Cage and angular contact ball bearing for angular contact ball bearings

Abstract

To provide a retainer for an angular contact ball bearing which can easily secure a force for holding a ball in a pocket before the ball is arranged between an outer ring raceway and an inner ring raceway, and to provide the angular contact ball bearing.SOLUTION: A retainer 5 includes: an annular rim part 22; multiple column parts 23 which respectively extend from multiple positions as seen in a circumferential direction of the rim part 22 to one axial side and each of which has a circumferential side surface having a concave curve shape; and multiple pockets 24 each of which is surrounded on threes sides by the two column parts 23 located adjacent to each other in the circumferential direction of the multiple column parts 23 and the rim part 22 and retains a ball 4 therein. Each of the multiple column parts 23 has an inclined surface part 26, which inclines in a direction toward the radial inner side as it goes to the one axial side, at one axial side portion of a radial outer surface and has a cutout 27, which is open to the one axial side and both sides in the circumferential direction and allows the two pockets 24 located adjacent to each other in the circumferential direction to communicate with each other, at the radial inner side relative to the inclined surface part 26.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a cage for an angular ball bearing and an angular ball bearing provided with the cage for an angular ball bearing.

Background Art

[0002] In an angular ball bearing used for a hub unit bearing for an automobile or the like, a plurality of balls arranged between an outer ring raceway and an inner ring raceway are arranged at equal intervals in the circumferential direction using a crowned cage for an angular ball bearing and are held so as to be freely rotatable.

[0003] Figs. 10 to 13 show a cage 100 which is a crowned cage for an angular ball bearing described in Japanese Unexamined Patent Application Publication No. 2017-125560 (Patent Document 1). The cage 100 includes an annular rim portion 101, a plurality of column portions 102 each extending from a plurality of locations in the circumferential direction of the rim portion 101 to one side in the axial direction and each having a circumferential side surface with a concave curved surface shape, and a plurality of pockets 103 for holding balls each surrounded by two column portions 102 adjacent to each other in the circumferential direction among the plurality of column portions 102 and the rim portion 101 on three sides.

[0004] In a radial ball bearing such as an angular ball bearing, the rated load necessary for bearing selection is obtained by using the following formula (1) representing the basic dynamic rated load Cr. Cr = b m f c (icosα) 0.7 Z 2 / 3 Dw 1.8 ···(1) Here, in formula (1), b m and f c are constants determined by the bearing material, shape, and manufacturing quality, i is the number of rows of balls in one bearing, α is the contact angle, Z is the number of balls included in one row, and Dw is the diameter of the ball. It can be seen from formula (1) that by increasing the number of balls (Z) included in one row, the basic dynamic rated load Cr can be improved and the bearing life can be extended.

[0005] In the holder 100, each of the multiple columnar sections 102 has a notch 104 that opens to one side in the axial direction, both sides in the circumferential direction, and radially inward, extending from one end in the axial direction to the axial middle section, and connecting two adjacent pockets 103 in the circumferential direction. The inner diameter of each of the multiple columnar sections 102, i.e., the portion located radially outside the notch 104, is larger than the outer diameter of the rim section 101. With such a holder 100, the distance between two adjacent balls in the circumferential direction can be reduced based on the presence of the notch 104, making it easier to increase the number of balls included in one row. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2017-125560 [Overview of the project] [Problems that the invention aims to solve]

[0007] The crown-shaped cage 100 described in Japanese Patent Publication No. 2017-125560 has room for improvement in terms of ensuring the workability of the assembly of angular contact ball bearings. The reasons for this are explained below.

[0008] When assembling an angular contact ball bearing equipped with a cage 100, the balls are first held in multiple pockets 103 of the cage 100, and then these balls are positioned between the outer ring raceway provided on the inner circumferential surface of the outer member and the inner ring raceway provided on the outer circumferential surface of the inner member. For this reason, it is necessary to prevent these balls from falling out of the pockets 103 before they are positioned between the outer and inner ring raceways.

[0009] Specifically, in a structure like the holder 100, which has a notch 104 extending from one axial end of the column portion 102 to the axial middle portion, it is necessary to firmly hold the ball in the pocket 103 with the rim portion 101 and the axial portions of two adjacent column portions 102 in the circumferential direction, i.e., the portions located radially outside the notch 104, so that the ball does not fall out of the pocket 103. For this reason, it is important that the shape of the portion of the column portion 102 located radially outside the notch 104, in particular the shape of the two pointed portions 105 located at both ends in the circumferential direction of the radially outer end of the axial end of the column portion 102, is correctly formed.

