Manufacturing method of crown type cage for angular contact ball bearing, and crown type cage for angular contact ball bearing

Abstract

To provide a manufacturing method of a crown type cage for an angular contact ball bearing which enables a resin crown type cage, including a cutout part allowing communication between a pair of pockets located adjacent to each other in a circumferential direction in a column part, to be molded without being damaged, and to provide the crown type cage for the angular contact ball bearing.SOLUTION: A resin crown type cage 40 includes a cutout part 46 allowing communication of a pair of pockets 45 located adjacent to each other in a circumferential direction. A column part 42 has: an outer diameter side claw part 47 formed at an outer diameter side relative to an outer diameter side opening edge part 46a of the cutout part 46; and an inner diameter side claw part 48 formed at an inner diameter side relative to an inner diameter side opening edge part 46b of the cutout part 46. An ejector pin P provided within a movable mold 212 pushes the crown type cage 40 so as to contact with an inner edge part 47b1 on an apical surface 47b at one axial side of the outer diameter side claw part 47 to release the crown type cage 40, held on the movable mold 212 by mold release after injection molding, from the movable mold 212.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a crown type cage for an angular contact ball bearing, and to a crown type cage for an angular contact ball bearing. [Background technology]

[0002] Conventionally, angular contact ball bearings used in automotive hub unit bearings have used a resin crown cage to hold multiple balls at equal circumferential intervals and allow each ball to roll freely. The crown cage has an annular rim portion and multiple pillar portions extending axially from multiple circumferential positions on the rim portion, forming multiple pockets for holding the balls, surrounded on three sides by pairs of circumferentially adjacent pillar portions and the rim portion.

[0003] For example, in the wheel bearing device 100 described in Patent Document 1, as shown in FIG. 7, the circumferential thickness of the column portion 103 of the resin crown-type cage 102 is reduced, and a cutout portion 105 is provided at the portion where adjacent balls 104 are closest to each other, thereby increasing the number of balls without increasing the pitch circle diameter and thereby increasing the load and bearing life. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-173966 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, although not specifically disclosed in Patent Document 1, such a crown type cage 102 is usually molded by axial draw molding, which allows multiple molding using an injection molding machine. For example, when such a crown type cage 102 is molded by axial draw molding, it is assumed that molten resin is injected from a gate G provided in the fixed die 211 into a cavity formed by a fixed die 211 and a movable die 212, as shown in Fig. 8.

[0006] After injection molding, the fixed mold 211 and the movable mold 212 are opened, and the crown cage 102 is removed from the fixed mold 211 while being held by the movable mold 212 due to molding shrinkage, and finally, is pressed by an ejector pin provided on the movable mold 212 and released from the movable mold 212.

[0007] The column portions 103 of the crown type cage 102 are branched by cutout portions 105 into an outer column (outer diameter side claw portion) 106 and an inner column (inner diameter side claw portion) 107. Because the inner column 107 has a flat tip end surface 107a, the tip end surface 107a of the inner column 107 can be pushed by an ejector pin P, as shown by arrow P1 in FIG. 8, and the crown type cage 102 can be released from the movable mold 212. However, in order to hold the balls 104 as much as possible within the crown type cage 102 while preventing interference with the inner ring raceway surface 111, it is necessary to make the tip end surface 107a of the inner column 107 an inclined surface (see FIG. 2). In this case, there is a risk that the tip end surface 107a of the inner column 107 will be deformed, making it difficult to push it with an ejector pin. Designing the ejector pin in accordance with the shape of the tip surface 107a of the inner column 107 may lead to a complicated mold, which may increase costs.

[0008] For this reason, it is conceivable that the ejector pin may press against the radial center position on the tip surface 106a of the outer column 106, where the ejector pin can easily come into contact, as shown by the arrow P2 in FIG.

[0009] Here, the portion of the outer column 106 that is radially outward from the parting line PL gradually becomes thinner toward the annular rim portion 108, while the portion that is radially inward from the parting line PL gradually becomes thinner as it moves away from the rim portion 108. In other words, there is a region where the circumferential width becomes narrower at the connection between the portion that is radially outward from the parting line PL and the portion that is radially inward from the parting line PL.

