Method and apparatus for monitoring rolling bearing

Abstract

To provide a rolling bearing monitoring device and its method capable of more properly finding a peak.SOLUTION: In the present invention, a frequency spectrum of vibration data representing vibration of a rolling bearing is obtained for each sampling period and stored in a storage unit in association with the sampling period, and a specific peak that does not appear in a normal state is detected from the frequency spectrum within a first frequency range including a theoretical frequency at which a peak occurs in an abnormal state. When the specific peak is searched, the present invention detects the specific peak as a re-detected specific peak in a second frequency range narrower than the first frequency range including the specific peak for one or a plurality of frequency spectra stored in the storage unit 6 before the sampling period, and displays the specific peak and the re-detected specific peak on the display unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rolling bearing monitoring method and a rolling bearing monitoring device. [Background technology]

[0002] A rolling bearing is a device that supports a load by placing rolling elements, such as balls or rollers, between two components (a shaft and a raceway), and is installed in devices with a variety of applications that include a rotating body. These rolling bearings can suffer from abnormalities, such as wear (wear and scratches), fatigue due to deformation, and fusion due to pressure, which can impede smooth rolling and cause malfunctions of the device. For this reason, it is desirable to monitor the condition (status) of rolling bearings. For example, Patent Document 1 discloses a vibration analyzer that diagnoses rolling bearings.

[0003] The vibration analyzer disclosed in Patent Document 1 is a vibration analyzer that diagnoses the state of a machine based on detected vibrations, and includes: a setting unit that sets a diagnosis target, a rotational speed, and a judgment reference value; a condition judgment unit that judges diagnostic conditions from information about the diagnosis target; an analysis unit that performs frequency analysis of input data; and an abnormality judgment unit that judges whether the diagnosis target is abnormal based on the judgment reference value. Patent Document 1 lists a rolling bearing as the diagnosis target (see, for example, paragraph

[0018] thereof), and the abnormality judgment unit determines a frequency range in which a peak is expected to appear when the bearing is damaged, based on the bearing's geometric dimensions (the bearing's characteristic frequency) that produce a peak in the frequency spectrum when an abnormality occurs, and displays a trend graph of the first-order peak that appears near the theoretical frequency (the bearing's characteristic frequency) (see, for example, paragraphs

[0056] ,

[0077] , and

[0083] thereof, and Figures 12 and 15). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-120875 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, a theoretical frequency based on the geometric dimensions of the rolling bearing is used to determine the frequency range in which a peak is expected to appear on the frequency spectrum when an abnormality occurs. However, in reality, a peak does not necessarily occur at the theoretical frequency when an abnormality occurs, and a peak may occur at a frequency deviating from the theoretical frequency. Furthermore, when a peak related to an abnormality initially appears, its amplitude is small, making it difficult to distinguish between other peaks unrelated to the abnormality and to find the peak related to the abnormality. In other words, when a fault occurs in a rolling bearing in a normal state that interferes with smooth rolling, it is difficult to detect the peak caused by the fault in the early stages. However, it becomes possible to detect the peak caused by the fault only after the fault progresses and the amplitude of the peak increases. Therefore, it has been difficult to understand how the amplitude of the peak caused by the fault has changed over the period before the peak becomes detectable. [Means for solving the problem]

[0006] After extensive investigation, the inventors have found that the above object can be achieved by the present invention described below. That is, a rolling bearing monitoring method according to one aspect of the present invention comprises a spectrum processing step of acquiring vibration data representing vibrations occurring in a rolling bearing at predetermined acquisition intervals for a predetermined sampling period, determining a frequency spectrum of the vibration data for that sampling period, and storing the determined frequency spectrum in a storage unit in association with that sampling period; a peak detection step of detecting from the frequency spectrum a specific peak that does not appear when the rolling bearing is normal within a predetermined first frequency range that includes a theoretical frequency that will produce a peak on the frequency spectrum when an abnormality has occurred; and, if a specific peak is detected in the peak detection step, detecting the specific peak. and a display step of displaying on a display unit time information relating to the sampling period when a re-detected specific peak is detected in the peak detection step and the amplitude of the detected specific peak, and time information relating to the sampling period when a re-detected specific peak is detected in the peak re-detection step. Preferably, in the above-mentioned rolling bearing monitoring method, the first frequency range is set so that the theoretical frequency is its center frequency.

[0007] Typically, when a rolling bearing in a normal state experiences some kind of fault that impairs smooth rolling, the fault progresses and the peak amplitude increases, after which the peak can be identified and its frequency can be determined. Meanwhile, peaks before identification are presumed to occur around the identified frequency. The rolling bearing monitoring method detects specific peaks in a first frequency range that includes the theoretical frequency, thereby enabling more reliable detection of the specific peak. Furthermore, the method redetects the specific peak by narrowing the first frequency range to a second frequency range that is narrower than the first frequency range. This eliminates from detection peaks that are included in the first frequency range but are not caused by the fault, enabling more accurate detection of the specific peak caused by the fault. Furthermore, the display unit displays the amplitude values ​​of peaks generated by faults in the rolling bearing prior to the point at which the peaks became detectable, allowing the user to understand the trends in peak amplitude over time.

[0008] In another aspect, in the above-mentioned rolling bearing monitoring method, when the peak redetection step detects the redetected specific peak in a past direction for the multiple frequency spectra, the peak detection step and the specific peak detected in the peak detection step are regarded as the initial peak redetection step and the initial redetected specific peak, respectively, for each of the multiple frequency spectra, and the redetected specific peak is detected in the second frequency range that includes the redetected specific peak detected in the previous peak redetection step for that frequency spectrum. Preferably, in the above-mentioned rolling bearing monitoring method, the second frequency range is set so that the frequency of the redetected specific peak is its center frequency. Preferably, in the above-mentioned rolling bearing monitoring method, the peak redetection step detects the redetected specific peak continuously and sequentially in a past direction for the multiple frequency spectra. Preferably, in the above-mentioned rolling bearing monitoring method, the peak redetection step detects the redetected specific peak discontinuously in a past direction for the multiple frequency spectra.

[0009] This rolling bearing monitoring method detects the redetected specific peak in a second frequency range that includes the redetected specific peak detected in the previous peak redetection process, so that the redetected specific peak can be detected more reliably even if the frequency of the redetected specific peak changes over time.

[0010] In another aspect, in the above-mentioned rolling bearing monitoring method, the display step displays on the display unit a Cartesian coordinate system with the horizontal axis representing time information related to the sampling period and the vertical axis representing the amplitude, and displays on the display unit a predetermined first mark at a first coordinate represented by the time information related to the sampling period when a specific peak is detected in the peak detection step and the amplitude of the detected specific peak, and displays on the display unit a predetermined second mark at a second coordinate represented by the time information related to the sampling period when a re-detected specific peak is detected in the peak re-detection step and the amplitude of the re-detected specific peak. Preferably, in the above-mentioned rolling bearing monitoring method, the first mark and the second mark are the same mark. Preferably, in the above-mentioned rolling bearing monitoring method, the first mark and the second mark are different marks.

[0011] The time information regarding the sampling period when a specific peak is detected in the peak detection process and the amplitude of the detected specific peak, and the time information regarding the sampling period when a re-detected specific peak is detected in the peak re-detection process and the amplitude of the re-detected specific peak are displayed on an orthogonal coordinate system, so that the user (operator) can visually recognize the change over time between the re-detected specific peak and the specific peak, and can visually recognize the progression of the fault (tendency of change over time, trend) in an easy-to-understand display format.

