Bearing diagnostic device and bearing diagnostic method

Abstract

To provide a bearing diagnostic device and bearing diagnostic method capable of predicting the remaining life of a bearing with high accuracy. [Solution] Based on the signal intensity of the third harmonic component of the damage frequency caused by damage occurring on the bearing raceway surface, the first time point at which the damage progressed to a first degree on the bearing raceway surface is estimated. Based on the signal intensity of the second harmonic component of the damage frequency, the second time point at which the damage progressed to a second degree on the bearing raceway surface is estimated. Based on the first and second time points, the remaining life of the bearing is predicted.

Description

Technical Field

[0001] The present invention relates to a bearing diagnosis device and a bearing diagnosis method.

Background Art

[0002] Generally, the bearing life is defined as the period until a rolling bearing becomes unusable due to flaky peeling on the raceway surface. Since it is not easy to replace bearings used in main shaft bearings, generator bearings, etc. of large mechanical equipment such as wind power generation devices, it is necessary to estimate the remaining life through regular inspections and determine the replacement time in advance. Patent Document 1 describes a method and configuration for theoretically calculating the relationship between the operating time and the peeling size using various parameters and predicting the remaining life of a bearing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above prior art, assumed values or estimated values may be used as various parameters when predicting the remaining life of a bearing. Therefore, depending on the accuracy of the assumed values or estimated values used as various parameters, the prediction accuracy of the remaining life of the bearing may decrease.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a bearing diagnosis device and a bearing diagnosis method capable of accurately predicting the remaining life of a bearing.

Means for Solving the Problems

[0006] To achieve the above objective, a bearing diagnostic device according to one aspect of the present invention is a bearing diagnostic device for diagnosing the condition of a bearing installed in mechanical equipment, comprising: an envelope processing unit that performs envelope processing on a vibration signal acquired by a vibration sensor; a frequency analysis processing unit that performs fast Fourier transform processing on the time-domain signal after envelope processing and converts it into a frequency-domain signal including signal intensity for each frequency; and a determination processing unit that estimates a first time when the damage on the raceway surface of the bearing progresses to a first degree of damage based on the signal intensity of the third harmonic component of the damage frequency caused by damage occurring on the raceway surface of the bearing, and estimates a second time when the damage on the raceway surface of the bearing progresses to a second degree of damage based on the signal intensity of the second harmonic component of the damage frequency, and predicts the remaining life of the bearing based on the first time and the second time.

[0007] In a preferred embodiment of the bearing diagnostic device, the determination processing unit preferably determines a relationship between the period from the first time to the second time and the degree of damage that progressed during that period, and estimates the time at which the estimated value of the degree of damage estimated by this relationship becomes a predetermined upper limit of the degree of damage as the remaining life of the bearing.

[0008] To achieve the above objective, a bearing diagnostic device according to one aspect of the present invention is a bearing diagnostic device for diagnosing the condition of a bearing installed in mechanical equipment, comprising: a storage unit that stores in advance a first time point at which damage progresses to a first degree on the raceway surface of the bearing, a second time point at which damage progresses to a second degree on the raceway surface of the bearing, and a relational expression for the degree of damage progressing during the period from the first time point to the second time point; an envelope processing unit that performs envelope processing on a vibration signal acquired by a vibration sensor; a frequency analysis processing unit that performs fast Fourier transform processing on the time-domain signal after envelope processing and converts it into a frequency-domain signal including signal intensity for each frequency; and an estimation of the first time point or the second time point based on the signal intensity of the second or third harmonic component of the damage frequency caused by damage occurring on the raceway surface of the bearing, and substituting these into the relational expression, the device estimates the time point at which the estimated value of the degree of damage estimated by the relational expression becomes a predetermined upper limit of the degree of damage as the remaining life of the bearing.

[0009] In a preferred embodiment of the bearing diagnostic device, the first degree of damage indicates a state in which the size of the delamination in the rotational direction of the damage occurring on the raceway surface of the bearing has progressed to a pitch of 0.33 of the distance between adjacent rolling elements, and the second degree of damage indicates a state in which the size of the delamination has progressed to a pitch of 0.5 of the distance between adjacent rolling elements.

[0010] A bearing diagnostic method according to one aspect of the present invention is a bearing diagnostic method for diagnosing the condition of a bearing installed in machinery, comprising: an envelope processing step of performing envelope processing on a vibration signal acquired by a vibration sensor; a frequency analysis processing step of performing a fast Fourier transform on the time-domain signal after envelope processing to convert it into a frequency-domain signal including signal intensity for each frequency; and a determination processing step of estimating a first time point at which the damage on the raceway surface of the bearing progressed to a first degree of damage and a second time point at which the damage on the raceway surface of the bearing progressed to a second degree of damage, based on the signal intensity of the second and third harmonic components of the damage frequency caused by damage occurring on the raceway surface of the bearing, and predicting the remaining life of the bearing based on the first and second time points.

[0011] In a preferred embodiment of the bearing diagnostic method, it is preferable that in the determination processing step, a relationship formula is obtained between the period from the first time to the second time and the degree of damage that progressed during the period from the first time to the second time, and the time at which the estimated value of the degree of damage estimated by this relationship formula becomes a predetermined upper limit of the degree of damage is estimated as the remaining life of the bearing.

