JP2024032356A - rolling bearing - Google Patents
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- JP2024032356A JP2024032356A JP2022135965A JP2022135965A JP2024032356A JP 2024032356 A JP2024032356 A JP 2024032356A JP 2022135965 A JP2022135965 A JP 2022135965A JP 2022135965 A JP2022135965 A JP 2022135965A JP 2024032356 A JP2024032356 A JP 2024032356A
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- 238000005096 rolling process Methods 0.000 title claims abstract description 124
- 238000010586 diagram Methods 0.000 claims abstract description 13
- 230000007935 neutral effect Effects 0.000 claims abstract description 7
- 230000002093 peripheral effect Effects 0.000 abstract description 13
- 230000000052 comparative effect Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002347 injection Methods 0.000 description 3
- 239000007924 injection Substances 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 2
- 238000005520 cutting process Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000004308 accommodation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- FXNGWBDIVIGISM-UHFFFAOYSA-N methylidynechromium Chemical group [Cr]#[C] FXNGWBDIVIGISM-UHFFFAOYSA-N 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000036316 preload Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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Abstract
Description
本発明は、転がり軸受に関し、特に、いわゆる軌道輪案内型の転がり軸受に関する。 The present invention relates to a rolling bearing, and in particular to a so-called raceway guided rolling bearing.
径方向に対向配置された状態で複数の転動体を介して相対回転する一対の軌道輪（内輪及び外輪）と、複数の転動体を周方向に間隔を空けて保持する環状の保持器と、を備えた転がり軸受において、保持器は、通常、径方向及び周方向に移動可能な状態で内外輪間に組み込まれる。従って、中立位置に位置する保持器は、各軌道輪との間に径方向すきまを形成すると共に、転動体の収容部（ポケット）に収容された転動体との間に径方向すきま及び周方向すきまを形成する。軌道輪と保持器の間の径方向すきまは「案内すきま」と、また、ポケットの内面と転動体の間の径方向すきま及び周方向すきまはそれぞれ「ポケット径方向すきま」及び「ポケット周方向すきま」とも称される。但し、例えばポケットの形状が径方向に一様な保持器を採用した転がり軸受では「ポケット径方向すきま」が存在しない（ポケット径方向すきまは無限大となる）。 A pair of bearing rings (inner ring and outer ring) that are arranged to face each other in the radial direction and rotate relative to each other via a plurality of rolling elements, and an annular retainer that holds the plurality of rolling elements at intervals in the circumferential direction; In a rolling bearing equipped with a cage, the cage is usually installed between the inner and outer rings in a manner movable in the radial and circumferential directions. Therefore, the cage located at the neutral position forms a radial clearance with each bearing ring, and a radial clearance and a circumferential clearance with the rolling elements accommodated in the rolling element accommodation portions (pockets). Form a gap. The radial clearance between the raceway ring and the cage is called the "guide clearance," and the radial and circumferential clearances between the inner surface of the pocket and the rolling elements are called the "pocket radial clearance" and "pocket circumferential clearance," respectively. ” is also called. However, for example, in a rolling bearing that uses a cage in which the pocket shape is uniform in the radial direction, there is no "pocket radial clearance" (the pocket radial clearance is infinite).
転がり軸受は、「転動体案内型」と「軌道輪案内型」とに大別される。転動体案内型の転がり軸受では、ポケット径方向すきまが案内すきまよりも小さく、保持器の径方向移動がポケットの内面（ポケット面）と転動体の接触により制限されることから、保持器と軌道輪が接触することはない。一方、軌道輪案内型の転がり軸受は、案内すきまがポケット径方向すきまよりも小さい転がり軸受である。軌道輪案内型の転がり軸受のうち、案内すきまがポケット周方向すきまより小さい場合、保持器が中立位置から径方向に移動すると、最初に軌道輪と接触する。案内すきまがポケット周方向すきまより大きい場合は、転動体の配置が等配であれば、保持器が径方向に移動したときに最初に転動体と接触するが、転動体の配置が等配からずれると保持器の可動範囲が変わるため、軌道輪と接触することもあり得る。転がり軸受を転動体案内型又は軌道輪案内型の何れにするか（保持器の案内形式を転動体案内又は軌道輪案内の何れにするか）は、転がり軸受の用途等に応じて適宜選択される。 Rolling bearings are broadly classified into "rolling element guided type" and "race ring guided type." In rolling element-guided rolling bearings, the pocket radial clearance is smaller than the guiding clearance, and the radial movement of the cage is limited by the contact between the inner surface of the pocket (pocket surface) and the rolling elements. The rings never touch. On the other hand, a ring guided rolling bearing is a rolling bearing in which the guiding clearance is smaller than the pocket radial clearance. In a ring-guided rolling bearing, when the guide clearance is smaller than the pocket circumferential clearance, when the cage moves radially from the neutral position, it first comes into contact with the bearing ring. If the guide clearance is larger than the pocket circumferential clearance, if the rolling elements are arranged evenly, the cage will first contact the rolling elements when it moves in the radial direction, but if the rolling elements are arranged evenly If the cage is misaligned, the range of motion of the cage changes, so it may come into contact with the raceway. Whether the rolling bearing is a rolling element guided type or raceway ring guided type (whether the cage is guided by rolling elements or raceway rings) is selected as appropriate depending on the application of the rolling bearing. Ru.
軌道輪案内型の転がり軸受の作動時（内輪と外輪の相対回転時）には、保持器と軌道輪（内輪又は外輪）の接触に伴って生じる摩擦力により、異音、振動、トルクの増大などの不具合、さらには保持器の破断等の致命的な不具合の発生要因である保持器の高速振れ回り現象（高速ホワール現象）が発生することがある。 When ring-guided rolling bearings operate (during relative rotation between the inner ring and outer ring), the frictional force generated due to the contact between the cage and the ring (inner ring or outer ring) may cause noise, vibration, and increased torque. A high-speed whirling phenomenon of the cage may occur, which is a cause of fatal defects such as breakage of the cage.
そこで、例えば下記の特許文献１においては、保持器に所定のアンバランス量を与えることで保持器を偏心回転可能とし、回転中の保持器の一部を外輪又は転動体に常時接触させることにより、高速ホワール現象の発生、さらにはこれに起因した異音・振動等の不具合発生を可及的に防止するようにしている。 Therefore, for example, in Patent Document 1 below, the cage is made eccentrically rotatable by giving the cage a predetermined unbalance amount, and a part of the rotating cage is kept in constant contact with the outer ring or the rolling elements. , the occurrence of high-speed whirl phenomena, as well as the occurrence of problems such as abnormal noises and vibrations caused by this phenomenon, are prevented as much as possible.
