Angular ball bearing and rolling mechanism

Abstract

To provide an angular ball bearing and a rolling mechanism capable of achieving higher rigidity, higher load capacity, etc. without increasing the size.SOLUTION: An angular ball bearing 1 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. The angular ball bearing 1 has a contact angle θ of 40°-50°. A ratio W / Dw of an axial length W of an outer peripheral face 2d on the back side of the inner ring 2 to a ball diameter Dw as the diameter of the ball 4 is 0.15-0.35. A ratio V / Dw of an axial length V of an inner peripheral face 3d on the back side of the outer ring 3 to the ball diameter Dw is 0.15-0.35.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an angular ball bearing and a rotation mechanism used, for example, in the main bearing portion of a reducer of a robot or construction machine, and relates to a technology specialized for achieving compactness, high load capacity, and high rigidity. [Background technology]

[0002] There are two conventional techniques for increasing the moment rigidity of a bearing without increasing the size of the bearing (Patent Documents 1 and 2). The angular ball bearing in Patent Document 1 is of a multi-point contact type in which balls contact the raceway surfaces of the inner and outer rings at two points each with a required contact angle. The angular ball bearing of Patent Document 2 is a double-row integral angular ball bearing which has multiple rows of balls with different pitch circle diameters and a cage that holds the multiple rows of balls, in which the balls in each row contact the inner and outer ring raceway surfaces at a predetermined contact angle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-201294 A [Patent Document 2] Patent No. 4515039 Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, a ball bearing has a contact ellipse, which is the contact point between the raceway and the ball where the load acts. When the ball rolls, it is not possible for it to roll purely at all points on this contact ellipse, and slippage (differential slippage) occurs within the contact ellipse. Multi-point contact angular ball bearings contact one ball at two contact angles, which creates the problem of large differential slip at one of the contact points, accelerating wear on the raceway surface.

[0005] In double-row integral angular ball bearings, the balls are arranged in double rows, so the thickness of the raceway shoulder is thin. Therefore, when a moment load is applied to double-row integral angular ball bearings, the moment rigidity decreases due to the elastic deformation of the shoulder. In addition, double-row integral angular ball bearings have a complicated raceway shape, so manufacturing the raceways is difficult and expensive.

[0006] An object of the present invention is to provide an angular contact ball bearing and a rotation mechanism that can achieve high rigidity, high load capacity, and the like without increasing the size. [Means for solving the problem]

[0007] The angular ball bearing of the present invention is an angular ball bearing including an inner ring, an outer ring, and a plurality of balls interposed between the inner ring and the outer ring, The contact angle is 40° or more and 50° or less, a ratio W / Dw of an axial length W of an outer peripheral surface on a back surface side of the inner ring to a ball diameter Dw that is a diameter of the ball is 0.15 or greater and 0.35 or less, A ratio V / Dw of an axial length V of an inner peripheral surface on a back surface side of the outer ring to the ball diameter Dw is 0.15 or greater and 0.35 or less.

[0008] With this configuration, in a so-called full-ball angular contact ball bearing, when the contact angle is in the range of 40° to 50°, W / Dw is in the range of 0.15≦W / Dw≦0.35, and V / Dw is in the range of 0.15≦V / Dw≦0.35, high moment rigidity and high load capacity can be achieved without increasing the size. This configuration can also solve the problems of the multi-point contact angular ball bearing described above, such as wear due to differential slip, reduced moment rigidity due to axial thinning of the shoulder, and high costs due to manufacturing difficulties.

[0009] In the case of an angular ball bearing without a cage, the ball packing rate can be improved compared to an angular ball bearing with a cage.

[0010] The rotation mechanism of the present invention is a rotation mechanism including an 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 inner ring shoulder deformation suppression means is provided to suppress deformation of the inner ring shoulder, The angular contact ball bearing is The contact angle is 40° or more and 50° or less, A ratio V / Dw of an axial length V of an inner peripheral surface on a back surface side of the outer ring to a ball diameter Dw which is a diameter of the ball is 0.15 or more. The "inner race shoulder" is the outer periphery on the back side of the inner race.

[0011] In this way, in a rotating mechanism equipped with a so-called full-ball angular contact ball bearing, if an inner ring shoulder deformation suppression means is provided, the contact angle is in the range of 40° to 50°, and V / Dw is in the range of 0.15 or more, high rigidity, high load capacity, etc. can be achieved without increasing the size.

[0012] When a rotating mechanism is equipped with an angular ball bearing without a cage, the ball filling rate can be improved compared to an angular ball bearing with a cage, contributing to higher rigidity and higher load capacity of the rotating mechanism.

