JP4244725B2

JP4244725B2 - Bearing inner ring fatigue measurement method using SH wave

Info

Publication number: JP4244725B2
Application number: JP2003184685A
Authority: JP
Inventors: 規泰小熊; 剛三上
Original assignee: JTEKT Corp
Current assignee: JTEKT Corp
Priority date: 2003-06-27
Filing date: 2003-06-27
Publication date: 2009-03-25
Anticipated expiration: 2023-06-27
Also published as: JP2005017188A

Description

【０００１】
【発明の属する技術分野】
本発明は、ＳＨ波を用いた軸受の内輪疲労度測定方法に関する。
【０００２】
【従来の技術】
従来、軸受の内輪疲労度測定方法としては、電子線マイクロアナライザー（Electron Prove Micro Analyzer : ＥＰＭＡ）を用いた方法がある。この電子線マイクロアナライザーを用いた方法では、内輪を破壊することによって内輪の軌道面の表層部の一部を取出して、この取出された表層部を研磨して試料を作成した後、この試料に電子線を照射してこの試料から炭素の特性Ｘ線を発生させて、この炭素の特性Ｘ線の測定を行っている。そして、この炭素の特性Ｘ線の測定に基づいて上記取出された表層部中の炭素の含有率を検出して、内輪の軌道面の表層部の疲労度を測定している。
【０００３】
また、他の軸受の内輪疲労度測定方法としては、Ｘ線照射装置を用いた方法もある。このＸ線照射装置を用いた方法では、内輪の軌道面の表層部にＸ線を照射することによって、上記表層部の残留応力および残留オーステナイト量を測定している。そして、この測定結果に基づいて内輪の軌道面の表層部の疲労度を測定している（例えば、特許文献１参照）。
【０００４】
【特許文献１】
特開２０００−３０４７１０号公報
【０００５】
【発明が解決しようとする課題】
しかしながら、上記電子線マイクロアナライザーを用いた内輪疲労度測定方法では、内輪の破壊が必要になるので、疲労度の測定をした内輪を使用できないという問題がある。
【０００６】
また、内輪の破壊や、内輪の軌道面の表層部から取出した試料の研磨等を必要とするので、上記軌道面の表層部の疲労度を測定するときの工数が多くなって、上記軌道面の表層部の疲労度の測定に要する時間が長くなり、コストと労力が大きくなるという問題がある。
【０００７】
一方、上記Ｘ線照射装置を用いた内輪疲労度測定方法では、内輪の疲労度の測定に大掛りなＸ線照射装置を用いるので、このＸ線照射装置を自由に疲労度の測定現場に持ち運びできず、上記軌道面の表層部の疲労度の測定を行う場所が限定されるという問題がある。
【０００８】
また、人体に危険な放射線のＸ線を用いるので、Ｘ線照射装置の操作に熟練を必要とし、上記軌道面の表層部の疲労度の測定を安全かつ簡単にできないという問題がある。
【０００９】
そこで、本発明の目的は、内輪軌道面の疲労度の測定を行う場所が限定されず、かつ、内輪の破壊検査をせずに内輪軌道面の表層部の疲労度を簡単安価かつ安全に測定できる内輪疲労度測定方法を提供することにある。
【００１０】
【課題を解決するための手段】
上記目的を達成するため、請求項１の発明の軸受の内輪疲労度測定方法は、
内輪の軌道面上に転動体によって付けられた転走痕の転走痕幅を測定する転走痕幅測定工程と、
上記測定された転送痕幅をｂ、上記転走痕の幅方向における上記内輪の曲率半径をｒ１、上記転走痕の幅方向における上記転動体の曲率半径をｒ２、上記軌道面の周方向の曲率半径をｒ３、上記転動体の中心を通る軸直角断面の曲率半径をｒ４としたとき、上記転動体の上記軌道面に対する接触楕円の短半径ａを、下記の（１）式から導出する接触楕円短半径導出工程と、
ａ＝（ｂ／２）（（１／ｒ１＋１／ｒ２）／（１／ｒ３＋１／ｒ４））^２／３・・・（１）
上記内輪と同じ材質の金属部材に対するＳＨ波（horizontal polalized shear wave）の固有の伝播速度をＶ、上記転動体の転がり運動による繰り返し応力が最も大きく作用する上記軌道面の表面からの深さの範囲を伝播するＳＨ波の周波数をＦとしたとき、下記の（２）式から周波数Ｆの範囲を計算するＳＨ波周波数計算工程と、
２Ｖ／０.３５ａ≧Ｆ≧２Ｖ／０.５ａ・・・（２）
ＳＨ波送信機とＳＨ波受信機とを上記内輪の軌道面上に互いに離間して配置して、上記ＳＨ波送信機から上記周波数Ｆの範囲内の周波数を有するＳＨ波を送信して、上記軌道面の表面から所定の深さを伝播した上記ＳＨ波を、上記ＳＨ波受信機で受信して、この受信されたＳＨ波に基づいてＳＨ波の伝播速度を測定するＳＨ波伝播速度測定工程とを備え、
