Cage for rolling bearing, and rolling bearing

Abstract

To provide a cage for a rolling bearing, which can prevent the occurrence of a failure such as separation of a resin part by dispensing with removal processing of a protrusion for positioning a resin molding, while securing cage strength, and the rolling bearing using the cage.SOLUTION: A cage 5 is a cage for a rolling bearing, which holds a plurality of rolling elements in the rolling bearing. The cage has a toric metal body part 7, and a resin part 9 that is integrated with the metal body part 7. A pocket 6 for housing the rolling element is made of a resin part 9. The resin part 9 is formed on an outer peripheral surface of the metal body part 7. In the cage 5, a width surface 7a of the metal body part 7 constituting an axial end surface of the cage 5 has a recess 8 that is depressed in an axial direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cage for a rolling bearing and to a rolling bearing. [Background technology]

[0002] It is difficult to use conventional oil or grease lubrication for the bearings of rocket turbopumps that use cryogenic fluids such as liquid hydrogen and liquid oxygen. Therefore, solid lubrication is used, with the cage for the rolling bearing made of polytetrafluoroethylene (PTFE) resin, supplied by sliding with the rolling elements. The PTFE resin is transferred to the raceway surface and rolling elements by sliding, ensuring the lubrication of the bearing.

[0003] On the other hand, in recent rocket development, there has been a demand for smaller and faster rockets, and there are concerns about the strength of cages made of resin as the base material.In response to this, a cage has been proposed in which a resin containing a solid lubricant is insert-molded into a metal substrate, integrating the main body and resin part.

[0004] For example, in Patent Document 1, the strength of the cage is ensured by a metal base material such as aluminum, and the pocket surfaces that slide against the rolling elements and the guide surfaces that slide against the inner or outer ring are made of resin to ensure lubrication. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6178117 [Patent Document 2] Japanese Patent Publication No. 2023-33016 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-described cage, the molded body needs to be positioned after resin molding in order to machine pockets for accommodating the rolling elements. However, depending on the manner in which the molded body is positioned, there is a risk that the resin portion will peel off during subsequent processing, and there is also a risk of reduced work efficiency. For example, in order to machine the pockets in the molded body, protrusions may be provided on the width surfaces of the molded body for positioning. In this case, however, the protrusions must be removed after machining the pockets, and there is a risk that the resin portion on the outer peripheral surface of the cage will peel off during the removal process.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a retainer for a rolling bearing that ensures the strength of the retainer while eliminating the need for processing to remove convex portions for positioning a resin molded body and preventing problems such as peeling of the resin portion, and a rolling bearing that uses this retainer. [Means for solving the problem]

[0008] The retainer for a rolling bearing of the present invention is a retainer for a rolling bearing that holds a plurality of rolling elements in a rolling bearing, characterized in that the retainer has a circular metal main body portion and a resin portion integrated with the metal main body portion, the pockets that accommodate the rolling elements are formed from the resin portion, and the resin portion is formed on the inner or outer peripheral surface of the metal main body portion, and the retainer has a recess that is recessed in the axial direction on the width surface of the metal main body portion that forms the axial end face of the retainer. Here, the rolling bearing comprises an outer ring, an inner ring, and rolling elements (balls) interposed between the outer ring and the inner ring. The axial direction of the central axis of the inner ring and the outer ring is defined as the "axial direction." The direction perpendicular to the "axial direction" is defined as the "radial direction." The "circumferential direction" refers to the direction along the circumference that goes around the central axis of the central axis of the inner ring and the outer ring. The definitions of these directions are the same in the following explanation.

[0009] The metal main body has a plurality of recesses on the width surface, and these recesses are provided at equal intervals in the circumferential direction.

[0010] The recess is a closed-end circular hole within the width surface, and the metal main body has the recess at a position on the width surface that axially overlaps with the pocket.

[0011] The metal main body portion has a circular first metal portion located on the inner diameter side and a circular second metal portion located on the outer diameter side into which the first metal portion is fitted, the first metal portion and the second metal portion are bonded by the resin portion, and the first metal portion has the recess on its width surface.

