WO2022070990A1 - Crossed roller bearing - Google Patents

Crossed roller bearing Download PDF

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Publication number
WO2022070990A1
WO2022070990A1 PCT/JP2021/034300 JP2021034300W WO2022070990A1 WO 2022070990 A1 WO2022070990 A1 WO 2022070990A1 JP 2021034300 W JP2021034300 W JP 2021034300W WO 2022070990 A1 WO2022070990 A1 WO 2022070990A1
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Prior art keywords
inclined raceway
roller bearing
outer ring
surface roughness
inner ring
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PCT/JP2021/034300
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French (fr)
Japanese (ja)
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雄一郎 川上
恵太 片渕
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Ntn株式会社
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Publication of WO2022070990A1 publication Critical patent/WO2022070990A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/22—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings
    • F16C19/34—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load
    • F16C19/36—Bearings with rolling contact, for exclusively rotary movement with bearing rollers essentially of the same size in one or more circular rows, e.g. needle bearings for both radial and axial load with a single row of rollers

Definitions

  • the present invention relates to a cross roller bearing in which rollers are incorporated so that the inclination direction alternately changes in the circumferential direction between the outer ring and the inner ring.
  • a cross roller bearing has a plurality of rollers bearing between a pair of inclined race planes formed on the inner peripheral surface of the outer ring and orthogonal to each other and a pair of inclined race planes formed on the outer peripheral surface of the inner ring.
  • the bearings are arranged so that the inclination directions change alternately in the circumferential direction (for example, Patent Document 1).
  • each inclined raceway surface of the inner ring and the outer ring is the same.
  • cross roller bearing can support a large radial load, thrust load, and moment load, it is widely used in industrial machines, for example, reduction gears for robots that require particularly high rigidity.
  • the cross roller bearing mounted on the speed reducer for robots is required to have low torque and a rolling life that can be used stably.
  • the cross roller bearing provided in the reduction gear for robots is used under dilute lubrication conditions where the oil film parameter between the inclined track surface and the roller is small because the rotation speed is slow.
  • the oil film parameter means the ratio of the minimum oil film thickness between two rolling surfaces determined by the elastic fluid lubrication theory to the square root of the sum of squares of the root mean square roughness of these two surfaces.
  • peeling refers to damage having a size of about 10 ⁇ m and a depth of about several ⁇ m to 10 ⁇ m in which minute peels are densely packed. Peeling on the rollers causes a significant deterioration in rolling life. It is known that peeling is likely to occur under dilute lubrication conditions and when the difference in surface roughness between the two rolling surfaces is large.
  • the surface roughness of the inclined track surface is made smaller than necessary. It is not preferable to do so.
  • the problem to be solved by the present invention is to suppress the cause of deterioration of low torque and rolling life while avoiding processing of an excessively inclined raceway surface of the cross roller bearing.
  • the present invention has an outer ring having a pair of inclined raceway surfaces orthogonal to each other on the inner peripheral surface, an inner ring having a pair of inclined raceway surfaces orthogonal to each other on the outer peripheral surface, and a pair of the outer rings.
  • a cross roller bearing provided with a plurality of rollers arranged so as to alternately change the inclined direction in the circumferential direction between the inclined raceway surface and the pair of inclined raceway surfaces of the inner ring, the surface of the inclined raceway surface of the outer ring.
  • a configuration is adopted in which the roughness Ra is provided to be smaller than the surface roughness Ra of the inclined raceway surface of the inner ring.
  • the surface roughness Ra refers to the arithmetic average roughness: Ra of the roughness parameter specified in JIS B0601: 2013 (corresponding ISO4287: 1997).
  • the slip contact between the end face of the roller and the raceway surface that occurs during the operation of the cross roller bearing mainly occurs between the outer ring and the roller, and hardly occurs between the inner ring and the roller. Therefore, if the surface roughness Ra of the inclined raceway surface of the outer ring is set smaller than the surface roughness Ra of the inclined raceway surface of the inner ring, the torque between the outer ring and the end face of the roller, which causes deterioration of low torque and rolling life, is provided. While the frictional resistance is reduced, it is possible to avoid excessively reducing the surface roughness of the inclined raceway surface of the inner ring.
  • the surface roughness Ra of the inclined raceway surface of the outer ring and the surface roughness Ra of the inclined raceway surface of the inner ring are each provided to be 0.3 ⁇ m or less. By doing so, it is possible to suppress the occurrence of peeling in the rollers.
  • the surface roughness Ra of the inclined raceway surface of the outer ring and the surface roughness Ra of the inclined raceway surface of the inner ring are each provided to 0.1 ⁇ m or more. Is more preferable.
  • the present invention by adopting the above configuration, it is possible to suppress the cause of deterioration of low torque and rolling life while avoiding processing of an excessively inclined raceway surface of the cross roller bearing.
  • Sectional drawing which shows the cross roller bearing which concerns on embodiment of this invention Partial cross-sectional view showing a state in which a cross roller bearing is in operation on the cut surface of the line II-II in FIG.
