JP7064383B2 - Performance evaluation method for rolling parts - Google Patents

Description

The present invention relates to a method for evaluating the performance of a rolling component, and more specifically, the performance of a rolling component that evaluates the performance of the rolling component by estimating the fatigue level and the remaining life of the rolling component in use. Regarding the evaluation method.

It is known that the life of rolling bearings (hereinafter also referred to as bearings) depends on operating conditions such as load and lubrication conditions, and material properties such as hardness, structure, and residual stress of rolling parts that make up the bearing. There is. Therefore, the life of the bearing is estimated using the life calculation formula that can be calculated from the operating conditions and material characteristics of the bearing. This formula is used to estimate how long the bearing can be used under certain conditions, or under what conditions the bearing should be used so that the bearing will not be damaged during the required usage period. Is used for.

Generally, bearings are used under the conditions of use set based on the life calculation formula. Therefore, if the bearing is used under the assumed conditions, life should not be an issue. However, bearing life is often an issue in the market. It is considered that this is because the life of the bearing may be unexpectedly shortened due to the disturbance such as the usage environment in the actual bearing. Therefore, in bearings, there is a need to estimate the actual fatigue degree of the bearing based on some analysis result and manage the risk of bearing breakage from the fatigue degree. There is also a need to estimate the remaining life from the degree of fatigue assuming the progress of fatigue in the future, and to quantitatively predict the bearing replacement time from the remaining life. Furthermore, if the rolling component fatigue degree and remaining life estimation are applied to the rolling component during the rolling fatigue test, the rolling component does not have to be tested until it reaches the end of its life, that is, until peeling occurs. The fatigue characteristics of rolling parts can be evaluated from the rapid progress of fatigue. As a result, it can contribute to speeding up the development of rolling parts.

For example, Japanese Patent Application Laid-Open No. 2014-167421 describes a method for predicting damage forms such as peeling, flaking, wear, and smearing from a plasticity index obtained from the contact pressure of a bearing and the protrusion shape of surface roughness. Has been done. Further, a method of predicting the life of peeling, which is a kind of surface-origin type damage, from conditions such as contact pressure, plasticity index, and slip rate is described.

For the method of estimating the remaining life for peeling, see "Application of X-ray stress measurement to bearing failure analysis" by Tsushima Masayuki et al., Bearing Engineer No. 49 (1984), pp. 25-34, shown in. In this paper, the degree of fatigue when peeling occurs is estimated from the residual stress measured by X-rays and the amount of change in the half-value width, and the remaining life is estimated from the degree of fatigue.

In Japanese Unexamined Patent Publication No. 2014-13188, various X-ray analysis values (for example, stress, residual austenite amount, annular diffraction X) obtained from annular diffracted X-rays generated when the rolling portion of a bearing component is irradiated with X-rays. A database is created of the diffraction intensity distribution with respect to the central angle of the line, the half-value width with respect to the central angle, etc. A method of estimating and estimating the life of a bearing from its usage conditions is disclosed.

Japanese Unexamined Patent Publication No. 2014-167421 Japanese Unexamined Patent Publication No. 2014-13188

Tsushima Masayuki et al., "Application of X-ray stress measurement to bearing damage analysis", Bearing Engineer No. 49 (1984), pp. 25-34

The method disclosed in Japanese Patent Application Laid-Open No. 2014-167421 described above can be used to obtain the form and life of surface-based damage if the conditions of use such as contact pressure, plasticity index indicating the severity of surface roughness contact, and slip rate are known. Can be predicted. However, the usage conditions of the bearing and the degree of fatigue of the bearing, that is, the means for predicting the degree of fatigue of the bearing are not shown, and it is difficult to estimate the remaining life.

The method disclosed in the above-mentioned paper "Application of X-ray stress measurement to bearing failure analysis" assumes that the product of the increase in compressive residual stress and the decrease in half-value width is the parameter corresponding to the degree of fatigue. However, the remaining life of the rolling parts is estimated from the relationship between the parameters and the life of the rolling parts obtained under specific test conditions. The rationale for the assumption that the product of the increase in compressive residual stress and the decrease in half-value width is the parameter corresponding to the degree of fatigue corresponds to the life of the rolling parts obtained under specific test conditions. The relationship has been seen. However, this relationship is not theoretically obtained, but is a correspondence between the degree of fatigue and the X-ray analysis value under specific experimental conditions. Therefore, since the relationship can change greatly depending on the test conditions, there is a problem in the estimation accuracy of the degree of fatigue and the remaining life.

The method disclosed in Japanese Patent Application Laid-Open No. 2014-13188 uses an X-ray diffractive ring analyzer that can obtain more information on rolling fatigue than the conventional device, and uses various X-ray analysis results and various rolling conditions (use). This is a method of constructing a database with surface pressure, lubrication conditions, slip conditions, etc., estimating the bearing usage conditions from the database, and estimating the remaining life. In this method, if the life can be estimated from the estimated usage conditions by the method of JP-A-2014-167421, the degree of fatigue will be clarified under the condition that the usage time up to the present is known. Furthermore, assuming that the subsequent usage conditions are the same as the current usage conditions, the remaining life of the bearing parts can be estimated. However, this method also has a large error in estimating the remaining life because assumptions are made in the subsequent usage conditions. Further, in this method, the usage conditions (for example, the number of loads, the load, the lubrication conditions, the slip, etc.) of the complicated rolling parts are statistically estimated from the X-ray analysis values. Therefore, if there is no database based on a huge amount of experiments, the estimation accuracy of the usage conditions will be low, and as a result, the estimation accuracy of the remaining life will be deteriorated.

Here, the inventor is considering evaluating the performance of a rolling component by utilizing the fatigue level or remaining life of the rolling component described above, but as described above, the conventional method has a fatigue level or remaining life. The estimation accuracy was low, and it was difficult to evaluate the performance of rolling parts with high accuracy by utilizing the degree of fatigue or the remaining life.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to utilize the fatigue degree or the remaining life by estimating the fatigue degree and the remaining life with high accuracy. It is to provide a performance evaluation method for rolling parts, which can perform performance evaluation of rolling parts with high accuracy.

The method for evaluating the performance of a rolling component according to the present disclosure includes a step of estimating the degree of fatigue of the rolling component and a step of evaluating the performance of the rolling component. In the step of estimating the fatigue level, the fatigue level of the rolling component is estimated for each of the rolling components to which the rolling component is repeatedly loaded in a plurality of states in which the number of times the repeated load is applied to the rolling component is different from each other. .. In the step of evaluating the performance of the rolling component, the performance of the rolling component is evaluated based on the relationship between the number of loads in a plurality of states and the degree of fatigue corresponding to the number of loads. The step of estimating the degree of fatigue includes a step of acquiring measurement data and a step of estimating the degree of fatigue. In the step of acquiring the measurement data, the fatigued portion of the rolling component is irradiated with X-rays to acquire the measurement data of the X-ray analysis value of the rolling component. In the step of estimating the degree of fatigue, the degree of fatigue of the rolling component is estimated from the measurement data based on the relationship between the X-ray analysis value and the degree of fatigue of the rolling component.

