Self-aligning rolling bearing
By differing the surface roughness of the outer and inner surfaces in self-aligning ring bearings, the design addresses the trade-off between self-alignment and productivity, ensuring high performance and efficiency in corrosive conditions.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- JTEKT CORP
- Filing Date
- 2022-06-29
- Publication Date
- 2026-06-23
AI Technical Summary
Conventional self-aligning ring bearings face a trade-off between maintaining self-alignment and improving productivity due to the same surface roughness specifications for the outer and inner surfaces of the outer ring and self-aligning ring, leading to complex polishing processes and reduced productivity.
Designing the outer ring's surface roughness to be greater than the inner ring's surface roughness in a self-aligning ring bearing, allowing for separate material selection based on machinability and corrosion resistance, with the outer ring made of ceramics and the inner ring made of metal, and using ceramics for rolling elements and a resin cage.
Achieves equivalent self-aligning performance while significantly enhancing productivity and corrosion resistance, particularly in corrosive environments.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a rolling bearing with a spherical seat ring.
Background Art
[0002] Misalignment due to installation errors of rolling bearings or deflection of the rotating shaft can cause shaft breakage, vibration, abnormal noise, etc. In devices and equipment to which rolling bearings are applied, in order to reduce the influence of the above misalignment, it is known to employ a rolling bearing with a spherical seat ring. The rolling bearing with a spherical seat ring includes an outer ring and a spherical seat ring that is swingably fitted to the outer peripheral surface of the outer ring. The influence of the above misalignment is reduced by the swing of the outer ring within the spherical seat ring.
[0003] In order to reduce the catching at the fitting surface between the outer ring and the spherical seat ring during self-alignment in a rolling bearing with a spherical seat ring, the above fitting surface is polished. The above catching is reduced more as the surface roughness of the above fitting surface is reduced by polishing. As the surface roughness of the fitting surface between the outer ring and the spherical seat ring, for example, Patent Document 1 discloses that the arithmetic mean roughness Ra of the spherical inner peripheral surface of the spherical seat ring and the spherical outer peripheral surface of the outer ring is set to be 0.04 μm or more and 1.50 μm or less.
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
[0005] As mentioned above, in bearings with self-aligning rings, the mating surfaces between the outer ring and the self-aligning ring should preferably have a low surface roughness from the standpoint of self-alignment, as this reduces snagging at the mating surface. Therefore, the surface roughness of the outer circumferential surface of the outer ring and the inner circumferential surface of the self-aligning ring, which form the mating surfaces, is one of the important specifications in the design of bearings with self-aligning rings. Naturally, in order to improve self-alignment, the surface roughness of the outer circumferential surface of the outer ring and the inner circumferential surface of the self-aligning ring should be designed to be smaller. However, the smaller the surface roughness, the more polishing time and setup changes are required, making the polishing process more complicated and reducing the productivity of bearings with self-aligning rings.
[0006] In conventional designs for bearings with self-aligning rings, the surface roughness of the outer ring's outer surface and the self-aligning ring's inner surface are set as a single category, taking into account the balance between self-alignment and productivity. In other words, in the conventional design described above, the surface roughness of the outer ring's outer surface and the self-aligning ring's inner surface are not designed individually. For example, Patent Document 1 describes setting the surface roughness of the outer ring's outer surface and the self-aligning ring's inner surface to a predetermined arithmetic mean roughness Ra, as described above. Therefore, in the conventional design described above, it was difficult to achieve both improved self-alignment and improved productivity.
[0007] Therefore, there was a need to develop a bearing with a self-aligning ring that maintained the same level of self-aligning performance as conventional bearings with self-aligning rings, while also offering high productivity.
