JP2012180886A - Cage and rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cage that can suppress the generation of abrasion powders in the cage during a high speed operation and a rolling bearing equipped with the same.SOLUTION: The cage 14 of a magnesium alloy includes a connection 14a and a plurality of bearings 14b circumferentially disposed, mutually connected by the connection 14a, and formed with a pocket 14c for supporting a ball 13. Each of the bearings 14b is configured to allow the ball 13 to be detachably attached from the pocket 14c to the inner diameter D1 side of the cage 14.

Description

  The present invention relates to a cage and a rolling bearing, and more particularly to a cage made of a magnesium alloy and a rolling bearing including the cage.

  In recent years, resin cages are increasingly used as cages for rolling bearings used under high-speed operation. For example, Japanese Patent Application Laid-Open No. 2010-156439 (Patent Document 1) discloses a ball bearing that includes a crown-shaped cage made of synthetic resin and is used at high speed rotation.

  Furthermore, it has been proposed to use a magnesium alloy cage for the rolling bearing in order to improve the performance under high-speed operation. For example, Japanese Utility Model Publication No. 5-42753 (Patent Document 2) discloses a rolling bearing in which a cage is formed of a fiber reinforced magnesium alloy. Japanese Unexamined Patent Publication No. 2000-213544 (Patent Document 3) discloses a cage for a rolling bearing based on a magnesium alloy. Japanese Patent Laying-Open No. 2000-240659 (Patent Document 4) discloses a rolling bearing cage made of magnesium alloy. Japanese Patent Laying-Open No. 2006-300294 (Patent Document 5) discloses a rolling bearing cage made of a magnesium alloy in which a plurality of coating layers are formed by surface treatment.

JP 2010-156439 A Japanese Utility Model Publication No. 5-42753 JP 2000-213544 A Japanese Unexamined Patent Publication No. 2000-240659 JP 2006-3000294 A

  Since the centrifugal force increases in proportion to the square of the rotational speed, the centrifugal force increases under high speed operation. For this reason, the cage is deformed to increase its diameter under high speed operation. At this time, the inner diameter side of the cage deformed so as to increase the diameter is in strong sliding contact with the rolling element. Due to this sliding contact, the cage is worn, and wear powder of the cage is generated. Since the wear powder is caught between the cage and the rolling element, there is a problem that vibration and noise are generated and rotation accuracy is lowered.

  This invention is made | formed in view of the said subject, The objective is providing a cage | basket which can suppress generation | occurrence | production of the abrasion powder of a cage | basket | car under high speed operation, and a rolling bearing provided with the same. is there.

  A cage according to the present invention is a cage that holds rolling elements in a rolling bearing, and is made of a magnesium alloy, and is arranged along a circumferential direction and connected to each other by a coupling part. And a plurality of support portions formed with pocket portions for support. The support portion is configured such that the rolling element can be detached from the pocket portion toward the inner diameter side of the cage.

  The cage of the present invention is made of a magnesium alloy. Since the magnesium alloy has light weight and high elastic modulus, when used as a cage, deformation due to centrifugal force can be reduced. And according to the holder | retainer of this invention, the support part is comprised so that the ball | bowl as a rolling element can be detached | separated from a pocket part to the inner diameter side of a holder | retainer. For this reason, even when the cage is deformed by centrifugal force under high speed operation, the cage and the ball do not come into sliding contact with each other on the inner diameter side of the cage. Therefore, wear of the pocket portion does not occur on the inner diameter side of the pocket portion. Therefore, the wear powder of the cage is not generated on the inner diameter side. Thereby, generation | occurrence | production of the abrasion powder of a holder | retainer can be suppressed. For this reason, generation | occurrence | production of the vibration by generation | occurrence | production of an abrasion powder, generation | occurrence | production of noise, and the fall of rotational accuracy can be suppressed.

  Preferably, in the above cage, the support portion is configured to limit the movement of the rolling element so that the rolling element cannot be detached from the pocket portion toward the outer diameter side of the cage. Thereby, it is possible to prevent the cage from coming into contact with both the outer ring and the inner ring. Therefore, the cage can be used as a rolling element guide type cage. Therefore, it is possible to suppress the occurrence of tension compared to the outer ring guide type and the inner ring guide type. Moreover, since it can be used as a rolling element guide type, it is possible to give a margin to the dimensional accuracy of the cage as compared with the outer ring guide type and the inner ring guide type. Therefore, the cage can be easily manufactured. Therefore, the productivity of the cage can be improved.

  Preferably, in the above cage, the pocket portion is formed so that the inner diameter side of the cage reaches the inner peripheral end of the cage while maintaining a dimension larger than the diameter of the rolling element, and the outer diameter of the cage. The side has a portion having a size smaller than the diameter of the rolling element. Since the inner diameter side of the cage is formed so as to reach the inner peripheral end of the cage while maintaining a size larger than the diameter of the ball, the cage can be prevented from slidingly contacting the ball on the inner diameter side. Further, since the outer diameter side of the cage has a portion having a size smaller than the diameter of the ball, the cage can be brought into sliding contact with the ball on the outer diameter side.

  In the above cage, the pocket portion preferably includes a pocket surface capable of sliding contact with the rolling element, and the pocket surface has a concave shape portion capable of retaining the lubricant. For this reason, lubricants, such as lubricating oil or grease, can be hold | maintained at a concave shape part. As a result, it is possible to suppress instantaneous lubrication failure that occurs under high-speed rotation. For this reason, it is possible to suppress abnormal wear from instantaneous lubrication failure. Therefore, seizure resistance can be improved. Thereby, the high-speed driving | operation property of a rolling bearing can be improved by enabling the stable high-speed driving | operation.

  In the above cage, the magnesium alloy is preferably made of a flame retardant magnesium alloy. For this reason, the flame retardance of a cage can be improved. Therefore, it is possible to reduce the possibility that the cage is ignited by friction due to high-speed rotation.

  In the above cage, a surface treatment for imparting lubricity is preferably performed on the surface portion of the pocket portion that is in sliding contact with the rolling elements. For this reason, lubricity can be improved.

  In the above cage, the surface treatment is preferably an anodic oxidation treatment, and the surface roughness of the surface portion is 2.0 μmRa or less. For this reason, abrasion resistance can be improved. Thereby, the high-speed operability of the rolling bearing can be improved.

  In the above cage, the surface treatment is preferably a resin coating treatment, and a resin layer is provided on the surface portion. For this reason, abrasion resistance can be improved. Thereby, the high-speed operability of the rolling bearing can be improved.

