Cage, method for manufacturing a cage, rolling bearing, and mold
The cage design for rolling bearings addresses the issue of strength reduction by altering resin flow paths during molding to position weld lines at thicker parts, thereby maintaining structural integrity.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- MINEBEAMITSUMI INC
- Filing Date
- 2022-11-28
- Publication Date
- 2026-06-12
Smart Images
Figure 0007873628000001 
Figure 0007873628000002 
Figure 0007873628000003
Abstract
Description
【Technical Field】 【0001】 The present invention relates to a cage, a method for manufacturing a cage, a rolling bearing, and a mold. 【Background Art】 【0002】 For example, a rolling bearing is incorporated in a motor. The rolling bearing includes an inner ring, an outer ring disposed outside the inner ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and a cage having a plurality of pockets each accommodating a rolling element. The cage is formed, for example, by injection molding from a resin material. Patent Documents 1 and 2 disclose a technique for adjusting the position of a weld line by providing a meat theft in the cage to create a difference in the flow volume of the molten resin material flowing in from the gate. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Utility Model Publication No. 60-71728 【Patent Document 2】 Japanese Patent Application Laid-Open No. 2014-87941 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 In a conventional cage, by using the technique for adjusting the position of the weld line described above, the position of the weld line can be shifted from the position corresponding to the bottom of the pocket, which is a thin part. In this way, in a conventional rolling bearing, a configuration capable of suppressing a decrease in the strength of the cage has been demanded. 【0005】 The present invention has been made in view of the above problems, and an object thereof is to provide a cage, a method for manufacturing a cage, a rolling bearing, and a mold capable of suppressing a decrease in the strength of the cage. 【Means for Solving the Problems】 【0006】 To achieve the above objective, a cage according to a first aspect of the present invention is a cage for a rolling bearing, comprising: a base extending annularly in the circumferential direction about an axis; a plurality of columnar portions extending from the base along the axis and arranged in the circumferential direction; a plurality of pockets formed between pairs of adjacent columnar portions; a material removal portion which is a recessed portion inward from the base or the columnar portion toward the interior of the columnar portion at a position corresponding to the columnar portion; and a plurality of gate marks formed on the columnar portion or the base adjacent to the columnar portion, corresponding to the gate position during the molding of the cage, wherein at least one of the plurality of gate marks is formed on the columnar portion or the base adjacent to the columnar portion, corresponding to the material removal portion. 【0007】 A rolling bearing according to a second aspect of the present invention comprises an inner ring, an outer ring disposed on the outside of the inner ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and the above-described retainer which houses each of the plurality of rolling elements in the pockets between the inner ring and the outer ring. 【0008】 A method for manufacturing a cage according to a third aspect of the present invention includes the steps of injecting a resin material from a plurality of gates into a cavity of a mold shaped like the outer shape of a cage for a rolling bearing, and curing the resin material in the cavity to form the cage, wherein the cavity is shaped like an annular base extending circumferentially around an axis, a plurality of columnar portions extending from the base along the axis and arranged circumferentially, a plurality of pockets formed between pairs of adjacent columnar portions, and material removal recesses that are recessed from the base or the columnar portions toward the interior of the columnar portions at positions corresponding to the columnar portions, each gate being positioned on the columnar portion or the base adjacent to the columnar portion, and at least one of the gates being formed on the columnar portion or the base adjacent to the columnar portion corresponding to the outer shape of the material removal recess. 【0009】 A mold according to a fourth aspect of the present invention is a mold that defines a cavity shaped like the outer shape of a cage for a rolling bearing, wherein the cavity shaped like the outer shape of a base extending annularly in the circumferential direction about an axis, a plurality of columnar portions extending from the base along the axis and arranged in the circumferential direction, a plurality of pockets formed between pairs of adjacent columnar portions, and a material removal recess that is recessed from the base or the columnar portions toward the interior of the columnar portions at positions corresponding to the columnar portions, wherein a plurality of gates are connected to the cavity at positions corresponding to different columnar portions, and at least one of the plurality of gates is formed on the columnar portion or the base adjacent to the columnar portion, corresponding to the outer shape of the material removal recess. [Effects of the Invention] 【0010】 According to the present invention, it is possible to provide a cage that can suppress a decrease in the strength of the cage, a method for manufacturing the cage, a rolling bearing, and a mold. [Brief explanation of the drawing] 【0011】 [Figure 1] This is a schematic partial cross-sectional view showing the structure of a rolling bearing 1 according to one embodiment of the present invention. [Figure 2] This is a schematic plan view showing the structure of a retainer 5 according to a first specific example of the present invention. [Figure 3] This is a schematic perspective view showing the structure of a retainer 5 according to a first specific example of the present invention. [Figure 4] This is a partially enlarged side view schematically showing the structure of a retainer 5 according to a first specific example of the present invention. [Figure 5] This is a schematic perspective view showing the structure of a retainer 5 according to a first specific example of the present invention. [Figure 6] This is a schematic bottom view showing the structure of a retainer 5 according to a first specific example of the present invention. [Figure 7] This is a partial cross-sectional view along line 7-7 in Figure 6. [Figure 8] This figure schematically shows the structure of a mold 100 for manufacturing a retainer 5 according to a first specific example of the present invention. [Figure 9]A perspective view showing the outer shapes of the cavity 101 and the gate 110D of the mold 100 for manufacturing the cage 5 according to the first specific example of the present invention. [Figure 10] A bottom view schematically showing the structure of the cage 5A according to the