JP2004190734A

JP2004190734A - Rolling bearing

Info

Publication number: JP2004190734A
Application number: JP2002357237A
Authority: JP
Inventors: Takashi Murai; 隆司村井; Kenji Kotaki; 賢司小滝; Yukio Oura; 大浦　　行雄
Original assignee: NSK Ltd
Current assignee: NSK Ltd
Priority date: 2002-12-09
Filing date: 2002-12-09
Publication date: 2004-07-08

Abstract

<P>PROBLEM TO BE SOLVED: To allow easy installation of rolling elements even in a raceway integrated type and also easily allow easy installation of the rolling elements even when the integrated type raceway is assembled with a retainer in this type of rolling bearing in which spin sliding between the rolling elements and a raceway groove is suppressed and a rolling resistance is reduced to reduce torque. <P>SOLUTION: After the outer and inner rings/retainer are installed at the center of the inner ring raceway groove 3, a small groove 4 for the rotation of the rolling elements is formed in a raceway groove space. The retainer 6 is installed only on one axial pocket face of a pocket 7, and the other face is opened. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、ラジアル荷重と両方向のアキシアル荷重、モーメント荷重を受けられる軸受に関するものであり、産業機械，ロボット，医療機器，食品機械，半導体／液晶製造装置，ダイレクトドライブモータ，光学及びオプトエレクトロニクス装置などに使われる。
【０００２】
【従来の技術】
一つの軸受でラジアル荷重と両方向のアキシアル荷重，モーメント荷重を受けられるものとしては、従来、クロスローラ軸受、４点接触玉軸受及び３点接触玉軸受が知られている。
クロスローラ軸受では、転動体がころであり、転動体と軌道輪が２箇所で線接触するので、モーメント剛性大の長所を持つ。
４点接触玉軸受又は３点接触玉軸受では、転動体が玉であり、転動体と軌道輪が４箇所又は３箇所で点接触するので、低トルク、作動円滑の長所を持つ。
【０００３】
【発明が解決しようとする課題】
しかしながら、クロスローラ軸受では、モーメント剛性大という長所を持つ一方、転動体と軌道輪の間に相対速度が生じるため、ころがスキューし易く、その結果、トルク変動が生じ易い短所もある。
４点接触玉軸受又は３点接触玉軸受は、転動体が玉なので、同寸法のクロスローラよりトルクが小さい長所を持つ一方、モーメント剛性小という短所もある。また、アキシアル荷重に対してラジアル荷重が優勢な場合又は純ラジアル荷重を受ける場合、各玉は、軌道輪と４点又は３点で接触するため、玉のスピンが大きく、小さなスピン摩耗性能は得られない。
さらに、通常、スピン摩耗性能を少しでも改善するためには、軸受の隙間が正に設定されるので、結果として軸受のモーメント剛性が小さくなってしまう。
【０００４】
そこで、このような問題点を解決する新規有用な転がり軸受として特開２００１−５０２６４が提供されている。
すなわち、図８に示すように、一対の軌道輪たる外輪１００と内輪２００の間に複数の転動体４００が組み込まれ、上記各軌道輪１００，２００は転動体４００の半径より大径状の軌道面１０１，２０１からなる軌道溝３００を夫々有し、その中に少なくとも一つの軌道輪１００（２００）は二つの軌道面からなり、上記各転動体４００は転がり接触面となる外径４０１が軸方向にも曲率を持ち、円周上に夫々交互に交差状に配されると共に、各転動体４００の外径４０１が常に相対する一方の軌道輪１００（２００）の軌道面１０１（２０１）と他方の軌道輪２００の軌道面２０１（１０１）にて夫々一点ずつ合計二点で接触している構成の転がり軸受である。そして上記転動体４００の具体的な形態は、図８，９に示す通り、一組の平面部（相対面）４０２，４０２を有する上下切断状玉（玉の上下部分を切断して相対面を形成した構造のものをいう。以下本明細書において同じ。）で、外径４０１を転がり接触面としている。
特開２００１−５０２６４では、上記形態の転動体４００の姿勢を安定させるため、少なくともポケット６００の軸方向の相対する二面（軸方向案内面）６０１，６０１で拘束して案内する保持器５００を用いていた（図８・９）。しかし、この保持器５００のポケット６００に転動体４００を収めるには、事実上軸受を組み立てるときに、少なくとも外輪１００と内輪２００のいずれかを分割しなければならない。このため、組み立て時に、分割された外輪１００，１００の半径方向ずれ等を管理する必要があった。図中、７００は締結ボルトである。また、軌道輪分割構成による軸受の低コスト化が達成し難い大きな課題となっている。
また、上述のような転動体４００を用いた転がり軸受としてＤＥ４３３４１９５がある。しかし、ＤＥ４３３４１９５では、内外輪は共に一体型で構成されているが、内輪及び外輪の軌道溝には、何等この外輪と内輪で形成される溝空間内にて転動体を回転させるための特別の構成を有していない。このため、特に予圧が掛かる場合、この溝空間内で転動体を回転させることは困難で、組み立ても事実上困難と思われる。
本発明は、上述した従来技術の有するこのような問題点に鑑みなされたものであり、その目的とするところは、転動体と軌道溝とのスピン滑りの抑制と共に、転がり抵抗を低くして低トルク化を実現した転がり軸受において、軌道輪一体型であっても転動体の組み込みが容易になし得るものとすることである。
