Roller bearing and method for designing roller bearing

Abstract

To provide a roller bearing with a long life and a method for designing a roller bearing by suppressing wear generated on the a roller end surface, a flange surface, etc., even in the case of using a standard roller bearing.SOLUTION: The hardness of a cylindrical roller 30 is larger than the hardness of an inside surface 14 of a flange part 12, and a chamfer dimension C in a direction along the inside surface 14 of the flange part 12 of a chamfer part 17 provided at a corner between a radial tip of the flange part 12 and the inside surface 14 of the flange part 12 is 0.2 mm or more, and satisfies the mathematical formula (1), where Dw is a diameter dimension (mm) of the roller 30, and in the case of a conical roller bearing 1, is a large diameter dimension (mm).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a roller bearing and a method for designing a roller bearing. [Background technology]

[0002] Cylindrical roller bearings and tapered roller bearings are equipped with ribs on the raceway or flange ring to hold the rollers in the raceway groove and guide them in the direction of revolution. In particular, the rib surface of a cylindrical roller bearing that can withstand axial loads, such as the NJ type, which has two ribs on the outer ring and one on the inner ring as shown in Figure 6, or the NF type, which has one rib on the outer ring and two ribs on the inner ring, or the large rib surface of a tapered roller bearing, slides against the roller end faces while receiving the load. When the load or speed is high or there is insufficient lubrication, wear can occur between the roller end faces and the rib surface.

[0003] Wear can also be a problem in NU-type cylindrical roller bearings (with two outer ring ribs and no inner ring rib) and N-type cylindrical roller bearings (without outer ring ribs and two inner ring ribs) in which the outer ring has two ribs and the outer ring, roller, and cage assembly can be separated from the inner ring, as well as in equivalent double-row and multiple-row cylindrical roller bearings. Specifically, when operating at very high speeds, although the roller end faces and rib faces do not support the load acting from outside the bearing, the sliding speed of these faces becomes very high, and as shown in Figure 7, so-called roller skew may occur, in which the rollers are inclined toward the direction of revolution of the rollers 130 relative to the raceway surfaces 111 of the inner ring 110 and the raceway surfaces 121 of the outer ring 120. Alternatively, as shown in Figure 8, if there is runout of the roller end faces 133 relative to the rolling surfaces 131 of the rollers 130 (the runout of the end faces is exaggerated in Figure 8), the contact force between the roller end faces 133 and the rib surfaces 114 increases. In these cases, wear and seizure may occur on the roller end face 133 and the flange face 114. Such an event occurs when dmn (the pitch circle diameter of the roller (mm)) and the raceway rotation speed (min -1 This is particularly noticeable under speed conditions where the product of the

[0004] Patent Document 1 also describes that wear on the rib surface and spalling on the inner ring raceway surface can be suppressed by using a specified steel material for the inner ring and subjecting it to carburizing treatment, and by appropriately setting specifications such as the carbon content, Rockwell C hardness, compressive residual stress, and maximum carbide diameter in the heavily loaded portion of the inner ring surface. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-168406 Summary of the Invention [Problem to be solved by the invention]

[0006] It is possible to extend the wear life of the rib face by carefully limiting the operating conditions of the machine and bearing, and the mounting state of the bearing on the machine (misalignment between the shaft and housing, misalignment (tilt of the inner or outer ring of the bearing relative to the center of the housing or shaft, etc.)). However, this is a difficult problem to address for so-called "standard roller bearings." In other words, even those skilled in the art face a difficult challenge in designing a "standard roller bearing" that is appropriate for the wear life of the rib face, mainly for economic reasons.

[0007] The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a roller bearing and a method for designing a roller bearing that has a long life by suppressing wear that occurs on the roller end faces and rib surfaces, etc., even in the case of a standard roller bearing. [Means for solving the problem]

[0008] The present invention comprises the following configurations. (1) A roller bearing in which at least one of a pair of raceways having a raceway surface is provided with a flange on at least one axial side of the raceway surface, and a plurality of rollers are disposed between the pair of raceways so as to be able to roll freely, The hardness of the roller is greater than the hardness of the inner surface of the rib portion, The chamfer dimension C in the direction along the inner surface of the flange portion of the chamfered portion provided at the corner between the radial tip of the flange portion and the inner surface of the flange portion is 0.2 mm or more and satisfies the following formula (1): Roller bearings.

