JP4584085B2 - Degradation evaluation method for rolling bearings - Google Patents

Description

  The present invention relates to a rolling bearing deterioration evaluation method for determining the remaining life of a rolling bearing in an actual machine.

Conventionally, the rated fatigue life L _h of a ball bearing among rolling bearings is expressed by the following formula (1).

L _h = (10 ⁶ / 60n) · (C / P) ³ (1)
(N: rotational speed (rpm), C: basic dynamic load rating, P: bearing load)
Based on the experimental results, there is known a formula for calculating the remaining life from the recognition of the bearing abnormality to the life (seizure or breakage) by the following formula (2) (see Non-Patent Document 1).

L _dh = (0.032 × 10 ⁶ / 60n) · (C / P) ^3.37 (2)
Noriaki Inoue “Practice answering on-site questions: Practical equipment diagnosis by vibration method” published by Japan Plant Maintenance Association

  However, the above formula (1) is determined assuming that 90% of bearings do not reach the end of their service life from the viewpoint of the safety side, and therefore the deterioration evaluation of the rolling bearing using the above formula (1). There is a problem that the method lacks practicality.

  Further, the present inventors applied the above formula (2) to the test conditions and compared the remaining life of the bearing after recognizing the abnormality with the test results. As a result, a comparison result as shown in Table 1 below was obtained. It has been found that the rolling bearing deterioration evaluation method using (2) cannot sufficiently predict the remaining life of the bearing after the abnormality is recognized.

そこで、本発明に先立ち、転がり軸受の余寿命を十分に予測することができる転がり軸受の劣化評価方法を提供することを目的として、次のような未公開の発明、つまり、試験用転がり軸受に定量フェログラフィ法を適用することによって求めたIs値から転がり軸受劣化評価曲線を作成する工程と、実機転がり軸受の異常発生後の任意の時点で定量フェログラフィ法を適用し、Is値を求める工程と、該求めたIs値を前記転がり軸受劣化評価曲線上に展開し、当該実機転がり軸受の余寿命を求める工程とからなることを特徴とする転がり軸受の劣化評価方法に係る発明がなされた。

Therefore, prior to the present invention, for the purpose of providing a rolling bearing deterioration evaluation method capable of sufficiently predicting the remaining life of a rolling bearing, the following unpublished invention, that is, a test rolling bearing, is provided. A process for creating a rolling bearing deterioration evaluation curve from the Is value obtained by applying the quantitative ferrography method, and a process for obtaining the Is value by applying the quantitative ferrography method at any time after the occurrence of an abnormality in the actual rolling bearing. And a process of developing the calculated Is value on the rolling bearing deterioration evaluation curve and determining the remaining life of the actual rolling bearing.

  This prerequisite invention has been made on the basis of the following knowledge.

  2. Description of the Related Art Conventionally, as a deterioration evaluation method for rolling bearings, a deterioration evaluation method using a ferrography method, which is a central technology of a lubricant diagnosis method, is known.

  In the ferrography method, wear particles contained in a lubricating oil are arranged and separated in order of magnitude by a strong magnetic field having a magnetic gradient.

  In the quantitative ferrography method, the separated wear particles are irradiated with light, and a large wear particle concentration PL of, for example, 5 μm or more and a small wear particle concentration PS of, for example, about 1-2 μm are measured according to the amount of transmitted light. The abnormal wear index Is is obtained by the following formula (3) from the wear abnormality degree PL-PS and the total wear amount WPC (= PL + PS), and the deterioration state of the rolling bearing is diagnosed from this Is value.

Is = (PL−PS) × (PL + PS) = PL ² −PS ² (3)
Focusing on this Is value, we examined the relationship between the Is value and the remaining life of the rolling bearing. From a lot of past diagnostic data and test data from a new deterioration acceleration test, the Is value is closely related to the remaining life. When the Is value increases to a predetermined value, the rolling bearing starts to deteriorate, that is, the rolling bearing becomes abnormal, and when the Is value further increases to a predetermined value, the rolling bearing seizes or breaks. It has been found. Furthermore, it was found that the change curve of the Is value from the rolling bearing deterioration start point (abnormal point of occurrence) to the point of seizure or breakage (life point) can be represented by an exponential function.

  The premise invention was made based on the above knowledge.

  According to the base invention, the rolling bearing deterioration evaluation curve created from the Is value obtained by the quantitative ferrography method almost accurately represents the change in the Is value from the time when the abnormality occurred to the life of the rolling bearing. By developing the Is value obtained by applying the quantitative ferrography method on the rolling bearing deterioration evaluation curve, the remaining life of the actual rolling bearing can be sufficiently predicted.

  However, the rolling bearing deterioration evaluation method using the ferrography method has a problem that it cannot be used for a shield type rolling bearing that cannot sample the lubricating oil during operation of the actual machine.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the premise invention and to provide a deterioration evaluation method for a rolling bearing capable of obtaining a remaining life even for a shield type rolling bearing.

