JP3622458B2

JP3622458B2 - Rolling bearing unit for wheel support

Info

Publication number: JP3622458B2
Application number: JP32105597A
Authority: JP
Inventors: 裕也宮崎; 善久大貫; 孝史桑野; 弘幸沢井
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 1997-08-28
Filing date: 1997-11-21
Publication date: 2005-02-23
Anticipated expiration: 2017-11-21
Also published as: JPH11129703A

Description

【０００１】
【発明の属する技術分野】
この発明に係る車輪支持用転がり軸受ユニットは、自動車の車輪を懸架装置に対して回転自在に支持する為に利用する。
【０００２】
【従来の技術】
自動車の車輪は、車輪支持用転がり軸受ユニットにより懸架装置に支持する。図１７は、従来から広く実施されている車輪支持用転がり軸受ユニットの第１例を示している。この車輪支持用転がり軸受ユニット１は、請求項１に記載した内側部材に相当する、ハブ２と、内輪３と、外輪４と、複数個の転動体５、５とを備える。このうちのハブ２の外周面の外端部（外とは、自動車への組み付け状態で幅方向外寄りとなる側を言い、図４〜６を除く各図の左側となる。反対に幅方向中央寄りとなる側を内と言い、図４〜６を除く各図の右側となる。）には、車輪を支持する為の第一のフランジ６を形成している。又、このハブ２の中間部外周面には第一の内輪軌道７を、同じく内端部には外径寸法が小さくなった段部８を、それぞれ形成している。
【０００３】
上記段部８には、外周面に第二の内輪軌道９を形成した、上記内輪３を外嵌している。又、上記ハブ２の内端部には雄ねじ部１０を形成し、この雄ねじ部１０の先端部を、上記内輪３の内端面よりも内方に突出させている。そして、この雄ねじ部１０に螺合したナット１１と上記段部８の段差面１２との間で上記内輪３を挟持する事により、この内輪３を上記ハブ２の所定位置に結合固定している。尚、上記雄ねじ部１０の先端部外周面には、係止凹部１４を形成している。そして、上記ナット１１を所定のトルクで緊締した後、このナット１１の一部で上記係止凹部１４に整合する部分を直径方向内方にかしめ付ける事により、このナット１１の緩み止めを図っている。
【０００４】
又、上記外輪４の内周面には、上記第一の内輪軌道７と対向する第一の外輪軌道１５及び上記第二の内輪軌道９に対向する第二の外輪軌道１６を形成している。そして、これら第一、第二の内輪軌道７、９と第一、第二の外輪軌道１５、１６との間に上記転動体５、５を、それぞれ複数個ずつ設けている。尚、図示の例では、転動体５、５として玉を使用しているが、重量の嵩む自動車用の転がり軸受ユニットの場合には、これら転動体としてテーパころを使用する場合もある。
【０００５】
上述の様な車輪支持用転がり軸受ユニット１を自動車に組み付けるには、上記外輪４の外周面に形成した第二のフランジ１７により、この外輪４を懸架装置に固定し、上記第一のフランジ６に車輪を固定する。この結果、この車輪を懸架装置に対し回転自在に支持する事ができる。
【０００６】
又、米国特許第５４９０７３２号明細書には、図１８に示す様な構造の車輪支持用転がり軸受ユニット１が記載されている。この従来構造の第２例の場合には、外周面に第一のフランジ６を設けたハブ１８の外周面に第一の内輪４１と第二の内輪３とを外嵌している。そして、上記ハブ１８の内端部で第二の内輪３の内端面よりも内方に突出した部分を直径方向外方に折り曲げる事によりかしめ部１９を形成し、このかしめ部１９と上記ハブ１８の中間部外周面で上記第一のフランジ６の基部に設けた段差面１２ａとの間で、上記第一、第二の内輪４１、３を挟持している。即ち、上記ハブ１８の内端部で上記第二の内輪３よりも内方に突出した部分に形成した円筒部を直径方向外方にかしめ広げる事で上記かしめ部１９を形成し、このかしめ部１９により上記第一、第二の内輪４１、３を、上記段差面１２ａに向け抑え付けている。
【０００７】
【発明が解決しようとする課題】
図１７に示した従来構造の第１例の場合には、雄ねじ部１０の先端部に係止凹部１４を形成する作業、及びナット１１の一部を直径方向内方にかしめ付ける作業が必要になる。この為、車輪支持用転がり軸受ユニット１の部品製造作業及び組立作業が面倒になり、コストが嵩む。
【０００８】
又、図１８に示した第２例の構造の場合、ハブ１８に対して第一、第二の内輪４１、３を結合固定する為のかしめ部１９を、上記ハブ１８に形成する必要がある。従って、上記ハブ１８を、上記かしめ部１９を形成可能な材料により造る必要がある。図１８に示した第２例の構造の場合には、上記ハブ１８自体には内輪軌道を設けず、このハブ１８に外嵌した第一、第二の内輪４１、３の外周面に第一、第二の内輪軌道７、９を設けている為、上記ハブ１８の材料として上記かしめ部１９を形成し易い、炭素の含有率が０．４５重量％未満の炭素鋼を使用できる。但し、上述の様なかしめ部１９の加工に伴い、上記ハブ１８に外嵌した第二の内輪３には大きな荷重が加わる。この為、上記第二の内輪３が変形して、転がり軸受ユニットの（正又は負の）内部隙間が、所望値からずれる可能性がある。そして、上記内部隙間が適正値からずれた場合には、上記第二の内輪３の外周面に形成した第二の内輪軌道９の転がり疲れ寿命の低下を招く事になる。
【０００９】
この様な不都合は、図１７に示した構造と図１８に示した構造とを組み合わせ、ハブ２に第一のフランジ６と第一の内輪軌道７とを設けた構造で、内輪３を上記ハブ２に対しかしめ部１９により結合固定する構造の場合にも発生する。更に、この様な構造を採用した場合には、図１８に示した従来構造のハブ１８の様に、上記ハブ２を炭素の含有率が０．４５重量％未満の炭素鋼により造ると、第一の内輪軌道７部分の硬度を十分に高くできず、十分な耐久性を確保できない。
本発明はこの様な事情に鑑みて、低コストでしかも十分な耐久性を有する車輪支持用転がり軸受ユニットを提供すべく発明したものである。
【００１０】
【課題を解決するための手段】
本発明の車輪支持用転がり軸受ユニットは、一端部外周面に第一のフランジ（６）を、中間部外周面に第一の内輪軌道（７）を、それぞれ形成した内側部材（２ｂ、２ｃ、５１）と、この内側部材（２ｂ、２ｃ、５１）の他端部に形成された、上記第一の内輪軌道（７）を形成した部分よりも外径寸法が小さくなった段部（８）と、外周面に第二の内輪軌道（９）を形成して上記段部（８）に外嵌した内輪（３）と、内周面に上記第一の内輪軌道（７）に対向する第一の外輪軌道（１５）及び上記第二の内輪軌道（９）に対向する第二の外輪軌道（１６）を、外周面に第二のフランジ（１７）を、それぞれ形成した外輪（４）と、上記第一、第二の内輪軌道（７、９）と上記第一、第二の外輪軌道（１５、１６）との間に、それぞれ複数個ずつ設けられた転動体（５）とを備え、上記内側部材（２ｂ、２ｃ、５１）の他端部で少なくとも上記段部（８）に外嵌した内輪（３）よりも突出した部分を直径方向外方にかしめ広げる事で形成したかしめ部（１９、１９ａ）により、上記段部（８）に外嵌した内輪（３）をこの段部（８）の段差面（１２）に向け抑え付けて、この段部（８）に外嵌した内輪（３）を上記内側部材（２ｂ、２ｃ、５１）に結合固定している。
特に、本発明の車輪支持用転がり軸受ユニットに於いては、上記内側部材（２ｂ、２ｃ、５１）は少なくとも上記内輪（３）の突き当て面である段差面（１２）を含む上記段部（８）の一端部分から、上記第一の内輪軌道（７）部分を含み、上記第一のフランジ（６）の基端部の側面部分までを連続して焼き入れ処理により硬化させると共に少なくとも上記内側部材（２ｂ、２ｃ、５１）の他端部で上記内輪（３）よりも突出した部分には上記焼き入れ処理を施さずに生のままとしている。
【００１１】
又、少なくとも上記段部の隅角部で、上記内輪を外嵌固定する円筒状の外周面とこの内輪の端面を突き当てる段差面との連続部に好ましくは、断面形状が四分の一円弧状である曲面部（隅Ｒ部）を形成する。そして、この曲面部の断面の曲率半径を、２．５±１．５mmの範囲に規制する。
【００１２】
【００１３】
【００１４】
【作用】
上述の様に構成する本発明の車輪支持用転がり軸受ユニットにより、懸架装置に対して車輪を回転自在に支持する作用は、従来から知られている車輪支持用転がり軸受ユニットと同様である。
特に、本発明の車輪支持用転がり軸受ユニットの場合には、十分な耐久性を確保しつつ低コスト化を図れる。
【００１５】
【００１６】
又、内輪を軸受鋼等の高炭素鋼製とし、心部まで焼き入れ硬化させた場合には、かしめ部の加工に伴って上記内輪に大きな荷重が加わった場合でも、この内輪の変形を防止して、転がり軸受ユニットの（正又は負の）内部隙間が、所望値からずれる事を防止できる。即ち、内側部材の他端部で内輪よりも突出した部分又はこの内側部材に設けた円筒部をかしめ広げて上記かしめ部を形成する際には、この内側部材の他端部で内輪よりも突出した部分又は円筒部に、直径方向外方に向く大きな荷重を付与する必要がある。この結果、上記かしめ部の形成作業に伴って上記内輪の内周面及び端面に、大きな面圧が作用する。従って、上記内輪の硬度が低いと、上記面圧によりこの内輪が変形して、上記転がり軸受ユニットの内部隙間が所望値からずれてしまう。これに対して、上記内輪を軸受鋼等の高炭素鋼製とし、心部まで焼き入れ硬化させた場合には、この内輪の硬度が十分に高く、上記大きな面圧に拘らず、この内輪が変形する事を防止して、上記内部隙間を所望値に保てる。又、第二の内輪軌道の直径が変化したり、形状精度（真円度、断面形状）が悪化する事を防止して、この第二の内輪軌道の転がり疲れ寿命の低下防止を図れる。
【００１７】
尚、内側部材を構成する炭素鋼中の炭素の含有量を０．４５〜１．１０重量％とし、この内側部材の他端部で内輪よりも突出した部分又はこの他端部に形成した円筒部の硬度を、かしめ加工前に於いてＨｖ２００〜３００とすれば、第一の内輪軌道部分の硬度を確保し、しかも上記内側部材の他端部で内輪よりも突出した部分又は上記円筒部のかしめ広げ作業を十分に行なえる。尚、内側部材を構成する炭素鋼中の炭素の含有量を０．４５〜０．６０重量％とすれば、鍛造後に焼鈍を行なわなくとも良い。又、鍛造後に冷却速度を簡易的に制御して、上記内側部材の他端部で内輪よりも突出した部分又は上記円筒部の硬さをＨｖ２００〜３００にできる。これに対して、内側部材を構成する炭素鋼中の炭素の含有量を０．６０〜１．１０重量％とした場合には、鍛造後に焼鈍を行なう。
【００１８】
【００１９】
【発明の実施の形態】
図１〜４は、本発明の実施の形態の第１例を示している。本例の車輪支持用転がり軸受ユニット１ａは、請求項１に記載した内側部材に相当するハブ２ｂと、内輪３と、外輪４と、複数個の転動体５、５とを備える。このうちのハブ２ｂの外周面の外端寄り部分には、車輪を支持する為の第一のフランジ６を形成している。又、この第一の内輪部材２ｂの中間部外周面には第一の内輪軌道７を、同じく内端部には外径寸法が小さくなった段部８を、それぞれ形成している。この様なハブ２ｂは、炭素の含有率が０．４５〜１．１０重量％である炭素鋼製の素材に鍛造を施す事により、一体に造っている。
【００２０】
又、この様なハブ２ｂの一部外周面で図１に斜格子で示した部分、即ち、上記第一の内輪軌道７部分、上記第一のフランジ６の基端部の側面部分、及び上記段部８の基半部分（内輪３の突き当て面である段差面１２から、この内輪３の嵌合部である円筒状の外周面の一部）には、高周波焼き入れ、浸炭焼き入れ、レーザ焼き入れ等の焼き入れ処理を施して、当該部分の硬度を、Ｈｖ５５０〜９００程度に高くしている。尚、上記各焼き入れ処理のうち、高周波焼き入れ処理が、処理コストが低廉である為、最も好ましい。これに対して、浸炭焼き入れ処理は硬化させない部分に防炭メッキ処理を施す必要がある為、処理コストが嵩む。又、レーザ焼き入れ処理は設備費が嵩む。
【００２１】
