Angular contact ball bearing

Abstract

To provide an angular ball bearing capable of increasing the number of balls and preventing the strength of the whole cage including a column part from being reduced.SOLUTION: The angular ball bearing 1 includes an inner ring 2, an outer ring 3, a plurality of balls 4 interposed between the inner ring 2 and the outer ring 3, and an annular cage 5 in which pockets Pt for holding the balls 4 are formed. In the cage 5, each pocket Pt is composed of annular parts 7, 8 and column parts 6, and in the cage 5, inside diameters or outside diameters of the column parts are in a range of 8-50% of ball diameters φ Da from a pitch circle P4 central part of the balls 4. T / dp * 100 is 0.40 or more and 1.50 or less, where dp is a pitch circle diameter of the ball 4, and T is a dimension of the thinnest part of a column width in the circumferential direction in the column part 6.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an angular contact ball bearing, and more particularly to an angular contact ball bearing with a separable outer ring, used for example as a main bearing portion of a reduction gear device for an industrial robot or the like. [Background technology]

[0002] Eccentric oscillating reducers are commonly used in the joints of industrial robots. The bearings used in reducers may be, for example, angular contact ball bearings with a separable outer ring. When incorporating angular contact ball bearings into reducers, the outer ring may be separated and first incorporated into the case, and the inner ring may be incorporated into the shaft or flange, which may then be combined with the outer ring incorporated into the case.

[0003] Previously, an angular contact ball bearing has been proposed in which the outer diameter of the counterbore of the inner ring and the diameter of the ball inscribed circle when the balls are assembled into a synthetic resin cage are controlled (Patent Document 1). By controlling these, the inner ring, balls, and cage are kept together, improving the ease of assembly using the above assembly method.

[0004] In the case of retainers used in full-ball angular contact ball bearings, openings are made between each pocket on the pitch circle of the balls, making it possible to use the retainer with full-ball angular contact ball bearings (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4824457 [Patent Document 2] Japanese Patent Application Publication No. 8-296650 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, one of the measures to meet the demand for greater moment rigidity and longer life in bearings used in reducers has been to increase the number of balls. When the number of balls is increased, the total weight of the balls also increases. As a result, when the weight of the balls acts on the cage, the cage deforms, causing the balls to overcome the inner ring counterbore diameter, and the inner ring, balls, and cage become separated. Furthermore, in conventional cages made of synthetic resin, when the number of pockets is increased to increase the number of balls, the pillars of the cage become thinner, and the strength of the pillars of the cage decreases.

[0007] An object of the present invention is to provide an angular contact ball bearing that allows an increase in the number of balls while preventing a decrease in the strength of the entire cage including the posts. [Means for solving the problem]

[0008] The angular contact ball bearing of the present invention comprises an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and an annular resin cage that holds the balls, the cage having a pair of annular portions and a plurality of column portions connecting the annular portions, and having pockets formed by the annular portions and column portions, and the balls are held in the pockets, The retainer is characterized in that, in a radial cross section, the column portion does not overlap with the pitch circle center of the ball, and the shortest distance from the pitch circle center of the ball to the column portion is between 8% and 50% of the ball diameter. The "radial cross section" is a cross section of the cage taken along an imaginary plane including the axial direction of the cage, that is, a so-called vertical cross section.

[0009] In the radial cross section of the cage, the bar portions do not overlap with the pitch circle center of the ball, and the shortest distance from the pitch circle center of the ball to the bar portions is 8% to 50% of the ball diameter. In other words, the inner diameter or outer diameter of the bar portions of the cage is in the range of 8% to 50% of the ball diameter from the pitch circle center of the ball. With this configuration, the inner or outer diameter of the bar portion is between 8% and 50% of the ball diameter from the center of the ball's pitch circle. This allows for an increase in the number of balls while preventing a decrease in the strength of the entire cage, including the bar portion. If the inner or outer diameter of the bar portion is less than 8% of the ball diameter from the center of the ball, the thinnest part of the circumferential width of the bar portion becomes too thin, resulting in a decrease in the strength of the bar portion compared to conventional structures. If the inner or outer diameter of the bar portion is more than 50% of the ball diameter from the center of the ball, the radial thickness of the cage becomes thin, resulting in a decrease in the strength of the entire cage compared to conventional structures.

