Angular ball bearing

Abstract

To provide an angular ball bearing capable of reducing the cost without impairing the incorporation property even if it is a full type one with no cage.SOLUTION: An angular ball bearing 1 is an angular ball beating with no cage which includes an inner ring 2 and an outer ring 3, and a plurality of balls 4 laid between the inner ring 2 and the outer ring 3. Herein, a jig 15 is provided for holding the plurality of balls 4 integrally with the inner ring 2. The jig 15 is attachable / detachable to / from the plurality of balls 4 and the inner ring 2. In the jig 15, pockets are provided for holding the respective balls 4. A radial pocket clearance between each of the balls 4 and the jig 15 is smaller than the counter height of the inner ring 2. The jig 15 is L-shaped in cross section with a cylindrical part where the pockets are formed, and an annular rising plate part linked to the axial base edge of the cylindrical part.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Eccentric oscillating reduction gears are generally known for use in the joints of industrial robots, etc. In order to meet the requirements for moment rigidity and long life, full-ball angular contact ball bearings are used in a back-to-back configuration for the main bearings of the reduction gears (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-92686 A [Patent Document 2] Japanese Patent Application Publication No. 9-119440 Summary of the Invention [Problem to be solved by the invention]

[0004] In order to meet the requirements for moment rigidity and long life, full-ball angular contact ball bearings are used in reducers. When installing angular contact ball bearings in reducers, the outer ring may be separated and first installed in the case, and the inner ring may be installed on the shaft or flange, and then combined with the outer ring installed in the case. In this case, with full-ball types, it is necessary to ensure that the balls do not come off the inner ring when the outer ring is separated.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an angular contact ball bearing which is a full ball type without a cage and which allows for cost reduction without impairing ease of installation. [Means for solving the problem]

[0006] The angular contact ball bearing of the present invention is a cageless angular contact ball bearing including an inner ring, an outer ring, and a plurality of balls interposed between the inner ring and the outer ring, A jig is provided that holds the plurality of balls integrally with the inner ring, and the jig is detachable from the plurality of balls and the inner ring.

[0007] According to this configuration, a jig is provided for holding the balls integrally with the inner ring in an angular contact ball bearing without a cage, so that assembly can be performed in the same way as with a separate outer ring type bearing. In other words, the outer ring is separated from the angular contact ball bearing and first assembled into the case, and the inner ring is assembled together with the jig and the balls onto a shaft or flange, etc., and then combined with the outer ring assembled into the case. The jig makes it possible to assemble the bearing without the balls coming off the inner ring undesirably. The jig can be attached and detached to the multiple balls and inner rings, so after the bearing is assembled, the jig can be removed and the bearing can be used as a full-ball angular contact ball bearing without a cage during operation. Because the jig can be removed during operation and used repeatedly, costs can be reduced compared to angular contact ball bearings with cages.

[0008] It is desirable that the jig is provided with pockets for holding each of the balls, and that the radial pocket clearance between the balls and the jig is smaller than the counter height of the inner ring. In this case, the balls will not ride up onto the counter of the inner ring, so the inner ring, balls and jig will not separate, making it easier to assemble the jig into the device or other object to be assembled.

[0009] The jig may be configured with an L-shaped cross section, with a cylindrical portion in which the pocket is formed, and an annular upright portion connected to the axial base end edge of the cylindrical portion. By forming the jig in this manner with a relatively simple L-shaped cross section, it is possible to reduce the manufacturing cost of the jig itself.

[0010] The jig may have a pocket forming portion in which one pocket is formed and a pocket forming portion in which another pocket adjacent to the first pocket in the circumferential direction is formed, and a slit opening to the rear surface side of the bearing may be provided between these circumferentially adjacent pocket forming portions. In this case, the jig can be easily pulled out to the front surface side of the bearing by utilizing the location where the slit is provided.

[0011] The jig may have an annular holding portion that is held on the outer circumferential surface of the inner ring, and the holding portion may have an interference with the outer circumferential surface of the inner ring. In this case, the plurality of balls and the inner ring can be more reliably integrated.

