Angular ball bearing

Abstract

An angular ball bearing (1) comprises: an inner ring (2); an outer ring (3); a plurality of balls (4); and a holder (5). The holder (5) has a small annular part (6) that is positioned between a counter bore part (2b) of the inner ring (2) and a shoulder part (3d) of the outer ring (3) in the radial direction, a large annular part (7) that is positioned between a counter bore part (3d) of the outer ring (3) and a shoulder part (2d) of the inner ring (2) in the radial direction, and columns (8) that are provided at a plurality of places in the circumferential direction and connect the small annular part (6) and the large annular part (7). A pocket (Pt) for holding the balls (4) is formed by the small annular part (6), the large annular part (7), and the columns (8). When the thickness of the small annular part (6) in the radial direction is denoted by (T1), the thickness of the large annular part (7) in the radial direction is denoted by (T2), and the diameter of each of the balls (4) is denoted by (Da), 0.170≤T1 / Da≤0.280, 0.170≤T2 / Da≤ 0.280, and 0.90≤T1 / T2≤0.10 are satisfied.

Description

Angular contact ball bearings Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2023-200059, filed November 27, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to an angular contact ball bearing used in, for example, compressors, pumps, injection molding machines, etc.

[0003] Patent Document 1 discloses an angular contact ball bearing that does not generate abnormal noise, vibration, or temperature rise and satisfies relationships defined in relation to the internal design of the bearing.

[0004] Japanese Patent Application Laid-Open No. 2022-24610

[0005] Angular contact ball bearings used in compressors, pumps, injection molding machines, etc. are required to have a high load capacity and high rotation speed. In conventional angular contact ball bearings, the pocket clearance A of the cage 50 is controlled as shown in Figure 5 to prevent abnormal noise, vibration, and temperature rise. However, when angular contact ball bearings are used with a large load capacity and at high rotation speed, the cage is also subjected to load, so the cage must have a certain level of strength.

[0006] An object of the present invention is to provide an angular contact ball bearing having a longer life by ensuring a certain level of cage strength even under high load capacity and high speed rotation.

[0007] The angular contact ball bearing of the present invention is an angular contact ball bearing comprising an inner ring and an outer ring each having a counterbore portion, a plurality of balls interposed between the inner ring and the outer ring, and a cage that holds the balls, wherein the cage has a small annular portion located radially between the counterbore portion of the inner ring and a shoulder portion of the outer ring, a large annular portion located radially between the counterbore portion of the outer ring and the shoulder portion of the inner ring, and pillar portions that connect the small annular portion and the large annular portion and are provided at a plurality of locations in the circumferential direction, and wherein the small annular portion, large annular portion, and pillar portions form pockets that hold the plurality of balls, wherein, when the radial thickness of the small annular portion is T1, the radial thickness of the large annular portion is T2, and the diameter of the balls is Da, the following relationships hold: 0.170≦T1 / Da≦0.280 0.170≦T2 / Da≦0.280 The relationship 0.90≦T1 / T2≦1.10 is satisfied. T1 refers to the radial thickness of the axially outer portion of the small annular portion. T2 refers to the radial thickness of the axially outer portion of the large annular portion. The shoulder of the outer ring is the inner peripheral portion on the back surface side of the outer ring. The shoulder of the inner ring is the outer peripheral portion on the back surface side of the inner ring.

[0008] According to this configuration, for a cage with a so-called asymmetric cross section, T1 / Da, which is the radial thickness T1 of the small annular portion divided by the diameter Da of the balls, and T2 / Da, which is the radial thickness T2 of the large annular portion divided by the diameter Da of the balls, are set within the above-mentioned ranges. This ensures a certain level of cage strength and prevents interference between the cage and at least one of the inner and outer rings. Furthermore, by controlling T1 / T2, which is the radial thickness T1 of the small annular portion divided by the radial thickness T2 of the large annular portion, within the above-mentioned range, the thicknesses of the small annular portion and the large annular portion are balanced, thereby suppressing cage whirling during high-speed rotation. Therefore, even under high load capacity and high-speed rotation, the cage strength can be ensured to a certain level, resulting in an angular contact ball bearing with a longer life.

[0009] When the contact angle is 30 degrees or greater and 45 degrees or less, the outer diameter of the outer ring is D, and the inner diameter of the inner ring is d, the following relationship may hold: 0.62≦2Da / (D−d)≦0.80 When the contact angle is 30 degrees or greater and 45 degrees or less, a higher load capacity can be achieved than with angular contact ball bearings with contact angles of, for example, 15 degrees or 25 degrees. Furthermore, based on the above relationship, balls are used that have a diameter Da that is relatively large compared to the outer diameter D of the outer ring and the inner diameter d of the inner ring. This allows for an even higher load capacity than angular contact ball bearings.