  A rolling bearing according to the present invention includes the above cage, a rolling element held by the cage so as to be able to roll, and a race member disposed in contact with the rolling element. Since the cage is provided, it is possible to suppress the generation of wear powder on the cage under high speed operation. For this reason, generation | occurrence | production of the vibration by generation | occurrence | production of an abrasion powder, generation | occurrence | production of noise, and the fall of rotational accuracy can be suppressed.

  As described above, according to the cage and rolling bearing of the present invention, it is to provide a cage capable of suppressing the generation of wear powder in the cage under high speed operation and a rolling bearing provided with the cage. .

It is a schematic sectional drawing which shows the structure of the spindle vicinity of the machine tool provided with the rolling bearing in Embodiment 1 of this invention. It is a general | schematic fragmentary sectional view which shows the structure of the rolling bearing in Embodiment 1 of this invention. It is a top view which shows the structure of the holder | retainer of the rolling bearing in Embodiment 1 of this invention. It is a schematic sectional drawing which follows the IV-IV line of FIG. It is a schematic sectional drawing in alignment with the VV line of FIG. It is a general | schematic expanded sectional view which shows the P1 part of FIG. It is a schematic sectional drawing which shows the structure of the angular ball bearing in Embodiment 1 of this invention. It is a schematic sectional drawing of the holder | retainer of the comparative example 1 in the cross-sectional position corresponding to FIG. It is a general | schematic fragmentary sectional view which shows the structure of the rolling bearing in Embodiment 2 of this invention. It is a top view which shows the structure of the holder | retainer of the rolling bearing in Embodiment 2 of this invention. FIG. 11 is a schematic cross-sectional view corresponding to the P2 portion in FIG. 9 and taken along line XI-XI in FIG. 10. It is a top view which shows the structure of the holder | retainer of the comparative example 2 in Embodiment 2 of this invention. It is a schematic sectional drawing which follows the XIII-XIII line | wire of FIG. It is a general | schematic fragmentary sectional view which shows the structure of the rolling bearing in Embodiment 3 of this invention. It is a top view which shows the structure of the holder | retainer of the rolling bearing in Embodiment 3 of this invention. It is a schematic sectional drawing in alignment with the XVI-XVI line of FIG. It is a top view which shows the structure of the holder | retainer of the comparative example 3 in Embodiment 3 of this invention. It is a schematic sectional drawing of the holder | retainer in Embodiment 4 of this invention, Comprising: It is a schematic sectional drawing in the cross-sectional position corresponding to FIG. It is a general | schematic fragmentary sectional view which shows the structure of the rolling bearing in Embodiment 5 of this invention. It is a schematic sectional drawing in alignment with the XX-XX line of FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
First, the configuration of the machine tool according to Embodiment 1 of the present invention will be described.

  Referring to FIG. 1, a machine tool 90 in the present embodiment mainly includes a main shaft 91, a housing 92, a deep groove ball bearing 1, and an angular ball bearing 2. The main shaft 91 has a cylindrical shape. The housing 92 is provided so as to surround the outer peripheral surface of the main shaft 91. In the deep groove ball bearing 1 (rear bearing) and the angular ball bearing 2 (front bearing) as rolling bearings for machine tools, the outer ring 11 and the outer ring 21 of the outer ring 21 are in contact with the inner wall 92A of the housing, and the inner ring 12 The inner ring 22 is fitted between the main shaft 91 and the housing 92 so that each of the inner peripheral surfaces of the inner ring 22 contacts the outer peripheral surface 91 </ b> A of the main shaft 91. Thus, the main shaft 91 is supported so as to be rotatable about the axis with respect to the housing 92.

  In addition, a motor rotor 93B is installed on the main shaft 91 so as to surround a part of the outer peripheral surface 91A. A motor stator 93A is installed on the inner wall 92A of the housing 92 at a position facing the motor rotor 93B. The motor stator 93A and the motor rotor 93B constitute a motor 93 (built-in motor). Thus, the main shaft 91 can be rotated relative to the housing 92 by the power of the motor 93.

  That is, the deep groove ball bearing 1 and the angular ball bearing 2 are rolling bearings for machine tools that rotatably support the main shaft 91 of the machine tool 90 with respect to a housing 92 that is a member disposed so as to face the main shaft 91. It is.

  Next, the operation of the machine tool 90 will be described. Referring to FIG. 1, when power is supplied from a power source (not shown) to motor stator 93A of motor 93, a driving force for rotating motor rotor 93B around the axis is generated. Thus, the main shaft 91 rotatably supported by the angular ball bearing 2 and the deep groove ball bearing 1 with respect to the housing 92 rotates relative to the housing 92 together with the motor rotor 93B. Thus, by rotating the main shaft 91, a tool (not shown) attached to the tip 91B of the main shaft 91 can cut and grind the workpiece, thereby processing the workpiece.

  Next, the deep groove ball bearing 1 will be described. Referring to FIG. 2, the deep groove ball bearing 1 includes an outer ring 11 as a first race member, an inner ring 12 as a second race member, balls 13 as a plurality of rolling elements, and a cage 14. Yes. An outer ring rolling surface 11 </ b> A as an annular first rolling surface is formed on the inner peripheral surface of the outer ring 11. On the outer peripheral surface of the inner ring 12, an inner ring rolling surface 12A as an annular second rolling surface facing the outer ring rolling surface 11A is formed. The outer ring rolling surface 11A and the inner ring rolling surface 12A are each formed in a deep groove type. In addition, a ball rolling surface 13A (the surface of the ball 13) as a rolling element contact surface is formed on the plurality of balls 13. The balls 13 are in contact with the outer ring rolling surface 11A and the inner ring rolling surface 12A at the ball rolling surface 13A, and are arranged at a predetermined pitch in the circumferential direction by the crown-shaped cage 14. It is held on an annular track so as to be freely rollable. Thereby, the outer ring | wheel 11 and the inner ring | wheel 12 can rotate relatively mutually. The ball 13 is made of, for example, a steel ball.

  Here, with reference to FIG. 3 and FIG. 4, the holder | retainer 14 has the connection part 14a and the some support part 14b. In this embodiment, as an example, the retainer 14 is formed in a crown shape having a plurality of column portions protruding in the axial direction from the annular portion. The plurality of support portions 14b are arranged along the circumferential direction. The plurality of support portions 14b are connected to each other by a connection portion 14a. Each of the plurality of support portions 14b is formed with a pocket portion 14c for supporting the ball 13 as a rolling element. The support portion 14b is formed along the pocket portion 14c. In the present embodiment, a region indicated by a broken line in FIG. 4 corresponds to the support portion 14b. The support part 14b has a protrusion provided so as to protrude in the axial direction.

