Calculation method of oil film parameters

Abstract

To provide a calculation method for an oil film parameter that can calculate an oil film parameter of lubricant taking the effect from such as an additive, a thickener, and traction into account.SOLUTION: A calculation method for an oil film parameter of any lubricant performs a rolling fatigue test with respect to each of a plurality of reference lubricants with different types of kinetic viscosity and has: a step (a) of obtaining each of ununiformity Ibase in X-ray diffraction ring strengths before and after the testing of a rolling motion plane; a step (b) of calculating oil film parameters Λbase for the reference lubricants, respectively; a step (c) of obtaining a reference line from the ununiformity Ibase of the x-ray diffraction ring strengths with respect to the oil film parameters Λbase; a step (d) of obtaining ununiformity I in the x-ray diffraction ring strengths before and after the test of the rolling motion plane by performing the rolling fatigue test with respect to any lubricant; and a step (e) of calculating a value of the oil film parameter on the reference line of the ununiformity I in the obtained X-ray diffraction ring strengths as an oil film parameter Λ of any lubricant.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for calculating oil film parameters of a lubricant used in automobiles, industrial machinery, etc., and more particularly to a method for calculating oil film parameters of a lubricant filled in a rolling bearing. [Background technology]

[0002] In recent years, various industries have been required to reduce fuel consumption and energy consumption as a measure against global warming. For example, in the automotive industry, efforts are being made to address this issue by reducing the viscosity of lubricants such as engine oil. However, such reduction in the viscosity of lubricants entails the risk of metal-to-metal contact, so the oil film parameter is used as one method of determining whether or not a lubricant can be used. The oil film parameter is a parameter that indicates the degree of interference between projections in the EHL region (elastohydrodynamic lubrication).

[0003] Conventionally, the oil film parameter Λ is calculated by the ratio of the thickness h of the oil film formed on the contact surfaces of two objects in rolling contact to the standard deviations of the roughnesses σ1 and σ2 of the two surfaces (see Non-Patent Document 1). Meanwhile, Patent Document 1 describes a prediction method for predicting the life of rolling bearings. This prediction method uses the specifications of the bearing, lubrication parameters, load parameters, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3855651 [Non-patent literature]

[0005] [Non-Patent Document 1] Yuji Yamamoto and Yoshihiro Kaneda, "Tribology", 2nd edition, Rikogakusha, December 2010, p.113-170 Summary of the Invention [Problem to be solved by the invention]

[0006] In the conventional method for calculating the oil film parameter Λ described above, the oil film thickness h (theoretical oil film thickness) is calculated by a theoretical formula based on the kinetic viscosity of the lubricating oil, and the oil film parameter Λ is calculated using the oil film thickness h. Then, the usability of the lubricant is judged based on the obtained oil film parameter Λ. However, in the conventional method for calculating the oil film parameter Λ, it is difficult to appropriately judge whether the lubricant can be used because it cannot take into account the effects of additives, thickeners, etc. contained in the lubricant, or the effects of usage conditions such as traction. In particular, in the low Λ region where metal contact may occur, additives, thickeners, traction, etc. have a large effect on the life of bearings, etc. In addition, the life prediction method of Patent Document 1 basically corrects the kinetic viscosity of the lubricating oil as a standard, and does not take into account the effects of additives or the effects of traction.

[0007] The present invention has been made in consideration of the above circumstances, and aims to provide a method for calculating an oil film parameter that can calculate the oil film parameter of a lubricant while taking into account the effects of additives, thickeners, traction, etc. [Means for solving the problem]

[0008] The method for calculating the oil film parameter of the present invention is a method for calculating the oil film parameter of an arbitrary lubricant, which comprises carrying out a rolling fatigue test for each of a plurality of standard lubricants having different kinetic viscosities, and measuring the variation S of the X-ray diffraction ring intensity of the rolling surface before and after the test. 0_base , S base The non-uniformity of the X-ray diffraction ring intensity I before and after the test on the rolling surface was measured. base (=S base / S 0_base ) and step (a) of determining the oil film parameter Λ of the reference lubricant in the rolling fatigue test. base and step (b) of calculating the oil film parameter Λ base Inhomogeneity of the X-ray diffraction ring intensity for I baseon a graph to obtain a reference line showing the relationship between the two; (d) performing the rolling fatigue test on the arbitrary lubricant, measuring the variations S0, S in the X-ray diffraction ring intensity of the rolling surface before and after the test in the test, and determining the non-uniformity I (=S / S0) of the X-ray diffraction ring intensity of the rolling surface before and after the test; and (e) calculating the oil film parameter value of the obtained non-uniformity I of the X-ray diffraction ring intensity on the reference line as the oil film parameter Λ of the arbitrary lubricant.