[0010] If the pitch circle diameter of the balls is dp and the dimension T is the thinnest part of the circumferential column width of the column portion, T / dp × 100 may be 0.40 or more and 1.50 or less. In this case, the rigidity of the thinnest part of the column portion is ensured and a decrease in the strength of the entire cage can be more reliably prevented. If the ratio of T to dp is less than 0.40%, the thinnest part may be too thin, which may result in a decrease in the strength of the column portion compared to conventional structures. If the ratio of T to dp is greater than 1.50, the radial thickness of the cage may be thin, which may result in a decrease in the strength of the entire cage compared to conventional structures.

[0011] The ball packing rate may be 88% or more and 96% or less. The ball packing rate is expressed by the following formula. Filling rate = (ball diameter x number of balls) / (pitch circle diameter x π) By setting the ball filling rate to between 88% and 96%, it is possible to satisfy the required rated load and prevent interference between the balls during operation. If the ball filling rate is less than 88%, the number of balls is too small to satisfy the required rated load. If the ball filling rate is more than 96%, the distance between the balls becomes too small, causing interference between the balls during operation.

[0012] The inner surface of the retainer may be provided with claws that protrude radially inward, and the inner ring counterbore portion on the outer surface of the inner ring may be provided with an annular recess and an insertion groove that allows the claws to pass into the bearing. The raceway surface of the inner ring is connected to the front surface of the inner ring via the inner ring counterbore portion. The front surface of the inner ring refers to the side surface that does not support the axial load. "Inside the bearing" is synonymous with the bearing space between the inner and outer rings.

[0013] With this configuration, even if the cage is deformed by the weight of the balls and the balls unexpectedly go over the inner race counterbore, the claws of the cage will catch on the recesses in the inner race counterbore, preventing the cage and balls from separating from the inner race.

[0014] The outer peripheral surface of the retainer may be provided with claw portions that protrude radially outward, and the outer ring counterbore portion on the inner peripheral surface of the outer ring may be provided with an annular recess and an insertion groove that allows the claw portions to pass into the bearing. The raceway surface of the outer ring is connected to the front surface of the outer ring via the outer ring counterbore portion. The front surface of the outer ring refers to the side surface that does not support the axial load.

[0015] When the outer ring, balls, and cage are integrated, even if the cage is deformed by the weight of the balls and the balls unexpectedly climb over the outer ring counterbore, the claws on the cage will catch on the recesses in the outer ring counterbore, preventing the cage and balls from separating from the outer ring.

[0016] A plurality of the filling grooves may be provided, and the plurality of filling grooves may be arranged at equal intervals in the circumferential direction.

[0017] A plurality of the claws may be provided, and these claws may be evenly spaced in the circumferential direction. In this case, the load acting on the contact points between the claws of the cage and the recesses of the inner ring can be evenly distributed in the circumferential direction, thereby enabling the cage and balls to be stably held.

[0018] The claws may be provided in two or more rows at different axial positions, and the claws in different rows may be arranged at different phases in the circumferential direction. When the inner ring, balls, and cage are integrated, it may be possible for the circumferential phase of the claws in the first row to match the circumferential phase of the filling groove in the inner ring counterbore, causing the claws in the first row to pass through the filling groove. Even in this case, the claws in the second row will catch on the recesses in the inner ring, preventing separation of the inner ring, balls, and cage. [Effects of the Invention]

