Rolling bearing

Abstract

A rolling bearing is provided with a rolling body having a chamfered portion at an axial end portion. And the intersection part of the outer diameter surface of the rolling body and the chamfer part is of an anti-stripping structure. The anti-peeling structure is configured in such a manner that the intersecting portion is formed of a continuous curve.

Description

Technical Field

[0001] The present invention relates to a rolling bearing, and in particular to a rolling bearing having a rolling element having a chamfered portion at an axial end portion. Background Art

[0002] Previously, a method for manufacturing roller bearings that ensures sufficient lifespan (durability) even in the presence of foreign matter has been disclosed (Patent Document 1). In the roller bearing manufacturing method of Patent Document 1, prior to the hardening process in which each roller is subjected to collision within a container (drum), each roller is subjected to a chamfering process to form R-shaped chamfers at both axial end edges. This chamfering process prevents damage to the rolling surface of each roller even if the axial end edges of the roller collide with the rolling surface, thereby ensuring the required hardness, strength, toughness, and fatigue strength.

[0003] Furthermore, there is a conventional cylindrical roller (Patent Document 2) in which the roller is provided with a convex portion having a surface roughness greater than or equal to the surface roughness of the portion other than the convex portion. This configuration can suppress surface damage such as surface peeling between the roller and the supporting object.

[0004] Furthermore, a tapered roller bearing with a long life and high durability has been proposed, as described in Patent Document 3. This tapered roller bearing includes a contact portion convex surface that makes surface contact with the inner ring raceway and a non-contact portion convex surface that does not. The shapes of the contact portion convex surface and the non-contact portion convex surface are represented by different functions, forming smoothly connected curves (continuous curves), and the curvature of the non-contact portion convex surface is set to be smaller than that of the contact portion convex surface.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-14126

[0008] Patent Document 2: Japanese Patent No. 4075364

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2021-105451 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] Typically, the rollers of cylindrical roller bearings and tapered roller bearings have chamfers (hereinafter referred to as chamfers) at the intersection of the rolling surface and the axial end edges. These chamfers are usually formed by forging (cold heading, upsetting) or turning before heat treatment of the rollers. Furthermore, as described in Patent Document 1, the chamfers are also processed by barrel polishing.

[0012] However, when using roller bearings, the chamfered portion often does not contact the rolling surfaces of the inner and outer rings. This is because, as described in Patent Documents 2 and 3, roller bearings sometimes have convex surfaces near the ends of the rolling surfaces of the inner and outer rings, or near the ends of the rollers. When such bearings are used under normal loads (the loads assumed during design), the ends of the rolling contact surfaces of the raceway ring and the roller do not directly contact each other. However, providing convex surfaces on the rollers increases processing time, reduces productivity, and leads to increased costs.

[0013] There are cases where convexity is not set and Figure 21 Even if there is a convex surface as shown, sometimes the end of the rolling surface of the roller contacts the track surface of the raceway ring depending on the load conditions. Figure 20 In that case, the chamfered portion 4 may also come into contact with the raceway surface 3a due to the elastic deformation of the rolling surface 2 and the roller 1. In this case, if the surface properties of the chamfered portion 4 are inappropriate, it may come into contact with the raceway surface 3a of the raceway ring 3 without passing through the oil film (metal contact), which may cause surface damage to the raceway ring 3.

[0014] And, as Figure 21 In that case, when the boundary 5 between the rolling surface 2 of the roller 1 and the chamfered portion 4 (hereinafter referred to as the chamfered connection portion) is a discontinuous shape, the edge stress increases compared to the case where the connection portion is a continuous shape, thereby increasing the risk of peeling at the end of the raceway ring 3 and the roller.

[0015] Therefore, the present application provides a rolling bearing that can effectively prevent separation near the chamfered connection portion, which is a portion where the outer diameter surface and the chamfered portion intersect.

[0016] Means for solving problems

[0017] The first rolling bearing of the present invention is a rolling bearing having a rolling element, which has a chamfered portion at the axial end, and is characterized in that the portion where the outer diameter surface of the rolling element intersects with the chamfered portion is an anti-peeling structure, and the anti-peeling structure is formed by a continuous curve, and the continuous curve is as follows: the positions of the endpoints of the function representing the outer diameter surface of the rolling element and the function representing the chamfered portion are consistent at the intersection, and can be differentiated at the intersection.

