SU1712783A1 - Ultrasonic echo-pulse thickness gauge - Google Patents

Abstract

The invention relates to non-destructive testing and can be used in measuring the thickness of various materials, as well as the speed of ultrasound in parts of known thickness. The purpose of the invention is to improve the accuracy and reliability of measurements. When measuring the thickness over the time interval between the arrival of reflection pulses from the edges of the product, the amplitude of the bottom pulse is monitored. With the arrival of each clock pulse, the subtracting counter changes its state, thereby reducing the threshold level for the bottom echo pulse. When it is compared with the amplitude of this pulse, the desired time interval is measured. 1 il.sls

Description

The invention relates to non-destructive testing and can be used in measuring the thickness of various materials, as well as the speed of ultrasound in detail; lx of known thickness.

Known ultrasonic thickness gauge containing RS-flip-flops, the scheme will match the sequentially connected synchronizer, probe pulse generator, transceiver unit, amplifier and comparator.

The disadvantage is its low reliability.

The closest to the present invention is an ultrasonic thickness gauge comprising a synchronizer connected in series, a first one-shot, a first RS trigger, a first match circuit, an output connected to the C input of a first RS trigger, a second one-shot, a second RS trigger and a second match circuit, output connected to the C input of the second RS trigger, a series connected probe pulse generator, the input of which is connected to the synchronizer output, a transceiver transducer, an amplifier, the first comparator, the third a coincidence circuit, the second input of which is connected to the output of the first RS flip-flop, a time interval meter and an indicator connected in series to a second comparator, whose information input is connected to the output of the amplifier, a fourth coincidence circuit, a second input connected to the output of the second RS flip-flop and output to the second input of the time interval meter, the third RS trigger, whose S input is with the output of the second coincidence circuit, and the output with the third inputs of the third and fourth coincidence circuit, the reference source connected to the reference input of the first comparator, the output of the first comparator is connected to the second input of the first matching circuit, the output of the second comparator is connected to the second input of the second matching circuit, and the synchronizer output is connected to the reset inputs of the first and second RS triggers and time meter.

The disadvantage of this thickness gauge is its low accuracy and reliability due to the fact that the third echo signal may be absent.

The purpose of the invention is to improve the accuracy and reliability of thickness measurement with varying parameters of the part (thickness, non-parallelism, curvature of surfaces, etc.) due to the accurate formation of the time interval between the first and second echo signals from the surfaces of the measured part, as well as eliminating the adjustment thresholds of discrimination of the amplitudes of the pulses.

This goal is achieved by the fact that an ultrasonic pulse echo pulse thickness gauge containing a serially connected synchronizer, the first one-shot, the first RS trigger, the first match circuit, the output connected to the C input of the first RS-trigger, the second one-shot, the second RS-trigger and the second coincidence circuit, output connected to C-input of second RS-flip-flop, series-connected probe pulse generator, input of which is connected to synchronizer output, transceiver converter, amplifier, first computer an ator, a third coincidence circuit, the second input of which is connected to the output of the first RS flip-flop, a time interval meter and an indicator connected in series to a second comparator, whose information input is connected to the amplifier output, the fourth coincidence circuit, a second input connected to the output of the second RS-flip-flop, and the output to the second input of the time interval meter, the third RS trigger, the S input of which is connected to the output of the second coincidence circuit, and the output to the third inputs of the third and fourth coincidence circuit, the source is voltage connected to the reference input of the first comparator, and the source of a single potential, the output of the first comparator is connected to the second input of the first matching circuit, the output of the second comparator is connected to the second input of the second matching circuit, and the output of the synchronizer is connected to the reset inputs of the first and second RS-triggers and time meter, equipped with a series-connected fifth circuit

match, the first input connected to the inverse output of the third RS-flip-flop, and the second input - to the synchronizer output, subtractive counter, informational inputs of which are connected to the source potential source, and the setup input - to the output of the time interval meter, digital-to-analog converter and the first switch,

0 the control input of which is connected to the inverse output of the third RS-flip-flop, and a series-connected voltage divider, the input connected to the output of the digital-to-analog converter, and

5 by a second switch, the control input of which is connected to the direct output of the third RS flip-flop, and the reference input of the second comparator is connected to the outputs of the switches.

The coupling of the interaction of these elements with the remaining elements of the thickness gauge allows automatically, depending on the change in the amplitude of the bottom echo pulse, to form the value

5 of the reference voltage, which determines the threshold of discrimination of the amplitude of the bottom echo pulse. This ensures accurate formation of the time interval between the first and second echo signals,

0 corresponding to the measured thickness.

