JP4015361B2

JP4015361B2 - Wheel bearing device

Info

Publication number: JP4015361B2
Application number: JP2000400411A
Authority: JP
Inventors: 昌世良; 昭吾鈴木
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2000-08-24
Filing date: 2000-12-28
Publication date: 2007-11-28
Anticipated expiration: 2020-12-28
Also published as: JP2002139060A

Description

【０００１】
【発明の属する技術分野】
本発明は車輪軸受装置に関し、詳しくは、自動車の懸架装置に対して車輪を回転自在に支持する車輪軸受装置に関する。
【０００２】
【従来の技術】
自動車の懸架装置に対して車輪を回転自在に支持する車輪軸受装置としては、例えば、特開平１０−９５２０３号公報、特開平１０−１９６６６１号公報、特開平１０−２７２９０３号公報や特開平１１−１２９７０３号公報に開示されたものがある。そのうちの代表的なものとして、特開平１０−２７２９０３号公報に開示された車輪軸受装置を図６に示す。
【０００３】
この車輪軸受装置は、ハブ輪１、内輪２、複列の転動体３、および外方部材である外輪４を主要な構成要素としている。
【０００４】
前記ハブ輪１は、その外周面にアウトボード側の軌道面５が形成されると共に、車輪（図示せず）を取り付けるためのフランジ６を備えている。このフランジ６の円周方向等間隔に、ホイールディスクを固定するためのハブボルト７が植設されている。また、ハブ輪１のインボード側に形成された小径段部８に内輪２を嵌合させ、この内輪２の外周面にインボード側の軌道面９が形成されている。内輪２は、クリープを防ぐために適当な締め代をもって圧入されている。車両のアウトボード側に位置する軌道面５とインボード側に位置する軌道面９とで複列の軌道面を構成する。
【０００５】
外輪４は、内周面に前記ハブ輪１および内輪２の軌道面５，９と対向する複列の軌道面１０，１１が形成され、車体に取り付けるためのフランジ１２を備えている。ハブ輪１および内輪２の軌道面５，９と外輪４の複列の軌道面１０，１１との間に複列の転動体３が組み込まれている。車輪軸受の両端開口部、つまり、ハブ輪１および内輪２の外周面と外輪４の内周面との間にはシール１３，１４が装着され、内部に充填されたグリースの漏洩ならびに外部からの水や異物の侵入を防止するようになっている。
【０００６】
この車輪軸受装置が従動輪用の場合、ハブ輪１の小径段部８に圧入された内輪２が脱落することを防止するため、ハブ輪１の小径段部８から延びて内輪２より突出した端部に形成された円筒部を直径方向外側に加締め、これにより形成された加締め部１５でもってハブ輪１に内輪２を固定している。このハブ輪１の円筒部を加締めることにより軸受すきまを所定値に設定するようにしている。
【０００７】
【発明が解決しようとする課題】
ところで、前述した従来の車輪軸受装置では、ハブ輪１に内輪２を固定するため、ハブ輪１の端部に形成された円筒部を塑性変形させて加締め部１５を形成する際に、内輪２の外径が直径方向外側に膨らみ、その内輪２の外径面に形成された軌道面９に無視できない変形が生じ、転動体３と内輪２が接触する位置での円周方向応力が大きくなり過ぎ、転動疲労寿命が減少することがあるので、接触位置での円周方向応力の、加締めによる増加を抑制するため、接触位置から加締め部１５までの寸法を所定値以上とする必要があり、内輪２がインボード側軸方向に大きくならざるを得なかった。
【０００８】
一方、前述したようにハブ輪１の端部を加締めることにより軸受すきまを所定値に設定するようにしているが、その加締めにより内輪２に変形が生じた場合、軸受すきまが所定値から逸脱する可能性があり、所期の軸受特性を得ることが困難となる。
【０００９】
また、内輪２に高価な軸受鋼、例えば軸受用高炭素クロム鋼としてJIS G 4805で規定されているＳＵＪ２等の高炭素鋼を用いていたため、製品のコストアップを招来するという問題があった。
【００１０】
そこで、本発明は前記問題点に鑑みて提案されたもので、その目的とするところは、内輪の変形を抑制すると共に耐久性に優れた安価な車輪軸受装置を提供することにある。
【００１１】
【課題を解決するための手段】
前記目的を達成するための技術的手段として、本発明に係る車輪軸受装置は、車体に取り付ける車体取付フランジを有し、内周に複列の軌道面を有する外方部材と、車輪を取り付ける車輪取付フランジを有し、外周に第１の軌道面が形成されたハブ輪、および前記ハブ輪の小径段部に嵌合され、外周に第２の軌道面が形成された内輪からなる内方部材と、前記外方部材と内方部材のそれぞれの軌道面間に介装された複列の転動体とを備え、前記ハブ輪の小径段部から延びる端部を加締めてそれらを非分離に一体化した車輪軸受装置において、加締め前の前記ハブ輪の端部が中空状の円筒部をなし、この肉厚が先端に向かって漸増することを特徴とする（請求項１）。
【００１２】
本発明の車輪軸受装置では、加締め前のハブ輪の端部が中空状の円筒部をなし、この肉厚が先端に向かって漸増することにより、加工初期にポンチによって押し広げられる肉量が多くなるため、前記ハブ輪の端部を塑性変形させる軸方向寸法が短くて済む上、ポンチ形状に、早期に充足し易く、内輪を強固に固定することができる。
【００１３】
本発明において、請求項２に記載したように加締め前の前記ハブ輪の端部に形成された円筒部は、その外径が先端に向かい僅かに小径となるように形成されていることが望ましい。このようにすれば、ハブ輪への内輪の組付時、内輪をハブ輪に圧入する際の作業が容易に行える。また、請求項３に記載したように加締め前の前記ハブ輪の端部に形成された円筒部の端面の角部に丸みを付けることが望ましい。このようにすれば、ハブ輪の円筒部を加締める際にバリや亀裂などの欠陥が発生することを防止できる。
【００１４】
また、本発明に係る車輪軸受装置は、車体に取り付ける車体取付フランジを有し、内周に複列の軌道面を有する外方部材と、車輪を取り付ける車輪取付フランジを有し、外周に第１の軌道面が形成されたハブ輪、および前記ハブ輪の小径段部に嵌合され、外周に第２の軌道面が形成された内輪からなる内方部材と、前記外方部材と内方部材のそれぞれの軌道面間に介装された複列の転動体とを備え、前記ハブ輪の小径段部から延びる端部を加締めてそれらを非分離に一体化した車輪軸受装置において、中空状の円筒部をなし、この肉厚が先端に向かって漸増する加締め前の前記ハブ輪の端部を加締め加工した前記加締め部の外端面を、変形起点側から外径方向に亘って軸方向厚みが漸増する第１のテーパ面で形成し、この第１のテーパ面が内輪のインボード側端面に対してなす角度を０〜３０°の範囲に設定したことを特徴とする（請求項４）。
【００１５】
本発明の車輪軸受装置では、前記加締め部の外端面を、変形起点側から外径方向に亘って軸方向厚みである肉厚が漸増する第１のテーパ面で形成し、この第１のテーパ面が内輪のインボード側端面に対してなす角度を０〜３０°の範囲に設定したことにより、内輪の抜け耐力を向上させることができ、かつ、内輪の変形を防止することができる。
【００１６】
本発明は、請求項５に記載したように前記加締め部の外端面を、第１のテーパ面から外周縁に亘って第２のテーパ面で形成し、その第２のテーパ面が内輪のインボード側端面に対して前記第１のテーパ面と逆向きになす角度を４５〜５０°の範囲に設定することが望ましい。このようにすれば、適正な予圧を付与することができ、かつ、加締め加工にバリが発生することもない。
【００１７】
本発明において、請求項６に記載したように前記第１のテーパ面と第２のテーパ面とを、所定の曲率半径を有する曲成面で前記両テーパ面と接するように連設すれば、加締め加工時のかじりやバリの発生を防止でき、かつ、適正な予圧を付与することができる点で望ましい。
【００１８】
本発明において、請求項７に記載したように前記内輪の内径端部に形成した面取り部が円弧状をなし、かつ、その軸方向および径方向寸法がほぼ１ｍｍとすることが望ましい。内輪の内径端部の面取り部形状を、曲率半径が１〜２．５ｍｍである円弧状とし、かつ、その軸方向および径方向寸法がほぼ１ｍｍとすることにより、ハブ輪に内輪を固定するに際して、加締め部が内輪を直径方向外側に押し広げることを抑制し、内輪の変形を最小限に抑える。
【００１９】
さらに、請求項８に記載したように前記ハブ輪の端部外径に環状溝を形成し、前記環状溝はその一部が前記内輪の内径端部に形成された面取り部にかかるように設けられていることが望ましい。このようにすれば、加締め部が内輪を直径方向外側に押し広げることをより一層抑制することができる。
【００２０】
本発明において、請求項９に記載したように前記ハブ輪を、Ｃが０．４５〜０．８０ｗｔ％、好ましくは０．６０〜０．８０ｗｔ％の炭素鋼で形成し、所定の部位に高周波焼き入れによる表面硬化層を形成し、また、請求項１０に記載したように前記内輪を、Ｃが０．６０〜０．８０ｗｔ％の炭素鋼で形成し、芯部まで焼き入れ硬化することが望ましい。このため、高炭素鋼より炭素量が少ない分、所望の転動疲労寿命を維持しながら、加工性（鍛造加工）を向上させることができる。また、ハブ輪については所定の部位に高周波焼き入れによる表面硬化層、内輪については芯部までの焼き入れ硬化により、硬度の低下を抑制して転動疲労寿命を向上させ得る。
【００２１】
【発明の実施の形態】
本発明に係る車輪軸受装置の実施形態を以下に詳述する。
【００２２】
図１に示す実施形態の車輪軸受装置は、ハブ輪２１、内輪２２、複列の転動体２３、および外方部材である外輪２４を主要な構成要素としている。
【００２３】
前記ハブ輪２１は、その外周面にアウトボード側（第１）の軌道面２５が形成されると共に、車輪（図示せず）を取り付けるためのフランジ２６を備えている。このフランジ２６の円周方向等間隔に、ホイールディスクを固定するためのハブボルト（図示せず）が植設されている。また、ハブ輪２１のインボード側に形成された小径段部２８に内輪２２を嵌合させ、この内輪２２の外周面にインボード側（第２）の軌道面２９が形成されている。内輪２２は、クリープを防ぐために適当な締め代をもって圧入されている。車両のアウトボード側に位置する軌道面２５とインボード側に位置する軌道面２９とで複列の軌道面を構成する。
【００２４】
外輪２４は、内周面に前記ハブ輪２１および内輪２２の軌道面２５，２９と対向する複列の軌道面３０，３１が形成され、車体に取り付けるためのフランジ３２を備えている。ハブ輪２１および内輪２２の軌道面２５，２９と外輪２４の複列の軌道面３０，３１との間に複列の転動体２３が組み込まれている。車輪軸受の両端開口部、つまり、ハブ輪２１および内輪２２の外周面と外輪２４の内周面との間にはシール３３，３４が装着され、内部に充填されたグリースの漏洩ならびに外部からの水や異物の侵入を防止するようになっている。
【００２５】
この車輪軸受装置が従動輪用の場合、ハブ輪２１の小径段部２８に圧入された内輪２２が脱落することを防止するため、ハブ輪２１の小径段部２８から延び、内輪２２より突出した端部に形成された円筒部を直径方向外側に加締め、これにより形成された加締め部３５でもってハブ輪２１に内輪２２を固定している。このハブ輪２１の円筒部を加締めることにより軸受すきまを所定値に設定するようにしている。
【００２６】
この加締め前におけるハブ輪２１の端部に形成された円筒部およびそのハブ輪２１の小径段部２８に圧入された内輪２２を図２に示す。
【００２７】
前述したように加締め前におけるハブ輪２１の端部が中空状の円筒部３６をなす。この円筒部３６は、一定の軸方向深さｄ₁を有し、この肉厚が先端に向かって漸増する。円筒部３６の軸方向深さｄ₁は、製品の要求性能により決定される寸法であり、この深さｄ₁が大きい方が、内輪２２の直径方向外側への加締めによる変形は小さくなるが、加締め強度はやや減少する。この円筒部３６は、円筒部３６の底位置での外側半径と内側半径との差を根元部肉厚Ｄ₁とした場合、根元部肉厚Ｄ₁よりも先端部肉厚Ｄ₂が大きくなるように先端に向かって漸増する形状を具備する。
【００２８】
根元部肉厚Ｄ₁よりも先端部肉厚Ｄ₂が同じか、小さくなっている場合に比べ、加工初期にポンチによって押し広げられる肉量が多くなるため、ハブ輪２１の円筒部３６を塑性変形させる軸方向寸法が短くて済む上、ポンチ形状に、早期に充足し易く、内輪２２を強固に固定することができる。
【００２９】
前記ハブ輪２１の円筒部３６の加締め加工は、図４（ａ）〜（ｃ）に示す要領でもって行われる。まず、同図（ａ）に示すようにハブ輪２１をベース３７上に載置した状態で、内輪２２をハブ輪２１の小径段部２８に所定位置まで嵌合させる。つまり、内輪２２のアウトボード側端面がハブ輪２１の小径段部２８の端面に突き合わされる位置まで前記内輪２２をハブ輪２１に圧入する。次に、同図（ｂ）に示すように加締め用ポンチ３８をハブ輪２１の軸心に対して揺動させながら回転させ、その状態で加締め用ポンチ３８の下端に位置する加工面３９によりハブ輪２１の円筒部３６に所定の荷重をかける。そして、同図（ｃ）に示すように最終的に加締め用ポンチ３８を下死点まで下降させることによりハブ輪２１の端部に加締め部３５を形成する。
【００３０】
また、図２に示すように加締め前において、前記ハブ輪２１の端部に形成された円筒部３６は、その外径が先端に向かい僅かに小径となるように形成されている。つまり、円筒部３６の外径が０．０５〜０．２５ｍｍ程度小さいインロー部４０を軸方向に５〜１２ｍｍ程度設ける。このようにすれば、ハブ輪２１への内輪２２の組付時、内輪２２をハブ輪２１に圧入する際の作業が容易に行え、圧入設備に要する費用が削減できて低コスト化が図れる。なお、内輪２２の内径のアウトボード側に０．０５〜０．２５ｍｍ程度の大きなインロー部を軸方向に５〜１２ｍｍ程度設けても同様の効果が得られる。
【００３１】
さらに、加締め前において、前記ハブ輪２１の円筒部３６の端面の角部４１に丸みを付ける。このようにすれば、ハブ輪２１の円筒部３６を加締める際にバリや亀裂などの欠陥が発生することを防止できる。
【００３２】