[0018] In the first rolling bearing of the present invention, the anti-stripping structure is formed by forming the intersection of the outer diameter surface of the rolling element and the chamfered portion as a continuous curve. This effectively prevents stripping near the chamfered connection portion, where the outer diameter surface of the rolling element and the chamfered portion intersect. Furthermore, since the intersection is formed as a continuous curve, damage to the mating surfaces (the raceways of the bearing inner and outer rings) (primarily the formation of surface indentations, plastic deformation, and structural changes below the contact surface) can be prevented.

[0019] The descending amount of the chamfered portion of the rolling element may be set to be less than 2% of the chamfered length at a position 1 / 20 of the chamfered length along the outer diameter surface of the rolling element.

[0020] The descending amount of the chamfered portion of the rolling element may be set to be 4% or less of the chamfered length at a position 1 / 10 of the chamfered length along the outer diameter surface of the rolling element.

[0021] Alternatively, the amount of descent of the chamfered portion of the rolling element may be set so that at a position 1 / 20 of the chamfered length along the outer diameter surface of the rolling element, the amount of descent is no more than 2% of the chamfered length, and at a position 1 / 10 of the chamfered length along the outer diameter surface of the rolling element, the amount of descent is no more than 4% of the chamfered length. This setting enables a more stable and smoother formation of a continuous curve.

[0022] Alternatively, the rolling elements may be processed to reduce surface roughness. This structure, in which surface roughness reduction processing has been applied, can suppress surface-origin damage such as micropitting on the mating surfaces (the rolling contact surfaces between the bearing inner and outer rings, which form the raceway). Micropitting refers to fine pitting on the contacting surfaces caused by plastic flow on the surface roughness due to repeated cyclical contact stress. Furthermore, pitting refers to damage resulting from fatigue failure of the material, creating spotty micropores.

[0023] The second rolling bearing of the present invention is a rolling bearing having a rolling element, which has a chamfered portion at the axial end, and is characterized in that the portion where the outer diameter surface of the rolling element intersects with the chamfered portion is an anti-peeling structure, a convex surface is formed on the outer diameter surface of the rolling element, and the anti-peeling structure is formed by performing processing to reduce the surface roughness, and the lowering amount of the chamfered portion of the rolling element at a position of 1 / 20 of the chamfer length along the convex portion direction of the chamfered portion is less than 2% of the chamfer length along the convex portion direction of the chamfered portion.

[0024] In the second rolling bearing of the present invention, processing is implemented to reduce the surface roughness, and the reduction amount of the chamfered portion of the rolling body at a position of 1 / 20 of the chamfered length along the convex portion direction of the chamfered portion is less than 2% of the chamfered length. Therefore, even if the portion where the outer diameter surface of the rolling body intersects with the chamfered portion is a discontinuous curve, peeling near the portion where the outer diameter surface of the rolling body intersects with the chamfered portion, that is, the chamfered connection portion, can be prevented.

[0025] Effects of the Invention

[0026] The present invention prevents peeling near the chamfered connection, where the outer diameter surface of the rolling element intersects the chamfered portion, thereby providing a rolling bearing with excellent durability. Furthermore, it prevents damage to the mating surfaces (the raceways of the inner and outer rings) (primarily surface indentation, plastic deformation, and structural changes beneath the contact surface), thereby extending the life of the entire bearing. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic cross-sectional view of the rolling bearing of the present invention.

[0028] Figure 2 This is a simplified diagram showing the relationship between a roller without a convex portion and a raceway ring.

[0029] Figure 3 This is an enlarged schematic diagram of the main parts of the roller.

[0030] Figure 4 This is a simplified diagram showing the relationship between a roller having a convex portion and a raceway ring.

[0031] Figure 5 This is a schematic cross-sectional view of another rolling bearing according to the present invention.

[0032] Figure 6 It is a schematic diagram showing the dimensions of the chamfered portion of the test piece A.

[0033] Figure 7 Graph showing the amount of drop in the chamfered portion of test piece A.

[0034] Figure 8 This is a schematic diagram showing the dimensions of the chamfered portion of test piece B.

[0035] Figure 9 Graph showing the amount of drop in the chamfered portion of test piece B.

[0036] Figure 10 This is a photograph of the surface of test piece A-1 after the test.

[0037] Figure 11 This is a photograph of the surface of test piece A-2 after the test.

[0038] Figure 12This is a photograph of the surface of test piece A-3 after the test.

