JP2015232382A - Cage for rolling bearing and rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cage for a rolling bearing which can be manufactured by a simple process, hardly causes the imbalance of the cage, and can prevent the breakage of the cage caused by hoop stress or the like at high rotation, and the rolling bearing incorporated with the cage.SOLUTION: A cage 1 for a rolling bearing is composed of a circular cage main body 2 having pockets for holding rolling bodies, and metal-made ring plates 3 fixed to both end faces of the cage main body 2. The cage main body 2 is a compression-molded body of a resin material, the ring plates 3 are integrated with the cage main body 2 at compression-molding, and the resin material is formed by blending at least one fibrous reinforcing material selected from a glass fiber and a carbon fiber to a polytetrafluoroethylene resin being a base resin, and if necessary, by blending at least one inorganic filling material selected from a magnesium oxide and calcium carbonate to the polytetrafluoroethylene resin.

Description

  The present invention relates to a rolling bearing cage used for high-temperature rotation and for cryogenic and vacuum environments, and a rolling bearing incorporating the cage.

  A rolling bearing such as an angular ball bearing is used for a rotation support portion of a turbo pump for liquid fuel used in a rocket engine. This rolling bearing is used in a high-speed rotation environment in a liquid propellant. In particular, since the temperature becomes extremely low in an environment such as liquid hydrogen or liquid oxygen, ordinary fluid lubricants such as oil and grease cannot be applied. Since it is used at high speed rotation, the cage is required to have a high specific strength capable of withstanding the hoop stress. In addition, if the inertial force generated when the satellite changes its direction acts on the rotating part of the satellite, a moment load is generated on the bearing used in the rotating part, and the rolling element and the cage that holds it are also very A large load is applied. This also requires high specific strength and high rigidity for the cage.

  Furthermore, since the rocket engine that will be developed in the future will be used for reusable rockets and manned rockets, it will be necessary to improve reliability more than before, and it will have functions and performance that can reduce costs and recover rockets. Consideration for the environment is also being considered. Therefore, the rolling bearing used in the rocket engine is required to have a long life and cost reduction.

  Conventionally, a glass woven fabric impregnated with polytetrafluoroethylene (hereinafter referred to as PTFE) resin as a base material is used as a cage for a rolling bearing used in a cryogenic and high-speed rotating environment, and a glass fiber on the surface layer is used. A cage that has been dissolved by hydrofluoric acid treatment has been devised (see Patent Document 1). By using this cage for the bearing, the strength is made of glass woven fabric, and the self-lubricating property and the transferability to the sliding counterpart material are secured by the impregnated PTFE resin.

  Further, a cage has been devised in which a cage base material is an aluminum alloy and a coating film mainly composed of PTFE resin is used on the cage pocket surface and the outer diameter surface (see Patent Document 2). By using this cage for the bearing, the strength is made of an aluminum alloy, and the coating film mainly composed of PTFE resin ensures high transferability and wear resistance.

  In addition, the first resin composition and the second resin composition are used, the retainer base material is formed from the first resin composition, the pocket portion is formed from the second resin composition, and the pocket portion is formed into the retainer. A cage mounted on a base material has been proposed (see Patent Document 3). Here, the first resin composition is a resin composite material containing a polyether ether ketone resin having a certain mechanical strength and wear characteristics as a main component and a fiber reinforcing material for imparting wear resistance. The second resin composition is a resin composite material mainly composed of a PTFE resin having self-lubricating properties.

Japanese Patent Publication No. 2-20854 JP 2006-220240 A JP 2007-239935 A

  In the cage of Patent Document 1, as described above, a material obtained by performing hydrofluoric acid treatment on a glass woven fabric impregnated with PTFE resin is used. In this case, if the wear progresses more than the hydrofluoric acid treatment layer on the surface of the cage, the glass fiber may be exposed and the rolling elements and the raceway may be damaged. Moreover, since the glass woven fabric of the cage surface layer is dissolved by the hydrofluoric acid treatment, the cage strength decreases. In addition, increasing the hydrofluoric acid treatment layer in order to increase the life of the bearing and improve the reliability against wear causes an increase in the hydrofluoric acid treatment time and increases the manufacturing cost.

