Contact area oil film thickness measuring method based on vibration correction compensation of rolling bearing

Abstract

The invention discloses a contact area oil film thickness measurement method based on rolling bearing vibration correction compensation, and belongs to the technical field of lubricating oil film thickness measurement. The invention aims to solve the problem that the vibration in the operation process of the rolling bearing affects the amplitude and phase of a film thickness measurement signal and further affects the film thickness measurement accuracy. Comprising the following steps: acquiring an ultrasonic pulse signal initially transmitted by a transducer and an ultrasonic pulse signal transmitted after vibration offset, and performing Fourier transform to obtain pulse signal amplitudes and phases before and after offset of a rolling bearing outer ring-water interface and pulse signal amplitudes and phases after offset of a rolling bearing outer ring-oil film interface; compensating the amplitude and the phase of the pulse signal after the offset of the rolling bearing outer ring-oil film interface by adopting the amplitude variation and the phase variation before and after the offset of the rolling bearing outer ring-water interface to obtain an amplitude correction value and a phase correction value; and calculating the effective reflection coefficient amplitude, and further calculating to obtain the center oil film thickness of the target oil film contact area. The method 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 compensation, and belongs to the technical field of lubricating oil film thickness measurement. Background Art

[0002] As one of the indispensable components in the mechanical system, rolling bearing plays a key role in supporting the rotating body, reducing friction and wear, and improving the operating efficiency of the system. Its importance is reflected in many aspects, especially in modern high-speed, high-precision and heavy-load mechanical equipment, the application of rolling bearings is even more crucial. In rolling bearings, the oil film thickness is an important parameter that directly reflects the lubrication state of the bearing contact area and needs to be measured.

[0003] Bearing vibration is a common phenomenon in the operation of rolling bearings. Its main causes include uneven oil film thickness, changes in lubricating oil viscosity, imbalance in the internal structure of the bearing, etc. Under high-speed rotation conditions, bearing vibration causes additional load and heat to be generated inside the bearing, which in turn affects the stability and life of the bearing; at the same time, bearing vibration will also cause noise and vibration during the operation of the bearing, affecting the overall performance of the machine.

[0004] At present, the measurement of oil film thickness mainly includes electrical method, optical method and ultrasonic method. Among them, the ultrasonic method has low requirements on the environment and can work normally in harsh environments such as high temperature, high pressure and high humidity; while the electrical method and optical method 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 interfering with 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 slight 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 period of data processing and analysis; 4) The ultrasonic method has a 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, the bearing will vibrate due to various reasons. The vibration causes the amplitude and phase changes of the signals of the coupling agent layer and the oil film layer, 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 a rolling bearing affects the amplitude and phase of a 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] A method for measuring oil film thickness in a contact area based on rolling bearing vibration correction compensation of the present invention comprises:

[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] The initial ultrasonic pulse signal of the transducer and the ultrasonic pulse signal after vibration offset are obtained, and Fourier transform is performed to obtain the pulse signal amplitude A before offset of the rolling bearing outer ring-water interface. w1 and phase α 1 , pulse signal amplitude after offset A w2 and phase α 2 and the offset pulse signal amplitude A of the rolling bearing outer ring-oil film interface s2 and phase ψ 2 ; Using the pre-shift pulse signal amplitude A of the rolling bearing outer ring-water interface 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 Compensation correction is performed to obtain the offset pulse signal amplitude correction value A of the rolling bearing outer ring-oil film interface s20 , and the phase α of the pre-shift pulse signal of the rolling bearing outer ring-water interface is used 1 and the pulse signal phase after shifting α 2 The change in the amount of the offset pulse signal ψ of the rolling bearing outer ring-oil film interface 2 Compensation correction is performed to obtain the offset pulse signal phase correction value ψ of the rolling bearing outer ring-oil film interface 20 ;

[0011] The amplitude correction value A of the pulse signal after the offset 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 transmission 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 α 1 ; Perform Fourier transform on 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 α 2 ;

[0015] The vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface is Fourier transformed to obtain the offset pulse signal amplitude signal A of the rolling bearing outer ring-oil film interface. s2 and phase ψ 2 .