上記ＳＨ波伝播速度測定工程で測定されたＳＨ波の伝播速度に基づいて内輪の疲労度を測定することを特徴としている。
【００１１】
尚、この明細書で、表層部といった場合、この表層部という表現には、表面を含むものとする。
【００１２】
また、上記ＳＨ波とは、主振動方向が伝播方向に垂直でかつ材料の表面に略平行な方向で、かつ、材料の表面に沿って伝播する超音波である。上記ＳＨ波は、主振動方向が材料の表面の法線方向で、かつ、材料の表面に沿って伝播する超音波である表面波とは異質な超音波である。
【００１３】
また、上記疲労度は、内輪表層部のひずみと対応しており、ひずみはＳＨ波の伝播速度と対応している。この発明の軸受の内輪疲労度測定方法は、内輪表層部におけるＳＨ波の伝播速度に基づいて、内輪表層部のひずみの度合いを測定し、このひずみの度合いに基づいて内輪の疲労度の度合いを測定するものである。
【００１４】
本発明者は、転動体による軌道面の転走痕の転走痕幅と、上記転動体の転がり運動による繰り返し応力が最も大きく作用する軌道面の表面からの深さを伝播するＳＨ波の周波数に相関関係があることを発見した。
【００１５】
詳細には、本発明者は、転送痕幅をｂ、転走痕の幅方向における上記内輪の曲率半径をｒ１、転走痕の幅方向における転動体の曲率半径をｒ２、軌道面の周方向の曲率半径をｒ３、転動体の中点を通る軸直角断面の曲率半径をｒ４、上記軌道面と同じ材質の金属部材に対するＳＨ波の固有の伝播速度をＶとしたとき、転動体の軌道面に対する接触楕円の短半径ａが、上記（１）式から導出できるという事実と、上記繰り返し応力が最も大きく作用する深さが、接触楕円の短半径ａに依存するという事実と、ＳＨ波が伝播する深さが、ＳＨ波の波長に依存するという事実に着目し、上記ＳＨ波の周波数Ｆの範囲が、上記短半径ａと上記固有の伝播速度Ｖを用いて、上記（２）式から導出できるということを発見した。
【００１６】
上記請求項１の発明の軸受の内輪疲労度測定方法によれば、ＳＨ波送信機と、ＳＨ波受信機とを内輪の軌道面上に所定の間隔を隔てて配置して、ＳＨ波の伝播速度を測定することにより、内輪の疲労度の測定を行うので、上記電子線マイクロアナライザーを用いる疲労度測定方法とは異なり、内輪の疲労度の測定を行うのに内輪を破壊する必要がない。したがって、内輪の疲労度の測定を行うときの工数を大幅に低減できて、内輪の疲労度の測定に要するコストと労力を大幅に低減できる。
【００１７】
また、上記請求項１の発明の軸受の内輪疲労度測定方法によれば、軽くて小型で持ち運び可能なＳＨ波送信機と、ＳＨ波受信機とを用い、かつ、人体に安全なＳＨ波の伝播速度に基づいて内輪の疲労度の測定を行うので、大掛りで人体に危険なＸ線を使用するＸ線照射装置を用いる疲労度測定方法とは異なり、内輪の疲労度の測定を行う場所が限定されず、かつ、内輪の疲労度の測定を安全に行うことができる。
【００１８】
また、上記請求項１の発明の軸受の内輪疲労度測定方法によれば、上記（１）式を用いて、転動体の軌道面に対する接触楕円の短半径ａを導出し、更に、上記（１）式から導き出されたａと、上記固有の伝播速度Ｖとを用いて計算された周波数Ｆの範囲の周波数のＳＨ波を、内輪の表層部に伝播させて、内輪の軌道面の疲労度の測定を行うので、ＳＨ波を、内輪の軌道面の表層部における繰り返し応力が最も大きく作用する箇所を伝播させることができて、内輪の疲労度の測定を精密に行うことができる。
【００１９】
【発明の実施の形態】
以下、本発明を図示の実施の形態により詳細に説明する。
【００２０】
尚、以下の実施形態では、全ての物理量の単位として、ＭＫＳ単位系を採用しているものとする。
【００２１】
図１は、内輪１０の軌道面１０Ａの平面図であり、転動体の一例としての円筒ころの転動によって軌道面１０Ａに付いた転走痕２１を示す図である。また、図２は、上記内輪１０の軌道面１０Ａ上の円筒ころ３１を示す軸方向の部分断面図であり、図３は、図２にＰ１で示す円筒ころ３１の中点を通る軸直角部分断面図である。上記内輪１０は、普通焼入品であるＳＵＪ２鋼から形成されている。尚、図１の参照番号２２は、実際には軌道面１０Ａに痕としてのこらない軌道面１０Ａと、円筒ころ３１（図２および図３参照）との接触楕円であり、図２の参照番号３３は、円筒ころの中心軸である。
【００２２】
先ず、図１、図２および図３を用いて、この発明の軸受の内輪疲労度測定方法の一実施形態としての円筒ころ軸受の内輪１０の疲労度測定方法の接触楕円短半径導出工程を説明する。
【００２３】
この接触楕円短半径導出工程では、軌道面と円筒ころとの接触楕円の長半径の２倍に相当する図１に示す転走痕２２の転走痕幅ｂを、軌道面１０Ａの転走痕から測定した後、この測定された転走痕幅ｂと、図２に示す上記転走痕の幅方向における値が既知の上記内輪の曲率半径ｒ１と、図２に示す上記転走痕の幅方向における値が既知の上記転動体の曲率半径ｒ２と、値が既知の図３に示す上記軌道面の周方向の曲率半径ｒ３と、値が既知の図３に示す上記転動体の中点を通る軸直角断面の曲率半径ｒ４とから、以下の（１）式を用いて、ａで示す接触楕円の短半径を導き出す。