[0013] The inner ring shoulder deformation suppression means may be formed by integrating the inner ring with the rotating shaft of the rotating mechanism. In this case, it is possible to make the inner ring shoulder thicker than the inner ring shoulder of a general angular ball bearing. In this case, there is no decrease in moment rigidity as long as the contact angle is in the range of 40° to 50° and V / Dw is in the range of 0.15 or more.

[0014] The inner ring shoulder deformation suppression means may be configured so that the shoulder diameter of a member facing the back surface of the inner ring is equal to or larger than the inner ring shoulder diameter. In this case as well, deformation of the inner ring shoulder can be suppressed, and a decrease in moment rigidity can be suppressed.

[0015] The member facing the back surface of the inner ring may be the rotating shaft of the rotating mechanism or an annular regulating member. When the shaft shoulder of the rotating shaft is set to be equal to or larger than the inner ring shoulder diameter, the number of parts can be reduced and the structure can be simplified compared to providing an annular regulating member. When the annular regulating member is set to be equal to or larger than the inner ring shoulder diameter, the diameter dimension of the rotating shaft can be shortened.

[0016] Another rotation mechanism of the present invention is a rotation mechanism including an 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, the outer ring is integrally provided with a housing of the rotation mechanism, The angular contact ball bearing is The contact angle is 40° or more and 50° or less, The ratio W / Dw of the axial length W of the outer peripheral surface on the back surface side of the inner ring to the ball diameter Dw which is the diameter of the ball is 0.15 or more.

[0017] In this way, in a rotating mechanism equipped with a so-called full-ball angular contact ball bearing, if the outer ring is integrally formed with the housing of the rotating mechanism, and the contact angle is in the range of 40° to 50° and W / Dw is in the range of 0.15 or more, high rigidity, high load capacity, etc. can be achieved without increasing the size.

[0018] When a rotating mechanism is equipped with an angular ball bearing without a cage, the ball filling rate can be improved compared to an angular ball bearing with a cage, contributing to higher rigidity and higher load capacity of the rotating mechanism.

[0019] The speed reducer of the present invention includes any one of the above-described rotation mechanisms of the present invention, and therefore the effects described above regarding the rotation mechanism of the present invention can be obtained. Effect of the Invention

[0020] The angular contact ball bearing of the present invention, in a full ball angular contact ball bearing, has a contact angle in the range of 40° to 50°, W / Dw in the range of 0.15≦W / Dw≦0.35, and V / Dw in the range of 0.15≦V / Dw≦0.35, so that it is possible to achieve both high moment rigidity and high load capacity without increasing the size. [Brief description of the drawings]

[0021] [Figure 1] 1 is a vertical sectional view of an angular contact ball bearing according to a first embodiment of the present invention. [Diagram 2] 4 is a conceptual diagram illustrating the relationship between the contact angle and moment stiffness of the angular ball bearing. FIG. [Diagram 3] FIG. 4 is a vertical cross-sectional view showing an example of a back-to-back assembly of the angular ball bearings. [Figure 4] FIG. 6 is an enlarged cross-sectional view of a main part of a rotation mechanism including an angular ball bearing according to a second embodiment of the present invention. [Diagram 5] FIG. 11 is an enlarged cross-sectional view of a main part of a rotation mechanism including an angular ball bearing according to a third embodiment of the present invention. [Figure 6] FIG. 11 is an enlarged cross-sectional view of a main part of a rotation mechanism including an angular ball bearing according to a fourth embodiment of the present invention. [Figure 7] FIG. 11 is an enlarged cross-sectional view of a main part of a rotation mechanism including an angular ball bearing according to a fifth embodiment of the present invention. [Figure 8] FIG. 2 is a vertical cross-sectional view showing the entire rotation mechanism of each embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] [First embodiment] An angular ball bearing according to an embodiment of the present invention will be described with reference to Figures 1 to 3. This angular ball bearing is used, for example, as a main bearing portion of a reducer in a robot or construction machine, etc. In this specification, the angular ball bearing may be simply referred to as a "bearing".

[0023] As shown in Fig. 1, the angular contact ball bearing 1 is a so-called full-ball angular contact ball bearing without a cage, which includes an inner ring 2, an outer ring 3, and a number of balls 4 interposed between raceway surfaces 2a, 3a of the inner and outer rings 2, 3. 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 of the angular ball bearing 1. The "radial direction" refers to the direction perpendicular to the straight line that forms the "axial direction".

