Oil film thickness measurement method in contact area based on rolling bearing vibration correction and compensation

Abstract

A method for measuring the oil film thickness in the contact area based on vibration correction and compensation of rolling bearings belongs to the technical field of lubricating oil film thickness measurement. The present invention addresses the problem that the vibration during the operation of rolling bearings affects the amplitude and phase of the film thickness measurement signal, thereby affecting the accuracy of film thickness measurement. It includes obtaining the ultrasonic pulse signal initially emitted by the transducer and the ultrasonic pulse signal emitted after the vibration offset and performing Fourier transform to obtain the amplitude and phase of the pulse signal before and after the offset of the outer ring-water interface of the rolling bearing and the amplitude and phase of the pulse signal after the offset of the outer ring-oil film interface of the rolling bearing; using the amplitude change and phase change of the outer ring-water interface of the rolling bearing to compensate for the amplitude and phase of the pulse signal after the offset of the outer ring-oil film interface of the rolling bearing to obtain the amplitude correction value and phase correction value; then calculating the effective reflection coefficient amplitude, and then calculating the oil film thickness at the center of the target oil film contact area. The present invention is used for oil film thickness measurement.

Description

Technical Field

[0001] The invention relates to a contact area oil film thickness measurement method based on rolling bearing vibration correction and compensation, and belongs to the technical field of lubricating oil film thickness measurement. Background Art

[0002] As an indispensable component in mechanical systems, rolling bearings play a key role in supporting rotating bodies, reducing friction and wear, and improving system efficiency. Their importance is reflected in many aspects, especially in modern high-speed, high-precision, and heavy-load mechanical equipment. In rolling bearings, oil film thickness, a key parameter that directly reflects the lubrication status of the bearing contact area, requires measurement.

[0003] Bearing vibration is a common phenomenon during the operation of rolling bearings. Its main causes include uneven oil film thickness, changes in lubricant viscosity, and imbalances in the bearing's internal structure. Under high-speed rotation, bearing vibration generates additional load and heat inside the bearing, which in turn affects the bearing's stability and lifespan. It also causes noise and vibration during operation, affecting the overall performance of the machine.

[0004] Currently, oil film thickness measurement mainly includes electrical, optical and ultrasonic methods. Among them, the ultrasonic method has lower environmental requirements and can work normally in harsh environments such as high temperature, high pressure, and high humidity; while the electrical and optical methods may be interfered by environmental factors; the details are as follows:

[0005] 1) The ultrasonic method is a non-contact measurement method that can perform measurements without disturbing the operating status of the bearing, while the electrical and optical methods may require direct contact with the oil film, affecting the accuracy of the measurement results; 2) The ultrasonic method can provide high-precision measurement results and is very sensitive to small changes in oil film thickness, which helps to promptly detect problems in bearing operation; 3) The ultrasonic method can realize real-time monitoring of oil film thickness and provide instant feedback on the operating status of the bearing, while the electrical and optical methods require a longer time for data processing and analysis; 4) The ultrasonic method has strong resistance to electromagnetic interference and optical interference, which makes it more reliable in complex electromagnetic and optical environments.

[0006] During the operation of the bearing, vibration may occur due to various reasons. The vibration causes the amplitude and phase of the signals of the coupling agent layer and the oil film layer to change, resulting in large errors in the film thickness measurement of the oil film contact area, which will seriously affect the accuracy and reliability of ultrasonic testing. Summary of the Invention

[0007] In order to solve the problem that the vibration during the operation of rolling bearings affects the amplitude and phase of the film thickness measurement signal, thereby affecting the accuracy of film thickness measurement, the present invention provides a contact area oil film thickness measurement method based on rolling bearing vibration correction and compensation.

