SU1597232A1 - Apparatus for generating mechanical vibrations of ultrasonic frequency - Google Patents

Abstract

This invention relates to the field of ultrasound technology. The aim of the invention is to increase the efficiency of the process unit and the quality of the ultrasonic treatment. The goal is achieved in that a known device comprising an ultrasonic frequency driving oscillator 1, a power amplifier 2, an electromechanical transducer 3 and a system for optimizing the mechanical oscillation excitation mode in amplitude and frequency based on introducing measuring pauses into the operation of the power amplifier 2, synchronization of the pause with the mains alternating voltage feeding the power amplifier 2. This eliminates the parasitic low-frequency envelope of ultrasonic mechanical vibrations, reducing the efficiency of the entire device and the quality of the technological effects of the vibrations. 2 Il.

Description

g

sd

with

tsD

oo to

The invention relates to an ultrasound technique and is intended to work in various areas of the national economy using technological processes using ultrasound.

The aim of the invention is to increase the efficiency of the device and the quality of processing by eliminating the low-frequency parasitic oscillations of an electromechanical converter.

, 1 is a block diagram

devices to obtain mechanical fictitiously,

And, and the output element And 6 connected to the input of the divider 12 frequency.

The device works as follows.

Converter 3, converting the electrical oscillations of the ultrasonic frequency into mechanical oscillations, together with the concentrator and the instrument to - is a resonance

oscillatory system. Due to. of this, it has a frequency of natural oscillations (resonant frequency), by which its excitation is the most

ultrasonic frequency oscillations; in fig. 2 - timing diagrams for the operation of the device. . The device contains a master oscillator 1, power amplifier 2, electromechanical converter 3 first, second 5 and third 6 elements And, rectifier 7, controlled by switch 8, integrators 9 and 10, dividers 11 and 12 frequencies, driver 13-15 pulses, an inverter 16, a limiter 17, a differential amplifier 18, and comparison devices 19 and 20.

The output of the master oscillator 1 is connected to the first inputs of logic elements I and 6, the output of the element I is connected to the input of power amplifier 2, the output of which is connected to the input of converter 3 and also to the inputs of rectifier 7 and limiter 17, the output of rectifier through switch 8, the integrator E and the device 19 comparison is connected to the control input of the amplifier 2, the output of the limiter connected to the first input element And 5, the output of which is connected to the input of the frequency divider 11, the input of the imaging unit 13 is connected to the energy input of the amplifier 2 power and connected to the mains, the output of the imaging unit 13 is connected to the inputs of the formers H and 15, the output of the imaging device is connected to the input of the inverter 16, the control input of the key 8 and the second inputs of the elements 5 and 6, the output of the imaging device 15 is connected to the control inputs dividers 11 and 12 frequencies, the inputs of which are connected to the opposite phase inputs of the differential amplifier 18, the output of which

20

25

thirty

35

40

45

50

In order to automatically maintain the optimum mode at the frequency and excitation level, the electrical parameters of the electrical transducer during periodic deviations from the excitation sources - power amplifier 2 and, according to the results of measurements during the EMF curve, the excitation level is set. The power amplifier 2 is disconnected from the converter 3 by locking the active elements of the power amplifier by preventing them from sending control signals from the master oscillator 1. To eliminate the influence on the results and measurements of the parasitic modulation of the amplifier's voltage. 2, a part of the multiple frequency of the mains supplying it through the energy input of amplification amplifier 2, synchronization of the pauses of the mains voltage by means of a torque generator 13 was introduced.

The master oscillator 1 generates rectangular pulses of ultrasound frequency, which are transmitted through the element 4 to the main input of the amplifier 2 power. After amplification and isolation of the main harmonic from the output of the amplifier 2, the voltage is applied to the electromechanical transducer l 3.

The signal from the output of the inverter 16 to the second input of the element I, periodically interrupts the arrival of rectangular pulses from the master oscillator 1, the input of the amplifier 2 power, resulting in the output voltage

connected through the integrator 10 and the device-55 lit. el forms a pause. Duration 20 comparison with the input of the master oscillator 1, the output of the inverter 1b is connected to the second input of the element

The duration of the pause is determined by the duration of the rectangular impulse to the output of the former AND (Fig. 2c). Launch

 Fictitiously

72324

And, and the output element And 6 is connected to the input of the divider frequency 12.

The device works as follows.

