Roller bearing

Abstract

To provide a roller bearing capable of reducing the manufacturing cost while preventing an integration damage to a bearing component.SOLUTION: The roller bearing includes an inner ring, an outer ring, a plurality of rollers laid between the inner ring and the outer ring, and a cage holding the rollers. An assembly of one of the inner ring and the outer ring, the plurality of rollers 3, and the cage is separable from the other of the inner ring and the outer ring in the axial direction. A chamfer 7 of each roller 3 is a round chamfer. An axial chamfer size (C) of the chamfer 7 is set to be a roller chamfer R size or smaller, and a roller chamfer face 7a and a roller outer peripheral face 3a are smoothly linked. The axial chamfer size (C) is 0.5 to 1.0×the roller chamfer R size.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a roller bearing with a separate inner or outer ring, for example for use in industrial machinery and This relates to technology applied to motors for railway vehicles, etc. [Background technology]

[0002] There are bearings with separate inner and outer rings to make them easier to install in the machines they are used in. Examples of this type of bearing include cylindrical roller bearings and tapered roller bearings. A separate inner ring makes it easier to "shrink fit" the inner ring onto the shaft compared to the integral type. Similarly, a separate outer ring makes it easier to "shrink fit" the inner ring assembly onto the shaft compared to the integral type.

[0003] When assembling this type of separate inner or outer ring, there is a possibility that the raceway surface of the inner or outer ring may be damaged, so great care must be taken to eliminate any relative inclination of the inner or outer ring. If relative tilt of the inner or outer ring occurs, the edge at the boundary between the roller chamfer surface and the outer diameter surface may interfere with the raceway surface of the inner or outer ring, which may cause scratches on the raceway surface of the inner or outer ring.

[0004] To address this issue, an "assembly jig" is used to suppress the relative inclination of the inner or outer ring (for example, Patent Document 1). In addition, there are also some in which the cage has a special shape to suppress the relative inclination of the inner or outer ring (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2005-188590 A [Patent Document 2] JP 2015-98901 A Summary of the Invention [Problem to be solved by the invention]

[0006] The conventional solution of using an "assembly jig" requires the preparation of this part separately, which is inefficient. The solution of using a "specially shaped cage" requires the cage to have a complex shape, which may increase the manufacturing cost of the bearing. As shown in Fig. 9, after the bearing is installed in a machine, it may be moved in the axial direction C1 with the inner ring 50 or the outer ring 51 tilted. In this case, as shown in Figs. 10 and 11, there is a possibility that the raceway surface of the inner ring 50 or the raceway surface of the outer ring 51 (not shown) may be damaged. If the inner or outer ring tilts in this way after the bearing is assembled, there is a risk that the raceway surface and roller rolling surfaces of the inner or outer ring will be damaged even if the bearing is assembled in a conventional manner that prevents tilt.

[0007] An object of the present invention is to provide a roller bearing which can prevent damage to bearing components during installation and reduce manufacturing costs. [Means for solving the problem]

[0008] The roller bearing of the present invention comprises an inner ring, an outer ring, a plurality of rollers interposed between the inner ring and the outer ring, and a cage that holds these rollers, wherein an assembly of either the inner ring or the outer ring, the plurality of rollers, and the cage is axially separable from the other of the inner ring and the outer ring, The chamfer between the roller outer peripheral surface and the roller end face of each roller is rounded, and the axial chamfer dimension (C) of the chamfer is set to be equal to or smaller than the roller chamfer R dimension (R) to smoothly connect the roller chamfer surface and the roller outer peripheral surface. The "roller" is a cylindrical roller, a needle roller, or a tapered roller.

[0009] According to this configuration, the axial chamfer dimension (C) of the round chamfer of each roller is set to be equal to or smaller than the roller chamfer R dimension (R), so that the roller chamfer surface and the roller outer peripheral surface are smoothly connected. This makes it possible to prevent the formation of a sharp edge at the boundary between the roller chamfer surface and the roller outer peripheral surface. This makes it possible to prevent stress concentration at the edge of the inner and outer ring raceway surfaces when the bearing is assembled into a machine or when the bearing is moved axially after assembly. Therefore, it is possible to prevent assembly damage to the raceway surfaces of the inner and outer rings, which are bearing components, without using a conventional assembly jig or a special cage shape. This makes it possible to prevent assembly damage to bearing components and reduce manufacturing costs.

[0010] The axial chamfer dimension (C) may be 0.5 to 1.0 x roller chamfer R dimension. If the axial chamfer dimension (C) is less than 0.5 x roller chamfer R dimension, a sharp edge may be formed at the boundary between the roller chamfer surface and the roller outer circumferential surface. If the axial chamfer dimension (C) exceeds 1.0 x roller chamfer R dimension, a sharp edge may be formed at the boundary between the roller chamfer surface and the roller outer circumferential surface.