前記ハブ輪２１は、Ｃが０．４５〜０．８０ｗｔ％、好ましくは０．６０〜０．８０ｗｔ％の中炭素鋼で形成し、図１に示すように所定の部位に高周波焼き入れによる表面硬化層４２を形成する。また、前記内輪２２は、Ｃが０．６０〜０．８０ｗｔ％の中炭素鋼で形成し、芯部まで焼き入れ硬化する。このため、JIS G 4805で規定されているＳＵＪ２（Ｃが０．９５〜１．１０ｗｔ％）等の高炭素鋼よりも炭素量が少ない分、加工性（鍛造加工）が向上する。
【００３３】
また、ハブ輪２１については、所定の部位に高周波焼き入れによる表面硬化層４２を形成したことにより、転動疲労寿命を向上させ、嵌合面のフレッティングを防止している。内輪２２については、インボード側に軌道面２９が寿命的に厳しい箇所であるため、芯部までの焼き入れ硬化により、硬度の低下を抑制して強度面および転動疲労寿命を向上させ得る。Ｃは、製品機能上必要な強度、耐摩耗性および転動疲労寿命を満足させる上で、ハブ輪２１は０．４５ｗｔ％以上、内輪２２は０．６０ｗｔ％以上必要であり、０．８０ｗｔ％より多くなると、加工性、被削性および靭性が低下する点でこれを上限とする。
【００３４】
ハブ輪２１の表面硬化層４２は、ハブ輪２１の所定の部位、すなわち、外輪２４のアウトボード側端部に装着されたシール３３のシールリップが摺接するハブ輪２１の外周面、つまり、シール摺接部から軌道面２５を経て小径段部２８に及ぶ領域に形成する。
【００３５】
この表面硬化層４２の各部をａ〜ｄで示すと、ａ部はシール３３のシールリップが摺接するシールリップ部であるため、耐摩耗性が要求される。ｂ部は転動体２３が転動する軌道面２５であるため、耐寿命性が要求される。ｃ部は内輪２２と当接する部分であり、ｄ部は内輪２２がハブ輪２１に嵌合する部分であるため、耐クリープ性、耐フレッティング性が要求される。なお、ｅ部は加締め部３５であるために延性が要求される。
【００３６】
前記表面硬化層４２を形成するための熱処理は、高周波焼き入れが適している。表面硬化処理としての高周波熱処理は、誘導加熱の特色を有効に生かして硬化層４２を自由に選定し、耐摩耗性を与えたり疲れ強さを改善することができる。誘導加熱は、電磁誘導現象を利用して金属内で電気エネルギーを直接熱エネルギーに変えて発熱させる方法で、これを利用した高周波熱処理には多くの特徴がある。特に、局部加熱ができ、硬化層深さの選定が自由であり、また硬化層以外には著しく熱影響を与えないように制御できるので、母材の性能を保持できる。したがって、ａ〜ｄ部の領域には所望の硬化層４２を形成させつつ、ｅ部を未焼き入れの母材のまま残すことができる。
【００３７】
図２に示すように、内輪２２の内径端部に面取り部４３を形成する。この内輪２２のインボード側端面と内径面とを繋ぐ面取り部４３は、曲率半径ｒ₁が１〜２．５ｍｍである円弧形状を有する。また、ハブ輪２１の円筒部３６の外径に、深さｎが０．５ｍｍ程度、曲率半径ｒ₂が５〜１０ｍｍ程度の環状溝４４をその一部が前記内輪２２の面取り部４３にかかるように形成する。このように内輪２２の内径端部に面取り部４３を形成し、ハブ輪２１の円筒部３６に環状溝４４を形成したことにより、前記ハブ輪２１の円筒部３６を加締めても、内輪２２を直径方向外側に押し広げることを抑制することができ、内輪２２の変形を最小限に抑えることができる。
【００３８】
ここで、前記内輪２２の面取り部４３の曲率半径ｒ₁が１ｍｍよりも小さいと、自動車に取り付けられて走行中に車輪軸受装置に負荷が作用した時、加締め部３５の根元部分の応力集中により亀裂などの損傷を生じる可能性がある。逆に、面取り部４３の曲率半径ｒ₁が２．５ｍｍより大きい場合（図３の傾斜面４５を有する比較例の場合を含む）、ハブ輪２１の円筒部３６を加締める際に、塑性変形した加締め部３５が内輪２２の大きな面取り部４３を直径方向外側に押し広げることになるため、内輪２２の外径が大きく変形し、軸受すきまが所定値から逸脱する可能性があり、所期の軸受特性を得ることが困難となる。
【００３９】
なお、前記面取り部４３は、内輪２２のインボード側端面および内径面に接するような曲率半径で連続的に形成することが可能であるが、内輪２２の熱処理後に面取り加工しなければ難しい点から、この面取り部４３の軸方向および径方向寸法ｃ₁，ｃ₂を曲率半径ｒ₁よりも若干小さく設定することが望ましい。このようにすれば、面取り部４３を内輪２２の熱処理前に加工しておき、熱処理後の面取り作業を省略することができる。
【００４０】
図２に示すハブ輪２１の端部に形成された加締め前の円筒部３６を、図４（ａ）〜（ｃ）に示す要領でもって加締め用ポンチ３８により、加締め加工した後の加締め部３５を図５に示す。
【００４１】
この加締め部３５の最終形状は、その内径側から外径側へ向かって、曲率半径ｒ₃を有する第１の曲成面４６と、変形起点Ｘ側から外径方向に亘って肉厚が漸増する第１のテーパ面４７と、曲率半径ｒ₄を有する第２の曲成面４８と、内輪２２のインボード側端面に対して第１のテーパ面４７と逆向きに角度α°をなす第２のテーパ面４９とで構成され、内輪２２のインボード側端面から加締め部３５の頂点までの軸方向長さｄ₄を有する。
【００４２】
前記加締め部３５の形状において、第１の曲成面４６の曲率半径ｒ₃が３ｍｍより小さいと、加締め加工時、加締め用ポンチ３８の加工面３９をかじり易くなり、加締め用ポンチ３８の寿命低下を招来する。また、前記曲率半径ｒ₃が５ｍｍより大きいと、加締め前に予備成形によりハブ輪２１の円筒部３６の端部を広げておかないと加締め時に加締め用ポンチ３８で軸方向アウトボード側に前方押し出しする必要があり、ハブ輪２１の円筒部内径と加締め用ポンチ３８とが激しく擦り合わされることでバリが発生する。そのため、第１の曲成面４６の曲率半径ｒ₃は、３〜５ｍｍ程度が好ましい。
【００４３】
第１のテーパ面４７は内輪２２のインボード側端面に対して角度β°をなし、その角度β°は、マイナス値になると内輪２２の抜け耐力が低下することが明らかとなっており、また、前記角度β°が３０°より大きいと、内輪２２を径方向に拡げる力が増大することで内輪２２に無視できない変形を生じる。その結果、第１のテーパ面４７の角度β°は、０〜３０°程度が好ましい。
【００４４】
第２の曲成面４８の曲率半径ｒ₄が２ｍｍより小さいと、加締め加工時、加締め用ポンチ３８の加工面３９をかじり易くなり、加締め用ポンチ３８の寿命低下を招来する。また、前記曲率半径ｒ₄が１０ｍｍより大きいと、加締め部３５で内輪２２を押圧する力が弱まり、適正な予圧を付与することが困難となる。そのため、第２の曲成面４８の曲率半径ｒ₄は、２〜１０ｍｍ程度が好ましい。
【００４５】
第２のテーパ面４９の角度α°が４５°より小さいと、加締め部３５で内輪２２を押圧する力が弱まり、適正な予圧を付与することが困難となる。また、前記角度α°が５０°より大きいと、加締め部３５が外径側に広がろうとするハブ輪２１の円筒部３６の端部と加締め用ポンチ３８とが激しく擦り合わされてバリを生じる。その結果、第２のテーパ面４９の角度α°は、４５〜５０°程度が好ましい。
【００４６】
但し、第２の曲成面４８と第１のテーパ面４７とが接しないように加締める場合には、第２の曲成面４８における曲率半径ｒ₄をもっと大きく設定することにより、第２のテーパ面４９を省略することも可能である。この場合、好ましくは、第２の曲成面４８と第１のテーパ面４７とのつなぎ目に１〜３ｍｍ程度の曲率半径を有する第３の曲成面を形成することにより、そのつなぎ目付近から発生するバリを抑制する上で、加締め用ポンチ３８の寿命を向上させることができる。
【００４７】
なお、加締め後の形状において、ハブ輪２１の外径に環状溝４４を残すことと、内輪２２の内径端部に面取り部４３を形成することで、内輪２２の変形を最小限に抑制することができる。
【００４８】
【実施例】
前述した図２に示す加締め前のハブ輪２１の端部および内輪２２の形態を実施例として、図３に示す加締め前のハブ輪２１の端部および内輪２２の形態を比較例とする。図３の比較例では、内輪２２の内径端部、つまり、内周端部に大きな傾斜面４５とインボード側端面と内径面とを繋ぐ面取り部４３’を形成する。なお、ハブ輪２１の端部における他の形状は図２と同一である。
【００４９】
図３の比較例において、内輪２２の外径ｄ₂が５８．８ｍｍ、内径ｄ₃が２８ｍｍ、傾斜面４５および面取り部４３の軸方向寸法ｃ₁’が３．５ｍｍ、径方向寸法ｃ₂’が１．５ｍｍ、傾斜面の角度θが１５°、面取り部４３の曲率半径ｒ₁’が５ｍｍで、かつ、ハブ輪２１の円筒部３６の外径に、深さｎが０．５ｍｍ程度、曲率半径ｒ₂が７．８ｍｍ程度の環状溝４４をその一部が内輪２２の面取り部４３’にかかるように形成した場合、加締め加工により内輪２２の端面から２ｍｍの位置の内輪２２の外径が３５μｍ程度膨張した。
【００５０】
これに対して、図２の実施例では、内輪２２の外径ｄ₂が５８．８ｍｍ、内径ｄ₃が２８ｍｍ、面取り部４３の軸方向寸法ｃ₁が１ｍｍ、径方向寸法ｃ₂が１ｍｍ、曲率半径ｒ₁が１．５ｍｍで、かつ、ハブ輪２１の円筒部３６の外径に、深さｎが０．５ｍｍ程度、曲率半径ｒ₂が７．８ｍｍ程度の環状溝４４をその一部が前記内輪２２の面取り部４３にかかるように形成した場合、加締め加工により内輪２２の端面から２ｍｍの位置の内輪２２の外径が１５μｍ程度しか膨張しなかった。
【００５１】
なお、図２の実施例と図３の比較例において、加締め後の加締め部３５の最終形状は、図５に示すように第１の曲成面４６での曲率半径ｒ₃が３ｍｍ、第１のテーパ面４７での角度β°が５°、第２の曲成面４８での曲率半径ｒ₄が４．２ｍｍ、第２のテーパ面４９での角度α°が４８．３°、内輪２２のインボード側端面から加締め部３５の頂点までの軸方向長さｄ₄が５．４ｍｍであり、加締め後に、ハブ輪２１の外径に環状溝４４を残すことと、内輪２２の内径端部に面取り部４３を形成することで、内輪２２の変形を最小限に抑制することができた。
【００５２】
【発明の効果】
本発明によれば、内輪の変形を無視できる程度まで減少させることができるので、転動疲労寿命を確保した上で、加締め部から転動体と内輪が接触する位置までの距離を短くすることができ、内輪およびハブ輪を軸方向にコンパクトに設計することができるため、製品重量の低減化が図れて自動車に使用した場合に燃費の向上が実現容易となり、地球環境への負荷が軽減できる。さらに、ハブ輪および内輪の材料費や加工費も減少するので、安価な車輪軸受装置を提供できる。
【図面の簡単な説明】
【図１】本発明に係る車輪軸受装置の実施形態を示す半断面図である。
【図２】本発明の実施例で、加締め前のハブ輪の端部および内輪を示す半断面図である。
【図３】図２の実施例に対する比較例で、加締め前のハブ輪の端部および内輪を示す半断面図である。
【図４】（ａ）〜（ｃ）は揺動加工によるハブ輪の端部を加締め加工する要領を説明するための工程図である。
【図５】本発明の実施例で、加締め後のハブ輪の端部および内輪を示す半断面図である。
【図６】車輪軸受装置の従来例を示す半断面図である。
【符号の説明】
２１内方部材（ハブ輪）
２２内方部材（内輪）
２３転動体
２４外方部材（外輪）
２５第１の軌道面
２６車輪取付フランジ
２８小径段部
２９第２の軌道面
３０，３１軌道面
３２車体取付フランジ
３５加締め部
３６円筒部
４１角部
４２表面硬化層
４３面取り部
４４環状溝
４７第１のテーパ面
４８曲成面（第２の曲成面）
４９第２のテーパ面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wheel bearing device, and more particularly to a wheel bearing device that rotatably supports a wheel with respect to a suspension device of an automobile.
[0002]
[Prior art]
Examples of the wheel bearing device that supports the wheel rotatably with respect to the suspension device of the automobile include, for example, JP-A-10-95203, JP-A-10-196661, JP-A-10-272903, and JP-A-11-11. There is one disclosed in Japanese Patent No. 129703. As a representative one of them, a wheel bearing device disclosed in Japanese Patent Laid-Open No. 10-272903 is shown in FIG.
[0003]
The wheel bearing device includes a hub wheel 1, an inner ring 2, a double row rolling element 3, and an outer ring 4 that is an outer member as main components.
[0004]
The hub wheel 1 has a track surface 5 on the outboard side formed on the outer peripheral surface thereof, and includes a flange 6 for attaching a wheel (not shown). Hub bolts 7 for fixing the wheel disc are implanted at equal intervals in the circumferential direction of the flange 6. Further, the inner ring 2 is fitted to a small diameter step portion 8 formed on the inboard side of the hub wheel 1, and an inboard side raceway surface 9 is formed on the outer peripheral surface of the inner ring 2. The inner ring 2 is press-fitted with an appropriate tightening margin to prevent creep. The raceway surface 5 located on the outboard side of the vehicle and the raceway surface 9 located on the inboard side constitute a double-row raceway surface.
