JP3748067B2 - Rolling element for traction drive - Google Patents

Description

【００１４】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項８に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線形状において、表面粗さ計の縦倍率と横倍率を等しくして計測した断面曲線の凸部の頂部付近の曲率半径が０．８ｍｍ以上１０ｍｍ以下であることを特徴としている。
【００１５】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項９に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線形状において、凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における凹凸１ピッチ分の基準線の長さに対し、同基準線上の突条幅である凸部の長さの割合が３５〜７０％であることを特徴としている。
【００１６】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１０に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線形状において、凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における凹凸１ピッチ分の基準線の長さに対し、同基準線上の突条幅である凸部の長さの割合が５０〜７０％であることを特徴としている。
【００１７】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１１に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線形状において、凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における基準線上で、突条幅である凸部の長さが７〜９０μｍであることを特徴としている。
【００１８】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１２に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線形状において、凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における基準線上で、突条幅である凸部の長さが２５〜８０μｍであることを特徴としている。
【００１９】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１３に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線において、凸部の頂上を中心とする１０μｍの範囲について、原子間力顕微鏡にて測定した表面粗さＲｚが１００ｎｍ以下であることを特徴としている。
【００２０】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１４に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線において、断面曲線の中心線での溝幅である凹部の長さが１０〜４０μｍであることを特徴としている。このとき、表面粗さＲｚは、ＪＩＳ−Ｂ０６０１において定められているものである。
【００２１】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１５に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線において、最大荷重におけるヘルツ接触楕円の転動方向に直交する方向の直径に対し、凹部のピッチが１．２〜９％であることを特徴としている。
【００２２】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１６に記載しているように、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線において、最大荷重におけるヘルツ接触楕円の転動方向に直交する方向の直径に対し、凹部のピッチが２．４〜６％であることを特徴としている。
【００２６】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１７に記載しているように、凹部が、少なくともヘルツ接触楕円の長さよりも長く連続していることを特徴としている。
【００２７】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１８に記載しているように、トラクションドライブ用転動体の動力を伝達する転動面について、駆動側および従動側の一方が、凹部と凸部を有し、他方が、断面曲線の中心線における平均粗さＲａで０．０１μｍ以下、最大高さＲｙで０．１μｍ以下の表面微細形状を有することを特徴としている。このとき、表面粗さＲｚおよび最大高さＲｙは、ＪＩＳ−Ｂ０６０１において定められているものである。
【００２８】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項１９に記載しているように、転動体に用いる材料および転動体製造時の熱処理の組み合わせが、肌焼き鋼材料と浸炭焼入れ焼き戻し熱処理の組み合わせ、肌焼き鋼材料と浸炭窒化焼入れ焼き戻し熱処理の組み合わせ、軸受鋼材料と焼入れ焼き戻し熱処理の組み合わせ、軸受鋼材料と浸炭焼入れ焼き戻し熱処理の組み合わせ、および軸受鋼材料と浸炭窒化焼入れ焼き戻し熱処理の組み合わせのうちから選択されることを特徴としている。
【００２９】
同じく、本発明に係わるトラクションドライブ用転動体は、請求項２０に記載しているように、転動体は、トロイダル曲面型の円環凹面形状をなす転動面をそれぞれ備えた入力ディスクおよび出力ディスクと、対向して配置された入力ディスクおよび出力ディスクの円環凹面形状の転動面に挟まれて円環凸面形状をなす転動面を備え且つローラ軸を傾動可能としたパワーローラとの組み合わせとから成り、ハーフトロイダル型無段変速機の構成要素となることを特徴としている。
【００３０】
【発明の作用】
本発明の請求項１に係わるトラクションドライブ用転動体では、転動面間でトラクションオイルを介在して動力を伝達するトラクションドライブ用転動体において、駆動側および従動側の少なくとも一方の転動体の動力を伝達する転動面に凹部と突条の凸部を規則的に交互に配置した形状を設けている。
【００３１】
このとき、当該トラクションドライブ用転動体では、転動面の表面微細形状に関し、表面粗さ計を用いて転動体の軸方向に測定されてフィルターを通さずに得られる断面曲線形状において、断面曲線の中心線すなわち断面曲線を長さ方向に積分した平均的な高さに引いた線よりも上側の凸部の形状が、角が丸みを帯びた概略台形状、概略クラウニング形状、概略楕円弧状、概略正弦波状、および頂点が丸みを帯びた概略三角形状のいずれかであるものとし、さらに、波長λと凹凸の高低差に相当する溝深さの半分ＡＭＰの比であるλ／ＡＭＰが５０以上４００以下としているので、金属接触を小さく留めて耐久性の向上を図りつつ、大きなトラクション力が発生することとなり、大きな動力の伝達が可能であるトラクション特性に優れたトラクションドライブ用転動体が提供される。
【００３２】
また、λ／ＡＭＰを５０以上とすることで、表面に発生する局所応力を小さくすることができるために、優れた安定性を有するものとなる。一方、λ／ＡＭＰを４００以下とすることで、トラクション係数を安定して向上させることが可能である。そして、当該トラクションドライブ用転動体では、凹部が転動体の転動方向に連続して軸回りの螺旋に沿って形成してあるので、より大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。
【００３３】
本発明の請求項２に係わるトラクションドライブ用転動体では、他方の転動体の転動面が平滑であって、凹凸を有する転動体の表面から少なくとも１００μｍ深さでの硬度をＨｖ８００以上としたので、使用中に凸部の深さが変化し難く、耐摩耗性や耐陥没性に優れたトラクションドライブ用転動体が提供される。
【００３４】
本発明の請求項３に係わるトラクションドライブ用転動体では、凹凸を有する転動体の表面から５０μｍ深さでの硬度をＨｖ８００以上としたので、耐摩耗性や耐陥没性がさらに優れたトラクションドライブ用転動体が提供される。
【００３５】
本発明の請求項４に係わるトラクションドライブ用転動体では、凹凸を有する転動体の表面から５０μｍ深さでの圧縮残留応力を８００ＭＰａ以上としたので、耐摩耗性や耐陥没性がさらに優れたトラクションドライブ用転動体が提供される。
【００３６】
本発明の請求項５に係わるトラクションドライブ用転動体では、凹凸を有する転動体の表面をローラバニッシング加工により加工硬化させるので、所望の硬度を有する転動体が得られることとなる。
【００３７】
本発明の請求項６に係わるトラクションドライブ用転動体では、凹凸を有する転動体の表面における凸部の曲率半径を１ｍｍ以上８ｍｍ以下としたので、エッジ応力の発生を抑制すると共に、過大な応力の発生を防止して、耐久性に優れたトラクションドライブ用転動体が提供される。
【００３８】
本発明の請求項７に係わるトラクションドライブ用転動体では、断面曲線形状において、凸部の頂部の曲率半径をβ（μｍ）、断面曲線の中心線から凸部の頂上までの高さのばらつきの標準偏差をσ（μｍ）、転動体材料の等価ヤング率をＥ’（Ｐａ）、転動体材料の硬度をＨ（Ｐａ）とし、これらの関係式で定義される塑性指数ψを０．２以下としているので、一層大きなトラクション係数が発揮されると共に、金属接触がさらに低減することとなり、トラクション伝達により優れた長寿命のトラクションドライブ用転動体が提供される。
【００３９】
本発明の請求項８に係わるトラクションドライブ用転動体では、断面曲線形状において、表面粗さ計の縦倍率と横倍率を等しくして計測した断面曲線における凸部の頂部付近の曲率半径を０．１ｍｍ以上とし、好ましくは曲率半径を０．８ｍｍ以上とし、より好ましくは０．８ｍｍ以上１０ｍｍ以下とすることにより、より大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。この場合、とくに、曲率半径を０．８ｍｍ以上と限定することにより、より一層の金属接触が低減されて耐久性が向上する。
【００４０】
なお、断面曲線における凸部の曲率半径（ｒ）は図２３に示す関係にある。すなわち、断面曲線の中心線Ｃ１から凸部の頂部までの長さをｔとし、凸部の中心線Ｃ２から断面曲線と同断面曲線の中心線Ｃ１との交点Ｃ３までの長さをＳとしたとき、曲率半径（ｒ）はｔ^２＋Ｓ^２／２ｔで表される。
【００４１】
本発明の請求項９に係わるトラクションドライブ用転動体では、断面曲線形状において、図２０に示すように、凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における凹凸１ピッチ分の基準線の長さにＬ１対して、同基準線上の突条幅である凸部の長さＬ２の割合を３５〜７０％としているので、より大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。
【００４２】
本発明の請求項１０に係わるトラクションドライブ用転動体では、断面曲線形状において、凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における凹凸１ピッチ分の基準線の長さに対して、同基準線上の突条幅である凸部の長さの割合を５０〜７０％としているので、より一層大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。
【００４３】
本発明の請求項１１に係わるトラクションドライブ用転動体では、断面曲線形状において、凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における凹凸１ピッチ分の基準線に対して、突条幅である凸部の長さを７〜９０μｍとしているので、より大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。
【００４４】
本発明の請求項１２に係わるトラクションドライブ用転動体では、断面曲線形状において、凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における凹凸１ピッチ分の基準線に対して、突条幅である凸部の長さを２５〜８０μｍとしているので、より一層大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。
【００４５】
本発明の請求項１３に係わるトラクションドライブ用転動体では、断面曲線において、図２１に示す如く凸部の頂上を中心とする１０μｍのＡ範囲について、原子間力顕微鏡にて測定した表面粗さＲｚを１００ｎｍ以下としているので、金属接触による耐久性への跳ね返りが小さくなり、より大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。
【００４６】
本発明の請求項１４に係わるトラクションドライブ用転動体では、断面曲線において、中心線での溝幅である凹部の長さを１０〜４０μｍとしているので、金属接触による耐久性への跳ね返りが小さくなり、より大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。この場合、凹部の長さを１０μｍよりも大きくすると、トラクション特性が飛躍的に向上し、凹部の長さを４０μｍよりも小さくすると、金属接触が生じる確立が下がり、耐久性が飛躍的に向上する。また、当該トラクションドライブ用転動体では、トラクションオイルの排出が効果的に行われると共に、油膜厚さを適切な厚さに保持し得ることとなり、より大きなトラクション係数を発揮しながら金属接触を低減して長寿命を維持する。