[0009] The rolling fatigue test in the step (a) is characterized in that it is a two-cylinder test in which two cylinders are brought into contact with each other and a load is applied thereto.

[0010] The above step (b) calculates the oil film parameter Λ using the following formula (1): base The present invention is characterized in that:

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[0011] The oil film thickness in the above formula (1) is calculated by a theoretical formula.

[0012] The oil film thickness in the above formula (1) is calculated by measuring the electrical resistance and capacitance of the oil film formed between two cylinders in a two-cylinder test in which the two cylinders are brought into contact with each other and a load is applied.

[0013] Any of the above lubricants has a kinetic viscosity of 5mm 2 / s~80mm 2 / s. Effect of the Invention

[0014] The method for calculating the oil film parameters of the present invention is to first carry out a rolling fatigue test on each of a number of standard lubricants having different kinetic viscosities, and then measure the variation S of the X-ray diffraction ring intensity on the rolling surface before and after the test. 0_base , S base The non-uniformity of the X-ray diffraction ring intensity before and after the test on the rolling surface I base (=S base / S 0_base ) and the oil film parameter Λ base is calculated, and a reference line in the Λ-I characteristic diagram showing the relationship between the nonuniformity of the X-ray diffraction ring intensity and the oil film parameter is obtained from these. Next, a rolling fatigue test is performed using an arbitrary lubricant, and the variations S0 and S in the X-ray diffraction ring intensity before and after the test of the rolling surface are obtained, and the nonuniformity I (=S / S0) of the X-ray diffraction ring intensity before and after the test of the rolling surface is obtained. This allows the nonuniformity of the X-ray diffraction ring intensity reflecting the influence of additives and thickeners contained in the lubricant and the influence of traction in addition to the kinetic viscosity of the lubricant to be obtained. Then, by using the reference line in the Λ-I characteristic diagram and setting the value of the oil film parameter corresponding to the obtained nonuniformity I of the X-ray diffraction ring intensity as the oil film parameter Λ, the oil film parameter Λ considering the influence of additives, thickeners, traction, etc. can be obtained. This allows the appropriate judgment of whether the lubricant can be used.

[0015] In the step (b), the oil film parameter Λ is calculated using the formula (1). base In calculating the oil film thickness in the above formula (1), the electrical resistance and capacitance of the reference lubricant between the two cylinders are measured, so that the oil film parameter Λ is more accurate than when calculated by a theoretical formula. base can be calculated. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a diagram showing a rolling bearing filled with grease. [Diagram 2] FIG. 1 is a schematic diagram of an X-ray analysis device. [Diagram 3] FIG. 11 is a diagram showing an example of a reference line obtained in step (c). [Figure 4]Schematic diagram of a two-cylinder testing machine [Diagram 5] FIG. 1 shows the relationship between oil film parameters and non-uniformity of X-ray diffraction ring intensity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The lubricants targeted by the method for calculating the oil film parameter of the present invention are lubricants used in automobiles, industrial machines, etc. Examples of such lubricants include lubricating oils and greases filled in rolling bearings, ATFs (Automatic Transmission Fluids) used in automatic transmissions, CVTFs (Continuously Variable Transmission Fluids) used in continuously variable transmissions, and differential gear oils used in differential gears.

[0018] FIG. 1 shows an example of a rolling bearing filled with grease as a lubricant. FIG. 1 is a cross-sectional view of a deep groove ball bearing. In the rolling bearing 1, an inner ring 2 having an inner ring raceway surface 2a on its outer circumferential surface and an outer ring 3 having an outer ring raceway surface 3a on its inner circumferential surface are concentrically arranged, and a plurality of balls 4 are arranged between the inner ring raceway surface 2a and the outer ring raceway surface 3a. The balls 4 are held by a cage 5. In addition, openings 8a, 8b at both axial ends of the inner and outer rings are sealed by a seal member 6, and grease 7 is filled at least around the balls 4. The inner ring 2, the outer ring 3 and the balls 4 are made of an iron-based metallic material, and the grease 7 is interposed between the raceway surface with the balls 4 to lubricate them.

