The method of vibration lubricity oils nodes mechanisms

 

(57) Abstract:

The method is designed to assess the technical condition of electrical machines, pumps, gearboxes, etc. In the control points on the surface of the elements integral measure the level of RMS value of vibration acceleration in the frequency range 14 to 40 kHz. Improved reliability and empowerment the application of the method for different types of elements. table 1.

The invention relates to nondestructive inspection of a technical condition of electrical machines, pumps, gearboxes, etc. and in particular to methods of diagnostics of machinery.

The reliability of machinery is determined by the intensity of wear them in friction, which largely depends on the quality of the lubricant. Vibrodiagnostics and temporal analysis of the lubricating ability of the oil in friction nodes mechanisms at an early stage to reduce operational properties allows to estimate the residual life of the lubricant. One of the main reasons for the decrease in the reliability of machinery is the limit lubricating ability of the oil, therefore, the development task.

It is known that the lubricity property of lubricants to reduce wear and friction force does not depend on its viscosity (C. D. Zozulya, E. L. Shvedkov and other Dictionary-a guide to friction, wear and lubrication of machine parts. Kiev: Nauk. Dumka, 1990. - 264).

Currently, the main methods for evaluating lubricity of oils are laboratory, bench and field test methods for lubricants in the elements. Known methods of evaluating lubricity of oils do not cover the whole variety of interaction effects in the real nodes mechanisms, as under different conditions of friction changes the nature of the frictional contact interaction and the nature of physico-chemical and mechanical phenomena that affect the friction and, consequently, on the lubricity of oils nodes mechanisms (E. C. Zinoviev, A. L. Levin, M. M. Borodulin, A. C. Chichinadze. "Polymers in friction units of machines and devices", - M.: Mashinostroenie, 1980, - 208).

Known electrical method for evaluating lubricity of oils of tribosystems (Shaolin C. M., Sarychev, A. "Acoustic control of friction NPP".- M.: Energoatomizdat, 1988.- 176), which consists in measuring the electrical resistance between the phone and what is the measurement only on the idle equipment.

Known acoustic estimation method based on the measurement of acoustic emission parameters, perceived piezoelectric sensor, and processing circuitry (A. I. of Sviridenko, N. To. Munchkin, T. F. Kalmykov, O. Century Kholodilov, "Acoustic and electrical methods in science in tribology", - Mn.: Science and technology, 1987. - 280).

However, the two methods have low sensitivity and resolution at an early stage of deterioration of the lubricating ability of the oil of elements.

Closest to the claimed method is vibrodiagnostics lubricant nodes mechanisms by measurement at the test points on the surface of the shields in the radial direction RMS level of vibration acceleration in the frequency range 10-20 kHz, in particular, in the frequency band 1/3 octave filter with a center frequency equal to 16 kHz. The vibration condition of the lubricant according to this method, based on a comparison of the initial level of RMS value of acceleration and its fluctuations characteristic of fresh lubricant, with the same value characteristic of a lubricant, which lost their operational properties (A., Gorb is ehnika 1992, N 10-11, S. 32-36).

The sensitivity of this method is 90 dB.

The dynamic range of the method - 20 dB.

The disadvantage is the high value of the threshold and the low dynamic range of the method.

The task of the invention consists in reducing the sensitivity of the method and the expansion of dynamic range.

The problem is solved in that for vibrodiagnostics lubricating ability of the oil to the mechanism nodes perform measurements of the integral level of RMS value of vibration acceleration in the frequency range 14-40 kHz.

The sensitivity threshold of the method is 10 dB.

The dynamic range of the method is 120 dB.

The method is as follows. On the surface of the body node of the mechanism set measuring sensor in close proximity to the diagnosed tribojunction, for example, to the outer race of the rolling bearing (sliding). Conduct measurements of the integral level of RMS value of vibration acceleration in the frequency range 14-40 kHz. About the importance of lubricity of the lubricant friction judged by the value of the integral level srednekwadrati residual life of a lubricant for a given node mechanism, that allows you to forecast the future health of the mechanism.