【００２４】
ａ＝（ｂ／２）（（１／ｒ１＋１／ｒ２）／（１／ｒ３＋１／ｒ４））^２／３[ｍ] ・・・（１）
次に、ＳＨ波周波数計算工程を行う。このＳＨ波周波数計算工程では、軌道面と転動体の接触楕円の短半径をａとしたとき、転動体の転がり運動によって繰り返し応力が最も大きく作用する軌道面の表面からの深さが、０.３５ａ以上０.５以下になるという事実と、ＳＨ波の波長をλとしたとき、ＳＨ波が２λの深さを伝播するという事実とから導き出された繰り返し応力が最も大きく作用する深さを伝播するＳＨ波の波長の範囲を示す下記の（３）式と、
０.３５ａ≦２λ≦０.５ａ[ｍ]・・・・（３）
ＳＨ波の内輪１０を伝播する固有の伝播速度（この固有の伝播速度をＶで表わす）と、ＳＨ波の波長λと、ＳＨ波の周波数（この周波数をＦで表わす）との間に成立する下記の（４）式と
Ｆ＝Ｖ／λ[Ｈｚ]・・・・（４）
から導き出された繰り返し応力が最も大きく作用する軌道面の表面からの深さを伝播するＳＨ波の周波数Ｆが満たす関係式である下記の（２）式
０.３５ａ≦２（Ｖ／Ｆ）≦０.５ａ[ｍ]
２Ｖ／（０.３５ａ）≧Ｆ≧２Ｖ／（０.５ａ）[Ｈｚ]・・・（２）
を用いて、上記周波数Ｆの範囲を計算する。
【００２５】
この実施形態では、内輪の材質として普通焼入品であるＳＵＪ２鋼を用いているので、ＳＨ波のＳＵＪ２鋼における固有の伝播速度（３２４０ｍ／ｓ）を上記（２）式のＶに代入することによって導き出された下記の（５）式から、繰り返し応力が最も大きく作用する深さを伝播するＳＨ波の周波数Ｆを計算する。
２×３２４０／（０.３５ａ）≧Ｆ≧２×３２４０／（０.５ａ）[Ｈｚ]
１２９６００／（７ａ）≧Ｆ≧１２９６０／ａ[Ｈｚ]・・・（５）
【００２６】
続いて、ＳＨ波伝播速度測定工程を行う。このＳＨ波伝播速度測定工程では、ＳＨ波送信機１とＳＨ波受信機２が設置された上記軌道面１０Ａを示す平面図である図４と、ＳＨ波送信機１とＳＨ波受信機２が設置された内輪１０の正面図である図５に示すように、ＳＨ波送信機１と内輪１０の軌道面１０Ａとが接触線３で線接触するように、ＳＨ波送信機１を内輪１０の軌道面１０Ａの軸方向の略中央に設置する一方、ＳＨ波受信機２と内輪１０の軌道面１０Ａとが接触線５で線接触するように、ＳＨ波受信機２をＳＨ波送信機１から周方向に離間した状態で内輪１０の軌道面１０Ａの軸方向の略中央に設置する。そして、上記ＳＨ送信機１が内蔵する圧電素子からなるＳＨ波発振部(図示せず)を駆動して、対向面１Ａの有効部分７を、上記（５）式で求めた周波数の範囲内の周波数で振動させて、上記ＳＨ波送信機１から上記（５）式で求めた周波数の範囲内の周波数を有するＳＨ波を発信して、上記ＳＨ送信機１から発信されて内輪１０の転動体の転がり運動によって繰り返し応力が最も大きく作用する深さを伝播したＳＨ波をＳＨ波受信機２で受信することによって、ＳＨ波の伝播速度の測定を行う。
【００２７】
詳細には、ＳＨ波送信機１の接触線３と内輪１０の中心Ｐ０とを結ぶ直線Ｌｒと、ＳＨ波受信機２の接触線５と上記中心Ｐ０とを結ぶ直線Ｌｑとがなす角度を２αとし、ｒを軌道面１０Ａの半径としたとき、ＳＨ波の振幅が０になるＳＨ波の波形のゼロクロス点を計時基準にして、ＳＨ波送信機１の接触線３からＳＨ波受信機２の線接触５までのＳＨ波の伝播時間ｔを求め、以下の（６）式から内輪１０の軌道面１０Ａの表層部におけるＳＨ波の伝播速度ｖを測定する。
ｖ＝（２πｒ・（２α/３６０°））／ｔ[ｍ／ｓ]・・・（６）
【００２８】
最後に、上記ＳＨ波伝播速度測定工程で測定された上記内輪１０の表層部におけるＳＨ波の伝播速度ｖに基づいて、ＳＨ波の伝播速度と対応している内輪１０の表層部のひずみの度合いを測定し、このひずみの度合いに基づいて内輪１０の疲労度の度合いを測定する。
【００２９】
尚、上記実施形態においては、上記ＳＨ波送信機１およびＳＨ波受信機２の軸方向の寸法Ｄ１は、内輪１０の軸方向の寸法Ｄ２の３分の１になっている。また、上記ＳＨ波送信機１の接触線３は、ＳＨ波送信機１の軌道面１０Ａに対する対向面１ＡのうちのＳＨ波を発生する有効部分７に含まれており、上記ＳＨ波受信機２の接触線５は、ＳＨ波受信機２の軌道面１０Ａに対する対向面２ＡのうちのＳＨ波を検知可能な有効部分８に含まれているものとする。
【００３０】
図６は、ＳＨ波の固有の伝播速度を、マルテンサイト鋼におけるＳＨ波の伝播速度の理論値（３２４０ｍ／ｓ）に設定したときの、上記接触楕円短半径ａと、上記繰り返し応力が最も大きく作用する深さの範囲を伝播するＳＨ波の周波数との関係を示す計算例の図である。
【００３１】
例えば、接触楕円短半径ａの値が８.０×１０^−４ｍである場合、図５に示す関係から、共振周波数（送信されるＳＨ波の周波数）が１６.２×１０^６Ｈｚ〜２３.１×１０^６ＨｚのＳＨ波送信機を用いて、内輪の疲労度の測定を行えば、内輪の疲労度を正確に測定できる。