[0024] The raceway surface 3a is connected to the front surface of the outer ring 3 via a counterbore 3b. An inner peripheral surface 3d on the back side of the outer ring 3 is located radially inward from the counterbore 3b of the outer ring 3. The raceway surface 2a is connected to the front surface of the inner ring 2 via a counterbore 2b. An outer peripheral surface 2d on the back 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. The outer peripheral surface 2d of the inner ring 2 is located radially outward from the counterbore 2b of the inner ring 2. The front surfaces of the inner and outer rings 2 and 3 refer to the side surfaces that do not support an axial load, and the back surfaces 2c and 3c of the inner and outer rings 2 and 3 refer to the side surfaces that support an axial load.

[0025] <About parameters etc.> In order to improve the load capacity and moment rigidity of an angular contact ball bearing within a given size, there are two methods: (1) increasing the number of balls, and (2) increasing the ball diameter. Another method for improving moment rigidity is to (3) increase the contact angle. The angular contact ball bearing 1 according to the embodiment of the present invention is cage-less (total balls) 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 an angular contact ball bearing with a cage. The packing rate of the balls 4 is expressed by the following formula: Packing rate = (ball diameter Dw x number) / (π x pitch circle diameter PCD). This indicates that the filling rate of the angular contact ball bearing of the present invention is 95% or more.

[0026] When the ball diameter Dw is increased, if deformation of the raceways, that is, the inner and outer rings 2 and 3, is not taken into consideration, the larger the ball diameter Dw is, the higher the relative load capacity and moment rigidity are improved. However, in reality, if the shoulders 5, 6 of the raceways are thin, deformation of the shoulders 5, 6 occurs. For this reason, as a trade-off when increasing the ball diameter Dw, the axial thickness of the shoulders 5, 6 of the inner and outer rings 2, 3 is reduced. When a moment load is applied to a thin shoulder, it deforms in the load area, and the clearance inside the bearing widens, reducing moment rigidity.

[0027] As shown in the right side of Figure 2, when the contact angle θ of an angular ball bearing is made larger than that shown in the left side of Figure 2, the distance between the points of application becomes larger. For this reason, the moment rigidity of an angular ball bearing with a larger contact angle θ on the right side of Figure 2 is usually improved. However, because the contact areas of the balls and the inner and outer ring raceways come into contact with the tips of the shoulders 5, 6, the deformation of the shoulders 5, 6 is actually promoted, and the moment rigidity decreases. Note that the deformation of the shoulders 5, 6 on the right side of Figure 2 is conceptually exaggerated.

[0028] Therefore, in this embodiment, in order to improve the load capacity and moment rigidity while considering the deformation of the shoulder, a functional comparison was made as follows for a full-ball angular contact ball bearing. This comparison was made by simulation, but substantially similar results were obtained in an actual machine test. The external load that the angular ball bearing received was verified using a moment load applied by a general reducer. The moment load means a load that tilts (bends) the rotating shaft, that is, a load that gives an angle to the rotating shaft.

[0029] The bearing size is an angular contact ball bearing with a ball diameter / PCD ratio of 0.05 to 0.10. As shown in Fig. 1, 20 types of angular contact ball bearings (Comparative Examples 1 to 16, Examples 1 to 4) were assumed, with a contact angle θ in the range of 20° to 55°, a ratio W / Dw of the axial length W of the outer peripheral surface 2d on the back side of the inner ring 2 to the ball diameter Dw which is the diameter of the balls 4 in the range of 0.07 to 0.4, and a ratio V / Dw of the axial length V of the inner peripheral surface 3d on the back side of the outer ring 3 to the ball diameter Dw which is the diameter of the balls 4 in the range of 0.07 to 0.4. Table 1 shows the load capacity, moment stiffness (when the raceway is rigid), and deformation of shoulder portions 5 and 6 for the comparative examples and examples in which each parameter was changed.

[0030] [Table 1] Table 1. Relationship between θ, W / Dw, V / Dw, load capacity, moment stiffness, and shoulder deformation

[0031] In Table 1, ◎ indicates that the load capacity can be implemented and can be implemented efficiently, ◯ indicates that the performance is inferior to ◎ but it is implementable, △ indicates that the performance is inferior to ◯ and it is not recommended to implement, and × indicates that it is not implementable. In Table 1, the arrow of V / Dw indicates that the value is the same as the W / Dw value in the same row.