[0012] A bearing diagnostic method according to one aspect of the present invention is a bearing diagnostic method for diagnosing the condition of a bearing installed in machinery, comprising: an envelope processing step that stores in advance a first time point at which damage progresses to a first degree on the raceway surface of the bearing, a second time point at which damage progresses to a second degree on the raceway surface of the bearing, and a relational expression for the degree of damage progressing during the period from the first time point to the second time point, and performs envelope processing on a vibration signal acquired by a vibration sensor; a frequency analysis processing step that performs fast Fourier transform processing on the time-domain signal after envelope processing and converts it into a frequency-domain signal including signal intensity for each frequency; and a determination processing step that estimates the first time point or the second time point based on the signal intensity of the second or third harmonic component of the damage frequency caused by damage occurring on the raceway surface of the bearing, substitutes it into the relational expression, and estimates the time point at which the estimated value of the degree of damage estimated by the relational expression becomes a predetermined upper limit of the degree of damage as the remaining life of the bearing.

[0013] In a preferred embodiment of the bearing diagnostic method, the first degree of damage is preferably characterized by a state in which the size of the delamination in the rotational direction of the damage occurring on the raceway surface of the bearing has progressed to a pitch of 0.33 of the distance between adjacent rolling elements, and the second degree of damage is preferably characterized by a state in which the size of the delamination has progressed to a pitch of 0.5 of the distance between adjacent rolling elements. [Effects of the Invention]

[0014] According to the present invention, a bearing diagnostic device and bearing diagnostic method capable of predicting the remaining life of a bearing with high accuracy can be obtained. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a diagram showing an example of the schematic configuration of a bearing diagnosis system. [Figure 2] Figure 2 is a block diagram showing an example of a bearing diagnosis device according to Embodiment 1. [Figure 3] Figure 3 is a conceptual diagram showing an example of envelope processing. [Figure 4] Figure 4 is a conceptual diagram showing an example of a frequency domain signal after FFT processing. [Figure 5A] Figure 5A is a conceptual diagram showing a transition example of the progress state of peeling generated on the raceway surface. [Figure 5B] Figure 5B is a conceptual diagram showing a transition example of the progress state of peeling generated on the raceway surface. [Figure 5C] Figure 5C is a conceptual diagram showing a transition example of the progress state of peeling generated on the raceway surface. [Figure 6A] Figure 6A is a schematic image diagram showing a transition example of a frequency domain signal. [Figure 6B] Figure 6B is a schematic image diagram showing a transition example of a frequency domain signal. [Figure 6C] Figure 6C is a schematic image diagram showing a transition example of a frequency domain signal. [Figure 7] Figure 7 is a conceptual diagram showing a time transition example of each frequency component. [Figure 8] Figure 8 is a flowchart showing an example of bearing remaining life prediction processing according to Embodiment 1. [Figure 9] Figure 9 is a sub - flowchart showing an example of the first peeling size arrival determination processing. [Figure 10] Figure 10 is a sub - flowchart showing an example of the second peeling size arrival determination processing. [Figure 11] Figure 11 is a conceptual diagram explaining an example of a method for calculating the remaining life of a bearing according to Embodiment 1. [Figure 12] Figure 12 is a flowchart showing an example of bearing remaining life prediction processing according to Embodiment 2. [Figure 13]Figure 13 is a conceptual diagram illustrating an example of a method for deriving a relational expression for predicting the remaining life of a bearing in the bearing remaining life prediction process according to Embodiment 2. [Figure 14] Figure 14 is a conceptual diagram illustrating an example of a bearing remaining life calculation method according to Embodiment 2. [Modes for carrying out the invention]

[0016] Hereinafter, embodiments for carrying out the invention (hereinafter referred to as "embodiments") will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below. Furthermore, the components in the embodiments described below include those that are easily conceivable by those skilled in the art, those that are substantially the same, and those that fall within the so-called equivalent range. Moreover, the components disclosed in the embodiments described below can be combined as appropriate.

[0017] (Embodiment 1) Figure 1 shows an example of a schematic configuration of a bearing diagnostic system. The bearing diagnostic system 1 includes a rolling bearing (hereinafter also simply referred to as "bearing") 11 incorporated into the machinery 10 and a bearing diagnostic device 3.

[0018] Examples of mechanical equipment 10 include railway vehicles, machine tools, wind power generation equipment, elevator equipment, etc. In this disclosure, the bearing diagnostic device 3 predicts the remaining life of the bearing 11 based on vibration signals acquired by vibration sensors 2 installed in the mechanical equipment 10.

[0019] Examples of vibration sensors 2 include acceleration sensors such as acceleration pickups. The vibration sensor 2 can be installed at any location where it can detect vibrations generated by the rotation of the bearing 11. The bearing diagnostic device 3 receives vibration signals (e.g., acceleration) acquired by the vibration sensor 2. In addition to the acceleration sensor used in this embodiment, other vibration sensors such as AE (Acoustic Emission) sensors and ultrasonic sensors can be used as vibration sensors 2. Furthermore, sensors that can detect vibrations equivalently by detecting acceleration, velocity, strain, stress, displacement, etc., and convert them into electrical signals can also be used as appropriate.

[0020] Furthermore, the bearing diagnostic device 3 receives the vibration signal acquired by the vibration sensor 2, as well as the operating conditions of the bearing 11. In this disclosure, the operating conditions of the bearing 11 include the inner ring rotation frequency fr and the cage rotation frequency fc. The inner ring rotation frequency fr and the cage rotation frequency fc are, for example, calculated from the detection signals of various rotational speed sensors (not shown) installed on the machinery 10. These operating conditions of the bearing 11 (specifically, the inner ring rotation frequency fr and the cage rotation frequency fc) are used to calculate the bearing 11 damage frequency, which will be described later.