[0010] However, as shown in Figures 10 and 11, the axial side of the column 102 has a greater wall thickness than the other axial side of the column 102, and moreover, the change in wall thickness in the axial direction and the change in wall thickness in the radial direction are large. For this reason, when the cage 100 is manufactured by injection molding, sink marks, which are undesirable deformations due to molding shrinkage, tend to occur in the axial side of the column 102. When sink marks occur in the axial side of the column 102, the two pointed portions 105 of the column 102 deform to tilt to one side in the axial direction and outward in the radial direction, that is, they deform to move away from the rolling surface of the ball held in the pocket 103, so the force holding the ball in the pocket 103 is reduced. Therefore, there is room for improvement in terms of ensuring the workability of the assembly work of the angular contact ball bearing.

[0011] The present invention aims to provide a cage for angular contact ball bearings and an angular contact ball bearing that facilitates securing the force to hold the balls in the pocket before they are positioned between the outer ring raceway and the inner ring raceway. [Means for solving the problem]

[0012] An angular contact ball bearing cage according to one aspect of the present invention comprises an annular rim portion, a plurality of columnar portions extending axially from a plurality of locations in the circumferential direction of the rim portion, each having a concave curved circumferential side surface, and a plurality of pockets for holding balls, each surrounded on three sides by two circumferentially adjacent columnar portions and the rim portion.

[0013] Each of the plurality of columnar portions has an inclined surface portion on one axial side of its radially outer surface that is inclined radially inward as it moves toward the one axial side, and a notch located radially inward from the inclined surface portion that opens toward one axial side and both sides in the circumferential direction, connecting two adjacent pockets in the circumferential direction.

[0014] In one embodiment of the present invention, the cage for an angular contact ball bearing is composed of a flat surface, and the flat surface has a shape that, when viewed from one axial side, extends from the central axis of the rim portion and extends in a direction perpendicular to a radial line passing through the circumferential center of the column portion having the inclined surface.

[0015] An angular contact ball bearing according to one aspect of the present invention comprises an outer member having an angular contact outer ring raceway on its inner circumferential surface, an inner member having an angular contact inner ring raceway on its outer circumferential surface, a plurality of balls disposed between the outer ring raceway and the inner ring raceway, and a cage for holding the balls so as to be able to roll, wherein the cage is the cage for the angular contact ball bearing of the present invention.

[0016] An angular contact ball bearing according to one aspect of the present invention is used as a hub unit bearing for rotatably supporting an automobile wheel with respect to a suspension system. [Effects of the Invention]

[0017] According to one embodiment of the present invention, a cage for an angular contact ball bearing and an angular contact ball bearing can ensure a high force for holding the balls in the pocket before they are positioned between the outer ring raceway and the inner ring raceway. [Brief explanation of the drawing]

[0018] [Figure 1] Figure 1 is a cross-sectional view of a hub unit bearing according to the first example of the embodiment of the present invention. [Figure 2] Figure 2 is a perspective view of a cage for an angular ball bearing according to the first example, seen from one axial side. [Figure 3] Figure 3 is a perspective view of a part of the circumferential direction of a cage for an angular ball bearing according to the first example, seen from one axial side and the inner diameter side. [Figure 4] Figure 4 is a view of a cage for an angular ball bearing according to the first example, seen from one axial side. [Figure 5] Figure 5 is an enlarged view of the upper end portion of FIG. 4. [Figure 6] Figure 6 is a cross-sectional view taken along line A-A of FIG. 4. [Figure 7] Figure 7 is a cross-sectional view taken along line B-B of FIG. 4. [Figure 8] Figure 8 is a partial cross-sectional view of a mold device used when manufacturing a cage for an angular ball bearing according to the first example by injection molding. [Figure 9] Figure 9 is a view corresponding to FIG. 5 regarding the second example of the embodiment of the present invention. [Figure 10] Figure 10 is a perspective view of a conventional cage for an angular ball bearing, seen from one axial side. [Figure 11] Figure 11 is a perspective view of a part of the circumferential direction of a conventional cage for an angular ball bearing, seen from one axial side and the inner diameter side. [Figure 12] Figure 12 is a view of a conventional cage for an angular ball bearing, seen from one axial side. [Figure 13] Figure 13 is a cross-sectional view taken along line C-C of FIG. 12.

Embodiments for Carrying Out the Invention

[0019] [First Example] The first example of the embodiment of the present invention will be described with reference to FIGS. 1 to 8.

[0020] This example demonstrates the application of an angular contact ball bearing equipped with the cage for angular contact ball bearings of the present invention to a hub unit bearing for rotatably supporting an automobile wheel relative to a suspension system. The angular contact ball bearing of the present invention is not limited to hub unit bearings, but can also be applied to single-row or double-row angular contact ball bearings incorporated into various mechanical devices.

[0021] The hub unit bearing 1 is for a drive wheel and comprises an outer ring 2 which is an outer member, a hub 3 which is an inner member, a plurality of balls 4, and two cages 5, each of which is an angular contact ball bearing cage. The angular contact ball bearing of the present invention is not limited to hub unit bearings for drive wheels, but can also be applied to hub unit bearings for driven wheels.