【００４７】
本発明の請求項１５に係わるトラクションドライブ用転動体では、断面曲線において、最大荷重におけるヘルツ接触楕円の転動方向に直交する方向の直径に対し、凹部ピッチを１．２〜９％としているので、より大きなトラクション係数が安定的に発揮され、且つ金属接触が生じることによる耐久性への跳ね返りの懸念が少ないトラクションドライブ用転動体が提供される。
【００４８】
本発明の請求項１６に係わるトラクションドライブ用転動体では、断面曲線において、最大荷重におけるヘルツ接触楕円の転動方向に直交する方向の直径に対し、凹部ピッチを２．４〜６％としているので、高いトラクション特性がより安定した状態で得られることとなる。
【００５２】
本発明の請求項１７に係わるトラクションドライブ用転動体では、凹部が少なくともヘルツ接触楕円の長さよりも長く連続しているので、大きなトラクション係数を発揮できるトラクションドライブ用転動体が提供される。
【００５３】
本発明の請求項１８に係わるトラクションドライブ用転動体では、トラクションドライブ用転動体の動力を伝達する転動面について、駆動側および従動側の一方が、凹部と凸部を有するものとし、他方が、断面曲線の中心線における平均粗さＲａで０．０１μｍ以下、最大高さＲｙで０．１μｍ以下としているので、より一層大きなトラクション係数がより安定的に発揮されると共に、金属接触による耐久性への跳ね返りの懸念の少ないトラクションドライブ用転動体が提供される。
【００５４】
本発明の請求項１９に係わるトラクションドライブ用転動体では、転動体に用いる材料および転動体製造時の熱処理の組み合わせが、肌焼き鋼材料と浸炭焼入れ焼き戻し熱処理の組み合わせ、肌焼き鋼材料と浸炭窒化焼入れ焼き戻し熱処理の組み合わせ、軸受鋼材料と焼入れ焼き戻し熱処理の組み合わせ、軸受鋼材料と浸炭焼入れ焼き戻し熱処理の組み合わせ、および軸受鋼材料と浸炭窒化焼入れ焼き戻し熱処理の組み合わせのうちから選択されるものとすることにより、耐摩耗性が良好で、且つまた長期にわたって優れたトラクション特性を維持し得るトラクションドライブ用転動体が提供される。
【００５５】
本発明の請求項２０に係わるトラクションドライブ用転動体では、転動体が、円環体凹面形状をなす転動面をそれぞれ備えた入力ディスクおよび出力ディスクと、対向して配置した入力ディスクおよび出力ディスクの円環体凹面形状のトラクション転動面間に挟まれて凹面形状のトラクション転動面と相互に転動する円環体凸面形状をなすトラクション転動面を備え且つローラ軸を傾動可能としたパワーローラとの組み合わせからなり、ハーフトロイダル型無段変速機の構成要素となるものとし、入力ディスクおよび出力ディスク、またはパワーローラの少なくとも１つのトラクション転動面を上述した表面微細形状としているので、大きな動力の伝達が可能であり、しかも、ユニットサイズの小型化および軽量化、ないしは単位容積および単位重量当たりの高出力化が可能であるハーフトロイダル型無段変速機が提供される。
【００５６】
【発明の効果】
本発明の請求項１に係わるトラクションドライブ用転動体によれば、転動面間でトラクションオイルを介在して動力を伝達するトラクションドライブ用転動体において、金属接触を小さく留めて耐久性の向上を図りつつ、大きなトラクション力を発生することが可能となり、大きな動力の伝達が可能であるトラクション特性に優れたトラクションドライブ用転動体を提供することができる。また、とくに凹凸の波長λと凹凸の高低差に相当する溝深さの半分ＡＭＰの比であるλ／ＡＭＰを５０以上とすることにより、表面に発生する局所応力を小さくできるために、優れた耐久性能を得ることができ、且つλ／ＡＭＰを４００以下とすることで、トラクション係数を安定して向上させることができる。そしてさらに、凹部を転動体の転動方向に連続させて軸回りの螺旋に沿って形成したことにより、より大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができる。
【００５７】
本発明の請求項２に係わるトラクションドライブ用転動体によれば、請求項１と同様の効果を得ることができるうえに、使用中に凸部の深さが変化し難く、耐摩耗性や耐陥没性に優れたトラクションドライブ用転動体を提供することができる。
【００５８】
本発明の請求項３に係わるトラクションドライブ用転動体によれば、請求項１および２と同様の効果を得ることができるうえに、耐摩耗性や耐陥没性がさらに優れたトラクションドライブ用転動体を提供することができる。
【００５９】
本発明の請求項４に係わるトラクションドライブ用転動体によれば、請求項１〜３と同様の効果を得ることができるうえに、耐摩耗性や耐陥没性がさらに優れたトラクションドライブ用転動体を提供することができる。
【００６０】
本発明の請求項５に係わるトラクションドライブ用転動体によれば、請求項１〜４と同様の効果を得ることができるうえに、所望の硬度を有する転動体を容易に得ることができる。
【００６１】
本発明の請求項６に係わるトラクションドライブ用転動体によれば、請求項１〜５と同様の効果を得ることができるうえに、エッジ応力の発生を抑制すると共に、過大な応力の発生を防止して、耐久性に優れたトラクションドライブ用転動体を提供することができる。
【００６２】
本発明の請求項７に係わるトラクションドライブ用転動体によれば、請求項１と同様の効果を得ることができるうえに、一層大きなトラクション係数を発揮することができると共に、金属接触をさらに低減させることができ、トラクション伝達により優れた長寿命のトラクションドライブ用転動体を提供することができる。
【００６３】
本発明の請求項８に係わるトラクションドライブ用転動体によれば、請求項１または７と同様の効果を得ることができるうえに、より大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができ、とくに、曲率半径を０．８ｍｍ以上と限定することにより、より一層の金属接触を低減でき、耐久性向上を図ることができる。
【００６４】
本発明の請求項９に係わるトラクションドライブ用転動体によれば、請求項１、７および８と同様の効果を得ることができるうえに、より大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができる。
【００６５】
本発明の請求項１０に係わるトラクションドライブ用転動体によれば、請求項１、７および８と同様の効果を得ることができるうえに、より大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができる。
【００６６】
本発明の請求項１１に係わるトラクションドライブ用転動体によれば、請求項１、７〜１０と同様の効果を得ることができるうえに、断面曲線形状において、より大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができる。
【００６７】
本発明の請求項１２に係わるトラクションドライブ用転動体によれば、請求項１、７〜１０と同様の効果を得ることができるうえに、より一層大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができる。
【００６８】
本発明の請求項１３に係わるトラクションドライブ用転動体によれば、請求項１、７〜１２と同様の効果を得ることができるうえに、金属接触による耐久性への跳ね返りを小さくし、より大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができる。
【００６９】
本発明の請求項１４に係わるトラクションドライブ用転動体によれば、請求項１、７〜１３と同様の効果を得ることができるうえに金属接触による耐久性への跳ね返りを小さくし、より大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができ、また、トラクションオイルの排出を効果的に実施することができると共に、油膜厚さを適切な厚さに保持することができ、より大きなトラクション係数を発揮しながら金属接触を低減して長寿命を維持することができる。
【００７０】
本発明の請求項１５に係わるトラクションドライブ用転動体によれば、請求項１、７〜１４と同様の効果を得ることができるうえに、より大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができる。
【００７１】
本発明の請求項１６に係わるトラクションドライブ用転動体によれば、請求項１、７〜１４と同様の効果を得ることができるうえに、より一層大きなトラクション係数を発揮するトラクションドライブ用転動体を提供することができる。
【００７５】
本発明の請求項１７に係わるトラクションドライブ用転動体によれば、請求項１、７〜１５と同様の効果を得ることができるうえに、大きなトラクション係数を発揮できるトラクションドライブ用転動体を提供することができる。
【００７６】
本発明の請求項１８に係わるトラクションドライブ用転動体によれば、請求項１、７〜１７と同様の効果を得ることができるうえに、より一層大きなトラクション係数をより安定的に発揮でき、且つ金属接触による耐久性への跳ね返りの懸念の少ないトラクションドライブ用転動体を提供することができる。
【００７７】
本発明の請求項１９に係わるトラクションドライブ用転動体によれば、請求項１、７〜１８と同様の効果を得ることができるうえに、耐摩耗性が良好になり、長期にわたって優れたトラクション特性を維持し得るトラクションドライブ用転動体を提供することができる。
【００７８】
本発明の請求項２０に係わるトラクションドライブ用転動体によれば、請求項１、７〜１９と同様の効果を得ることができるうえに、大きな動力の伝達が可能であり、しかも、ユニットサイズの小型化および軽量化、ないしは単位容積および単位重量当たりの高出力化が可能であるハーフトロイダル型無段変速機を提供することができる。
【００７９】
【実施例】
本発明に係わるトラクションドライブ用転動体は、その製造方法がとくに限定されることはないが、製造方法の代表的な例としては、材料を肌焼き鋼もしくは軸受鋼とし、肌焼き鋼の場合には、浸炭焼入れ焼き戻し、あるいは浸炭窒化焼入れ焼き戻しを行い、軸受鋼の場合には、焼入れ焼き戻し、あるいは浸炭焼入れ焼き戻し、あるいは浸炭窒化焼入れ焼き戻しを行う。そして、熱処理後には、転動面となる面に対して、研削加工、ｃ―ＢＮ工具を用いた切削による溝状凹部の形成、テープラップ、凸部の削り取りを順次行い、凹部（溝）と凸部（突条）を等間隔で交互に配列させた形状とし、この際、断面曲線の中心線よりも上側の凸部の形状が、角が丸みを帯びた概略台形状、概略クラウニング形状、概略楕円弧状、概略正弦波状、および頂点が丸みを帯びた概略三角形状となるようにする。
【００８０】
このとき、当該トラクションドライブ用転動体では、本発明の請求項１から１６に記載したように、転動面の表面微細形状を設定することで、大きな動力の伝達が可能であると共に、高温高面圧下において優れたトラクション特性と高い転動疲労寿命性能を実現し得るものとなる。
【００８１】
また、トラクション特性に優れたトラクションドライブ用転動体が提供されることから、トロイダル曲面型の円環凹面形状をなす転動面をそれぞれ備えた入力ディスクおよび出力ディスクと、対向して配置された入力ディスクおよび出力ディスクの円環凹面形状の転動面に挟まれて円環凸面形状をなす転動面を備え且つローラ軸を傾動可能としたパワーローラとの組み合わせから、トラクション特性に優れたハーフトロイダル型無段変速機を構成し得ることとなる。
【００８２】
以下、本発明に係わるトラクションドライブ用転動体について、実施例および比較例により詳しく説明する。なお、本発明に係わるトラクションドライブ用転動体は、以下の実施例のみに限定されないことはいうまでもない。
【００８３】
（試験方法）
本実施例では、図２に示す４円筒転がり試験機を用いて転動体（試験片）の転がりすべり試験を実施した。図示の４円筒転がり試験機は、従軸５１と、従軸５１を中心にして互いに平行に配置され且つ遊星歯車を介して回転する３本の主軸５３ａ〜５３ｃを備えると共に、従軸５１に支持された従動側転動体５２の外周面に、各主軸５３ａ〜５３ｃにより個別に支持された３個の駆動側転動体５４ａ〜５４ｃを接触させ、３本の主軸５３ａ〜５３ｃのうちの１本（５３ａ）に対して加圧機構で負荷を加えることにより、従動側転動体５２の外周面に各駆動側転動体５４ａ〜５４ｃを圧接させる構造になっている。加圧機構は、３本の加圧用アーム５５ａ〜５５ｃをＴ型に配置して、各アーム５５ａ〜５５ｃを上下方向に揺動自在に保持し、直線状に配置した横２本のアーム５５ａ，５５ｂの外側の端部にウエイト５６を吊り下げると共に、両アーム５５ａ，５５ｂの内側の端部同士を上下に重合させている。また、残る１本のアーム５５ｃは、一端部を横のアーム５５ａ，５５ｂの重合部分の上側に重合すると共に、他端部を先の駆動側転動体５４ａの回転軸５３ａに設けた加圧部５７に当接させている。
【００８４】
４円筒転がり試験機は、加圧機構において、左右のウエイト５６の重量を各アーム５５ａ〜５５ｃを介して加圧部５７に作用させ、従動側転動体５２の外周面に各駆動側転動体５４ａ〜５４ｃを圧接させるものとなっており、従動側転動体５２の従軸５１に設けたトルクセンサで同従軸５１に発生するトルクを測定することにより、トラクション係数を算出することができる。
【００８５】
本実施例では、先の図２に示す４円筒転がり試験機を用いて転動体（試験片）の転がりすべり試験を実施し、トラクション係数を算出すると共に、円筒間の接触状態を定性的に評価する目的で、電気抵抗法を用いた油膜形成率の算出を行った。本実施例の試験では、スリップ率：０〜３％、平均すべり速度：３０ｍ／ｓ、平均軸回転数：１００００ｒｐｍとし、主軸５３ａ〜５３ｃと従軸５１に均等に差動を与えてすべり速度を一定にした。さらに、１５０℃に設定したトラクションオイルを２Ｌ／ｍｉｎで回転方向入り口部から供給した。そして、本実施例では、スリップ率３％でのトラクション係数および油膜形成率を算出した。