[0019] The grease filled in the rolling bearing contains a base oil and a thickener. The base oil is not particularly limited, and any common base oil that is normally used in the field of greases can be used. For example, highly refined oil, mineral oil, ester oil, ether oil, synthetic hydrocarbon oil (PAO oil), silicone oil, fluorine oil, and mixtures of these oils can be used.

[0020] The thickener is not particularly limited, and any of the general thickeners used in the field of greases can be used. For example, soap-based thickeners such as metal soaps and complex metal soaps, and non-soap-based thickeners such as bentone, silica gel, urea compounds, and urea-urethane compounds can be used. Metal soaps include sodium soap, calcium soap, aluminum soap, and lithium soap, while urea compounds and urea-urethane compounds include diurea compounds, triurea compounds, tetraurea compounds, other polyurea compounds, and diurethane compounds.

[0021] The grease may also contain other known additives as necessary, such as amine or phenol-based antioxidants, chlorine-, sulfur-, or phosphorus-based compounds, extreme pressure agents such as organic molybdenum, and rust inhibitors such as petroleum sulfonates, dinonylnaphthalene sulfonates, and sorbitan esters.

[0022] On the other hand, the lubricating oil filled in the rolling bearing contains the above-mentioned base oil and additives.

[0023] Depending on the additives and thickeners contained in the lubricant, some have a beneficial effect on rolling fatigue, while others have no effect. On the other hand, in the case of lubricants where the influence of traction is large, such as CVTF, traction tends to have a detrimental effect on rolling fatigue. Conventional methods for calculating oil film parameters have been based only on the kinetic viscosity of the lubricant, so the effects of additives, thickeners, and traction were not taken into account.

[0024] In contrast, the method for calculating the oil film parameter of the present invention is based on the fact that the nonuniformity of the X-ray diffraction ring intensity before and after the rolling fatigue test shows a correlation with the oil film parameter, and is a method for calculating the oil film parameter from the nonuniformity of the X-ray diffraction ring intensity before and after the rolling fatigue test. In the rolling fatigue test using the lubricant itself, the nonuniformity of the X-ray diffraction ring intensity, that is, the change in the variation of the X-ray diffraction ring intensity before and after the test, is used to incorporate the influence of factors such as additives, thickeners, and traction contained in the lubricant, and the oil film parameter can be calculated with high accuracy.

[0025] The method for calculating the oil film parameters of the present invention is to carry out a rolling fatigue test using a number of standard lubricants with different kinetic viscosities, and to calculate the variation S of the X-ray diffraction ring intensity before and after the test on the rolling surface. 0_base , S base The non-uniformity of the X-ray diffraction ring intensity before and after the test on the rolling surface I base (=S base / S 0_base ) and determining the oil film parameter Λ of the reference lubricant. base and step (b) calculating the inhomogeneity of the obtained X-ray diffraction ring intensity I base and the oil film parameter Λ base The method includes a step (c) of obtaining a reference line from the obtained line, a step (d) of performing a rolling fatigue test using a given lubricant, obtaining the variations S0 and S in the X-ray diffraction ring intensity of the rolling surface before and after the test, and determining the non-uniformity I (=S / S0) of the X-ray diffraction ring intensity of the rolling surface before and after the test, and a step (e) of calculating the oil film parameter Λ of the given lubricant from the obtained non-uniformity I of the X-ray diffraction ring intensity and the reference line. Each step will be described below.

[0026] <Step (a)> In this step, rolling fatigue tests are conducted for each of several standard lubricants with different kinetic viscosities. Rolling fatigue tests include tests using bearings and two-cylinder tests, which end when a certain number of load cycles have elapsed. As shown in Figure 4 below, the two-cylinder test is a test in which a cylindrical test piece is attached to two parallel rotating shafts, and the two cylinders are brought into contact and a load is applied. The following describes the case where the two-cylinder test is used as the rolling fatigue test.