[0010] When the axial center axis of the entire angular contact ball bearing and the axial center axis of the cage are aligned, the radial clearance between the ball surface and the surface of the cage facing the balls is defined as A, and the pitch circle diameter of the balls is defined as PCD, the following relationships may be established: A / Da≦0.020 2A / PCD≦0.010

[0011] In this case, by appropriately adjusting the clearance A relative to the ball diameter Da and pitch circle diameter PCD, the amount of cage movement during operation of the angular contact ball bearing is appropriate. This ensures cage stability during bearing operation. When the clearance A is controlled as described above, the occurrence of speed differences between the inner and outer rings and the balls is suppressed. This is because the rotation of the balls is not suppressed and the ball rotation speed does not decrease. As a result, the occurrence of abnormal noise, vibration, and temperature rises between the inner and outer rings and the balls due to speed differences between the inner and outer rings and the balls can be stably suppressed.

[0012] When the column width, which is the circumferential width of the column portion, is T3 and the pitch circle diameter of the balls is PCD, the following relationship may hold: 0.01≦T3 / PCD≦0.05 If T3 / PCD, obtained by dividing the column width T3 by the pitch circle diameter PCD, is less than 0.01, the strength of the cage may be insufficient. If T3 / PCD is greater than 0.05, the load capacity may be reduced. By keeping T3 / PCD within the above range, the strength of the cage is ensured, and an angular contact ball bearing can be obtained without reducing the ball diameter or the number of balls.

[0013] Any combination of at least two features disclosed in the claims and / or the specification and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

[0014] The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present invention. The scope of the present invention is defined by the accompanying claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts. Figure 1 is a longitudinal sectional view of an angular contact ball bearing according to a first embodiment of the present invention. Figure 2 is a perspective view of a cage of the angular contact ball bearing. Figure 3 is an enlarged sectional view of a main part of the cage. Figure 4 is a partial sectional view of the cage cut along a plane perpendicular to the axial direction. Figure 5 is a partially enlarged sectional view of a cage in a conventional angular contact ball bearing.

[0015] [First Embodiment] An angular contact ball bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 4. This angular contact ball bearing is used in, for example, compressors, pumps, injection molding machines, etc. However, the angular contact ball bearing is not limited to these applications and can be applied to various industrial machines, etc. In this specification, the angular contact ball bearing may sometimes be simply referred to as a "bearing."

[0016] 1 , an angular contact ball bearing 1 comprises an inner ring 2 and an outer ring 3 which are raceway rings, a plurality of balls 4 interposed between a raceway surface 2a of the inner ring 2 and a raceway surface 3a of the outer ring 3, and a cage 5 formed with pockets Pt which hold these balls 4. A contact angle α is formed between the raceway surfaces 2a, 3a of the inner and outer rings 2, 3.

[0017] The inner and outer rings 2, 3 are made of, for example, high-carbon chromium bearing steel such as SUJ2 or martensitic stainless steel. The balls 4 are made of, for example, steel balls or ceramics. The cage 5 is formed in an annular shape from, for example, nylon, PPS, PEEK, or a resin such as phenolic resin reinforced with, for example, glass fiber or carbon fiber. In this specification, the "axial direction" refers to the direction along the bearing center line AX of the angular contact ball bearing 1. The "radial direction" refers to the direction perpendicular to the line that forms the "axial direction."

[0018] The raceway surface 3a is connected to the front surface of the outer ring 3 via a counterbore portion 3b, which will be described later. The front surface of the outer ring 3 represents the side surface that does not support an axial load. The back surface 3c of the outer ring 3 represents the side surface that supports an axial load. A shoulder 3d, which is the inner circumferential surface on the back surface side of the outer ring 3, is located radially inward from the counterbore portion 3b of the outer ring 3. The raceway surface 2a is connected to the front surface of the inner ring 2 via a counterbore portion 2b, which will be described later. The front surface of the inner ring 2 represents the side surface that does not support an axial load. The back surface 2c of the inner ring 2 represents the side surface that supports an axial load. The inner circumferential surface on the back surface side of the inner ring 2 is called the shoulder 2d. The shoulder 2d is formed between the raceway surface 2a of the inner ring 2 and the back surface 2c of the inner ring 2. The shoulder 2d of the inner ring 2 is located radially outward from the counterbore portion 2b of the inner ring 2.

