SU1668928A1 - Device for complex nondestructive check - Google Patents

Abstract

The invention relates to non-destructive testing and can be used to measure the thickness of a coating. The purpose of the invention is to increase the reliability of control by suppressing the influence of several interfering factors. The goal is achieved by the fact that the device containing high and low frequency generators, eddy current transducer, high frequency and low frequency channels and information presentation unit is equipped with a first switch whose inputs are connected to generators, and the output is connected to the input of the eddy current transducer connected in series with an eddy current transducer, two additional amplifiers and a second switch, two memory blocks and a control unit, and each of the measuring channels in complete in the form of a serially connected first amplifier, which is simultaneously a reference voltage unit, the input of which is connected to the output of a compensation converter, an amplitude controller and a phase shifter, the output of which is connected to the first input of the adder, the second input of which is connected via an additional amplifier to the output of the eddy current converter , the output of the adder is connected to the first input of the phase difference meter, the second input of which is connected to the output of the first amplifier, the outputs of the phase difference meters about their measuring channels are connected to the inputs of the second switch, the outputs of which are connected to two memory blocks, the outputs of which are connected to the information representation unit. 3 il.

Description

The invention relates to non-destructive testing and can be used to measure one of the geometrical or physical parameters of a product with the suppression of the influence of several interfering factors, in particular for the control of multilayer products.

The purpose of the invention is to increase the reliability of control by suppressing the influence of several interfering factors.

Figure 1 shows the block diagram of the device; in fig. 2-year stress curves

a transducer obtained by measuring the thickness of the coating at a frequency of 5.5 kHz; fig.Z - the same, at a frequency of 10 kHz.

The device for multi-parameter non-destructive testing contains low-frequency generators 1 and high-frequency 2, the first switch 3, which alternately supplies both frequencies to the vortex converter 4 and the compensation converter 5, measuring channels 6 and 7, each of which consists of series-connected amplifiers 8. soseso

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its input with the output of the compensation converter 5, the amplitude controller 9, the phase shifter 10, as well as from the amplifier 11 connected by its input to the output of the eddy current transducer 4, the adder 12 connected to the outputs of the phase shifter 10 and the amplifier 11 by its input, meter 13 phase difference connected by its inputs to the outputs of the adder 12 and amplifier 8, the second switch 14 connected by its inputs to the outputs of the meters 13 phase differences of both channels, blocks 15 and 16 of the memory connected by their inputs to the outputs of the second switch 14, serially connected differential amplifier 17 connected by its inputs to the outputs of memory blocks 15 and 16, linearizer 18 and analog-to-digital converter 19, and also control block 20, whose outputs are connected to control inputs of switches 3 and 14 .

Device for multi-parameter non-destructive testing works as follows.

Generators 1 and 2 produce sinusoidal voltages of two frequencies, which by means of switch 3 are fed to sequentially connected eddy current transducer 4 and compensating transducer 5. Signals from eddy current transducer 4 and compensation transducer 5 are simultaneously fed to inputs of measuring channel 6 of lower frequency and measuring channel 7 the higher frequencies in which the selection of a reference point on the complex plane takes place by the formation of a reference voltage with the help of amplifier 8, 9 amplitude controller, phase shifter 10 and vectorial summation by adder 12 with a signal transmitted to the adder 12 from amplifier 11 connected to the eddy current probe 4.

A phase difference meter 13 converts phase shift information between signals from eddy current transducer 4 and compensation transducer 5 into direct voltage, which is switched to blocks 15 by switch 14 and

16 tam. Differential amplifier

17 serves for algebraic summing with different coefficients of signals arriving at its inputs from the outputs of memory blocks 15 and 16.

Linearizer 18 serves to convert a nonlinear voltage-controlled parameter to

linear. The analog-to-digital converter 19 serves to convert the voltage supplied to its input from the linearizer 18 into digital information.

about the size of the monitored parameter. The operation of the switches 3 and 14 is controlled by the control unit 20.

Figure 2 shows the hodographs of transformer converter voltages on a ferrite core, obtained by measuring the thickness of nickel on magnetic steel at a frequency of 5.5 kHz (FIG. 3, at a frequency of 10 kHz). Nickel films 0 to 100 microns thick are used, various modes (current density 1.5 - 5, OA / dm, unannealed and annealed in air, in vacuum), various samples of magnetic steel ZI-811 with a radius of curvature of 0-10 mm, the gap between the transducer and

product ranges from 0-30 microns. As can be seen from the hodographs, the properties of steel of even one grade (EI-811) vary both from sample to sample (first to fourth samples), and within one sample.