[0008] The present invention provides a method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation, comprising:

[0009] Assume that the transmitting ultrasonic pulse signal and the receiving ultrasonic pulse signal of the transducer are affected by the same vibration offset;

[0010] Obtain the initial ultrasonic pulse signal of the transducer and the ultrasonic pulse signal after vibration offset, and perform Fourier transform to obtain the pulse signal amplitude A before offset of the rolling bearing outer ring-water interface. w1 and phase α1, pulse signal amplitude A after offset w2 The pulse signal amplitude A after the phase α2 and the offset of the rolling bearing outer ring-oil film interface s2 and phase ψ2; the pulse signal amplitude before the offset of the rolling bearing outer ring-water interface is A w1 and the amplitude of the pulse signal after the shift A w2 The change in the amount of the pulse signal amplitude A after the offset of the rolling bearing outer ring-oil film interface s2 Perform compensation correction to obtain the offset pulse signal amplitude correction value A of the rolling bearing outer ring-oil film interface s20 At the same time, the variation of the phase α1 of the pulse signal before the offset and the phase α2 of the pulse signal after the offset of the rolling bearing outer ring-water interface is used to compensate and correct the offset pulse signal ψ2 of the rolling bearing outer ring-oil film interface, and the offset pulse signal phase correction value ψ of the rolling bearing outer ring-oil film interface is obtained. 20 ;

[0011] The amplitude correction value A of the offset pulse signal based on the rolling bearing outer ring-oil film interface s20 and the phase correction value of the pulse signal after the shift ψ 20 The effective reflection coefficient amplitude is calculated, and then the oil film thickness at the center of the target oil film contact area is calculated based on the effective reflection coefficient amplitude.

[0012] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, the initial transmitted ultrasonic pulse signal of the transducer includes the initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface; wherein t represents time;

[0013] The ultrasonic pulse signal emitted after the vibration offset of the transducer includes the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface and the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface.

[0014] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, the initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface is Fourier transformed to obtain the pre-offset pulse signal amplitude A of the rolling bearing outer ring-water interface. w1 and phase α1; Fourier transform the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface to obtain the offset pulse signal amplitude A of the rolling bearing outer ring-water interface w2 and phase α2;

[0015] Perform Fourier transform on the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface to obtain the offset pulse signal amplitude signal A of the rolling bearing outer ring-oil film interface. s2 and phase ψ2.

[0016] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, the pre-offset pulse signal amplitude A of the rolling bearing outer ring-water interface is w1 and the amplitude of the pulse signal after the shift A w2 The change in is expressed as ΔA:

[0017] ΔA=A w2 / A w1 ;

[0018] The amplitude correction value of the offset pulse signal at the rolling bearing outer ring-oil film interface is A s20 :

[0019] A s20 =A s2 / ΔA;

[0020] The change in the phase α1 of the pulse signal before the offset and the phase α2 of the pulse signal after the offset at the rolling bearing outer ring-water interface is expressed as Δα:

[0021] Δα=α2-α1;

[0022] The phase correction value of the offset pulse signal of the rolling bearing outer ring-oil film interface ψ 20 for:

[0023] ψ 20 =ψ2-Δα.

[0024] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, the effective reflection coefficient amplitude is expressed as |R(f c )|:

[0025]

[0026] Where fc is the center frequency of the transducer ultrasonic probe, A ref is the mean amplitude of the non-rolling element area of ​​the rolling bearing, ψ ref is the phase mean value of the non-rolling element area of ​​the rolling bearing, and r is the reflection coefficient of the ultrasonic incident signal incident on the outer ring-oil film interface of the rolling bearing.

[0027] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, the calculation method of the oil film thickness at the center of the target oil film contact area is:

[0028]

[0029] Where h center is the oil film thickness at the center of the target oil film contact area, ρ o is the density of lubricating oil, c o is the longitudinal sound velocity of the lubricating oil, ρ s is the density of the outer ring of the rolling bearing, c s is the longitudinal sound velocity of the outer ring of the rolling bearing.