[0022] With respect to the hub unit bearing 1, the axial outer side is the left side of Figure 1, which corresponds to the outer side in the width direction of the vehicle when assembled to the vehicle, and the axial inner side is the right side of Figure 1, which corresponds to the center side in the width direction of the vehicle when assembled to the vehicle.

[0023] The outer ring 2 has double rows of outer ring raceways 6a and 6b on its inner circumferential surface, each of which is an angular outer ring raceway. The outer ring 2 has large-diameter groove shoulders 7 on the inner circumferential surface, specifically in the portion adjacent to the axially inward side of the axially inward outer ring raceway 6a and in the portion adjacent to the axially outward side of the axially outward outer ring raceway 6b. The outer ring 2 has a stationary flange 8 projecting radially outward in its axial middle section. The stationary flange 8 has support holes 9 that penetrate axially at multiple locations in the circumferential direction in its radial middle section.

[0024] In this example, the support hole 9 is made up of a threaded hole. The outer ring 2 is supported and fixed to the suspension system by screwing support bolts, which are inserted through holes provided in the knuckle of the suspension system, into the support holes 9 of the stationary flange 8 from the axial inside, and does not rotate even when the wheel rotates.

[0025] The hub 3 has double rows of inner ring raceways 10a and 10b on its outer circumference, each of which is an angular contact inner ring raceway, and is arranged coaxially with the outer ring 2, radially inward from the outer ring 2. The hub 3 has a rotating flange 11 that protrudes radially outward in the portion located axially outward from the outer ring 2, and a cylindrical pilot portion 12 at its axially outward end.

[0026] The rotating flange 11 has mounting holes 13 that penetrate axially at multiple locations in the circumferential direction in the radial middle section. Studs 14 for connecting and fixing braking rotating bodies such as discs and drums, and wheels constituting the wheels, to the rotating flange 11 are press-fitted and serrated into each of the mounting holes 13. In other words, in this example, the mounting holes 13 are made up of press-fit holes.

[0027] The braking rotating body and wheel are connected and fixed to the rotating flange 11 by inserting the pilot portion 12 through the central hole provided in the center of each, and inserting the studs 14 through the through holes provided at multiple locations in the circumferential direction in the radial middle of each, and then screwing hub nuts onto the tips of the studs 14.

[0028] The mounting holes for the rotating flange can also be made of threaded holes. In this case, the braking rotating body and the wheel are joined and fixed to the rotating flange by screwing hub bolts, which are inserted through holes in the braking rotating body and through holes in the wheel, into the mounting holes.

[0029] In this example, the hub 3 is formed by combining the inner ring 15 and the hub ring 16.

[0030] The inner ring 15 has an inner ring raceway 10a on its outer circumferential surface, which is one of the two rows of inner ring raceways 10a and 10b, with the innermost inner ring raceway 10a in the axial direction.

[0031] The hub wheel 16 has an outer inner ring raceway 10b, one of two rows of inner ring raceways 10a and 10b, in the axial middle portion of its outer circumference. The hub wheel 16 has a rotating flange 11 in the portion located axially outward from the outer inner ring raceway 10b, and a pilot portion 12 at the axially outward end.

[0032] The hub wheel 16 has a small-diameter cylindrical portion 17 located axially inward from the inner ring raceway 10b on the axially outer side, which has a smaller outer diameter than the adjacent portion on the axially outer side, and into which the inner ring 15 is fitted. The hub wheel 16 has a crimping portion 18 that bends radially outward from the axially inward end of the small-diameter cylindrical portion 17 and presses against the axially inward end face of the inner ring 15. In other words, the hub 3 in this example is constructed by fitting the inner ring 15 onto the small-diameter cylindrical portion 17 of the hub wheel 16, and then clamping the inner ring 15 from both axial sides between the stepped surface 19 located at the axially outer end of the small-diameter cylindrical portion 17 and the crimping portion 18, thereby joining the inner ring 15 and the hub wheel 16. The inner ring can also be joined to the hub wheel by a nut or press-fitting.

[0033] The balls 4 are arranged to roll freely between the double-row outer ring raceways 6a, 6b and the double-row inner ring raceways 10a, 10b, with multiple balls in each row, held by the cages 5 of each row. As a result, the hub 3 is rotatably supported radially inward of the outer ring 2.

[0034] The hub unit bearing 1 in this example has a uniform diameter PCD type structure in which the pitch circle diameter of the balls 4 in the axial inner row is equal to the pitch circle diameter of the balls 4 in the axial outer row. However, the present invention can also be applied to a different diameter PCD type hub unit bearing in which the pitch circle diameter of the balls in the axial inner row is smaller or larger than the pitch circle diameter of the balls in the axial outer row.