  In the cage of Patent Document 2, as described above, an aluminum alloy is employed for the cage base material, and a PTFE resin coating film is employed for the pocket surface and the guide surface. In this case, it is necessary to increase the coating film thickness in order to improve the reliability of the bearing for a longer service life. To that end, it is necessary to repeat the cycle of “coating, drying, and firing” multiple times. Long lead time. In addition, in order to secure a reference surface for finishing processing after coating, masking is required on the non-functional surface, which is difficult to manufacture.

  In the cage of Patent Document 3, as described above, the PEEK resin composite material is used for the cage base material and the PTFE resin composite material is used for the pocket portion. In this case, since the PTFE resin composite material to be attached to the pocket portion is manufactured individually, a mutual difference occurs, which may be an unbalance factor. Moreover, since there is a difference between the linear expansion coefficients of the cage base material and the pocket member, the attached pocket member may fall off due to a temperature change of the cage during operation. Furthermore, since the annular retainer base material is manufactured by injection molding, it has a weld, and depending on the use conditions, there is a risk of damage at the portion.

  The present invention has been made to cope with such a problem, and can be manufactured by a simple process, is less likely to cause unbalance of the cage, and prevents the cage from being damaged due to hoop stress during high-speed rotation. An object of the present invention is to provide a cage for a rolling bearing that can be produced, and a rolling bearing incorporating the cage.

  A rolling bearing retainer according to the present invention is a rolling bearing retainer for retaining a rolling element in a rolling bearing, and the retainer includes an annular retainer body having a pocket for retaining the rolling element, and the retainer. It consists of metal ring plates fixed to both end faces of the cage body, and the cage body is a compression molded body of a resin material. In particular, the ring plate is integrated with the cage body at the time of compression molding of the cage body.

  The resin material is characterized in that at least one fibrous reinforcing material selected from glass fibers and carbon fibers is blended with a polytetrafluoroethylene resin as a base resin.

  The metal material of the ring plate is an aluminum alloy, magnesium alloy, titanium alloy, carbon steel, or copper alloy.

  The ring plate has a notch on at least one surface selected from an inner diameter surface and an outer diameter surface, and the retainer body is in a state of being fitted into the notch.

  The rolling bearing of the present invention is a rolling bearing having a rolling element and a cage that holds the rolling element, and the cage is the above-described rolling bearing cage of the present invention. Further, the rolling bearing is a bearing used for a rotation support portion of a turbo pump for liquid fuel of a rocket engine.

  The rolling bearing retainer of the present invention comprises an annular retainer body having a pocket for retaining a rolling element, and a metal ring plate fixed to both end faces of the retainer body. Since this is a compression molded body of resin material, the cage body does not have a weld like an injection molded body, and the reinforcing effect of the ring plate can prevent the cage body from being damaged by hoop stress during high-speed rotation. In addition, since the cage body including the pocket surface is integrally formed of a single material, the cage is less likely to be unbalanced, and the tolerance for wear increases, contributing to a longer life of the bearing. Further, by integrating the ring plate during compression molding of the cage body, the manufacturing process can be simplified and the cost can be greatly reduced.

  In addition, by adopting a resin material with self-lubricating property and transferability to the sliding counterpart material, the cage body wears during operation, and the self-impact from the pocket surface to the rolling elements and bearing raceway surface. Components can be transferred and contribute to bearing lubrication. Thereby, it can utilize suitably as a cage | basket of the rolling bearing used in the cryogenic and high-speed rotation environment which contact | connects liquid hydrogen and liquid oxygen which are liquid propellants.

It is an axial sectional view and an A direction arrow view of an outer ring guide type angular ball bearing which is an example of a rolling bearing of the present invention. It is a perspective view of the holder | retainer in the rolling bearing of FIG. It is a figure which shows only a ring plate. It is sectional drawing which shows the other shape of the notch part in a ring plate. It is a schematic diagram which shows the manufacturing process of the cage for rolling bearings of this invention.

  A rolling bearing cage and a rolling bearing according to the present invention will be described with reference to FIGS. FIG. 1 is an axial sectional view (FIG. 1 (a)) and an A-direction view (FIG. 1 (b)) of an angular ball bearing which is an example of the rolling bearing of the present invention, and FIG. 2 is a rolling view of FIG. It is a perspective view of the holder | retainer (outer ring guide) in a bearing. As shown in FIGS. 1A and 1B, the rolling bearing 5 includes an inner ring 6 and an outer ring 7, a plurality of rolling elements 8 interposed between the inner ring 6 and the outer ring 7, and the rolling elements 8 around the rolling element 8. And a retainer 1 that holds it at regular intervals in the direction. The cage 1 is the rolling bearing cage of the present invention. The inner ring 6 and the outer ring 7 and the rolling element 8 are in contact with each other at a predetermined angle (contact angle) with respect to the radial center line, and can apply a radial load and an axial load in one direction.

