Method for manufacturing resin cage, resin cage, and rolling bearing

Abstract

To provide a method for manufacturing a resin-made cage capable of rapidly and economically manufacturing the resin-made cage having excellent strength.SOLUTION: A mold 15 having a cylindrical cavity 17 and a gate 18 opened at one end in the axial direction of the cylindrical cavity 17 is used, and a resin composition in a molten state is injected into the cylindrical cavity 17 from the gate 18 to manufacture a hollow cylindrical blank 16 composed of the resin composition in which the orientation direction of the fibrous reinforcing material 14 is set to the axial direction, and the resin-made cage 1 is formed from the cylindrical blank 16 by cutting.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a resin cage, a resin cage manufactured by the manufacturing method, and a rolling bearing using the resin cage. [Background technology]

[0002] Rolling bearings are often used to support rotating shafts in automobiles, industrial machinery, etc. A rolling bearing generally has an outer ring, an inner ring positioned radially inside the outer ring, multiple rolling elements incorporated between the outer ring and the inner ring, and a cage that holds the multiple rolling elements.

[0003] Known examples of such cages for rolling bearings include the resin cages described in Patent Documents 1 and 2. This resin cage has a cage annular portion and multiple cantilever-shaped cage bar portions extending axially at intervals in the circumferential direction from the cage annular portion. The cage bar portions are composed of a bar base portion connected to the cage annular portion and a pair of claw portions that branch into two at intervals in the circumferential direction and extend axially from the bar base. Concave spherical pockets that accommodate balls as rolling elements are formed between circumferentially adjacent cage bar portions. The cage annular portion and multiple cage bar portions are integrally formed from a resin composition made by blending a fibrous reinforcing material (such as glass fiber) with a resin material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6608151 [Patent Document 2] Japanese Patent Publication No. 2022-108083 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, a resin cage such as that disclosed in Patent Document 1 is manufactured by injection molding of a resin using a mold. That is, in general, when manufacturing a resin cage such as that disclosed in Patent Document 1, a mold having a cavity corresponding to the shape of the finished resin cage is designed and manufactured, a molten resin composition is then injected into the mold, and the resin composition is removed from the mold after it has cooled and solidified.

[0006] When a resin cage is manufactured by this method, excellent productivity can be achieved when large-lot production is carried out in which resin cages of the same shape and dimensions are mass-produced.

[0007] Meanwhile, up until now, when carrying out small-lot production of plastic cages with the same shape and dimensions, or when making prototypes of plastic cages under development, just as with large-lot production, a mold with a cavity shaped to accommodate the plastic cage was designed and manufactured, and the plastic cage was manufactured by injection molding using that mold.

[0008] However, when producing small lots of plastic cages or when making prototypes of plastic cages that are currently under development, it takes a lot of time and is uneconomical to design and manufacture a new mold each time.

[0009] Therefore, as a method for manufacturing a resin cage without using a mold, a manufacturing method has been proposed in Patent Document 2. The manufacturing method in Patent Document 2 involves manufacturing the resin cage using a 3D printer that forms a three-dimensional shape by layering molten resin.

[0010] However, when a resin cage is manufactured using a 3D printer as in Patent Document 2, there is a problem in that it is difficult to ensure the strength of the resin cage.

[0011] That is, when a resin cage is manufactured using a 3D printer, the resin cage is formed by stacking molten resin one layer at a time. At this time, the molten resin is stacked in the axial direction of the resin cage. Here, when a three-dimensional shape is formed using a 3D printer, the object obtained by stacking the molten resin has a property that it has relatively high strength against compressive forces acting in the stacking direction, but low strength against compressive forces acting in a direction perpendicular to the stacking direction.

[0012] Therefore, when a plastic cage is manufactured using a 3D printer, the cage column portion of the plastic cage has low strength against pressing forces acting in a direction perpendicular to the axial direction, i.e., pressing forces acting from the balls to the cage column portion when the balls are placed in the pockets during bearing assembly, and pressing forces acting from the balls to the cage column portion due to the balls lagging or advancing during bearing operation, which makes it difficult to ensure the strength of the plastic cage.

[0013] Furthermore, when a resin cage is molded using a 3D printer, shrinkage occurs as the resin ejected from the nozzle of the 3D printer hardens, making it difficult to ensure dimensional accuracy. Regarding this issue, Patent Document 2 employs a method in which a resin cage is first molded using a 3D printer, the dimensions of the resin cage obtained by molding are measured, the input values ​​to the 3D printer are corrected, and the resin cage is molded again using the 3D printer. However, this method requires effort, time, and money. Furthermore, when a resin cage is molded using a 3D printer, the resin material is not readily available, and the surface roughness of the molded resin cage is low, so additional processing may be required.

[0014] An object of the present invention is to provide a method for manufacturing a resin cage that can quickly and economically manufacture a resin cage having excellent strength. [Means for solving the problem]

[0015] In order to solve the above problems, the present invention provides a method for manufacturing a resin cage having the following configuration. [Configuration 1] A method for manufacturing a resin cage, in which a cage annular portion and a plurality of cantilever-shaped cage bar portions extending in the axial direction at circumferential intervals from the cage annular portion are integrally formed from a resin composition obtained by blending a fibrous reinforcing material into a resin material, and pockets for accommodating rolling elements of a rolling bearing are formed between the cage bar portions adjacent in the circumferential direction, a cylindrical blank production process in which a mold having a cylindrical cavity and a gate opening at one axial end of the cylindrical cavity is used, and the molten resin composition is injected from the gate into the cylindrical cavity to produce a hollow cylindrical blank made of the resin composition in which the orientation direction of the fibrous reinforcing material is axial; A method for manufacturing a plastic retainer, characterized by including, after the cylindrical blank manufacturing process, a cutting process in which the plastic retainer is formed by cutting from the cylindrical blank so that the axial direction of the cylindrical blank coincides with the axial direction of the plastic retainer.

[0016] When this configuration is adopted, a hollow cylindrical blank made of a resin composition is injection molded, and then the cylindrical blank is cut to form a resin cage, eliminating the need to design and manufacture a mold for the resin cage. This makes it possible to quickly manufacture small lots of resin cages and prototypes of resin cages under development.

[0017] Here, because the cylindrical blank has a simple shape, it is relatively easy to design and manufacture a mold for the cylindrical blank. Furthermore, even when manufacturing plastic cages of different shapes, it is possible to use a common cylindrical blank as long as the radial size of the plastic cages is approximately the same (specifically, a size that fits within the cross section of the cylindrical blank). This makes it possible to reduce total costs and is economical.