The transducer 3, which converts the electrical oscillations of the ultrasonic frequency into mechanical vibrations, together with the concentrator and the tool, is a resonant

oscillatory system. Due to. of this, it has a natural frequency (resonant frequency), at which its excitation is most effective,

In order to automatically maintain the optimum frequency and excitation level, the electrical parameters of the electromechanical transducer are measured during its periodic deviations from the excitation source - power amplifier 2, and the frequency and level of the excitation are set based on the results of measurements during the parameters of the EMF curve. The power amplifier 2 is disconnected from converter 3 by locking the active elements of the power amplifier by stopping the supply of control signals from the master oscillator 1 to them. To eliminate the influence of the measurement results of the parasitic modulation of the output voltage of the amplifier. 2 with a frequency that is a multiple of the frequency of the mains supplying through the energy input of the amplifier 2, the synchronization of the pauses with the mains voltage by means of the shaper 13 is introduced.

The master oscillator 1 generates square ultrasonic frequency pulses, which are fed through the element 4 to the main input of the amplifier 2 power. After amplification and extraction of the main harmonic from the output of the usi-. The voltage 2 is fed to the input of the electromechanical converter 3.

The signal from the output of the inverter 16 to the second input of the element I periodically interrupts the arrival of rectangular pulses from the master oscillator 1 to the input of the power amplifier 2, with the result that a pause is formed in the output voltage of the amplifier. The duration of the pause is determined by the duration of the rectangular pulse at the output of the former And (Fig. 2c). Launch

the latter is carried out by the front of the output pulse of the former 13, which generates a sequence of sawtooth pulses (Fig. 26) and is launched in turn by the network voltage (Fig. 2a). The pulse frequency of the imaging unit 13, depending on the starting method and the phase of the network, may differ from the network frequency by an integer number of times (in Fig. 26, the frequency of the pulses is twice the network frequency).

During a pause in the operation of the amplifier 2, its output terminals, directly connected with the input terminals of the electromechanical transducer 3, are affected by EMF caused by the free damped oscillations of the latter (Fig. 2d). The reason for the EMF is determined, depending on the type of transducer, by the reverse magnetostrictive or direct piezoelectric effects. At the same time, the period of the EMF acting during the pause determines the natural oscillation frequency (mechanical resonance frequency) of the electromechanical transducer, and the amplitude of the emf of damped oscillations is unambiguously related to the amplitude of its forced oscillations preceding the introduction of the pause. The auto-tuning of the frequency of the master oscillator 1 to the frequency of the mechanical resonance of the transducer 3 is carried out by forming a pulse during a pause, the duration of which is equal to the duration of a whole number of periods of free oscillation EMF. For this purpose, the voltage from the output of the amplifier 2 is supplied through the amplitude limiter 17 and the element. And 5 to the main input divider frequency 11. The second input element And 5 receives pulses from the output of the shaper 14 (Fig. 2B). A bounded signal passes to the input of the divider 11 during the pause in the amplifier operation (Fig. 2e). The control inputs of the divider 11 are fed by counting pulses (Fig. 2e), which prohibit the counting of the input pulses for the duration of which the transients processes at the output of amplifier 2 after introducing a pause. The pulse duration of the delay is determined by the parameters of the pulse driver 15 and is set to 1-4 periods of the fundamental frequency. Shaper 15 is started by those

1597232

0

same fronts as the launch of shaper 14, at time t, (Fig. 2). After the end of the impulse impulse (time t), the first positive edge (time t) switches the divider output to state 1. After counting the specified number of pulses, the counter is transferred to the state O (time tj). In the next pause (time t), the processes are repeated. At the same time, at the output of divider 11, the voltage form is a periodic equalization of pulses of the same amplitude, the duration of which is equal to the duration of an integer number of periods of free damped oscillations of the converter 3. The average value of the voltage at the output of the divider 11 is

TT UiijitK

 “EP- and is the voltage value of a logical unit;

t is the pulse duration equal to an integer number of periods n free damped oscillations of converter 3;

five

0

TP When

repetition period of pauses, multiple to the period of the network T .. constant values and, / ,, and T

35

0

five

I p

voltage, and, J, is proportional to the duration of the period of free damped oscillations (interval tj-. To form the reference voltage, rectangular control pulses from the output of the master oscillator 1 through element 6 enter during pauses to the input of the separator 12 (Fig. 2h) controlled by the generator 15 parallel to the divider 11. At the output of the divider 12, pulses are formed, the mean value is proportional to the duration of the period of control pulses

TI - and.- „"

f2cp

0 where t, is the duration of the interval tj in FIG. 2i, equal to an integer number of periods n control pulses at the output of the master oscillator 1. e. Voltage U ,, and U, using

differential amplifier 18 is subtracted. The integrator 10 performs an average of the difference.

C

U 4

10 Wed f (Cp

r t (tp-ty).