[0039] Figure 13 This is a photograph of the surface of test piece B-1 after the test.

[0040] Figure 14 This is a photograph of the surface of test piece B-2 after the test.

[0041] Figure 15 This is a photograph of the surface of the target material of Test Specimen A-1 after the test.

[0042] Figure 16 This is a photograph of the surface of the target material of Test Specimen A-2 after the test.

[0043] Figure 17 This is a photograph of the surface of the target material of Test Specimen A-3 after the test.

[0044] Figure 18 This is a photograph of the surface of the target material of Test Specimen B-1 after the test.

[0045] Figure 19 This is a photograph of the surface of the target material of test piece B-2 after the test.

[0046] Figure 20 This is a simplified diagram showing the relationship between the roller and the raceway ring, which shows the existing shortcomings.

[0047] Figure 21 This is a simplified diagram showing the relationship between the roller and the raceway ring, which reveals other existing shortcomings. DETAILED DESCRIPTION

[0048] The following, according to Figures 1 to 19 Embodiments of the present invention will be described. Figure 1 A schematic cross-sectional view shows a rolling bearing according to the present invention, which is a cylindrical roller bearing comprising: an inner ring 11 having a raceway 10 on its outer diameter surface, constituting one raceway ring; an outer ring 13 having a raceway 12 on its inner diameter surface, constituting the other raceway ring; cylindrical rollers 14, serving as rolling elements, interposed between raceway 10 of inner ring 11 and raceway 12 of outer ring 13; and a retainer 15 for retaining cylindrical rollers 14. The cylindrical roller bearing shown in this illustration is a so-called NU-type cylindrical roller bearing, having a pair of flanges 16, 16 on the inner diameter surface of outer ring 13 and no flange on the outer diameter surface of inner ring 11.

[0049] In this bearing, Figure 2As shown, a chamfered portion 20 is provided at the axial end portion, and the intersection 21 of the rolling element outer diameter surface (roller outer diameter surface) and the chamfered portion 20 forms an anti-stripping structure M. In this case, the anti-stripping structure M is formed by forming the intersection 21 with a continuous curve. Here, a continuous curve means that at the intersection 21, the endpoints of the function representing the rolling element outer diameter surface and the function representing the chamfered portion 20 coincide with each other, and that differentiation is possible at the intersection 21.

[0050] In this case, the amount of descent Da of the chamfered portion 20 of the rolling element (roller 14) is less than 2% of the chamfered length at a position of 1 / 20 of the axial chamfered length of the chamfered portion 20 (the chamfered length L of the chamfered portion 20 along the roller outer diameter surface 17), or further less than 0.5% of the chamfered length. That is, when the length of the chamfered portion 20 along the outer diameter surface is L, at the position of L / 20, the amount of descent Da2 is less than L×0.02, or the amount of descent Da2 is less than L×0.005. Here, regarding the chamfered portion 20 along the roller outer diameter surface 17, if Figure 3 The extended line E along the outer diameter surface shown is defined as the X-axis direction, and the drop amount Da refers to the length in the Y-axis direction perpendicular to the X-axis direction.

[0051] Furthermore, at a position that is 1 / 10 of the axial chamfer length of the chamfered portion (the chamfer length of the chamfered portion 20 along the roller outer diameter surface 17), the chamfer length is 4% or less, or 1% or less of the chamfer length. In other words, when the length of the chamfered portion 20 along the outer diameter surface is L, the drop Da1 is L x 0.04 or less. Alternatively, the drop Da1 is L x 0.01 or less. The drop Da also represents the length in the Y-axis direction, which is perpendicular to the X-axis direction.

[0052] By setting the drop amount Da in this manner, the intersecting portion 21 can be formed by a continuous curve. It is particularly preferable to set the drop amount Da1 at the L / 10 position and the drop amount Da2 at the L / 20 position. However, it is also possible to set only the drop amount Da1 at the L / 10 position and only the drop amount Da2 at the L / 20 position.

[0053] Furthermore, the roller 14 preferably achieves improvement of the surface properties of the chamfered portion 20 (reduction of surface roughness) by roller processing or lapping process. Here, roller processing refers to the following processing: abrasive, workpiece and working fluid are placed in a container called a roller (barrel), and the surface is finished by rotating or vibrating it. Therefore, there are rotary roller grinders, mechanical vibration roller grinders and centrifugal roller grinders, etc. as roller processing machines. Any of these machines can be used. Furthermore, lapping process refers to the following free abrasive processing: sliding motion (mutual friction) is performed in a state containing free abrasive (abrasive), while performing micro-cutting on the workpiece and grinding it, thereby gradually finishing the workpiece to be flatter.

