Retainer, rolling bearing, and method for molding retainer

Abstract

This synthetic resin retainer 14 comprises: an annular body 17; a plurality of horns 19; a plurality of gate marks 28 formed at intervals in the circumferential direction; a weld 24 formed between the gate marks 28 adjacent to each other in the circumferential direction; and a plurality of pocket forming parts 21 that are respectively disposed between the gate marks 28 and in which pockets 15 are formed. Each pocket forming part 21 has, at the bottom of the pocket 15, a through-hole 23 formed penetrating in the axial direction. The weld 24 is formed between the gate marks 28 only in a region R1 closer to one side in the circumferential direction than the through-hole 23 or only in a region R2 closer to the other side in the circumferential direction than the through-hole.

Description

Cage, rolling bearing, and method for forming a cage

[0001] The present invention relates to a cage, a rolling bearing, and a method for forming a cage.

[0002] For example, with regard to rolling bearings used in drive units such as automobile transmissions, there is a demand for reducing the axial width of the rolling bearings as drive units become smaller. If the width of the rolling bearing is reduced, the cage that holds the rolling elements may protrude axially beyond the side surfaces of the outer and inner rings. This may cause the cage to interfere with other components and be damaged during the manufacturing process, packaging, or transportation of the rolling bearing. Therefore, when reducing the width of the rolling bearing, it is necessary to ensure that the cage does not protrude axially beyond the side surfaces of the outer and inner rings. Therefore, it has been considered to reduce the width of the rolling bearing by using a crown-shaped cage made of synthetic resin (see, for example, Patent Document 1).

[0003] FIG. 10 is a perspective view showing a portion of a conventional synthetic resin crown cage 90. FIG. 11 is a cross-sectional view of a rolling bearing 80 equipped with the crown cage 90. As shown in FIGS. 10 and 11 , the crown cage 90 includes an annular body 91 and a plurality of horns 92. The annular body 91 is annular. The annular body 91 is disposed on one axial side between the outer ring 81 and the inner ring 82. The plurality of horns 92 protrude from the annular body 91 on the other axial side. A pocket 93 is a space surrounded by two adjacent horns 92 and the annular body 91 between the two horns 92. The rolling elements 83 are accommodated in the pocket 93. This crown cage 90 has a thin axial thickness t11 at the bottom 91a of the pocket 93 of the annular body 91. Because the thickness t11 is thin, the axial width W11 of the rolling bearing 80 is smaller than that of a rolling bearing using a standard dimensional system.

[0004] Japanese Patent Application Laid-Open No. 2019-127974

[0005] As described above, the axial width W11 of the rolling bearing can be reduced by reducing the thickness t11 of the bottom 91 a of the annular body 91 of the crown cage 90. However, because the thickness t11 is thin, the strength of the crown cage 90 is reduced compared to rolling bearings of standard dimensions. For this reason, there is a limit to how thin the thickness of the bottom 91 a of the annular body 91 can be made.

[0006] The present invention makes it possible to minimize the axial width of a rolling bearing while ensuring the strength of the cage.

[0007] The retainer of the present invention comprises an annular body and a plurality of horns that protrude from the annular body to one side in the axial direction at intervals around the annular body, and is made of synthetic resin, in which a plurality of pockets that hold a plurality of rolling elements of a rolling bearing so that they can roll freely are formed between adjacent horns in the circumferential direction, and the retainer comprises a plurality of gate marks formed at intervals around the circumferential direction, welds formed between adjacent gate marks in the circumferential direction, and a plurality of pocket forming portions that are respectively positioned between the gate marks and in which each of the pockets is formed, each of the pocket forming portions having a through hole formed axially at the bottom of the pocket, and the welds are formed between the gate marks only in the region on one side of the through hole in the circumferential direction or only in the region on the other side of the through hole in the circumferential direction.

[0008] The rolling bearing of the present invention comprises an inner ring, an outer ring, a plurality of rolling elements arranged between the inner ring and the outer ring, and the cage.