The rolling component performance evaluation method according to the present disclosure includes a step of estimating the remaining life and a step of evaluating the performance of the rolling component. In the step of estimating the remaining life, the remaining life of the rolling parts is estimated for each of the rolling parts to which the rolling parts are repeatedly loaded in a plurality of states in which the number of times the repeated loads are applied to the rolling parts is different from each other. In the performance evaluation step, the performance of rolling components is evaluated based on the relationship between the number of loads and the remaining life in a plurality of states. The steps for estimating the remaining life are the step of acquiring the measurement data of the X-ray analysis value, the step of acquiring the measurement data of the surface shape, the step of deriving the data of the residual stress, and the step of estimating the data of the repetitive stress. It includes a step of estimating the life, a step of estimating the degree of fatigue, and a step of estimating the remaining life. In the step of acquiring the measurement data of the X-ray analysis value, the measurement data of the X-ray analysis value of the rolling component is acquired by irradiating the fatigued portion of the rolling component with X-rays. In the step of acquiring the surface shape measurement data, the fatigued portion of the rolling component is measured and the surface shape measurement data is acquired. In the step of deriving the residual stress data, the residual stress data in the fatigued portion of the rolling component is derived based on the measurement data of the X-ray analysis value. In the step of estimating the repeated stress data, the repeated stress data acting on the fatigued portion is estimated based on the residual stress data and the surface shape measurement data. In the step of estimating the life, the life of the rolling parts is estimated from the data of the repetitive stress. In the step of estimating the fatigue degree, the fatigue degree of the rolling component is estimated from the measurement data of the X-ray analysis value based on the relationship between the X-ray analysis value and the fatigue degree of the rolling component. In the step of estimating the remaining life, the remaining life of the rolling component is estimated based on the life and the degree of fatigue of the rolling component.

According to the above, it is possible to obtain a performance evaluation method for rolling parts, which can perform performance evaluation of rolling parts with high accuracy by utilizing the degree of fatigue or remaining life.

It is a flowchart for demonstrating the performance evaluation method of the rolling part which concerns on this embodiment. It is a flowchart for demonstrating the modification of the performance evaluation method of a rolling part which concerns on this embodiment. It is a graph for demonstrating the performance evaluation method of the rolling part which concerns on this embodiment. It is a flowchart for demonstrating the process of finding the remaining life of a rolling part. It is a flowchart for demonstrating the process of creating a database which shows the relationship between the X-ray analysis value and the fatigue degree of a rolling part. It is a schematic diagram which shows the structural example of the measuring apparatus of the X-ray analysis value. It is a schematic diagram for demonstrating the minute unevenness of the rolling surface of a rolling component. It is a graph for demonstrating the relationship between the SN diagram and the degree of fatigue. It is a graph which shows the relationship between the history of equivalent stress and the residual life schematically. It is a graph which shows the relationship between the number of loads and the variation of the diffraction intensity. It is a schematic diagram which shows the structure of a two-cylindrical tester. It is a graph which shows the change of the residual stress (equivalent stress) in an Example. It is a graph which shows the change of the root mean square slope R _dq in an Example.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the same or corresponding parts will be given the same reference number and the explanation will not be repeated.

<Outline of performance evaluation method for rolling parts>
FIG. 1 is a flowchart for explaining a performance evaluation method of a rolling component according to the present embodiment. FIG. 2 is a flowchart for explaining a modified example of the performance evaluation method of the rolling component according to the present embodiment. FIG. 3 is a graph for explaining a performance evaluation method for rolling components according to the present embodiment. Hereinafter, the outline of the performance evaluation method of the rolling parts according to the present embodiment will be described.

As shown in FIG. 1, the method for evaluating the performance of a rolling component according to the present disclosure includes a step of estimating the degree of fatigue of the rolling component (S1) and a step of evaluating the performance of the rolling component (S2). .. In the step (S1) of estimating the degree of fatigue, for a rolling component to which a repeated load is applied, for example, in a rolling fatigue test, regarding a plurality of states in which the number of times of repeated loading in the rolling component is different from each other. Estimate the degree of fatigue of each rolling component. For example, a step (S1) of estimating the degree of fatigue is performed every fixed number of loads. The details of the step (S1) for estimating the degree of fatigue will be described later. In the step (S2) of evaluating the performance of the rolling component, as shown in FIG. 3, the rolling component is based on the relationship between the number of loads in a plurality of states and the degree of fatigue, which is evaluation data corresponding to the number of loads. Evaluate performance. In FIG. 3, the horizontal axis indicates the period of use, that is, the number of loads, and the vertical axis indicates the value of the evaluation data. Here, the value of the degree of fatigue is shown as evaluation data. As shown in FIG. 3, when the data showing the relationship between the number of loads and the degree of fatigue is plotted for the rolling parts, the data group shown in the first group 10 is obtained for the rolling parts in a normal use state. .. On the other hand, it can be seen that the rolling parts showing the data 11 outside the first group 10 are fatigued faster than the rolling parts included in the first group 10. Further, the rolling parts showing the data 12 outside the first group 10 are used under the condition that the fatigue progresses slower than the rolling parts included in the first group 10 and the life is long. I understand.

Further, the performance evaluation method of the rolling component shown in FIG. 2 includes a step of estimating the remaining life (S3) and a step of evaluating the performance of the rolling component (S2). In the step (S3) of estimating the remaining life, the remaining life of the rolling parts is determined for each of the rolling parts to which the rolling parts are repeatedly loaded in a plurality of states in which the number of times of the repeated loading of the rolling parts is different from each other. presume. In the step (S2) of evaluating the performance, the performance of the rolling component is evaluated based on the relationship between the number of loads and the remaining life in a plurality of states. The details of the step (S3) for estimating the remaining life will be described later. In the performance evaluation step (S2), the remaining life estimated in the above step (S3) is shown in a graph in which the number of loads is taken on the horizontal axis and the remaining life is taken on the vertical axis, as in the performance evaluation method shown in FIG. By plotting the data of, the performance of the rolling component can be evaluated from the change in the remaining life of the rolling component with respect to the number of loads.

<Estimation method of remaining life>
About remaining life:
The remaining life of the bearing is determined by how tired the bearing is at the present time (fatigue degree) and the conditions of subsequent use. Fatigue and remaining life are easily confused, but the difference is easy to understand by looking at the following formula that expresses the Miner's Rule (hereinafter referred to as the Miner's Rule).

In the above formula (1), when the lifetime at a certain stress amplitude is L1, L2 ... Li ... Ln, the load is N1, N2, ... Ni ... Nn times at each stress amplitude. It is an empirical formula that the life is reached when the linear sum of the ratio of the load to each life reaches 1. In this equation, the inside of the broken line square on the left side is the degree of fatigue indicating "how long it has been used under certain usage conditions". Further, Nn in the last term on the left side of the above equation (1) has a remaining life indicating "how long can it be used thereafter". As is clear from this equation (1), the remaining life cannot be estimated unless the fatigue degree (that is, within the broken line square in the equation (1)) and the life Ln determined by the subsequent usage conditions are known. Therefore, in the fatigue degree estimation, it is a problem to devise an analysis method for accurately estimating the fatigue degree in the broken line square of the equation (1). Further, in the estimation of the remaining life, in addition to the accurate estimation of the degree of fatigue, it is an issue to devise a method for predicting the future life from the usage conditions.