尚、上記斜格子で示した焼き入れ処理を施す部分のうち、上記第一の内輪軌道７部分は、上記転動体５の転動面との当接に基づいて大きな面圧を受ける為、転がり疲れ寿命を確保する為に硬化させる。又、上記第一のフランジ６の基端部の側面部分は、車輪を固定した上記第一のフランジ６から受けるモーメント荷重に拘らず、上記基端部分が変形する事を防止する為に硬化させる。更に、上記段部８の基半部分のうち、上記段部８の一部外周面部分は、上記内輪３の嵌合圧力及び上記複数の転動体５から上記内輪３が受けるラジアル荷重に拘らず、この段部８の外周面が変形するのを防止したり、更には、上記内輪３との嵌合部であるこの段部８の外周面に、フレッチング摩耗が発生する事を防止する為に硬化させる。又、上記段部８の段差面１２部分は、後述するかしめ作業により上記内輪３に加わる軸方向荷重に拘らず、この段差面１２が変形するのを防止したり、更には、上記内輪３の外端面との当接面であるこの段差面１２に、フレッチング摩耗が発生する事を防止する為に硬化させる。又、上記段部８の外周面と上記段差面１２との連続部である隅Ｒ部分は、応力集中により変形する事を防止する為に硬化させる。尚、好ましくは、この隅Ｒ部分の断面の曲率半径を、２．５±１．５mmの範囲に規制する。この部分の曲率半径が１mm未満になると、応力集中により亀裂等の損傷を発生する可能性が生じる。反対に、上記部分の曲率半径が４mmを超えると、上記内輪３の端部内周縁と干渉し易くなって、車輪支持用転がり軸受ユニットが難しくなる。
【００２２】
尚、上記斜格子で示した焼き入れ硬化層の内端の軸方向位置（図１のイ点）は、上記内輪３の周囲に配置した複数個の転動体５の中心の軸方向位置（図１のロ点）よりも内側（図１の右側）で、後述するかしめ部１９の基端（かしめ部の外径が段部８の外径よりも大きくなり始める部分）の軸方向位置（図１のハ点）よりも外側（図１の左側）とする。上記焼き入れ硬化層の内端位置をこの様に規制する理由は、上記段部８の外周面部分に存在する焼き入れ硬化層の表面積をできるだけ広くし、しかも上記かしめ部１９の加工を容易にすると共に、上記焼き入れ硬化層の存在に基づいてこのかしめ部１９に亀裂等の損傷が発生しない様にする為である。尚、上述の様な焼き入れ硬化層は、必要とする部分毎に不連続に形成しても良いが、図１に示した本例の様に、隣り合う焼き入れ硬化層同士を連続して形成すれば、ハブ２ｂの強度及び耐久性の向上を図れる。
【００２３】
上記ハブ２ｂの内端部には、上記内輪３を固定する為のかしめ部１９を構成する為の円筒部２０を形成している。図示の例では、この円筒部２０の肉厚は、図３に示した、この円筒部２０を直径方向外方にかしめ広げる以前の状態で、先端縁に向かう程小さくなっている。この為に図示の例の場合には、上記ハブ２ｂの内端面に、凹部に向かう程次第に内径が小さくなるテーパ孔２１を形成している。又、上記内輪３は、ＳＵＪ２等の高炭素クロム軸受鋼の様な高炭素鋼製とし、心部まで焼き入れ硬化させている。
【００２４】
尚、上記ハブ２ｂを構成する炭素鋼中の炭素の含有量は前述の様に０．４５〜１．１０重量％とし、少なくとも上記ハブ２ｂの他端部に形成した円筒部２０の硬度は、図３に示したかしめ加工前に於いてＨｖ２００〜３００とする。この様な条件を満たす事により、前記第一の内輪軌道７部分に必要とする硬度（Ｈｖ５５０〜９００）を確保し、しかも上記円筒部２０のかしめ広げ作業を十分に行なえる。即ち、上記円筒部２０をかしめ広げてかしめ部１９とする際に、この円筒部２０の硬度がＨｖ３００を越えていると、形成されたかしめ部１９にクラックが発生したり、かしめが不十分となってかしめ部１９と内輪３とが密着しなくなって上記ハブ２ｂに対するこの内輪３の締結力が小さくなったりする。又、上記かしめ部１９を形成する為に要する荷重が過大になって、かしめ作業に伴って各軌道面や転動体５、５に圧痕等の損傷を生じ易くなる他、各部の寸法精度が悪化する可能性を生じる。又、ハブ２ｂの機械加工が困難になる。即ち、加工時間が長くなると共に工具寿命が低下し、コスト上昇を招く。
【００２５】
上記ハブ２ｂを構成する炭素鋼中の炭素の含有量が１．１０重量％を越えると、上記円筒部２０の硬度をＨｖ３００以下に抑える事が難しくなる為、上記ハブ２ｂを構成する炭素鋼中の炭素の含有量の上限を１．１０重量％とした。反対に、上記円筒部２０の硬度がＨｖ２００に達しないと、この円筒部２０をかしめる事により形成したかしめ部１９の硬度を確保できず、やはりこのかしめ部１９による上記内輪３の締結力が不足する。上記ハブ２ｂを構成する炭素鋼中の炭素の含有量が０．４５重量％に達しないと、第一の内輪軌道７部分に必要とする硬さ（Ｈｖ５５０〜９００）を確保できず、この第一の内輪軌道７部分の寿命が低下する為、上記ハブ２ｂを構成する炭素鋼中の炭素の含有量の下限を０．４５重量％とした。
【００２６】
尚、上記ハブ２ｂは、上述の様な理由で炭素の含有量を０．４５〜１．１０重量％とした炭素鋼に鍛造加工を施す事により造るが、炭素の含有量が０．４５〜０．６０重量％の場合には、鍛造後に焼鈍処理を施す必要はない。即ち、鍛造後の冷却速度を簡易的に制御する事により、少なくとも上記円筒部２０の硬度をＨｖ２００〜３００に範囲に収める事が可能である。従って、上記ハブ２ｂを鍛造加工により造った後、上記円筒部２０をかしめ部１９に加工する作業を、焼鈍処理を行なう事なく可能になって、このかしめ部１９を備えた車輪支持用転がり軸受ユニットを低コストで造れる。
【００２７】
これに対して、上記ハブ２ｂを構成する炭素鋼中の炭素の含有量を０．６０〜１．１０重量％とした場合には、上記ハブ２ｂを鍛造加工により造った後、焼鈍する必要がある。即ち、炭素鋼中の炭素の含有量を０．６０〜１．１０重量％とした場合でも、鍛造後の冷却速度を制御する事により、上記円筒部２０の硬度をＨｖ２００〜３００程度にする事は可能ではある。但し、冷却速度を相当に小さく（遅く）する必要がある為、長時間を要し、専用の設備も必要になる。この為、上記冷却速度を制御するよりも焼鈍を行なった方が、生産効率の確保並びに生産設備の簡素化の面から好ましい。又、一度焼鈍を行なった方が、上記ハブ２ｂの必要個所を焼き入れする際の焼き入れ性が良くなる。そこで、このハブ２ｂを鍛造加工により造った後、焼鈍処理を施して、少なくとも上記円筒部２０の硬度をＨｖ２００〜３００程度にする。尚、上記ハブ２ｂを構成する炭素鋼中の炭素の含有量を０．６０〜１．１０重量％とした場合で、鍛造後の冷却速度を遅くせず、焼鈍処理も行なわない場合には、前述した様な上記炭素鋼中の含有量が１．１０重量％を越えた場合と同様の問題を生じる。ちなみに、上記炭素鋼中の含有量が１．１０重量％を越えた場合には、鍛造後の冷却速度を遅くしたり、焼鈍処理を施した場合でも、上記円筒部２０の硬度をＨｖ３００以下に抑える事が難しくなる。
【００２８】
上記ハブ２ｂの内端部に上記内輪３を固定すべく、上述の様な円筒部２０の先端部をかしめ広げるには、上記ハブ２ｂが軸方向にずれ動かない様に固定した状態で、図２に示す様に、押型２２を上記円筒部２０の先端部に強く押し付ける。この押型２２の先端面（図２の左端面）中央部には、上記円筒部２０の内側に押し込み自在な円錐台状の凸部２３を形成し、この凸部２３の周囲に断面円弧状の凹部２４を、この凸部２３の全周を囲む状態で形成している。尚、この凹部２４の断面形状、並びに外径Ｒ₂₄及び深さＤ₂₄は、上記円筒部２０を塑性変形させて上記かしめ部１９を形成する際に、この円筒部２０を構成する金属（炭素鋼）に圧縮方向の力を付与しつつ、所定の形状及び大きさを有する上記かしめ部１９を形成する様に規制する。即ち、上記凹部２４の断面形状は、この凹部２４により上記円筒部２０の先端部を塑性変形させる事により得られるかしめ部１９の断面形状が、基端部から先端部に向かう程厚さ寸法が漸次小さくなる様に、特にこの厚さ寸法が先端部で急激に小さくなる様に、外径側に向かう程曲率半径が小さくなる複合曲面としている。又、外径Ｒ₂₄は、形成すべきかしめ部１９の外径Ｒ₁₉と同じか、このかしめ部１９の外径Ｒ₁₉よりも僅かに小さい程度（Ｒ₂₄≦Ｒ₁₉）にしている。更に、深さＤ₂₄は、上記内輪３の内端部内周面及び内端面との間で上記円筒部２０の先端部を挟持する事により上記かしめ部１９を形成した状態で、上記押型２２の先端面と上記内輪３の内端面との間に隙間２５が残留する様に規制する。
【００２９】
上述の様な形状並びに寸法の凸部２３と凹部２４とを有する押型２２を上記円筒部２０の先端部に押し付ければ、この円筒部２０の先端部を直径方向外方にかしめ広げて、上記かしめ部１９を形成する事ができる。そして、このかしめ部１９とハブ２ｂの内端部に形成した段部８の段差面１２との間で上記内輪３を挟持して、この内輪３を上記ハブ２ｂに固定できる。図示の例の場合には、上記円筒部２０の内端面を塑性変形させる事により上記かしめ部１９を形成する最終段階で、上記凹部２４の内面からこのかしめ部１９の外径面に、直径方向内方に向く圧縮力が作用する。従って、このかしめ部１９の外周縁に亀裂等の損傷が発生する事を、有効に防止できる。又、上記かしめ部１９の基端部外径面が当接する、上記内輪３の内端開口周縁部には、断面円弧状の曲面部２６を形成している。従って、上記かしめ部１９の基端部の曲率半径が小さくなる事はなく、この基端部にも無理な応力が加わりにくくなる。
【００３０】
上述の様に本発明の車輪支持用転がり軸受ユニットの場合には、上記ハブ２ｂを、炭素の含有量が０．４５〜１．１０重量％の炭素鋼製とし、前記第一の内輪軌道７部分を焼き入れ処理により硬化させている為、上記第一の内輪軌道７表面の転がり疲れ寿命を、転動体５、５から繰り返し加えられる負荷に拘らず、十分に確保できる。一方、上記円筒部２０には焼き入れ処理を施す事なく、生のままとしている。この為、上記円筒部２０を塑性変形させる為に要する力が徒に大きくなったり、或は上記円筒部２０を塑性変形させる場合にこの円筒部２０に亀裂等の損傷が発生し易くなる事はない。従って、上述の様に第一の内輪軌道７部分の硬度を高くしてこの第一の内輪軌道７部分の転がり疲れ寿命を確保した場合でも、上記ハブ２ｂと内輪３とを結合する為のかしめ部１９の加工が面倒になる事はない。しかも、上記内輪３を軸受鋼等の高炭素鋼製とし、心部まで焼き入れ硬化させている為、上記かしめ部１９の加工に伴って上記内輪３に大きな荷重が加わった場合でも、この内輪３の変形を防止して、転がり軸受ユニットの内部隙間が、所望値からずれる事を防止できる。又、上記内輪３の外周面に形成した第二の内輪軌道９の直径が変化したり、精度が悪化する事を防止して、この第二の内輪軌道９の転がり疲れ寿命の低下防止を図れる。
【００３１】
更に、図示の例の場合には、かしめ部１９を形成する為の円筒部２０の肉厚を先端縁に向かう程小さくしている為、上記ハブ２ｂを炭素の含有量が０．４５〜１．１０重量％の炭素鋼により造った場合でも、上記円筒部２０の先端部を前述の様な押型２２により塑性変形させて上記かしめ部１９を形成する為に要する力が、徒に大きくなる事がない。この為、かしめ作業に伴ってかしめ部１９に亀裂等の損傷が発生したり、或はかしめ部１９により固定する内輪３に、この内輪３の直径を予圧や転がり疲れ寿命等の耐久性に影響を及ぼす程大きく変える様な力が作用する事を、より確実に防止できる。特に、図示の例では、かしめ部１９の先端部に圧縮応力を作用させると共に、このかしめ部１９の基端部の曲率半径を大きくしている為、このかしめ部１９の損傷防止をより有効に図れる。尚、転動体５、５を設けた空間２７の外端開口部はシールリング２８により、内端開口部は蓋体２９により、それぞれ塞いで、上記空間２７に塵芥が進入したり、或はこの空間から潤滑油等が漏出するのを防止している。
【００３２】
次に、図１〜４に示す様な構造を実現する場合に於ける、各部の寸法の適正値に就いて説明する。尚、この値は、一般的な乗用車に組み込む車輪支持用転がり軸受ユニットの場合、即ち、ハブ２ｂに固定すべき内輪３の内径ｒ₃ が２０〜６０mm程度、同じく長さ寸法Ｌ₃ が１５〜４０mm程度の場合で、ハブ２ｂの材質を、炭素の含有量が０．４５〜１．１０重量％である炭素鋼とし、内輪３の材質をＳＵＪ２等の高炭素クロム軸受鋼とした場合に関するものである。
先ず、上記かしめ部１９を加工する以前に於ける上記円筒部２０の先端部の厚さ寸法ｔ₂₀は、１．５〜５mmの範囲が好ましい。又、この円筒部２０の基端部の厚さ寸法Ｔ₂₀は、５〜１０mmの範囲が好ましい。これら先端部及び基端部の厚さ寸法ｔ₂₀及びＴ₂₀をこの範囲に規制すれば、かしめ部１９に亀裂等の損傷が発生する事を防止し、且つ、このかしめ部１９による上記内輪３の支持剛性を確保できる。