[0010] For this reason, if the temperature of the resin after injection does not drop completely and is still high at or above the glass transition point, and the radial center position of the tip surface 106a of the outer column 106 is pressed by the ejector pin, stress will be concentrated near the outer diameter corner 110 of the cutout portion 105, causing the outer column 106 to fall radially outward or, in extreme cases, to break.

[0011] Furthermore, because the volume of the resin decreases by about 3% as it solidifies, the injection-molded product has a smaller diameter than the cabinet of the molding die. As a result, a gap is created between the outer peripheral surface of the outer column 106 and the movable die 212, and the inner peripheral surface of the outer column 106 tightens the movable die 212, making it even more likely to fall radially outward when the ejector pin presses the radial center position of the tip surface 106a of the outer column 106.

[0012] The present invention has been made in view of the above-mentioned problems, and its object is to provide a method for manufacturing a crown type cage for an angular contact ball bearing, which is capable of molding, without damaging, a resin crown type cage having a pillar portion with a notch portion that connects a pair of circumferentially adjacent pockets, and the crown type cage for an angular contact ball bearing. [Means for solving the problem]

[0013] The above object of the present invention can be achieved by the following configuration. [1] A method for manufacturing a crown-type cage for an angular contact ball bearing, the method comprising: injection molding a resin crown-type cage, which comprises an annular rim portion and a plurality of column portions extending from a plurality of circumferential positions of the rim portion toward one axial side, the resin crown-type cage holding balls of the angular contact ball bearing so that they can roll freely by a plurality of pockets formed by a pair of circumferentially adjacent column portions and the rim portion, using an axial draw mold having a fixed mold and a movable mold; the pillar portion includes a cutout portion extending from an end portion on one axial side to an intermediate portion in the axial direction, the cutout portion communicating a pair of the pockets adjacent in the circumferential direction, the pillar portion has an outer diameter side claw portion formed on the outer diameter side of an outer diameter side opening edge portion of the cutout portion, and an inner diameter side claw portion formed on the inner diameter side of an inner diameter side opening edge portion of the cutout portion, After injection molding, the crown cage held in the movable die is released from the movable die by an ejector pin provided in the movable die pushing the crown cage so as to contact an inner edge portion on a tip end surface on one side in the axial direction of the outer diameter side claw portion. A method for manufacturing a crown cage for angular contact ball bearings.

[0014] [2] A crown type cage manufactured by the manufacturing method of a crown type cage for an angular contact ball bearing according to [1], a pressing mark by the ejector pin is formed in a region including an inner edge portion on a tip end surface on one axial side of the outer diameter side claw portion; Crown type cage for angular contact ball bearings. [Effects of the Invention]

[0015] According to the method for manufacturing a crown type cage for an angular contact ball bearing and the crown type cage for an angular contact ball bearing of the present invention, a resin crown type cage having cutouts in its column portions that connect a pair of circumferentially adjacent pockets can be released from a movable mold by pushing it in the axial direction with an ejector pin positioned so as to contact the inner edge of the tip surface of the outer diameter side claw portion of the column portion, and the crown type cage can be molded without being damaged. Moreover, regardless of the shape of the inner diameter side claw portion, there is no need to make major design changes to the ejector pin in the mold, which reduces the manufacturing cost of the mold. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional view of a hub unit bearing provided with a crown type cage for an angular contact ball bearing according to the present invention. [Figure 2] FIG. 2 is an enlarged view of the area surrounded by A in FIG. [Figure 3] FIG. 2 is an enlarged perspective view of a crown-type cage that holds the balls. [Figure 4] FIG. [Figure 5] 5A is a cross-sectional view of a molding die for molding the crown cage shown in FIG. 4, and FIG. 5B is a cross-sectional view of the crown cage when the fixed die is open and the crown cage is held by the movable die. [Figure 6] FIG. 10 is an enlarged perspective view of a modified crown type cage. [Figure 7] FIG. 10 is a cross-sectional view of a main portion of a conventional hub unit bearing. [Figure 8] FIG. 8 is a cross-sectional view of a molding die for molding the conventional crown type cage shown in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0017] A method for manufacturing a crown type cage for an angular contact ball bearing according to one embodiment of the present invention will be described in detail below with reference to FIGS. In this specification, "axially inner" refers to the vehicle body side of the hub unit bearing 10 when attached to the vehicle body, and is the right side in FIG. 1. "Axially outer" refers to the wheel side of the hub unit bearing 10 when attached to the vehicle body, and is the left side in FIG. 1. "Axial direction" refers to the direction in which the rotation axis O extends, and is the left-right direction in FIG. 1. "Radially outer" refers to the direction away from the rotation axis O. "Radially inner" refers to the direction approaching the rotation axis O. "Circumferential direction" refers to the direction of rotation around the rotation axis O. Furthermore, with regard to the crown-type retainer 40 used in the hub unit bearing 10, the side on which the column portion extends relative to the rim portion in the axial direction is referred to as the "one axial side," and the side of the rim portion relative to the column portion is referred to as the "other axial side."

