Rolling bearing design method, rolling bearing, rolling bearing design device, and program

Abstract

To provide a design method of a rolling bearing, the rolling bearing, and a design device and a program of the rolling bearing, hardly causing a foreign matter impression on a raceway surface of the rolling bearing, and hardly shortening a flaking life even if the foreign matter impression is caused.SOLUTION: A product of a life ratio l obtained from Equation (1) according to a hardness ratio h (H1 / H2) between a hardness H1 of a rolling surface of the rolling element and a hardness H2 of a raceway surface of the raceway ring and a life correction coefficient aISO based on JISB1518:2023 of roller bearings is set to 1 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for designing a rolling bearing, a rolling bearing, and an apparatus and program for designing a rolling bearing. [Background technology]

[0002] A method for predicting the life of a rolling bearing is known, which calculates the bearing life based on the properties of the lubricant (see, for example, Patent Document 1). Generally, the basic rating life L of a rolling bearing is 10 (also known as peeling life) is calculated using the method specified in JIS B1518:2013 (or ISO281:2007).

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[0003] L 10 : Basic rated life (unit: 1 million rotations) C: Basic dynamic load rating (unit: N or kgf) P: Dynamic equivalent load (unit: N or kgf) e: 3 for ball bearings, 10 / 3 for roller bearings

[0004] The above standards also provide a method for taking into account lubricant contamination and the fatigue load limit of steel materials in life calculations as a modified rating life. Modified rating life L 10m is calculated by the following formula: where aISO is the life modification coefficient, the details of which will be explained later.

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[0005] This new life theory, based on the basic rating life and modified rating life, suggests that in a clean lubrication environment, the flake life can be expected to be longer than the conventional calculation value. However, if the lubricant is contaminated, the flake life can be significantly shorter. This suggests that bearing users, such as manufacturers and users of machines incorporating rolling bearings, should properly maintain the cleanliness of the lubricant used in the machine. While lubricating oil or grease is typically used as a lubricant for rolling bearings, a method known as flushing, in which new lubricant is introduced and circulated, is known as a method for improving the cleanliness of the lubricant inside the machine. The importance of flushing is mentioned in the above-mentioned standards. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-270911 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the reality is that the new life theory described above has not been widely adopted by general bearing users, and many bearing users tend to apply spalling life values ​​calculated using conventional methods to machine design. The reason for this is the difficulty of understanding the level of lubricant contamination. Even if machine designers can understand the level of lubricant contamination during machine assembly, it is difficult to determine the level of machine user management.

[0008] In the case of the rolling bearing 110 shown in FIG. 4, the inner ring 113, rolling elements 115, and cage 117 are assembled inside the outer ring 111, and the clearance between the components inside the bearing is narrow. In particular, if the cage 117 has a complex shape, the clearance can be on the order of 0.1 mm or less in some locations. For example, foreign matter in the area Pa surrounded by the outer ring 111, cage 117, and rolling elements 115 cannot be adequately removed by simply passing a cleaning agent through it. Furthermore, the clearance area Pb between the cage 117 and rolling elements 115 is narrow, making it difficult for the cleaning agent to flow through. Therefore, even if a rolling bearing contaminated by foreign matter is assembled into a machine and flushed, it is difficult to adequately remove the foreign matter from inside the bearing.

[0009] Therefore, if a rolling bearing can be rotated at a very low speed while carrying a slight load, a lubricant flow will occur within the bearing. This lubricant flow also has the effect of pushing away foreign matter as the rolling elements roll along the raceway, making it easier to remove foreign matter from the bearing. However, once the rolling bearing is installed in a machine, the bearing is subjected to either the weight of the shaft and attached components (such as gears) through the inner ring, or the weight of the housing components through the outer ring. This means that a certain amount of bearing load is unavoidable during operation. When a machine is operated under this bearing load, if foreign matter is present between the raceway surface and the rolling elements, it can become lodged and cause indentations (foreign matter indentations) on the surfaces of these bearing components. Once a foreign matter indentation occurs, extremely large stress is applied to the edge, particularly the raised portion, due to contact between the rolling elements and the raceway surface, which can significantly reduce the bearing's flaking life. In other words, if the inside of the rolling bearing is not kept clean when it is installed in a machine, the rolling bearing's flaking life may be shorter than expected, even if the lubricant is flushed after installation.