即ち、変形量が多くなる円筒部２０の先端部を薄肉にし、この先端部を容易に塑性変形できる様にして、上記損傷の発生防止を有効に図れる。又、上記内輪３を前記段差面１２に向け抑え付ける為に利用する、上記円筒部２０の基端部を厚肉にして、上記内輪３の支持強度を十分に確保できる。
【００３３】
又、上記円筒部２０の長さ寸法Ｌ₂₀は、８〜２０mm程度とする事が好ましい。この長さ寸法Ｌ₂₀が小さ過ぎる（Ｌ₂₀＜８mm）と、上記かしめ部１９を十分に形成できなかったり、或は形成時にかしめ部１９の一部に亀裂等の損傷が発生し易くなる。これに対して、上記長さ寸法Ｌ₂₀が大き過ぎる（Ｌ₂₀＞２０mm）と、ハブ２ｂの内端部に存在する中空部の長さ寸法が長くなり過ぎて、このハブ２ｂの強度が低くなり、上記内輪３に加わるラジアル荷重に基づいて上記ハブ２ｂの内端部が変形し易くなる。尚、上述の様な寸法に規制した円筒部２０を塑性変形させて上記かしめ部１９とする作業は、鍛造加工、揺動プレス加工により行なう事が好ましい。
【００３４】
又、複数の転動体５から上記内輪３に加わる荷重の作用線（転動体５の接触角を表す図２の鎖線αに一致する）は、この内輪３の内周面と前記段部８との嵌合面を通過し、上記かしめ部１９を通過する事がない様にする。この様に規制する理由は、上記荷重が、かしめ部１９を直径方向内方に直接変形させる力として働かない様にして、このかしめ部１９が変形或は破損するのを防止する為である。
【００３５】
次に、上記内輪３のうち、第二の内輪軌道９よりも外側寄り部分（図３のＡ−Ａ線部分）の断面積Ｓ₃ と、当該部分に於けるハブ２ｂの断面積Ｓ_2bとの関係に就いては、Ｓ₃ ＜Ｓ_2bとし、更に好ましくはＳ₃ ≦０．９４Ｓ_2bとする。これら各部の断面積をこの様に規制する理由は、上記ハブ２ｂに対する上記内輪３の支持強度を確保する為である。
即ち、上記かしめ部１９と前記段差面１２との間で上記内輪３を挟持した状態で、この内輪３を軸方向に押圧してこの内輪３の回転を防止する力（軸力）は、上記ハブ２ｂ及び内輪３の軸方向に亙る歪み量の差で定まる。即ち、かしめ加工中は、内輪３の弾性変形量がハブ２ｂの弾性変形量よりも大きい。そして、かしめ加工終了後は、これら内輪３及びハブ２ｂが弾性復帰して、この内輪３に軸方向の力（軸力）が付与される。内輪３を構成する材料とハブ２ｂを構成する材料とは、弾性係数がほぼ同じである為、上述の様にＳ₃ ＜Ｓ_2bとすれば、かしめ加工中の弾性変形量はハブ２ｂよりも内輪３の方が大きい。従って、各部の断面積をこの様に規制すれば、上記内輪３に十分な圧縮荷重を付与し続けて、上記内輪３がハブ２ｂに対して回転する、所謂クリープの発生を有効に防止できる。
【００３６】
次に、内輪３の周囲に配置した複数の転動体５が玉である場合、この転動体５の中心Ｏから上記内輪３の内端面までの距離Ｌ_O3は、転動体５の直径Ｄ₅ の０．７５倍以上（Ｌ_O3≧０．７５Ｄ₅ ）とする事が好ましい。この距離Ｌ_O3を或る程度以上確保する理由は、上記かしめ部１９の形成作業に伴って、上記転動体５の転動面が当接する、前記第二の内輪軌道９部分の直径が大きくなったり、精度（真円度、断面形状）が悪化する事を防止する為である。即ち、この距離Ｌ_O3が小さ過ぎると、上記かしめ部１９の基端部が上記第二の内輪軌道９の内径側部分に存在する様になって、上記かしめ部１９の形成作業に伴い、上記第二の内輪軌道９部分の直径が無視できない程度に大きくなったり上記精度が悪化する可能性が生じる。
【００３７】
次に、前述したかしめ部１９の外径Ｒ₁₉は、内輪３の内径ｒ₃ と、この内輪３の外端部で上記第二の内輪軌道９から外れた部分の外径Ｒ₃ との関係で、次の範囲に規制する事が好ましい。
ｒ₃ ＋０．７（Ｒ₃ −ｒ₃ ）≦Ｒ₁₉≦ｒ₃ ＋１．３（Ｒ₃ −ｒ₃ ）
上記かしめ部１９の外径Ｒ₁₉をこの範囲に規制する事により、このかしめ部１９に割れ等の損傷が発生する事を防止し、且つ、上記ハブ２ｂに対する上記内輪３の支持強度を確保できる。
上記外径Ｒ₁₉が上記範囲よりも大きい方向にずれると、上記損傷が発生し易くなる。反対に、上記外径Ｒ₁₉が上記範囲よりも小さい方向にずれると、上記支持強度を確保する事が難しくなる。
【００３８】
更に、前記曲面部２６の断面形状は、次の様に規制する事が好ましい。先ず、この曲面部２６の始点寄りに傾斜面部分を設け、この傾斜面部分が上記内輪３の中心軸に対し傾斜する角度θ₂₆を、１０〜４５度とする。又、上記内輪３の内周面と上記傾斜面部分とを連続させる部分の曲率半径ｒ₂₆を、２〜８mmとする。更に、上記傾斜面部分と上記内輪３の端面とを連続させる部分の曲率半径Ｒ₂₆を、３〜１０mmとする。
上記曲面部２６の断面形状をこの様に規制する事により、前記円筒部２０を塑性変形させて上記かしめ部１９を形成する際に、このかしめ部１９の基端部分に過大な応力が発生する事がなくなり、この基端部分の破損防止を図れる。
【００３９】
又、上記円筒部２０を塑性変形させて（かしめ広げて）上記かしめ部１９を形成する作業は、図５〜６に示す様な揺動プレス装置４３を使用して行なう事が好ましい。この揺動プレス装置４３は、押型２２と、抑え治具４４と、ホルダ４５とを備える。このうちのホルダ４５は、十分に大きな剛性を有する金属材により有底円筒状に構成しており、底部４６の上面は、ハブ２ｂの外端部をがたつきなく突き当て自在な形状としている。又、上記抑え治具４４は、それぞれが半円弧形に構成した治具素子４７、４７を組み合わせる事により全体を円輪状に構成したもので、内周縁部に円筒状の抑え部４８を備える。又、これら各治具素子４７、４７の外周縁並びに上記ホルダ４５の上端開口部内周面は、上方に向かう程直径が大きくなる方向に傾斜したテーパ面としている。上記各治具素子４７、４７を、通孔４９、４９を挿通した図示しないボルトにより、上記ホルダ４５の上部内周面に設けた取付部５１に結合固定する過程で上記各治具素子４７、４７は、上記テーパ面同士の係合に基づき、直径方向内方に変位する。そして、これら各治具素子４７、４７により構成する上記抑え治具４４の抑え部４８の内周面を、内輪３の外周面に強く押し付ける。この様に構成する為、上記抑え治具４４は、上記内輪３の外径が、寸法公差（５０μｍ）の範囲内でずれても、この内輪３を十分に強く抑え付ける事ができる。
【００４０】
上記円筒部２０をかしめ広げて上記かしめ部１９を形成する際には、上記ホルダ４５を介して上記ハブ２ｂを上方に押圧しつつ、上記押型２２を揺動回転させる。即ち、この押型２２の中心軸と上記ハブ２ｂの中心軸とを角度θだけ傾斜させた状態で、この押型２２を、このハブ２ｂの中心軸を中心として回転させる。この様な揺動プレスにより上記かしめ部１９を形成する際には、上記押型２２の円周方向の一部が前記円筒部２０を押圧する事になり、上記かしめ部１９への加工作業は部分的に且つ円周方向に連続して進行する事になる。この為、一般的な鍛造加工により上記かしめ部１９を形成する場合に比べて、加工時に上記円筒部２０に加える荷重を小さくできる。尚、上記抑え治具４４は、上記押型２２によるかしめ部１９の加工時に上記ハブ２ｂが振れる事を防止して、各軌道面や転動体５、５等、構成各部の寸法並びに形状精度が悪化する事を防止する。
【００４１】
尚、上記押型２２の傾斜角度（揺動角度）θ、揺動回転速度、押し付け荷重等は、上記かしめ部１９を加工すべき車輪支持用転がり軸受ユニットの大きさ等に応じて設計的に定めるが、例えば、前述した様な形状及び寸法の円筒部２０を有する、一般的な乗用車用の車輪支持用転がり軸受ユニットの場合、次の範囲に定める。先ず、傾斜角度θに関しては、０．５〜５．０度程度が好ましい。この傾斜角度θが０．５度未満の場合には、上記円筒部２０を塑性変形させて上記かしめ部１９とする為に要する荷重が大きくなり、各軌道面、転動体の寸法精度並びに形状精度が悪化したり、圧痕等が生じ易くなる。反対に、上記傾斜角度θが５度を越えると、上記円筒部２０を塑性変形させて上記かしめ部１９とする際に上記ハブ２ｂが直径方向に振られて、前記抑え治具４４によってこのハブ２ｂを十分に保持できなくなり、やはり各軌道面、転動体の寸法精度並びに形状精度が悪化したり、圧痕等が生じ易くなる。
【００４２】
又、揺動回転速度に関しては、１００〜５００r.p.m.（min^-1 ）程度が好ましい。この揺動回転速度が１００r.p.m.未満の場合には、加工時間が徒に長くなる。反対に、５００r.p.m.を越えると、加工硬化により、得られるかしめ部１９が硬くなり、割れ等の損傷を発生し易くなる。
更に、上記押し付け荷重に関しては、１５〜５０ｔ程度が好ましい。この押し付け荷重が１５ｔ未満の場合には、上記円筒部２０を十分に塑性変形させる事ができず、良好なかしめ部１９を得られない為、上記ハブ２ｂに対する前記内輪３の結合強度が不足する。反対に、上記押し付け荷重が５０ｔを越えると、各軌道面、転動体の寸法精度並びに形状精度が悪化したり、圧痕等が生じ易くなる。
尚、上述の様な揺動プレス装置４３によりかしめ部１９を形成する事による作用・効果は、上記ハブ２ｂ及び内輪３を構成する金属材料の種類に関係なく得られる。
【００４３】
次に、図７は、本発明の実施の形態の第２例を示している。本例は、車輪の回転速度を検出する為の回転速度検出装置付の車輪支持用転がり軸受ユニットに、本発明を適用したものである。この為に本例の場合には、内輪３の内端部に、この内輪３の肩部３０よりも小径で、この肩部３０よりも内方に突出する段部３１を形成している。そして、この肩部３０に、回転速度検出装置を構成するトーンホイール３２の基端部（図７の左端部）を外嵌固定している。このトーンホイール３２の一部は、上記肩部３０の内端面で上記段部３１の基端部（図７の左端部）周囲部分に突き当てて、軸方向（図７の左右方向）に亙る位置決めを図っている。又、外輪４の内端開口部には合成樹脂製或は金属製のカバー３３を嵌合固定し、このカバー３３に包埋したセンサ３４を、上記トーンホイール３２に対向させて、回転速度検出装置を構成している。
【００４４】
本例の場合、上述の様に内輪３の内端部に段部３１を形成し、ハブ２ｂの内端部に形成したかしめ部１９により、この段部３１を抑え付けている。この様な段部３１を形成した分、上記かしめ部１９と、上記内輪３の外周面に形成した第二の内輪軌道９との軸方向距離が離れる。この結果、上記かしめ部１９の形成に伴う上記第二の内輪軌道９の寸法変化をより小さく抑える事ができる。更には、この第二の内輪軌道９部分だけでなく、上記肩部３０の外径が大きくなる事も防止できる。従って、この肩部３０にシールリングやトーンホイールを外嵌したり、この肩部３０の外周面にシールリップを摺接させたりする場合に、シールリングやトーンホイールの機能が損なわれる事を防止できる。尚、本例の場合も、内輪３の周囲に配置した複数の転動体５が玉である場合、この転動体５の中心Ｏから上記第二の内輪部材３の内端面までの距離Ｌ_O3は、転動体５の直径Ｄ₅ の０．７５倍以上（Ｌ_O3≧０．７５Ｄ₅ ）とする事が好ましい。その他の部分の構成及び作用は、上述した第１例の場合と同様であるから、同等部分には同一符号を付して重複する説明を省略する。尚、本例の場合（並びに以下に述べる第３〜５例及び参考例の第１〜６例の場合）も、ハブのうちで焼き入れ硬化している部分を斜格子で表している。
【００４５】
次に、図８は、本発明の実施の形態の第３例を示している。前述した第１例及び上述した第２例が、何れも、回転しない外輪４の内側にハブ２ｂを回転自在に設けていたのに対して、本例の場合には、外輪４の側が回転する様にし、この外輪４の内径側に、請求項１に記載した内側部材に相当する軸部材５１と、内輪３とを配置している。即ち、本例の場合には、この外輪４が、車輪と共に回転する。回転側と静止側とが、直径方向で内外逆になり、それに伴って軸方向の内外が一部逆になった以外の構成及び作用は、前述した第１例の場合と同様であるから、同等部分には同一符号を付して重複する説明を省略する。
【００４６】
次に、図９は、本発明の実施の形態の第４例を示している。前述した第１〜２例及び上述した第３例が、何れも、回転駆動しない従動輪（ＦＲ車及びＲＲ車の前輪、ＦＦ車の後輪）を回転自在に支持する為の車輪支持用転がり軸受ユニットに本発明を適用していたのに対して、本例の場合には、駆動輪（ＦＲ車及びＲＲ車の後輪、ＦＦ車の前輪、４ＷＤ車の全輪）を回転自在に支持する為の車輪支持用転がり軸受ユニットに本発明を適用したものである。
【００４７】