[0018] The hub unit bearing 10 of this embodiment is for a drive wheel and mainly comprises an outer ring 20, a hub 30, a plurality of rolling elements (balls 11), a pair of sealing members 12, and a crown-type cage 40 made of resin.

[0019] The outer ring 20 comprises a substantially cylindrical portion 21 having double-row (two-row) outer ring raceways 23a, 23b on its inner peripheral surface, and a mounting flange 22 provided on the outer peripheral surface of this substantially cylindrical portion 21 and extending radially outward. During use, the outer ring 20 is connected and fixed to a knuckle (not shown) of the suspension device by a mounting bolt threaded into a threaded hole 22a provided in the mounting flange 22, and the outer ring 20 does not rotate while supported by the suspension device.

[0020] The hub 30 is made up of a hub ring 31 and an inner ring 32, and is disposed coaxially with the outer ring 20 on the inner diameter side of the outer ring 20, and rotates during use.

[0021] The hub ring 31 is provided with a wheel mounting flange 33 that extends radially outward from a portion that protrudes axially outward from the axially outer opening of the outer ring 20. The flange 33 has mounting holes 33a that penetrate axially at multiple locations around the circumference. Studs 28 are press-fitted into the mounting holes 33a. Nuts (not shown) are threaded onto the tips of the studs 28. This secures the wheel and braking rotor that constitute the wheel to the axially outer side of the flange 33. When practicing the present invention, it is also possible to secure the wheel and braking rotor to the axially outer side of the flange by forming female threaded holes in the flange and directly threading hub bolts into the female threaded holes.

[0022] An inner ring raceway 35a is provided on the outer peripheral surface of the hub ring 31 at a portion facing the outer ring raceway 23a of the outer ring 20. Furthermore, a small diameter step 34 is provided on the outer peripheral surface of the hub ring 31 at an end portion facing the outer ring raceway 23b of the outer ring 20.

[0023] The inner ring 32 is press-fit onto the outer peripheral surface of the small diameter step 34 while abutting against the step surface 34a of the small diameter step 34, and is fixed to the hub ring 31 by crimping portion 24 provided on the axially inner end surface of the hub ring 31. This positions and fixes the inner ring 32 in the axial direction relative to the hub ring 31. An inner ring raceway 35b is provided on the outer peripheral surface of the inner ring 32 in a portion facing the outer ring raceway 23b of the outer ring 20.

[0024] A splined hole 36 is formed in the center of the hub wheel 31, passing through the rotation axis O in the axial direction. A drive shaft connected to a constant velocity joint (not shown) is spline-fitted into the splined hole 36, and the drive shaft and hub wheel 31 are fixed together by screwing a nut onto a male threaded portion provided at the tip of the drive shaft. Therefore, when the vehicle is running, the drive shaft drives and rotates the hub 30, which in turn drives and rotates the wheel and braking rotor connected and fixed to the flange 33 of the hub 30. However, when the present invention is applied to a hub unit bearing for a driven wheel, a solid hub wheel 31 can be used.

[0025] Balls 11 are arranged rollably between outer ring raceways 23a, 23b and inner ring raceways 35a, 35b, with multiple balls each held by a resin crown-type cage 40. The balls 11 arranged in double rows are given a back-to-back (DB) type contact angle, so that the equator portions of the rolling surfaces of balls 11 are inclined by the amount of the contact angle with respect to an imaginary plane perpendicular to the central axis of hub 30. In this way, a double-row angular contact ball bearing is configured inside hub unit bearing 10.

[0026] A pair of sealing members 12 are arranged between the axial outer end of the outer ring 20 and the axial middle part of the hub ring 31, and between the axial inner end of the outer ring 20 and the axial inner end of the inner ring 32, and seal both axial sides of the internal space 14 in which multiple balls 11 are provided.