[0010] An object of the present invention is to provide a method for designing a rolling bearing, a rolling bearing, a rolling bearing design device, and a program that make it difficult for foreign matter indentations to occur on the raceway surfaces of the rolling bearing, and that, even if foreign matter indentations do occur, make it difficult for the flaking life to be shortened. [Means for solving the problem]

[0011] The present invention comprises the following configurations. (1) A method for designing a roller bearing having a raceway and rolling elements that roll on the raceway surface of the raceway, comprising the steps of: the product of the life ratio l calculated from equation (1) according to the hardness ratio h (H1 / H2) between the hardness H1 of the rolling surface of the rolling element and the hardness H2 of the raceway surface of the bearing ring, and the life modification coefficient aISO of the roller bearing in accordance with JIS B1518:2023, is set to 1 or more; How to design roller bearings. (2) A rolling bearing comprising a raceway and rolling elements that roll on the raceway surface of the raceway, the product of the life ratio l calculated from equation (1) according to the hardness ratio h (H1 / H2) between the hardness H1 of the rolling surface of the rolling element and the hardness H2 of the raceway surface of the bearing ring, and the life modification coefficient aISO of the rolling bearing in accordance with JIS B1518:2023 is 1 or more; Rolling bearing. (3) A rolling bearing design device for designing a rolling bearing having a raceway and rolling elements that roll on the raceway surface of the raceway, comprising: an input unit into which the set configuration conditions and environmental conditions of the rolling bearing are input; a life ratio calculation unit that calculates a life ratio l from equation (1) according to a hardness ratio h (H1 / H2) between a hardness H1 of the rolling surface based on the input configuration conditions and a hardness H2 of the raceway surface of the bearing ring; a life modification factor setting unit that calculates a life modification factor aISO conforming to JIS B1518:2023 for the rolling bearing based on the input configuration conditions and environmental conditions; a condition changing unit that changes at least one of the structural conditions and the environmental conditions of the rolling bearing so that the product of the life ratio l and the life modification coefficient aISO becomes 1 or greater; A rolling bearing design device comprising: (4) A program for causing a computer to realize a design function for a rolling bearing having a raceway and rolling elements that roll on the raceway surface of the raceway, the program comprising: The computer, a function for inputting the set configuration conditions and environmental conditions of the rolling bearing; a function of calculating a life ratio l from equation (1) according to a hardness ratio h (H1 / H2) between a hardness H1 of the rolling surface based on the input configuration conditions and a hardness H2 of the raceway surface of the bearing ring; A function of calculating a life modification coefficient aISO conforming to JIS B1518:2023 for the rolling bearing based on the input configuration conditions and environmental conditions; a function of changing at least one of the structural conditions and the environmental conditions of the rolling bearing so that the product of the life ratio l and the life modification coefficient aISO becomes 1 or greater; A program to achieve this.

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[0012] According to the present invention, foreign matter indentations are less likely to occur on the raceway surfaces of rolling bearings, and even if foreign matter indentations do occur, the flaking life is less likely to be shortened. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a graph showing the relationship between flaking life and cumulative failure probability for each hardness of the rolling surface of the roller. [Figure 2] FIG. 2 is a graph showing the change in flaking life with respect to the ratio of the hardness of the rolling element to the hardness of the raceway surface of the bearing ring. [Figure 3] FIG. 3 is a functional block diagram of a rolling bearing design device. [Figure 4] FIG. 4 is a perspective view showing a conventional rolling bearing. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The rolling bearing according to the present invention is a bearing in which the specifications and condition of the rust preventive oil and the hardness of the parts are controlled so that the product of the rate of reduction in flaking life based on the viscosity and contamination state of the rust preventive oil applied to the surfaces of the parts when the bearing is packaged and the rate of life extension achieved by making the rolling elements harder than the raceway surfaces is at least 1. Here, roller bearings will be used as an example of the rolling bearing, but the type of rolling bearing is not limited to this.

[0015] <Contamination level of anti-rust oil> Anti-rust oils used in rolling bearings include the traditional high-viscosity type containing petrolatum, and the low-viscosity type, which has become more widely used in recent years. High-viscosity anti-rust oils have excellent anti-rust properties, but they are difficult to remove before installing the rolling bearing in a machine. Furthermore, in applications requiring high rotational accuracy, such as machine tools and precision measuring instruments, residual anti-rust oil may affect the bearing's rotational accuracy. However, JIS B1518:2013 suggests that higher viscosity anti-rust oils result in less reduction in flaking life. Therefore, even if high-viscosity anti-rust oils are contaminated, their high viscosity means that initial indentations will likely result in less reduction in flaking life.