[0018] Furthermore, since a mold for injection molding the cylindrical blank has a gate located at one axial end of the cylindrical cavity, the orientation direction of the fibrous reinforcing material contained in the cylindrical blank is the axial direction. The cylindrical blank is then cut to form the plastic cage so that its axial direction coincides with the axial direction of the plastic cage. Therefore, the plastic cage obtained by this cutting process has cage post portions that are strong against pressing forces acting in a direction perpendicular to the axial direction (i.e., pressing forces acting from the rolling elements on the cage post portions when they are inserted into pockets during bearing assembly, and pressing forces acting from the rolling elements on the cage post portions due to the rolling elements' advance and lag movements during bearing operation).

[0019] Furthermore, when a plastic cage is injection-molded using a mold, as in general large-lot production, there is a problem in that disturbances in the flow of the molten resin composition occur at the tip portions of the cage bar sections of the plastic cage, which in turn disturbs the orientation direction of the fibrous reinforcing material, potentially reducing the strength of the tip portions of the cage bar sections. To address this problem, if a plastic cage is formed by cutting a cylindrical blank with the fiber reinforcing material oriented in the axial direction, as in the above configuration, the orientation direction of the fibrous reinforcing material is reliably aligned in the axial direction, even at the tip portions of the cage bar sections, making it possible to ensure the strength of the tip portions of the cage bar sections. In other words, it is possible to obtain a plastic cage with strength equivalent to or greater than that of a plastic cage injection-molded using a mold.

[0020] Furthermore, because the cylindrical blank has a simple shape, molding defects such as sink marks and short molds (insufficient filling of the resin into the cavity) are less likely to occur when the cylindrical blank is injection molded. Therefore, compared to when injection molding resin cages as in general large-lot production, it is possible to use a resin composition containing a fibrous reinforcing material with a long fiber length or a resin composition with a high blend ratio of fibrous reinforcing material, which makes it possible to manufacture a resin cage with particularly high strength.

[0021] [Configuration 2] A method for manufacturing a resin cage according to configuration 1, wherein the gate of the mold used in the cylindrical blank manufacturing process is a disk gate that opens annularly around the entire inner circumference of one axial end of the cylindrical cavity.

[0022] By adopting this configuration, it is possible to form a weldless cylindrical blank that is free of weld lines (joining points of molten resin compositions). Therefore, the resin cage obtained by cutting the cylindrical blank also becomes weldless, which makes it possible to particularly effectively increase the strength of the resin cage.

[0023] [Configuration 3] In the cylindrical blank manufacturing step, the axial length of the cylindrical cavity is set to a length at least twice the axial length of the resin cage, thereby manufacturing the cylindrical blank having an axial length at least twice the axial length of the resin cage; A method for manufacturing a plastic cage according to configuration 1 or 2, wherein in the cutting process, the cylindrical blank is cut perpendicular to the axial direction to form a plurality of annular divided blanks, and each of the divided blanks is cut to form a plurality of the plastic cages.

[0024] When this configuration is adopted, a plurality of resin cages are manufactured from one cylindrical blank, making it possible to manufacture the resin cages efficiently.

[0025] [Configuration 4] In the cutting process, when cutting the divided blank located at the axial end farther from the gate out of the plurality of divided blanks formed by cutting the cylindrical blank perpendicular to the axial direction to form the plastic cage, the plastic cage is formed in an orientation in which the cage annular portion is formed on the side farther from the gate and the cage column portion is formed on the side closer to the gate.

[0026] By adopting this configuration, when a plastic retainer is formed by cutting the split blank located at the axial end farthest from the gate out of multiple split blanks formed by cutting a cylindrical blank perpendicular to the axial direction, it is possible to ensure the strength of the retainer column portion of the plastic retainer.

[0027] That is, when a hollow cylindrical blank is manufactured by injecting a molten resin composition into a cylindrical cavity through a gate that opens at one axial end of the cylindrical cavity, the molten resin composition flows in the axial direction in most of the cylindrical blank, so that the orientation direction of the fibrous reinforcing material contained in the resin composition is axial. However, at the axial end of the cylindrical blank far from the gate, the flow of the molten resin composition may be disturbed, which may cause a disturbance in the orientation direction of the fibrous reinforcing material. Therefore, if a resin cage is formed by cutting a divided blank located at the axial end far from the gate of the cylindrical blank, and the resin cage is formed with the cage post portions on the far side from the gate, the orientation direction of the fibrous reinforcing material of the resin composition that forms the cage post portions will be disturbed and not aligned in the axial direction, which may reduce the strength of the cage post portions. In contrast, when forming a plastic retainer by cutting a split blank located at the axial end of the cylindrical blank farthest from the gate, if the plastic retainer is formed with the retainer column portion on the side closer to the gate, the orientation direction of the fibrous reinforcing material of the resin composition forming the retainer column portion is more likely to be aligned in the axial direction, making it possible to ensure the strength of the retainer column portion.

[0028] [Configuration 5] A method for manufacturing a plastic cage according to any one of configurations 1 to 4, wherein in the cutting process, the cylindrical blank is cut perpendicularly to the axial direction to form the multiple divided blanks, and then an annealing treatment is performed to heat the divided blanks and remove residual stress before cutting the divided blanks to form the plastic cage.

[0029] By adopting this configuration, an annealing treatment to remove residual stress is performed before cutting the divided blank, so that when the divided blank is cut, the residual stress in the divided blank is released, preventing dimensional changes, and thus making it possible to manufacture a resin cage with stable dimensional accuracy.

[0030] [Configuration 6] A method for manufacturing a plastic cage according to any one of configurations 1 to 5, wherein in the cutting process, the cylindrical blank is cut perpendicularly to the axial direction to form the multiple divided blanks, and then, before cutting the divided blanks to form the plastic cage, a humidity control treatment is performed in which the divided blanks are left to stand in a constant temperature and humidity bath for a predetermined time.

[0031] By adopting this configuration, after the divided blanks are cut to form the resin cage, the resin composition forming the resin cage can be prevented from absorbing moisture and causing dimensional changes. This makes it possible to manufacture resin cages with stable dimensional accuracy. In addition, the humidity conditioning treatment improves the impact strength of the resin, making it possible to prevent cracking and whitening of the resin cage when the divided blanks are cut to form the resin cage or when the resin cage is incorporated into a rolling bearing. This humidity conditioning treatment is particularly effective when a resin material that easily absorbs moisture, such as polyamide resin, is used as the resin material constituting the resin composition.