また、この種の軸受で一体型の軌道輪と保持器を組み立てた状態でも転動体の組み込みが容易になし得るものとすることである。
【０００５】
【課題を解決するための手段】
上記課題を達成するために本発明がなした技術的手段は、一対の軌道輪間に保持器を介して複数の転動体が組み込まれ、上記各軌道輪は転動体の半径より大径状の軌道面からなる軌道溝を夫々有し、その中に少なくとも一つの軌道輪は二つの軌道面からなり、上記各転動体は転がり接触面となる外径が軸方向にも曲率を持ち、円周上に夫々交互に交差状に配されると共に、各転動体の外径が常に相対する一方の軌道輪の軌道面と他方の軌道輪の軌道面にて夫々一点ずつ合計二点で接触しているものであって、一対の軌道輪は夫々一体型で形成され、該軌道輪のいずれか一方若しくは双方の軌道溝の一部には、所望深さの溝を設けたことである。
また、上記保持器は、転動体を保持する夫々のポケットが、周方向に相対する二面のポケット面を有すると共に、軸方向は一面のポケット面のみ有し、相対する面側は開放されており、該軸方向のポケット面は、互いに交差状に組み込まれる転動体の傾斜の向きに対応して、互いに軸方向の反対側に傾斜状に配列されている。転動体は、少なくとも一平面を有し、該平面が保持器の軸方向ポケット面と接する。
このような技術的手段により、転動体は、内外輪保持器を組み立てた状態でも挿入可能である。そして、挿入された転動体は、軌道溝に小さな溝を設けたことにより、軌道輪が一体型であっても、その軌道輪間で形成される溝空間内で転動体が回転可能となる。また、保持器ポケットの軸方向の片側が開放しているので、内外輪、保持器を組み込んだ状態で、片側ずつ組み込むことが可能となる。また、このような保持器構成を採用することにより、転動体の軸方向案内面が、従来の二面から一面に減少しているため、転動体を拘束する力が減少する。その結果、保持器と転動体の間に生じる端面摩擦が大幅（約半分）に小さくなるためトルクも減少する。
【０００６】
【発明の実施の形態】
以下、本発明の一実施形態を図に基いて説明する。なお、本実施形態は本発明の一実施形態にすぎず、これに限定して解釈されるものではなく本発明の範囲内で設計変更可能である。
転がり軸受Ａは、図１に開示しているように、一体型で成形された軸受軌道輪（軸受外輪）１の内径と、同じく一体型に成形された軸受軌道輪（軸受内輪）２の外径に形成される軌道溝３に、保持器６を介して複数の転動体５，５…が組み込まれて構成されている。なお、図中、８はシール溝で、本実施形態では密封板（シール・シールド）を図示省略しているが、密封板は必要に応じて適宜設けることが出来る。なお、軸受寸法・接触角・転動体径あるいは材質などの諸構成は限定されない。
本実施形態によれば、軌道輪としての外輪１と内輪２のいずれも一体型で成形されているため、締結ボルトなどの関連部品を含めた軌道輪の製作コスト・組み立て管理および組み立て費が大幅に削減できた。
軌道溝３は、転動体５の半径よりも大きな半径の軌道面１ａ・１ｂ，２ａ・２ｂにより形成されている。
また、少なくともいずれか一方の軌道輪の軌道溝が、二つの軌道面から構成されているものであればよく本発明の範囲内で適宜選択される。
各軌道面１ａ・１ｂ，２ａ・２ｂの形状は、転動体５の転がりに適切な形状を有しているものであれば、断面アーチ状あるいはＶ字状等任意で、また曲線状あるいは直線状等のいずれであってもよく特に限定されるものではないが、例えば本実施形態では、円心をクロスに配置した両円弧で形成されている、いわゆるゴシックアーチが適用される。
【０００７】
そして、内輪２の軌道溝３の一部に、この軌道溝３よりも小さな溝４を凹設している。
本実施形態では、内輪軌道面２ａ，２ｂからなる軌道溝３の中心に、周方向に連続する所望深さの断面半円状の小径（例えば溝半径は約０．８ｍｍ）な溝とする。この溝４は、転動体５の組み込み時における回転用溝として主に使用される。すなわち、後述する転動体５の転がり接触面５ａと平面部５ｂとの繋ぎ部（交点）５ｆを、組み込み時に溝４内に挿入させることによって、転動体５を軌道溝３空間内で回転可能とする。なお、溝４は、その溝４内に潤滑剤を保有させておくことも可能で、軌道面内に備えられる潤滑剤（油、グリースなど）保有機能としての作用もあり、安定した軸受寿命が期待できる。
溝４の形状・径方向深さ・軸方向幅は、軌道面を可能な限り大きく取れるように最小限の大きさにするのが好ましいが、転動体５の転がり接触面５ａと平面部５ｂとの繋ぎ部５ｆが溝４内に一部挿入可能であれば全て本発明の範囲内であり、特に図示形態に限定されず本発明の範囲内で適宜設計変更可能である。例えば４５度程度の面取り程度でもよい。
また、転動体５の周方向配設間隔を考慮すれば、溝４は所望長さをもって周方向に断続して設けてもよく本発明の範囲内である。
なお、軌道面２ａ，２ｂとの繋ぎ部２ｃのエッジを無くしＲ状に形成してもよい。
この溝４は、本実施形態では上述の通り内輪２の軌道溝３にのみ設けているが、外輪１の軌道溝３に設けてもよく、また外輪１と内輪２の双方に設けてもよい。
【０００８】
転動体５は、転がり接触面となる外径５ａが軸方向に曲率を持ち、かつ軌道面１ａ・１ｂ，２ａ・２ｂの夫々の半径よりも小径の半径を有する任意形状で、該転動体５は、隣接する転動体５が夫々交互に交差状に配されると共に、各転動体５の外径５ａが、常に一方の軌道輪１の軌道面１ａ・１ｂと他方の軌道輪２の軌道面２ｂ，２ａにて二点接触している。
転動体５は、例えば本実施形態では図３に拡大して開示しているように、一組の平面部（本実施形態では相対面）５ｂ，５ｂを有する上下切断状玉（玉の上下部分を切断して平面部５ｂ，５ｂを形成した構造のものをいう。以下同じ。）で、該平面部５ｂ，５ｂに垂直する自転中心軸５ｃが夫々交差状となるように夫々の転動体５，５…が組込まれると共に、各転動体５の外径５ａが、常に一方の軌道輪１の軌道面１ａ，１ｂと他方の軌道輪２の軌道面２ｂ，２ａにて二点接触している。図中５ｆは、転動体５の転がり接触面５ａと平面部５ｂとの繋ぎ部（交点）である。
転動体５は、その上下の切断幅は特に限定されず、また上下の切断割合は、均等あるいは均等でないものであってもよく、本発明の範囲内で任意に選択可能である。すなわち、本実施形態では、平面部５ｂ，５ｂを対称としたが、転動体５の平面部５ｂ，５ｂは、対称であっても非対称であってもよくいずれも本発明の範囲内である。