[0012] The first metal part has a portion on its outer peripheral surface that forms a three-dimensional mesh lattice, and the depth of the recess on the width surface of the first metal part is smaller than the thickness from the width surface to the portion that forms the three-dimensional mesh lattice.

[0013] The rolling bearing of the present invention is a rolling bearing comprising an inner ring, an outer ring, rolling elements interposed between the inner ring and the outer ring, and a retainer that holds the rolling elements, wherein the retainer is the rolling bearing retainer of the present invention. [Effects of the Invention]

[0014] The cage for a rolling bearing of the present invention has an annular metal main body portion and a resin portion integrated with the metal main body portion. The pockets that accommodate the rolling elements are composed of the resin portion, and the resin portion is formed on the inner or outer peripheral surface of the metal main body portion. This ensures the strength of the cage while maintaining lubrication. Furthermore, the cage has axially recessed recesses on the width surfaces of the metal main body portion that form the axial end faces of the cage. This recess can be used to position the pockets during processing after resin molding. Therefore, unlike when, for example, a convex positioning portion is provided, this portion does not need to be removed, and there is no risk of peeling off the resin portion on the outer peripheral surface during removal. Furthermore, because the recesses are provided on the width surfaces of the metal main body portion, they do not interfere with sliding contact with the rolling elements or raceways. In this way, the cage for a rolling bearing of the present invention can prevent positioning problems while ensuring the strength of the cage.

[0015] The metal main body has a plurality of recesses on its width surface, and these recesses are arranged at equal intervals in the circumferential direction, which makes it easier to ensure stability during rotation.

[0016] For example, when resin is molded onto the outer peripheral surface of the metal main body, the outer peripheral surface of the metal main body is covered with resin, making it impossible to see the pocket holes in the metal main body. However, since the metal main body has a recess on its width surface at a position that overlaps with the pocket in the axial direction, the position of the pocket holes in the metal main body can be seen, making it easier to process the pocket holes after resin molding.

[0017] The metal main body has a first annular metal part located on the inner diameter side and a second annular metal part located on the outer diameter side into which the first metal part is fitted, and the first metal part and the second metal part are bonded by a resin part, and the first metal part has a recess on its width surface, and the first metal part has a part that forms a three-dimensional mesh lattice on its outer surface, and the depth of the recess on the width surface of the first metal part is smaller than the thickness from the width surface to the part that forms the three-dimensional mesh lattice, so that a flow path for the resin can be secured and it becomes easier to fill the spaces between the three-dimensional mesh lattice, and the metal main body and the resin part can be firmly bonded.

[0018] The rolling bearing of the present invention is a rolling bearing equipped with the rolling bearing cage of the present invention, and therefore can maintain lubrication while ensuring cage strength and preventing problems associated with positioning, allowing the cage to fully function as an integrated metal body and resin portion. It is particularly suitable as a bearing used in liquid fuel turbopumps for rocket engines used in cryogenic environments. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is an axial cross-sectional view showing an example of a rolling bearing of the present invention. [Figure 2] 1 is a perspective view of an example of a cage for a rolling bearing according to the present invention. [Figure 3] 1 is an end view of an example of a cage for a rolling bearing of the present invention. FIG. [Figure 4] 5A and 5B are perspective views of a metal main body of another example of a cage for a rolling bearing of the present invention. [Figure 5] 5A and 5B are a plan view and a cross-sectional view of the first metal part of FIG. 4. [Figure 6] FIG. 3 is an axial cross-sectional view showing another example of the rolling bearing of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The rolling bearing of the present invention will be described with reference to FIG. 1. FIG. 1 is a schematic diagram of an axial cross section of an angular contact ball bearing, an example of a rolling bearing of the present invention. Note that details of the cage configuration have been omitted. As shown in FIG. 1, angular contact ball bearing 1 includes an inner ring 2, an outer ring 3, a plurality of balls 4 interposed between the inner ring 2 and the outer ring 3, and a cage 5 that holds the balls 4 at regular intervals in the circumferential direction. This angular contact ball bearing 1 is used under unlubricated conditions, for example, without the use of a mobile lubricant such as lubricating oil or grease. The inner ring 2, the outer ring 3, and the balls 4 are in contact with each other at a predetermined angle θ (contact angle) relative to the radial centerline, and can withstand radial loads and unidirectional axial loads.

