RU1787269C - Method of vibroacoustic diagnostics of rolling bearings - Google Patents

Abstract

The invention relates to methods for diagnosing rolling bearings and bearing assemblies, mainly axlebox assemblies of a railway rolling system cfaBa, and can be used in the maintenance and repair of machines, mechanisms and vehicles. SUMMARY OF THE INVENTION: the vibration signal of a test rotating rotating bearing is recorded, the amplitude spectrum of vibration is measured, the vibration spectrum components of the bearing elements are isolated, the frequency range of the selected components and the shift of these frequencies are measured, and the state of the bearing elements is judged by their values , then reverse the direction of rotation of the bearing and, comparing the largest amplitudes of the spectrum components belonging to the corresponding elements of the bearing, with the initial values We conclude that the defect is located in the element on the side of the direction of movement of the bearing, if the compared amplitudes of the components are larger than the original ones, and on the side of the opposite direction of the movement, if the compared amplitudes of the components are smaller than the initial ones, and the parameters of the defect are estimated from the value of the comparison result, 1 tab., 4 ill.

Description

The invention relates to the diagnosis of rolling bearings and bearing units, mainly axle boxes of railway rolling stock, and can be used in the maintenance and repair of machines, mechanisms and vehicles.

A known method for the diagnosis of rolling bearings, which measure the amplitude spectrum of the vibration of the mechanism with the bearings being diagnosed, isolates the components of the vibration spectrum of the bearings that do not coincide with the components of the vibration spectrum of others

elements of the mechanism, measure the frequency range of the selected components and judging by its magnitude the state of the bearings. However, the known method does not allow diagnostics with the localization of defects in the assembled bearing, since the vibration spectrum of the bearings is high-frequency modulated signals with a large number of harmonics and subharmonics, which makes it difficult to monitor the technical condition of the bearing over the measured frequency range selected components and determine the location of the defect and its magnitude. Indicated

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causes reduce the effectiveness of bearing diagnostics.

The aim of the invention is to increase the efficiency of diagnosis.

The goal is achieved in that according to the method of vibro-acoustic diagnostics of rolling bearings, based on measuring the amplitude spectrum of the vibration of the bearing elements when rotating it under load and isolating the components of the vibration spectrum in the given frequency ranges, the amplitude spectrum of the vibration of the bearing elements upon reverse rotation is additionally measured, structure-. the components of this spectrum in a given frequency range determine the frequency shift of the components relative to the reference value and the magnitude of the frequency shift determines the presence of a defect, the magnitude of the comparison of the maximum values of the amplitudes of the components of the vibration spectrum of the bearing during forward and reverse rotation determines the location of the defect and its magnitude.

In FIG. 1 is a functional diagram of an apparatus for implementing the proposed method; in FIG. 2 shows a separator with cracks in the corners on one side of the jumper; in FIG. 3 - spectrograms of the vibration of the bearing, corresponding (from bottom to top) to the reference bearing with cracks in the cage on one surface of its jumper during forward rotation and to a bearing with the same defect, but during reverse rotation; in FIG. 4 is a graph of the dependence of the difference in maximum amplitudes for forward and reverse rotation on the magnitude of the defect.

The device comprises a diagnostic object 1, a vibration sensor 2, an amplifier 3, a spectrum analyzer 4, an amplitude spectrum adjuster 5 of a reference bearing, a frequency shift measuring unit 6, a threshold device 7, an indicator 8, a control unit 9, a memory cell 10, a switch 11, a block 12 subtracting, character determining unit 13, module extraction unit 14. Diagnostic object 1 includes a rotary drive bearing. In this case, the diagnostic object 1, the vibration sensor 2, the amplifier 3, the spectrum analyzer 4, the frequency shift measuring unit b and the threshold device 7 are connected in series. The output of the master unit 5 of the amplitude spectrum of the reference bearing is connected to the reference input of block 6. The outputs of the threshold device 7, the sign determining unit 13, and the module allocation unit 14 are connected to the corresponding inputs of the indicator 8. The inputs of the blocks 13. and 14 are combined and connected to the output of the block 12 subtraction, two inputs of which are connected to the corresponding outputs of the switch 11. The last control input is connected to the first output of the control unit 9, the first information

the input is connected to the output of the memory cell 10, the second to the output of the spectrum analyzer 4. The memory cell 10 is connected by the first input to the output of the spectrum analyzer 4, and the second to the first output of the control unit 9,

0 .second1 output of which is connected to the input of diagnostic object 1.

The method is carried out as follows.