[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 w1 And the pulse signal amplitude after offset 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] Phase α of the pulse signal before the offset of the rolling bearing outer ring-water interface 1 and the pulse signal phase after shifting α 2 The change in is expressed as Δα:

[0021] Δα=α 2 -α 1 ;

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

[0023] ψ20 =ψ 2 -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 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.

[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 outer ring density 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 a data preprocessing module;

[0033] The signal acquisition module transfers the segmented signal to the original data storage module for data storage using the synchronous transfer technology queue in LabVIEW, and at the same time transfers 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] Beneficial effects of the present invention: The method of the present invention calculates the oil film thickness at the center of the contact area by compensating and correcting the phase and amplitude of the reflected wave signal of the oil film layer to obtain the amplitude of the ultrasonic reflection coefficient, and can realize accurate measurement of the oil film thickness of the rolling bearing 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 in 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 the real-time measurement of the oil film thickness in the center of the contact area more accurately. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0039] Figure 2 It is a schematic diagram of the effect of bearing vibration on ultrasonic testing 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 be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are 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 in conjunction with 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 contact area oil film thickness measurement method based on rolling bearing vibration correction compensation, comprising:

[0046] Combination Figure 1 As shown in the figure, considering the rolling bearing is affected by vibration, the transducer will have a relative displacement and speed relative to the outer ring-water interface, which causes the phase and amplitude of the reflected wave signal of the oil film layer received by the transducer to change accordingly. The time history from the transducer sending ultrasonic waves to act on the oil film layer to the ultrasonic waves returning from the oil film layer is very short, so it can be approximately considered that the position of the probe receiving and transmitting signal process is fixed. This means that the signal received or transmitted by the transducer can be approximately considered to be only affected by the vibration displacement.

[0047] When the bearing vibrates, the outer ring is regarded as a rigid body, and its thickness does not change. The displacement of the interface between the outer diameter of the outer ring 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 is 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 wh_v and the residual reflection coefficient R rem_v becomes:

[0054]

[0055] Considering that the bearing vibration amplitude is very small, in this case, it can be approximately considered that the reflected wave at the outer ring-water interface is affected by the vibration in the same way as the reflected wave at the outer ring-oil film interface, 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 α 1 , α 2 ——Ultrasonic phase before and after the reflected wave from the outer ring-water interface vibrates (rad);

[0058] ψ 1 , 2 ——Ultrasonic phase before and after the reflected wave at the outer ring-oil film interface vibrates (rad);

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

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

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

[0062] The initial ultrasonic pulse signal of the transducer and the ultrasonic pulse signal after vibration offset are obtained, and Fourier transform is performed to obtain the pulse signal amplitude A before offset of the rolling bearing outer ring-water interface. w1 and phase α 1 , pulse signal amplitude after offset A w2 and phase α 2 and the offset pulse signal amplitude A of the rolling bearing outer ring-oil film interface s2 and phase ψ 2 ; Using the pre-shift pulse signal amplitude A of the rolling bearing outer ring-water interface 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 Compensation correction is performed to obtain the offset pulse signal amplitude correction value A of the rolling bearing outer ring-oil film interface s20 , and the phase α of the pre-shift pulse signal of the rolling bearing outer ring-water interface is used 1 and the pulse signal phase after shifting α 2 The change in the amount of the offset pulse signal ψ of the rolling bearing outer ring-oil film interface2 Compensation correction is performed to obtain the offset pulse signal phase correction value ψ of the rolling bearing outer ring-oil film interface 20 ;

[0063] The amplitude correction value A of the pulse signal after the offset 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 emitted by the transducer and the ultrasonic pulse signal emitted after the vibration shift are segmented. The initial ultrasonic pulse signal emitted by the transducer includes an initial position incident signal xoi_w1(t) of the rolling bearing outer ring-water interface; wherein t represents time; and also includes 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 α 1 , 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 α 2 ;

[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 ψ 1 ; 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 , phase ψ 2 .

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

[0069] ΔA=A w2 / A w1 ;

[0070] Phase α of the pulse signal before the offset of the rolling bearing outer ring-water interface 1 and the pulse signal phase after shifting α 2 Phase change Δα = α 2 -α 1 .