Specific estimation method of remaining life:
FIG. 4 is a flowchart for explaining a process for obtaining the remaining life of a rolling component. As shown in FIG. 4, in the method of estimating the remaining life of the rolling component, first, the surface shape measuring step (S20) of the rolling component is carried out. Next, the step (S21) of estimating the oil film parameters from the data obtained in the step (S20) and the data of the operating conditions of the rolling parts, specifically, the rotation speed, the operating temperature, the load, the lubricating oil conditions, and the like. To carry out. When the oil film parameter is 3 or less, the tip of the convex portion of the minute unevenness on the surface of the rolling surface of the rolling component can be in direct contact with the tip of the convex portion of the minute unevenness on the surface of the rotating member in contact with the rolling surface. There is sex. In this case, stress concentration (hereinafter referred to as micro stress) occurs due to minute irregularities on the surface of the rolling component. Surface-origin damage is due to this microstress. In the performance evaluation method according to the present embodiment, the performance is evaluated by focusing on the surface-origin type damage (for example, peeling). Therefore, by confirming that the oil film parameter is 3 or less in the above step (S21), it can be confirmed that the performance evaluation method according to the present embodiment can be applied. Whether or not a rolling component such as a bearing in use causes surface-origin type peeling is determined by the state of the surface shape. Therefore, in the process of estimating the remaining life in the performance evaluation method according to the present embodiment, the calculation step (S22) of the stress state of the rolling surface is carried out.

Hereinafter, an example of a specific method for calculating the stress state in step (S22) will be shown.
First, the root mean square slope shown in the paper by Ioannides et al. (E. Ioannides, G. Bergling, A. Gabelli, "An Analytical Formulation for the Life of Rolling Bearings", ACTA POLYTECHNICA SCANDINAVICA, MECHANICAL ENGINEERING SERIES No.137). Suppose the relationship shown by the following equation (2) that is proportional to the micro stress.

The roughness produced by grinding has directionality, and long and thin protrusions are present on the grinding surface along the grinding direction as shown in FIG. 7. Here, FIG. 7 is a schematic diagram for explaining minute irregularities on the rolling surface of the rolling component. In FIG. 7, the direction indicated by the arrow 31 is the grinding direction. The convex portion 30 of the minute unevenness is formed so as to extend along the grinding direction indicated by the arrow 31. Here, if the cross-sectional shape of the object is uniform and has a sufficient length, it can be regarded as a plane strain state except for both ends thereof. Therefore, it is possible to assume a plane strain stress state in the contact portion of the minute unevenness, and the internal stress under the micro contact portion on the surface can be calculated by the following equations (3) to (6). For the friction coefficient μ, an approximate value under the boundary lubrication condition, for example, an appropriate value such as 0.1 may be substituted. In the following equation, the xyz coordinates may be defined as follows, for example. That is, when considering a test piece in a two-cylinder test as a rolling component, the z-axis is an axis extending radially from the outer peripheral surface of the test piece, and the x-axis is along the rotation direction of the test piece and in the tangential direction from the outer peripheral surface. The y-axis is the axis extending from the outer peripheral surface of the test piece in the direction along the rotation axis. When considering the inner ring of a rolling bearing as a rolling component, the z-axis is an axis extending radially from the outer peripheral surface (rolling surface) of the inner ring, and the x-axis is along the rotation direction of the inner ring and tangent from the outer peripheral surface. The axis extends in the direction, and the y-axis is an axis extending from the outer peripheral surface of the inner ring in the direction along the rotation axis.

The equivalent stress can be calculated by the following formula.

From the above, if the root mean square slope R _dq is measured, the triaxial stress directly under the micro-contact portion can be calculated by using equations (2) to (7), leaving the unknown constant a in equation (2). can.

On the other hand, when a high stress is generated on the raceway surface of the rolling component, a high residual stress is gradually generated on the raceway surface due to repeated plastic deformation. Therefore, when the rolling component is rolled, the residual stress is superimposed on the above-mentioned micro stress. Therefore, it is necessary to predict the repetitive stress of the surface layer, which determines the life due to surface-origin type peeling, in consideration of both the micro stress due to unevenness and the residual stress. Therefore, in the remaining life estimation process shown in FIG. 4, the residual stress is calculated from the result of the X-ray diffraction ring analysis on the surface (rolling surface) of the rolling component, and the micro stress obtained in step (S22) is superimposed. At the same time, the equivalent stress (repeated stress) just below the contact part is calculated. Specifically, after performing the X-ray diffraction ring analysis step (S10) of the rolling component, the step (S12) for calculating the residual stress of the rolling surface is performed to obtain the residual stress, and then the rolling surface. The calculation step (S30) of the repetitive stress in consideration of the residual stress of is carried out.

In step (S10), the X-ray diffractometric ring is measured using, for example, a measuring device as shown in FIG. FIG. 6 is a schematic diagram showing a configuration example of an X-ray analysis value measuring device. As shown in FIG. 6, the measuring device includes an irradiation unit 21 that irradiates an object 90 such as a rolling component with X-rays, and a detector 22 that detects an annular X-ray diffracted by the object 90 to be measured. A control calculation unit 23 connected to the detector 22 and calculating a predetermined X-ray analysis value based on the detection data of the annular X-ray detected by the detector 22 and storing the detection data, and a control calculation. It is connected to the unit 23 and includes a display unit 24 that displays the calculation result and the detection data in the control calculation unit 23.

The irradiation unit 21 includes an X-ray tube installed so as to face the object to be measured 90. The detector 22 includes a hole formed in a central portion through which X-rays emitted from the irradiation unit 21 pass, and a planar detection unit 22A capable of facing the measurement object 90. An X-ray CCD may be adopted for the detector 22A of the detector 22. The control calculation unit 23 calculates the X-ray analysis value of the measurement object 90 based on the database stored in the storage unit (not shown) in advance and the ring-shaped X-ray detection data detected by the detector 22. You may. The calculated X-ray analysis value and detection data are displayed on the display unit 24.

In the X-ray diffraction ring analysis step (S10) using the measuring device shown in FIG. 6, first, the measurement target 90 is prepared, and the step (S101) of irradiating the fatigued portion of the measurement target 90 with X-rays is performed. Will be implemented. In this step (S101), the measurement object 90, which is a rolling component, is set at a predetermined position, and the irradiation unit 21 irradiates the measurement object 90 with X-rays. At this time, as shown in FIG. 6, X-rays are emitted along the arrow α so as to be incident on the measurement object 90 at a predetermined incident angle.