この為に本例の場合には、内側部材に相当する、ハブ２ｃを円筒状に形成すると共に、このハブ２ｃの内周面に雌スプライン部３５を形成している。そして、この雌スプライン部３５に、等速ジョイント３６に付属で、外周面に雄スプライン部を形成した駆動軸３７を挿入している。一方、上記ハブ２ｃの内端部外周面に形成した段部８には内輪３を外嵌しており、この内輪３の内端面内径寄り部分に段部３８を形成している。そして、上記ハブ２ｃの内端部に形成したかしめ部１９を、上記段部３８に向けかしめ付けている。この状態で上記かしめ部１９は、上記内輪３の内端面よりも内方に突出する事はない。従って、上記等速ジョイント３６の本体部分３９の外端面は、上記内輪３の内端面に当接している。この様に、本体部分３９の外端面を内輪３の内端面に当接させた状態で、上記駆動軸３７の先端部で上記ハブ２ｃの外端面よりも突出した部分にナット４０を螺合し、更に緊締する事により、上記内輪３とハブ２ｃとを、軸方向に亙り強く挟持している。
【００４８】
尚、本例の構造で、内輪３の周囲に配置した複数の転動体５が玉である場合、好ましくは、この転動体５の中心Ｏから上記段部３８の段差面までの距離Ｌ₃₈を、転動体５の直径Ｄ₅ （図３参照）の０．７５倍以上（Ｌ₃₈≧０．７５Ｄ₅ ）とする。その他の部分の構成及び作用は、前述した第１例の場合と同様であるから、同等部分には同一符号を付して重複する説明を省略する。
【００４９】
尚、本例の場合には、ハブ２ｃとして中空円筒状のものを使用している為、このハブ２ｃの断面積を内輪３の断面積よりも大きくする事が難しい場合も考えられる。但し、本例の構造は、使用状態では上記ナット３８の緊締に基づく軸力により、上記内輪３をハブ２ｃの段差面１２に強く押し付けるので、この内輪３から上記かしめ部１９に、このかしめ部１９を緩める方向に作用する力は限られたものとなる。従って、上記断面積の関係を満たせなくても、上記かしめ部１９の耐久性が損なわれる事はない。
【００５０】
次に、図１０は、本発明の実施の形態の第５例を示している。本例の場合には、ハブ２ｃの内端部に形成したかしめ部１９ａを、内輪３の内端面に向けかしめ付けて、このかしめ部１９ａを、この内輪３の内端面よりも軸方向内方に突出させている。又、このかしめ部１９ａの内側面側に円輪状の平坦面４２を形成し、この平坦面４２と等速ジョイント３６の本体部分３９の外端面とを当接させている。上記かしめ部１９ａは、生のままの炭素鋼であるが、上記平坦面４２により上記本体部分３９の外端面と広い面積で当接するので、ナット４０の緊締時にも、当接部に加わる面圧が極端に高くなる事はない。従って、長期間に亙る使用に拘らず、上記かしめ部１９ａがへたる事を防止して、このかしめ部１９ａのへたりにより、上記ナット４０の緩みや転動体５、５設置部分のがたつきが発生する事を有効に防止できる。その他の部分の構成及び作用は、上述した第４例の場合と同様であるから、同等部分には同一符号を付して重複する説明を省略する。
【００５１】
次に、図１１〜１３は、本発明から外れる本発明の参考例の第１〜３例を示している。上述した本発明の実施の形態の第１〜５例の場合には、何れもかしめ部１９を形成する部材に施す焼き入れ硬化層を連続的に形成していたのに対し、参考例の第１〜３例の場合、上記焼き入れ硬化層は、特に必要とする部分毎に不連続に形成している。即ち、図１１に示した参考例の第１例の場合は、第一の内輪軌道７部分と段差面１２及びこの段差面１２の内周寄り部に存在する隅Ｒ部とにのみ、図１２に示した参考例の第２例の場合は、第一の内輪軌道７部分と段差面１２及び上記隅Ｒ部及び段部８の基半部外周面とにのみ、図１３に示した参考例の第３例の場合は、第一の内輪軌道７部分及び第一のフランジ６の基端部分と段差面１２及び上記隅Ｒ部及び段部８の基半部外周面とにのみ、それぞれ上記焼き入れ硬化層を形成している。但し、前述した通り、上記焼き入れ硬化層は、上述の様に特に必要とする部分毎に不連続に形成するよりも、図１、７、８、９、１０に示した本発明の実施の形態の第１〜５例の様に、隣り合う焼き入れ硬化層同士を連続して形成した方が、上記焼き入れ硬化層を施す部材の強度及び耐久性の向上を図れる。その他の部分の構成及び作用は、前述した本発明の実施の形態の第１例の場合と同様である。
【００５２】
次に、図１４は、やはり本発明から外れる、本発明の参考例の第４例を示している。本参考例の車輪支持用転がり軸受ユニットは、第一、第二の内輪軌道７、９を、ハブ２ｄの段部８ａに外嵌した第一、第二の内輪４１、３の外周面に、それぞれ形成している。この様な第一、第二の各内輪４１、３は、共にＳＵＪ２等の高炭素クロム軸受鋼の様な高炭素鋼製とし、心部まで焼き入れ硬化させている。又、これら第一、第二の内輪４１、３は、上記段部８ａに外嵌した状態で、上記ハブ２ｄの内端部に形成したかしめ部１９と第一のフランジ６の基部に形成した段差面１２との間に挟持している。
【００５３】
又、本参考例の場合、上記ハブ２ｄは、炭素の含有量が０．４５重量％未満の炭素鋼とする事が可能となる。そして、図１４に斜格子で示した部分、即ち、上記第一のフランジ６の基端部分、上記段差面１２を含む上記段部８ａの基端部分、及び上記段部８ａの外周面の内端寄り部を除く部分に焼き入れ処理を施して、当該部分の硬度を高くしている。但し、少なくとも上記かしめ部１９を形成する部分である上記ハブ２ｄの円筒部２０には、上記焼き入れ処理を施さずに生のままとしている。尚、ハブ２ｄの上記各部分に焼き入れ処理を施す理由、及び上記斜格子で示した焼き入れ硬化層の内端の軸方向位置（図１４のイ点）を規制する理由は、前述した本発明の実施の形態の第１例の場合と同様である。
【００５４】
上述の様に構成する本参考例の車輪支持用転がり軸受ユニットの場合、ハブ２ｄ自体には内輪軌道を設けていない為、このハブ２ｄの材料としてかしめ部１９を形成し易い、炭素の含有量が０．４５重量％未満の炭素鋼を使用できる。但し、上記ハブ２ｄは上述の図１４に斜格子で示した部分に焼き入れ硬化層を形成している。この為、上記焼き入れ硬化層を形成した部分にフレッチング摩耗が発生したり、或はこの焼き入れ硬化層を形成した部分が変形する事を防止して、上記ハブ２ｄの強度及び耐久性を確保できる。一方、少なくとも上記ハブ２ｄに設けた円筒部２０に、上記焼き入れ処理を施さず生のままとしている為、上記ハブ２ｄと第一、第二の内輪４１、３とを結合する為のかしめ部１９の加工が面倒になったり、このかしめ部１９に損傷が発生する事はない。
【００５５】
又、上記段部８ａに外嵌する第二の内輪３を軸受鋼等の高炭素鋼製とし、心部まで焼き入れ硬化させている。この為、前述した本発明の実施の形態の第１例の内輪３の場合と同様、上記ハブ２ｄに形成するかしめ部１９の加工に伴って上記第二の内輪３に大きな荷重が加わった場合でも、この第二の内輪３の変形を防止して、転がり軸受ユニットの内部隙間が、所望値からずれる事を防止できる。又、この第二の内輪３の外周面に形成した第二の内輪軌道９の直径が変化したり、精度が悪化する事を防止して、この第二の内輪軌道９の転がり疲れ寿命の低下防止を図れる。尚、本参考例の場合、上記ハブ２ｄを、炭素の含有量が０．４５〜１．１０重量％の炭素鋼製とする事もできる。この場合には、上記ハブ２ｄの強度及び耐久性は更に向上する。その他の部分の構成及び作用は、前述した本発明の実施の形態の第１例の場合と同様である。
【００５６】
尚、本参考例（並びに後述する参考例の第５〜６例）の場合、上記ハブ２ｄを構成する炭素鋼中の炭素の含有量を０．２０〜１．１０重量％の範囲に規制し、少なくとも上記円筒部２０の硬度を、かしめ加工前でＨｖ２００〜３００とする。上記ハブ２ｄは、この様な条件を満たす炭素鋼に鍛造加工を施す事により造る。又、上記ハブ２ｄを構成する炭素鋼中の炭素の含有量が０．２０〜０．６０重量％の範囲である場合には、鍛造加工後、上記円筒部２０をかしめ広げる以前に於いて、少なくともこの円筒部２０に焼鈍処理を施さない。これに対して、上記ハブ２ｄを構成する炭素鋼中の炭素の含有量が０．６０〜１．１０重量％の範囲である場合には、鍛造加工後、上記円筒部２０をかしめ広げる以前に於いて、少なくともこの円筒部２０に焼鈍処理を施す。ハブ２ｄの硬度、鍛造加工後に於ける焼鈍の要否に就いては、前述の本発明の実施の形態の第１例の場合と同様である。
【００５７】
次に、図１５〜１６は、やはり本発明から外れる本発明の参考例の第５〜６例を示している。これら第５〜６例の場合には、ハブ２ｄに施す焼き入れ硬化層を、転がり軸受の使用時に、特に大きな荷重を受ける部分にのみ形成している。即ち、図１５に示した参考例の第５例の場合は、段差面１２を含む上記段部８ａの基端部分にのみ、図１６に示した参考例の第６例の場合は、上記段差面１２を含む上記段部８ａの基端部分及び上記第一のフランジ６の基端部分にのみ、それぞれ上記焼き入れ硬化層を形成している。その他の部分の構成及び作用は、上述した参考例の第４例の場合と同様である。
【００５８】
又、図示は省略したが、以上に述べた各実施の形態で、各かしめ部１９と内輪（第二の内輪）３とは、必ずしも対向部分の全面に亙って密接しなくても良い。対向部分の一部に隙間が存在しても、本発明の作用・効果は同様に得られる。尚、上記かしめ部１９を形成する以前に於ける円筒部２０の硬度はＨｖ２００〜３００程度であるが、この円筒部２０をかしめ広げて上記かしめ部１９とした状態では、加工硬化によりこのかしめ部１９の硬度は、Ｈｖ２００〜３００よりも大きくなる。
【００５９】
【発明の効果】
本発明の車輪支持用転がり軸受ユニットは、以上に述べた通り構成され作用するので、低コストでしかも十分な耐久性を有する車輪支持用転がり軸受ユニットを実現できる。
更に、図示の例の様に、かしめ部を形成する為の円筒部の形状を、この円筒部を直径方向外方にかしめ広げる以前の状態で、先端縁に向かう程小さくする事により、かしめ部に亀裂等の損傷が発生する事を防止すると共に、このかしめ部によりハブに固定される内輪の直径が実用上問題になる程変化する事を防止できる。そして、この内輪がその固定作業に基づいて損傷する可能性を低くすると共に予圧を適正値に維持でき、しかも部品点数、部品加工、組立工数の減少により、コスト低減を図れる。
【図面の簡単な説明】
【図１】本発明の実施の形態の第１例を示す半部断面図。
【図２】第１例の構造の製造時に内輪を固定する為、ハブの内端部をかしめ広げる状態を示す部分拡大断面図。
【図３】同じくハブの内端部をかしめ広げる以前の状態で示す部分拡大断面図。
【図４】図３のＡ−Ａ断面図。
【図５】揺動プレス装置の要部縦断面図。
【図６】揺動プレス装置に組み込む抑え治具の平面図。
【図７】本発明の実施の形態の第２例を示す半部断面図。
【図８】同第３例を示す半部断面図。
【図９】同第４例を示す半部断面図。
【図１０】同第５例を示す半部断面図。
【図１１】本発明の参考例の第１例を示す半部断面図。
【図１２】同第２例を示す半部断面図。
【図１３】同第３例を示す半部断面図。
【図１４】同第４例を示す半部断面図。
【図１５】同第５例を示す半部断面図。
【図１６】同第６例を示す半部断面図。
【図１７】従来構造の第１例を示す半部断面図。
【図１８】同第２例を示す断面図。
【符号の説明】
１、１ａ車輪支持用ハブユニット
２、２ａ、２ｂ、２ｃ、２ｄハブ
３内輪（第二の内輪）
４外輪
５転動体
６第一のフランジ
７第一の内輪軌道
８、８ａ段部
９第二の内輪軌道
１０雄ねじ部
１１ナット
１２、１２ａ段差面
１３第二の内輪部材
１４係止凹部
１５第一の外輪軌道
１６第二の外輪軌道
１７第二のフランジ
１８ハブ
１９、１９ａかしめ部
２０円筒部
２１テーパ孔
２２押型
２３凸部
２４凹部
２５隙間
２６曲面部
２７空間
２８シールリング
２９蓋体
３０肩部
３１段部
３２トーンホイール
３３カバー
３４センサ
３５雌スプライン部
３６等速ジョイント
３７駆動軸
３８段部
３９本体部分
４０ナット
４１第一の内輪
４２平坦面
４３揺動プレス装置
４４抑え治具
４５ホルダ
４６底部
４７治具素子
４８抑え部
４９通孔
５０取付部
５１軸部材 [0001]
BACKGROUND OF THE INVENTION
The wheel support rolling bearing unit according to the present invention is used for rotatably supporting the wheel of an automobile with respect to a suspension device.
