SU670885A1 - Device for measuring ultrasound velocity in moving sheet material - Google Patents

Description

amplifier 5 and trigger 6, amplifier 7, the input of which is connected to the output of receiver 3. And output to the inputs of flip-flops 6 and 8, connected in series to receiver 9. amplifier 10, trigger //, whose input is connected to the output of generator 1, key 12. an adder 13, a reversible counter 14 and a calculating unit 15, a generator 16 of a stable frequency E, the output of which is connected to the input of the switch 12, are connected in series with the delay stage 17, the input of which is connected to the output of the generator 16, and the switch 18, the input of which is connected to the output trigger 8, the second input of which is connected to the output home generator 1, and the output to the second input of the adder 13, serially connected frequency converter 19, the input of which is connected to the output of the generator 15, and the key 20, the output of which is connected to the second input of the reversible counter, with three receivers located in the plane, perpendicular the plane of the sheet on both sides at a fixed distance relative to each other.

The device works as follows.

At the initial moment of time / o (see Fig. 2, a), the generator 1 of the probing impulses excites the emitter 2 and at the same time brings into one state three:) -er 8.

The acoustic pulse emitted by the transducer 2 propagates through the sheet material, is partially emitted into the air and is received by acoustic receivers 3, 4 and 9. From the outputs of the receivers, the received signals arrive at the inputs of amplifiers 5, 7 and 10, at the outputs of which pulses are formed (see Fig. 2, b, c, d).

In this case, the pulse at the output of the amplifier 10 has a time shift equal to 7i T ,, + TI, where then is the delay time in the test material, and TI is D-, where C is the speed

ultrasound in the medium between the receiver and the sheet material (for example, in the air), and / 1 is the distance from the receiver 9 to the sheet material.

Accordingly, the time shift at the output of the amplifier 7 is equal to G2, where

/about

-2 -. The time shift at the output of the amplifier

.1Р 5 5 in relation to the shift at the output of the assertion, where D / is the distance between

do receivers 3 and 4.

The pulses from the outputs of amplifiers 10 and 7 bring the triggers 8 11 to their initial zero states, and the trigger 6 to the single state, which is reset by a pulse from the output of the amplifier 5. The generated rectangular impulses from the outputs of the triggers 6, // and 5 (see Fig. 2, d, g, e from;: the keys 12, 18 and 20 are recognized. Nai air with s

chihoda generator 16 stable frequency is fed to the input of the key 12 directly (see. Fig. 2 and), and to the input of the key 18 through the stage 17 of the delay (see. Fig. 2, k). The delay time ts of the delay cascade is chosen from the condition where /.,, is the pulse duration, and t ,; - repetition period of the stable frequency generator. Iri this

the number of PULSES at the outputs of the keys 12 and - I.18 different yV,: - + 1 (see. Fig. 2 l) and

L2 - +1 (see Fig. 2 m). These

-TO

The pulses are fed to the input of the adder 13, at the output of which the number of pulses yVo / Vi + A2 appears (see Fig. 2n). The voltage from the output of the stable frequency generator is also fed through a frequency converter 19 with a K-G -, conversion coefficient 19 to the input of the key 20. The output of this key is the number of integers K + 1 (see Fig. 2).

Lo pulses from the output of the adder 13 are fed to the summing input of the reversible counter 14, and to the subtractor - a series of pulses Lz from the output of the key 20. C is the number of pulses recorded in the reversing counter for one period of operation,

 D Lp - N., - - +1. If you choose tk 2. where / rt 0, 1, 2

The number of pulses L recorded in the reversible counter is equal to the transit time I: Q of ultrasound through the sheet material only.

The code from the reversible counter 14 is fed to a calculating unit 15, in which the known base of measurement 1 and the measured travel time determine the speed of ultrasound and is india on the display in digital form.

The proposed device makes it possible to measure ultrasonic velocity in a moving sheet material with high accuracy by reducing the dispersion of waves in the medium between the sheet material and the receivers, as well as by using digital circuits.

Claims (1)

1. Copyright certificate Ho 323738, cl. G 01 N 33/34, 1970. 2 USSR author's certificate L 502324, cl. G 01 N 33/34, 1974. / Hus. p u . Jn Li V, - t