Next, the step (S102) in which the X-ray diffractometric ring is detected is carried out. In this step (S102), as shown in FIG. 6, X-rays incident on the measurement object 90 along the arrow α are diffracted so as to form the conical surface β and reach the detection unit 22A. Then, for example, in the detection unit 22A which is an X-ray CCD, an annular diffracted X-ray (X-ray diffractogram) is detected by a signal having an intensity corresponding to the intensity of the X-ray output by each pixel. The X-ray analysis value can be obtained from the above-mentioned measurement data of the annular diffracted X-ray. The X-ray analysis value is data showing the variation between the central angle and the diffraction intensity of the annular diffracted X-ray diffracted in the fatigued portion of the measuring object 90 which is a rolling component, and the measuring object 90 which is a rolling component. It consists of data on the residual stress of the six components in the fatigued part, data on the half-value width of the peak of the diffracted X-ray diffracted in the fatigued part of the object to be measured 90, and data on the amount of retained austenite in the fatigued part of the object to be measured 90. It may be one data selected from the group, or it may be a combination of at least two data selected from the above group. The above-mentioned data of the residual stress of the six components are, for example, normal stress σx in the direction along the x-axis direction, normal stress σy in the direction along the y-axis direction, normal stress σz in the direction along the z-axis direction, and xy plane. The shear stress τxy generated inside, the shear stress τxz generated in the xz plane, the shear stress τyz generated in the yz plane, and the like.

After the above step (S10), a step (S11) for estimating the fatigue degree from the relationship between the fatigue degree and the X-ray analysis value is performed, and the fatigue degree D is specified (step (S13)). The relationship between the degree of fatigue and the X-ray analysis value is specified based on the data of the X-ray analysis of the rolling parts and the surface shape measurement. An example of how to obtain the relationship will be described later. The obtained fatigue degree D is used for estimating the remaining life as described later.

Further, after the above step (S10), a step (S12) of calculating the residual stress of the rolling surface based on the data obtained in the step (S10) is carried out. The obtained residual stress value is used in the calculation of the repetitive stress in step (S30).

Here, the value of the triaxial residual stress is required for the calculation of the repetitive stress. As a method for calculating the triaxial residual stress, an X-ray stress measuring method capable of measuring the triaxial residual stress is applied. Any method can be used as such an X-ray stress measurement method. For example, the paper by Dolle et al. ("The Influence of Stress States, Stress Gradients and Elastic Anisotropy on the Evaluation of (Residual) Stresses by X-" rays ”, J. Appl. Crysr., 12 (1979) 489-501), Toshihiko Sasaki et al. , 750, (2009) 219-227, etc. can be applied. As a result, the normal stress, shear stress, and equivalent stress directly under the contact portion can be obtained from the results of the residual stress measurement and the surface roughness measurement. Therefore, the relationship between these stresses S and the lifetime L (repeated stress S and lifetime). If the life (relationship with L) is known, the life L can be obtained by performing the step (S40) for obtaining the life based on the relationship (step (S50)). Further, if the fatigue degree D can be obtained from the relationship between the fatigue degree and the X-ray analysis value as described above, the remaining life _NR can be obtained from the following relationship using the minor rule (step (S60)). ..

Hereinafter, an example of a method of obtaining an SN diagram showing the relationship between the stress S and the lifetime L and the relationship between the X-ray analysis value and the degree of fatigue from the experimental results will be described.

Method for determining the SN diagram showing the relationship between stress S and lifetime L:
Hereinafter, the procedure for obtaining the relationship between the equivalent stress and the lifetime will be described by focusing on the equivalent stress as one of the stress S. FIG. 8 is a graph for explaining the relationship between the SN diagram and the degree of fatigue. FIG. 9 is a graph schematically showing the relationship between the history of equivalent stress and the remaining life. The horizontal axis of FIGS. 8 and 9 indicates the number of loads corresponding to the life, and the vertical axis indicates the equivalent stress. In the SN diagram of FIG. 8 (hereinafter, also referred to as an SN curve), if the life under the rolling condition in which the equivalent stress S ₁ acts is L ₁ , the equivalent stress S ₁ gives N ₁ repeated fatigue. The degree of fatigue at the time is expressed by N ₁ / L ₁ . In the rolling contact in the rolling test, the surface roughness decreases with use, the stress concentration at the protrusion contact portion is also reduced, and at the same time, the residual stress of compression is generated. Therefore, the equivalent stress S decreases as the number of loads increases, and the degree of fatigue accumulates as the number of loads increases, as is clear from the equation (1). In order to experimentally obtain the change in equivalent stress shown by the broken line in FIG. 8 from the results of the rolling test, the surface roughness of the rolling component being subjected to the rolling test and the measurement of the X-ray diffractive ring are measured. Will be performed for each load count. Therefore, the change in stress S obtained in the actual calculation is stepped as shown by S1, S2, S3 and the like in FIG.

Next, as the material-specific SN curve equation shown in FIGS. 8 and 9, for example, the following equation (9) is used.

Here, N indicates the number of loads, S indicates the equivalent stress acting on the contact surface, S _f indicates the yield stress of the material after work hardening due to repeated stress, and A and B indicate constants. The yield stress S _f is a material constant and can be specified according to the material of the rolling component.

A rolling test was carried out on the rolling component, and the surface roughness and the X-ray diffraction ring of the rolling surface (fatigue surface) of the rolling component were measured for each predetermined number of loads. Continue the test until peeling occurs, calculating the degree of fatigue of the solid line. If this rolling test is performed a plurality of times, a plurality of life data of rolling parts can be plotted in FIG. The unknowns of Eqs. (2) and Eq. (9) are obtained so as to fit this plot with the Eq. Of the SN curve of Eq. (9). In this way, an SN diagram based on the experimental results can be obtained. Since there are a total of four unknowns in equations (2) and (9), a, A, B, and S, the SN diagram can be determined from the experimental results of four or more levels, but a more accurate SN diagram can be obtained. It is desirable to experiment at as many levels as possible to create it.

Relationship between life and number of loads:
Consider the case where a considerable stress acts on the rolling surface in the history as shown in FIG. The contact surface equivalent stresses at the points indicated by 1, 2 and 3 circled in FIG. 9 are S ₁ , S ₂ and S ₃ , respectively, and the peeling life when these equivalent stresses are repeatedly applied is defined as the peeling life. Let L ₁ , L ₂ , and L ₃ . In order to calculate the equivalent stresses S ₁ , S ₂ and S ₃ during the experiment, it is necessary to measure the roughness each time.

First, it is assumed that the rolling fatigue is _N1 times under the condition of equivalent stress S1 and _{N2 times} under the condition of equivalent stress S2. Further, it is assumed that after the number of loads (N ₁ + N ₂ ), the contact surface equivalent stress S ₃ is continuously received, and peeling occurs after N ₃ loads. At this time, the remaining life at the time of the number of loads (N ₁ + N ₂ ) is N ₃ , and the relationship between the life and the number of loads can be expressed by the following equation based on the minor rule.

When equation (10) is rearranged, it is assumed that the load is applied (N ₁ + N ₂ ) times and the fatigue progresses with the surface roughness and residual stress at the time of (N ₁ + N ₂ ) times, and the remaining life is N. ₃ is represented by the following equation (11).

Further, the generalization of the equation (11) is the following equation (12).