[0016] On the other hand, low-viscosity anti-rust oils are relatively easy to remove when installing rolling bearings in machinery, and depending on the application, it may even be possible to install the rolling bearings in machinery with the anti-rust oil still attached. Low-viscosity anti-rust oils are often used for large or smaller bearings, for example, while high-viscosity anti-rust oils tend to be used for extra-large bearings with an outer ring diameter of over 400 mm. Furthermore, the kinematic viscosity of commercially available low-viscosity anti-rust oils at 40°C is 10 to 20 mm. 2 In other words, when a low-viscosity rust preventive oil is applied to a rolling bearing, there is a high possibility that the rolling bearing will be installed in a machine and test-run with the rust preventive oil still remaining, and because the viscosity is low, foreign matter in the rust preventive oil will cause initial indentations that have a significant impact on flaking life.

[0017] However, it is difficult to reduce contamination of the anti-rust oil at the time of packaging of rolling bearings. This is because, in addition to contamination of the anti-rust oil itself applied to the rolling bearings, if foreign matter adheres to the surface when the bearing components are processed and handled during the manufacturing process, the foreign matter cannot be easily removed even by cleaning after the rolling bearing is assembled. One possible solution is to clean each of the multiple processes, but this would increase manufacturing costs. Therefore, as will be described later, it is preferable to optimally manage the hardness of the rolling elements and bearing rings so that a certain degree of anti-rust oil contamination can be tolerated.

[0018] According to the aforementioned JIS B1518:2013, it is suggested that the degree of contamination of the anti-rust oil (lubricant), in other words the distribution of the size and quantity of foreign matter that penetrates the bearing, is correlated with a decrease in flaking life. Specific examples of this are shown below, with the results of calculations using three typical types of cylindrical roller bearings.

[0019] Calculation example 1 is a small product with an inner ring bore diameter of 50 mm (single-row cylindrical roller bearing NU210EW, manufactured by NSK). Calculation example 2 is a large product with an inner ring bore diameter of 100 mm (single-row cylindrical roller bearing NU320EM, manufactured by NSK). Calculation example 3 is an extra-large product with an inner ring bore diameter of 500 mm, the largest size in NSK Ltd.'s catalog "Rolling Bearings for Industrial Machinery" (CAT No. 1103e) (cylindrical roller bearing NU10 / 500, manufactured by NSK). The calculation conditions here are assumed based on empirical values ​​for the initial rotation state during trial operation after the bearing has been installed in the machine.

[0020] [Table 1]

[0021] [Table 2]

[0022] [Table 3]

[0023] [Table 4]

[0024] The rotational speed n was set to 10% of the allowable rotational speed for oil lubrication listed in the catalogue mentioned above. This is because the problem of indentation formation at the beginning of rotation is more likely to occur with oil lubrication than with grease lubrication, and the initial test run begins at a low speed. The dynamic equivalent load Pr is set to 3% of the basic dynamic load rating Cr. Page A164 of the aforementioned catalog defines a light load as 6% or less of Cr, and since test runs are generally performed without load, this assumes that the bearing is supporting the weight of the shaft and other peripheral parts. The temperature was set to 20°C because the temperature of the machine at the start of operation is generally equivalent to room temperature. The fatigue load limit Cu was calculated from the basic static load rating Cor using a simplified formula in Appendix B of JIS B1518:2013. If the fatigue load limit Cu is disclosed for each bearing, that value may be applied.

[0025] aISO in Tables 2 to 4 is the life modification coefficient (life reduction rate) specified in JIS B1518:2013, which takes into account the dynamic viscosity of the bearing lubricant, the state of contamination, etc., and can be expressed by the following formula (2).