【００３２】
上記実施形態の軸受の内輪疲労度測定方法によれば、ＳＨ波送信機１と、ＳＨ波受信機２とを内輪１０の軌道面１０Ａ上に所定の間隔を隔てて配置して、ＳＨ波の伝播速度を測定することにより、内輪１０の疲労度の測定を行うので、上記電子線マイクロアナライザーを用いる疲労度測定方法とは異なり、内輪１０の疲労度の測定を行うのに内輪１０を破壊する必要がない。したがって、内輪１０の疲労度の測定を行うときの工数を大幅に低減できて、内輪１０の疲労度の測定に要するコストと労力を大幅に低減できる。
【００３３】
また、上記実施形態の軸受の内輪疲労度測定方法によれば、軽くて小型で持ち運び可能なＳＨ波送信機１と、ＳＨ波受信機２とを用い、かつ、人体に安全なＳＨ波の伝播速度に基づいて内輪１０の疲労度の測定を行うので、大掛りで人体に危険なＸ線を使用するＸ線照射装置を用いる疲労度測定方法とは異なり、内輪１０の疲労度の測定を行う場所が限定されず、かつ、内輪１０の疲労度の測定を安全に行うことができる。
【００３４】
また、上記実施形態の軸受の内輪疲労度測定方法によれば、上記（１）式を用いて、転動体の軌道面に対する接触楕円の短半径ａを導出し、更に、このａと、上記固有の伝播速度Ｖ（この実施形態では、３２４０ｍ／ｓ）とを用いて、（５）式より計算された周波数Ｆの範囲の周波数のＳＨ波を用いて、内輪１０の軌道面１０Ａの疲労度の測定を行うので、ＳＨ波を、内輪１０の軌道面１０Ａにおける繰り返し応力が最も大きく作用する深さを伝播させることができる。したがって、内輪１０の疲労度の測定を精密に行うことができる。
【００３５】
尚、上記実施形態の軸受の内輪疲労度測定方法では、この発明の軸受の内輪疲労度測定方法を、ころ軸受に適用したが、この発明の軸受の内輪疲労度測定方法を、深溝玉軸受の内輪や、単列や複列のアンギュラ玉軸受の内輪に適用しても良い。また、この発明を円錐ころ軸受の内輪に適用しても良い。
【００３６】
また、この実施形態の軸受の内輪疲労度測定方法では、内輪の構成素材としてＳＵＪ２（高炭素クロム軸受鋼）の普通焼入品を用いたが、内輪の構成素材として、浸炭焼入を行ったＳＡＥ５１２０鋼等のＳＵＪ２の普通焼入品以外の構成素材を用いても良い。
【００３７】
【発明の効果】
以上より明らかなように、請求項１の発明によれば、ＳＨ波送信機と、ＳＨ波受信機とを内輪軌道面上に所定の間隔を隔てて配置して、ＳＨ波の伝播速度を測定するだけで、内輪の軌道面の疲労度の測定を行うことができるので、内輪の軌道面の疲労度の測定を行うのに内輪を破壊する必要がない。したがって、内輪の軌道面の疲労度の測定を行うときの工数を大幅に低減できて、内輪の軌道面の疲労度の測定に要するコストと労力を大幅に低減できる。
【００３８】
また、請求項１の発明によれば、軽くて小型で持ち運び自由なＳＨ波送信機と、ＳＨ波受信機とを用い、かつ、人体に安全なＳＨ波の伝播速度に基づいて内輪の軌道面の疲労度の測定を行うので、内輪の軌道面の疲労度の測定を行う場所が限定されず、かつ、内輪の軌道面の疲労度の測定を安全に行うことができる。
【００３９】
また、請求項１の発明によれば、上記（１）式を用いて、転動体の軌道面に対する接触楕円の短半径ａを導出し、更に、このａと、上記固有の伝播速度Ｖとを用いて計算された周波数Ｆの範囲の周波数のＳＨ波を用いて、内輪の軌道面の疲労度の測定を行うので、ＳＨ波を、内輪の軌道面の表層部における上記転動体の転がり運動による繰り返し応力が最も大きく作用する箇所を伝播させることができて、内輪の疲労度の測定を精密に行うことができる。
【図面の簡単な説明】
【図１】内輪の軌道面における円筒ころの転走痕を示す図である。
【図２】内輪の軌道面上の円筒ころを示す軸方向の部分断面図である。
【図３】内輪の軌道面上の円筒ころの中点を通る軸直角部分断面図である。
【図４】ＳＨ波送信機とＳＨ波受信機が設置されている軌道面の平面図である。
【図５】ＳＨ波送信機とＳＨ波受信機が設置されている内輪の正面図である。
【図６】接触楕円短半径と、上記転動体の転がり運動による繰り返し応力が最も大きく作用する上記軌道面の表面からの深さの範囲を伝播するＳＨ波の周波数との関係を示す図である。
【符号の説明】
１ＳＨ波送信機
２ＳＨ波受信機
１０内輪
１０Ａ軌道面
２１転走痕
２２接触楕円
３１円筒ころ
ａ接触楕円短半径
ｂ転走痕幅
ｐ１円筒ころの中点
ｒ１転走痕の幅方向における内輪の曲率半径
ｒ２転走痕の幅方向における転動体の曲率半径
ｒ３軌道面の周方向の曲率半径
ｒ４転動体の中点を通る軸直角断面の曲率半径
Ｖ内輪に対するＳＨ波の固有の伝播速度
ｖ内輪に対するＳＨ波の伝播速度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a bearing inner ring fatigue measurement method using SH waves.