The drawing shows an ultrasonic echo impulse thickness gauge, block diagram.

The ultrasonic pulse echo thickness gauge contains a series-connected synchronizer 1, a 2 probe pulse generator, a transceiver transducer 3, and an amplifier 4, connected in series first

0 one-shot 5, the input connected to the output of the synchronizer 1, RS-flip-flop 6, 7 matching circuit, output connected to the C-input of the first RS-flip-flop 6, second one-vibrator 8, RS-flip-flop 9, 10 matching circuit, output connected to the C- to the input of the second RS flip-flop 9, connected in series the first comparator 11, the first input connected to the output of the amplifier 4, the second input to the source Uon

0 of the reference voltage, the third coincidence circuit 12, the second input of which is connected to the output of the first RS flip-flop, a meter of 13 time slots and an indicator 14 connected in series to the second comparator 15, the first input connected to the output of the amplifier 4, the fourth circuit 16 coincidences, the output connected to the second input of the meter 13, and the second input to the output of the second RS-flip-flop 9, connect the output of the second comparator 15 to the second input of the second circuit 10 matches, the third RS-flip-flop 17, S-input connected to the output of the second circuit 10 matches, output to the third Dame of the third 12 and the fourth 16 coincidence circuits connected in series to the fifth coincidence circuit 18 by the first input connected to the second output of the third RS flip-flop 17, the second input to the output of the synchronizer 1, the subtracting counter 19, the information inputs of which are connected to to the power source ga setup input PE - to the second output of the meter 13 time intervals, digital-to-analog converter (DAC) 20, the digital inputs of which are connected to the corresponding outputs of the subtractive counter 19, the analog input - to the source Iku Uon reference voltage, the first switch 21, the control input of which is connected to the second output of the third RS-flip-flop 17, and the output to the second input of the second comparator 15, serially connected voltage divider 22, the input connected to the output of the DAC 20, the second switch 23, the control input of which is connected to the first output of the third RS trigger 17, and the output to the second, input of the second comparator 15.

The thickness gauge works as follows.

The synchronizer 1 triggers the probe pulse generator 2, sets the RS-flip-flops 6 and 9 and the 13 time intervals meter to the source state and the trailing edge triggers the first one-oscillator 5. The generator 2 excites the pulse emitted by the piezoelectric transducer 3, is introduced through the matching medium into the controlled product , spreading in it, undergoes repeated reflections from surfaces. The ultrasonic vibrations arising in this case are received by the piezoelectric transducer 3 and are converted by it into electrical signals that are fed to the amplifier. The amplified signals are fed to the inputs of the first 11 and second 15: comparators. A reference voltage Don is applied to one of the inputs of the first comparator 11, which is chosen to be somewhat larger than the maximum amplitude of the noise.

The pulses at the output of the first comparator 11 appear when the amplitude of the signals at the input is greater than the level of the reference voltage. The signals are simultaneously supplied to the input of the second comparator 15. And the second input of this comparator from the DAC 20 is fed through the first switch 21 to the reference voltage Don. Its recognition is determined by the state of the digital outputs, which is determined by the value of the digital outputs of the detracting counter 19. In the initial state, all inputs are set to one when the meter enters the PE input from the meter of 13 time slots. This state corresponds to the maximum value of the reference voltage, which is chosen to be somewhat larger than the maximum amplitude of the bottom pulse. At the same time, at the outputs of the second comparator 15 and the second coincidence circuit 10, the bottom pulse is absent and the third RS flip-flop 17 is

5 in the zero state, and the second output in state 1, which, being fed to the second input of the fifth coincidence circuit 18, permits the passage of synchronizer 1 pulses to the clock C-BKHOD of the high-speed counter 19. From the incoming pulses the state of the digital outputs counter .19 is discretely varied, and the value of the reference voltage Don is reduced accordingly. When its value at the second input

5 of the second comparator 15 is less than the bottom pulse, the output of this comparator and, accordingly, the output of the second circuit 10 coincides with a pulse that will set the third RS flip-flop 17 to one

About state. In this case, on the inverse trigger output there will be a zero state, prohibiting the passage of the pulses of synchronizer 1 through the fifth coincidence circuit 18 and the reference voltage Uon through the first

5 switch 21. At the same time, the potential of the direct output of the third RS flip-flop 17 opens the second switch 23. Thus, the steady-state value of the digital outputs of the counter 19 and the corresponding inputs of the DAC 20 will fix the value of the reference voltage Uon, which is equal to the amplitude of the bottom pulse 22 voltages at a given level of discrimination threshold will be applied through the open second switch 23

to the second input of the second comparator 15.

