RU1781538C - Ultrasound echo-pulse thickness meter - Google Patents

Abstract

The invention relates to a measurement technique. The purpose of the invention is to improve the accuracy of measurements. The storage unit and the comparison unit provide a sampling of pulses at the output of the triggers, having a duration corresponding to the thickness of the measured product and an amplitude exceeding the given value of Gur6vep. The measurement accuracy is improved by dividing the separation ™ of the duration of the GuestHPG pulse between the first and second echo pulses with the pulse duration between the third and j fourth and subsequent echo pulses by the number of pairs of echo pulses whose amplitude exceeds a predetermined level. 2 s.p. f-ly, A il.

Description

The invention relates to a measuring and control technique and can be used to control the thickness of products from various materials.

A known ultrasonic thickness gauge containing a series-connected crystal oscillator, synchronizer, probe pulse generator, acoustic transducer, amplifier, driver, the second input of which is connected to the output of the synchronizer, and a key, as well as a code adjuster connected to the second key input, and an indicator, in series connected multiplying digital-to-analog converter and integrating analog-to-digital converter connected between the key output and the indicator input.

A disadvantage of the known thickness gauge is the low measurement accuracy caused by the discrete counting of the number of periods of the clock pulses of the crystal oscillator.

Known ultrasonic echo-pulse thickness gauge containing a serially connected synchronizer, a probe pulse generator, an acoustic transducer and an amplifier, a first one-shot vibrator connected in series, an input connected to a second synchronizer output, a first RS trigger, a matching circuit connected to a C RS input of the first RS trigger, second one-shot, RS-trigger, match circuit, second input connected to the R-input of the second RS-trigger third single-vibrator, RS-tripper, match pattern,

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the second input connected to the C-input of the third RS-flip-flop, a time interval meter, the second input connected to the first output of the second coincidence circuit and an indicator. Installation R-inputs of RS-flip-flops and the third input of the time interval meter are connected to the second input of the synchronizer. The first comparator with the third input is connected to the output by the second input - to the voltage reference source, and by the output - to the second inputs of the matching circuits (2).

The disadvantage of the local thickness gauge is the low accuracy of measurements caused by the presence of a methodological error, which arises due to the fact that with a constant level of response of the first comparator and a change in the amplitude of the echo pulses due to a change in the roughness or wedge-shaped surface of the measured product, one half-cycle of an electric pulse is possible which changes the response time of the first comparator.

Closest to the claimed invention is a technical solution comprising a serially connected synchronizer, a generator, an acoustic transducer, a preamplifier, an amplifier-driver, a first trigger, a first time interval multiplier, a first ramp generator, a first peak detector, an adder, analog-to-digital converter, a memory unit and an indication unit connected in series to a second trigger, a second time interval multiplier, a second generator linearly luminant voltage and a second peak detector connected in series and a first one-shot RS-flip-flop and a second monostable multivibrator. The output of the second peak detector is connected to the second input of the adder, and the input of the second trigger is connected to the output of the amplifier-former. The output of the second time interval multiplier is connected to the input of the second one-shot, and the output of the latter is connected to the second inputs of the analog-to-digital converter and the memory unit. The output of the second trigger is connected to the input of the first single-vibrator, the output of the RS-trigger is connected to the second inputs of the triggers, and the output of the synchronizer is connected to the second inputs of the RS-trigger and peak detectors.

The disadvantage of this technical solution is the low accuracy of measurements, caused by the fact that the first echo signal is reflected from the surface of the contact liquid and the time interval between the first and second echo pulses is proportional to the total thickness of the article and contact liquid at the transducer installation site.

The purpose of the invention is to improve the accuracy of measurements.