[0009]

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[0010] However, Dw is the diameter dimension of the roller (mm), and in the case of tapered roller bearings, it is the large diameter dimension (mm).

[0011] (2) A design method for a roller bearing in which at least one of a pair of raceways having a raceway surface is provided with a flange on at least one axial side of the raceway surface, and a plurality of rollers are disposed between the pair of raceways so as to be able to roll freely, comprising: The hardness of the roller is made harder than the hardness of the inner surface of the rib portion, The chamfer dimension C in the direction along the inner surface of the flange portion of the chamfered portion provided at the corner between the radial tip of the flange portion and the inner surface of the flange portion is 0.2 mm or more, and satisfies the following formula (2): How to design roller bearings.

[0012]

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[0013] However, Dw is the diameter dimension of the roller (mm), and in the case of tapered roller bearings, it is the large diameter dimension (mm). [Effects of the Invention]

[0014] According to the roller bearing of the present invention, even if it is a standard roller bearing, it is possible to suppress wear that occurs on the roller end faces and rib faces, etc., thereby extending the bearing life. [Brief explanation of the drawings]

[0015] [Figure 1]FIG. 1 is a cross-sectional view of a tapered roller bearing according to one embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view of a portion enclosed by a circle A of the tapered roller bearing shown in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing the positional relationship between the large rib portion and the roller end face of a tapered roller bearing. [Figure 4] FIG. 4 is a graph showing the relationship between the roller diameter and the chamfer dimension of the rib tip portion. [Figure 5] FIG. 5 is a graph showing the relationship between roller diameter and flange grinding relief dimension. [Figure 6] FIG. 6 is an explanatory diagram showing various types of roller bearings. [Figure 7] FIG. 7 is a cross-sectional view for explaining a conventional skew. [Figure 8] FIG. 8 is a side view of a conventional roller having runout on its end surface. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a roller bearing according to the present invention will now be described in detail with reference to the drawings. There are known multiple types of roller bearings that are configured by combining a plurality of outer rings that differ in shape depending on whether they have a rib or not, and a plurality of inner rings that similarly differ in shape depending on whether they have a rib or not. The present invention is applicable to any type of roller bearing, and the following description will be given taking a tapered roller bearing as a representative example.

[0017] Fig. 1 is a cross-sectional view of a tapered roller bearing according to one embodiment of the present invention. Fig. 2 is an enlarged cross-sectional view of the portion enclosed by circle A of the tapered roller bearing shown in Fig. 1. Fig. 3 is a cross-sectional view showing the positional relationship between the large rib portion and the roller end face of the tapered roller bearing. As shown in Figs. 1 to 3, the tapered roller bearing 1 comprises an inner ring 10, an outer ring 20, a plurality of tapered rollers 30, and a cage 40 that rotatably holds the tapered rollers 30.

[0018] Tapered roller bearing 1 is a so-called standard product, and inner ring 10, outer ring 20, and tapered rollers 30 are made of JIS standard steel types such as SUJ2, SUJ3, SUJ4, and SUJ5, and are hardened by general quenching and tempering processes. In addition, large rib portion 12 (large rib surface 14), which will be described later, is ground, and raceway surfaces 11 and 21 are ground and then super-finished.

[0019] The inner ring 10 and the outer ring 20 are annular bearing components arranged coaxially. The inner ring 10 has a raceway surface 11 on its outer diameter side, and a large rib portion 12 and a small rib portion 13 are provided at the axial ends of the raceway surface 11. The large rib portion 12 is formed with a large rib surface 14, which is its axially inner side surface. The small rib portion 13 is formed with a small rib surface 15, which is its axially inner side surface. The large rib surface 14 and the small rib surface 15 are formed generally parallel to the roller large end face 33 and the roller small end face 32, respectively. The outer ring 20 has a raceway surface 21 on its inner diameter side. Each raceway surface 11, 21 is formed in a conical shape.

[0020] 2, a chamfered portion 17 having a generally arc-shaped axial cross section is formed at the outer corner between the outer peripheral surface (radial tip) 16 of the large rib portion 12 and the large rib surface 14. A grinding relief groove 18 having a generally arc-shaped axial cross section is formed at the inner corner between the raceway surface 11 and the large rib surface 14.