[0030] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, the initial ultrasonic pulse signal and the ultrasonic pulse signal emitted after vibration offset are collected by a signal acquisition module; the signal acquisition module continuously collects signals based on a while loop frame.

[0031] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, the signal collected by the signal acquisition module is divided into the initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface, the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface and the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface through a rectangular window function.

[0032] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, the process of obtaining the offset pulse signal amplitude correction value and the offset pulse signal phase correction value from the signal collected by the signal acquisition module is implemented by the data preprocessing module;

[0033] The signal acquisition module transmits the segmented signal to the original data storage module for data storage using the synchronous transmission technology queue in LabVIEW, and simultaneously transmits it to the data preprocessing module for data processing;

[0034] The raw data storage module and the data preprocessing module are distributed in two independent CPU threads.

[0035] According to the contact area oil film thickness measurement method based on rolling bearing vibration correction compensation of the present invention, a control module is set to adjust the signal transmission frequency of the transducer according to the rotation speed of the rolling bearing cage so that the ultrasonic pulse signal acts on the center of the target oil film contact area.

[0036] The present invention's beneficial effects: By compensating and correcting the phase and amplitude of the oil film reflection wave signal, the method obtains the ultrasonic reflection coefficient amplitude and calculates the oil film thickness at the center of the contact area. This allows for accurate measurement of rolling bearing oil film thickness under vibration conditions.

[0037] The method of the present invention is based on the equal influence of vibration on the outer ring-oil film interface reflection wave and the outer ring-water interface reflection wave, compensates for the phase and amplitude changes of the outer ring-oil film interface reflection wave, and comprehensively corrects the film thickness of the contact area of ​​the roller bearing. It can realize the in-situ measurement of the film thickness in the center of the contact area of ​​the high-speed roller bearing, thereby realizing more accurate real-time measurement of the oil film thickness in the center of the contact area. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of equivalent displacement of the transducer and the bearing caused by vibration in the contact area oil film thickness measurement method based on rolling bearing vibration correction and compensation according to the present invention;

[0039] Figure 2 This is a schematic diagram of the effect of bearing vibration on the ultrasonic test of oil film thickness;

[0040] Figure 3 is a flow chart of the method of the present invention;

[0041] Figure 4 It is a specific implementation algorithm flow chart of the method of the present invention. DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0043] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0044] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0045] Specific implementation method 1. Combination Figures 1 to 3 As shown, the present invention provides a method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction compensation, comprising:

[0046] Combine Figure 1 As shown in the figure, considering the rolling bearing's vibration, the transducer experiences a relative displacement and velocity relative to the outer ring-water interface, which causes corresponding changes in the phase and amplitude of the reflected wave signal from the oil film received by the transducer. The time from the transducer's ultrasonic wave acting on the oil film to its return from the oil film is very short, so the probe's position during signal reception and transmission can be roughly considered fixed. This means that the signal received or transmitted by the transducer can be roughly considered to be affected only by the vibration displacement.

[0047] When the bearing vibrates instantaneously, the outer ring is considered as a rigid body, and its thickness does not change. The displacement of the interface between the outer ring outer diameter and the coupling agent water relative to the non-vibration state is Δy. When the vibration position of the bearing outer ring is above the initial position, Δy is positive; when it is below the initial position, Δy is negative. Assume that the complex amplitudes of the reference signal and the oil film layer signal that are not affected by the vibration at the center frequency of the transducer are Y re 、Y oi , then the corresponding total reflection coefficient of the oil film layer R whole and the residual reflection coefficient R remain It can be expressed as:

[0048]

[0049] Where r represents the reflection coefficient of the steel-oil interface when the ultrasonic wave is incident from the steel to the oil.

[0050] When vibrating, the complex amplitude of the oil film signal received by the transducer at the center frequency of the transducer is Y oi_v :

[0051]

[0052] Where a is the coefficient related to absorption, and c is the propagation speed of ultrasound in the oil film.

