SU1114940A1 - Eddy-current flaw detector - Google Patents

Abstract

VORTEX DEFEKTOSKOP, containing a series-connected eddy current transducer, an auto-oscillator and an amplitude detector, an amplifier-limiter connected to the auto-oscillator, and an indicator, characterized in that, in order to increase the monitoring reliability, it is equipped with a DC amplifier connected to 1 € € OS5 SHRM5. 13 TFXJ ivV-AS LANDBLOT rA between the amplitude detector and the indicator, an analog switch connected between the output of the DC amplifier and its second input, a capacitor connected between the input of the DC amplifier and the common wire, and connected in series by the first 2I circuit, the first input of which is connected to the limiter amplifier, a reversible counter, the counter content analysis circuit and the second 2I circuit, whose pin is connected to the control input of the analog switch and the Pulse Generator The outputs of which are connected to the second inputs of the first and second circuits 2I and the control input: the counting direction of the reversible counter.

Description

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The invention relates to methods of non-destructive testing and can be used to determine the location of defects in metal products and structures.

Known eddy current flaw containing a self-oscillator connected in series eddy current transducer, amplitude detector and indicator lj.

The disadvantage of this flaw detector is its sensitivity to various interfering factors, for example, the gap between the product and the transducer, which adversely affects the accuracy of control.

The closest to the technical essence of the invention is an eddy current flaw detector containing an eddy current transducer connected in series, an auto-oscillator and an amplitude detector and an amplifier-limiter connected to the auto-oscillator and an indicator 2J.

However, in dependence of the amplitude and frequency on the size of the tap in the self-oscillating measuring circuit, the known flaw detectors have significant non-linearities, the character of which strongly depends on the electrophysical properties of the tested surfaces. The desire to set off these properties necessitates the introduction of an element with controlled correction nonlinearity and the correction of weighting factors for each material under study. As a result, there is no manual operation, and full compensation of the effect of retraction in this device is not achieved.

The aim of the invention is to increase the reliability of the control.

The goal is achieved by the fact that the eddy current flaw detector containing an avogenerator and an amplitude detector connected in series by the eddy current transducer, and an amplifier-limiter connected to the autogenerator, and the indicator are equipped with a DC amplifier connected between the amplitude detector and the indicator, similar to a key included between the output of the DC amplifier, ka, and its second input, a capacitor, connected between the second input of the DC amplifier and the common wire, and the connected about 149402

first circuit 2I, the first input of which is connected to the amplifier-limiter, reversible counter, counter content analysis circuit and the second circuit 2I, the output of which is connected to the control input of the analog switch, and a pulse distributor, the outputs of which are connected to the second inputs of the first and second circuit 2I and the input of the direction control of the reversible counter.

FIG. 1 is a block diagram of a flaw detector i in FIG. 2 - time5 voltage diagrams at the outputs of the pulse distributor generator.

The flaw detector contains an eddy current transducer 1 connected in series, an auto-oscillator 2 and an amplitude defector 3. The output of an auto-generator 2 is connected in series by an amplifier-limiter 4, circuit 2I, 5, reversible counter 5, circuit 7I 8. The device also contains a pulse-distribution generator 9, the outputs of which are connected to the second inputs of the 2I 5 and 8 circuits and to the counting direction control input of the reversible counter 6.

The flaw detector also contains a DC amplifier 10 connected to an amplitude detector 3, an analog switch 11 connected between the output of the DC amplifier 10 and its second input, and a capacitor 12 connected between

0 with the second input of the DC 10 amplifier and the common wire.

The flaw detector contains an indicator 13 connected to the output of the DC amplifier 10.

five

The flaw detector works as follows

in a way.

The eddy current transducer 1, together with the auto-oscillator 2, ensures the conversion of the presence

defects, the magnitude of the removal and electrophysical properties of the investigated surfaces into corresponding changes in the amplitude and frequency of oscillations. The relative frequency changes, mainly due to the change in the value of the tap, are allocated by a reversible counter oscillation 6, to the counting input of which is received from the auto-oscillator 2 through the limiting amplifier 4 and the logic circuit 2I 5. The impulse-distributing generator 9 provides equal time intervals T forward and countdown, synchronous change of counting direction and gating the result of the evaluation of the frequency change. The signal at the output of circuit 7 for analyzing the contents of the counter corresponds to logical 1 in all cases when the contents of counter 6 are different from zero. At the same time, the strobe pulse from the third output of the distribution generator 9 pulses passes through the logic circuit 2I 8 to the control input of the analog switch 11, which, closing, during time tj. provides memory for 2T + t voltage, which compensates for the relative change in amplitude.

1149AO4

due to the change in the size of the allotment.

In the event that the magnitude of the transducer output 1 is unchanged, 5 relative frequency changes

insignificant and gating pulses to the control input of the analog switch 11 does not pass and compensating for the capacitor

10 12 remains almost unchanged, which is provided by a sufficiently large input impedance of the amplifier 10 DC, the output resistance of the analog switch

15 11 and low leakage currents of the capacitor 12.

The proposed eddy current flaw detector makes it possible to virtually eliminate the operation of setting up the circuit

20 offset compensation in the process

operation of the device, which reduces the complexity of its operation.

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"ABOUT

Claims (1)

Vortex defectoscopy,. comprising an eddy-current transducer connected in series, an oscillator and an amplitude detector, a limiter amplifier connected to the oscillator, and an indicator, characterized in that, in order to increase the reliability of control, it is equipped with a DC amplifier connected between the amplitude detector and the hh- ⁴ dictator, an analog switch connected between the output of the DC amplifier and its second input, a capacitor connected between the second input of the DC amplifier and the common wire, and the connected by the first 2I circuit, the first input of which is connected to an amplifier-limiter, a reversible counter, a circuit for analyzing the contents of the counter and a second 2I circuit, the output of which is connected to the control input of an analog key and a pulse-distribution generator whose outputs are connected to the second inputs of the first and second circuits 2I and the input control direction of the counting of the reversible counter.