[0027] In step (a), the rolling surface is subjected to X-ray analysis before and after the two-cylinder test (at the time when a predetermined number of loads has elapsed). FIG. 2 shows a schematic diagram of an X-ray analysis device. As shown in FIG. 2, the X-ray analysis device 11 has an irradiation unit 12 that irradiates X-rays onto a rolling surface 15 of a rolling part such as a cylinder, a detector 13 that detects annular X-rays diffracted at the rolling surface 15, and a calculation unit 14 that is connected to the detector 13 and calculates predetermined X-ray analysis data based on detection data of the annular X-rays detected by the detector 13. The calculation unit 14 may have a function of storing the detection data. The X-ray analysis device 11 may also have a display unit that displays the calculation results of the calculation unit 14.

[0028] Irradiation unit 12 includes an X-ray tube that is installed so as to be able to face rolling surface 15. Irradiation unit 12 irradiates X-rays onto rolling surface 15. The irradiated X-rays are irradiated along arrow α so as to be incident on rolling surface 15 at a predetermined incident angle.

[0029] The detector 13 detects annular X-rays (X-ray diffraction rings) diffracted by the rolling surface 15. Specifically, the detector 13 includes a hole 13a formed in the center to allow the X-rays irradiated from the irradiation unit 12 to pass through, and a planar detection unit 13b that can be placed opposite the rolling surface 15. For example, an X-ray CCD (Charge Coupled Device) can be used as the detection unit 13b. The X-rays that enter the rolling surface 15 along the arrow α are diffracted to form a conical surface β and reach the detection unit 13b. In the detection unit 13b, the X-ray diffraction rings are detected by signals of an intensity corresponding to the intensity of the X-rays output by each pixel.

[0030] The calculation unit 14 obtains the X-ray diffraction ring intensity variation S based on the detected X-ray diffraction ring. The X-ray diffraction ring intensity variation S is the average deviation between the diffraction intensity at the central angle of the ring-shaped diffracted X-ray and each diffraction intensity, and is expressed by the following formula (2).

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[0031] The variation in the X-ray diffraction ring intensity is obtained before and after the two-cylinder test. The obtained variation in the X-ray diffraction ring intensity S 0_base , S base Inhomogeneity of X-ray diffraction ring I base The non-uniformity of the X-ray diffraction ring is calculated by the variation S of the X-ray diffraction ring intensity before the test. 0_base and the variation in X-ray diffraction ring intensity after the test S base The ratio (S base / S 0_base ).

[0032] Here, the "X-ray diffraction ring intensity" of the rolling surface indicates whether the crystal orientation of the rolling surface is random or aligned in the same direction. Specifically, the value is greater for crystals aligned in the same direction than for crystals aligned in a random direction. Usually, the crystal orientation of the rolling surface before a rolling fatigue test is random, but after the test, the crystal orientation of the rolling surface is aligned in a specific direction. Therefore, the value of the X-ray diffraction ring intensity after the test is greater than the X-ray diffraction ring intensity before the test.

[0033] In addition, the "variation of X-ray diffraction ring intensity" is the average of the deviations between the diffraction intensity at the central angle of the circular diffracted X-ray and each diffraction intensity, and the "unevenness of X-ray diffraction ring intensity" is the ratio of the variation of X-ray diffraction ring intensity before and after the test. The larger the "unevenness of X-ray diffraction ring intensity" value, the more advanced the fatigue is. In the present invention, the degree of crystal orientation (the degree to which the crystal orientation is aligned) associated with rolling can be quantified by using the "unevenness of X-ray diffraction ring intensity". Then, the ratio of the variation of X-ray diffraction ring intensity before and after the test can be taken to eliminate the influence of each individual test piece.

[0034] <Step (b)> In this step, the oil film parameter Λ of the reference lubricant in the two-cylinder test is calculated. base The oil film parameter Λ is calculated. base is calculated using the following formula (1).

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[0035] Here, the oil film thickness h in the above formula (1) can be calculated by a theoretical formula or actual measurement. When using a theoretical formula, for example, the Chittenden formula shown in the following formula (3) (Reference: Chittenden, RJ, Dowson, D., Dunn, JF, Taylor, CM, Proc. Roy. Soc. London, A397 (1985) 271) can be used.