また、図４に示す非対称の平面部５ｂ，５ｄを有する転動体（上下切断状玉）５の場合、大端側の平面部５ｄが軸受の内輪２に向くように配することで、転動体５の回転がより安定になり、より低トルクを実現することができる。
転動体５の全体形状、相対面５ｂ，５ｂの有無や、外径５ａにおける軸方向の曲率の大小等は、上記具体的形状に何等限定されるものではなく、本発明の範囲内において任意に変更可能である。すなわち、例えば、平面部５ｂ，５ｂに代えて、非平行状の両面（平面部）を備え、該両面に垂直する自転中心軸を有するものとしてもよい（図示省略）。
また、図５に示す玉の片側をカット（切断）して一つの平面部（カット面）５ｅを設けた片側カット状玉としたものであってもよい。
また、平面部５ｂ（５ｄ，５ｅ）は、任意形状であって、適宜最適な形状・大きさに変更・選択できる。
【０００９】
転動体５，５…の組込みは、隣り合う転動体５，５における各平面部５ｂ・５ｂ，５ｂ・５ｂに垂直する自転中心軸５ｃ，５ｃが交互に交差状となるようにする。なお、その交差状態は直交状・非直交状のいずれでも構わない。
また、転動体５の交差状に配される方式は、両方のなりで数が同じなら、周方向に交互に配されるものでなくともよく特に限定されない。すなわち、転動体５が１ヶ毎に交差してもよく、１ヶ毎に交差しなくとも両方のなりで数が同じなら、２ヶずつ交差あるいは２ヶ１ヶ１ヶ２ヶ等のように交差していてもよくいずれも本発明の範囲内である。
【００１０】
各転動体５，５の運動は、保持器６で案内される（図２参照）。
保持器６は、転動体５を保持案内するポケット（保持部）７…が、周方向に複数個備えられた円環状に形成され、夫々のポケット７が、周方向に相対する二面のポケット面（周方向案内面）７ａ，７ａを有すると共に、軸方向は一面のポケット面（軸方向に転動体姿勢を安定させる軸方向案内面）７ｂのみ有し、相対する面側は開放（開放面）されており、該軸方向のポケット面７ｂは、互いに交差状に組み込まれる転動体５の傾斜の向きに対応して、互いに軸方向の反対側に傾斜状に配列されている。なお周方向のポケット面７ａの形状は特に限定されず任意である。
軸方向のポケット面７ｂは、転動体５の外輪対向側の平面部５ｂ（図１で左上方に向いている面）を案内するよう外径６ａから内径６ｂにわたり傾斜状に形成されている。よって、ポケット７の外径側開口７ｃより内径側開口７ｄが広く形成されることとなる。
このポケット面７ｂの傾斜角度は任意で、軌道溝３空間内で配される転動体５の角度を考慮して決定される。
本実施形態では、円周上で転動体５…数量と同一数量をもって等間隔で設けられると共に、周方向で隣り合うポケット７の軸方向ポケット面７ｂは、周方向に交互に交差状に配されており、隣り合う各転動体５，５を上述の通り平面部５ｂ・５ｂ，５ｂ・５ｂに垂直する自転中心軸５ｃ，５ｃが夫々交差状になるように交互に組み込み可能とする。
なお、本実施形態では、円周上で転動体５…数量と同一数量のポケット７…が等間隔で、かつ交互に交差状に配されているが、特に限定されず、両方のなりで数が同じなら、２ヶずつ交差あるいは２ヶ１ヶ１ヶ２ヶ等のように交差していても良く本発明の範囲内である。よって、上述した転動体５の配される方式に応じたポケット構成を周方向に設けた保持器とする。
保持器６の案内方式は特に限定されるものではなく、内輪案内でも、外輪案内でも、転動体案内でもよい。また、本実施形態では保持器６を一体型の構成としているが、特に限定されるものではなく、幾つかの部分から形成したものでも良い。
本実施形態の保持器６によれば、外輪１、内輪２と共に組み立てた後、転動体５を保持器６の開放側より軸受軌道溝３空間内へ順次挿入できる。
【００１１】
本実施形態は予圧品であるが、すきま品でもよいことは言うまでもない。
転動体と軌道面との間における予圧の付与される状態は特に限定されず、すなわち、製造段階で予圧が付与されても付与されなくてもよくいずれも本発明の範囲内である。
【００１２】
これら軸受の軌動輪１，２と転動体５の材質としては、通常軸受鋼が用いられるが、使用環境に応じて耐食性や、耐熱性を向上させる場合にはステンレス鋼やセラミック等が適宜選択される。
また保持器６の材料としては、もみ抜き保持器、プレス保持器、樹脂保持器等が適宜選択されるので、例えば黄銅や鉄等の金属や、例えばポリアミド６６（ナイロン６６）・ポリフェニレンサルファイド（ＰＰＳ）等の合成樹脂が本発明の範囲内で選ばれる。
【００１３】
この実施形態によれば、転動体５の外径５ａが相対する外輪１の軌道面１ｂと内輪２の軌道面２ａに夫々点接触（接触点を１１，１１で示す）し、隣接する転動体５が外輪１の軌道面１ａと内輪２の軌道面２ｂに夫々点接触（接触点を１２，１２で示す）する。転動体５，５の接触角交互に交差するので、一つの軸受でラジアル荷重と両方向のアキシアル荷重、モーメント荷重を受けることができる。
【００１４】
さらに、本実施形態の転がり軸受Ａは、図６に開示しているようにダイレクトドライブモータに組み込むことにより従来品に比して優れたこの種のモータが提供できる。
図６はダイレクトドライブモータの一実施形態を示す概略図で、図中１７は回転子（ロータ）、１８は固定子（ステータ）、２１はコイルを示し、回転子１７と固定子１８との間に転がり軸受Ａが組み込まれ、コイル２１に通電することにより、ロータ１７およびパルサーリング１９が回転し、パルサーリング１９の凹凸を位置検出器２０により検出し、制御器（図示しない）によって回転速度や位置決めの制御を行う構造となっている。本実施形態では、モータの外側が回転するアウターロータ型にて説明しているが、モータの内側が回転するインナーロータ型に採用しても何等問題はない。
軸受外輪１はロータ１７に嵌合され、パルサーリング１９とともに固定される。一方、軸受内輪２はコイル２１の巻かれたステータ１８側に嵌合され、位置検出器２０と共に固定されている。
本実施形態のダイレクトドライブモータは、転がり軸受Ａ構成部分を除いて従来のダイレクトドライブモータと同一の周知構成であるため、特に図示例に限定されるものではなく、他の周知構成が本発明の範囲内で適宜設計変更可能である。このように、ダイレクトドライブモータに内蔵される軸受Ａの構成を、上述の実施形態にて説明した本発明の転がり軸受とすることにより、軸受のトルクを従来のクロスローラ軸受よりも小さく出来、発熱が抑えられる。また、前記軸受に予圧を付与することにより剛性が得られる。従って、従来のダイレクトドライブモータの機能を損うこと無く、高速化が可能となる。
【００１５】
ここで、本実施形態の転がり軸受（図１実施形態品）Ａと、従来の転がり軸受（図８従来品）の軸受トルクとその変動について比較した実験結果を図７に示す。