Relationship between X-ray analysis value and fatigue level:
In the rolling test carried out in the above-mentioned method for determining the SN diagram, the degree of fatigue is obtained for each predetermined number of loads, and X-ray analysis is also performed each time. Therefore, it is possible to create a database showing the relationship between the degree of fatigue and the X-ray analysis value which is the X-ray analysis result. The method of creating the database will be described with reference to FIG. The X-ray analysis values include stress, residual austenite amount, variation in diffraction intensity with respect to the central angle of the annular diffracted X-ray, half-value width with respect to the central angle, average value of diffraction intensity, and difference between the minimum value and the maximum value. , Integration width (product of half-value width and diffraction intensity at a certain position) and the like.

<How to build a database of fatigue and X-ray analysis values>
FIG. 5 is a flowchart for explaining a process of creating a database showing a relationship between an X-ray analysis value and a degree of fatigue of a rolling component. As shown in FIG. 5, in the process of creating a database showing the relationship between the degree of fatigue and the X-ray analysis value, a step (S110) for carrying out a rolling fatigue test is carried out. In the rolling fatigue test, the X-ray analysis step (S120) and the surface shape measuring step of the rolling component (S130) are performed when a certain number of loads have elapsed. In step (S120), the X-ray diffractometric ring is measured in the same manner as in the process for obtaining the SN diagram described above. Further, also in the step (S130), the surface roughness of the rolling surface of the rolling component is measured in the same manner as in the process of obtaining the SN diagram described above.

Next, a step (S121) for obtaining residual stress on the rolling surface of the rolling component is carried out based on the result of the X-ray analysis step (S120). In this step (S121), the residual stress is calculated using the same method as in step (S12) of FIG.

Further, in the step (S131) of estimating the oil film parameter from the data obtained in step (S20) and the operating condition data of the rolling parts such as the rotation speed, the operating temperature, the load, and the lubricating oil condition, the rolling surface The stress state calculation step (S132) and the repetitive stress calculation step (S140) in consideration of the residual stress of the raceway surface are the same as the steps (S21), step (S22), and step (S30) shown in FIG. 4, respectively. Carry out the process. If peeling has not occurred in the rolling component at the time of performing step (S140), the process returns to step (S110) again, a certain number of loads are applied to the rolling component again, and then each step described above is performed. do. Then, if peeling has occurred in the rolling parts at the time of performing step (S140), the process proceeds to step (S15) of acquiring life data (peeling time) and stopping the rolling fatigue test. Then, by repeating the above-mentioned steps (S110) to (S150) four or more times, four or more life data are acquired. After that, a step (S160) for determining an unknown number in the SN diagram is carried out so that the cyclic stress S on the rolling surface and the lifetime data N match. In this step (S160), in the process of obtaining the SN diagram, the same process as the process of obtaining the unknowns of the equations (2) and (9) can be applied.

After that, a step (S170) is carried out in which the degree of fatigue for each load number of each rolling test is calculated from the SN diagram using the minor side. As a result, it is possible to acquire data on the degree of fatigue and the X-ray analysis value for each of a plurality of loads, so the step of constructing a database showing the relationship between the degree of fatigue and the X-ray analysis value using these data ( S180) is carried out. In this way, the above database can be obtained. Then, this database can be used to estimate the degree of fatigue based on the X-ray analysis value in the step (S11) of FIG.

Here, in step (S1) in the performance evaluation method shown in FIG. 1, steps (S10), steps (S11), and steps (S13) shown in FIG. 4 are performed, and X-ray diffraction which is an X-ray analysis value is performed. The degree of fatigue can be estimated from the ring analysis results. In this case, as shown in FIG. 5, the database used for estimating the fatigue degree is created based on the results of the X-ray analysis and the surface shape measurement measured in the rolling fatigue test, so that the fatigue degree is highly accurate. Can be estimated. Further, in the performance evaluation method shown in FIG. 2, the remaining life can be estimated by using the process shown in FIG. As can be seen from the process shown in FIG. 4, since the results of X-ray analysis and surface shape measurement in the rolling fatigue test of the rolling parts are used to estimate the remaining life, the remaining life is estimated with high accuracy. can.

With the performance evaluation method described above, the performance of rolling components can be evaluated. The performance of the rolling component includes, for example, the performance of the surface-treated portion (for example, a plastically processed portion such as shot peening, a chemical conversion processing portion such as black dyeing, and a film forming portion) applied to the rolling surface of the rolling component. .. Further, as the performance of the rolling component, the quality of the lubrication state of the rolling component may be evaluated. Specifically, the viscosity and life of the lubricant used during the operation of the rolling parts can be considered as an evaluation target. For example, if there is a difference in the remaining life of two types of lubricants applied to the same rolling component at the same number of loads, the lubricant with a relatively long remaining life is superior in terms of lubrication performance. It is thought that there is.

<Action effect>
As shown in FIG. 1, the method for evaluating the performance of a rolling component according to the present disclosure includes a step (S1) for estimating the degree of fatigue of the rolling component and a step (S2) for evaluating the performance of the rolling component. In the step (S1) of estimating the fatigue level, the fatigue level of the rolling component is determined for each of the rolling components to which the rolling component is repeatedly loaded, in a plurality of states in which the number of times the repeated load is applied to the rolling component is different from each other. presume. In the step (S2) of evaluating the performance of the rolling component, as shown in FIG. 3, the rolling component is based on the relationship between the number of loads in a plurality of states and the degree of fatigue, which is evaluation data corresponding to the number of loads. Evaluate performance. The step of estimating the degree of fatigue (S1) includes a step of acquiring measurement data (S10) and a step of estimating the degree of fatigue (S11). In the step (S10) of acquiring measurement data, the fatigued portion of the rolling component is irradiated with X-rays to acquire the measurement data of the X-ray analysis value of the rolling component. In the step of estimating the fatigue degree (S11), the fatigue degree of the rolling component is estimated from the measurement data based on the relationship between the X-ray analysis value and the fatigue degree of the rolling component. The relationship between the measurement data of the X-ray analysis value and the degree of fatigue may be determined by using the measurement result of the surface shape of the rolling component and the analysis result of the X-ray diffraction as described above. Further, in the step (S2) of evaluating the performance of the rolling parts, the reference data group (FIG. 3) showing the standard performance by comparing the relational data between the number of repeated loads and the degree of fatigue for a plurality of rolling parts. After specifying the first group 10), the performance of the rolling component may be evaluated based on the degree of deviation from the reference data group in the fatigue degree data of the rolling component to be targeted.

By doing so, for example, the fatigue degree of the rolling parts in use can be estimated with high accuracy by using the relationship between the measurement data of the X-ray analysis value and the fatigue degree. Therefore, in the step (S2) of evaluating the performance of the rolling component, the transition of the fatigue degree according to the number of times of repeated loading can be estimated with high accuracy. It is possible to accurately evaluate the performance of the lubricant used during the operation of rolling components.

In the step (S2) of evaluating the performance of the rolling component, the relationship between the number of loads and the degree of fatigue includes the ratio of the amount of change in the degree of fatigue to the amount of change in the number of loads. In this case, the rate of change in the degree of fatigue with an increase in the number of loads can be used for performance evaluation.