  A spherical concave shape is formed on the inner peripheral surface of each pocket portion 14c. In the present embodiment, as an example, eight pocket portions 14c are provided. The number of pocket portions 14c is not limited to this. The number of pocket portions 14c is not limited to an even number, and may be an odd number.

  As shown in FIG. 2, the length Lc of the column portion constituting the pocket portion 14 c is longer than ½ L with respect to the length L of the rolling element. The diameter L of the ball 13 corresponds to the length L of the rolling element. Conversely, the shorter the smaller the friction area, the smaller the heat generated in the entire deep groove ball bearing 1. On the other hand, if the length Lc of the column part is longer than 2 / 3L, it is difficult to assemble the deep groove ball bearing 1. For these reasons, the length Lc of the column portion constituting the pocket portion 14c is preferably 1 / 2L <Lc ≦ 2 / 3L.

  Referring to FIGS. 5 and 6, the retainer 14 is configured to retain the ball 13 in the pocket portion 14 c. The support portion 14b is configured to be able to remove the ball 13 from the pocket portion 14c to the inner diameter D1 side of the cage 14. The support portion 14b is configured not to slide on the ball 13 on the inner diameter D1 side of the cage 14. The pocket portion 14 c includes the center CP of the ball 13 and is configured to be able to remove the ball 13 from the virtual surface CS orthogonal to the radial direction of the cage 14 toward the inner diameter D1 of the cage 14. The pocket portion 14c is formed so that the inner diameter D1 side of the cage 14 reaches the inner peripheral end DE of the cage 14 while maintaining a dimension larger than the diameter DI of the ball 13.

  Moreover, the support part 14b is comprised so that the movement of the ball | bowl 13 may be restrict | limited so that the ball | bowl 13 cannot detach | leave from the pocket part 14c to the outer diameter D2 side of the holder | retainer 14. FIG. The pocket portion 14 c has a portion whose outer diameter D 2 side of the cage 14 is smaller than the diameter of the ball 13. The pocket portion 14 c is configured so that the ball 13 cannot be detached from the virtual surface CS including the center CP of the ball 13 and orthogonal to the radial direction of the cage 14 toward the outer diameter D2 of the cage 14.

  Further, in the present embodiment, the cage 14 does not restrain the ball 13 in the radial direction of the cage 14 on the inner diameter D1 side from the virtual pitch circle diameter (PCD) of the cage 14, and the outside of the cage 14. The ball 13 is configured to be restrained in the radial direction of the cage 14 on the diameter D2 side.

  The cage 14 is made of a magnesium (Mg) alloy. As the magnesium alloy, for example, a magnesium alloy such as ASTM standard AZ91 series, AZ92 series, and AM60 series can be applied. As the magnesium alloy, for example, a magnesium alloy having a melting point of 610 ° C. or less can be applied. The cage 14 can be formed by injection molding. The cage 14 may be formed by die casting. The cage 14 is preferably manufactured by injection molding after completely melting the magnesium alloy. In this case, the cage 14 has fine crystal grains and is excellent in the peelability.

  The magnesium alloy may be made of a flame retardant magnesium alloy. As such a flame-retardant magnesium alloy, a magnesium alloy in which about several percent of calcium (Ca) element is added to ASTM standard AZ-based magnesium alloy and AM-based magnesium alloy can be applied. By adding about 1 to 2% by mass of calcium element, the ignition point is increased by 200 ° C. or more. Flame retardancy in which about 1 to 2% of calcium element is blended with ASTM standard AZ91 and AZ92 based magnesium alloy in which about 6 to 9% by mass of aluminum (Al) element and about 1 to 2% of zinc (Zn) element are blended Magnesium alloys can be injection molded. In view of excellent injection moldability, anodizing property and corrosion resistance, a flame retardant magnesium alloy containing about 1% of calcium element is particularly preferable.

Moreover, when the cross section of the holder | retainer 14 is observed, the ratio of the alpha phase with a particle size of 20 micrometers or more in a magnesium alloy may be less than 15%. More preferably, when the cross section of the cage 14 is observed, the proportion of the α phase having a particle diameter of 20 μm or more in the magnesium alloy may be less than 5%. More preferably, when the cross section of the cage 14 is observed, the magnesium alloy may not contain an α phase having a particle size of 20 μm or more. Here, the state in which the α phase having a particle size of 20 μm or more is not included refers to a state in which the magnesium alloy does not substantially include an α phase having a particle size of 20 μm or more. Specifically, in the cross section of the cage 14, when four or more regions of 10 mm ² or more are observed at random and no α phase having a particle diameter of 20 μm or more is confirmed, the magnesium alloy constituting the cage 14 is substantially Is determined not to contain an α phase having a particle size of 20 μm or more.

  When such a retainer 14 is manufactured by injection molding, a magnesium alloy that is controlled to be in a liquid phase only state (a state that does not include an α phase, a completely molten state) by being heated to a temperature range higher than the melting point is a mold. The retainer 14 may be manufactured by being injected with respect to.

  Next, the angular ball bearing 2 will be described. With reference to FIG. 1 and FIG. 7, the angular ball bearing 2 and the deep groove ball bearing 1 have basically the same configuration and exhibit the same effects. However, the angular ball bearing 2 is different from the deep groove ball bearing 1 in the shape of the race and rolling elements.

  That is, the angular ball bearing 2 includes an outer ring 21 as a first race member, an inner ring 22 as a second race member, balls 23 as a plurality of rolling elements, and a cage 24. On the inner peripheral surface of the outer ring 21, an outer ring rolling surface 21A as an annular first rolling surface is formed. An inner ring rolling surface 22A as an annular second rolling surface facing the outer ring rolling surface 21A is formed on the outer peripheral surface of the inner ring 22. Moreover, the ball | bowl rolling surface 23A (surface of the ball | bowl 23) as a rolling-element contact surface is formed in the some ball | bowl 23. As shown in FIG. The balls 23 come into contact with each of the outer ring rolling surface 21A and the inner ring rolling surface 22A at the ball rolling surface 23A, and are arranged at a predetermined pitch in the circumferential direction by an annular retainer 24. It is rotatably held on an annular track. Thereby, the outer ring | wheel 21 and the inner ring | wheel 22 can rotate relatively mutually.