[0005]
The outer ring 4 is formed with double-row raceway surfaces 10 and 11 facing the raceway surfaces 5 and 9 of the hub wheel 1 and the inner ring 2 on the inner peripheral surface, and includes a flange 12 for mounting to the vehicle body. Double row rolling elements 3 are incorporated between the raceway surfaces 5 and 9 of the hub wheel 1 and the inner ring 2 and the double row raceway surfaces 10 and 11 of the outer ring 4. Seals 13 and 14 are attached between the opening portions at both ends of the wheel bearing, that is, between the outer peripheral surface of the hub wheel 1 and the inner ring 2 and the inner peripheral surface of the outer ring 4 to leak grease filled inside and It is designed to prevent water and foreign objects from entering.
[0006]
When this wheel bearing device is for a driven wheel, the inner ring 2 press-fitted into the small-diameter step portion 8 of the hub wheel 1 extends from the small-diameter step portion 8 of the hub wheel 1 and protrudes from the inner ring 2 in order to prevent the inner ring 2 from falling off. The cylindrical portion formed at the end portion is swaged outward in the diameter direction, and the inner ring 2 is fixed to the hub wheel 1 with the swaged portion 15 formed thereby. The bearing clearance is set to a predetermined value by caulking the cylindrical portion of the hub wheel 1.
[0007]
[Problems to be solved by the invention]
By the way, in the conventional wheel bearing device described above, when the inner ring 2 is fixed to the hub wheel 1, the cylindrical portion formed at the end of the hub wheel 1 is plastically deformed to form the crimped portion 15. 2 swells outward in the diametrical direction, a non-negligible deformation occurs in the raceway surface 9 formed on the outer diameter surface of the inner ring 2, and the circumferential stress at the position where the rolling element 3 and the inner ring 2 come into contact is large. Since the rolling fatigue life may decrease, the dimension from the contact position to the crimped portion 15 is set to a predetermined value or more in order to suppress the increase in the circumferential stress at the contact position due to the crimping. The inner ring 2 has to be increased in the axial direction on the inboard side.
[0008]
On the other hand, the bearing clearance is set to a predetermined value by caulking the end portion of the hub wheel 1 as described above. However, when the inner ring 2 is deformed by the caulking, the bearing clearance is increased from the predetermined value. There is a possibility of deviating, and it becomes difficult to obtain the desired bearing characteristics.
[0009]
Further, since expensive bearing steel, for example, high carbon steel such as SUJ2 defined in JIS G 4805 is used for the inner ring 2 as a high carbon chromium steel for bearings, there is a problem in that the cost of the product is increased.
[0010]
Accordingly, the present invention has been proposed in view of the above problems, and an object thereof is to provide an inexpensive wheel bearing device that suppresses deformation of the inner ring and is excellent in durability.
[0011]
[Means for Solving the Problems]
As technical means for achieving the above object, a wheel bearing device according to the present invention has a vehicle body mounting flange attached to a vehicle body, an outer member having a double row raceway surface on an inner periphery, and a wheel to which a wheel is attached. A hub ring having a mounting flange and having a first raceway surface formed on the outer periphery, and an inner member that is fitted to a small-diameter step portion of the hub ring and has a second raceway surface formed on the outer periphery. And a double row rolling element interposed between the raceway surfaces of the outer member and the inner member, and crimping the end portion extending from the small diameter step portion of the hub wheel so that they are not separated. In the integrated wheel bearing device, the end portion of the hub wheel before caulking forms a hollow cylindrical portion, and the thickness thereof gradually increases toward the tip (Claim 1).
[0012]
In the wheel bearing device of the present invention, the end of the hub wheel before caulking forms a hollow cylindrical portion, and this wall thickness gradually increases toward the tip, so that the amount of the wall that is pushed and expanded by the punch at the initial stage of processing is reduced. Therefore, the axial dimension for plastically deforming the end portion of the hub wheel only needs to be short, and it is easy to satisfy the punch shape at an early stage, and the inner ring can be firmly fixed.
[0013]
In the present invention, as described in claim 2, the cylindrical portion formed at the end of the hub wheel before caulking is formed so that its outer diameter is slightly smaller toward the tip. desirable. In this way, when assembling the inner ring to the hub ring, the work for press-fitting the inner ring into the hub ring can be easily performed. In addition, as described in claim 3, it is desirable to round the corner of the end surface of the cylindrical portion formed at the end of the hub wheel before caulking. If it does in this way, when caulking the cylindrical part of a hub wheel, it can prevent generating defects, such as a burr and a crack.
[0014]