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[0036] In the above formula (3), R x is the equivalent radius of curvature in the flow direction, R y is the equivalent radius of curvature perpendicular to the flow. R x is 1 / Rx =(1 / R x1 )+(1 / R x2 ) and R y is 1 / R y =(1 / R y1 )+(1 / R y2 ) is calculated by R x1 is the radius of curvature of one cylinder in the flow direction, and R x2 is the radius of curvature of the other cylinder in the flow direction, and R y1 is the radius of curvature of one of the cylinders in the direction perpendicular to the flow, and R y2 is the radius of curvature of the other cylinder in the direction perpendicular to the flow. In the above equation (3), U is the velocity parameter, (η0×u) / (E′×R x ) where η0 is the normal pressure viscosity. η0 is calculated by ρ×ν, where ρ is the density of the lubricating oil and ν is the kinetic viscosity of the lubricating oil. u is the average value of the peripheral speed of one cylinder and the peripheral speed of the other cylinder. E′ is the equivalent Young's modulus. E′ is calculated by 2 / E′={(1-ν1 2 ) / E1}+{(1-ν2 2 ) / E2}, where E1 is the Young's modulus of one cylinder, and E2 is the Young's modulus of the other cylinder. ν1 is the Poisson's ratio of one cylinder, and ν2 is the Poisson's ratio of the other cylinder.

[0037] In the above formula (3), G is a material parameter and is calculated by α×E′. α is a viscosity pressure coefficient. α is calculated by the Wu-Klaus-Duda formula. More specifically, α is (0.1657+0.2332×log 10 ν)×m×10 -8 where ν is the kinetic viscosity of the lubricating oil. m is a constant determined by the lubricating oil and is calculated by the Walther-ASTM formula. More specifically, m is log 10 {log 10 (ν+0.7)}=-m×log 10It is calculated by T+K, where T is the temperature and K is a constant determined by the lubricant. The values ​​of m and K can be calculated by substituting the two temperatures and the kinematic viscosity at those two temperatures into the Walther-ASTM formula and solving the simultaneous equations. W is a load parameter, and is expressed as w / (E′×R x 2 ) where w is the load.

[0038] Although the oil film thickness h can be easily calculated using a theoretical formula, it is preferable to calculate the oil film thickness h by actual measurement in terms of accuracy. By calculating the oil film thickness h more accurately, a more accurate reference line can be obtained in the subsequent step (c).

[0039] When measuring by actual measurement, for example, the electrical resistance and capacitance of the oil film formed between the two cylinders in a two-cylinder test are measured. A voltage is applied between the two cylinders to measure the capacitance of the oil film. In this case, the oil film can be regarded as an electrical equivalent circuit that regards it as a capacitor. Since there is a correlation between the capacitance of the oil film and the oil film thickness h, the oil film thickness h can be calculated from the capacitance of the oil film based on this correlation. Note that the conditions of the two-cylinder test when calculating the oil film thickness h are preferably the same as those of the two-cylinder test in step (a).

[0040] <Step (c)> In this step, the inhomogeneity of the X-ray diffraction ring intensity I obtained in step (a) is base and the oil film parameter Λ obtained in step (b). base A reference line is obtained from the above. Here, FIG. 3 is a graph showing the relationship between the nonuniformity of the X-ray diffraction ring intensity and the oil film parameter, where the horizontal axis is the oil film parameter and the vertical axis is the nonuniformity of the X-ray diffraction ring intensity. For example, the oil film parameter Λ, which is the measurement result of five lubricants, is shown in this graph. base Inhomogeneity of X-ray diffraction ring intensity for I base By plotting each of these, a reference line L can be drawn as shown in Figure 3. As shown in Figure 3, there is a correlation between the nonuniformity of the X-ray diffraction ring intensity and the oil film parameters, and the reference line L can also be approximated by a certain relational expression.

[0041] In this way, the reference line L shown in FIG. 3 is obtained by steps (a) to (c). In creating the reference line, it is necessary to use a plurality of reference lubricants. In the above, five types of lubricants are used, but the number of lubricants is not limited to this. In addition, the kinetic viscosities of these lubricants (the kinetic viscosity of the base oil in the case of grease) are different from one another. For example, if the kinetic viscosity at 40°C is 5 mm 2 / s~180mm 2 By using multiple lubricants with different kinetic viscosities in a wide range, it is possible to calculate the oil film parameters of lubricants with various kinetic viscosities.

