Method of identification of dissipative characteristics of bearings

FIELD: measurement technology; test equipment.

SUBSTANCE: method intends for inspection of rolling bearings, plain bearings and bearing units in instrument engineering, mechanical instrument engineering and electric machine engineering. One ring of bearing is loaded with permanent radial force and the other one is brought into oscillatory motion with specified frequency and amplitude by means of electro-mechanical system made of sync electric motor provided with active rotor and with two windings on stator. One winding is connected with dc source and the other one is connected with ac source. Alternative current is measured in second winding. Angular speed of oscillations of rotor is measured additionally and equivalent dissipative factor is calculated as product of constitutive factor of electric motor and relation of average meaning of current value product during period by speed to average square speed within the period.

EFFECT: improved precision of measurement.

1 dwg

 

The present invention relates to measuring and testing technology and is intended for use in studies of rolling bearings, sliding and bearing assemblies in instrumentation, mechanical engineering and electrical engineering.

A known method for the identification of the dissipative characteristics of the bearings under load which one of the rings of the bearing radial force, and the other rotates at a constant speed with a drive, and register the friction torque on the testimony of the electromagnetic brake (A.S. No. 1293576 (USSR). Device for determination of static and kinetic friction bearing / Ebhausen, Neshkov, Wegstreichen. - Publ. 28.02.87. Bull. No. 8, IPC G 01 N 19/02).

A known method for the identification of the dissipative characteristics of the bearings under load which one of the rings of the bearing radial force, and the other rotates with a constant operating frequency, change the direction of action of the radial force in the direction of rotation of the first ring with a frequency equal to the frequency of rotation of the ring, and then with the frequency equal to zero, at each frequency is measured RMS value of the variable component and the average value of the normalized integral time, electric contact in the bearing, and evaluate the dissipative characteristic values of the square of the ratio of srednica the democratic values of the variable component to the average value of the specified parameter at each frequency changes the direction of the radial force (RF Patent No. 2168712, IPC G 01 M 13/00, 13/04 was investigated. The method of controlling the quality of rolling bearings / Cowpastures. - Publ. 10.06.2001).

When you implement known methods dissipative characteristics of bearings: the moment of force of friction or the coefficient of friction measured during the rotation of one of the bearing rings with constant speed. However, it is known that the friction force in the presence of a lubricant depends on the travel speed, the ambient temperature, the condition of the surfaces, work duration, and other factors, and is random (L.A. Sosnovskiy, Makhutov N.A., problems in mechanics of machines VA Friction mechanical fatigue: Basic laws / laboratory, 1992, No. 9. - P.46-63). Therefore, the dimension of dissipative characteristics at one speed does not allow to obtain reliable information about the dissipative characteristics of the bearings when changing speeds, corresponding to real working conditions. Therefore, known methods do not provide high precision determination of the dissipative characteristics of the bearings.

Known the closest to the technical nature of the proposed technical solution is the way to identify the dissipative characteristics of the bearings, wherein one of the rings of the bearing load constant radial force, and the other lead to oscillatory motion is with predetermined frequency and amplitude using Electromechanical systems, made on the basis of a synchronous motor with an active rotor and two windings on the stator, one of which is connected to the constant current source and the second source of alternating current, measure the current in the second winding, hope its the first and third harmonics, the amplitude of the velocity fluctuations, the phase shift between dynamic variables, additional moment caused by the higher harmonics, and calculate the moment of friction force according to the formula

where J is the moment of inertia of the oscillating part;

ω frequency fluctuations;

θmthe amplitude of the velocity fluctuations;

Md- extension torque of the electric motor;

I1, I3- amplitude respectively of the first and third current harmonic;

ψmdesign factor-dependent stator windings data and characteristics of the permanent magnet rotor;

ϕ - the phase shift between dynamic variables (current and speed). (Kopeikin A.I., Malafeev, S. Identification of the characteristics of the Electromechanical friction in the system // problems of technical management in the regional energy sector. Collection of articles of materials of scientific-technical conference. - Penza, Publisher PETIT, 2000. - S-153).

There is a method allows to determine the moment of friction forces in the bearings under conditions of vibrations the deposits, providing accounting complicated nonlinear dependence of the moment of force of friction on the speed throughout the range of speed change. However, the known method, first, based on the use in the calculations, only the first and third harmonics of current and does not take into account other higher harmonic currents, except the third, second, involves precise measurement of the first and third harmonics of current and additional moment Md, error definitions which depend on many uncontrollable factors, and, thirdly, it provides high accuracy measurements only when the constancy ψmand J, which are in the process of measurement can be changed.

Therefore, the disadvantage of this method of identification dissipative characteristics of bearings - low measurement accuracy.

The purpose of the present invention is the improved accuracy of the measurements.

This objective is achieved in that in the known method for the identification of the dissipative characteristics of the bearings, wherein one of the rings of the bearing load constant radial force, and the other lead to oscillatory motion with predetermined frequency and amplitude using Electromechanical systems based on the synchronous motor with an active rotor and two windings on the stator, one of which is under Lucena to the constant current source, and the second AC power source and measure the current in the second winding, additionally measure the angular velocity of oscillation of the rotor and calculate equivalent dissipative coefficient as the product of a constructive factor of the motor on the ratio of the average for the period of oscillation of the value of works of current speed to average for the period of oscillation of the square of the velocity.

Compared with the closest similar technical solution the proposed solution has the following new operations:

- measure the angular velocity of oscillation of the rotor;

- calculate equivalent dissipative coefficient as the product of a constructive factor of the motor on the ratio of the average for the period of oscillation of the value of works of current speed to average for the period of oscillation of the square of the velocity.