  Here, in the angular ball bearing 2, a straight line connecting a contact point between the ball 23 and the outer ring 21 and a contact point between the ball 23 and the inner ring 22 is a radial direction (a direction perpendicular to the rotation axis of the angular ball bearing 2). ). Therefore, it is possible to receive not only the radial load but also the axial load, and when the radial load is applied, the axial direction (the direction of the rotation axis of the angular ball bearing 2) is reduced. Power is generated. Referring to FIG. 1, in machine tool 90 of the present embodiment, two angular ball bearings 2 in the same direction are arranged on the front side (tip 91B side of main shaft 91) and on the rear side (motor rotor 93B side). Has two angular ball bearings 2 opposite to the front side to cancel the component force.

  Further, the cage 24 of the angular ball bearing 2 is different in shape from the cage 14 of the deep groove ball bearing 1 described above. The cage 14 of the deep groove ball bearing 1 is formed in a crown shape, while the cage 24 of the angular ball bearing 2 is formed in a cage shape. Note that the cage 24 may be formed in a crown shape like the cage 14 of the deep groove ball bearing 1 described above.

  Although the case where the deep groove ball bearing 1 is applied to the machine tool 90 has been described above, the deep groove ball bearing 1 is a turbocharger such as a hybrid turbocharger (electrically assisted turbocharger) as an application that requires high-speed operability. The present invention can be applied to a charger, an electric compressor, a motor, a gas turbine, and the like.

Next, the effect of this embodiment will be described in comparison with a comparative example.
Referring to FIG. 8, the cage 14 of Comparative Example 1 is made of a magnesium alloy. In the cage 14 of Comparative Example 1, the support portion 14b is configured to limit the movement of the ball 13 so that the ball 13 cannot be detached from the pocket portion 14c to both the inner diameter D1 side and the outer diameter D2 side of the cage 14. Has been. The pocket portion 14c is configured to be smaller than the diameter of the ball 13 on both the inner diameter D1 side and the outer diameter D2 side of the cage 14.

For example, in a device such as a turbocharger that is operated at a high speed of tens of thousands of revolutions min ⁻¹ or more, the cage 14 may be deformed so as to expand to the outer diameter D2 side due to centrifugal force during bearing operation. Further, the column portion in a cantilever state may be deformed so as to fall down toward the outer diameter D2. In the cage 14 of Comparative Example 1, the pocket portion 14c may be worn on the inner diameter D1 side of the pocket portion 14c due to the diameter expansion of the cage 14 due to the centrifugal force. Further, when the column part falls to the outer diameter D2 side, the pocket part 14c may be worn on the inner diameter D1 side of the pocket part 14c. Under high speed rotation, the restraining portion on the inner diameter D1 side of the cage 14 is pressed against the ball 13 with a very strong force. In this case, the generated wear powder may cause the vibration of the device, the generation of noise, and the rotation accuracy.

  In contrast, the cage 14 of the present embodiment is made of a magnesium alloy. Since the magnesium alloy has light weight and high elastic modulus, when it is used as the cage 14, it can reduce deformation due to centrifugal force. And as for the holder | retainer 14 of this Embodiment, the support part 14b is comprised so that the ball | bowl 13 as a rolling element can be detached | separated from the pocket part 14c to the inner diameter D1 side of the holder | retainer 14. FIG. For this reason, even when the cage 14 is deformed by centrifugal force under high speed operation, the cage 14 and the ball 13 do not slide in contact with the inner diameter D1 side of the cage 14. Therefore, the pocket portion 14c is not worn on the inner diameter D1 side of the pocket portion 14c. Therefore, the abrasion powder of the cage 14 is not generated on the inner diameter D1 side. Thereby, generation | occurrence | production of the abrasion powder of the holder | retainer 14 can be suppressed. For this reason, generation | occurrence | production of the vibration by generation | occurrence | production of an abrasion powder, generation | occurrence | production of noise, and the fall of rotational accuracy can be suppressed.

Further, since the retainer 14 does not have a restraining portion on the inner diameter D1 side, the column portion is reduced in weight. As a result, the weight of the column portion is reduced, so that deformation of the column portion due to centrifugal force is also suppressed.
For this reason, the reliability of the holder | retainer 14 can be improved.

  Further, in the cage 14 of the present embodiment, the support portion 14b moves the ball 13 as the rolling element so that the ball 13 as the rolling element cannot be detached from the pocket portion 14c to the outer diameter D2 side of the cage 14. Since it is configured to restrict, it is possible to prevent the retainer 14 from coming into contact with both the outer ring 11 and the inner ring 12. For this reason, the cage 14 can be used as a rolling element guide type cage 14. Therefore, it is possible to suppress the occurrence of tension compared to the outer ring guide type and the inner ring guide type. Moreover, since it can be used as a rolling element guide type, it is possible to give a margin to the dimensional accuracy of the cage 14 compared to the outer ring guide type and the inner ring guide type. Therefore, the retainer 14 can be easily manufactured. Therefore, the productivity of the cage 14 can be improved.

  Further, in the cage 14 of the present embodiment, the inner diameter D1 side of the cage 14 is formed so as to reach the inner peripheral end DE of the cage 14 while maintaining a dimension larger than the diameter DI of the ball 13. It is possible to prevent the retainer 14 from slidingly contacting the ball 13 on the inner diameter D1 side. Further, since the outer diameter D2 side of the cage 14 has a portion having a size smaller than the diameter DI of the ball 13, the cage 14 can be brought into sliding contact with the ball 13 on the outer diameter D2 side. In other words, since the retainer 14 does not have a restraining portion on the inner diameter D1 side, even when the retainer 14 is deformed under high speed operation, the retainer 14 and the ball 13 are not in sliding contact with the restraining portion on the inner diameter D1 side. can do. Further, it is possible to prevent the ball 13 from being detached from the pocket portion 14c to the outer diameter D2 side of the cage 14.

  In the cage 14 of the present embodiment, the magnesium alloy may be made of a flame retardant magnesium alloy. For this reason, the flame retardance of the retainer 14 can be improved. Accordingly, it is possible to reduce the possibility that the cage 14 is ignited by friction due to high-speed rotation.

  A bearing cage used under high-speed rotation needs to withstand particularly high cycle fatigue in addition to securing strength to withstand a large centrifugal force. Therefore, in order to ensure sufficient strength and fatigue characteristics of the cage 14, when the cross section of the cage 14 is observed, it is effective that the proportion of α phase having a particle diameter of 20 μm or more in the magnesium alloy is less than 15%. is there. When the cross section of the cage 14 is observed, the proportion of the α phase having a particle diameter of 20 μm or more in the magnesium alloy is more preferably less than 5%. Further, when the cross section of the cage 14 is observed, it is more preferable that the magnesium alloy does not contain an α phase having a particle size of 20 μm or more.