[0021] As shown in Figure 1, tapered roller 30 has a conical rolling surface 31, a roller small end face 32, and a roller large end face 33. Rolling surface 31 contacts raceway surface 11 of inner ring 10 and raceway surface 21 of outer ring 20. Roller small end face 32 is the side surface of tapered roller 30 on the small diameter side, and roller large end face 33 is the side surface of tapered roller 30 on the large diameter side.

[0022] Based on many years of experience in applying standard bearings to a variety of rotating machines, the applicant has conducted extensive research and found the following bearing specifications as standard specifications that can suppress wear on the roller end faces, rib faces, etc. That is, the bearing rings and rollers are made of bearing steel and hardened by quenching and tempering (through hardening) heat treatment, and at least the following conditions (A) and (C) are satisfied. (A) The flange tip side chamfer dimension C is 0.2 mm or more and satisfies the following formula (3).

[0023]

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[0024] where Dw is the diameter of the roller (mm), and in the case of a tapered roller bearing, it is the large diameter dimension (mm). Here, the rib tip side chamfer dimension C is the length in the direction along the large rib surface 14 from the intersection or contact point 17a of the chamfered portion 17 and the large rib surface 14 shown in Figure 2 to the outer peripheral surface 16 of the large rib portion 12.

[0025] FIG. 4 shows the relationship between the roller diameter Dw and the rib tip side chamfer dimension C / roller diameter Dw, which is obtained from formula (3).

[0026] (B) The grinding relief dimension E of the flange is 0.4 mm or more, and satisfies the following formula (4).

[0027]

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[0028] Here, the grinding relief dimension E is the length from the intersection 18 a between the grinding relief groove 18 and the large rib surface 14 to the raceway surface 11 in the direction along the large rib surface 14 .

[0029] FIG. 5 shows the relationship between the roller diameter Dw and the grinding relief dimension E / roller diameter Dw, which is obtained from equation (4).

[0030] (C) The hardness of the roller is greater than the hardness of the rib surface. (D) The roller end surface roughness is smaller than the rib surface roughness. (E) The Rsk of the rib surface (or the surface that slides against the roller end face, such as the guide ring of a spherical roller bearing) is less than 0 (there are more valleys than peaks in the roughness), and preferably is -0.3 or less. (F) The residual stress on the rib surface is a compressive residual stress (stress value less than 0), and is preferably set to -400 to -50 MPa.

[0031] <Regarding (A) and (B)> Considering raceways of various sizes, when the ratio (C / Dw) of the rib tip side chamfer dimension C to the roller diameter Dw satisfies formula (3), lubricant (lubricating oil or grease) can easily flow from the tip of the large rib portion 12 to the space between the large rib surface 14 and the roller large end face 33, thereby suppressing wear of the large rib surface 14 and the roller large end face 33.

[0032] Furthermore, when the ratio (E / Dw) of the rib grinding relief dimension E to the roller diameter Dw satisfies formula (4), the length of the large rib surface 14 in the generatrix direction can be suitably secured, resulting in good contact with the roller large end face 33. Regarding the rib tip side chamfer dimension C and the rib grinding relief dimension E, particularly for small-sized raceways (i.e., ribs), they must be set to a minimum value (absolute value) or greater for economical production. In other words, we have learned that maintaining these values ​​"above the minimum value and within the range of the roller diameter ratio" is important as a measure against rib wear. Formulas (3) and (4) are not simply design considerations; they are mathematical expressions that indicate optimal ranges derived based on various experimental considerations in order to solve issues specific to "standard roller bearings" for various applications.

[0033] <Regarding (C) and (D)> In cylindrical rollers 30 with improved hardness to extend the bearing ring spalling life, reducing the roughness of roller large end faces 33 makes roller large end faces 33 less susceptible to wear. When hardening is performed by economical quenching and tempering (through hardening) heat treatment on rib surfaces 14 that come into contact with roller large end faces 33 to make a "standard roller bearing," the hardness of raceway surface 11 and rib surface 14 becomes equivalent, so the hardness of rib surface 14 becomes relatively lower than that of roller large end faces 33.