【００８６】
（実施例１〜１２、比較例１，２）
従動側転動体５２については、直径＝６０ｍｍ、厚さ＝１０ｍｍであり、転動面がフラットな円筒形状とした。本実施例および比較例においては、ＳＣｒ４２０鋼、ＳＣＭ４２０鋼を浸炭焼入れ焼き戻ししたもの、ＳＣＭ４２０鋼を浸炭窒化焼入れ焼き戻ししたもの、ＳＵＪ２鋼を焼入れ焼き戻ししたもの、およびＳＵＪ２鋼を浸炭窒化焼入れ焼き戻したものを用い、転動面を研削した後、多結晶ｃ―ＢＮ切削工具を用いて転動面に溝を切削加工し、この後、テープラップにて突部を削り落とし、転動面に、溝状凹部と突条の凸部を交互に配置してなる所望の凹凸形状の表面微細形状を得た。
【００８７】
他方、外側３個の駆動側転動体５４ａ〜５４ｃについては、直径＝６０ｍｍ、厚さ＝１０ｍｍであり、転動面がＲ＝３０ｍｍのクラウニング形状をなす円筒形状とした。この場合には、ＳＵＪ２鋼の焼入れ焼き戻し材を用い、転動面に研削を行ってからテープラップにより中心線平均粗さＲａを０．０１μｍ、最大高さＲｙを０．１μｍに仕上げた。
【００８８】
従動側転動体５２について、実施例１〜１２の断面曲線を図３〜１４に、比較例１，２の断面曲線を図１５，１６に示す。また、実施例１〜１２、比較例１，２に用いた外側の駆動側転動体５４ａ〜５４ｃの断面曲線を図１８に示す。
【００８９】
なお、断面曲線は、転動体５２の軸方向（転動方向と直角な方向）に測定したものである。この断面曲線については、（株）東京精密製の触針式表面粗さ形状測定機、サーフコム１４００を用いて測定した。この際、粗さ測定機の触針は、先端の形状が球面で、曲率半径がＲ５μｍ、頂角が９０°であり、測定長さは１ｍｍであった。
【００９０】
また、凸部頂上の表面粗さについては、Ｄｉｇｉｔａｌ Ｉｎｓｔｒｕｍｅｎｔｓ社製のＮａｎｏｓｃｏｐｅ−ＩＩＩａ＋Ｄ３１００型の原子間力顕微鏡を用い、スキャンサイズ１０μｍにてＡＦＭコンタクトモードにて測定した。
【００９１】
（比較例３）
従動側転動体５２については、直径＝６０ｍｍ、厚さ＝１０ｍｍであり、転動面がフラットな円筒形状とした。ＳＵＪ２鋼の焼入れ焼き戻し後、転動面を研削し、さらに超仕上げを施した。この断面曲線を図１７に示す。
【００９２】
他方、外側３個の駆動側転動体５４ａ〜５４ｃについては、直径＝６０ｍｍ、厚さ＝６０ｍｍであり、転動面がＲ＝３０ｍｍのクラウニング形状をなす円筒形状とした。この場合には、ＳＵＪ２鋼を焼入れ焼き戻ししたものを用い、転動面を研削し、さらに超仕上げを施した。この断面曲線を図１９に示す。
【００９３】
（評価結果）
上記の実施例１〜１２および比較例１〜３の仕様、ならびに実施例および比較例で得られたスリップ率３％におけるトラクション係数および油膜形成率を表１に示す。
【００９４】
【表１】

【００９５】
表１に示した結果から明らかなように、実施例１〜１２では、比較例３に対して良好なトラクション係数が安定して得られ、油膜も十分に形成されて金属接触を低減することができた。これに対して、比較例１、２では、油膜が十分に形成されず、トラクション係数の測定中に金属接触が発生し、表面粗さが悪化することにより振動が増大して、試験を継続することができなかった。
【００９６】
（実施例１３〜３０、比較例４、５）
従動側転動体５２については、直径＝６０ｍｍ、厚さ＝１０ｍｍであり、転動面がフラットな円筒形状とした。本実施例１３〜３０および比較例４、５では、ＳＵＪ２鋼を焼入れ焼き戻ししたものを用い、転動面を研削した後、多結晶ｃ―ＢＮ切削工具を用いて転動面に溝を切削加工し、その後、テープラップにて凸部を削り落とし、転動面に溝状凹部と突条の凸部を交互に配置してなる所望の凹凸形状の表面微細形状を得た。
【００９７】
他方、外側３個の駆動側転動体５４ａ〜５４ｃについては、直径＝６０ｍｍ、厚さ＝１０ｍｍであり、転動面がＲ＝３０ｍｍのクラウニング形状を成す円筒形状とした。この場合には、ＳＵＪ２鋼の焼入れ焼き戻し材を用い、転動面に研削を行ってから、超仕上げ加工により中心線平均粗さＲａを０．０２μｍ、最大高さＲｙを０．１２μｍに仕上げた。
【００９８】
（評価結果）
上記の実施例１３〜３０および比較例４、５の仕様、ならびに実施例および比較例で得られたスリップ率３％におけるトラクション係数および油膜形成率を表１に示す。本実施例１３〜３０においては、ワイドピッチ化することで比較例３に対して良好なトラクション係数が安定して得られ、油膜も十分に形成されて金属接触をすることが低減できた。これに対して比較例４、５では、比較例３と同等のトラクション係数しか得られなかった。
【００９９】
実施例１３〜３０においては、ワイドピッチとすることでトラクション係数および油膜形成率のいずれも溝深さに鈍感な特性を示し、使用中に摩耗等により溝深さが小さくなっても、特性が変化しにくいという優れた効果がある。また、溝深さのばらつき範囲の許容差を大きくできるため、溝形成も容易になるという優れた特性を付与しえる。
【０１００】
（実施例３１〜３４、比較例６）
実施例３１〜３４では、一方の転動体の作成において、直径が２６ｍｍであり、トラクション転動面がフラットな円筒形状の転動体とした。ＳＣＭ４２０鋼を浸炭窒化焼入れ焼戻ししたものを用い、トラクション転動面を研削した後、超仕上加工を行った。その後、φ６ｍｍの窒化珪素球を用いたバニッシング加工を施した。バニッシング条件は、押付け荷重を１００ｋｇｆとし、送りを０．１ｍｍ／ｒｅｖとした。こののち、刃先が５０μｍのｃ−ＢＮ工具を用いて溝を切削し、テープラップ加工にて凸部を削り落とし、所望の凹凸形状を得た。
【０１０１】
実施例３４の転動体については、超仕上加工までは同一とし、その後、平均粒径５０μｍ、硬度８３０Ｈｖのスチールビーズを、投射距離２００ｍｍから、投射圧力５ｋｇｆ／ｃｍ^２ 、２ｒｐｍで６０秒噴射し、さらに、実施例３１〜３３と同様のバニッシング加工を行った後に溝を切削し、テープラップ加工を施して所望の凹凸形状を得た。
【０１０２】
比較例６の転動体については、超仕上加工が終了した時点で加工工程を終了し、試験に供した。なお、実施例３１と比較例６について、転動面の表面からの距離と硬度との関係を図２２に示す。
【０１０３】
他方の転動体に関しては、実施例３１〜３４および比較例６のいずれも同じものを使用した。他方の転動体については、直径１３０ｍｍ、厚さ１８ｍｍ、トラクション転動面がＲ＝３０ｍｍのクラウニング形状を成すようにし、ＳＣＭ４３５鋼を浸炭窒化焼入れ焼戻ししたものを用い、研削後、超仕上加工により転動面がＲａ０．０２μｍになるように仕上た。
【０１０４】
これらの実験条件としては、２つの円筒を互いに押付けながら、荷重１５６０ｋｇｆ、油温９０℃、供給油量２ｌ／ｍｉｎ、平均転がり速度２．８５ｍ／ｓ、滑り率−１０％で回転させた。この場合、φ２６ｍｍの円筒の周速をｖ１（ｍ／ｓ）とし、φ１３０ｍｍの円筒の周速をｖ２（ｍ／ｓ）とした場合、滑り率は（ｖ１−ｖ２）／ｖ２で表される。上記の条件にてφ２６ｍｍの円筒が１×１０^６回数回転した後、試験片を取外し、試験前の形状と試験後の形状を比較することにより、凹凸の深さの変化量を測定した。
【０１０５】
（評価結果）
溝深さの変化量は、（株）東京精密製の表面粗さ形状測定器サーフコム１４００Ａにて測定した。溝深さ変化量は、非転動部の平均値から転動部の溝深さを差し引いたものとし、その結果を表２に示す。なお、表２中のＲＬＢ加工はローラバニッシング加工であり、ＷＰＣは極小径ショットピーニング加工である。また、上記ＳＣｒ４２０鋼、ＳＣＭ４２０鋼、ＳＣＭ４３５鋼およびＳＵＪ２鋼は、ＪＩＳ Ｇ４１０５に示される鋼材の分類である。
【０１０６】
【表２】

【０１０７】
表２から明らかなように、実施例３１〜３４は、比較例６に比べて溝深さの変化量が小さい。すなわち、実施例３１〜３４のものは、溝深さが減少することによる性能変化を抑制することができ、大きなトラクション力を安定して且つ持続的に発揮することができる。これに対して、比較例６のものは、溝深さの変化量が大きく、この場合には、トラクション係数が時間とともに減少し、良好なトラクション係数を維持する時間が実施例のものよりも短くなる。
【図面の簡単な説明】
【図１】トラクションドライブ型無段変速機の基本構成を示す断面説明図である。
【図２】４円筒転がり試験機の概要を示す斜視説明図である。
【図３】表面粗さ計により測定された実施例１の従動側転動体５２の断面曲線を示すグラフである。
【図４】表面粗さ計により測定された実施例２の従動側転動体５２の断面曲線を示すグラフである。
【図５】表面粗さ計により測定された実施例３の従動側転動体５２の断面曲線を示すグラフである。
【図６】表面粗さ計により測定された実施例４の従動側転動体５２の断面曲線を示すグラフである。
【図７】表面粗さ計により測定された実施例５の従動側転動体５２の断面曲線を示すグラフである。
【図８】表面粗さ計により測定された実施例６の従動側転動体５２の断面曲線を示すグラフである。
【図９】表面粗さ計により測定された実施例７の従動側転動体５２の断面曲線を示すグラフである。
【図１０】表面粗さ計により測定された実施例８の従動側転動体５２の断面曲線を示すグラフである。
【図１１】表面粗さ計により測定された実施例９の従動側転動体５２の断面曲線を示すグラフである。
【図１２】表面粗さ計により測定された実施例１０の従動側転動体５２の断面曲線を示すグラフである。
【図１３】表面粗さ計により測定された実施例１１の従動側転動体５２の断面曲線を示すグラフである。
【図１４】表面粗さ計により測定された実施例１２の従動側転動体５２の断面曲線を示すグラフである。
【図１５】表面粗さ計により測定された比較例１の従動側転動体５２の断面曲線を示すグラフである。
【図１６】表面粗さ計により測定された比較例２の従動側転動体５２の断面曲線を示すグラフである。
【図１７】表面粗さ計により測定された比較例３の従動側転動体５２の断面曲線を示すグラフである。
【図１８】表面粗さ計により測定された実施例１〜１２および比較例１，２の駆動側転動体５４ａ〜５４ｃの断面曲線を示すグラフである。
【図１９】表面粗さ計により測定された比較例３の駆動側転動体５４ａ〜５４ｃの断面曲線を示すグラフである。
【図２０】 凸部の頂上から凸部と凹部の高低差の１／１０だけ低い位置における凹凸１ピッチ分の基準線上の凸部の長さを示す説明図である。
【図２１】凸部の頂上を中心とする１０μｍの範囲を示す説明図である。
【図２２】実施例３１および比較例６について、転動面表面からの距離と硬度との関係を示すグラフである。
【図２３】断面曲線における凸部の曲率半径（ｒ）の定義を示す説明図である。
【符号の説明】
１ トラクションドライブ型無段変速機
３ 入力ディスク（転動体）
５ 出力ディスク（転動体）
６ パワーローラー（転動体）
５２ 従動側転動体
５４ａ〜５４ｃ 駆動側転動体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a traction drive type continuously variable transmission used in a power transmission device such as an automobile or an industrial machine to transmit rotation from an input shaft steplessly by a traction drive and transmit it to an output side. More specifically, the present invention relates to a traction drive rolling element used with traction oil interposed therebetween, and more particularly to a traction drive rolling element having a surface shape of a rolling surface excellent in traction characteristics.
[0002]
[Prior art]
The continuously variable transmission has been studied in various fields because of its excellent power transmission performance and no shift shock. Among them, a method of transmitting power between rolling surfaces via traction oil (traction drive method: rolling method) has been studied for the purpose of transmitting large power.
[0003]