[0071] The amplitude correction value of the pulse signal after the offset of 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 =ψ 2 -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 wave of the thin oil film layer, the calculated phase difference and amplitude change can be equivalent to the influence of the vibration on the reflection wave of the oil film layer, thereby realizing the amplitude and phase correction compensation of 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, which is calculated according to the frequency domain amplitude of the center frequency of the ultrasonic probe corresponding to the ultrasonic reflection wave signal, and 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 ois the density of lubricating oil, c o is the longitudinal sound velocity of the lubricating oil, ρ s is the outer ring density 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 implementation scheme 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 running time of the while loop or for loop frame 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 multi-threaded parallel mode, wherein the LabVIEW Real-Time module controls the scheduling of tasks and the allocation of CPU computing resources more finely, and allows specific tasks to be allocated to specific CPU cores.

[0083] The specific process is as follows:

[0084] To achieve high-speed acquisition, the initial ultrasonic pulse signal and the ultrasonic pulse signal after vibration offset are collected by the signal acquisition module; the signal acquisition module continuously acquires signals based on the while loop frame. The acquisition module is set to single-start continuous trigger acquisition, that is, the total number of trigger acquisitions and the corresponding record length are preset before continuous acquisition. 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 transfers the segmented signal to the original data storage module for data storage using the synchronous transfer technology queue in LabVIEW, and at the same time transfers it to the data preprocessing module for data processing;

[0088] The original 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 slow, so two parallel data preprocessing modules can be set according to the parity of the data acquisition cycle number i. After the data is transferred to the preprocessing module, it is processed by fast Fourier transform, vibration compensation correction algorithm, and low-pass filtering to obtain the corresponding reflection coefficient. The reflection coefficient is transferred to the film thickness calculation module in the form of a queue to obtain the reflection coefficient amplitude. Subsequently, the data segment containing the contact area center signal is obtained through the dynamic window function and the reflection coefficient amplitude of the contact area center is further extracted. After that, the contact area film thickness is calculated by the roller bearing contact area film thickness comprehensive correction model. Considering that real-time display takes a long time, the contact area film thickness data is transferred to the film thickness display and storage module for real-time display and storage.

[0090] In order to control the pulse transmission frequency of the signal generator receiver, 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. Considering the calculation amount of the data preprocessing module and the film thickness calculation module, more CPU computing resources are allocated to them during the initial program design and debugging. In addition, the parameter input and interaction modules are set up mainly for inputting parameters and data transmission between modules.

[0091] Embodiment 1:

[0092] Combination Figure 1 and Figure 2 As shown, the bearing vibrates during operation, and the transducer has a relative displacement and velocity relative to the outer ring-water interface, which 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] Combination Figure 3 As shown, the input initial pulse signal and the pulse signal after vibration offset are segmented to obtain the outer ring-water interface pulse signal xoi_w1(t) at the initial position, the outer ring-oil film interface pulse signal xoi_s1(t), the outer ring-water interface pulse signal xoi_w2(t) after vibration offset, and the outer ring-oil film interface pulse signal xoi_s2(t). The above signals are Fourier transformed to obtain the outer ring-water interface pulse signal amplitude A at the initial position w1 (f), phase α 1 , outer ring-oil film interface signal amplitude A s1 (f), phase ψ 1 , the outer ring-water interface signal A after vibration offset w2 (f), phase α 2, outer ring-oil film interface pulse signal A s2 (f), phase ψ 2 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] Combination Figure 4 As shown in the figure, it is a schematic diagram of the algorithm flow of the in-situ measurement of the film thickness in the center of the contact area of ​​a high-speed roller bearing. The acquisition module is placed separately in the while loop frame, and the acquisition module is set to single-start continuous trigger acquisition, that is, the total number of trigger acquisitions and the corresponding record length are preset and then continuous acquisition is performed. The output data is divided into the outer ring-water interface signal and the outer ring-oil film interface signal only by the rectangular window function in the acquisition module, and then the data is transferred to the original data storage module and the data preprocessing module through the synchronous transfer technology "queue" in labview. The data preprocessing process sets two parallel data preprocessing modules according to the parity of the acquisition cycle number i. After the data is transferred to the preprocessing module, it is subjected to fast Fourier transform, vibration compensation correction algorithm, and low-pass filtering to obtain the corresponding reflection coefficient. The reflection coefficient is transferred to the film thickness calculation module in the form of a queue to obtain the reflection coefficient amplitude, and then the data segment containing the contact area center signal is obtained by the dynamic window function and the reflection coefficient amplitude of the contact area center is further extracted. Then, the contact area film thickness is calculated by the comprehensive correction model of the film thickness of the roller bearing contact area. Considering that real-time display takes a long time, the film thickness data of the contact area is transmitted to the film thickness display and storage module for real-time display and storage. The corresponding control module is set to control the pulse emission frequency of the transducer, and the pulse emission frequency is fine-tuned by analyzing the real-time bearing cage speed, so that the ultrasonic pulse is easier to act on the center of the contact area.