[0054] According to the present invention, by forming the intersecting portion 21 by a continuous curve, peeling near the chamfered connection portion where the outer diameter surface of the rolling element (roller outer diameter surface 17) intersects with the chamfered portion 20 can be effectively prevented, thereby providing a rolling bearing with excellent durability.

[0055] By setting the descending amount Da of the chamfered portion 20 of the rolling element (roller 14) to be 2% or less of the chamfered length L at a position 1 / 20 of the chamfered length L along the roller outer diameter surface 17, a continuous curve can be stably formed.

[0056] Alternatively, the descending amount Da of the chamfered portion 20 of the rolling element (roller 14) may be set to be 4% or less of the chamfered length L at a position 1 / 10 of the chamfered length L along the roller outer diameter surface 17 of the chamfered portion 20. This setting allows for more stable formation of a continuous curve.

[0057] Alternatively, the amount of depression Da of the chamfered portion 20 of the rolling element (roller 14) may be set to be 2% or less of the chamfered length L at a position 1 / 20 of the chamfered length L along the roller outer diameter surface 17 of the chamfered portion 20, and to be 4% or less of the chamfered length L at a position 1 / 10 of the chamfered length L along the roller outer diameter surface 17 of the chamfered portion 20. By setting this, a continuous curved line can be formed more stably and smoothly.

[0058] The rolling elements (rollers 14) can also be machined to reduce surface roughness. This process can suppress surface-origin damage, such as micropitting, on the target surfaces (the rolling contact surfaces between the bearing inner and outer races). Micropitting refers to tiny pitting on the contacting surfaces caused by plastic flow on the surface roughness due to repeated cyclical contact stress. Furthermore, pitting refers to damage resulting from fatigue failure of the material, creating spotty micropores.

[0059] Next, Figure 4The roller 14 is shown with a convex portion 22. In this case, the portion 21a where the convex portion 22 and the chamfered portion 20 of the outer diameter surface 17 intersect forms an anti-stripping structure M. Furthermore, surface roughness reduction processing is performed. This surface roughness reduction processing is performed by, for example, the aforementioned roller processing or grinding. In this case, assuming the curvature radius (convex radius) of the convex portion 22 is r and the curvature radius (chamfered radius) of the chamfered portion 20 is R, r = approximately 100R to 20,000R.

[0060] Furthermore, the drop Db is based on the extension line E1 of the convex portion 22. Specifically, let the length of the chamfered portion 20 along this extension line E be L1. At a position L1 / 20 from the intersection 21a where the convex portion 22 and the chamfered portion 20 intersect, the dimension of the chamfered portion 20 from the extension line E1 (drop Db2) is set to be no greater than L1 × 0.02, and further set to no greater than L1 × 0.005. This extension line E1 is tilted at an angle (inclination angle) θ relative to the extension line E of the roller outer diameter surface 17 in the absence of the convex portion 22. The angle (inclination angle) θ is, for example, approximately 0.005° to 1.0°. Therefore, if the extension line E1 of the convex portion 22 is in the X'-axis direction, the drop in this case is the length in the Y'-axis direction, which is perpendicular to the X'-axis direction. In other words, the extension line E1 is tilted by θ relative to the extension line E, and the Y'-axis direction, the direction of drop, is tilted by θ relative to the Y-axis direction.

[0061] The length of the chamfered portion 20 along the extension line E1 is set to L1, and the dimension (drop amount Db1) from the extension line E1 to the chamfered portion at a position L2 / 10 from the intersection 21a where the convex portion 22 and the chamfered portion 20 intersect is set to be less than L1×0.04, and further set to be less than L1×0.01.

[0062] In this case, the position of L1 / 20 may be set to L1×0.02 or less, or the position of L1 / 10 may be set to L1×0.04 or less, or both positions may be used.

[0063] By configuring in this way, even if the convex portion 22 is provided, the same effect as that of a device without a convex portion can be achieved. Figure 2 The same effect is achieved with the roller bearing shown.