[0002]
[Prior art]
The wheels of the automobile are supported on the suspension device by a rolling bearing unit for supporting the wheels. FIG. 17 shows a first example of a wheel bearing rolling bearing unit that has been widely used in the past. This wheel supporting rolling bearing unit 1 isCorresponding to the inner member according to claim 1,A hub 2, an inner ring 3, an outer ring 4, and a plurality of rolling elements 5 and 5 are provided. Out of these, the outer end of the outer peripheral surface of the hub 2 (outside means the side that is outward in the width direction when assembled to the automobile, and is the left side of each figure excluding FIGS. 4 to 6. The first flange 6 for supporting the wheel is formed on the side closer to the center is called the inner side, and is the right side of each figure except FIGS. A first inner ring raceway 7 is formed on the outer peripheral surface of the intermediate portion of the hub 2, and a step portion 8 having a smaller outer diameter is formed on the inner end portion.
[0003]
The step 8 is fitted with the inner ring 3 having a second inner ring raceway 9 formed on the outer peripheral surface thereof. Further, a male screw portion 10 is formed at the inner end portion of the hub 2, and a tip portion of the male screw portion 10 is projected inward from the inner end surface of the inner ring 3. The inner ring 3 is clamped and fixed to a predetermined position of the hub 2 by sandwiching the inner ring 3 between a nut 11 screwed into the male threaded portion 10 and a stepped surface 12 of the stepped portion 8. . A locking recess 14 is formed on the outer peripheral surface of the distal end portion of the male screw portion 10. Then, after tightening the nut 11 with a predetermined torque, a portion of the nut 11 that matches the locking recess 14 is caulked inward in the diametrical direction, thereby preventing the nut 11 from loosening. Yes.
[0004]
A first outer ring raceway 15 that faces the first inner ring raceway 7 and a second outer ring raceway 16 that faces the second inner ring raceway 9 are formed on the inner peripheral surface of the outer ring 4. . A plurality of rolling elements 5 and 5 are provided between the first and second inner ring raceways 7 and 9 and the first and second outer ring raceways 15 and 16, respectively. In the illustrated example, balls are used as the rolling elements 5 and 5. However, in the case of a rolling bearing unit for automobiles that is heavy in weight, tapered rollers may be used as these rolling elements.
[0005]
In order to assemble the wheel bearing rolling bearing unit 1 as described above to an automobile, the outer ring 4 is fixed to the suspension device by the second flange 17 formed on the outer peripheral surface of the outer ring 4, and the first flange 6 Secure the wheels to the As a result, this wheel can be rotatably supported with respect to the suspension device.
[0006]
US Pat. No. 5,490,732 describes a wheel bearing rolling bearing unit 1 having a structure as shown in FIG. In the case of the second example of this conventional structure, the first inner ring 41 and the second inner ring 3 are fitted on the outer peripheral surface of the hub 18 provided with the first flange 6 on the outer peripheral surface. A caulking portion 19 is formed by bending a portion of the inner end portion of the hub 18 that protrudes inward from the inner end surface of the second inner ring 3 outward in the diametrical direction, and the caulking portion 19 and the hub 18 are formed. The first and second inner rings 41 and 3 are sandwiched between the stepped surface 12a provided at the base of the first flange 6 at the outer peripheral surface of the intermediate portion. That is, the caulking portion 19 is formed by caulking and expanding the cylindrical portion formed at the inner end portion of the hub 18 inwardly from the second inner ring 3 in the diametrical direction. 19, the first and second inner rings 41 and 3 are pressed against the step surface 12a.
[0007]
[Problems to be solved by the invention]
In the case of the first example of the conventional structure shown in FIG. 17, it is necessary to perform the operation of forming the locking recess 14 at the tip of the male screw 10 and the operation of caulking a part of the nut 11 inward in the diameter direction. Become. For this reason, the parts manufacturing work and assembling work of the wheel bearing rolling bearing unit 1 become troublesome, and the cost increases.
[0008]
Further, in the case of the structure of the second example shown in FIG. 18, it is necessary to form a caulking portion 19 on the hub 18 for connecting and fixing the first and second inner rings 41 and 3 to the hub 18. . Therefore, the hub 18 needs to be made of a material capable of forming the caulking portion 19. In the case of the structure of the second example shown in FIG. 18, the hub 18 itself is not provided with an inner ring raceway, and the first and second inner rings 41, 3 externally fitted to the hub 18 are provided on the outer peripheral surfaces. Since the second inner ring raceways 7 and 9 are provided, carbon steel having a carbon content of less than 0.45 wt%, which can easily form the caulking portion 19 as the material of the hub 18, can be used. However, with the processing of the caulking portion 19 as described above, a large load is applied to the second inner ring 3 fitted on the hub 18. For this reason, the second inner ring 3 may be deformed, and the (positive or negative) internal clearance of the rolling bearing unit may deviate from a desired value. When the internal gap deviates from an appropriate value, the rolling fatigue life of the second inner ring raceway 9 formed on the outer peripheral surface of the second inner ring 3 is reduced.
[0009]
Such inconvenience is a structure in which the structure shown in FIG. 17 and the structure shown in FIG. 18 are combined and the hub 2 is provided with the first flange 6 and the first inner ring raceway 7, and the inner ring 3 is connected to the hub. This also occurs in the case of a structure that is coupled and fixed with the caulking portion 19 to 2. Further, when such a structure is adopted, the hub 2 is made of carbon steel having a carbon content of less than 0.45% by weight, like the hub 18 having the conventional structure shown in FIG. The hardness of one inner ring raceway 7 portion cannot be sufficiently increased, and sufficient durability cannot be ensured.
In view of such circumstances, the present invention was invented to provide a rolling bearing unit for supporting a wheel that is low in cost and has sufficient durability.
[0010]
[Means for Solving the Problems]
The wheel support rolling bearing unit of the present invention includes inner members (2b, 2c, 2c, 2c, 1c) each formed with a first flange (6) on the outer peripheral surface of one end and a first inner ring raceway (7) on the outer peripheral surface of the intermediate portion. 51) and a stepped portion (8) having a smaller outer diameter than the portion where the first inner ring raceway (7) is formed, which is formed at the other end of the inner member (2b, 2c, 51). A second inner ring raceway (9) is formed on the outer peripheral surface and the inner ring (3) is externally fitted to the stepped portion (8), and the inner ring is opposed to the first inner ring raceway (7). An outer ring (4) formed with one outer ring raceway (15) and a second outer ring raceway (16) facing the second inner ring raceway (9), and a second flange (17) on the outer peripheral surface, respectively. There are not a plurality of each between the first and second inner ring raceways (7, 9) and the first and second outer ring raceways (15, 16). And provided with rolling elements (5) provided, and at the other end of the inner member (2b, 2c, 51), at least a portion protruding from the inner ring (3) externally fitted to the stepped portion (8) is diametrically The inner ring (3) fitted to the stepped portion (8) is pressed against the stepped surface (12) of the stepped portion (8) by the crimped portions (19, 19a) formed by caulking outward. The inner ring (3) externally fitted to the step (8) is coupled and fixed to the inner member (2b, 2c, 51).
In particular, in the rolling bearing unit for supporting a wheel of the present invention, the inner member (2b, 2c, 51) includes the stepped portion (12) including at least a step surface (12) which is an abutting surface of the inner ring (3). 8) From the one end portion of the first inner ring raceway (7) portionA side surface portion of the base end portion of the first flange (6)Are hardened continuously by quenching treatment, and at least the other end portion of the inner member (2b, 2c, 51) protrudes from the inner ring (3) without being subjected to the quenching treatment. I'm leaving.
[0011]
Preferably, at least at the corners of the stepped portion, the cross-sectional shape is preferably a quarter of a circle on the continuous portion of the cylindrical outer peripheral surface on which the inner ring is fitted and fixed and the stepped surface that abuts the end surface of the inner ring. An arcuate curved surface portion (corner R portion) is formed. And the curvature radius of the cross section of this curved surface part is regulated to the range of 2.5 ± 1.5 mm.
[0012]
[0013]
[0014]
[Action]
The action of rotatably supporting the wheel with respect to the suspension device by the wheel supporting rolling bearing unit of the present invention configured as described above is the same as that of the conventionally known wheel supporting rolling bearing unit.
In particular, in the case of the rolling bearing unit for supporting a wheel according to the present invention, the cost can be reduced while ensuring sufficient durability.
[0015]
[0016]
or,Inner ringIs made of high carbon steel such as bearing steel and hardened to the core,Caulking partEven when a large load is applied to the inner ring as a result of this processing, deformation of the inner ring can be prevented and the (positive or negative) internal gap of the rolling bearing unit can be prevented from deviating from a desired value. That is,Inner memberA portion protruding from the inner ring at the other end of theProvided on this inner memberWhen the caulking part is formed by caulking the cylindrical part,Inner memberIt is necessary to apply a large load directed outward in the diametrical direction to a portion protruding from the inner ring or the cylindrical portion at the other end. As a result, a large surface pressure acts on the inner peripheral surface and the end surface of the inner ring in association with the forming operation of the caulking portion. Therefore, if the hardness of the inner ring is low, the inner ring is deformed by the surface pressure, and the internal clearance of the rolling bearing unit deviates from a desired value. On the other hand, when the inner ring is made of high carbon steel such as bearing steel and is hardened and hardened to the core, the hardness of the inner ring is sufficiently high. The internal gap can be kept at a desired value by preventing deformation. or,secondIt is possible to prevent the diameter of the inner ring raceway from changing and the shape accuracy (roundness, cross-sectional shape) from deteriorating, thereby preventing the rolling fatigue life of the second inner ring raceway from being lowered.
[0017]
still,Inner memberThe carbon content in the carbon steel constituting the steel is 0.45 to 1.10% by weight.Inner memberIf the hardness of the part protruding from the inner ring at the other end of the cylinder or the cylindrical part formed at the other end is Hv 200 to 300 before caulking,firstTo ensure the hardness of the inner ring raceway part and the aboveInner memberIt is possible to sufficiently perform the caulking and expanding operation of the portion protruding from the inner ring at the other end of the inner ring or the cylindrical portion. still,Inner memberIf the carbon content in the carbon steel constituting the steel is 0.45 to 0.60% by weight, annealing may not be performed after forging. In addition, the cooling rate is simply controlled after forging, and the aboveInner memberThe hardness of the part which protruded from the inner ring | wheel at the other end part or the said cylindrical part can be set to Hv200-300. On the contrary,Inner memberWhen the carbon content in the carbon steel constituting is 0.60 to 1.10% by weight, annealing is performed after forging.
[0018]
[0019]
DETAILED DESCRIPTION OF THE INVENTION
1-4,The present inventionThe 1st example of this embodiment is shown. The wheel support rolling bearing unit 1a of this example isIt corresponds to the inner member recited in claim 1.A hub 2b, an inner ring 3, an outer ring 4, and a plurality of rolling elements 5, 5 are provided. Of these, a first flange 6 for supporting the wheel is formed in a portion near the outer end of the outer peripheral surface of the hub 2b. Further, a first inner ring raceway 7 is formed on the outer peripheral surface of the intermediate part of the first inner ring member 2b, and a step part 8 having a smaller outer diameter is formed on the inner end part. Such a hub 2b is integrally formed by forging a carbon steel material having a carbon content of 0.45 to 1.10% by weight.
[0020]
Further, a part of the outer peripheral surface of such a hub 2b shown by an oblique lattice in FIG. 1, that is, the first inner ring raceway 7 part and the base end of the first flange 6 are shown.Part sideThe portion and the base half of the step portion 8 (from the step surface 12 which is the butting surface of the inner ring 3 to a part of the cylindrical outer peripheral surface which is the fitting portion of the inner ring 3) are induction-hardened, Quenching treatment such as carburizing quenching and laser quenching is performed to increase the hardness of the portion to about Hv550 to 900. Of the above quenching processes, the induction quenching process is most preferable because the process cost is low. On the other hand, since the carburizing quenching process needs to perform a charcoal-proof plating process on the part which is not hardened, processing cost increases. Also, laser quenching increases equipment costs.
[0021]
Of the portions subjected to the quenching treatment indicated by the oblique lattice, the first inner ring raceway 7 portion receives a large surface pressure based on the contact with the rolling surface of the rolling element 5, so that it rolls. Harden to ensure fatigue life. Also, the base end of the first flange 6Part sideThe portion is cured to prevent the base end portion from being deformed regardless of the moment load received from the first flange 6 to which the wheel is fixed. Further, of the base half portion of the step portion 8, a part of the outer peripheral surface portion of the step portion 8 is irrespective of the fitting pressure of the inner ring 3 and the radial load received by the inner ring 3 from the plurality of rolling elements 5. In order to prevent the outer peripheral surface of the step portion 8 from being deformed, and to prevent fretting wear from occurring on the outer peripheral surface of the step portion 8 which is a fitting portion with the inner ring 3. Harden. Further, the stepped surface 12 portion of the stepped portion 8 prevents the stepped surface 12 from being deformed regardless of the axial load applied to the inner ring 3 by the caulking operation described later. The stepped surface 12 that is a contact surface with the outer end surface is cured to prevent fretting wear from occurring. Further, the corner R portion which is a continuous portion between the outer peripheral surface of the step portion 8 and the step surface 12 is cured in order to prevent deformation due to stress concentration. In addition, Preferably, the curvature radius of the cross section of this corner R part is regulated in the range of 2.5 ± 1.5 mm. If the radius of curvature of this portion is less than 1 mm, there is a possibility that damage such as cracks may occur due to stress concentration. On the other hand, if the radius of curvature of the portion exceeds 4 mm, it easily interferes with the inner peripheral edge of the end of the inner ring 3, and the wheel bearing rolling bearing unit becomes difficult.