[0019] The angular contact ball bearing of the present invention comprises an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and an annular resin cage that holds the balls. The cage has a pair of annular portions and a plurality of column portions connecting the annular portions, and has pockets formed by the annular portions and the column portions, and the pockets hold the balls. In the radial cross section of the cage, the column portions do not overlap with the pitch circle centers of the balls, and the shortest distance from the pitch circle center of the balls to the column portions is 8% to 50% of the ball diameter. In other words, the inner diameter or outer diameter of the column portions of the cage is in the range of 8% to 50% of the ball diameter from the pitch circle center of the balls. This allows for an increase in the number of balls while preventing a decrease in the strength of the entire cage, including the column portions. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a vertical cross-sectional view of an angular contact ball bearing according to a first embodiment of the present invention. [Figure 2] 4 is a longitudinal sectional view showing a column relief portion of a cage in the angular contact ball bearing. FIG. [Figure 3A] FIG. 10 is a partial cross-sectional view of a conventional retainer taken along a plane perpendicular to the axial direction. [Figure 3B] 1 is a partial cross-sectional view of a cage of an angular contact ball bearing according to a first embodiment, taken along a plane perpendicular to the axial direction. [Figure 3C] FIG. 2 is a perspective view of a portion of the cage as viewed from the inner diameter side. [Figure 3D]FIG. 10 is a perspective view of a part of the cage when the pocket is cut, seen from the inner diameter side. [Figure 3E] FIG. 10 is a perspective view of a part of the cage when the pocket is cut, as seen from the outer diameter side. [Figure 4] FIG. 4 is a partial cross-sectional view of a main part illustrating a post width of the cage. [Figure 5A] FIG. 4 is a partial cross-sectional view of a main part showing that a part of a column portion of the cage is on the pitch circle diameter. [Figure 5B] FIG. 4 is a partial cross-sectional view of a main part showing that a part of a column portion of the cage is on the pitch circle diameter. [Figure 6] FIG. 6 is a partial cross-sectional view of a cage of an angular contact ball bearing according to a second embodiment of the present invention. [Figure 7] FIG. 10 is a vertical cross-sectional view of an angular contact ball bearing according to a third embodiment of the present invention. [Figure 8] FIG. 10 is a vertical cross-sectional view of an angular contact ball bearing according to a fourth embodiment of the present invention. [Figure 9A] FIG. 2 is a front view of the inner ring of the angular contact ball bearing, showing the filling grooves. [Figure 9B] FIG. 9B is a partially enlarged view of the main part of FIG. 9A. [Figure 10A] FIG. 10 is a vertical cross-sectional view of an angular contact ball bearing according to a fifth embodiment of the present invention. [Figure 10B] 10B is a vertical cross-sectional view of the angular contact ball bearing at a different phase from that of FIG. 10A. [Figure 11] 3 is a plan view of the retainer of the angular contact ball bearing as viewed from the axial direction. FIG. [Figure 12] FIG. 4 is a partially enlarged view showing a claw portion of the cage. [Figure 13] FIG. 4 is a perspective view of a main part of the cage, showing the positional relationship of the claw portions. [Figure 14] 3 is a longitudinal cross-sectional view illustrating a method of assembling an inner ring assembly including an inner ring, balls, and a cage of the angular contact ball bearing. FIG. [Figure 15] 10 is a longitudinal cross-sectional view of the inner ring assembly at an intermediate assembly stage. FIG. [Figure 16] 10 is a vertical cross-sectional view illustrating the function of the first row of claw portions when assembling the inner race assembly. FIG. [Figure 17] 10 is a vertical cross-sectional view illustrating the function of the second row of claw portions when assembling the inner race assembly. FIG. [Figure 18] FIG. 10 is a vertical cross-sectional view of an outer ring assembly of an angular contact ball bearing according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] [First embodiment] An angular contact ball bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 5B. This angular contact ball bearing is used, for example, as the main bearing portion of a reducer for an industrial robot or the like. Examples of the reducer include an eccentric differential reducer, a strain wave gear reducer, and a planetary gear reducer. In this specification, the angular contact ball bearing may be simply referred to as a "bearing."