[0032] [Configuration 7] 7. The method for manufacturing a resin cage according to any one of configurations 1 to 6, wherein the fibrous reinforcing material mixed in the resin material is long fiber having a fiber length of 1.0 mm or more.

[0033] This configuration makes it possible to manufacture a resin cage with particularly high strength. Specifically, if a resin composition for forming the resin cage is blended with a fibrous reinforcing material having a long fiber length, the mechanical properties (strength, rigidity, impact resistance, creep resistance, etc.) of the resin cage can be improved. However, when manufacturing a resin cage by injection molding using a mold, as in the past, it is difficult to use a fibrous reinforcing material with a long fiber length in order to ensure the moldability of the resin and the freedom of the cage shape. Therefore, a fibrous reinforcing material with a fiber length of less than 1.0 mm is generally used. Furthermore, when manufacturing a resin cage using a 3D printer, it is difficult to use a fibrous reinforcing material with a fiber length of 1.0 mm or more. In contrast, in this invention, a cylindrical blank with a simple shape is produced by injection molding resin using a mold, and a plastic retainer is then formed from the cylindrical blank by cutting.Therefore, even if a resin composition containing a fibrous reinforcing material with a long fiber length is used to form the plastic retainer, it is possible to ensure the moldability of the resin in the cylindrical blank production process.Therefore, by using long fibers with a fiber length of 1.0 mm or more, it is possible to manufacture a plastic retainer with particularly high mechanical properties (strength, rigidity, impact resistance, creep resistance, etc.).

[0034] [Configuration 8] A method for manufacturing a resin cage according to any one of configurations 1 to 7, wherein the resin composition contains the fibrous reinforcing material in an amount that accounts for 20 to 70 mass % of the resin composition.

[0035] This structure allows the production of a resin cage with particularly high strength, since the proportion of fibrous reinforcing material in the resin composition is 20% by mass or more. Also, since the proportion of fibrous reinforcing material in the resin composition is 70% by mass or less, the resin cage is prevented from becoming too hard, ensuring the ease of incorporation of the resin cage into rolling bearings.

[0036] [Configuration 9] 9. The method for manufacturing a plastic cage according to any one of configurations 1 to 8, wherein the cutting step uses a three-dimensional cutting machine to perform cutting based on three-dimensional data of the plastic cage.

[0037] By adopting this configuration, it is possible to form the resin cage efficiently in a short time.

[0038] [Configuration 10] A method for manufacturing a resin cage described in any one of configurations 1 to 9, wherein the pocket forming surface of the cage column portion that forms the pocket is formed in a concave spherical shape to accommodate balls as the rolling elements.

[0039] The present invention also provides a resin cage manufactured by the above-described method, which has the following configuration. [Configuration 11] A resin cage in which a cage annular portion and a plurality of cantilever-shaped cage bar portions extending in the axial direction at intervals in the circumferential direction from the cage annular portion are integrally formed from a resin composition in which a fibrous reinforcing material is blended into a resin material, and pockets for accommodating rolling elements of a rolling bearing are formed between the cage bar portions adjacent in the circumferential direction, an orientation direction of the fibrous reinforcing material in a portion of the retainer post portion along a pocket forming surface that forms the pocket is set to an axial direction that extends non-parallel to the pocket forming surface, A resin cage, wherein the pocket forming surface of the cage post portion is a machined surface on which cut surfaces of a large number of the fibrous reinforcing materials cut midway in the longitudinal direction are exposed.

[0040] [Configuration 12] A resin cage as described in configuration 11, in which the cage annular portion and the plurality of cage column portions are formed weldless, with no weld lines occurring at the confluence of the molten resin composition.

[0041] [Configuration 13] 13. The resin cage according to configuration 11 or 12, wherein the pocket forming surface of the cage post portion is formed into a concave spherical shape to accommodate balls as the rolling elements.

[0042] The present invention also provides a rolling bearing using the above-mentioned resin cage, which has the following configuration. [Configuration 14] The outer ring and an inner ring disposed radially inside the outer ring; a plurality of rolling elements incorporated between the outer ring and the inner ring; A rolling bearing comprising a resin cage according to any one of configurations 11 to 13 for holding the plurality of rolling elements. [Effects of the Invention]

[0043] In the method for manufacturing a plastic cage of this invention, a hollow cylindrical blank made of a resin composition is injection molded, and then the plastic cage is formed from the cylindrical blank by cutting, so there is no need to design and manufacture a mold for the plastic cage.As a result, it is possible to quickly manufacture small lots of plastic cages or prototypes of plastic cages under development.

[0044] Here, because the cylindrical blank has a simple shape, it is relatively easy to design and manufacture a mold for the cylindrical blank, and even when manufacturing plastic cages of different shapes, it is possible to use a common cylindrical blank as long as the radial size of the plastic cages is the same. This makes it possible to reduce total costs and is economical.

[0045] Furthermore, since a mold for injection molding the cylindrical blank has a gate located at one axial end of the cylindrical cavity, the orientation direction of the fibrous reinforcing material contained in the cylindrical blank is the axial direction. The cylindrical blank is then cut to form the plastic cage so that the axial direction of the cylindrical blank coincides with the axial direction of the plastic cage. Therefore, the plastic cage obtained by this cutting process has retainer posts that are highly resistant to pressing forces acting in a direction perpendicular to the axial direction.

[0046] Furthermore, since the resin cage is formed by cutting a cylindrical blank with the fiber reinforcement oriented in the axial direction, the orientation of the fiber reinforcement can be aligned in the axial direction even at the tip portions of the cage bar sections, ensuring the strength of the tip portions of the cage bar sections.