[0002]
[Prior art]
Conventionally, as a method for measuring the inner ring fatigue level of a bearing, there is a method using an electron probe micro analyzer (EPMA). In the method using this electron beam microanalyzer, a part of the surface layer portion of the raceway surface of the inner ring is taken out by destroying the inner ring, and the sample is prepared by polishing the extracted surface layer part. A characteristic X-ray of carbon is generated from this sample by irradiation with an electron beam, and the characteristic X-ray of this carbon is measured. And based on the measurement of the characteristic X-rays of carbon, the carbon content in the extracted surface layer portion is detected, and the fatigue level of the surface layer portion of the raceway surface of the inner ring is measured.
[0003]
As another method for measuring the inner ring fatigue level of other bearings, there is a method using an X-ray irradiation apparatus. In the method using this X-ray irradiation apparatus, the residual stress and the residual austenite amount of the surface layer portion are measured by irradiating the surface layer portion of the raceway surface of the inner ring with X-rays. And the fatigue degree of the surface layer part of the track surface of an inner ring is measured based on this measurement result (for example, refer to patent documents 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-304710
[Problems to be solved by the invention]
However, in the inner ring fatigue measurement method using the electron beam microanalyzer, since the inner ring needs to be destroyed, there is a problem that the inner ring whose fatigue degree is measured cannot be used.
[0006]
In addition, because the inner ring is broken or the sample taken from the surface layer of the raceway surface of the inner ring is required, the man-hour when measuring the fatigue level of the surface layer part of the raceway increases, and the raceway surface There is a problem that the time required for the measurement of the fatigue level of the surface layer becomes longer and the cost and labor increase.
[0007]
On the other hand, in the inner ring fatigue measurement method using the X-ray irradiation apparatus, since a large X-ray irradiation apparatus is used to measure the fatigue degree of the inner ring, the X-ray irradiation apparatus can be freely carried to the fatigue measurement site. However, there is a problem that the place where the degree of fatigue of the surface layer portion of the raceway surface is measured is limited.
[0008]
Further, since X-rays of radiation that is dangerous to the human body are used, there is a problem that skill is required for the operation of the X-ray irradiation apparatus, and the measurement of the fatigue level of the surface layer portion of the raceway surface cannot be performed safely and easily.
[0009]
Therefore, the purpose of the present invention is not limited to the place where the fatigue level of the inner ring raceway surface is measured, and the fatigue level of the surface layer portion of the inner ring raceway surface can be measured easily and inexpensively without performing a destructive inspection of the inner ring. An object of the present invention is to provide a method for measuring the inner ring fatigue level.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the method for measuring the inner ring fatigue level of a bearing according to the invention of claim 1 comprises:
A rolling trace width measuring step for measuring a rolling trace width of a rolling trace attached by a rolling element on the raceway surface of the inner ring;
The measured transfer trace width is b, the radius of curvature of the inner ring in the width direction of the rolling trace is r1, the radius of curvature of the rolling element in the width direction of the rolling trace is r2, and the circumferential direction of the raceway surface. When the radius of curvature is r3 and the radius of curvature of the cross section perpendicular to the axis passing through the center of the rolling element is r4, the contact ellipse has a short radius a of the contact ellipse with respect to the raceway surface from the following equation (1). An ellipse short radius deriving step;
a = (b / 2) ((1 / r1 + 1 / r2) / (1 / r3 + 1 / r4)) ^2/3 (1)
The inherent propagation speed of SH wave (horizontal polalized shear wave) to the metal member of the same material as the inner ring is V, and the depth range from the surface of the raceway where the repeated stress due to the rolling motion of the rolling element is the largest. When the frequency of the SH wave propagating through the channel is F, the SH wave frequency calculating step for calculating the range of the frequency F from the following equation (2):
2V / 0.35a ≧ F ≧ 2V / 0.5a (2)
An SH wave transmitter and an SH wave receiver are arranged apart from each other on the raceway surface of the inner ring, and SH waves having a frequency within the range of the frequency F are transmitted from the SH wave transmitter. The SH wave propagation velocity measurement step of receiving the SH wave propagating a predetermined depth from the surface of the raceway surface with the SH wave receiver and measuring the propagation velocity of the SH wave based on the received SH wave. And
It is characterized in that the fatigue level of the inner ring is measured based on the SH wave propagation velocity measured in the SH wave propagation velocity measuring step.
[0011]
In this specification, in the case of the surface layer portion, the expression “surface layer portion” includes the surface.
[0012]
The SH wave is an ultrasonic wave that propagates along the surface of the material in a direction in which the main vibration direction is perpendicular to the propagation direction and substantially parallel to the surface of the material. The SH wave is an ultrasonic wave that is different from a surface wave that is an ultrasonic wave that propagates along the surface of the material and whose main vibration direction is the normal direction of the surface of the material.
[0013]
The fatigue level corresponds to the strain of the inner ring surface layer, and the strain corresponds to the propagation speed of the SH wave. The bearing inner ring fatigue level measuring method of the present invention measures the degree of strain of the inner ring surface layer portion based on the propagation speed of the SH wave in the inner ring surface layer portion, and determines the degree of fatigue level of the inner ring based on the degree of strain. Measure.
[0014]
The inventor of the present invention describes the frequency of the SH wave that propagates the rolling trace width of the rolling trace of the raceway surface by the rolling element and the depth from the surface of the raceway surface where the repeated stress due to the rolling motion of the rolling element is the largest. I found that there is a correlation.
[0015]
More specifically, the inventor sets the transfer trace width to b, the radius of curvature of the inner ring in the width direction of the rolling trace to r1, the radius of curvature of the rolling element in the width direction of the rolling trace to r2, and the circumferential direction of the raceway surface. The radius of curvature of the rolling element is r3, the radius of curvature of the cross section perpendicular to the axis passing through the middle point of the rolling element is r4, and the inherent propagation velocity of the SH wave to the metal member of the same material as the above-mentioned raceway surface is V. The fact that the short radius a of the contact ellipse can be derived from the above equation (1), the fact that the depth at which the repeated stress acts most greatly depends on the short radius a of the contact ellipse, and the propagation of SH waves. Focusing on the fact that the depth to be dependent on the wavelength of the SH wave, the range of the frequency F of the SH wave is derived from the equation (2) using the short radius a and the inherent propagation velocity V. I discovered that I can do it.