[0022] <Overall structure of angular contact ball bearing> As shown in Figure 1, angular contact ball bearing 1 comprises an inner ring 2, an outer ring 3, a plurality of balls 4 interposed between the inner ring 2 and the outer ring 3, and an annular resin cage 5 in which pockets Pt for holding these balls 4 are formed. Cage 5 has a pair of annular portions 7, 8 and a plurality of column portions 6 connecting the annular portions 7, 8, and said pockets Pt are made up of the pair of annular portions 7, 8 and the column portions 6. Note that resin cage 5 may also be simply referred to as cage 5. The angular contact ball bearing 1 in this example is a type in which the outer ring 3 is separated in the axial direction.

[0023] For example, when incorporating angular contact ball bearing 1 into a reducer or the like, outer ring 3 is separated and first incorporated into a case (not shown), and inner ring 2 is incorporated into a shaft or flange (not shown). The inner ring assembly, which integrates inner ring 2, balls 4, and cage 5, is then combined with the outer ring 3 incorporated into the case, completing assembly of angular contact ball bearing 1. The inner and outer rings 2 and 3 are made of, for example, high-carbon chromium bearing steel such as SUJ2 or martensitic stainless steel. Balls 4 are made of, for example, steel balls or ceramics.

[0024] The direction along the bearing center line C1 of the angular contact ball bearing 1 or the direction parallel to the bearing center line C1 is referred to as the "axial direction." The direction perpendicular to the "axial direction" is referred to as the "radial direction." The circumferential direction around the center axis is referred to as the "circumferential direction."

[0025] The raceway surface 3a is connected to the front surface of the outer ring 3 via the inner peripheral surface. The inner peripheral surface 3d on the back surface side of the outer ring 3 is located radially inward of the inner peripheral surface on the front surface side of the outer ring 3. The raceway surface 2a is connected to the front surface of the inner ring 2 via an inner ring counterbore portion 2b. The outer peripheral surface 2d on the back surface side of the inner ring 2 is formed between the raceway surface 2a of the inner ring 2 and the back surface 2c of the inner ring 2. This outer peripheral surface 2d on the back surface side is located radially outward of the counterbore 2b, which is the outer peripheral surface on the front surface side of the inner ring 2. The front surface of the inner and outer rings 2, 3 refers to the side surface on the side that does not support an axial load, and the back surfaces 2c, 3c of the inner and outer rings 2, 3 refer to the side surface on the side that supports an axial load.

[0026] <Cage> 2 and 3C, the cage 5 is made of synthetic resin and formed into a tapered cylindrical annular shape, with pockets Pt, which are window-shaped holes that hold the balls 4, provided in the axially middle portion of the cage 5. The cage 5 holds the balls 4 in the pockets Pt. The cage 5 includes a column portion 6, a small-diameter annular portion 7, and a large-diameter annular portion 8, which are formed integrally. The phrase "formed integrally" means that the column portion 6, the small-diameter annular portion 7, and the large-diameter annular portion 8 are not formed by combining multiple elements but are molded as part or the whole of a single object from a single material by, for example, injection molding or machining.

[0027] As shown in FIG. 3B, the column portions 6 of the cage 5 are between the pockets Pt, and as shown in FIGS. 2 and 3D, they are partition walls that slope radially outward toward one side in the axial direction (the right side in FIG. 2). The inner surfaces of the column portions 6 that face the balls 4 (the shape of the pockets Pt) are formed in a partially spherical shape corresponding to the outer diameter of the balls 4. The small-diameter side annular portion 7 is an annular portion on the smaller diameter side than the pockets Pt, and its inner circumferential surface 7a is formed in a cylindrical shape. As shown in FIG. 3E, the large-diameter side annular portion 8 is an annular portion on the larger diameter side than the pockets Pt, and its outer circumferential surface 8a is formed in a cylindrical shape.