second specific example of the present invention. [Figure 11] A perspective view schematically showing the structure of the cage 5A according to the second specific example of the present invention. [Figure 12] A view schematically showing the structure of the mold 100A for manufacturing the cage 5A according to the second specific example of the present invention. [Figure 13] A bottom view showing the outer shapes of the cavity 101 and the gate 110D of the mold 100 for manufacturing the cage 5A according to the second specific example of the present invention. [Figure 14] A bottom view schematically showing the structure of the cage 5B according to the third specific example of the present invention. [Figure 15] A view schematically showing the structure of the mold 100B for manufacturing the cage 5B according to the third specific example of the present invention. [Figure 16] A bottom view schematically showing the structure of the cage 5C according to the fourth specific example of the present invention. [Figure 17] A view schematically showing the structure of the mold 100C for manufacturing the cage 5C according to the fourth specific example of the present invention. 【Mode for Carrying Out the Invention】 【0012】 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view schematically showing the structure of a rolling bearing 1 according to an embodiment of the present invention. This rolling bearing 1 includes an inner ring 2, an outer ring 3 disposed outside the inner ring 2, a plurality of rolling elements 4 disposed between the inner ring 2 and the outer ring 3, and a cage 5 that holds the plurality of rolling elements 4. The inner ring 2, the outer ring 3, and the cage 5 are all annular members having the axis x as the central axis or substantially the central axis. The axis x is the axis of the rolling bearing 1. In addition, in FIG. 1, the rolling bearing 1 viewed in plan is shown in a state where the inner ring 2, the outer ring 3, and the cage 5 are cut and the rolling elements 4 are represented. In this rolling bearing 1, for example, the outer ring 3 is fixed to the housing of a motor (not shown), and the inner ring 2 is fixed to the shaft of the motor, so that the inner ring 2 and the outer ring 3 can rotate relative to each other around the axis x. 【0013】 On the outer peripheral surface of the inner ring 2 in the radial direction perpendicular to the axis x, a raceway groove 21 is formed. Similarly, on the inner peripheral surface of the outer ring 3 in the radial direction, a raceway groove 31 is formed. A plurality of rolling elements 4 are arranged in the circumferential direction around the axis x between these raceway grooves 21 and the raceway groove 31. The rolling element 4 is a sphere (ball), and therefore, the rolling bearing 1 is a rolling ball bearing. The inner ring 2 and the outer ring 3 are formed of, for example, stainless steel. The rolling element 4 is formed of, for example, stainless steel or ceramic. The cage 5 is formed of, for example, a resin material. A lubricant (not shown) such as grease is filled between the inner ring 2 and the outer ring 3. The lubricant reduces the friction between the rolling element 4 and the inner ring 2, the outer ring 3, and the cage 5. The rolling bearing 1 may include a pair of shield members (not shown) that seal the space between the inner ring 2 and the outer ring 3 in order to avoid leakage of the lubricant from the rolling bearing 1 to the outside and intrusion of foreign matter into the rolling bearing 1. 【0014】 Figure 2 is a schematic plan view showing the structure of a retainer 5 according to a first specific example of the present invention, and Figure 3 is a schematic perspective view showing the structure of a retainer 5 according to a first specific example of the present invention. Figure 3 is a perspective view of the retainer 5 as seen from one side (top) in the direction of the axis x. Referring together to Figures 1 to 3, the retainer 5 comprises an inner circumferential surface 5a facing the radially inward side of the retainer 5, an outer circumferential surface 5b facing the radially outward side of the retainer 5, and a bottom surface 5c defined on the other side (bottom) in the direction of the axis x, extending along a virtual plane perpendicular to the axis x. As is clear from Figure 1, the diameter of the inner circumferential surface 5a is larger than the diameter of the outer circumferential surface of the inner ring 2, and the diameter of the outer circumferential surface 5b is smaller than the diameter of the inner circumferential surface of the outer ring 3. 【0015】 Figure 4 is a schematic enlarged side view showing the structure of a retainer 5 according to a first specific example of the present invention. Referring to Figure 4, the retainer 5 comprises an annular base 51 with axis x as its central axis, a plurality of columnar portions 52 extending from the base 51 along axis x and arranged at intervals in the circumferential direction, and a plurality of pockets 53 formed between pairs of adjacent columnar portions 52. In this embodiment, for example, 11 columnar portions 52 and 11 pockets 53 are arranged alternately in the circumferential direction. Each columnar portion 52 constitutes a thick portion of the retainer 5. Each columnar portion 52 comprises a pair of claw portions 52a, 52a protruding along axis x, and a grease pocket 52b formed between the claw portions 52a, 52a. A pocket 53 is opened between one claw portion 52a of one columnar portion 52 and the other claw portion 52a of a columnar portion 52 circumferentially adjacent to this columnar portion 52. The grease pocket 52b holds the aforementioned lubricant and promotes a reduction in friction between the rolling elements 4 and the inner ring 2, outer ring 3, and cage 5. 【0016】 Each pocket 53 is recessed along the axis x. Each pocket 53 extends radially from the inner circumferential surface 5a to the outer circumferential surface 5b of the retainer 5. A rolling element 4 is housed in each pocket 53. The pocket 53 is opened by an opening 53a defined on one side (the upper side) in the axial x direction. The opening 53a is formed between a pair of claws 52a, 52a. The length of the opening 53a in the circumferential direction is defined to be, for example, less than the diameter of the rolling element 4. Each pocket 53 further defines a spherical surface 53b opposite the spherical surface of the rolling element 4. The spherical surface 53b is defined, for example, from a sphere that partially faces the outer circumferential surface of the rolling element 4 around the center of the rolling element 4. The spherical surface 53b is formed to be deepest at the center position C1 of the pocket 53 defined in the circumferential direction (see Figure 2). In other words, the center position C1 of the pocket 53 forms the thinnest part of the retainer 5. 