(To highlight information signals

from the impulse series are one-shot 5

and 8, RS-flip-flops 6, 9 and 17 and schemes 7, 10.12 and

0 16 matches.

The duration of the output pulse of the first one-shot 5 is determined by the time. It transients in the amplifier 4 and the thickness of the matching material. The first trigger 6 is cocked on the falling edge of the pulse. At its output, a potential is established to allow the passage of pulses from the second comparator 15 through the first coincidence circuit 7. The first impulse corresponding to the first echo impulse, passed through the first circuit 7 of coincidence, with its falling edge on the C-input resets the first RS flip-flop 6, which prohibits further passage of pulses through the first circuit 7 of coincidence and starts the second one-vibrator 8, on the trailing edge the pulse is cocked by the second RS flip-flop 9. At the output of the second RS flip-flop 9, a potential is established that permits the passage of pulses through the second coincidence circuit 10. After the addition of pulses at the output of the coincidence circuit 10, a pulse corresponding to the bottom echo pulse will appear. The falling edge of this pulse of the second RS flip-flop 9 is reset and prohibits the passage of pulses through the second coincidence circuit 10. The third RS-trigger 17 is charged with the same impulse. A potential is established at its output that allows the passage of the pulses of the first 11 and second 15 comparators, respectively, through the third 12 and fourth 16 coincidence circuits. After the addition of pulses at the outputs of these coincidence circuits, pulses appear that correspond to reflections from the outer (first) and inner (bottom) surfaces of the part.

Thus, from the entire pulse train, two pulses are selected, the leading edges of which correspond to a given discrimination threshold for the amplitudes of the first and second (bottom) echo pulses, and the time between them for any changes in the amplitudes of the bottom echo pulses corresponds to the measured thickness.

Impulses act on the meter 13 time i intervals, where the duration is Tism. is converted to metric units corresponding to the measured thickness, which are measured by the indicator 14.

The use of the invention improves the accuracy of thickness control and the stability of measurement results in the presence of various influencing factors: thickness varies, varies roughness, curvature of the surface, etc., leading to sharp and unpredictable changes in the amplitude of the signals during the measurement. , it eliminates the rearrangement of the thresholds of discrimination of the amplitudes of the pulses in the control of materials with different attenuation coefficients, varying surface roughness and curvature, and thereby simplify instrument setup during operation.

Claims (1)

Ultrasonic Echo Pulse Thickness Gauge, containing a synchronously connected synchronizer, the first one-shot, the first RS trigger, the first match circuit, output connected to the C input of the first RS trigger, the second one-shot, second RS trigger and the second match circuit, output connected to the C input of the second RS flip-flop, a probe pulse generator connected in series, the input of which is connected to the synchronizer output, a transceiver transducer, an amplifier, a first comparator, a third circuit matches, the second input of which is connected to the output of the first RS flip-flop, time interval meter and indicator connected in series to the second comparator, whose information input is connected to the amplifier output, the fourth matching circuit, the second input connected to the output of the second RS flip-flop, and output to the second input of the time interval meter, the third RS trigger, the S input of which is associated with the output of the second matching circuit, and the output with the third inputs of the third and fourth matching circuit, the source of the reference voltage, n CONNECTIONS to the reference input of the first comparator, and a unified source. The output potential of the first comparator is connected to the second input of the first matching circuit, the output of the second comparator is connected to the second input of the second matching circuit, and the synchronizer output is connected to the reset inputs of the first and second RS-triggers and time meter, which differs from in order to increase accuracy and reliability, it is equipped with series-matched fifth matching circuit, the first input connected to the inverse output of the third RS flip-flop, and the second input to the synchronizer output, deducting the score A sensor whose information inputs are connected to a source of single potential, and a setup input to the output of a time interval meter, a digital-to-analog converter and the first switch, the control input of which is connected to the inverse output of the third RS flip-flop, are connected in series with a voltage divider. a digital-to-analog converter output, and a second switch, the control input of which is connected to the forward output of the third RS flip-flop, and the reference input of the second comparator is connected to Exit switch.