[0028] <Relationship between the base and the pitch circle diameter of the ball> As shown in Figure 2, the cage 5 has a bar relief portion Es defined in the radial cross section of Figure 2, which is a range where no bar portion 6 is provided on the pitch circle diameter dp of the balls 4. In other words, the inner diameter surface 6a of the bar portion of the cage is configured to be within a range of 8% to 50% of the ball diameter φDa from the pitch circle center P4 of the balls 4. In other words, as in the conventional cage 50 shown in Figure 3A, the circumferential bar width of the bar portions 51 is thinnest on the pitch circle diameter dp. For this reason, if the number of balls 52 (number of pockets) is increased, the bar width on the pitch circle diameter dp becomes thinner, and the strength of the thinnest part T1 of the cage bar portion decreases.

[0029] As shown in Fig. 3B, when no bar portion 6 is provided on the pitch circle diameter dp, the dimension T (hereinafter sometimes referred to as "bar width T"), which is the thinnest part of the circumferential width of the bar portion 6, can be made thicker than in the conventional example (Fig. 3A). This increases the strength of the cage 5 compared to the conventional example, and prevents contact between adjacent balls 4, 4 in the circumferential direction.

[0030] <Definition of cage post width> Assuming that the balls 4 move along the pitch circle diameter dp as shown in Figure 4, the shortest distance between the points of contact between the column portion 6 of the cage 5 and the circumferentially adjacent balls 4, 4 is defined as the column width T. Therefore, as shown in FIGS. 5A and 5B, if there is no portion with column width T in a certain range near the pitch circle diameter dp, there may be a column portion that is not in contact with the ball 4.

[0031] <t dp> As shown in FIG. 3B, the dimension T, which is the thinnest part of the circumferential width of the bar portion 6, is 0.40% to 1.50% of the pitch circle diameter dp of the balls 4. In other words, T / dp × 100 is 0.40 or more and 1.50 or less. If the ratio of the bar width T to the pitch circle diameter dp is less than 0.40%, the thinnest part will be too thin, and the strength of the bar portion 6 may be reduced compared to conventional structures. If the ratio of the bar width T to the pitch circle diameter dp is more than 1.50, the radial thickness of the cage 5 will be thin, and the strength of the entire cage may be reduced compared to conventional structures.

[0032] <Ball filling rate> The filling rate of ball 4 is between 88% and 96%. Filling rate = (ball diameter x number of balls) / (pitch circle diameter x π) By setting the packing rate of the balls 4 to between 88% and 96%, it is possible to satisfy the required rated load and prevent interference between the balls 4, 4 during operation. If the packing rate of the balls 4 is less than 88%, the number of balls is too small to satisfy the required rated load. If the packing rate of the balls 4 is more than 96%, the distance between the balls becomes too small, causing interference between the balls 4, 4 during operation.

[0033] <Action and effect> Table 1 shows the relationship between the inner diameter of the bar portion and the strength of the cage. In Table 1, an "X" in the "Strength of the bar width portion of the cage" column means that there is a problem with the strength of the bar width portion being reduced, and that the bearing usage conditions, cage material, etc. are restricted. An "O" in the "Strength of the bar width portion of the cage" column means that the desired strength of the bar width portion is met, and that there are no restrictions on the bearing usage conditions, cage material, etc. An "x" in the "Overall cage strength" column means that there is a problem of reducing the overall cage strength and that it is not feasible. An "o" in the "Overall cage strength" column means that the desired overall cage strength is met and that it is feasible.

[0034] [Table 1]

[0035] In the angular contact ball bearing 1 of FIG. 2 described above, the inner diameter surface 6a of the bar portion of the cage is in the range of 8% to 50% of the ball diameter φDa from the pitch circle center P4 of the balls 4. This allows for an increase in the number of balls while preventing a decrease in the strength of the entire cage, including the bar portion 6. If the inner diameter surface 6a of the bar portion of the cage is in the range of less than 8% of the ball diameter φDa from the pitch circle center P4 of the balls 4, the thinnest part of the circumferential column width of the bar portion 6 becomes too thin, resulting in a decrease in the strength of the bar portion 6 compared to a conventional structure. If the inner diameter surface 6a of the bar portion of the cage is in the range of more than 50% of the ball diameter φDa from the center P4 of the balls 4, the radial thickness of the cage 5 becomes thin, resulting in a decrease in the strength of the entire cage compared to a conventional structure.