[0016]
According to the method for measuring the inner ring fatigue level of the bearing according to the first aspect of the present invention, the SH wave transmitter and the SH wave receiver are arranged on the raceway surface of the inner ring at a predetermined interval to propagate the SH wave. Since the fatigue level of the inner ring is measured by measuring the speed, unlike the fatigue level measurement method using the electron beam microanalyzer, it is not necessary to destroy the inner ring in order to measure the fatigue level of the inner ring. Therefore, the man-hour for measuring the fatigue level of the inner ring can be greatly reduced, and the cost and labor required for measuring the fatigue level of the inner ring can be greatly reduced.
[0017]
According to the bearing inner ring fatigue level measuring method of the first aspect of the present invention, a light, small and portable SH wave transmitter and SH wave receiver are used. Because the inner ring fatigue level is measured based on the propagation speed, it is different from the fatigue level measurement method using an X-ray irradiation device that uses X-rays that are large and dangerous to the human body. However, it is possible to safely measure the fatigue level of the inner ring.
[0018]
Further, according to the method for measuring the inner ring fatigue level of the bearing according to the first aspect of the present invention, the short radius a of the contact ellipse with respect to the raceway surface of the rolling element is derived using the above equation (1), and the above (1) ) And the SH wave having a frequency in the range of the frequency F calculated using the inherent propagation velocity V is propagated to the surface layer portion of the inner ring, and the fatigue level of the raceway surface of the inner ring is calculated. Since the measurement is performed, the SH wave can be propagated through the portion where the repeated stress in the surface layer portion of the raceway surface of the inner ring acts most, and the fatigue degree of the inner ring can be accurately measured.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0020]
In the following embodiment, it is assumed that the MKS unit system is adopted as the unit of all physical quantities.
[0021]
FIG. 1 is a plan view of the raceway surface 10A of the inner ring 10 and shows a rolling trace 21 attached to the raceway surface 10A by rolling of a cylindrical roller as an example of a rolling element. 2 is a partial sectional view in the axial direction showing the cylindrical roller 31 on the raceway surface 10A of the inner ring 10, and FIG. 3 is a portion perpendicular to the axis passing through the midpoint of the cylindrical roller 31 indicated by P1 in FIG. It is sectional drawing. The inner ring 10 is made of SUJ2 steel, which is a normal hardened product. Reference numeral 22 in FIG. 1 is a contact ellipse between the raceway surface 10A that does not actually remain as a trace on the raceway surface 10A and the cylindrical roller 31 (see FIGS. 2 and 3). Reference numeral 33 denotes a central axis of the cylindrical roller.
[0022]
First, the contact ellipse short radius deriving step of the fatigue measurement method of the inner ring 10 of the cylindrical roller bearing as one embodiment of the inner ring fatigue measurement method of the bearing of the present invention will be described with reference to FIGS. To do.
[0023]
In this contact ellipse short radius deriving step, the rolling trace width b of the rolling trace 22 shown in FIG. 1 corresponding to twice the major radius of the contact ellipse between the raceway surface and the cylindrical roller is used as the rolling trace of the raceway surface 10A. , The measured rolling trace width b, the radius of curvature r1 of the inner ring whose known value in the width direction of the rolling trace shown in FIG. 2, and the width of the rolling trace shown in FIG. The radius of curvature r2 of the rolling element whose value in the direction is known, the radius of curvature r3 in the circumferential direction of the raceway surface shown in FIG. 3 whose value is known, and the midpoint of the rolling element shown in FIG. The short radius of the contact ellipse indicated by a is derived from the curvature radius r4 of the cross section perpendicular to the axis through which the following equation (1) is used.
[0024]
a = (b / 2) ((1 / r1 + 1 / r2) / (1 / r3 + 1 / r4)) ^2/3 [m] (1)
Next, an SH wave frequency calculation step is performed. In this SH wave frequency calculation process, when the short radius of the contact ellipse between the raceway surface and the rolling element is a, the depth from the surface of the raceway surface where the repeated stress is the largest due to the rolling motion of the rolling element is 0. Propagating the depth at which the repeated stress derived from the fact that it is 35a or more and 0.5 or less and the fact that the SH wave propagates to a depth of 2λ when the wavelength of the SH wave is λ is the largest. The following formula (3) showing the range of the wavelength of the SH wave to be
0.35a ≦ 2λ ≦ 0.5a [m] (3)
It is established between the inherent propagation speed (this inherent propagation speed is represented by V) of the SH wave inner ring 10, the SH wave wavelength λ, and the frequency of the SH wave (this frequency is represented by F). The following equation (4) and F = V / λ [Hz] (4)
The following equation (2) 0.35a ≦ 2 (V / F) ≦ which is a relational expression satisfied by the frequency F of the SH wave propagating through the depth from the surface of the raceway surface where the repeated stress derived from the maximum is applied. 0.5a [m]
2V / (0.35a) ≧ F ≧ 2V / (0.5a) [Hz] (2)
Is used to calculate the range of the frequency F.
[0025]
In this embodiment, SUJ2 steel, which is a normal hardened product, is used as the material of the inner ring. Therefore, the inherent propagation velocity (3240 m / s) of the SU wave in SUJ2 steel is substituted for V in the above equation (2). The frequency F of the SH wave propagating through the depth at which the repeated stress acts most greatly is calculated from the following equation (5) derived from the above.