[0008] A rolling bearing with a self-aligning ring according to one aspect of this disclosure is: An inner ring having an inner ring raceway surface on its outer circumference, An outer ring having an outer ring raceway surface on its inner circumference and an outer ring surface that is part of a sphere, A rolling element is arranged to roll freely between the inner ring raceway surface and the outer ring raceway surface, The outer ring is fitted to the outer circumferential surface of the outer ring in a pivotable manner, and the aligning ring has an inner circumferential surface that is part of a spherical surface. The surface roughness of the outer circumferential surface of the outer ring is greater than the surface roughness of the inner circumferential surface of the self-aligning ring. [Brief explanation of the drawing]
[0009] [Figure 1] This is a schematic axial cross-sectional view of a self-aligning ring-equipped rolling bearing 100. [Figure 2] This is a schematic cross-sectional view of the roll 210 in the extending direction, showing a part of the apparatus 200. [Modes for carrying out the invention]
[0010] <Problems that the present invention aims to solve> As described above, in the conventional design of bearings with self-aligning rings, where the surface roughness of the outer ring's outer surface and the self-aligning ring's inner surface are defined as a single category, it has been difficult to achieve both improved self-alignment and increased productivity. Furthermore, in the design of various bearings, including bearings with self-aligning rings, bearings using various materials have been considered to improve corrosion resistance and durability. For example, Patent Document 1 describes a bearing with a self-aligning ring that uses inner and outer rings made of Ni-Cr-Al alloy or precipitation-hardening stainless steel to improve corrosion resistance and durability. Here, the machinability of bearing materials differs depending on their type. The polishing process for materials with low machinability is more complicated than the polishing process for materials with high machinability.
[0011] Bearing materials are broadly classified into metal materials and ceramic materials. Generally, metal materials have better machinability than ceramic materials, but are inferior in corrosion resistance and durability. Conversely, ceramic materials have better corrosion resistance and durability than metal materials, but are inferior in machinability. In bearings with self-aligning rings, ceramic zirconia is used for the inner ring, outer ring, and rolling elements where corrosion resistance and durability are required, while metal stainless steel, which has excellent machinability, may be used for the self-aligning ring. As mentioned above, in the design of conventional self-aligning ring bearings, the surface roughness of the outer circumferential surface of the outer ring and the inner circumferential surface of the self-aligning ring are set to the same specifications. Here, zirconia has lower machinability than stainless steel. Therefore, in the machining of the mating surfaces of the outer ring and the self-aligning ring, the polishing process of the outer circumferential surface of the zirconia outer ring becomes a bottleneck in the manufacturing lead time. As a result, even if stainless steel, which has excellent machinability, is used for the self-aligning ring, it may not be possible to sufficiently improve the productivity of bearings with self-aligning rings.
[0012] <Effects of the Invention of the Present Disclosure> According to the invention of the present disclosure, a spherical plain bearing with equivalent self-aligning property as that of the conventional spherical plain bearing and with high productivity is provided while maintaining the self-aligning property.
[0013] <Summary of Embodiments of the Invention of the Present Disclosure> Hereinafter, a summary of embodiments of the invention of the present disclosure will be listed and described. (1) The rolling bearing with a spherical plain bearing of the present disclosure includes an inner ring having an inner ring raceway surface on the outer periphery, an outer ring having an outer ring raceway surface on the inner periphery and the outer peripheral surface being a part of a spherical surface, rolling elements arranged to be freely rollable between the inner ring raceway surface and the outer ring raceway surface, and a spherical plain bearing having an inner peripheral surface formed as a part of a spherical surface, which is swingably fitted to the outer peripheral surface of the outer ring. The surface roughness of the outer peripheral surface of the outer ring is larger than that of the inner peripheral surface of the spherical plain bearing.
[0014] The rolling bearing with a spherical plain bearing described in (1) above has equivalent self-aligning property as that of the conventional spherical plain bearing and has high productivity while maintaining the self-aligning property.
[0015] (2) In the rolling bearing with a spherical plain bearing described in (1) above, the difference in the arithmetic mean roughness Ra between the outer peripheral surface of the outer ring and the inner peripheral surface of the spherical plain bearing is 0.1 μm or more and 0.2 μm or less.