[0011] At least one of the rollers, the inner ring and the outer ring may be surface-treated. In this case, the sliding performance of the inner ring, the outer ring or the rollers can be improved and the bearing component can be more reliably prevented from being damaged during installation than in a bearing component that is not surface-treated.

[0012] The surface treatment may be a DLC coating or black dyeing. When the DLC coating is used, the wear resistance can be improved more than a surface treatment such as black dyeing. When the black dyeing is used, the manufacturing cost can be reduced more than other surface treatments. Effect of the Invention

[0013] In the roller bearing of the present invention, the chamfers of each roller are rounded and the axial chamfer dimension (C) of the chamfer is equal to or smaller than the roller chamfer R dimension, so that the roller chamfer surface and the roller outer circumferential surface are smoothly connected. This makes it possible to prevent scratches on the bearing components during assembly and reduce manufacturing costs. [Brief description of the drawings]

[0014] [Figure 1A] 1 is a vertical sectional view of a roller bearing etc. according to a first embodiment of the present invention. [Figure 1B] 5 is an explanatory diagram showing a process of installing the roller bearing into a machine. FIG. [Diagram 2] FIG. [Diagram 3] 3 is a partial enlarged view showing in detail a portion III in FIG. 2. [Figure 4] FIG. 13 is a partially enlarged view showing an example of surface treatment performed on the same roller. [Diagram 5] FIG. 2 is a schematic cross-sectional view showing the configuration of a DLC coating applied to the roller. [Figure 6] 4 is a partially enlarged view showing an example in which surface treatment is applied to the inner and outer rings and rollers of the roller bearing. FIG. [Figure 7A] FIG. 4 is a vertical sectional view of a roller bearing according to a second embodiment of the present invention. [Figure 7B] 4 is an explanatory diagram showing the process of assembling the roller bearing. FIG. [Figure 8] FIG. 11 is a vertical sectional view of a roller bearing according to a third embodiment of the present invention. [Figure 9] FIG. 1 is a cross-sectional view showing an example of installation of a conventional roller bearing in a machine. [Figure 10] FIG. 4 is a diagram showing installation scratches on the inner ring raceway surface of the roller bearing. [Figure 11] FIG. 11 is a partially enlarged view of a portion XI in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [First embodiment: NU type] A roller bearing according to an embodiment of the present invention will be described with reference to Figures 1A to 3. The roller bearing according to the embodiment is a single-row cylindrical roller bearing that is applied to motors for industrial machines and railway vehicles, for example. <Overview of cylindrical roller bearing> NU-type cylindrical roller bearing 10 shown in Fig. 1A comprises an inner ring 1, an outer ring 2, a number of cylindrical rollers 3 interposed between the raceway surfaces of the inner ring 1 and the outer ring 2, and a cage 4 that holds these cylindrical rollers 3. The inner ring 1 is ribless, and the outer ring 2 has ribs 2a, 2a on both axial sides of the raceway surface. Cylindrical roller bearing 10 is one of the so-called radial roller bearings in which the outer ring 2 is disposed radially outward from the outer circumferential surface of the inner ring 1. The axial direction of the central axes of the inner ring 1 and outer ring 2 is defined as the "axial direction" C1. The direction perpendicular to the "axial direction" C1 is defined as the "radial direction".

[0016] In a NU-type cylindrical roller bearing 10, as shown in Fig. 1B, an assembly 10A of an outer ring 2, multiple cylindrical rollers 3, and cage 4 is separable in the axial direction C1 from the inner ring 1. The cage 4 holds the multiple cylindrical rollers 3 at regular intervals in the circumferential direction. The cage 4 is, for example, a machined cage or a stamped cage. The cylindrical rollers 3 may be simply referred to as rollers 3.

[0017] <Detailed structure of roller chamfer> As shown in FIG. 2, the chamfer 7 between the roller outer peripheral surface 3a and the roller end surface 3b of each roller 3 is rounded. Furthermore, as shown in FIG. 3, the axial chamfer dimension (C) of the chamfer 7 is set to be equal to or smaller than the roller chamfer R dimension, smoothly connecting the roller chamfer surface 7a and the roller outer peripheral surface 3a. The roller chamfer R dimension of the rounded chamfer 7 is specified based on the allowable limit value rsmax of the measured chamfer dimension of a roller in JIS B 1506, which is in accordance with ISO 3096 of the International Organization for Standardization (abbreviated as ISO). The end surface shape of the roller 3 is a so-called flat shape. The contour of the roller chamfer R dimension is a rounded chamfer, and the center of the radius of curvature of this rounded chamfer is located inside the roller in FIG. 3. However, the roller chamfer R dimension may be a rounded chamfer that does not conform to JIS B 1506. The axial chamfer dimension (C) is set to be equal to or smaller than the roller chamfer R dimension, i.e., the axial chamfer dimension (C) ≒ the roller chamfer R dimension, and the roller outer peripheral surface 3a is made closer to the tangent line R. Specifically, (0.5 × roller chamfer R dimension) ≦ axial chamfer dimension (C) ≦ (1.0 × roller chamfer R dimension). The radial chamfer dimension (D7) of the round chamfer 7 is also specified in the same way.

