Roller bearing

Abstract

To provide a roller bearing having improved assembling performance.SOLUTION: A roller bearing 50 includes: inner and outer rings 10, 20 that are one pair of bearing rings; a plurality of rollers 30 located between the inner and outer rings 10, 20 in a radial direction; and a cage 40 that holds the rollers 30. The roller bearing can be separated / assembled by causing an assembly 70 formed by combining one bearing ring 10 of the one pair, the plurality of rollers 30 and the cage 40 to move in an axial direction relatively to the other bearing ring 20 of the one pair. The other bearing ring 20 has a plurality of curved surface parts 131, 132, 133 that form a peripheral surface smoothly connecting a raceway surface 11 that defines a raceway of the roller 30 and a bearing ring end surface 12 thereof. The plurality of curved surface parts each have a round shape having different curvature radiuses. The plurality of curved surface parts are sequentially connected in the axial direction so that the curvature radius of the curved surface part becomes larger from the bearing ring end surface 12 toward the raceway surface 11.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a roller bearing that can be widely used in industrial machines such as compressors, etc. More specifically, the present invention relates to a technology that can improve the ease of assembly in a roller bearing having a lead in chamfer for assembly on either the inner or outer raceway. [Background technology]

[0002] Conventionally, in consideration of ease of assembly of roller bearings, a roller bearing in which a lead-in chamfer is provided on one of a pair of raceways has been put to practical use. This roller bearing can be separated and assembled by moving an assembly of one of the inner or outer raceways, the plurality of rollers, and the cage relative to the other raceway in the axial direction (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-45988 A [Patent Document 2] Japanese Patent Application Publication No. 11-82518 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the roller bearing described above, all parts must be assembled while keeping the axis of the rollers parallel to the axis of the pair of raceways (inner and outer rings). In addition, assembly must be performed while preventing the rollers of the roller bearing from being pushed radially inward or outward and falling out of the cage. Thus, in conventional roller bearings, each component must be assembled carefully and precisely, and there is room for improvement in terms of ease of assembly.

[0005] The cage provided in the cylindrical roller bearing of Patent Document 1 has multiple column sections connecting a pair of annular sections, with pockets formed between adjacent column sections in the circumferential direction. In order to suppress inclination of the cylindrical rollers in the axial direction, the distance between opposing roller stoppers sandwiching the pocket is set to less than the diameter of the cylindrical rollers.

[0006] The bearing cage of Patent Document 2 is provided with an extension portion that is formed by extending the inner diameter portion or the outer diameter portion of the annular portion in the radial direction and protruding further toward the inner diameter side or the outer diameter side than the column portion. Patent Document 2 describes that the radial movement of the rollers is regulated by setting the protruding direction of this extension portion to a predetermined direction.

[0007] However, when assembling the rollers, stress can still be concentrated on the edges of the rollers or the edges of the raceways due to misalignment of the axial directions of the various components, roller dropout, etc., and improvements to further improve assembly ease were desired.

[0008] Furthermore, if the axis of the roller is significantly misaligned with the axial direction of the raceway, or if the roller moves significantly in the radial direction (also called "drop"), there is a risk that the raceway end face of the inner or outer race will come into contact with the roller end face during assembly, making it impossible to assemble the bearing while maintaining such a positional relationship. Furthermore, if an attempt is made to forcibly assemble the bearing by applying a load to each component while maintaining the above positional relationship, there is a risk that the roller will fall off the cage.

[0009] In view of the above circumstances, an object of the present invention is to provide a roller bearing with improved assembly ease. [Means for solving the problem]

[0010] The roller bearing of the present invention comprises a pair of raceways, that is, inner and outer races, a number of rollers located radially between the inner and outer races, and a cage for retaining these rollers, and an assembly consisting of one of the pair of raceways, the number of rollers and the cage can be separated and assembled by moving it axially relative to the other of the pair of raceways, The other raceway of the pair has a plurality of curved surface portions that form a circumferential surface that smoothly connects between the raceway surface that defines the raceway of the rollers and the raceway end face, and the plurality of curved surface portions are R-shaped with different radii of curvature, and the plurality of curved surface portions are connected sequentially in the axial direction so that the radii of curvature of the curved surface portions increase from the raceway end face to the raceway surface, making this a roller bearing.

[0011] This configuration makes it possible to eliminate the edge on the raceway surface that would occur if the boundary between the raceway surface and the raceway end face of the other of the paired raceways were simply chamfered, while reducing the radial dimension of the raceway end face and reducing the risk of contact between the raceway end face and the roller end face, thereby preventing damage to the roller raceway surface due to the edge, and improving the ease of assembly of the roller bearing.