[0022]
Note that the axial position (point a in FIG. 1) of the inner end of the hardened hardened layer indicated by the oblique lattice is the axial position of the center of the plurality of rolling elements 5 arranged around the inner ring 3 (see FIG. 1). The position in the axial direction of the base end of the caulking portion 19 described later (the portion where the outer diameter of the caulking portion begins to become larger than the outer diameter of the step portion 8) (in FIG. 1). It is assumed that the outer side (the left side in FIG. 1) from the point (1). The reason for restricting the inner end position of the hardened hardening layer in this way is that the surface area of the hardened hardened layer present on the outer peripheral surface portion of the stepped portion 8 is made as wide as possible and the processing of the caulking portion 19 is facilitated. In addition, this is to prevent damage such as cracks from occurring in the caulking portion 19 based on the presence of the hardened and hardened layer. In addition, although the above-mentioned quench hardening layer may be discontinuously formed for every required part, like this example shown in FIG. 1, adjacent quench hardening layers are continuously connected. If formed, the strength and durability of the hub 2b can be improved.
[0023]
A cylindrical portion 20 for forming a caulking portion 19 for fixing the inner ring 3 is formed at the inner end portion of the hub 2b. In the example shown in the drawing, the thickness of the cylindrical portion 20 becomes smaller toward the leading edge in a state before the cylindrical portion 20 is caulked outward in the diameter direction shown in FIG. For this reason, in the case of the illustrated example, a tapered hole 21 is formed on the inner end surface of the hub 2b. The inner ring 3 is made of a high carbon steel such as a high carbon chromium bearing steel such as SUJ2, and is hardened and hardened to the core.
[0024]
The carbon content in the carbon steel constituting the hub 2b is 0.45 to 1.10% by weight as described above, and the hardness of the cylindrical portion 20 formed at least on the other end of the hub 2b is as follows. Before the caulking process shown in FIG. By satisfying such a condition, the required hardness (Hv 550 to 900) is ensured for the first inner ring raceway 7 portion, and the work of caulking and expanding the cylindrical portion 20 can be sufficiently performed. That is, when the cylindrical portion 20 is caulked and spread into the caulking portion 19, if the hardness of the cylindrical portion 20 exceeds Hv300, the formed caulking portion 19 may be cracked or insufficiently caulked. As a result, the caulking portion 19 and the inner ring 3 are not in close contact with each other, and the fastening force of the inner ring 3 to the hub 2b is reduced. In addition, the load required to form the caulking portion 19 becomes excessive, and it becomes easy to cause damage such as indentation on each raceway surface and the rolling elements 5 and 5 along with caulking work, and the dimensional accuracy of each portion deteriorates. Cause the possibility of Further, machining of the hub 2b becomes difficult. That is, the machining time becomes longer and the tool life is reduced, resulting in an increase in cost.
[0025]
If the carbon content in the carbon steel constituting the hub 2b exceeds 1.10% by weight, it becomes difficult to suppress the hardness of the cylindrical portion 20 to Hv300 or less. Therefore, in the carbon steel constituting the hub 2b, The upper limit of the carbon content was 1.10% by weight. On the other hand, if the hardness of the cylindrical portion 20 does not reach Hv200, the hardness of the caulking portion 19 formed by caulking the cylindrical portion 20 cannot be secured, and the fastening force of the inner ring 3 by the caulking portion 19 is also increased. Run short. If the carbon content in the carbon steel constituting the hub 2b does not reach 0.45% by weight, the hardness (Hv 550 to 900) required for the first inner ring raceway portion 7 cannot be secured, and this first Since the life of one inner ring raceway portion 7 is reduced, the lower limit of the carbon content in the carbon steel constituting the hub 2b is set to 0.45% by weight.
[0026]
The hub 2b is manufactured by forging a carbon steel having a carbon content of 0.45 to 1.10% by weight for the reasons described above. In the case of 0.60% by weight, it is not necessary to perform an annealing process after forging. That is, by simply controlling the cooling rate after forging, it is possible to keep at least the hardness of the cylindrical portion 20 in the range of Hv 200 to 300. Therefore, after the hub 2b is formed by forging, the work of processing the cylindrical portion 20 into the caulking portion 19 can be performed without performing an annealing process. The wheel-supporting rolling bearing having the caulking portion 19 is provided. Units can be built at low cost.
[0027]
On the other hand, when the carbon content in the carbon steel constituting the hub 2b is 0.60 to 1.10% by weight, the hub 2b needs to be annealed after being made by forging. is there. That is, even when the carbon content in the carbon steel is 0.60 to 1.10% by weight, the hardness of the cylindrical portion 20 is set to about Hv 200 to 300 by controlling the cooling rate after forging. Is possible. However, since the cooling rate needs to be considerably small (slow), it takes a long time and special equipment is also required. For this reason, it is preferable to perform annealing rather than controlling the cooling rate in terms of securing production efficiency and simplifying production equipment. Moreover, the one-time annealing improves the hardenability when quenching the necessary portion of the hub 2b. Therefore, after the hub 2b is made by forging, annealing is performed so that at least the hardness of the cylindrical portion 20 is about Hv 200 to 300. In the case where the carbon content in the carbon steel constituting the hub 2b is 0.60 to 1.10% by weight, the cooling rate after forging is not slowed down and the annealing treatment is not performed. The same problem as described above occurs when the content in the carbon steel exceeds 1.10% by weight. By the way, when the content in the carbon steel exceeds 1.10% by weight, the hardness of the cylindrical portion 20 is reduced to Hv300 or less even when the cooling rate after forging is slowed or annealing is performed. It becomes difficult to suppress.
[0028]
In order to squeeze the tip of the cylindrical portion 20 as described above in order to fix the inner ring 3 to the inner end of the hub 2b, the hub 2b is fixed so that it does not move in the axial direction. As shown in FIG. 2, the pressing die 22 is strongly pressed against the tip of the cylindrical portion 20. A frustoconical convex portion 23 that can be pushed into the inside of the cylindrical portion 20 is formed at the center of the front end surface (left end surface in FIG. 2) of the pressing die 22, and a circular arc section is formed around the convex portion 23. The concave portion 24 is formed so as to surround the entire circumference of the convex portion 23. The cross-sectional shape of the recess 24 and the outer diameter R_{twenty four}And depth D_{twenty four}When the cylindrical portion 20 is plastically deformed to form the caulking portion 19, a predetermined shape and size are applied while applying a compressive force to the metal (carbon steel) constituting the cylindrical portion 20. It restrict | limits so that the said crimping part 19 to have may be formed. That is, the cross-sectional shape of the concave portion 24 is such that the cross-sectional shape of the caulking portion 19 obtained by plastically deforming the distal end portion of the cylindrical portion 20 by the concave portion 24 has a thickness dimension as it goes from the proximal end portion toward the distal end portion. The composite curved surface has a curvature radius that becomes smaller toward the outer diameter side, so that the thickness dimension is abruptly reduced especially at the tip portion so as to gradually become smaller. Outer diameter R_{twenty four}Is the outer diameter R of the caulking portion 19 to be formed₁₉Or the outer diameter R of the caulking portion 19₁₉Slightly less than (R_{twenty four}≦ R₁₉)I have to. Furthermore, depth D_{twenty four}In the state where the caulking portion 19 is formed by sandwiching the tip end portion of the cylindrical portion 20 between the inner peripheral surface and the inner end surface of the inner end portion of the inner ring 3, the tip end surface of the pressing die 22 and the inner ring 3 are formed. The gap 25 is restricted so as to remain between the inner end face and the inner end face.
[0029]
If the pressing die 22 having the convex portion 23 and the concave portion 24 having the shape and dimensions as described above is pressed against the tip portion of the cylindrical portion 20, the tip portion of the cylindrical portion 20 is caulked outward in the diametrical direction, The caulking portion 19 can be formed. The inner ring 3 can be clamped between the caulking portion 19 and the stepped surface 12 of the stepped portion 8 formed at the inner end of the hub 2b, and the inner ring 3 can be fixed to the hub 2b. In the case of the illustrated example, in the final stage of forming the caulking portion 19 by plastically deforming the inner end surface of the cylindrical portion 20, the inner surface of the concave portion 24 extends from the inner diameter surface of the caulking portion 19 to the outer diameter surface. Inward compression force acts. Therefore, it is possible to effectively prevent the occurrence of damage such as cracks on the outer peripheral edge of the caulking portion 19. Further, a curved surface portion 26 having an arcuate cross section is formed in the inner end opening peripheral edge portion of the inner ring 3 where the outer diameter surface of the base end portion of the caulking portion 19 abuts. Therefore, the radius of curvature of the base end portion of the caulking portion 19 is not reduced, and it is difficult to apply an excessive stress to the base end portion.
[0030]
As described above, in the case of the rolling bearing unit for supporting a wheel of the present invention, the hub 2b is made of carbon steel having a carbon content of 0.45 to 1.10% by weight, and the first inner ring raceway 7 is formed. Since the portion is hardened by the quenching process, the rolling fatigue life of the surface of the first inner ring raceway 7 can be sufficiently ensured regardless of the load repeatedly applied from the rolling elements 5 and 5. On the other hand, the cylindrical portion 20 is left raw without being quenched. For this reason, the force required to plastically deform the cylindrical portion 20 increases suddenly, or when the cylindrical portion 20 is plastically deformed, damage such as cracks is likely to occur in the cylindrical portion 20. Absent. Therefore, even when the hardness of the first inner ring raceway 7 portion is increased to secure the rolling fatigue life of the first inner ring raceway portion 7 as described above, the caulking for joining the hub 2b and the inner ring 3 is performed. The processing of the part 19 is not troublesome. Moreover, since the inner ring 3 is made of high carbon steel such as bearing steel and is hardened and hardened to the core, even if a large load is applied to the inner ring 3 due to the processing of the caulking portion 19, the inner ring 3 3 can be prevented and the internal clearance of the rolling bearing unit can be prevented from deviating from a desired value. Further, the diameter of the second inner ring raceway 9 formed on the outer peripheral surface of the inner ring 3 can be prevented from changing or the accuracy can be prevented, so that the rolling fatigue life of the second inner ring raceway 9 can be prevented from being lowered. .
[0031]
Furthermore, in the case of the illustrated example, since the thickness of the cylindrical portion 20 for forming the caulking portion 19 is made smaller toward the tip edge, the hub 2b has a carbon content of 0.45 to 1. Even when made of 10% by weight carbon steel, the force required to form the caulking portion 19 by plastically deforming the tip portion of the cylindrical portion 20 with the pressing die 22 as described above is increased. There is no. For this reason, damage such as cracks occurs in the caulking portion 19 due to the caulking work, or the diameter of the inner ring 3 affects the durability such as preload and rolling fatigue life of the inner ring 3 fixed by the caulking portion 19. It is possible to more reliably prevent the action of a force that changes so much that it exerts. In particular, in the illustrated example, compressive stress is applied to the distal end portion of the caulking portion 19 and the radius of curvature of the proximal end portion of the caulking portion 19 is increased, so that the caulking portion 19 can be more effectively prevented from being damaged. I can plan. The outer end opening of the space 27 provided with the rolling elements 5 and 5 is closed by the seal ring 28 and the inner end opening is closed by the lid 29, so that dust enters the space 27, or Lubricating oil is prevented from leaking from the space.
[0032]
Next, the appropriate values of the dimensions of each part in the case of realizing the structure as shown in FIGS. Note that this value is the inner diameter r of the inner ring 3 to be fixed to the hub 2b in the case of a wheel bearing rolling bearing unit incorporated in a general passenger car._Three Is about 20-60mm, and length dimension L_Three Is about 15 to 40 mm, the material of the hub 2b is carbon steel with a carbon content of 0.45 to 1.10% by weight, and the material of the inner ring 3 is high carbon chromium bearing steel such as SUJ2. It is about the case.
First, the thickness dimension t of the tip of the cylindrical portion 20 before the caulking portion 19 is processed.₂₀Is preferably in the range of 1.5 to 5 mm. Also, the thickness T of the base end portion of the cylindrical portion 20₂₀Is preferably in the range of 5 to 10 mm. Thickness dimension t of the tip and base ends₂₀And T₂₀If this is regulated within this range, it is possible to prevent the caulking portion 19 from being damaged, such as a crack, and to secure the support rigidity of the inner ring 3 by the caulking portion 19.
That is, it is possible to effectively prevent the occurrence of the damage by thinning the tip portion of the cylindrical portion 20 where the amount of deformation increases and making the tip portion easily plastically deformable. Also, the base end portion of the cylindrical portion 20 that is used to hold the inner ring 3 toward the stepped surface 12 can be made thick so that the support strength of the inner ring 3 can be sufficiently secured.
[0033]
Also, the length L of the cylindrical portion 20₂₀Is preferably about 8 to 20 mm. This length L₂₀Is too small (L₂₀<8 mm), the above-mentioned caulking portion 19 cannot be formed sufficiently, or damage such as a crack is likely to occur in a part of the caulking portion 19 at the time of formation. In contrast, the length dimension L₂₀Is too large (L₂₀> 20 mm), the length of the hollow portion existing at the inner end of the hub 2b becomes too long, and the strength of the hub 2b is reduced. Based on the radial load applied to the inner ring 3, the inner diameter of the hub 2b is reduced. The end portion is easily deformed. The operation of plastically deforming the cylindrical portion 20 restricted to the above dimensions to form the caulking portion 19 is preferably performed by forging or swing pressing.