[0019] The shoulder 3d of the outer ring 3 is formed into a cylindrical surface shape parallel to the axial direction. The counterbore 3b of the outer ring 3 is formed into a cylindrical surface or tapered surface shape formed radially outward from the shoulder 3d with a diameter larger by a predetermined dimension, and is also referred to as the "shoulder-dropped portion" of the outer ring 3. The tapered surface is a tapered surface that slopes radially inward from the front side of the outer ring toward the raceway surface 3a. The shoulder 2d of the inner ring 2 is formed into a cylindrical surface shape parallel to the axial direction. The counterbore 2b of the inner ring 2 is formed into a cylindrical surface or tapered surface shape formed radially inward from the shoulder 2d with a diameter smaller by a predetermined dimension, and is also referred to as the "shoulder-dropped portion" of the inner ring 2. The tapered surface is a tapered surface that slopes radially outward from the front side of the inner ring toward the raceway surface 2a.

[0020] <Regarding the Cage> As shown in Figures 2 and 3, the cage 5 has small annular portions 6, large annular portions 7, and pillar portions 8. This cage 5 is independently tradeable in the market. As shown in Figure 1, the small annular portions 6 are fitted between the counterbore portion 2b of the inner ring 2 and the shoulder portion 3d of the outer ring 3. The large annular portions 7 are fitted between the counterbore portion 3b of the outer ring 3 and the shoulder portion 2d of the inner ring 2. As shown in Figure 3, the large annular portions 7 are located radially outward of the small annular portions 6. The pillar portions 8 connect the small annular portions 6 and the large annular portions 7 and are provided at multiple locations in the circumferential direction.

[0021] The small annular portion 6, the large annular portion 7, and the pillar portion 8 form a pocket Pt that holds multiple balls 4. The small annular portion 6, the large annular portion 7, and the pillar portion 8 are integrally formed. "Integrated" means that the small annular portion 6, the large annular portion 7, and the pillar portion 8 are not formed by combining multiple elements, but are molded from a single material by, for example, injection molding, as part or the whole of a single object.

[0022] The column portion 8 has an inner diameter side column portion 8a and an outer diameter side column portion 8b. The inner diameter side column portion 8a extends between the small annular portion 6 and the large annular portion 7, generally along the axial direction, from the small annular portion 6 toward the large annular portion 7. The outer diameter side column portion 8b extends between the small annular portion 6 and the large annular portion 7, generally along the axial direction, from the large annular portion 7 toward the small annular portion 6. The inner diameter side column portion 8a has a first inclined surface 8c formed on its large annular portion side, that is, on the right side in Figure 3 . The first inclined surface 8c is an inclined surface that inclines radially outward as it approaches the front surface of the bearing and reaches the large annular portion 7.

[0023] 1 , the small annular portion 6 has a first inner peripheral surface 6 a and a first outer peripheral surface 6 b. The first inner peripheral surface 6 a is the surface of the small annular portion 6 that is closest to the inner ring 2. The first outer peripheral surface 6 b is the surface of the small annular portion 6 that is closest to the outer ring 3, and is located radially inward of the pitch circle diameter PCD of the balls 4.

[0024] The large annular portion 7 has a second inner circumferential surface 7a and a second outer circumferential surface 7b. The second inner circumferential surface 7a is the surface of the large annular portion 7 closest to the inner ring 2 and is located radially outward of the pitch circle diameter PCD of the balls 4. The second outer circumferential surface 7b is the surface of the large annular portion 7 closest to the outer ring 3. As shown in FIG. 3 , the first inclined surface 8c connects from an end P1 on the large annular portion side, which is flush with the first inner circumferential surface 6a, to the second inner circumferential surface 7a of the large annular portion 7. The outer diameter side column portion 8b has a second inclined surface 8d that slopes radially outward toward the front surface of the bearing and reaches the large annular portion 7.