【0017】 As shown in Figures 2 and 3, the retainer 5 further comprises a plurality of gate marks 54A to 54E, in this embodiment five, arranged circumferentially around axis x on its inner circumferential surface 5a. The gate marks 54A to 54E are formed at positions corresponding to the gate positions during the molding of the retainer 5. As will be described later, the gate marks 54A to 54E are irregularities shaped to the tip of the gate when the gate is separated from the molded retainer 5 after it has been removed from the mold used to mold the retainer 5. The shape of the gate marks 54A to 54E changes according to the shape of the tip of the gate, but in this embodiment, for example, they are formed in the shape of a flat cylinder. The gate marks 54A to 54E are formed on the inner circumferential surface 5a of the retainer 5 at the column portion 52 or the base portion 51 adjacent to the column portion 52. Note that each gate mark 54A to 54E may also be formed on the outer circumferential surface 5b of the retainer 5 at the column portion 52 or the base portion 51 adjacent to the column portion 52. From the viewpoint of moldability, it is preferable that each gate mark 54A to 54E be formed on the column portion 52 side. As is clear from Figure 2, the circumferential center C of each gate mark 54A to 54E coincides with the circumferential center position C2 of the column portion 52. An even number of pockets 53, i.e., two pockets 53, are arranged between each pair of circumferentially adjacent gate marks 54E, 54A, a pair of gate marks 54A, 54B, a pair of gate marks 54B, 54C, and a pair of gate marks 54C, 54D. On the other hand, an odd number of pockets 53, i.e., three pockets 53, are arranged between each pair of circumferentially adjacent gate marks 54D, 54E. 【0018】 Figure 5 is a schematic perspective view showing the structure of a retainer 5 according to a first specific example of the present invention, and Figure 6 is a schematic bottom view showing the structure of a retainer 5 according to a first specific example of the present invention. Figure 5 is a perspective view of the retainer 5 as seen from the other side (bottom side) in the axial x direction. Referring together to Figures 3, 5 and 6, the retainer 5 further comprises a material removal section 55, which is a recessed portion that extends from the base 51 toward the interior of the base 51 and the column 52 at a position corresponding to the column 52 in the circumferential direction. In this embodiment, the material removal section 55 is formed at a position corresponding to the column 52 where the gate mark 54D is formed. As is clear from Figure 6, the material removal section 55 comprises a circumferential end (first circumferential end) 55a and a circumferential end (second circumferential end) 55b defined in the circumferential direction, and extends between the circumferential end 55a and the circumferential end 55b with a predetermined circumferential length L1 in the circumferential direction. In the circumferential direction, the center of the material removal 55 coincides with the center position C2 of the column portion 52. That is, in the circumferential direction, the center of the material removal 55 also coincides with the center of the gate mark 54E. Note that the material removal 55 may be a recess that extends from the column portion 52 toward the interior of the column portion 52, rather than from the base portion 51. That is, the material removal 55 may be a recess in the column portion 52 from the inner circumferential surface 5a or the outer circumferential surface 5b of the retainer 5 toward the interior of the column portion 52. 【0019】 Figure 7 is a partial cross-sectional view along line 7-7 in Figure 6. As shown in Figure 7, the material removal 55 has a predetermined depth D from the bottom surface 5c toward one side (upper side) in the axial x direction. In this embodiment, the depth D is set to, for example, about half the height of the retainer 5 from the bottom surface 5c in the axial x direction. The radial length L2 of the material removal 55, defined in the radial direction, is set to, for example, about half the length from the inner circumferential surface 5a to the outer circumferential surface 5b, which is also defined in the radial direction. On the other hand, the gate marks 54D formed on the inner circumferential surface 5a of the column portion 52 or the base portion 51 adjacent to the column portion 52 face the inner circumferential surface of the material removal 55 in the radial direction. In this embodiment, the gate marks 54A to 54E are all located on the column portion 52. The gate marks 54A to 54C and 54E are located similarly to the gate mark 54D. Furthermore, it is preferable that the material removal section 55 has a circumferential length L1 that is greater than the radial length L2, that is, it is preferable that it has a shape that extends long in the circumferential direction. 【0020】 Next, a method for manufacturing the retainer 5 according to the first specific example of the present invention will be described. Injection molding is performed in the manufacture of the retainer 5. Figure 8 is a schematic diagram showing the structure of the mold 100 for manufacturing the retainer 5 according to the first specific example of the present invention. Figure 8 is a partially perspective cross-sectional view of the shape of the cavity 101 formed in the mold 100, viewed from the other side (bottom side) of axis x. The cavity 101 forms a cavity that extends in an annular shape in the circumferential direction around axis x. Axis x is the central axis or approximate central axis of the annular cavity 101 and coincides with the central axis of the retainer 5 manufactured by the mold 100. The cavity 101 coincides with the outer shape of the base 51, column 52, pocket 53 and material removal 55 of the retainer 5. The mold 100 forms the cavity 101 by combining multiple molds, but a detailed explanation of the mold combination will be omitted. 【0021】 Multiple gates, five in this embodiment, are connected to the cavity 101 of the mold 100. The gates 110A to 110E are arranged circumferentially around axis x. The circumferential positions of the gates 110A to 110E correspond to the positions of the gate marks 54A to 54E on the retainer 5, respectively. The mold 100 has a projection 100a that protrudes from the inner surface of the mold 100 toward the cavity 101 along axis x. The projection 100a matches the outer shape of the material removal 55. The gate 110D faces the projection 100a of the mold 100 in the radial direction perpendicular to axis x. Here, for the sake of explanation, only the projection 100a that forms the outer shape of the material removal 55 will be given a reference numeral, but as mentioned above, the cavity 101 matches the outer shapes of the base 51, column 52 and pocket 53. In this embodiment, gates 110A to 110E are arranged on the column portion 52, and gate 110D is arranged on the column portion 52 corresponding to the outer shape of the material removal section 55. 