[0027] Next, the resin crown cage 40, which is the main part of the present invention, will be described in detail with reference to FIGS.

[0028] The crown-type cage 40 has an annular rim portion 41 and a plurality of pillar portions 42 each extending from multiple circumferential positions on the rim portion 41 to one axial side (upward in Figure 4), and is surrounded on three sides by a pair of circumferentially adjacent pillar portions 42 and the rim portion 41 to form a plurality of pockets 45 that hold the balls 11 in a freely rolling manner.

[0029] The rim portion 41 is arranged with a gap between the outer peripheral surface of the hub wheel 31 or the inner ring 32, which are opposed in the radial direction, and the inner peripheral surface of the outer ring 20. The rim portion 41 also defines a pocket bottom surface 45a on one axial side between the pair of pillar portions 42, and is formed in the shape of a concave curved surface.

[0030] The column portion 42 has a cutout portion 46 that is approximately U-shaped when viewed circumferentially, extending from one axial end to the middle axial portion, including the portion through which the pitch circle of the ball 11 passes, and that connects a pair of circumferentially adjacent pockets 45.

[0031] Therefore, each pillar portion 42 includes an outer diameter side claw portion 47 formed outer diameter side of the outer diameter side opening edge 46a of the cutout portion 46, an inner diameter side claw portion 48 formed inner diameter side of the inner diameter side opening edge 46b of the cutout portion 46, and a partition wall 49 formed on the other axial side of the rear side opening edge 46c connecting the outer diameter side opening edge 46a and the inner diameter side opening edge 46b of the cutout portion 46, and connecting the outer diameter side claw portion 47 and the inner diameter side claw portion 48, which circumferentially separates adjacent pockets 45.

[0032] The outer diameter side opening edge 46a is located radially outward from the center C of the pocket 45, extends substantially linearly in the axial direction, and in this embodiment is formed by the inner peripheral surface of the outer diameter side claw 47. The inner diameter side opening edge 46b is located radially inward from the center C of the pocket 26, and extends substantially linearly in a direction radially inward as it moves toward one axial side. The rear side opening edge 46c connects the other axial end of the outer diameter side opening edge 46a and the other axial end of the inner diameter side opening edge 46b in a curved surface shape.

[0033] The column portion 42 also has a parting line PL that extends in a substantially straight line from the outer diameter side opening edge 46a of the outer diameter side claw portion 47 across the partition wall 49 toward the other axial side to the outer circumferential surface of the rim portion 41. The parting line PL is formed on the circumferential side surface of the column portion 42 when injection molding is performed using an axial draw mold described below, at the butt portion between the fixed mold 211 and the movable mold 212, i.e., at the boundary between the portion formed by the fixed mold 211 that is located radially outward from the parting line PL and the portion formed by the movable mold 212 that is located radially inward from the parting line PL. In particular, in this embodiment, the parting line PL is formed along the outer diameter side opening edge 46a of the cutout portion 46.

[0034] The circumferential side surface of the column portion 42 is formed into a concave curved surface, with the outer diameter side claw portion 47, the inner diameter side claw portion 48, and the partition wall 49 constituting the pocket side surface 45b, with the exception of a portion. That is, the other axial half of the portion of the column portion 42 that is radially outward from the parting line PL does not constitute the pocket side surface. In this embodiment, the circumferential side surface of the column portion 25 excluding the other axial half of the portion that is radially outward from the parting line PL constitutes the pocket side surface 45b.

[0035] The pocket side surface 45b is curved so as to protrude more inward of the pocket 45 as it moves from the radial middle portion (center portion) toward both radial sides. As a result, the opening width of the pocket 45 in the circumferential direction is smaller than the diameter of the ball 11 at the radially outer end and the radially inner end of the pocket 45. This prevents the ball 11 from slipping out from the inside of the pocket 45 to the radially outer or inner side.