[0035] The hub unit bearing 1 in this example further includes sealing devices 21a and 21b that close the axial openings on both sides of the cylindrical rolling element installation space 20, which is located between the inner circumferential surface of the outer ring 2 and the outer circumferential surface of the hub 3 and on which the balls 4 are arranged. In other words, the sealing devices 21a and 21b prevent leakage of the grease sealed in the rolling element installation space 20 and prevent foreign matter such as muddy water from entering the rolling element installation space 20.

[0036] Next, we will specifically describe the cages 5 in each row that are incorporated into the hub unit bearing 1 of this example. With respect to the cages 5, the axial, radial, and circumferential directions refer to the axial, radial, and circumferential directions of the rim portion 22 that constitutes the cage 5, unless otherwise specified.

[0037] Each of the retainers 5 in each row has the same shape as the others, and they are assembled in opposite directions with respect to the axial direction. In other words, the retainers 5 on the axial inner side are the same shape as the retainers 5 on the axial outer side, but inverted with respect to the axial direction. That is, with respect to the retainers 5 on the axial inner side, the axial inner side corresponds to one axial side, and the axial outer side corresponds to the other axial side. In contrast, with respect to the retainers 5 on the axial outer side, the axial outer side corresponds to one axial side, and the axial inner side corresponds to the other axial side.

[0038] Since the retainers 5 in each row have the same shape, the shape of these retainers 5 will be explained below by taking one retainer 5 as an example.

[0039] The cage 5 is a crown-shaped cage for an angular contact ball bearing, manufactured as a single unit by injection molding, specifically axial draw molding, of synthetic resin, and has a generally truncated cone shape.

[0040] Various synthetic resins such as polyamide 66 (PA66), polyamide 6 (PA6), polyamide 46 (PA46), polyamide 9T (PA9T), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), polyacetal (POM), and phenolic resin (PF) can be used as the synthetic resin constituting the retainer 5. Various reinforcing fibers such as glass fibers, polyethylene fibers, carbon fibers, and aramid fibers can be mixed into these synthetic resins as needed.

[0041] The holder 5 comprises an annular rim portion 22, a plurality of columnar portions 23 extending axially from multiple locations in the circumferential direction of the rim portion 22, each having a concave curved circumferential side surface, and a plurality of pockets 24 for holding the ball 4, each surrounded on three sides by two adjacent columnar portions 23 in the circumferential direction and the rim portion 22.

[0042] As shown in Figures 1, 6, and 7, the rim portion 22 has a substantially cylindrical outer surface and an outer diameter smaller than the inner diameter of the portion between the double rows of outer ring raceways 6a and 6b on the inner surface of the outer ring 2. The rim portion 22 has a substantially cylindrical inner surface and an inner diameter larger than the outer diameter of the portion between the double rows of inner ring raceways 10a and 10b on the outer surface of the hub 3. The other axial end of the column portion 23 is connected to multiple equally spaced locations in the circumferential direction on one axial side of the rim portion 22. Each portion of the rim portion 22 that is circumferentially separated from the column portion 23 on one axial side is configured as a concave curved surface. The other axial side of the rim portion 22 is configured as a flat surface existing on a virtual plane perpendicular to the central axis of the rim portion 22.

[0043] In this example, the rim portion 22 has a recess 25 on the other axial side of its inner circumferential surface, which is recessed radially outward. As shown in Figure 8, the recess 25 is formed by a protrusion 47 of the movable mold 45 used when manufacturing the retainer 5 by axial draw molding. The recess is not limited to the other axial side of the inner circumferential surface of the rim portion, but can also be provided on one axial side of the inner circumferential surface of the rim portion or in the axial middle portion, for example. The recess 25 and the protrusion 47 will be described further later.

[0044] Each of the multiple column sections 23 has the same shape. Therefore, in the following description, we will focus on one of these column sections 23 to explain its shape.

[0045] As shown in Figures 6 and 7, the column portion 23 has an inclined surface portion 26 on one axial side of its radially outer surface, which is inclined radially inward as it moves toward the axial side, and a notch 27 located radially inward from the inclined surface portion 26, which opens toward one axial side and both sides in the circumferential direction, and connects two adjacent pockets 24 in the circumferential direction.

[0046] In this example, the radial outer surface of the column portion 23 has a roughly S-shaped cross-sectional shape that extends radially outward as it moves toward one axial side, and consists of an axial other side portion 28, which is the portion from point X1 to point X2 in Figures 6 and 7, and an inclined surface portion 26, which is the portion from point X2 to point X3 in Figures 6 and 7, that slopes radially inward as it moves toward one axial side from the axial end of the axial other side portion 28. The inclined surface portion 26 is perpendicular to the central axis of the retainer 5 and is located axially to one side of the virtual plane S1 that includes the center C of the pocket 24, which will be described later. In this example, the inclined surface portion 26 is composed of a partially conical convex surface centered on the central axis of the retainer 5. Therefore, when viewed from one axial side, the inclined surface portion 26 has an arc shape centered on the central axis of the retainer 5, as shown in Figures 4 and 5.