[0021] Figure 2 is a block diagram showing an example of a bearing diagnostic device according to Embodiment 1. As shown in Figure 2, the bearing diagnostic device 3 according to the embodiment includes an AD conversion unit 31, an envelope processing unit 32, a frequency analysis processing unit 33, a determination processing unit 34, and a storage unit 35.

[0022] The AD conversion unit 31 converts the vibration signal (e.g., acceleration) detected by the vibration sensor 2 into digital data.

[0023] The envelope processing unit 32 performs envelope processing (envelope detection processing) on ​​the vibration signal converted into digital data in the AD conversion unit 31, for example, by absolute value detection. Figure 3 is a conceptual diagram showing an example of envelope processing. In Figure 3, the dashed line shows the vibration signal before envelope processing, and the solid line shows the time-domain signal after envelope processing. Although Figure 3 illustrates envelope processing by absolute value detection, the envelope processing of the vibration signal may also be performed using, for example, a Hilbert transform.

[0024] The frequency analysis processing unit 33 performs a Fast Fourier Transform (FFT) on the signal after envelope processing, converting it into a frequency domain signal that includes signal intensity for each frequency. Figure 4 is a conceptual diagram showing an example of a frequency domain signal after FFT processing.

[0025] The determination processing unit 34 calculates the bearing damage frequency of the bearing 11 based on the above-described operating conditions (inner ring rotation frequency fr and cage rotation frequency fc) as a prerequisite for the bearing diagnostic processing according to this disclosure. The parameters of the bearing 11 (design specification data) used when calculating the bearing damage frequency of the bearing 11 are stored in the storage unit 35 in advance. The storage unit 35 is exemplified by a storage device such as a memory. The determination processing unit 34 may also store the bearing diagnostic processing results and intermediate data, which will be described later, in the storage unit 35.

[0026] The damage frequency resulting from damage to the inner ring 111 (hereinafter also simply referred to as the "inner ring damage frequency") can be expressed as the value obtained by multiplying the number of rolling elements Z by the relative rotation frequency fi between the inner ring rotation frequency fr and the cage rotation frequency fc (= Z × fi, hereinafter also simply referred to as "Zfi"). The inner ring damage frequency Zfi is given by the following equation (1), using the rolling element diameter Da, pitch circle diameter dm, and contact angle α.

[0027]

number

[0028] The damage frequency resulting from damage to the outer ring 112 (hereinafter also simply referred to as the "outer ring damage frequency") can be expressed as the value obtained by multiplying the cage rotation frequency fc by the number of rolling elements Z (= Z × fc, hereinafter also simply referred to as "Zfc"). The outer ring damage frequency Zfc is given by the following equation (2).

[0029]

number

[0030] In the bearing 11 of this disclosure, if scale-like delamination occurs on the surface of the raceway surface 111a of the inner ring 111 (hereinafter also simply referred to as the "inner ring raceway surface") 111a or the raceway surface 112a of the outer ring 112 (hereinafter also simply referred to as the "outer ring raceway surface") 112a, periodic vibrations corresponding to the size of the delamination occur. The following description will explain an example in which delamination occurs on the inner ring raceway surface 111a. In the following description, "damage frequency Zfi" refers to the inner ring damage frequency, but if delamination occurs on the outer ring raceway surface 112a, it can be interpreted as the outer ring damage frequency.

[0031] Delamination occurring on the raceway surface (in this case, the inner ring raceway surface 111a) progresses in the rotational direction over time. Figures 5A, 5B, and 5C are conceptual diagrams showing examples of the progression of delamination on the raceway surface.

[0032] Figures 5A, 5B, and 5C show examples of flaking occurring on the inner ring raceway surface 111a. In Figures 5A, 5B, and 5C, the direction of alignment of the rolling elements 113 is shown as a straight line for ease of explanation. The example shown in Figure 5B shows a case where the flaking size A in the rotational direction on the inner ring raceway surface 111a of the bearing 11 has progressed to a pitch of 0.33 (A / d ≈ 0.33) of the distance d between adjacent rolling elements 113. The example shown in Figure 5C shows a case where the flaking size A in the rotational direction on the inner ring raceway surface 111a of the bearing 11 has progressed to a pitch of 0.5 (A / d = 0.5) of the distance d between adjacent rolling elements 113. Hereinafter, the flaking size A in the rotational direction on the inner ring raceway surface 111a of the bearing 11 will also be simply referred to as "flaking size A in the rotational direction".

[0033] Figures 6A, 6B, and 6C are schematic diagrams illustrating examples of frequency domain signal progression. Figure 7 is a conceptual diagram showing examples of time progression for each frequency component. In the example shown in Figure 7, the solid line represents the time progression of the signal intensity at the damaged frequency Zfi, the dashed line represents the time progression of the signal intensity at the second harmonic of the damaged frequency Zfi (2Zfi), and the dashed-dotted line represents the time progression of the signal intensity at the third harmonic of the damaged frequency Zfi (3Zfi).

[0034] Figure 6A shows a schematic image of the frequency domain signal when a defect occurs on the raceway surface (in this case, the inner ring raceway surface 111a). The example shown in Figure 6B illustrates a schematic image of the frequency domain signal when the delamination size A in the rotational direction progresses to a pitch of 0.33 of the distance d between adjacent rolling elements 113 (hereinafter also simply referred to as "distance between rolling elements") (A / d ≈ 0.33). The example shown in Figure 6C illustrates a schematic image of the frequency domain signal when the delamination size A in the rotational direction progresses to a pitch of 0.5 of the distance between rolling elements d (A / d = 0.5). Figures 6A, 6B, and 6C also schematically show the relative ratios of the signal strength at the damage frequency Zfi, the signal strength at the second harmonic 2Zfi of the damage frequency Zfi, and the signal strength at the third harmonic 3Zfi of the damage frequency Zfi.