[0021] In angular contact ball bearing 1, both inner ring 2 and outer ring 3 are made of steel. Any material commonly used as a bearing material can be used for the steel. For example, high-carbon chromium bearing steel (SUJ1, SUJ2, SUJ3, SUJ4, SUJ5, etc.; JIS G 4805), carburized steel (SCr420, SCM420, etc.; JIS G 4053), stainless steel (SUS440C, etc.; JIS G 4303), cold-rolled steel, etc. can be used. Furthermore, the above steels or ceramic materials can be used for balls 4.

[0022] 1, the cage 5 is an outer ring guide type cage, and part of the outer peripheral surface of the cage has a guide portion that is guided by the outer ring 3. In the configuration of FIG. 1, this guide portion comes into contact with the inner peripheral surface of the outer ring 3, thereby guiding the cage 5 to the outer ring 3.

[0023] Fig. 2 shows a perspective view of an example of a cage for a rolling bearing of the present invention. As shown in Fig. 2, the cage 5 is a machined cage, and is provided with a plurality of pockets 6 at regular intervals in the circumferential direction to hold the balls, which are the rolling elements. The cage 5 has an annular metal main body portion 7 and a resin portion 9 integrated with the metal main body portion 7. In the cage 5 of Fig. 2, the resin portion 9 is formed on the outer peripheral surface of the metal main body portion 7.

[0024] 2, the pockets 6 that house the rolling elements are made of a resin portion 9, which slides against the inner peripheral surface of the outer ring and each ball. The metal main body portion 7 is exposed on the inner peripheral surface and axial end face of the cage 5.

[0025] The metal constituting the metal body 7 may be an aluminum alloy, a titanium alloy, a stainless steel alloy, or Inconel. The base resin constituting the resin portion 9 is preferably a resin with excellent lubrication properties, as will be described later.

[0026] The cage 5 has recesses 8 recessed in the axial direction on the width surface 7a of the metal main body 7 that constitutes the axial end surface of the cage 5. These recesses 8 function as positioning portions for processing pockets in a resin molded product. The metal main body 7 has multiple recesses 8 (two in FIG. 2 ), which are arranged at equal intervals in the circumferential direction. Although the formation of the recesses 8 may cause imbalance on the circumference of the cage 5, it is preferable that the recesses 8 be arranged at equal intervals on the width surface 7a to maintain balance. For example, if the number of pockets 6 is an even number, two recesses 8 are arranged at equal intervals in the circumferential direction. Furthermore, if the number of pockets 6 is an odd number, three recesses 8 are arranged at equal intervals in the circumferential direction.

[0027] The recess 8 is a closed-end circular hole within the width surface 7a. The diameter of the circular hole is set to a dimension that does not exceed the thickness (radial length) of the width surface 7a of the metal main body portion 7. When processing the pocket after resin molding, the molded body is positioned by inserting a pin or the like into the recess 8. The shape of the recess 8 is not particularly limited and is set according to the shape of the pin. As shown in Figure 2, the recess 8 is not connected to the inner peripheral surface of the cage 5. Furthermore, the recess 8 is not formed so as to straddle the resin portion 9, and no recess is formed on the width surface of the resin portion 9.

[0028] 2, the metal main body 7 preferably has recesses 8 on the width surface 7a at positions that axially overlap with the pockets 6. In this case, the recesses 8 are not formed in the circumferential regions of the pillar portions between the pockets 6 on the width surface 7a.

[0029] 2, the recesses 8 are formed only on one axial width surface 7a of the metal main body 7, but they may also be formed on both axial width surfaces. When forming them on both axial width surfaces, it is preferable to form them symmetrically in consideration of weight balance.