As shown in FIG. 2, the method for evaluating the performance of rolling components according to the present disclosure includes a step of estimating the remaining life (S3) and a step of evaluating the performance of rolling components (S2). In the step (S3) of estimating the remaining life, the remaining life of the rolling parts is determined for each of the rolling parts to which the rolling parts are repeatedly loaded in a plurality of states in which the number of times of the repeated loading of the rolling parts is different from each other. presume. In the step (S2) of evaluating the performance, the performance of the rolling component is evaluated based on the relationship between the number of loads and the remaining life in a plurality of states. As shown in FIG. 4, the step of estimating the remaining life (S3) includes a step of acquiring measurement data of X-ray analysis values (S10), a step of acquiring measurement data of surface shape (S20), and residual stress. The step of deriving the data of (S12), the step of estimating the data of repeated stress (S30), the step of estimating the life (S40), the step of estimating the degree of fatigue (S11), and the estimation of the remaining life. Includes step (S60). In the step (S10) of acquiring the measurement data of the X-ray analysis value, the measurement data of the X-ray analysis value of the rolling component is acquired by irradiating the fatigued portion of the rolling component with X-rays. In the step (S20) of acquiring the surface shape measurement data, the fatigued portion of the rolling component is measured and the surface shape measurement data is acquired. In the step (S12) of deriving the residual stress data, the residual stress data in the fatigued portion of the rolling component is derived based on the measurement data of the X-ray analysis value. In the step (S30) of estimating the repeated stress data, the repeated stress data acting on the fatigued portion is estimated based on the residual stress data and the surface shape measurement data. In the step of estimating the life (S40), the life of the rolling component is estimated from the data of the repetitive stress. In the step of estimating the fatigue degree (S11), the fatigue degree of the rolling component is estimated from the measurement data of the X-ray analysis value based on the relationship between the X-ray analysis value and the fatigue degree of the rolling component. In the step of estimating the remaining life (S60), the remaining life of the rolling component is estimated based on the life of the rolling component and the degree of fatigue. In the step (S2) of evaluating the performance of rolling components, the relationship data between the number of repeated loads and the remaining life of a plurality of rolling components are compared, and a reference data group showing standard performance is specified. The performance of the rolling parts may be evaluated based on the degree of deviation from the reference data group in the data of the remaining life of the rolling parts of interest.

By doing so, the relationship between the measurement data of the X-ray analysis value and the degree of fatigue is determined by using the measurement result of the surface shape of the rolling component and the analysis result of the X-ray diffraction as described above, and further rolling. Since the measurement result of the surface shape of the rolling component and the analysis result of the X-ray diffraction are also used for estimating the life of the moving component, for example, the remaining life of the rolling component in use can be estimated with high accuracy. Therefore, in the step (S2) of evaluating the performance of the rolling component, the transition of the remaining life according to the number of times of repeated loading can be estimated with high accuracy. Therefore, the performance of the rolling component or the transition of the remaining life is based on the transition. It is possible to accurately evaluate the performance of the lubricant used during the operation of rolling components.

In the performance evaluation method of the rolling component, as shown in FIGS. 3 and 4, in the step (S30) of estimating the repeating stress data, the data used for estimating the repeating stress data is the oil film of the rolling component. Includes parameters.

In this case, by estimating the oil film parameter, it is possible to confirm whether or not the surface-origin type peeling, which is the focus of the performance evaluation method for the rolling component according to the present embodiment, can occur. Therefore, it is possible to confirm in advance whether the performance evaluation method according to the present embodiment is effective.

In the above-mentioned method for evaluating the performance of rolling parts, the relationship between the X-ray analysis value and the degree of fatigue of the rolling parts is carried out for a plurality of rolling parts samples to which a repeated load is applied, as shown in FIG. It is a relationship between a plurality of X-ray analysis values and a plurality of fatigue degrees obtained by the relationship derivation step (S110 to S180). The relationship derivation step (S110 to S180) includes a step of obtaining lifetime data and repeated stress data (S110 to S150), a step of estimating an SN diagram (S160), and a step of obtaining a degree of fatigue (S170). include. In the steps (S110 to S150) for obtaining life data and repetitive stress data, the fatigued part of the rolling component sample is irradiated with X-rays to acquire the first measurement data of the X-ray analysis value for the rolling component sample. Step (S120), the step of deriving the residual stress data in the fatigued part of the rolling component sample based on the first measurement data (S121), and the second step of measuring the fatigued part of the rolling component sample and the surface shape. The step of acquiring the measurement data (S130) and the step of estimating the data of the repetitive stress acting on the fatigue part based on the residual stress data and the second measurement data (S140) are performed for the repetitive load in the rolling component sample. By carrying out each process until the rolling component sample is damaged in a plurality of states in which the number of loads is different from each other, life data and repeated stress data, which are the number of times of repeated loading in which the rolling component sample is damaged, are obtained. In the step of estimating the SN diagram (S160), the SN diagram of the rolling component sample is estimated from the lifetime data and the repeated stress data. In the step of obtaining the degree of fatigue (S170), the degree of fatigue for each of a plurality of states in the rolling component sample is obtained by using the SN diagram.

In this case, since a highly accurate database of the relationship between the fatigue degree and the X-ray analysis value can be created, the fatigue degree can be accurately estimated using the database.

In the performance evaluation method of the rolling component, the X-ray analysis value includes data showing the variation between the central angle and the diffraction intensity of the annular diffracted X-ray diffracted in the fatigued portion of the rolling component. In this case, since the annular diffracted X-ray (X-ray diffractogram) contains more information than the information obtained at one time by the conventional X-ray diffraction method, the information obtained by one measurement causes rolling. It is possible to accurately estimate the degree of fatigue or the remaining life of a part.

In the performance evaluation method of the rolling component, the X-ray analysis value includes the data of the residual stress of the six components in the fatigued portion of the rolling component.

In the above-mentioned method for evaluating the performance of a rolling component, the X-ray analysis value includes data on the half-value width of the peak of the diffracted X-ray diffracted in the fatigued portion of the rolling component.

In the above-mentioned method for evaluating the performance of a rolling component, the X-ray analysis value includes data on the amount of retained austenite in the fatigued portion of the rolling component.

Since there is a strong phase between each of the above data and the usage conditions of the rolling component, the fatigue level or remaining life of the rolling component can be estimated with high accuracy using the above data.

In the performance evaluation method of the rolling component, the X-ray analysis value is data showing the variation between the central angle and the diffraction intensity of the annular diffracted X-ray diffracted in the fatigued portion of the rolling component, and the fatigued portion of the rolling component. It is selected from the group consisting of the data of the residual stress of the six components in the above, the data of the half-value width of the peak of the diffracted X-ray diffracted in the fatigue part of the rolling component, and the data of the amount of residual austenite in the fatigue part of the rolling component. Includes a combination of at least two data. In this case, since the fatigue degree or the remaining life is estimated by combining a plurality of data, the fatigue degree or the remaining life can be estimated with higher accuracy.

(Example)
(Ii) An example in which a rolling fatigue test using a cylindrical tester was carried out and the degree of fatigue was estimated for the rolling parts as test pieces will be described below.