[0047] Furthermore, because the cylindrical blank has a simple shape, molding defects such as sink marks and short molds (insufficient filling of the resin into the cavity) are less likely to occur when the cylindrical blank is injection molded. Therefore, compared to when injection molding resin cages as in general large-lot production, it is possible to use a resin composition containing a fibrous reinforcing material with a long fiber length or a resin composition with a high blend ratio of fibrous reinforcing material, which makes it possible to manufacture a resin cage with particularly high strength. [Brief explanation of the drawings]

[0048] [Figure 1] FIG. 1 is a cross-sectional view showing a rolling bearing incorporating a resin cage manufactured by a manufacturing method according to a first embodiment of the present invention. [Figure 2] Axial view of the plastic cage shown in Figure 1 [Figure 3] A view of the resin cage shown in Figure 1 from the inside in the radial direction [Figure 4] A perspective view of the pocket and its surroundings in the plastic cage shown in Figure 1 [Figure 5] FIG. 2 is a diagram showing a state in which a cylindrical blank for manufacturing the resin cage shown in FIG. 1 is injection molded in a mold. [Figure 6] FIG. 6 shows a cylindrical blank formed by the injection molding shown in FIG. 5. [Figure 7] FIG. 7 is a diagram showing a divided blank obtained by removing a disk gate portion from the cylindrical blank shown in FIG. 6. [Figure 8] FIG. 10 is a diagram showing a second embodiment of the present invention, corresponding to FIG. 5. [Figure 9] FIG. 9 shows a cylindrical blank formed by the injection molding shown in FIG. 8. [Figure 10]FIG. 10 is a diagram schematically illustrating an example of the distribution of the orientation of the fiber reinforcement inside a divided blank located at the end farthest from the gate, among a plurality of divided blanks obtained by dividing the cylindrical blank shown in FIG. [Figure 11] FIG. 1 is a diagram showing an example of the distribution of orientation of fiber reinforcement inside a divided blank and the positional relationship with a resin cage formed by cutting the divided blank. [Figure 12] FIG. 10 is a view corresponding to FIG. 2 showing another example of a resin cage manufactured by the manufacturing method according to the embodiment of the present invention. [Figure 13] A view of the resin cage shown in Figure 12 from the inside in the radial direction [Figure 14] A perspective view of the vicinity of the pocket of the resin cage shown in Figure 12 DETAILED DESCRIPTION OF THE INVENTION

[0049] 1 shows a rolling bearing incorporating a resin cage 1 manufactured by a manufacturing method according to a first embodiment of the present invention. This rolling bearing has an outer ring 2, an inner ring 3 arranged coaxially on the radially inner side of the outer ring 2, a plurality of rolling elements 4 incorporated at regular intervals in the circumferential direction between the outer ring 2 and the inner ring 3, and the resin cage 1 that holds the plurality of rolling elements 4. In this embodiment, the rolling elements 4 are balls.

[0050] The axial direction is the direction parallel to the central axis of the resin retainer 1 (the central axis of rotation of the bearing), the radial direction is the direction perpendicular to the central axis of the resin retainer 1, and the circumferential direction is the direction along the circumference that goes around the central axis of the resin retainer 1.

[0051] An outer ring raceway groove 5 with which the rolling elements 4 roll and make contact is formed on the inner periphery of the outer ring 2. The outer ring raceway groove 5 is a groove that extends circumferentially around the inner periphery of the outer ring 2 and has an arc-shaped cross section.

[0052] An inner ring raceway groove 6 with which the rolling elements 4 roll and make contact is formed on the outer periphery of the inner ring 3. The inner ring raceway groove 6 is a groove that extends circumferentially around the outer periphery of the inner ring 3 and has an arc-shaped cross section.

[0053] The rolling elements 4 are radially sandwiched between an outer ring raceway groove 5 and an inner ring raceway groove 6. The outer ring raceway groove 5 is formed symmetrically with respect to the axial center of the outer ring 2, and the inner ring raceway groove 6 is also formed symmetrically with respect to the axial center of the inner ring 3. This rolling bearing is a deep groove ball bearing.

[0054] Here, we will explain using as an example a plastic retainer 1 that is incorporated into a deep groove ball bearing in which the outer ring raceway groove 5 and inner ring raceway groove 6 are symmetrical about the axial center, but this invention can also be applied to a plastic retainer 1 that is incorporated into a ball bearing, such as an angular contact ball bearing, in which the outer ring raceway groove 5 and inner ring raceway groove 6 are formed asymmetrically about the axial center.

[0055] The resin cage 1 has a cage annular portion 7 extending circumferentially from one axial side (the right side in the figure) of the rolling elements 4, and a plurality of cage post portions 8 extending circumferentially from the cage annular portion 7 to the other axial side (the left side in the figure) at intervals. Each cage post portion 8 is formed in a cantilever shape with its end on one axial side (the right side in the figure) as a fixed end fixed to the cage annular portion 7 and its end on the other axial side (the left side in the figure) as a free end. Each cage post portion 8 is arranged to extend axially between adjacent rolling elements 4 in the circumferential direction.

[0056] As shown in Figures 2 to 4, concave spherical pockets 9 for accommodating rolling elements 4 are formed between adjacent cage post portions 8 in the circumferential direction. As shown in Figure 3, the cage post portion 8 is composed of a post base 10 connected to the cage annular portion 7 and a pair of claw portions 11 that extend axially, bifurcating from the post base 10 at a circumferentially spaced interval. The post base 10 is a portion formed to protrude axially (upward in the figure) from the cage annular portion 7 so as to overlap with the rolling elements 4 when viewed circumferentially (left-right direction in the figure). The rolling elements 4 are held in place by the pair of claw portions 11 that face each other in the circumferential direction (left-right direction in the figure) with the pocket 9 between them, preventing them from falling out of the pocket 9 in the axial direction. This resin cage 1 is a crown-shaped resin cage.

[0057] As shown in FIG. 4, the cage post 8 is formed with an inner diameter chamfer 12 extending along the ridgeline where the pocket forming surface of the cage post 8 intersects with the radially inner surface of the cage post 8. Also, as shown in FIG. 2, the cage post 8 is formed with an outer diameter chamfer 13 extending along the ridgeline where the pocket forming surface of the cage post 8 (i.e., the inner surface of the pocket 9) intersects with the radially outer surface of the cage post 8. While the inner diameter chamfer 12 and the outer diameter chamfer 13 are shown with a concave arc cross section in the figure, they can also be formed with a linear cross section. Providing this inner diameter chamfer 12 and outer diameter chamfer 13 suppresses scraping of lubricating oil by the edges of the inner surface of the pocket 9 during bearing rotation, making it possible to prevent oil film breakdown during high-speed rotation.

[0058] The cage annular portion 7 and each cage bar portion 8 are formed seamlessly and integrally from a resin composition in which a fibrous reinforcing material 14 (see FIG. 11) is blended with a resin material.

[0059] The resin material constituting the resin composition may be an engineering plastic such as polyphthalamide resin (PPA), polyamide resin (PA), polyether ether ketone resin (PEEK), polyphenylene sulfide resin (PPS), etc. Examples of polyamide resin (PA) that may be used include polyamide 46 (PA46), polyamide 66 (PA66), polynonamethylene terephthalamide (PA9T), polyhexamethylene terephthalamide (PA6T), and polydecamethylene terephthalamide (PA10T).