[0095] Embodiment 2:

[0096] First, the reference reflection wave of the steel-air interface before vibration and the reflection wave of the oil film layer corresponding to the set film thickness are measured. Then, the vertical micrometer is used to randomly set the small displacement of the ultrasonic transducer to simulate vibration, and the reflection wave of the oil film layer under the given small displacement is obtained by testing.

[0097] As shown in Table 1, the amplitude and phase of the steel-water interface reflection wave and steel-oil film interface reflection wave at each position corresponding to the center frequency of the ultrasonic transducer at 25MHz when the film thickness is set to 3.05μm. In the table, A_w and A_s represent the normalized reflection wave amplitudes of the steel-water interface and the steel-oil interface, respectively, and α and ψ represent the reflection wave phases of the steel-water interface and the steel-oil interface, respectively. The reflection wave amplitudes of the steel-water interface and the steel-oil interface are almost negligibly affected by the small vibration displacement, while their phases are significantly affected by the small vibration displacement.

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

[0099]

[0100] After correction by 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 the phase correction of the above algorithm, the phase under each vibration displacement did not change significantly compared with the case without vibration.

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

[0102]

[0103] The oil film thickness is calculated using the complex total reflection coefficient method. Table 3 shows the calculated values ​​of the oil film thickness after vibration compensation under different vibration displacements. The calculated values ​​of the oil film thickness after vibration compensation are in good agreement with the results without vibration. This verifies the correctness of the signal compensation method considering vibration proposed in the present invention.

[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 examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A method for measuring the oil film thickness in the contact area based on vibration correction and compensation of rolling bearings, 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; The initial ultrasonic pulse signal of the transducer and the ultrasonic pulse signal after vibration offset are obtained, and Fourier transform is performed 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; using the pre-shift pulse signal amplitude A of the rolling bearing outer ring-water interface 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 Compensation correction is performed 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 pre-shift pulse signal phase α1 and the post-shift pulse signal phase α2 of the rolling bearing outer ring-water interface is used to compensate and correct the post-shift pulse signal ψ2 of the rolling bearing outer ring-oil film interface, and the post-shift 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 pulse signal after the offset 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 contact area oil film thickness measurement method based on rolling bearing vibration correction compensation according to claim 1 is characterized in that: The initial transmission 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 contact area oil film thickness measurement method based on rolling bearing vibration correction compensation according to claim 2 is 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; The vibration offset position incident signal xoi_s2(t) of the rolling bearing outer ring-oil film interface is Fourier transformed to obtain the offset pulse signal amplitude signal A of the rolling bearing outer ring-oil film interface. s2 and phase ψ2.

4. The contact area oil film thickness measurement method based on rolling bearing vibration correction compensation according to claim 3 is 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 of the rolling bearing outer ring-water interface is expressed as Δα: Δα=α2-α1; The phase correction value of the pulse signal after the offset of the rolling bearing outer ring-oil film interface ψ 20 for: ψ 20 =ψ2-Dα.

5. The contact area oil film thickness measurement method based on rolling bearing vibration correction compensation according to claim 4 is 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 contact area oil film thickness measurement method based on rolling bearing vibration correction compensation according to claim 5 is 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 outer ring density of the rolling bearing, c s is the longitudinal sound velocity of the outer ring of the rolling bearing.

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

8. The contact area oil film thickness measurement method based on rolling bearing vibration correction compensation according to claim 7 is 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 contact area oil film thickness measurement method based on rolling bearing vibration correction compensation according to claim 8 is 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 transfers the segmented signal to the original data storage module for data storage using the synchronous transfer technology queue in LabVIEW, and at the same time transfers 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 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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