  As shown in FIG. 2, the rolling bearing cage 1 of the present invention includes an annular cage body 2 having a hollow portion on the inner diameter side, and a metal ring plate fixed to both end faces of the cage body 2. 3. The cage body 2 has a plurality of pockets 4 for holding rolling elements (balls) at equal intervals in the circumferential direction. The rolling element holding surface of the pocket 4 is made of the same material as the cage body, and the ring plate 3 is not exposed to the holding surface. The radial width of the ring plate 3 is slightly smaller than the radial width of the cage body 2, and the ring plate 3 is not exposed to the outer diameter surface side that is a guide surface at both end surfaces of the cage body 2 in the annular axis direction. Further, it is fixed so as to be exposed on the inner diameter side. In the case of the inner ring guide, it is necessary to design it so as not to be exposed at least on the inner surface side.

  The cage body 2 is a compression molded body of a resin material. The ring plate 3 may be integrated in a state of being fixed to the main body at the time of compression molding of the cage main body 2, or may be fixed to the cage main body 2 after compression molding. The pocket 4 is formed by machining after compression molding. When the ring plate is integrated at the time of compression molding of the cage body, for example, a method of compression molding in a state where the ring plate and a resin material (powder) described later are inserted into a mold can be employed. Further, when the ring plate is fixed after the cage body is molded, for example, a complementary fitting portion (a notch portion to be described later) is formed in advance on both members, and heat is applied to one or both. A method such as fitting and fixing can be employed. In the present invention, since the manufacturing process can be simplified, it is preferable to integrate the cage main body and the ring plate at the time of compression molding of the cage main body.

  The planar shape of the pocket 4 can be a flat circle or a perfect circle. Here, the flat circular shape means a pocket that approximates the radius of the ball on both sides with a gap that matches the amount of pocket gap (difference between pocket inner diameter and ball diameter) required for a perfect circle shape. A shape that is a flat circle composed of the radius of the surface. It is preferable to have a flat circular shape that can reduce the load applied to the cage by increasing the pocket clearance in the circumferential direction of the rotation axis and absorbing the advance and delay of the ball.

  In rolling bearings used in artificial satellites, when the inertial force generated when the satellite changes direction acts on the rotating part of the artificial satellite, a moment load is generated in the bearing used in the rotating part, and the rolling elements of the bearing A lead / lag occurs between the cage and the cage. When the rolling element increases the force pushing the cage and moves beyond the guide clearance of the cage, bending deformation occurs in the cage. Since the rolling bearing cage of the present invention is a compression molded body, there is no weld portion in the molded body, and both end faces are reinforced by ring plates. Therefore, the bearing has high strength while being a resin cage. The deformation can be suppressed even when the moment load due to the inertial force is applied.

  Here, although the angular ball bearing has been described based on FIG. 1 and the like, the bearing configuration of the rolling bearing of the present invention is not limited to this. As a bearing type, for example, it can be applied to rolling bearings such as deep groove ball bearings, cylindrical roller bearings, needle roller bearings, etc.

  Only the ring plate in FIG. 2 is shown in FIG. The ring plate 3 has a notch 3a on the outer diameter surface of the plate. A plurality of notches 3a are formed at equal intervals in the circumferential direction. A part of the cage body is fitted in the notch 3a (see FIG. 2 and the like). With this structure, it is possible to prevent the cage body 2 and the ring plate 3 from being separated, and when the cage body 2 is subjected to hoop stress or heat, deformation (expansion) of the body in the radial direction can be prevented. When the resin plate (powder) is compression molded to form the cage body with the ring plate having the notch formed in the mold, the resin material is also filled in the notch portion. A complementary portion corresponding to the notch of the ring plate is formed on the cage body side, and the fitting structure is formed.

