Cage, rolling bearing, and method for forming a cage

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

Technical Field

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

Background Art

[0002] For example, in a rolling bearing used in a drive unit such as an automobile transmission, as the drive unit is miniaturized, it is required to reduce the axial width dimension of the rolling bearing. By reducing the width dimension of the rolling bearing, when a cage that holds rolling elements protrudes axially beyond each side surface of the outer ring and the inner ring, during the manufacturing process, packaging, or transportation of the rolling bearing, etc., the cage may interfere with other members other than the rolling bearing, and the cage may be damaged. Therefore, when reducing the width dimension of the rolling bearing, it is necessary to prevent the cage from protruding axially with respect to each side surface of the outer ring and the inner ring. Thus, it is conceivable to use a crowned cage made of synthetic resin (for example, see Patent Document 1) to reduce the width dimension of the rolling bearing.

[0003] FIG. 10 is a perspective view showing a part of a conventional synthetic resin crowned cage 90. FIG. 11 is a cross-sectional view of a rolling bearing 80 provided with the crowned cage 90. As shown in FIGS. 10 and 11, the crowned cage 90 has an annular body 91 and a plurality of projections 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 projections 92 project axially from the annular body 91 to the other axial side. A pocket 93 is a space surrounded by two adjacent projections 92 and the annular body 91 between the two projections 92. The rolling element 83 is accommodated in the pocket 93. This crowned cage 90 has a reduced axial thickness t11 at the bottom 91a of the pocket 93 of the annular body 91. Because the thickness t11 is small, the axial width dimension W11 of the rolling bearing 80 is smaller than that of a rolling bearing of a standard dimension system.

Prior Art Documents

Patent Documents

[0004] [Patent Document 1] Japanese Patent Publication No. 2019-127974 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] As described above, by reducing the thickness t11 of the bottom 91a of the annular body 91 of the crown-shaped cage 90, the axial width dimension W11 of the rolling bearing can be reduced. On the other hand, because the thickness t11 is thin, the strength of the crown-shaped cage 90 is lower than that of a rolling bearing with standard dimensions. For this reason, there is a limit to how much the thickness of the bottom 91a of the annular body 91 can be reduced.

[0006] The present invention aims to minimize the axial width dimension of the rolling bearing while ensuring the strength of the cage. [Means for solving the problem]

[0007] The present invention provides a retainer made of synthetic resin comprising an annular body and a plurality of horns projecting from the annular body in one axial direction at intervals in the circumferential direction, wherein a plurality of pockets for rotatably holding a plurality of rolling elements of a rolling bearing are formed between adjacent horns in the circumferential direction, and further comprising a plurality of gate marks formed at intervals in the circumferential direction, welds formed between adjacent gate marks in the circumferential direction, and a plurality of pocket forming portions arranged between the gate marks, wherein each pocket forming portion has a through hole formed in the axial direction at the bottom of the pocket, and the welds are formed between the gate marks only in a region on one circumferential direction side or only in a region on the other circumferential direction side of the through hole.

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

[0009] The present invention provides a method for molding a retainer using a mold comprising 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 intervals in the circumferential direction, wherein the cavity has a plurality of pocket molding spaces in which each of the pocket forming portions is formed, and a plurality of molding spaces in which each of the forming portions is formed, alternately formed in the circumferential direction, and one of the molding spaces is connected to each of the molding spaces, and when molten resin is poured from each of the runners through the gates into the cavity, 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. [Effects of the Invention]

[0010] According to the present invention, the axial width dimension of the rolling bearing can be reduced as much as possible while ensuring the strength of the cage. [Brief explanation of the drawing]

[0011] [Figure 1] This is a cross-sectional view of a rolling bearing according to an embodiment of the present invention. [Figure 2] This is a perspective view showing the cage of a rolling bearing. [Figure 3] This is a perspective view showing the annular component of the retainer. [Figure 4] This is a cross-sectional view taken along arrow II in Figure 2. [Figure 5] This is a front view of the annular component, seen from the axial direction and from the inside. [Figure 6] This is a perspective view showing a portion of a ring-shaped component. [Figure 7] This is a view of a portion of a disassembled pair of annular components, seen from the radially inner side. [Figure 8] This is a perspective view showing a mold used to form annular parts by injection molding. [Figure 9] This is a plan view of the mold. [Figure 10] This is a perspective view showing a portion of a conventional crown-shaped retainer made of synthetic resin. [Figure 11] This is a cross-sectional view of a conventional rolling bearing with a crown-shaped cage. [Modes for carrying out the invention]