[0012] Preferably, in a roller bearing of the present invention, the plurality of curved surface portions have a first curved surface portion connected to the raceway end face and a second curved surface portion connected adjacent to the first curved surface portion in the axial direction, and a value (C / D) obtained by dividing a drop amount (C), which is the radial distance between a connection end portion connecting the first curved surface portion and the second curved surface portion and the raceway surface, by a diameter (D) of the roller, is 0.02 or more and 0.40 or less. With this configuration, the shape of the multiple curved portions can be appropriate taking into consideration the ratio to the radial dimension of the rolling element, and while the main part of the end face of the raceway is made a straight surface, the drop amount of the raceway end face is increased, making it easier to incorporate the raceway into the roller bearing.

[0013] Preferably, in the roller bearing of the present invention, the plurality of curved surface portions are arranged so that the surface roughness thereof increases from the raceway surface toward the raceway ring end surface. With this configuration, it is not necessary to polish the first curved surface portion with a grindstone or other means to the same extent as the surface roughness of the second curved surface portion, and the manufacturing process for the roller bearing can be simplified.

[0014] In this specification, "axial direction" refers to the inherent axial direction common to a pair of raceways when a roller bearing is ideally assembled with high precision, "circumferential direction" refers to the circumferential direction of an imaginary circle drawn about the axial direction, and "radial direction" refers to the radial direction linearly connecting the center of the imaginary circle and any point on the outer periphery of the imaginary circle in a plane perpendicular to the axial direction. Effect of the Invention

[0015] According to the present invention, it is possible to provide a roller bearing with improved assembly properties. [Brief description of the drawings]

[0016] [Figure 1] 1 is a vertical sectional view of a roller bearing according to one embodiment of the present invention; [Diagram 2] FIG. 2 is a view showing a main portion of the inner ring of the roller bearing. [Diagram 3] FIG. 2 is an enlarged cross-sectional view of a main portion of the inner ring of the roller bearing. [Figure 4] 4 is a schematic cross-sectional view showing the state in which an inner ring is attached to a subassembly that combines an outer ring, rollers, and a cage in the roller bearing. FIG. [Diagram 5] FIG. 13 is a view showing a main portion of an inner ring of a conventional roller bearing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] [First embodiment: NU type, Figs. 1 to 4] A roller bearing according to the present embodiment will be described with reference to the drawings. The roller bearing is used in industrial machinery such as compressors, for example. <General structure of roller bearing> 1 is a cross-sectional view showing a schematic configuration of a roller bearing 50 according to one embodiment of the present invention. The roller bearing 50 according to this embodiment is a cylindrical roller bearing, and includes an inner ring 10, an outer ring 20, a plurality of cylindrical rollers 30, and a cage 40.

[0018] In the following description, the terms "axial direction," "circumferential direction," and "radial direction" respectively refer to the directions defined in the above-mentioned means for solving the problems.

[0019] The roller bearing 50 in this embodiment is a NU type cylindrical roller bearing and comprises an inner ring 10 having an outer raceway surface 11 on its outer peripheral surface, an outer ring 20 having an inner raceway surface 21 on its inner peripheral surface, a plurality of cylindrical rollers 30 located radially between the inner and outer rings 10, 20 and arranged so as to roll freely between the inner and outer raceway surfaces 11, 21, and a retainer 40 that holds adjacent rollers 30, 30 while spacing them apart in the circumferential direction.

[0020] The inner ring 10 and the outer ring 20 form a pair of raceways. The outer ring 20 according to this embodiment has flanges 22 that protrude radially inward at both axial ends. The cage 40 has two annular members 41 provided on one side and the other side in the axial direction, and a plurality of column portions 42 that extend in the axial direction, both axial ends of which are connected to the annular members 41, 41, and are arranged at regular intervals in the circumferential direction. Each of a plurality of pockets defined by the annular members 41 and the column portions 42 adjacent in the circumferential direction accommodates one roller 30. In the roller bearing 50, the outer peripheral surface of each roller 30 rotates while contacting the inner and outer raceway surfaces 11, 21, so that each roller 30 revolves in the circumferential direction while rotating, thereby enabling the inner ring 10 and the outer ring 20 to rotate relatively.

[0021] When assembling a roller bearing having the above-mentioned configuration, for example, a cage and rollers are attached to one raceway to form a subassembly (assembly 70), and then the other raceway is attached to the subassembly from one axial side (or the other side). At that time, it is required to align the axis of the subassembly and the axis of the other raceway in a straight line, and to assemble carefully and precisely while preventing the rollers supported by the cage from being pushed radially inward or outward and falling out of the cage.