[0012] In another aspect, the above-mentioned rolling bearing monitoring method further comprises a peak detection continuation step, in which, when a specific peak is detected in the peak detection process, for each sampling period after the sampling period in which the specific peak is detected, the peak detection continuation step detects, as a detected specific peak, a specific peak that does not appear when the rolling bearing is normal, within a predetermined second frequency range that includes the frequency of the specific peak and is narrower than the first frequency range, for the frequency spectrum stored in the memory unit for that sampling period, and the display step further displays, on the display unit, for each sampling period after the sampling period in which the specific peak is detected, the sampling period in which the specific peak is detected and the amplitude of the detected specific peak detected in the peak detection continuation step.

[0013] This rolling bearing monitoring method includes a peak detection continuation step, so that a specific peak can be detected for each sampling period after the sampling period in which a specific peak was detected in the peak detection step, and detection of the specific peak can be continued.

[0014] In another aspect, in the above-mentioned rolling bearing monitoring method, the peak detection continuation process regards the peak detection process and the specific peak detected in the peak detection process as the first peak detection continuation process and the first post-detection specific peak, respectively, and detects the post-detection specific peak in the second frequency range that includes the post-detection specific peak detected in the peak detection continuation process immediately before the sampling period for the frequency spectrum stored in the memory unit for the sampling period.

[0015] This rolling bearing monitoring method detects the post-detection specific peak in a second frequency range that includes the post-detection specific peak detected in the previous peak re-detection continuation process, so that the post-detection specific peak can be detected more reliably even if the frequency of the post-detection specific peak changes over time.

[0016] In another aspect, in the above-mentioned rolling bearing monitoring method, the display step is a process of displaying on the display unit a Cartesian coordinate system with the horizontal axis representing time information related to the sampling period and the vertical axis representing the amplitude, displaying on the display unit a predetermined first mark at a first coordinate represented by time information related to the sampling period when a specific peak is detected in the peak detection step and the amplitude of the detected specific peak, displaying on the display unit a predetermined second mark at a second coordinate represented by time information related to the sampling period when a re-detected specific peak is detected in the peak re-detection step and the amplitude of the detected re-detected specific peak, and displaying on the display unit a predetermined third mark at a third coordinate represented by time information related to the sampling period when a post-detection specific peak is detected in the peak detection continuing step and the amplitude of the detected post-detection specific peak. Preferably, in the above-mentioned rolling bearing monitoring method, the first mark, the second mark, and the third mark are the same mark. Preferably, in the above-mentioned rolling bearing monitoring method, the first mark, the second mark, and the third mark are mutually different marks. Preferably, in the above-described rolling bearing monitoring method, the first mark, the second mark, and the third mark are partially the same mark.

[0017] This rolling bearing monitoring method displays, in an orthogonal coordinate system, time information regarding the sampling period when a specific peak is detected in the peak detection process and the amplitude of the detected specific peak, time information regarding the sampling period when a re-detected specific peak is detected in the peak re-detection process and the amplitude of the detected re-detected specific peak, and time information regarding the sampling period when a post-detection specific peak is detected in the peak detection continuation process and the amplitude of the detected post-detection specific peak, so that the user (operator) can visually see the changes over time between the re-detected specific peak, the specific peak, and the post-detection specific peak, and how the fault is progressing (tendency of change over time, trend) in an easy-to-understand display format.

[0018] In another aspect, in the above-described rolling bearing monitoring method, the length of the sampling period is set based on the second frequency range, and the narrower the second frequency range, the longer the sampling period is set.

[0019] This rolling bearing monitoring method can detect peaks from frequency spectrum data with a frequency resolution suitable for the second frequency range.

[0020] A rolling bearing monitoring device according to another aspect of the present invention comprises a vibration detection sensor that acquires vibration data representing vibrations occurring in a rolling bearing, a storage unit, a control processing unit that performs spectrum processing, peak detection processing, peak re-detection processing and display processing, and a display unit, wherein the spectrum processing is a process of acquiring data for a predetermined sampling period at predetermined acquisition intervals, determining a frequency spectrum of the vibration data for that sampling period for that vibration data, and storing the determined frequency spectrum in the storage unit in association with that sampling period, and the peak detection processing is a process of detecting a specific peak that does not appear when the rolling bearing is normal from the frequency spectrum within a predetermined first frequency range that includes a theoretical frequency that will produce a peak on the frequency spectrum when an abnormality occurs. the peak re-detection process is a process of detecting, when a specific peak is detected in the peak detection process, as a re-detected specific peak, a specific peak that does not appear when the rolling bearing is normal, within a predetermined second frequency range narrower than the first frequency range and that includes the frequency of the specific peak detected in the peak detection process, for one or more frequency spectra stored in the storage unit prior to the sampling period when the specific peak is detected; and the display process is a process of displaying, on the display unit, time information regarding the sampling period when the specific peak is detected in the peak detection process and the amplitude of the detected specific peak, and time information regarding the sampling period when the re-detected specific peak is detected in the peak re-detection process and the amplitude of the detected re-detected specific peak.

[0021] Such a rolling bearing monitoring device can more appropriately find peaks (specific peaks and redetected specific peaks). [Effects of the Invention]

[0022] The rolling bearing monitoring method and rolling bearing monitoring device of the present invention display on a display unit what the amplitude of a peak caused by a fault in a rolling bearing was in the period prior to the point at which the peak became detectable, allowing the user to understand the trends in peak amplitude over the past. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a block diagram showing a configuration of a rolling bearing monitoring device according to an embodiment; [Figure 2] FIG. 10 is a diagram for explaining a predetermined time length in vibration data. [Figure 3] FIG. 1 is a diagram illustrating a mechanical facility equipped with a rolling bearing. [Figure 4] FIG. 3 is a diagram for explaining first and second frequency ranges. [Figure 5] FIG. 10 is a diagram illustrating a display screen of peaks (specific peaks and re-searched specific peaks) as an example. [Figure 6] 4 is a flowchart showing the operation of the rolling bearing monitoring device before a specific peak is detected. [Figure 7] 10 is a flowchart showing the operation of the rolling bearing monitoring device after the specific peak is detected. [Figure 8] FIG. 10 is a block diagram showing the configuration of a rolling bearing monitoring device according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments. In addition, components with the same reference numerals in each drawing indicate the same components, and their description will be omitted as appropriate. In this specification, when referring to a general term, a reference numeral without a subscript is used, and when referring to an individual component, a reference numeral with a subscript is used.

[0025] FIG. 1 is a block diagram showing the configuration of a rolling bearing monitoring device according to an embodiment. FIG. 2 is a diagram illustrating a predetermined time length in vibration data. FIG. 3 is a diagram illustrating mechanical equipment equipped with a rolling bearing. FIG. 4 is a diagram illustrating first and second frequency ranges. FIG. 4A shows the first frequency range, and FIG. 4B shows the second frequency range. The horizontal axis in each of FIGS. 4A and 4B represents frequency [Hz], and the vertical axis represents amplitude. FIG. 5 is a diagram illustrating, as an example, a display screen for peaks (specific peaks and re-searched specific peaks). FIG. 5A shows the case of a first example of mechanical equipment, and FIG. 5B shows the case of a second example of mechanical equipment.

[0026] The rolling bearing monitoring device 1000 in the embodiment includes, for example, a vibration detection sensor 1, a control processing unit 2, an input unit 3, a display unit 4, an interface unit (IF unit) 5, and a storage unit 6, as shown in FIG.