[0030] FIG. 3 shows an end view of an example of a cage for a rolling bearing of the present invention. In FIG. 3, the cage is cut axially at the location where the recess is formed. In this case, the resin portion 9 is formed by injection molding using the metal body portion 7 as an insert part, and has a first portion 9a and a second portion 9b as an integral part. The first portion 9a is provided in each pocket hole of the metal body portion 7, and the second portion 9b is provided on the outer peripheral surface of the metal body portion 7. In FIG. 3, the resin portion 9 is formed from a single resin composition, and the thickness of the first portion 9a and the second portion 9b are uniform.

[0031] The depth h (axial dimension) of the recess 8 in the width surface 7a of the metal main body 7 is, for example, about 0.3 mm to 5 mm. In Fig. 3, the bottom surface of the recess 8 is flat and the depth h is constant, but the depth may be configured to vary.

[0032] 3 shows an example in which the metal main body 7 is made of a single member, but the metal main body 7 may be made of multiple members. Also, the metal main body 7 may be a solid body, or may be configured so that the metal main body 7 has voids communicating with the outside, and the voids are partially filled with resin.

[0033] Another example of the metal body in the cage for a rolling bearing of the present invention will be described with reference to Fig. 4. In the example of Fig. 4, the metal body is composed of two members, an inner diameter side and an outer diameter side, and is provided with holes communicating with the outside. As shown in Fig. 4(a), the metal body 10 has an annular first metal part 11 located on the inner diameter side and a second metal part 12 located on the outer diameter side. The first metal part 11 has two recesses 13 on its width surface.

[0034] As shown in Fig. 4(b), the first metal part 11 is an annular member having a pocket hole 11a. This first metal part 11 has a part that constitutes a three-dimensional mesh-like lattice. The holes formed by this lattice communicate with the outside and constitute communication holes. Generally, a lattice structure in which a periodically repeated lattice is three-dimensionally connected is called a lattice structure. For example, there are structures in which a simple cubic lattice, a body-centered cubic lattice, and a face-centered cubic lattice are three-dimensionally connected. In Fig. 4(b), based on the three-dimensional mesh-like lattice, a plurality of holes are formed on the inner surface of the pocket hole 11a of the first metal part 11, and a plurality of holes are formed on the outer peripheral surface of the first metal part 11. A part of the resin is filled in such holes. Note that the inner peripheral surface of the first metal part 11 shown in Fig. 4(b) is constituted by a flat curved surface. Also, one axial end face is constituted by a flat plane except for the concave portion 13.

[0035] As shown in Fig. 4(c), the second metal part 12 is an annular member having a pocket hole 12a. This second metal part 12 also has a part that constitutes a three-dimensional mesh-like lattice. In Fig. 4(c), based on the three-dimensional mesh-like lattice, irregularities are repeatedly formed on the inner peripheral surface of the second metal part 12, and a plurality of holes are formed on the outer peripheral surface of the second metal part 12. A part of the resin is filled in such holes.

[0036] Fig. 5(a) shows a plan view of the first metal part 11, and Fig. 5(b) shows an A-A cross-sectional view thereof. As shown in Fig. 5(b), the first metal part 11 has a part that constitutes a three-dimensional mesh-like lattice on its outer peripheral surface. Here, it is preferable that the depth h of the concave portion 13 is smaller than the thickness t from the width surface to the part that constitutes the three-dimensional mesh-like lattice (specifically, the axial distance from the width surface to the hole formed by the three-dimensional mesh-like lattice) (depth h < thickness t). In Fig. 5, the relationship of 0.5t < h < t further holds.

[0037] Since each of the metal parts shown in Figs. 4 and 5 has a part that constitutes a three-dimensional mesh-like lattice, the structure is complicated. These metal parts are manufactured by a 3D printer or precision casting.

[0038] Figure 4(a) shows the state in which the metal parts are assembled. The first metal part 11 is fitted into the space surrounded by the inner peripheral surface of the second metal part 12, thereby forming the annular metal main body part 10. In this case, the metal parts are assembled so that the circumferential positions of the pocket holes of each part are aligned. The resin composition that forms the resin part flows into the gap between the first metal part 11 and the second metal part 12, thereby bonding the metal parts together.