[0064] Next, Figure 5The tapered roller bearing shown here includes an inner ring 31 having a conical raceway surface 30 on its outer circumference; an outer ring 33 having a conical raceway surface 32 on its inner circumference; a plurality of tapered rollers 34 assembled between the two raceways 30 and 32; and a cage 35 that houses the tapered rollers 34. In this case, a small-diameter flange portion 36 and a large-diameter flange portion 37 are formed on the inner ring 31.

[0065] like Figure 2 As shown, the tapered roller 34 also has chamfered portions 40, 40 at its axial end portions, and a portion 41 where the roller outer diameter surface 38 and the chamfered portions 40, 40 intersect is a separation prevention structure M. In this case, the separation prevention structure M is formed by forming the intersecting portion 41 with a continuous curve.

[0066] In this case, the intersecting portion 41 formed by the continuous curved line on the small and large diameter sides of the tapered roller 34 also constitutes the peeling prevention structure M. Furthermore, the amount of depression Da of the chamfered portion 40 of the rolling element (tapered roller 34) is 1 / 20 of the chamfered length L along the outer diameter surface 38 of the chamfered portion 40, which is 2% or less of the chamfered length L along the outer diameter surface 38, or further, 0.5% or less of the chamfered length L. In other words, when the length of the chamfered portion 40 along the outer diameter surface 38 is L, at the position L / 20, the amount of depression Da2 is L×0.02 or less, or L×0.005 or less.

[0067] Furthermore, the amount of depression Da of the chamfered portion 40 of the rolling element (tapered roller 34) is 4% or less of the chamfered length L along the outer diameter surface 38 at a position where the chamfered portion 40 is 1 / 10 of the chamfered length L along the outer diameter surface 38, or further, is 1% or less of the chamfered length L. That is, when the length of the chamfered portion 40 along the outer diameter surface 38 is L, at a position where L / 10, the amount of depression Da1 is L×0.04 or less, or L×0.01 or less.

[0068] Furthermore, the tapered roller may have a convex portion 42. In this case, the drop D is based on the extension line E of the convex portion 42. Specifically, the length of the chamfered portion 40 along the extension line E is defined as L1. At a position L1 / 20 from the intersection 21a where the convex portion 42 and the chamfered portion 40 intersect, the dimension (drop b2) from the extension line E to the chamfered portion 40 is set to be L1 × 0.02 or less, or further, L1 × 0.005 or less.

[0069] The length of the chamfered portion 40 along the extension line E is set to L1, and the dimension (drop amount b1) from the extension line E to the chamfered portion 40 at a position L1 / 10 from the intersection 21a where the convex portion 42 and the chamfered portion 40 intersect is set to less than L1×0.04, and further set to less than L1×0.015.

[0070] In this case, the descent amount Db2 at the position of L1 / 20 may be set to L1×0.02 or less, or the descent amount Db1 at the position of L1 / 10 may be set to L1×0.04 or less, or both positions may be used.

[0071] Therefore, even if Figure 5 The tapered roller bearing shown here features an anti-peeling structure M on the tapered rollers 34, which serve as rolling elements. This prevents peeling near the chamfered connection, resulting in a rolling bearing with excellent durability. Furthermore, damage to the mating surfaces (the raceways of the inner and outer rings) (primarily surface indentation, plastic deformation, and structural changes below the contact surface) is prevented, extending the life of the entire bearing.

[0072] The above describes the embodiments of the present invention, but the present invention is not limited to the above embodiments and can be modified in various ways. For cylindrical rollers and tapered rollers serving as rolling elements, as a process for reducing surface roughness, in addition to roller processing and grinding processing, shot peening (a method of processing a workpiece by causing particles called projection materials to collide with the workpiece (workpiece)) or grinding using a grinding wheel can also be used.

[0073] In addition, as a cylindrical roller bearing, an outer ring with double flanges (NU type) is shown in the embodiment, but it is not limited to this. Various well-known bearing forms can be adopted, such as an inner ring with double flanges (N type), an outer ring with double flanges (NU type), an inner ring with double flanges and an outer ring with a single flange (NF type), an inner ring with a single flange and an outer ring with double flanges (NJ type), and an inner ring with a double flange with one side being a separate flange ring and an outer ring with double flanges (NUP type).

[0074] These bearings can be multi-row cylindrical roller bearings, multi-row tapered roller bearings, or needle roller bearings. They are used in a variety of general machinery, electrical machinery, industrial machinery, conveying machinery, and vehicles.