2 × 3240 / (0.35a) ≧ F ≧ 2 × 3240 / (0.5a) [Hz]
129600 / (7a) ≧ F ≧ 12960 / a [Hz] (5)
[0026]
Subsequently, an SH wave propagation velocity measurement step is performed. In this SH wave propagation velocity measurement step, FIG. 4 is a plan view showing the orbital surface 10A on which the SH wave transmitter 1 and the SH wave receiver 2 are installed, and the SH wave transmitter 1 and the SH wave receiver 2 As shown in FIG. 5, which is a front view of the installed inner ring 10, the SH wave transmitter 1 is connected to the inner ring 10 so that the SH wave transmitter 1 and the raceway surface 10 </ b> A of the inner ring 10 are in line contact with the contact line 3. The SH wave receiver 2 is moved from the SH wave transmitter 1 so that the SH wave receiver 2 and the raceway surface 10A of the inner ring 10 are in line contact with each other at the contact line 5 while being installed at the approximate center in the axial direction of the track surface 10A. It is installed at the approximate center in the axial direction of the raceway surface 10A of the inner ring 10 while being separated in the circumferential direction. And the SH wave oscillation part (not shown) which consists of a piezoelectric element which the said SH transmitter 1 contains is driven, and the effective part 7 of the opposing surface 1A is within the range of the frequency calculated | required by said (5) Formula. The SH wave transmitter 1 is caused to vibrate at a frequency, and an SH wave having a frequency within the range of the frequency obtained by the above equation (5) is transmitted, and is transmitted from the SH transmitter 1 and is a rolling element of the inner ring 10. The SH wave receiver 2 receives the SH wave that has propagated through the depth at which the repeated stress exerts the greatest effect due to the rolling motion of the SH wave receiver 2 to measure the propagation speed of the SH wave.
[0027]
Specifically, an angle formed by a straight line Lr connecting the contact line 3 of the SH wave transmitter 1 and the center P0 of the inner ring 10 and a straight line Lq connecting the contact line 5 of the SH wave receiver 2 and the center P0 is 2α. Where r is the radius of the orbital plane 10A, the zero cross point of the waveform of the SH wave where the amplitude of the SH wave is 0 is used as a time reference, and the contact line 3 of the SH wave transmitter 1 to the SH wave receiver 2 The propagation time t of the SH wave to the line contact 5 is obtained, and the propagation speed v of the SH wave in the surface layer portion of the raceway surface 10A of the inner ring 10 is measured from the following equation (6).
v = (2πr · (2α / 360 °)) / t [m / s] (6)
[0028]
Finally, based on the SH wave propagation velocity v in the surface layer portion of the inner ring 10 measured in the SH wave propagation velocity measurement step, the degree of strain in the surface layer portion of the inner ring 10 corresponding to the SH wave propagation velocity. And the degree of fatigue of the inner ring 10 is measured based on the degree of strain.
[0029]
In the embodiment, the axial dimension D1 of the SH wave transmitter 1 and the SH wave receiver 2 is one third of the axial dimension D2 of the inner ring 10. Further, the contact line 3 of the SH wave transmitter 1 is included in the effective portion 7 that generates the SH wave in the surface 1A facing the orbital surface 10A of the SH wave transmitter 1, and the SH wave receiver 2 The contact line 5 is assumed to be included in the effective portion 8 capable of detecting the SH wave in the facing surface 2A with respect to the orbital surface 10A of the SH wave receiver 2.
[0030]
FIG. 6 shows that when the inherent propagation velocity of SH waves is set to the theoretical value (3240 m / s) of the propagation velocity of SH waves in martensitic steel, the contact ellipse short radius a and the repetitive stress are the largest. It is a figure of the example of calculation which shows the relationship with the frequency of the SH wave which propagates the range of the depth which acts.
[0031]
For example, when the value of the contact ellipse short radius a is 8.0 × 10 ⁻⁴ m, the resonance frequency (frequency of the transmitted SH wave) is 16.2 × 10 ⁶ Hz to 23 from the relationship shown in FIG. The fatigue level of the inner ring can be accurately measured by measuring the fatigue level of the inner ring using a SH wave transmitter of .1 × 10 ⁶ Hz.
[0032]
According to the bearing inner ring fatigue measurement method of the above embodiment, the SH wave transmitter 1 and the SH wave receiver 2 are arranged on the raceway surface 10A of the inner ring 10 at a predetermined interval, and Since the fatigue level of the inner ring 10 is measured by measuring the propagation speed, the inner ring 10 is destroyed to measure the fatigue level of the inner ring 10, unlike the fatigue level measuring method using the electron beam microanalyzer. There is no need. Therefore, the man-hour when measuring the fatigue degree of the inner ring 10 can be greatly reduced, and the cost and labor required for measuring the fatigue degree of the inner ring 10 can be greatly reduced.
[0033]
In addition, according to the method for measuring the inner ring fatigue level of the bearing according to the above-described embodiment, the SH wave transmitter 1 and the SH wave receiver 2 that are light, small, and portable, and the propagation of the SH wave is safe for the human body. Since the fatigue level of the inner ring 10 is measured based on the speed, the fatigue level of the inner ring 10 is measured unlike a fatigue level measurement method using an X-ray irradiation apparatus that uses X-rays that are large and dangerous to the human body. The place is not limited, and the measurement of the fatigue level of the inner ring 10 can be performed safely.