[0035] When the delamination size A in the rotational direction progresses to a pitch of 0.33 of the distance d between rolling elements (A / d ≈ 0.33), as shown in Figure 6B, the signal strength of the third harmonic of the damage frequency Zfi, 3Zfi (dotted line), increases around time t1 shown in Figure 7.

[0036] As the delamination size A in the rotational direction progresses further to a pitch of 0.5 (A / d=0.5) in the distance d between rolling elements, the signal strength of the second harmonic of the damage frequency Zfi, 2Zfi (dashed line), increases around time t2 shown in Figure 7, as shown in Figure 6C.

[0037] The bearing diagnostic device 3 and bearing diagnostic method described herein utilize this characteristic to predict the remaining life of the bearing 11. The method for predicting the remaining life of the bearing 11 will be described below.

[0038] Figure 8 is a flowchart showing an example of the bearing remaining life prediction process according to Embodiment 1. In the bearing remaining life prediction process shown in Figure 8, the bearing diagnostic device 3 performs a first delamination size arrival determination process to determine whether the delamination size A in the rotational direction has reached 0.33 pitches of the distance d between rolling elements (A / d ≈ 0.33) (step S100). Figure 9 is a subflowchart showing an example of the first delamination size arrival determination process.

[0039] When the process moves to the first delamination size determination process shown in Figure 9, the determination processing unit 34 of the bearing diagnostic device 3 first initializes the peak value S3peak of the signal intensity of the third harmonic 3Zfi of the damage frequency Zfi and temporarily stores it in the storage unit 35 (S3peak=0, step S101), and also initializes the counter value C1 and temporarily stores it in the storage unit 35 (C1=0, step S102). The peak value S3peak functions as a determination threshold for determining whether the delamination size A in the rotational direction has progressed to a pitch of 0.33 of the distance d between rolling elements (A / d≒0.33) in the first delamination size determination process shown in Figure 9. The counter value C1 indicates the cumulative number of times, in step S106 described later, that the signal intensity S3 of the component corresponding to the third harmonic 3Zfi of the damage frequency Zfi has been determined to be continuously greater than the signal intensity S2 of the component corresponding to the second harmonic 2Zfi of the damage frequency Zfi.

[0040] The AD conversion unit 31 performs AD conversion processing on the vibration signal acquired by the vibration sensor 2 (step S103). The envelope processing unit 32 performs envelope processing on the vibration signal after AD conversion (step S104). The frequency analysis processing unit 33 performs FFT processing on the time-domain signal after envelope processing to perform frequency spectrum analysis (step S105), and extracts the signal intensity S2 of the component corresponding to the second harmonic 2Zfi of the damage frequency Zfi, and the signal intensity S3 of the component corresponding to the third harmonic 3Zfi of the damage frequency Zfi (step S106).

[0041] The signal strength S2 of the component corresponding to the second harmonic 2Zfi of the damaged frequency Zfi is exemplified, for example, by the maximum value of the signal strength within a predetermined frequency range that includes the second harmonic 2Zfi of the damaged frequency Zfi. The signal strength S3 of the component corresponding to the third harmonic 3Zfi of the damaged frequency Zfi is exemplified, for example, by the maximum value of the signal strength within a predetermined frequency range that includes the third harmonic 3Zfi of the damaged frequency Zfi. Hereinafter, the signal strength S2 of the component corresponding to the second harmonic 2Zfi of the damaged frequency Zfi will also be referred to as "the signal strength S2 of the second harmonic component of the damaged frequency." Similarly, the signal strength S3 of the component corresponding to the third harmonic 3Zfi of the damaged frequency Zfi will also be referred to as "the signal strength S3 of the third harmonic component of the damaged frequency."

[0042] Furthermore, the signal intensity S2 of the second harmonic component of the damaged frequency is not limited to the maximum value of the signal intensity within a predetermined frequency range that includes the second harmonic 2Zfi of the damaged frequency Zfi. Specifically, the signal intensity S2 of the second harmonic component of the damaged frequency may be, for example, the integrated value or average value of the signal intensity within a predetermined frequency range that includes the second harmonic 2Zfi of the damaged frequency Zfi, or it may be a trend value such as the maximum value, integrated value, or average value of the signal intensity after filtering.

[0043] Furthermore, the signal intensity S3 of the third harmonic component of the damaged frequency is not limited to the maximum value of the signal intensity within a predetermined frequency range that includes the third harmonic 3Zfi of the damaged frequency Zfi. Specifically, the signal intensity S3 of the third harmonic component of the damaged frequency may be, for example, the integrated value or average value of the signal intensity within a predetermined frequency range that includes the third harmonic 3Zfi of the damaged frequency Zfi, or it may be a trend value such as the maximum value, integrated value, or average value of the signal intensity after filtering.

[0044] The determination processing unit 34 determines whether the signal strength S3 of the third harmonic component of the damaged frequency is greater than the signal strength S2 of the second harmonic component of the damaged frequency (step S107). If the signal strength S3 of the third harmonic component of the damaged frequency is less than or equal to the signal strength S2 of the second harmonic component of the damaged frequency (step S107; No), the process returns to step S102, the counter value C1 is reset (C1=0), and the process from step S103 onwards is executed.

[0045] If the signal strength S3 of the third harmonic component of the damaged frequency is greater than the signal strength S2 of the second harmonic component of the damaged frequency (step S107; Yes), the counter value C1 is incremented (C1 = C1 + 1, step S108), and then the determination processing unit 34 determines whether the counter value C1 is 3 or not (step S109).