本実験結果によれば、本実施形態軸受Ａの方が従来軸受（図８，９）よりトルクが下がることがわかった。またその軸受トルクの変動が小さいこともわかった。また、今回の試験軸受は、予圧品のため転動体が全て溝内に挿入されるためには、外輪を加熱によって膨張させ、すきまを持たせた状態で組み付けた。
なお、外輪を加熱することなく転動体を内、外輪の相対変位を利用し、直接溝に押し込んでも可能であることを確認した。但し、挿入時に転動体の転がり接触面に傷がつかないように注意が必要である。
【００１６】
【発明の効果】
本発明は、上述の通りの構成としたため次の作用効果を奏する。
▲１▼従来のように、一対の軌道輪のうちいずれか一方を少なくとも分割する構成としなくとも、転動体の組み込みがなし得るため、軌道輪の製作コスト・組み立て管理および組み立て費が大幅に削減できた。
▲２▼軌道輪のいずれもが分割構成としないため、分割構成とするときに要する締結用のボルト・リベットなどの関連部品が不要となり、部品削減が図れた。その結果、これらに要していた製作コスト・製作手間、および管理などが削減できた。
▲３▼一体型で加工された軌道輪の加工精度を損なうことなく軸受とすることができるため、軸受精度を高く維持できる。
▲４▼本発明を構成する保持器によれば、一対の軌道輪・保持器を組み立てた後に、各ポケットにおける開放側を介して軸方向から転動体を容易に組み込むことができる。
▲５▼軌道溝に設けた溝は、転動体組み込み時の転動体回転用としての機能を有すると共に、軌道面内に、油・グリースなどの潤滑剤の保有機能も有するため、安定した軸受寿命が期待できる。
【図面の簡単な説明】
【図１】本発明転がり軸受の一実施形態を一部省略して示す概略断面図。
【図２】本発明転がり軸受における保持器への転動体組み込み方向を一部省略して示す概略平面図。
【図３】本発明転がり軸受に組み込まれる転動体の一実施形態を示す斜視図。
【図４】本発明転がり軸受に組み込まれる転動体の他の実施形態を示す斜視図。
【図５】本発明転がり軸受に組み込まれる転動体の他の実施形態を示す斜視図。
【図６】ダイレクトドライブモーターに本発明転がり軸受を組み込んだ実施の一形態を一部切欠いて示す概略断面図。
【図７】本実施形態軸受と従来の軸受の軸受トルクとその変動を示す実験結果の図。
【図８】従来の転がり軸受を一部省略して示す概略断面図。
【図９】従来の転がり軸受における保持器への転動体組み込み方向を一部省略して示す概略平面図。
【符号の説明】
Ａ：転がり軸受
１：外輪
２：内輪
３：軌道溝
４：溝（回転用）
５：転動体
５ａ：外径
５ｂ：平面部
５ｆ：繋ぎ部
６：保持器
７：ポケット
７ｂ：軸方向ポケット面[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a bearing capable of receiving a radial load, an axial load in both directions, and a moment load, and includes an industrial machine, a robot, a medical device, a food machine, a semiconductor / liquid crystal manufacturing device, a direct drive motor, an optical and optoelectronic device, and the like. Used for
[0002]
[Prior art]
Conventionally, as a bearing capable of receiving a radial load, an axial load and a moment load in both directions, a cross roller bearing, a four-point contact ball bearing and a three-point contact ball bearing are known.
In the cross roller bearing, the rolling element is a roller, and the rolling element and the race ring are in line contact with each other at two places, so that the advantage of large moment rigidity is obtained.
In a four-point contact ball bearing or a three-point contact ball bearing, the rolling element is a ball, and the rolling element and the bearing ring make point contact at four or three points, so that they have advantages of low torque and smooth operation.
[0003]
[Problems to be solved by the invention]
However, the cross roller bearing has an advantage of high moment rigidity, but has a disadvantage that the relative speed is generated between the rolling element and the bearing ring, so that the rollers are easily skewed, and as a result, torque fluctuation is apt to occur.
The four-point contact ball bearing or the three-point contact ball bearing has the advantage that the torque is smaller than the cross roller of the same size because the rolling element is a ball, but also has the disadvantage that the moment rigidity is small. Also, when the radial load is dominant over the axial load or when a pure radial load is received, each ball contacts the raceway at four or three points, so that the ball has large spin and small spin wear performance is obtained. I can't.
Further, usually, in order to improve the spin wear performance even a little, the gap of the bearing is set to be positive, and as a result, the moment rigidity of the bearing is reduced.
[0004]
Therefore, Japanese Patent Application Laid-Open No. 2001-50264 is provided as a new and useful rolling bearing that solves such a problem.
That is, as shown in FIG. 8, a plurality of rolling elements 400 are incorporated between an outer ring 100 and an inner ring 200 as a pair of races, and each of the