[0036] Furthermore, the pocket side surface 45b is curved with respect to the outer diameter side claw portion 47 and the partition wall 49 so as to protrude more inwardly of the pocket 45 from the axially intermediate portion toward both axial ends. As a result, the opening width of the pocket 45 in the circumferential direction is smaller than the diameter of the balls 11 at one axial end of the pocket 45 and at the other axial end of the pocket 45. This prevents the balls 11 from slipping out from inside the pocket 45 to one axial end or the other axial end. On the other hand, the pocket side surface 45b is formed so that the opening width of the pocket 45 in the circumferential direction is approximately constant with respect to the one axial end of the inner diameter side claw portion 48, allowing the crown type cage 40 to be separated from the movable die 212 described later.

[0037] In this way, pocket 45 is composed of pocket bottom surface 45a and pocket side surface 45b. Pocket 45 is composed of, for example, a continuous partially spherical concave surface in which the center C of pocket 45 substantially coincides with the center of ball 11 and has a radius of curvature slightly (usually about 3%) larger than the radius of curvature of the rolling surface of ball 11. Alternatively, pocket 45 may have a portion constituting pocket side surface 45b as a composite surface including multiple concave surface shapes with different radii of curvature. For example, the portion of pocket 45 where the rolling surface of ball 11 faces outer diameter side opening edge 46a and inner diameter side opening edge 46b of cutout portion 46 may be composed of a spherical concave surface with a larger radius of curvature than the other spherical concave surfaces.

[0038] The tip end faces of the inner diameter side claw portions 48 form inclined surfaces 48a that gradually decrease in diameter toward the other axial side so as to prevent interference between the crown type cage 40 and the inner ring raceway 35b when the crown type cage 40 is assembled into an angular contact ball bearing (see FIG. 2). The tip end faces of the inner diameter side claw portions 48 have an apex of the inclined surfaces 48a at approximately the same axial position as the tip end faces 47b of the outer diameter side claw portions 47 so that even one axial side portion of the circumferential side surface of the inner diameter side claw portions 48 can sufficiently guide the balls 11 in the radial direction.

[0039] As shown in FIG. 5( a), such a crown type cage 40 is formed by an axial draw die 200 having a fixed die 211 and a movable die 212. A parting line PL formed at the butt portion between the fixed die 211 and the movable die 212 is formed in a substantially straight line along an outer diameter side opening edge 46a of the cutout portion 46. A pocket side surface 45b in a portion located radially outward from the parting line PL, including the outer diameter side claw portions 47, is formed by the surface of the fixed die 211, while a pocket side surface 45b in a portion located radially inward from the parting line PL, including the inner diameter side claw portions 48, is formed by the surface of the movable die 212.

[0040] The pocket bottom surface 45a of the rim portion 41 is formed by the movable mold 212, while the outer peripheral surface, the other axial end surface, and the inner peripheral surface of the rim portion 41 are formed by the fixed mold 211.

[0041] 5(a), the crown cage 40 is molded by injecting molten resin into a cavity through a gate G, and then, as shown in FIG. 5(b), the fixed die 211 and the movable die 212 are opened, and the crown cage 40 is removed from the fixed die 211 while being held by the movable die 212 due to molding shrinkage. Next, the crown cage 40 is released from the movable die 212 by pressing it in the axial direction with an ejector pin P provided on the movable die 212.

[0042] Here, in this embodiment, the ejector pin P provided in the movable mold is positioned at a pressing position 55 (see Figure 4) so ​​as to contact the inner edge portion 47b1 on the tip surface 47b on one axial side of the molded outer diameter side claw portion 47.

[0043] 3 and 4, the circumferential width of the portion radially outward from the parting line PL gradually narrows toward the other axial side, while the circumferential width of the portion radially inward from the parting line PL gradually narrows toward one axial side. Also, the axial dimension L of the connection between the portion radially outward from the parting line PL and the portion radially inward from the parting line PL is only about 0.3 to 0.5 times the ball diameter, so the area of ​​the connection is small.

[0044] For this reason, as described above, if the temperature of the resin after injection has not yet dropped sufficiently and is still at a high temperature above the glass transition point, and the radial center position of the tip surface 47b of the outer claw portion 47 is pressed by the ejector pin P, stress will be concentrated near the outer diameter corner portion 50 of the cutout portion 46, causing the outer claw portion 47 to fall radially outward or, in extreme cases, to break.

[0045] Furthermore, because the volume of the resin decreases by about 3% as it solidifies, the diameter of the injection-molded product becomes smaller than the cavity of the mold. As a result, a gap is created between the outer peripheral surface of the outer diameter side claw portion 47 and the movable mold 212, and the inner peripheral surface of the outer diameter side claw portion 47 tightens the movable mold 212, making it even more likely to fall radially outward when the ejector pin presses the tip surface 106a of the outer column 106.