In a magnesium alloy to which aluminum is added, a compound such as MG ₁₇ Al ₁₂ having a hardness higher than that of the base material is generated as a precipitation phase at the grain boundary between such crystal grains. By preventing the generation of a coarse α phase as described above, this precipitated phase also becomes fine, so that uniform hardness is obtained, and conversely, since there is no low hardness portion derived from a large α phase, High wear resistance can be obtained stably on the sliding surface.

  The α phase (solid phase made of pure magnesium) having a particle size of 20 μm or more in the magnesium alloy becomes a factor for reducing the strength of the cage 14. Therefore, by reducing the proportion of the α phase having a particle diameter of 20 μm or more in the magnesium alloy constituting the cage 14, the strength at the weld portion and other than the weld portion is improved. More specifically, when the cross section of the cage 14 is observed, the strength of the cage 14 can be effectively improved by setting the proportion of the α phase having a particle diameter of 20 μm or more in the magnesium alloy to less than 15%. .

  By setting the ratio of the α phase having a particle size of 20 μm or more to less than 5%, the strength of the cage 14 can be further improved. Moreover, the intensity | strength of the holder | retainer 14 can be improved further by making the ratio of alpha phase with a particle size of 20 micrometers or more less than 2%. Moreover, the intensity | strength of the holder | retainer 14 can further be improved by not containing the alpha phase with a particle size of 20 micrometers or more.

  When the cage 14 is manufactured by injection molding, a magnesium alloy that is controlled to a liquid phase only state (a state that does not include an α phase; a completely molten state) by being heated to a temperature range equal to or higher than the melting point is It is preferably manufactured by being injected. Thereby, it is possible to provide a cage 14 made of a magnesium alloy that is more excellent in fatigue strength than the precipitation of coarsened α phase (α phase crystal grains). The coarse α phase as used herein means a crystal grain size of 20 μm or more, and sometimes exceeds 100 μm. Such a coarsened α phase is formed by coarsening an approximately spherical α phase generated in an injection molding cylinder in the course of cooling and solidification from injection of molding.

  Since the deep groove ball bearing 1 as the rolling bearing of the present embodiment includes the cage 14 described above, it is possible to suppress the generation of wear powder in the cage 14 under high speed operation. For this reason, generation | occurrence | production of the vibration by generation | occurrence | production of an abrasion powder, generation | occurrence | production of noise, and the fall of rotational accuracy can be suppressed. Therefore, the deep groove ball bearing 1 of the present embodiment is not only excellent in high-speed driving resistance and light weight, but also can improve the reliability of the rolling bearing, because the cage 14 is made of a magnesium alloy.

(Embodiment 2)
The second embodiment of the present invention is mainly different from the first embodiment in that it is a double row cylindrical roller bearing and a comb cage. Except for these, the second embodiment is the same as the first embodiment, and the same or corresponding portions are denoted by the same reference numerals and description thereof will not be repeated.

  With reference to FIG. 9, the double row cylindrical roller bearing 1 is demonstrated. The double row cylindrical roller bearing 1 includes an outer ring 11 as a first race member, an inner ring 12 as a second race member, a cylindrical roller 13 as a plurality of rolling elements, and a cage 14. On the inner peripheral surface of the outer ring 11, outer ring rolling surfaces 11A as first annular rolling surfaces are formed in double rows (two rows). On the outer peripheral surface of the inner ring 12, inner ring rolling surfaces 12 </ b> A are formed in a double row (two rows) as an annular second rolling surface facing each of the double row (two rows) outer ring rolling surfaces 11 </ b> A. ing. The plurality of cylindrical rollers 13 are formed with cylindrical roller transfer surfaces 13A (outer peripheral surfaces of the cylindrical rollers 13) as rolling element rolling surfaces. The cylindrical roller 13 is in contact with each of the outer ring rolling surface 11A and the inner ring rolling surface 12A at the cylindrical roller rolling surface 13A, and is arranged at a predetermined pitch in the circumferential direction by an annular retainer 14. Thus, it is held so as to be able to roll on two rows of circular orbits. Thereby, the outer ring | wheel 11 and the inner ring | wheel 12 can rotate relatively mutually.

  Here, with reference to FIG. 10 and FIG. 11, the cage 14 is made of a magnesium alloy, and includes a connecting portion 14 a and a plurality of supporting portions 14 b. In the present embodiment, as an example, the retainer 14 is formed in a comb shape having a plurality of column portions protruding in the axial direction from the annular portion. The plurality of support portions 14b are arranged along the circumferential direction. The plurality of support portions 14b are connected to each other by a connection portion 14a. Each of the plurality of support portions 14b is formed with a pocket portion 14c for supporting the cylindrical roller 13 as a rolling element. The support portion 14b is formed along the pocket portion 14c. The support portion 14b is configured such that the cylindrical roller 13 can be detached from the pocket portion 14c toward the inner diameter D1 of the cage 14.

  The pocket portion 14c is provided in a tapered shape so that the interval between the opposing support portions 14b becomes wider toward the inner diameter D1 side of the cage 14. The pocket portion 14 c is formed along the outer peripheral surface of the cylindrical roller 13 so that the outer diameter D <b> 2 side of the cage 14 is smaller than the diameter of the cylindrical roller 13. The pocket portion 14c includes the center CP of the cylindrical roller 13, and is configured so that the cylindrical roller 13 can be detached from the virtual surface CS orthogonal to the radial direction of the cage 14 toward the inner diameter D1 of the cage 14. The cylindrical roller 13 is configured so that it cannot be detached toward the diameter D2.

  The pocket portion 14 c has a pocket surface 14 c 1 that can slide in contact with the cylindrical roller 13. The pocket surface 14c1 is provided on the outer diameter D2 side of the cage 14. The pocket surface 14c1 has a concave portion 14c2 that can hold the lubricant. The concave portion 14c2 is formed on the end surface of the pocket surface 14c1. The concave portion 14c2 is provided so as to extend from the tip of the column portion toward the root. The concave portion 14c2 is provided from the tip of the column portion to the middle of the column portion.

  A projecting portion 14d is formed between the opposing support portions 14b so as to project in the axial direction from the annular portion. The protrusion 14d is provided so as to support one end surface of the cylindrical roller 13. In the present embodiment, as an example, eleven pocket portions 14c are provided. The number of pocket portions 14c is not limited to this.