[0075] Example 1

[0076] Rollers made of SUJ2 with different shapes of chamfered joints and finished parts (hereinafter referred to as test pieces) were made and subjected to rolling fatigue tests. The test piece size was 12mm in outer diameter, and the shapes of the chamfered joints of test pieces A and B were different. Figure 6As shown in FIG. 1 , the chamfered connection portion 21 of the test piece A (A-1 to A-3) is composed of a discontinuous curve. In this case, the chamfer length L of the chamfered portion 20 is 1.2 mm, and the curvature radius R of the chamfered portion 20 is 3 mm. Figure 8 As shown, the chamfered connection portion 21 of the test piece B (B-1, B-2) is composed of a continuous curved line. In this case, the chamfer length L of the chamfered portion 20 is 1.5 mm, and the curvature radius R of the chamfered portion 20 is 3 mm.

[0077] exist Figure 6 The dimensions of the chamfered connection portion of each test piece A are shown in Figure 8 The shape of the chamfered portion of each test piece A is shown in FIG. Figure 7 The dimensions of the chamfered connection portion of each test piece B are shown in Figure 9 The shapes of the chamfered portions of each test piece B are shown in the figure. These test pieces were placed in contact with a 20 mm diameter counterpart material simulating a bearing raceway, and the damage state of the counterpart material's rolling contact surface was observed after a rolling fatigue test. Table 1 shows the test conditions and test piece details for test pieces A-1, A-2, and A-3.

[0078] [Table 1]

[0079] Test conditions and test piece details for test piece A

[0080]

[0081] In the test pieces A-1, A-2, and A-3, the pressure Pmax at the center of the test piece was 3200 MPa, and the number of tests was 10. 6 times, the object load times is (3×10 5 ) times, turbine oil (VG56) was used as the lubricant, the oil film parameter Λ was greater than 3, the chamfered connection was discontinuous, the drop at the L / 20 position was -0.0352mm (2.93% of L), and the drop at the L / 10 position was -0.0729mm (6.07% of L). Test piece A-1 maintained its upset state, test piece A-2 was shot peened, and test piece A-3 was ground. Furthermore, the surface roughness Ra of the chamfered portion of test piece A-1 was 0.8μm, the surface roughness Ra of the chamfered portion of test piece A-2 was 1.3μm, and the surface roughness Ra of the chamfered portion of test piece A-3 was 0.7μm. The surface roughness Ra of the raceway surface of the counterpart material was 0.04μm.

[0082] The test conditions and test piece details of test pieces B-1 and B-2 are shown in Table 2. In test pieces B-1 and B-2, the pressure Pmax at the center of the test piece was 3200 MPa, and the number of tests was 10.6 times, the object load times is (3×10 5 ) times, using turbine oil (VG56) as the lubricant, with an oil film parameter Λ of 3 or greater. The chamfered joint was continuous, with a drop of -0.00091 mm (0.06% of L) at the L / 20 position and -0.00375 mm (0.25% of L) at the L / 10 position. Test piece B-1 was ground, while test piece B-2 was shot peened. The surface roughness Ra of the chamfered portion of test piece B-1 was 0.2 μm, while that of test piece B-2 was 1.3 μm. The surface roughness Ra of the raceway surface of the counterpart material was 0.04 μm.

[0083] [Table 2]

[0084] Test conditions and test piece details for test piece B

[0085]

[0086] exist Figure 10 The surface photograph of the test piece A-1 after the test is shown in FIG. Figure 11 The surface photograph of the test piece A-2 after the test is shown in FIG. Figure 12 Surface photos of test piece A-3 after the test are shown in the figure. From these surface photos, it can be seen that in test pieces A-1 and A-2, peeling with a length of more than 200 μm occurred near the chamfered connection. Although tiny peeling of about 20 μm can be observed sporadically in test piece A-3, it is believed that this will not hinder the function as a rolling component. In addition, no large peeling occurred in test piece A-3 because the corners of the chamfered connection were removed by grinding, and the stress concentration was alleviated.

[0087] exist Figure 13 The surface photograph of the chamfered connection portion of the test piece B-1 after the test is shown in FIG. Figure 14 A surface photograph of the chamfered connection portion of test piece B-2 after the test is shown in Figure 2. No peeling occurred in test pieces B-1 or B-2. This is because the chamfered connection portion is formed by a continuous curve, which alleviates stress concentration.