[0012] The jig may have an annular retaining portion that is retained on the outer peripheral surface of the inner ring, the portion of this retaining portion that contacts the outer peripheral surface of the inner ring being made of a resin material or a rubber material, and the portion of the jig other than the portion that contacts the outer peripheral surface of the inner ring being made of an iron plate or a resin material. In this way, because the portion of the retaining portion of the jig that contacts the outer peripheral surface of the inner ring is made of a resin material or a rubber material, damage to the outer peripheral surface of the inner ring is suppressed and the jig is easy to attach and detach.

[0013] The value (Dj-dp) / Da obtained by subtracting the pitch circle diameter dp of the balls from the outer diameter dimension Dj of the jig and dividing the result by the diameter Da of the balls may be 0.70 or more and 0.95 or less. In this case, it is possible to prevent the strength of the jig from decreasing, and to prevent the jig from interfering with the outer ring raceway surface and thus from damaging the outer ring raceway surface during assembly. If (Dj-dp) / Da is less than 0.70, the column width between the pockets of the jig becomes small, thereby reducing the strength of the jig. If (Dj-dp) / Da is more than 0.95, the jig interferes with the outer ring raceway surface, which may cause damage to the outer ring raceway surface during assembly. Effect of the Invention

[0014] The angular contact ball bearing of the present invention is a cage-less angular contact ball bearing that is provided with a jig that holds the balls integrally with the inner ring, and this jig is detachable from the balls and the inner ring. Therefore, even if it is a full ball type, it does not use a cage, and installation is not impaired, allowing costs to be reduced. [Brief description of the drawings]

[0015] [Figure 1] 1 is a vertical sectional view of an angular ball bearing according to a first embodiment of the present invention. [Diagram 2] 4 is a cross-sectional view of bearing components, etc., in a state where the outer ring of the angular ball bearing is separated. FIG. [Diagram 3] 3 is a plan view of a main part of the jig in FIG. 2(b) as viewed from the outer diameter side. [Figure 4] This is a view taken along line IV-IV in Figure 2(b). [Figure 5A] FIG. 3 is a partially enlarged view of FIG. 2(b) showing the relationship between the pocket clearance of the jig and the inner ring counter height. [Figure 5B] 5B is a partially enlarged view of a modified example in which the pocket shape of FIG. 5A is partially changed. FIG. [Figure 6] FIG. 4 is a vertical cross-sectional view showing an example of a back-to-back assembly of the angular ball bearings. [Figure 7A] FIG. 4 is a vertical sectional view of an angular contact ball bearing according to a second embodiment of the present invention. [Figure 7B] 7B is a plan view of a main part of the jig in FIG. 7A as viewed from the outer diameter side. [Figure 8A] FIG. 11 is a vertical sectional view of an angular contact ball bearing according to a third embodiment of the present invention. [Figure 8B] 8B is a plan view of a main part of the jig in FIG. 8A as viewed from the outer diameter side. [Figure 8C] FIG. 8B is a partially enlarged view of part VIII in FIG. 8A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [First embodiment] An angular ball bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 5A. This angular ball bearing is used, for example, as a main bearing of a reduction gear used in the joints of industrial robots. In this specification, the angular ball bearing may be simply referred to as a "bearing".

[0017] As shown in FIG. 1, the angular ball bearing 1 includes an inner ring 2, an outer ring 3, and a number of balls 4 interposed between the raceway surfaces 2a, 3a of the inner and outer rings 2, 3, and is a full-ball type without a cage in which the outer ring 3 is separate, as shown in FIG. 2(a) and (b). In this specification, the full-ball type angular ball bearing 1 refers to one in which the filling rate of the balls 4, which will be described later, is 95% or more. Therefore, as Comparative Example 2, which will be described later, there is a full-ball type angular ball bearing with a cage. 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. In this specification, the "axial direction" refers to the direction along the bearing center line C1 of the angular ball bearing 1 shown in Figure 1. The "radial direction" refers to the direction perpendicular to the straight line that forms the "axial direction".