【0022】 During manufacturing, molten resin material is injected into the cavity 101 from each gate 110A to 110E at a predetermined flow rate almost simultaneously. Taking a pair of gates 110A and 110B as an example, the first flow F1 of molten resin material flowing in from gate 110A flows circumferentially toward gates 110B and 110E. Similarly, the first flow F1 of molten resin material flowing in from gate 110B flows circumferentially toward gates 110A and 110C. As a result, between a pair of gates 110A and 110B, the first flow F1 of molten resin material merges at a position equidistant circumferentially from gates 110A and 110B. This merging position of the molten resin material corresponds to the so-called weld line. The flow of the molten resin material is similar between a pair of gates 110B and 110C and between a pair of gates 110E and 110A. 【0023】 Figure 9 is a perspective view showing the external shape of the cavity 101 and gate 110D of a mold 100 for manufacturing a retainer 5 according to a first specific example of the present invention. Figure 9 shows a partially enlarged view of the gate 110D and the protrusion 100a as seen from the other side (bottom side) of axis x. Referring to Figure 9 as well, the molten resin material flowing into the cavity 101 from the gate 110D first collides with the inner circumferential surface of the protrusion 100a. Due to the presence of this protrusion 100a, the cross-sectional area of the inflow path of the molten resin material from the gate 110D into the cavity 101 is smaller than the cross-sectional area of the inflow path of the molten resin material from gates 110A to 110C and 110E where the protrusion 100a is not formed. Therefore, the protrusion 100a of the mold 100 acts as resistance to the inflow of molten resin material into the cavity 101. 【0024】 As a result, the second flow F2 of molten resin material flowing from gate 110D into cavity 101 is less efficient than the first flow F1 of molten resin material flowing from gates 110A-110C and 110E into cavity 101. Therefore, between gate 110D and gate 110C, the first flow F1 of molten resin material from gate 110C toward gate 110D merges with the second flow F2 of molten resin material from gate 110D toward gate 110C at a position circumferentially biased toward gate 110D. Similarly, between gate 110D and gate 110E, the first flow F1 of molten resin material from gate 110E toward gate 110D merges with the second flow F2 of molten resin material from gate 110D toward gate 110E at a position circumferentially biased toward gate 110D. Subsequently, the resin material hardens within the mold 100, and the molded body of the retainer 5, equipped with gates 110A to 110E, is removed from the mold 100. Then, the gates 110A to 110E are separated from the molded body of the retainer 5. In this way, the retainer 5 is manufactured from the mold 100. 【0025】 Here, Figure 8 shows the position of the weld line WL obtained from the simulation results performed on the software under the same conditions as the manufacturing method described above. Between a pair of gates 110A, 110B adjacent to each other in the circumferential direction, between a pair of gates 110B, 110C, and between a pair of gates 110E, 110A, the first flow F1 of molten resin material flows in from gates 110A~110C and 110E, and the weld line WL is positioned at a position approximately equidistant from each of the gates 110A~110C and 110E in the circumferential direction. Since an even number, i.e., two pockets 53, are positioned between these gates 110A~110C and 110E, the weld line WL approximately coincides with the circumferential center position C2 of the column portion 52. In other words, the weld line WL is formed in the retainer 5 at a position corresponding to the column portion 52, which is the thick portion. Furthermore, an even number of pockets 53, i.e., two pockets 53, are arranged between a pair of gates 110C and 110D that are adjacent to each other in the circumferential direction. Between these pairs of gates 110C and 110D, due to the difference in the ease with which the molten resin material flows (the second flow F2 is more difficult to flow than the first flow F1), a weld line WL is positioned in the circumferential direction, offset from the center position C2 of the column 52 towards the gate 110D side. However, the weld line WL almost coincides with the center position C2 of the column 52. 【0026】 On the other hand, an odd number of pockets 53, i.e., three pockets 53, are arranged between a pair of gates 110D and 110E that are adjacent to each other in the circumferential direction. Due to the difference in the ease with which the molten resin material flows between this pair of gates 110D and 110E (the second flow F2 is more difficult to flow than the first flow F1), the weld line WL is positioned circumferentially, offset towards gate 110D. That is, the equidistant point from the pair of gates 110D and 110E is the circumferential center position C1 of the middle pocket 53 of the three pockets 53, but the weld line WL is positioned offset from this center position C1 towards gate 110D. Therefore, the weld line WL is positioned offset from the center position C1 of the pocket 53, which is the thinnest part of the retainer 5. Furthermore, since the distance between adjacent gates 110 is greater when three pockets 53 are arranged than when two pockets 53 are arranged, the amount of deviation from the center position C1 of the weld line WL between gates 110D and 110E is considered to be greater than the amount of deviation from the center position C2 of the weld line WL between gates 110C and 110D. 【0027】 According to the retainer 5 and its manufacturing method described above, one of the two adjacent pairs of gate marks 54D and 54E (gates 110D and 110E), between which three pockets 53 are arranged, faces the material removal 55 (protrusion 100a) in the radial direction. With this configuration, during the manufacturing of the retainer 5, the second flow F2 of molten resin material flowing in from gate 110D is less likely to flow than the first flow F1 of molten resin material flowing in from the other gates 110A to 110C and 110E. As a result, the position of the weld line WL between gate marks 54D and 54E (gates 110D and 110E) is biased towards gate mark 54D (gate 110D). The weld line WL is positioned offset from the center position C1 of the pocket 53, which is the thinnest part of the retainer 5. Therefore, a decrease in the strength of the retainer 5 can be suppressed. 【0028】 In the manufacturing method described above, as the circumferential length, radial length, and depth of the protrusion 100a (circumferential length L1, radial length L2, and depth D of the protrusion 55) that matches the outer shape of the material removal 55 increase, the cross-sectional area of the path through which the molten resin material flows decreases. Therefore, in order to increase the difference in the ease of flow of the molten resin material, it is preferable to increase the circumferential length, radial length, and depth of the protrusion 100a. In particular, the circumferential length has the greatest effect on the reduction of the cross-sectional area of the path. Therefore, although there are limits depending on the size of the cavity 101, i.e., the retainer 5, it is possible to adjust the circumferential position of the weld line WL by increasing the circumferential length, radial length, and depth of the protrusion 100a. For example, it is preferable to set the circumferential length L1 of the material removal 55 to be greater than the length of the grease pocket 52b, which is similarly defined in the circumferential direction. 