[0022] In this regard, in order to make it easier to align the axis of the subassembly with the axis of the other raceway ring and to prevent the rollers from falling off by reducing the risk of contact between the roller end face and the raceway ring end face, it is possible to consider cutting the boundary between the raceway surface and the raceway ring end face of the other raceway ring at an angle to the axial direction to form an inclined surface (tapered surface) and to give it a chamfered shape.

[0023] However, simply chamfering the boundary as shown in FIG. 5 does not ensure a sufficient drop amount at the raceway end face, so there is still a risk of contact between the roller end face and the raceway end face, and the connection (edge) between the chamfered portion and the raceway surface becomes sharp, which may result in poor assembly.

[0024] In contrast, in the roller bearing of this embodiment, the outer surface of the boundary connecting the raceway surface 11 and the end face 12 of the raceway ring 10 (hereinafter referred to as the raceway ring end face 12) is made into a unique curved shape to form a lead-in chamfer, thereby further reducing the risk of contact between the roller end face and the raceway ring end face and improving assembly ease.

[0025] The characteristic configuration of this embodiment will be described in more detail below with reference to Fig. 3. Fig. 3 is a cross-sectional view showing the shapes of outer raceway surface 11, raceway end face 12, and boundary portion 13 connecting these in a curved shape (curved shape in cross-sectional view).

[0026] The boundary portion 13 has a curved shape in which the outer surface (circumferential surface) gradually descends radially inward as it approaches the other axial side. The boundary portion 13 smoothly connects the outer raceway surface 11 and the flat raceway end surface 12, and connects the connection portion between the outer raceway surface 11 and the raceway end surface 12 so as to be rounded in cross section. The boundary portion 13 of this embodiment has a first curved surface portion 131, a second curved surface portion 132, and a third curved surface portion 133. The first curved surface portion 131, the second curved surface portion 132, and the third curved surface portion 133 of this embodiment are R-shaped with different radii of curvature. More specifically, the radius of curvature R2 of the second curved surface portion 132 is designed to be larger than the radius of curvature R1 of the first curved surface portion 131, and the radius of curvature R3 of the third curved surface portion 133 is designed to be larger than the radius of curvature R2 of the second curved surface portion 132. These curved surface portions 131, 132, 133 are sequentially connected in the axial direction in this order from the raceway end face 12 side. As a result, in the boundary portion 13 according to this embodiment, when viewed in a cross section along the axial direction, the radius of curvature of the curved surface portions 131, 132, 133 increases from the raceway end face 12 toward the outer raceway surface 11, thereby forming a lead-in chamfer.

[0027] More specifically, as shown in Fig. 2 and Fig. 3, the curved surface portions 131, 132, 133 are each an arc-shaped portion when the inner ring 10 (boundary portion 13) is viewed in a cross section along the axial direction. These arc-shaped portions are an arc of a first imaginary circle with a radius of R1, an arc of a second imaginary circle with a radius of R2, and an arc of a third imaginary circle with a radius of R3, respectively. A radially inner end of the first curved surface portion is connected to the outer edge portion of the raceway end face 12, a radially outer end of the first curved surface portion is connected to a radially inner end of the second curved surface portion, a radially outer end of the second curved surface portion is connected to a radially inner end of the third curved surface portion, and a radially outer end of the third curved surface portion is connected to an end portion on the other axial side of the outer raceway 11.

[0028] Here, the first curved surface portion and the second curved surface portion are smoothly connected, and the second curved surface portion and the third curved surface portion are also smoothly connected in the same manner. Also, since the radius R3 of the third virtual circle forming the third curved surface portion is larger than R2, it can be smoothly connected to the outer raceway surface 11, and no sharp edge or the like is formed at the boundary portion between the third curved surface portion 133 and the outer raceway surface 11.

[0029] Also, in the roller bearing 50 (FIG. 1) of the present embodiment, the surface roughness S1 of the first curved surface portion 131 is the same as or larger than the surface roughness S2 of the second curved surface portion 132. Similarly, the surface roughness S2 of the second curved surface portion 132 is larger than the surface roughness S3 of the third curved surface portion 133. That is, the surface roughness of the curved surface forming the boundary portion 13 satisfies the magnitude relationship of S3 < S2 ≤ S1, and the surface roughness becomes smaller as it approaches the outer raceway surface 11.