[0018] As shown in Fig. 2(a) and (b), 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 side of the outer ring 3 is located radially inward from the inner peripheral surface on the front side of the outer ring 3. The raceway surface 2a is connected to the front surface of the inner ring 2 via the counter 2b. The counter 2b is also called the counterbore 2b. Between the raceway surface 2a of the inner ring 2 and the back surface 2c of the inner ring 2, the outer peripheral surface 2d on the back side of the inner ring 2 is formed. The outer peripheral surface 2d of the inner ring 2 is located radially outward from the counterbore 2b of the inner ring 2. As shown in Fig. 1, the front surface of the inner and outer rings 2 and 3 refers to the side surface that does not support the axial load, and the back surfaces 2c and 3c of the inner and outer rings 2 and 3 refer to the side surface that supports the axial load.

[0019] <About the jig> This angular ball bearing 1 is provided with a jig 15 that holds the balls 4 integrally with the inner ring 2. The jig 15 is detachable from the side of the bearing with respect to the balls 4 and the inner ring 2. The jig 15 is provided with pockets Pt shown in FIG. 3 that hold the balls 4. The pockets Pt are formed in an arc shape that opens to the rear side of the bearing, as shown in FIG. 3 when the jig 15 is viewed from the outer diameter side. As shown in FIG. 2(b), the jig 15 is configured with an L-shaped cross section, including a cylindrical portion 16 that is a pocket forming portion in which the pockets Pt are formed, and a standing plate portion 17 that is an annular holding portion. The standing plate portion 17 is connected to the axial base end edge portion of the cylindrical portion 16. As shown in FIG. 2(b) and FIG. 3, the cross section of the pocket Pt of the cylindrical portion 16 cut along a plane including the axial direction is a partially spherical shape that follows the spherical surface of the balls 4.

[0020] 3 and 4, the jig 15 has a pocket forming portion 16 in which one pocket Pt is formed, and a pocket forming portion 16 in which another pocket Pt adjacent to the one pocket Pt in the circumferential direction is formed. As shown in Fig. 3, the jig 15 has a slit SL that opens to the back surface side of the bearing between these circumferentially adjacent pocket forming portions 16, 16.

[0021] As shown in Fig. 1, after the inner ring 2, outer ring 3, and balls 4 are assembled, a jig 15 is attached from the side surface on the front side of the bearing. As shown in Fig. 4, a gap is provided between the pocket Pt of the jig 15 and the balls 4. As shown in Fig. 2(b), the standing plate portion 17, which is an annular retaining portion, is retained on the outer peripheral surface 2d of the inner ring 2. The standing plate portion 17 has a tightening margin with respect to the outer peripheral surface 2d of the inner ring 2. A portion 17a of the standing plate portion 17 that contacts the outer peripheral surface 2d of the inner ring 2 is made of a resin material or a rubber material. The rest of the jig 15, other than the portion 17a that contacts the outer peripheral surface 2d of the inner ring 2, is made of an iron plate or a resin material.

[0022] <Parameters etc.>

[0023] In order to improve the load capacity and moment rigidity of an angular ball bearing within a given size, there are two methods: (1) increasing the number of balls, and (2) making the ball diameter larger. The angular ball bearing 1 according to the embodiment of the present invention shown in FIG. 1 is a full-ball type without a cage in order to increase the number of balls, and by improving the packing rate of the balls 4, the load capacity and moment rigidity are relatively improved compared to angular ball bearings with cages. The packing rate of the balls 4 is calculated by the following formula: Packing rate = (ball diameter Dw x number) / (π x pitch circle diameter PCD)

