JP2015215317A - Remaining life prediction method of rolling bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which can further accurately predict a remaining life of a bearing without causing a variation.SOLUTION: An X-ray fatigue degree with respect to a fatigue progression degree is digitized in advance by measuring a reduction amount of a half value width of a martensite structure of a material, and a reduction amount of a remaining austenite amount with respect to a bearing constituting part by using an X-ray diffraction device, at least one of the followings (A) to (C) is measured after an operation for a prescribed time., and a remaining life of the bearing is predicted by making the X-ray fatigue degree associate with one of the followings. (A) A load of rolling during an operation. (B) At least one of a size, quantity and weight of a foreign matter in a lubricant. (C) At least one of a size and an occupation are of an impression which is formed on a raceway surface or a rolling surface.

Description

  The present invention relates to a method for predicting the remaining life of a rolling bearing.

  In a rolling bearing, a peeling phenomenon occurs in which the raceway surface is peeled off after use for a certain period. In general, there are two types of delamination: internal-origin type delamination starting from non-metallic inclusions in steel and surface-origin type delamination starting from indentations formed by the inclusion of foreign matter mixed in the lubricant. Broadly divided. In recent years, with the high cleaning of bearing materials, most of the commercial products are surface-origin type peeling. This separation phenomenon is unavoidable for rolling bearings.If separation occurs on the raceway surface or rolling surface, vibrations may occur during use, and in the worst case damage to manufactured products may occur. It may lead to serious damage to incidental facilities.

  For this reason, methods for predicting the remaining life of rolling bearings have been proposed. In the method of predicting the remaining life, it is considered effective to extract a parameter that changes during use of the rolling bearing and detect the progress of fatigue based on the parameter. One of the parameters that change during use is considered. The degree of fatigue (material life) of the bearing material is given as an example. With respect to this material life, Patent Document 1 prepares a fatigue index (X-ray fatigue) by measuring the reduction in the half-value width of the martensite structure and the reduction in the amount of retained austenite by the X-ray diffraction method. Based on actual measured values, a method for evaluating the degree of fatigue progression from the X-ray fatigue degree is proposed.

  However, in Non-Patent Document 1, it is pointed out that the prediction method described in Patent Document 1 shows that the X-ray fatigue degree and the fatigue progression degree have a good correlation, but the variation becomes large. One of the causes is the area of X-ray irradiation (φ several μm). As described above, the surface-origin-type delamination that has occurred in most rolling bearings in recent years is based on the prediction method described in Patent Document 1, and since the irradiation area is wide, the change in the material structure other than the indentation is also an X-ray fatigue degree. Furthermore, since the indentation state (number, size, etc.) differs depending on the use environment, the X-ray fatigue level is also expected to be different.

  As one of the countermeasures, Non-Patent Document 2 clarifies that variation can be suppressed when the X-ray irradiation area is set to a minute region in order to capture the change in the material structure near the indentation. However, this method requires a long measurement time.

Japanese Patent Publication No. 63-34423

NSK Bearing Journal, 1982, No. 644, p. 1) Material Science Forum Vols. 706-709, p. 1679

  The present invention has been made in view of such circumstances, and has improved the remaining life prediction method of a rolling bearing using the X-ray fatigue degree, and can predict the remaining life of the bearing more accurately without variation. It aims to provide a method.

In order to solve the above problems, the present invention provides a method for predicting the remaining life of a rolling bearing shown below.
(1) A method for predicting the remaining life of a rolling bearing in operation,
For bearing components, the amount of reduction in half-value width of the martensite structure of the material and the amount of reduction in retained austenite are measured using an X-ray diffractometer, and the degree of X-ray fatigue relative to the degree of fatigue progress is quantified. A method for predicting a remaining life of a rolling bearing, comprising: measuring at least one of the following (A) to (C) after operation for a predetermined time and predicting a remaining life in association with the X-ray fatigue level.
(A) Load applied to the rolling bearing in operation (B) At least one of the size, amount and hardness of foreign matter in the lubricant (C) Size of the indentation formed on the raceway surface or rolling surface and occupation of the indentation At least one of the areas (2) (A) to (C) are measured for at least one of the raceway surface of the outer ring, the raceway surface of the inner ring, and the rolling surface of the rolling element, and the fatigue level is the highest among the measured values. The remaining life prediction method for a rolling bearing according to (1), wherein the remaining life is predicted from a high value.
(3) The above-described (1) or (1), wherein the measurement is performed by mounting the bearing to be measured on a fixed X-ray diffractometer or by measuring the bearing to be measured on-site using a mobile X-ray diffractometer. 2) A method for predicting the remaining life of the rolling bearing as described.