  Under the above object, the present inventors have represented the correlation between the Is value obtained from the test results and the vibration acceleration with a graph, and as shown in FIG. 1, there is a sufficient correlation between the Is value and the vibration acceleration. I found that there was a relationship.

  Based on the correlation between the Is value and vibration acceleration, it was concluded that the remaining life can be estimated from the vibration acceleration of shield type rolling bearings.

  The deterioration evaluation method for a rolling bearing according to the present invention includes a first step for obtaining a rolling bearing deterioration curve with an unweighted Is value and a correlation curve between the Is value and vibration acceleration, and the rolling bearing deterioration curve with respect to the rolling bearing deterioration curve. By applying the relationship between the Is value of the correlation curve and the vibration acceleration, the second step of determining the rolling bearing deterioration curve based on the vibration acceleration, and measuring the vibration acceleration of the actual rolling bearing at at least two measurement points, By developing the vibration acceleration measured at each measurement time point on the rolling bearing deterioration curve based on the vibration acceleration, the elapsed time indicating the vibrationless value indicating the vibration acceleration value is obtained, and the obtained weightlessness is obtained. And a third step of determining the remaining life of the actual rolling bearing based on the elapsed time and the measurement time points. Here, “no-quantity” means that the unit axis (time axis) from the initial state to the end (limit) state is a dimensionless unit of “1” for convenience in order to compare all bearing deterioration phenomena equally. This is expressed as a quantity.

  According to the present invention, it is possible to accurately and quantitatively predict a bearing state using vibration acceleration as information.

  The rolling bearing deterioration evaluation method according to the present embodiment includes a first step for obtaining a rolling bearing deterioration curve in which the Is value is reduced and a correlation curve between the Is value and vibration acceleration, and correlation with the rolling bearing deterioration curve. By applying the relationship between the Is value of the curve and the vibration acceleration, the second step of determining the rolling bearing deterioration curve based on the vibration acceleration, and measuring the vibration acceleration of the actual rolling bearing at at least two measurement points, By developing the vibration acceleration measured at the time of measurement on the rolling bearing deterioration curve based on the vibration acceleration, the elapsed time indicating the vibrationless value indicating each vibration acceleration value is obtained, and the calculated flowlessness is obtained. And a third step of obtaining the remaining life of the actual rolling bearing based on the time and each measurement time point.

FIG. 2 shows an example of a rolling bearing deterioration curve (including a straight line) that has been converted into an elementless quantity based on the Is value in the first step. In FIG. 2, the elapsed time “0” corresponds to a deterioration start point (abnormal point in time) at which the Is value becomes a predetermined value, for example, 10 ¹ , and the elapsed time “1” Corresponds to the control life point of 10 ³ . The correlation curve between the Is value and the vibration acceleration is shown in FIG. 1 as described above.

  In the second step, when the rolling bearing deterioration curve based on the vibration acceleration is obtained from FIGS. 1 and 2, it is as shown in FIG.

FIG. 4 shows measurement data of the actual rolling bearing in the third step. In this measurement data, the measurement time points are τ ₁ and τ ₂ , and the vibration accelerations measured at the respective measurement time points τ ₁ and τ ₂ are G ₁ and G ₂ . The measured vibration accelerations G ₁ and G ₂ are developed on the master curve shown in FIG. 5 (rolling bearing deterioration curve based on the vibration acceleration), and an unquantified course indicating the vibration acceleration values G ₁ and G ₂ is obtained. Times t ₁ and t ₂ are obtained. The master curve shown in FIG. 5 is an image of the rolling bearing deterioration curve shown in FIG. 3, and is the same curve as FIG. Then, the remaining life τ ₃ of the actual rolling bearing is obtained by the following formula (4).

(τ ₂ −τ ₁ ) / (t ₂ −t ₁ ) = (τ ₃ −τ ₂ ) / (1−t ₂ )
τ ₃ = τ ₂ + (τ ₂ −τ ₁ ) (1-t ₂ ) / (t ₂ −t ₁ ) (4)
As described above, according to the present embodiment, it is possible to accurately and quantitatively predict the bearing state using vibration acceleration as information.

It is a correlation curve figure of Is value and vibration acceleration. It is a rolling bearing deterioration curve figure by Is value. It is a rolling bearing deterioration curve figure on the basis of vibration acceleration. It is an actual machine data diagram. It is a master curve figure (rolling bearing deterioration curve figure on the basis of vibration acceleration).

Claims (1)

A first step for obtaining a rolling bearing deterioration curve obtained by the Is value and a correlation curve between the Is value and the vibration acceleration;
Applying a relationship between the Is value of the correlation curve and the vibration acceleration to the rolling bearing deterioration curve to obtain a rolling bearing deterioration curve based on the vibration acceleration;
The vibration acceleration of the actual rolling bearing is measured at at least two measurement time points, and the vibration acceleration values measured at each measurement time point are developed on the rolling bearing deterioration curve based on the vibration acceleration. And a third step of obtaining the remaining life of the actual rolling bearing based on the obtained elapsed time and the respective measurement time points. Degradation evaluation method for rolling bearings.

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