This goal is achieved in that an ultrasonic echo-pulse thickness gauge comprising a serially connected synchronizer, a generator, an acoustic transducer, a pre-amplifier, a driver-amplifier and a first trigger, a serially connected first ramp generator, a first peak detector, an adder and an analog digital converter, serially connected to a second ramp generator and a second peak

a detector with an output connected to the second input of the adder, a second trigger connected in series, an input connected to the output of the amplifier-former, and the first one-shot, as well as the RS-trigger,

the first input connected to the output of the synchronizer, and the input connected to the second inputs of the first and second RS-triggers, the second one-shot and display unit according to the invention, is equipped

connected in series by a storage unit, a comparison unit, a digital adder and a digital divider, an output connected to the input of the display unit, a counter, an output connected

with the second input of the digital divider, and the comparison unit connected to the output, and an OR circuit connected to the second inputs of the first and second peak detectors, the output of the first one-shot connected to the input of the second one-shot and the second input of the analog-to-digital converter, the output of the second one-shot with the first inputs of the storage unit and circuit OR and

the second input of the comparison unit, the synchronizer output is connected to the second inputs of the OR circuit, the counter, the storage unit and the digital adder, the output of the first trigger is connected to the input of the first ramp generator, the output of the second trigger is connected to the input of the second ramp generator, the output of the analog-to-digital converter is connected to the fourth input of the comparison unit and the third inputs of the storage unit and the adder, and the second input of the RS flip-flop is connected to the second output of the comparison unit.

In FIG. 1 is a functional diagram of a claimed ultrasonic echo pulse thickness gauge; from FIG. 2 is a timing chart illustrating the operation of the claimed ultrasonic echo-pulse thickness gauge: FIG. 3 is a functional block diagram of a storage unit; in FIG. 4 is a functional block diagram of a comparison unit.

The circuit (Fig. 1) includes a synchronizer 1 connected in series 1. an oscillator 2, an acoustic transducer 3, a preamplifier 4, an amplifier-former 5, a trigger 6, a ramp generator 7, a peak detector 8, an adder 9, and an analog -digital converter (ADC) 10, serially connected trigger 11, GLIN 12 and peak detector 13, serially connected memory unit 14, comparator 15, digital adder 16, digital divider 17 and indication unit 18, connected in series to one-vibrator 19, a single vibrator 20 and an OR circuit 21, as well as a counter 22 and an RS trigger 23. The output of a single vibrator 20 is connected to the first input of the storage unit 14, the output of the OR circuit 21 is connected to the second inputs of the peak detectors 8, 13, the first input of the counter 22 is connected to the first output of the comparison unit 15, and the output of the counter 22 is connected to the second input of the digital divider 17. The output of the synchronizer 1 is connected to the second inputs of the OR circuit 21, the counter 22, the storage unit 14 and the digital adder 16, the first input of the RS flip-flop 23 and the third input of the block 15 comparisons. The input of the trigger 11 is connected to the output of the amplifier-former 5, and the output of the peak detector 13 is connected to the second input of the adder 9. The output of the ADC 10 is connected to the fourth input of the comparison unit 15 and the third inputs of the storage unit 14 and the digital adder 16. The output of the first one-shot 9 is connected to the second input of the ADC 10, the second input of the RS-trigger 23 is connected to the second output of the comparison unit 15, the output of the RS-trigger 23 is connected to the second inputs of the triggers b, 11, and the output of the trigger 11 is connected to the input of the one-shot 19, Acoustic transducer 3 is set to overhnost article 24,

Ultrasonic echo-pulse thickness gauge works as follows.

The synchronizer 1 starts the generator 2, which generates rectangular pulses (Fig. 2, a) and at the same time installs the RS-flip-flop 23 (Fig. 2, b), the storage unit 14, the comparison unit 15, the digital adder 16, the counter 22 and, by Schemes 21 OR. peak detectors 8, 13 in the zero state RS-trigger 23 output zero potential supplied to the second inputs of the triggers b, 11, allows the operation of the latter From the output of the generator 2, electrical pulses are fed to the acoustic transducer 3, which