  According to the present invention, the remaining life of the bearing can be predicted more accurately without variation.

It is a graph which shows the relationship between the fatigue progression degree and the X-ray fatigue degree in condition 1, condition 12 and condition 13. It is a graph which shows the relationship between the fatigue progress degree in condition 2, condition 3 and condition 12, and X-ray fatigue degree. It is a graph which shows the relationship between the fatigue progressing degree and the X-ray fatigue degree in the conditions 6, 9 and 12. It is a graph which shows the relationship between the fatigue progression degree and the X-ray fatigue degree in the conditions 10, 11 and 12. It is a figure for demonstrating the relationship of the X-ray fatigue degree at the time of peeling by the difference in a foreign material state. It is a graph which shows the relationship between the fatigue progression degree and a X-ray fatigue degree for every foreign material state. It is a graph which shows the relationship between the average size of a foreign material, and the average size of an indentation. It is a graph which shows the relationship between content of a foreign material, and the ratio of the indentation which occupies for a track surface.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

In the method for predicting the remaining life of the present invention, first, with respect to the bearing to be measured, before the rotation and after a predetermined time has elapsed, the half-value width and the amount of retained austenite of the martensite of the measurement unit are measured using an X-ray diffractometer. Then, the amount of decrease in martensite half-value (δa) and the amount of decrease in retained austenite (δb) from before rotation are obtained, and the degree of X-ray fatigue is calculated from the following equation (1).
X-ray fatigue level = (δa) + C × (δb) (1)
(In the formula, C is a material coefficient depending on the amount of retained austenite.)

  In addition, as a measurement part, any of an inner ring raceway surface, an outer ring raceway surface, and a rolling surface may be sufficient.

Then, in the bearing to be measured, a lubricant mixed with foreign matters having different sizes, contents in the lubricant, or hardness is enclosed, rotated under different loads, and the size, content or hardness of the foreign matters, or the load. Obtain the correlation of the degree of fatigue progression due to the difference in. The degree of fatigue progression is expressed by the following equation (2) from the time until the measured bearing is rotated and the above X-ray diffraction measurement is carried out (measurement execution time) and the time until peeling (peeling time). Can be sought.
Fatigue progress = (measurement time) / (peeling time) × 100

  Below, using a rolling bearing “HR32017XJ” as a bearing to be measured, encapsulating a lubricant mixed with foreign matters having different hardness, content and average size as shown in Table 1, and rotating with the indicated load, The relationship between the degree of X-ray fatigue and the degree of fatigue progress was investigated. The results are shown in Table 1.

  FIG. 1 is a graph showing the relationship between the degree of fatigue progression and the degree of X-ray fatigue under conditions 1, 12 and 13, and a good correlation is obtained between the degree of fatigue progression and the degree of X-ray fatigue under each condition. ing. Moreover, in the conditions 1, 12 and 13, the hardness and content of the foreign matter are the same, the average size is almost the same, and the comparison results are substantially different only in the load. Therefore, it can be seen from the figure that the greater the load, the greater the degree of X-ray fatigue during peeling.

  FIG. 2 is a graph showing the relationship between the degree of fatigue progression and the degree of X-ray fatigue under conditions 2, 3 and 12, and a good correlation is obtained between the degree of fatigue progression and the degree of X-ray fatigue under each condition. ing. Moreover, in the conditions 2, 3 and 12, since the content of foreign matter is the same, the average size is almost the same, and the load is the same, it is also a comparison result that is substantially different only in the hardness of the foreign matter. Accordingly, it can be seen from the figure that the harder the foreign matter, the greater the degree of X-ray fatigue during peeling.

  FIG. 3 is a graph showing the relationship between the degree of fatigue progress and the degree of X-ray fatigue under conditions 6, 9 and 12, and there is a good correlation between the degree of fatigue progression and the degree of X-ray fatigue under each condition. Yes. Moreover, in the conditions 6, 9 and 12, since the hardness of the foreign matter is the same, the average size is almost the same, and the load is the same, it is a comparison result that is substantially different only in the content of the foreign matter. Therefore, it can be seen from the figure that as the content of foreign matter increases, the degree of X-ray fatigue during peeling increases.

  FIG. 4 is a graph showing the relationship between the degree of fatigue progression and the degree of X-ray fatigue under conditions 10, 11 and 12, and a good correlation is obtained between the degree of fatigue progression and the degree of X-ray fatigue under each condition. ing. Moreover, since the load is the same and the hardness and content of a foreign material are the same in the conditions 10, 11 and 12, it is also a comparison result in which only the average size of the foreign material is different. Therefore, it can be seen from the figure that as the size of the foreign matter increases, the degree of X-ray fatigue at the time of peeling increases.