[0027] The vibration detection sensor 1 is connected to the control processing unit 2 and is a device that acquires vibration data that represents vibrations occurring in the rolling bearing in accordance with the control of the control processing unit 2. In this embodiment, the vibration detection sensor 1 detects vibrations occurring in the rolling bearing, and stores a plurality of vibration data acquired over a predetermined sampling period at predetermined acquisition intervals in the storage unit 6.

[0028] As described below, vibration data is transformed from time space to frequency space using a fast Fourier transform. In this case, the frequency resolution of the frequency spectrum depends on the number of data points used in the fast Fourier transform. The greater the number of data points, the higher the frequency resolution, and the corresponding amount of vibration data is required for the predetermined sampling period. Here, if the sampling interval is SP, the number of data points is Nfft, and the length of the predetermined sampling period is TW, then TW = SP × Nfft. In this embodiment, the length of the predetermined sampling period TW is set based on the second frequency range FW2 described below. The narrower the second frequency range, the longer the sampling period is set. To detect significant peaks in the second frequency range ±Δfw2, for example, as shown in FIG. 2, the second frequency range ±Δfw2 (= 2 × Δfw2) needs to be divided into four or more parts. Therefore, the frequency resolution is 2 × Δfw2 / 4 = Δfw2 / 2 [Hz] or greater, and therefore the length of the predetermined sampling period TW is equal to or greater than its reciprocal, 2 / Δfw2 [seconds]. For example, if Δfw2 is set to 0.02 Hz and the sampling interval SP is set to 0.2 ms (= 0.0002 s), the length TW of the predetermined sampling period is TW = 2 / 0.02 = 100 s or more, and the number of data points Nfft is Nfft = 100 / 0.0002 = 500,000 or more. Since fast Fourier transforms generally handle powers of 2, the minimum number exceeding 500,000 is 2^19 = 524,288, and the length TW of the predetermined sampling period is TW = 0.0002 × 524,288 = 104.8576 s.

[0029] One or more vibration detection sensors 1 are installed in a device to be monitored, such as a mechanical facility, that includes a rolling bearing. The mechanical facility is an example of a device that includes a rolling bearing, and may be any facility that includes a rolling bearing. For example, the mechanical facility M is a reducer M shown in FIG. 3, which generally includes first through third rolling bearings BE-1 through BE-3, first and second rotating shafts AX-1 and AX-2, first and second gears GA-1 and GA-2, and a housing (not shown) that accommodates the first through third rolling bearings BE-1 through BE-3, the first and second rotating shafts AX-1 and AX-2, and the first and second gears GA-1 and GA-2. The first rotating shaft AX-1 is fixed to the first gear GA-1 and is the rotating shaft of the first gear GA-1, and is supported by the first rolling bearing BE-1. The second rotating shaft AX-2 is fixed to the second gear GA-2, is the rotating shaft of this second gear GA-1, and is supported by the second and third rolling bearings BE-2 and BE-3. The first gear GA-1 and the second gear GA-2 are in mesh with each other, and for example, the rotational force caused by the rotation of the first rotating shaft AX-1 is transmitted to the second rotating shaft AX-2 via the first and second gears GA-1 and GA-2, causing the second rotating shaft AX-2 to rotate.

[0030] For the reducer M configured as described above, the vibration detection sensor 1 includes three vibration detection sensors, namely, first to third vibration detection sensors 1-1 to 1-3. The first to third vibration detection sensors 1-1 to 1-3 are respectively arranged on the outer peripheries of the first to third rolling bearings BE-1 to BE-3. The vibration detection sensors 1 (1-1 to 1-3) are not limited to the rolling bearings BE, and may be arranged, for example, on the housing. In short, the first to third vibration detection sensors 1-1 to 1-3 are arranged at locations where vibrations caused by the rolling bearings BE propagate. The first to third vibration detection sensors 1-1 to 1-3 are, for example, acceleration sensors or AE (Acoustic Emission) sensors, and appropriate sensors are used depending on the frequency of vibrations occurring in the monitored object. In this embodiment, the first to third vibration detection sensors 1-1 to 1-3 output detection results to the control processing unit 2.

[0031] In this embodiment, for example, when a predetermined sampling period starts, the control processing unit 2 instructs the first through third vibration detection sensors 1-1 to 1-3 to acquire the vibration data, and in response to this instruction, the first through third vibration detection sensors 1-1 to 1-3 detect vibrations at each sampling timing according to a predetermined sampling interval and output vibration data for the length TW of the predetermined sampling period to the control processing unit 2. The control processing unit 2 stores and saves the vibration data in the storage unit 6 in association with the sampling period (for example, the start time of the sampling period).

[0032] The input unit 3 is connected to the control processing unit 2 and is a device that inputs various commands, such as a command to start monitoring, and various data required to operate the rolling bearing monitoring device 1000, such as the name of the machinery and equipment to be monitored, to the rolling bearing monitoring device 1000, and is, for example, a plurality of input switches to which predetermined functions are assigned, a keyboard, a mouse, etc. The display unit 4 is connected to the control processing unit 2 and is a device that displays the commands and data input from the input unit 3, as well as the monitoring results, etc., in accordance with the control of the control processing unit 2, and is, for example, a display device such as a CRT display, liquid crystal display, or organic EL display.

[0033] The input unit 3 and display unit 4 may also form a so-called touch panel. When this touch panel is formed, the input unit 3 is a position input device, such as a resistive film type or a capacitive type, that detects an operation position and inputs the position. In this touch panel, the position input device is provided on the display surface of the display unit 4, and one or more input content candidates that can be input are displayed on the display unit 4. When the user touches the display position showing the input content that the user wants to input, the position is detected by the position input device, and the display content displayed at the detected position is input to the rolling bearing monitoring device 1000 as the user's operation input content. Such a touch panel makes it easy for the user to intuitively understand input operations, and therefore provides a rolling bearing monitoring device 1000 that is easy for the user to use.

[0034] The IF unit 5 is connected to the control processing unit 2 and is a circuit that inputs and outputs data to and from external devices under the control of the control processing unit 2, and is, for example, an interface circuit for RS-232C, which is a serial communication method, an interface circuit using the Bluetooth (registered trademark) standard, an interface circuit for infrared communication such as the IrDA (Infrared Data Association) standard, and an interface circuit using the USB (Universal Serial Bus) standard. The IF unit 5 is also a circuit that communicates with external devices, and may be, for example, a data communication card or a communication interface circuit conforming to the IEEE802.11 standard or the like.