しかしながら、特許文献１に記載されている、高速ホワール現象の発生を防止するための技術手段は、保持器の案内方式として内輪案内方式を採用する転がり軸受には適さないとされており（同文献の段落００３６を参照）、実質的には、軌道輪案内方式のうち外輪案内方式の転がり軸受にしか適用することができない。また、特許文献１に記載されている技術手段は、回転数の増加に伴い接触部の接触面圧が上昇し易いことから、軸受のピッチ円直径［ｍｍ］と回転数［ｒｐｍ］の積で表されるｄｍｎ値が所定値を超えるような高速回転タイプの転がり軸受には適さない、とされている。しかしながら、高速ホワール現象は、特許文献１に記載の技術手段の適用が難しいとされている転がり軸受、すなわち内輪案内方式の転がり軸受や、軌道輪案内方式でかつ高速回転タイプの転がり軸受においても生じ得る。 However, the technical means for preventing the occurrence of the high-speed whirl phenomenon described in Patent Document 1 is said to be unsuitable for rolling bearings that adopt an inner ring guide system as the cage guide system (Patent Document 1). (Refer to paragraph 0036), it can be practically applied only to outer ring guide type rolling bearings among raceway ring guide types. In addition, the technical means described in Patent Document 1 is based on the product of the pitch circle diameter [mm] of the bearing and the rotation speed [rpm], since the contact surface pressure of the contact portion tends to increase as the rotation speed increases. It is said that it is not suitable for high-speed rotation type rolling bearings in which the expressed dmn value exceeds a predetermined value. However, the high-speed whirl phenomenon also occurs in rolling bearings for which it is difficult to apply the technical means described in Patent Document 1, that is, inner ring guide type rolling bearings and raceway ring guided type rolling bearings that rotate at high speed. obtain.
係る実情に鑑み、本発明は、高速ホワール現象の発生を可及的に防止することができる軌道輪案内型の転がり軸受を提供することを目的とする。 In view of the above circumstances, an object of the present invention is to provide a raceway-guided rolling bearing that can prevent the occurrence of high-speed whirl phenomena as much as possible.
前述したとおり、軌道輪案内型の転がり軸受では、保持器の径方向移動が、軌道輪（の案内面）と保持器（の被案内面）の接触により制限されることから、案内面及び被案内面の形状等に基づいて幾何学的に保持器中心が存在できる領域、換言すると、保持器が軌道輪（案内輪）と接触することなく移動できる領域（以下、この領域を「保持器可動領域」と言う。）をシミュレーションにより推定することができる。そして、本発明者らが鋭意検討を重ねた結果、高速ホワール現象が発生すると認められる解析条件においては、保持器可動領域の形状が真円形に近づくほど高速ホワール現象が発生し易く、これとは逆に、保持器可動領域の形状が、円形（真円形）から乖離する「いびつな形状」になるほど、高速ホワール現象が発生し難くなることを見出した。本発明は、係る知見に基づいて創案されたものである。 As mentioned above, in raceway-guided rolling bearings, the radial movement of the cage is limited by the contact between (the guide surface of) the raceway and (the guided surface of) the cage. An area where the center of the cage can exist geometrically based on the shape of the guide surface, etc. In other words, an area where the cage can move without contacting the bearing ring (guide ring) (hereinafter, this area is referred to as "cage movable") (referred to as "region") can be estimated by simulation. As a result of intensive studies by the present inventors, it has been found that under analytical conditions in which high-speed whirl phenomenon is recognized to occur, the closer the shape of the cage movable region becomes to a perfect circle, the more likely high-speed whirl phenomenon occurs. On the contrary, it has been found that the more the cage movable region has a "distorted shape" that deviates from a circular shape (a perfect circle), the more difficult the high-speed whirl phenomenon is to occur. The present invention was created based on such knowledge.
すなわち、上記の目的を達成するために創案された本発明は、複数の転動体を介して相対回転する内輪及び外輪と、転動体を個別に収容した複数のポケットが周方向に間隔を空けて設けられた保持器と、を備え、保持器が、内輪の外周面又は外輪の内周面に設けられた環状の案内面に案内される環状の被案内面を有し、上記案内面と上記被案内面の間に形成される径方向すきまが、保持器のポケット内面と転動体の間に形成される径方向すきまよりも小さい転がり軸受において、中立位置に位置している保持器が内輪、外輪及び転動体と接触せずに存在可能な位置を、二次元座標上に無数にプロットすることで得られる散布図の外縁部を繋ぐ線で囲まれた領域を保持器可動領域と定義したとき、この保持器可動領域の最小外接円径Ｒｅに対する保持器可動領域の最大内接円径Ｒｉの比Ｒｉ／Ｒｅが０．９９０未満であることを特徴とする。 That is, the present invention, which was created to achieve the above object, has an inner ring and an outer ring that rotate relative to each other via a plurality of rolling elements, and a plurality of pockets each housing the rolling elements at intervals in the circumferential direction. a retainer provided, the retainer having an annular guided surface guided by an annular guide surface provided on the outer circumferential surface of the inner ring or the inner circumferential surface of the outer ring, the guide surface and the above In a rolling bearing in which the radial clearance formed between the guided surfaces is smaller than the radial clearance formed between the inner surface of the pocket of the cage and the rolling elements, the cage in the neutral position When the cage movable area is defined as the area surrounded by the line connecting the outer edges of the scatter diagram obtained by plotting an infinite number of positions that can exist without contacting the outer ring and rolling elements on two-dimensional coordinates. , the ratio Ri/Re of the maximum circumscribed circle diameter Ri of the cage movable region to the minimum circumscribed circle diameter Re of the cage movable region is less than 0.990.
上記の比Ｒｉ／Ｒｅが０．９９０未満であるということは、保持器可動領域の形状が、真円形状から乖離したいびつな形状であることを意味する。そのため、上記構成を有する転がり軸受は、本発明者らの検証結果から、高速ホワール現象の発生を効果的に防止することができる。なお、保持器可動領域の形状をいびつな形状とすることが高速ホワール現象の発生防止に有効である詳細理由を断定することはできないものの、保持器可動領域がいびつな形状になることによって案内面と被案内面の接触時に生じる摩擦力の方向が円軌道から外れ、保持器の振れ回り運動を継続的に加速させることができなくなったためであると推察される。言い換えれば、高速ホワール現象を発生させるには、保持器に作用する力の向きが時計の針のように回転し、常に円運動の加速度として働く必要があり、可動領域の形状をいびつにすればこの作用を妨げることができるものと推察される。 The fact that the ratio Ri/Re is less than 0.990 means that the shape of the retainer movable region is a distorted shape that deviates from a perfect circular shape. Therefore, the rolling bearing having the above configuration can effectively prevent the occurrence of high-speed whirl phenomenon, based on the verification results of the present inventors. It should be noted that although it is not possible to determine the detailed reason why making the cage movable region in an irregular shape is effective in preventing the occurrence of high-speed whirl, the guide surface It is presumed that this is because the direction of the frictional force generated when the guide surface contacts the cage deviates from the circular orbit, making it impossible to continuously accelerate the whirling motion of the cage. In other words, in order to generate a high-speed whirl phenomenon, the direction of the force acting on the retainer must rotate like the hands of a clock and always act as an acceleration of circular motion, and if the shape of the movable region is distorted, It is presumed that this effect can be prevented.