[0024] As shown in FIG. 5(A), the radial clearance δ1 between the balls 4 and the jig 15 is set smaller than the counter height h1 of the inner ring 2. Also, as shown in FIG. 2(b), the value (Dj-dp) / Da obtained by subtracting the pitch circle diameter dp of the balls 4 from the outer diameter dimension Dj of the jig 15 and dividing the result by the diameter Da of the balls is 0.70 or more and 0.95 or less. In this case, the strength of the jig 15 is prevented from decreasing, and the jig 15 is prevented from interfering with the outer ring raceway surface 3a, thereby preventing the outer ring raceway surface 3a from being scratched during assembly. As shown in Table 1, when (Dj-dp) / Da is smaller than 0.70, the column width between the pockets of the jig is reduced, and the strength of the jig is reduced. When (Dj-dp) / Da is larger than 0.95, the jig interferes with the outer ring raceway surface, and there is a risk of scratching the outer ring raceway surface during assembly.

[0025] [Table 1]

[0026] In Table 1, an "X" in the jig strength column indicates that there is a problem with the strength of the jig being reduced, and that the jig's usage conditions, materials used, dimensions, etc. may be restricted. An "O" in the jig strength column indicates that the jig meets the desired strength, and there are no restrictions on the jig's usage conditions, materials used, etc. In Table 1, an "X" in the raceway surface interference column indicates that the outer diameter of the jig interferes with the outer ring raceway surface. An "O" in the raceway surface interference column indicates that the outer diameter of the jig does not interfere with the outer ring raceway surface, and there is no risk of scratching the outer ring raceway surface during assembly.

[0027] <Comparison of characteristics between Examples and Comparative Examples> Table 2 shows a comparison of the characteristics of the examples and the comparative examples. [Table 2] In Table 2, "◯" in each characteristic column indicates that it is possible to implement and has excellent characteristics, "△" indicates that it has inferior characteristics to ◯ and is not recommended to implement, and "×" indicates that it is not possible to implement.

[0028] <Action and effect> As shown in Table 2, the angular contact ball bearing of the embodiment has good bearing assembly properties because the jig can be attached and detached from the side of the bearing. In contrast, the full-ball type angular contact ball bearing of Comparative Example 1 has a non-separable outer ring, so a counter is provided on the outer ring and the outer ring must be heated during assembly. Therefore, Comparative Example 1 is inferior to the embodiments in bearing assembly properties. Also, because Comparative Example 1 has a non-separable outer ring, it is difficult to assemble the outer ring into the reducer because it cannot be separated and assembled into the case first.

[0029] In the angular contact ball bearing of Comparative Example 2, which is a full ball type with a cage, torque is generated due to friction between the cage and the balls. Therefore, Comparative Example 2 has inferior torque performance to the Examples without a cage. Comparative Example 2 is more expensive than the Examples because it has a cage, and there is a risk that the cage will interfere with the mating part. Also, in Comparative Example 2, the outer ring does not have a counter, but during assembly, the inner ring must be installed with the balls set in each pocket of the cage.

[0030] In contrast, in the Example, the jig can be attached and detached from the side of the bearing, so the inner ring 2, outer ring 3, and balls 4 are assembled first, as shown in Figure 1. In the Example, the outer ring is separated when the jig is attached, so there is no counter on the outer ring 3, so there is no need to heat the outer ring 3 during assembly, and there is no need to set the balls in the pockets as in Comparative Example 2, which is a product with a cage. For this reason, the assembly process of the inner ring 2, outer ring 3, and balls 4 is easier in the Example than in Comparative Examples 1 and 2.

[0031] In the full-ball type angular contact ball bearing 1, a jig 15 is provided that holds the multiple balls 4 integrally with the inner ring 2, allowing for assembly in the same way as with a separate outer ring type bearing. That is, as shown in Figures 2(a) and (b), the outer ring 3 is separated from the angular contact ball bearing 1 and first assembled into the case, and the inner ring 2 is assembled onto a shaft or flange together with the jig 15 and the multiple balls 4, and then combined with the outer ring 3 assembled into the case. The jig 15 makes it possible to assemble the bearing 1 without the balls 4 undesirably coming apart from the inner ring 2.