[0053] The total reflection coefficient R is affected by vibration. wh_v and the residual reflection coefficient R rem_v becomes:

[0054]

[0055] Considering the small bearing vibration amplitude, in this case, it can be approximately assumed that the reflected wave at the outer ring-water interface and the reflected wave at the outer ring-oil film interface are affected by the vibration in the same way. That is, the phase and amplitude of the reflected wave at the outer ring-water interface change identically to those at the outer ring-oil film interface:

[0056]

[0057] Where α1, α2 are the ultrasonic phases before and after the reflected wave at the outer ring-water interface (rad);

[0058] ψ1, ψ2 – ultrasonic phase before and after the reflected wave at the outer ring-oil film interface (rad);

[0059] A w1 、A w2 ——The ultrasonic amplitude before and after the reflected wave at the outer ring-water interface vibrates;

[0060] A s1 、A s2 ——The ultrasonic amplitude before and after the reflected wave at the outer ring-oil film interface vibrates.

[0061] In this embodiment, it is assumed that the transmitted ultrasonic pulse signal and the received ultrasonic pulse signal of the transducer are affected by the same vibration offset;

[0062] Obtain the initial ultrasonic pulse signal of the transducer and the ultrasonic pulse signal after vibration offset, and perform Fourier transform to obtain the pulse signal amplitude A before offset of the rolling bearing outer ring-water interface. w1 and phase α1, pulse signal amplitude A after offset w2 The pulse signal amplitude A after the phase α2 and the offset of the rolling bearing outer ring-oil film interface s2 and phase ψ2; the pulse signal amplitude before the offset of the rolling bearing outer ring-water interface is A w1 and the amplitude of the pulse signal after the shift A w2 The change in the amount of the pulse signal amplitude A after the offset of the rolling bearing outer ring-oil film interface s2 Perform compensation correction to obtain the offset pulse signal amplitude correction value A of the rolling bearing outer ring-oil film interface s20 At the same time, the variation of the phase α1 of the pulse signal before the offset and the phase α2 of the pulse signal after the offset of the rolling bearing outer ring-water interface is used to compensate and correct the offset pulse signal ψ2 of the rolling bearing outer ring-oil film interface, and the offset pulse signal phase correction value ψ of the rolling bearing outer ring-oil film interface is obtained. 20 ;

[0063] The amplitude correction value A of the offset pulse signal based on the rolling bearing outer ring-oil film interface s20 and the phase correction value of the pulse signal after the shift ψ 20 The effective reflection coefficient amplitude is calculated, and then the oil film thickness at the center of the target oil film contact area is calculated based on the effective reflection coefficient amplitude.

[0064] Furthermore, the initial ultrasonic pulse signal transmitted by the transducer and the ultrasonic pulse signal transmitted after the vibration shift are segmented. The initial ultrasonic pulse signal transmitted by the transducer includes an initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface, where t represents time, and an initial position incident signal xoi_s1(t) of the rolling bearing outer ring-oil film interface.

[0065] The ultrasonic pulse signal emitted after the vibration offset of the transducer includes the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface and the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface.

[0066] Perform Fourier transform on the initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface to obtain the pre-offset pulse signal amplitude A of the rolling bearing outer ring-water interface. w1 , phase α1, perform Fourier transform on the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface, and obtain the offset pulse signal amplitude A of the rolling bearing outer ring-water interface w2 , phase α2;

[0067] Perform Fourier transform on the initial position incident signal xoi_s1(t) of the rolling bearing outer ring-oil film interface to obtain the pre-offset pulse signal amplitude A of the rolling bearing outer ring-oil film interface. s1 (f), phase ψ1; Fourier transform the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface to obtain the offset pulse signal amplitude signal A of the rolling bearing outer ring-oil film interface s2 , phase ψ2.