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[0026] Here, the coefficients are as follows: Viscosity ratio κ=ν / ν1 ν: Dynamic viscosity of lubricant [mm 2 / s] ν1: Reference kinematic viscosity of lubricant [mm 2 / s] n<1000min -1 When ν1=45000×n (-0.83) ×D pw (-0.5) n≧1000min -1When ν1=45000×n (-0.5) ×D pw (-0.5) D pw : Pitch diameter of roller set [mm] Coefficients A and B are as shown in the table below (for radial roller bearings)

[0027] [Table 5]

[0028] The contamination coefficient ec is a value disclosed in JIS B1518:2013. The contamination coefficient ec for conditions equivalent to oil lubrication without a filter, which is not disclosed, is determined by the following equation (3). Coefficients C and D in equation (3) are shown in Table 6.

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[0029] [Table 6]

[0030] The ISO 4406 code (also called contamination code) referred to here is defined by ISO 4406:2021 (or JIS B9933) and indicates the degree of contamination of hydraulic oil by solid particles. The code value is expressed in three levels of particle size (4 μm or more, 6 μm or more, 14 μm or more), with each value increasing by 1 indicating twice the number of particles. JIS B1518:2013 also discloses coefficients for the ISO 4406 code numbers, roughly in steps of two, as shown in Table 6, and the contamination coefficient ec can be calculated using equation (3) for these.

[0031] On the other hand, there may be intermediate tainted codes. For example, between - / 17 / 14 and - / 19 / 16, there may be a code called - / 18 / 15. The following method is suitable for calculating aISO for such intermediate tainted codes.

[0032] The contamination level is calculated by calculating the aISO for the contamination levels above, below, and below the level, and then calculating the average of the logarithms (base 10) of these values, and using this as the exponent to find the value raised to the power of 10. The specific calculation formula is shown in Equation (4).

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[0033] As mentioned above, the greater the amount of foreign matter, the greater the content of larger foreign matter, and the shorter the flaking life. For any rolling bearing, the new life value equivalent to the conventional flaking life calculation value is achieved when the aISO value in Tables 2, 3, and 4 is 1. In other words, this condition can be used as the control limit for internal cleanliness at the time of bearing shipment.

[0034] In particular, the commonly used viscosity of 10 to 20 mm 2 For rolling bearings coated with low-viscosity rust-preventive oil of 1 / s (at 40°C), the effectiveness of applying this design method can be enhanced by properly managing the degree of lubrication (rust-preventive oil) and the hardness of the bearing parts (rolling elements and raceways).

[0035] Although the above-mentioned equation (2) shows the calculation formula and coefficients for radial roller bearings, this design method can also be applied to thrust roller bearings by using the formulas and coefficients for thrust roller bearings shown in JIS B1518: 2013. Furthermore, although a detailed explanation will be omitted, this design method can also be applied to other types of bearings by appropriately selecting the calculation formulas and coefficients.

[0036] <Hardness of rolling elements and raceway surfaces> The flaking life of a rolling bearing can be extended by making the rolling elements of the rolling bearing harder than the raceway surface of the bearing ring. In order to confirm this, the following test was carried out. The flaking life test here is referred to as an "initial indentation life test." Specifically, before the actual flaking life test of a roller bearing, hard foreign matter is intentionally mixed into the lubricant, and the roller bearing is rotated while a bearing load is applied. This creates foreign matter indentations on the raceway surfaces and roller rolling surfaces. The roller bearing is then removed and thoroughly cleaned, and is then installed in a life testing machine and a life test is conducted using clean lubricant. This life test assumes that foreign matter is present inside the roller bearing when it is shipped, and that when the roller bearing is installed in a machine and a trial run is conducted, foreign matter indentations are created on the raceway surfaces and roller rolling surfaces. The situation is assumed to be such that filtered, clean lubricant is supplied during the actual operation that follows.

[0037] (Life test conditions) Test material: Tapered roller bearing (HR32017XJ manufactured by NSK) P / C=0.43 P: Dynamic equivalent load kgf C: Basic dynamic load rating kgf (Radial load Fr=6278kgf, axial load Fa=1883kgf) Inner ring rotation speed n: 1500 min -1 Lubricant specifications: FBK Oil RO68 (ENEOS: kinematic viscosity 68mm) 2 / s(40℃) product equivalent)

[0038] (Initial indentation conditions) The coefficient P / C and inner ring rotation speed n were the same as the life test conditions described above, and cementite-based foreign matter (hardness 870HV), 74 to 147μm in size, and 0.3g in weight was placed inside the bearing.