  As shown in FIG. 2, in the double row cylindrical roller bearing 1, two cages are provided so that surfaces opposite to the side from which the column portion of the annular portion protrudes face each other, and the central axes thereof coincide with each other. 14 is incorporated. Moreover, the length Lc of the column part which comprises the pocket part 14c has preferable 1 / 2L <Lc <= 2 / 3L. The length L of this rolling element corresponds to the length of the cylindrical roller 13.

Next, the effect of this embodiment will be described in comparison with a comparative example.
Referring to FIGS. 12 and 13, the cage 14 of Comparative Example 2 is made of a magnesium alloy, and the support portion 14 b is cylindrical from the pocket portion 14 c to both the inner diameter D1 side and the outer diameter D2 side of the cage 14. The movement of the cylindrical roller 13 is limited so that the roller 13 cannot be separated. The pocket portion 14c is configured to be smaller than the diameter of the cylindrical roller 13 on both the inner diameter D1 side and the outer diameter D2 side of the cage 14. In the cage 14 of Comparative Example 2, wear of the pocket portion 14c occurs on the inner diameter D1 side when the diameter of the cage 14 is increased by centrifugal force under high-speed operation and the column portion falls to the outer diameter D2 side. There is a case.

  In contrast, the cage 14 of the present embodiment is made of a magnesium alloy, and the support portion 14b is configured to be able to detach the ball 13 as a rolling element from the pocket portion 14c to the inner diameter D1 side of the cage 14. Has been. For this reason, the deformation due to the centrifugal force can be reduced, and even when the cage 14 is deformed by the centrifugal force under high speed operation, the cage 14 and the ball 13 do not slide in contact with the inner diameter D1 side of the cage 14. . Therefore, the pocket portion 14c is not worn on the inner diameter D1 side of the pocket portion 14c. Therefore, since generation | occurrence | production of the abrasion powder of the holder | retainer 14 can be suppressed, generation | occurrence | production of the vibration by generation | occurrence | production of abrasion powder, generation | occurrence | production of noise, and the fall of a rotation precision can be suppressed.

  Further, in a magnesium alloy comb cage, when incorporated in a rolling bearing, a cylindrical roller which is a rolling element can be inserted by a so-called squeeze as in the case of a resin comb cage. In this case, in the case of the shape having the restraining portion on the inner diameter D1 side of the retainer 14 as in the comparative example 2, the end portion of the cylindrical roller 13 and the inner peripheral side of the pocket portion 14c may be rubbed strongly when being held. As a result, the sliding contact portion of the retainer 14 is scraped, and relatively large wear powder may be mixed into the rolling bearing during assembly of the rolling bearing.

  On the other hand, in the cage 14 of the present embodiment, the support portion 14b is configured to be able to remove the cylindrical roller 13 as a rolling element from the pocket portion 14c to the inner diameter D1 side of the cage 14, so that the cylinder 14 is cylindrical. By incorporating the roller 13 from the inner diameter D1 side, it is possible to prevent the sliding contact portion of the retainer 14 from being scraped and generating relatively large wear powder. For this reason, generation | occurrence | production of the vibration by the abrasion powder mixed in the rolling bearing 1, generation | occurrence | production of noise, and the fall of rotation accuracy can be suppressed. Further, by incorporating the cylindrical roller 13 from the inner diameter D1 side, the assemblability can be improved as compared with the case.

  As the lubrication method, lean lubrication such as mist oil lubrication or grease lubrication is used. Rolling bearings used for motors or machine tool spindles are required to operate with a small amount of lubricating oil or grease in order to reduce torque and heat. Under such conditions, the lubrication between the pocket portion 14c and the cylindrical roller 13 is severe under high speed operation. Therefore, in such a condition, in the cage 14 of Comparative Example 2, there is a high possibility that an instantaneous lubrication failure will occur due to lack of lubricating oil or grease.

  On the other hand, in the cage 14 of the present embodiment, the pocket surface 14c1 has the concave shape portion 14c2 capable of holding the lubricant, and therefore, lubricant such as lubricating oil or grease is applied to the concave shape portion 14c2. Can be held in. As a result, it is possible to suppress instantaneous lubrication failure that occurs under high-speed rotation. For this reason, it is possible to suppress abnormal wear from instantaneous lubrication failure. Therefore, seizure resistance can be improved. Thereby, the high-speed driving | operation property of a rolling bearing can be improved by enabling the stable high-speed driving | operation.

  Further, the lubricating oil or grease moves more to the outer diameter D2 side of the cage 14 due to centrifugal force during high-speed operation. In the cage 14 according to the present embodiment, these lubricants easily intervene in the sliding portion with the cylindrical roller 13. Since the recessed portion 14c2 is provided in the pocket surface 14c1 located on the outer diameter D2 side of the cage 14, these intervening lubricants can be effectively retained. Therefore, drivability can be improved particularly under lean lubrication conditions.

Further, the amount of collapse of the cage column was calculated by FEM (Finite Element Method) analysis. In the calculation, Comparative Example 2 and the cage 14 of the present embodiment were applied to an NN3020 double row cylindrical roller bearing (PCD φ 126 mm, column length Lc = 0.7 L). Rotation speed was 16000 rotating min ^-1. As a result of the calculation, the amount of collapse of the retainer column portion of Comparative Example 2 was 250 μm, and the amount of collapse of the retainer column portion of the present embodiment was 260 μm. For FEM analysis, I-DEAS manufactured by Siemens PLM Software was used. The magnesium alloy of the cage 14 of Comparative Example 2 and the present embodiment was calculated with a density of 1.82 g / cm ³ and an elastic modulus of 45 GPa. In the cage 14 of the present embodiment, the column portion is thinner than the cage 14 of Comparative Example 2, but since the weight is reduced, the amount of deformation becomes smaller. Further, when the column portion length Lc of the cage 14 of the present embodiment is shortened to 0.52 L, the deformation amount is further reduced to 120 μm. For this reason, it becomes the holder | retainer 14 excellent in the deformability at the time of very high-speed driving | operation.

(Embodiment 3)
The third embodiment of the present invention is mainly different from the first embodiment in that it is a single row cylindrical roller bearing and a cage cage. Except for these, the second embodiment is the same as the first embodiment, and the same or corresponding portions are denoted by the same reference numerals and description thereof will not be repeated.