[0025] <Parameters and Effects> From the results of the step-up test described later for the above-mentioned angular contact ball bearing, it was found that when the radial thickness of the small annular portion 6 is T1, the radial thickness of the large annular portion 7 is T2, and the diameter of the balls 4 is Da, if the following formulas (1), (2), and (3) are all satisfied, the strength of the cage 5 is ensured to a certain level even under high load capacity and high speed rotation, and the raceways and the cage 5 do not interfere with each other. Note that the high load capacity and high speed rotation are determined appropriately depending on the application and conditions of use of the angular contact ball bearing. 0.170≦T1 / Da≦0.280 ...formula (1) 0.170≦T2 / Da≦0.280 ...formula (2) 0.90≦T1 / T2≦1.10 ...formula (3)

[0026] For a cage with a so-called asymmetric cross section, T1 / Da, which is the radial thickness T1 of the small annular portion 6 divided by the diameter Da of the balls 4, and T2 / Da, which is the radial thickness T2 of the large annular portion 7 divided by the diameter Da of the balls 4, are set within the ranges of the above-mentioned formulas (1) and (2). This ensures a certain level of strength for the cage 5 and prevents interference between the cage 5 and at least one of the inner and outer raceways. Furthermore, by controlling T1 / T2, which is the radial thickness T1 of the small annular portion 6 divided by the radial thickness T2 of the large annular portion 7, within the range of the above-mentioned formula (3), the balance between the thicknesses of the small annular portion 6 and the large annular portion 7 can be maintained, thereby suppressing whirling of the cage 5 during high-speed rotation. Therefore, even under high load capacity and high-speed rotation, the strength of the cage 5 can be ensured to a certain level, resulting in an angular contact ball bearing with a longer life.

[0027] As shown in Figure 1, in the angular contact ball bearing 1, when the contact angle α is 30 degrees or greater and 45 degrees or less, the outer diameter of the outer ring 3 is D, and the inner diameter of the inner ring 2 is d, it is preferable that the following relationship (4) hold: 0.62≦2Da / (D-d)≦0.80 ...Equation (4) When the contact angle α is 30 degrees or greater and 45 degrees or less, a higher load capacity can be achieved than in angular contact ball bearings with contact angles α of, for example, 15 degrees or 25 degrees. Furthermore, based on the above relationship (4), balls 4 are used that have a diameter Da that is relatively large compared to the outer diameter D of the outer ring 2 and the inner diameter d of the inner ring 2. This allows the angular contact ball bearing 1 to have an even higher load capacity.

[0028] In the angular contact ball bearing 1, when the axial center axis of the entire angular contact ball bearing and the axial center axis A5 (FIG. 3) of the cage 5 are aligned, the radial clearance between the ball surface and the surface of the pocket Pt of the cage 5 facing the balls 4 is A, and the pitch circle diameter of the balls 4 is PCD, it is preferable that the following relationship formulas (5) and (6) hold true: A / Da≦0.020 (formula (5)) 2A / PCD≦0.010 (formula (6))

[0029] In this case, by appropriately adjusting the clearance A relative to the diameter Da and pitch circle diameter PCD of the balls 4, the amount of movement of the cage 5 during operation of the angular contact ball bearing 1 is appropriate. This ensures the stability of the cage 5 during bearing operation. When the clearance A is controlled as described above, the occurrence of a speed difference between the inner ring 2 / outer ring 3 and the balls 4 is suppressed. This is because the rotation of the balls 4 is not suppressed and the rotational speed of the balls 4 does not decrease. As a result, the occurrence of abnormal noise, vibration, and temperature rises that occur between the inner ring 2 / outer ring 3 and the balls 4 due to the speed difference between the inner ring 2 / outer ring 3 and the balls 4 can be stably suppressed.

[0030] As shown in Figure 4, in the angular contact ball bearing, when the column width, which is the circumferential width of the column portion, is T3 and the pitch circle diameter of the balls 4 is PCD, it is preferable that the following relational expression (7) be established: 0.01≦T3 / PCD≦0.05 ...Equation (7) If T3 / PCD, obtained by dividing the column width T3 by the pitch circle diameter PCD, is less than 0.01, the strength of the cage 5 may be insufficient. If T3 / PCD is more than 0.05, the load capacity may be reduced. By keeping T3 / PCD within the above range, the strength of the cage 5 is ensured, and an angular contact ball bearing can be obtained without reducing the ball diameter or the number of balls.

[0031] <Step-up test> A step-up test was conducted on the allowable rotational speed of the example and comparative example. 1. Test bearings - Model number 7308B equivalent (inner diameter φ40 mm x outer diameter φ90 mm x width 23 mm, contact angle 40°) For both the example and comparative example, a duplex angular contact ball bearing was used, with 7308B mated back to back. - Model number 7210B equivalent (inner diameter φ50 mm x outer diameter φ90 mm x width 20 mm, contact angle 40°) For both the example and comparative example, a duplex angular contact ball bearing was used, with 7210B mated back to back.