[0060] The fibrous reinforcing material 14 to be blended into the resin composition may be glass fiber, carbon fiber, aramid fiber, or the like. The fibrous reinforcing material 14 is blended in a proportion of 20 to 70 mass % (preferably 30 to 60 mass %, more preferably 40 to 60 mass %) of the resin composition. Furthermore, the fibrous reinforcing material 14 used is a long fiber having an average fiber length of 1.0 mm or more (preferably 2.0 mm or more, more preferably 3.0 mm or more).

[0061] An example of a manufacturing method for this resin cage 1 will be described.

[0062] [Cylindrical blank manufacturing process] A hollow cylindrical blank 16 shown in Fig. 6 is produced by resin injection molding using a mold 15 shown in Fig. 5. Specifically, as shown in Fig. 5, a mold 15 having a cylindrical cavity 17 and a gate 18 opening at one axial end (the upper end in the figure) of the cylindrical cavity 17 is used. A molten resin composition is injected into the cylindrical cavity 17 through the gate 18 of the mold 15. After the resin composition has cooled and solidified, the hollow cylindrical blank 16 shown in Fig. 6 is removed from the mold 15. Here, when the molten resin composition is injected into the cylindrical cavity 17 through the gate 18 shown in Fig. 5, because the gate 18 is located at one axial end (the upper end in the figure) of the cylindrical cavity 17, the molten resin composition flows axially (downward in the figure) inside the cylindrical cavity 17. As a result, the orientation direction of the fibrous reinforcing material 14 contained in the resin composition forming the cylindrical blank 16 shown in Fig. 6 is axial.

[0063] In the mold 15 shown in Fig. 5, the gate 18 can be a disk gate that opens continuously around the entire inner periphery of one axial end (top end in the figure) of the cylindrical cavity 17, although it is possible to use gates that open locally on the inner periphery (or outer periphery) of one axial end of the cylindrical cavity 17 and are provided at multiple locations spaced apart in the circumferential direction. As a result, the cylindrical blank 16 shown in Fig. 6 is formed weldless, with no weld lines, which are the joining points of the molten resin composition.

[0064] [Cutting process] After the cylindrical blank manufacturing process, as shown in Fig. 6, the cylindrical blank 16 is cut into a disk-shaped resin portion 19 solidified within the gate 18 and an annular divided blank 20 (see Fig. 7) with both ends open. The figure shows an example in which the cylindrical blank 16 is divided into the disk-shaped resin portion 19 and the divided blank 20 by cutting the cylindrical blank 16 perpendicular to the axial direction, but the cylindrical blank 16 may also be cut into an annular shape at the position of the gate 18 (the point at which the axial thickness of the gate 18 is thinnest).

[0065] Next, the divided blank 20 is subjected to an annealing treatment and a humidity conditioning treatment, in that order. The annealing treatment is a treatment in which the divided blank 20 is heated to remove residual stress in the resin composition that constitutes the divided blank 20, and the humidity conditioning treatment is a treatment in which the divided blank 20 is left standing in a constant temperature and humidity chamber for a predetermined time to adjust the moisture content of the resin composition that constitutes the divided blank 20.

[0066] Thereafter, the divided blanks 20 shown in FIG. 7 are cut to form the plastic cage 1 shown in FIGS. 1 to 4. At this time, the cutting is performed so that the axial direction of the divided blanks 20 shown in FIG. 7 (i.e., the axial direction of the cylindrical blank 16 shown in FIG. 6) coincides with the axial direction of the plastic cage 1 shown in FIG. 1. As shown in FIG. 11, the plastic cage 1 is formed with the cage annular portion 7 formed on the side farther from the gate 18 (see FIG. 5) (the lower side in the figure) and the cage bar portion 8 formed on the side closer to the gate 18 (see FIG. 5) (the upper side in the figure). This cutting is performed using a three-dimensional cutting machine based on preset three-dimensional data of the plastic cage 1. The three-dimensional cutting machine is a machine tool that simultaneously controls at least three axes, the X-axis, the Y-axis, and the Z-axis, to cut a workpiece, and is, for example, a 3D modeling machine, a machining center, a multi-axis machine, or a multi-tasking machine.

[0067] When the resin cage 1 is manufactured by the above method, as shown in FIG. 11 , the orientation direction of the fibrous reinforcing materials 14 contained in the divided blank 20 is the axial direction, and the divided blank 20 is cut to form the resin cage 1. Therefore, in the resin cage 1 manufactured by the above method, the orientation direction of the fibrous reinforcing materials 14 in the portion along the pocket forming surface (inner surface of the pocket 9) of the cage post portion 8 is not parallel to the pocket forming surface (inner surface of the pocket 9) of the cage post portion 8, but is the axial direction extending non-parallel to the pocket forming surface (inner surface of the pocket 9) of the cage post portion 8. Furthermore, the pocket forming surface (inner surface of the pocket 9) of the cage post portion 8 becomes a machined surface on which the cut surfaces of the numerous fibrous reinforcing materials 14 are exposed. In other words, when the divided blank 20 is cut, the numerous fibrous reinforcing materials 14 are cut along the inner surface of the pocket 9 midway in the longitudinal direction, and the cut surfaces of the fibrous reinforcing materials 14 are exposed from the pocket forming surface (inner surface of the pocket 9) of the cage post portion 8. Furthermore, the resin cage 1 manufactured by the above method is weldless, with no weld lines occurring at the joining points of the molten resin compositions.

[0068] The orientation direction of the fibrous reinforcing material 14 constituting the cylindrical blank 16 refers to the direction that occurs most frequently when the length direction of all the fibrous reinforcing material 14 contained in the resin composition in the axial center portion of the cylindrical blank 16 is classified into the closest direction among the axial direction, the radial direction, and the circumferential direction.

[0069] 6, in the manufacturing method of this embodiment, a cylindrical blank 16 made of a resin composition is injection-molded, and then the cylindrical blank 16 is cut to form the resin cage 1, so there is no need to design and manufacture a mold for the resin cage 1. This makes it possible to quickly manufacture small lots of resin cages 1 or prototypes of resin cages 1 under development.