[0009] The cage molding method of the present invention is a method of molding the cage using a mold having a plurality of runners, a plurality of gates connected to each of the runners, and an annular cavity in which the plurality of gates are connected at circumferential intervals, wherein the cavity is formed with a plurality of pocket molding spaces in which each of the pocket forming portions is molded and a plurality of one molding spaces in which each of the one forming portions is molded, alternately formed in the circumferential direction, and one of the gates is connected to each of the one molding spaces, and when molten resin is poured from each of the runners into the cavity through the gate, the volume of molten resin poured from one of two circumferentially adjacent gates is made greater than the volume of molten resin poured from the other gate.

[0010] According to the present invention, the axial width of the rolling bearing can be made as small as possible while ensuring the strength of the cage.

[0011] FIG. 3 is a cross-sectional view of a rolling bearing according to an embodiment of the present invention. FIG. 4 is a perspective view of a cage of the rolling bearing. FIG. 5 is a perspective view of an annular part of the cage. FIG. 6 is a cross-sectional view taken along the arrows I-I in FIG. 2. FIG. 7 is a front view of the annular part as viewed from the axially inner side. FIG. 8 is a perspective view of a part of the annular part. FIG. 9 is a view of a part of a pair of exploded annular parts as viewed from the radially inner side. FIG. 10 is a perspective view of a mold for molding the annular part by injection molding. FIG. 11 is a plan view of the mold. FIG. 12 is a perspective view of a part of a conventional crown cage made of synthetic resin. FIG. 13 is a cross-sectional view of a rolling bearing equipped with a conventional crown cage.

[0012] First, the contents of the embodiments will be described below. <Outline of the Embodiments> (1) A cage according to the embodiment includes an annular body and a plurality of tines that are spaced apart in the circumferential direction of the annular body and protrude from the annular body toward one side in the axial direction, and is made of synthetic resin, and a plurality of pockets that rollably hold a plurality of rolling elements of a rolling bearing are formed between adjacent tines in the circumferential direction, and the cage includes a plurality of gate marks that are spaced apart in the circumferential direction, welds that are formed between the adjacent gate marks in the circumferential direction, and a plurality of pocket forming portions that are respectively disposed between the gate marks and in which the pockets are formed, and each of the pocket forming portions has a through hole that is formed in the axial direction at a bottom of the pocket, and the welds are formed between the gate marks only in a region on one side in the circumferential direction of the through hole or only in a region on the other side in the circumferential direction of the through hole.

[0013] According to the above-described cage, through holes are formed in the bottoms of the pockets in the pocket forming portions, so that the axial thickness of the bottoms of the pocket forming portions can be made as thin as possible. This allows the axial width dimension of the rolling bearing to be reduced. Furthermore, welds are formed between circumferentially adjacent gate marks only in the region on one circumferential side or the other circumferential side of the through holes. This prevents the formation of the weakest welds in the regions (stress concentration regions) radially outward and radially inward of the through holes in the pocket forming portions during use of the rolling bearing. Therefore, the strength of the cage can be ensured even when through holes are formed in the pocket forming portions.

[0014] (2) In the cage described in (1), the weld preferably has a first weld portion that extends radially in the entire direction as viewed in the axial direction, and a second weld portion that extends circumferentially from a radially intermediate position of the first weld portion to the through hole as viewed in the axial direction. In this case, the strength of the cage can be further increased compared to when only the second weld portion is formed to extend circumferentially in a region on one circumferential side or the other circumferential side of the through hole.

[0015] (3) The cage described in (2) above preferably further includes a plurality of horn formation portions where the horns are formed, and each of the horn formation portions preferably has one gate mark formed therein. In this case, when the cage is molded using a mold, molten resin flows into the mold from gates corresponding to all of the horn formation portions. Therefore, by controlling the volume of molten resin flowing from each gate, it is possible to easily form the first weld and the second weld in the region on one circumferential side or the other circumferential side of the through hole.

[0016] (4) The cage according to any one of (1) to (3) is preferably configured by a pair of annular parts each including the annular body and the plurality of tines, which are connected in the axial direction. In this case, since the cage is configured by the pair of annular parts, the strength of the cage can be further increased compared to a cage configured by only a single annular part and having pillars formed by connecting the tines of the pair of annular parts.