また、本発明で採用する技術手段は、特許文献１で提案されている技術手段のように保持器のアンバランスを意図的に増加させようとするものではないことから、本発明を転がり軸受（特に軌道輪案内型の転がり軸受）に適用してもアンバランスに起因する遠心力の増加や軸のＮＲＲＯの増加の懸念はない。このため、本発明は軌道輪案内型の転がり軸受に広く適用することができる。 Furthermore, since the technical means adopted in the present invention does not intentionally increase the unbalance of the cage like the technical means proposed in Patent Document 1, the present invention can be applied to rolling bearings ( In particular, even when applied to ring-guided rolling bearings, there is no concern about an increase in centrifugal force due to unbalance or an increase in NRRO of the shaft. Therefore, the present invention can be widely applied to raceway guided rolling bearings.
外輪の内周面に案内面が設けられると共に保持器の外周面に被案内面が設けられる場合には、例えば、転がり軸受の軸心に沿って延びる軸平行平面と平行なストレート部を上記被案内面に設けることにより、上記の比Ｒｉ／Ｒｅを０．９９０未満とすることができる。 When a guiding surface is provided on the inner circumferential surface of the outer ring and a guided surface is provided on the outer circumferential surface of the cage, for example, the straight portion parallel to the axis-parallel plane extending along the axis of the rolling bearing is By providing it on the guide surface, the above ratio Ri/Re can be made less than 0.990.
内輪の外周面に案内面が設けられると共に保持器の内周面に被案内面が設けられる場合には、例えば、転がり軸受の軸心に沿って延びる軸平行平面と平行なストレート部を上記案内面に設けることにより、上記の比Ｒｉ／Ｒｅを０．９９０未満とすることができる。 When a guide surface is provided on the outer circumferential surface of the inner ring and a guided surface is provided on the inner circumferential surface of the cage, for example, the straight portion parallel to the axis-parallel plane extending along the axis of the rolling bearing is used as the guide surface. By providing it on the surface, the above ratio Ri/Re can be made less than 0.990.
上記のストレート部は周方向等間隔で複数設けるのが好ましい。これにより、保持器や内輪の質量アンバランスに起因する振動等の問題発生を可及的に防止することができる。 It is preferable that a plurality of the above-mentioned straight portions be provided at equal intervals in the circumferential direction. This makes it possible to prevent problems such as vibrations caused by mass imbalance of the retainer and the inner ring as much as possible.
以上から、本発明によれば、内輪案内又は外輪案内の別を問わず、また軸受の回転数（ｄｍｎ値）を問わず、高速ホワール現象の発生を可及的に防止することができる軌道輪案内型の転がり軸受を実現することが可能となる。 From the above, according to the present invention, the bearing ring can prevent the occurrence of high-speed whirl as much as possible, regardless of whether the inner ring guide or the outer ring guide, and regardless of the rotation speed (dmn value) of the bearing. It becomes possible to realize a guided rolling bearing.
以下、本発明の実施の形態を図面に基づいて説明する。なお、方向性を示すために以下使用する「軸方向」、「径方向」及び「周方向」とは、それぞれ、図１等に示す転がり軸受１の軸受中心（軸心）Ｏと平行な方向、軸心Ｏを中心とする円の径方向、及び軸心Ｏを中心とする円の周方向である。 Embodiments of the present invention will be described below based on the drawings. Note that "axial direction," "radial direction," and "circumferential direction" used below to indicate directionality are directions parallel to the bearing center (axial center) O of the rolling bearing 1 shown in Fig. 1, etc. , a radial direction of a circle centered on the axis O, and a circumferential direction of a circle centered on the axis O.
図１は、本発明の実施形態に係る転がり軸受１の平面図、図２は、図１のＡ－Ａ線矢視概略断面図、図３（ａ）は、転がり軸受１を構成する保持器５の平面図、図３（ｂ）は、同保持器５の右側面図である。この転がり軸受１は、軸受鋼（高炭素クロム軸受鋼）等の高剛性の金属材料で形成され、径方向に対向配置された一対の軌道輪（内輪２及び外輪３）と、内輪２の外周面２ａに形成された内側軌道面と外輪３の内周面３ａに形成された外側軌道面の間に転動自在に介在する複数の転動体（ここでは１０個のボール４）と、ボール４を周方向に間隔を空けて保持した円環状の保持器５とを備えた、いわゆる玉軸受である。 1 is a plan view of a rolling bearing 1 according to an embodiment of the present invention, FIG. 2 is a schematic cross-sectional view taken along the line AA in FIG. 1, and FIG. 3(a) is a cage constituting the rolling bearing 1. 5, and FIG. 3(b) is a right side view of the cage 5. The rolling bearing 1 is made of a highly rigid metal material such as bearing steel (high carbon chromium bearing steel), and includes a pair of bearing rings (inner ring 2 and outer ring 3) arranged radially opposite each other, and an outer circumference of the inner ring 2. A plurality of rolling elements (here, 10 balls 4) interposed in a freely rolling manner between the inner raceway surface formed on the surface 2a and the outer raceway surface formed on the inner peripheral surface 3a of the outer ring 3; This is a so-called ball bearing, which is equipped with an annular retainer 5 that holds the bearings at intervals in the circumferential direction.
保持器５は、周方向等間隔で配置された複数（１０個）のポケット６を有し、各ポケット６にボール４が１個ずつ収容されている。図示例の保持器５は、各ポケット６の内面（ポケット面）６ａが径一定の円筒面に形成された保持器、すなわちポケット６の形状が径方向に一様な保持器である。そして、保持器５は、内輪２及び外輪３との間に径方向すきまを、また、ポケット６に収容したボール４との間に周方向すきまをそれぞれ形成するように内輪２と外輪３の間に組み込まれている。すなわち、図１に示すように、保持器５が中立位置に位置しているとき、対向する内輪２の外周面２ａと保持器５の内周面５ａの間、及び外輪３の内周面３ａと保持器５の外周面５ｂの間には、それぞれ、「案内すきま」とも称される径方向すきま（第１径方向すきまδ１及び第２径方向すきまδ２）が形成され、また、ボール４とポケット面６ａの間には「ポケット周方向すきま」とも称される周方向すきまεが形成される（図２参照）。これにより、転がり軸受１は滑らかに作動可能である。 The retainer 5 has a plurality of (10) pockets 6 arranged at equal intervals in the circumferential direction, and one ball 4 is accommodated in each pocket 6. The cage 5 in the illustrated example is a cage in which the inner surface (pocket surface) 6a of each pocket 6 is formed into a cylindrical surface with a constant diameter, that is, a cage in which the shape of the pocket 6 is uniform in the radial direction. The cage 5 is arranged between the inner ring 2 and the outer ring 3 so as to form a radial clearance between the inner ring 2 and the outer ring 3, and a circumferential clearance between the balls 4 housed in the pockets 6. incorporated into. That is, as shown in FIG. 1, when the cage 5 is located at the neutral position, the space between the opposing outer circumferential surface 2a of the inner ring 2 and the inner circumferential surface 5a of the cage 5, and the inner circumferential surface 3a of the outer ring 3 A radial clearance (a first radial clearance δ1 and a second radial clearance δ2), also called a “guiding clearance”, is formed between the balls 4 and the outer circumferential surface 5b of the cage 5. A circumferential gap ε, also called a "pocket circumferential gap", is formed between the pocket surfaces 6a (see FIG. 2). Thereby, the rolling bearing 1 can operate smoothly.