[0046] If the counter value C1 is not 3 (step S109; No), the process returns to step S103. If the counter value C1 becomes 3 (step S109; Yes), the determination processing unit 34 determines whether the signal strength S3 of the third harmonic component of the damaged frequency is smaller than the peak value S3peak of the signal strength of the third harmonic component of the damaged frequency temporarily stored in the storage unit 35 (step S110).

[0047] If the signal strength S3 of the third harmonic component of the damaged frequency is greater than or equal to the peak value S3peak (step S110; No), the determination processing unit 34 updates the peak value S3peak temporarily stored in the storage unit 35 to the current signal strength S3 of the third harmonic component of the damaged frequency, and stores the current time t as the first time t1 in the storage unit 35 (S3peak=S3, t1=t, step S111), and returns to the process in step S103.

[0048] If the signal intensity S3 of the third harmonic component of the damage frequency is less than the peak value S3peak (step S110; Yes), the process returns to the bearing remaining life prediction process shown in Figure 8.

[0049] In this disclosure, if the signal intensity S3 of the third harmonic component of the damage frequency has been greater than the signal intensity S2 of the second harmonic component of the damage frequency for three consecutive times, including the present (step S109; Yes), the first time t1 currently stored in the memory unit 35 is determined as the estimated time when the rotational peeling size A on the inner ring raceway surface 111a of the bearing 11 has progressed to a pitch of 0.33 of the distance d between rolling elements (A / d ≈ 0.33).

[0050] Returning to the bearing remaining life prediction process shown in Figure 8, the bearing diagnostic device 3 then performs a second delamination size determination process to determine whether the delamination size A in the rotational direction has reached 0.5 pitches of the distance d between rolling elements (A / d=0.5) (step S200). Figure 10 is a subflowchart showing an example of the second delamination size determination process.

[0051] When the process moves to the second delamination size determination process shown in Figure 10, the determination processing unit 34 of the bearing diagnostic device 3 first initializes the peak value S2peak of the signal intensity of the second harmonic 2Zfi of the damage frequency Zfi and temporarily stores it in the storage unit 35 (S2peak=0, step S201), and also initializes the counter value C2 and temporarily stores it in the storage unit 35 (C2=0, step S202). The peak value S2peak functions as a determination threshold for determining whether the delamination size A in the rotational direction has progressed to a 0.5 pitch (A / d=0.5) of the distance d between rolling elements in the second delamination size determination process shown in Figure 10. The counter value C2 indicates the cumulative number of times, in step 207 described later, the signal strength S2 of the component corresponding to the second harmonic 2Zfi of the damaged frequency Zfi is determined to be continuously greater than the signal strength S1 of the component corresponding to the damaged frequency Zfi, and in step 208 described later, the signal strength S2 of the component corresponding to the second harmonic 2Zfi of the damaged frequency Zfi is determined to be continuously greater than the signal strength S3 of the component corresponding to the third harmonic 3Zfi of the damaged frequency Zfi.

[0052] The AD conversion unit 31 performs AD conversion processing on the vibration signal acquired by the vibration sensor 2 (step S203). The envelope processing unit 32 performs envelope processing on the vibration signal after AD conversion (step S204). The frequency analysis processing unit 33 performs FFT processing on the time-domain signal after envelope processing to perform frequency spectrum analysis (step S205), and extracts the signal intensity S1 of the component corresponding to the damage frequency Zfi, the signal intensity S2 of the component corresponding to the second harmonic 2Zfi of the damage frequency Zfi, and the signal intensity S3 of the component corresponding to the third harmonic 3Zfi of the damage frequency Zfi (step S206).

[0053] The signal strength S1 of the component corresponding to the damage frequency Zfi is exemplified by, for example, the maximum value of the signal strength within a predetermined frequency range that includes the damage frequency Zf. The signal strength S2 of the component corresponding to the second harmonic 2Zfi of the damage frequency Zfi is exemplified by, for example, the maximum value of the signal strength within a predetermined frequency range that includes the second harmonic 2Zfi of the damage frequency Zfi. The signal strength S3 of the component corresponding to the third harmonic 3Zfi of the damage frequency Zfi is exemplified by, for example, the maximum value of the signal strength within a predetermined frequency range that includes the third harmonic 3Zfi of the damage frequency Zfi. Hereinafter, the signal strength S1 of the component corresponding to the damage frequency Zfi will also be referred to as "signal strength S1 of the damage frequency". Furthermore, the signal strength S2 of the component corresponding to the second harmonic 2Zfi of the damage frequency Zfi will also be referred to as "signal strength S2 of the second harmonic component of the damage frequency". Furthermore, the signal strength S3 of the component corresponding to the third harmonic 3Zfi of the damage frequency will also be referred to as "signal strength S3 of the third harmonic component of the damage frequency".

[0054] Furthermore, the signal intensity S1 at the damaged frequency is not limited to the maximum value of the signal intensity within a predetermined frequency range including the damaged frequency Zfi. Specifically, the signal intensity S1 at the damaged frequency may be, for example, the integrated value or average value of the signal intensity within a predetermined frequency range including the damaged frequency Zfi, or it may be a trend value such as the maximum value, integrated value, or average value of the signal intensity after filtering.