[0047] When implementing the present invention, the axial dimension La of the inclined surface portion 26 (see Figure 6) can be determined to any size, but in order to suppress the change in wall thickness on one axial side of the column portion 23, it is preferable to set it to 50% or more of the axial dimension Lb of the portion of the radial outer surface of the column portion 23 that is located on one axial side of the virtual plane S1, and more preferably to 60% or more of the axial dimension Lb. In this example, the axial dimension La is set to approximately 60% of the axial dimension Lb.

[0048] When implementing the present invention, the inclination angle θ of the inclined surface portion 26 with respect to the central axis of the retainer 5 can be determined to any size, but it is preferably 10° to 30° and more preferably 15° to 25°, from the perspective of suppressing the change in wall thickness on one axial side of the column portion 23. In this example, the inclination angle θ is set to about 20°.

[0049] In this example, the radially inner surface of the column portion 23 consists of an axial other side portion 29 having a linear cross-sectional shape extending in one axial direction from the inner circumferential surface of the rim portion 22, a stepped portion 30 having a linear cross-sectional shape extending radially outward from the axial end of the axial other side portion 29, and an axial one side portion 31 having a linear cross-sectional shape extending radially outward from the radially outer end of the stepped portion 30 as it moves toward the axial side.

[0050] In this example, the notch 27 of the column portion 23 is provided so as to open only on one side in the axial direction and on both sides in the circumferential direction, in a range extending from one end on the axial side to the middle part in the axial direction. When implementing the present invention, the notch of the column portion may open not only on one side in the axial direction and on both sides in the circumferential direction, as in the conventional structure described above, but also on the radially inward side. That is, in the present invention, the notch of the column portion is interpreted as opening on at least one side in the axial direction and on both sides in the circumferential direction, and also includes notches that open on one side in the axial direction, both sides in the circumferential direction, and radially inward side.

[0051] In this example, the area where the notch 27 exists in the column 23 includes the portion through which the pitch circle, which is a circle centered on the central axis of the holder 5 and passing through the center C of the pocket 24 (described later), i.e., the center O of the ball 4, passes. That is, the pitch circle passes inside the notch 27. The notch 27 cuts out a roughly U-shape when viewed from the circumferential direction, extending from one end on the axial side of the column 23 to the axial middle. The radial width of the notch 27 increases toward one side on the axial side. In the holder 5 of this example, the presence of the notch 27 makes it possible to reduce the distance between two adjacent balls 4 in the circumferential direction, thus making it easier to increase the number of balls included in one row.

[0052] The column portion 23 has an outer column piece 32 in the portion of the axial side that is radially outward from the notch 27, and an inner column piece 33 in the portion of the axial side that is radially inward from the notch 27. The inclined surface portion 26 of the column portion 23 is located on the radially outer surface of the outer column piece 32, on one side of the virtual plane S1 in the axial direction.

[0053] In this example, the inner end face 35, which is the axial end face of the inner column piece 33, is located one axial side further to the outer end face 34, which is the axial end face of the outer column piece 32. When implementing the present invention, a configuration in which the inner end face and the outer end face are positioned at the same position with respect to the axial direction, or a configuration in which the outer end face is located one axial side further to the inner end face, can also be adopted.

[0054] In this example, the outer end face 34 is composed of a partially conical convex surface centered on the central axis of the retainer 5, which is inclined in a direction toward one side in the axial direction as it extends radially inward. The inner end face 35 is composed of a convex curved surface having an arc-shaped cross-section. When implementing the present invention, different shapes from those in this example can be adopted for the outer and inner end faces, such as a flat surface perpendicular to the central axis of the retainer.

[0055] In this example, a parting line 36 exists on the circumferential side surface of the column portion 23, located at the joint between the fixed mold 44 and the movable mold 45 during axial draw molding (see Figures 3, 6-8). The parting line 36 extends axially along the circumferential side surface of the column portion 23, from the part P1 near the other axial edge of the radial outer edge of the column portion 23 to the radial inner edge P2 of the axial edge of the outer column piece 32, and is slightly inclined radially outward as it moves toward the axial side. The parting line 36 is located radially outward from the virtual cylindrical surface S2, which is centered on the central axis of the retainer 5 and passes through the center C of the pocket 24, which will be described later. The axial portion of the parting line 36 is located along the radial inner edge of the outer column piece 32.

[0056] The column portion 23 consists of an outer column portion 37, which is the portion radially outside the parting line 36 (left side in Figures 6 and 7), and an inner column portion 38, which is the portion radially inside the parting line 36 (right side in Figures 6 and 7). The outer column portion 37 includes the outer column piece 32, and the inner column portion 38 includes the inner column piece 33.