  • the figure which shows the measurement example of the generatrix shape in the initial wear state of the inclined track surface of the outer ring of FIG.
  • This cross roller bearing shown in FIG. 1 includes an outer ring 1, an inner ring 2, and a plurality of rollers 3 arranged in a single row between the outer ring 1 and the inner ring 2.
  • This cross-roller bearing is specifically intended to be incorporated in a speed reducer for a robot.
  • the outer ring 1 has a pair of inclined raceway surfaces 1a orthogonal to each other on the inner peripheral surface.
  • the inner ring 2 has a pair of inclined raceway surfaces 2a orthogonal to each other on the outer peripheral surface.
  • the roller 3 is made of a cylindrical roller.
  • the outer ring 1, inner ring 2 and roller 3 are each made of steel.
  • the material is, for example, bearing steel.
  • the plurality of rollers 3 alternately change their inclination directions in the circumferential direction between the pair of inclined raceway surfaces 1a of the outer ring 1 and the pair of inclined raceway surfaces 2a of the inner ring 2. Is located in.
  • This cross roller bearing is provided in a full roller type.
  • the total roller type is a bearing component (holding) in which the sum of the clearances between the rollers 3 arranged in a row between the inclined raceway surfaces 1a and 2a does not exceed the diameter of the rollers 3 and separates the adjacent rollers 3. It does not have a vessel, spacer, etc.), but it means that the adjacent rollers 3 are arranged so as to be in contact with each other so as to function as a bearing.
  • the pair of inclined track surfaces 1a of the outer ring 1 extend linearly to both sides in the axial direction from the relief groove 1b formed in the central portion of the inner peripheral surface of the outer ring 1 in the axial direction in the axial cross section, and one of them is inclined.
  • the raceway surface 1a comes into linear contact with the rolling surface of the roller 3.
  • the pair of inclined orbital surfaces 2a of the inner ring 2 extend linearly on both sides in the axial direction from the relief groove 2b formed in the axial center portion of the outer peripheral surface of the inner ring 2 in the axial cross section thereof, and one of them.
  • the inclined track surface 2a of the roller 3 comes into linear contact with the rolling surface of the roller 3.
  • the roller 3 is closer to the outer ring 1 side, and the end surface 3a on the outer ring 1 side of the roller 3 is narrower than the inclined track surface 1a that covers the roller 3 in the traveling direction. This is because the end surface 3a on the inner ring 2 side of the roller 3 hardly contacts the inclined raceway surface 2a of the inner ring 2 while sliding contact is made in the contact region P.
  • FIG. 3 illustrates the generatrix shape of the inclined raceway surface 1a of the outer ring 1 subjected to the wear evaluation test.
  • FIG. 3 on the inclined track surface 1a in the initial wear state, initial wear due to contact with the edge of the end surface 3a of the roller 3 is observed in the vicinity of the central portion of the bus shape.
  • the contact marks due to the initial wear are drawn with a large exaggeration.
  • Table 1 shows the evaluation results of the presence or absence of peeling.
  • the inclined raceway surface 1a of the outer ring 1 and the inclined raceway surface 2a of the inner ring 2 were finished to have the same surface roughness Ra.
  • the difference in surface roughness Ra of the inclined orbital surfaces 1a and 2a between the samples was set to 0.05 ⁇ m.
  • peeling is more likely to occur in the roller 3 when the inclined track surfaces 1a and 2a are rough surfaces, and the surface roughness Ra of the inclined track surfaces 1a and 2a can be set to 0.3 ⁇ m or less. It is considered to be effective in preventing the occurrence of peeling.
  • reducing the surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 reduces the contact resistance between the outer ring 1 and the end surface 3a of the roller 3. It is particularly effective in suppressing the deterioration of the rolling life due to torque reduction and wear, but it is considered that reducing the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 is not effective.
  • the surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 is set to be smaller than the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 in consideration of the load on the machined surface while taking the above-mentioned test results into consideration.
  • the surface roughness Ra of the inclined track surface 1a and the surface roughness Ra of the inclined track surface 2a are provided to be 0.1 ⁇ m or more and 0.3 ⁇ m or less, respectively.
  • Table 1 shows the evaluation results at 0.15 ⁇ m or more, but in consideration of the variation in the machined surface, it was set to 0.1 ⁇ m or more.
  • this cross roller bearing is provided with a surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 smaller than the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2, so that it has low torque and rolling. While the frictional resistance at the sliding contact portion between the inclined raceway surface 1a of the outer ring 1 and the end surface 3a of the roller 3 which causes deterioration of the life is reduced, the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 is excessively increased. It is possible to avoid making it smaller. Therefore, this cross-roller bearing can suppress the cause of deterioration of low torque property and rolling life while avoiding processing of an excessively inclined raceway surface.
  • the surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 and the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 are each provided to be 0.3 ⁇ m or less, so that the peeling on the roller 3 is performed. Can be suppressed.
  • the cross roller bearing is provided with the surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 and the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 of 0.1 ⁇ m or more, the above-mentioned roller 3 is provided.