[0035] The memory unit 6 is connected to the control processing unit 2 and is a circuit that stores various predetermined programs and various predetermined data under the control of the control processing unit 2. The various predetermined programs include, for example, a control processing program, which includes a control program, a spectrum processing program, a peak detection program, a peak redetection program, a peak detection continuation program, and a display processing program. The control program controls each of the units 1, 3-6 of the rolling bearing monitoring device 1000 according to its function. The spectrum processing program acquires multiple vibration data sets from the vibration detection sensor 1 over multiple different sampling periods, calculates a frequency spectrum for the vibration data over each sampling period, and stores the calculated frequency spectrum in the memory unit 6 in association with the sampling period. The peak detection program searches for a specific peak that does not appear when the rolling bearing is normal within a predetermined first frequency range that includes a theoretical frequency that produces a peak on the frequency spectrum when an abnormality occurs. The peak re-detection program is a program that, when a specific peak is detected by the peak detection program, detects, as a re-detected specific peak, a specific peak that does not appear when the rolling bearing is normal, and that includes the frequency of the specific peak detected by the peak detection program, within a predetermined second frequency range narrower than the first frequency range, for one or more frequency spectra that are associated with each other and stored in the storage unit 6 before the sampling period when the specific peak is detected.The peak detection continuation program is a program that, when a specific peak is detected by the peak detection program, detects, for each sampling period after the sampling period when the specific peak is detected, a specific peak that does not appear when the rolling bearing is normal, within a predetermined second frequency range narrower than the first frequency range, and that includes the frequency of the specific peak, for the frequency spectra stored in the storage unit 6 during that sampling period.The display processing program is a program that displays, on the display unit 4, time information (e.g., date, part of time information, etc.) related to a sampling period when a specific peak is detected by the peak detection program and the amplitude of the detected specific peak, and time information (e.g., date, part of time information, etc.) related to a sampling period when a re-detected specific peak is detected by the peak re-detection program and the amplitude of the re-detected specific peak. The various predetermined data include, for example, data necessary for executing each of these programs, such as a frequency spectrum associated with time information related to the sampling period, a theoretical frequency, a first frequency range, a second frequency range, a specific peak, and a re-detected specific peak. The storage unit 6 includes, for example, a nonvolatile storage element such as a read-only memory (ROM) or a rewritable nonvolatile storage element such as an electrically erasable programmable read-only memory (EEPROM). The storage unit 6 also includes a random access memory (RAM) that serves as a working memory for the control processing unit 2 and stores data generated during execution of the predetermined programs. The storage unit 6 may include a hard disk drive (HHD) or a solid state drive (SSD) that can store a relatively large amount of data.

[0036] The control processing unit 2 is a circuit that controls each of the units 1, 3 to 6 of the rolling bearing monitoring device 1000 in accordance with the function of each unit, and monitors the rolling bearing BE (the state (condition) of the rolling bearing BE). The control processing unit 2 is configured to include, for example, a CPU (Central Processing Unit) and its peripheral circuits. When the control processing program is executed in the control processing unit 2, a control unit 21, a spectrum processing unit 22, a peak detection unit 23, a peak re-detection unit 24, a peak detection continuation unit 25, and a display processing unit 26 are functionally configured.

[0037] The control unit 21 controls each of the units 1, 3 to 6 of the rolling bearing monitoring device 1000 in accordance with the function of each unit, and is responsible for controlling the rolling bearing monitoring device 1000 as a whole.

[0038] The spectrum processing unit 22 performs spectrum processing to acquire vibration data for each of a plurality of different sampling periods by the vibration detection sensor 1, and for each of the plurality of sampling periods, calculates a frequency spectrum of the vibration data for that sampling period and stores the calculated frequency spectrum in the storage unit 6 in association with the sampling period. More specifically, in the spectrum processing unit, at the start timing of a sampling period having a preset acquisition interval, vibration data is acquired by each of the first to third vibration detection sensors 1-1 to 1-3 for the length TW of the predetermined sampling period, and the data is stored in the storage unit 6. The spectrum processing unit 22 then acquires the vibration data as the vibration data for the current sampling period. Next, the spectrum processing unit 22 converts the vibration data in time space acquired by the first vibration detection sensor 1-1 into vibration data in frequency space by, for example, fast Fourier transform (FFT), thereby calculating the frequency spectrum of the vibration data, and stores the frequency spectrum in association with the sampling period and the first vibration detection sensor 1-1 (for example, an identifier (sensor ID) of the first vibration detection sensor 1-1) in the storage unit 6. Next, similarly, the spectrum processing unit 22 converts the vibration data in time space acquired by the second vibration detection sensor 1-2 into vibration data in frequency space using the FFT, thereby obtaining a frequency spectrum of the vibration data, and stores the frequency spectrum in the storage unit 6 in association with the sampling period and the second vibration detection sensor 1-2 (e.g., the identifier (sensor ID) of the second vibration detection sensor 1-2). Similarly, the spectrum processing unit 22 converts the vibration data in time space acquired by the third vibration detection sensor 1-3 into vibration data in frequency space using the FFT, thereby obtaining a frequency spectrum of the vibration data, and stores the frequency spectrum in association with the sampling period and the third vibration detection sensor 1-3 (e.g., the identifier (sensor ID) of the third vibration detection sensor 1-3) in association with the sampling period. This process is repeatedly executed at the start timing of the sampling period at a preset acquisition interval. The acquisition interval is set in advance as appropriate depending on, for example, the lifespan of the monitored object. The lifespan of a rolling bearing can be predicted from, for example, the load and rotation speed.For example, if the monitoring target is a rolling bearing that supports a shaft that is used relatively hard, such as a shaft that is constantly operated and rotates at high speed, the acquisition interval is set to a relatively short time length, such as one hour or one day, or if the monitoring target is a rolling bearing that supports a shaft that is used relatively softly, such as a shaft that rotates relatively slowly, the acquisition interval is set to a relatively long time length, such as one month or six months. The start timing of the sampling period is represented, for example, by a serial number from the start of acquisition of the vibration data, the time of the start timing, etc.

[0039] When storing the frequency spectrum in the storage unit 6, the peak detection unit 23 executes a peak detection process to detect, from the frequency spectrum, a specific peak that does not appear when the rolling bearing is normal, within a predetermined first frequency range that includes a theoretical frequency that will produce a peak on the frequency spectrum when an abnormality occurs. When the peak detection unit 23 detects a specific peak, it stores in the storage unit 6 the sampling period, amplitude, and frequency of the detected specific peak.

[0040] The theoretical frequency ft, which produces a peak on the frequency spectrum when an abnormality occurs, is publicly known and varies depending on the location of the rolling bearing damage (bearing damage), as shown in Table 1 below, for example. The locations of the bearing damage include, for example, the inner ring, outer ring, rolling elements, and cage. Here, fti is the theoretical frequency when bearing damage occurs on the inner ring, fto is the theoretical frequency when bearing damage occurs on the outer ring, ftb is the theoretical frequency when bearing damage occurs on the rolling elements, and ftm is the theoretical frequency when bearing damage occurs on the cage. d is the diameter of the rolling element, D is the pitch circle diameter of the rolling element, Z is the number of rolling elements, and α is the contact angle.

[0041] [Table 1]

[0042] When a normal rolling bearing (e.g., an unused rolling bearing) experiences some kind of obstacle that prevents smooth rolling, the frequency of a peak that appears on the frequency spectrum does not actually coincide with the theoretical frequency due to factors such as the rolling bearing's dimensional tolerances and deformation due to load. Therefore, in order to search for unknown peaks that appear on the frequency spectrum, a predetermined first frequency range including the theoretical frequency ft is appropriately set in advance. For example, as shown in FIG. 4A, the first frequency range FW1 is set so that the theoretical frequency ft is its central frequency (ft - Δfw1 ≦ FW1 ≦ ft + Δfw1, where Δfw1 is, for example, approximately 1 to 5% of ft).