[0039] Here, the resin portion formed on the cage may be, for example, the same resin composition for the inner surface of the pocket and the guide portion, or different resin compositions (e.g., a first resin portion and a second resin portion) depending on the sliding portion. For example, in an extremely low-temperature environment where a fluid lubricant cannot be used, the cage requires lubricity, so a highly self-lubricating resin such as PTFE resin is required for the sliding portion such as the inner surface of the pocket. On the other hand, the guide portion of the cage that slides against the raceway ring requires wear resistance rather than lubricity, which are performance requirements that are contradictory to those of the sliding portion of the pocket. In light of this, it is possible to satisfy different required characteristics.

[0040] For example, in the cage 5 shown in FIG. 3, a first resin portion (a resin portion corresponding to the first portion 9a) may be formed on the inner surface of the pocket 6, and a second resin portion (a resin portion corresponding to the second portion 9b) having a different composition from the first resin portion may be formed in the guide portion that slides against the outer ring. For example, by making the first resin portion a highly lubricating composition and the second resin portion a highly wear-resistant composition, it is possible to impart performance suited to the intended use of each portion, such as self-lubrication to the sliding portion of the pocket 6 and wear resistance to the guide portion of the cage 5. Here, "resin portions having different compositions" refers to cases where the types of raw materials contained in each resin portion are different (for example, types of resin (including differences in molecular weight, etc.) or types of additives (including differences in size, etc.)), as well as cases where the types of raw materials are all the same but the content ratios of each raw material are different.

[0041] The following describes the composition of each resin portion when the resin portion is composed of a first resin portion and a second resin portion.

[0042] The base resin constituting the first resin portion is preferably a resin with excellent lubrication properties, such as polyamide-imide (PAI) resin, PTFE resin, tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA) resin, ultra-high molecular weight polyethylene (PE) resin, polyamide (PA) resin, or polyacetal (POM) resin. These resins may be used alone or in combination to form a polymer alloy. Other resins, such as polyether ether ketone (PEEK) resin and polyphenylene sulfide (PPS) resin, may also be mixed as secondary components.

[0043] Among the above resins, PTFE resin is particularly preferred because it has an excellent property of transferring to a sliding mating material and reducing the friction coefficient of the sliding portion. As the PTFE resin, a general PTFE resin represented by -(CF2-CF2)n- can be used. Also, a general PTFE resin having a perfluoroalkyl ether group (-C p F 2p -O-) (p is an integer of 1-4) or polyfluoroalkyl group (H(CF2) q Modified PTFE resins into which q is introduced (q is an integer of 1-20) can also be used. These PTFE resins and modified PTFE resins can be obtained by either the suspension polymerization method used to obtain general molding powders or the emulsion polymerization method used to obtain fine powders. PTFE resins that have been heated and baked at or above their melting point can also be used. Powders that have been baked and then further irradiated with gamma rays or electron beams can also be used. The molecular weight of PTFE resins is such that the number average molecular weight (Mn) is 10 6 It is preferable that it is less than 10 ...

[0044] On the other hand, the base resin constituting the second resin portion can be PAI resin, PTFE resin, PFA resin, ultra-high molecular weight PE resin, PA resin, POM resin, PEEK resin, PPS resin, etc. These resins can be used alone or as a polymer alloy in which two or more types are mixed.

[0045] The resin composition forming the first resin portion and the second resin portion can be blended with fibrous reinforcing materials such as glass fiber, carbon fiber, and aramid fiber as needed. Blending in fibrous reinforcing materials can improve the wear resistance of the resin portion. It can also reduce the linear expansion coefficient of the resin portion, improving adhesion to the cage body during use. Among fibrous reinforcing materials, it is preferable to use glass fiber, which is relatively inexpensive.