[0017] (5) A rolling bearing according to an embodiment includes an inner ring, an outer ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and the cage according to any one of (1) to (3). The rolling bearing exhibits the same effects as the cage.

[0018] (6) A rolling bearing according to an embodiment includes an inner ring, an outer ring, a plurality of rolling elements disposed between the inner ring and the outer ring, and the cage described in (4). The rolling bearing provides the same effects as the cage.

[0019] (7) A retainer molding method according to an embodiment is a method for molding the retainer described in (3) above using a mold having a plurality of runners, a plurality of gates connected to each runner, and an annular cavity in which the plurality of gates are connected at circumferential intervals, wherein the cavity is formed with a plurality of pocket molding spaces in which each of the pocket forming portions is molded and a plurality of one molding spaces in which each of the one forming portions is molded, arranged alternately in the circumferential direction, and one of the gates is connected to each of the one molding spaces, and when molten resin is poured from each of the runners into the cavity through the gate, the volume of molten resin poured from one of two circumferentially adjacent gates is made larger than the volume of molten resin poured from the other gate.

[0020] According to the cage molding method described above, in a pocket molding space formed between one molding space connected to one gate and the other molding space connected to the other gate, the volume of molten resin flowing from one molding space is greater than the volume of molten resin flowing from the other molding space. This makes it easier for the molten resin flowing from one molding space and the molten resin flowing from the other molding space to meet on one or the other circumferential side of the through hole in the pocket forming portion. This makes it easier to form the first weld and the second weld in the region on one or the other circumferential side of the through hole.

[0021] <Details of the embodiment> Preferred embodiments will now be described with reference to the drawings. [Rolling bearing] Fig. 1 is a cross-sectional view of a rolling bearing 10 according to an embodiment of the present invention. The rolling bearing 10 comprises an inner ring 11, an outer ring 12, a plurality of rolling elements 13, and a cage 14. In the following description, the side closer to the axial center C1 of the rolling bearing 10 may be referred to as the axial inner side, and the side farther from the axial center C1 may be referred to as the axial outer side.

[0022] The inner ring 11 is annular. The outer ring 12 is annular. The outer ring 12 is arranged radially outward of the inner ring 11. A plurality of rolling elements 13 are arranged between the inner ring 11 and the outer ring 12. The rolling elements 13 in this embodiment are balls. The rolling bearing 10 in this embodiment is a deep groove ball bearing. The outer peripheral surface of the inner ring 11 has a raceway 11a on which the balls 13 roll. This raceway 11a has a cross section that is approximately concave arc-shaped. The inner peripheral surface of the outer ring 12 has a raceway 12a on which the balls 13 roll. This raceway 12a has a cross section that is approximately concave arc-shaped.

[0023] Figure 2 is a perspective view showing the cage 14 of the rolling bearing 10. As shown in Figures 1 and 2, the cage 14 has a plurality of pockets 15. The plurality of pockets 15 each hold a plurality of balls 13 so that they can roll freely. The plurality of pockets 15 are arranged at intervals in the circumferential direction of the cage 14. When viewed in the radial direction, each pocket 15 has a circular shape. The inner surface of the pocket 15 has a concave curved shape that is a part of a sphere. The radius of the concave curved shape is slightly larger than the radius of the outer peripheral surface of the balls 13 (see also Figure 4).

[0024] The cage 14 of this embodiment is a mating cage that holds the balls 13 from both axial sides. The cage 14 is composed of a pair of annular parts 16 that are joined together in the axial direction. The pair of annular parts 16 have the same shape. The pair of annular parts 16 are connected in an inverted state. Each annular part 16 is made of synthetic resin. Each annular part 16 is integrally molded by injection molding.