[0039] Figure 1 is a graph showing the relationship between flaking life and cumulative failure probability for each hardness of the roller rolling surface. Figure 1 also shows the results of testing the flaking life of roller bearings using a combination of roller bearings treated to target three hardness conditions: HRC62, 63, and 64. The test results showed that the harder the roller rolling surface, the longer the bearing life. Compared to the result for HRC62, L10 (flaking life at 10% cumulative flaking) was 1.34 times when targeting HRC63, and 1.58 times when targeting HRC64. The actual measured component hardness HRC values ​​of the bearings used in this test are shown in Table 7.

[0040] [Table 7]

[0041] Figure 2 is a graph showing the change in flaking life versus the ratio of the hardness of the rolling element to the hardness of the raceway surface of the bearing ring. From the relationship shown in Figure 2, it was discovered that the change in life relative to the life when the hardness of the rolling surface of the roller and the raceway surface of the bearing ring are the same is related by the following equation (5), with the hardness ratio h as a variable.

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[0042] Here, the hardness ratio h is the hardness of the rolling element's rolling surface divided by the hardness of the raceway surface of the bearing ring, and the life ratio l is the rate of change in life compared to the life when the rolling surface of the roller and the raceway surface of the bearing ring have the same hardness (hardness ratio h = 1). Taking this effect into consideration, for example, if the hardness ratio h is 1.2, the flaking life will be 1.71 times longer. In other words, by increasing the hardness of the rolling element beyond the hardness of the raceway surface, the aforementioned control limit for bearing cleanliness can be relaxed. The hardness ratio h is preferably 1.03 or higher, more preferably 1.05 or higher, and even more preferably 1.1 or higher. There is no particular upper limit to the hardness ratio h, but in reality it is, for example, 1.30 or lower, preferably 1.22 or lower.

[0043] The effect of initial indentations that may occur in the early stages of test operation due to the viscosity and contamination of the lubricant (rust prevention oil) that is attached to the surface during bearing packaging on reducing life can be calculated using equation (2) above. Also, the effect of extending flaking life in a state where initial indentations have been formed by making the hardness of the rolling surface of the roller higher than the hardness of the raceway surface of the bearing ring can be calculated using equation (5) above.

[0044] The cleanliness of the bearing interior is controlled within an appropriate range, and the hardness of the bearing components is controlled so that the product of the life modification coefficient aISO in equation (2) and the life ratio l in equation (5) is 1 or greater. This allows the flaking life expected by bearing users to be achieved. Maintaining high internal cleanliness during bearing manufacturing requires investment in production facilities and quality control. Therefore, relaxing the internal cleanliness control limits leads to improved economic efficiency. The product of the life modification coefficient aISO and the life ratio l is preferably 1.5 or greater, and more preferably 3 or greater. While there is no particular upper limit to this product, it is practically 87.5 or less, and preferably 86 or less.

[0045] The following example can also be given based on the results of the initial indentation test described above. The measured hardness of the bearing ring in this test was HRC 59.5, so the bearing ring hardness was set to HRC 60. On the other hand, if the roller hardness is set to HRC 62, the hardness ratio h is 62 / 60 ≒ 1.03. According to equation (5), the life ratio l due to the hardness ratio h is 1.36, so a 1.36-fold life extension can be expected with this hardness ratio h. Therefore, if the life reduction rate due to lubricant contamination is 1 / 1.36 ≒ 0.735 or higher, the flaking life expected by bearing users can be achieved. In Tables 2 to 4, which show the calculation results of aISO in the aforementioned Calculation Examples 1 to 3, the underlined aISO values ​​correspond to the appropriate range described above. According to this, if the kinematic viscosity of the lubricant at 20°C is 27mm, 2 In the case of / s(VG12), we can see that the tainted code can tolerate a range up to - / 18 / 15.

[0046] The hardness range of the raceway is specified as HRC57 to 65 (when no dimensional stabilization heat treatment is performed) in JIS B1511. If the hardness is set to HRC61, the median value of this hardness range, and the roller hardness is set to HRC63, the hardness ratio h of the roller to the raceway is 63 / 61 ≒ 1.03, and it is expected that a similar reduction rate in flaking life as above can be obtained, and the contamination code range mentioned above is acceptable.

[0047] As described above, by using the above-described rolling bearing design method, it is possible to individually set the bearing specifications (particularly size), lubricant (rust preventative oil) specifications, and lubricant contamination control level to economically optimal conditions.

