RU1798676C - Device for nondestructive testing of metal articles - Google Patents

Abstract

The invention relates to the field of non-destructive testing of ferromagnetic materials and can be used in mechanical engineering and ferrous metallurgy. The purpose of the invention is to improve the accuracy in controlling the physicomechanical properties of ferromagnetic materials - due to the fact that the device for non-destructive testing of metal products, comprising an inductive transducer, a capacitive gap transducer, a gap measurement channel and a recorder, is equipped with a multiplier connected between the inductive transducer and the registrar, and the gap measurement channel is made in the form of a series-connected frequency-controlled oscillator into the oscillating circuit of a cat A capacitive gap converter, a frequency divider, a synchronous filter, a rectifier, an amplifier, and a functional unit, the output of which is connected to the second input of the multiplier, a series-connected phase detector and a digital memory unit, the output of which is connected to the control input of a frequency-controlled oscillator, is turned on as well as a clock generator, the output of which is connected to the outputs of the synchronous filter and phase detector, and through the .key to the second input of the memory unit. 3 ill.

Description

The invention relates to the field of non-destructive testing of products from ferromagnetic materials and can be used in mechanical engineering and ferrous metallurgy.

The aim of the invention is to increase accuracy in controlling the physicomechanical properties of ferromagnetic materials.

Fig. 1 shows a block diagram of a device for controlling the physicomechanical properties of ferromagnetic materials; in FIG. 2 - graphs explaining the operation of the device; in FIG. 3 - one of the possible designs of the inductive converter used in the device.

The device comprises an inductive converter 1; a capacitive gap sensor 2 fixed thereto; recording device 3; a multiplier 4, connected between the output of the inductive converter 1 and the input of the recording device 3. The output of the generator 5, in the oscillatory circuit of which is connected a capacitive sensor of the gap 2, is connected through the frequency divider 6 to the input of the synchronous filter 7. The output of the synchronous filter 7 through rectifier 8, the amplifier 9 and the functional block 10 is connected to the second input of the multiplier 4. The output of the phase detector 11, the inputs of which are connected to

Yoo oo

CX

XI CN

the frequency divider 6 and the output of the clock generator 12 through the memory block 13 is connected to the control input of the generator 5, and the control input of the digital memory 13 through the key 14 is connected to the output of the clock 12

It has been experimentally established that the output signal of the inductive converter as a function of the gap is most accurately approximated by the expression:

Unp Uo pr (a # + b 5 + 1),

0)

where Uonp is the converter signal with a gap equal to 0;

d is the size of the gap;

a, b are constants determined by the design of the sensor.

Equation (1) is obtained by processing the experimental data using the least squares method. For the converter used by the authors (see Fig. 3), the constants a and b are equal to 0.031 0.290, respectively.

As follows from expression (1), in order to tune from the influence of the gap, the output signal of the inductive converter must be multiplied by a correction signal

Corps a b2 + bd + 1.

(2)

To this end, by means of a capacitive sensor 2, the changes in the gap are converted into changes in the frequency of the generator 5.

The frequency of the generator 5 is chosen high in order to obtain a high sensitivity of the capacitive sensor to the gap. However, signal processing is more convenient and more accurate at a low frequency. Therefore, using a frequency divider 6, the frequency of the generator 5 is divided by the number N.

In a particular device tested by the authors, the frequency of the oscillator 5 is chosen to be 5 MHz, (with d), the division coefficient is N 100. In addition, the frequency divider 6 limits and stabilizes the pulse amplitude, which is necessary to obtain high conversion accuracy.

The device operates as follows;

The frequency of the generator 5, determined by the capacitance of the gap 2 sensor, and therefore, the gap d, is fed to the input of the frequency divider 6. G of the output of the frequency divider 6 is a pulse train fed to the input of the synchronous filter 7 and one of the inputs of the phase detector 11.

The resonance frequency of the synchronous filter 7 is equal to the clock frequency coming from the output of the clock 12. The synchronous filter 7 is necessary to obtain a signal that is directly proportional to the size of the gap. The conversion process using the filter is shown in FIG. 2, which shows the dependence of the relative change in the frequency of the oscillator 5 on the gap (curve 1), the dependence of the relative change in the transfer coefficient of the synchronous filter 7 on the relative change in the frequency of the generator 5 (curve 2), the dependence of the relative change in the transmission coefficient of the synchronous filter 7 on the gap (curve 3) ) As can be seen from FIG. 2 the nonlinearity of curve 1 is compensated by the nonlinearity of curve 2. As a result, the output of the synchronous filter

receive a signal linearly dependent on the gap. The linear nature of dependencies is ensured by equality

f

res

X-ray / N,

(3)

where Tres is the resonance frequency of the synchronous filter;

 - the frequency of the generator 5 with an infinitely large gap;

0 N - division factor of the frequency divider 6.

This is achieved by periodically adjusting the frequency of the generator 5 using the voltage supplied to the control

5 the input of the generator 5 from the output of the digital memory unit 13. The adjustment of the generator 5 is carried out by closing the key 14 in the absence of controlled material. In this case, a sequence of clock pulses begins to arrive at the control input of the digital block of memory 13. At a generator frequency of 5 fpea N, there is no signal at the output of the phase detector 11, and at the output of the digital memory unit 13, the control voltage value necessary to fulfill equality (5) is set. In the case of a deviation of the frequency of the generator 5 up or down at the output of the phase detector 11

0, a mismatch signal corresponding to the polarity arrives at the storage input of the digital memory unit 13. A control voltage is generated at the output of the digital memory unit 13.

5, an increase or decrease in which respectively increases or decreases the frequency of the generator 5. As a result of the adjustment, equality (3) is restored. The duration of the process does not exceed 0.5 s., After which the opening of the key 14 is stopped

a cycle of adjusting the frequency of the generator 5. In this case, clock pulses are not supplied to the control input of the digital memory unit 13, the digital memory unit 13 stores the generated control voltage in the form of a binary digital code. This ensures long-term storage of the control voltage at the control input of the generator 5,

The output of the synchronous filter, directly proportional to the gap d, is rectified, amplified, and fed to the input of function block 10. Function block 10 generates a correction signal defined by expression (2). The result of the multiplication of the correction signal and the output signal of the inductive converter 1, independent of the instability of the working gap, is supplied to the recording device 3.

Thus, the device provides an increase in the sensitivity of the correction signal to the gap with an increase in the gap, which eliminates undercompensation in the gaps, more than the nominal value, and re-recombination in the gaps, less than the nominal value. Long-term storage of the control voltage at the control input of the generator 5, in the circuit of which a capacitive gap sensor is included, with its periodic adjustment, reduces the imbalance of the device. As a result

the accuracy of controlling the physicomechanical properties of ferromagnetic materials is improved.

Claims (1)

Formula and goiter re shadow A device for non-destructive testing of metal products, comprising an inductive transducer, a capacitive gap transducer, a gap measurement channel and a recorder rigidly attached to it, characterized in that, in order to increase the accuracy in controlling the physicomechanical properties of ferromagnetic materials, it is equipped with a multiplier included between the output of the inductive converter and the recorder, and the channel-measurement of the gap is made in the form of series-connected frequency-controlled oscillator into the oscillator whose circuit includes a capacitive gap converter, frequency divider, synchronous filter, rectifier, amplifier, and function block, the output of which is connected to the second input a multiplier, a series-connected phase detector and a digital memory unit, the output of which is connected to the control input of a frequency-controlled oscillator, as well as a clock generator pulses, the output of which is connected to the inputs of a synchronous filter and a phase detector, and through a key, to the second input of a digital memory unit.