[0030] Specifically, the surface roughness is measured based on JIS B 0651 and is represented by the maximum roughness (Rmax), the arithmetic mean roughness (Ra), or the ten-point mean roughness (Rz). For example, the Ra of the surface roughness S1 of the first curved surface portion is 3.2 μm or more and 6.3 μm or less. The Ra of the surface roughness S2 of the second curved surface portion is 0.8 μm or more and 6.3 μm or less, and the Ra of the surface roughness S3 of the third curved surface portion is 0.8 μm or more and 1.6 μm or less. In this way, the outer surface of the inner ring 10 has a smaller surface roughness as it is closer to the outer raceway surface 11, that is, at the location where it is more likely to contact the roller 30 during assembly. The measurement location of the surface roughness is to measure any one location of each of the first curved surface portion, the second curved surface portion, and the third curved surface portion of the inner ring.

[0031] To describe the dimension setting of the boundary portion 13 in detail, as shown in Figs. 2 and 3, when viewed in a cross section along the axial direction, the value (C / D) obtained by dividing the drop amount, which is the radial distance C between the connection end Z where the first curved surface portion 131 and the second curved surface portion 132 are connected to each other and the outer raceway surface 11, by the diameter D of the roller 30 is preferably 0.02 or more and 0.40 or less, and more preferably 0.02 or more and 0.20 or less. If the value (C / D) is less than 0.02, the drop amount is insufficient, increasing the possibility that the roller 30 and the raceway end face will come into contact, making it difficult to assemble the raceway into the roller bearing. If the value (C / D) exceeds 0.40, the drop amount becomes excessive, and the radial dimension of the straight surface of the raceway end face 12 is insufficient, resulting in a sharp shape, which may scratch the roller 30 or adjacent members. By thus designing the shape of boundary portion 13 to satisfy the above-mentioned numerical range, it is possible to ensure the radial dimension of the straight surface of raceway end face 12 while avoiding contact between raceway end face 12 of inner ring 10 and roller end face 31.

[0032] <How to assemble roller bearings> The roller bearing 50 having the above-mentioned configuration has its individual components assembled through the assembly of subassemblies such as those shown in FIG. That is, first, the rollers 30 are accommodated in pockets defined between circumferentially adjacent column sections 42, 42 in the cage 40. This combination of the cage 40 and multiple rollers 30 is then assembled to the outer ring 20. Specifically, the outer ring 20 and the cage 40 are concentrically arranged, and the rollers 30 are press-fitted between the column sections 42 that are equally spaced along the circumferential direction, thereby forming an outer ring side sub-assembly 70 (assembled product) in which the rollers 30, cage 40, and outer ring 20 are combined.

[0033] Meanwhile, the shaft 60, which is a rotating object that rotates relative to the outer ring 20, is inserted into the insertion hole 14 of the inner ring 10, and the shaft 60 and the inner ring 10 are fixed to each other so that they cannot rotate relative to each other by a known method such as shrink fitting or press fitting. This combination of the shaft 60 and the inner ring 10 is moved from one axial side of the outer ring-side subassembly 70 so as to pass through the radial inside of the arrangement of the multiple rollers 30. This completes the assembly of the roller bearing 50, with the outer ring 20, the rollers 30 and the cage 40, and the inner ring 10 aligned in a straight line (radially) toward the radial inside.

[0034] 4, when the combination of shaft 60 and inner ring 10 is inserted into outer ring side subassembly 70 radially inward of the arrangement of multiple rollers 30, unless outer ring side subassembly 70 and rollers 30 are completely concentric, boundary portion 13 of inner ring 10 will collide with the corner (inner edge) between roller end face 31 and roller raceway surface 32 located on one axial side of roller 30. As a result, roller 30 is guided by boundary portion 13 and rides up onto outer raceway surface 11 of inner ring 10, completing the assembly of roller bearing 50.

[0035] <Action and effect> With the roller bearing 50 configured as described above, it is possible to reduce the radial dimension of the raceway end face 12 while blunting the edge portion on the raceway end face 12 that would arise if the boundary portion 13 between the outer raceway surface 11 and the raceway end face 12 on the other side of the inner ring 10 of the pair of raceways 10, 20 were simply chamfered.

[0036] More specifically, if the connection (corner) between the outer raceway surface and the raceway end face of one of the raceways is simply cut obliquely to form an inclined surface (tapered surface), a sharp edge will be generated at the boundary between this inclined surface and the raceway surface, as shown in Fig. 5. The outer surface of the inclined surface in cross section is shown by the two-dot chain line in Fig. 3. Since the inclination of this inclined surface is uniform at any position in the axial direction, if the angle X (Fig. 3) between the raceway surface and the inclined surface is designed to be small in order to blunt the edge, the drop of the raceway surface end face will be small, increasing the risk of contact between the raceway end face and the roller end face, which is thought to result in a decrease in ease of assembly.