races

100 and 200 has a raceway having a diameter larger than the radius of the rolling body 400. Each has a raceway groove 300 composed of

surfaces

101 and 201, in which at least one raceway ring 100 (200) is composed of two raceway surfaces, and each of the rolling elements 400 has an outer diameter 401 serving as a rolling contact surface. The rolling element 400 also has a curvature in the direction, and is alternately arranged on the circumference so as to cross each other, and the outer diameter 401 of each rolling element 400 is always opposed to the raceway surface 101 (201) of one raceway 100 (200). The rolling bearing has a configuration in which two points are in contact with each other on the raceway surface 201 (101) of the other raceway 200. As shown in FIGS. 8 and 9, a specific form of the rolling element 400 is a vertically cut ball having a pair of flat portions (relative surfaces) 402, 402 (cutting the upper and lower portions of the ball to form a relative surface). The outer diameter 401 is used as a rolling contact surface.
In Japanese Patent Application Laid-Open No. 2001-50264, in order to stabilize the posture of the rolling element 400 of the above-described configuration, the cage 500 that guides the pocket 600 by restricting and guiding it with at least two opposing surfaces (axial guide surfaces) 601 and 601 in the axial direction. (Figs. 8 and 9). However, in order to fit the rolling element 400 in the pocket 600 of the retainer 500, at least one of the outer ring 100 and the inner ring 200 must be divided when the bearing is assembled. For this reason, at the time of assembling, it is necessary to manage the deviation of the divided

outer races

100, 100 in the radial direction. In the figure, reference numeral 700 denotes a fastening bolt. Further, there is a major problem that it is difficult to reduce the cost of the bearing by the raceway ring split configuration.
Further, as a rolling bearing using the rolling element 400 as described above, there is DE 4334195. However, in DE 4 334 195, the inner and outer rings are both integrally formed, but the inner and outer raceways have special raceways for rotating the rolling elements in the groove space formed by the outer and inner races. No configuration. For this reason, especially when a preload is applied, it is difficult to rotate the rolling element in this groove space, and it is considered that assembly is practically difficult.
SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the related art, and has as its object to suppress the spin sliding between a rolling element and a raceway groove and to reduce the rolling resistance to reduce the rolling resistance. It is an object of the present invention to make it possible to easily incorporate a rolling element in a rolling bearing that realizes torque, even if the rolling bearing is of an integral type.
Another object of the present invention is to make it possible to easily incorporate a rolling element even in a state where an integrated race and a retainer are assembled with this type of bearing.
[0005]
[Means for Solving the Problems]
Technical means achieved by the present invention to achieve the above object is that a plurality of rolling elements are incorporated via a retainer between a pair of races, and each of the races has a larger diameter than the radius of the rolling bodies. Each has a raceway groove formed of a raceway surface, and at least one raceway ring has two raceway surfaces therein, and each of the rolling elements has an outer diameter serving as a rolling contact surface also having a curvature in the axial direction, and a circumferential surface. The rolling elements are arranged alternately in an intersecting manner, and the outer diameters of the rolling elements are always in contact with each other at one point on the raceway surface of one raceway and the raceway surface of the other raceway at a total of two points. That is, the pair of races are formed integrally, and a groove of a desired depth is provided in one or both raceways of the race.
Further, in the retainer, each pocket holding the rolling element has two pocket surfaces facing each other in the circumferential direction, has only one pocket surface in the axial direction, and the facing surface side is open. The pocket surfaces in the axial direction are arranged obliquely on opposite sides in the axial direction so as to correspond to the inclination directions of the rolling elements incorporated into each other in an intersecting manner. The rolling element has at least one plane, which is in contact with the axial pocket surface of the cage.
By such technical means, the rolling elements can be inserted even when the inner and outer race retainers are assembled. Since the inserted rolling element has a small groove in the raceway groove, the rolling element can rotate in the groove space formed between the raceways even if the raceway is integral. Also, since one side in the axial direction of the retainer pocket is open, it is possible to incorporate the inner and outer rings and the retainer one by one in a state of being incorporated. Further, by adopting such a retainer configuration, the axial guide surface of the rolling element is reduced from the conventional two surfaces to one surface, so that the force for restraining the rolling element is reduced. As a result, the end face friction generated between the retainer and the rolling element is significantly (about half) reduced, so that the torque is also reduced.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that this embodiment is merely an embodiment of the present invention, and is not to be construed as being limited to the embodiment, and the design can be changed within the scope of the present invention.
As disclosed in FIG. 1, the rolling bearing A has an inner diameter of an integrally formed bearing race ring (bearing outer ring) 1 and an outer periphery of a similarly integrally formed bearing race ring (bearing inner ring) 2. A plurality of