[0055] Furthermore, the signal intensity S2 of the second harmonic component of the damaged frequency is not limited to the maximum value of the signal intensity within a predetermined frequency range that includes the second harmonic 2Zfi of the damaged frequency Zfi. Specifically, the signal intensity S2 of the second harmonic component of the damaged frequency may be, for example, the integrated value or average value of the signal intensity within a predetermined frequency range that includes the second harmonic 2Zfi of the damaged frequency Zfi, or it may be a trend value such as the maximum value, integrated value, or average value of the signal intensity after filtering.

[0056] Furthermore, the signal intensity S3 of the third harmonic component of the damaged frequency is not limited to the maximum value of the signal intensity within a predetermined frequency range that includes the third harmonic 3Zfi of the damaged frequency Zfi. Specifically, the signal intensity S3 of the third harmonic component of the damaged frequency may be, for example, the integrated value or average value of the signal intensity within a predetermined frequency range that includes the third harmonic 3Zfi of the damaged frequency Zfi, or it may be a trend value such as the maximum value, integrated value, or average value of the signal intensity after filtering.

[0057] The determination processing unit 34 determines whether the signal strength S2 of the second harmonic component of the damaged frequency is greater than the signal strength S1 of the damaged frequency (step S207). If the signal strength S2 of the second harmonic component of the damaged frequency is less than or equal to the signal strength S1 of the damaged frequency (step S207; No), the process returns to step S202, the counter value C2 is reset (C2=0), and the process from step S203 onwards is executed.

[0058] If the signal strength S2 of the second harmonic component of the damaged frequency is greater than the signal strength S1 of the damaged frequency (step S207; Yes), the determination processing unit 34 then determines whether the signal strength S2 of the second harmonic component of the damaged frequency is greater than the signal strength S3 of the third harmonic component of the damaged frequency (step S208). If the signal strength S2 of the second harmonic component of the damaged frequency is less than or equal to the signal strength S3 of the third harmonic component of the damaged frequency (step S208; No), the process returns to step S202, the counter value C2 is reset (C2=0), and the process from step S203 onwards is executed.

[0059] If the signal strength S2 of the second harmonic component of the damaged frequency is greater than the signal strength S3 of the third harmonic component of the damaged frequency (step S208; Yes), the counter value C2 is incremented (C2 = C2 + 1, step S209), and then the determination processing unit 34 determines whether the counter value C2 is 3 or not (step S210).

[0060] If the counter value C2 is not 3 (step S210; No), the process returns to step S203. If the counter value C2 becomes 3 (step S210; Yes), the determination processing unit 34 determines whether the signal strength S2 of the second harmonic component of the damaged frequency is smaller than the peak value S2peak of the signal strength of the second harmonic component of the damaged frequency temporarily stored in the storage unit 35 (step S211).

[0061] If the signal strength S2 of the second harmonic component of the damaged frequency is greater than or equal to the peak value S2peak (step S211; No), the peak value S2peak temporarily stored in the memory unit 35 is updated to the current signal strength S2 of the second harmonic component of the damaged frequency, and the current time t is stored in the memory unit 35 as the second time t2 (S2peak=S2, t2=t, step S212), and the process returns to step S203.

[0062] If the signal intensity S2 of the second harmonic component of the damage frequency is less than the peak value S2peak (step S211; Yes), the process returns to the bearing remaining life prediction process shown in Figure 8.

[0063] In this disclosure, if the signal intensity S2 of the second harmonic component of the damage frequency has been greater than the signal intensity S1 of the damage frequency for three consecutive times, including the present, and the signal intensity S2 of the second harmonic component of the damage frequency has been greater than the signal intensity S3 of the third harmonic component of the damage frequency for three consecutive times, including the present (step S210; Yes), then the second time t2 currently stored in the memory unit 35 is determined as the estimated time when the rotational peeling size A on the inner ring raceway surface 111a of the bearing 11 has progressed to a pitch of 0.5 of the distance d between rolling elements (A / d=0.5).

[0064] Returning to the bearing remaining life prediction process shown in Figure 8, the determination processing unit 34 calculates the remaining useful life (RUL) of the bearing 11 (step S300). Figure 11 is a conceptual diagram illustrating an example of a bearing remaining life calculation method according to Embodiment 1. In Figure 11, the horizontal axis represents the operating time of the bearing 11, and the vertical axis represents the peeling pitch size, which is the ratio (A / d) of the peeling size A in the rotational direction to the distance d between rolling elements on the inner ring raceway surface 111a of the bearing 11.

[0065] In this disclosure, the relationship between the period (t2-t1) from time t1, when the rotational peeling size A on the inner ring raceway surface 111a of the bearing 11 progresses to a pitch of 0.33 of the distance d between rolling elements (A / d ≈ 0.33), to time t2, when the rotational peeling size A on the inner ring raceway surface 111a of the bearing 11 progresses to a pitch of 0.5 of the distance d between rolling elements (A / d = 0.5), and the peeling size that progressed during that period (t2-t1) (0.5-0.33) is shown by equations (3) and (4) below.

[0066] A / d = a / t ... (3)

[0067] a = (0.5 - 0.33) / (t2 - t1) ... (4)

[0068] In this disclosure, the upper limit of the peeling pitch size, Alim / d, is defined as the usage limit of the bearing 11. In this embodiment, the period from the second time t2, when the peeling size A in the rotational direction has progressed to 0.5 pitches of the distance d between rolling elements (A / d=0.5), until the time trick, when the relational expressions shown in equations (3) and (4) above reach the upper limit Alim / d, is defined as the remaining life RUL of the bearing 11. The remaining life RUL of the bearing 11 at the second time t2, when the peeling size A in the rotational direction has progressed to 0.5 pitches of the distance d between rolling elements (A / d=0.5), is shown by the following equation (5).