The wheel bearing device according to the present invention has a vehicle body mounting flange attached to the vehicle body, an outer member having a double-row raceway surface on the inner periphery, a wheel mounting flange to which the wheel is attached, and a first on the outer periphery. A hub ring formed with a raceway surface, an inner member that is fitted to a small-diameter step portion of the hub ring and has a second raceway surface formed on the outer periphery, and the outer member and the inner member In a wheel bearing device comprising a plurality of rolling elements interposed between the respective raceway surfaces, and crimping ends extending from the small-diameter step portion of the hub wheel so as to integrate them in a non-separable manner. The outer end surface of the caulking portion obtained by caulking the end portion of the hub wheel before caulking, whose thickness gradually increases toward the tip, extends from the deformation starting point side to the outer radial direction. the first is formed by the tapered surface, the first tapered surface inner has an axial thickness increases gradually The angle formed with respect to the inboard side end face, characterized in that set in the range of 0 to 30 ° (claim 4).
[0015]
In the wheel bearing device of the present invention, the outer end surface of the caulking portion is formed by a first tapered surface whose thickness, which is the axial thickness, gradually increases from the deformation starting point side to the outer radial direction. By setting the angle formed by the taper surface with respect to the end face on the inboard side of the inner ring within a range of 0 to 30 °, it is possible to improve the slip-off resistance of the inner ring and to prevent deformation of the inner ring. .
[0016]
According to the present invention, the outer end surface of the caulking portion is formed as a second taper surface from the first taper surface to the outer peripheral edge, and the second taper surface is the inner ring. It is desirable to set the angle formed opposite to the first tapered surface with respect to the inboard side end surface in a range of 45 to 50 °. In this way, an appropriate preload can be applied, and no burrs are generated in the caulking process.
[0017]
In the present invention, as described in claim 6, if the first taper surface and the second taper surface are connected so as to be in contact with the two taper surfaces with a curved surface having a predetermined radius of curvature, It is desirable in that it can prevent the occurrence of galling and burrs during the caulking process and can provide an appropriate preload.
[0018]
In the present invention, as described in claim 7, it is desirable that the chamfered portion formed at the inner diameter end portion of the inner ring has an arc shape, and the axial direction and radial dimension thereof are approximately 1 mm. When the inner ring is fixed to the hub ring by setting the shape of the chamfered portion at the inner diameter end of the inner ring to an arc shape with a radius of curvature of 1 to 2.5 mm and an axial direction and a radial dimension of about 1 mm. The caulking portion suppresses the inner ring from being pushed outward in the diameter direction, and the deformation of the inner ring is minimized.
[0019]
Furthermore, as described in claim 8, an annular groove is formed in the outer diameter of the end portion of the hub wheel, and the annular groove is provided so that a part of the annular groove covers a chamfered portion formed in the inner diameter end portion of the inner ring. It is desirable that If it does in this way, it can suppress further that a crimping part pushes an inner ring | wheel outward in a diameter direction.
[0020]
In the present invention, as described in claim 9, the hub ring is made of carbon steel having C of 0.45 to 0.80 wt%, preferably 0.60 to 0.80 wt%, and high frequency is applied to a predetermined portion. A surface hardened layer is formed by quenching, and the inner ring is formed of carbon steel having C of 0.60 to 0.80 wt% and hardened to the core as described in claim 10. desirable. For this reason, workability (forging process) can be improved, maintaining a desired rolling fatigue life by the amount of carbon less than that of high carbon steel. In addition, a hardened surface can be improved by induction hardening at a predetermined portion for the hub ring, and a decrease in hardness can be suppressed by quenching to the core for the inner ring, thereby improving the rolling fatigue life.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a wheel bearing device according to the present invention will be described in detail below.
[0022]
The wheel bearing device of the embodiment shown in FIG. 1 includes a hub wheel 21, an inner ring 22, a double row rolling element 23, and an outer ring 24 that is an outer member as main components.
[0023]
The hub wheel 21 is formed with an outer surface (first) raceway surface 25 on an outer peripheral surface thereof and a flange 26 for attaching a wheel (not shown). Hub bolts (not shown) for fixing the wheel disc are implanted at equal intervals in the circumferential direction of the flange 26. Further, an inner ring 22 is fitted to a small diameter step portion 28 formed on the inboard side of the hub wheel 21, and an inboard side (second) raceway surface 29 is formed on the outer peripheral surface of the inner ring 22. The inner ring 22 is press-fitted with an appropriate tightening allowance to prevent creep. The track surface 25 located on the outboard side of the vehicle and the track surface 29 located on the inboard side constitute a double-row track surface.
[0024]
The outer ring 24 is formed with double-row raceway surfaces 30 and 31 facing the raceway surfaces 25 and 29 of the hub wheel 21 and the inner ring 22 on the inner circumferential surface, and includes a flange 32 for attaching to the vehicle body. Double row rolling elements 23 are incorporated between the raceway surfaces 25 and 29 of the hub wheel 21 and the inner ring 22 and the double row raceway surfaces 30 and 31 of the outer ring 24. Seals 33 and 34 are mounted between the opening portions at both ends of the wheel bearing, that is, between the outer peripheral surface of the hub ring 21 and the inner ring 22 and the inner peripheral surface of the outer ring 24, and leakage of grease filled therein and leakage from the outside. It is designed to prevent water and foreign objects from entering.
[0025]
When this wheel bearing device is for a driven wheel, it extends from the small diameter step portion 28 of the hub wheel 21 and protrudes from the inner ring 22 in order to prevent the inner ring 22 press-fitted into the small diameter step portion 28 of the hub wheel 21 from falling off. The cylindrical portion formed at the end portion is swaged outward in the diameter direction, and the inner ring 22 is fixed to the hub wheel 21 by the swaged portion 35 formed thereby. The bearing clearance is set to a predetermined value by caulking the cylindrical portion of the hub wheel 21.