The proposed method reduces the threshold to 10 dB increase in dynamic range up to 120 dB, which leads to improved accuracy and reliability of the method of vibrodiagnostics lubricity oils nodes mechanism.

Because the lubricity is a property of a lubricant to reduce wear and friction and does not depend on the viscosity of the material, for the diagnosis of lubricating ability of the spectrum of the vibration signal, it is necessary to highlight areas that do not depend on the viscosity of the lubricant, speed, type of bearing Assembly, etc.

To detect the above-mentioned region of the spectrum of the vibration signal we have delivered and analyzed experiments in laboratory settings, the mechanisms of General purpose, arrangements with high requirements on vibration activity and reliability, with speed from 700 to 6000 rpm, with a capacity of 6 kW to 60 MW and with bearing units on the basis of bearings, slides and combo. Studies were conducted on a universal laboratory setup M-PW on the four-ball and reliability. Time series analysis of vibration activity conducted on the mechanisms with a wide range of defects and quality lubricants before and after repair. We examined 40 centrifugal pumps with a capacity of 630 kW for 3 cycles repair-repair within 3 years of operation. Analysis of vibratory activity carried out by the spectral analyzer on a personal computer with specialized software and modified devices development company LLP "Firm made before and after service on the basis of the device "malachite". The analysis of the spectra and their temporal analysis was carried out in the frequency range 5-50 kHz, 10-10000 Hz, and integral levels in the frequency range 10-1000 Hz, 5-10 kHz, 14-40 kHz. Controlled RMS value of vibration velocity, vibration acceleration and peak factor.

The error of measurement was 5%.

Research on installing M-PV conducted on the four-ball scheme. The accelerometer was attached to the body of the cuvette three balls through the studs. The test conditions are the following:

- the test one set of balls - 5 minutes;

- cooling the cell to laboratory temperature;

- replacement balls;

- the next testing cycle.

Study the discrete narrow (10 kgf) in the range 10-180 kgf. Changing the speed of rotation selectable in the range from 300 to 4500 rpm Investigations were carried out with liquid and plastic lubricant material IA, MS-20, TA-22, lithol-24, tsiatim-201, XA-extra.

Controlled spectra RMS value of vibration acceleration in the frequency range 5-50 kHz, were averaging 10 spectra and the data were represented in a logarithmic scale, i.e., in dB (3 of 10-4m/s2).

The results of these studies showed that the integral level of RMS value of vibration acceleration in the frequency range 14 to 40 kHz corresponds to the friction coefficient of friction, i.e., the lubricating ability of the oil.

Compliance data of vibratory activity of friction in the band 14-40 kHz, RMS value of vibration acceleration in dB (3 of 10-4m/s2) - (A) and coefficients of friction (f) is shown in the table at the end of the description.

Studies of vibratory activity nodes mechanisms in the band 14-40 kHz when operating conditions from break-in to failure showed that the values of vibratory activity are within a 10 - 130 dB and depend only on friction, wear surface friction and does not depend on the viscosity of lubricating mA the phenomena of the elements of the mechanism and their harmonics, that leads to increased sensitivity and reducing the dynamic range of the method.

In the region of the spectrum above 40 kHz sensitivity is the noise level.

Range RMS value of vibration acceleration in the frequency range 14-40 kHz depends on the node type and may be either discrete spectrum, or continuum with discrete components, or a continuous spectrum. It is found experimentally that the monitoring individual components of the spectrum in the claimed bandwidth does not increase the accuracy of diagnostics lubricating ability in contrast to the analysis of integral level in the band 14 - 40 kHz.

Experimental tests have shown that the value of vibratory activity below 80 dB (3 of 10-4m/s2) is a characteristic of the lubricating ability of the oil in friction, in which there is irreversible changes of the metal. In this case, replacement of the lubricant leads to a significant reduction of vibratory activity. The value of vibratory activity above 90 dB is a characteristic of the lubricating ability of the oil in friction, in which the probability of violating the integrity of the metal friction pairs high and is the La leads to a temporary and insignificant reduction of vibratory activity, that is 90 dB is the maximum value of the index lubricity oils node mechanism and is the basis for calculating the residual life of a lubricant for a given node of the mechanism under these conditions.