  • the frictional resistance at the sliding contact portion between the end surface 3a and the inclined track surface 1a is suppressed to reduce the torque, and the wear due to this friction and the occurrence of peeling on the roller 3 are suppressed to improve the rolling life. It is also possible to suppress excessive processing of the inclined track surfaces 1a and 2a to reduce the provided price.
  • this cross roller bearing is provided in a full roller type, it can be made particularly highly rigid.
  • the full roller type there is no cage or spacer, and the maximum number of rollers 3 that can be accommodated between the inclined track surfaces 1a and 2a is incorporated, so that the adjacent rollers 3 come into contact with each other and the number of rollers 3 increases. Will increase.
  • the full roller type cross roller bearing has a slow rotation speed and tends to be under dilute lubrication conditions, and also has a large number of sliding contact points between the end surface 3a of the roller 3 and the inclined raceway surface 1a.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

The present invention suppresses the causes of deterioration of the low torque property and rolling life of a crossed roller bearing, while avoiding excessive machining of an inclined raceway surface of the crossed roller bearing. An inclined raceway surface (1a) of an outer ring (1) is provided so as to have a smaller surface roughness Ra than the surface roughness Ra of an inclined raceway surface (2a) of an inner ring (2). The inclined raceway surfaces (1a, 2a) are provided such that the surface roughnesses Ra are smaller than or equal to 0.3 μm.

Description

クロスローラ軸受Cross roller bearing
　この発明は、外輪と内輪の間に周方向に交互に傾斜方向が変わるようにローラを組み込んだクロスローラ軸受に関する。 The present invention relates to a cross roller bearing in which rollers are incorporated so that the inclination direction alternately changes in the circumferential direction between the outer ring and the inner ring.
　クロスローラ軸受は、外輪の内周面に形成された互いに直交する一対の傾斜軌道面と、内輪の外周面に形成された互いに直交する一対の傾斜軌道面との間に、複数のローラを軸受周方向に交互に傾斜方向が変わるように配したものである（例えば、特許文献１）。 A cross roller bearing has a plurality of rollers bearing between a pair of inclined race planes formed on the inner peripheral surface of the outer ring and orthogonal to each other and a pair of inclined race planes formed on the outer peripheral surface of the inner ring. The bearings are arranged so that the inclination directions change alternately in the circumferential direction (for example, Patent Document 1).
　一般的なクロスローラ軸受では、内輪と外輪の各傾斜軌道面における表面粗さは同等である。 In a general cross roller bearing, the surface roughness of each inclined raceway surface of the inner ring and the outer ring is the same.
　クロスローラ軸受は、大きなラジアル荷重やスラスト荷重、モーメント荷重を支えることが可能なため、産業機械、例えば、特に高い剛性が必要とされるロボット用の減速機等に広く使用されている。 Since the cross roller bearing can support a large radial load, thrust load, and moment load, it is widely used in industrial machines, for example, reduction gears for robots that require particularly high rigidity.
特許第３７３９０５６号公報Japanese Patent No. 3739056
　ロボット用減速機に搭載されるクロスローラ軸受には、低トルク性や、安定して使用し続けられる転がり寿命が要求される。 The cross roller bearing mounted on the speed reducer for robots is required to have low torque and a rolling life that can be used stably.
　しかしながら、クラスローラ軸受では、傾斜軌道面に対して各ローラの端面が滑り接触する摩擦抵抗がある。この摩擦抵抗は、低トルク性を阻害し、また、摩耗の原因となるので、転がり寿命に悪影響を及ぼす。 However, in class roller bearings, there is frictional resistance in which the end faces of each roller slide into contact with the inclined raceway surface. This frictional resistance hinders low torque performance and causes wear, which adversely affects the rolling life.
　また、ロボット用減速機に備わるクロスローラ軸受は、使用回転速度が遅いため、傾斜軌道面とローラ間の油膜パラメータが小さい希薄潤滑条件下で使用される。ここで、油膜パラメータは、弾性流体潤滑理論によって求められる転動する二面間の最小油膜厚さと、これら二面の二乗平均平方根粗さの二乗和の平方根との比を意味する。 In addition, the cross roller bearing provided in the reduction gear for robots is used under dilute lubrication conditions where the oil film parameter between the inclined track surface and the roller is small because the rotation speed is slow. Here, the oil film parameter means the ratio of the minimum oil film thickness between two rolling surfaces determined by the elastic fluid lubrication theory to the square root of the sum of squares of the root mean square roughness of these two surfaces.
　油膜パラメータが小さい程、ローラにピーリングが発生する可能性が高まる。ここで、ピーリングは、大きさが１０μｍ程度、深さが数μｍから１０μｍ程度の微小はく離が密集した損傷のことをいう。ローラにピーリングが発生することは、転がり寿命を著しく悪化させる原因となる。希薄潤滑条件下で、かつ転動する二面間の表面粗さの差が大きい場合にピーリングが発生しやすいことが知られている。 The smaller the oil film parameter, the higher the possibility of peeling on the rollers. Here, peeling refers to damage having a size of about 10 μm and a depth of about several μm to 10 μm in which minute peels are densely packed. Peeling on the rollers causes a significant deterioration in rolling life. It is known that peeling is likely to occur under dilute lubrication conditions and when the difference in surface roughness between the two rolling surfaces is large.