[0026]
A cylindrical portion formed at the end of the hub wheel 21 before the caulking and the inner ring 22 press-fitted into the small diameter step portion 28 of the hub wheel 21 are shown in FIG.
[0027]
As described above, the end of the hub wheel 21 before caulking forms a hollow cylindrical portion 36. The cylindrical portion 36 has a constant axial depth d ₁ , and the thickness gradually increases toward the tip. The axial depth d ₁ of the cylindrical portion 36 is a dimension determined by the required performance of the product. The larger the depth d _{1, the} smaller the deformation caused by caulking the inner ring 22 outward in the diameter direction. The caulking strength is slightly reduced. When the difference between the outer radius and the inner radius at the bottom position of the cylindrical portion 36 is the root portion thickness D ₁ , the cylindrical portion 36 has a tip portion thickness D ₂ larger than the root portion thickness D _1. Thus, the shape gradually increases toward the tip.
[0028]
Compared with the case where the tip portion thickness D ₂ is the same or smaller than the root portion thickness D _{1, the} amount of the wall that is pushed out by the punch in the initial stage of processing increases, so the cylindrical portion 36 of the hub wheel 21 is made plastic. The axial dimension to be deformed can be short, and it is easy to satisfy the punch shape at an early stage, and the inner ring 22 can be firmly fixed.
[0029]
The caulking process of the cylindrical portion 36 of the hub wheel 21 is performed according to the procedure shown in FIGS. First, the inner ring 22 is fitted to the small-diameter step portion 28 of the hub wheel 21 to a predetermined position with the hub wheel 21 placed on the base 37 as shown in FIG. That is, the inner ring 22 is press-fitted into the hub wheel 21 until the end surface on the outboard side of the inner ring 22 abuts with the end surface of the small diameter step portion 28 of the hub wheel 21. Next, as shown in FIG. 4B, the caulking punch 38 is rotated while being swung with respect to the axis of the hub wheel 21, and in this state, the machining surface 39 positioned at the lower end of the caulking punch 38. Thus, a predetermined load is applied to the cylindrical portion 36 of the hub wheel 21. Then, as shown in FIG. 3C, the caulking punch 38 is finally lowered to the bottom dead center, thereby forming the caulking portion 35 at the end of the hub wheel 21.
[0030]
Also, as shown in FIG. 2, before caulking, the cylindrical portion 36 formed at the end of the hub wheel 21 is formed so that its outer diameter is slightly smaller toward the tip. That is, the inlay portion 40 having an outer diameter of the cylindrical portion 36 as small as about 0.05 to 0.25 mm is provided in the axial direction about 5 to 12 mm. In this way, when assembling the inner ring 22 to the hub wheel 21, the work for press-fitting the inner ring 22 into the hub wheel 21 can be easily performed, the cost required for the press-fitting equipment can be reduced, and the cost can be reduced. The same effect can be obtained by providing a large inlay portion of about 0.05 to 0.25 mm on the outboard side of the inner diameter of the inner ring 22 in the axial direction of about 5 to 12 mm.
[0031]
Furthermore, the corner 41 of the end surface of the cylindrical portion 36 of the hub wheel 21 is rounded before caulking. In this way, it is possible to prevent the occurrence of defects such as burrs and cracks when the cylindrical portion 36 of the hub wheel 21 is caulked.
[0032]
The hub ring 21 is made of medium carbon steel with C of 0.45 to 0.80 wt%, preferably 0.60 to 0.80 wt%, and a surface by induction hardening as shown in FIG. A hardened layer 42 is formed. The inner ring 22 is made of medium carbon steel having C of 0.60 to 0.80 wt% and hardened to the core. For this reason, workability (forging process) is improved by the amount of carbon less than that of high carbon steel such as SUJ2 (C is 0.95 to 1.10 wt%) defined in JIS G 4805.
[0033]
Further, the hub wheel 21 is formed with a hardened surface layer 42 by induction hardening at a predetermined portion, thereby improving the rolling fatigue life and preventing fretting of the fitting surface. As for the inner ring 22, since the raceway surface 29 is a severe part on the inboard side in terms of life, quenching to the core can suppress the decrease in hardness and improve the strength surface and rolling fatigue life. C satisfies the strength, wear resistance, and rolling fatigue life required for the product function, and the hub ring 21 requires 0.45 wt% or more, and the inner ring 22 requires 0.60 wt% or more, 0.80 wt%. If it is more, this is the upper limit in that the workability, machinability and toughness are lowered.
[0034]
The surface hardened layer 42 of the hub wheel 21 is a predetermined portion of the hub wheel 21, that is, the outer peripheral surface of the hub wheel 21, which is in contact with the seal lip of the seal 33 attached to the end portion on the outboard side of the outer ring 24, that is, the seal It is formed in a region extending from the sliding contact portion through the raceway surface 25 to the small diameter step portion 28.
[0035]
When each part of the surface hardened layer 42 is indicated by a to d, the a part is a seal lip part with which the seal lip of the seal 33 is slidably contacted, so that wear resistance is required. Since part b is the raceway surface 25 on which the rolling elements 23 roll, life resistance is required. The portion c is a portion that contacts the inner ring 22, and the portion d is a portion where the inner ring 22 is fitted to the hub wheel 21, so that creep resistance and fretting resistance are required. In addition, since e part is the crimping part 35, ductility is requested | required.
[0036]