[0043] In detecting a specific peak (a peak that appears due to the fault) that does not appear when the rolling bearing is normal, for example, if a peak is detected in a first frequency range FW1 and a peak (a harmonic) also exists at a frequency that is an integer multiple of the frequency of the detected peak (for example, twice the frequency or three times the frequency), the detected peak is determined to be a specific peak and it is determined that the specific peak has been detected. If no peak exists at a frequency that is an integer multiple of the frequency of the detected peak, it is determined that the detected peak is not a specific peak and it is determined that the specific peak has not been detected. For example, in Figure 4A, peaks PK1 and PK2 are detected in the first frequency range FW1, and no peaks exist at integer multiples of the frequency fp1 of peak PK1 that are characteristic of bearing damage vibration, while peaks exist at integer multiples of the frequency fp2 of peak PK2. In this case, peak PK1 is determined not to be a specific peak, while peak PK2 is determined to be a specific peak and it is determined that the specific peak has been detected. In this embodiment, multiple first to third vibration detection sensors 1-1 to 1-3 are used, and therefore, when a specific peak is determined at a common frequency in the frequency spectra of two or more of the first to third vibration detection sensors 1-1 to 1-3, it is ultimately determined that the specific peak has been found.

[0044] When a specific peak is detected by the peak detection unit 23, the peak re-detection unit 24 executes a peak re-detection process to detect, as a re-detected specific peak, a specific peak that does not appear under normal conditions and that includes the frequency of the specific peak detected by the peak detection unit 23 and is within a predetermined second frequency range FW2 narrower than the first frequency range FW1, for one or more frequency spectra stored in the storage unit 6 before the sampling period when the specific peak is detected. The peak re-detection unit 24 stores the sampling period, amplitude, and frequency of the re-detected specific peak in the storage unit 6.

[0045] Typically, a specific peak can be detected only after some kind of obstacle that hinders smooth rolling occurs in a rolling bearing in a normal state and the obstacle progresses, causing the peak amplitude to increase. Therefore, a specific peak may have existed even before the sampling period in which the specific peak was first detected. The peak re-detection unit 24 detects the specific peak that occurred before the sampling period in which the specific peak was first detected as a re-detected specific peak. For this reason, the peak re-detection unit 24 may detect the specific peak as a re-detected specific peak for one frequency spectrum stored in the storage unit 6 before the sampling period of the frequency spectrum in which the specific peak was detected by the peak detection unit 23, or may detect the specific peak as a re-detected specific peak for some frequency spectrums (a plurality of frequency spectrums less than all) of all frequency spectrums stored in the storage unit 6 before the sampling period, or may detect the specific peak as a re-detected specific peak for all frequency spectrums stored in the storage unit 6 before the sampling period. When detecting the specific peak as a re-detected specific peak for a plurality of frequency spectra, the peak re-detection unit 24 may, for example, detect the re-detected specific peak consecutively in the past direction for the plurality of frequency spectra, or may, for example, detect the re-detected specific peak non-consecutively in the past direction for the plurality of frequency spectra. In this embodiment, the peak re-detection unit 24 consecutively extracts a predetermined number of frequency spectra corresponding to a predetermined number of sampling periods before the sampling period and stored in the storage unit 6, and detects the re-detected specific peak consecutively in the past direction for the extracted predetermined number of frequency spectra.

[0046] As described above, a specific peak can usually be identified only after the fault progresses and the amplitude of the peak increases. Therefore, before the specific peak is detected by the peak search unit 23, the frequency of the specific peak is unknown, and therefore the first frequency range FW1 must be set relatively wide. Meanwhile, the specific peak before identification is presumed to occur around the identified frequency. Therefore, a predetermined second frequency range that includes the frequency of the specific peak and is narrower than the first frequency range FW1 is appropriately set in advance. For example, as shown in FIG. 4B, the second frequency range FW2 is set so that the frequency fp2 of the specific peak PK2 is its central frequency (fp2 - Δfw2 ≦ FW2 ≦ fp2 + Δfw2, where Δfw2 is, for example, approximately 0.1 to 0.5% of the theoretical frequency ft).

[0047] In the detection of the re-detected specific peak, the peak having the maximum amplitude in the second frequency range FW2 and having peaks at integer multiples of that frequency is determined as the re-detected specific peak. For example, in FIG. 4B, peak PK2' having the maximum amplitude in the second frequency range FW2 and having peaks at integer multiples of that frequency is determined as the re-detected specific peak.

[0048] The second frequency range FW2 may be the same when searching for a redetected specific peak from each of a plurality of frequency spectra. However, in this embodiment, when detecting the redetected specific peak in the past direction for the plurality of frequency spectra, the peak redetector 24 regards the peak detection process and the specific peak detected in the peak detection process as the first peak redetection process and the first redetected specific peak, respectively, for each of the plurality of frequency spectra, and detects the redetected specific peak in the second frequency range FW2 that includes the redetected specific peak detected in the previous peak redetection process for that frequency spectrum. For example, the redetected specific peak can be detected even if there is a shift in the frequency of the redetected specific peak due to wear, etc.

[0049] When a specific peak is detected in the peak detection process, the peak detection continuation unit 25 executes peak detection continuation process for each sampling period after the sampling period when the specific peak is detected, to detect, as a post-detection specific peak, a specific peak that includes the frequency of the specific peak and does not appear when the rolling bearing is normal, within a predetermined second frequency range FW2 narrower than the first frequency range FW1, for the frequency spectrum stored in the storage unit 6 at that acquisition timing. The peak detection continuation unit 25 stores the sampling period, amplitude, and frequency of the detected post-detection specific peak in the storage unit 6.

[0050] In detecting the post-detection specific peak, similarly to the detection of the specific peak, if a peak is detected in the second frequency range FW2 and a peak also exists at an integer multiple frequency, the peak may be determined to be the post-detection specific peak, or the peak with the largest amplitude within the second frequency range FW2 may be determined to be the post-detection specific peak.

[0051] The second frequency range FW2 may be the same when detecting a post-detection specific peak for each sampling period after the sampling period in which the specific peak was detected, but in this embodiment, the peak detection continuation unit 25 regards the peak detection process and the specific peak detected in the peak detection process as the first peak detection continuation process and the first post-detection specific peak, respectively, and detects the post-detection specific peak in the second frequency range that includes the post-detection specific peak detected in the peak detection continuation process immediately before the sampling period in question, for the frequency spectrum stored in the storage unit 6 for the sampling period in question. For example, the post-detection specific peak can be detected even if there is a shift in the frequency of the post-detection specific peak due to wear, etc.

[0052] The display processing unit 26 executes a display process for displaying, on the display unit 4, time information about a sampling period when a specific peak is detected by the peak detection unit 23 and the amplitude of the detected specific peak, and time information about a sampling period when a re-detected specific peak is detected by the peak re-detection unit 24 and the amplitude of the re-detected specific peak. In this embodiment, the display process further displays, for each sampling period after the sampling period when the specific peak is detected, time information about the sampling period and the amplitude of the post-detection specific peak detected in the peak detection continuation process. More specifically, assuming that the acquisition interval is every other day, for example, display processing unit 26 displays on display unit 4 a Cartesian coordinate system with the horizontal axis representing the date, which is time information related to the sampling period, and the vertical axis representing the amplitude, and displays on display unit 4 a predetermined first mark at a first coordinate represented by the date when a specific peak was detected in the peak detection process and the amplitude of the detected specific peak, displays on display unit 4 a predetermined second mark at a second coordinate represented by the date when a re-detected specific peak was searched for in the peak re-detection process and the amplitude of the detected re-detected specific peak, and displays on display unit 4 a predetermined third mark at a third coordinate represented by the date when a post-detection specific peak was detected in the peak detection continuation process and the amplitude of the detected post-detection specific peak. The first mark, the second mark, and the third mark may be the same, different from each other, or may be partially the same.