[0025] FIG. 3 is a perspective view of the annular component 16. As shown in FIGS. 2 and 3 , each annular component 16 includes an annular body 17 and a plurality of horns 19. The annular body 17 is annular. The annular body 17 is defined as the portion axially outward of a cylindrical or conical surface formed by a first imaginary circle K1 connecting the axially outermost positions of the radially outer openings of each pocket 15 and a second imaginary circle K2 connecting the axially outermost positions of the radially inner openings of each pocket 15. A plurality of hollowed portions 17a are provided at intervals in the circumferential direction. The hollowed portions 17a open on the axially outer end surface of the annular body 17 and are recessed axially inward into the horns 19 (see also FIG. 1 ). The plurality of horns 19 are formed integrally with the annular body 17 at intervals in the circumferential direction of the annular body 17. The plurality of horns 19 protrude from the annular body 17 to one axial side toward the mating annular component 16. Each of the pockets 19 is a portion (excluding the annular body 17) between adjacent pocket forming portions 21 (described later) in the annular part 16.

[0026] The annular part 16 is configured by alternately forming a plurality of pocket forming portions 21 and a plurality of horn forming portions 22 in the circumferential direction. The pocket forming portions 21 are the portions of the annular part 16 where each pocket 15 is formed. The horn forming portions 22 are the portions of the annular part 16 where each horn 19 is formed. The horn forming portions 22 are the portions of the annular body 17 where each horn 19 is joined, and the horns 19 themselves. The horn 19 has a horn main body 20 and a horn protrusion 18. The horn protrusion 18 extends axially inward from the tip end surface 22a of the horn main body 20.

[0027] Fig. 4 is a perspective view showing a portion of the annular component 16. Fig. 5 is a view of a portion of the pair of disassembled annular components 16 viewed from the radially inner side. As shown in Figs. 4 and 5, the axially inner tip surface 22a of each main body 20 is formed flat when viewed in the radial direction. The tip surface 22a of each main body 20 abuts against the tip surface 22a of each main body 20 of the mating annular component 16 (see Fig. 2).

[0028] The horn protrusions 18 are coupled to the tip end surface 22a of each horn body 20. The horn protrusions 18 extend axially toward the mating annular component 16. The horn protrusions 18 are coupled to the radially inner portion of the tip end surface 22a of the horn body 20, and are coupled to a position offset to one circumferential side from the circumferential center C2 of the tip end surface 22a of the horn body 20. The horn protrusions 18 are formed in a substantially quadrangular prism shape. The radially inner surface 18a of each horn protrusion 18 forms part of the inner circumferential surface of the annular component 16 (see Figure 2). The horn protrusions 18 have a horn protrusion body 18c extending axially and a locking projection 18b protruding radially outward from the tip of the horn protrusion body 18c.

[0029] The inner peripheral surface of each horn 19 has a locking groove 22b extending in the axial direction. The locking groove 22b opens at the position of the tip surface 22a of the horn main body 20. The locking groove 22b is provided at a position offset to the opposite side of the horn protrusion 18 with respect to the circumferential center C2 of the tip surface 22a of the horn main body 20. The horn protrusion 18 of the mating annular part 16 is inserted into the locking groove 22b from the tip surface 22a side of the horn main body 20. The horn protrusion 18 of the mating annular part 16 is inserted into the locking groove 22b from the locking projection 18b.

[0030] As shown in FIG. 1 , the locking groove 22b communicates with the hollow portion 17a, which is recessed axially inward from the axially outer end face of the annular body 17. A radial step surface 22c is formed in the axial middle of the locking groove 22b. The locking protrusion 18b is axially locked to the step surface 22c of the locking groove 22b. The two protrusion bodies 18c are housed in the locking groove 22b. By locking the locking protrusion 18b to the step surface 22c, the pair of annular components 16 are prevented from moving apart axially. The pair of annular components 16 are connected.

[0031] As shown in Figure 3, all of the horn forming portions 22 of each annular part 16 have one gate mark 28 (see also Figure 5). The gate mark 28 is a shear mark formed when a gate 46 (described below) of a mold 40 is separated after the annular part 16 is molded using the mold 40 (described below). In this embodiment, the gate mark 28 is located at a position biased toward one circumferential side (the horn protruding portion 18 side) of the inner surface 22d on the radially inner side of each horn forming portion 22. The gate mark 28 is circular.

[0032] As described above, the multiple gate marks 28 are present at intervals in the circumferential direction on the inner peripheral surface of the annular component 16. The pocket forming portions 21 are present between circumferentially adjacent gate marks 28. Note that the gate marks 28 are not shown in Figure 2.