The traction drive system that transmits power between the rolling surfaces via the traction oil has a mechanism that can handle a high-power engine. For example, the basic configuration of a traction drive type continuously variable transmission 1 shown in FIG. 1 is a metal rolling element that is in contact via traction oil, that is, two discs (an input disc 3 fixed to an input shaft 2 and an output shaft). By changing the inclination of the roller shaft of the power roller 6 sandwiched between the output disks 5) fixed to 4 and changing the contact radius of the disks 3 and 5 via the power roller 6, the power can be continuously variable. It is a mechanism to communicate. One example of this traction drive type continuously variable transmission is a half-toroidal continuously variable transmission.
[0004]
[Problems to be solved by the invention]
The rolling elements (input disk 3, output disk 5, power roller 6) used in such a traction drive system are required to have excellent traction characteristics and high rolling fatigue life performance under high temperature and high surface pressure. Is done. In addition, considering the reduction of the load on the environment in the future, it is necessary to reduce the vehicle weight in order to further improve the fuel efficiency. For this purpose, the unit size can be reduced and the unit of the same size can be transmitted. There was a problem that it was necessary to increase the power.
[0005]
OBJECT OF THE INVENTION
The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a rolling element for a traction drive excellent in traction characteristics capable of transmitting a large amount of power.
[0006]
[Means for Solving the Problems]
The rolling element for a traction drive according to the present invention is a rolling element for a traction drive that transmits power through traction oil between rolling surfaces, as described in claim 1. Regarding the surface fine shape of the rolling surface that transmits the power of at least one rolling element, the cross-sectional curve shape that is measured in the axial direction of the rolling element using a surface roughness meter and does not pass through the filter is a groove. It is a shape in which convex portions that are concave portions and ridges are regularly and alternately arranged, and the shape of the convex portion above the center line of the cross-sectional curve is a rough trapezoidal shape with rounded corners, a rough crowning shape, Λ / AMP, which is one of a substantially elliptic arc shape, a substantially sinusoidal shape, and a substantially triangular shape with a rounded top, and a ratio of the λ of the unevenness to the half AMP of the groove depth corresponding to the height difference of the unevenness 50 or more It is 400 or less, and the recess is formed along the spiral around the axis continuously in the rolling direction of the rolling element, and the above configuration is a means for solving the conventional problems.
[0007]
Similarly, the rolling element for a traction drive according to the present invention has a smooth rolling surface of the other rolling element and a depth of at least 100 μm from the surface of the rolling element having irregularities. It is characterized in that the hardness at Hv is 800 or more.
[0008]
Similarly, the rolling element for a traction drive according to the present invention is characterized in that the hardness at a depth of 50 μm from the surface of the rolling element having irregularities is Hv 800 or more.
[0009]
Similarly, the rolling element for a traction drive according to the present invention is characterized in that the compressive residual stress at a depth of 50 μm from the surface of the rolling element having irregularities is 800 MPa or more. .
[0010]
Similarly, the rolling element for a traction drive according to the present invention is characterized in that the surface of the rolling element having irregularities is work-hardened by roller burnishing as described in claim 5.
[0011]
Similarly, the rolling element for a traction drive according to the present invention is characterized in that the curvature radius of the convex portion on the surface of the rolling element having irregularities is 1 mm or more and 8 mm or less.
[0012]
Similarly, the rolling element for a traction drive according to the present invention, as described in claim 7, is a cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and without passing through a filter. , The curvature radius of the top of the convex part is β (μm), the standard deviation of the height variation from the center line of the cross section curve to the top of the convex part is σ (μm), and the equivalent Young's modulus of the rolling element material is E ′ (Pa), where the hardness of the rolling element material is H (Pa), and the plasticity index ψ defined by the following formula is 0.2 or less.
[0013]
[Expression 2]

[0014]
Similarly, the rolling element for a traction drive according to the present invention has a cross-sectional curved shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter without passing through a filter. 2 is characterized in that the radius of curvature near the top of the convex portion of the cross-sectional curve measured by equalizing the vertical and horizontal magnifications of the surface roughness meter is 0.8 mm or more and 10 mm or less.
[0015]
Similarly, the rolling element for a traction drive according to the present invention is, as described in claim 9, a cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and not passing through a filter. , The ratio of the length of the convex portion that is the width of the protrusion on the reference line to the length of the reference line for one pitch of the concave and convex portions at a position 1/10 lower than the height difference between the convex portion and the concave portion from the top of the convex portion Is 35 to 70%.
[0016]
Similarly, the rolling element for a traction drive according to the present invention is, as described in claim 10, a cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and without passing through a filter. , The ratio of the length of the convex portion that is the width of the protrusion on the reference line to the length of the reference line for one pitch of the concave and convex portions at a position 1/10 lower than the height difference between the convex portion and the concave portion from the top of the convex portion Is 50 to 70%.