[0046] The resin composition forming the first resin part and the second resin part may also contain solid lubricants such as PTFE resin (except when PTFE resin is used as the base resin), graphite, tungsten disulfide, molybdenum disulfide, etc., and inorganic fillers such as magnesium oxide, calcium carbonate, iron oxide, titanium oxide, silica, etc. These may be blended alone or in combination.

[0047] In each resin part, the content of the base resin is, for example, 50% by mass or more, preferably 60% to 90% by mass, and more preferably 65% ​​to 90% by mass, based on the entire resin part. From the viewpoints of wear resistance and linear expansion coefficient, the content of the fibrous reinforcing material is, for example, 5% to 40% by mass, and preferably 10% to 30% by mass, based on the entire resin part. In a configuration that includes a solid lubricant, the content of the solid lubricant is, for example, 5% to 20% by mass, based on the entire resin part. In a configuration that includes an inorganic filler, the content of the inorganic filler is, for example, 0.3% to 5% by mass, based on the entire resin part.

[0048] In consideration of the required characteristics of each part of the cage, it is preferable that the first resin part has lubricity, and it is preferable that the second resin part has higher wear resistance than the first resin part. Here, high wear resistance means that the specific wear rate is small when each resin part slides under the same sliding conditions. Note that the following explanation will be given assuming that the two resin parts have this relationship.

[0049] For example, if PTFE resin is used as the base resin for the first resin part, the wear resistance of the second resin part can be relatively increased by using PEEK resin or PPS resin as the base resin for the second resin part. Also, by adjusting the types and amounts of fibrous reinforcing material, solid lubricant, and resin, it is possible to form resin parts that meet the requirements of the sliding part and guide part of the pocket, respectively.

[0050] In a preferred embodiment of the cage, the first resin portion and the second resin portion each contain PTFE resin as a base resin and a fibrous reinforcement material. In this case, the wear resistance and self-lubricating properties can be varied by varying the PTFE resin content, the fibrous reinforcement content, and the molecular weight of the PTFE resin between the resin portions. Specifically, it is preferable that the PTFE resin content in the second resin portion be lower than the PTFE resin content in the first resin portion, and that the fibrous reinforcement content in the second resin portion be higher than the fibrous reinforcement content in the first resin portion. Furthermore, while satisfying the above-mentioned magnitude relationship, it is preferable that the first resin portion contains 70% to 90% by mass of PTFE resin and 10% to 30% by mass of fibrous reinforcement, relative to the entire resin portion, and the second resin portion contains 65% to 85% by mass of PTFE resin and 15% to 35% by mass of fibrous reinforcement, relative to the entire resin portion.

[0051] Additionally, by making the molecular weight of the PTFE resin used in the second resin portion larger than the molecular weight of the PTFE resin used in the first resin portion, the wear resistance of the second resin portion can be made relatively high.

[0052] An example of a configuration in which the resin portion is composed of a first resin portion and a second resin portion is shown in FIG. 6. The axial cross-sectional view shown in FIG. 6 shows a schematic cross-section of the cage. In FIG. 6, the metal main body portion shown in FIG. 4 is used. Note that the three-dimensional mesh structure and the resin portions filled in its pores are omitted for convenience.

[0053] In FIG. 6, cage 25 is structurally divided into a cage inner diameter side portion located on the inner diameter side of cage 25 and a cage outer diameter side portion located on the outer diameter side. Furthermore, the cage inner diameter side portion is composed of an annular first metal portion 27a and a first resin portion 29a, and the cage outer diameter side portion is composed of an annular second metal portion 27b and a second resin portion 29b. First resin portion 29a is formed in the sliding portion of pocket 26 where balls 24 slide, and second resin portion 29b is formed in the guide portion where outer ring 23 slides. In the configuration of FIG. 6, part of the inner surface of pocket 26 is also formed by second resin portion 29b, but by making the outer diameter φ of the cage inner diameter side portion larger than the pitch circle diameter PCD of the bearing, balls 24 can slide only on first resin portion 29a, which has high self-lubricating properties. In this case, the surface of the part of the inner surface of the pocket 26 where the resin composition is different, that is, the boundary between the first resin portion 29a and the second resin portion 29b, is located closer to the outer ring 23 than the pitch circle diameter PCD.