As the heat treatment for forming the surface hardened layer 42, induction hardening is suitable. In the high-frequency heat treatment as the surface hardening treatment, the hardened layer 42 can be freely selected by making effective use of the feature of induction heating, and wear resistance and fatigue strength can be improved. Induction heating is a method of generating heat by directly converting electrical energy into thermal energy in a metal using an electromagnetic induction phenomenon, and there are many features of high-frequency heat treatment using this. In particular, local heating can be performed, the depth of the hardened layer can be freely selected, and control other than the hardened layer can be controlled so as not to significantly affect the heat, so that the performance of the base material can be maintained. Accordingly, the desired hardened layer 42 is formed in the regions a to d, and the portion e can be left as an unquenched base material.
[0037]
As shown in FIG. 2, a chamfered portion 43 is formed at the inner diameter end portion of the inner ring 22. The chamfered portion 43 that connects the inboard side end surface of the inner ring 22 and the inner diameter surface has an arc shape with a curvature radius r _{1 of 1} to 2.5 mm. In addition, an annular groove 44 having a depth n of about 0.5 mm and a curvature radius r ₂ of about 5 to 10 mm is formed on the outer diameter of the cylindrical portion 36 of the hub wheel 21, and a part of the annular groove 44 covers the chamfered portion 43 of the inner ring 22. To form. Since the chamfered portion 43 is formed at the inner diameter end portion of the inner ring 22 and the annular groove 44 is formed in the cylindrical portion 36 of the hub ring 21, the inner ring 22 can be tightened even if the cylindrical portion 36 of the hub ring 21 is crimped. Can be suppressed from being pushed outward in the diameter direction, and deformation of the inner ring 22 can be minimized.
[0038]
Here, if the radius of curvature r ₁ of the chamfered portion 43 of the inner ring 22 is smaller than ₁ mm, the stress concentration at the root portion of the caulking portion 35 is applied when a load is applied to the wheel bearing device during traveling while being attached to the automobile. May cause damage such as cracks. Conversely, when the radius of curvature r ₁ of the chamfered portion 43 is larger than 2.5 mm (including the case of the comparative example having the inclined surface 45 in FIG. 3), the plastic deformation is caused when the cylindrical portion 36 of the hub wheel 21 is caulked. Since the crimped portion 35 pushes the large chamfered portion 43 of the inner ring 22 outward in the diameter direction, the outer diameter of the inner ring 22 may be greatly deformed, and the bearing clearance may deviate from a predetermined value. It is difficult to obtain the bearing characteristics.
[0039]
The chamfered portion 43 can be continuously formed with a radius of curvature so as to be in contact with the inboard side end surface and the inner diameter surface of the inner ring 22, but it is difficult to chamfer after the heat treatment of the inner ring 22. The axial and radial dimensions c ₁ and c ₂ of the chamfered portion 43 are desirably set slightly smaller than the curvature radius r ₁ . In this way, the chamfered portion 43 is processed before the inner ring 22 is heat-treated, and the chamfering work after the heat treatment can be omitted.
[0040]
The cylindrical part 36 before caulking formed at the end of the hub wheel 21 shown in FIG. 2 is caulked by the caulking punch 38 in the manner shown in FIGS. 4 (a) to 4 (c). The caulking portion 35 is shown in FIG.
[0041]
The final shape of the caulking portion 35 has a first curved surface 46 having a radius of curvature r ₃ from the inner diameter side to the outer diameter side, and a wall thickness extending from the deformation starting point X side to the outer diameter direction. A first taper surface 47 that gradually increases, a second curved surface 48 having a radius of curvature r _4, and an angle α ° opposite to the first taper surface 47 with respect to the inboard side end surface of the inner ring 22 . The second tapered surface 49 is formed, and has an axial length d ₄ from the end surface on the inboard side of the inner ring 22 to the apex of the crimped portion 35.
[0042]
When the radius of curvature r ₃ of the first curved surface 46 is smaller than ₃ mm in the shape of the caulking portion 35, the machining surface 39 of the caulking punch 38 is easily gnawed during caulking, and the caulking punch This leads to a decrease in lifespan of 38. Further, if the radius of curvature r ₃ is larger than 5 mm, the end of the cylindrical portion 36 of the hub wheel 21 is not expanded by pre-forming before caulking, and the caulking punch 38 is used for the caulking punch 38 when caulking. It is necessary to push forward, and the inner diameter of the cylindrical portion of the hub wheel 21 and the caulking punch 38 are rubbed together violently. Therefore, the radius of curvature r ₃ of the first curved surface 46 is preferably about ₃ to 5 mm.
[0043]
The first taper surface 47 forms an angle β ° with respect to the end face on the inboard side of the inner ring 22, and it is clear that if the angle β ° becomes a negative value, the slip-off resistance of the inner ring 22 decreases. On the other hand, when the angle β ° is larger than 30 °, a force that expands the inner ring 22 in the radial direction increases, so that the inner ring 22 undergoes non-negligible deformation. As a result, the angle β ° of the first tapered surface 47 is preferably about 0 to 30 °.
[0044]
If the radius of curvature r ₄ of the second curved surface 48 is smaller than 2 mm, the machining surface 39 of the caulking punch 38 is easily gnawed during caulking, and the life of the caulking punch 38 is reduced. On the other hand, if the radius of curvature r ₄ is larger than 10 mm, the force that presses the inner ring 22 by the caulking portion 35 is weakened, and it becomes difficult to apply an appropriate preload. Therefore, the radius of curvature r ₄ of the second curved surface 48 is preferably about 2 to 10 mm.
[0045]
