SU1619064A1 - Method of measuring speed of ultrasonic waves - Google Patents

Abstract

The measurement relates to measurement technology and can be used to control the properties of materials based on the measurement of the velocity of ultrasound in them. The purpose of the invention is to improve the measurement accuracy by using higher amplitude pulses with steeper edges. At the same time, electroacoustic transducers, which emit longitudinal ultrasonic waves of a limited duration normal to the surface of the product, located in the immersion liquid bath, from opposite sides relative to this product, are excited. In receive mode, each of the transducers first receives a pulse reflected from the external surface of the product, then a pulse that passes once through the product. The time intervals between the probe pulse and the received pulses are measured, which determine the speed Cg of ultrasound in the material of the product Cg 2L - C0 (c (+ + c2) / 2se-and + tt), where L is the distance between the transducers; CQ is the ultrasound velocity in the immersion liquid; t (is the time interval between the probe and reflected impulses received from one converter; t- is the time interval between the probing impulses and the reflected impulses received from another transducer; and c is the time interval between the probing impulses and the impulses once passed through the product. 3 or . Ј3 & Cfc

Description

The invention relates to a measuring technique and can be used to control the properties of materials of products based on measuring the speed of ultrasound in them.

The purpose of the invention is to improve the measurement accuracy by providing a smaller difference in amplitudes of received signals.

Figure 1 shows an example of a device for implementing the proposed method; 2, 3 are timing diagrams explaining his work.

A device implementing the proposed method comprises a bath 1 with an immersion liquid, into which product 2 is placed, two electroacoustic transducers 3 and 4 located in bath 1 coaxially at a known distance, a generator 5, the output of which is connected to a converter 3 and 4, two amplifiers b and 7 pulses, the inputs of which are connected to converters 3 and 4, and the outputs to the switch 8, the selector 9, in the closed state, do not let through only

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the first pulse following the probe pulse, the selector input 9 being connected to the output of the switch 8 and measuring 10 time intervals, one input of which is connected to the output of the selector 9, and the other - to the synchronous output of the generator 5.

The method is carried out as follows.

The generator 5 simultaneously excites transducers 3 and 4, which emit longitudinal ultrasonic waves of limited duration. In the reception mode, each of the transducers first receives a pulse reflected from the external surface of the product (Fig. 2, 3, signal I and II), then a pulse that passed once through the product (Fig. 2, 3, signal III). Amplifiers 6 and 7 amplify and detect the pulses for subsequent registration. Using the switch 8 through the selector 9 to the meter 10 time intervals first connect the channel of the Converter 3 (Fig.2), then the channel of the Converter 4 (fig.Z). A time interval meter 10 measures the time between the probe pulse and the next pulse coming from the selector 9. The time t and tg are measured with the selector open, the time t-j with the selector closed.

The speed of longitudinal ultrasonic waves in IMMEDIATION taking into account known dependencies is determined by

С 2b-Z 9oiHJ ± Ј2j 2t5- (t, + t2) where L, is the distance between the transducers;

C.- ultrasound velocity in immersion liquid; t, is the time interval between the probe pulse and the reflected pulse received from one transducer;

t, is the time interval between the probe pulse and the reflected pulse received from another transducer;

t - time interval-in probe pulse and pulse, once passed through the product. Due to the fact that in the proposed method for measuring the speed of the ultrasound, pulses that are reflected once from the external surfaces of the product, and pulses that are once4 passed through the product that are very intense and 5 are recorded reliably, are associated with by stretching the leading edge of the pulses, is reduced by 4 to 5 times in comparison with the known method. No measurement of the acoustic base value of the product to determine the ultrasound velocity in the product material is required, which also contributes to an increase in the measurement accuracy.

Claims (1)

Invention Formula A method for measuring the speed of ultrasonic waves, consisting in the emission of ultrasonic waves normally 0 to the surface of the product being in the bath with immersion liquid, receiving longitudinal ultrasonic waves that passed through the product once and measuring time intervals between 5 remote control pulses, which determine the ultrasound velocity in the material of the product, characterized in that, in order to improve the measurement accuracy, ultrasound waves 0 emit simultaneously in opposite directions, receive ultrasonic wave pulses reflected from external surfaces of the product, time intervals are measured between the probe pulse and the received pulses, the product size and the propagation time of the ultrasonic waves in the product are determined by the measured time intervals calculate the ultrasound velocity in the material of the product. // ///