[0054] An example of manufacturing the cage 25 of FIG. 6 is shown. First, the first metal portion 27a on the inner diameter side of the cage is prepared. Then, the resin composition of the first resin portion 29a is heated and press-fitted into the first metal portion 27a. At this time, the first resin portion 29a is laminated on the sliding portion of the pocket hole of the first metal portion 27a. Furthermore, the resin composition enters the pores of the portion that constitutes the three-dimensional mesh structure of the first metal portion 27a, thereby filling the pores with part of the first resin portion 29a. As a result, the first metal portion 27a and the first resin portion 29a are tightly bonded together by an anchor effect.

[0055] Next, the second metal portion 27b of the outer diameter side portion of the cage is fitted to the obtained inner diameter side portion of the cage. Then, the resin composition of the second resin portion 29b is heated and press-fitted into the second metal portion 27b. At this time, the second resin portion 29b is laminated on the outer peripheral surface of the second metal portion 27b. Furthermore, the resin composition enters the pores of the portion that constitutes the three-dimensional mesh structure of the second metal portion 27b, thereby filling the pores with part of the second resin portion 27b. As a result, the second metal portion 27b and the second resin portion 29b are tightly bonded to each other by an anchor effect.

[0056] Furthermore, the first metal portion 27a and the second metal portion 27b are bonded together by thermocompression bonding of the resin composition that forms the second resin portion 29b. That is, a portion of the molten resin composition fills the gap between the first metal portion 27a and the second metal portion 27b and the pores in the first metal portion 27a, thereby providing an excellent anchoring effect. Furthermore, the first resin portion 29a present on the outer diameter surface of the first metal portion 27a and the molten resin composition are thermocompression bonded to each other, thereby bonding the first resin portion 29a and the second resin portion 29b together. From the viewpoint of adhesion, it is preferable that the linear expansion coefficient of the second resin portion 29b, which acts as an adhesive, is lower than that of the first resin portion 29a.

[0057] After the resin molding, a fixing pin or the like is inserted into a recess 28 provided on the width surface of the first metal portion 27a to position the resin molding. Then, processing of the pocket 26 (specifically, grinding of the resin portion, etc.) is performed. It is possible to form a convex shape on the width surface as a positioning portion. However, in that case, the convex portion needs to be removed at the end of the processing, which may cause the resin portion on the outer peripheral surface of the cage to peel off. In contrast, forming the recess 28 on the width surface eliminates the need for such a removal step, and thus prevents the resin portion from peeling off from the outer peripheral surface of the cage. The fixing pin is a component used to accurately position a workpiece, a jig, etc., during cutting or assembly work. As described above, by forming a recess in the workpiece and inserting the fixing pin into the recess, the workpiece is fixed and positioned, and cutting or other processing can be performed on the workpiece.

[0058] In the cage shown in Figure 6, the metal body is divided into two parts, an inner diameter side part and an outer diameter side part, and resins of different compositions are molded into each part to provide resin parts with appropriate performance on the appropriate surfaces. Specifically, by gradually pouring resin into each metal part, a resin layer used on the outer diameter side of the cage is formed in the guide part, and a resin layer used mainly on the inner diameter side of the cage is formed in the sliding part of the pocket. This allows for the formation of a lubricating layer with improved wear resistance in the guide part, and a lubricating layer with improved self-lubricating properties on the inner surface of the pocket. In addition, the metal body has a three-dimensional mesh structure with lattices in the circumferential, radial, and axial directions. By inserting resin deep into the structure, the dissimilar materials of resin and metal are firmly held together, giving the resin part excellent peel resistance.

[0059] The resin portion can be formed by other methods besides pouring a molten resin composition into the pores of the three-dimensional mesh structure of the metal body. For example, it can be formed by applying pressure or vibration to the powder to introduce the resin into the pores, and then baking it. Conventional methods such as compression molding, extrusion molding, and injection molding can also be used.