[0053] When peak re-detection unit 24 detects one re-detected specific peak using one frequency spectrum, display processing unit 26 displays on display unit 4 the specific peak searched for by peak detection unit 23 and the one re-detected specific peak searched for by peak re-detection unit 24. When peak re-detection unit 24 detects multiple re-detected specific peaks using multiple frequency spectrums, display processing unit 26 displays on display unit 4 the specific peak detected by peak detection unit 23 and the multiple re-detected specific peaks detected by peak re-detection unit 24. During the sampling period after peak detection unit 23 detects a specific peak for the first time, display processing unit 26 displays on display unit 4 the specific peak detected for the first time, one or more re-detected specific peaks, and post-detection peaks detected after the specific peak detected for the first time.

[0054] For example, the display processing unit 26 displays a display screen shown in Fig. 5 on the display unit 4. Fig. 5A shows the case of a first example of mechanical equipment, and Fig. 5B shows the case of a second example of mechanical equipment.

[0055] In FIG. 5A, the date for this sampling period is the timing TD +1 And this timing TD +1 In this example, a specific peak is detected for the first time at the timing TD0 immediately before the timing TD1. In the peak re-detection process, four frequency spectra are extracted and detected going back in time.

[0056] In the example shown in FIG. 5A, the peak re-detection unit 24 detects the timing TD immediately before the timing TD0. -1 For the frequency spectrum of the signal, a re-detection process is performed within a second frequency range FW2 including a specific peak, for example, indicated by a black circle, detected by the peak detection unit 23. At timing TD -1 Then, the peak re-detection unit 24 detects the specific peak at the timing TD -1 The timing before TD -2 For the frequency spectrum of -1The redetection process is performed within the second frequency range FW2 including the redetection specific peak x at the timing TD -2 Then, the peak re-detection unit 24 detects the specific peak at the timing TD -2 The timing before TD -3 For the frequency spectrum of -2 In the example shown in FIG. 5A, the redetection process is performed within a second frequency range FW2 including the redetection specific peak x at timing TD -3 Then, the peak re-detection unit 24 detects a peak at the timing TD -3 The timing before TD -4 For the frequency spectrum of -3 In the example shown in FIG. 5A, the redetection process is performed within a second frequency range FW2 including the redetection specific peak x at timing TD -4 No peak is detected from the frequency spectrum at timing TD0. +1 When this occurs, the peak detection continuation unit 25 detects the timing TD +1 For the frequency spectrum of the timing TD0, within the second frequency range FW2 including the specific peak ● at the timing TD +1 Peak detection continuation processing is performed at timing TD, for example, indicated by an x. +1 5A, the display processing unit 26 displays an orthogonal coordinate system on the display unit 4, with the horizontal axis representing the date related to the sampling period and the vertical axis representing the amplitude, and displays a first mark ● on the display unit 4 at the coordinates of the timing TD0 and the amplitude of the specific peak. -1 and the coordinates and timing of the amplitude of the specific peaks detected by the re-detection TD -2 The second marks x are displayed on the display unit 4 at the coordinates of the amplitudes of the re-detected specific peaks, and the timing TD +1After the detection, a third mark x is displayed on the display unit 4 at the coordinate of the amplitude of the specific peak. In the example shown in Fig. 5A, the second and third marks are the same mark x, and the first mark is a mark ● that is different from the second and third marks.

[0057] In the example shown in FIG. 5A, the display processing unit 26 determines a fitting curve α that best fits the date and amplitude related to the sampling period of the specific peak, the date and amplitude related to the sampling period of the redetected specific peak, and the date and amplitude related to the sampling period of the post-detection specific peak in a coordinate space with time and amplitude as the coordinate axes, and displays the determined fitting curve α on the display unit 4.

[0058] In Figure 5B, the timing this time is timing TD +3 And this timing TD +3 An example is shown in which a specific peak is first detected at timing TD0, three times before the timing TD0.

[0059] In the example shown in FIG. 5B, the peak re-detector 24 detects the timing TD immediately before the timing TD0. -1 For the frequency spectrum of the signal, a re-detection process is performed within a second frequency range FW2 including a specific peak, for example, indicated by a ●, detected by the peak detection unit 23. -1 Then, the peak re-detection unit 24 detects the specific peak at the timing TD -1 The timing before TD -2 For the frequency spectrum of -1 The redetection process is performed within the second frequency range FW2 including the redetection specific peak ○ at the timing TD -2 Then, the peak re-detection unit 24 detects the specific peak at the timing TD -2 The timing before TD -3 For the frequency spectrum of -2The redetection process is performed within the second frequency range FW2 including the redetection specific peak ○ at the timing TD -3 Then, the peak re-detection unit 24 detects the specific peak at the timing TD -3 The timing before TD -4 For the frequency spectrum of -3 The redetection process is performed within the second frequency range FW2 including the redetection specific peak ○ at the timing TD -4 A specific peak is detected at the timing TD0. +1 When this occurs, the peak detection continuation unit 25 detects the timing TD +1 For the frequency spectrum of the timing TD0, within the second frequency range FW2 including the specific peak ● at the timing TD +1 Peak detection continuation processing is performed at timing TD, for example, as indicated by a circle. +1 After the detection at TD, a specific peak is detected. +2 When this occurs, the peak detection continuation unit 25 detects the timing TD +2 For the frequency spectrum of +1 After detection at the specific peak ○, the timing TD is detected within the second frequency range FW2 including the specific peak ○. +2 Peak detection continuation processing is performed at timing TD, for example, as indicated by a circle. +2 After the detection at TD, a specific peak is detected. +3 When this occurs, the peak detection continuation unit 25 detects the timing TD +3 For the frequency spectrum of +2 After detection at the specific peak ○, the timing TD is detected within the second frequency range FW2 including the specific peak ○. +3 Peak detection continuation processing is performed at timing TD, for example, as indicated by a circle. +3 5B, the display processing unit 26 displays an orthogonal coordinate system on the display unit 4, with the horizontal axis representing the date related to the sampling period and the vertical axis representing the amplitude, and displays a first mark ● on the display unit 4 at the coordinates of the timing TD0 and the amplitude of the specific peak.-1 ~TD -4 At each coordinate of each amplitude of each of the re-detected specific peaks, each second mark ○ is displayed on the display unit 4, and each timing TD +1 ~TD +3 At each coordinate of each amplitude of each of the detected specific peaks, a third mark ○ is displayed on the display unit 4. In the example shown in FIG. 5B, the second and third marks are the same mark ○, and the first mark is a mark ● that is different from the second and third marks.

[0060] In the example shown in FIG. 5B, the display processing unit 26 determines a fitting curve β that best fits the date and amplitude related to the sampling period of the specific peak, the date and amplitude related to the sampling period of the redetected specific peak, and the date and amplitude related to the sampling period of the post-detection specific peak in a coordinate space with time and amplitude as the coordinate axes, and displays the determined fitting curve β on the display unit 4.

[0061] The control processing unit 2, input unit 3, display unit 4, IF unit 5 and storage unit 6 can be configured by, for example, a desktop or notebook computer.

[0062] Next, the operation of this embodiment will be described. Fig. 6 is a flowchart showing the operation of the rolling bearing monitoring device before the specific peak is detected. Fig. 7 is a flowchart showing the operation of the rolling bearing monitoring device after the specific peak is detected.