[0016] The rolling bearing with a spherical plain bearing described in (2) above is excellent in maintaining self-aligning property and productivity.
[0017] (3) In the rolling bearing with a spherical plain bearing described in (2) above, the arithmetic mean roughness Ra of the outer peripheral surface of the outer ring is 0.3 μm or more and 0.7 μm or less.
[0018] The rolling bearing with a spherical plain bearing described in (3) above is excellent in self-aligning property and productivity.
[0019] (4) In the rolling bearing with a spherical roller according to any one of (1) to (3) above, the outer ring is made of ceramics and the spherical roller is made of metal.
[0020] The rolling bearing with a spherical roller according to (4) above has higher productivity than a conventional rolling bearing with a spherical roller having an outer ring made of ceramics and a spherical roller made of metal.
[0021] (5) In the rolling bearing with a spherical roller according to (4) above, the outer ring is made of zirconia and the spherical roller is made of stainless steel.
[0022] The rolling bearing with a spherical roller according to (5) above has higher productivity than a conventional rolling bearing with a spherical roller having an outer ring made of zirconia and a spherical roller made of stainless steel.
[0023] (6) In the rolling bearing with a spherical roller according to (4) or (5) above, the inner ring and the rolling elements are made of ceramics.
[0024] (7) In the rolling bearing with a spherical roller according to (6) above, the inner ring and the rolling elements are made of zirconia.
[0025] The rolling bearing with a spherical roller according to (6) or (7) above has excellent corrosion resistance and durability.
[0026] <Details of Embodiments of the Invention of the Present Disclosure> Hereinafter, embodiments of the present disclosure will be described. In the present disclosure, it should be considered that the embodiments of the invention are illustrative in all respects and not restrictive. The scope of the rights of the present invention is indicated by the scope of claims, and it is intended that all modifications within the meaning and scope equivalent to the scope of claims be included.
[0027] Figure 1 is a schematic axial cross-sectional view of the self-aligning ring rolling bearing 100 of the present disclosure (hereinafter sometimes simply referred to as "bearing 100"). The bearing 100 comprises an inner ring 110, an outer ring 120, rolling elements 130, a self-aligning ring 140, and a cage 150. The inner ring 110 has an inner ring raceway surface 111 on its outer circumference. The outer ring 120 has an outer ring raceway surface 121 on its inner circumference. The rolling elements 130 are held by the cage 150 and are arranged to roll freely between the inner ring raceway surface 111 and the outer ring raceway surface 121. The inner ring 110 has a retaining surface 112 on its inner circumference for holding a rotating shaft. The rotating shaft 211, which will be described later, is inserted into a hole H formed by the retaining surface 112 of the inner ring 110 and is held by the retaining surface 112. The self-aligning ring 140 has a mounting surface 141 on its outer circumference for holding a housing. The bearing 100 is fixed to the housing 220 by fitting its mounting surface 141 into the mounting portion 221 of the housing 220, which will be described later.
[0028] The outer ring 120 has an outer circumferential surface 122 which is part of a sphere. The centering ring 140 has an inner circumferential surface 142 which is part of a sphere. The outer circumferential surface 122 and the inner circumferential surface 142 have substantially the same radius of curvature. The outer circumferential surface 122 is formed as a convex curved surface. The inner circumferential surface 142 is formed as a concave curved surface. As a result, when the outer ring 120 and the centering ring 140 are fitted together, the outer ring 120 and the centering ring 140 can swing relative to each other via the outer circumferential surface 122 and the inner circumferential surface 142.
[0029] Figure 2 is a schematic cross-sectional view in the extending direction of the roll 210, showing a part of the apparatus 200 equipped with the roll 210. The apparatus 200 comprises a bearing 100, the roll 210, and a housing 220. The roll 210 has a rotating shaft 211. The rotating shaft 211 is held by the holding surface 112 of the bearing 100. The housing 220 has a mounting portion 221. The bearing 100 is fitted into the mounting portion 221 and fixed to the housing 220.