[0057] Each inner surface of the multiple pockets 24 is configured as a partially spherical concave surface by the circumferential sides of two circumferentially opposing concave curved columnar portions 23 and a concave curved portion provided on one axial side of the rim portion 22 that is circumferentially offset from the columnar portions 23, and has a radius of curvature slightly larger than the radius of curvature of the rolling surface of the ball 4. The center C of the pocket 24 substantially coincides with the center O of the ball 4 held within the pocket 24.

[0058] Specifically, in this example, as shown in Figure 7, the portion of the circumferential side surface of the outer column portion 37 located on one axial side of the virtual plane S1, that is, the portion of the circumferential side surface of the outer column piece 32 located on one axial side of the virtual plane S1, is composed of an outer spherical concave surface 39, which is a partial spherical concave surface centered at the center C of the pocket 24. The outer spherical concave surface 39 has a radius of curvature that is slightly larger than the radius of curvature of the rolling surface of the ball 4. The portion of the circumferential side surface of the inner column portion 38 located on the other axial side of the virtual plane S1, and the portion of the rim portion 22 on one axial side that is circumferentially separated from the column portion 23, are composed of an inner spherical concave surface 40, which is a single partial spherical concave surface centered at the center C of the pocket 24. The radius of curvature of the inner spherical concave surface 40 is the same as the radius of curvature of the outer spherical concave surface 39. In this example, the inner surface of the pocket 24 is composed of two outer spherical concave surfaces 39 and one inner spherical concave surface 40 that are opposite each other in the circumferential direction.

[0059] In this example, the portion of the outer column portion 37's circumferential side surface located on the other axial side of the virtual plane S1 is formed by an outer cylindrical concave surface 41, which is a partially cylindrical concave surface centered on a straight line passing through the center C of the pocket 24 and parallel to the central axis of the retainer 5. The portion of the inner column portion 38's circumferential side surface located on one axial side of the virtual plane S1, that is, the portion of the inner column piece 33's circumferential side surface located on one axial side of the virtual plane S1, is formed by an inner cylindrical concave surface 42, which is a partially cylindrical concave surface centered on a straight line passing through the center C of the pocket 24 and parallel to the central axis of the retainer 5. Neither the outer cylindrical concave surface 41 nor the inner cylindrical concave surface 42 comes into contact with the rolling surface of the ball 4.

[0060] Of the outer column portion 37, each of the circumferential sides of the portion located axially to one side of the virtual plane S1 is composed of an outer spherical concave surface 39, which is a partially spherical concave surface centered at the center C of the pocket 24. Therefore, the thickness of the portion of the outer column portion 37 located axially to one side of the virtual plane S1, that is, the thickness of the portion of the outer column piece 32 located axially to one side of the virtual plane S1, increases in one direction in the axial direction and also increases radially to the outside.

[0061] In this example, as shown in Figure 8, the mold apparatus 43 used to manufacture the retainer 5 by axial draw molding comprises a fixed mold 44 and a movable mold 45, which are split molds that can be opened in the axial direction. As shown in Figure 8, with the fixed mold 44 and the movable mold 45 closed in the axial direction, a cavity 46 is defined between the fixed mold 44 and the movable mold 45, which is a space for molding the retainer 5.

[0062] The fixed type 44 has a portion that forms the axial side of the rim portion 22, the outer circumferential surface of the rim portion 22, the radial outer surface of each of the multiple column portions 23, and the circumferential sides of the outer column portions 37 that constitute each of the multiple column portions 23 on the surface of the retainer 5. The movable type 45 has a portion that forms the remaining part of the surface of the retainer 5. That is, the movable type 45 has a portion that forms the inner circumferential surface of the rim portion 22 and the radial inner surface of each of the multiple rim portions 22 on the surface of the retainer 5.

[0063] When manufacturing the retainer 5 by axial draw molding, molten synthetic resin is poured into the cavity 46. After the synthetic resin cools and solidifies, the molded retainer 5 is removed from the cavity 46 by opening the fixed mold 44 and the movable mold 45 in the axial direction. The mold opening is performed by moving the movable mold 45 upward relative to the fixed mold 44 as shown in Figure 8, without moving the fixed mold 44.

[0064] In this process, the retainer 5 moves upward in Figure 8 together with the movable mold 45, as the inner circumferential surface of the rim portion 22 and the radially inner surfaces of the multiple column portions 23 press down on a part of the movable mold 45 due to molding shrinkage. In this example, in order to ensure that the retainer 5 moves upward in Figure 8 together with the movable mold 45, a protrusion 47 is provided on the part of the movable mold 45 that molds the axially opposite side of the inner circumferential surface of the rim portion 22, protruding radially outward by about 0.05 mm to 0.1 mm. The retainer 5 is then made to move upward in Figure 8 together with the movable mold 45 by engaging the protrusion 47 with the recess 25 of the retainer 5 formed by the protrusion 47. When implementing the present invention, the recess 25 and protrusion 47 can be omitted if the retainer can be reliably moved together with the movable mold when the mold is opened, even without the recess 25 and protrusion 47.