[0048] Next, the configuration of a rolling bearing design device 100 for implementing the above-described rolling bearing design method will be described. 3 is a functional block diagram of a rolling bearing design device. The bearing design device (hereinafter referred to as the design device) 100 comprises an input unit 11, a life ratio calculation unit 13, a life correction coefficient setting unit 15, and a condition change unit 17. The input unit 11 receives input of the set configuration conditions and environmental conditions of the rolling bearing. The configuration conditions include, for example, the hardness of the rolling element rolling surfaces, the hardness of the raceway surfaces of the bearing rings, the pitch diameter of the rolling element set, the bearing outer diameter, the bearing bore diameter, the diameter, length, and chamfer dimensions of the rollers (rolling elements), the rated load, and the fatigue stress limit of the raceway material, as well as lubricant properties such as the viscosity ratio, kinematic viscosity, and contamination level (ISO 4406 code). The environmental conditions include the bearing rotational speed, actual axial load, radial load, and the kinematic viscosity of the lubricant during operation.

[0049] The life ratio calculation unit 13 calculates the life ratio l from the above-mentioned equation (5) according to the hardness ratio h (H1 / H2) between the hardness H1 of the rolling surface based on the input configuration conditions and the hardness H2 of the raceway surface of the bearing ring.

[0050] The life modification coefficient setting unit 15 determines the life modification coefficient aISO of the rolling bearing that conforms to JIS B1518:2023, based on the input configuration conditions and environmental conditions. For example, the life modification coefficient aISO corresponding to the various conditions of the life modification coefficient aISO is determined for the target rolling bearing by referring to a database DB in which table values ​​or arithmetic expressions, etc. are registered in advance, and the life modification coefficient aISO is set as the aISO value.

[0051] The condition modification unit 17 calculates the product of the life ratio l calculated by the life ratio calculation unit 13 and the life modification coefficient aISO set by the life modification coefficient setting unit 15. Then, at least one of the structural conditions and environmental conditions of the rolling bearing described above is changed so that the value of this product becomes 1 or greater. In other words, by changing the structural conditions and environmental conditions, a combination is found that makes the product of the life ratio l and the life modification coefficient aISO 1 or greater. Specifically, the values ​​of various items such as the structural conditions and environmental conditions described above are changed. The condition modification unit 17 changes the structural conditions and environmental conditions and repeatedly calculates the life ratio l and the life modification coefficient aISO until the product becomes 1 or greater, and when the product becomes 1 or greater, outputs the combination of various conditions at that time as design information.

[0052] The design device 100 described above is configured with hardware using an information processing device such as a PC (Personal Computer). Each function of the design device 100 is realized by a control unit (not shown) reading and executing a program having a specific function stored in a storage device (not shown). Examples of the storage device include memory such as RAM (Random Access Memory), which is a volatile storage area, and ROM (Read Only Memory), which is a non-volatile storage area, and storage such as HDD (Hard Disk Drive) and SSD (Solid State Drive). Examples of the control unit include a processor such as a CPU (Central Processing Unit) or MPU (Micro Processor Unit), or a dedicated circuit.

[0053] According to the design device 100 of this configuration, the conditions under which the product of the life ratio l and the life modification coefficient aISO is 1 or greater can be quickly and simply determined using a computer, making it easy to design rolling bearings that suit a variety of usage conditions, and also to make design changes easily.

[0054] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications 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.

[0055] As described above, the present specification discloses the following: (1) A method for designing a roller bearing having a raceway and rolling elements that roll on the raceway surface of the raceway, comprising the steps of: the product of the life ratio l calculated from equation (6) according to the hardness ratio h (H1 / H2) between the hardness H1 of the rolling surface of the rolling element and the hardness H2 of the raceway surface of the bearing ring and the life modification coefficient aISO of the roller bearing in accordance with JIS B1518:2023 is set to 1 or more; How to design roller bearings.

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[0056] This design method for roller bearings ensures that the internal cleanliness of the rolling bearing is adequately maintained, making it difficult for foreign matter remaining inside the bearing to cause foreign matter indentations on the raceway surfaces. Even if foreign matter indentations do occur, they are unlikely to shorten the flaking life, making it possible to achieve the flaking life expected by bearing users.

[0057] (2) A method for designing a roller bearing according to (1), wherein the value of the life modification factor aISO is a value calculated using equation (7) according to the viscosity of the lubricant supplied to the rolling bearing and a contamination factor conforming to JIS B1518:2023.

