SU1645888A2 - Eddy current test device - Google Patents

Description

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 1033947

(21) 4707769/28

(22) 06/19/89

(46) 04.30.91. Kyul P 16

(72) E.V.Troshkov

(53) 620.179.14 (088.8)

(56) USSR Author's Certificate (R 1033947, class G 01 N 27 / 90.1983.

(54) DEVICE FOR VORTEX-MONITORING CONTROL

(57) The invention relates to non-destructive testing of material parameters by electromagnetic methods. The purpose of the invention is to improve the accuracy of control due to the linearization of the characteristics of the converter. For this, the device contains a generator, a three-winding eddy current transducer connected to it, a phase shifter and an indicator, first, second and third differential limiter amplifiers connected in series, OR circuit 2, a stable amplitude and RC circuit shaper connected between the output of the eddy current transducer and input indicator, and the fourth differential amplifier-limiter connected between the output of the phase shifter and the second input of the 2IL circuit, and also connected between the RC circuit and the indicator A digital-to-digital converter made in series of an amplifier with a lower limit measurement controller, comparator, transmission circuit and pulse counter, serially connected shift register, switch, resistor matrix, divider and integrator, the output of which is connected to the second input of the comparator, capacitor and reset key, connected in parallel by the integrator of the generator of counting pulses, made with the upper limit controller, the second input of the transmission circuit is connected to you Odom count pulse generator, and pulse counter second- output - to the input of the shift register. The indicator is digital, and the pulse counter is stored with the measurement result. 2 Il.

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The invention relates to non-destructive testing of material parameters by electromagnetic methods and is in addition to auth.s. No. 1033947.

The purpose of the invention is to improve the accuracy of control due to the linearization of the characteristics of the converter.

FIG. 1 shows a block diagram of the device; FIG. 2 - time diagrams of the signals of his work.

The device contains a generator of 1 sinusoidal oscillations, made, for example, on a microcircuit in the form of a push-pull I C generator.

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The Olin output of the generator 1 is connected by successively connected eddy transducer 2, amplification limiters 3-5 is connected to the first input of the logic element 6, which functions as the element 2IL. The output of element 6 through the shaper 7 pulses of stable amplitude is connected to the KS circuit 8. The second output of the generator 1 is connected via a serially connected phase shifter 9 and the amplifier-limiter 10 is connected to the second input of the logic element 6, between the RC circuit 8 and the indicator 11 is turned on analog-digital Converter 12, made in the form of series-connected amplifier 13 with regulator 14 of the lower limit of measurements, comparator 15, transmission circuit 16 and pulse counter 17, serially connected shift register 18, switch a 19, a resistor matrix 20, a divider 21 and an integrator 22, the output of which is connected to the second input of the comparator 15, the capacitor 23 and the reset key 24 connected in parallel to the integrator 22 of the counting pulse generator 25, made with the upper limit controller 26 the input of the transmission circuit 16 is connected to the output of the generator 25 counting pulses, and the second output of the pulse counter 17 is connected to the input of the shift register 18.

The device works as follows.

The eddy current transducer 2 is installed on the surface of the controlled product and turn on the power. From the generator 1, the voltage goes to the exciting winding of the eddy current transducer 2 and to the phase shifter 9. The output voltage of the eddy current transducer 2, carrying information about the electrical conductivity of the product and removed from the series-connected measuring and compensation windings (not shown), is amplified and transformed in rectangular form in the x-limiter amplifier x 3-5 and fed to the first input of logic element 2ILI 6. The voltage of the eddy-current converter 2 passed through the phase shifter 9, silivaets and converted into the amplifier og

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the input of the logic element 6. The phase shifter 9 ensures stable operation of the device in the measurement range with a constant sign of the phase angle. Logic element 2ILI 6 extracts at its output a pulse signal, the constant component of which is extracted by means of a shaper of 7 stable amplitude pulses with a KS circuit 8 at the output. Structurally, the logic element 6 can be combined with the pulse shaper 7, for example, by introducing into the ECL element 2IL a stable current generator made in the form of a current mirror. When this capacitor RC circuit 8 will be connected with the load resistor of the element 6.