[0012] First, the details of the embodiment will be listed and explained. <Overview of Embodiments> (1) The cage of the embodiment comprises an annular body and a plurality of horns projecting from the annular body in one axial direction at intervals in the circumferential direction, wherein a plurality of pockets for holding a plurality of rolling elements of a rolling bearing are formed between adjacent horns in the circumferential direction, and comprises a plurality of gate marks formed at intervals in the circumferential direction, welds formed between adjacent gate marks in the circumferential direction, and a plurality of pocket forming portions arranged between the gate marks and for forming each of the pockets, wherein each pocket forming portion has a through hole formed in the axial direction at the bottom of the pocket, and the welds are formed between the gate marks only in a region on one circumferential direction side or only in a region on the other circumferential direction side of the through hole.

[0013] According to the above-described cage, since a through hole is formed at the bottom of the pocket in the pocket forming section, the axial thickness at the bottom of the pocket forming section can be made as thin as possible. This makes it possible to reduce the axial width dimension of the rolling bearing. In addition, between adjacent gate marks in the circumferential direction, weld is formed only in the region on one or the other circumferential side of the through hole. This makes it possible to suppress the formation of the weakest weld in the regions radially outside and radially inside the through hole in the pocket forming section (stress concentration areas) during use of the rolling bearing. Therefore, the strength of the cage can be ensured even if a through hole is formed in the pocket forming section.

[0014] (2) In the cage according to (1) above, it is preferable that the weld has a first weld portion extending in the entire radial direction in an axial view, and a second weld portion extending circumferentially from an arbitrary position in the radial direction of the first weld portion to the through hole in the axial view. In this case, the strength of the cage can be further increased as compared with the case where only the second weld portion extends over the entire circumferential direction in a region on one side or the other side in the circumferential direction with respect to the through hole.

[0015] (3) The cage according to (2) above preferably further includes a plurality of formation portions where each of the above is formed, and one of the above gate marks is formed in each of all the formation portions. In this case, when the cage is molded by a mold, molten resin flows into the mold from a gate corresponding to each of all the formation portions. Therefore, by controlling the volume of the molten resin flowing in from each gate, the first weld portion and the second weld portion can be easily formed in a region on one side or the other side in the circumferential direction with respect to the through hole.

[0016] (4) The cage according to any one of (1) to (3) above is preferably configured by axially connecting a pair of annular components including the annular body and the plurality of above. In this case, since the cage is configured by a pair of annular components, the strength of the cage can be further increased as compared with the case where the cage is configured by only a single annular component and has columns formed by connecting the respective ones of the pair of annular components.

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

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

[0019] (7) A method for molding a retainer according to an embodiment, comprising 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 intervals in the circumferential direction, wherein the cavity has a plurality of pocket molding spaces in which each of the pocket forming portions is formed, and a plurality of molding spaces in which each of the forming portions is formed, alternately formed in the circumferential direction, and one of the molding spaces is connected to each of the molding spaces, and when molten resin is poured from each of the runners through the gates into the cavity, the volume of molten resin poured from one of the two circumferentially adjacent gates is made greater than the volume of molten resin poured from the other gate.

[0020] According to the above method for molding the retainer, in the pocket molding space formed between one molding space to which one gate is connected and the other molding space to which the other gate is connected, the volume of molten resin poured from one molding space is greater than the volume of molten resin poured from the other molding space. Therefore, the molten resin flowing from one molding space and the molten resin flowing from the other molding space are more likely to merge on one or the other side of the through hole in the pocket forming section in the circumferential direction. As a result, the first weld portion and the second weld portion can be formed even more easily in the region on one or the other side of the through hole in the circumferential direction.

[0021] <Details of the embodiment> Preferred embodiments will be described below with reference to the drawings. [Rolling bearings] Figure 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 of the rolling bearing 10 closer to the axial center C1 may be referred to as the axial inner side, and the side further 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 positioned radially outward from the inner ring 11. Multiple rolling elements 13 are positioned between the inner ring 11 and the outer ring 12. In this embodiment, the rolling elements 13 are balls. The rolling bearing 10 in this embodiment is a deep groove ball bearing. The outer circumferential surface of the inner ring 11 has a raceway 11a on which the balls 13 roll. This raceway 11a has a substantially concave arc cross-section. The inner circumferential surface of the outer ring 12 has a raceway 12a on which the balls 13 roll. This raceway 12a has a substantially concave arc cross-section.