[0032] Moment stiffness indicates the stiffness of an angular contact ball bearing, and is expressed as the load moment value required to tilt a unit angle (1 arc.min.). The moment stiffness in this example is expressed when the raceway is considered to be a rigid body, and the ◎, O, △, and × in the moment stiffness in Table 1 have the same definition as the load capacity. In Table 1, the shoulder deformation is indicated as ◯ if there is almost no shoulder deformation and no reduction in moment rigidity, and × if the shoulder deformation reduces moment rigidity. According to Table 1, it can be seen that Examples 1, 2, 3, and 4 are capable of achieving load capacity and moment rigidity or can achieve them efficiently, and do not experience a decrease in moment rigidity due to deformation of the shoulder portion.

[0033] <Action and effect> Therefore, in a cageless, full-ball angular contact ball bearing, high load capacity and high moment rigidity can be achieved simultaneously when the contact angle θ is in the range of 40° to 50°, W / Dw is in the range of 0.15≦W / Dw≦0.35, and V / Dw is in the range of 0.15≦V / Dw≦0.35. In addition, if W / Dw≧0.15 and V / Dw≧0.15, there is no decrease in rigidity due to deformation of the shoulder. The configuration of this embodiment can solve problems associated with the multi-point contact angular ball bearing described above, such as wear due to differential slippage, reduced moment rigidity due to thinning of the shoulder portion, and high costs due to manufacturing difficulties.

[0034] <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. 3 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. 3, 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.

[0035] <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.

[0036] The following FIGS. 4 to 7 are partial views of the rotation mechanism in FIG. 8, which will be described later. [Second embodiment: Inner ring and rotating shaft integrated] FIG. 4 is an enlarged cross-sectional view of a main part of a rotation mechanism 9 including an angular ball bearing according to a second embodiment.

[0037] The rotation mechanism 9 may be provided with an inner ring shoulder deformation suppression means 11 for suppressing deformation of the inner ring shoulder 5. Specifically, the inner ring shoulder deformation suppression means 11 is formed by integrating the inner ring 2 of the angular contact ball bearing 1 on the left side of Fig. 4 with the rotating shaft 12 of this rotation mechanism 9. The term "integrated" means that the inner ring 2 and the rotating shaft 12 are not formed by combining multiple elements but are formed as a part or the whole of a single object from a single material by, for example, forging or machining.

[0038] In this way, in a rotation mechanism 9 equipped with a cage-less, full-ball angular contact ball bearing 1, if the inner ring shoulder deformation suppression means 11 is provided and the contact angle θ is in the range of 40° to 50° and V / Dw (see FIG. 1) is in the range of 0.15 or more, high rigidity and high load capacity can be achieved without increasing the size. If the inner ring 2 is integrated with the rotating shaft 12 of the rotation mechanism 9, it is possible to make the inner ring shoulder 5 thicker than the inner ring shoulder of a general angular contact ball bearing. In that case, if the contact angle θ is in the range of 40° to 50° and V / Dw (see FIG. 1) is in the range of 0.15 or more, no reduction in moment rigidity occurs.

[0039] [Third embodiment: Shaft shoulder ≧ inner ring shoulder diameter] As shown in Fig. 5, in a rotation mechanism 9 equipped with a cage-less, so-called full-ball angular contact ball bearing 1, the inner ring shoulder deformation suppression means may be configured to make the shoulder diameter D1 of a member facing the back surface 2c of the inner ring 2 equal to or larger than the inner ring shoulder diameter D2. The member facing the back surface 2c of the inner ring 2 is the rotating shaft 12 of the rotation mechanism 9. When the shaft shoulder D1 of this rotating shaft 12 is equal to or larger than the inner ring shoulder diameter D2, the number of parts can be reduced and the structure simplified compared to providing an annular restricting member or the like, which will be described later. In addition, the same effects as those of the above-mentioned rotation mechanism are achieved.

[0040] [Fourth embodiment: Shoulder diameter (outer diameter) of regulating member ≧ shoulder diameter of inner ring] As shown in Fig. 6, the member facing the back surface of the inner ring 2 may be an annular regulating member 13. The regulating member 13 is formed, for example, in a rectangular cross section, and is interposed between the inner surface of the flange portion 12a of the rotating shaft 12 and the back surface 2c of the inner ring 2. In a rotation mechanism 9 including a full-ball angular contact ball bearing 1, the outer diameter of the regulating member 13, that is, the shoulder diameter D3, is set to be equal to or larger than the inner ring shoulder diameter D2, thereby making it possible to reduce the diameter dimension of the rotating shaft 12. In addition, the same effects as those of the rotation mechanism of the second embodiment are achieved.