[0033] As shown in Figures 2 and 3, the axially inner end surface 21a of each pocket forming portion 21 is formed in a semicircular shape when viewed in the radial direction. The axially inner end surface 21a of each pocket forming portion 21 is part of a spherical surface with a radius slightly larger than the radius of the balls 13. One pocket 15 is formed by arranging the pocket forming portions 21 of a pair of annular components 16 facing each other in the axial direction. One pocket 15 is part of a spherical surface formed by the two end surfaces 21a. The cage 14 has a plurality of pillars 25 in the circumferential direction. One pillar 25 is formed by connecting the horns 19 of a pair of annular components 16 in the axial direction. Each pocket 15 is formed between pillars 25 adjacent to each other in the circumferential direction of the cage 14.

[0034] Figure 6 is a cross-sectional view taken along the line I-I in Figure 2. As shown in Figures 3 and 6, a circular through-hole 23 opens into the bottom of each pocket forming portion 21, located at the outermost position in the axial direction of the pocket 15. The through-hole 23 passes through the annular body 17 in the axial direction. The through-hole 23 opens into the axially outer end face of the annular body 17. By providing the through-hole 23, the axial thickness t1 of the bottom of the pocket forming portion 21 can be made thinner than the thickness t11 of the pocket bottom of a conventional annular body (see Figure 11). As a result, the axial width dimension W1 of the rolling bearing 10 (see Figure 1) is smaller than the width dimension W11 of a conventional rolling bearing (see Figure 11).

[0035] Figure 7 is a front view of the annular part 16 as viewed from the axially inner side. As shown in Figure 7, the annular part 16 has a weld (weld line) 24 between circumferentially adjacent gate marks 28. The weld 24 is generated when the annular part 16 is molded using a mold 40 (described below). The weld 24 is a thin line that occurs at a portion where flows of molten resin join and fuse together inside the mold 40 (described below).

[0036] The welds 24 are formed between adjacent gate marks 28 only in region R1 on one circumferential side of the through hole 23 or only in region R2 on the other circumferential side. Regions R1 and R2 include the horn forming portion 22 and the pocket forming portion 21 excluding region R3. Region R3 is a region radially outward and radially inward of the through hole 23 within the range in which the through hole 23 is located in the circumferential direction of the horn forming portion 22. The welds 24 are not formed in region R3, which is a stress concentration portion of each pocket forming portion 21. In this embodiment, the welds 24 are formed in the pocket forming portion 21 and / or the horn forming portion 22 within region R1 or region R2. The welds 24 are formed throughout the entire thickness of the pocket forming portion 21 in the axial direction (perpendicular to the plane of the paper in FIG. 7 ).

[0037] The weld 24 has a first weld portion 24a and a second weld portion 24b. When viewed in the axial direction (front view in FIG. 7 ), the first weld portion 24a extends radially and axially over the entire region R1 or region R2. When viewed in the axial direction, the second weld portion 24b extends circumferentially and axially from a radially intermediate position (here, the center position) of the first weld portion 24a to the through hole 23. Note that the weld 24 is not shown in FIGS. 2 and 3 .

[0038] [Mold] Figure 8 is a perspective view showing a mold 40 that molds the annular part 16 by injection molding. Figure 9 is a plan view of the mold 40. As shown in Figures 8 and 9, the mold 40 includes a first mold part 41 and a second mold part 42 that are divided into two parts in the axial direction of the annular part 16. The first mold part 41 is a fixed mold. The second mold part 42 is a movable mold that is movable in the axial direction relative to the first mold part 41. In Figure 8, for convenience, the first mold part 41 and the second mold part 42 are drawn with imaginary lines (two-dot chain lines).

[0039] The mold 40 further includes a cavity 43, a sprue 44, a plurality of runners 45, and a plurality of gates 46. The cavity 43 is formed between the first mold portion 41 and the second mold portion 42. The cavity 43 is a space filled with molten resin. The cavity 43 is formed in an annular shape corresponding to the shape of the annular part 16. As a result, the cavity 43 is formed with a plurality of pocket molding spaces 43a in which the pocket forming portions 21 are molded and a plurality of molding spaces 43b in which the molding portions 22 are molded, which are alternately formed in the circumferential direction. Although not shown, cylindrical molding posts for molding the through holes 23 are provided in the first mold portion 41 or the second mold portion 42 at positions in the pocket molding spaces 43a corresponding to the respective through holes 23.