【0029】 Figure 10 is a schematic bottom view showing the structure of a retainer 5A according to a second specific example of the present invention. Figure 11 is a schematic perspective view showing the structure of a retainer 5A according to a second specific example of the present invention. In the following drawings, components identical to those in the retainer 5 according to the first specific example are denoted by the same reference numerals, and redundant explanations are omitted. Hereinafter, the configuration of the retainer 5A according to the second specific example will be described in a way that differs from that of the retainer 5 according to the first specific example. Although Figure 10 is a bottom view of the retainer 5A, for the sake of explanation, the outlines of the column 52 and pockets 53 as seen through from the bottom surface 5c side of the retainer 5A are shown by dotted lines. As shown in Figures 10 and 11, the retainer 5A according to the second specific example differs from the retainer 5 according to the first specific example in that a pair of gate marks 54D and 54E, which arrange three pockets 53 between them, are offset in the same circumferential direction over a predetermined angular range from the center position C2 of the column 52. The other components of the retainer 5A in the second example are the same as those of the retainer 5 in the first example. 【0030】 Specifically, in the second example of the retainer 5A, the gate marks 54D and 54E are offset clockwise by an angle α when viewed from the bottom. However, the angle of offset between the gate marks 54D and 54E does not necessarily have to be the same. One of the pair of gate marks 54D and 54E, gate mark 54D, is located on the circumferential end 55a side of the material removal 55, opposite to the circumferential end 55b of the material removal 55, which is located on the side of the other gate mark 54E. In this second example, in the circumferential direction, the center C of gate mark 54D almost coincides with the circumferential end 55a of the material removal 55. Thus, the gate mark 54D is partially opposite the material removal 55 in the radial direction. On the other hand, the other gate mark 54E of the pair of gate marks 54D and 54E is offset circumferentially towards the material removal 55 side from the center position C2 of the column portion 52, but the position of gate mark 54E in the circumferential direction is located on the column portion 52. In the second specific example of the retainer 5A, the circumferential center C of the other gate mark 54E may coincide with the center position C2 of the column portion 52. That is, only one of the gate marks 54D may be offset in the circumferential direction. 【0031】 Next, a method for manufacturing the retainer 5A according to a second specific example of the present invention will be described. Figure 12 corresponds to Figure 8 and schematically shows the structure of a mold 100A for manufacturing the retainer 5A according to a second specific example of the present invention. This mold 100A differs from the mold 100 described above in that a pair of gates 110D and 110E, which position the formation locations of three pockets 53 between them, are shifted in the same direction circumferentially over a predetermined angular range from the center position C2 of the formation location of the column portion 52. Specifically, in a bottom view, the gates 110D and 110E are shifted clockwise by an angle α. However, the angle of shift of the gates 110D and 110E does not necessarily have to be the same. One of the pair of gates 110D and 110E, gate 110D, is positioned on the side of the circumferential end (first circumferential end) 100a1 opposite to the circumferential end (second circumferential end) 100a2 of the protrusion 100a on the other gate 110E side. In this second specific example, in the circumferential direction, the center C of gate 110D substantially coincides with the circumferential end 100a1 of the projection 100a. Thus, gate 110D is partially opposite to projection 100a in the radial direction. On the other hand, gate 110E, one of the pair of gates 110D and 110E, is positioned offset towards projection 100a in the circumferential direction, but in the circumferential direction, the position of gate 110E is located at the formation position of column 52. 【0032】 During manufacturing, molten resin material is injected into the cavity 101 at a predetermined flow rate from each gate 110A to 110E almost simultaneously. Figure 13 is a bottom view showing the external shape of the cavity 101 and gate 110D of a mold 100 for manufacturing a retainer 5A according to a second specific example of the present invention. Figure 13 shows a partially enlarged view of the gate 110D and the protrusion 100a as seen from the other side (bottom side) along the axis x. Referring to Figure 13 as well, in the circumferential direction, the center C of the gate 110D almost coincides with the circumferential end 100a2 of the protrusion 100a, so that almost the entire protrusion 100 is positioned in the path of the molten resin material from gate 110D to gate 110E. As a result, the cross-sectional area of the path of the molten resin material from gate 110D to gate 110E is reduced. Thus, the protrusion 100a of the mold 100 acts as resistance to the flow of the molten resin material within the cavity 101. On the other hand, no protrusions 100a are placed in the path of the molten resin material from gate 110D towards gate 110C. 【0033】 As a result, the third flow F3 of molten resin material flowing from gate 110D towards gate 110E becomes relatively more difficult to flow than the fourth flow F4 of molten resin material flowing from gate 110D towards gate 110C. On the other hand, since the protrusion 100a is not located in the path of the molten resin material flowing in from gates 110A to 110C, the first flow F1 of molten resin material flowing in from gates 110A to 110C flows toward the adjacent gate 110, as described above. Also, since gate 110E is positioned circumferentially biased toward the protrusion 100a side, the fifth flow F5 and sixth flow F6 of molten resin material flow from gate 110E toward gates 110A and 110D, respectively. 【0034】 Figure 12 shows the position of the weld line WL obtained from the simulation results performed on the software for the retainer 5A of the second specific example, similar to the first specific example. Between pairs of gates 110A and 110B that are adjacent to each other in the circumferential direction, between pairs of gates 110B and 110C, between pairs of gates 110C and 110D, and between pairs of gates 110E and 110A, the weld line WL was positioned at approximately equidistant from each gate 110 in the circumferential direction. That is, the weld line WL was formed in the retainer 5 at a position corresponding to the columnar portion 52, which is a thick-walled portion. On the other hand, between pairs of gates 110D and 110E, the third flow F3 of molten resin material from gate 110D to gate 110E is relatively obstructed, so the position of the weld line WL between gates 110D and 110E was offset from the center position C1 of the pocket 53, which is the thinnest-walled portion of the retainer 5. With the retainer 5A and its manufacturing method described above, the reduction in strength of the retainer 5A is suppressed, similar to the first specific example. 