[0017]
Similarly, the rolling element for a traction drive according to the present invention is, as described in claim 11, a cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and without passing through a filter. The length of the convex portion, which is the width of the ridge, is 7 to 90 μm on the reference line at a position 1/10 lower than the height difference between the convex portion and the concave portion from the top of the convex portion.
[0018]
Similarly, the rolling element for a traction drive according to the present invention has a cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter without passing through a filter. The length of the convex portion, which is the ridge width, is 25 to 80 μm on the reference line at a position 1/10 lower than the height difference between the convex portion and the concave portion from the top of the convex portion.
[0019]
Similarly, the rolling element for a traction drive according to the present invention is a cross-sectional curve obtained by measuring in the axial direction of a rolling element using a surface roughness meter and passing through a filter as described in claim 13. In the range of 10 μm centered on the top of the convex part, the surface roughness Rz measured with an atomic force microscope is 100 nm or less.
[0020]
Similarly, the rolling element for a traction drive according to the present invention has a sectional curve obtained by measuring in the axial direction of the rolling element using a surface roughness meter and passing through the filter as described in claim 14. The length of the recess, which is the groove width at the center line of the cross-sectional curve, is 10 to 40 μm. At this time, the surface roughness Rz is defined in JIS-B0601.
[0021]
Similarly, the rolling element for a traction drive according to the present invention is a cross-sectional curve obtained by measuring in the axial direction of the rolling element using a surface roughness meter without passing through a filter, as described in claim 15. The pitch of the recesses is 1.2 to 9% with respect to the diameter in the direction orthogonal to the rolling direction of the Hertz contact ellipse at the maximum load.
[0022]
Similarly, the rolling element for a traction drive according to the present invention is a cross-sectional curve obtained by measuring in the axial direction of the rolling element using a surface roughness meter without passing through a filter, as described in claim 16. The pitch of the recesses is 2.4 to 6% with respect to the diameter in the direction orthogonal to the rolling direction of the Hertz contact ellipse at the maximum load.
[0026]
Similarly, the rolling element for a traction drive according to the present invention is characterized in that the concave portion is continuous longer than at least the length of the Hertz contact ellipse.
[0027]
Similarly, the rolling element for a traction drive according to the present invention includes, as described in claim 18, one of the driving side and the driven side of the rolling surface for transmitting the power of the rolling element for traction drive is a recess. It has a convex portion, and the other has a surface fine shape having an average roughness Ra of 0.01 μm or less and a maximum height Ry of 0.1 μm or less at the center line of the cross-sectional curve. At this time, the surface roughness Rz and the maximum height Ry are those defined in JIS-B0601.
[0028]
Similarly, in the rolling element for a traction drive according to the present invention, the combination of the material used for the rolling element and the heat treatment at the time of manufacturing the rolling element is a case-hardening steel material and carburizing and quenching and tempering heat treatment. Combination of case-hardened steel material and carbonitriding quenching and tempering heat treatment, combination of bearing steel material and quenching and tempering heat treatment, combination of bearing steel material and carburizing and quenching and tempering heat treatment, and bearing steel material and carbonitriding and quenching and tempering heat treatment It is characterized by being selected from a combination of heat treatments.
[0029]
Similarly, in the rolling element for a traction drive according to the present invention, as described in claim 20, the rolling element has an input disk and an output disk each having a rolling surface having a toroidal curved annular concave surface. And a power roller having a rolling surface that forms an annular convex shape by being sandwiched between the annular concave rolling surfaces of the input disk and the output disk that are arranged to face each other and that can tilt the roller shaft. And is a component of a half-toroidal continuously variable transmission.
[0030]
[Effects of the Invention]
In the rolling element for a traction drive according to claim 1 of the present invention, in the rolling element for a traction drive that transmits power through the traction oil between the rolling surfaces, the power of at least one of the rolling elements on the driving side and the driven side. Is provided with a shape in which the concave portions and the convex portions of the protrusions are regularly and alternately arranged on the rolling surface for transmitting the light.
[0031]
At this time, in the rolling element for the traction drive, regarding the surface fine shape of the rolling surface, the sectional curve in the sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and passing through the filter is not obtained. The shape of the convex part above the center line, that is, the line drawn to the average height obtained by integrating the cross-sectional curve in the length direction, is a rough trapezoidal shape with rounded corners, a rough crowning shape, a rough elliptical arc shape, Approximate sine wave shape, or a substantially triangular shape with rounded vertices, and λ / AMP, which is a ratio of half AMP of groove depth corresponding to difference in height of wavelength λ and unevenness, is 50 or more Because it is 400 or less, a large traction force is generated while keeping the metal contact small and improving durability, and a traction with excellent traction characteristics that can transmit a large amount of power. Rolling elements are provided.
[0032]
Further, by setting λ / AMP to 50 or more, the local stress generated on the surface can be reduced, so that excellent stability is obtained. On the other hand, by setting λ / AMP to 400 or less, the traction coefficient can be stably improved. And in the said traction drive rolling element, since the recessed part is formed along the spiral around an axis continuously in the rolling direction of the rolling element, a traction drive rolling element capable of exhibiting a larger traction coefficient is provided. The
[0033]
In the rolling element for traction drive according to claim 2 of the present invention, the rolling surface of the other rolling element is smooth, and the hardness at a depth of at least 100 μm from the surface of the rolling element having irregularities is Hv 800 or more. Thus, a rolling element for a traction drive is provided in which the depth of the convex portion hardly changes during use, and is excellent in wear resistance and depression resistance.
[0034]
In the rolling element for a traction drive according to claim 3 of the present invention, since the hardness at a depth of 50 μm from the surface of the rolling element having irregularities is set to Hv 800 or more, the rolling element for traction drive having further excellent wear resistance and depression resistance. A rolling element is provided.
[0035]
In the rolling element for a traction drive according to claim 4 of the present invention, since the compressive residual stress at a depth of 50 μm from the surface of the rolling element having irregularities is set to 800 MPa or more, the traction having further excellent wear resistance and depression resistance. A rolling element for a drive is provided.
[0036]
In the rolling element for a traction drive according to claim 5 of the present invention, the surface of the rolling element having irregularities is work hardened by roller burnishing, so that a rolling element having a desired hardness is obtained.
[0037]
In the rolling element for a traction drive according to claim 6 of the present invention, since the curvature radius of the convex portion on the surface of the rolling element having unevenness is set to 1 mm or more and 8 mm or less, generation of edge stress is suppressed and excessive stress is generated. A rolling element for a traction drive that prevents occurrence and has excellent durability is provided.
[0038]
In the rolling element for a traction drive according to claim 7 of the present invention, in the cross-sectional curve shape, the curvature radius of the top of the convex portion is β (μm), and the height variation from the center line of the cross-sectional curve to the top of the convex portion The standard deviation is σ (μm), the equivalent Young's modulus of the rolling element material is E ′ (Pa), the hardness of the rolling element material is H (Pa), and the plasticity index ψ defined by these relational expressions is 0.2 or less. Therefore, a larger traction coefficient is exhibited and metal contact is further reduced, and a traction drive rolling element having an excellent long life due to traction transmission is provided.
[0039]
In the rolling element for a traction drive according to claim 8 of the present invention, in the cross-sectional curve shape, the radius of curvature near the top of the convex portion in the cross-sectional curve measured by making the vertical and horizontal magnifications of the surface roughness meter equal is 0. By setting the radius of curvature to 1 mm or more, preferably 0.8 mm or more, more preferably 0.8 mm to 10 mm, a rolling element for a traction drive capable of exhibiting a larger traction coefficient is provided. In this case, in particular, by limiting the radius of curvature to 0.8 mm or more, further metal contact is reduced and durability is improved.
[0040]
In addition, the curvature radius (r) of the convex part in a cross-sectional curve has the relationship shown in FIG. That is, t is the length from the center line C1 of the cross-sectional curve to the top of the convex portion, and S is the length from the center line C2 of the convex portion to the intersection C3 of the cross-sectional curve and the center line C1 of the cross-sectional curve. When the radius of curvature (r) is t ² + S ² / 2t.
[0041]
In the rolling element for a traction drive according to claim 9 of the present invention, as shown in FIG. 20, in the cross-sectional curve shape, the unevenness 1 pitch at a position lower by 1/10 of the height difference between the convex part and the concave part from the top of the convex part. Since the ratio of the length L2 of the convex portion, which is the width of the protrusion on the reference line, is 35 to 70% with respect to the length L1 of the minute reference line, the rolling element for a traction drive capable of exhibiting a larger traction coefficient is obtained. Provided.
[0042]
In the rolling element for a traction drive according to claim 10 of the present invention, in the cross-sectional curve shape, the length of the reference line corresponding to one pitch of the unevenness at a position lower by 1/10 of the height difference between the convex portion and the concave portion from the top of the convex portion. On the other hand, since the ratio of the length of the convex portion, which is the width of the protrusion on the reference line, is 50 to 70%, a rolling element for a traction drive that can exhibit a much larger traction coefficient is provided.
[0043]
In the rolling element for a traction drive according to claim 11 of the present invention, in the cross-sectional curve shape, with respect to the reference line for one pitch of the unevenness at a position lower by 1/10 of the height difference between the convex portion and the concave portion from the top of the convex portion. And since the length of the convex part which is a protrusion width | variety is 7-90 micrometers, the rolling element for traction drives which can exhibit a bigger traction coefficient is provided.
[0044]
In the rolling element for a traction drive according to claim 12 of the present invention, in the cross-sectional curve shape, with respect to a reference line corresponding to one pitch of unevenness at a position lower by 1/10 of the height difference between the convex and concave portions from the top of the convex portion Since the length of the convex portion, which is the width of the ridge, is 25 to 80 μm, a rolling element for a traction drive that can exhibit a much larger traction coefficient is provided.
[0045]
In the rolling element for a traction drive according to claim 13 of the present invention, the surface roughness Rz measured with an atomic force microscope in a cross-sectional curve in a range of 10 μm centered on the top of the convex portion as shown in FIG. Is set to 100 nm or less, the rebound to durability due to metal contact is reduced, and a rolling element for a traction drive capable of exhibiting a larger traction coefficient is provided.