converts electrical signals into ultrasonic pulses, which fall into the measured product 24, while part of the energy of the ultrasonic pulse is emitted from the external surface of the measured product 24 in contact with the acoustic transducer 3 towards the transducer 3, and part of the energy passes into the product 24 and reflecting from the inner surface, it also returns to transducer 3, again crossing the interface of transducer 3 and article 24. At this boundary, partial reflection of ultra sonic pulse, which leads to multiple reflections of these pulses, gradually decreasing in amplitude, and with each reflection from the outer surface of article 24, part of the energy goes to acoustic transducer 3. After some 5, the time required to pass along the delay line (not shown) , at the pye of the sonic transducer 3, which performs the function of the receiver, a series of ultrasonic pulses falls, converted by the acoustic transducer 3 into electrical signals that are fed to the input itelnogo amplifier 4 (Fig. 2c). From the output of the latter, the electric signals are fed to the input of the amplifier -for5 of the reverberator 5, where there is an additional amplification of signals exceeding the specified level U in amplitude (Fig. 2, c), as well as the formation of steep fronts of electrical signals (Fig. 2, d). From the output of the amplifier-former 5, electric signals are supplied to the first inputs of triggers b, 11. The first trigger b is triggered when a positive voltage drop occurs at the input, and the second trigger 11 is activated when a negative voltage drop occurs at the input, t. e. when the leading and trailing edges of the forward echo pulse appear, the triggers G, 11 go into the single state, respectively, and

0, when the leading and trailing edges of the second echo pulse appear, the triggers 6, 11 go to the zero state, respectively. When the third and subsequent echo pulses appear, the operation of triggers C,

5 to 11 is repeated with the corresponding frame (Fig. 2, e). In the case of pulsed pulses at the output of the triggers 6, 11, the GLIN 7, 12 respectively, a voltage linearly varying in time is generated (Fig. 2, g, h), which are supplied to the first inputs of the peak detectors 8, 13, respectively. The output voltages of the peak detectors 8, 13 (Fig. 2, and, k) are supplied to the corresponding inputs of the adder 9, where they are summed (Fig. 2, l) and from the output of the adder 9 are fed to the input of the ADC 10. The trailing edge of the pulse at the output of the second trigger 11, the first one-shot 19 is triggered (Fig. 2, m). When a trailing edge of the pulse appears at the output of the latter, the second one-shot 20 is triggered (Fig. 2, n) and, when a trailing edge appears at the output of the last ADC 10, it converts the signal from the output of the adder 9 into a digital code, which is fed to the second input of the comparison unit 15 the third inputs of the storage unit 14 and the digital adder 16. After the operation of the single vibrator 20, the pulse from the output of the last is fed to the first input of the storage unit 14 and the digital code from the output of the ADC 10 is recorded in the storage unit 14. The pulse from the output of the second one-shot 20 through the circuit 21, OR is supplied to the second inputs of the peak detectors 8, 13 and the voltage at the output of the latter is set to zero. The digital code from the output of the storage unit 14 is fed to the first input of the comparison unit 15, where this digital code is compared with a digital code at the output of the ADC 10, which is supplied to the second input of the comparison unit 15, and in the case of the inequality UBxi UBx2 input-A (where UBxi is the digital code at the first input of the comparison unit 15, UBx2 is the digital code at the second input of the comparison unit 15, A is the set value of the digital code, characterize it measurement accuracy), the output of comparator unit 15 and is momentum, by which a digital code on output of the ADC 10 is recorded in a digital adder 16. A counter 22 counts the number of pulses at their trailing edge at the output of comparator 15. With the advent of the third and fourth, fifth and sixth, etc. echo pulses, respectively, whose amplitude exceeds a predetermined level U, the operation of triggers 6.11 GLIN 7, 12, peak detectors 8, 13, adder 9, ADC 10, block 15 comparison, counter 22, digital adder 16s and single vibrators 19, 20 is repeated, while in the digital adder 16 a digital code is recorded proportional to the sum of the time intervals between the leading and trailing edges of the first and second, third and fourth, etc. echo pulses, respectively, and a digital code corresponding to the number of pairs of echo pulses appears at the output of counter 22. On the trailing edge of the first

of the pulse at the output of the trigger 11, the single-shots 19, 20 are sequentially triggered and when the last pulse appears at the output, which arrives at the first inputs