[0070] Here, because the cylindrical blank 16 has a simple shape, it is relatively easy to design and manufacture a mold 15 for the cylindrical blank 16 as shown in FIG. 5. Furthermore, even when manufacturing plastic cages 1 with different shapes, it is possible to use a common cylindrical blank 16 (see FIG. 6) as long as the radial sizes of the plastic cages 1 are approximately the same (specifically, sizes that fit within the cross section of the cylindrical blank 16 shown in FIG. 6). This makes it possible to reduce total costs and is economical. Furthermore, by manufacturing and stocking multiple sizes of cylindrical blanks 16 in advance, it becomes possible to manufacture small lots of plastic cages 1 or development prototypes of plastic cages 1 in a particularly short period of time.

[0071] 5, the manufacturing method of this embodiment uses a mold 15 for injection molding a cylindrical blank 16, in which a gate 18 is arranged at one axial end of a cylindrical cavity 17, so that the orientation direction of the fibrous reinforcing material 14 contained in the cylindrical blank 16 is the axial direction, as shown in FIG. 11. Then, the resin cage 1 is formed by cutting the cylindrical blank 16 so that the axial direction of the cylindrical blank 16 coincides with the axial direction of the resin cage 1. Therefore, the cage post portions 8 of the resin cage 1 obtained by this cutting process have high strength against pressing forces acting in a direction perpendicular to the axial direction (i.e., pressing forces acting on the cage post portions 8 from the rolling elements 4 when the rolling elements 4 are inserted into the pockets 9 shown in FIG. 3, and pressing forces acting on the cage post portions 8 from the rolling elements 4 due to the advance / lag of the rolling elements 4 during bearing operation).

[0072] Furthermore, when the resin cage 1 is injection-molded using a mold as in general large-lot production, there is a problem in that disturbances in the flow of the molten resin composition occur in the claw portions 11 at the tips of the cage bar portions 8 of the resin cage 1 shown in Fig. 3, which causes disturbances in the orientation direction of the fibrous reinforcing material 14 and may reduce the strength of the claw portions 11. To address this problem, if the resin cage 1 is formed by cutting a cylindrical blank 16 in which the orientation direction of the fiber reinforcing material is axial, as shown in Fig. 11, the orientation direction of the fibrous reinforcing material 14 is reliably aligned in the axial direction even in the claw portions 11 at the tips of the cage bar portions 8 shown in Fig. 3, making it possible to ensure the strength of the claw portions 11 at the tips of the cage bar portions 8. In other words, when the resin cage 1 is manufactured using the manufacturing method of this embodiment, it is possible to obtain a resin cage 1 having strength equal to or greater than that of a resin cage 1 injection-molded using a mold.

[0073] Furthermore, when the resin cage 1 is formed by cutting the cylindrical blank 16 shown in Fig. 6, the skin layer (the surface layer where the molten resin composition shown in Fig. 5 solidifies in contact with the inner surface of the cavity of the mold 15; generally has lower strength than the core layer) of the cylindrical blank 16 is removed, and the resin cage 1 can be formed using almost only the core layer (the portion inside the skin layer). Therefore, a resin cage 1 with high strength can be manufactured.

[0074] Furthermore, as shown in Fig. 6, the cylindrical blank 16 has a simple shape, and therefore, when the cylindrical blank 16 is injection molded, molding defects such as sink marks and short molds (insufficient filling of the resin in the cavity) are less likely to occur, as shown in Fig. 5. Therefore, the manufacturing method of this embodiment makes it possible to use a resin composition containing a fibrous reinforcing material 14 with a long fiber length or a resin composition with a high blend ratio of the fibrous reinforcing material 14, compared to when the resin cage 1 is injection molded as in general large-lot production, and this makes it possible to manufacture a resin cage 1 with particularly high strength.

[0075] 5, the manufacturing method of this embodiment employs a disk gate as the gate 18 of the mold 15 that produces the cylindrical blank 16, making it possible to form a weldless cylindrical blank 16 that is free of weld lines. Therefore, the plastic cage 1 obtained by cutting the cylindrical blank 16 is also weldless, making it possible to particularly effectively increase the strength of the plastic cage 1.

[0076] In addition, in the manufacturing method of this embodiment, an annealing treatment is performed to remove residual stress before cutting the divided blank 20 shown in Fig. 7, so that when the divided blank 20 is cut, the residual stress of the divided blank 20 is released, preventing dimensional changes. Therefore, it is possible to manufacture the resin cage 1 with stable dimensional accuracy.

[0077] In addition, in the manufacturing method of this embodiment, humidity conditioning is performed before cutting the divided blank 20 shown in FIG. 7 . This prevents the resin composition forming the resin cage 1 from absorbing moisture and causing dimensional changes after cutting the divided blank 20 to form the resin cage 1. This makes it possible to manufacture the resin cage 1 with stable dimensional accuracy. Furthermore, humidity conditioning improves the impact strength of the resin. This prevents cracks and whitening from occurring in the claw portions 11 and the bottoms of the pockets 9 of the resin cage 1 shown in FIGS. 3 and 4 when cutting the divided blank 20 to form the resin cage 1 or when incorporating the resin cage 1 into a rolling bearing. This humidity conditioning is particularly effective when using a resin material that easily absorbs moisture, such as polyamide resin, as the resin material constituting the resin composition.

[0078] Furthermore, the manufacturing method of this embodiment uses long fibers having a fiber length of 1.0 mm or more (preferably 2.0 mm or more, and more preferably 3.0 mm or more) as the fibrous reinforcing material to be blended into the resin material, making it possible to manufacture a resin cage 1 with particularly high strength. In other words, if a resin composition containing a fibrous reinforcing material with a long fiber length is used to form the resin cage 1, it is possible to improve the mechanical properties (strength, rigidity, impact resistance, creep resistance, etc.) of the resin cage 1. However, when manufacturing the resin cage 1 by injection molding of resin using a mold, as in the past, it is difficult to use a fibrous reinforcing material with a long fiber length in terms of ensuring the moldability of the resin and the degree of freedom in the shape of the cage. Therefore, a fibrous reinforcing material with a fiber length of less than 1.0 mm is generally used. Furthermore, even when manufacturing the resin cage 1 using a 3D printer, it is difficult to use a fibrous reinforcing material with a fiber length of 1.0 mm or more. In contrast, in the manufacturing method of this embodiment, as shown in Figures 5 and 6, a cylindrical blank 16 with a simple shape is produced by injection molding resin using a mold 15, and then a plastic retainer 1 is formed from the cylindrical blank 16 by cutting.Therefore, even if a resin composition containing a fibrous reinforcing material with a long fiber length is used to form the plastic retainer 1, it is possible to ensure the moldability of the resin in the cylindrical blank manufacturing process shown in Figure 5.Therefore, by using long fibers with a fiber length of 1.0 mm or more (preferably 2.0 mm or more, more preferably 3.0 mm or more), it is possible to manufacture a plastic retainer 1 with particularly high mechanical properties (strength, rigidity, impact resistance, creep resistance, etc.).