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[0058] however, Viscosity ratio κ=ν / ν1 ν: Dynamic viscosity of lubricant [mm 2 / s] ν1: Reference kinematic viscosity of lubricant [mm 2 / s] Pr: Dynamic equivalent load [N] Cu: Fatigue load limit [N] Cr: Basic dynamic load rating [N] ec: Contamination coefficient According to this roller bearing design method, it is possible to set a life correction factor that takes into account the dynamic viscosity of the bearing lubricant, the state of contamination, and the like.

[0059] (3) A rolling bearing comprising a raceway and rolling elements that roll on the raceway surface of the raceway, the product of the life ratio l calculated from equation (8) according to the hardness ratio h (H1 / H2) between the hardness H1 of the rolling surface of the rolling element and the hardness H2 of the raceway surface of the bearing ring and the life modification coefficient aISO of the rolling bearing in accordance with JIS B1518:2023 is 1 or more; Rolling bearing.

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[0060] This rolling bearing maintains a high level of internal cleanliness, making it less likely for foreign matter remaining inside the bearing to cause foreign matter indentations on the raceway surfaces. Even if foreign matter indentations do occur, this is less likely to shorten the flaking life, making it possible to achieve the flaking life expected by bearing users.

[0061] (4) The rolling bearing is a radial roller bearing, The rolling bearing according to (3), wherein the value of the life modification coefficient aISO is a value calculated by equation (9) according to the viscosity of the lubricant supplied to the rolling bearing and a contamination coefficient conforming to JIS B1518:2023.

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[0062] however, Viscosity ratio κ=ν / ν1 ν: Dynamic viscosity of lubricant [mm 2 / s] ν1: Reference kinematic viscosity of lubricant [mm 2 / s] Pr: Dynamic equivalent load [N] Cu: Fatigue load limit [N] Cr: Basic dynamic load rating [N] ec: Contamination coefficient This roller bearing provides a life correction factor suitable for radial roller bearings.

[0063] (5) The kinematic viscosity of the lubricant at 20°C is 27mm 2 / s or more, and the life modification factor aISO of the lubricant in accordance with JIS B1518:2023 at the time of packaging the rolling bearing after manufacture is greater than a value equivalent to - / 18 / 15 in the ISO 4406 code, and the hardness ratio h is 1.03 or more. This rolling bearing can stably achieve the desired flaking life under economical conditions suitable for a typical radial roller bearing.

[0064] (6) A rolling bearing design device for designing a rolling bearing having a raceway and rolling elements that roll on a raceway surface of the raceway, comprising: an input unit into which the set configuration conditions and environmental conditions of the rolling bearing are input; a life ratio calculation unit that calculates a life ratio l from equation (10) according to a hardness ratio h (H1 / H2) between a hardness H1 of the rolling surface based on the input configuration conditions and a hardness H2 of the raceway surface of the bearing ring; a life modification factor setting unit that calculates a life modification factor aISO conforming to JIS B1518:2023 for the rolling bearing based on the input configuration conditions and environmental conditions; a condition changing unit that changes at least one of the structural conditions and the environmental conditions of the rolling bearing so that the product of the life ratio l and the life modification coefficient aISO becomes 1 or greater; A rolling bearing design device comprising:

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[0065] (7) A program for causing a computer to realize a design function for a rolling bearing having a raceway and rolling elements that roll on the raceway surface of the raceway, the program comprising: The computer, a function for inputting the set configuration conditions and environmental conditions of the rolling bearing; a function of calculating a life ratio l from equation (11) according to a hardness ratio h (H1 / H2) between the hardness H1 of the rolling surface based on the input configuration conditions and the hardness H2 of the raceway surface of the bearing ring; A function of calculating a life modification coefficient aISO conforming to JIS B1518:2023 for the rolling bearing based on the input configuration conditions and environmental conditions; a function of changing at least one of the structural conditions and the environmental conditions of the rolling bearing so that the product of the life ratio l and the life modification coefficient aISO becomes 1 or greater; A program to achieve this.