図示例の転がり軸受１では、第１径方向すきまδ１よりも第２径方向すきまδ２の方が小さく、第２径方向すきまδ２は、例えば直径値で０．８ｍｍとされる。つまり、外輪３の内周面３ａの直径寸法は、保持器５の外周面５ｂの直径寸法よりも０．８ｍｍ大きい。また、周方向すきまεは、例えば直径値で１．２ｍｍとされる。つまり、ポケット６の直径寸法Ｗ［図３（ｂ）参照］は、ボール４の直径寸法よりも１．２ｍｍ大きい。従って、本実施形態の転がり軸受１では、第１径方向すきまδ１、第２径方向すきまδ２及び周方向すきまεのうち、第２径方向すきまδ２が最も小さい。そのため、本実施形態の転がり軸受１は、保持器５の径方向移動が軌道輪である外輪３と保持器５の接触によって制限される。 In the illustrated rolling bearing 1, the second radial clearance δ2 is smaller than the first radial clearance δ1, and the second radial clearance δ2 is, for example, 0.8 mm in diameter. That is, the diameter of the inner peripheral surface 3a of the outer ring 3 is 0.8 mm larger than the diameter of the outer peripheral surface 5b of the retainer 5. Further, the circumferential clearance ε is, for example, 1.2 mm in diameter. That is, the diameter W of the pocket 6 [see FIG. 3(b)] is 1.2 mm larger than the diameter of the ball 4. Therefore, in the rolling bearing 1 of this embodiment, the second radial clearance δ2 is the smallest among the first radial clearance δ1, the second radial clearance δ2, and the circumferential clearance ε. Therefore, in the rolling bearing 1 of this embodiment, the radial movement of the cage 5 is limited by the contact between the cage 5 and the outer ring 3, which is a bearing ring.
図３（ａ）にも示すように、本実施形態の保持器５は、これを平面視したとき、内周面５ａが真円形状に形成されている一方、外周面５ｂが非真円形状に形成されている。ここでは、外周面５ｂの周方向一箇所に、転がり軸受１の軸心Ｏ（保持器５の中心Ｏｃ）に沿って延びる軸平行平面Ｐ－Ｐと平行なストレート部７を形成することにより、外周面５ｂが非真円形状に形成されている。保持器５の内径寸法φａは、例えば４２．８ｍｍとされ、保持器５の外周面５ｂが真円形状であると仮定した場合の外径寸法φｂは、例えば５１．４ｍｍとされ、上記の軸平行平面Ｐ－Ｐ（保持器５の中心Ｏｃ）とストレート部７の離間距離Ｄ１は、例えば２５．３ｍｍとされる。この場合、ストレート部７は、保持器５の外周面５ｂの一部を径方向に最大０．４ｍｍ肉取りすることにより得られる。 As shown in FIG. 3(a), the cage 5 of this embodiment has an inner circumferential surface 5a formed in a perfect circular shape, while an outer circumferential surface 5b has a non-perfect circular shape. is formed. Here, by forming a straight portion 7 parallel to the axis-parallel plane PP extending along the axis O of the rolling bearing 1 (the center Oc of the cage 5) at one location in the circumferential direction of the outer peripheral surface 5b, The outer peripheral surface 5b is formed into a non-perfect circular shape. The inner diameter dimension φa of the cage 5 is, for example, 42.8 mm, and the outer diameter dimension φb when assuming that the outer circumferential surface 5b of the cage 5 is a perfect circle is, for example, 51.4 mm. The distance D 1 between the parallel plane PP (center Oc of the cage 5) and the straight portion 7 is, for example, 25.3 mm. In this case, the straight portion 7 is obtained by cutting a portion of the outer circumferential surface 5b of the retainer 5 by a maximum of 0.4 mm in the radial direction.
保持器５の外周面５ｂにストレート部７を形成したことにより、ストレート部７が形成された周方向領域における第２径方向すきまδ２は、ストレート部７が形成されていない周方向領域における第２径方向すきまδ２よりも大きくなっている（図１参照）。 By forming the straight portion 7 on the outer circumferential surface 5b of the cage 5, the second radial clearance δ2 in the circumferential region where the straight portion 7 is formed is the same as the second radial clearance δ2 in the circumferential region where the straight portion 7 is not formed. It is larger than the radial clearance δ2 (see FIG. 1).
以上の構成を有する本実施形態の保持器５は、樹脂材料の射出成形品からなる樹脂保持器とされ、ポケット６は保持器５を射出成形するのと同時に型成形される。ストレート部７は、ポケット６と同様に、保持器５を射出成形するのと同時に型成形しても良いし、型成形後の機械加工により形成しても良い。但し、保持器５としては、用途・要求特性等に応じて、樹脂保持器以外の保持器、例えば金属材料を所定形状に削り出すことで得られるもみ抜き保持器、あるいは、所定の環状形態にプレス成形（打ち抜き加工）された一対の保持器素材を結合して得られるプレス保持器、が使用される場合もある。 The retainer 5 of this embodiment having the above configuration is a resin retainer made of an injection molded product of a resin material, and the pocket 6 is molded at the same time as the retainer 5 is injection molded. Like the pocket 6, the straight portion 7 may be molded at the same time as the cage 5 is injection molded, or may be formed by machining after molding. However, the cage 5 may be a cage other than a resin cage, such as a machined cage obtained by cutting a metal material into a predetermined shape, or a cage with a predetermined annular shape, depending on the application and required characteristics. A pressed cage obtained by joining a pair of press-formed (punched) cage materials may also be used.