[0046]
In the rolling element for a traction drive according to claim 14 of the present invention, since the length of the concave portion, which is the groove width at the center line, is 10 to 40 μm in the cross-sectional curve, the rebound to durability due to metal contact is reduced. A rolling element for a traction drive capable of exhibiting a larger traction coefficient is provided. In this case, if the length of the recess is made larger than 10 μm, the traction characteristics are dramatically improved, and if the length of the recess is made smaller than 40 μm, the occurrence of metal contact is lowered and the durability is dramatically improved. . In addition, the rolling element for traction drive effectively discharges traction oil and can maintain the oil film thickness at an appropriate thickness, thereby reducing metal contact while exhibiting a larger traction coefficient. To maintain a long service life.
[0047]
In the rolling element for a traction drive according to claim 15 of the present invention, the recess pitch is set to 1.2 to 9% with respect to the diameter in the direction perpendicular to the rolling direction of the Hertz contact ellipse at the maximum load in the sectional curve. A rolling element for a traction drive is provided in which a larger traction coefficient is stably exhibited and there is less concern about rebound to durability due to metal contact.
[0048]
In the rolling element for a traction drive according to claim 16 of the present invention, the recess pitch is 2.4 to 6% with respect to the diameter in the direction perpendicular to the rolling direction of the Hertz contact ellipse at the maximum load in the cross-sectional curve. High traction characteristics can be obtained in a more stable state.
[0052]
In the rolling element for traction drive according to claim 17 of the present invention, since the concave portion is continuous longer than at least the length of the Hertz contact ellipse, a rolling element for traction drive capable of exhibiting a large traction coefficient is provided.
[0053]
In the rolling element for a traction drive according to claim 18 of the present invention, one of the driving side and the driven side of the rolling surface for transmitting the power of the rolling element for the traction drive has a concave portion and a convex portion, and the other is The average roughness Ra at the center line of the cross-sectional curve is 0.01 μm or less, and the maximum height Ry is 0.1 μm or less, so that a larger traction coefficient can be exhibited more stably and durability due to metal contact. Provided is a rolling element for a traction drive with less concern about rebounding.
[0054]
In the rolling element for a traction drive according to claim 19 of the present invention, the combination of the material used for the rolling element and the heat treatment at the time of manufacturing the rolling element is a combination of the case hardening steel material and carburizing quenching and tempering heat treatment, the case hardening steel material and carburizing. Selected from a combination of nitriding quenching and tempering heat treatment, a combination of bearing steel material and quenching and tempering heat treatment, a combination of bearing steel material and carburizing and quenching and tempering heat treatment, and a combination of bearing steel material and carburizing and tempering and tempering heat treatment Thus, a rolling element for a traction drive that has good wear resistance and can maintain excellent traction characteristics over a long period of time is provided.
[0055]
In the rolling element for a traction drive according to claim 20 of the present invention, the rolling element has an input disk and an output disk each provided with a rolling surface having a toroidal concave surface shape, and an input disk and an output disk arranged to face each other. It has a traction rolling surface that forms a toroidal convex shape that is sandwiched between the concave traction rolling surfaces of the torus and rolls with the concave traction rolling surface, and the roller shaft can be tilted. It consists of a combination with a power roller and is a component of a half-toroidal type continuously variable transmission, and at least one traction rolling surface of the input disk and output disk or power roller has the above-mentioned surface fine shape, Large power can be transmitted, and the unit size can be reduced and the weight can be reduced. Position toroidal type continuously variable transmission is capable of high output per unit weight is provided.
[0056]
【The invention's effect】
According to the rolling element for a traction drive according to claim 1 of the present invention, in the rolling element for a traction drive that transmits power through the traction oil between the rolling surfaces, the metal contact is kept small and the durability is improved. It is possible to provide a traction drive rolling element with excellent traction characteristics that can generate a large traction force and can transmit a large amount of power. In addition, the local stress generated on the surface can be reduced by setting λ / AMP, which is a ratio of AMP of half the groove depth corresponding to the difference between the wavelength λ of the unevenness and the height difference of the unevenness, to 50 or more. The durability performance can be obtained, and the traction coefficient can be stably improved by setting λ / AMP to 400 or less. Further, by forming the recesses along the spiral around the axis in a continuous manner in the rolling direction of the rolling elements, it is possible to provide a rolling element for a traction drive that can exhibit a larger traction coefficient.
[0057]
According to the rolling element for a traction drive according to claim 2 of the present invention, the same effect as that of claim 1 can be obtained, and the depth of the convex portion is hardly changed during use, and the wear resistance and resistance to wear are reduced. It is possible to provide a rolling element for a traction drive that is excellent in depression.
[0058]
According to the rolling element for a traction drive according to claim 3 of the present invention, the effect similar to that of claims 1 and 2 can be obtained, and the rolling element for traction drive having further excellent wear resistance and depression resistance. Can be provided.
[0059]
According to the rolling element for a traction drive according to the fourth aspect of the present invention, the same effect as in the first to third aspects can be obtained, and the rolling element for a traction drive further improved in wear resistance and depression resistance. Can be provided.
[0060]
According to the rolling element for a traction drive according to the fifth aspect of the present invention, the same effect as in the first to fourth aspects can be obtained, and a rolling element having a desired hardness can be easily obtained.
[0061]
According to the rolling element for a traction drive according to claim 6 of the present invention, the same effects as in claims 1 to 5 can be obtained, and the generation of edge stress is suppressed and the generation of excessive stress is prevented. Thus, a rolling element for a traction drive having excellent durability can be provided.
[0062]
According to the rolling element for a traction drive according to the seventh aspect of the present invention, the same effect as that of the first aspect can be obtained and a larger traction coefficient can be exhibited and the metal contact is further reduced. Therefore, it is possible to provide a rolling element for a traction drive that has a long life due to traction transmission.
[0063]
According to the rolling element for traction drive according to claim 8 of the present invention, it is possible to provide the rolling element for traction drive capable of obtaining the same effect as that of claim 1 or 7 and exhibiting a larger traction coefficient. In particular, by limiting the radius of curvature to 0.8 mm or more, further metal contact can be reduced and durability can be improved.
[0064]
According to the rolling element for traction drive according to claim 9 of the present invention, the rolling element for traction drive capable of obtaining the same effect as that of claims 1, 7 and 8 and exhibiting a larger traction coefficient is provided. can do.
[0065]
According to the rolling element for a traction drive according to claim 10 of the present invention, there is provided a rolling element for traction drive capable of obtaining the same effect as that of claims 1, 7 and 8 and exhibiting a larger traction coefficient. can do.
[0066]
According to the rolling element for a traction drive according to the eleventh aspect of the present invention, the same effects as those of the first and seventh to tenth aspects can be obtained, and a larger traction coefficient can be exhibited in the cross-sectional curve shape. A rolling element can be provided.
[0067]
According to the rolling element for a traction drive according to claim 12 of the present invention, there is provided a rolling element for a traction drive capable of obtaining the same effects as those of claims 1 and 7 to 10 and exhibiting a larger traction coefficient. Can be provided.
[0068]
According to the rolling element for a traction drive according to the thirteenth aspect of the present invention, the same effects as in the first and seventh to twelfth aspects can be obtained, and the rebound to the durability due to the metal contact can be reduced and larger. A rolling element for a traction drive that can exhibit a traction coefficient can be provided.
[0069]
According to the rolling element for a traction drive according to the fourteenth aspect of the present invention, the same effects as those of the first and seventh to thirteenth aspects can be obtained, and the rebound to durability due to the metal contact can be reduced, resulting in a larger traction. A rolling element for a traction drive capable of exhibiting a coefficient can be provided, and traction oil can be effectively discharged, and an oil film thickness can be maintained at an appropriate thickness, which is larger. While exhibiting a traction coefficient, metal contact can be reduced and a long life can be maintained.
[0070]
According to the rolling element for traction drive according to claim 15 of the present invention, the rolling element for traction drive capable of obtaining the same effect as claims 1 and 7 to 14 and exhibiting a larger traction coefficient is provided. can do.
[0071]
According to the rolling element for a traction drive according to the sixteenth aspect of the present invention, the rolling element for a traction drive that can obtain the same effects as those of the first and seventh to fourteenth aspects and that exhibits a larger traction coefficient is provided. Can be provided.
[0075]
According to the rolling element for traction drive according to claim 17 of the present invention, there is provided a rolling element for traction drive capable of obtaining the same effects as those of claims 1 and 7 to 15 and exhibiting a large traction coefficient. be able to.
[0076]
According to the rolling element for a traction drive according to claim 18 of the present invention, the same effects as in claims 1 and 7 to 17 can be obtained, and a larger traction coefficient can be more stably exhibited, and It is possible to provide a rolling element for a traction drive that is less likely to be rebounded to durability due to metal contact.
[0077]
According to the rolling element for a traction drive according to the nineteenth aspect of the present invention, the same effects as those of the first and seventh to eighteenth aspects can be obtained, the wear resistance is improved, and the traction characteristics are excellent over a long period of time. It is possible to provide a rolling element for a traction drive capable of maintaining the above.
[0078]
According to the rolling element for a traction drive according to claim 20 of the present invention, the same effects as those of claims 1 and 7 to 19 can be obtained, large power can be transmitted, and the unit size can be reduced. It is possible to provide a half toroidal continuously variable transmission that can be reduced in size and weight, or increased in output per unit volume and unit weight.
[0079]
【Example】
The rolling method for a traction drive according to the present invention is not particularly limited in its manufacturing method. As a typical example of the manufacturing method, the material is case-hardened steel or bearing steel, and in the case of case-hardened steel. Carburizing quenching tempering or carbonitriding quenching tempering is performed. In the case of bearing steel, quenching tempering, carburizing quenching tempering, or carbonitriding quenching tempering is performed. After the heat treatment, the surface to be the rolling surface is sequentially subjected to grinding, formation of a groove-shaped recess by cutting using a c-BN tool, tape wrap, and scraping of the protrusion. In this case, the convex portions (projections) are alternately arranged at equal intervals. At this time, the shape of the convex portion above the center line of the cross-sectional curve is a rough trapezoidal shape with rounded corners, a rough crowning shape, A substantially elliptic arc shape, a substantially sine wave shape, and a substantially triangular shape with rounded vertices.
[0080]
At this time, in the rolling element for traction drive, as described in claims 1 to 16 of the present invention, by setting the surface fine shape of the rolling surface, it is possible to transmit a large amount of power, Excellent traction characteristics and high rolling fatigue life performance can be achieved under surface pressure.