[0036] If dp is the pitch circle diameter of balls 4 and T is the dimension of the thinnest part of the circumferential width of bar portion 6, T / dp × 100 is 0.40 or more and 1.50 or less. In this case, the rigidity of the thinnest part of bar portion 6 is ensured and a decrease in the strength of the entire cage can be more reliably prevented. By setting the filling rate of the balls 4 to 88% or more and 96% or less, it is possible to satisfy the required rated load and to prevent interference between the balls 4, 4 during operation.

[0037] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. It is possible to combine not only the parts specifically described in each embodiment, but also partially combine embodiments as long as there is no particular problem with the combination.

[0038] [Second embodiment] As shown in Fig. 6, the shape of the pocket Pt of the cage 5A may be a shape other than a partial spherical shape. In the example of Fig. 6, the shape of the pocket Pt is cylindrical. In the second embodiment, the inner diameter surface 6a of the column portion is in a range of 8% to 50% of the ball diameter φDa from the center of the ball 4, T / dp x 100 is 0.40 to 1.50, and the packing rate of the balls 4 is 88% to 96%. In this case, the same effects as those of the first embodiment described above are achieved.

[0039] [Third embodiment] 7, the inner circumferential surface 7a of the small diameter side annular portion 7 of the cage 5 is provided with a claw portion 9 that protrudes radially inward. This claw portion 9 is provided at one location on the axial tip of the inner circumferential surface 7a of the small diameter side annular portion 7, but the position and number of the claw portion 9 are not limited to this example.

[0040] An annular recess 10 is provided in the inner ring counterbore 2b on the outer peripheral surface of the inner ring 2. At the same time, the inner ring counterbore 2b is provided with a filling groove 11 that allows the claws 9 to pass into the bearing. The filling groove 11 is, for example, a recess with an arc-shaped cross section that extends axially in a portion of the circumferential direction of the inner ring counterbore 2b (see FIG. 9B), and is formed to facilitate the axial insertion of the claws 9 of the cage 5. The groove bottom of the filling groove 11 is formed, for example, to have the same diameter as the annular recess 10.

[0041] With this configuration, even if the cage 5 is deformed by the weight of the balls and the balls 4 undesirably climb over the inner race counterbore 2b, the claws 9 of the cage 5 will catch on the recesses 10 in the inner race counterbore 2b. This prevents the cage 5 and balls 4 from separating from the inner race 2.

[0042] [Fourth embodiment] As shown in Figures 8 and 9A, multiple filling grooves 11 (two in this example) are provided, and these multiple filling grooves 11 are arranged at equal intervals in the circumferential direction. Multiple claw portions 9 are provided so that the number is the same as the number of filling grooves 11 shown in Figure 9A. As shown in Figure 8, these multiple claw portions 9 are arranged at equal intervals in the circumferential direction. In this case, the load acting on the contact points between the claw portions 9 of the cage 5 and the recesses 10 of the inner ring 2 can be distributed evenly in the circumferential direction. This allows the cage 5 and balls 4 to be held stably.

[0043] [Fifth embodiment] 10A and 10B, the claw portions 9 may be provided in two or more rows at different positions in the axial direction. Specifically, as shown in Fig. 10A, a first row of claw portions 9 is provided at the axial tip portion of the inner circumferential surface 7a of the small diameter side annular portion 7. Furthermore, as shown in Fig. 10B, a second row of claw portions 9 is provided near the axial middle portion of the inner circumferential surface 7a of the small diameter side annular portion 7.