[0063] When the rolling bearing monitoring device 1000 configured as described above is powered on, it initializes the necessary parts and starts operation. By executing the control processing program, the control processing unit 2 is functionally configured to include a control unit 21, a spectrum processing unit 22, a peak detection unit 23, a peak re-detection unit 24, a peak detection continuation unit 25, and a display processing unit 26.

[0064] When the operation starts and the timing for starting the sampling period arrives, in Figure 6, the rolling bearing monitoring device 1000 first uses the spectrum processing unit 22 of the control processing unit 2 to obtain from the memory unit 6 vibration data for a sampling period equivalent to the length TW of the predetermined sampling period obtained by the first to third vibration detection sensors 1-1 to 1-3, calculates the frequency spectrum of the vibration data (S11), and stores this calculated frequency spectrum in the memory unit 6 in association with the current sampling period (S12).

[0065] Next, the rolling bearing monitoring device 1000 detects a specific peak within a predetermined first frequency range including the theoretical frequency from the frequency spectrum for the current sampling period using the peak detection unit 23 of the control processing unit 2 (S13). If this detection results in no specific peak being detected (NO (none)), the rolling bearing monitoring device 1000 ends this processing for the current sampling period. On the other hand, if the detection results in a specific peak being detected (YES (present)), the rolling bearing monitoring device 1000 then executes processing S14.

[0066] In this step S14, the rolling bearing monitoring device 1000 causes the peak detection unit 23 of the control processing unit 2 to store the detected specific peak (its sampling period, amplitude and frequency) in the storage unit 6.

[0067] Next, the rolling bearing monitoring device 1000 detects the specific peak as a re-detected specific peak using the peak re-detection unit 24 of the control processing unit 2, and stores this detected re-detected specific peak (its sampling period, amplitude and frequency) in the memory unit 6 (S15).

[0068] Then, the rolling bearing monitoring device 1000 causes the display processing unit 26 of the control processing unit 2 to display the specific peak and the re-detected specific peak on the display unit 4 (S16), and ends this processing for the current sampling period. Note that the detection results may be output to an external device via the IF unit 5, as necessary.

[0069] On the other hand, when the sampling period begins after the specific peak has been detected, in FIG. 7, the rolling bearing monitoring device 1000 first uses the spectrum processing unit 22 of the control processing unit 2 to determine the frequency spectrum of the vibration data for the current sampling period (S21), as in the above-mentioned process S11, and then stores this determined frequency spectrum in the memory unit 6 in association with the current sampling period (S22), as in the above-mentioned process S12.

[0070] Next, the rolling bearing monitoring device 1000 detects a post-detection specific peak during the current sampling period using the peak detection continuation unit 25 of the control processing unit 2, and stores this detected post-detection specific peak (its sampling period, amplitude and frequency) in the memory unit 6 (S23).

[0071] Then, the rolling bearing monitoring device 1000 causes the display processing unit 26 of the control processing unit 2 to display on the display unit 4 the specific peaks that have been detected so far, the re-detected specific peaks, and the post-detection specific peaks (S24), and ends this processing for the current sampling period.

[0072] Typically, when a rolling bearing BE in a normal state experiences some kind of fault that impairs smooth rolling, the fault progresses and the peak amplitude increases, after which the peak can be identified and its frequency can be determined. Meanwhile, peaks before identification are presumably occurring around the identified frequency. As described above, the rolling bearing monitoring device 1000 and the rolling bearing monitoring method implemented therein in the embodiment detect specific peaks in a first frequency range FW1 that includes the theoretical frequency, thereby enabling more reliable detection of the specific peak. Furthermore, the rolling bearing monitoring device 1000 redetects the specific peak by narrowing the search to a second frequency range FW2 that is narrower than the first frequency range FW1. This eliminates from the search target any confusing peaks that are included in the first frequency range but are not attributable to the fault, enabling more accurate searching for the specific peak attributable to the fault. Furthermore, the display unit displays the amplitude values ​​of peaks occurring due to a fault in the rolling bearing prior to the point at which the peak became detectable, allowing the user to grasp the trends in past peak amplitudes.

[0073] The rolling bearing monitoring device 1000 and the rolling bearing monitoring method detect the redetected specific peak in the second frequency range FW2, which includes the redetected specific peak detected in the previous peak redetection process, and therefore can more reliably detect the redetected specific peak even if the frequency of the redetected specific peak changes over time.

[0074] The rolling bearing monitoring device 1000 and the rolling bearing monitoring method perform peak detection continuation processing, so that a specific peak can be detected for each sampling period after the sampling period in which a specific peak is detected in the peak detection processing, and detection of the specific peak can be continued.

[0075] The rolling bearing monitoring device 1000 and the rolling bearing monitoring method detect the post-detection specific peak in the second frequency range FW2, which includes the post-detection specific peak searched for in the previous peak detection continuation process, and therefore can more reliably detect the post-detection specific peak even if the frequency of the post-detection specific peak changes over time.

[0076] The rolling bearing monitoring device 1000 and rolling bearing monitoring method display, in an orthogonal coordinate system, time information relating to the sampling period when a specific peak is detected in the peak detection process and the amplitude of the detected specific peak, time information relating to the sampling period when a re-detected specific peak is detected in the peak re-detection process and the amplitude of the detected re-detected specific peak, and time information relating to the sampling period when a post-detection specific peak is detected in the peak detection continuation process and the amplitude of the detected post-detection specific peak, so that the user (operator) can visually recognize the changes over time among the re-detected specific peak, the specific peak, and the post-detection specific peak, and can visually recognize the progression of the fault (tendency of change over time, trend).

[0077] The remaining lifespan, which is the time until the rolling bearing needs to be replaced after a specific peak is detected ((time information related to the sampling period in the frequency spectrum (vibration data) in which the specific peak was detected) + (remaining lifespan at that time) = (replacement time)), depends on the progression of the failure. By referring to the display of the first mark ●, the second mark ×, and the third mark ×, the user can see that, for example, in the example shown in Figure 5A, the progression of the failure is relatively faster than in the example shown in Figure 5B, and that the remaining lifespan (remaining lifespan) from timing TD0 is relatively short. In particular, by referring to the display of the fitting curve α, it is easy to predict the remaining lifespan. Predicting the remaining lifespan makes it possible to more accurately plan maintenance for the monitored object, making equipment maintenance easier.

[0078] Furthermore, by referring to the oldest redetected specific peak, the user can estimate the time when the fault will occur. In particular, by referring to the display of the fitting curve α, the user can easily find the time when the fitting curve α rises (=the time when the fault will occur), and can easily estimate the time when the fault will occur.

[0079] In the above-described embodiment, a data logger 7 may be provided between the vibration detection sensor 1 and the control processing unit 2, and the spectrum processing unit 22 may be provided in this data logger 7.

[0080] Figure 8 is a block diagram showing the configuration of a rolling bearing monitoring device according to a modified example of the embodiment. A rolling bearing monitoring device 1000a according to this modified example includes, for example, a vibration detection sensor 1, a data logger 7, a control processing unit 2, an input unit 3, an output unit 4, an IF unit 5, and a storage unit 6, as shown in Figure 8.