　前述の滑り接触による摩擦抵抗の抑制やピーリングの発生を抑制するため、傾斜軌道面の表面粗さを小さくすることが好ましいが、加工性やコストの観点からすると、必要以上に表面粗さを小さくすることは好ましくない。 It is preferable to reduce the surface roughness of the inclined track surface in order to suppress the frictional resistance and the occurrence of peeling due to the slip contact described above, but from the viewpoint of workability and cost, the surface roughness is made smaller than necessary. It is not preferable to do so.
　上述の背景に鑑み、この発明が解決しようとする課題は、クロスローラ軸受の過剰な傾斜軌道面の加工を避けつつ、低トルク性及び転がり寿命の悪化原因を抑制することにある。 In view of the above background, the problem to be solved by the present invention is to suppress the cause of deterioration of low torque and rolling life while avoiding processing of an excessively inclined raceway surface of the cross roller bearing.
　上記の課題を達成するため、この発明は、互いに直交する一対の傾斜軌道面を内周面に有する外輪と、互いに直交する一対の傾斜軌道面を外周面に有する内輪と、前記外輪の一対の傾斜軌道面と前記内輪の一対の傾斜軌道面との間に、周方向に交互に傾斜方向が変わるように配置された複数のローラとを備えるクロスローラ軸受において、前記外輪の傾斜軌道面の表面粗さＲａが前記内輪の傾斜軌道面の表面粗さＲａよりも小さく設けられている構成を採用したものである。ここで、表面粗さＲａは、ＪＩＳ　Ｂ０６０１：２０１３（対応ＩＳＯ４２８７：１９９７）で規定された粗さパラメータの算術平均粗さ：Ｒａのことをいう。 In order to achieve the above problems, the present invention has an outer ring having a pair of inclined raceway surfaces orthogonal to each other on the inner peripheral surface, an inner ring having a pair of inclined raceway surfaces orthogonal to each other on the outer peripheral surface, and a pair of the outer rings. In a cross roller bearing provided with a plurality of rollers arranged so as to alternately change the inclined direction in the circumferential direction between the inclined raceway surface and the pair of inclined raceway surfaces of the inner ring, the surface of the inclined raceway surface of the outer ring. A configuration is adopted in which the roughness Ra is provided to be smaller than the surface roughness Ra of the inclined raceway surface of the inner ring. Here, the surface roughness Ra refers to the arithmetic average roughness: Ra of the roughness parameter specified in JIS B0601: 2013 (corresponding ISO4287: 1997).
　クロスローラ軸受の運転中に発生するローラの端面と軌道面の滑り接触は、外輪とローラ間で主に発生し、内輪とローラ間では殆ど発生しない。このため、外輪の傾斜軌道面の表面粗さＲａを内輪の傾斜軌道面の表面粗さＲａよりも小さく設ければ、低トルク性及び転がり寿命を悪化させる原因となる外輪とローラの端面間の摩擦抵抗が低減される一方、内輪の傾斜軌道面の表面粗さを過剰に小さくすることが避けられる。 The slip contact between the end face of the roller and the raceway surface that occurs during the operation of the cross roller bearing mainly occurs between the outer ring and the roller, and hardly occurs between the inner ring and the roller. Therefore, if the surface roughness Ra of the inclined raceway surface of the outer ring is set smaller than the surface roughness Ra of the inclined raceway surface of the inner ring, the torque between the outer ring and the end face of the roller, which causes deterioration of low torque and rolling life, is provided. While the frictional resistance is reduced, it is possible to avoid excessively reducing the surface roughness of the inclined raceway surface of the inner ring.
　前記外輪の傾斜軌道面の表面粗さＲａ及び前記内輪の傾斜軌道面の表面粗さＲａがそれぞれ０．３μｍ以下に設けられているとよい。このようにすると、ローラにおけるピーリングの発生を抑制することができる。 It is preferable that the surface roughness Ra of the inclined raceway surface of the outer ring and the surface roughness Ra of the inclined raceway surface of the inner ring are each provided to be 0.3 μm or less. By doing so, it is possible to suppress the occurrence of peeling in the rollers.
　内外輪の傾斜軌道面の加工コストを抑える観点からは、前記外輪の傾斜軌道面の表面粗さＲａ及び前記内輪の傾斜軌道面の表面粗さＲａがそれぞれ０．１μｍ以上に設けられていることがより好ましい。 From the viewpoint of suppressing the processing cost of the inclined raceway surface of the inner and outer rings, the surface roughness Ra of the inclined raceway surface of the outer ring and the surface roughness Ra of the inclined raceway surface of the inner ring are each provided to 0.1 μm or more. Is more preferable.