If the angle α ° of the second tapered surface 49 is smaller than 45 °, the force that presses the inner ring 22 by the crimping portion 35 is weakened, and it becomes difficult to apply an appropriate preload. If the angle α ° is larger than 50 °, the end of the cylindrical portion 36 of the hub wheel 21 and the caulking punch 38 that the caulking portion 35 tends to spread toward the outer diameter side are vigorously rubbed together to remove burrs. Arise. As a result, the angle α ° of the second tapered surface 49 is preferably about 45 to 50 °.
[0046]
However, when caulking so that the second curved surface 48 and the first tapered surface 47 are not in contact with each other, the radius of curvature r ₄ on the second curved surface 48 is set to be larger, so that the second It is also possible to omit the tapered surface 49. In this case, it is preferable that a third curved surface having a radius of curvature of about 1 to 3 mm is formed at the joint between the second curved surface 48 and the first tapered surface 47 to generate from the vicinity of the joint. In suppressing the burrs, the life of the caulking punch 38 can be improved.
[0047]
In addition, in the shape after caulking, the deformation of the inner ring 22 is suppressed to a minimum by leaving the annular groove 44 in the outer diameter of the hub ring 21 and forming the chamfered portion 43 at the inner diameter end of the inner ring 22. be able to.
[0048]
【Example】
The embodiment of the end portion of the hub wheel 21 and the inner ring 22 before caulking shown in FIG. 2 is used as an example, and the embodiment of the end portion of the hub wheel 21 and the inner ring 22 before caulking shown in FIG. . In the comparative example of FIG. 3, a chamfered portion 43 ′ connecting the large inclined surface 45, the inboard side end surface and the inner diameter surface is formed at the inner diameter end portion of the inner ring 22, that is, the inner peripheral end portion. The other shapes at the end of the hub wheel 21 are the same as those in FIG.
[0049]
In the comparative example of FIG. 3, the outer diameter d ₂ of the inner ring 22 is 58.8 mm, the inner diameter d ₃ is 28 mm, the axial dimension c ₁ ′ of the inclined surface 45 and the chamfered portion 43 is 3.5 mm, and the radial dimension c ₂ ′. Is 1.5 mm, the angle θ of the inclined surface is 15 °, the radius of curvature r ₁ ′ of the chamfered portion 43 is 5 mm, and the depth n is about 0.5 mm at the outer diameter of the cylindrical portion 36 of the hub wheel 21. When the annular groove 44 having a radius of curvature r ₂ of about 7.8 mm is formed so that a part thereof covers the chamfered portion 43 ′ of the inner ring 22, the outer ring 22 is positioned 2 mm from the end face of the inner ring 22 by caulking. The diameter expanded about 35 μm.
[0050]
On the other hand, in the embodiment of FIG. 2, the outer diameter d ₂ of the inner ring 22 is 58.8 mm, the inner diameter d ₃ is 28 mm, the axial dimension c ₁ of the chamfer 43 is 1 mm, the radial dimension c ₂ is 1 mm, An annular groove 44 having a radius of curvature r ₁ of 1.5 mm, a depth n of about 0.5 mm, and a radius of curvature r ₂ of about 7.8 mm is formed on a part of the outer diameter of the cylindrical portion 36 of the hub wheel 21. Is formed so as to cover the chamfered portion 43 of the inner ring 22, the outer diameter of the inner ring 22 at a position of 2 mm from the end face of the inner ring 22 expanded only about 15 μm by caulking.
[0051]
In the embodiment of FIG. 2 and the comparative example of FIG. 3, the final shape of the caulking portion 35 after caulking is 3 mm in radius of curvature r ₃ at the first curved surface 46 as shown in FIG. The angle β ° at the first tapered surface 47 is 5 °, the radius of curvature r ₄ at the second curved surface 48 is 4.2 mm, the angle α ° at the second tapered surface 49 is 48.3 °, The axial length d ₄ from the end face on the inboard side of the inner ring 22 to the apex of the caulking portion 35 is 5.4 mm, and after the caulking, an annular groove 44 is left on the outer diameter of the hub ring 21, and the inner ring 22 By forming the chamfered portion 43 at the inner diameter end portion, deformation of the inner ring 22 could be minimized.
[0052]
【The invention's effect】
According to the present invention, since the deformation of the inner ring can be reduced to a negligible level, the distance from the crimped portion to the position where the rolling element and the inner ring contact is shortened while ensuring the rolling fatigue life. Because the inner ring and hub ring can be designed to be compact in the axial direction, the weight of the product can be reduced, making it easier to improve fuel efficiency when used in automobiles and reducing the burden on the global environment. . Further, since the material cost and processing cost of the hub wheel and the inner ring are reduced, an inexpensive wheel bearing device can be provided.
[Brief description of the drawings]
FIG. 1 is a half sectional view showing an embodiment of a wheel bearing device according to the present invention.
FIG. 2 is a half sectional view showing an end portion and an inner ring of a hub wheel before caulking in an embodiment of the present invention.
FIG. 3 is a comparative example with respect to the embodiment of FIG. 2 and is a half sectional view showing an end portion and an inner ring of a hub ring before caulking.
FIGS. 4A to 4C are process diagrams for explaining a procedure for caulking an end portion of a hub wheel by swing machining. FIGS.
FIG. 5 is a half sectional view showing the end of the hub wheel and the inner ring after caulking in the embodiment of the present invention.
FIG. 6 is a half sectional view showing a conventional example of a wheel bearing device.
[Explanation of symbols]
21 Inner member (hub ring)
22 Inner member (inner ring)
23 Rolling element 24 Outer member (outer ring)
25 First track surface 26 Wheel mounting flange 28 Small diameter step portion 29 Second track surface 30, 31 Track surface 32 Vehicle body mounting flange 35 Clamping portion 36 Cylindrical portion 41 Corner portion 42 Surface hardening layer 43 Chamfered portion 44 Annular groove 47 First tapered surface 48 curved surface (second curved surface)
49 Second taper surface