[0065] Then, as described above, while the movable mold 45 and the retainer 5 are moving upward in Figure 8, a stationary ejector pin (not shown) pushes against the bottom of the retainer 5, which is part of the retainer 5, located at the other axial end of the outer end face 34 or the notch 27, thereby separating the retainer 5 from the movable mold 45.

[0066] In this example, the retainer 5 does not fall from the movable mold 45 until the movable mold 45 moves upward relative to the retainer 5 by approximately half the axial dimension of the retainer 5. Specifically, the retainer 5 falls from the movable mold 45 when the stepped portion 30 reaches below the lower edge of the movable mold 45. This ensures that the fall position of the retainer 5 is stable.

[0067] The hub unit bearing 1 can be assembled, for example, as follows: First, the balls 4 are inserted into the pockets 24 of the two cages 5. Specifically, for each of the two cages 5, the distance between the axial ends of two adjacent columnar portions 23 in the circumferential direction of the cage 5, with one axial side facing upward, is elastically widened, and the balls 4 are inserted into the pockets 24 by pushing them in from above and radially inward.

[0068] Next, two retainers 5, each with a ball 4 inserted into a pocket 24, are positioned inside the double-row outer ring raceways 6a and 6b of the outer ring 2. To do this, first, the balls 4 held in each of the pockets 24 of the retainer 5 are moved radially inward, so that the circumscribed diameter of the balls 4 around the central axis of the retainer 5 is smaller than the inner diameter of the large-diameter groove shoulder 7. In this state, the retainer 5 and the balls 4 held in the retainer 5 are passed radially inside the large-diameter groove shoulder 7. Then, the force pressing the balls 4 radially inward is released, making them free, so that the circumscribed diameter of the balls 4 around the central axis of the retainer 5 is larger than the inner diameter of the large-diameter groove shoulder 7. In this way, the retainer 5 and the balls 4 held in the retainer 5 are assembled to the outer ring 2 in a way that prevents them from being unintentionally separated.

[0069] Next, the hub ring 16 is inserted radially inward between the combined outer ring 2, the two cages 5, and the multiple balls 4, and then the inner ring 15 is fitted onto the small diameter cylindrical portion 17 of the hub ring 16. Then, by plastically deforming the axially inward end of the hub ring 16 radially outward, a crimped portion 18 is formed, and the inner ring 15 and the hub ring 16 are joined to form the hub 3. The hub unit bearing 1 is assembled in this manner. Note that the procedure for assembling the hub unit bearing 1 can be rearranged or performed simultaneously as appropriate, as long as it does not create a contradiction.

[0070] As described above, when assembling the hub unit bearing 1, it is necessary to prevent the balls 4 held in the pocket 24 of the cage 5 from falling out of the pocket 24 before they are positioned between the outer ring raceways 6a, 6b and the inner ring raceways 10a, 10b. Specifically, it is necessary to prevent the balls 4 from falling out of the pocket 24 by firmly holding them with two outer spherical concave surfaces 39 and one inner spherical concave surface 40 that form the inner surface of the pocket 24 and are opposed to each other in the circumferential direction. For this reason, it is important that the shape of the two outer spherical concave surfaces 39, in particular the shape of the ends on one axial side and radially outward of each of the two outer spherical concave surfaces 39, is correctly formed. In other words, it is important that the shape of the two pointed portions 48 located on both circumferential sides of the radially outward end of the outer column piece 32 that constitutes the column portion 23 is correctly formed.

[0071] In this regard, in the structure of this example, the thickness of the portion of the outer column piece 32 located on one axial side of the virtual plane S1 (see Figures 6 and 7) increases as it moves toward one axial side and also as it moves toward the outside in the radial direction. However, in the structure of this example, the outer column piece 32 has an inclined surface portion 26 on the axial side portion of its radially outer surface, which is inclined toward the radially inward direction as it moves toward one axial side. Therefore, based on the presence of the inclined surface portion 26, that is, compared to a structure without the inclined surface portion 26, the change in the thickness of the axial side portion of the outer column piece 32 can be kept small.

[0072] Therefore, when manufacturing the retainer 5 by injection molding, it is possible to suppress the occurrence of sink marks, which are undesirable deformations due to molding shrinkage, on one axial side of the outer column piece 32. Consequently, the shape of the two pointed portions 48 located at both ends in the circumferential direction of the radially outer end of the axially outer end of the outer column piece 32 can be correctly molded. In other words, the shape of the axially outer and radially outer ends of each of the two outer spherical concave surfaces 39 that constitute the inner surface of the pocket 24 can be correctly molded. As a result, it is easier to secure the force to hold the ball 4 in the pocket 24 before it is placed between the outer ring raceways 6a, 6b and the inner ring raceways 10a, 10b.