[0040] The sprue 44, the plurality of runners 45, and the plurality of gates 46 are passages for supplying molten resin to the cavity 43. The sprue 44 is a passage formed in the second mold portion 42. The sprue 44 extends in the axial direction at the center of the annular cavity 43. The sprue 44 in this embodiment is formed to have a circular cross section.

[0041] The runners 45 are passages formed between the first mold part 41 and the second mold part 42. There is one runner 45 for each horn forming part 22. The multiple runners 45 extend radially outward from the tip of the sprue 44. In this embodiment, each runner 45 is formed to have a square cross section.

[0042] The gates 46 are connected to the radially outer ends of the runners 45. Each gate 46 extends radially outward from the radially outer end of the runner 45 and toward one axial side (the upper side in FIG. 8 ). In this embodiment, each gate 46 has a circular cross section and is formed so that the diameter gradually decreases toward the tip.

[0043] The tips of the multiple gates 46 are connected to each other at intervals in the circumferential direction of the cavity 43. Specifically, the tip of each gate 46 is connected to each molding space 43b at a position biased to one circumferential side (the horn protruding portion 18 side) of a location corresponding to the inner surface 22d of the horn forming portion 22. In this way, each gate 46 is connected to all of the molding spaces 43b.

[0044] The method for molding the annular part 16 is as follows. Molten resin supplied to the sprue 44 of the mold 40 passes through each runner 45 and each gate 46 in order, and flows into each molding space 43b of the cavity 43. The molten resin that flows into each molding space 43b flows into the adjacent pocket molding space 43a. The molten resin then fills the entire cavity 43. The molten resin solidifies, and the solidified resin is removed from the mold 40 as the annular part 16.

[0045] As shown in FIG. 9 , the gates 46 in this embodiment include a plurality of first gates 46A, a plurality of second gates 46B, and one third gate 46C. The diameter of the first gate 46A at the position where the tip thereof opens into the cavity 43, the diameter of the second gate 46B at the position where the tip thereof opens into the cavity 43, and the diameter of the third gate 46C at the position where the tip thereof opens into the cavity 43 are all different. Four first gates 46A and four second gates 46B are provided. One third gate 46C is provided. The diameter of the tip of the first gate 46A is larger than the diameter of the tip of the second gate 46B. The diameter of the tip of the second gate 46B is larger than the diameter of the tip of the third gate 46C.

[0046] The first gate 46A and the second gate 46B are arranged adjacent to each other in the circumferential direction. The third gate 46C is arranged between the first gate 46A and the second gate 46B at a predetermined circumferential location (approximately the 10 o'clock position in FIG. 9 ). As a result, the tip diameters of two circumferentially adjacent gates 46 are different from each other. Therefore, the volumetric flow rate of molten resin flowing from one of the adjacent gates 46, which has a larger tip diameter, into the one molding space 43b is greater than the volumetric flow rate of molten resin flowing from the other gate 46, which has a smaller tip diameter, into the one molding space 43b.

[0047] The volumetric flow rate of the molten resin flowing through the first gate 46A is greater than the volumetric flow rate of the molten resin flowing through the second gate 46B. The volumetric flow rate of the molten resin flowing through the first gate 46A is greater than the volumetric flow rate of the molten resin flowing through the third gate 46C. The volumetric flow rate of the molten resin flowing through the second gate 46B is greater than the volumetric flow rate of the molten resin flowing through the third gate 46C.