The bearing is rotated, vib5 sensor 2 converts vibration into an electrical signal, which, after amplification in amplifier 3, is decomposed by spectrum analyzer 4 into amplitude spectra corresponding to each element of the bearing, and

0 store them in memory cells 10. Then, these amplitude spectra in the frequency shift measuring unit 6 are compared with the amplitude spectra of the reference bearing from the master 5 and the frequency shifts of the selected components for each element are measured. that bearing. The magnitude of these shifts using a threshold device 7 and indicator 8 determines the defective or defect-free state of the bearing. Then

0 localize the defect. To this end, the direction of rotation is reversed using the control unit 9 and the spectrum analyzer 4 decomposes the amplitude spectra of vibration of the elements of the bearing being diagnosed. Using the control unit 9, they simultaneously turn on the memory cell 10 and the switch 11, which connects the subtraction unit 12, to the first input of which

0 amplitude spectra belonging to the corresponding elements of the bearing when it is rotated in the opposite direction, and on the second - the same spectra for the forward direction of rotation. The result is compared5 simultaneously to the sign determination unit 13 and to the module allocation unit 14. Block 13 determines the sign of the comparison result, and block 14 extracts the comparison result without regard to the sign. As a result, if

If the sign of the result of the comparison is positive, then the defect is located in the bearing element on the side of the direction of movement of the reverse rotation of the bearing, and if the sign of the result is negative, the defect is located on the side of the opposite direction of movement of the reverse rotation of the bearing.

To confirm the effectiveness of the proposed method, we consider a bearing with the most dangerous and hardly recognized defect - cracks in the cage on one surface of its jumper (Fig. 2). When the car moves in one direction during one revolution of the separator, its jumper sequentially experiences two hits FI and F2 from the roller side. With one hit, the inertia of the roller and its gravity add up, and with another, they are subtracted. We assume that Fj F2. Obviously, the probability of a crack occurring from the side of the force Ft is much greater. Statistical analysis of long-running bearings confirms that cracks in the cages of the cages are typically located in the corners of the windows on one surface of the cage. It can be argued that this surface is incident, i.e. the one affected by the force FL. When the roller hits the separator jumper, acoustic vibrations arise, whose energy W is determined by the formula

WK-A

where K is the coefficient of stiffness of the material in the contact zone;

And - the amplitude of the jumper of the separator.

The appearance of a crack in the separator jumper decreases the stiffness of the jumper, and (Fig. 2) the stiffness Ki of the jumper from the side of its surface, which is affected by the force FI, decreases to a greater extent than the sacrifice K2 from the opposite jumper surface, i.e. KI K2.

Assuming, to a first approximation, that the energy of the impact by the force FI completely transforms into the energy W of the oscillations, and also, considering that the forward and reverse rotation, the energy of the impact by the force FI is the same,

W

Ki afw

 K2 -Afe

Hence

Ki Aji K2 AJ2

2 2

where Aji, Aj2 are the amplitudes of the jth jumper during reverse and forward rotation of the bearing, respectively.

But since Ki K2, then Aj2 AJL

Thus, during reverse rotation, the amplitude of the oscillations Aji is greater than the amplitude Aj2 of the oscillations during forward rotation. From the graphs in FIG. Figure 3 shows that the maximum amplitudes of the spectral components of the bearing with a cage crack shift to the right by A.f relative to the maximum amplitude of the reference bearing, which indicates

0 defective bearing. Moreover, when the bearing rotates in the opposite direction, the maximum amplitudes are greater than when it is forward, and this indicates that the defect is located on the side of the direction of movement 5 of the reverse rotation of the bearing.The difference in maximum amplitudes A A for forward and reverse rotation indicates the size of the bearing defect rolling and directly proportional to it (Fig. 4). It is similarly obtained with other defects of bearing elements, as can be seen from the table of experimental data.

The table shows that the crack growth;

5, for example, of a separator (an increase in the degree of defectiveness - the magnitude of a defect) gives a change in the amplitudes of oscillations when changing the direction of rotation for a small crack, 0.7, and for a large 1, which

0 the likelihood of FIG. 4 and that there is a positive effect. From the table as well. it can be seen that the above types of defects are uniquely associated with shifts A f of the frequencies of maximum amplitudes with respect to

5 maximum oscillation amplitudes of the reference bearing. For example, a separator crack gives A f 150-300 Hz, a roller crack gives A f 900 Hz, etc., which is evidence of the localization of defects with

0 accuracy to the part inside the bearing. A further increase in the accuracy of localization of the defect within one part is achieved by this method due to a change. direction of rotation. For example, a place

5, the location of cracks in the separator is detected to within one surface of the web.

Thus, this method is enhanced. improves diagnostic efficiency

0 rolling bearings, as it allows not only to identify the defect, but also to determine the location of the defect and its magnitude.

Claims (1)

SUMMARY OF THE INVENTION Vibro-acoustic diagnostic method 5 rolling bearings, namely, that they measure the amplitude spectrum of vibration of the bearing elements when it rotates under load, selects the components of the vibration spectrum in the given frequency ranges and judges the state of the bearing elements, characterized in that, for the purpose of to increase the diagnostic efficiency, they additionally measure the amplitude spectrum of vibration of the bearing elements during reverse rotation, isolate the components of this spectrum in a given frequency range, determine the frequency shift of the components relative to the reference value, determine the presence of a defect by the frequency shift, compare the maximum values of the amplitudes of the components of the vibration spectrum of the bearing during forward and reverse rotation, determine the location of the defect and its parameters. Fib. 2.