[0069] RUL = [(Alim / d) - 0.5] / a ···(5)

[0070] In this disclosure, the upper limit value Alim / d for the peeling pitch size is assumed to be stored in the storage unit 35 in advance. The upper limit value Alim / d for the peeling pitch size may be set by the supplier of the bearing 11, or by the user of the bearing 11.

[0071] The determination processing unit 34 calculates the remaining life RUL of the bearing 11 using equations (3), (4), and (5) above (step S300), and terminates the bearing remaining life prediction process. Specifically, the remaining life RUL of the bearing 11 can be calculated by substituting the first time t1 (the time when the peeling pitch size A / d progresses to 0.33 pitches), which is determined by the first peeling size arrival determination process shown in Figure 9, and the second time t2 (the time when the peeling pitch size A / d progresses to 0.5 pitches), which is determined by the second peeling size arrival determination process shown in Figure 10, into the relational equations shown in equations (3), (4), and (5) above.

[0072] In Embodiment 1, as described above, a first time t1 in which the peeling pitch size A / d progressed to a 0.33 pitch, and a second time t2 in which the peeling pitch size A / d progressed to a 0.5 pitch are estimated. A relationship expression is then obtained between the period from the first time t1 to the second time t2 (t2-t1) and the peeling size that progressed during that period (t2-t1). This relationship expression is then used to estimate the remaining life of the bearing 11. This allows for highly accurate estimation of the remaining life of the bearing 11.

[0073] (Embodiment 2) Figure 12 is a flowchart showing an example of bearing remaining life prediction processing according to Embodiment 2. Here, we will explain in detail the processing that differs from Embodiment 1 described above, and we may omit detailed explanations of the processing that is the same as Embodiment 1 described above.

[0074] In this embodiment, the storage unit 35 is assumed to have already stored relational expressions corresponding to equations (3), (4), and (5) described in Embodiment 1.

[0075] Figure 13 is a conceptual diagram illustrating an example of a method for deriving relational equations for predicting the remaining life of a bearing in the bearing remaining life prediction process according to Embodiment 2. Relational equations corresponding to equations (3) and (4) above can be obtained by performing linear regression on the first time t1 and second time t2 estimated using multiple actual machines of the same type as the bearing 11, as shown in Figure 13.

[0076] In the bearing remaining life prediction process according to Embodiment 2 shown in Figure 12, the bearing diagnostic device 3 performs a first delamination size determination process (step S100), then returns to the bearing remaining life prediction process shown in Figure 12, and the determination processing unit 34 calculates the remaining life RUL of the bearing 11 (step S300a). Figure 14 is a conceptual diagram illustrating an example of the bearing remaining life calculation method according to Embodiment 2. In Figure 14, the horizontal axis represents the operating time of the bearing 11, and the vertical axis represents the delamination pitch size, which is the ratio (A / d) of the delamination size A in the rotational direction and the distance d between rolling elements on the inner ring raceway surface 111a of the bearing 11.

[0077] In this embodiment, the remaining life RUL of the bearing 11 is defined as the period (tlim-t1) from the first time t1, when the delamination size A in the rotational direction has progressed to a pitch of 0.33 of the distance d between rolling elements (A / d ≈ 0.33), until the time trick, when the relational expressions shown in equations (3) and (4) above reach the upper limit Alim / d. The remaining life RUL of the bearing 11 at the first time t1, when the delamination size A in the rotational direction has progressed to a pitch of 0.33 of the distance d between rolling elements (A / d ≈ 0.33), is given by equation (6) below.

[0078] RUL=[(Alim / d)-0.33] / a···(6)

[0079] In this embodiment, equations (3), (4), (6), and the upper limit value Alim / d for the isolation pitch size are stored in the storage unit 35 in advance. Therefore, the remaining life RUL of the bearing 11 at the first time t1 (the time when the peeling pitch size A / d has progressed to 0.33 pitches), which is estimated by the first peeling size determination process (step S100), can be calculated in advance using equation (6).

[0080] The determination processing unit 34 applies the remaining life RUL of the bearing 11 calculated using the above equation (6) (step S300a), and terminates the bearing remaining life prediction process.

[0081] In Embodiment 2, as described above, using the first time t1 and second time t2 estimated from multiple actual machines of the same type as the bearing 11, a relationship formula between the first time t1 when the peeling pitch size A / d has progressed to 0.33 pitches, the second time t2 when the peeling pitch size A / d has progressed to 0.5 pitches, and the peeling size that progresses during the period from the first time t1 to the second time t2 is stored in advance, and the remaining life of the bearing 11 is estimated using this relationship formula. As a result, the remaining life of the bearing 11 can be estimated with high accuracy, similar to Embodiment 1. Furthermore, the remaining life RUL of the bearing 11 at the time when the peeling pitch size A / d has progressed to 0.33 pitches can be calculated in advance.

[0082] In the above-described embodiment 2, an example was given of obtaining the relational expression by performing linear regression on a first time t1 and a second time t2 estimated from multiple actual machines of the same type as the bearing 11, but the invention is not limited to this. Specifically, for example, instead of the first time t1 or the second time t2, the relational expression may be obtained by estimating a third time, when the separation size A in the rotational direction has progressed to a pitch of 0.66 of the distance d between rolling elements (A / d ≈ 0.66), from multiple actual machines of the same type as the bearing 11 and performing linear regression.