[0037] In this regard, according to the roller bearing 50 of this embodiment, it is possible to increase the drop amount of the raceway end face 12 on the other axial side while making the edge of the boundary between the outer raceway surface 11 and the curved surface portion R3 which is closest to the outer raceway surface 11 among the multiple curved surface portions R1, R2, R3, and it is possible to improve the assemblyability of the roller bearing 50 while preventing damage to the roller raceway surface 32 by the edge.

[0038] <Modification> [Other embodiments: N-type, etc.] In the above embodiment, as shown in Figure 4, the inner ring 10 is assembled from the other axial side toward the hollow portion (radially inner) of the outer ring side subassembly 70 which combines the outer ring 20, a plurality of rollers 30, and a retainer 40, but this is not limited to this. Instead of the outer ring side subassembly, an inner ring side subassembly combining the inner ring 10, rollers 30, and cage 40, and another subassembly in which a cylindrical rotating object is attached to the radial outside of the outer ring 20 may be prepared first, and the other subassembly may be assembled to the inner ring side subassembly 80 from one axial side or the other side of the inner ring side subassembly. In other words, the roller bearing 50 is not limited to the NU type, but may also be applied to an N type roller bearing. In that case, the boundary portion 13 as shown in the above embodiment may be formed on the inner edge portion on the radially inner side of the outer ring 20, and the rib portion may be provided on the inner ring side instead of the outer ring side.

[0039] Furthermore, the roller bearing according to the present disclosure can also be applied to other types such as N type, NN type, NJ type, and NNU type.

[0040] In the above embodiment, boundary portion 13 in FIG. 3 has three curved portions (i.e., first to third curved portions 131, 132, 133), but this is not limited thereto, and boundary portion 13 may have four or more curved portions.

[0041] In the above embodiment, the roller bearing 50 is a cylindrical roller bearing, but this is not limiting. For example, the roller bearing 50 may be a needle roller bearing instead of a cylindrical roller bearing.

[0042] In the above embodiment, the boundary portion 13 is provided on one axial side of the inner ring 10, and no particular mention is made of the configuration on the other axial side. However, various modifications may be made, such as providing a positioning portion (protruding portion) that protrudes radially outward from the inner ring on the other axial side of the inner ring.

[0043] The roller bearing of each embodiment can also be applied to industrial machines, such as machine tools and robots, instead of compressors.

[0044] 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]

[0045] 10...Inner ring (other raceway ring) 11...Outer raceway surface 12...Rearing ring end face 13...Border 131...First curved surface part 132…Second curved surface part 133…Third curved surface part 14...Through hole 20…Outer ring (one of the raceways) 21...Inner raceway surface 22…Flange Around 30 31...Roller end face 32...Roller raceway surface 40...Cage 41...Ring member 42...Column part 50...Roller bearing 60...Shaft (rotating object) 70...Outer ring side sub-assembly (assembly)

Claims

1. A roller bearing comprising a pair of inner and outer raceways, a number of rollers located between the inner and outer raceways in the radial direction, and a cage for retaining these rollers, wherein an assembly of one of the pair of raceways, the number of rollers, and the cage can be separated and assembled by moving the assembly axially relative to the other of the pair of raceways, A roller bearing in which the other raceway of the pair has a plurality of curved surface portions forming a circumferential surface that smoothly connects between a raceway surface that defines the raceway of the roller and the raceway end face, the plurality of curved surface portions having R-shapes each having a different radius of curvature, and the plurality of curved surface portions are connected sequentially in the axial direction so that the radius of curvature of the curved surface portions increases from the raceway end face to the raceway surface.

2. 2. A roller bearing as described in claim 1, wherein the plurality of curved surface portions have a first curved surface portion connected to the raceway end face and a second curved surface portion connected adjacent to the first curved surface portion in the axial direction, and a value (C / D) obtained by dividing a drop amount (C), which is a radial distance between a connection end portion connecting the first curved surface portion and the second curved surface portion and the raceway surface, by a diameter (D) of the roller, is 0.02 or more and 0.40 or less.

3. 3. A roller bearing according to claim 1, wherein the plurality of curved surface portions are arranged such that the surface roughness of the curved surface portions increases from the raceway surface toward the raceway ring end surface.

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