With equal control frequency and natural frequency t; ty and u ((J cf. When the frequency leaves the resonance, an error signal appears, which acts through the comparison device 20 on the frequency of the master oscillator 1 in such a way as to bring it closer to the mechanical resonance frequency of the converter 3. By changing the voltage U, the voltage is set to 1. average (nominal) control frequency, 5

The second channel of the optimization system

 The drive mode of the converter 3 according to the amplitude of mechanical oscillations is dialogic used in the known device. The difference lies in the control of the key 8, in the tight binding of the moment of its opening to a certain phase of the network alternating voltage. The channel optimization, the amplitude of the mechanical oscillations consists of 25

the rectifier 7, the controllable key 8, the integrator 9, the comparator device 19 and the controlled ycilit 2 power. A controlled pulse of the driver 1 key 8 transmits the signal from the amplifier Z power output, rectified by rectifier 7, to the input of the integrator 9. The latter selects the average value of this signal a. It is proportional to the amplitude of the –sg-mechanical oscillations of the transducer 3, since it is formed due to the emf of its free oscillating oscillations uniquely associated with the forced oscillations. After comparison in 4Q

the device 19 with the set voltage b is received the error signal, which acts on the control input of the amplifier 2 power, changing. its gain factor. As a result, the level of mechanical oscillations of the transducer 3 specified by the installation is maintained.

When the amplifier 2 is powered from the AC mains, pulsations with a network frequency or a multiple of it are present in its output voltage. They

A disturbing effect, which manifests itself in the form of parasitic low-frequency oscillations, is introduced into the operation of the system for stabilizing the amplitude of mechanical oscillations. In the proposed device, this possibility is excluded due to the tight binding of the measuring

pauses to the AC mains voltage curve that is the source of the disturbance.

The effectiveness of the technical solution is to increase the efficiency of the entire device by increasing the accuracy of maintaining the optimal mode both in frequency (operation only at the resonant frequency) and in amplitude (operation at a given amplitude of mechanical oscillations without deviations of more or less ), and the quality of the technological impact due to the exact correspondence of the amplitude of oscillations to the requirements of the technological process. In particular, this requirement must be fulfilled during ultrasonic polymer welding.

F. formula

A device for obtaining mechanical vibrations of ultrasonic frequency, containing (its electromechanical transducer, power amplifier, master oscillator, first, second and third elements AND, limiter, transmitter, control key, first and second integrators, divider, frequencies, first and second devices the comparison, in which the output of the master oscillator is connected to the first input of the first element I, the output of the first element H is connected to the input of the power amplifier, the output of which is connected to the inputs of an electromechanical conversion The output switch, rectifier and limiter J is the output of the rectifier. The control key, the integrator and the first comparator device are connected to the auxiliary input of the power amplifier 5, the output of the limiter is connected to the first input of the second element I, the output of which is connected to the input of the frequency splitter, The integrator output through the second comparator is connected to the input of the master oscillator, characterized in that, in order to increase the device efficiency and the quality of the technological effect of the ultrasonic vibrations, the first, second and retiy pulse formers, inverter, second frequency divider and differential amplifier, while the input of the first driver is connected to the power input of the power amplifier connected to the mains, the output of the first driver is connected to the inputs of the second and third driver,: the output of the second driver is connected via an inverter to the second input of the first element And, as well as to the control input of the key and the second inputs of the second and third elements And, the output of the third driver is connected to the control

ten

The inputs of the first and second frequency dividers, and the output of the third element I are connected to the input of the second frequency divider, the outputs of the first and second frequency dividers are connected to the main-voltage inputs of the differential amplifier, the output of which is connected to the input of the second integrator.

network

Claims (1)

The claims “A device for producing mechanical vibrations of an ultrasonic frequency, comprising an electromechanical transducer, a power amplifier, a master oscillator, first, second and third elements AND, a limiter, 20 rectifier, a controlled key, first and second integrators, a frequency divider, first and second devices comparison, in which the output of the master oscillator is connected to the first input of the first element And, the output of the first element And is connected to the input of the power amplifier, to the output of which the inputs are connected by an electric converter, rectifier and 'limiter, rectifier output Through a controlled key, integrator and first comparison device connected to an additional input of the power amplifier, the output of the limiter connected to the first input of the second element And, the output of which is connected to the input of the frequency divider, the output of the integrator through the second comparison device connected to the input of the master oscillator, characterized in that, in order to increase the efficiency of the device and the quality of the technological impact of ultrasonic vibrations, it is introduced We have the first, second and third pulse shapers, an inverter, a second frequency divider and a differential amplifier, while the input of the first driver is connected to the energy input of the power amplifier connected to the mains, the output of the first driver is connected to the inputs of the second and third drivers, the output of the second driver connected through an inverter to the second input of the first element And, as well as to the control input of the key and the second inputs of the second and third elements And, the output of the third driver is connected to the control 1597232 by the input inputs of the first and second frequency dividers, and the output of the third element And is connected to the input of the second frequency divider, the outputs of the first and second frequency dividers are connected to the antiphase inputs of the differential amplifier, the output of which is connected to the input of the second integrator.