[0073] [Example 2] A second example of an embodiment of the present invention will be described with reference to Figure 9.

[0074] In this example, the inclined surface portion 26a provided on one axial side of the radially outer surface of the multiple column portions 23 constituting the retainer 5a is made of a flat surface. As shown in Figure 9, the inclined surface portion 26a, which is a flat surface, has a shape that extends in a direction perpendicular to the radial line α that extends from the central axis of the rim portion 22 and passes through the circumferential center of the column portion 23 having the inclined surface portion 26a, when viewed from one axial side. The axial edge of such an inclined surface portion 26a has a linear shape that linearly connects two pointed portions 48 located at both ends in the circumferential direction of the radially outer end of the outer column piece 32a on one axial side.

[0075] In the structure of this example, since the inclined surface portion 26a is made of the flat surface, the radial thickness of the central portion in the circumferential direction, which is the portion with the largest radial thickness among the axial portions of the outer column piece 32a, can be reduced compared to the structure of the first example in which the inclined surface portion is made of a partially conical convex surface centered on the central axis of the retainer. As a result, sink marks, which are undesirable deformations due to molding shrinkage, can be further suppressed in the axial portion of the outer column piece 32a. Other configurations and effects are the same as in the first example. [Explanation of Symbols]

[0076] 1 Hub unit bearing 2 Outer ring 3 Hubs 4 balls 5, 5a retainer 6a, 6b Outer ring track 7. Large diameter groove shoulder 8. Static flange 9 Support hole 10a, 10b Inner ring track 11 Rotating flange 12 Pilot Section 13 mounting holes 14 studs 15 Inner circle 16 hub wheels 17 Small diameter cylinder part 18 Crimping part 19 Step surface 20 Rolling element installation space 21a, 21b sealing device 22 Rim section 23 Pillar section 24 pockets 25 recesses 26, 26a Slope section 27 Notches 28 The other side in the axial direction 29 The other side in the axial direction 30 Steps 31 One side in the axial direction 32, 32a outer column piece 33 Inside column piece 34 Outer end face 35 Inner end face 36 parting lines 37 Outer column part 38 Inner column part 39 Outer spherical concave surface 40 Inner spherical concave surface 41 Outer cylindrical concave surface 42 Inner cylindrical concave surface 43. Mold equipment 44 Fixed type 45 Movable type 46 Cavity 47 Convex part 48 Apex 100 retainer 101 Rim section 102 Column section 103 pockets 104 Notches 105 Apex

Claims

1. The annular rim portion, Multiple columnar portions extending from multiple locations in the circumferential direction of the rim portion toward one axial direction, each having a concave curved surface in the circumferential direction, Each of the multiple pockets for holding a ball is surrounded on three sides by two adjacent columnar sections in the circumferential direction and the rim section, Equipped with, Each of the plurality of columnar portions has an inclined surface portion on one axial side of its radially outer surface that is inclined radially inward as it moves toward the one axial side, and a notch located radially inward from the inclined surface portion that opens toward one axial side and both sides in the circumferential direction, and connects two adjacent pockets in the circumferential direction. The inclined surface portion is provided on one axial side of the radially outer surface of the outer column piece, which is the portion of the column piece located radially outward from the notch, in order to suppress the occurrence of sink marks due to molding shrinkage on one axial side of the outer column piece. The inclined surface portion is perpendicular to the central axis of the rim portion and is located on one axial side of the virtual plane S1 that includes the center of the pocket. The axial dimension La of the inclined surface portion is 50% or more of the axial dimension Lb of the radial outer surface of the column portion from the virtual plane S1 to the edge portion on one side of the inclined surface portion in the axial direction. The inclination angle θ of the inclined surface portion with respect to the central axis of the rim portion is 10° or more and 30° or less. Cage for angular contact ball bearings.

2. The angular contact ball bearing cage according to claim 1, wherein the inclined surface portion is composed of a flat surface, and the flat surface has a shape that, when viewed from one side in the axial direction, extends from the central axis of the rim portion and extends in a direction perpendicular to a radial line passing through the circumferential center of the column portion having the inclined surface portion.

3. An outer member having an angular outer ring raceway on its inner circumferential surface, An inner member having an angular inner ring raceway on its outer surface, A plurality of balls are arranged between the outer ring raceway and the inner ring raceway, The system comprises a retainer for holding the aforementioned ball so that it can roll freely, The cage is the cage for the angular contact ball bearing described in claim 1 or 2. Angular contact ball bearing.

4. The angular contact ball bearing according to claim 3, used as a hub unit bearing for rotatably supporting an automobile wheel with respect to a suspension system.

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