[0018] <About the embedding process> As shown in Fig. 1B, assembly 10A in which cage 4 and rollers 3 are assembled to outer ring 2 is attached to housing 5. At this time, grease G has been applied to the bearing space. After that, inner ring 1, which has been attached to shaft 6 by press fitting or the like, is pressed axially into assembly 10A as shown in Fig. 1A, thereby assembling cylindrical roller bearing 10.

[0019] <Action and effect> According to the cylindrical roller bearing 10 described above, as shown in FIG. 3, the axial chamfer dimension (C) of the round chamfer 7 of each roller 3 is set to be equal to or smaller than the roller chamfer R dimension, smoothly connecting the roller chamfered surface 7a and the roller outer peripheral surface 3a. This makes it possible to prevent a sharp edge from being formed at the boundary 8 between the roller chamfered surface 7a and the roller outer peripheral surface 3a. This makes it possible to prevent stress concentration from occurring at the edge portions of the inner and outer ring raceway surfaces when the bearing 10 is assembled into a machine or when the bearing 10 is moved axially after assembly, as shown in FIG. 1B. Therefore, it is possible to prevent assembly damage to the raceway surfaces of the inner and outer rings 1 and 2, which are bearing components, without using a conventional assembly jig or a special cage shape. This makes it possible to prevent assembly damage to the bearing components and reduce manufacturing costs.

[0020] As shown in Figure 3, the axial chamfer dimension (C) = 0.5 to 1.0 x roller chamfer R dimension. If the axial chamfer dimension (C) is less than 0.5 x roller chamfer R dimension, there is a risk of a steep edge being formed at the boundary 8 between the roller chamfer surface 7a and the roller outer peripheral surface 3a. Similarly, if the axial chamfer dimension (C) exceeds 1.0 x roller chamfer R dimension, there is a risk of a steep edge being formed at the boundary 8 between the roller chamfer surface 7a and the roller outer peripheral surface 3a.

[0021] <Other embodiments, etc.> 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.

[0022] [Modification 1: DLC coating on rollers, Fig. 4, 5] As shown in FIG. 4, the outer peripheral surface 3a of the roller 3 is surface-treated with a multi-layered DLC coating 9. The roller end surface 3b does not have a DLC coating. However, the DLC coating 9 is not limited to a multi-layered structure, and may be, for example, a single-layer structure including DLC. The DLC coating 9 may also be formed on the chamfer 7 of the roller 3. For example, when the DLC coating 9 is formed on the outer peripheral surface 3a while the roller end surface 3b is masked, the DLC coating 9 is also formed around the chamfer 7. The DLC coating 9 shown in FIG. 4 is exaggerated to be thicker than the actual thickness. It is also possible to provide a DLC coating not only on the outer peripheral surface 3a of the roller 3 but also on the roller end surface 3b.

[0023] As shown in Fig. 5, when the DLC coating 9 has a multilayer structure, the DLC coating 9 has three layers, which are, in order from the base material side of the roller 3, a base layer 9a, a mixed layer 9b, and a surface layer 9c. The hardness of each of the layers 9a, 9b, and 9c in the DLC coating 9 having a multilayer structure increases stepwise from the outer layer side to the outer layer side. The DLC coating 9 has a three-layer structure including (1) a base layer 9a mainly made of Cr and WC that is formed directly on the outer circumferential surface 3a of the roller 3, (2) a mixed layer 9b mainly made of WC and DLC that is formed on the base layer 9a, and (3) a surface layer 9c mainly made of DLC that is formed on the mixed layer 9b. The mixed layer 9b is a layer in which the WC content in the mixed layer decreases and the DLC content in the mixed layer increases continuously or stepwise from the base layer 9a side to the surface layer 9c side. In this embodiment, the DLC coating 9 has a three-layer structure as described above, thereby preventing abrupt changes in physical properties (hardness, elastic modulus, etc.).

[0024] With this configuration, the sliding performance of the inner ring and rollers 3 is improved compared to bearing parts that have not been surface-treated, and assembly damage to the bearing part can be more reliably prevented without using conventional assembly jigs or special cage shapes, etc. When DLC coating 9 is formed so as to wrap around chamfer 7 of roller 3 as in Figure 4, it is possible to more reliably prevent the occurrence of assembly damage on the inner ring or outer ring raceway surface when assembling a cylindrical roller bearing, etc.