<Test equipment>
FIG. 11 is a schematic view showing the configuration of a two-cylindrical tester. The two-cylindrical tester 2 shown in FIG. 11 has a drive-side rotation shaft D1 and a driven-side rotation shaft F1. The drive-side rotation shaft D1 is a member extending in the left-right direction in FIG. 11, and the motor M is connected to the left end portion in FIG. By this motor M, the drive-side rotation shaft D1 can rotate with respect to the central shaft C1 extending in the left-right direction in FIG. A drive-side test piece D2 is attached to the tip on the right side of the drive-side rotary shaft D1 in FIG. 11. The drive-side test piece D2 is fixed to the tip on the right side of the drive-side rotary shaft D1 so as to be rotatable around the central shaft C1 as the drive-side rotary shaft D1 rotates.

On the other hand, the driven side rotation shaft F1 is a member extending in the left-right direction in FIG. 11, and is rotatable with respect to the central axis C2 extending in the left-right direction in FIG. In FIG. 11, the driven side rotation shaft F1 has a tip portion on the left side and an end portion on the right side, contrary to the drive side rotation shaft D1. A driven side test piece F2 is attached to the tip on the left side of the driven side rotating shaft F1 in FIG. 11.

The central axis C1 of the drive-side rotation axis D1 and the central axis C2 of the driven-side rotation axis F1 do not match, and both have an interval in the vertical direction in FIG. Therefore, the drive-side test piece D2 fixed to the tip of the drive-side rotary shaft D1 and the driven-side test piece F2 fixed to the tip of the driven-side rotary shaft F1 have their respective outer diameter surfaces. It is arranged so as to be in contact with each other by the outer diameter surface contact portion DF in the non-rotating state. The drive-side test piece D2 and the driven-side test piece F2 arranged so as to be in contact with each other are in contact with the refueling felt pad 3 laid under them.

<Test piece>
The drive side test piece D1 and the driven side test piece F2 are made of JIS standard SUJ2 and have a cylindrical shape with an outer diameter of 40 mm and a width of 12 mm. Two types of surface finish of each test piece were prepared: super finish (surface roughness Ra about 0.01 μm) and grinding finish (surface roughness Ra about 0.5 μm). The axial radius of curvature of each test piece is ∞ (straight) for a test piece with a super-finished surface finish and 60 mm (curved surface) for a test piece with a ground-finished surface finish.

<Test method>
Before starting the test, measure the surface roughness and residual stress of each test piece, and start the test. The test conditions are shown in Table 1.

In Table 1, Pmax is the maximum contact pressure (unit: GPa) in the test piece. The test was carried out under two types of conditions, test A and test B.

Next, the residual stress measurement conditions are shown in Table 2.

The residual stress was measured by the X-ray residual stress measuring device μ-X360 manufactured by Pulstec Industrial Co., Ltd. During the rolling fatigue test, the test was interrupted at regular intervals, and the surface roughness and residual stress of each test piece were measured each time. Changes in residual stress (equivalent stress) and root mean square slope R _dq are shown in FIGS. 12 and 13. The horizontal axis of FIGS. 12 and 13 indicates the number of loads. The vertical axis of FIG. 12 shows the equivalent stress (unit: MPa). The vertical axis of FIG. 13 shows the root mean square slope R _dq .

Here, it is known that the residual stress (equivalent stress) decreases with the increase of peeling (that is, stress release occurs due to the occurrence of peeling). In the test of condition A shown in FIG. 12, stress release due to peeling occurred when the number of loads was 3 × 10 ⁵ times. Further, in the test of condition B shown in FIG. 12, stress release occurred when the number of loads was 3 × 10 ⁵ times. That is, in these tests, the peeling life is 3 × 10 ⁵ times and 3 × 10 ⁵ times, respectively.

From the above test results, the constants in equations (2) and (9) were determined as follows.
First, the unknown number a in the equation (2) is determined. Here, in line contact, the maximum contact pressure Pmax can be calculated by the following equation.

_PLmax in the formula (2) is the local maximum contact pressure generated between the roughness protrusion (for example, a rolling element) and the mating side (for example, a raceway ring) shown in FIG. 7. In this case, the other party is regarded as a plane. In the above equation (13), _PLmax can be calculated by making the following assumptions.
<Assumption>
1) The radius of curvature of the tip of the roughness protrusion shall be 0.02 mm (= R ₁ ).
2) The radius of curvature of the other party (object 2) is ∞ (= R ₂ ). (That is, assuming contact with a flat surface.)
3) The force generated per roughness protrusion is 2.41N (= F).
4) The length (= l) of the roughness protrusion in the rolling direction is almost equal to the semi-minor axis radius of the macroscopic ellipse circle. (In the case of the above-mentioned two-cylinder test, it is about 1 mm.)
Of the above assumptions, 1) and 3) are based on actual measurement values.

Using the above assumptions and the physical characteristics of steel, _PLmax = 3281 MPa. In addition, the measured R _dq (mean value of three rough surface side test pieces) immediately before the occurrence of damage was 0.1875. Substituting these into equation (2) yields a = 1.75 × 10 ⁴ .

After that, by carrying out the process shown in FIG. 5 and acquiring a plurality of lifetime data (number of loads when damage occurs) and stress Seq at that time, plots constituting the SN curve can be obtained. By fitting the plot to Eq. (9), unknown constants A and B are obtained. As a result, A = 4.336 and B = -2.381 × 10 ^-3 . These constants were determined using the convergence calculation function of the spreadsheet software. In this calculation, the yield stress S _f after work hardening of JIS standard SUJ2 was set to 2000 MPa.

With the above, the SN curve was determined. Then, the fatigue degree and the remaining life under the condition A were calculated based on the equation (11). Table 3 shows the relationship between the number of loads under condition A, the degree of fatigue, and the remaining life.

On the other hand, when the relationship between the degree of fatigue D obtained above and the variation I in the diffraction intensity with respect to the central angle of the annular diffracted X-ray was investigated, it was found that the following relationship can be approximated.

The variation I of the diffraction intensity in the above formula (14) is expressed by the following formula (15).

Here, it is considered that the relationship between the fatigue degree D and the variation I in the diffraction intensity can be approximated as in the equation (14) for the following reasons. That is, it is known from the experiments so far that the variation I of the diffraction intensity with respect to the number of loads changes as shown in FIG. Here, FIG. 10 is a graph showing the relationship between the number of loads and the variation in diffraction intensity. The horizontal axis of FIG. 10 shows the number of loads, and the vertical axis shows the variation I of the diffraction intensity. Since the fatigue degree D is a value obtained from the number of loads and the life, it can be expected that the relationship between the diffraction intensity and the fatigue degree D will be as shown in FIG. Therefore, when a parameter study was performed assuming a root function for the relationship between the degree of fatigue D and the variation I in the diffraction intensity, it was found that the relationship can be approximated by the relational expression shown in the above equation (14).

Here, by fitting the relationship between the degree of fatigue D under the above-mentioned conditions A and B and the variation I of the diffraction intensity with respect to the central angle of the diffracted X-rays into the equation (14), the constants b and c of the equation (14), It was determined that d was b = 10.07, c = 0.864, and d = 0.812, respectively.