[0068] Furthermore, the amplitude of the pulse signal before the offset of the rolling bearing outer ring-water interface A w1 and the amplitude of the pulse signal after the shift A w2 The change in is expressed as ΔA:

[0069] ΔA=A w2 / A w1 ;

[0070] The phase change Δα between the pulse signal phase α1 before the offset and the pulse signal phase α2 after the offset at the rolling bearing outer ring-water interface is Δα=α2-α1.

[0071] The amplitude correction value of the offset pulse signal at the rolling bearing outer ring-oil film interface is expressed as A s20 :

[0072] A s20 =A s2 / ΔA.

[0073] The phase correction value of the offset pulse signal at the rolling bearing outer ring-oil film interface is expressed as ψ 20 :

[0074] ψ 20 =ψ2-Δα.

[0075] In this embodiment, since the ultrasonic phase and amplitude before and after the vibration of the outer ring-water interface are not affected by the superimposed reflection waves of the thin oil film layer, the calculated phase difference and amplitude change are equivalent to the impact of the vibration on the reflection wave of the oil film layer, thereby achieving amplitude and phase correction compensation for the reflection wave signal of the oil film layer. The method for calculating the oil film thickness at the center of the target oil film contact area includes calculating the reflection coefficient. The reflection coefficient is calculated based on the frequency domain amplitude of the ultrasonic probe center frequency corresponding to the ultrasonic reflection wave signal. The minimum frequency domain amplitude after correction is selected to calculate the effective reflection coefficient amplitude expressed as |R(f c )|:

[0076]

[0077] Where f c is the center frequency of the transducer ultrasonic probe, A ref is the mean amplitude of the non-rolling element area of ​​the rolling bearing, ψ ref is the phase mean value of the non-rolling element area of ​​the rolling bearing, and r is the reflection coefficient of the ultrasonic incident signal incident on the outer ring-oil film interface of the rolling bearing.

[0078] The calculation method of the oil film thickness at the center of the target oil film contact area is:

[0079]

[0080] Where h center is the oil film thickness at the center of the target oil film contact area, ρ o is the density of lubricating oil, c o is the longitudinal sound velocity of the lubricating oil, ρ s is the density of the outer ring of the rolling bearing, c s is the longitudinal sound velocity of the outer ring of the rolling bearing.

[0081] The following is a specific embodiment of the method of the present invention:

[0082] The method of the present invention may include an acquisition module, a data preprocessing module, a real-time film thickness calculation module, a film thickness display and storage module, a signal generator control module, and a parameter input and interaction module. In order to improve the timeliness of in-situ measurement, the Windows Real Time system is used to ensure that the execution time of the while loop or for loop box in Labview is accurate to 1ms, which can greatly improve the efficiency and stability of data processing. In order to improve the overall computational efficiency of the roller bearing film thickness in-situ measurement algorithm, the program is designed using the LabVIEW Real-Time module and a multi-threaded parallel method, wherein the LabVIEW Real-Time module more finely controls the scheduling of tasks and the allocation of CPU computing resources, and allows specific tasks to be assigned to specific CPU cores.

[0083] The specific process is as follows:

[0084] To achieve high-speed data acquisition, the signal acquisition module collects the initial ultrasonic pulse signal and the ultrasonic pulse signal emitted after the vibration offset. This module continuously acquires signals within a while loop. The acquisition module is configured for single-shot continuous trigger acquisition, which means that the total number of trigger acquisitions and the corresponding record length are pre-set. This method is suitable for high-speed, real-time data acquisition tasks.

[0085] The signal collected by the signal acquisition module is divided into the initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface, the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface, and the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface through a rectangular window function.

[0086] The process of obtaining the amplitude correction value of the offset pulse signal and the phase correction value of the offset pulse signal from the signal collected by the signal collection module is realized by the data preprocessing module;

[0087] The signal acquisition module transmits the segmented signal to the original data storage module for data storage using the synchronous transmission technology queue in LabVIEW, and simultaneously transmits it to the data preprocessing module for data processing;

[0088] The raw data storage module and the data preprocessing module are distributed in two independent CPU threads. The two modules do not interfere with each other, which can improve the efficiency of data processing.