[0042] <Step (d)> This step is the same as step (a) above, except that any lubricant is used to determine whether it can be used as a lubricant. That is, a two-cylinder test is performed on any lubricant, and the unevenness I (=S / S0) of the X-ray diffraction ring intensity of the rolling surface is determined by measuring the variations S0 and S in the X-ray diffraction ring intensity of the rolling surface before and after the test. The conditions for the two-cylinder test and X-ray analysis performed in step (d) are the same as those in step (a).

[0043] <Step (e)> In this step, as shown by the arrow in Figure 3, the oil film parameter Λ of any lubricant is calculated by reading the value of the oil film parameter on the reference line L from the nonuniformity I of the X-ray diffraction ring intensity obtained in step (d). Note that, in the case where the reference line L can be approximated by a predetermined relational expression, step (e) also includes calculating the oil film parameter Λ by substituting the nonuniformity I of the X-ray diffraction ring intensity into the relational expression.

[0044] The kinematic viscosity at 40° C. of the arbitrary lubricant used in steps (d) and (e) to determine whether it can be used or not is not particularly limited, and may be, for example, 5 mm 2 / s~180mm 2The method for calculating the oil film parameter of the present invention is suitable for calculating the oil film parameter of a low-viscosity lubricant. Therefore, the kinetic viscosity of any lubricant at 40° C. is in the range of 5 mm 2 / s~80mm 2 / s is preferred, 5mm 2 / s~30mm 2 / s is more preferred.

[0045] By using the oil film parameter Λ calculated using the above steps (a) to (e), it is possible to determine whether or not a given lubricant can be used for a bearing or the like used under a given condition. For example, by using the calculated oil film parameter Λ, iso The life time can be calculated by a life calculation method such as those described above, and if the required life time is met, it can be determined that the product can be used. EXAMPLES

[0046] (i) Obtaining a baseline for the Λ-I characteristic diagram When obtaining the reference line, five types of lubricants (lubricants 1 to 5) with different kinetic viscosities were used. A two-cylinder test was carried out using each of these lubricants. A schematic diagram of the two-cylinder test machine is shown in FIG. 4. This two-cylinder test machine is equipped with a driving side test piece 21 and a driven side test piece 22 in rolling contact with each other, and each test piece (ring) is supported by a support bearing 24, and a load is applied by a load spring 25. In addition, 23 in the figure is a driving pulley, and 26 is a non-contact tachometer. <Test conditions> Oil temperature: 32℃ Surface pressure: 2.3GPa Rotational speed: 500 min-1 Load count: 50,000 times

[0047] Variation in X-ray diffraction ring intensity of the rolling surface of the driving test piece before and after the two-cylinder test S 0_base , S base The measurement was performed as shown in Figure 2, and the non-uniformity of the X-ray diffraction ring intensity on the rolling surface I base (S base / S 0_base ) was sought.

[0048] Film thickness parameter Λ for five lubricants base The oil film thickness h was calculated using the Chittenden formula. The non-uniformity of X-ray diffraction ring intensity I of the five lubricants base , and the oil film parameter Λ base are also shown in Table 1.

[0049] [Table 1]

[0050] The oil film parameter Λ of the five obtained lubricants base Inhomogeneity of X-ray diffraction ring intensity for I base were plotted to obtain the reference line shown in FIG. 5.

[0051] (ii) Calculation of the oil film parameter Λ for any lubricant Seven types of lubricants (lubricants A to G) were used as arbitrary lubricants. The type of each lubricant and the kinematic viscosity at 40 ° C. are shown in Table 2. Lubricants F and G are obtained by adding a phosphorus-based additive and a sulfur-based additive to the above-mentioned lubricant 1, respectively. The seven types of lubricants were subjected to a two-cylinder test under the same conditions as the two-cylinder test performed in (i) above. In addition, the variations S0 and S in the X-ray diffraction ring intensity of the rolling surface of the driving side test piece were measured before and after the two-cylinder test, and the non-uniformity I of the X-ray diffraction ring intensity of the rolling surface was obtained. Then, based on the obtained non-uniformity I of the X-ray diffraction ring intensity, the oil film parameter Λ was calculated from the reference line shown in Figure 5. The non-uniformity I of the X-ray diffraction ring intensity and the oil film parameter Λ of each lubricant are also shown in Table 2. The oil film parameter Λ is a value on the reference line in Figure 5.