[0046] Therefore, in the crown type cage 40 of this embodiment, after mold opening, the ejector pin P presses the tip end surface 47b on one axial side of the outer diameter side claw portion 47 at a position that contacts the inner edge portion 47b1, as shown in Fig. 5(b). This reduces the moment load acting on the vicinity of the outer diameter side corner portion 50 of the cutout portion 46, and causes the pressing force of the ejector pin P to act evenly in the axial direction on the connecting portion between the portion located radially outside and the portion located radially inside with respect to the parting line PL, preventing the outer diameter side claw portion 47 from falling outward in the radial direction. Therefore, in the crown type cage 40 of this embodiment, a pressing mark by the ejector pin P is formed in a region including the inner edge portion 47b1 on the tip end surface 47b on one axial side of the outer diameter side claw portion 47. In Figure 4, the pressing position 55 of the ejector pin P is shown as a circle, but the tip shape and position of the ejector pin P are not limited to this as long as it includes a position where it contacts the inner edge portion 47b1 of the tip surface 47b of the outer diameter side claw portion 47. Furthermore, the number of ejector pins P is preferably the same as the number of pillar portions 42, but as long as they are provided at equally spaced positions in the circumferential direction, they may be less than the number of pillar portions 42, which simplifies the mold structure.

[0047] As described above, according to the manufacturing method of the crown type cage 40 of the present embodiment, it is possible to prevent the outer diameter side claw portions 47 from falling radially outward or being damaged, and to form the crown type cage 40 without damaging it.

[0048] (Variation 1) Next, a method for manufacturing a crown type cage according to a modified example of this embodiment will be described with reference to Fig. 6. The crown type cage 40 of this modified example differs from that of the above embodiment in that recesses 56 are formed on the tip end surfaces 47b of the outer diameter side claw portions 47.

[0049] The recess 56 opens to the outer diameter surface 47c of the outer diameter side claw portion 47 and is recessed toward the other axial side. This makes it possible to make the wall thickness uniform, thereby suppressing the occurrence of sink marks due to shrinkage of the molded product around the tip surface 47b of the outer diameter side claw portion 47.

[0050] When such a crown type cage 40 is injection molded, the recesses 56 are formed by the movable mold 212. Furthermore, when the crown type cage 40 is released from the movable mold 212, the ejector pin P is positioned so as to simultaneously come into contact with the inner edge portions 47b1 of the tip ends 47b of the outer diameter side claw portions 47 and the bottom edge portions 56a of the recesses 56. As a result, even in the case of a crown type cage 40 in which the recesses 56 are formed on the tip ends 47b of the outer diameter side claw portions 47, the outer diameter side claw portions 47 are prevented from falling radially outward or being damaged, and the crown type cage 40 can be molded without being damaged.

[0051] The present invention is not limited to the above-described embodiment and modifications, and can be modified, improved, etc. as appropriate.

[0052] As described above, the present specification discloses the following: (1) A method for manufacturing a crown type cage for an angular contact ball bearing, the method comprising: injection molding a resin crown type cage, which comprises an annular rim portion and a plurality of column portions extending from a plurality of circumferential positions of the rim portion toward one side in the axial direction, and which holds balls of the angular contact ball bearing so that they can roll freely by a plurality of pockets formed by a pair of circumferentially adjacent column portions and the rim portion, using an axial draw mold having a fixed mold and a movable mold; the pillar portion includes a cutout portion extending from an end portion on one axial side to an intermediate portion in the axial direction, the cutout portion communicating a pair of the pockets adjacent in the circumferential direction, the pillar portion has an outer diameter side claw portion formed on the outer diameter side of an outer diameter side opening edge portion of the cutout portion, and an inner diameter side claw portion formed on the inner diameter side of an inner diameter side opening edge portion of the cutout portion, After injection molding, the crown cage held in the movable die is released from the movable die by an ejector pin provided in the movable die pushing the crown cage so as to contact an inner edge portion on a tip end surface on one side in the axial direction of the outer diameter side claw portion. A method for manufacturing a crown cage for angular contact ball bearings. According to this configuration, the ejector pin presses the crown-type cage so that it contacts the inner edge of the tip surface of the outer diameter side claw portion, thereby releasing it from the movable mold. This reduces the moment load acting near the outer diameter side corner of the cutout portion, preventing the outer diameter side claw portion from falling radially outward, and allows the crown-type cage to be molded without damaging it.