OR circuit 21 and a storage unit 14, the latter stores a digital code from the output of the ADC 10, corresponding to the sum of the time intervals between the leading and trailing edges of the first and second echo pulses. The comparison unit 15 compares the digital codes at the outputs of the storage unit 14 and the ADC 10. In the case where the digital code at the output of the storage unit 14 is equal to or less than the value set, the digital code at the output of the ADC 10 (or, which is the same, when the sum of the time intervals between the leading and trailing edges of the first and second, third and fourth, etc. echo pulses

equal to or less by an amount not exceeding a given sum of time intervals between the leading and trailing edges of the first and second echo pulses), at the first output of the comparison unit 15

pulses appear (Fig. 2, p), according to which the digital adder sums and writes digital codes from the output of the ADC 10, and the counter 22 counts the number of these pulses. In the case when the time interval between

echo pulses, the amplitude of which exceeds a predetermined level, becomes larger or differs in a smaller direction by an amount greater than a specified, compared with the time interval between

the first and second echo pulses, the high potential appears at the second output of the comparison unit 15, while the RS potential of the trigger 23 also shows a high potential (Fig. 2, o), according to which the triggers 6,

11, the GLIN 7, 12, peak detectors 8, 13, adder 9, and ADC 10 stop operating (until a new pulse arrives from the output of synchronizer 1). A digital divider 17 with a variable division coefficient divides the digital code at the output of the digital adder 16, corresponding to the sum of the time intervals between the leading and trailing edges of the first and second,

third and fourth, etc. echo pulses, by the number stored in the memory of the counter 22, and from the output of the digital divider 17, the division result is transmitted to the input of the display unit 18.

When a trailing edge of pulses appears at the output of the second trigger 11, one-shots 19, 20 are sequentially triggered and pulses from the output of the latter through circuit 21 OR are fed to the second inputs

peak detectors 8, 13 and the latter are set to zero. Thus, at the output of the peak detectors 8.13, at the end of the pulses, the output of the triggers b, 11, respectively, shows voltages proportional to the duration of these pulses and after a certain time equal to the duration of the pulses of the one-shot 19, 20 (which is necessary to record the output voltage of the adder 9 in the ADC 10 and eliminating false alarms). Therefore, in the digital adder 16, a digital code corresponding to the sum of the time intervals between the leading and trailing edges of the echo pulses, the amplitude of which exceeds a predetermined level and the time interval between which is included in a predetermined interval.

A functional diagram of the storage unit 14 is shown in FIG. 3.

The storage unit 14 contains a series-connected RS-flip-flop 25, a one-shot 26 and random access memory (03B) 27. The first and second inputs of the RS-flip-flop 25 and the second input 03 B 27 are connected to the first, second and third inputs of the storage unit 14, respectively and the output 03B 27 is connected to the output of the latter.

The storage unit 14 operates as follows.

Upon receipt of a pulse from the output of the synchronizer 1 to the second input of the RS-flip-flop 25, the latter goes into a single state. After the single-shot 19 is triggered, the ADC 10 converts the voltage at the input of the latter to a digital code, which is fed to the second input of the OZB 27 and, when a pulse occurs at the output of the second one-shot 20 of the RS flip-flop 25, it goes to the zero state. a single vibrator 26, the output pulse of which is fed to the first input of the OZB 27 and the last digital code is written from the output of the ADC 10. The subsequent operation of the single vibrator 20 does not change the state of the second RS-flip-flop 25 and the digital code in the OZB 27 is stored until the appearance next pulse at the output of the synchronizer 1

The functional block diagram of the comparison unit 15 is shown in FIG. 4.

Comparison unit 15 comprises series-connected adder 28, two-threshold comparator 29, and 2I circuit 30. The input of the adder 28 and the second input of the two-threshold comparator 29 are connected to the first input of the comparison unit 15. The second input of the circuit 30 214, the second input of the adder 28 and the third input of the double-threshold comparator 29 are connected to the second, third and fourth

the inputs of the comparison unit 15, respectively, and the output of the 2I circuit 30 and the second input of the two-threshold comparator 29 are connected to the first and second outputs of the comparison unit 15, respectively.

The comparison unit 15 operates as follows.