rolling elements

5, 5,... Are assembled via a retainer 6 into a raceway groove 3 formed in a diameter. In the drawings, reference numeral 8 denotes a seal groove. Although a sealing plate (seal / shield) is not shown in the present embodiment, the sealing plate can be appropriately provided as needed. Various configurations such as bearing dimensions, contact angles, rolling element diameters, and materials are not limited.
According to the present embodiment, since both the outer ring 1 and the inner ring 2 as the race rings are integrally formed, the production cost, the assembly management and the assembly cost of the race rings including the related parts such as the fastening bolts are large. Was reduced to
The raceway groove 3 is formed by

raceway surfaces

1 a and 1 b and 2 a and 2 b having a radius larger than the radius of the rolling element 5.
In addition, it is sufficient that at least one of the raceways has a raceway groove composed of two raceway surfaces, and is appropriately selected within the scope of the present invention.
The shape of each

raceway surface

1a, 1b, 2a, 2b is arbitrary, such as a cross-section arch shape or a V-shape, as long as it has a shape suitable for rolling of the rolling element 5, and a curved or linear shape. For example, in the present embodiment, a so-called Gothic arch, which is formed by two arcs each having a circular center arranged in a cross, is applied.
[0007]
A groove 4 smaller than the raceway groove 3 is recessed in a part of the raceway groove 3 of the inner race 2.
In the present embodiment, a groove having a semicircular cross-section (for example, a groove radius of about 0.8 mm) having a desired depth in a circumferential direction and having a desired depth is formed at the center of the raceway groove 3 formed by the

inner raceway surfaces

2a and 2b. The groove 4 is mainly used as a groove for rotation when the rolling element 5 is assembled. In other words, by inserting a connecting portion (intersection) 5f between the rolling contact surface 5a of the rolling element 5 and the plane portion 5b, which will be described later, into the groove 4 at the time of assembly, the rolling element 5 can be rotated in the space of the raceway groove 3. I do. In addition, the groove 4 can hold a lubricant in the groove 4 and also has a function of holding a lubricant (oil, grease, etc.) provided in the raceway surface, so that a stable bearing life is provided. Can be expected.
The shape, radial depth and axial width of the groove 4 are preferably minimized so that the raceway surface can be as large as possible, but the rolling contact surface 5a of the rolling element 5 and the flat portion 5b If the connecting portion 5f can be partially inserted into the groove 4, it is entirely within the scope of the present invention, and the design is not particularly limited to the illustrated embodiment but can be appropriately changed within the scope of the present invention. For example, a chamfer of about 45 degrees may be used.
Further, in consideration of the interval between the rolling elements 5 in the circumferential direction, the grooves 4 may be provided in the circumferential direction with a desired length, which is within the scope of the present invention.
The edge of the connecting portion 2c with the raceway surfaces 2a and 2b may be formed in an R shape without the edge.
In this embodiment, the groove 4 is provided only in the raceway groove 3 of the inner ring 2 as described above, but may be provided in the raceway groove 3 of the outer ring 1 or may be provided in both the outer ring 1 and the inner ring 2. .
[0008]
The rolling element 5 has an arbitrary shape in which an outer diameter 5a serving as a rolling contact surface has a curvature in the axial direction and a radius smaller than the radius of each of the

raceway surfaces

1a, 1b, 2a, 2b. Is that the rolling elements 5 adjacent to each other are alternately arranged in an intersecting manner, and the outer diameter 5a of each rolling element 5 is always the

raceway surface

1a, 1b of one raceway 1 and the raceway surface of the other raceway 2 Two-point contact is made at 2b and 2a.
The rolling element 5 is, for example, a vertically cut ball (a vertical part of a ball) having a pair of flat portions (relative surfaces in the present embodiment) 5b, 5b as disclosed in this embodiment in an enlarged manner in FIG. Are cut to form

flat portions

5b, 5b. The same applies to the following.), And each rolling element 5 is arranged such that a rotation center axis 5c perpendicular to the

flat portions

5b, 5b crosses each other. , 5... And the outer diameter 5a of each rolling element 5 is always in two-point contact with the

raceway surfaces

1a, 1b of one raceway 1 and the

raceway surfaces

2b, 2a of the other raceway 2. . In the figure, reference numeral 5f denotes a connecting portion (intersection) between the rolling contact surface 5a of the rolling element 5 and the flat portion 5b.
The upper and lower cutting widths of the rolling element 5 are not particularly limited, and the upper and lower cutting ratios may be equal or unequal, and can be arbitrarily selected within the scope of the present invention. That is, in the present embodiment, the

plane portions

5b, 5b are symmetric, but the

plane portions

5b, 5b of the rolling element 5 may be symmetric or asymmetric, and both are within the scope of the present invention.
In the case of a rolling element (vertical cut ball) 5 having asymmetrical