[0034] <About (E)> The skewness Rsk on the rib surface 14 is negative. This results in many valleys in the roughness profile, making it easier for lubricant (oil or grease base oil) to accumulate in these valleys. As a result, wear is suppressed. The skewness Rsk is preferably -0.3 or less. Note that the skewness Rsk here refers to the skewness Rsk of the roughness curve defined in Japanese Industrial Standards (JIS) B0601:2013.

[0035] <About (F)> By adjusting the grinding method of the rib face 14 and imparting an appropriate residual compressive stress to the surface of the rib face 14, the progression of microscopic wear on the rib face 14 can be suppressed. Note that the higher the residual compressive stress, the more the progression of microscopic wear can be suppressed. However, when grinding a rib face 14 that has been hardened by quenching and tempering heat treatment using JIS standard SUJ type 2, type 3, type 4, etc., as is the target of the present invention, processing that increases the residual compressive stress requires increasing the pressing force of the grinding stone against the rib face 14, which makes it more likely to cause manufacturing defects such as grinding burns. Therefore, when grinding with the above-mentioned steel types and heat treatments, a residual compressive stress of -400 to -50 MPa is suitable.

[0036] 3, the roller large end face 33 that comes into contact with the rib surface 14 may have a chamfer 34 applied to the corner between the roller large end face 33 and the rolling surface 31, and a grinding relief 35 provided in the center of the roller large end face 33. Depending on the dimensions of the roller chamfer 34 and grinding relief 35, it is conceivable that these edge portions 34a, 35a may come into contact with the rib surface 14.

[0037] In that case, lubrication will be insufficient at the edge portions 34a, 35a, which may cause wear on the rib surface 14 and roller large end face 33. For this reason, it is preferable that the dimensions of the roller chamfer 34 and grinding relief 35 be set to a size that prevents the edge portions 34a, 35a from contacting the rib surface 14. If these dimensions are such that they can come into contact with the rib surface 14 due to manufacturing reasons, etc., it is also preferable to apply barrel processing or the like to the tapered roller 30 to round the edge portions 34a, 35a in order to suppress wear on the rib surface 14 and roller large end face 33.

[0038] It should be noted that the above values ​​include those that can be quantitatively designed by a person skilled in the art if the operating conditions are defined. However, the bearings targeted by this invention are standard products, and there is a problem in that it is difficult to limit the operating conditions. If we were to consider the "worst conditions" that combine the most severe conditions for each item of operating conditions (e.g., rotational speed, load, lubrication method, lubricant, temperature, and atmosphere) for various rotating machines, the resulting specifications would be economically unreasonable. Since rotating machines under such worst-case conditions are thought to be extremely rare, it is not reasonable to find optimal specifications using this approach.

[0039] The present invention is not limited to the above-described embodiments, and it is also intended that the various components of the embodiments be combined with one another, and that modifications and applications be made by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0040] The present invention can be applied to any single-row roller bearing, such as the NU, NJ, N, and NF types shown in FIG. 6, the NUP type in which a flange ring is provided on the side of the inner ring where there is no flange, and the NH type in which an L-shaped flange ring is provided on an NJ type, as well as NUP-type double-row roller bearings NNU type and N-type double-row roller bearings NN type.

[0041] As described above, the present specification discloses the following: (1) A roller bearing in which at least one of a pair of raceways having a raceway surface is provided with a flange on at least one axial side of the raceway surface, and a plurality of rollers are disposed between the pair of raceways so as to be able to roll freely, The hardness of the roller is greater than the hardness of the inner surface of the rib portion, A chamfer dimension C in a direction along the inner surface of the flange portion of a chamfered portion provided at a corner between the radial tip of the flange portion and the inner surface of the flange portion is 0.2 mm or more, and satisfies the following formula (5): Roller bearings.

[0042]

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[0043] However, Dw is the diameter dimension of the roller (mm), and in the case of tapered roller bearings, it is the large diameter dimension (mm). With this configuration, even in the case of a standard roller bearing, lubricant can easily flow from the tip of the rib into the gap between the rib surface and the roller end surface, suppressing wear on the roller end surface and rib surface, etc., thereby extending the bearing life.

[0044] (2) A relief dimension E of a relief groove provided at a corner between the raceway surface and the inner surface of the rib portion in a direction along the inner surface of the rib portion is 0.4 mm or more, and satisfies the following formula (6): (1) A roller bearing according to the present invention.