[0044] As shown in Fig. 11, each row has a plurality of claws 9 (two in this example), and these claws 9 are arranged at equal intervals in the circumferential direction. As shown in Figs. 12 and 13, the claws 9 in different rows are arranged at different phases in the circumferential direction. As shown in Figs. 10A and 10B, the claws 9 in the same row are arranged so that their axial positions are aligned. As shown in Fig. 11, since the claws 9 in the same row are arranged at two equal intervals in the circumferential direction, the axial positions of the claws 9, 9 at diagonal corners are the same.

[0045] <Assembly method> When assembling the inner ring assembly, the balls 4, cage 5, and inner ring 2 are assembled into a single unit, as shown in Figure 14. First, the inner ring 2 is assembled so that the claws 9 on the axially inner row of the cage 5 mesh with the filling grooves 11 in the inner ring counterbore portion 2b. As shown in Figure 15, after the first row of claws 9 (Figure 14) has passed through the filling grooves 11, the inner ring 2 or cage 5 is rotated circumferentially to bring the next row of claws 9 into engagement with the filling grooves 11. This completes the assembly of the inner ring assembly.

[0046] 16 and 17, even in the fifth embodiment, if the cage 5 is deformed by the weight of the balls and the balls 4 undesirably climb over the inner race counterbore 2b, the claws 9 of the cage 5 will catch on the recesses 10 in the inner race counterbore 2b. This prevents the cage 5 and balls 4 from separating from the inner race 2. When the inner ring 2, balls 4, and cage 5 are integrated, there may be cases where the circumferential phase of the first row of claws 9 (Fig. 16) matches the circumferential phase of the filling groove 11 (Fig. 15) in the inner ring counterbore portion 2b, causing the first row of claws 9 to pass through the filling groove 11 (Fig. 15). Even in this case, the second row of claws 9 (Fig. 17) will catch on the recesses 10 of the inner ring 2, preventing the inner ring 2, balls 4, and cage 5 from separating.

[0047] [Sixth embodiment] In the case of an outer ring assembly in which the outer ring 3, balls 4, and cage 5 are integrated as shown in Figure 18, an annular recess 10A is provided in the outer ring counterbore 3b on the inner peripheral surface of the outer ring 3. At the same time, claws 9A that protrude radially outward are provided on the outer peripheral surface 8a of the large-diameter annular portion 8 of the cage 5. Furthermore, filling grooves 11A are provided in the outer ring counterbore 3b to allow the claws 9A to pass through into the bearing. In this case, even if the weight of the balls causes the cage 5 to deform and the balls 4 to undesirably climb over the outer race counterbore 3b, the claws 9A of the cage 5 will catch on the recesses 10A in the outer race counterbore 3b, preventing the cage 5 and balls 4 from separating from the outer race 3. In Figure 18, the outer diameter surface 6b of the bar portion of the cage is in a range of 8% to 50% of the ball diameter from the pitch circle center of the balls 4. This allows for an increase in the number of balls while preventing a decrease in the strength of the entire cage, including the bar portions 6. If the outer diameter surface 6b of the bar portion of the cage is in a range less than 8% of the ball diameter φDa from the pitch circle center P4 of the balls 4, the thinnest part of the circumferential column width of the bar portions 6 becomes too thin, resulting in a decrease in the strength of the bar portions 6 compared to conventional structures. If the inner diameter surface 6b of the bar portion of the cage is in a range more than 50% of the ball diameter φDa from the pitch circle center P4 of the balls 4, the radial thickness of the cage 5 becomes thinner, resulting in a decrease in the strength of the entire cage compared to conventional structures.

[0048] Generally, angular contact ball bearings are mounted on a shaft and a housing, but the features of the cage and inner ring described in each embodiment can also be applied to configurations in which the inner ring and shaft, and the outer ring and housing are integrated.