The hodographs of the transducer located above nickel on magnetic steel are obtained by measuring the thickness of nickel films at the same point of one sample (the first sample). As can be seen from the hodographs, the properties of nickel also change. The hodographs of the transducer located with a gap above nickel on magnetic steel are obtained by changing the gap between the transducer and nickel at the first

sample The hodographs of the converter, located with a gap and without a gap over nickel on other samples of steel EI-811 (the second to fourth samples), are not shown. In addition, the hodographs of the converter located above nickel on products with a radius of curvature of up to 10 mm are not shown, since they coincide with the hodographs of the converter located with a gap of up to 10 µm above nickel on flat products.

Changes in electrical conductivity and magnetic permeability of nickel are built up in a phase manner, i.e. at each frequency, measurements are taken from such a point in the complex plane (Fig. 2, point A) so that the signal phase does not depend on changes in these interfering factors.

The diameter of the transducer and the frequency are chosen such that the phases of the signals measured from point A relative to the axis imU, with

changes in the properties of the steel, the gap and the radius of curvature are proportional with one coefficient of proportionality, and when the thickness of the nickel coating changes with another. Gains at inputs

Differential amplifier 17 is selected by changing one of them so that the increments of the signals measured from point A at frequencies of 5.5 and 10 kHz when the properties of the steel change, the gap and radius of curvature are the same. The coefficient is determined experimentally using a set of standard samples so that the output of the amplifier suppresses the influence of these interfering factors. Then the output signal of the amplifier does not depend on the change in the interfering factors and is determined only by the value of the monitored parameter — the thickness of the nickel coating.

For rmul and invention n and

A device for multi-parameter non-destructive testing, containing high and low frequency generators, a vortex converter, high-frequency and low-frequency measuring channels, each of which includes an amplifier, amplitude controller, adder, phase shifter, phase meter and reference voltage block, and information representation unit , characterized in that, in order to increase the reliability of control by suppressing the influence of several interfering factors, it is equipped with a first switch, the inputs of which are connected to g generators, and the output is to the input of the eddy current transducer

l, a compensation converter connected in series with the eddy current converter, two additional amplifiers and a second switch, two memory blocks and a control unit, and each of the measuring channels is made of serially connected first amplifier, which is simultaneously whose input is connected to the output of the compensation converter, amplitude controller and phase shifter, the output of which is connected to the first input of the adder, the second input of which is connected Via an additional amplifier to the output of the eddy current converter, the output of the adder is connected to the first input of the phase difference meter, the second input of which is connected to the output of the first amplifier, the outputs of the phase difference meters of both measuring channels are connected to the inputs of the second switch, the outputs of which are connected to two memory blocks, the outputs of which are connected to the information presentation unit, made in the form of serially connected differential amplifier, linearizer and analog-digital conversion the hub and the outputs of the control unit are connected to the control inputs of the switches.

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Claims (1)

Claim A device for multi-parameter non-destructive testing, containing high and low frequency generators, eddy current transducer, high-frequency and low-frequency measuring channels, each of which includes an amplifier, an amplitude regulator, an adder, a phase shifter, a phase meter and a reference voltage unit, and an information presentation unit, characterized in that, in order to increase the reliability of control by suppressing the influence of several interfering factors, it is equipped with a first switch, the inputs of which are connected to the gene to the speakers, and the output is to the input of the eddy current transducer, a compensation transducer connected in series with the eddy current transducer, two additional amplifiers and a second switch, two memory units and a control unit, and each of the measuring channels is made in the form of a first amplifier connected in series, which is simultaneously both the reference voltage unit, the input of which is connected to the output of the compensation transducer, amplitude regulator and phase shifter, the output of which is connected to the first input of the adder, the second input of which is connected through an additional amplifier to the output of the eddy current transducer, the output of the adder is connected to the first input of the phase difference meter, the second input of which is connected to the output of the first amplifier, the outputs of the phase difference meters of both measuring channels are connected to the inputs of the second switch, the outputs of which connected to two memory blocks, the outputs of which are connected to the information presentation unit, made in the form of series-connected differential gain I linearizer and analog-to-digital converter, and the outputs of the control unit connected to the control inputs of the switches. FIG. 2 beyond ntv of FIG. 3 Compiled by D. Molyavin Editor I. Shulla Tehred M. Morgenthal Corrector O. Kundrick --------------- --------------------- i ------------— --------- Order 2652 Circulation 379 Subscription VNIIIPI of the State Committee for Inventions and Discoveries under the State Committee for Science and Technology of the USSR 113035, Moscow, Zh-35, Raushskaya nab., 4/5 Production and Publishing Combine Patent, Uzhgorod, 101 Gagarin St.