[0088] exist Figure 15 The surface photograph of the test piece A-1 after the test is shown in FIG. Figure 16 The surface photograph of the test piece A-2 object material after the test is shown in FIG. Figure 17 The surface photograph of the test piece A-3 after the test is shown in FIG. Figure 18 The surface photograph of the test piece B-1 after the test is shown in FIG. Figure 19 A photograph of the surface of the test piece B-2 after the test is shown in . Each observation location is near the position where the chamfered connection portion of the test piece contacts.

[0089] In the tests using test pieces A-1 and A-2, the surface of the target material produced plastic deformation (indentation) and surface roughness due to contact with the chamfered portion. This surface roughness evolved into cracking and ultimately delamination as the number of loads increased. In the test using test piece A-3, the surface of the target material produced plastic deformation (indentation) due to contact with the chamfered portion, but no cracking was confirmed.

[0090] In the test using test piece B-1, slight plastic deformation (indentation) due to high surface pressure occurred, but no surface roughness was observed. In the test using test piece B-2, slight plastic deformation (indentation) due to high surface pressure occurred, and microcracks associated with surface-origin damage were confirmed. The indentation depth was (test pieces B-1, B-2) < (test pieces A-1, A-2, A-3).

[0091] The test results are summarized below.

[0092] (a) If the chamfered connection portion is formed by a continuous curve as in test pieces B-1 and B-2, the indentation on the target surface (raceway surface of the bearing inner and outer rings) can be minimized.

[0093] (b) By alleviating the discontinuous shape of the chamfered connection portion by polishing or the like, as in at least Test Specimen A-3, the formation of indentations can be reduced, and peeling near the chamfered connection portion can be suppressed.

[0094] (c) By reducing the surface roughness of the chamfered portion through grinding or lapping, it is possible to suppress surface damage such as micropitting on the target surface (raceway surfaces of the bearing inner and outer rings).

[0095] Industrial applicability

[0096] A rolling bearing having rolling elements with an anti-stripping structure at the intersection of the outer diameter surface and the chamfered portion of the axial end. This bearing can be a multi-row cylindrical roller bearing, a multi-row tapered roller bearing, or a needle roller bearing incorporating needle rollers. It can be used in various general machinery, electrical machinery, industrial machinery, conveying machinery, and vehicles.

[0097] Description of labels

[0098] 14: rolling element (roller); 17: outer diameter surface of rolling element (outer diameter surface of roller); 22: convex portion; 30, 32: raceway surface; 31: inner ring; 33: outer ring; 35: retainer; 38: outer diameter surface of rolling element (outer diameter surface of roller); 40, 40: chamfered portion; 41: intersecting portion (connecting portion); 42: convex portion.

Claims

1. A rolling bearing comprising a rolling element having a chamfered portion at an axial end portion, wherein: The portion where the outer diameter surface of the rolling element intersects with the chamfered portion is an anti-peeling structure, and the anti-peeling structure is formed by a continuous curve, which is as follows: the positions of the endpoints of the function representing the outer diameter surface of the rolling element and the function representing the chamfered portion are consistent at the intersection, and can be differentiated at the intersection.

2. The rolling bearing according to claim 1, characterized in that The amount of depression of the chamfered portion of the rolling element is 2% or less of the chamfered length at a position that is 1 / 20 of the chamfered length along the outer diameter surface of the rolling element.

3. The rolling bearing according to claim 1, characterized in that The amount of depression of the chamfered portion of the rolling element at a position that is 1 / 10 of the chamfered length along the outer diameter surface of the rolling element is 4% or less of the chamfered length.

4. The rolling bearing according to claim 1, characterized in that The amount of descent of the chamfered portion of the rolling element is less than 2% of the chamfered length at a position of 1 / 20 of the chamfered length along the outer diameter surface of the rolling element, and is less than 4% of the chamfered length at a position of 1 / 10 of the chamfered length along the outer diameter surface.

5. The rolling bearing according to any one of claims 1 to 4, characterized in that The rolling elements are processed to reduce surface roughness.

6. A rolling bearing comprising a rolling element having a chamfered portion at an axial end portion, wherein: The portion where the outer diameter surface of the rolling element intersects with the chamfered portion is an anti-peeling structure, a convex surface is formed on the outer diameter surface of the rolling element, and the anti-peeling structure is formed by performing processing to reduce the surface roughness, and the lowering amount of the chamfered portion of the rolling element at a position of 1 / 20 of the chamfer length along the convex portion direction of the chamfered portion is less than 2% of the chamfer length along the convex portion direction.

Images