[0079] In addition, in the manufacturing method of this embodiment, when cutting the divided blank 20 shown in Figure 7, a three-dimensional cutting machine is used to perform the cutting based on three-dimensional data of the plastic retainer 1, so that the plastic retainer 1 can be formed efficiently in a short amount of time.

[0080] Furthermore, the manufacturing method of this embodiment uses a resin composition with a fibrous reinforcing material ratio of 20 mass % or more (preferably 30 mass % or more, and more preferably 40 mass % or more), making it possible to manufacture a resin cage 1 with particularly high strength. Furthermore, the use of a resin composition with a fibrous reinforcing material ratio of 70 mass % or less (preferably 60 mass % or less) prevents the resin cage 1 from becoming too hard, and ensures the ease of assembling the resin cage 1 into a rolling bearing.

[0081] 8 and 9 show a second embodiment of the present invention. The second embodiment is different from the first embodiment only in the axial length of the cylindrical blank 16, and the other configurations are basically the same. Therefore, parts corresponding to those in the first embodiment are given the same reference numerals, and descriptions thereof will be omitted.

[0082] [Cylindrical blank manufacturing process] A hollow cylindrical blank 16 shown in Fig. 9 is produced by injection molding a resin using a mold 15 shown in Fig. 8. Specifically, as shown in Fig. 8, a mold 15 is used that has a cylindrical cavity 17 and a gate 18 that opens at one axial end of the cylindrical cavity 17 (the upper end in the figure), and a molten resin composition is injected into the cylindrical cavity 17 through the gate 18 of the mold 15. After the resin composition has cooled and solidified, the hollow cylindrical blank 16 shown in Fig. 9 is removed from the mold 15. The outer and inner peripheries of the cylindrical blank 16 may be provided with a draft angle (for example, an angle of about 0.5 to 2.0°) to make it easier to remove the cylindrical blank 16 from the cylindrical cavity 17.

[0083] Here, in the mold 15 shown in Fig. 8, the axial length of the cylindrical cavity 17 is set to be at least twice (preferably at least three times, and at least five times in the figure) the axial length of the resin cage 1 shown in Fig. 3 (the height from the lower end of the cage annular portion 7 to the upper ends of the claw portions 11 of the cage column portions 8 in the figure). As a result, the axial length of the cylindrical cavity 17 shown in Fig. 9 is at least twice (preferably at least three times, and at least five times in the figure) the axial length of the resin cage 1.

[0084] [Cutting process] After the cylindrical blank manufacturing process, as shown in Figure 9, the cylindrical blank 16 is cut perpendicular to the axial direction to separate it into a disk-shaped resin portion 19 that has solidified within the gate 18 and multiple (five in the figure) annular divided blanks 20 that are open at both ends.

[0085] Next, the divided blanks 20 are subjected to an annealing treatment and a humidity conditioning treatment, in that order. After that, each of the divided blanks 20 is cut to form the resin cage 1 shown in FIGS. 1 to 4. At this time, the cutting is performed so that the axial direction of the divided blank 20 shown in FIG. 9 (i.e., the axial direction of the cylindrical blank 16) coincides with the axial direction of the resin cage 1 shown in FIG. 1. At this time, of the divided blanks 20 shown in FIG. 9, at least the divided blank 20 located at the axial end (lower end in the figure) farther from the gate 18 is formed into the resin cage 1 in an orientation such that the cage annular portion 7 is formed on the side farther from the gate 18 (see FIG. 8) (lower side in the figure) and the cage post portion 8 is formed on the side closer to the gate 18 (see FIG. 8) (upper side in the figure), as shown in FIG. 11.

[0086] When a plastic retainer 1 is manufactured using this method, multiple plastic retainers 1 shown in Figures 1 to 4 are manufactured from a single cylindrical blank 16, as shown in Figure 9, making it possible to manufacture the plastic retainer 1 efficiently.

[0087] Furthermore, when a plastic retainer 1 is manufactured using this method, as shown in Figure 9, when the plastic retainer 1 is formed by cutting the split blank 20 located at the axial end (lower end in the figure) farthest from the gate 18 out of multiple split blanks 20 formed by cutting a cylindrical blank 16 perpendicular to the axial direction, it is possible to ensure the strength of the retainer column portion 8 of the plastic retainer 1.

[0088] That is, as shown in Figure 8, when a cylindrical blank 16 shown in Figure 9 is produced by injecting a molten resin composition into a cylindrical cavity 17 from a gate 18 that opens at one axial end of the cylindrical cavity 17, the molten resin composition flows in the axial direction in most of the cylindrical blank 16, so that the orientation direction of the fibrous reinforcing material 14 contained in the resin composition is the axial direction. However, in a divided blank 20 located at the axial end (lower end in the figure) farther from the gate 18 (see Figure 8) of the cylindrical blank 16, as shown in Figure 10, there is a risk that the flow of the molten resin composition will be disturbed at the end 20a farther from the gate 18 (lower end in the figure), causing a disturbance in the orientation direction of the fibrous reinforcing material 14. Therefore, if the resin cage 1 is formed by cutting the divided blank 20 located at the axial end (the lower end in the figure) farther from the gate 18 of the cylindrical blank 16, and the resin cage 1 is formed with the cage post portions 8 on the side farther from the gate 18 (the lower side in the figure), the orientation direction of the fibrous reinforcing material 14 of the resin composition forming the cage post portions 8 will not be aligned in the axial direction and will be disordered, which may reduce the strength of the cage post portions 8. In contrast, as shown in Figure 11, if the resin cage 1 is formed with the cage post portions 8 on the side closer to the gate 18 (the upper side in the figure), the orientation direction of the fibrous reinforcing material 14 of the resin composition forming the cage post portions 8 will be more likely to be aligned in the axial direction, making it possible to ensure the strength of the cage post portions 8.

[0089] Other functions and effects are the same as those of the first embodiment.