  As another shape of the notch, for example, a shape as shown in FIG. 4 can also be adopted. In a rocket engine liquid fuel turbo pump or the like, the rotational direction of the shaft is constant. In FIG. 4, the black arrow in the drawing is the cage rotation direction, and during rotation, a load in the direction of the white arrow in the drawing is applied to the cage body 2 by the rolling elements held in the pocket 4. In FIG. 4, the notch 3b of the ring plate 3 has a shape inclined from the direction parallel to the axial direction toward the cage rotation direction. This notch 3b is formed in a direction that opposes (hooks) a load applied from the rolling element during rotation. For this reason, both members are firmly fixed even during high-speed rotation, separation of the ring plate and the cage body can be prevented, and deformation due to hoop stress can also be prevented. Further, since the compression is performed from the direction of the annular axis at the time of compression molding, the notch portion having the shape is sufficiently filled with the resin material.

  The shape of the notch is not limited to that shown in FIGS. 3 and 4 as long as it can prevent the cage body and the ring plate from being separated from each other and can prevent the cage body from being deformed. it can. Moreover, you may form combining the shape shown in FIG.3 and FIG.4.

  The metal material of the ring plate is preferably selected from those having a tensile strength that can withstand high-speed rotation in a cryogenic environment. For example, an aluminum alloy, a magnesium alloy, a titanium alloy, carbon steel, a copper alloy, etc. are mentioned. In particular, it is preferable to employ an aluminum alloy that is low in cost, strong in corrosion resistance, and high in specific strength.

  The base resin of the resin material forming the cage body is not particularly limited as long as it is excellent in sliding properties such as self-lubricity and can be compression molded or heat compression molded. For example, it can be selected from super engineering plastic, high engineering plastic, and general-purpose engineering plastic. More specifically, polytetrafluoroethylene (PTFE) resin, polyimide (PI) resin, polyethylene (PE) resin, ultrahigh molecular weight polyethylene (UHMWPE) resin, polyvinylidene fluoride (PVDF) resin, polyacetal (POM) resin, polycarbonate (PC) resin, polyimide (PI) resin, polyether imide (PEI) resin, polyphenylene sulfide (PPS) resin, polyether ether ketone (PEEK) resin, etc. are mentioned.

  Ordinary fluid lubricants such as oil and grease for bearings used in liquid hydrogen and liquid oxygen used in rocket engine liquid fuel turbo pumps, and bearings used in space equipment and other vacuum environments. Therefore, it is preferable to provide the cage main body with self-lubricating property and transferability of the lubricating component (component constituting the main body) to the sliding counterpart material. That is, it is preferable that the cage body is worn during operation, and the self component is transferred from the pocket surface to the rolling elements and the bearing raceway surface, thereby contributing to the lubrication of the bearing. From such a viewpoint, among the above resins, it is preferable to employ a resin that is excellent in transferability to a sliding partner material, and it is particularly preferable to employ a PTFE resin.

PTFE resin is a crystalline thermoplastic resin, and its melting point is usually set to 327 ° C. for convenience, but the melt viscosity is extremely high at 10 ¹¹ poise even at 380 ° C., and the melt viscosity at the time of molding is 10 ³ to 10 Unlike a general thermoplastic resin having ⁴ poise, a melt molding method such as injection molding cannot be applied. For this reason, PTFE resin can be obtained by molding a powdered resin into a mold, pressurizing and compressing and then firing (compression molding), or heating to 360 to 390 ° C. above the melting point and pressurizing (sintering) A molding method (heat compression molding) is employed. In the present invention, a general PTFE resin represented by-(CF ₂ -CF ₂ ) _n- can be used as the PTFE resin, and a perfluoroalkyl ether group (-C _p F _{2p is added to the} general PTFE resin. -O -) (p is 1-4 integer) and polyfluoroalkyl group _{(H (CF 2) q -} ) (q can also be used a modified PTFE resin obtained by introducing such as an integer) of 1-20. The molecular weight of the PTFE resin is preferably one having a number average molecular weight (Mn) of about 100,000 to 10 million.

  As the PTFE resin, any of a molding powder by a suspension polymerization method, a fine powder by an emulsion polymerization method, and a recycled PTFE resin may be used. Here, the recycled PTFE resin is a PTFE resin that is not a virgin material. For example, a molded product obtained by heating and pressing a molding powder or fine powder at a melting point or higher, or a powder obtained by pulverizing a processed product after heating and firing, In addition, there is a type such as a powder obtained by further irradiating the powder with γ rays or electron beams. As the PTFE resin, it is preferable to use the above recycled PTFE resin. Since the recycled PTFE resin is heated and fired, it has excellent fluidity to the mold.