[0032] Since jig 15 is detachable from the multiple balls 4 and inner ring 2, by removing jig 15 after assembling the bearing as shown in Figure 1, the bearing can be used as a full-ball type angular contact ball bearing 1 when in operation. In this way, because jig 15 can be removed during operation and used repeatedly, costs can be reduced compared to angular contact ball bearings with cages.

[0033] A gap is provided between the pocket of the jig 15 and the balls 4, and the standing plate portion 17 in FIG. 2(b) has an interference with the outer circumferential surface 2d of the inner ring 2, so that the balls 4 are not easily damaged when the jig 15 is inserted. The balls 4 and the inner ring 2 are integrated by providing an interference between the inner diameter of the standing plate portion 17 of the jig 15 and the outer diameter of the inner ring. Meanwhile, a gap is provided between the balls 4 and the jig pocket, which reduces interference between the jig 15 and the balls 4 when the jig is inserted, making the balls 4 less likely to be damaged. The standing plate portion 17, which is the holding portion of the jig 15, has a portion 17a that contacts the outer circumferential surface 2d of the inner ring 2 made of a resin material or a rubber material, which prevents damage to the outer circumferential surface 2d of the inner ring 2 and makes it easy to attach and remove the jig 15.

[0034] The embodiment is used as a full ball type angular contact ball bearing during bearing operation, and therefore has the following advantages: Since there is no cage, no torque is generated due to friction between the cage and the balls. Since there is no cage, it is possible to save space and reduce weight compared to angular contact ball bearings with cages. Since the jig 15 can be used repeatedly, it is possible to reduce costs compared to an angular ball bearing with a cage.

[0035] <Rear combination, etc.> Moment loads are often applied to industrial machinery. Under operating conditions where moment loads are applied by angular contact ball bearings, the angular contact ball bearings 1 can be arranged in a back-to-back configuration as shown in Fig. 6 to increase the distance between the bearing load points, so that the allowable radial load and allowable moment load can be increased even if the angular contact ball bearings 1 are made smaller, i.e., more compact. Furthermore, by arranging the angular contact ball bearings 1 in a back-to-back configuration, they can withstand axial loads in both directions, and the rigidity of the bearing portion can be increased by adding preload. In the example shown in Fig. 6, an inner ring spacer 7 and an outer ring spacer 8 are interposed between the angular contact ball bearings 1, 1 adjacent to each other in the axial direction, but it is also possible to omit these spacers 7, 8 and arrange the angular contact ball bearings 1, 1 in a back-to-back configuration.

[0036] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description is omitted. When only a part of the configuration is described, the other parts of the configuration are the same as the previously described embodiment unless otherwise specified. The same configuration has the same action and effect. It is possible to combine not only the parts specifically described in each embodiment, but also partially combine embodiments together, provided that there is no particular problem with the combination.

[0037] [Pocket cross section is straight] As a modified example in which the pocket shape in Fig. 5A is partially changed, as shown in Fig. 5B, the cross-sectional shape of the pocket Pt of the cylindrical portion 16 cut along a plane including the axial direction may be a straight shape along the radial direction. In this case, the radial clearance δ1 between the ball 4 and the jig 15 changes to a display part displaced in the pocket clearance radial direction with the inner diameter edge of the cylindrical portion 16 as the reference. In the case of Fig. 5B, the radial clearance δ1 is also set smaller than the counter height h1 of the inner ring 2. When the pocket cross section is made straight, the number of processing steps for the pocket Pt can be reduced, and the manufacturing cost can be reduced, compared to when the pocket cross section is made partially spherical.

[0038] [Second embodiment: U-shaped pocket, etc.] As shown in Fig. 7B, the pocket Pt of the cylindrical portion 16 may be U-shaped and open to the rear surface of the bearing. Also, as shown in Fig. 7A, the cross-sectional shape of the pocket Pt of the cylindrical portion 16 cut along a plane including the axial direction may be a straight shape along the radial direction. When the cylindrical portion 16 is made of resin, making the pocket Pt U-shaped and open to the rear surface of the bearing as shown in Fig. 7B makes it easier to punch out the pocket Pt than making it partially spherical, facilitating injection molding and reducing costs.