[0034]
Further, the line of action of the load applied to the inner ring 3 from the plurality of rolling elements 5 (corresponding to the chain line α in FIG. 2 representing the contact angle of the rolling elements 5) is the inner peripheral surface of the inner ring 3 and the step portion 8. So that it does not pass through the crimping part 19. The reason for regulating in this way is to prevent the caulking portion 19 from being deformed or damaged by preventing the load from acting as a force that directly deforms the caulking portion 19 inward in the diameter direction.
[0035]
Next, the cross-sectional area S of the inner ring 3 that is closer to the outer side than the second inner ring raceway 9 (the AA line portion in FIG. 3)._Three And the cross-sectional area S of the hub 2b at that portion._2bS in relation to_Three <S_2bAnd more preferably S_Three ≦ 0.94S_2bAnd The reason for restricting the cross-sectional areas of these parts in this way is to ensure the support strength of the inner ring 3 with respect to the hub 2b.
That is, the force (axial force) for pressing the inner ring 3 in the axial direction and preventing the rotation of the inner ring 3 in the state where the inner ring 3 is sandwiched between the caulking portion 19 and the stepped surface 12 is as described above. It is determined by the difference in strain amount in the axial direction of the hub 2b and the inner ring 3. That is, during the caulking process, the elastic deformation amount of the inner ring 3 is larger than the elastic deformation amount of the hub 2b. After the caulking process, the inner ring 3 and the hub 2b are elastically restored, and an axial force (axial force) is applied to the inner ring 3. Since the material constituting the inner ring 3 and the material constituting the hub 2b have substantially the same elastic modulus, as described above, S_Three <S_2bIf so, the amount of elastic deformation during caulking is larger in the inner ring 3 than in the hub 2b. Therefore, if the cross-sectional area of each part is regulated in this way, it is possible to effectively prevent the occurrence of so-called creep, in which the inner ring 3 continues to be applied to the inner ring 3 and the inner ring 3 rotates with respect to the hub 2b.
[0036]
Next, when the plurality of rolling elements 5 arranged around the inner ring 3 are balls, the distance L from the center O of the rolling element 5 to the inner end face of the inner ring 3 is as follows._O3Is the diameter D of the rolling element 5_Five 0.75 times or more (L_O3≧ 0.75D_Five ) Is preferable. This distance L_O3This is because the diameter of the second inner ring raceway 9 where the rolling contact surface of the rolling element 5 comes into contact with the caulking portion 19 is increased or the accuracy ( This is to prevent deterioration in roundness and cross-sectional shape. That is, this distance L_O3Is too small, the base end portion of the caulking portion 19 is present on the inner diameter side portion of the second inner ring raceway 9, and the second inner ring raceway 9 is formed along with the forming operation of the caulking portion 19. There is a possibility that the diameter of the portion becomes so large that it cannot be ignored or the accuracy is deteriorated.
[0037]
Next, the outer diameter R of the caulking portion 19 described above.₁₉Is the inner diameter r of the inner ring 3_Three And the outer diameter R of the outer ring portion of the inner ring 3 that is out of the second inner ring raceway 9_Three Therefore, it is preferable to regulate to the following range.
r_Three +0.7 (R_Three -R_Three ) ≦ R₁₉≦ r_Three +1.3 (R_Three -R_Three )
Outer diameter R of the caulking portion 19₁₉By limiting the range to this range, it is possible to prevent the caulking portion 19 from being damaged such as cracking and to secure the support strength of the inner ring 3 with respect to the hub 2b.
Outer diameter R₁₉Is shifted in a direction larger than the above range, the damage is likely to occur. Conversely, the outer diameter R₁₉Is shifted in a direction smaller than the above range, it is difficult to ensure the support strength.
[0038]
Further, the cross-sectional shape of the curved surface portion 26 is preferably regulated as follows. First, an inclined surface portion is provided near the starting point of the curved surface portion 26, and the angle θ at which the inclined surface portion is inclined with respect to the central axis of the inner ring 3.₂₆Is 10 to 45 degrees. Further, the radius of curvature r of the portion where the inner peripheral surface of the inner ring 3 and the inclined surface portion are continuous is provided.₂₆Is 2 to 8 mm. Further, the radius of curvature R of the portion where the inclined surface portion and the end surface of the inner ring 3 are continuous is provided.₂₆Is 3 to 10 mm.
By restricting the cross-sectional shape of the curved surface portion 26 in this way, excessive stress is generated at the proximal end portion of the caulking portion 19 when the cylindrical portion 20 is plastically deformed to form the caulking portion 19. This prevents the damage to the base end portion.
[0039]
Moreover, it is preferable to perform the operation | work which plastically deforms the said cylindrical part 20 (caulking and expanding) and forms the said crimping part 19 using the rocking press apparatus 43 as shown in FIGS. The swing press device 43 includes a pressing die 22, a holding jig 44, and a holder 45. Of these, the holder 45 is formed in a bottomed cylindrical shape with a metal material having a sufficiently large rigidity, and the upper surface of the bottom portion 46 has a shape that allows the outer end portion of the hub 2b to be abutted without being rattled. . The holding jig 44 is formed as a whole by combining jig elements 47 and 47 each having a semicircular arc shape, and includes a cylindrical holding section 48 at the inner peripheral edge. . The outer peripheral edges of the jig elements 47 and 47 and the inner peripheral surface of the upper end opening of the holder 45 are tapered surfaces that are inclined in a direction in which the diameter increases toward the upper side. In the process of coupling and fixing the jig elements 47, 47 to the mounting portion 51 provided on the upper inner peripheral surface of the holder 45 with bolts (not shown) inserted through the through holes 49, 49, 47 is displaced inward in the diameter direction based on the engagement between the tapered surfaces. Then, the inner peripheral surface of the holding portion 48 of the holding jig 44 constituted by these jig elements 47 and 47 is strongly pressed against the outer peripheral surface of the inner ring 3. Due to such a configuration, the holding jig 44 can hold down the inner ring 3 sufficiently strongly even if the outer diameter of the inner ring 3 is deviated within the range of dimensional tolerance (50 μm).
[0040]
When the caulking portion 19 is formed by caulking the cylindrical portion 20, the pressing die 22 is swung and rotated while pressing the hub 2 b upward via the holder 45. That is, in a state where the central axis of the pressing die 22 and the central axis of the hub 2b are inclined by an angle θ, the pressing die 22 is rotated around the central axis of the hub 2b. When the caulking portion 19 is formed by such a rocking press, a part in the circumferential direction of the pressing die 22 presses the cylindrical portion 20, and the machining operation on the caulking portion 19 is a partial process. And continuously in the circumferential direction. For this reason, compared with the case where the said crimping part 19 is formed by general forging, the load added to the said cylindrical part 20 at the time of a process can be made small. The holding jig 44 prevents the hub 2b from swinging when the caulking portion 19 is processed by the pressing die 22, and the size and shape accuracy of each portion of the constituent elements such as the raceway surfaces and the rolling elements 5, 5 are deteriorated. To prevent it.
[0041]
The inclination angle (swinging angle) θ, the swinging rotational speed, the pressing load and the like of the pressing die 22 are determined in design according to the size and the like of the wheel support rolling bearing unit in which the caulking portion 19 is to be processed. However, for example, in the case of a general rolling bearing unit for supporting a wheel for a passenger car having the cylindrical portion 20 having the shape and size as described above, the following range is set. First, the inclination angle θ is preferably about 0.5 to 5.0 degrees. When the inclination angle θ is less than 0.5 degrees, the load required to plastically deform the cylindrical portion 20 to form the caulking portion 19 increases, and the dimensional accuracy and shape accuracy of each raceway surface and rolling element are increased. Deteriorates or indentation or the like is likely to occur. On the other hand, when the inclination angle θ exceeds 5 degrees, the hub 2b is shaken in the diameter direction when the cylindrical portion 20 is plastically deformed to form the caulking portion 19, and the hub 2b is swung by the restraining jig 44. 2b cannot be held sufficiently, and the dimensional accuracy and shape accuracy of each raceway surface and rolling element are deteriorated, and indentations and the like are liable to occur.
[0042]
In addition, the swinging rotation speed is 100 to 500 r.p.m. (min^-1 ) Degree is preferred. When this rocking rotation speed is less than 100 r.p.m., the machining time becomes long. On the contrary, if it exceeds 500 r.p.m., the caulking portion 19 obtained is hardened due to work hardening, and damage such as cracking is likely to occur.
Further, the pressing load is preferably about 15 to 50 t. When the pressing load is less than 15 t, the cylindrical portion 20 cannot be sufficiently plastically deformed, and a good caulking portion 19 cannot be obtained, so that the coupling strength of the inner ring 3 to the hub 2b is insufficient. . On the other hand, when the pressing load exceeds 50 t, the dimensional accuracy and shape accuracy of each raceway surface and rolling element are deteriorated, and indentations and the like are liable to occur.
In addition, the effect | action and effect by forming the crimping part 19 with the above oscillating press apparatuses 43 are acquired irrespective of the kind of metal material which comprises the said hub 2b and the inner ring | wheel 3. FIG.
[0043]
Next, FIG.The present invention2 shows a second example of the embodiment. In this example, the present invention is applied to a wheel bearing rolling bearing unit with a rotation speed detection device for detecting the rotation speed of a wheel. For this reason, in the case of this example, a step portion 31 having a smaller diameter than the shoulder portion 30 of the inner ring 3 and projecting inward from the shoulder portion 30 is formed at the inner end portion of the inner ring 3. And the base end part (left end part of FIG. 7) of the tone wheel 32 which comprises a rotational speed detection apparatus is externally fixed to this shoulder part 30. As shown in FIG. A part of the tone wheel 32 abuts on the periphery of the base end portion (left end portion in FIG. 7) of the step portion 31 on the inner end face of the shoulder portion 30, and extends in the axial direction (left and right direction in FIG. 7). Positioning is planned. A synthetic resin or metal cover 33 is fitted and fixed to the inner end opening of the outer ring 4, and the sensor 34 embedded in the cover 33 is opposed to the tone wheel 32 to detect the rotational speed. Configure the device.
[0044]
In this example, the step portion 31 is formed at the inner end portion of the inner ring 3 as described above, and the step portion 31 is suppressed by the caulking portion 19 formed at the inner end portion of the hub 2b. The axial distance between the caulking portion 19 and the second inner ring raceway 9 formed on the outer peripheral surface of the inner ring 3 is increased by the amount of such stepped portion 31 formed. As a result, the dimensional change of the second inner ring raceway 9 due to the formation of the caulking portion 19 can be further suppressed. Furthermore, not only the second inner ring raceway 9 but also the shoulder 30 can be prevented from increasing in outer diameter. Therefore, when a seal ring or tone wheel is externally fitted to the shoulder portion 30 or a seal lip is slidably brought into contact with the outer peripheral surface of the shoulder portion 30, the function of the seal ring or tone wheel is prevented from being impaired. it can. In the case of this example as well, when the plurality of rolling elements 5 arranged around the inner ring 3 are balls, the distance L from the center O of the rolling element 5 to the inner end face of the second inner ring member 3._O3Is the diameter D of the rolling element 5_Five 0.75 times or more (L_O3≧ 0.75D_Five ) Is preferable. Since the configuration and operation of the other parts are the same as in the case of the first example described above, the same parts are denoted by the same reference numerals, and redundant description is omitted. In the case of this example (and will be described below)Examples 3 to 5 and Reference Examples 1 to 6In the case of ()), the hardened and hardened portion of the hub is represented by a diagonal lattice.
[0045]
Next, FIG.The present invention3 shows a third example of the embodiment. In the first example and the second example described above, the hub 2b is rotatably provided inside the non-rotating outer ring 4, whereas in this example, the outer ring 4 side rotates. LikeA shaft member 51 corresponding to the inner member described in claim 1 and the inner ring 3 are arranged on the inner diameter side of the outer ring 4.ing. That is, in the case of this example, the outer ring 4 rotates together with the wheels. Since the rotation side and the stationary side are inward and outward in the diametrical direction, and the configuration and action other than that in which the inner and outer sides in the axial direction are partially reversed are the same as in the case of the first example described above. Equivalent parts are denoted by the same reference numerals, and redundant description is omitted.
[0046]
Next, FIG.The present invention4 shows a fourth example of the embodiment. In both the first and second examples described above and the third example described above, wheel support rolling for rotatably supporting driven wheels (front wheels of FR and RR vehicles, rear wheels of FF vehicles) that are not rotationally driven. Whereas the present invention is applied to the bearing unit, in this example, the drive wheels (the rear wheels of the FR and RR vehicles, the front wheels of the FF vehicle, and all the wheels of the 4WD vehicle) are supported rotatably. The present invention is applied to a rolling bearing unit for supporting a wheel.
[0047]
For this reason, in this example,Corresponds to the inner member,The hub 2c is formed in a cylindrical shape, and a female spline portion 35 is formed on the inner peripheral surface of the hub 2c. A drive shaft 37 attached to the constant velocity joint 36 and having a male spline portion formed on the outer peripheral surface is inserted into the female spline portion 35. On the other hand, the inner ring 3 is fitted on the step 8 formed on the outer peripheral surface of the inner end of the hub 2c, and a step 38 is formed near the inner end surface of the inner ring 3. The caulking portion 19 formed at the inner end portion of the hub 2c is caulked toward the step portion 38. In this state, the caulking portion 19 does not protrude inward from the inner end surface of the inner ring 3. Accordingly, the outer end surface of the main body portion 39 of the constant velocity joint 36 is in contact with the inner end surface of the inner ring 3. In this manner, with the outer end surface of the main body portion 39 in contact with the inner end surface of the inner ring 3, the nut 40 is screwed into a portion protruding from the outer end surface of the hub 2c at the distal end portion of the drive shaft 37. By further tightening, the inner ring 3 and the hub 2c are firmly held in the axial direction.