  PTFE resin is used in powder form during compression molding as described above. The average particle size (laser diffraction method) of the PTFE resin powder is preferably 3 to 50 μm, more preferably 3 to 15 μm. If the average particle size is less than 3 μm, the particles may aggregate and form a lump. If the average particle size exceeds 50 μm, the frictional wear characteristics with the sliding counterpart material may vary. Considering the fluidity to the mold, 3 to 10 μm recycled PTFE resin is particularly preferable.

  Examples of commercially available PTFE resins that can be used in the present invention include Kitamura Co., Ltd .: KTL-610, KTL-450, KTL-350, KTL-8N, KTL-400H, Mitsui DuPont Fluorochemical Co., Ltd .: Teflon (registered trademark). 7-J, TLP-10, Asahi Glass Co., Ltd .: Fullon G163, L150J, L169J, L170J, L172J, L173J, Daikin Industries, Ltd .: Polyflon M-15, Lubron L-5, Hoechst: Hostaflon TF9205, TF9207, etc. Can be mentioned.

  The base resin is blended with a fibrous reinforcing material for the purpose of improving mechanical strength and wear resistance and reducing the linear expansion coefficient. Examples of the fibrous reinforcing material include carbon fiber (PAN-based or pitch-based), glass fiber, and aramid fiber. Among these, it is preferable to use carbon fiber or glass fiber because the reinforcing effect can be easily obtained. Moreover, the fiber diameter and fiber length of carbon fiber or glass fiber are not particularly limited. 10-30 volume% is preferable with respect to the whole resin material, and, as for the compounding quantity of a fibrous reinforcement, 15-25 volume% is more preferable. If the blended amount of the fibrous reinforcing material is less than 10% by volume, the strength may be insufficient, and if it exceeds 30% by volume, no further improvement in strength is observed. In addition, when using together multiple types of fibrous reinforcement, it is preferable to adjust the total compounding quantity in the said range.

  Moreover, you may mix | blend an inorganic filler with the said base resin for the purpose of making the linear expansion coefficient of the cage body which consists of resin materials close to the linear expansion coefficient of a ring plate. Examples of the inorganic filler include magnesium oxide, calcium carbonate, iron oxide, titanium oxide, and silica. The blending amount of the inorganic filler is preferably less than 20% by volume and more preferably 15% by volume or less with respect to the entire resin material. There exists a possibility that required material strength cannot be ensured as the compounding quantity of an inorganic filler is 20 volume% or more. In addition, also about an inorganic filler, when using together multiple types, it is preferable to adjust the total compounding quantity in the said range.

  In addition, a solid lubricant, a pigment, and the like may be blended as necessary within a range not impairing the function as a cage and the compression moldability.

  As a resin material for forming the cage body, PTFE resin is used as a base resin, and at least one fibrous reinforcing material selected from glass fiber and carbon fiber is blended therein, and magnesium oxide and calcium carbonate are used as necessary. An embodiment in which at least one inorganic filler selected from the above is blended is most preferable. In this case, as described above, as described above, the fibrous reinforcing material is 10 to 30% by volume, the inorganic filler is less than 20% by volume, and the balance (50 to 90% by volume) with respect to the entire resin material as described above. Is a PTFE resin. When the PTFE resin used as the base resin is less than 50% by volume, the transferability to the sliding partner material is lowered, and the lubrication performance may be lowered. In addition, when such a resin material is used as a molding material, each component may be mixed and filled in a mold before compression molding, or may be prepared in advance as a composite powder composed of each component. Also good. The particle diameter of the composite powder is preferably set to be equal to or less than the surface roughness of the ring plate because the adhesion strength with the ring plate can be improved during compression molding.

  An example of the manufacturing process of the rolling bearing cage of the present invention will be described with reference to FIG. FIG. 5 is a schematic view showing an example of a manufacturing process (compression molding) of the rolling bearing cage of the present invention.

(1) Ring plate processing Using a metal material, a ring-shaped plate is manufactured by pressing or cutting. A notch (FIGS. 3 and 4) for suppressing deformation of the cage body is formed in the obtained ring plate.