[0034]
Further, according to the method for measuring the inner ring fatigue level of the bearing according to the above embodiment, the short radius a of the contact ellipse with respect to the raceway surface of the rolling element is derived using the equation (1). Of the raceway surface 10A of the inner ring 10 by using the SH wave having a frequency in the range of the frequency F calculated from the equation (5) using the propagation velocity V of (3240 m / s in this embodiment). Since the measurement is performed, it is possible to propagate the SH wave to a depth at which the repeated stress on the raceway surface 10A of the inner ring 10 acts most. Therefore, the fatigue level of the inner ring 10 can be accurately measured.
[0035]
In the bearing inner ring fatigue measurement method of the above embodiment, the inner ring fatigue measurement method of the bearing of the present invention is applied to a roller bearing. However, the inner ring fatigue measurement method of the bearing of the present invention is applied to a deep groove ball bearing. The present invention may be applied to an inner ring or an inner ring of a single row or double row angular ball bearing. Further, the present invention may be applied to an inner ring of a tapered roller bearing.
[0036]
Further, in the inner ring fatigue measurement method of the bearing of this embodiment, SUJ2 (high carbon chromium bearing steel) is used as the inner ring constituent material, but carburizing and quenching was performed as the inner ring constituent material. Constituent materials other than SUJ2 ordinary quenching products such as SAE5120 steel may be used.
[0037]
【The invention's effect】
As apparent from the above, according to the first aspect of the invention, the SH wave transmitter and the SH wave receiver are arranged on the inner ring raceway surface at a predetermined interval, and the propagation speed of the SH wave is measured. Thus, since the fatigue level of the raceway surface of the inner ring can be measured, it is not necessary to destroy the inner ring in order to measure the fatigue level of the raceway surface of the inner ring. Therefore, the man-hour when measuring the fatigue level of the raceway surface of the inner ring can be greatly reduced, and the cost and labor required for measuring the fatigue level of the raceway surface of the inner ring can be greatly reduced.
[0038]
According to the invention of claim 1, the raceway surface of the inner ring uses a light, small and portable SH wave transmitter and SH wave receiver and is safe for the human body based on the propagation speed of the SH wave. Therefore, the place where the fatigue level of the raceway surface of the inner ring is measured is not limited, and the fatigue level of the raceway surface of the inner ring can be measured safely.
[0039]
According to the invention of claim 1, the short radius a of the contact ellipse with respect to the raceway surface of the rolling element is derived using the above equation (1), and this a and the inherent propagation velocity V are calculated. Since the fatigue level of the raceway surface of the inner ring is measured using the SH wave having a frequency in the range of the frequency F calculated by using the SH wave, the rolling motion of the rolling element in the surface layer portion of the raceway surface of the inner ring is performed. It is possible to propagate the portion where the repeated stress acts most greatly, and it is possible to accurately measure the fatigue degree of the inner ring.
[Brief description of the drawings]
FIG. 1 is a view showing rolling traces of a cylindrical roller on a raceway surface of an inner ring.
FIG. 2 is a partial sectional view in the axial direction showing a cylindrical roller on a raceway surface of an inner ring.
FIG. 3 is a partial cross-sectional view perpendicular to an axis passing through a midpoint of a cylindrical roller on a raceway surface of an inner ring.
FIG. 4 is a plan view of a track surface on which an SH wave transmitter and an SH wave receiver are installed.
FIG. 5 is a front view of an inner ring in which an SH wave transmitter and an SH wave receiver are installed.
FIG. 6 is a diagram showing the relationship between the contact ellipse short radius and the frequency of the SH wave propagating through the range of the depth from the surface of the raceway where the repeated stress caused by the rolling motion of the rolling element acts most greatly. .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 SH wave transmitter 2 SH wave receiver 10 Inner ring 10A Raceway 21 Rolling trace 22 Contact ellipse 31 Cylindrical roller a Contact ellipse short radius b Rolling trace width p1 Cylindrical roller middle point r1 Inner ring in width direction of rolling trace Radius of curvature r2 radius of curvature r3 of the rolling element in the width direction of the rolling trace radius of curvature r4 in the circumferential direction of the raceway curvature radius V of the cross section perpendicular to the axis passing through the middle point of the rolling element V inherent propagation velocity of the SH wave to the inner ring v Propagation speed of SH wave to inner ring

Claims

A rolling trace width measuring step for measuring a rolling trace width of a rolling trace attached by a rolling element on the raceway surface of the inner ring;
The measured transfer trace width is b, the radius of curvature of the inner ring in the width direction of the rolling trace is r1, the radius of curvature of the rolling element in the width direction of the rolling trace is r2, and the circumferential direction of the raceway surface. When the radius of curvature is r3 and the radius of curvature of the cross section perpendicular to the axis passing through the center of the rolling element is r4, the contact ellipse has a short radius a of the contact ellipse with respect to the raceway surface from the following equation (1). An ellipse short radius deriving step;
a = (b / 2) ((1 / r1 + 1 / r2) / (1 / r3 + 1 / r4)) ^2/3 (1)
The inherent propagation velocity of the SH wave to the metal member made of the same material as the inner ring is V, and the SH wave propagating through the range of the depth from the surface of the raceway surface where the repeated stress due to the rolling motion of the rolling element acts most greatly. When the frequency is F, an SH wave frequency calculation step for calculating the range of the frequency F from the following equation (2):
2V / 0.35a ≧ F ≧ 2V / 0.5a (2)
An SH wave transmitter and an SH wave receiver are arranged apart from each other on the raceway surface of the inner ring, and SH waves having a frequency within the range of the frequency F are transmitted from the SH wave transmitter. The SH wave propagation velocity measurement step of receiving the SH wave propagating a predetermined depth from the surface of the raceway surface with the SH wave receiver and measuring the propagation velocity of the SH wave based on the received SH wave. And
A bearing inner ring fatigue degree measuring method, comprising: measuring an inner ring fatigue degree based on the SH wave propagation speed measured in the SH wave propagation speed measuring step.