[0081]
In addition, since a rolling element for a traction drive having excellent traction characteristics is provided, an input disk and an output disk each provided with a rolling surface having a toroidal curved annular ring shape, and an input disposed opposite to each other. A half toroid with excellent traction characteristics due to the combination with a power roller that has a rolling surface that forms an annular convex shape between the disc and the annular concave rolling surface of the output disc and that can tilt the roller shaft A type continuously variable transmission can be constructed.
[0082]
Hereinafter, the rolling element for a traction drive according to the present invention will be described in detail with reference to Examples and Comparative Examples. In addition, it cannot be overemphasized that the rolling element for traction drives concerning this invention is not limited only to the following Examples.
[0083]
(Test method)
In this example, a rolling sliding test of a rolling element (test piece) was performed using a four-cylinder rolling tester shown in FIG. The illustrated four-cylinder rolling tester includes a slave shaft 51 and three main shafts 53 a to 53 c that are arranged parallel to each other around the slave shaft 51 and rotate via planetary gears, and are supported by the slave shaft 51. The three driving-side rolling elements 54a to 54c individually supported by the main shafts 53a to 53c are brought into contact with the outer peripheral surface of the driven side rolling element 52, and one of the three main shafts 53a to 53c ( The driving-side rolling elements 54a to 54c are brought into pressure contact with the outer peripheral surface of the driven-side rolling element 52 by applying a load to 53a) with a pressurizing mechanism. The pressurizing mechanism has three pressurizing arms 55a to 55c arranged in a T shape, holds the arms 55a to 55c so as to be swingable in the vertical direction, and has two horizontal arms 55a arranged linearly. The weight 56 is suspended from the outer end of 55b, and the inner ends of the arms 55a and 55b are vertically overlapped. The remaining one arm 55c overlaps one end portion above the overlapping portion of the horizontal arms 55a and 55b, and the other end portion is a pressurizing portion provided on the rotating shaft 53a of the drive side rolling element 54a. 57.
[0084]
In the four-cylinder rolling test machine, in the pressurizing mechanism, the weights of the left and right weights 56 are applied to the pressurizing unit 57 via the arms 55a to 55c, and the driving-side rolling elements 54a are arranged on the outer peripheral surface of the driven-side rolling element 52. ˜54c are brought into pressure contact, and the traction coefficient can be calculated by measuring the torque generated on the driven shaft 51 by a torque sensor provided on the driven shaft 51 of the driven-side rolling element 52.
[0085]
In this example, a rolling sliding test of a rolling element (test piece) was performed using the four-cylinder rolling tester shown in FIG. 2 to calculate the traction coefficient and qualitatively evaluate the contact state between the cylinders. Therefore, the oil film formation rate was calculated using the electric resistance method. In the test of this example, the slip rate was 0 to 3%, the average slip speed was 30 m / s, the average shaft rotation speed was 10000 rpm, and the slip speed was obtained by giving differentials equally to the main shafts 53a to 53c and the slave shaft 51. Made constant. Furthermore, traction oil set at 150 ° C. was supplied at 2 L / min from the rotational direction entrance. In this example, the traction coefficient and oil film formation rate at a slip rate of 3% were calculated.
[0086]
(Examples 1 to 12, Comparative Examples 1 and 2)
The driven-side rolling element 52 had a diameter = 60 mm, a thickness = 10 mm, and a cylindrical shape with a flat rolling surface. In this example and comparative example, SCr420 steel, SCM420 steel carburized, quenched and tempered, SCM420 steel carbonitrided, quenched and tempered, SUJ2 steel quenched and tempered, and SUJ2 steel carbonitrided and quenched and quenched After grinding the rolling surface using the returned one, the groove is cut on the rolling surface using a polycrystalline c-BN cutting tool, and then the protrusion is scraped off with a tape wrap. In addition, a desired surface irregular shape having a concave and convex shape obtained by alternately arranging groove-shaped concave portions and convex portions of the protrusions was obtained.
[0087]
On the other hand, the outer three driving-side rolling elements 54a to 54c were formed into a cylindrical shape having a crowning shape with a diameter = 60 mm, a thickness = 10 mm, and a rolling surface of R = 30 mm. In this case, a hardened and tempered material of SUJ2 steel was used, and after grinding the rolling surface, the center line average roughness Ra was finished to 0.01 μm and the maximum height Ry to 0.1 μm by tape wrapping.
[0088]
About the driven side rolling element 52, the cross-sectional curve of Examples 1-12 is shown in FIGS. 3-14, and the cross-sectional curve of Comparative Examples 1 and 2 is shown in FIGS. Moreover, the cross-sectional curve of the outer side drive side rolling elements 54a-54c used for Examples 1-12 and Comparative Examples 1 and 2 is shown in FIG.
[0089]
The cross-sectional curve is measured in the axial direction of the rolling element 52 (a direction perpendicular to the rolling direction). About this cross-sectional curve, it measured using the stylus type surface roughness shape measuring machine by Surfacing Co., Ltd., Surfcom 1400. At this time, the stylus of the roughness measuring machine had a spherical tip shape, a radius of curvature of R5 μm, an apex angle of 90 °, and a measurement length of 1 mm.
[0090]
Further, the surface roughness on the top of the convex portion was measured in an AFM contact mode with a scanning size of 10 μm using a Nanoscope-IIIa + D3100 type atomic force microscope manufactured by Digital Instruments.
[0091]
(Comparative Example 3)
The driven-side rolling element 52 had a diameter = 60 mm, a thickness = 10 mm, and a cylindrical shape with a flat rolling surface. After quenching and tempering of SUJ2 steel, the rolling surface was ground and further superfinished. This sectional curve is shown in FIG.
[0092]
On the other hand, the outer three drive-side rolling elements 54a to 54c were formed into a cylindrical shape having a diameter = 60 mm, a thickness = 60 mm, and a crowning shape with a rolling surface of R = 30 mm. In this case, SUJ2 steel quenched and tempered was used, the rolling surface was ground, and superfinishing was further performed. This sectional curve is shown in FIG.
[0093]
(Evaluation results)
Table 1 shows the specifications of Examples 1 to 12 and Comparative Examples 1 to 3 above, and the traction coefficient and oil film formation rate at a slip rate of 3% obtained in Examples and Comparative Examples.
[0094]
[Table 1]

[0095]
As is clear from the results shown in Table 1, in Examples 1 to 12, a good traction coefficient can be stably obtained with respect to Comparative Example 3, and an oil film can be sufficiently formed to reduce metal contact. did it. On the other hand, in Comparative Examples 1 and 2, the oil film is not sufficiently formed, metal contact occurs during measurement of the traction coefficient, the surface roughness deteriorates, vibration increases, and the test is continued. I couldn't.
[0096]
(Examples 13 to 30, Comparative Examples 4 and 5)
The driven-side rolling element 52 had a diameter = 60 mm, a thickness = 10 mm, and a cylindrical shape with a flat rolling surface. In Examples 13 to 30 and Comparative Examples 4 and 5, after using SUJ2 steel quenched and tempered to grind the rolling surface, a polycrystalline c-BN cutting tool was used to cut a groove on the rolling surface. After that, the convex portion was scraped off with a tape wrap, and a desired concave-convex surface fine shape obtained by alternately arranging groove-like concave portions and convex portions of the ridges on the rolling surface was obtained.
[0097]
On the other hand, the outer three driving-side rolling elements 54a to 54c have a cylindrical shape that has a diameter = 60 mm, a thickness = 10 mm, and a crowning shape with a rolling surface R = 30 mm. In this case, use SUJ2 steel quenching and tempering material, grind the rolling surface, and finish the centerline average roughness Ra to 0.02μm and the maximum height Ry to 0.12μm by super finishing. It was.
[0098]
(Evaluation results)
Table 1 shows the specifications of Examples 13 to 30 and Comparative Examples 4 and 5, and the traction coefficient and oil film formation rate at a slip rate of 3% obtained in Examples and Comparative Examples. In Examples 13 to 30, a wide pit coefficient was obtained stably with respect to Comparative Example 3 by increasing the pitch, and an oil film was sufficiently formed to reduce metal contact. In contrast, in Comparative Examples 4 and 5, only the traction coefficient equivalent to that in Comparative Example 3 was obtained.
[0099]
In Examples 13 to 30, the wide pitch gives both the traction coefficient and the oil film formation rate insensitive characteristics to the groove depth, and even if the groove depth becomes smaller due to wear during use, the characteristics are good. There is an excellent effect that it is difficult to change. Moreover, since the tolerance of the variation range of the groove depth can be increased, an excellent characteristic that the groove formation is facilitated can be provided.
[0100]
(Examples 31-34, Comparative Example 6)
In Examples 31 to 34, in making one rolling element, a cylindrical rolling element having a diameter of 26 mm and a flat traction rolling surface was used. SCM420 steel was carbonitrided, quenched and tempered, and after grinding the traction rolling surface, superfinishing was performed. Thereafter, burnishing using a silicon nitride sphere having a diameter of 6 mm was performed. The burnishing conditions were a pressing load of 100 kgf and a feed of 0.1 mm / rev. After that, the groove was cut using a c-BN tool having a cutting edge of 50 μm, and the convex portion was scraped off by tape lapping to obtain a desired concave-convex shape.
[0101]
About the rolling element of Example 34, it is the same until super-finishing processing, and thereafter, steel beads having an average particle diameter of 50 μm and a hardness of 830 Hv are projected from a projection distance of 200 mm to a projection pressure of 5 kgf / cm. ² After spraying at 2 rpm for 60 seconds and further performing the same burnishing as in Examples 31 to 33, grooves were cut and tape lapping was performed to obtain a desired uneven shape.
[0102]
About the rolling element of the comparative example 6, when the superfinishing process was complete | finished, the process process was complete | finished and it used for the test. In addition, about Example 31 and Comparative Example 6, the relationship between the distance from the surface of a rolling surface and hardness is shown in FIG.
[0103]
Regarding the other rolling element, the same ones were used in Examples 31 to 34 and Comparative Example 6. As for the other rolling element, a SCM435 steel made by carbonitriding and quenching and tempering was used so as to form a crowning shape having a diameter of 130 mm, a thickness of 18 mm, and a traction rolling surface of R = 30 mm. The moving surface was finished to Ra 0.02 μm.