[0030] The apparatus 200 of this disclosure, shown in Figure 2, is a liquid crystal film manufacturing apparatus. The apparatus 200 has a chemical solution C filled inside a housing 220. The chemical solution consists of an aqueous solution containing boric acid and potassium iodide. The apparatus 200 is configured to pass a liquid crystal deflection film through the chemical solution C by driving a plurality of rolls 210 (not shown). The rolls 210 may bend due to their own weight and the tension of the deflection film. This bending causes misalignment of the rotation axis 211 of the rolls 210. In this case, the outer ring 120 oscillates relative to the centering ring 140 in accordance with the misalignment. As a result, as shown in Figure 2, the structure (bearing 100) consisting of the inner ring 110, outer ring 120, rolling elements 130, and cage 150 tilts and oscillates with respect to the self-aligning ring 140 fixed to the housing 220, and the misalignment is automatically corrected.
[0031] In a liquid crystal film manufacturing apparatus such as the apparatus 200 of this disclosure, the bearing 100 comes into contact with the chemical solution C. In such an environment, the inner ring 110, outer ring 120, and rolling elements 130 are particularly susceptible to corrosion by the chemical solution C. Here, the inner ring 110, outer ring 120, and rolling elements 130 of the bearing 100 installed in the apparatus 200 of this disclosure are made of ceramics. By making the inner ring 110, outer ring 120, and rolling elements 130 of ceramics, corrosion resistance and durability are improved. Therefore, the bearing 100 of this disclosure is suitable for placement in corrosive liquids. The ceramic material used for the inner ring 110, outer ring 120, and rolling elements 130 can be any ceramic material that can be used in bearings, and is not particularly limited. Specific ceramic materials include, for example, silicon nitride, silicon carbide, zirconia, and alumina. Zirconia is preferred as the ceramic material used for the inner ring 110, outer ring 120, and rolling element 130 of this disclosure, from the viewpoint of corrosion resistance and durability.
[0032] In the bearing 100 of this disclosure, the cage 150 is made of resin. By making the cage 150 of resin, the processability is improved. The resin material used for the cage 150 can be any resin material that can be used in bearings, and is not particularly limited. Specific resin materials include, for example, polyamide resin and polyetheretherketone (PEEK). As described above, the bearing 100 of this disclosure is placed in a corrosive chemical solution C. Therefore, from the viewpoint of corrosion resistance, PEEK is preferred as the resin material used for the cage 150 of this disclosure.
[0033] In the bearing 100 of this disclosure, the aligning ring 140 is made of metal. Making the aligning ring 140 out of metal improves machinability. The metal material used for the aligning ring 140 can be any metal material that can be used in bearings, and is not particularly limited. Specific metal materials include, for example, bearing steel and stainless steel. In this disclosure, stainless steel is preferred as the metal material used for the aligning ring 140 from the viewpoint of machinability and durability, and JIS standard SUS304 is particularly preferred.
[0034] As described above, in the bearing 100 of this disclosure, the outer ring 120 is made of ceramics, and the centering ring 140 is made of metal. Therefore, there is a difference in the machinability of the outer ring 120 and the centering ring 140. Generally, ceramic materials have superior corrosion resistance and durability compared to metal materials, but are inferior in machinability. Therefore, the polishing process for the outer circumferential surface 122 of the outer ring 120 is more complicated than that for the inner circumferential surface 142 of the centering ring 140. Here, if the outer circumferential surface 122 and the inner circumferential surface 142, which are the mating surfaces of the outer ring and the centering ring, are designed to have the same surface roughness, as in the design of conventional bearings with centering rings, the polishing process for the outer circumferential surface 122 of the outer ring 120 becomes a bottleneck in the manufacturing lead time. On the other hand, in the bearing 100 of this disclosure, the surface roughness of the outer circumferential surface 122 of the outer ring 120 is designed to be greater than the surface roughness of the inner circumferential surface 142 of the centering ring 140. Therefore, the number of steps required for polishing the outer circumferential surface 122 is reduced, resulting in improved productivity of the bearing 100. Furthermore, the inventors have found that the bearing 100 of this disclosure, in which the surface roughness of the outer circumferential surface 122 is designed to be greater than that of the inner circumferential surface 142, has the same degree of self-aligning ability as a conventional bearing with a self-aligning ring in which the mating surfaces of the outer ring and the self-aligning ring are designed to have the same surface roughness.