[0060] Furthermore, to increase the adhesive strength of the resin portion, the surface of the metal main body may be roughened by a method such as shot blasting or other mechanical roughening methods, glow discharge or plasma discharge or other electrical roughening methods, or alkali treatment or other chemical roughening methods.

[0061] In the above, an outer ring guide type cage is shown, but the cage is not limited to this, and an inner ring guide type cage that is guided by sliding against the outer peripheral surface of the inner ring may also be used.

[0062] Because the rolling bearing of the present invention has a cage with the above-described structure, it can be used in environments where no fluid lubricant is used. It is particularly suitable for use in cryogenic environments where liquid hydrogen, liquid oxygen, liquid nitrogen, liquefied natural gas, etc. are used, and in vacuum environments. Specifically, it can be used in liquid fuel turbopumps for rocket engines, space equipment such as artificial satellites, etc. It is not limited to cryogenic environments, and can also be used in environments above room temperature, for example.

[0063] In Figure 1 and other figures, an angular contact ball bearing has been used as an example of the rolling bearing of the present invention, but the bearing type to which the present invention can be applied is not limited to this and the present invention can also be applied to other ball bearings, tapered roller bearings, self-aligning roller bearings, needle roller bearings, etc.

[0064] The embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims, and includes all modifications within the meaning and scope of the claims. [Industrial Applicability]

[0065] The retainer for rolling bearings of the present invention can be widely used as a retainer because it ensures the strength of the retainer while eliminating the need for processing to remove convex portions used to position the resin molded body and preventing problems such as peeling of the resin portion. [Explanation of symbols]

[0066] 1. Angular contact ball bearings (rolling bearings) 2. Inner circle 3 outer ring 4 balls 5. Cage (for rolling bearings) 6 pockets 7 Metal body 7a width side 8 recess 9 Resin part 9a Part 1 9b Part 2 10 Metal body 11 1st metal part 11a pocket hole 12 Second metal part 12a pocket hole 13 Recess 21 Rolling bearings 22 Inner Circle 23 Outer ring 24 balls 25 Cage (rolling bearing cage) 26 pockets 27a 1st metal part 27b 2nd metal part 28 Recess 29a 1st resin part 29b 2nd resin part

Claims

1. A rolling bearing cage that holds a plurality of rolling elements in a rolling bearing, The cage has an annular metal main body portion and a resin portion integrated with the metal main body portion, and pockets for accommodating the rolling elements are formed by the resin portion, and the resin portion is formed on an inner circumferential surface or an outer circumferential surface of the metal main body portion, The cage for a rolling bearing is characterized in that the cage has a recess recessed in the axial direction on a width surface of the metal body portion that constitutes an axial end surface of the cage.

2. 2. The cage for a rolling bearing according to claim 1, wherein the metal body has a plurality of recesses on the width surface, the recesses being provided at equal intervals in the circumferential direction.

3. 3. A retainer for a rolling bearing according to claim 1 or claim 2, characterized in that the recess is a closed, bottomed circular hole within the width surface, and the metal main body portion has the recess at a position on the width surface that axially overlaps with the pocket.

4. 3. A retainer for a rolling bearing as described in claim 1 or claim 2, characterized in that the metal main body portion has a first annular metal portion located on the inner diameter side and a second annular metal portion located on the outer diameter side and into which the first metal portion is fitted, the first metal portion and the second metal portion being bonded by the resin portion, and the first metal portion having the recess on its width surface.

5. A retainer for a rolling bearing as described in claim 4, characterized in that the first metal portion has a portion on its outer surface that forms a three-dimensional mesh lattice, and the depth of the recess on the width surface of the first metal portion is smaller than the thickness from the width surface to the portion that forms the three-dimensional mesh lattice.

6. A rolling bearing comprising an inner ring, an outer ring, rolling elements interposed between the inner ring and the outer ring, and a cage that holds the rolling elements, 3. A rolling bearing, wherein the cage is the cage for a rolling bearing according to claim 1 or 2.

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