[0104]
As these experimental conditions, the two cylinders were pressed against each other and rotated at a load of 1560 kgf, an oil temperature of 90 ° C., an oil supply amount of 2 l / min, an average rolling speed of 2.85 m / s, and a slip rate of −10%. In this case, when the circumferential speed of the φ26 mm cylinder is v1 (m / s) and the circumferential speed of the φ130 mm cylinder is v2 (m / s), the slip ratio is represented by (v1−v2) / v2. Under the above conditions, a cylinder with a diameter of 26 mm is 1 × 10 ⁶ After rotating a number of times, the test piece was removed, and the amount of change in the depth of the unevenness was measured by comparing the shape before the test and the shape after the test.
[0105]
(Evaluation results)
The amount of change in the groove depth was measured with a surface roughness shape measuring instrument Surfcom 1400A manufactured by Tokyo Seimitsu Co., Ltd. The amount of change in groove depth is obtained by subtracting the groove depth of the rolling part from the average value of the non-rolling part, and the results are shown in Table 2. The RLB process in Table 2 is a roller burnishing process, and WPC is an extremely small diameter shot peening process. The above-mentioned SCr420 steel, SCM420 steel, SCM435 steel and SUJ2 steel are classifications of steel materials shown in JIS G4105.
[0106]
[Table 2]

[0107]
As is clear from Table 2, Examples 31 to 34 have a smaller amount of change in groove depth than Comparative Example 6. That is, Examples 31 to 34 can suppress a change in performance due to a decrease in the groove depth, and can stably and continuously exert a large traction force. On the other hand, the change in the groove depth is large in Comparative Example 6, and in this case, the traction coefficient decreases with time, and the time for maintaining a good traction coefficient is shorter than that in the Example. Become.
[Brief description of the drawings]
FIG. 1 is a cross-sectional explanatory view showing a basic configuration of a traction drive type continuously variable transmission.
FIG. 2 is an explanatory perspective view showing an outline of a four-cylinder rolling tester.
FIG. 3 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 1 measured by a surface roughness meter.
FIG. 4 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 2 measured by a surface roughness meter.
FIG. 5 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 3 measured by a surface roughness meter.
FIG. 6 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 4 measured by a surface roughness meter.
FIG. 7 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 5 measured by a surface roughness meter.
FIG. 8 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 6 measured by a surface roughness meter.
FIG. 9 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 7 measured by a surface roughness meter.
FIG. 10 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 8 measured by a surface roughness meter.
FIG. 11 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 9 measured by a surface roughness meter.
FIG. 12 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 10 measured by a surface roughness meter.
FIG. 13 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 11 measured by a surface roughness meter.
FIG. 14 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Example 12 measured by a surface roughness meter.
FIG. 15 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Comparative Example 1 measured by a surface roughness meter.
16 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Comparative Example 2 measured by a surface roughness meter. FIG.
FIG. 17 is a graph showing a cross-sectional curve of a driven-side rolling element 52 of Comparative Example 3 measured by a surface roughness meter.
FIG. 18 is a graph showing cross-sectional curves of driving side rolling elements 54a to 54c of Examples 1 to 12 and Comparative Examples 1 and 2 measured by a surface roughness meter.
FIG. 19 is a graph showing cross-sectional curves of driving-side rolling elements 54a to 54c of Comparative Example 3 measured by a surface roughness meter.
FIG. 20 is an explanatory diagram showing the length of the convex portion on the reference line for one pitch of the concave and convex portions at a position 1/10 lower than the height difference between the convex portion and the concave portion from the top of the convex portion.
FIG. 21 is an explanatory diagram showing a range of 10 μm centered on the top of a convex portion.
22 is a graph showing the relationship between the distance from the rolling surface and the hardness in Example 31 and Comparative Example 6. FIG.
FIG. 23 is an explanatory diagram showing a definition of a curvature radius (r) of a convex portion in a cross-sectional curve.
[Explanation of symbols]
1 Traction drive continuously variable transmission
3 Input disk (rolling element)
5 Output disk (rolling element)
6 Power roller (rolling element)
52 Driven rolling element
54a to 54c Driving side rolling element

Claims (20)

  In a traction drive rolling element that transmits power through traction oil between the rolling surfaces, the surface roughness of the rolling surface that transmits the power of at least one of the driving side and driven side rolling elements The cross-sectional curve shape obtained by measuring the axial direction of the rolling element using a meter and without passing through the filter is a shape in which concave portions that are grooves and convex portions that are ridges are arranged alternately and regularly. The shape of the convex part above the center line of the curve is any one of a general trapezoidal shape with rounded corners, a general crowning shape, a general elliptical arc shape, a general sinusoidal shape, and a general triangular shape with rounded tops. Yes, λ / AMP, which is a ratio of the λ of the unevenness λ and the half AMP of the groove depth corresponding to the height difference of the unevenness, is 50 or more and 400 or less, and the recess is continuously around the axis of rolling of the rolling element. Along the spiral A rolling element for a traction drive characterized by being formed.   2. The rolling element for a traction drive according to claim 1, wherein the rolling surface of the other rolling element is smooth, and the hardness at a depth of at least 100 μm from the surface of the uneven rolling element is Hv 800 or more. .   The rolling element for a traction drive according to claim 1 or 2, wherein the hardness at a depth of 50 µm from the surface of the rolling element having irregularities is Hv 800 or more.   The rolling element for a traction drive according to any one of claims 1 to 3, wherein a compressive residual stress at a depth of 50 µm from the surface of the rolling element having irregularities is 800 MPa or more.   The rolling element for a traction drive according to any one of claims 1 to 4, wherein the surface of the rolling element having irregularities is work hardened by roller burnishing.   The rolling element for a traction drive according to any one of claims 1 to 5, wherein the curvature radius of the convex part on the surface of the rolling element having irregularities is 1 mm or more and 8 mm or less. In the cross-sectional curve shape that is measured in the axial direction of the rolling element using a surface roughness meter and obtained without passing through the filter, the curvature radius of the top of the convex part is β (μm), and the convex part from the center line of the cross-sectional curve The standard deviation of the height variation up to the top is σ (μm), the equivalent Young's modulus of the rolling element material is E ′ (Pa), and the hardness of the rolling element material is H (Pa). The rolling element for a traction drive according to claim 1, wherein the index ψ is 0.2 or less.

  In the cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and passing through the filter, the convex portion of the cross-section curve measured by making the vertical and horizontal magnifications of the surface roughness meter equal. The rolling element for a traction drive according to claim 1 or 7, wherein the radius of curvature near the top is 0.8 mm or more and 10 mm or less.   In the cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and passing through the filter, the unevenness 1 at a position 1/10 lower than the height difference between the convex portion and the concave portion from the top of the convex portion The ratio of the length of the convex part which is the protrusion width | variety on the same reference line with respect to the length of the reference line for a pitch is 35 to 70%, The any one of Claim 1, 7 and 8 characterized by the above-mentioned. Rolling element for traction drive.   In the cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and passing through the filter, the unevenness 1 at a position 1/10 lower than the height difference between the convex portion and the concave portion from the top of the convex portion The ratio of the length of the convex part which is the protrusion width | variety on the same reference line with respect to the length of the reference line for a pitch is 50 to 70%, It is any one of Claim 1, 7 and 8 characterized by the above-mentioned. Rolling element for traction drive.   In the cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and without passing through the filter, on the reference line at a position lower by 1/10 of the height difference between the convex part and the concave part from the top of the convex part The rolling element for a traction drive according to any one of claims 1 and 7 to 10, wherein the length of the convex portion that is the width of the ridge is 7 to 90 µm.   In the cross-sectional curve shape obtained by measuring in the axial direction of the rolling element using a surface roughness meter and without passing through the filter, on the reference line at a position lower by 1/10 of the height difference between the convex part and the concave part from the top of the convex part The rolling element for a traction drive according to any one of claims 1 and 7 to 10, wherein the length of the convex portion that is the width of the ridge is 25 to 80 µm.   Surface roughness measured with an atomic force microscope over a range of 10 μm centered on the top of the convex portion in a cross-sectional curve obtained without using a filter by measuring in the axial direction of the rolling element using a surface roughness meter The rolling element for a traction drive according to any one of claims 1 and 7 to 12, wherein the thickness Rz is 100 nm or less.   In the cross-sectional curve obtained by measuring in the axial direction of the rolling element using a surface roughness meter and not passing through the filter, the length of the recess, which is the groove width at the center line of the cross-sectional curve, is 10 to 40 μm. The rolling element for a traction drive according to any one of claims 1 and 7 to 13.   In the cross-sectional curve obtained without using a filter by measuring in the axial direction of the rolling element using a surface roughness meter, the pitch of the recesses is relative to the diameter in the direction perpendicular to the rolling direction of the Hertz contact ellipse at the maximum load. It is 1.2 to 9%, The rolling element for traction drives in any one of Claim 1, 7-14 characterized by the above-mentioned.   In the cross-sectional curve obtained without using a filter by measuring in the axial direction of the rolling element using a surface roughness meter, the pitch of the recesses is relative to the diameter in the direction perpendicular to the rolling direction of the Hertz contact ellipse at the maximum load. It is 2.4 to 6%, The rolling element for traction drives in any one of Claims 1 and 7-14 characterized by the above-mentioned.   The rolling element for a traction drive according to any one of claims 1 and 7 to 16, wherein the recess is continuous longer than at least the length of the Hertz contact ellipse.   Regarding the rolling surface that transmits the power of the traction drive rolling element, one of the driving side and the driven side has a concave portion and a convex portion, and the other has an average roughness Ra of 0.01 μm or less at the center line of the cross-sectional curve. The rolling element for a traction drive according to any one of claims 1 and 7 to 17, which has a fine surface shape of 0.1 μm or less at a maximum height Ry.   The combination of the material used for the rolling element and the heat treatment during the production of the rolling element is a combination of case hardening steel material and carburizing quenching tempering heat treatment, combination of case hardening steel material and carbonitriding tempering tempering heat treatment, bearing steel material and quenching and tempering. The combination of heat treatment, a combination of bearing steel material and carburizing and quenching and tempering heat treatment, and a combination of bearing steel material and carbonitriding and quenching and tempering and heat treatment are selected. Rolling body for traction drive described in 1.   The rolling element is sandwiched between an input disc and an output disc each having a toroidal curved annular concave surface, and an annular concave rolling surface of the input disc and output disc arranged opposite to each other. And a power roller having a rolling surface having an annular convex shape and capable of tilting a roller shaft, and is a component of a half-toroidal continuously variable transmission. The rolling element for traction drives in any one of 7-19.

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