  The cylindrical roller bearing 1 will be described with reference to FIG. The cylindrical roller bearing 1 includes an outer ring 11 as a first race member, an inner ring 12 as a second race member, a cylindrical roller 13 as a plurality of rolling elements, and a cage 14. The outer ring 11 is formed with an outer ring rolling surface 11A as an annular first rolling surface. The inner ring 12 is formed with an inner ring rolling surface 12A as an annular second rolling surface facing the outer ring rolling surface 11A. The plurality of cylindrical rollers 13 are formed with cylindrical roller rolling surfaces 13A (outer circumferential surfaces of the cylindrical rollers 13) as rolling element rolling surfaces. The cylindrical roller 13 is in contact with each of the outer ring rolling surface 11A and the inner ring rolling surface 12A at the cylindrical roller rolling surface 13A, and is arranged at a predetermined pitch in the circumferential direction by an annular retainer 14. Thus, it is held on an annular track so as to be freely rollable. Thereby, the outer ring | wheel 11 and the inner ring | wheel 12 can rotate relatively mutually.

  Here, with reference to FIG. 15 and FIG. 16, the retainer 14 is made of a magnesium alloy, and includes a connecting portion 14 a and a plurality of support portions 14 b. In the present embodiment, as an example, the cage 14 is formed in a cage shape having a plurality of column portions protruding in the axial direction so as to connect the annular portions facing each other. The plurality of support portions 14b are arranged along the circumferential direction. The plurality of support portions 14b are connected to each other by a connection portion 14a. Each of the plurality of support portions 14b is formed with a pocket portion 14c for supporting the cylindrical roller 13 as a rolling element. The support portion 14b is formed along the pocket portion 14c. The support portion 14b is configured such that the cylindrical roller 13 can be detached from the pocket portion 14c toward the inner diameter D1 of the cage 14.

  The pocket portion 14c is provided in a tapered shape so that the interval between the opposing support portions 14b becomes wider toward the inner diameter D1 side of the cage 14. The pocket portion 14c is provided between the opposed annular portions. The pocket portion 14 c is formed along the outer peripheral surface of the cylindrical roller 13 so that the outer diameter D <b> 2 side of the cage 14 is smaller than the diameter of the cylindrical roller 13. The pocket portion 14c includes the center CP of the cylindrical roller 13, and is configured so that the cylindrical roller 13 can be detached from the virtual surface CS orthogonal to the radial direction of the cage 14 toward the inner diameter D1 of the cage 14. The cylindrical roller 13 is configured so that it cannot be detached toward the diameter D2.

  A projecting portion 14d is formed between the opposing support portions 14b so as to project in the axial direction from the annular portion. The protrusion 14d is provided so as to support one end surface of the cylindrical roller 13. In the present embodiment, as an example, ten pocket portions 14c are provided. The number of pocket portions 14c is not limited to this.

Next, the effect of this embodiment will be described in comparison with a comparative example.
Referring to FIG. 17, the retainer 14 of Comparative Example 3 is made of a magnesium alloy, and the support portion 14 b is separated from the pocket portion 14 c to both the inner diameter D1 side and the outer diameter D2 side of the retainer 14. The movement of the cylindrical roller 13 is limited so as not to be performed. The pocket portion 14c is configured to be smaller than the diameter of the cylindrical roller 13 on both the inner diameter D1 side and the outer diameter D2 side of the cage 14. In the cage type cage, the cage 14 is deformed so as to expand its diameter by centrifugal force under high speed operation. For this reason, in the cage 14 of Comparative Example 3, wear of the pocket portion 14c may occur on the inner diameter D1 side due to the diameter of the cage 14 being increased by centrifugal force under high speed operation.

  In contrast, the cage 14 of the present embodiment is made of a magnesium alloy, and the support portion 14b is configured to be able to detach the ball 13 as a rolling element from the pocket portion 14c to the inner diameter D1 side of the cage 14. Has been. For this reason, it can reduce that it deforms so that it may expand by centrifugal force, and even when it deform | transforms so that the retainer 14 may expand by centrifugal force under high-speed operation, in the inner diameter D1 side of the retainer 14 The cage 14 and the ball 13 are not in sliding contact. Therefore, the pocket portion 14c is not worn on the inner diameter D1 side of the pocket portion 14c. Therefore, since generation | occurrence | production of the abrasion powder of the holder | retainer 14 can be suppressed, generation | occurrence | production of the vibration by generation | occurrence | production of abrasion powder, generation | occurrence | production of noise, and the fall of a rotation precision can be suppressed.

(Embodiment 4)
The fourth embodiment of the present invention is mainly different from the first embodiment in that a surface treatment is applied to the cage in order to suppress the generation of wear powder. Except for these, the second embodiment is the same as the first embodiment, and the same or corresponding portions are denoted by the same reference numerals and description thereof will not be repeated.

  Referring to FIG. 18, the crown-shaped cage 14 is subjected to a surface treatment for imparting lubricity to the cage 14. The surface treatment is applied to at least the surface portion SP in sliding contact with the rolling elements of the pocket portion 14c. An anodizing treatment can be applied as the surface treatment. The thickness of the anodized layer is, for example, 3 μm or more and 20 μm or less. In this case, the surface roughness of the surface portion SP is preferably 0.2 μmRa or less, for example. Here, Ra is the arithmetic average roughness of the JIS standard. If the surface roughness does not affect the lubricity under high speed operation, the surface roughness is not particularly limited, but the surface roughness is 0.2 μmRa or less in consideration of the retention of the lubricant and the lubricity. Is preferred.

  Moreover, a resin coat process may be applied as the surface treatment. In this case, a resin layer is provided on the surface portion SP. The thickness of the resin layer is, for example, 5 μm or more and 30 μm or less. The resin coating treatment can be performed by, for example, electrodeposition coating. As a material for the resin layer, polyamide-imide resin, polyamide resin, epoxy resin, or the like can be applied. The resin coating treatment improves the familiarity and self-lubrication when the lubricant is insufficient. An anodizing treatment may be performed to form the base of the resin layer. In this case, a resin coating process may be performed after the anodizing process.

Next, the effect of this Embodiment is demonstrated.
In the cage 14 according to the present embodiment, the surface portion SP that is in sliding contact with the rolling elements of the pocket portion 14c is subjected to surface treatment for imparting lubricity, so that the lubricity can be improved.

  Further, in the cage 14 of the present embodiment, the surface treatment is an anodizing treatment, and the surface roughness of the surface portion SP is 2.0 μmRa or less, so that the wear resistance can be improved. Thereby, the high-speed operability of the rolling bearing can be improved.