When a pulse appears at the output of the synchronizer 1, the adder 28 is installed

0 to the initial state. The digital code from the output of the ADC 10 is supplied to the third input of the two-threshold comparator 29. The digital code from the output of the storage unit 14 is supplied to the first input of the adder 28 and the second input

5 of the two-threshold comparator 29. In the adder 28, this digital code is subtracted by an amount proportional to the time the echo pulses travel through the contact liquid. So on

At the first and second inputs of the two-threshold comparator 29, lower and upper thresholds (i.e., a predetermined interval) are set respectively. In the case when the digital code from the output of the ADC 10

5 enters a predetermined interval, the high potential is maintained at the first output of the two-threshold comparator 29, and the triggers 6, 11 continue to operate, and the pulses from the output of the one-shot 20 through the circuit 30 2A and arrive at the first input of the counter 22. In the case when the time interval between the echo pulses differ from the set one, the maximum duration being determined by the duration of the time interval between the first and second echo pulses, and the minimum duration equal to the difference between the last interval and the interval corresponding to Meni passage echo pulses on contact

0 liquids, the potentials at the outputs of the two-threshold comparator 29 change, while the RS flip-flop 23, and together with the latter triggers 6, 11, go to the zero state. The one-shots 19, 20 sequentially 5 work as in the previous case, however, the potential at the output of the circuit 29 2I does not change and the digital code corresponding to the last interval, which differs from the specified interval, is not entered into the digital adder 0 and the pulse does not enter the counter input 22 .

The time interval between the first and second echo pulses is slightly larger than the time intervals between the second and

5 by the third and subsequent echo pulses, as the first echo pulse is reflected from the outer surface of the contact liquid, and the second and subsequent echo pulses are reflected from the surface of the article 24. Therefore, when measuring the thickness of the products

the prototype measurement result will be slightly higher (differs by the thickness of the contact liquid). When measuring the thickness of product 24 with an ultrasonic pulse echo pulse thickness gauge, the measurement error will be much lower, since time interval between the third and fourth, etc. echo pulses correspond to the thickness of article 24, and when dividing the digital code corresponding to the total time interval by the number of corresponding pulses, the resulting error is reduced as many times as the pairs exceed the specified level in amplitude and this increases the accuracy of measurements.

Claims (3)

SUMMARY OF THE INVENTION 1. An ultrasonic echo-pulse thickness gauge comprising a serially connected synchronizer, a generator, an acoustic transducer, a pre-amplifier, a driver-former and a first trigger, a serially connected first ramp generator, a first peak detector, an adder and an analog a digital converter, a second linearly varying voltage generator and a second peak detector connected in series to the second input of the adder in series sequentially connected by a second trigger, the first input connected to the output of the amplifier - former, and the first one-shot, RS-trigger, R-input connected to the output of the synchronizer, and the output connected to the second inputs of the first and second triggers, the second one-shot and display unit, characterized in In order to increase accuracy, it is equipped with a memory unit, a comparison unit, a digital adder and a digital divider connected in series, an output connected to the input of the display unit, a counter, a connection output connected to the second input of the digital divider, and the first input connected to the output of the comparison device, and an OR circuit connected to the second inputs of the first and second peak detectors, the output of the first one-shot is connected to the input of the second one-shot and to the second input of the analog-to-digital converter, the output of the second one-shot is connected to the first inputs of the storage unit and the OR circuit and the second input of the comparison unit, the output of the synchronizer is connected to the second inputs of the OR circuit, counter, storage unit and digital sou the motherboard and with the third input of the comparison unit, the output of the first trigger is connected to the input of the first ramp generator, the output of the second trigger is connected to the input of the second ramp generator, the output of the analog-to-digital converter is connected to the fourth input of the comparison unit and to the third inputs a storage unit and an adder, a S-input of the RS-flip-flop connected to the second output of the comparison unit. 2. The thickness gauge according to claim 1, with the fact that the storage unit is made of series-connected RS-flip-flop, one-shot, random-access memory, and the R-input and S-input RS- the trigger and the second input and output of the random access memory are respectively the first, second and third inputs and output of the memory block 3. The thickness gauge according to claim 1, with the exception that the comparison unit is made up of a series-connected adder, a two-threshold comparator and circuit 2I, the input of the adder and the second input of the two-way comparator are the first input the comparison unit, the second input of the And circuit, the second input of the adder and the third input of the two-threshold comparator are respectively the second, third and fourth inputs of the comparison unit, and the output of the And circuit and the second output of the two-threshold comparator are the first and second outputs of the comparison unit, respectively. i-D -D -A-A-A l / u4 P P P P P 3 I1 UL l l l l l l l / l Riga 2 L I-I (-I Drum 1 FIG. B 3 $ x0E fЈxod Pc / g4 4faod 2 & sob Bark