[0089] The data preprocessing process is relatively slow, so two parallel data preprocessing modules can be set up based on the odd or even number of data acquisition cycles, i. After the data is transferred to the preprocessing module, it undergoes a fast Fourier transform, a vibration compensation correction algorithm, and a low-pass filter to obtain the corresponding reflection coefficient. This reflection coefficient is then passed to the film thickness calculation module in a queue to obtain the reflection coefficient amplitude. A dynamic window function is then used to obtain the data segment containing the contact zone center signal and further extract the reflection coefficient amplitude at the contact zone center. The contact zone film thickness is then calculated using the roller bearing contact zone film thickness comprehensive correction model. Given the time required for real-time display, the contact zone film thickness data is transferred to the film thickness display and storage module for real-time display and storage.

[0090] To control the pulse transmission frequency of the signal generator and receiver, a control module was set up to adjust the transducer's signal transmission frequency based on the rolling bearing cage's rotational speed, ensuring that the ultrasonic pulse signal interacts with the center of the target oil film contact area. Given the computational complexity of the data preprocessing module and film thickness calculation module, additional CPU resources were allocated to them during initial program design and debugging. Furthermore, a parameter input and interaction module was set up to facilitate parameter input and data transfer between modules.

[0091] Example 1:

[0092] Combine Figure 1 and Figure 2 As shown in the figure, the bearing vibrates during operation, and the transducer has a relative displacement and velocity relative to the outer ring-water interface. This causes the phase and amplitude of the outer ring-water interface reflection wave signal and the outer ring-oil film interface reflection wave signal received by the transducer to change accordingly.

[0093] Combine Figure 3 As shown in the figure, the initial input pulse signal and the pulse signal after vibration offset are segmented to obtain the outer ring-water interface pulse signal xoi_w1(t), the outer ring-oil film interface pulse signal xoi_s1(t), the outer ring-water interface pulse signal xoi_w2(t), and the outer ring-oil film interface pulse signal xoi_s2(t) at the initial position. The above signals are Fourier transformed to obtain the outer ring-water interface pulse signal amplitude A at the initial position. w1 (f), Phase α1, outer ring-oil film interface signal amplitude A s1 (f) Phase ψ1, outer ring-water interface signal A after vibration offset w2 (f), Phase α2, outer ring-oil film interface pulse signal A s2 (f), phase ψ2. The amplitude and phase changes caused by vibration are obtained, and finally the compensated amplitude and phase are obtained. Where f represents the transducer ultrasonic probe frequency.

[0094] Combine Figure 4Figure 2 shows a flow chart of the in-situ film thickness measurement algorithm for the center of the contact zone of a high-speed roller bearing. The acquisition module is placed within a separate while loop and configured for single-shot continuous trigger acquisition. This means that continuous acquisition occurs after a preset total number of trigger acquisitions and corresponding record length. The output data in the acquisition module is segmented into the outer ring-water interface signal and the outer ring-oil film interface signal using a rectangular window function. The data is then transferred to the raw data storage module and the data preprocessing module using the "queue" synchronous transfer technology in LabVIEW. The data preprocessing process involves two parallel data preprocessing modules, each configured based on the odd or even number of acquisition cycles. After the data is transferred to the preprocessing module, it undergoes a fast Fourier transform, a vibration compensation correction algorithm, and a low-pass filter to obtain the corresponding reflection coefficient. This reflection coefficient is then queued and transferred to the film thickness calculation module to obtain the reflection coefficient amplitude. A dynamic window function is then applied to obtain the data segment containing the contact zone center signal and further extracting the reflection coefficient amplitude at the contact zone center. The contact zone film thickness is then calculated using the comprehensive correction model for the roller bearing contact zone film thickness. Considering the time it takes to display the film thickness in real time, the contact area film thickness data is transmitted to the film thickness display and storage module for real-time display and storage. A corresponding control module is set up to control the pulse transmission frequency of the transducer. By analyzing the real-time bearing cage speed, the pulse transmission frequency is fine-tuned to make it easier for the ultrasonic pulse to interact with the center of the contact area.

