SU1425043A1 - Method of controlling the accuracy of displacement - Google Patents

Abstract

The invention relates to mechanical engineering, primarily the operation of kinematic gears of drives of metal-cutting machine tools. The purpose of the invention is to increase the accuracy of the interfacing of the frictional contact due to the operational analysis of its dynamic quality. For this, real-time analysis of the amplitudes of the natural oscillations of the system, excited in the elastic system of the friction contact, is carried out, as they most fully characterize the dissipative properties of the friction contact. By changing the diagnostic signal, the magnitude of the sylg of the normal pressure in the frictional contact is controlled. 2 Il. 1 tab.

Description

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The invention relates to machine tools, mainly to the problems of exploiting the kinematic gears of machine tool drives, and is intended to control the operation of the drive gear by diagnosing the dissipative properties of the friction contact.

The chain of the invention is to increase the accuracy of movement and the efficiency of the function of the friction-free contact due to the operational use of its dynamic quality. j FIG. a diagram is shown, a pea of the proposed method, in FIG. 2 - logarithmic amplitudes - i | io-4acTOTHbie characteristics of the freak-ijtHOHHOfo contact. I The accuracy of moving 1Gi can be realized, for example, by a device containing a vibrator 1, which is mounted on a slider 2 and powered by a generator L, a vibration sensor 4 installed 1g in the zone of frictional contact formed by a slider 2 and guides 5, with In this way, the output of the generator 3 is electrically connected to the input of the amplifier 6, the low-frequency filter 7 and the scalar intelligent block 8; The second entrance of the scalar multiplication unit 8 is connected to the sensor 4 vibrations, the outputs of the amplifier 6 and the low frequency filter 7 are connected to the first normalization prttoKy 9, the output of which is |; connected to the input of the second unit 10, the second input of the second unit - | ca 10 nsGrmirovaniya connected to the output of the block In scalar multiplication, the output of the second unit 10 of the normalization is connected to the input of the block 11 of the control, the output is connected to the regulating element 12, for example, throttle-But-distribution type, which regulates the oil pressure in the hydraulic unit re 13 slider 2.

The invention is based on the features of the dynamic characteristics of the elastic system of frictional contact and the interaction of various effects on the elements of the dynamic system. The friction contact system belongs to the category of principally unstable. In the absence of regular external disturbances, frictional oscillations arise. Random impact modifies the strength of friction, which

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. leads to a change in the contact deformation and, accordingly, the elastic force of the actuator and the dissipative properties of the friction contact. The area of factors that influence the dynamic quality of the VO and determine the characteristic of frictional contact (elastic, plastic, viscous, hydrodynamic, mechanical, intermolecular interaction) has found its reflection in the logarithmic amplitude characteristic of the frictional contact. Thus, in the presence of fluid friction, the applied load varies in proportion to the speed, while the natural vibration frequency (fp) varies in amplitude, indicating that there is a dissipation in the system (for example, damping). Thus, the change in the load impedance in the area of the Frictional contact converts the process of elastic interaction into dissipative, which is characterized by damping of the amplitude of natural oscillations (Fig. 2 and), and thus the quality factor of the frictional contact, tuned to the frequency of the own oscillation ( Fig. 2, curve 11)

Consequently, at any given time, the difference in the amplitudes of natural oscillations by measuring the amplitude of oscillations excited from outside in the frequency range fp ± 0.5fp and in the amplitude range (o, 7 ... O, 9) Ash, i.e. not exceeding the amplitude of the intrinsic noise of the Ac1 system, they receive a diagnostic signal indicating the dynamic quality of the friction contact, its dissipative properties and, by supplying it to the control unit, control the force of the normal pressure in the contact, which in turn leads to the achievement of the required accuracy.

The limiting values of the amplitude of the imposed vibrations and frequencies are determined by the aim of the invention and by ensuring a low level of energy consumption, as well as the TexHi-gs possibilities of its realization.

When the amplitude of the imposed vibrations is less than the level of 0.7 of the noise level of the actual contacting process, the proposed method does not allow to increase the accuracy of movement, which is due to the insufficient sigal level obtained from the contact zone and, as a result, the lack of response of the system ..

An increase in the amplitude of more than 0.9 of the noise level leads to an increase in energy consumption during the implementation of the method and does not allow an increase in accuracy, since in this case the system responds randomly.