以上の構成を有する転がり軸受１について、「保持器可動領域」、つまり、中立位置に位置している保持器５が外輪３（及び内輪２）と接触せずに存在可能な位置を、二次元座標上に無数にプロットすることで得られる散布図の外縁部を繋ぐ線で囲まれた領域、を求めた。なお、前述したとおり、本実施形態の転がり軸受１では、内輪２と保持器５の間に形成される第１径方向すきまδ１よりも、外輪３と保持器５の間に形成される第２径方向すきまδ２の方が小さいことから、保持器５と外輪３の非接触状態が維持されている間は保持器５と内輪２の非接触状態も維持される。要するに、保持器５が外輪３と接触せずに存在可能な位置に位置している場合、保持器５は内輪２（及びボール４）とも接触しない。本実施形態の転がり軸受１における「保持器可動領域」を求めるに当たって必要となる、保持器５が外輪３と接触せずに存在可能な位置、の求め方を図４に示す概念図に基づいて説明する。 Regarding the rolling bearing 1 having the above configuration, the "cage movable area", that is, the position where the cage 5 located in the neutral position can exist without contacting the outer ring 3 (and inner ring 2) is defined in two dimensions. The area surrounded by the line connecting the outer edges of the scatter diagram obtained by plotting an infinite number of plots on the coordinates was calculated. As described above, in the rolling bearing 1 of this embodiment, the second radial clearance formed between the outer ring 3 and the cage 5 is larger than the first radial clearance δ1 formed between the inner ring 2 and the cage 5. Since the radial clearance δ2 is smaller, while the non-contact state between the cage 5 and the outer ring 3 is maintained, the non-contact state between the cage 5 and the inner ring 2 is also maintained. In short, when the cage 5 is located at a position where it can exist without contacting the outer ring 3, the cage 5 does not contact the inner ring 2 (and the balls 4) either. The method of determining the position where the retainer 5 can exist without contacting the outer ring 3, which is necessary to determine the "cage movable area" in the rolling bearing 1 of this embodiment, is based on the conceptual diagram shown in FIG. explain.
図４は、保持器５、及び外輪３の内周面３ａの一部を抜き出して示す概念図である。同図中の符号Ｏ，Ｏｃは前述したとおり軸受中心及び保持器５の中心をそれぞれ示し、符号Ｐは保持器５の外周面５ｂ上の任意の点を示している。なお、符号Ｐの下付き文字（添え字）は、保持器５の外周面５ｂを離散化（メッシュ分割）したときのｊ番目の点、を示している。 FIG. 4 is a conceptual diagram showing a portion of the retainer 5 and the inner circumferential surface 3a of the outer ring 3. As described above, the symbols O and Oc in the figure indicate the center of the bearing and the center of the cage 5, respectively, and the symbol P indicates an arbitrary point on the outer circumferential surface 5b of the cage 5. Note that the subscript P indicates the j-th point when the outer circumferential surface 5b of the cage 5 is discretized (divided into mesh).
まず、軸受中心Ｏから保持器５の外周面５ｂ上の任意の点Ｐｊに向かうベクトルの大きさ（絶対値ｄ）と外輪３の内周面３ａの半径ｒとを比較し、
・上記絶対値ｄが半径ｒ以上である場合は、保持器５の外周面５ｂ上の任意の点Ｐｊは外輪３と干渉する、と判定し、
・上記絶対値ｄが半径ｒよりも小さい場合は、保持器５の外周面５ｂ上の任意の点Ｐｊは外輪３と干渉しない、と判定する。
以降、これと同様の判定作業を、保持器５の外周面５ｂ上の他の任意の点Ｐｊ＋ｎに対して実行する。
図４に示す例では、保持器５の外周面５ｂ上の任意の点Ｐｊ、Ｐｊ＋１は、外輪３と干渉しない、と言える。
そして、ｆ（ｊ）＝ｄ－ｒとしたときに、全てのｊに対してｆ（ｊ）＜０の関係式が成立すれば、そのときの保持器中心Ｏｃの位置は、保持器５が外輪３と接触せずに存在可能な保持器可動領域上の点であると判定される。
First, compare the magnitude (absolute value d) of a vector directed from the bearing center O to an arbitrary point Pj on the outer circumferential surface 5b of the cage 5 and the radius r of the inner circumferential surface 3a of the outer ring 3,
- If the absolute value d is greater than or equal to the radius r, it is determined that any point Pj on the outer peripheral surface 5b of the retainer 5 interferes with the outer ring 3,
- If the absolute value d is smaller than the radius r, it is determined that any point P j on the outer peripheral surface 5b of the retainer 5 does not interfere with the outer ring 3.
Thereafter, a similar determination operation is performed for any other point P j+n on the outer circumferential surface 5b of the cage 5.
In the example shown in FIG. 4, it can be said that arbitrary points P j and P j+1 on the outer peripheral surface 5b of the cage 5 do not interfere with the outer ring 3.
Then, when f(j)=d−r, if the relational expression f(j)<0 holds true for all j, the position of the cage center O c at that time is the cage 5 is determined to be a point on the retainer movable region that can exist without contacting the outer ring 3.
次に、保持器中心Ｏｃの位置、及び保持器５の位相を変化させ、上記の判定作業と同様の判定作業を実行する。そして、選択した保持器中心Ｏｃの位置において一つでも上記の「保持器可動領域上の点」と判定される位相があれば、その選択したＯｃの位置、及び保持器中心Ｏｃの位置は「保持器可動領域上の点」であると判定する。 Next, the position of the cage center O c and the phase of the cage 5 are changed, and a determination task similar to that described above is performed. If there is a phase that is determined to be the above-mentioned "point on the cage movable region" at the position of the selected cage center O c , then the selected position of the cage center O c and the cage center O c are The position is determined to be "a point on the cage movable area."
図１～３に示す構成を有する本実施形態の転がり軸受１の保持器可動領域１０の形状は、図５（ａ）に示すように、真円形状から多少崩れた形状となり、この保持器可動領域１０の最小外接円径Ｒｅに対する最大内接円径Ｒｉの比（＝Ｒｉ／Ｒｅ）は０．９８６である。一方、これとの比較対象として、保持器６の形状が部分的に異なる転がり軸受１、具体的には、外周面の周方向一箇所にストレート部７が設けられ、かつストレート部７と中心Ｏｃの離間距離Ｄ１を２５．５ｍｍとした保持器６を具備する転がり軸受１における保持器可動領域を求めた。この場合の保持器可動領域１０の形状は図６（ａ）に示すものとなり、この保持器可動領域１０の最小外接円径Ｒｅに対する最大内接円径Ｒｉの比（＝Ｒｉ／Ｒｅ）は０．９９０である。 The shape of the cage movable region 10 of the rolling bearing 1 of this embodiment having the configuration shown in FIGS. 1 to 3 is a shape slightly deformed from a perfect circular shape, as shown in FIG. The ratio of the maximum inscribed circle diameter Ri to the minimum circumscribed circle diameter Re of the region 10 (=Ri/Re) is 0.986. On the other hand, as a comparison object with this, a rolling bearing 1 in which the shape of the retainer 6 is partially different, specifically, a straight part 7 is provided at one location in the circumferential direction of the outer peripheral surface, and the straight part 7 and the center Oc The cage movable area in the rolling bearing 1 equipped with the cage 6 with the separation distance D1 of 25.5 mm was determined. The shape of the cage movable region 10 in this case is as shown in FIG. 6(a), and the ratio of the maximum inscribed circle diameter Ri to the minimum circumscribed circle diameter Re of this cage movable region 10 (=Ri/Re) is 0 It is .990.
