JP2014088893A5

JP2014088893A5 -

Info

Publication number: JP2014088893A5
Application number: JP2012238231A
Authority: JP
Filing date: 2012-10-29
Publication date: 2015-12-03

Description

本発明の対象となる転がり軸受は、それぞれが円環状で互いに同心に配置され、互いに対向する面にそれぞれ軌道面を設けた１対の軌道輪と、これら両軌道面同士の間に転動自在に配置された複数個の転動体とを備える。
特に、本発明の転がり軸受に於いては、前記両軌道輪と前記各転動体との３種類の軸受構成部品のうちの少なくとも１種類の軸受構成部品（例えばラジアル転がり軸受の内輪の如く、転がり疲れ寿命確保の面から最も条件が厳しくなる部品、好ましくは１対の軌道輪、更に好ましくは総ての軸受構成部品）を、相手部材と転がり接触する、この転がり接触面から深さ１００μｍまでの範囲である表面層部分の残留オーステナイト量（残留γ）を１２〜４０容量％とすると共に、当該軸受構成部品の鋼中水素濃度を０．５ｐｐｍ以下としている。尚、前記残留オーステナイト量を、好ましくは１５〜４０容量％、より好ましくは２０〜４０容量％とする。又、前記鋼中水素濃度を、好ましくは０．３ｐｐｍ以下とする。 The rolling bearings that are the subject of the present invention are a pair of race rings, each of which is annular and concentrically arranged and provided with raceway surfaces facing each other, and can freely roll between these raceway surfaces. And a plurality of rolling elements arranged in the.
In particular, in the rolling bearing according to the present invention, at least one type of bearing component (for example, an inner ring of a radial rolling bearing) of at least one of the three types of bearing components of the both race rings and the rolling elements. The parts whose conditions are most severe in terms of ensuring the fatigue life, preferably a pair of race rings, and more preferably all bearing components) are brought into rolling contact with the mating member. From the rolling contact surface to a depth of 100 μm The amount of retained austenite (residual γ) in the surface layer portion in the range is set to 12 to 40% by volume, and the hydrogen concentration in the steel of the bearing component is set to 0.5 ppm or less. The amount of retained austenite is preferably 15 to 40% by volume, more preferably 20 to 40% by volume. The hydrogen concentration in the steel is preferably 0.3 ppm or less.

この様な本発明の転がり軸受を造る為に、例えば、請求項２に記載した転がり軸受ユニットの製造方法の様に、前記表面層部分の残留オーステナイト量を１２〜４０容量％とすると共に、鋼中水素濃度を０．５ｐｐｍ以下とする軸受構成部品を、前記両軌道輪のうちの少なくとも一方の軌道輪とする。そして、この軌道輪に設けた軌道面の表面を、高周波加熱による焼き入れ処理で硬化する。
又、請求項２に記載した転がり軸受の製造方法を実施する場合、請求項３に記載した製造方法の発明の様に、前記軌道面の表面を高周波加熱焼き入れ処理により硬化させる前に、軟窒化処理を施す事もできる。
或いは、請求項４に記載した製造方法の発明の様に、前記軌道面の表面を高周波加熱焼き入れ処理により硬化させる前に、８００〜１０００℃で浸炭窒化処理した後、７５０〜８５０℃の温度で窒素雰囲気中に所定時間（３０分〜３時間程度）保持し、その後に、前記高周波焼き入れ処理を行う事もできる。尚、この保持時間が３０分未満の場合には処理の効果が不十分となり、３時間を越えると脱炭等の不利益を生じ易くなる。 In order to manufacture such a rolling bearing of the present invention, the amount of retained austenite in the surface layer portion is set to 12 to 40% by volume, as in the method for manufacturing a rolling bearing unit according to claim 2, for example. A bearing component having a medium hydrogen concentration of 0.5 ppm or less is used as at least one of the two bearing rings. And the surface of the raceway surface provided in this raceway ring is hardened by the quenching process by high frequency heating.
When the rolling bearing manufacturing method according to claim 2 is carried out , the surface of the raceway surface is softened before being hardened by high-frequency heat quenching as in the manufacturing method according to claim 3. Nitriding treatment can also be performed.
Alternatively, as in the invention of the manufacturing method according to claim 4, before the surface of the raceway surface is hardened by induction heating and quenching, carbonitriding is performed at 800 to 1000 ° C., and then a temperature of 750 to 850 ° C. In the nitrogen atmosphere, it can be kept for a predetermined time (about 30 minutes to 3 hours), and then the induction hardening process can be performed. If the holding time is less than 30 minutes, the effect of the treatment is insufficient, and if it exceeds 3 hours, disadvantages such as decarburization are likely to occur.

Claims

A pair of race rings, each of which is annular and concentrically arranged, and provided with raceway surfaces on opposite surfaces, and a plurality of rolling elements arranged so as to be freely rollable between the raceway surfaces; The amount of retained austenite in the surface layer portion in rolling contact with the mating member of at least one of the three types of bearing components of the bearing rings and the rolling elements. Rolling bearing characterized in that the hydrogen concentration in the steel of the bearing component is 0.5 ppm or less.

It is a manufacturing method of the rolling bearing according to claim 1, Comprising: The bearing component which makes the amount of residual austenite of the surface layer part 12-40 volume%, and makes hydrogen concentration in steel 0.5 ppm or less, A method for manufacturing a rolling bearing, characterized in that at least one of the bearing rings is hardened, and a surface of a raceway surface provided on the bearing ring is hardened by a quenching treatment by high-frequency heating.

The method of manufacturing a rolling bearing according to claim 2 , wherein a soft nitriding treatment is performed before the surface of the raceway surface is hardened by a high-frequency heating quenching treatment.

The surface of the raceway surface prior to curing by high-frequency heating quenching treatment, after carbonitriding at 800 to 1000 ° C., and held there a predetermined time in a nitrogen atmosphere at a temperature of 750 to 850 ° C., the induction hardening The manufacturing method of the rolling bearing of Claim 2 which processes.