The initial state of the blocks included in the A / D converter 12, from the moment the power is turned on to the conversion process, is as follows. Pulse counter 17 and shift register 18 are reset, reset key 24 closes and shunts capacitor 23 of integrator 22, the voltage at the output of integrator 22 is equal to the reference voltage (U, jrt) and exceeds the output voltage of amplifier 13 by value. As a result, the output of comparator 15 is supported a high voltage level and the transmission circuit 16 is open for passing counting pulses from the generator 25 counting pulses to the counter 17 pulses. However, since the signal of setting to the zero state arrives at the zeroing inputs of the pulse counter 17 at a given time interval, no pulse counting occurs. The time delay between the moment the device is turned on and the start of the pulse counting is necessary to establish transients in the device blocks.

The A / D converter 12 operates in two pre-recording and conversion cycles.

Preliminary recording of pulses into pulse counter 17 begins simultaneously with the removal of the zero signal, but on condition that the specific electrical conductivity of the product is not less than the lower limit of the measuring range of the device (the device has been pre-calibrated using the lower regulators 14 and upper 26 measuring limits). If the electrical conductivity is less than the lower limit of the measuring range, the output

the yarn of the amplifier 13 can be more than the output voltage of the integrator 22; at the output of the compiler 15 NIIANI, the voltage level of the transmission band 16 is closed and the pulses are written to the counter 17 pulse

fie produced. In this case on

digital display 11 are displayed

zeros.

As you record pulses in

counter 17 at the i-th output of the counter

17 pulses are formed whose frequency is lower than the frequency of the counting pulses in accordance with the division factor at the ith output. These pulses arrive at the synchronization inputs of the shift register 18 (input F) causing the process of shifting a logical 1 at its outputs. With the appearance of a logic 1 on the K-output register

18, the reset key of the integrator 22 is opened 24 and the ADC conversion cycle 12 begins. The output numbers of the pulse counter 17 and the K-outputs of the shift register 18 are chosen so that by the time the logical 1 appears at the output K of the shift register 18, the number of pulses written In the pulse counter 17, it was less than or equal to the numerical value of the lower limit of the measuring range of the device.

When opening the reset key 24, the integrator 22 generates a linearly decreasing voltage, the slope of which is able to change N + 2 times in the whole measuring range of the device. The division ratio of the counting pulses (output i of the pulse counter 17), the number of bits of the shift register 18, the numbers of the outputs of register 18 to which the switch 19 is connected, the resistances included in the resistor matrix 20 are chosen so that the function of the output voltage of the integrator 22 was possibly a more accurate model of the characteristics of the eddy current transducer 2. In this case, the conditions in the device linearized the conversion characteristic.

The conversion cycle ends at the moment of comparing the output voltage of the integrator 22 with the output voltage of the amplifier 13. At the same time, the output of the comparator 15 is

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a low voltage is applied, the transmission circuit 16 closes and the flow of counting pulses into the counter 17 is stopped. The indicator 11 displays and remembers the number recorded in the pulse counter 17, which corresponds to the conductivity of the product. Reset readings

Indicator 11 occurs when the device is turned off.

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The controllers of the lower 14 and upper 26 limits of measurement in the simplest case are made in the form of variable resistors. Using the controller 14, the device is adjusted to the lower limit of measurement. In the process of setting up the eddy current transducer 2, they are mounted on a reference sample corresponding to the lower limit of measurement, turn on the power and, by adjusting the resistance

5 R of the regulator 14, the indications of the indicator 11 to the sample conductivity value are adjusted. Similarly, the device is adjusted using the controller 26 for the upper measurement limit on the reference sample corresponding to the upper measurement limit.

Claims (1)

Invention Formula Device for eddy current testing on avt.Sv. No. 1033947, characterized in that, in order to increase the control accuracy due to the Q linearization characteristics of the converter, it is equipped with an analog-to-digital converter connected between the RC circuit and the indicator, made in series with the amplifier with the lower limit measurement controller, comparator, the transmission circuits and pulse counters connected in series to the shift register, the switch, the resistor about the matrix, the divider and the integrator, the output of which is connected to the second input of the comparator, the capacitor and yucha reset connected in parallel integrator count pulse generator adapted regulator upper limit of measurement, the second transmission input circuit connected to the output count pulse generator, and the second output of the pulse counter connected to the input of the shift register, the indicator is digital, and the score II and 1.1SH11 III I I I II 11 1 111 11 I I 1 i Svtti pulse pulses are made with memorization of the measurement result. I№} i  t c / luHtapuMttufu L13