[0048] The molten resin flowing through the first gate 46A flows from the first gate 46A to one circumferential side of the cavity 43 and the other circumferential side of the cavity 43. The molten resin flowing through the second gate 46B flows from the second gate 46B to one circumferential side of the cavity 43 and the other circumferential side of the cavity 43. The molten resin flowing through the third gate 46C flows from the third gate 46C to one circumferential side of the cavity 43 and the other circumferential side of the cavity 43. With respect to adjacent first gates 46A and second gates 46B, the volume of molten resin flowing from the first gate 46A to one circumferential side of the cavity 43 and the volume of molten resin flowing from the second gate 46B to the other circumferential side of the cavity 43 can be made different. With respect to adjacent first gate 46A and second gate 46B, the volume of molten resin flowing from the first gate 46A to the other circumferential side of cavity 43 can be made different from the volume of molten resin flowing from the second gate 46B to one circumferential side of cavity 43. With respect to adjacent first gate 46A and third gate 46C, the volume of molten resin flowing from the first gate 46A to one circumferential side of cavity 43 can be made different from the volume of molten resin flowing from the third gate 46C to the other circumferential side of cavity 43. With respect to adjacent second gate 46B and third gate 46C, the volume of molten resin flowing from the second gate 46B to the other circumferential side of cavity 43 can be made different from the volume of molten resin flowing from the third gate 46C to one circumferential side of cavity 43. By combining the diameter and arrangement of the tip of the first gate 46A, the diameter and arrangement of the tip of the second gate 46B, and the diameter and arrangement of the tip of the third gate 46C, it is possible to make the molten resin merge at a position other than the circumferential center between adjacent gates 46.

[0049] 7, in the annular part 16 after molding, welds 24 are formed in the pocket forming portions 21 in the region R1 on one circumferential side of each through hole 23 or in the region R2 on the other circumferential side. The second weld portion 24b of the weld 24 is a thin line generated at a portion where the flows of molten resin that have passed from one of the molding spaces 43b to the radially outer side and the radially inner side of the through hole 23 join and fuse together. The first weld portion 24a of the weld 24 is a thin line generated at a portion where the flows of molten resin that have passed from the radially outer side and the radially inner side of the through hole 23 join and fuse together with the flows of molten resin from the other molding space 43b.

[0050] [Effects of the embodiment] As described above, the cage 14 of this embodiment has through holes formed in the bottoms of the pockets 15 in the pocket forming portions 21, which allows the axial thickness t1 at the bottoms of the pocket forming portions 21 to be reduced. As a result, the rolling bearing 10 using the cage 14 of this embodiment can have a reduced axial width dimension W1 of the rolling bearing 10. Furthermore, the welds 24 are formed only in the region R1 on one circumferential side of the through hole 23 or only in the region R2 on the other circumferential side, between circumferentially adjacent gate marks 28. As a result, the cage 14 of this embodiment can prevent the formation of welds, which have the weakest strength, in the region R3, which becomes a stress concentration portion of the pocket forming portions 21 during use of the rolling bearing 10. Therefore, the cage 14 of this embodiment has the strength of the cage 14 despite having the through holes 23 in the pocket forming portions 21.

[0051] Furthermore, the weld 24 has a first weld portion 24a that extends radially in the entire direction as viewed in the axial direction, and a second weld portion 24b that extends circumferentially from a radially intermediate position of the first weld portion 24a to the through hole 23 as viewed in the axial direction. Therefore, the strength of the cage 14 of this embodiment can be further increased compared to when only the second weld portion 24b is formed to extend circumferentially in the entire region R1.

[0052] Furthermore, all of the five forming portions 22 of the cage 14 of this embodiment each have a gate mark 28. That is, when the cage 14 of this embodiment is molded using a mold 40, molten resin flows into the mold 40 from gates 46 corresponding to all of the five forming portions 22. Therefore, by controlling the volume of molten resin flowing from each gate 46, the first weld 24a and the second weld 24b can be easily formed in region R1 or region R2, rather than region R3.

[0053] Furthermore, the cage 14 of this embodiment is configured by axially connecting a pair of annular parts 16. Therefore, the cage 14 of this embodiment can further increase the strength of the cage 14 compared to a crown cage configured by only a single annular part.

[0054] Furthermore, two gates 46 adjacent to each other in the circumferential direction of the mold 40 have different diameters at their tips. Therefore, the volume of molten resin flowing from one of the two circumferentially adjacent gates 46 into the cavity 43 on one side in the circumferential direction is greater than the volume of molten resin flowing from the other gate 46 into the cavity 43 on the other side in the circumferential direction. As a result, by controlling the volume of molten resin flowing from each gate 46, the first weld 24a and the second weld 24b can be more easily formed in region R1 or region R2 rather than region R3.

