性を示す
特性図である。FIG. 10 is a characteristic diagram showing cold workability with respect to a graphite area ratio of a material.
【図１１】黒鉛化処理条件を示す図である。FIG. 11 is a diagram showing graphitization treatment conditions.
【図１２】冷間加工性の評価（５段加工前の状態）を行
った試験片であるピンの加工穴を示す断面図である。FIG. 12 is a cross-sectional view showing a processing hole of a pin which is a test piece on which cold workability was evaluated (a state before five-step processing).
【図１３】試験片であるピンのピーリング損傷や滑り摩
耗での寿命評価試験を行う様子を示す図である。FIG. 13 is a diagram showing a state in which a life evaluation test is performed on a pin as a test piece due to peeling damage or sliding wear.
【図１４】完成品の黒鉛面積率に対するピン回転Ｌ１０
寿命との関係を示す特性図である。FIG. 14: Pin rotation L10 with respect to the graphite area ratio of the finished product
It is a characteristic view which shows the relationship with a service life.
【図１５】トロイダル形無段変速機の構造を示す断面図
である。FIG. 15 is a sectional view showing a structure of a toroidal-type continuously variable transmission.
【図１６】試験片を製作する際の種々の熱処理条件を示
す図である。FIG. 16 is a view showing various heat treatment conditions when producing a test piece.
８ ころ軸受 １０ ピン １６、１７ パワーローラ軸受 ３１ 入力ディスク ３２ 出力ディスク ３３ 入力軸 8 Roller bearing 10 Pin 16, 17 Power roller bearing 31 Input disk 32 Output disk 33 Input shaft
Claims (1)
つに浸炭または浸炭窒化処理を行った素材が適用される
転がり軸受において、 前記素材は、炭素０．４５〜０．９重量％、シリコン
０．５〜１．５重量％、マンガン０．３〜１．５重量％
およびクロム０．７重量％以下を含有し、残りが鉄およ
び不純物元素からなる合金であり、 前記素材に対して黒鉛化処理を行って微細黒鉛を析出さ
せておき、 完成品表面における黒鉛の面積率を５％以下とし、 平均粒径５μｍ以上の大形黒鉛粒が全黒鉛に対して面積
率で２％以下であり、かつ平均粒径２μｍ以下の微細黒
鉛粒が全黒鉛に対して面積率で５０％以上であり、 完成品表面層における炭素量および窒素量がそれぞれ
０．９〜１．４重量％および０．０１〜０．３重量％で
あることを特徴とする転がり軸受。At least one of an inner ring, an outer ring and a rolling element
In a rolling bearing to which a material subjected to carburizing or carbonitriding is applied, the material is carbon 0.45 to 0.9% by weight, silicon 0.5 to 1.5% by weight, manganese 0.3 to 0.3%. 1.5% by weight
And an alloy containing 0.7% by weight or less of chromium and the balance consisting of iron and impurity elements. The material is subjected to a graphitization treatment to precipitate fine graphite, and the area of graphite on the surface of the finished product The ratio of large graphite particles having an average particle size of 5 μm or more to the total graphite is 2% or less, and the ratio of fine graphite particles having an average particle size of 2 μm or less to the total graphite is 5% or less. Wherein the amount of carbon and the amount of nitrogen in the surface layer of the finished product are 0.9 to 1.4% by weight and 0.01 to 0.3% by weight, respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4639198A JPH11193823A (en) | 1997-07-10 | 1998-02-13 | Rolling bearing |
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20074597 | 1997-07-10 | ||
| JP9-200745 | 1997-10-30 | ||
| JP31291697 | 1997-10-30 | ||
| JP9-312916 | 1997-10-30 | ||
| JP4639198A JPH11193823A (en) | 1997-07-10 | 1998-02-13 | Rolling bearing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11193823A true JPH11193823A (en) | 1999-07-21 |
Family
ID=27292590
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4639198A Withdrawn JPH11193823A (en) | 1997-07-10 | 1998-02-13 | Rolling bearing |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11193823A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006200720A (en) * | 2005-01-24 | 2006-08-03 | Ntn Corp | Thrust bearing for continuously variable transmission |
| JP2006200719A (en) * | 2005-01-24 | 2006-08-03 | Ntn Corp | Thrust bearing for compressor of car air conditioner |
| JP2006200724A (en) * | 2005-01-24 | 2006-08-03 | Ntn Corp | Thrust bearing for automatic transmission |
| US7677810B2 (en) | 2005-01-21 | 2010-03-16 | Ntn Corporation | Bearing washer for thrust bearing and thrust bearing |
| WO2012018239A3 (en) * | 2010-08-06 | 2012-05-03 | 주식회사 포스코 | High carbon chromium bearing steel, and preparation method thereof |
-
1998
- 1998-02-13 JP JP4639198A patent/JPH11193823A/en not_active Withdrawn
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7677810B2 (en) | 2005-01-21 | 2010-03-16 | Ntn Corporation | Bearing washer for thrust bearing and thrust bearing |
| JP2006200720A (en) * | 2005-01-24 | 2006-08-03 | Ntn Corp | Thrust bearing for continuously variable transmission |
| JP2006200719A (en) * | 2005-01-24 | 2006-08-03 | Ntn Corp | Thrust bearing for compressor of car air conditioner |
| JP2006200724A (en) * | 2005-01-24 | 2006-08-03 | Ntn Corp | Thrust bearing for automatic transmission |
| WO2012018239A3 (en) * | 2010-08-06 | 2012-05-03 | 주식회사 포스코 | High carbon chromium bearing steel, and preparation method thereof |
| KR101271899B1 (en) * | 2010-08-06 | 2013-06-05 | 주식회사 포스코 | High carbon and chromium bearing steel and method for manufacturing the same |
| JP2013537586A (en) * | 2010-08-06 | 2013-10-03 | ポスコ | High carbon chromium bearing steel and manufacturing method thereof |
| US9062359B2 (en) | 2010-08-06 | 2015-06-23 | Posco | High carbon chromium bearing steel, and preparation method thereof |
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