【0035】 Figure 14 is a schematic bottom view showing the structure of a retainer 5B according to a third specific example of the present invention. The configuration of the retainer 5B according to the third specific example will be described below, differing from that of the retainers 5 and 5A according to the first and second specific examples. Although Figure 14 shows a bottom view of the retainer 5B, for the sake of clarity, the outlines of the column portion 52 and pocket 53 are shown with dotted lines. As shown in Figure 14, the retainer 5B according to the third specific example differs from the retainers 5 and 5A according to the first and second specific examples in that it has six gate marks 54A to 54F. Furthermore, an odd number of pockets 53, i.e., one pocket, are arranged between a pair of gate marks 54D and 54E. On the other hand, an even number of pockets 53, i.e., 2 pockets 53, are placed between each pair of gate marks 54A, 54B, 54B, 54C, 54C, 54D, 54E, 54F, and 54F, 54A that are adjacent to each other in the circumferential direction. In other words, in the third specific example, the number of pockets 53 placed between a pair of gate marks 54D, 54E is smaller than the number of pockets 53 placed between other pairs of gate marks 54 other than this pair of gate marks 54D, 54E. 【0036】 Furthermore, a pair of gate marks 54D and 54E, each containing a pocket 53, are offset in the same circumferential direction over a predetermined angular range from the center position C2 of the column portion 52. In a bottom view, the gate marks 54D and 54E are offset clockwise by an angle α. However, the angles of offset between the gate marks 54D and 54E do not necessarily have to be the same. One of the pair of gate marks 54D and 54E, gate mark 54E, is located on the circumferential end (second circumferential end) 55a side of the material removal 55 on the other gate mark 54D side. In the circumferential direction, the center C of gate mark 54E approximately coincides with the circumferential end 55a of the material removal 55. As a result, the gate mark 54E partially faces the material removal 55 in the radial direction. On the one hand, one of the pair of gate marks 54D and 54E, the other gate mark 54D, is positioned offset in the circumferential direction to the opposite side from the material removal 55, while the position of gate mark 54E in the circumferential direction is located on the column 52. Note that, as in the specific example described above, the circumferential center C of the other gate mark 54D may coincide with the center position C2 of the column 52. That is, only one of the gate marks 54E may be positioned offset in the circumferential direction. 【0037】 Next, a method for manufacturing the retainer 5B according to a third specific example of the present invention will be described. Figure 15 corresponds to Figures 8 and 12 and schematically shows the structure of the mold 100B for manufacturing the retainer 5B according to the third specific example of the present invention. This mold 100B differs from the molds 100 and 100A described above in that six gates 110A to 110F are connected to the cavity 101. In addition, a pair of gates 110D and 110E, which position the formation location of one pocket 53 between them, are offset in the same circumferential direction over a predetermined angular range from the center position C2 of the formation location of the column portion 52. The positions of gates 110A to 110F in the circumferential direction coincide with the gate marks 54A to 54F in the retainer 5B, respectively. In this third specific example, in a bottom view, gates 110D and 110E are offset clockwise by an angle α. In the circumferential direction, the center C of one of the pair of gates 110D and 110E is approximately coincident with the circumferential end (second circumferential end) 100a1 of the projection 100a on the other gate 110D of the pair of gates 110D and 110E. As a result, gate 110E is partially opposite to the projection 100a in the radial direction. On the other hand, the other gate 110D is offset in the circumferential direction to the opposite side from the projection 100a, but the position of gate 110E in the circumferential direction is located at the formation position of the column 52. 【0038】 During manufacturing, molten resin material is injected into the cavity 101 at a predetermined flow rate from each gate 110A to 110F almost simultaneously. As shown in the simulation results in Figure 15, the position of the weld line WL approximately coincides with the center position C2 of the formation position of the column 52 between the pair of gates 110A and 110B, between gates 110B and 110C, between gates 110C and 110D, between gates 110E and 110F, and between gates 110F and 110A, with two pockets 53 positioned between them. On the other hand, between the pair of gates 110D and 110E, since gate 110E faces the second circumferential end 100a1 of the protruding piece 100a, the fourth flow F4 of molten resin material from gate 110E towards gate 110D is relatively easier to flow than the third flow F3 of molten resin material from gate 110E towards gate 110F. On the other hand, although the gate 110D does not face the protruding piece 100a, due to the circumferential displacement, the area from gate 110D to gate 110C becomes a thin-walled portion where the pocket 53 is formed, and the area from gate 110D to gate 110E becomes a thick-walled portion where the column 52 is formed. In other words, the volume that the fifth flow F5 of molten resin material moving from gate 110D to gate 110E fills the cavity 101 before forming the weld line WL is relatively larger compared to the case where the position of gate 110D almost coincides with the center position C2 where the column 52 is formed. As a result, the weld line WL is positioned circumferentially offset from the center position C1 of the pocket 53, which is the thinnest part of the retainer 5. With the retainer 5B and its manufacturing method described above, the reduction in strength of the retainer 5B is suppressed, similar to the first and second specific examples. 