　総ころ形式に設けられていることが好ましい。このようにすると、特に高剛性のクロスローラ軸受にすることできる。 It is preferable that it is provided in a full-roll format. By doing so, it is possible to obtain a cross roller bearing having particularly high rigidity.
　この発明は、上記構成の採用により、クロスローラ軸受の過剰な傾斜軌道面の加工を避けつつ、低トルク性及び転がり寿命の悪化原因を抑制することができる。 According to the present invention, by adopting the above configuration, it is possible to suppress the cause of deterioration of low torque and rolling life while avoiding processing of an excessively inclined raceway surface of the cross roller bearing.
この発明の実施形態に係るクロスローラ軸受を示す断面図Sectional drawing which shows the cross roller bearing which concerns on embodiment of this invention 図１のＩＩ－ＩＩ線の切断面でクロスローラ軸受の運転中の様子を示す部分断面図Partial cross-sectional view showing a state in which a cross roller bearing is in operation on the cut surface of the line II-II in FIG. 図１の外輪の傾斜軌道面の初期摩耗状態における母線形状の測定例を示す図The figure which shows the measurement example of the generatrix shape in the initial wear state of the inclined track surface of the outer ring of FIG.
　以下、図面に基づき、この発明の一例としての実施形態を説明する。 Hereinafter, embodiments as an example of the present invention will be described with reference to the drawings.
　図１に示すこのクロスローラ軸受は、外輪１と、内輪２と、外輪１と内輪２との間に単列に配置された複数のローラ３とを備える。このクロスローラ軸受は、特に、ロボット用の減速機に組み込まれるものを想定している。 This cross roller bearing shown in FIG. 1 includes an outer ring 1, an inner ring 2, and a plurality of rollers 3 arranged in a single row between the outer ring 1 and the inner ring 2. This cross-roller bearing is specifically intended to be incorporated in a speed reducer for a robot.
　外輪１は、互いに直交する一対の傾斜軌道面１ａを内周面に有する。内輪２は、互いに直交する一対の傾斜軌道面２ａを外周面に有する。 The outer ring 1 has a pair of inclined raceway surfaces 1a orthogonal to each other on the inner peripheral surface. The inner ring 2 has a pair of inclined raceway surfaces 2a orthogonal to each other on the outer peripheral surface.
　ローラ３は、円筒ころからなる。 The roller 3 is made of a cylindrical roller.
　外輪１、内輪２及びローラ３は、それぞれ鋼を素材としたものである。その素材は、例えば、軸受鋼である。 The outer ring 1, inner ring 2 and roller 3 are each made of steel. The material is, for example, bearing steel.
　図１、図２に示すように、複数のローラ３は、外輪１の一対の傾斜軌道面１ａと内輪２の一対の傾斜軌道面２ａとの間に、周方向に交互に傾斜方向が変わるように配置されている。 As shown in FIGS. 1 and 2, the plurality of rollers 3 alternately change their inclination directions in the circumferential direction between the pair of inclined raceway surfaces 1a of the outer ring 1 and the pair of inclined raceway surfaces 2a of the inner ring 2. Is located in.
　このクロスローラ軸受は、総ころ形式に設けられている。ここで、総ころ形式とは、傾斜軌道面１ａと２ａ間に一列に並ぶローラ３間のすきまの和が、ローラ３の直径を超えておらず、隣り合うローラ３間を隔てる軸受部品（保持器、スペーサ等）を備えていないが、軸受として機能するように隣り合うローラ３同士が接触可能に配置されていることを意味する。 This cross roller bearing is provided in a full roller type. Here, the total roller type is a bearing component (holding) in which the sum of the clearances between the rollers 3 arranged in a row between the inclined raceway surfaces 1a and 2a does not exceed the diameter of the rollers 3 and separates the adjacent rollers 3. It does not have a vessel, spacer, etc.), but it means that the adjacent rollers 3 are arranged so as to be in contact with each other so as to function as a bearing.
　外輪１の一対の傾斜軌道面１ａは、その軸方向断面において、外輪１の内周面の軸方向中央部に形成された逃げ溝１ｂから軸方向両側へ直線状に延び、そのうちの一方の傾斜軌道面１ａがローラ３の転動面と直線的に接触する。同様に、内輪２の一対の傾斜軌道面２ａは、その軸方向断面において、内輪２の外周面の軸方向中央部に形成された逃げ溝２ｂから軸方向両側へ直線状に延び、そのうちの一方の傾斜軌道面２ａがローラ３の転動面と直線的に接触する。 The pair of inclined track surfaces 1a of the outer ring 1 extend linearly to both sides in the axial direction from the relief groove 1b formed in the central portion of the inner peripheral surface of the outer ring 1 in the axial direction in the axial cross section, and one of them is inclined. The raceway surface 1a comes into linear contact with the rolling surface of the roller 3. Similarly, the pair of inclined orbital surfaces 2a of the inner ring 2 extend linearly on both sides in the axial direction from the relief groove 2b formed in the axial center portion of the outer peripheral surface of the inner ring 2 in the axial cross section thereof, and one of them. The inclined track surface 2a of the roller 3 comes into linear contact with the rolling surface of the roller 3.