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[0066] This program determines the structural and environmental conditions for a rolling bearing that will result in the product of the life ratio l and the life modification coefficient aIOS being equal to or greater than 1. This makes it easy to design a rolling bearing that is less likely to have a shortened flaking life and that can achieve the flaking life expected by bearing users. [Explanation of symbols]

[0067] 11 Input section 13 Life ratio calculation section 15 Life correction coefficient setting section 17 Condition change section 100 Bearing design equipment

Claims

1. A design method for a roller bearing including a raceway ring and rolling elements that roll on a raceway surface of the raceway ring, comprising the steps of: the product of a life ratio l calculated from equation (1) according to a hardness ratio h (H1 / H2) between the hardness H1 of the rolling surface of the rolling element and the hardness H2 of the raceway surface of the raceway ring, and a life modification coefficient aISO of the roller bearing in accordance with JIS B1518:2023, is set to 1 or more; How to design roller bearings. [Equation 1]

2. The value of the life modification coefficient aISO is a value calculated by equation (2) according to the viscosity of the lubricant supplied to the rolling bearing and the contamination coefficient in accordance with JIS B1518:2023. The method for designing a rolling bearing according to claim 1. [Equation 2] however, Viscosity ratio k=ν / ν １ ν: kinematic viscosity of lubricant [mm ２ / s] ν １ : Reference kinematic viscosity of lubricant [mm ２ / s] Pr: Dynamic equivalent load [N] Cu: fatigue load limit [N] Cr: Basic dynamic load rating [N] ec: Contamination coefficient

3. A rolling bearing comprising a raceway and rolling elements that roll on a raceway surface of the raceway, the product of a life ratio l calculated from equation (3) according to a hardness ratio h (H1 / H2) between the hardness H1 of the rolling surface of the rolling element and the hardness H2 of the raceway surface of the raceway ring and a life modification coefficient aISO of the rolling bearing in accordance with JIS B1518:2023 is 1 or more; Rolling bearing. [Equation 3]

4. The rolling bearing is a radial roller bearing, The value of the life modification coefficient aISO is a value calculated by equation (4) according to the viscosity of the lubricant supplied to the rolling bearing and the contamination coefficient in accordance with JIS B1518:2023.

4. The rolling bearing according to claim 3. [Equation 4] however, k=n / n １ ν: kinematic viscosity of lubricant [mm ２ / s] ν １ : Reference kinematic viscosity of lubricant [mm ２ / s] Pr: Dynamic equivalent load [N] Cu: fatigue load limit [N] Cr: Basic dynamic load rating [N] ec: Contamination coefficient

5. The kinematic viscosity of the lubricant at 20°C is 27 mm ２ / s or more, and the life modification coefficient aISO of the lubricant in accordance with JIS B1518:2023 at the time of packaging the rolling bearing after manufacture is greater than a value equivalent to - / 18 / 15 in the ISO 4406 code, and the hardness ratio h is 1.03 or more.

5. The rolling bearing according to claim 4.

6. A rolling bearing design device for designing a rolling bearing including a raceway ring and rolling elements that roll on a raceway surface of the raceway ring, comprising: an input unit into which the set configuration conditions and environmental conditions of the rolling bearing are input; a life ratio calculation unit that calculates a life ratio l from equation (5) according to a hardness ratio h (H1 / H2) between a hardness H1 of the rolling surface based on the input configuration conditions and a hardness H2 of the raceway surface of the bearing ring; a life modification factor setting unit that calculates a life modification factor aISO of the rolling bearing in accordance with JIS B1518:2023 based on the input configuration conditions and environmental conditions; a condition changing unit that changes at least one of the structural conditions and the environmental conditions of the rolling bearing so that the product of the life ratio l and the life modification coefficient aISO becomes 1 or greater; A rolling bearing design device comprising: [Equation 5]

7. A program for causing a computer to realize a design function for a rolling bearing including a raceway ring and rolling elements that roll on a raceway surface of the raceway ring, The computer, a function for inputting the set configuration conditions and environmental conditions of the rolling bearing; a function of calculating a life ratio l from equation (6) according to a hardness ratio h (H1 / H2) between a hardness H1 of the rolling surface based on the input configuration conditions and a hardness H2 of the raceway surface of the bearing ring; a function of calculating a life modification coefficient aISO of the rolling bearing in accordance with JIS B1518:2023 based on the input configuration conditions and environmental conditions; a function of changing at least one of the structural conditions and the environmental conditions of the rolling bearing so that the product of the life ratio l and the life modification coefficient aISO becomes 1 or greater; A program to achieve this. [Equation 6]

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