The proposed frequency range is due to the dynamically active frequency range of the natural oscillations of the elastic system of the friction contact.

The narrowing of the proposed frequency range leads to the need for a very accurate experimental determination of the natural frequency of oscillations of each frictional contact (in the elastic system of an object), and the expansion of the range is impractical due to the increase in time required for scanning in this frequency range and, ultimately, reducing the effectiveness of the method.

Movement accuracy control is as follows.

The natural frequency fp and the amplitude of the noise Ach of the dynamic system of the friction contact are measured.

In the zone of frictional contact between the slider 2 and the guides 5, they are excited by a vibrator, which is fed, for example, from oscillator frequency generator 3, oscillations in the frequency range, 5fp with amplitude (0.7. 0.9) Ash.

The signal A from the output of the vibration sensor 4, for example, of the piezoelectric type, installed in the zone of frictional contact, is measured and fed to the input of the scalar multiplication unit 8.

The signal B, which characterizes the oscillations excited by the vibrator I in the zone of frictional contact, is measured and is also fed to another input of the scalar multiplication unit 8.

In block 8, scalp multiply operation is performed, whereby the signal C is extracted as a reaction of frictional contact to external excitation due to the operation of the vibrator 1.

Signal B is normalized at the average level in the first normalization block 9, having preamplified it in amplifier 6 with an adjustable coefficient

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The volume is amplified and the average level of signal B in the low-pass filter 7 is raised.

Next, the operation of normalizing the signal C, which characterizes the reaction of the frictional contact to external excitation, is performed in relation to the normalized by the average level signal B in the second normalization unit 10, to the inputs of which the indicated signals are supplied.

By means of the second normalization operation, in block 20, signal 5 is selected, which characterizes the dynamic quality and dissipative properties of the friction contact in real time.

By changing the diagnostic signal D, the dissipative properties of the frictional contact are diagnosed and the magnitude of the force of the normal pressure in the frictional contact between the slide 2 and the rails 5 is controlled, giving the signal D to the control unit 11, and. - by means of the input signal from block 11, the regulating element 12 is controlled, for example, the oil pressure in the hydraulic bearing 3 of the friction terminal, so that a change in signal D causes a corresponding change in the oil pressure in the hydraulic bearing J3.

PRI me R. In order to improve the accuracy of the proposed method, the slider of the UT16FZ lathe with CNC type Luch-21 and the upgraded oil supply device for the slide slide hydrocores used an installation containing the following blocks: vibrator control rack SUPV-0.1A, vibrator type VED-10, accelerometer type The IC-318, an amplifier, a low-frequency filter, a scalar multiplication unit, as well as normalization blocks, executed in the swing of dividers.

Scanning in the ff ± 0.5fp frequency range was done manually.

The accuracy of the stop was measured by the monitor.

The table shows the effect of the amplitude of the excited vibrations on the accuracy of the movement.

Claims (1)

5 claims The method of controlling the accuracy of movement mainly in the moving elements of the drives of metal-cutting five 0 five 0 {tanks, consisting in the imposition of | E | ibrations in the direction perpendicular of the p-plane of the slide, that is, with the aim of r: to determine the accuracy of the movement and the effect of fric-idone contact due to operatoto-} foro analysis of its dynamic band lecTBa, vibrations are excited with an amplitude not exceeding the amplitude of the sound of the actual contact process at. A (0.7 ...) And where A is the amplitude of the excited vibrations, ASH is the amplitude of the noise of the actual contacting process, in frequency 9.0 50 9.0 60 8.0 6.0 7.0 8.5 70 80 90 100 9.5 software 12.0 120 12.0 130 Note, range from 0.5fp to 1.5 fp. where fp is the natural frequency of the system, while the amplitude of the forced oscillations is measured, the systems separate the system’s response to external disturbances, normalize the received signal relative to the normalized signal, excitation, and change the normalized output signal to determine the dissipative properties of the friction contact taking into account the factors, the magnitude of the force of the normal pressure in the frictional contact is controlled, for example, the pressure of the oil in the hydrospore. the system does not respond to disturbances Also The system controls The system randomly responds to BOSMj emiH Same || The measurements were carried out at the speed of movement of the slider 50 / Mnn, the amplitude of the real process is 100 mV.  V R SuSpamiu frequency Fi.y