　このクロスローラ軸受の傾斜軌道面１ａ、２ａの表面粗さＲａを変更したサンプルにて、一般的な使用条件で評価試験を行った。その評価内容は、触感による回転検査、ピーリング発生有無、および摩耗である。 An evaluation test was conducted under general usage conditions on a sample in which the surface roughness Ra of the inclined raceway surfaces 1a and 2a of this cross roller bearing was changed. The evaluation contents are rotation inspection by tactile sensation, presence / absence of peeling, and wear.
　まず、サンプル組み立て後、触感による回転検査を行った。その結果、傾斜軌道面１ａ、２ａの表面粗さＲａが小さいものである程、滑らかに回転した。ただし、内輪２の傾斜軌道面２ａの表面粗さＲａの大小は、触感での回転検査の結果に殆ど影響を及ぼさず、外輪１の傾斜軌道面１ａの表面粗さＲａの大小は、触感での回転検査の結果に大きな影響を及ぼした。この理由は、運転中、図２に示すように、ローラ３が外輪１側に寄り、ローラ３の進行方向に覆いかぶさった傾斜軌道面１ａに対してローラ３の外輪１側の端面３ａが狭い接触領域Ｐにおいて滑り接触する一方、このとき、ローラ３の内輪２側の端面３ａが内輪２の傾斜軌道面２ａに殆ど接触しないためである。 First, after assembling the sample, a rotation inspection was performed by tactile sensation. As a result, the smaller the surface roughness Ra of the inclined orbital surfaces 1a and 2a, the smoother the rotation. However, the magnitude of the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 has almost no effect on the result of the rotation inspection by tactile sensation, and the magnitude of the surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 is tactile sensation. It had a great influence on the result of the rotation inspection. The reason for this is that, as shown in FIG. 2, during operation, the roller 3 is closer to the outer ring 1 side, and the end surface 3a on the outer ring 1 side of the roller 3 is narrower than the inclined track surface 1a that covers the roller 3 in the traveling direction. This is because the end surface 3a on the inner ring 2 side of the roller 3 hardly contacts the inclined raceway surface 2a of the inner ring 2 while sliding contact is made in the contact region P.
　実際に、摩耗評価試験の外輪１の傾斜軌道面１ａの中央部には、図１に示すように、初期摩耗による接触痕Ｉｗが発生したが、内輪２の傾斜軌道面２ａには初期摩耗による接触痕が殆ど発生しなかった。図３に、摩耗評価試験を行った外輪１の傾斜軌道面１ａの母線形状を例示する。図３から明らかなように、初期摩耗状態の傾斜軌道面１ａには、母線形状の中央部近傍にローラ３の端面３ａの縁付近との接触による初期摩耗が認められる。なお、図１では、初期摩耗による接触痕を大幅に誇張して描いている。 Actually, as shown in FIG. 1, a contact mark Iw due to initial wear was generated in the central portion of the inclined raceway surface 1a of the outer ring 1 in the wear evaluation test, but the inclined raceway surface 2a of the inner ring 2 was caused by the initial wear. Almost no contact marks were generated. FIG. 3 illustrates the generatrix shape of the inclined raceway surface 1a of the outer ring 1 subjected to the wear evaluation test. As is clear from FIG. 3, on the inclined track surface 1a in the initial wear state, initial wear due to contact with the edge of the end surface 3a of the roller 3 is observed in the vicinity of the central portion of the bus shape. In FIG. 1, the contact marks due to the initial wear are drawn with a large exaggeration.
　次に、ピーリング発生有無の評価結果を表１に示す。各サンプルでは、外輪１の傾斜軌道面１ａ及び内輪２の傾斜軌道面２ａを同等の表面粗さＲａに仕上げた。サンプル間での傾斜軌道面１ａ、２ａの表面粗さＲａの差は、０．０５μｍに設定した。 Next, Table 1 shows the evaluation results of the presence or absence of peeling. In each sample, the inclined raceway surface 1a of the outer ring 1 and the inclined raceway surface 2a of the inner ring 2 were finished to have the same surface roughness Ra. The difference in surface roughness Ra of the inclined orbital surfaces 1a and 2a between the samples was set to 0.05 μm.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　表１の評価結果より、傾斜軌道面１ａ、２ａが粗面である方がローラ３にピーリングが発生し易くなり、傾斜軌道面１ａ、２ａの表面粗さＲａを０．３μｍ以下にすることがピーリング発生を防止することに有効であると考えられる。 From the evaluation results in Table 1, peeling is more likely to occur in the roller 3 when the inclined track surfaces 1a and 2a are rough surfaces, and the surface roughness Ra of the inclined track surfaces 1a and 2a can be set to 0.3 μm or less. It is considered to be effective in preventing the occurrence of peeling.