  Further, in the cage 14 of the present embodiment, the surface treatment is a resin coating treatment, and since the resin layer is provided on the surface portion SP, the wear resistance can be improved. Thereby, the high-speed operability of the rolling bearing can be improved.

(Embodiment 5)
The fifth embodiment of the present invention is mainly different from the first embodiment in that it is a thrust ball bearing and the shape of the cage. Except for these, the second embodiment is the same as the first embodiment, and the same or corresponding portions are denoted by the same reference numerals and description thereof will not be repeated.

  Referring to FIG. 19, the thrust ball bearing 1 includes a shaft washer 31 as a first race member, a housing washer 32 as a second race member, balls 13 as a plurality of rolling elements, and a cage 14. And. An axial raceway rolling surface 31A as an annular first rolling surface is formed on the axial raceway 31. The housing washer 32 is formed with a housing washer rolling surface 32A as an annular second rolling surface facing the axial washer rolling surface 31A. Further, a ball rolling surface 13 </ b> A (an outer peripheral surface of the ball 13) as a rolling element rolling surface is formed on the plurality of balls 13. The balls 13 are in contact with each of the shaft raceway rolling surface 31A and the housing raceway rolling surface 32A at the ball rolling surface 13A, and are arranged at a predetermined pitch in the circumferential direction by the annular cage 14. Thus, it is held on an annular track so as to be freely rollable. Thereby, the shaft washer 31 and the housing washer 32 are rotatable relative to each other.

  Here, with reference to FIG. 15 and FIG. 16, the retainer 14 is made of a magnesium alloy, and includes a connecting portion 14 a and a plurality of support portions 14 b. In the present embodiment, as an example, the cage 14 is formed in a cylindrical shape. The cage 14 is configured such that the balls 13 are held on the inner peripheral side of the cylindrical shape. The plurality of support portions 14b are arranged along the circumferential direction. The plurality of support portions 14b are connected to each other by a connection portion 14a. Each of the plurality of support portions 14b is formed with a pocket portion 14c for supporting the ball 13 as a rolling element. The support portion 14b is formed along the pocket portion 14c. In the present embodiment, a region indicated by a broken line in FIG. 20 corresponds to the support portion 14b. The support portion 14b is configured to be able to remove the ball 13 from the pocket portion 14c to the inner diameter D1 side of the cage 14.

  The pocket portion 14c is provided in a tapered shape so that the interval between the opposing support portions 14b becomes wider toward the inner diameter D1 side of the cage 14. Further, the pocket portion 14 c is formed so that the outer diameter D <b> 2 side of the cage 14 surrounds the outer peripheral surface of the ball 13. The pocket portion 14c is configured so that the ball 13 can be detached toward the inner diameter D1 side of the cage 14, and is configured so that the ball 13 cannot be detached toward the outer diameter D2 side. In the present embodiment, as an example, eight pocket portions 14c are provided. The number of pocket portions 14c is not limited to this.

  The cage 14 of the present embodiment is made of a magnesium alloy, and the support portion 14b is configured to be able to remove the balls 13 as rolling elements from the pocket portion 14c to the inner diameter D1 side of the cage 14. For this reason, it can reduce that it deforms so that it may expand by centrifugal force, and even when it deform | transforms so that the retainer 14 may expand by centrifugal force under high-speed operation, in the inner diameter D1 side of the retainer 14 The cage 14 and the ball 13 are not in sliding contact. Therefore, the pocket portion 14c is not worn on the inner diameter D1 side of the pocket portion 14c. Therefore, since generation | occurrence | production of the abrasion powder of the holder | retainer 14 can be suppressed, generation | occurrence | production of the vibration by generation | occurrence | production of abrasion powder, generation | occurrence | production of noise, and the fall of a rotation precision can be suppressed.

The above-described embodiment of the present invention is combined in a timely manner.
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied particularly advantageously to a cage made of a magnesium alloy and a rolling bearing provided with the same.

  DESCRIPTION OF SYMBOLS 1 Rolling bearing, 2 Angular contact ball bearing, 11 Outer ring, 11A Outer ring rolling surface, 12 Inner ring, 12A Inner ring rolling surface, 13 Rolling body, 13A Rolling body transfer surface, 14 Cage, 14a Connection part, 14b Support part, 14c Pocket part, 14c1 Pocket surface, 14c2 Concave shape part, 14d Projection part, 21 Outer ring, 21A Outer ring rolling surface, 22 Inner ring, 22A Inner ring rolling surface, 23 balls, 23A Ball rolling surface, 24 Cage, 31 Axis track Board, 31A shaft washer rolling surface, 32 housing washer, 32A housing washer rolling surface, 90 machine tool, 91 spindle, 91A outer peripheral surface, 91B tip, 92 housing, 92A inner wall, 93 motor, 93A motor stator, 93B Motor rotor, D1 inner diameter, D2 outer diameter, SP surface portion.

Claims (9)

A cage for holding rolling elements in a rolling bearing,
Made of magnesium alloy,
A connecting portion;
A plurality of support portions arranged along a circumferential direction and connected to each other by the connection portions, and formed with pocket portions for supporting the rolling elements,
The said support part is a holder | retainer comprised so that the said rolling element can be detached | separated from the said pocket part to the internal-diameter side of the said holder | retainer.   The retainer according to claim 1, wherein the support portion is configured to limit movement of the rolling element so that the rolling element cannot be detached from the pocket portion toward the outer diameter side of the retainer.   The pocket portion is formed such that the inner diameter side of the cage reaches the inner peripheral end of the cage while maintaining a size larger than the diameter of the rolling element, and the outer diameter side of the cage is the rolling side. The cage according to claim 2, wherein the cage has a portion having a size smaller than a diameter of the moving body. The pocket portion includes a pocket surface capable of sliding contact with the rolling element,
The cage according to any one of claims 1 to 3, wherein the pocket surface has a concave portion capable of holding a lubricant.   The cage according to any one of claims 1 to 4, wherein the magnesium alloy is made of a flame retardant magnesium alloy.   The cage according to any one of claims 1 to 5, wherein a surface treatment for imparting lubricity is applied to a surface portion of the pocket portion that is in sliding contact with the rolling elements. The surface treatment is anodizing;
The cage according to claim 6, wherein the surface portion has a surface roughness of 2.0 μmRa or less. The surface treatment is a resin coating treatment;
The cage according to claim 6 or 7, wherein a resin layer is provided on the surface portion. The cage according to any one of claims 1 to 8,
The rolling element held in a rollable manner by the cage;
A rolling bearing comprising a raceway member disposed in contact with the rolling element.

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