そして、上述した本実施形態の転がり軸受１、及び比較対象の転がり軸受を同一条件で運転したときに、各保持器の中心がどのような移動軌跡を辿るか、また各保持器の移動速度（並進速度）がどのように推移するかを動力学解析により検証した。図５（ｂ）及び図５（ｃ）に、本実施形態の転がり軸受１の内輪２が１０回転する間の保持器中心の移動軌跡及び速度（並進速度）の推移をそれぞれ示し、また、図６（ｂ）及び図６（ｃ）に、比較対象の転がり軸受の内輪が１０回転する間の保持器中心の移動軌跡及び速度（並進速度）の推移をそれぞれ示す。 Then, when the rolling bearing 1 of this embodiment described above and the rolling bearing for comparison are operated under the same conditions, what kind of movement locus does the center of each cage follow, and the moving speed of each cage ( We verified how the translational velocity (translational velocity) changes through dynamic analysis. 5(b) and 5(c) respectively show the movement locus of the cage center and the change in speed (translational speed) during 10 rotations of the inner ring 2 of the rolling bearing 1 of this embodiment. 6(b) and 6(c) respectively show the movement locus of the cage center and the change in speed (translational speed) during 10 rotations of the inner ring of the rolling bearing to be compared.
図５（ｂ）と図６（ｂ）を対比すると、本実施形態の転がり軸受１よりも比較対象の転がり軸受の方が、保持器中心の移動軌跡を示す線が遥かに密になっている。また、図５（ｃ）と図６（ｃ）を対比すると、本実施形態の転がり軸受１では、その運転開始後、時間が経過するにつれて保持器５の並進速度がゼロに収束するように徐々に低下しているのに対し、比較対象の転がり軸受では、その運転開始後、所定時間が経過した段階で保持器の並進速度が急激に高速化し、かつその高速化した状態が継続している。この解析結果から、本実施形態の転がり軸受１においては保持器５の高速ホワール現象が発生しないと認められるのに対し、比較対象の転がり軸受においては保持器の高速ホワール現象が発生すると認められる。 Comparing FIG. 5(b) and FIG. 6(b), the lines indicating the movement locus of the cage center are much denser in the comparative rolling bearing than in the rolling bearing 1 of this embodiment. . Moreover, comparing FIG. 5(c) and FIG. 6(c), in the rolling bearing 1 of this embodiment, after the start of operation, the translational speed of the cage 5 gradually converges to zero as time passes. On the other hand, in the comparative rolling bearing, the translational speed of the cage suddenly increases after a predetermined period of time has passed after the start of operation, and this high-speed state continues. . From this analysis result, it is recognized that the high-speed whirl phenomenon of the cage 5 does not occur in the rolling bearing 1 of this embodiment, whereas it is recognized that the high-speed whirl phenomenon of the cage occurs in the rolling bearing for comparison.
従って、保持器可動領域１０の最小外接円径Ｒｅに対する保持器可動領域１０の最大内接円径Ｒｉの比Ｒｉ／Ｒｅを０．９９０未満、すなわち、保持器可動領域１０の形状を、真円形状から乖離した「いびつな形状」とすれば、保持器５の高速ホワール現象の発生を効果的に防止することができると考えられる。保持器可動領域１０の形状をいびつな形状とすることが高速ホワール現象の発生防止に有効である詳細理由を断定することはできないものの、保持器可動領域１０の形状がいびつな形状になることにより、案内面（外輪３の内周面３ａ）と被案内面（保持器５の外周面５ｂ）の接触時に生じる摩擦力の方向が円軌道から外れ、保持器５の振れ回り運動を継続的に加速させることができなくなったためであると推察される。言い換えれば、高速ホワール現象を発生させるには、保持器に作用する力の向きが時計の針のように回転し、常に円運動の加速度として働く必要があり、可動領域の形状をいびつにすることがこの作用を妨げていると推察される。 Therefore, the ratio Ri/Re of the maximum circumscribed circle diameter Ri of the cage movable region 10 to the minimum circumscribed circle diameter Re of the cage movable region 10 is less than 0.990, that is, the shape of the cage movable region 10 is set to a perfect circle. It is believed that the occurrence of high-speed whirl phenomenon in the cage 5 can be effectively prevented by creating a "distorted shape" that deviates from the shape. Although it is not possible to determine the detailed reason why the shape of the cage movable region 10 is effective in preventing the occurrence of high-speed whirl phenomenon, it is possible that the shape of the cage movable region 10 is distorted. , the direction of the frictional force generated when the guiding surface (inner circumferential surface 3a of the outer ring 3) and the guided surface (outer circumferential surface 5b of the cage 5) deviates from the circular orbit, causing the whirling motion of the cage 5 to continue. It is presumed that this was because it was no longer possible to accelerate. In other words, in order to generate a high-speed whirl phenomenon, the direction of the force acting on the retainer must rotate like the hands of a clock and always act as an acceleration of circular motion, making the shape of the movable area distorted. is presumed to be interfering with this effect.
保持器５の高速ホワール現象の発生を効果的に防止するためには、上記のとおり、保持器可動領域１０の最小外接円径Ｒｅに対する最大内接円径Ｒｉの比Ｒｉ／Ｒｅを０．９９０未満とすれば良いが、この比Ｒｉ／Ｒｅがあまりに小さくなると、保持器５に必要とされる機械的強度等を確保することができなくなる、周方向で保持器５の質量バランスが崩れる、などといった問題が生じ、転がり軸受１の軸受性能に悪影響が及ぶ可能性がある。そのため、上記の比Ｒｉ／Ｒｅの下限値は、要求特性やサイズに応じて適宜選定する。 In order to effectively prevent the occurrence of a high-speed whirl phenomenon in the cage 5, as described above, the ratio Ri/Re of the maximum circumscribed circle diameter Ri to the minimum circumscribed circle diameter Re of the cage movable region 10 is set to 0.990. However, if this ratio Ri/Re becomes too small, it will become impossible to ensure the mechanical strength etc. required for the cage 5, and the mass balance of the cage 5 in the circumferential direction will collapse, etc. Such problems may arise, and the bearing performance of the rolling bearing 1 may be adversely affected. Therefore, the lower limit value of the above ratio Ri/Re is appropriately selected depending on the required characteristics and size.
また、本実施形態の転がり軸受１で採用した上記の技術手段は、特許文献１で提案されている技術手段のように保持器のアンバランスを意図的に増加させようとするものではないことから、本発明を転がり軸受１に適用してもアンバランスに起因する遠心力の増加や軸のＮＲＲＯの増加の懸念はない。このため、本発明は軌道輪案内型の転がり軸受に広く適用することができる。 Furthermore, the above technical means adopted in the rolling bearing 1 of this embodiment does not intentionally increase the unbalance of the retainer, unlike the technical means proposed in Patent Document 1. Even if the present invention is applied to the rolling bearing 1, there is no concern about an increase in centrifugal force due to unbalance or an increase in NRRO of the shaft. Therefore, the present invention can be widely applied to raceway guided rolling bearings.