[0053] (2) The outer diameter side portion of the tip end surface on the one axial side of the outer diameter side claw portion further includes a recess that opens to an outer peripheral surface and is recessed toward the other axial side, when the crown-type cage is injection-molded, the ejector pin is positioned so as to simultaneously contact an inner edge portion of the tip end surface on one axial side of the outer diameter side claw portion and a bottom edge portion of the recess. A method for manufacturing the crown type cage for an angular contact ball bearing according to (1). According to this configuration, the recessed portion prevents sink marks due to shrinkage of the crown type cage, and also prevents the outer diameter side claw portions from falling radially outward when the crown type cage is released from the movable mold.

[0054] (3) A crown type cage manufactured by the manufacturing method of a crown type cage for an angular contact ball bearing according to (1) or (2), a pressing mark by the ejector pin is formed in a region including an inner edge portion on a tip end surface on one axial side of the outer diameter side claw portion; Crown type cage for angular contact ball bearings. According to this configuration, the ejector pin presses the crown-type cage so that it contacts the inner edge of the tip surface of the outer diameter side claw portion, thereby releasing it from the movable mold. This reduces the moment load acting near the outer diameter side corner of the cutout portion, preventing the outer diameter side claw portion from falling radially outward, and allows the crown-type cage to be molded without damaging it. [Explanation of symbols]

[0055] 10 Hub unit bearing 11 balls 40 Crown retainer 41 Rim 42 Column section 45 pockets 45a Bottom of pocket 45b Pocket side 46 Notch 46a Outer diameter side opening edge 46b Inner diameter side opening edge 46c Back opening edge 47 Outer diameter side claw part 47b Tip surface of outer diameter side claw 47b1 Inner edge 48 Inner diameter claw 49 Bulkhead 56 Recess 56a Bottom edge 200 Axial draw forming die 211 Fixed type 212 Mobile type P Ejector pin PL parting line

Claims

1. A method for manufacturing a crown type cage for an angular contact ball bearing, the method comprising: injection molding a resin crown type cage, which comprises an annular rim portion and a plurality of column portions extending from a plurality of circumferential positions of the rim portion toward one axial direction; the resin crown type cage rollingly holding balls of the angular contact ball bearing by a plurality of pockets formed by each pair of circumferentially adjacent column portions and the rim portion; and injection molding the resin crown type cage using an axial draw mold having a fixed mold and a movable mold, the pillar portion includes a cutout portion extending from an end portion on one axial side to an intermediate portion in the axial direction, the cutout portion communicating a pair of the pockets adjacent in the circumferential direction with each other, the pillar portion has an outer diameter side claw portion formed on the outer diameter side of an outer diameter side opening edge portion of the cutout portion, and an inner diameter side claw portion formed on the inner diameter side of an inner diameter side opening edge portion of the cutout portion, After injection molding, the crown cage held in the movable die is released from the movable die by an ejector pin provided in the movable die pushing the crown cage so as to contact an inner edge portion on a tip end surface on one side in the axial direction of the outer diameter side claw portion. A method for manufacturing a crown cage for angular contact ball bearings.

2. an outer diameter side portion of the tip end surface on the one axial side of the outer diameter side claw portion further includes a recess that opens to an outer peripheral surface and is recessed toward the other axial side, After injection molding, the crown cage held in the movable die is released from the movable die by the die opening, by the ejector pin pushing the crown cage so that the ejector pin simultaneously contacts the inner edge portion of the tip end surface on one side of the outer diameter side claw portion in the axial direction and the edge portion of the inner diameter side end surface of the recess. A method for manufacturing the crown type cage for an angular contact ball bearing according to claim 1.

3. 3. A crown type cage for an angular contact ball bearing manufactured by the manufacturing method of the crown type cage for an angular contact ball bearing according to claim 1 or 2, a pressing mark by the ejector pin is formed in a region including an inner edge portion on a tip end surface on one axial side of the outer diameter side claw portion; Crown type cage for angular contact ball bearings.

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