Therefore, the claimed technical solution to meet the requirement of "novelty".

When implementing the present invention increases the accuracy of measurement of the dissipative characteristics of the bearing by increasing the accuracy of calculating the equivalent dissipative factor based on the measured values of the alternating current in the second winding and the angular velocity.

Therefore, the proposed solution meets the requirement "the positive effect is.

For each distinctive feature conducted a search of the known technical solutions in the field of electrical engineering, automation and electric drive.

The operation of measuring angular velocity in similar devices are not detected.

The operation of calculating the equivalent dissipative coefficient as the product of a constructive factor of the motor on the ratio of the average for the period of oscillation of the value of works of current speed to average for the period of oscillation of the square of the velocity in ways similar purpose is also not found.

Thus, these characteristics provide the claimed technical solution according to the requirement of "substantial differences".

The essence of the proposed method is illustrated by a drawing, which shows: 1 - the test bearing; 2 - synchronous motor containing the active rotor with permanent magnets 3, the first 4 and second 5 windings on the stator; 6 - device loading bearing radial force; 7 - DC power supply; 8 - sensor angular velocity of the rotor; 9 - current sensor (measuring shunt); 10 measuring signal amplifier shunt; 11 - current amplifier windings of the motor; 12 - speed control of the engine; a 13 - block speed setting of the engine; 14 - computing device.

In accordance with the proposed method Ident is the codification of dissipative characteristics of the bearings, wherein one of the bearing rings 1 load a constant radial force using a loading device 6, and the other lead to oscillating motion with a given constant frequency and amplitude using Electromechanical systems based on the synchronous motor 2 with an active rotor 3 and the two windings on the stator (4 and 5), one of which (4) is connected to the constant current source 7 and the second (5) to the AC power source 11, measure the AC current in the second winding 5 through the current sensor (shunt) 9 and the measuring signal amplifier shunt 10, the measured angular velocity with the angular rate sensor 8 and calculate the equivalent dissipative coefficient as the product of a constructive factor of the motor on the ratio of the average for the period of oscillation of the value of works of current speed to average for the period of oscillation of the square of the velocity by computing device 14. The speed and frequency of the oscillations is carried out using a block job 13, stabilization of oscillation is performed using a controller 12, one input of which is fed the output signal of unit assignments 13, and on the other a feedback signal from the output of the angular rate sensor 8.

To explain the proposed method, we consider the process of vibrational magic cube MOV whom I system when the driving force M(t) and nonlinear viscous friction. The differential equation of this system is

where J is the moment of inertia of the rotating elements of the system;

- time dissipative forces due to friction;

with the stiffness of the vibrating system;

M(t) - mechanical point of driving force;

ϕ - the angle of rotation.

To solve equation (1) will use the method of energy balance, i.e. we replace the nonlinear momentequivalent energy linear time. Factor βedetermine from the condition of equality of the works performed both points in one period of oscillation:

From the expressions (2) determine the equivalent dissipation factor:

The integral in the numerator of equation (3) is the work for the period of oscillation against the moment of friction force, which can be defined by the formula

In Electromechanical oscillatory system with a synchronous motor mode of the harmonic oscillations of the electromagnetic torque proportional to the current in the winding (Kopeikin A.I., Malafeev SR Controlled Electromechanical oscillation system. - Vladimir, Posada, 2001. - 28 S.)

M(t)=ki,

where k is the structural coefficient of the motor, depending on the magnetic flux generated by the permanent magnets on the rotor, and the number of turns of stator windings;

Hence, the equivalent dissipative coefficient can be defined by the formula:

Calculation of equivalent dissipative coefficient βeby the formula (4) is performed in the computing device 14, which can be used by the microcontroller.

Thus, to determine the equivalent dissipation factor measurement is used only two variables - current and speed, and the computational procedure is carried out by the exact formula (4) using error correcting operation of integration. Under these conditions provides a high accuracy of determination of equivalent dissipative coefficient.

Experimental verification of the proposed method to determine the dissipative characteristics of rolling bearings No. 27 with an outer diameter of the outer ring 22 mm and a bore diameter of inner ring 7 mm showed that the measurement error does not exceed 0.5%.

Thus, using the known method of identification of dissipative characteristics of the bearings, wherein one of the rings of the bearing load is permanent radial force, and the other result in oscillatory motion with predetermined frequency and amplitude using Electromechanical systems based on the synchronous motor with an active rotor and two windings on the stator, one of which is connected to the constant current source and the second source of alternating current, and measure the AC current in the second winding, additional measurements of the angular velocity of the rotor and calculating the equivalent dissipative factor works as a constructive factor of the motor on the ratio of the average for the period of oscillation of the value of works of current speed to average for the period of oscillation of the square of the speed improves the accuracy of determination of equivalent dissipative coefficient.

The use of the proposed method in acceptance and research trials bearings will improve the accuracy and efficiency of identification of dissipative characteristics.

The way to identify the dissipative characteristics of the bearings, wherein one of the rings of the bearing load constant radial force, and the other lead to oscillatory motion with predetermined frequency and amplitude using Electromechanical systems based on the synchronous motor with an active rotor and DV of the two windings on the stator, one of which is connected to the constant current source and the second source of alternating current, and measure the AC current in the second winding, characterized in that it further measure the angular velocity of oscillation of the rotor and calculate equivalent dissipative coefficient as the product of a constructive factor of the motor on the ratio of the average for the period of oscillation of the value of works of current speed to average for the period of oscillation of the square of the velocity.



 

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