[0048]
In the structure of this example, when the plurality of rolling elements 5 arranged around the inner ring 3 are balls, it is preferable that the distance L from the center O of the rolling element 5 to the step surface of the step portion 38 is preferable.₃₈, The diameter D of the rolling element 5_Five 0.75 times or more (see Fig. 3)₃₈≧ 0.75D_Five ). Since the configuration and operation of the other parts are the same as in the case of the first example described above, the same parts are denoted by the same reference numerals, and redundant description is omitted.
[0049]
In the case of this example, since a hollow cylindrical member is used as the hub 2c, it may be difficult to make the cross-sectional area of the hub 2c larger than the cross-sectional area of the inner ring 3. However, in the structure of this example, since the inner ring 3 is strongly pressed against the stepped surface 12 of the hub 2c by the axial force based on the tightening of the nut 38 in the used state, the caulking portion is pressed from the inner ring 3 to the caulking portion 19. The force acting in the direction of loosening 19 is limited. Therefore, even if the relationship of the cross-sectional areas cannot be satisfied, the durability of the caulking portion 19 is not impaired.
[0050]
Next, FIG.The present inventionThe 5th example of embodiment of this is shown. In the case of this example, the caulking portion 19a formed at the inner end portion of the hub 2c is caulked toward the inner end surface of the inner ring 3, and the caulking portion 19a is axially inward from the inner end surface of the inner ring 3. Protruding. Further, an annular flat surface 42 is formed on the inner surface side of the caulking portion 19a, and the flat surface 42 is brought into contact with the outer end surface of the main body portion 39 of the constant velocity joint 36. The caulking portion 19a is raw carbon steel, but the flat surface 42 makes contact with the outer end surface of the main body portion 39 in a wide area. Therefore, the surface pressure applied to the contact portion even when the nut 40 is tightened. Is never extremely high. Therefore, it is possible to prevent the caulking portion 19a from sagging regardless of the use over a long period of time, and the caulking portion 19a may cause the nut 40 to loosen and the rolling elements 5 and 5 to rattle. Can be effectively prevented. Since the configuration and operation of the other parts are the same as in the case of the above-described fourth example, the same parts are denoted by the same reference numerals, and redundant description is omitted.
[0051]
Next, FIGS. 11 to 13 show the present invention.Reference examples of the present invention that are not includedThe first1-3An exampleYes.Mentioned aboveEmbodiment of the present inventionIn the case of the first to fifth examples, the quench hardening layer applied to the member forming the caulking portion 19 was continuously formed, whereasFirst to third examplesIn the case of an example, the said hardening hardening layer is formed discontinuously for every part especially required. That is, as shown in FIG.First reference exampleIn the case of the example, only the first inner ring raceway portion 7 and the step surface 12 and the corner R portion existing on the inner peripheral portion of the step surface 12 are shown in FIG.Second reference exampleIn the case of the example, only the first inner ring raceway 7 portion, the step surface 12, the corner R portion, and the base half outer peripheral surface of the step portion 8 are shown in FIG.Third reference exampleIn the case of the example, only the first inner ring raceway portion 7 and the base end portion of the first flange 6 and the stepped surface 12 and the outer peripheral surface of the base half portion of the corner R portion and the stepped portion 8 are respectively quenched and hardened. Forming a layer. However, as described above, the quenched and hardened layer is shown in FIGS. 1, 7, 8, 9, and 10, rather than being discontinuously formed at each necessary portion as described above.Embodiment of the present inventionAs in the first to fifth examples, it is possible to improve the strength and durability of the member to which the quenching and hardening layer is applied by continuously forming the adjacent hardening and hardening layers. The configuration and operation of the other parts are described above.Embodiment of the present inventionThis is the same as in the first example.
[0052]
Next, FIG.A fourth reference example of the present invention, which also departs from the present invention.An example is shown. BookreferenceThe wheel support rolling bearing unit of the example is formed with the first and second inner ring raceways 7 and 9 on the outer peripheral surfaces of the first and second inner rings 41 and 3 that are externally fitted to the step portion 8a of the hub 2d. doing. Each of the first and second inner rings 41 and 3 is made of a high carbon steel such as a high carbon chrome bearing steel such as SUJ2, and is hardened and hardened to the core. Further, the first and second inner rings 41 and 3 are formed at the base portion of the first flange 6 and the caulking portion 19 formed at the inner end portion of the hub 2d in a state of being fitted on the step portion 8a. It is sandwiched between the step surface 12.
[0053]
BookreferenceIn the example, the hub 2d can be made of carbon steel having a carbon content of less than 0.45% by weight. 14, the base end portion of the first flange 6, the base end portion of the step portion 8a including the step surface 12, and the outer peripheral surface of the step portion 8a. A portion other than the end portion is hardened to increase the hardness of the portion. However, at least the cylindrical portion 20 of the hub 2d, which is the portion that forms the caulking portion 19, is left without being subjected to the quenching process. The reason why the above-mentioned portions of the hub 2d are quenched and the reason for restricting the axial position (point a in FIG. 14) of the inner end of the quenched and hardened layer indicated by the oblique lattice is described above.Embodiment of the present inventionThis is the same as in the first example.
[0054]
Book configured as abovereferenceIn the case of the wheel support rolling bearing unit of the example, since the inner ring raceway is not provided in the hub 2d itself, it is easy to form the caulking portion 19 as the material of the hub 2d, and the carbon content is less than 0.45% by weight. Carbon steel can be used. However, the hub 2d has a hardened hardened layer formed in the portion shown by the oblique grid in FIG. Therefore, the strength and durability of the hub 2d can be ensured by preventing fretting wear from occurring in the portion where the hardened layer is formed or deformation of the portion where the hardened layer is formed. it can. On the other hand, since at least the cylindrical portion 20 provided in the hub 2d is not subjected to the quenching process and remains raw, the caulking portion for joining the hub 2d and the first and second inner rings 41, 3 is used. The processing of 19 is not troublesome and the caulking portion 19 is not damaged.
[0055]
Further, the second inner ring 3 fitted on the stepped portion 8a is made of high carbon steel such as bearing steel, and is hardened and hardened to the core. For this reason,Embodiment of the present inventionAs in the case of the inner ring 3 of the first example, even when a large load is applied to the second inner ring 3 due to the processing of the caulking portion 19 formed on the hub 2d, the deformation of the second inner ring 3 is prevented. Thus, the internal clearance of the rolling bearing unit can be prevented from deviating from a desired value. Further, the diameter of the second inner ring raceway 9 formed on the outer peripheral surface of the second inner ring 3 is prevented from changing or the accuracy is deteriorated, and the rolling fatigue life of the second inner ring raceway 9 is reduced. It can be prevented. BookreferenceIn the example, the hub 2d may be made of carbon steel having a carbon content of 0.45 to 1.10% by weight. In this case, the strength and durability of the hub 2d are further improved. The configuration and operation of the other parts are described above.Embodiment of the present inventionThis is the same as in the first example.
[0056]
BookreferenceExamples (and laterReference examples 5-6In the case of Example), the carbon content in the carbon steel constituting the hub 2d is restricted to a range of 0.20 to 1.10% by weight, and at least the hardness of the cylindrical portion 20 is Hv200 to 300. The hub 2d is manufactured by forging a carbon steel that satisfies such conditions. Further, when the carbon content in the carbon steel constituting the hub 2d is in the range of 0.20 to 0.60% by weight, after forging and before caulking the cylindrical portion 20, At least the cylindrical portion 20 is not annealed. On the other hand, when the carbon content in the carbon steel constituting the hub 2d is in the range of 0.60 to 1.10% by weight, after forging and before caulking and expanding the cylindrical portion 20 At least the cylindrical portion 20 is annealed. Regarding the hardness of the hub 2d and the necessity of annealing after the forging process,Embodiment of the present inventionThis is the same as in the first example.
[0057]
Next, FIGS.Reference examples 5 to 6 of the present invention that also depart from the present inventionAn exampleYes.These second5-6In the case of the example, the hardened hardened layer applied to the hub 2d is formed only in a portion that receives a particularly large load when the rolling bearing is used. That is, as shown in FIG.The fifth reference exampleIn the case of the example, only the base end portion of the step portion 8a including the step surface 12 is shown in FIG.Sixth reference exampleIn the case of the example, the hardened hardened layer is formed only on the base end portion of the stepped portion 8 a including the stepped surface 12 and the base end portion of the first flange 6, respectively. The configuration and operation of other parts are as described above.Fourth reference exampleThe same as in the example.
[0058]
Although not shown in the drawings, in each of the embodiments described above, each caulking portion 19 and the inner ring (second inner ring) 3 do not necessarily have to be in close contact with each other over the entire surface of the facing portion. Even if a gap exists in a part of the facing portion, the operation and effect of the present invention can be obtained in the same manner. Before the caulking portion 19 is formed, the cylindrical portion 20 has a hardness of about Hv 200 to 300. However, in the state where the cylindrical portion 20 is caulked and expanded to form the caulking portion 19, this caulking portion is formed by work hardening. The hardness of 19 becomes larger than Hv200-300.
[0059]
【The invention's effect】
Since the wheel-supporting rolling bearing unit of the present invention is configured and operates as described above, it is possible to realize a wheel-supporting rolling bearing unit having low cost and sufficient durability.
Further, as shown in the example in the figure, the shape of the cylindrical portion for forming the caulking portion is reduced toward the tip edge in a state before the cylindrical portion is caulked outward in the diametrical direction. It is possible to prevent the occurrence of damage such as cracks in the steel sheet, and to prevent the caulking portion from changing so that the diameter of the inner ring fixed to the hub becomes a problem in practice. Further, it is possible to reduce the possibility that the inner ring is damaged based on the fixing operation and to maintain the preload at an appropriate value, and to reduce the cost by reducing the number of parts, parts processing, and assembly man-hours.
[Brief description of the drawings]
FIG. 1 is a half sectional view showing a first example of an embodiment of the present invention.
FIG. 2 is a partially enlarged cross-sectional view showing a state in which the inner end of the hub is caulked to fix the inner ring during the manufacture of the structure of the first example.
FIG. 3 is a partially enlarged cross-sectional view showing a state before the inner end of the hub is caulked and spread.
4 is a cross-sectional view taken along line AA in FIG.
FIG. 5 is a longitudinal sectional view of a main part of a rocking press device.
FIG. 6 is a plan view of a holding jig incorporated in a rocking press device.
FIG. 7 is a half sectional view showing a second example of an embodiment of the present invention.
FIG. 8 is a half sectional view showing the third example.
FIG. 9 is a half sectional view showing the fourth example.
FIG. 10 is a half sectional view showing the fifth example.
FIG. 11First reference example of the present inventionThe half part sectional view showing an example.
FIG. 122The half part sectional view showing an example.
FIG. 133The half part sectional view showing an example.
FIG. 144The half part sectional view showing an example.
FIG. 155The half part sectional view showing an example.
FIG. 166The half part sectional view showing an example.
FIG. 17 is a half sectional view showing a first example of a conventional structure.
FIG. 18 is a sectional view showing the second example.
[Explanation of symbols]
1, 1a Wheel support hub unit
2, 2a, 2b, 2c, 2d hub
3 Inner ring (second inner ring)
4 outer ring
5 Rolling elements
6 First flange
7 First inner ring raceway
8, 8a Step
9 Second inner ring raceway
10 Male thread
11 Nut
12, 12a Step surface
13 Second inner ring member
14 Locking recess
15 First outer ring raceway
16 Second outer ring raceway
17 Second flange
18 Hub
19, 19a Caulking part
20 Cylindrical part
21 Tapered hole
22 stamping die
23 Convex
24 recess
25 Clearance
26 Curved surface
27 space
28 Seal ring
29 Lid
30 shoulder
31 steps
32 tone wheel
33 Cover
34 sensors
35 Female spline section
36 Constant Velocity Joint
37 Drive shaft
38 steps
39 Body part
40 nuts
41 First inner ring
42 flat surface
43 Oscillating press device
44 Holding jig
45 Holder
46 Bottom
47 Jig elements
48 restraining part
49 through hole
50 Mounting part
51 Shaft member

Claims

An inner member (2b, 2c, 51) formed with a first flange (6) on the outer peripheral surface of one end and a first inner ring raceway (7) on the outer peripheral surface of the intermediate portion, and the inner members (2b, 2c). 51), the step portion (8) having a smaller outer diameter than the portion where the first inner ring raceway (7) is formed, and the second inner ring raceway ( 9) and an outer ring (3) externally fitted to the step (8), a first outer ring raceway (15) facing the first inner ring raceway (7) on the inner peripheral surface, and the second A second outer ring raceway (16) facing the inner ring raceway (9), an outer ring (4) formed with a second flange (17) on the outer peripheral surface, and the first and second inner ring raceways ( 7, 9) and the first and second outer ring raceways (15, 16), and a plurality of rolling elements (5) each provided, A caulking portion (19, 19) formed by caulking and expanding a portion protruding from the inner ring (3) at least externally fitted to the stepped portion (8) at the other end of the member (2b, 2c, 51) radially outward. 19a), the inner ring (3) fitted on the stepped portion (8) is pressed against the stepped surface (12) of the stepped portion (8), and the inner ring (3) fitted on the stepped portion (8) is pressed. ) Is coupled and fixed to the inner member (2b, 2c, 51), and the inner member (2b, 2c, 51) is at least a step which is an abutting surface of the inner ring (3). From one end of the step (8) including the surface (12) to the side surface of the base end of the first flange (6) including the first inner ring raceway (7). It is hardened by quenching treatment and at least the inner member (2b, 2c, 51 Wheel supporting rolling bearing unit in the portion that protrudes from the inner ring (3), characterized in that was neat without being subjected to the quenching treatment in the other end portion.