(2) Surface treatment of the ring plate If necessary, at least the contact surface of the ring plate with the cage body is roughened into a concavo-convex shape by shot blasting, tumbler, machining, or chemical surface treatment such as acid treatment. To form a fine uneven shape. At the time of compression molding, resin forming the cage main body enters these uneven portions, and the adhesion strength between the cage main body and the ring plate is improved by the anchor effect. Here, the surface roughness is preferably adjusted so that the particle diameter is equal to or less than the surface roughness in consideration of the particle diameter of the composite powder.

(3) Heat compression molding Insert the ring plate 3 ′, the resin composite powder 2 ′, and the ring plate 3 ″ into the compression mold 11 in this order. The compression mold 11 includes an inner diameter mold 12, an outer diameter mold 13, a lower mold 15, and an upper mold 14. The inner diameter mold 12 and the outer diameter mold 13 are arranged at the same center, and are fixed to the lower mold 15 with bolts or the like. The molding material is inserted and arranged in an annular clearance portion surrounded by the inner diameter mold 12, the outer diameter mold 13 and the lower mold 15. In this state, the mold is heated to 360 ° C. or more, and the upper mold 14 having a shape partially fitted to the clearance portion is moved to the bottom dead center, whereby the resin composite material powder 2 sandwiched between the ring plates is obtained. 'Is compressed in the direction of the ring axis. Here, the molding pressure is 10 MPa or more, for example. By this compression molding, an annular member in which the ring plate 3 and the cage body 2 are integrated is obtained. If there is a concern about dimensional changes during use due to residual compressive stress in compression molding, an annealing treatment may be performed.

(4) Machining A cage is obtained by taking out the obtained annular member from the mold and forming pockets by post-processing. In addition, in the case where it is not possible to mold to the target dimensional tolerance only by compression molding, a cage having a target shape may be formed by finishing (machining). A molding die using a slide core may be used to form a pocket during compression molding.

  The rolling bearing cage of the present invention can integrate the cage body and the ring plate with such a simple manufacturing process, and can reduce the manufacturing cost. In addition, since the retainer body does not have a weld like an injection molded body and the ring plate is fixed to both end faces, deformation and breakage can be prevented even during high-speed rotation use.

  The rolling bearing cage of the present invention can be manufactured by a simple process, the cage is not likely to be unbalanced, and the cage can be prevented from being damaged due to hoop stress during high speed rotation. It can be suitably used as a cage. In addition, by using a resin material with excellent self-lubricating properties such as PTFE resin and transferability to the sliding counterpart material for the cage body, it is used in liquid hydrogen and liquid oxygen for rocket engine liquid fuel turbo pumps. It can be suitably used as a bearing retainer used in a vacuum environment used for a bearing used in a space environment or the like.

DESCRIPTION OF SYMBOLS 1 Rolling bearing cage 2 Cage body 3 Ring plate 4 Pocket 5 Rolling bearing 6 Inner ring 7 Outer ring 8 Rolling element 11 Compression molding die 12 Inner diameter die 13 Outer diameter die 14 Upper die 15 Lower die

Claims (7)

A rolling bearing cage for holding rolling elements in a rolling bearing,
The cage includes an annular cage body having a pocket for holding the rolling elements, and a metal ring plate fixed to both end faces of the cage body,
The cage for a rolling bearing, wherein the cage body is a compression molded body of a resin material.   The rolling bearing retainer according to claim 1, wherein the ring plate is integrated with the retainer body when the retainer body is compression-molded.   The said resin material mix | blends the polytetrafluoroethylene resin which is base resin, and mix | blends at least 1 fibrous reinforcement selected from glass fiber and carbon fiber, The Claim 1 or Claim 2 characterized by the above-mentioned. Roller bearing cage.   The rolling bearing cage according to claim 1, 2 or 3, wherein the metal material of the ring plate is an aluminum alloy, a magnesium alloy, a titanium alloy, carbon steel, or a copper alloy.   The ring plate has a notch portion on at least one surface selected from an inner diameter surface and an outer diameter surface, and the retainer body is in a state of being fitted into the notch portion. The cage for rolling bearings according to any one of claims 1 to 4. A rolling bearing having a rolling element and a cage for holding the rolling element,
The rolling bearing according to any one of claims 1 to 5, wherein the cage is a rolling bearing cage.   The rolling bearing according to claim 6, wherein the rolling bearing is a bearing used in a rotation support portion of a turbo pump for liquid fuel of a rocket engine.

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