[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. Each of the multiple pockets 15 holds a plurality of balls 13 so that they can roll freely. The multiple pockets 15 are arranged on the cage 14 at circumferential intervals. In radial view, each pocket 15 is circular in shape. The inner surface of the pocket 15 has a concave curved surface shape which is part of a sphere. The radius of the concave curved surface shape is slightly larger than the radius of the outer surface of the ball 13 (see also Figure 4).

[0024] The retainer 14 of this embodiment is a combined retainer that holds the ball 13 from both axial sides. The retainer 14 is composed of a pair of annular parts 16 joined in the axial direction. The pair of annular parts 16 are identical in 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] Figure 3 is a perspective view showing an annular component 16. As shown in Figures 2 and 3, each annular component 16 comprises an annular body 17 and a plurality of horns 19. The annular body 17 is circular. The annular body 17 is defined as the portion axially outside the cylindrical or conical surface connecting a first virtual circle K1, which connects the outermost axial positions of the radially outward openings of each pocket 15, and a second virtual circle K2, which connects the outermost axial positions of the radially inward openings of each pocket 15. The plurality of back cutouts 17a are provided at intervals in the circumferential direction. The plurality of back cutouts 17a open on the axially outward end face of the annular body 17 and are recessed into the horns 19 axially inward (see also Figure 1). The plurality of horns 19 are formed integrally with the annular body 17 at intervals in the circumferential direction. The plurality of horns 19 project from the annular body 17 toward the mating annular component 16 in one axial direction. Each of the 19s is a portion of the annular component 16 between adjacent pocket forming portions 21 (described later) (excluding the annular body 17).

[0026] The annular component 16 is constructed 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 parts in the annular component 16 where each pocket 15 is formed. The horn-forming portions 22 are the parts in the annular component 16 where each horn 19 is formed. The horn-forming portions 22 are the parts in the annular body 17 where each horn 19 is joined, and the horn 19 itself. Each horn 19 has a horn body 20 and a horn projection 18. The horn projection 18 extends axially inward from the tip surface 22a of the horn body 20.

[0027] Figure 4 is a perspective view showing a portion of the annular component 16. Figure 5 is a view of a portion of the disassembled pair of annular components 16 from the radially inner side. As shown in Figures 4 and 5, the axially inner end surface 22a of each body 20 is formed to be flat in radial view. The end surface 22a of each body 20 abuts against the end surface 22a of each body 20 in the mating annular component 16 (see Figure 2).

[0028] Each projection 18 connects to the tip surface 22a of each body 20. Each projection 18 extends axially toward the mating annular component 16. Each projection 18 connects to the radially inner portion of the tip surface 22a of the body 20, and is positioned off-center to one side in the circumferential direction from the circumferential center C2 of the tip surface 22a of the body 20. Each projection 18 is formed in a substantially rectangular prism shape. The radially inner surface 18a of each projection 18 constitutes a part of the inner circumferential surface of the annular component 16 (see Figure 2). Each projection 18 has a projection body 18c that extends axially and a locking projection 18b that protrudes radially outward from the tip of the projection body 18c.

[0029] Each of the 19 horns has an axially extending locking groove 22b on its inner circumferential surface. The locking groove 22b opens at the tip surface 22a of the horn body 20. The locking groove 22b is positioned offset from the horn projection 18 with respect to the circumferential center C2 of the tip surface 22a of the horn body 20. The horn projection 18 of the mating annular component 16 is inserted into the locking groove 22b from the tip surface 22a side of the horn body 20. The horn projection 18 of the mating annular component 16 is inserted into the locking groove 22b from the locking projection 18b.

[0030] As shown in Figure 1, the locking groove 22b communicates with a recessed portion 17a that extends axially inward from the axially outer end face of the annular body 17. The radially stepped surface 22c is formed in the axial middle of the locking groove 22b. The locking projection 18b is axially locked to the stepped surface 22c of the locking groove 22b. The two protruding body parts 18c are housed in the locking groove 22b. Because the locking projection 18b is locked to the stepped surface 22c, the pair of annular parts 16 are not separated from each other in the axial direction. The pair of annular parts 16 are connected.