　また、上述の摩耗評価試験で行った触感による回転検査の結果からは、外輪１の傾斜軌道面１ａの表面粗さＲａを小さくすることは、外輪１とローラ３の端面３ａ間の接触抵抗を抑制し、ひいてはトルク低減及び摩耗による転がり寿命の悪化を抑制することに特に有効であるが、内輪２の傾斜軌道面２ａの表面粗さＲａを小さくすることは有効性に乏しいと考えられる。 Further, from the results of the rotation inspection by tactile sensation conducted in the above-mentioned wear evaluation test, reducing the surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 reduces the contact resistance between the outer ring 1 and the end surface 3a of the roller 3. It is particularly effective in suppressing the deterioration of the rolling life due to torque reduction and wear, but it is considered that reducing the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 is not effective.
　一方、傾斜軌道面１ａ、２ａの表面粗さＲａを小さくする程、加工が難しくなり、コストを要することになる。 On the other hand, the smaller the surface roughness Ra of the inclined track surfaces 1a and 2a, the more difficult the processing becomes and the more costly it becomes.
　上述の試験結果を踏まえつつ加工面の負担を考慮して、外輪１の傾斜軌道面１ａの表面粗さＲａは、内輪２の傾斜軌道面２ａの表面粗さＲａよりも小さく設けられている。 The surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 is set to be smaller than the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 in consideration of the load on the machined surface while taking the above-mentioned test results into consideration.
　また、傾斜軌道面１ａの表面粗さＲａ及び傾斜軌道面２ａの表面粗さＲａは、それぞれ０．１μｍ以上、０．３μｍ以下に設けられている。表１では０．１５μｍ以上における評価結果が記載されているが、加工面のばらつきを考慮して、０．１μｍ以上とした。 Further, the surface roughness Ra of the inclined track surface 1a and the surface roughness Ra of the inclined track surface 2a are provided to be 0.1 μm or more and 0.3 μm or less, respectively. Table 1 shows the evaluation results at 0.15 μm or more, but in consideration of the variation in the machined surface, it was set to 0.1 μm or more.
　このクロスローラ軸受は、上述のように、外輪１の傾斜軌道面１ａの表面粗さＲａが内輪２の傾斜軌道面２ａの表面粗さＲａよりも小さく設けられているため、低トルク性及び転がり寿命を悪化させる原因となる外輪１の傾斜軌道面１ａとローラ３の端面３ａ間の滑り接触部での摩擦抵抗が低減される一方、内輪２の傾斜軌道面２ａの表面粗さＲａを過剰に小さくすることが避けられる。したがって、このクロスローラ軸受は、過剰な傾斜軌道面の加工を避けつつ、低トルク性及び転がり寿命の悪化原因を抑制することができる。 As described above, this cross roller bearing is provided with a surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 smaller than the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2, so that it has low torque and rolling. While the frictional resistance at the sliding contact portion between the inclined raceway surface 1a of the outer ring 1 and the end surface 3a of the roller 3 which causes deterioration of the life is reduced, the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 is excessively increased. It is possible to avoid making it smaller. Therefore, this cross-roller bearing can suppress the cause of deterioration of low torque property and rolling life while avoiding processing of an excessively inclined raceway surface.
　また、このクロスローラ軸受は、外輪１の傾斜軌道面１ａの表面粗さＲａ及び内輪２の傾斜軌道面２ａの表面粗さＲａがそれぞれ０．３μｍ以下に設けられているため、ローラ３におけるピーリングの発生を抑制することができる。 Further, in this cross roller bearing, the surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 and the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 are each provided to be 0.3 μm or less, so that the peeling on the roller 3 is performed. Can be suppressed.
　また、このクロスローラ軸受は、外輪１の傾斜軌道面１ａの表面粗さＲａ及び内輪２の傾斜軌道面２ａの表面粗さＲａがそれぞれ０．１μｍ以上に設けられているため、前述のローラ３の端面３ａと傾斜軌道面１ａ間の滑り接触部での摩擦抵抗を抑制してトルク低減を図り、この摩擦による摩耗やローラ３でのピーリング発生を抑制して転がり寿命の向上を図りつつも、傾斜軌道面１ａ、２ａの過剰な加工を抑制して提供価格を抑えることもできる。 Further, since the cross roller bearing is provided with the surface roughness Ra of the inclined raceway surface 1a of the outer ring 1 and the surface roughness Ra of the inclined raceway surface 2a of the inner ring 2 of 0.1 μm or more, the above-mentioned roller 3 is provided. The frictional resistance at the sliding contact portion between the end surface 3a and the inclined track surface 1a is suppressed to reduce the torque, and the wear due to this friction and the occurrence of peeling on the roller 3 are suppressed to improve the rolling life. It is also possible to suppress excessive processing of the inclined track surfaces 1a and 2a to reduce the provided price.