[0095] Example 2:

[0096] First, a reference reflection wave from the steel-air interface before vibration and a reflection wave from the oil film corresponding to a set film thickness were measured. Then, a vertical micrometer was used to randomly set small displacements of the ultrasonic transducer to simulate vibration, and the reflection wave from the oil film at the given small displacements was measured.

[0097] Table 1 shows the amplitude and phase of the reflected waves from the steel-water interface and the steel-oil interface at various locations at a 25 MHz ultrasonic transducer center frequency, obtained for a set film thickness of 3.05 μm. In the table, A_w and A_s represent the normalized reflected wave amplitudes at the steel-water and steel-oil interfaces, respectively, while α and ψ represent the reflected wave phases at the steel-water and steel-oil interfaces, respectively. While the reflected wave amplitudes at the steel-water and steel-oil interfaces are negligibly affected by small vibration displacements, their phases are significantly affected.

[0098] Table 1 Reflection wave amplitude and phase under different vibration displacements

[0099]

[0100] After correction using the correction algorithm, the amplitude and phase of the steel-oil interface reflection wave at different vibration displacements at 25 MHz are shown in Table 2. After phase correction using the above algorithm, the phase at each vibration displacement does not change significantly compared to the state without vibration.

[0101] Table 2 Corrected steel-oil interface reflection wave amplitude and phase under different vibration displacements

[0102]

[0103] The oil film thickness was calculated using the complex total reflection coefficient method. Table 3 shows the calculated oil film thickness values ​​after vibration compensation at different vibration displacements. The calculated values ​​of the oil film thickness after vibration compensation are in good agreement with the results obtained without vibration. This verifies the correctness of the signal compensation method proposed in this invention that takes vibration into account.

[0104] Table 3 Corrected oil film thickness calculation results under different vibration displacements (μm)

[0105]

[0106]

[0107] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely illustrative of the principles and applications of the invention. It should be understood that many modifications may be made to the illustrative embodiments, and that other arrangements may be devised, without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in ways other than those described in the original claims. It should also be understood that features described in conjunction with individual embodiments may be used in conjunction with other described embodiments.

Claims

1. A method for measuring the oil film thickness in the contact area of ​​a rolling bearing based on vibration correction and compensation, characterized in that: include: Assume that the transmitting ultrasonic pulse signal and the receiving ultrasonic pulse signal of the transducer are affected by the same vibration offset; Obtain the initial ultrasonic pulse signal of the transducer and the ultrasonic pulse signal after vibration offset, and perform Fourier transform to obtain the pulse signal amplitude A before offset of the rolling bearing outer ring-water interface. w1 and phase α1, pulse signal amplitude A after offset w2 The pulse signal amplitude A after the phase α2 and the offset of the rolling bearing outer ring-oil film interface s2 and phase ψ2; the pulse signal amplitude before the offset of the rolling bearing outer ring-water interface is A w1 And the pulse signal amplitude after offset A w2 The change in the amount of the pulse signal amplitude A after the offset of the rolling bearing outer ring-oil film interface s2 Perform compensation correction to obtain the offset pulse signal amplitude correction value A of the rolling bearing outer ring-oil film interface s20 At the same time, the variation of the phase α1 of the pulse signal before the offset and the phase α2 of the pulse signal after the offset of the rolling bearing outer ring-water interface is used to compensate and correct the offset pulse signal ψ2 of the rolling bearing outer ring-oil film interface, and the offset pulse signal phase correction value ψ of the rolling bearing outer ring-oil film interface is obtained. 20 ; The amplitude correction value A of the offset pulse signal based on the rolling bearing outer ring-oil film interface s20 and the phase correction value of the pulse signal after the shift ψ 20 The effective reflection coefficient amplitude is calculated, and then the oil film thickness at the center of the target oil film contact area is calculated based on the effective reflection coefficient amplitude.