[0039] [Third embodiment: Figs. 8A to 8C, rectangular pocket, etc.] As shown in Fig. 8B, the pocket Pt of the cylindrical portion 16 may be rectangular and open to the rear surface of the bearing. As shown in Fig. 8A, the cross-sectional shape of the pocket Pt of the cylindrical portion 16 cut along a plane including the axial direction may be a straight shape along the radial direction. When the cylindrical portion 16 is made of resin, making the pocket Pt rectangular and open to the rear surface of the bearing as shown in Fig. 8B makes it easier to punch out the pocket Pt than making the pocket partially spherical, facilitating injection molding and reducing costs.

[0040] 8C, an annular elastic body 18 having a concave cross section that covers the inner diameter surface of the standing plate portion 17 and the inner diameter side portion of the inner and outer surfaces connected to this inner diameter surface may be attached to the standing plate portion 17. The annular elastic body 18 is made of resin, rubber, or the like. Since the portion 17a of the standing plate portion 17 that contacts the outer diameter surface 2d of the inner ring 2 and the surrounding area are enveloped by the annular elastic body 18, damage to the outer diameter surface 2d of the inner ring 2 is suppressed and the jig 15 is easy to attach and remove.

[0041] A jig without a slit may be used. It is also possible to use angular contact ball bearings in face-to-face combination, parallel combination, etc. The bearing may be an angular contact ball bearing without a cage and with a filling rate of the balls 4 of less than 95%. Angular contact ball bearings can also be used for applications other than industrial robots.

[0042] Although the embodiment for carrying out the present invention has been described above, the embodiment disclosed herein is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0043] 1...angular contact ball bearing, 2...inner ring, 3...outer ring, 4...ball, 15...jig, Pt...pocket, 16...cylindrical portion (pocket forming portion), 17...standing portion (retaining portion), SL...slit

Claims

1. A cageless angular contact ball bearing including an inner ring, an outer ring, and a plurality of balls interposed between the inner ring and the outer ring, An angular ball bearing comprising a jig that holds the plurality of balls integrally with the inner ring, the jig being detachable from the plurality of balls and the inner ring.

2. 2. The angular ball bearing according to claim 1, wherein the jig is provided with pockets for respectively holding the balls, and a radial pocket clearance between the balls and the jig is smaller than a counter height of the inner ring.

3. 3. The angular ball bearing according to claim 2, wherein the jig is configured with an L-shaped cross section, the L-shaped cross section being defined by a cylindrical portion in which the pocket is formed and an annular upright portion connected to the axial base end edge of the cylindrical portion.

4. 4. An angular contact ball bearing as described in claim 2 or claim 3, wherein the jig has a pocket forming portion in which one pocket is formed and a pocket forming portion in which another pocket circumferentially adjacent to the one pocket is formed, and a slit opening to the back side of the bearing is provided between these circumferentially adjacent pocket forming portions.

5. 3. An angular ball bearing according to claim 1, wherein the jig has an annular retaining portion that is retained on the outer peripheral surface of the inner ring, and the retaining portion has an interference with the outer peripheral surface of the inner ring.

6. 3. An angular contact ball bearing according to claim 1 or claim 2, wherein the jig has an annular retaining portion that is retained on the outer peripheral surface of the inner ring, the portion of this retaining portion that contacts the outer peripheral surface of the inner ring being made of a resin material or a rubber material, and the portion of the jig other than the portion that contacts the outer peripheral surface of the inner ring being made of an iron plate or a resin material.

7. 3. The angular ball bearing according to claim 1, wherein the value (Dj-dp) / Da obtained by subtracting the pitch circle diameter dp of the balls from the outer diameter dimension Dj of the jig and dividing the result by the diameter Da of the balls is 0.70 or more and 0.95 or less.

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