[0052] For comparison, the oil film parameters of seven types of lubricants calculated by the conventional method are also shown in Table 2. The nonuniformity of the X-ray diffraction ring intensity versus the calculated oil film parameters is plotted in Figure 5. This conventional method uses the above formula (1). The oil film thickness h was calculated using Chittenden's formula.

[0053] [Table 2]

[0054] Lubricant A has a CVTF (kinetic viscosity at 40°C of 29mm 2 The nonuniformity of the X-ray diffraction ring intensity at 1000 / s was 13.08, which is plotted above the reference line of the Λ-I characteristic diagram. Therefore, it is found that it is more prone to fatigue than lubricants of the same kinematic viscosity. This is due to the effect of traction, which is a characteristic of CVTF, and as a result, the oil film parameter Λ is 0.24. On the other hand, the oil film parameter of the conventional method is 0.34, which is large compared to the oil film parameter Λ, and does not reflect the effect of traction, which is a characteristic of CVTF.

[0055] Lubricant B has a CVTF (kinetic viscosity at 40°C of 26mm 2 The nonuniformity of the X-ray diffraction ring intensity at 1000 / s was 16.27, which is plotted above the reference line of the Λ-I characteristic diagram. Therefore, it is found that it is more prone to fatigue than lubricants of the same kinematic viscosity. This is due to the effect of traction, which is a characteristic of CVTF, and as a result, the oil film parameter Λ is 0.17. On the other hand, the oil film parameter of the conventional method is 0.30, which is large compared to the oil film parameter Λ, and does not reflect the effect of traction, which is a characteristic of CVTF.

[0056] Lubricant C has a CVTF (kinetic viscosity at 40°C of 27mm 2 The nonuniformity of the X-ray diffraction ring intensity at 1000 rpm (1 / s) is 23.15, which is plotted above the reference line of the Λ-I characteristic diagram. Therefore, it is found that it is more prone to fatigue than lubricants with the same kinematic viscosity. This is due to the effect of traction, which is a characteristic of CVTF, and as a result, the oil film parameter Λ is 0.09. On the other hand, the oil film parameter of the conventional method is 0.33, which is large compared to the oil film parameter Λ, and does not reflect the effect of traction, which is a characteristic of CVTF.

[0057] Lubricant D is ATF (kinetic viscosity 24 mm at 40°C) 2The nonuniformity of the X-ray diffraction ring intensity at 1000 / s is 11.09, which is plotted on the reference line of the Λ-I characteristic diagram. Therefore, it can be seen that the lubricant fatigues to the same extent as a lubricant of the same kinetic viscosity. This is because the effect of additives and the influence of traction are small, and as a result, the oil film parameter Λ is 0.32. On the other hand, the oil film parameter of the conventional method is 0.32, and there is no change in the oil film parameter Λ, and the effect of additives and the influence of traction are small.

[0058] Lubricant E is ATF (kinetic viscosity 12 mm at 40°C) 2 The non-uniformity of the X-ray diffraction ring intensity at 1000 / s is 13.27, which is plotted below the reference line of the Λ-I characteristic diagram. Therefore, it is found that it is less prone to fatigue than lubricants with the same kinetic viscosity. This is the effect of the additive, and as a result, the oil film parameter Λ is 0.24. On the other hand, the oil film parameter of the conventional method is 0.19, which is smaller than the oil film parameter Λ, and the effect of the additive is not reflected.

[0059] For lubricant F, the nonuniformity of the X-ray diffraction ring intensity is 5.68, which is plotted below the reference line of the Λ-I characteristic diagram. Therefore, it is found that it is less prone to fatigue than lubricants with the same kinematic viscosity. This is the effect of the phosphorus-based additive, and as a result, the oil film parameter Λ is 1.02. On the other hand, the oil film parameter of the conventional method is 0.12, which is smaller than the oil film parameter Λ, and the effect of the phosphorus-based additive is not reflected.