[0041] [Fifth embodiment: Outer ring and housing integrated] 7, in a rotation mechanism 9 equipped with a full-ball angular contact ball bearing 1, an outer ring 3 may be provided integrally with a housing 14 of the rotation mechanism 9. The term "integral" means that the outer ring 3 and the housing 14 are not formed by combining a plurality of elements but are formed as a part or the whole of a single object from a single material by, for example, forging, machining, etc.

[0042] In this way, in a rotating mechanism 9 equipped with a cage-less, full-ball angular contact ball bearing 1, if the outer ring 3 is integrally formed with the housing 14 of the rotating mechanism 9, and the contact angle is in the range of 40° to 50° and W / Dw (see Figure 1) is in the range of 0.15 or more, high rigidity, high load capacity, etc. can be achieved without increasing the size.

[0043] <Axle unit> The rotation mechanism 9 shown in Fig. 8 is a vehicle power unit, a so-called axle unit, provided on a vehicle, and includes a double-row angular ball bearing 1 assembled back-to-back, and a drive motor M with a power generating function. The outer ring 3 of the angular ball bearing 1 is a rotating ring, and the inner ring 2 integrated with the shaft is a fixed ring. A brake rotor BR and a wheel (not shown) are attached to a wheel mounting flange 3F provided on the outboard end of the outer ring 3 in a state where they overlap in the axial direction. When this rotation mechanism 9 is configured as the partial views of Figs. 4 to 7, the above-mentioned effects can be obtained.

[0044] 4 to 7 may be used, for example, as a main bearing portion of a reducer 10 of a robot, a construction machine, or the like. In other words, the reducer 10 may include any of the above-mentioned rotation mechanisms 9. It is also possible to use angular ball bearings in a face-to-face combination, a parallel combination, or the like. It is also possible to use angular contact ball bearings in multiple rows (three or more rows). The angular ball bearing and the rotation mechanism can also be used for purposes other than the reducer.

[0045] 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]

[0046] 1...angular contact ball bearing, 2...inner ring, 3...outer ring, 4...ball, 5...inner ring shoulder, 9...rotation mechanism, 10...reduction gear, 11...means for suppressing deformation of inner ring shoulder, 12...rotating shaft, 13...regulating member, 14...housing

Claims

1. An angular contact ball bearing having an inner ring, an outer ring, and a plurality of balls interposed between the inner ring and the outer ring, The contact angle is 40° or more and 50° or less, a ratio W / Dw of an axial length W of an outer peripheral surface on a back surface side of the inner ring to a ball diameter Dw which is a diameter of the ball is 0.15 or greater and 0.35 or less, The angular contact ball bearing has a ratio V / Dw of an axial length V of an inner peripheral surface on the back side of the outer ring to the ball diameter Dw of 0.15 or more and 0.35 or less.

2. 2. The angular contact ball bearing according to claim 1, which is cageless.

3. A rotation mechanism including an 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 inner ring shoulder deformation suppression means is provided to suppress deformation of the inner ring shoulder, The angular contact ball bearing is The contact angle is 40° or more and 50° or less, A rotation mechanism in which a ratio V / Dw of an axial length V of an inner peripheral surface on the back side of the outer ring to a ball diameter Dw which is the diameter of the ball is 0.15 or more.

4. 4. The rotating mechanism according to claim 3, further comprising a cageless angular contact ball bearing.

5. 5. The rotating mechanism according to claim 3, wherein the inner ring shoulder deformation suppressing means is formed by integrating the inner ring with a rotating shaft of the rotating mechanism.

6. 5. The rotation mechanism according to claim 3, wherein the inner ring shoulder deformation suppressing means comprises a member having a shoulder diameter facing a back surface of the inner ring that is equal to or larger than the inner ring shoulder diameter.

7. 7. The rotation mechanism according to claim 6, wherein the member facing the back surface of the inner ring is a rotation shaft of the rotation mechanism or an annular regulating member.

8. A rotation mechanism including an 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, the outer ring is integrally provided with a housing of the rotation mechanism, The angular contact ball bearing is The contact angle is 40° or more and 50° or less, A rotation mechanism in which a ratio W / Dw of an axial length W of an outer peripheral surface on a back surface side of the inner ring to a ball diameter Dw which is a diameter of the ball is 0.15 or more.

9. 9. The rotating mechanism according to claim 8, comprising a cageless angular contact ball bearing.

10. A reducer comprising the rotation mechanism according to claim 3 or 4.

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