以上で説明した実施形態では、保持器５の外周面５ｂの周方向一箇所にストレート部７を設けたが、このストレート部７は、周方向の二箇所以上に設けても良い。図７（ａ）（ｂ）は、その具体的な一例を示す図であり、外周面５ｂのうち、中心Ｏｃを挟んで対向する二箇所にストレート部７を設けた保持器５（ストレート部７を外周面５ｂの二箇所に等配した保持器５）を示している。係る態様でストレート部７を設けるようにすれば、保持器５の質量アンバランスに起因する振動等の問題発生を防止することができるので、転がり軸受１の信頼性向上を図る上で有利である。 In the embodiment described above, the straight portion 7 is provided at one location in the circumferential direction of the outer peripheral surface 5b of the retainer 5, but the straight portion 7 may be provided at two or more locations in the circumferential direction. FIGS. 7(a) and 7(b) are diagrams showing a specific example of the cage 5 (straight portion 7 This figure shows a cage 5) in which the retainer 5) is equally distributed at two locations on the outer peripheral surface 5b. Providing the straight portion 7 in this manner can prevent problems such as vibration caused by mass imbalance of the cage 5, which is advantageous in improving the reliability of the rolling bearing 1. .
なお、保持器可動領域１０の最小外接円径Ｒｅに対する保持器可動領域１０の最大内接円径Ｒｉの比Ｒｉ／Ｒｅを０．９９０未満とするために設けるストレート部７は、保持器５の外周面５ｂ（被案内面）に替えて、第２径方向すきまδ２を介して対向する外輪３の内周面３ａ（案内面）に設けることも可能である。但し、加工の容易性等を考慮すると保持器５の外周面５ｂにストレート部７を設けるのが好ましい。 The straight portion 7 provided in order to keep the ratio Ri/Re of the maximum circumscribed circle diameter Ri of the cage movable region 10 to the minimum circumscribed circle diameter Re of the cage movable region 10 to be less than 0.990 is Instead of the outer circumferential surface 5b (guided surface), it may be provided on the inner circumferential surface 3a (guide surface) of the outer ring 3 that faces each other with the second radial clearance δ2 in between. However, in consideration of ease of processing, etc., it is preferable to provide the straight portion 7 on the outer circumferential surface 5b of the retainer 5.
以上で説明した本発明の実施形態に係る転がり軸受１は、外輪３の内周面３ａを保持器５を案内するための案内面とした外輪案内型であるが、本発明は、内輪２の外周面２ａを案内面とし、保持器５の内周面５ａを被案内面とした内輪案内型の転がり軸受に適用することもできる。内輪案内型の転がり軸受についての図示は省略するが、この場合には、例えば図８に示すように、案内面である内輪２の外周面２ａの周方向一箇所にストレート部７を設けることにより、保持器可動領域１０の最小外接円径Ｒｅに対する保持器可動領域１０の最大内接円径Ｒｉの比Ｒｉ／Ｒｅを０．９９０未満とすれば、前述した外輪案内型の転がり軸受１と同様の作用効果を享受することができる。なお、ストレート部７は、内輪２の外周面２ａの周方向二箇所以上に設けても良いが、その場合には、内輪２に質量アンバランスが生じるのを防止する観点から、ストレート部７を周方向等間隔で配置するのが好ましい。 The rolling bearing 1 according to the embodiment of the present invention described above is an outer ring guide type in which the inner circumferential surface 3a of the outer ring 3 is used as a guide surface for guiding the cage 5. It can also be applied to an inner ring guide type rolling bearing in which the outer circumferential surface 2a is a guide surface and the inner circumferential surface 5a of the retainer 5 is a guided surface. Although the illustration of an inner ring guide type rolling bearing is omitted, in this case, for example, as shown in FIG. , if the ratio Ri/Re of the maximum circumscribed circle diameter Ri of the cage movable region 10 to the minimum circumscribed circle diameter Re of the cage movable region 10 is less than 0.990, it is similar to the outer ring guided rolling bearing 1 described above. You can enjoy the effects of Note that the straight portions 7 may be provided at two or more locations in the circumferential direction on the outer circumferential surface 2a of the inner ring 2, but in that case, from the viewpoint of preventing mass imbalance from occurring in the inner ring 2, the straight portions 7 It is preferable to arrange them at equal intervals in the circumferential direction.
内輪案内型の転がり軸受１においては、ストレート部７を、内輪２の外周面２ａ（案内面）に替えて、第１径方向すきまδ１を介して対向する保持器５の内周面５ａ（被案内面）に設けることも可能である。但し、加工の容易性等を考慮すると、内輪２の外周面２ａにストレート部７を設けるのが好ましい。 In the inner ring guide type rolling bearing 1, the straight portion 7 is replaced with the outer circumferential surface 2a (guide surface) of the inner ring 2, and is replaced with the inner circumferential surface 5a (covered surface) of the cage 5, which faces the inner circumferential surface 2a (guide surface) of the inner ring 2. It is also possible to provide it on the guide surface. However, in consideration of ease of machining, etc., it is preferable to provide the straight portion 7 on the outer circumferential surface 2a of the inner ring 2.
以上、本発明の実施形態に係る転がり軸受１について説明したが、本発明の実施の形態はこれに限定されるわけではなく、本発明の要旨を逸脱しない範囲において種々の変更を施すことができる。 Although the rolling bearing 1 according to the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to this, and various changes can be made without departing from the gist of the present invention. .
例えば、転がり軸受１を構成する転動体には、ボール４に替えてころ（円筒ころ、針状ころ等）を用いることも可能である。すなわち、本発明は、玉軸受のみならず、円筒ころ軸受や針状ころ軸受等、公知の他の転がり軸受にも適用可能である。また、保持器５に設けられるポケット６の形状は、図２に示すような平面視真円形に形成される以外に、例えば周方向に沿って長軸が配置された楕円状に形成される場合もある。また、単列軸受のみならず複列軸受にも適用可能である。 For example, instead of the balls 4, rollers (cylindrical rollers, needle rollers, etc.) may be used as the rolling elements constituting the rolling bearing 1. That is, the present invention is applicable not only to ball bearings but also to other known rolling bearings such as cylindrical roller bearings and needle roller bearings. In addition, the shape of the pocket 6 provided in the retainer 5 is not limited to a perfect circle in plan view as shown in FIG. There is also. Moreover, it is applicable not only to single-row bearings but also to double-row bearings.
以上で説明したとおり、本発明は、転がり軸受１を構成する保持器５の高速ホワール現象の発生を効果的に防止し得るものであることから、高速ホワール現象が発生し易い用途等で使用される転がり軸受に特に好ましく適用することができる。 As explained above, the present invention can effectively prevent the occurrence of high-speed whirl phenomenon in the cage 5 constituting the rolling bearing 1, and therefore can be used in applications where high-speed whirl phenomenon is likely to occur. It can be particularly preferably applied to rolling bearings.