[0055] [Others] The embodiments disclosed above are illustrative in all respects and are not limiting. For example, the rolling bearing 10 may be an angular contact ball bearing or the like in addition to a deep groove ball bearing. The cage 14 may be a crown cage or a horn-shaped cage in addition to a mating cage. The weld 24 may be formed in the pocket forming portion 21 or the horn-shaped portion 22 in region R1 or region R2.

[0056] The gates 46 of the mold 40 are connected to the locations in each molding space 43b that correspond to the inner surfaces 22d of the horn forming portions 22, but this is not limited thereto. For example, the gates 46 may be connected to the locations in each molding space 43b that correspond to the horn protrusions 18. In this case, it goes without saying that gate marks 28 will be formed on the horn protrusions 18 in the cage 14 after molding.

[0057] The number of gates 46 is not limited to that of the present embodiment. When the number of gates 46 is even, these gates 46 may be configured as two types of gates with different tip diameters. Two gates 46 adjacent to each other in the circumferential direction of the mold 40 have different tip diameters to differentiate the volumetric flow rates of the molten resin, but this is not a limitation. For example, two gates 46 adjacent to each other in the circumferential direction may be connected to independent flow paths, and the inflow pressure of the molten resin to each gate 46 may be differentiated.

[0058] 10 Rolling bearing 11 Inner ring 12 Outer ring 13 Ball (rolling element) 14 Cage 15 Pocket 16 Annular part 17 Annular body 18 Protrusions 19 20 Main body 21 Pocket forming portion 22 Forming portion 23 Through hole 24 Weld 24a First weld portion 24b Second weld portion 25 Pillar 28 Gate mark 40 Mold 43 Cavity 43a Pocket molding space 43b Molding space 45 Runner 46 Gate R1 Region R2 Region R3 Region

Claims

1. A synthetic resin cage comprising an annular body and a plurality of tines protruding from the annular body to one side in an axial direction at intervals in a circumferential direction of the annular body, wherein a plurality of pockets for holding a plurality of rolling elements of a rolling bearing in a freely rollable manner are formed between adjacent tines in the circumferential direction, A plurality of gate marks formed at intervals in the circumferential direction; a weld formed between the gate marks adjacent to each other in the circumferential direction; a plurality of pocket forming portions that are respectively disposed between the gate marks and in which the pockets are formed; Each of the pocket forming portions has a through hole formed in a bottom portion of the pocket so as to penetrate therethrough in the axial direction, The weld is formed between the gate marks only in a region on one circumferential side of the through hole or only in a region on the other circumferential side of the through hole, The weld is A first weld portion extending radially in the axial direction; a second weld portion extending circumferentially from a radial midpoint of the first weld portion to the through hole when viewed in the axial direction.

2. The method further includes forming a plurality of nibs on which the nibs are formed, The cage according to claim 1 , wherein each of the horn formation portions has one gate mark formed therein.

3. A pair of annular components including the annular body and the plurality of tines are connected in an axial direction, 3. The cage according to claim 1, further comprising a pillar formed by connecting the prongs of each of the pair of annular components to each other.

4. A rolling bearing comprising: an inner ring; an outer ring; a plurality of rolling elements disposed between the inner ring and the outer ring; and the cage according to claim 1 or 2.

5. 3. A method for molding the cage according to claim 2, using a mold including a plurality of runners, a plurality of gates connected to the runners, and an annular cavity to which the plurality of gates are connected at intervals in a circumferential direction, comprising: In the cavity, a plurality of pocket forming spaces in which the pocket forming portions are formed and a plurality of molding spaces in which the respective forming portions are formed are alternately formed in a circumferential direction, Each of the molding spaces is connected to one of the gates, A method for molding a retainer, wherein when molten resin is poured from each runner through the gate into the cavity, the volume of the molten resin poured from one of two circumferentially adjacent gates is made greater than the volume of the molten resin poured from the other gate.