flat parts

5b and 5d shown in FIG. 4, the rolling element is arranged such that the large end side flat part 5d faces the inner ring 2 of the bearing. 5 is more stable, and lower torque can be realized.
The overall shape of the rolling element 5, the presence or absence of the

relative surfaces

5b, 5b, and the magnitude of the axial curvature at the outer diameter 5a are not limited to the above-described specific shapes, and may be arbitrarily set within the scope of the present invention. Can be changed. That is, for example, instead of the

plane portions

5b, 5b, non-parallel surfaces (plane portions) may be provided, and a rotation center axis perpendicular to the both surfaces may be provided (not shown).
Alternatively, one side of the ball shown in FIG. 5 may be cut (cut) to form a one-side cut ball provided with one flat portion (cut surface) 5e.
The flat portion 5b (5d, 5e) has an arbitrary shape, and can be appropriately changed and selected to an optimum shape and size.
[0009]
The rolling

elements

5, 5,... Are assembled so that the rotation center axes 5c, 5c perpendicular to the

plane portions

5b, 5b, 5b, 5b of the

adjacent rolling elements

5, 5 alternately cross each other. The crossing state may be either orthogonal or non-orthogonal.
In addition, the method of arranging the rolling elements 5 in an intersecting manner is not particularly limited, as long as the numbers are the same in both cases, as long as they are not alternately arranged in the circumferential direction. That is, the rolling elements 5 may intersect one by one, and if they do not intersect one by one, and if the numbers are the same in both cases, they intersect two by two or two by one or two. They may intersect and all are within the scope of the present invention.
[0010]
The movement of each rolling

element

5, 5 is guided by a retainer 6 (see FIG. 2).
The cage 6 has a plurality of pockets (holding portions) 7 for holding and guiding the rolling elements 5 formed in an annular shape having a plurality of circumferentially arranged pockets. Surfaces (circumferential guide surfaces) 7a, 7a, and has only one pocket surface (axial guide surface for stabilizing the rolling element posture in the axial direction) 7b in the axial direction, and the opposite surface side is open (open surface). ), And the pocket surfaces 7b in the axial direction are arranged obliquely on opposite sides in the axial direction so as to correspond to the inclination directions of the rolling elements 5 incorporated into each other in an intersecting manner. The shape of the pocket surface 7a in the circumferential direction is not particularly limited and is arbitrary.
The axial pocket surface 7b is formed so as to be inclined from the outer diameter 6a to the inner diameter 6b so as to guide the flat portion 5b (the surface facing upward and left in FIG. 1) of the rolling element 5 on the outer ring facing side. Therefore, the inner diameter side opening 7d is formed wider than the outer diameter side opening 7c of the pocket 7.
The inclination angle of the pocket surface 7b is arbitrarily determined in consideration of the angle of the rolling elements 5 disposed in the space of the raceway groove 3.
In this embodiment, the same number of rolling elements 5 as the number of rolling elements 5 are provided on the circumference at equal intervals, and the axial pocket surfaces 7b of the pockets 7 adjacent in the circumferential direction are alternately arranged in the circumferential direction so as to intersect. As described above, the rolling elements 5 adjacent to each other can be alternately assembled such that the rotation center axes 5c, 5c perpendicular to the

plane portions

5b, 5b, 5b, 5b cross each other.
In the present embodiment, the same number of the rolling elements 5 as the number of the pockets 7 are arranged at regular intervals and alternately in an intersecting manner on the circumference. However, the number of the pockets 7 is not particularly limited. If they are the same, they may intersect each other, such as two by two or two by one, which is within the scope of the present invention. Therefore, a cage provided in the circumferential direction has a pocket configuration corresponding to the method of disposing the rolling elements 5 described above.
The guide system of the retainer 6 is not particularly limited, and may be inner ring guide, outer ring guide, or rolling element guide. Further, in the present embodiment, the retainer 6 has an integral structure, but the retainer 6 is not particularly limited and may be formed from several parts.
According to the cage 6 of the present embodiment, after assembling with the outer ring 1 and the inner ring 2, the rolling elements 5 can be sequentially inserted into the space of the bearing raceway groove 3 from the open side of the cage 6.
[0011]
Although the present embodiment is a preload product, it goes without saying that a clearance product may be used.
The state in which the preload is applied between the rolling element and the raceway surface is not particularly limited, that is, the preload may or may not be applied in the manufacturing stage, and both are within the scope of the present invention.
[0012]
Usually, bearing steel is used as a material for the

orbital wheels

1 and 2 and the rolling elements 5 of these bearings. To improve corrosion resistance and heat resistance according to the use environment, stainless steel, ceramic, and the like are appropriately selected. You.
As the material of the retainer 6, an extruded retainer, a press retainer, a resin retainer, and the like are appropriately selected. For example, a metal such as brass or iron, or a polyamide 66 (nylon 66) / polyphenylene sulfide (PPS) is used. ) Are selected within the scope of the present invention.
[0013]
According to this embodiment, the outer diameter 5a of the rolling element 5 makes point contact with the raceway surface 1b of the outer race 1 and the raceway surface 2a of the inner race 2 (points of contact are indicated by 11 and 11), respectively. 5 makes point contact with the raceway surface 1a of the outer race 1 and the raceway surface 2b of the inner race 2 (contact points are indicated by 12 and 12). Since the contact angles of the rolling