[0083] Furthermore, while the above-described embodiment 2 illustrates a method for calculating the remaining life RUL at a first time point t1 when the peeling pitch size A / d has progressed to 0.33 pitch, the invention is not limited thereto. Specifically, for example, similar to embodiment 1, the method may be to calculate the remaining life RUL at a second time point t2 when the peeling pitch size A / d has progressed to 0.5 pitch, or to calculate the remaining life RUL at a third time point when the peeling pitch size A / d has progressed to 0.66 pitch. [Explanation of Symbols]

[0084] 1. Bearing diagnostic system 2. Vibration Sensor 3. Bearing diagnostic device 10. Mechanical equipment 11 bearings 31 AD Conversion Unit 32 Envelope Processing Unit 33 Frequency Analysis Processing Unit 34. Determination Processing Unit 35 Storage section 111 Inner Ring 111a Track surface (inner ring track surface) 112 Outer ring 112a Track surface (outer ring track surface) 113 Rolling element

Claims

1. A bearing diagnostic device for diagnosing the condition of bearings installed in mechanical equipment, An envelope processing unit that performs envelope processing on vibration signals acquired by a vibration sensor, A frequency analysis processing unit performs a fast Fourier transform on the time-domain signal after envelope processing to convert it into a frequency-domain signal that includes signal intensity for each frequency. A determination processing unit estimates a first time point at which the damage progresses to a first degree on the bearing raceway surface based on the signal intensity of the third harmonic component of the damage frequency caused by damage occurring on the bearing raceway surface, and estimates a second time point at which the damage progresses to a second degree on the bearing raceway surface based on the signal intensity of the second harmonic component of the damage frequency, and predicts the remaining life of the bearing based on the first and second time points. Equipped with, Bearing diagnostic device.

2. The determination processing unit, A relationship formula is determined between the period from the first time to the second time and the degree of damage that progressed during that period. The time at which the estimated degree of damage calculated using this relationship formula reaches a predetermined upper limit of the degree of damage is estimated as the remaining life of the bearing. The bearing diagnostic device according to claim 1.

3. A bearing diagnostic device for diagnosing the condition of bearings installed in mechanical equipment, A storage unit that pre-stores a relationship between a first time point at which the bearing raceway surface progresses to a first degree of damage, a second time point at which the bearing raceway surface progresses to a second degree of damage, and the degree of damage that progresses during the period from the first time point to the second time point. An envelope processing unit that performs envelope processing on vibration signals acquired by a vibration sensor, A frequency analysis processing unit performs a fast Fourier transform on the time-domain signal after envelope processing to convert it into a frequency-domain signal that includes signal intensity for each frequency. Based on the signal intensity of the second or third harmonic component of the damage frequency caused by damage occurring on the raceway surface of the bearing, the first or second time is estimated, and by substituting this into the relational formula, the time at which the estimated value of the degree of damage estimated by the relational formula becomes the predetermined upper limit of the degree of damage is estimated as the remaining life of the bearing. Bearing diagnostic device.

4. The aforementioned first degree of damage is, This indicates a state in which the size of the delamination in the rotational direction of the damage occurring on the raceway surface of the bearing has progressed to a pitch of 0.33, which is the distance between adjacent rolling elements. The second degree of damage is, This shows a state where the peeling size has progressed to a pitch of 0.5 units, which is the distance between adjacent rolling elements. The bearing diagnostic device according to claim 2 or 3.

5. A bearing diagnostic method for diagnosing the condition of bearings installed in mechanical equipment, An envelope processing step that performs envelope processing on vibration signals acquired by a vibration sensor, A frequency analysis step involves performing a Fast Fourier Transform on the time-domain signal after envelope processing to convert it into a frequency-domain signal that includes signal intensity for each frequency, A determination process step in which, based on the signal intensity of the second and third harmonic components of the damage frequency caused by damage occurring on the raceway surface of the bearing, a first time point at which the damage progressed to a first degree and a second time point at which the damage progressed to a second degree on the raceway surface of the bearing are estimated, and the remaining life of the bearing is predicted based on the first and second time points, Having, Bearing diagnostic methods.

6. In the aforementioned determination process step, A relationship formula is determined between the period from the first time to the second time and the degree of damage that progressed during that period. The time at which the estimated degree of damage calculated using this relationship formula reaches a predetermined upper limit of the degree of damage is estimated as the remaining life of the bearing. The bearing diagnostic method according to claim 5.

7. A bearing diagnostic method for diagnosing the condition of bearings installed in mechanical equipment, A relationship formula is pre-established between the first time point at which the bearing raceway surface progresses to a first degree of damage, the second time point at which the bearing raceway surface progresses to a second degree of damage, and the degree of damage that progresses during the period from the first time point to the second time point. An envelope processing step that performs envelope processing on vibration signals acquired by a vibration sensor, A frequency analysis step involves performing a Fast Fourier Transform on the time-domain signal after envelope processing to convert it into a frequency-domain signal that includes signal intensity for each frequency, A determination process step in which, based on the signal intensity of the second or third harmonic component of the damage frequency caused by damage occurring on the raceway surface of the bearing, the first time or the second time is estimated, and this is substituted into the relational formula, and the time at which the estimated value of the degree of damage estimated by the relational formula becomes the predetermined upper limit of the degree of damage is estimated to be the remaining life of the bearing, Having, Bearing diagnostic methods.

8. The aforementioned first degree of damage is, This indicates a state in which the size of the delamination in the rotational direction of the damage occurring on the raceway surface of the bearing has progressed to a pitch of 0.33, which is the distance between adjacent rolling elements. The second degree of damage is, This shows a state where the peeling size has progressed to a pitch of 0.5 units, which is the distance between adjacent rolling elements. The bearing diagnostic method according to claim 6 or 7.

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