2. The method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation according to claim 1, characterized in that: The initial transmitted ultrasonic pulse signal of the transducer includes the initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface; wherein t represents time; The ultrasonic pulse signal emitted after the vibration offset of the transducer includes the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface and the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface.

3. The method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation according to claim 2, characterized in that: Perform Fourier transform on the initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface to obtain the pre-offset pulse signal amplitude A of the rolling bearing outer ring-water interface. w1 and phase α1; Fourier transform the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface to obtain the offset pulse signal amplitude A of the rolling bearing outer ring-water interface w2 and phase α2; Perform Fourier transform on the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface to obtain the offset pulse signal amplitude signal A of the rolling bearing outer ring-oil film interface. s2 and phase ψ2.

4. The method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation according to claim 3, characterized in that: The amplitude of the pulse signal before the offset of the rolling bearing outer ring-water interface A w1 And the pulse signal amplitude after offset A w2 The change in is expressed as ΔA: ΔA=A w2 / IN w1 ; The amplitude correction value of the offset pulse signal at the rolling bearing outer ring-oil film interface is A s20 : IN s20 = Yes s2 / ΔA; The change in the phase α1 of the pulse signal before the offset and the phase α2 of the pulse signal after the offset at the rolling bearing outer ring-water interface is expressed as Δα: Δα=α2-α1; The phase correction value of the offset pulse signal of the rolling bearing outer ring-oil film interface ψ 20 for: ψ 20 =ψ2-Dα.

5. The method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation according to claim 4, characterized in that: The effective reflection coefficient amplitude is expressed as |R(f c )|: Where f c is the center frequency of the transducer ultrasonic probe, A ref is the mean amplitude of the non-rolling element area of ​​the rolling bearing, ψ ref is the phase mean value of the non-rolling element area of ​​the rolling bearing, and r is the reflection coefficient of the ultrasonic incident signal incident on the outer ring-oil film interface of the rolling bearing.

6. The method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation according to claim 5, characterized in that: The calculation method of the oil film thickness at the center of the target oil film contact area is: Where h center is the oil film thickness at the center of the target oil film contact area, ρ o is the density of lubricating oil, c o is the longitudinal sound velocity of the lubricating oil, ρ s is the density of the outer ring of the rolling bearing, c s is the longitudinal sound velocity of the outer ring of the rolling bearing.

7. The method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation according to claim 2, characterized in that: The initial ultrasonic pulse signal and the ultrasonic pulse signal transmitted after the vibration shift are collected by a signal acquisition module; the signal acquisition module continuously collects signals based on a while loop frame.

8. The method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation according to claim 7, characterized in that: The signal collected by the signal acquisition module is divided into the initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface, the vibration offset position incident signal xoi_w2(t) of the rolling bearing outer ring-water interface, and the vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface through a rectangular window function.

9. The method for measuring the oil film thickness in the contact area based on rolling bearing vibration correction and compensation according to claim 8, characterized in that: The process of obtaining the amplitude correction value of the offset pulse signal and the phase correction value of the offset pulse signal from the signal collected by the signal collection module is realized by the data preprocessing module; The signal acquisition module transmits the segmented signal to the original data storage module for data storage using the synchronous transmission technology queue in LabVIEW, and simultaneously transmits it to the data preprocessing module for data processing; The raw data storage module and the data preprocessing module are distributed in two independent CPU threads.

10. The contact area oil film thickness measurement method based on rolling bearing vibration correction and compensation according to claim 9, characterized in that: A control module is provided to adjust the signal transmission frequency of the transducer according to the rotation speed of the rolling bearing cage so that the ultrasonic pulse signal acts on the center of the target oil film contact area.

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