[0032] 2. Test conditions Preload: Back-to-back combination, constant preload 2kN Lubrication: Circulating oil supply, grease Rotational speed: 2000-10000min －１ (1000 min －１ (Step up each time) Test stop: Until the temperature of the outer ring (fixed ring) reaches 70°C Operating time: Circulating oil supply...20 min each, grease...60 min each 3. Test results In the comparative example and example, operation was possible without abnormal noise, temperature rise, or abnormal heat generation. For the model equivalent to 7308B, the example generated less heat than the comparative example, achieving a 10% improvement in allowable rotation speed compared to the comparative example.

[0033] The relationship between the ratios of T1 / Da and T2 / Da, the strength of the cage, and the interference with the raceway is shown in Table 1 below.

[0034] In Table 1, in the column for insufficient cage strength, ◯ indicates that the cage strength is ensured, △ indicates that there is a problem with the cage strength, and × indicates that the cage strength is insufficient. In the column for interference with the raceway, ◯ indicates that the cage and raceway do not interfere, △ indicates that there is a risk of interference between the cage and raceway, and × indicates that the cage and raceway interfere. According to Table 1, if T1 / Da or T2 / Da is less than 0.170, there is a concern that the cage may have insufficient strength. If T1 / Da or T2 / Da is greater than 0.280, there is a concern that the cage may interfere with the raceway.

[0035] The relationship between T3 / PCD and the strength and load capacity reduction of the cage is shown in Table 2 below.

[0036] In Table 2, in the column for insufficient cage strength, ◯ indicates that the cage strength is ensured, △ indicates that there is a problem with the cage strength, and × indicates that the cage strength is insufficient. In the column for reduced load capacity, ◯ indicates that the cage has sufficient load capacity, △ indicates that it is feasible although there is a concern that the load capacity may be reduced, and × indicates that the load capacity will be reduced. According to Table 2, when T3 / PCD is less than 0.01, there is a concern that the cage strength may be insufficient. When T3 / PCD is more than 0.05, there is a concern that the ball diameter or the number of balls will need to be reduced, which will reduce the load capacity.

[0037] 1 can be used not only in back-to-back arrangement, but also in face-to-face arrangement and parallel arrangement, and can also be used in a single row. The cage 5 may be formed by a combination of injection molding and machining, or it can also be formed using a 3D printer or the like.

[0038] As described above, the preferred embodiment has been described with reference to the drawings, but various additions, modifications, and deletions can be made without departing from the spirit of the present invention. Therefore, such additions, modifications, and deletions are also included in the scope of the present invention.

[0039] DESCRIPTION OF SYMBOLS 1...Angular contact ball bearing 2...Inner ring 2b...Counterbore portion 2d...Shoulder portion 3...Outer ring 3b...Counterbore portion 3d...Shoulder portion 4...Ball 5...Cage 6...Small annular portion 7...Large annular portion 8...Column portion Pt...Pocket α...Contact angle PCD...Pitch circle diameter

Claims

1. An angular contact ball bearing comprising an inner ring and an outer ring each having a counterbore portion, a plurality of balls interposed between the inner ring and the outer ring, and a retainer for retaining the balls, wherein the retainer has a small annular portion located radially between the counterbore portion of the inner ring and a shoulder portion of the outer ring, a large annular portion located radially between the counterbore portion of the outer ring and a shoulder portion of the inner ring, and pillar portions connecting the small annular portion and the large annular portion and provided at a plurality of positions in the circumferential direction, wherein the small annular portion, the large annular portion and the pillar portions form pockets for retaining the plurality of balls, wherein: 0.170≦T1 / Da≦0.280 0.170≦T2 / Da≦0.280, where T1 is the radial thickness of the small annular portion, T2 is the radial thickness of the large annular portion and Da is the diameter of the balls. An angular contact ball bearing that satisfies 0.90≦T1 / T2≦1.

10.

2. The angular contact ball bearing according to claim 1, wherein the contact angle is between 30 degrees and 45 degrees, the outer diameter of the outer ring is D, and the inner diameter of the inner ring is d, and the following relationship holds: 0.62≦2Da / (D-d)≦0.80 3. An angular contact ball bearing as claimed in claim 1 or 2, in which the following relationship holds when the radial clearance between the ball surface and the surface of the cage pocket facing the balls in a state in which the axial center axis of the entire angular contact ball bearing and the axial center axis of the cage are aligned is A and the pitch circle diameter of the balls is PCD: A / Da≦0.020 2A / PCD≦0.010 4. In the angular contact ball bearing according to claim 1, when the circumferential width of the column portion is T3 and the pitch circle diameter of the ball is PCD, the following relationship is established: 0.01≦T3 / PCD≦0.05.

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