Using the above results, the degree of fatigue D can be obtained from the measurement results of the X-ray diffractometric ring. Then, the life L of the equation (8) can be obtained from the measurement data of the surface roughness and the residual stress. As a result, the remaining life _NR can be estimated. Even with an X-ray stress measuring device that cannot measure an X-ray diffractogram (for example, a device that detects X-rays with a one-dimensional PSPC, scintillation counter, etc.), if the sample is rotated and the diffracted X-rays are measured from multiple directions, Since the residual stress of the three axes can be measured, the life L can be obtained. Further, if the relationship between the analysis value obtained by the X-ray stress measuring device that cannot measure the X-ray diffractometric ring and the degree of fatigue D is known, the present embodiment can also use the X-ray stress measuring device that cannot measure the X-ray diffractometric ring. It is possible to estimate the remaining life of the product.

As described above, in the performance evaluation method according to the present embodiment, the change (trend) with respect to the degree of fatigue of the rolling component in use and the number of loads of the remaining life is analyzed by the measurement result of the surface shape of the rolling component and the X-ray analysis. Obtained from the result. Then, the performance of rolling parts and lubricants can be evaluated from this trend.

The embodiments and examples disclosed this time should be considered to be exemplary and not restrictive in all respects. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

2 Two-cylindrical tester, 3 Felt pad for refueling, 10 First group, 11, 12 data, 21 Irradiation unit, 22 Detector, 22A detection unit, 23 Control calculation unit, 24 Display unit, 30 Convex part, 31 Arrow ..

Claims (9)

A step of estimating the fatigue level of the rolling component in a plurality of states in which the number of times the repeated load is applied to the rolling component is different from each other for the rolling component to which the rolling component is repeatedly loaded.
A step of evaluating the performance of the rolling component based on the relationship between the number of loads in the plurality of states and the degree of fatigue corresponding to the number of loads is provided.
The step of estimating the degree of fatigue is
A step of acquiring measurement data of X-ray analysis values for the rolling component by irradiating the fatigued portion of the rolling component with X-rays.
Including a step of estimating the fatigue degree of the rolling component from the measurement data based on the relationship between the X-ray analysis value and the fatigue degree of the rolling component.
In the step of evaluating the performance of the rolling component, a reference data group showing standard performance is specified from the relationship data between the number of loads and the degree of fatigue of the plurality of rolling components, and then the target is targeted. The performance of the rolling component is evaluated by the degree of separation from the reference data group in the fatigue degree data of the rolling component .
When the fatigue level of the rolling component to be targeted exceeds the fatigue level of the reference data group at the same load frequency, it is assumed that the fatigue of the rolling component to be targeted is progressing quickly. A method for evaluating the performance of a rolling component, wherein when the fatigue level of the rolling component to be targeted is lower than the fatigue level of the reference data group, the fatigue of the rolling component to be targeted is considered to be slow. .. For a rolling component to which a repetitive load is applied, a step of estimating the remaining life of the rolling component in a plurality of states in which the number of times the repetitive load is applied to the rolling component is different from each other, and a step of estimating the remaining life of the rolling component.
A step of evaluating the performance of the rolling component based on the relationship between the number of loads and the remaining life in the plurality of states is provided.
The step of estimating the remaining life is
A step of acquiring measurement data of X-ray analysis values for the rolling component by irradiating the fatigued portion of the rolling component with X-rays.
A step of measuring the fatigued portion of the rolling component and acquiring measurement data of the surface shape,
A step of deriving data on residual stress in the fatigued portion of the rolling component based on the measured data of the X-ray analysis value, and a step of deriving the data.
A step of estimating the data of the repetitive stress acting on the fatigue portion based on the data of the residual stress and the measurement data of the surface shape, and
The step of estimating the life of the rolling component from the data of the repeating stress, and
A step of estimating the fatigue degree of the rolling component from the measurement data of the X-ray analysis value based on the relationship between the X-ray analysis value and the fatigue degree of the rolling component.
Including a step of estimating the remaining life of the rolling component based on the life of the rolling component and the degree of fatigue.
In the step of evaluating the performance of the rolling component, a reference data group showing standard performance is specified from the relationship data between the number of loads and the remaining life of the plurality of rolling components, and then the target is targeted. The degree of separation of the rolling component from the reference data group in the remaining life data is evaluated.
A method for evaluating the performance of a rolling component, which estimates the transition of the remaining life of the rolling component to be targeted according to the number of loads and evaluates the performance of the rolling component to be targeted . The performance evaluation method for a rolling component according to claim 2, wherein in the step of estimating the repeating stress data, the data used for estimating the repeating stress data includes an oil film parameter of the rolling component. The relationship between the X-ray analysis value and the degree of fatigue of the rolling component is obtained by a plurality of the X-ray analysis performed by the relationship derivation step performed on the plurality of rolling component samples to which the repeated load is applied. It is the relationship between the value and the plurality of said fatigue degrees,
The relationship derivation step is
By irradiating the fatigued part of the rolling component sample with X-rays, the step of acquiring the first measurement data of the X-ray analysis value for the rolling component sample and the rolling component based on the first measurement data. A step of deriving the residual stress data in the fatigued portion of the sample, a step of measuring the fatigued portion of the rolling component sample to obtain a second measurement data of the surface shape, the data of the residual stress, and the above. The step of estimating the data of the repetitive stress acting on the fatigued portion based on the second measurement data is performed by the rolling component sample in a plurality of states in which the number of times the repeated load is applied to the rolling component sample is different from each other. A step of obtaining life data, which is the number of times of repeated load in which the rolling component sample is damaged, and data of the repeated stress, by carrying out each process until the rolling component sample is damaged.
A step of estimating the SN diagram of the rolling component sample from the lifetime data and the repeating stress data, and
The performance evaluation method for a rolling component according to any one of claims 1 to 3, comprising a step of obtaining a degree of fatigue for each of the plurality of states in the rolling component sample using the SN diagram. .. The X-ray analysis value is according to any one of claims 1 to 4, which includes data indicating a variation between the central angle and the diffraction intensity of the annular diffracted X-ray diffracted in the fatigued portion of the rolling component. The method for evaluating the performance of the rolling parts described. The performance evaluation method for a rolling component according to any one of claims 1 to 4, wherein the X-ray analysis value includes data on residual stress of six components in the fatigued portion of the rolling component. The rolling component according to any one of claims 1 to 4, wherein the X-ray analysis value includes data of a half-value width of a peak of diffracted X-rays diffracted in the fatigued portion of the rolling component. Performance evaluation method. The method for evaluating the performance of a rolling component according to any one of claims 1 to 4, wherein the X-ray analysis value includes data on the amount of retained austenite in the fatigued portion of the rolling component. The X-ray analysis value is data showing the variation between the central angle and the diffraction intensity of the annular diffracted X-ray diffracted in the fatigued portion of the rolling component, and the residual of 6 components in the fatigued portion of the rolling component. Selected from the group consisting of stress data, half-value width data of the peak of the diffracted X-ray diffracted in the fatigued portion of the rolling component, and data on the amount of retained austenite in the fatigued portion of the rolling component. The method for evaluating the performance of a rolling component according to any one of claims 1 to 4, which comprises a combination of at least two data.

Images