  Thus, there is a high correlation between the load during operation and the hardness, content and size of foreign matter in the lubricant, and the degree of fatigue of the bearing. It can be seen that the harder the foreign matter, the greater the content of foreign matter, and the larger the foreign matter, the greater the degree of fatigue of the bearing and the shorter the remaining life.

  In addition, the average size and content of foreign matters were measured for the lubricant collected from the bearings during periodic inspections. Incidentally, (P / C) of the bearing is 0.5. And based on said result, the X-ray fatigue degree at the time of peeling was estimated from the average size and content of a foreign material, and it classified into the X-ray fatigue degree for every foreign material state (average size and content). The results are shown in FIG. 5, and it can be seen that the more severe the foreign material state, that is, the higher the average size and content of the foreign material, the higher the degree of X-ray fatigue during peeling.

  Based on this result, when the relationship between the X-ray fatigue degree of each foreign substance state and the fatigue progress degree is obtained, as shown in FIG. 6, the X-ray fatigue degree and the fatigue progress degree for each foreign substance state are linearly related. You can see that Therefore, the remaining life of the bearing to be measured can be predicted from the foreign material state (here, the size and content of the foreign material).

  As shown in FIG. 1, since the X-ray fatigue level at the time of peeling varies depending on the load, it is necessary to obtain the relationship between the fatigue level and the foreign material state shown in FIG. 5 for each load.

  In addition, the state of foreign matter in the lubricant affects the size and amount of indentations formed on the raceway surface and rolling surface of the bearing. For example, the relationship between the size of the foreign matter and the size of the indentation formed on the raceway surface is shown in FIG. 7. The content of the foreign matter and the area occupied by the indentation formed on the raceway surface (the indentation occupying the measurement location) are shown in FIG. FIG. 8 shows the result of examining the relationship with the area. In all cases, the (P / C) of the bearing is 0.5.

  As shown in the figure, since there is a high correlation between the size of the foreign matter and the size of the indentation, and the content of the foreign matter and the occupied area of the indentation, the size and occupied area of the indentation are set in place of the above-described foreign matter state. The remaining life of the bearing to be measured can also be predicted by using it.

As described above, since there is a good correlation between the following (A) to (C) and the degree of X-ray fatigue, at least one of the following (A) to (C), all to increase the accuracy Can be used to predict the remaining life of the bearing to be measured.
(A) Load applied to the rolling bearing in operation (B) At least one of the size, amount and hardness of foreign matter in the lubricant (C) Size of the indentation formed on the raceway surface or rolling surface and occupation of the indentation At least one of the areas

  Moreover, the remaining life of the bearing to be measured can be predicted with a higher degree of safety by using the value having the highest degree of fatigue among the measured values of (A) to (C).

  The X-ray diffractometer used for measuring the X-ray fatigue degree may be fixed or movable. When using a fixed X-ray diffractometer, it is necessary to bring the bearing to be measured into the installation facility of the X-ray diffractometer. On the other hand, in the movable X-ray diffractometer, the X-ray fatigue degree of the bearing to be measured can be measured non-destructively by bringing it into the field at the time of periodic inspection. This movable X-ray diffractometer is a small and lightweight X-ray diffractometer that can suppress the X-ray output to a low voltage and low current and does not require a goniometer mechanism. A portable X-ray residual stress device or the like can be used.

Claims (3)

A method for predicting the remaining life of a rolling bearing in operation,
For bearing components, the amount of reduction in half-value width of the martensite structure of the material and the amount of reduction in retained austenite are measured using an X-ray diffractometer, and the degree of X-ray fatigue relative to the degree of fatigue progress is quantified. A method for predicting a remaining life of a rolling bearing, comprising: measuring at least one of the following (A) to (C) after operation for a predetermined time and predicting a remaining life in association with the X-ray fatigue level.
(A) Load applied to the rolling bearing in operation (B) At least one of the size, amount and hardness of foreign matter in the lubricant (C) Size of the indentation formed on the raceway surface or rolling surface and occupation of the indentation At least one of the areas   Measure (A) to (C) for at least one of the raceway surface of the outer ring, the raceway surface of the inner ring, and the rolling surface of the rolling element, and predict the remaining life from the value with the highest fatigue level among the measured values. The method for predicting the remaining life of a rolling bearing according to claim 1.   The rolling bearing according to claim 1 or 2, wherein the measurement is performed by mounting the bearing to be measured on a fixed X-ray diffractometer, or the bearing to be measured is measured on-site using a mobile X-ray diffractometer. For predicting the remaining life of

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