[0031] As shown in Figure 3, each of the formed portions 22 of each annular part 16 has one gate mark 28 (see also Figure 5). The gate mark 28 is a shear mark formed when the gate 46 (described later) of the mold 40 (described later) is cut off after the annular part 16 has been formed by the mold 40 (described later). In this embodiment, the gate mark 28 is located off-center on one side in the circumferential direction (towards the protruding portion 18) of the radially inward inner surface 22d of each formed portion 22. The gate mark 28 is circular.

[0032] As described above, multiple gate marks 28 exist on the inner circumferential surface of the annular part 16, spaced apart in the circumferential direction. The pocket forming portion 21 is located between adjacent gate marks 28 in the circumferential direction. Note that Figure 2 omits the illustration of the gate marks 28.

[0033] As shown in Figures 2 and 3, the axially inner end face 21a of each pocket forming portion 21 is formed in a semicircular shape when viewed radially. The axially inner end face 21a of each pocket forming portion 21 is part of a sphere having a radius slightly larger than the radius of the ball 13. One pocket 15 is formed by axially oriented pocket forming portions 21 of a pair of annular components 16 facing each other. One pocket 15 is part of a sphere formed by two end faces 21a. The retainer 14 is provided with a plurality of columns 25 in the circumferential direction. One column 25 is formed by axially oriented connections between the horns 19 of a pair of annular components 16. Each pocket 15 is formed between adjacent columns 25 in the circumferential direction of the retainer 14.

[0034] Figure 6 is a cross-sectional view taken along arrow II in Figure 2. As shown in Figures 3 and 6, a circular through-hole 23 opens at the bottom of the pocket 15 located on the outermost axial side in each pocket forming section 21. The through-hole 23 penetrates the annular body 17 in the axial direction. The through-hole 23 opens at the axially outer end face of the annular body 17. By providing the through-hole 23, the axial thickness t1 at the bottom of the pocket forming section 21 can be made thinner than the thickness t11 of the pocket bottom in 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 seen from the axial inner side. As shown in Figure 7, the annular part 16 has welds (weld lines) 24 between adjacent gate marks 28 in the circumferential direction. The welds 24 are generated when the annular part 16 is molded using a mold 40 (described later). The welds 24 are thin lines that occur in the parts where the flow of molten resin merges and fuses within the mold 40, which will be described later.

[0036] The weld 24 is formed between adjacent gate marks 28, but only in region R1 on one side in the circumferential direction of the through hole 23, or only in region R2 on the other side in the circumferential direction. Regions R1 and R2 include the two forming parts 22 and the pocket forming part 21 excluding region R3. Region R3 is the region radially outside and radially inside the through hole 23 in the range where the through hole 23 is located in the circumferential direction of the two forming parts 22. The weld 24 is not formed in region R3, which is a stress concentration area of ​​each pocket forming part 21. In this embodiment, the weld 24 is formed in the pocket forming part 21 and / or the two forming parts 22 within region R1 or region R2. The weld 24 is formed over the entire thickness of the pocket forming part 21 in the axial direction (perpendicular to the plane of the paper in Figure 7).

[0037] The weld 24 has a first weld portion 24a and a second weld portion 24b. The first weld portion 24a extends radially and axially across the entire region R1 or region R2 in an axial view (front view in Figure 7). The second weld portion 24b extends circumferentially and axially across the entire region from an intermediate radial position (in this case, the central position) in the first weld portion 24a to the through hole 23 in an axial view. Note that Figures 2 and 3 omit the illustration of the weld 24.

[0038] [Mold] Figure 8 is a perspective view showing a mold 40 for molding an 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 comprises a first mold section 41 and a second mold section 42, which are divided in the axial direction of the annular part 16. The first mold section 41 is a fixed mold. The second mold section 42 is a movable mold that can move axially relative to the first mold section 41. In Figure 8, for convenience, the first mold section 41 and the second mold section 42 are depicted with dashed lines (two-dot lines).

[0039] The mold 40 further comprises 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 section 41 and the second mold section 42. The cavity 43 is a space into which molten resin is filled. The cavity 43 is formed in an annular shape corresponding to the shape of the annular part 16. As a result, the cavity 43 alternately has a plurality of pocket molding spaces 43a in which each pocket forming section 21 is molded, and a plurality of molding spaces 43b in which each forming section 22 is molded. Although not shown, cylindrical molding columns for forming through holes 23 are provided in the first mold section 41 or the second mold section 42 at positions corresponding to each through hole 23 in the pocket molding space 43a.