elements

5 and 5 intersect alternately, a single bearing can receive a radial load and an axial load and a moment load in both directions.
[0014]
Further, by incorporating the rolling bearing A of the present embodiment into a direct drive motor as disclosed in FIG. 6, a motor of this type which is superior to a conventional product can be provided.
FIG. 6 is a schematic view showing an embodiment of a direct drive motor, in which 17 is a rotor (rotor), 18 is a stator (stator), 21 is a coil, and a portion between the rotor 17 and the stator 18 is shown. When the coil 21 is energized, the rotor 17 and the pulsar ring 19 rotate, and the unevenness of the pulsar ring 19 is detected by the position detector 20, and the rotation speed and the rotation speed are controlled by a controller (not shown). It has a structure to control positioning. In the present embodiment, the outer rotor type in which the outside of the motor rotates is described, but there is no problem if the inner rotor type in which the inside of the motor rotates is adopted.
The bearing outer ring 1 is fitted to the rotor 17 and fixed together with the pulsar ring 19. On the other hand, the bearing inner ring 2 is fitted on the stator 18 side on which the coil 21 is wound, and is fixed together with the position detector 20.
The direct drive motor of the present embodiment has the same well-known configuration as the conventional direct drive motor except for the rolling bearing A component, and is not particularly limited to the illustrated example. The design can be appropriately changed within the range. As described above, the configuration of the bearing A incorporated in the direct drive motor is the rolling bearing of the present invention described in the above-described embodiment, so that the torque of the bearing can be made smaller than that of the conventional cross roller bearing, and heat generation can be achieved. Is suppressed. Further, rigidity can be obtained by applying a preload to the bearing. Therefore, the speed can be increased without impairing the function of the conventional direct drive motor.
[0015]
Here, FIG. 7 shows an experimental result comparing the bearing torque of the rolling bearing A of the present embodiment (the product of the embodiment of FIG. 1) A with the conventional rolling bearing (the conventional product of FIG. 8) and its fluctuation.

According to the results of this experiment, it was found that the torque of the bearing A of the present embodiment was lower than that of the conventional bearing (FIGS. 8 and 9). It was also found that the fluctuation of the bearing torque was small. In addition, in order to insert all the rolling elements into the groove for the preloaded product, the test bearing of this test was assembled with the outer ring expanded by heating and with a clearance.
In addition, it was confirmed that the rolling element can be directly pushed into the groove using the relative displacement of the inner and outer rings without heating the outer ring. However, care must be taken so that the rolling contact surface of the rolling element is not damaged during insertion.
[0016]
【The invention's effect】
The present invention has the following functions and effects due to the configuration described above.
(1) Unlike the conventional case, the rolling element can be incorporated without having to split at least one of the pair of races, so that the production cost, the assembly management and the assembly cost of the race are greatly reduced. did it.
{Circle around (2)} Since none of the races has a split configuration, related parts such as fastening bolts and rivets required for the split configuration are not required, and the number of components can be reduced. As a result, the production cost, production labor, management, and the like required for these were reduced.
{Circle over (3)} Since the bearing can be formed without impairing the processing accuracy of the raceway formed integrally, the bearing accuracy can be maintained high.
(4) According to the retainer constituting the present invention, after assembling the pair of races / retainers, the rolling elements can be easily incorporated from the axial direction through the open side of each pocket.
(5) The groove provided in the raceway groove has the function of rotating the rolling element when the rolling element is incorporated, and also has the function of retaining lubricant such as oil and grease in the raceway surface, so that the stable bearing life Can be expected.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing a rolling bearing according to an embodiment of the present invention with a part thereof omitted;
FIG. 2 is a schematic plan view showing the rolling bearing of the present invention with a partly omitted illustration of a direction in which rolling elements are incorporated into a cage.
FIG. 3 is a perspective view showing one embodiment of a rolling element incorporated in the rolling bearing of the present invention.
FIG. 4 is a perspective view showing another embodiment of the rolling element incorporated in the rolling bearing of the present invention.
FIG. 5 is a perspective view showing another embodiment of the rolling element incorporated in the rolling bearing of the present invention.
FIG. 6 is a schematic sectional view showing an embodiment in which the rolling bearing of the present invention is incorporated in a direct drive motor, with a part cut away.
FIG. 7 is a graph of experimental results showing bearing torques of the bearing of the present embodiment and a conventional bearing and their fluctuations.
FIG. 8 is a schematic cross-sectional view partially showing a conventional rolling bearing.
FIG. 9 is a schematic plan view partially showing a direction in which rolling elements are incorporated into a cage in a conventional rolling bearing.
[Explanation of symbols]
A: Rolling bearing 1: Outer ring 2: Inner ring 3: Track groove 4: Groove (for rotation)
5: rolling element 5a: outer diameter 5b: flat portion 5f: connecting portion 6: retainer 7: pocket 7b: axial pocket surface

Claims

A plurality of rolling elements are incorporated via a retainer between a pair of races,
Each of the races has a raceway groove having a raceway surface having a diameter larger than the radius of the rolling element,
In which at least one orbit consists of two raceways,
Each of the rolling elements has an outer diameter serving as a rolling contact surface also has a curvature in the axial direction, and is alternately arranged on the circumference in an alternating manner.
The outer diameter of each rolling element is always in contact with the raceway surface of one raceway and the raceway surface of the other raceway, each of which is in contact with the raceway surface at a total of two points.
Each of the pair of bearing rings is integrally formed,
A rolling bearing characterized in that a groove of a desired depth is provided in a part of one or both raceways of the race.

In each of the pockets for holding the rolling elements, the retainer has only one axial pocket surface, and the opposite surface side is open, and the axial pocket surfaces are assembled so as to intersect with each other in the circumferential direction. The rolling bearing according to claim 1, wherein the rolling bearings are arranged in an inclined manner on opposite sides of the axial direction in correspondence with the inclination direction of the rolling elements.

3. The rolling bearing according to claim 2, wherein the rolling element has at least one flat portion, and the flat portion contacts an axial pocket surface of the retainer.