[0045]

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[0046] According to this configuration, the length of the rib surface (the inner surface of the rib portion) in the generatrix direction can be suitably secured, the state of contact with the roller end surfaces is improved, and wear of the rib surface can be suppressed.

[0047] (3) A roller bearing according to (1) or (2), wherein the surface roughness of the side surface of the roller is smaller than the surface roughness of the inner surface of the rib portion. According to this configuration, the roughness of the roller side surface can be reduced, thereby suppressing wear on the roller end surface.

[0048] (4) The roller bearing according to (1) or (2), wherein the rib portion has compressive residual stress. This configuration makes it possible to suppress the progression of microscopic wear on the flange surface, and further extend the life of the bearing.

[0049] (5) A design method for a roller bearing in which at least one of a pair of raceways having a raceway surface is provided with a flange portion on at least one axial side of the raceway surface, and a plurality of rollers are disposed between the pair of raceways so as to be able to roll freely, comprising: The hardness of the roller is made harder than the hardness of the inner surface of the rib portion, The chamfer dimension C in the direction along the inner surface of the flange portion of the chamfered portion provided at the corner between the radial tip of the flange portion and the inner surface of the flange portion is 0.2 mm or more, and satisfies the following formula (7): How to design roller bearings.

[0050]

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[0051] However, Dw is the diameter dimension of the roller (mm), and in the case of tapered roller bearings, it is the large diameter dimension (mm).

[0052] (6) A relief dimension E of a relief groove provided at a corner between the raceway surface and the inner surface of the rib portion in a direction along the inner surface of the rib portion is 0.4 mm or more, and satisfies the following formula (4): A method for designing a roller bearing according to claim 5.

[0053]

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[0054] 1. Tapered roller bearings (roller bearings) 10 Inner ring (bearing ring) 11 Raceway surface 12 Large brim (brim) 13 Small brim (brim) 14 Large flange surface (inner surface of flange) 17 Chamfered part 18 Grinding undercut groove 20 Outer ring (bearing ring) 21 Raceway surface 30 Tapered rollers 33 Roller large end face (side) C Chamfer dimension Dw Roller diameter (large diameter side dimension) E Grinding relief dimension

Claims

1. A roller bearing in which at least one of a pair of bearing rings having a raceway surface is provided with a flange portion on at least one axial side of the raceway surface, and a plurality of rollers are rollably disposed between the pair of bearing rings, The hardness of the roller is greater than the hardness of the inner surface of the rib portion, A chamfer dimension C in a direction along the inner surface of the flange portion of a chamfered portion provided at a corner between a radial tip end of the flange portion and the inner surface of the flange portion is 0.2 mm or more, and satisfies the following formula (1): Roller bearings. [Equation 1] Here, Dw is the diameter dimension (mm) of the roller, and in the case of a tapered roller bearing, it is the large diameter dimension (mm).

2. a relief dimension E of a relief groove provided at a corner between the raceway surface and the inner surface of the rib portion in a direction along the inner surface of the rib portion is 0.4 mm or more, and satisfies the following formula (2):

2. A roller bearing according to claim 1. [Equation 2]

3. the surface roughness of the side surface of the roller is smaller than the surface roughness of the inner surface of the rib portion; 3. A roller bearing according to claim 1 or 2.

4. The flange portion has compressive residual stress.

3. A roller bearing according to claim 1 or 2.

5. A design method for a roller bearing in which at least one of a pair of bearing rings having a raceway surface is provided with a flange portion on at least one axial side of the raceway surface, and a plurality of rollers are disposed between the pair of bearing rings so as to be able to roll freely, comprising: The hardness of the roller is made harder than the hardness of the inner surface of the rib portion, a chamfer dimension C in a direction along the inner surface of the flange portion of a chamfered portion provided at a corner between the radial tip of the flange portion and the inner surface of the flange portion is set to 0.2 mm or more, and the following formula (3) is satisfied: How to design roller bearings. [Equation 3] Here, Dw is the diameter dimension (mm) of the roller, and in the case of a tapered roller bearing, it is the large diameter dimension (mm).

6. a relief dimension E of a relief groove provided at a corner between the raceway surface and the inner surface of the rib portion in a direction along the inner surface of the rib portion is 0.4 mm or more, and satisfies the following formula (4): A method for designing a roller bearing according to claim 5. [Equation 4]

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