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

[0041] The runner 45 is a passage formed between the first mold section 41 and the second mold section 42. There is one runner 45 for each forming section 22. Multiple runners 45 extend radially outward from the tip of the sprue 44. In this embodiment, each runner 45 is formed with a square cross-section.

[0042] Multiple gates 46 are connected to the radially outer end of each runner 45. Each gate 46 extends radially outward and axially in one direction (upper side in Figure 8) from the radially outer end of each runner 45. In this embodiment, each gate 46 is formed with a circular cross-section, and its diameter gradually decreases towards the tip.

[0043] The tips of the multiple gates 46 are connected to the cavity 43 at intervals in the circumferential direction. Specifically, the tip of each gate 46 is connected in each molding space 43b at a position biased toward one side in the circumferential direction (towards the protruding portion 18) of the location corresponding to the inner surface 22d of the two formed portions 22. As a result, each gate 46 is connected to all of the molding spaces 43b.

[0044] The molding method for 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 sequence and flows into each molding space 43b of the cavity 43. The molten resin that has flowed 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 Figure 9, the plurality of gates 46 in this embodiment include a plurality of first gates 46A, a plurality of second gates 46B, and one third gate 46C. The diameters of the positions where the tips of the first gates 46A open into the cavity 43, the diameters of the positions where the tips of the second gates 46B open into the cavity 43, and the diameters of the positions where the tips of the third gates 46C open into the cavity 43 are different from each other. There are four first gates 46A and four second gates 46B. There is one third gate 46C. 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 positioned between the first gate 46A and the second gate 46B at a predetermined location in the circumferential direction (approximately the 10 o'clock position in Figure 9). As a result, the diameters of the tips of two adjacent gates 46 in the circumferential direction are different. Therefore, the volumetric flow rate of molten resin flowing from one gate 46 with a larger tip diameter into the molding space 43b is greater than the volumetric flow rate of molten resin flowing from the other gate 46 with a smaller tip diameter into the molding space 43b.

[0047] The volumetric flow rate of molten resin flowing through the first gate 46A is greater than the volumetric flow rate of molten resin flowing through the second gate 46B. The volumetric flow rate of molten resin flowing through the first gate 46A is greater than the volumetric flow rate of molten resin flowing through the third gate 46C. The volumetric flow rate of molten resin flowing through the second gate 46B is greater than the volumetric flow rate of 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 side of the cavity 43 in the circumferential direction and to the other side of the cavity 43 in the circumferential direction. The molten resin flowing through the second gate 46B flows from the second gate 46B to one side of the cavity 43 in the circumferential direction and to the other side of the cavity 43 in the circumferential direction. The molten resin flowing through the third gate 46C flows from the third gate 46C to one side of the cavity 43 in the circumferential direction and to the other side of the cavity 43 in the circumferential direction. With respect to adjacent first gates 46A and second gates 46B, the volume of molten resin flowing from the first gate 46A to one side of the cavity 43 in the circumferential direction and the volume of molten resin flowing from the second gate 46B to the other side of the cavity 43 in the circumferential direction can be made to be different. With respect to adjacent first gates 46A and second gates 46B, the volume of molten resin flowing from the first gate 46A to the other side of the cavity 43 in the circumferential direction can be made different from the volume of molten resin flowing from the second gate 46B to one side of the cavity 43 in the circumferential direction. With respect to adjacent first gates 46A and third gates 46C, the volume of molten resin flowing from the first gate 46A to one side of the cavity 43 in the circumferential direction can be made different from the volume of molten resin flowing from the third gate 46C to the other side of the cavity 43 in the circumferential direction. With respect to adjacent second gates 46B and third gates 46C, the volume of molten resin flowing from the second gate 46B to the other side of the cavity 43 in the circumferential direction can be made different from the volume of molten resin flowing from the third gate 46C to one side of the cavity 43 in the circumferential direction. 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 merge molten resins at a position that is not the circumferential center between adjacent gates 46.

[0049] As described above, as shown in Figure 7, after molding, welds 24 are formed in the pocket forming portions 21 of the annular part 16 in the region R1 on one side in the circumferential direction or the region R2 on the other side in the circumferential direction of each through hole 23. The second weld portion 24b of the weld 24 is a thin line that occurs in the portion where the flow of molten resin that has passed from one of the molding spaces 43b through the radially outer and radially inner sides of the through hole 23, respectively, merges and fuses. The first weld portion 24a of the weld 24 is a thin line that occurs in the portion where the flow of molten resin that has passed from the radially outer and radially inner sides of the through hole 23, respectively, merges and fuses with the flow of molten resin from the other molding space 43b.