【0039】 In the first and second specific examples, the retainers 5 and 5A have five gate marks 54A to 54E (gates 110A to 110E), and three pockets 53 are placed between a pair of gate marks 54D and 54E. On the other hand, the retainer 5B in the third specific example has six gate marks 54A to 54F (gates 110A to 110F), and the three pockets placed between a pair of gate marks 54D and 54E in retainers 5 and 5A are placed between gate marks 54D, 54E, and 54F in retainer 5B. Therefore, one pocket 53 is placed between gate marks 54D and 54E in retainer 5B. In other words, the number of pockets 53 placed between each gate mark 54 is reduced. As a result, the distance traveled by the molten resin material flowing between each gate 110 is reduced, so the filling pressure of the molten resin material flowing in the cavity 101 can be increased. Therefore, the retainer 5B according to the third specific example can further suppress the reduction in strength compared to the retainers 5 and 5A according to the first and second specific examples. 【0040】 Figure 16 is a schematic bottom view showing the structure of the retainer 5C according to the fourth specific example of the present invention. Below, the configuration of the retainer 5C according to the fourth specific example will be described in a way that differs from that of the retainer 5B according to the third specific example. Although Figure 16 shows a bottom view of the retainer 5C, for the sake of explanation, the outer shapes of the column portion 52 and the pocket 53 are shown with dotted lines. As shown in Figure 16, the retainer 5C according to the fourth specific example differs from the retainer 5B according to the third specific example in that the material removal 55 faces the gate mark 54D rather than the gate mark 54E. Specifically, one of the pair of gate marks 54D, 54E, the gate mark 54D, is located on the side of the circumferential end (first circumferential end) 55a of the material removal 55, opposite to the other gate mark 54E. In the circumferential direction, the center C of the gate mark 54D almost coincides with the circumferential end 55a of the material removal 55. Thus, the gate mark 54D partially faces the material removal 55 in the radial direction. 【0041】 Next, a method for manufacturing the retainer 5C according to the fourth specific example of the present invention will be described. Figure 17 corresponds to Figure 15 and schematically shows the structure of the mold 100C for manufacturing the retainer 5C according to the fourth specific example of the present invention. Compared with the mold 100B described above, in this mold 100C, the protruding piece 100a that matches the outer shape of the material removal 55 faces the gate 110D instead of the gate 110E. Specifically, in the circumferential direction, the center C of the gate 110D almost coincides with the circumferential end (first circumferential end) 100a1 of the protruding portion 100a opposite to the end 100a2 on the other gate 110E side. Molten resin material is injected into the cavity 101 at a predetermined flow rate almost simultaneously from each gate 110A to 110F. As a result, as shown in the simulation results in Figure 17, a position of the weld line WL is secured that is almost the same as in the case of the third specific example. 【0042】 Specifically, between a pair of gates 110D and 110E that are offset in a clockwise direction, gate 110D faces the end 100a1 of the protruding piece 100a. Therefore, the third flow F3 of molten resin material from gate 110D to gate 110E is relatively less likely to flow compared to the fourth flow F4 of molten resin material from gate 110D to gate 110C. As a result, the weld line WL is offset from the center position C1 of the pocket 53, which is the thinnest part of the retainer 5C. With the retainer 5C and its manufacturing method described above, the reduction in strength of the retainer 5C is suppressed, similar to the first to third specific examples. 【0043】 Although embodiments of the present invention have been described above, the present invention is not limited to the rolling bearings 5, 5A, 5B, and 5C according to the embodiments of the invention described above, but includes all embodiments included in the concept and claims of the present invention. Furthermore, each component may be selectively combined as appropriate to achieve at least some of the above-described problems and effects. For example, the shape, material, arrangement, size, etc., of each component in the above embodiments may be appropriately changed depending on the specific use of the present invention. [Explanation of Symbols] 【0044】 1...Rolling bearing, 2...Inner ring, 21...Inner ring raceway, 3...Outer ring, 31...Outer ring raceway, 4...Rolling element, 5, 5A, 5B, 5C...Cage, 5a...Inner circumferential surface, 5b...Outer circumferential surface, 5c...Bottom surface, 51...Base, 52...Column, 52a...Claw, 52b...Grease pocket, 53...Pocket, 53a...Open section, 53b...Spherical surface, 54A~54F...Gate mark, 55...Weight removal, 55a...Circumferential end, 55b...Circumferential end, 100...Mold, 100a...Protrusion, 100a1...Circumferential end, 100a2...Circumferential end, 101...Cavity, 110A~110F...Gate, C...Center, C1...Center position, C2...Center position, x...Axis, WL...Weld line
Claims
[Claim 1] A cage for a rolling bearing, A base that extends in an annular shape in the circumferential direction around the axis, A plurality of columnar portions extending from the base along the axis and arranged in the circumferential direction, A plurality of pockets are formed between each of a pair of adjacent column portions, A portion that is recessed from the base or the column towards the interior of the column at a position corresponding to the column, The retainer comprises a plurality of gate marks formed on the column portion or the base portion adjacent to the column portion, corresponding to the gate position during molding of the retainer, At least one of the plurality of gate marks is formed on the column portion or the base portion adjacent to the column portion, corresponding to the meat removal. Between them, one of a pair of adjacent gate marks, in which an odd number of the aforementioned pockets are arranged, faces the material removal in the radial direction perpendicular to the axis, The meat removal includes a first circumferential end and a second circumferential end located on the other gate mark side, and the one gate mark is located on the first circumferential end side. retainer. [Claim 2] The pair of gate marks are offset in the same circumferential direction from the center of the column. The retainer according to claim 1. [Claim 3] The number of pockets positioned between the pair of gate marks is smaller than the number of pockets positioned between other pairs of adjacent gate marks other than the pair of gate marks. The retainer according to claim 1. [Claim 4] A cage for a rolling bearing, A base that extends in an annular shape in the circumferential direction around the axis, A plurality of columnar portions extending from the base along the axis and arranged in the circumferential direction, A plurality of pockets are formed between each of a pair of adjacent column portions, A portion that is recessed from the base or the column towards the interior of the column at a position corresponding to the column, The retainer comprises a plurality of gate marks formed on the column portion or the base portion adjacent to the column portion, corresponding to the gate position during molding of the retainer, At