Thus, on the basis of the analysis of monitoring nodes mechanisms laboratory installations, surveillance mechanisms CHP, ship mechanisms, mechanisms of thermal networks, water utility management, flour production line, the polygraph works and so on, before and after replacement of the lubricant found that the limiting value of the integral level of RMS value of vibration acceleration in the frequency range 14-40 kHz 90 dB. Operation of elements with values above 90 dB can lead to irreversible changes in the material pairs, which are in frictional engagement.

Examples of the complete method.

Example 1.

Vladivostok, VTEC-2, nourishing centrifugal pump PE-500-180-2 (ESP), power 3150 kW, speed 2985 rpm, lubrication TP-22. Bearing assemblies slip. Analyzed the lubricity of the oil 4 bearing slides. Time analysis of vibratone perform during the 4 IU the LLP "Firm made before and after service". Measure the integral level of RMS value of vibration acceleration in the frequency range 14-40 kHz. The averaging time set to 10 s, which corresponds to averaging over 1000 measurements. The measurement error of 5%.

The threshold amounted to 8 dB.

The dynamic range of 70 dB.

Minimum residual life of the lubricant is 2400 hours of operation.

Example 2.

Heat networks JSC Dalenergo, network centrifugal pump CPU h electric type AI-U-US, the capacity of 630 kW speed 1450 R/min Consider bearing assemblies with roller bearings. Bearing assemblies of the motor (grease - Litol), bearing centrifugal pump (liquid grease - MS-20). The analysis is subjected to 40 mechanisms 4 the bearing. Temporal analysis was carried out for 3 years, the measurement interval of 7 days. Means of measurement in example 1 for condition monitoring of lubricants and selective spectral analysis of the nodes in the band 14-40 kHz spectral analyzer on a personal computer with special software. The measurement error of 5%.

The threshold of sensibility and RMS value of vibration acceleration in the frequency range 14-40 kHz 90 dB defects of rolling bearings in the form of waviness of the outer and/or inner race, pitting erosion bodies and the raceways, etc., Replacement of the lubricant when the values of 60-80 dB leads to a reduction of vibratory activity in the frequency band from 2 to 8 dB, subject to the technology replacement lubricant.

Example 3.

The mechanisms and tools of measurement in example 2. Spectral analysis of mean-square value of acceleration is carried out in the frequency range of 10-40 kHz.

The sensitivity threshold was 40 dB

Dynamic range is 50 dB.

The useful signal of the controlled node is masked by the signal of the adjacent elements, their harmonics and resonance phenomena mechanism design. Limit value permissible for the operation of the lubricating oil, is meaningless.

Example 4.

The mechanisms and tools of measurement in example 2. Spectral analysis of mean-square value of acceleration is carried out in the frequency range 14-50 kHz.

The sensitivity threshold was - 14 dB

Dynamic range is 80 dB.

I.e., the extension strip of analysis has not led to a decrease of the threshold and the expansion of dynamic range, but unreasonably increased requirements to increase the resonant frequency of Akseki lubricity oils largest RMS value of the vibration by measurements on the surface of the host mechanism, characterized in that they measure the integral of the level of RMS value of vibration acceleration in the frequency range 14-40 kHz.

 

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SUBSTANCE: central excited pillar of the device is secured to the table of the vibration bench. The side loaded pillars are secured to the corresponding bearing strips of the vibration insulators. The second bearing strips are secured to the central pillar. The loaded side pillars and shelves are provided with slots for changing position of the vibration insulators depending on their sizes. The exciting force is directed along the axis of the vibration insulator and transmitted through excited central pillar and strips to the flexible member of vibration insulators which undergo shearing vibration energy and reduce the exciting force transmitted to the loaded weight through side pillars.

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