　また、このクロスローラ軸受は、総ころ形式に設けられているため、特に高剛性のものとすることができる。総ころ形式は、保持器やスペーサがなく、傾斜軌道面１ａと２ａ間に収容可能な最大数のローラ３が組み込まれているので、隣り合うローラ３同士の接触が生じ、ローラ３の本数が多くなる。このため、総ころ形式のクロスローラ軸受は、使用回転速度が遅く、希薄潤滑条件下になり易い上に、ローラ３の端面３ａと傾斜軌道面１ａの滑り接触箇所の数も多くなる。上述のように傾斜軌道面１ａ、２ａの表面粗さＲａを適正化することにより、低トルク性や転がり寿命の向上を図りつつ、総ころ形式の採用により、軸受の高剛性化を図ることができ、これにより、ロボット用の減速機に特に好適なクロスローラ軸受にすることができる。 Moreover, since this cross roller bearing is provided in a full roller type, it can be made particularly highly rigid. In the full roller type, there is no cage or spacer, and the maximum number of rollers 3 that can be accommodated between the inclined track surfaces 1a and 2a is incorporated, so that the adjacent rollers 3 come into contact with each other and the number of rollers 3 increases. Will increase. For this reason, the full roller type cross roller bearing has a slow rotation speed and tends to be under dilute lubrication conditions, and also has a large number of sliding contact points between the end surface 3a of the roller 3 and the inclined raceway surface 1a. By optimizing the surface roughness Ra of the inclined raceway surfaces 1a and 2a as described above, it is possible to improve the low torque performance and the rolling life, and to improve the rigidity of the bearing by adopting the full roller type. This makes it possible to make a cross roller bearing particularly suitable for a speed reducer for a robot.
　今回開示された実施形態はすべての点で例示であって制限的なものではないと考えられるべきである。したがって、本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. Therefore, the scope of the present invention is shown by the scope of claims rather than the above description, and it is intended that all modifications within the meaning and scope equivalent to the scope of claims are included.
１　外輪
１ａ　傾斜軌道面
２　内輪
２ａ　傾斜軌道面
３　ローラ
３ａ　端面 1 Outer ring 1a Inclined track surface 2 Inner ring 2a Inclined track surface 3 Roller 3a End surface

Claims (4)

  1. 　互いに直交する一対の傾斜軌道面を内周面に有する外輪と、互いに直交する一対の傾斜軌道面を外周面に有する内輪と、前記外輪の一対の傾斜軌道面と前記内輪の一対の傾斜軌道面との間に、周方向に交互に傾斜方向が変わるように配置された複数のローラとを備えるクロスローラ軸受において、
    　前記外輪の傾斜軌道面の表面粗さＲａが前記内輪の傾斜軌道面の表面粗さＲａよりも小さく設けられていることを特徴とするクロスローラ軸受。     An outer ring having a pair of inclined raceway surfaces orthogonal to each other on the inner peripheral surface, an inner ring having a pair of inclined raceway surfaces orthogonal to each other on the outer peripheral surface, and a pair of inclined raceway surfaces of the outer ring and a pair of inclined raceway surfaces of the inner ring. In a cross-roller bearing provided with a plurality of rollers arranged so as to alternately change the inclination direction in the circumferential direction.
    A cross roller bearing characterized in that the surface roughness Ra of the inclined raceway surface of the outer ring is provided to be smaller than the surface roughness Ra of the inclined raceway surface of the inner ring.
  2. 　前記外輪の傾斜軌道面の表面粗さＲａ及び前記内輪の傾斜軌道面の表面粗さＲａがそれぞれ０．３μｍ以下に設けられている請求項１に記載のクロスローラ軸受。 The cross roller bearing according to claim 1, wherein the surface roughness Ra of the inclined raceway surface of the outer ring and the surface roughness Ra of the inclined raceway surface of the inner ring are each provided to be 0.3 μm or less.
  3. 　前記外輪の傾斜軌道面の表面粗さＲａ及び前記内輪の傾斜軌道面の表面粗さＲａがそれぞれ０．１μｍ以上に設けられている請求項２に記載のクロスローラ軸受。 The cross roller bearing according to claim 2, wherein the surface roughness Ra of the inclined raceway surface of the outer ring and the surface roughness Ra of the inclined raceway surface of the inner ring are each provided at 0.1 μm or more.
  4. 　総ころ形式に設けられている請求項１から３のいずれか１項に記載のクロスローラ軸受。 The cross roller bearing according to any one of claims 1 to 3 provided in the total roller type.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06264933A (en) * 1993-03-15 1994-09-20 Yaskawa Electric Corp Total roller type solid lubricating cross roller bearing
WO2017033396A1 (en) * 2015-08-26 2017-03-02 Thk株式会社 Slewing bearing
JP2020046008A (en) * 2018-09-20 2020-03-26 Ntn株式会社 Cross roller bearing

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06264933A (en) * 1993-03-15 1994-09-20 Yaskawa Electric Corp Total roller type solid lubricating cross roller bearing
WO2017033396A1 (en) * 2015-08-26 2017-03-02 Thk株式会社 Slewing bearing
JP2020046008A (en) * 2018-09-20 2020-03-26 Ntn株式会社 Cross roller bearing

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