least one of the plurality of gate marks is formed on the column portion or the base portion adjacent to the column portion, corresponding to the meat removal. Between them, one of a pair of adjacent gate marks, in which an odd number of the aforementioned pockets are arranged, faces the material removal in the radial direction perpendicular to the axis, The meat removal includes a first circumferential end and a second circumferential end located on the other gate mark side, and the one gate mark is located on the second circumferential end side. retainer. [Claim 5] The pair of gate marks are offset in the same circumferential direction from the center of the column. The retainer according to claim 4. [Claim 6] The number of pockets positioned between the pair of gate marks is smaller than the number of pockets positioned between other pairs of adjacent gate marks other than the pair of gate marks. The retainer according to claim 4. [Claim 7] An inner ring, an outer ring positioned outside the inner ring, and a plurality of rolling elements positioned between the inner ring and the outer ring, Each of the plurality of rolling elements is housed in the pocket between the inner ring and the outer ring. A rolling bearing comprising a cage according to any one of claims 1 to 6. [Claim 8] The process involves injecting resin material from multiple gates into the cavity of a mold shaped like the outer form of a rolling bearing cage, The step of curing the resin material in the cavity to form the retainer includes: fruit, The aforementioned cavity is The shape is formed of a base extending annularly in the circumferential direction around an axis, a plurality of columnar parts extending from the base along the axis and arranged in the circumferential direction, a plurality of pockets formed between pairs of adjacent columnar parts, and material removal recesses that are recessed from the base or the columnar parts toward the interior of the columnar parts at positions corresponding to the columnar parts. Each gate is positioned on the column or the base adjacent to the column, and at least one of the gates is formed on the column or the base adjacent to the column, corresponding to the outer shape of the material removal. In the cavity, one of a pair of adjacent gates, between which an odd number of pocket outlines are arranged, faces the material removal outline in a radial direction perpendicular to the axis. The external shape of the meat scavenger comprises a first circumferential end and a second circumferential end located on the other gate side of the pair of gates, the one gate being positioned on the first circumferential end side. A method for manufacturing a retainer. [Claim 9] A step of injecting resin material from multiple gates into a cavity of a mold shaped like the outer shape of a cage for a rolling bearing, The step of curing the resin material in the cavity to form the retainer includes: fruit, The aforementioned cavity is The shape is formed of a base extending annularly in the circumferential direction around an axis, a plurality of columnar parts extending from the base along the axis and arranged in the circumferential direction, a plurality of pockets formed between pairs of adjacent columnar parts, and material removal recesses that are recessed from the base or the columnar parts toward the interior of the columnar parts at positions corresponding to the columnar parts. Each gate is positioned on the column or the base adjacent to the column, and at least one of the gates is formed on the column or the base adjacent to the column, corresponding to the outer shape of the material removal. In the cavity, one of a pair of adjacent gates, between which an odd number of pocket outlines are arranged, faces the material removal outline in a radial direction perpendicular to the axis. The external shape of the meat scavenger comprises a first circumferential end and a second circumferential end located on the other gate side of the pair of gates, the one gate being positioned on the second circumferential end side. A method for manufacturing a retainer. [Claim 10] The pair of gates are offset in the same circumferential direction from the center of the column. A method for manufacturing the retainer according to claim 8 or 9. [Claim 11] The number of pockets arranged between the pair of gates is smaller than the number of pockets arranged between other pairs of adjacent gates other than the pair of gates. A method for manufacturing the retainer according to claim 8 or 9. [Claim 12] A mold that defines a cavity shaped like the outer form of a cage for a rolling bearing, The aforementioned cavity is The shape is formed of a base extending annularly in the circumferential direction around an axis, a plurality of columnar parts extending from the base along the axis and arranged in the circumferential direction, a plurality of pockets formed between pairs of adjacent columnar parts, and material removal recesses that are recessed from the base or the columnar parts toward the interior of the columnar parts at positions corresponding to the columnar parts. Multiple gates are connected to the cavity at positions corresponding to different column sections. At least one of the plurality of gates is formed on the column portion or the base portion adjacent to the column portion, corresponding to the outer shape of the meat removal. In the cavity, one of a pair of adjacent gates, between which an odd number of pocket outlines are arranged, faces the material removal outline in a radial direction perpendicular to the axis. The external shape of the meat scavenger comprises a first circumferential end and a second circumferential end located on the other gate side of the pair of gates, the one gate being positioned on the first circumferential end side. Mold. [Claim 13] A mold for defining a cavity that is shaped like the outer form of a cage for a rolling bearing, The aforementioned cavity is The shape is formed of a base extending annularly in the circumferential direction around an axis, a plurality of columnar parts extending from the base along the axis and arranged in the circumferential direction, a plurality of pockets formed between pairs of adjacent columnar parts, and material removal recesses that are recessed from the base or the columnar parts toward the interior of the columnar parts at positions corresponding to the columnar parts. Multiple gates are connected to the cavity at positions corresponding to different column sections. At least one of the plurality of gates is formed on the column portion or the base portion adjacent to the column portion, corresponding to the outer shape of the meat removal. In the cavity, one of a pair of adjacent gates, between which an odd number of pocket outlines are arranged, faces the material removal outline in a radial direction perpendicular to the axis. The external shape of the meat scavenger comprises a first circumferential end and a second circumferential end located on the other gate side of the pair of gates, the one gate being positioned on the second circumferential end side. Mold.