Claims

An outer member having a vehicle body mounting flange attached to the vehicle body, an outer member having a double-row raceway surface on the inner periphery, a wheel attachment flange to which a wheel is attached, and a hub wheel having a first raceway surface formed on the outer periphery; An inner member comprising an inner ring that is fitted to a small-diameter step portion of the hub wheel and has a second raceway surface formed on the outer periphery thereof, and is interposed between the raceway surfaces of the outer member and the inner member. In a wheel bearing device comprising a double row rolling element, wherein end portions extending from the small-diameter step portion of the hub ring are caulked and integrated in a non-separable manner, the end portion of the hub ring before caulking is hollow A wheel bearing device characterized in that the thickness of the cylindrical portion increases gradually toward the tip.

The wheel bearing device according to claim 1, wherein the cylindrical portion formed at the end of the hub wheel before caulking is formed so that an outer diameter thereof is slightly smaller toward the tip. .

The wheel bearing device according to claim 1 or 2, wherein a corner portion of an end surface of a cylindrical portion formed at an end portion of the hub wheel before caulking is rounded.

An outer member having a vehicle body attachment flange attached to the vehicle body, an outer member having a double row raceway surface on the inner periphery, a wheel attachment flange to which a wheel is attached, and a first raceway surface formed on the outer periphery; and An inner member comprising an inner ring that is fitted to a small-diameter step portion of the hub wheel and has a second raceway surface formed on the outer periphery thereof, and is interposed between the raceway surfaces of the outer member and the inner member. In a wheel bearing device comprising a double row rolling element, the end portion extending from the small diameter step portion of the hub wheel is plastically deformed to form a swaged portion, and these are integrated in a non-separable manner , a hollow cylindrical portion None of the outer end face of the crimped portion of the end portion was machined crimping of the hub wheel before crimping of the wall thickness gradually increases toward the tip, the axial thickness from the deformation starting point side over the outer diameter direction There is formed in the first tapered surface gradually increasing, Invocation the first tapered surface of the inner ring Wheel bearing apparatus characterized by setting the angle formed with respect to de-side end face in the range of 0 to 30 °.

An outer end surface of the caulking portion is formed as a second tapered surface from the first tapered surface to the outer peripheral edge, and the second tapered surface is the first tapered surface with respect to the inboard side end surface of the inner ring . The wheel bearing device according to claim 4, wherein an angle formed in a direction opposite to the tapered surface is set in a range of 45 to 50 °.

6. The wheel bearing device according to claim 5, wherein the first taper surface and the second taper surface are continuously provided so as to be in contact with both the taper surfaces by a curved surface having a predetermined radius of curvature. .

The wheel bearing device according to any one of claims 1 to 6, wherein a chamfered portion formed at an inner diameter end portion of the inner ring has an arc shape, and an axial direction and a radial direction dimension thereof are approximately 1 mm. .

An annular groove is formed in the outer diameter of the end portion of the hub wheel, and the annular groove is provided so that a part of the annular groove covers a chamfered portion formed in an inner diameter end portion of the inner ring. 7. The wheel bearing device according to 7.

9. The hub ring according to claim 1, wherein the hub ring is formed of carbon steel having C of 0.45 to 0.80 wt%, and a hardened surface layer is formed at a predetermined portion by induction hardening. The wheel bearing device described.

The wheel bearing device according to any one of claims 1 to 9, wherein the inner ring is made of carbon steel having C of 0.60 to 0.80 wt% and is hardened by hardening to the core.