[0081] The vibration detection sensor 1, control processing unit 2, input unit 3, output unit 4, IF unit 5 and memory unit 6 in the rolling bearing monitoring device 1000a are similar to the vibration detection sensor 1, control processing unit 2, input unit 3, output unit 4, IF unit 5 and memory unit 6 in the rolling bearing monitoring device 1000, except that some functions of the control processing unit 2 and some functions of the memory unit 6 have been moved to the data logger 7, and therefore their description will be omitted. The control processing unit 2 functionally comprises a control unit 21, a peak detection unit 23, a peak re-detection unit 24, a peak detection continuation unit 25 and a display processing unit 26, and the spectrum processing function has been moved to the data logger 7. The function of storing vibration data and its frequency spectrum has been moved to the data logger 7.

[0082] The data logger 7 is connected to both the vibration detection sensor 1 and the control processing unit 2, and is configured with, for example, a computer, and includes a data logger control processing unit 71 and a data logger storage unit 72. The data logger control processing unit 71 is configured with a CPU and its peripheral circuits, and functionally includes a spectrum processing unit 22 that functions similarly to the above, except that data is stored in the data logger storage unit 72 instead of the storage unit 6. The data logger storage unit 72 includes a ROM, EEPROM, RAM, a hard disk drive, etc., and stores the vibration data and frequency spectrum. The data logger 7 outputs the frequency spectrum of the vibration data to the control processing unit 2 in response to a request from the control processing unit 2.

[0083] In order to express the present invention, the present invention has been properly and sufficiently described above through the embodiments with reference to the drawings, but it should be recognized that those skilled in the art can easily change and / or improve the above-mentioned embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that causes departure from the scope of the claims described in the claims, such changes or improvements are interpreted as being included in the scope of the claims. [Explanation of symbols]

[0084] BE (BE-1 to BE-3) Rolling bearings (1st to 3rd rolling bearings) FW1 First frequency range FW2 Second frequency range 1000 Rolling bearing monitoring device 1 (1-1 to 1-3) Vibration detection sensor (first to third vibration detection sensor) 2. Control processing section 4 Display section 6 Memory section 7 Data Logger 21 Control Unit 22 Spectral Processing Section 23 Peak Search Section 24 Peak re-search section 25 Peak Search Continuation 26 Display processing section

Claims

1. a spectrum processing step of acquiring vibration data representing vibrations occurring in the rolling bearing at predetermined acquisition intervals for a predetermined sampling period, determining a frequency spectrum of the vibration data for the sampling period, and storing the determined frequency spectrum in a storage unit in association with the sampling period; a peak detection step of detecting, from the frequency spectrum, a specific peak that does not appear when the rolling bearing is normal, within a predetermined first frequency range that includes a theoretical frequency that causes a peak on the frequency spectrum when an abnormality occurs; a peak re-detection step of, when a specific peak is detected in the peak detection step, re-detecting a specific peak that does not appear when the rolling bearing is normal, within a predetermined second frequency range narrower than the first frequency range and that includes the frequency of the specific peak detected in the peak detection step, for one or more frequency spectra stored in the storage unit prior to the sampling period when the specific peak is detected; a display step of displaying, on a display unit, time information relating to a sampling period when a specific peak is detected in the peak detection step and the amplitude of the detected specific peak, and time information relating to a sampling period when a re-detected specific peak is detected in the peak re-detection step and the amplitude of the re-detected specific peak. Rolling bearing monitoring method.

2. In the peak re-detection step, when the re-detected specific peak is detected in a past direction for the plurality of frequency spectra, the peak detection step and the specific peak detected in the peak detection step are regarded as the first peak re-detection step and the first re-detected specific peak, respectively, for each of the plurality of frequency spectra, and the re-detected specific peak is detected in the second frequency range including the re-detected specific peak detected in the previous peak re-detection step for the frequency spectrum.

2. The rolling bearing monitoring method according to claim 1.

3. The display step displays, on the display unit, a Cartesian coordinate system with the horizontal axis representing time information related to the sampling period and the vertical axis representing the amplitude, and displays, on the display unit, a predetermined first mark at a first coordinate represented by the time information related to the sampling period when a specific peak is detected in the peak detection step and the amplitude of the detected specific peak, and displays, on the display unit, a predetermined second mark at a second coordinate represented by the time information related to the sampling period when a re-detected specific peak is detected in the peak re-detection step and the amplitude of the re-detected specific peak.

2. The rolling bearing monitoring method according to claim 1.

4. Further, a peak detection continuing step is provided, the peak detection continuing step is a process in which, when a specific peak is detected in the peak detection process, for each sampling period after the sampling period in which the specific peak was detected, a specific peak that does not appear when the rolling bearing is normal is detected as a detected specific peak within a predetermined second frequency range that includes the frequency of the specific peak and is narrower than the first frequency range, for the frequency spectrum stored in the storage unit for that sampling period; The display step further includes displaying, on the display unit, the amplitude of the post-detection specific peak detected in the sampling period and the peak detection continuing step for each sampling period after the sampling period when the specific peak is detected.

2. The rolling bearing monitoring method according to claim 1.

5. the peak detection continuing step regards the peak detection step and the specific peak detected in the peak detection step as a first peak detection continuing step and a first post-detection specific peak, respectively, and detects the post-detection specific peak in the second frequency range including the post-detection specific peak detected in the peak detection continuing step immediately before the sampling period, for the frequency spectrum stored in the storage unit in the sampling period; 5. The rolling bearing monitoring method according to claim 4.

6. The displaying step is a process of displaying on the display unit a Cartesian coordinate system with the horizontal axis representing time information related to the sampling period and the vertical axis representing the amplitude, displaying on the display unit a predetermined first mark at a first coordinate represented by time information related to the sampling period when a specific peak is detected in the peak detecting step and the amplitude of the detected specific peak, displaying on the display unit a predetermined second mark at a second coordinate represented by time information related to the sampling period when a re-detected specific peak is detected in the peak re-detecting step and the amplitude of the detected re-detected specific peak, and displaying on the display unit a predetermined third mark at a third coordinate represented by time information related to the sampling period when a post-detection specific peak is detected in the peak detection continuing step and the amplitude of the detected post-detection specific peak.

6. The rolling bearing monitoring method according to claim 4 or 5.

7. a length of the sampling period is set based on the second frequency range; The narrower the second frequency range, the longer the sampling period is set.

2. The rolling bearing monitoring method according to claim 1.

8. a vibration detection sensor that acquires vibration data representing vibrations occurring in the rolling bearing; A memory unit; a control processing unit that performs spectrum processing, peak detection processing, peak re-detection processing, and display processing; a display unit, the spectrum processing is a process of acquiring vibration data for a predetermined sampling period at predetermined acquisition intervals, determining a frequency spectrum of the vibration data for the sampling period, and storing the determined frequency spectrum in a storage unit in association with the sampling period; the peak detection process is a process of detecting, from the frequency spectrum, a specific peak that does not appear when the rolling bearing is normal, within a predetermined first frequency range that includes a theoretical frequency that causes a peak on the frequency spectrum when an abnormality occurs, the peak re-detection process is a process for detecting, when a specific peak is detected in the peak detection process, a specific peak that does not appear when the rolling bearing is normal, as a re-detected specific peak, within a predetermined second frequency range narrower than the first frequency range and including the frequency of the specific peak detected in the peak detection process, for one or more frequency spectra stored in the storage unit prior to the sampling period when the specific peak is detected; the display processing is processing for displaying, on the display unit, time information regarding a sampling period when a specific peak is detected in the peak detection processing and the amplitude of the detected specific peak, and time information regarding a sampling period when a re-detected specific peak is detected in the peak re-detection processing and the amplitude of the re-detected specific peak. Rolling bearing monitoring device.

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