[0025] [Modification 2: DLC coating on inner and outer rings and rollers, Fig. 6] As shown in Figure 6, the DLC coating 9 may be applied to all of the rollers 3 and the inner and outer rings 1 and 2. The DLC coating 9 is formed individually for each bearing component. This modification 2 improves the sliding performance of the inner and outer rings 1 and 2 and the rollers 3, and makes it possible to more reliably prevent damage to the bearing components during assembly without using conventional assembly jigs or special cage shapes, etc.

[0026] [Variation 3: Black dyeing of inner and outer rings and rollers, Fig. 6] The surface treatment may be black dye 9A instead of DLC coating. When black dye 9A is used as the surface treatment for the bearing parts, the cost of equipment can be reduced compared to surface treatment equipment for DLC coating, etc., and the manufacturing cost can be reduced accordingly. Furthermore, the sliding performance of the inner and outer rings 1, 2 and the rollers 3 is improved, and scratches on the bearing parts during assembly can be more reliably prevented without using conventional assembly jigs or special cage shapes.

[0027] [Second embodiment: N type, Figs. 7A to 7B] In the N-type cylindrical roller bearing 10 shown in FIG. 7A, the outer ring 2 has no flange, and the raceway surface of the inner ring 1 has flanges 1a, 1a on both axial sides. In the N-type cylindrical roller bearing 10, as shown in FIG. 7B, an assembly 10B of the inner ring 1, a plurality of cylindrical rollers 3, and a cage 4 can be separated from the outer ring 2 in the axial direction. The detailed structure of the roller chamfer is the same as that of the first embodiment. In this cylindrical roller bearing 10, the cylindrical roller bearing 10 is assembled by pushing the outer ring 2 in the axial direction as shown in FIG. 7A into the assembly 10B in which the rollers 3 and the cage 4 are assembled into the inner ring 1. In this case, too, by making the detailed structure of the roller chamfer the same as that of the first embodiment, the same action and effect as that of the first embodiment can be achieved. In the second embodiment, it is also possible to perform surface treatment as in each of the modified examples.

[0028] [Third embodiment: tapered roller bearing, FIG. 8] As shown in FIG. 8, a tapered roller bearing 10 can also be applied as the roller bearing according to the embodiment. In this tapered roller bearing 10, an assembly of an inner ring 1, a plurality of tapered rollers 3, and a cage 4 can be separated in the axial direction from an outer ring 2. The detailed structure of the roller chamfer is similar to that of the first embodiment. In this case, too, by making the detailed structure of the roller chamfer similar to that of the first embodiment, the same effects as those of the first embodiment can be achieved. In the third embodiment, it is also possible to carry out surface treatments such as those in the respective modified examples.

[0029] As the roller bearing according to the embodiment, a needle roller bearing, a double row cylindrical roller bearing, or a four row cylindrical roller bearing may be used. A thrust roller bearing is not applicable. At least one of the rollers and the inner and outer rings may be subjected to a surface treatment. The roller bearings of each embodiment may be applied to applications other than motors for industrial machines and railway vehicles. As the surface treatment, in addition to DLC coating or black dyeing, it is also possible to apply a surface treatment that has the effect of improving the sliding performance of the inner and outer rings or rollers.

[0030] Although the embodiment of the present invention has been described above, the disclosed embodiment 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]

[0031] 1...inner ring, 2...outer ring, 3...roller, 3a...roller outer peripheral surface, 3b...roller end face, 4...retainer, 7...chamfer, 7a...roller chamfered surface, 9...DLC coating, 9A...black dyeing, 10...cylindrical roller bearing, 10A, 10B...assembly

Claims

1. A roller bearing comprising an inner ring, an outer ring, a plurality of rollers interposed between the inner ring and the outer ring, and a cage that holds these rollers, wherein an assembly of either the inner ring or the outer ring, the plurality of rollers, and the cage is axially separable from the other of the inner ring and the outer ring, a roller bearing in which the chamfer between the roller outer peripheral surface and the roller end face of each roller is rounded, and the axial chamfer dimension (C) of the chamfer is equal to or smaller than the roller chamfer R dimension, thereby smoothly connecting the roller chamfer surface and the roller outer peripheral surface.

2. 2. The roller bearing according to claim 1, wherein the axial chamfer dimension (C) = 0.5 to 1.0 x roller chamfer R dimension.

3. 3. A roller bearing according to claim 1, wherein at least one of said rollers, said inner ring and said outer ring is subjected to a surface treatment.

4. 4. The roller bearing according to claim 3, wherein the surface treatment is a DLC coating or a black dyeing.

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