[0090] 12 to 14 show other examples of a resin cage 1 manufactured by the manufacturing method of each of the above embodiments. A plurality of axially extending oil grooves 21 are formed at circumferential intervals in the bottom of the pocket 9. As shown in FIG. 13, the axial length of the claw portion 11 at the tip of the cage post portion 8 (i.e., the axial distance from the tip of the post base portion 10 to the tip of the claw portion 11) is set to 50% or more of the diameter of the rolling element 4. Furthermore, as shown in FIG. 14, an oil-retaining recess 22 for retaining lubricating oil is formed in the axial center of the end of the tip side of the claw portion 11 on the pocket-forming surface of the cage post portion 8 (the inner surface of the pocket 9). A chamfered portion 12 is formed along the ridge where the pocket-forming surface of the cage post portion 8 (the inner surface of the pocket 9) and the radially inner surface of the cage post portion 8 intersect.

[0091] In the above embodiments, a method for manufacturing a crown cage having concave spherical pockets 9 for accommodating balls as rolling elements 4 has been described as an example. However, the present invention can also be applied to other types of resin cages, and can also be applied to, for example, a method for manufacturing a comb cage having concave cylindrical pockets 9 for accommodating cylindrical rollers as rolling elements 4.

[0092] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0093] 1 Resin cage 2 outer ring 3. Inner circle 4 rolling elements 7 Retainer ring 8 Cage pillar section 9 pockets 14 Fibrous reinforcement 15 Molds 16 cylindrical blanks 17 Cylindrical cavity Gate 18 20 division blanks

Claims

1. A method for manufacturing a resin cage, in which a cage annular portion (7) and a plurality of cantilever-shaped cage bar portions (8) extending in the axial direction at intervals in the circumferential direction from the cage annular portion (7) are integrally formed from a resin composition in which a fibrous reinforcing material (14) is blended into a resin material, and pockets (9) for accommodating rolling elements (4) of a rolling bearing are formed between the cage bar portions (8) adjacent in the circumferential direction, a cylindrical blank production step in which a mold (15) having a cylindrical cavity (17) and a gate (18) opening at one axial end of the cylindrical cavity (17) is used, and the molten resin composition is injected into the cylindrical cavity (17) through the gate (18) to produce a hollow cylindrical blank (16) made of the resin composition in which the orientation direction of the fibrous reinforcing material (14) is axial; A method for manufacturing a plastic retainer, characterized by including, after the cylindrical blank manufacturing process, a cutting process in which the plastic retainer (1) is formed by cutting the cylindrical blank (16) so that the axial direction of the cylindrical blank (16) coincides with the axial direction of the plastic retainer (1).

2. 2. The method for manufacturing a resin cage according to claim 1, wherein the gate (18) of the mold (15) used in the cylindrical blank manufacturing process is a disk gate that opens annularly around the entire inner circumference of one axial end of the cylindrical cavity (17).

3. In the cylindrical blank manufacturing process, the axial length of the cylindrical cavity (17) is set to a length at least twice the axial length of the resin cage (1), thereby manufacturing the cylindrical blank (16) having an axial length at least twice the axial length of the resin cage (1); 3. A method for manufacturing a plastic retainer as described in claim 1 or 2, wherein in the cutting process, the cylindrical blank (16) is cut perpendicular to the axial direction to form a plurality of annular divided blanks (20), and each of the divided blanks (20) is cut to form a plurality of the plastic retainers (1).

4. 4. A method for manufacturing a plastic retainer as described in claim 3, wherein in the cutting process, when cutting the divided blank (20) located at the axial end farther from the gate (18) out of the multiple divided blanks (20) formed by cutting the cylindrical blank (16) perpendicular to the axial direction to form the plastic retainer (1), the plastic retainer (1) is formed in an orientation such that the retainer annular portion (7) is formed on the side farther from the gate (18) and the retainer column portion (8) is formed on the side closer to the gate (18).

5. 4. The method for manufacturing a plastic cage according to claim 3, wherein in the cutting process, the cylindrical blank (16) is cut perpendicular to the axial direction to form the plurality of divided blanks (20), and then, before cutting the divided blanks (20) to form the plastic cage (1), an annealing treatment is performed to heat the divided blanks (20) and remove residual stress.

6. 4. The method for manufacturing a plastic retainer according to claim 3, wherein in the cutting process, the cylindrical blank (16) is cut perpendicular to the axial direction to form the plurality of divided blanks (20), and then, before cutting the divided blanks (20) to form the plastic retainer (1), a humidity control treatment is performed in which the divided blanks (20) are left to stand in a constant temperature and humidity tank for a predetermined period of time.

7. 3. The method for manufacturing a resin cage according to claim 1, wherein the fibrous reinforcing material (14) mixed with the resin material is long fiber having a fiber length of 1.0 mm or more.

8. 3. A method for manufacturing a resin cage as described in claim 1 or 2, wherein the resin composition is one in which the fibrous reinforcing material (14) is blended in an amount that accounts for 20 to 70 mass % of the resin composition.

9. 3. The method for manufacturing a resin cage according to claim 1, wherein the cutting step uses a three-dimensional cutting machine and performs cutting based on three-dimensional data of the resin cage (1).

10. 3. A method for manufacturing a resin cage as described in claim 1 or 2, wherein the pocket forming surface that forms the pocket (9) of the cage column portion (8) is formed in a concave spherical shape to accommodate balls as the rolling elements (4).

11. A resin cage in which a cage annular portion (7) and a plurality of cantilever-shaped cage bar portions (8) extending in the axial direction at intervals in the circumferential direction from the cage annular portion (7) are integrally formed from a resin composition in which a fibrous reinforcing material (14) is blended into a resin material, and pockets (9) for accommodating rolling elements (4) of a rolling bearing are formed between the cage bar portions (8) adjacent in the circumferential direction, the orientation direction of the fibrous reinforcing material (14) in a portion of the retainer post portion (8) along a pocket forming surface that forms the pocket (9) is an axial direction that extends non-parallel to the pocket forming surface, The pocket forming surface of the retainer column portion (8) is a machined surface that exposes the cut surfaces of the numerous fibrous reinforcing materials (14) cut midway in the longitudinal direction.

12. 12. The resin cage according to claim 11, wherein the cage annular portion (7) and the plurality of cage column portions (8) are formed weldless, with no weld lines occurring at the confluence of the molten resin composition.

13. 13. The resin cage according to claim 11 or 12, wherein the pocket forming surface of the cage post portion (8) is formed in a concave spherical shape to accommodate balls as the rolling elements (4).

14. outer ring (2), an inner ring (3) disposed radially inside the outer ring (2); a plurality of rolling elements (4) incorporated between the outer ring (2) and the inner ring (3); A rolling bearing comprising the resin cage according to claim 11 or 12, which holds the plurality of rolling elements (4).

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