[0035] Here, the difference between the surface roughness of the outer circumferential surface 122 of the outer ring 120 and the surface roughness of the inner circumferential surface 142 of the self-aligning ring 140 is preferably 0.1 μm or more and 0.2 μm or less in terms of arithmetic mean roughness Ra. If the above difference in surface roughness is 0.1 μm or more, the productivity of the bearing 100 is further improved. If the above difference in surface roughness is 0.2 μm or less, the bearing 100 can maintain a self-aligning performance equivalent to that of conventional bearings with self-aligning rings. Furthermore, the arithmetic mean roughness Ra of the outer circumferential surface 122 of the outer ring 120 is preferably 0.3 μm or more and 0.7 μm or less. In other words, the arithmetic mean roughness Ra of the inner circumferential surface 142 of the self-aligning ring 140 is preferably 0.1 μm or more and 0.6 μm or less. A bearing 100 having such surface roughness of the outer circumferential surface 122 and inner circumferential surface 142 has excellent self-aligning performance and productivity.
[0036] As the bearing 100 of this disclosure, Figure 1 shows a ball bearing with a self-aligning ring, in which balls are used as rolling elements 130. However, the bearing 100 of this disclosure is not limited to a ball bearing with a self-aligning ring, and can also be a roller bearing with a self-aligning ring. Furthermore, as the apparatus 200 of this disclosure, Figure 2 shows a liquid crystal film manufacturing apparatus to which the bearing 100 is applied. However, the bearing 100 of this disclosure is not limited to a liquid crystal film manufacturing apparatus, and can also be applied to other equipment and apparatus to which self-aligning ring rolling bearings are applied, such as continuous casting equipment, papermaking machinery, and reduction gears. [Explanation of symbols]
[0037] 100 bearings 110 Inner Ring 111 Inner ring track surface 112 Holding surface 120 Outer ring 121 Outer ring raceway surface 122 Outer surface 130 Rolling element 140 Aligning wheel 141 Mounting surface 142 Inner surface 150 Retainer 200 equipment 210 rolls 211 Rotation axis 220 Housing 221 Mounting part H hole
Claims
1. An inner ring having an inner ring raceway surface on its outer circumference, An outer ring having an outer ring raceway surface on its inner circumference and an outer ring surface that is part of a sphere, A rolling element is disposed to roll freely between the inner ring raceway surface and the outer ring raceway surface, The outer ring comprises a self-aligning ring having an inner surface that is part of a sphere and is pivotably fitted onto the outer surface of the outer ring, The surface roughness of the outer circumferential surface of the outer ring is greater than the surface roughness of the inner circumferential surface of the self-aligning ring. Self-aligning rolling bearing.
2. The rolling bearing with a self-aligning ring according to claim 1, wherein the difference in arithmetic mean roughness Ra between the outer surface of the outer ring and the inner surface of the self-aligning ring is 0.1 μm or more and 0.2 μm or less.
3. The self-aligning rolling bearing with a self-aligning ring according to claim 2, wherein the arithmetic mean roughness Ra of the outer surface of the outer ring is 0.3 μm or more and 0.7 μm or less.
4. A rolling bearing with a self-aligning ring according to any one of claims 1 to 3, wherein the outer ring is made of ceramic and the self-aligning ring is made of metal.
5. The rolling bearing with a self-aligning ring according to claim 4, wherein the outer ring is made of zirconia and the self-aligning ring is made of stainless steel.