例えば、工作機械の主軸や宇宙機器のリアクションホイールを支持するための転がり軸受（特に玉軸受）は、使用時に比較的大きな軸方向の予圧を受けている。具体的には、運転中に受ける径方向荷重Ｆｒと軸方向荷重Ｆａの比（＝Ｆｒ／Ｆａ）が３以下である場合が多く、このような場合には高速ホワール現象が特に発生し易い。これは、転動体の周方向での配置間隔が一定になるほど高速ホワール現象が発生し易いためである。逆に言えば、玉軸受に作用する径方向荷重が軸方向荷重に比べて格段に大きい場合（例えば、上記の比Ｆｒ／Ｆａが３を超える場合）には、各転動体（ボール）に進み遅れが生じて転動体の配置間隔が不均一になるため、高速ホワール現象が発生しにくくなる。従って、工作機械の主軸や宇宙機器のリアクションホイールの支持軸受等、下記の式（１）が成立する用途で使用される玉軸受には、本発明を特に好適に適用することができる。 For example, rolling bearings (particularly ball bearings) for supporting the spindle of a machine tool or the reaction wheel of a space machine are subjected to a relatively large axial preload during use. Specifically, the ratio of the radial load Fr to the axial load Fa (=Fr/Fa) received during operation is often 3 or less, and in such cases, the high-speed whirl phenomenon is particularly likely to occur. This is because the more constant the spacing of the rolling elements in the circumferential direction, the more likely the high-speed whirl phenomenon will occur. Conversely, if the radial load acting on the ball bearing is much larger than the axial load (for example, when the above ratio Fr/Fa exceeds 3), the load will be applied to each rolling element (ball). As a delay occurs and the spacing of the rolling elements becomes uneven, high-speed whirl phenomenon becomes less likely to occur. Therefore, the present invention can be particularly suitably applied to ball bearings used in applications where the following formula (1) holds, such as support bearings for main shafts of machine tools and reaction wheels of space equipment.
また、保持器の理論回転数をＮｃ(ｒｐｍ)、ポケットすきまをｃ(ｍｍ)、保持器質量をｍ(ｋｇ)、軸受内の平均転動体荷重をＱ(Ｎ)としたとき、下記の式（２）が成立するときには高速ホワール現象が発生し易い。すなわち、下記の式（２）が成立する運転状況では、保持器の遠心力により転動体が外輪の軌道面（外側軌道面）に対して滑り難いため、転動体の配置間隔が不均一になり難い。従って、本発明は、下記の式（２）が成立する状況で運転される転がり軸受に好適に適用することができる。 In addition, when the theoretical rotational speed of the cage is Nc (rpm), the pocket clearance is c (mm), the cage mass is m (kg), and the average rolling element load in the bearing is Q (N), the following formula is used. When (2) holds true, a high-speed whirl phenomenon is likely to occur. In other words, under operating conditions where formula (2) below holds true, the centrifugal force of the cage makes it difficult for the rolling elements to slide against the raceway surface of the outer ring (outer raceway surface), resulting in uneven spacing between the rolling elements. hard. Therefore, the present invention can be suitably applied to a rolling bearing that is operated in a situation where the following formula (2) holds true.
なお、上記の式（２）における、保持器理論回転数Ｎｃは、内輪回転数をＮｉ（ｒｐｍ）、外輪回転数をＮｅ（ｒｐｍ）、転動体径をＤｗ（ｍｍ）、転動体のピッチ円直径をｄｐ（ｍｍ）、軌道面に対する転動体の接触角をα（ｒａｄ）としたとき、以下の式（３）によって算出することができる。 In addition, in the above formula (2), the cage theoretical rotation speed Nc is determined by the inner ring rotation speed Ni (rpm), the outer ring rotation speed Ne (rpm), the rolling element diameter Dw (mm), and the pitch circle of the rolling element. When the diameter is dp (mm) and the contact angle of the rolling element with the raceway surface is α (rad), it can be calculated using the following equation (3).
以上、本発明に係る転がり軸受１について説明したが、本発明は以上で説明した実施形態に何ら限定されるものではなく、本発明の要旨を逸脱しない範囲内において、さらに種々なる形態で実施し得ることは言うまでもない。本発明の範囲は、特許請求の範囲によって示され、さらに特許請求の範囲に記載の均等の意味、及び範囲内のすべての変更を含む。 Although the rolling bearing 1 according to the present invention has been described above, the present invention is not limited to the embodiments described above, and may be implemented in various forms without departing from the gist of the present invention. Needless to say, you can get it. The scope of the invention is indicated by the claims, and includes all equivalents and all changes within the scope of the claims.
１ 転がり軸受
２ 内輪
３ 外輪
４ ボール（転動体）
５ 保持器
６ ポケット
６ａ ポケット面
１０ 保持器可動領域
Ｒｅ 最小外接円径
Ｒｉ 最大内接円径
δ１ 第１径方向すきま（案内すきま）
δ２ 第２径方向すきま（案内すきま）
ε 周方向すきま（ポケット周方向すきま）
1 Rolling bearing 2 Inner ring 3 Outer ring 4 Ball (rolling element)
5 Cage 6 Pocket 6a Pocket surface 10 Cage movable area Re Minimum circumscribed circle diameter Ri Maximum inscribed circle diameter δ1 First radial clearance (guide clearance)
δ2 2nd radial clearance (guiding clearance)
ε Circumferential clearance (pocket circumferential clearance)
Claims (4)
中立位置に位置している前記保持器が前記内輪、前記外輪及び前記転動体と接触せずに存在可能な位置を、二次元座標上に無数にプロットすることで得られる散布図の外縁部を繋ぐ線で囲まれた領域を保持器可動領域と定義したとき、この保持器可動領域の最小外接円径Ｒｅに対する前記保持器可動領域の最大内接円径Ｒｉの比Ｒｉ／Ｒｅが０．９９０未満であることを特徴とする転がり軸受。 An inner ring and an outer ring that rotate relative to each other via a plurality of rolling elements, and a cage in which a plurality of pockets each housing the rolling elements are provided at intervals in the circumferential direction, and the cage is configured to It has an annular guided surface that is guided by an annular guide surface provided on the inner circumferential surface of the outer ring or the outer circumferential surface of the inner ring, and the radial clearance formed between the guide surface and the guided surface is , in a rolling bearing smaller than a radial clearance formed between the pocket inner surface of the retainer and the rolling element,
The outer edge of a scatter diagram obtained by plotting on two-dimensional coordinates an infinite number of positions where the cage located at the neutral position can exist without contacting the inner ring, the outer ring, and the rolling elements. When the area surrounded by the connecting lines is defined as the cage movable region, the ratio Ri/Re of the maximum inscribed circle diameter Ri of the cage movable region to the minimum circumscribed circle diameter Re of this cage movable region is 0.990. A rolling bearing characterized in that:
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