[0060] For lubricant G, the nonuniformity of the X-ray diffraction ring intensity is 9.40, which is plotted below the reference line of the Λ-I characteristic diagram. Therefore, it is found to be less prone to fatigue than lubricants with the same kinetic viscosity. This is the effect of the sulfur-based additive, and as a result, the oil film parameter Λ is 0.43. On the other hand, the oil film parameter of the conventional method is 0.12, which is smaller than the oil film parameter Λ, and does not reflect the effect of the sulfur-based additive.

[0061] As described above, according to the calculation method of the present invention, in the case of lubricants that are greatly influenced by traction such as CVTF, the oil film parameter Λ can be estimated smaller than the oil film parameter calculated by the conventional calculation method as a result of reflecting the influence of traction that acts unfavorably on fatigue. In addition, in the case of lubricants in which additives are added, the oil film parameter Λ can be estimated larger than the oil film parameter calculated by the conventional method as a result of reflecting the effect of additives that act favorably on rolling fatigue. On the other hand, if the additives are not effective against rolling fatigue, the oil film parameter Λ can be estimated to be equivalent to the oil film parameter calculated by the conventional method, taking into account the effect of the additives. As a result, it is possible to properly judge whether the lubricant can be used. [Industrial Applicability]

[0062] The method for calculating the oil film parameter of the present invention can calculate the oil film parameter of a lubricant while taking into account the effects of additives, thickeners, traction, etc., and can be widely used in fields such as automobiles and industrial machinery. [Explanation of symbols]

[0063] 1. Rolling bearings 2. Inner Circle 3 Outer ring 4 balls 5 Cage 6 Sealing material 7 Grease 8 Openings 11 Measuring equipment 12 Irradiation unit 13 Detector 14 Arithmetic section 15 Rolling surface 21 Drive side test piece 22 Driven side test piece 23 Drive pulley 24 Support bearing 25 Load spring 26 Non-contact tachometer

Claims

1. A method for calculating an oil film parameter of any lubricant, comprising the steps of: A rolling fatigue test was carried out for each of a number of standard lubricants having different kinetic viscosities, and the variation S in the X-ray diffraction ring intensity of the rolling surface before and after the test was measured. ０＿ｂａｓｅ , S ｂａｓｅ The non-uniformity I of the X-ray diffraction ring intensity of the rolling surface before and after the test was measured. ｂａｓｅ (=S ｂａｓｅ / S ０＿ｂａｓｅ ) The oil film parameter Λ of the reference lubricant in the rolling fatigue test ｂａｓｅ and (b) calculating The oil film parameter Λ ｂａｓｅ The inhomogeneity of the X-ray diffraction ring intensity I ｂａｓｅ (c) plotting the above on a graph to obtain a reference line showing the relationship between the above and the above; The rolling fatigue test is carried out on the arbitrary lubricant, and the variation S of the X-ray diffraction ring intensity of the rolling surface before and after the test is ０ , S, and the non-uniformity I (= S / S) of the X-ray diffraction ring intensity before and after the test on the rolling surface was calculated. ０ ) (d) determining and (e) calculating an oil film parameter value on the reference line of the obtained X-ray diffraction ring intensity nonuniformity I as an oil film parameter Λ of the arbitrary lubricant; The method for calculating an oil film parameter, wherein the step (b) calculates the oil film parameter Λ base using the following formula (1): [0010] In the formula, the symbols are: h: oil film thickness [μm] of the oil film formed on the contact surfaces of two objects in rolling contact in the rolling fatigue test; σ1: root mean square roughness [μm] of one of the two objects; and σ2: root mean square roughness [μm] of the other object.

2. 2. The method for calculating an oil film parameter according to claim 1, wherein the rolling fatigue test in the step (a) is a two-cylinder test in which two cylinders are brought into contact with each other and a load is applied thereto.

3. 2. The method for calculating an oil film parameter according to claim 1, wherein the oil film thickness in the formula (1) is calculated by a theoretical formula.

4. 2. The method for calculating an oil film parameter according to claim 1, characterized in that the oil film thickness in the formula (1) is calculated by measuring the electrical resistance and electrostatic capacitance of the oil film formed between two cylinders in a two-cylinder test in which two cylinders are brought into contact with each other and a load is applied thereto.

5. The kinetic viscosity of the any lubricant is 5 mm ２ / s ~ 80mm ２ The method for calculating an oil film parameter according to any one of claims 1 to 4, characterized in that the oil film parameter is / s.

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