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

[0051] Furthermore, the weld 24 has a first weld portion 24a that extends radially over the entire length in an axial view, and a second weld portion 24b that extends circumferentially from an intermediate radial position of the first weld portion 24a to the through hole 23 in an axial view. Therefore, the strength of the retainer 14 in this embodiment can be further increased compared to the case where only the second weld portion 24b is formed extending over the entire circumferential length of region R1.

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

[0053] Furthermore, the retainer 14 of this embodiment is constructed by connecting a pair of annular parts 16 in the axial direction. Therefore, the strength of the retainer 14 of this embodiment can be further increased compared to a crown-shaped retainer which is composed of only a single annular part.

[0054] Furthermore, the two gates 46 adjacent to each other in the circumferential direction of the mold 40 have different tip diameters. As a result, the volume of molten resin flowing from one gate 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. Consequently, by controlling the volume of molten resin flowing from each gate 46, the first weld portion 24a and the second weld portion 24b can be formed more easily in region R1 or region R2, rather than in region R3.

[0055] [others] The embodiments disclosed above are illustrative and not restrictive in all respects. 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 cage, in addition to a mating cage. The weld 24 may be formed in the pocket forming portion 21 or in the horn forming portion 22 in region R1 or region R2.

[0056] The gate 46 of the mold 40 is connected to a location corresponding to the inner surface 22d of one of the forming parts 22 in each molding space 43b, but is not limited to this. For example, the gate 46 may be connected to a location corresponding to one of the protrusions 18 in each molding space 43b. In this case, it goes without saying that a gate mark 28 will be formed on the protrusions 18 in the retainer 14 after molding.

[0057] The number of gates 46 is not limited to this embodiment. If there is an even number of gates 46, these gates 46 may consist of 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 cause different volumetric flow rates of molten resin, but this is not limited to this. 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 molten resin into each gate 46 may be made different from each other. [Explanation of Symbols]

[0058] 10 Rolling bearings 11 Inner circle 12 Outer ring 13 Balls (rolling bodies) 14 Cage 15 pockets 16 ring-shaped parts 17 Ring-shaped bodies 18 protrusions 19 20 main units 21 Pocket forming section 22 forming parts 23 Through hole 24 Weld 24a First Weld Section 24b Second Weld Section 25 pillars 28 Gate marks 40 molds 43 Cavity 43a Pocket molding space 43b Two molding spaces 45 Runners Gate 46 R1 area R2 area R3 area

Claims

1. A synthetic resin retainer comprising an annular body and a plurality of horns projecting from the annular body in one axial direction at intervals in the circumferential direction, wherein a plurality of pockets for holding a plurality of rolling elements of a rolling bearing are formed between adjacent horns in the circumferential direction, Multiple gate marks formed at intervals in the circumferential direction, A weld formed between adjacent gate marks in the circumferential direction, It comprises a plurality of pocket forming sections, each positioned between the gate marks, where the respective pockets are formed, Each of the aforementioned pocket forming portions has a through hole formed in the bottom of the pocket that penetrates axially, The weld is formed in a predetermined number of spaces between all the gate marks, only in the region on one side of the through hole in the circumferential direction, and in the remaining predetermined number of spaces, only in the region on the other side of the through hole in the circumferential direction. The aforementioned weld is A first weld portion extending radially in an axial view, A retainer having a second weld portion that extends circumferentially from an intermediate radial position of the first weld portion to the through hole in an axial view.

2. The system further comprises a plurality of forming parts on which each of the aforementioned parts is formed, The retainer according to claim 1, wherein one gate mark is formed in each of the aforementioned forming portions.

3. A pair of annular components, each comprising the annular body and the plurality of horns, are connected in the axial direction. The retainer according to claim 1 or claim 2, comprising a column formed by connecting the respective ends of a pair of the annular parts.

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 a cage according to claim 1 or claim 2.

5. A method for forming the retainer described in claim 2, using a mold comprising 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, The cavity has multiple pocket forming spaces in which each of the pocket forming portions is formed, and multiple forming spaces in which each of the forming portions is formed, which are alternately formed in the circumferential direction. Each of the aforementioned molding spaces is connected to one of the aforementioned gates. A method for molding a retainer, wherein when pouring molten resin from each runner through the gate into the cavity, the volume of molten resin poured from one of the two circumferentially adjacent gates is greater than the volume of molten resin poured from the other gate.

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