[0049] In addition, in order to satisfy the required moment rigidity, it is possible to increase the ball size and contact angle, but in this case, the load bearing location on the bearing ring changes due to the increase in ball size and contact angle. Therefore, when applying preload in applications such as reducers, it is necessary to support the bearing at the shaft shoulder, so it is preferable that the outer diameter of the shaft or flange into which the inner ring is installed is larger than the outer diameter of the inner ring, and that the inner diameter of the case into which the outer ring is installed is smaller than the inner diameter of the outer ring. Also, when applying preload with an inner shim, it is preferable to use an inner shim with an outer diameter larger than the outer diameter of the inner ring, and to apply a fixed-position preload. Furthermore, when the ball size is increased, it becomes difficult to attach a seal to the bearing due to dimensional constraints. When the main bearing is used with grease or oil lubrication, a shaft seal must be installed on the axial outside of the bearing.

[0050] Moment loads are often applied to industrial machinery. Under operating conditions where moment loads are applied by angular contact ball bearings, arranging angular contact ball bearings in a back-to-back configuration increases the distance between the bearing's application points, allowing for larger allowable radial and moment loads even when the angular contact ball bearings are made smaller or more compact. Furthermore, by arranging angular contact ball bearings in a back-to-back configuration, they can withstand axial loads in both directions, and the addition of preload increases the rigidity of the bearing section.

[0051] Between axially adjacent angular contact ball bearings, angular contact ball bearings may be assembled back-to-back via inner ring spacers and outer ring spacers, or these inner ring spacers and outer ring spacers may be omitted and angular contact ball bearings may be assembled back-to-back.

[0052] Angular contact ball bearings can also be used in face-to-face or parallel combinations. Angular contact ball bearings can also be used for applications other than industrial robots.

[0053] Although the embodiments of the present invention have been described above, the disclosed embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0054] 1...angular contact ball bearing, 2...inner ring, 2b...inner ring counterbore portion, 3...outer ring, 3b...outer ring counterbore portion, 4...ball, 5, 5A...retainer, 6...pillar portion, 6a...pillar portion inner diameter surface, 6b...pillar portion outer diameter surface, 9, 9A...claw portion, 10, 10A...recess, 11, 11A...filling groove, Es...pillar portion relief portion< / t>

Claims

1. An angular contact ball bearing comprising an inner ring, an outer ring, a plurality of balls interposed between the inner ring and the outer ring, and an annular resin cage that holds the balls, the cage having a pair of annular portions and a plurality of column portions connecting the annular portions, and having pockets formed by the annular portions and the column portions, the pockets holding the balls, The retainer is an angular contact ball bearing characterized in that, in a radial cross section, the column portion does not overlap with the pitch circle center of the ball, and the shortest distance from the pitch circle center of the ball to the column portion is 8% or more and 50% or less of the ball diameter.

2. 2. The angular ball bearing according to claim 1, wherein, when the pitch circle diameter dp of the ball is defined as the pitch circle diameter of the ball and the dimension T of the thinnest part of the column width in the circumferential direction of the column portion, T / dp x 100 is 0.40 or more and 1.50 or less.

3. 3. The angular contact ball bearing according to claim 2, wherein the ball packing ratio is 88% or more and 96% or less.

4. 4. The angular contact ball bearing according to claim 3, wherein the inner peripheral surface of the retainer is provided with claw portions that protrude radially inward, and the inner ring counterbore portion on the outer peripheral surface of the inner ring is provided with an annular recess and an insertion groove that allows the claw portions to pass into the bearing.

5. 4. The angular contact ball bearing according to claim 3, wherein the outer peripheral surface of the retainer is provided with claw portions that protrude radially outward, and the outer ring counterbore portion on the inner peripheral surface of the outer ring is provided with an annular recess and an insertion groove that allows the claw portions to pass into the bearing.

6. 5. The angular ball bearing according to claim 4, wherein a plurality of said filling grooves are provided, and said plurality of filling grooves are provided at equal intervals in the circumferential direction.

7. 7. The angular ball bearing according to claim 6, wherein a plurality of said claw portions are provided, and said plurality of claw portions are provided at equal intervals in the circumferential direction.

8. 8. The angular contact ball bearing according to claim 7, wherein the claw portions are provided in two or more rows at different positions in the axial direction, and the claw portions in different rows are arranged at different phases in the circumferential direction.

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