SU502324A1 - Device for measuring the speed of ultrasound in a moving sheet material - Google Patents

Description

second, it is equal to the amplitude value of three / g pulse of the voltage divider output.

The voltage from the peak detector is fed to another input of the comparison circuit 9. At the time point, when the voltage at both inputs becomes equal, the comparison circuit 9 produces a short electrical pulse (plot IX). This pulse is shifted relative to the pulse of the pulse of the generator 5 by the time interval TO, i.e., by the time equal to the propagation time of the sounding acoustic pulse from the sheet of material to the main receiver of acoustic oscillations. The impulse received in the comparison circuit triggers trigger 12 (plot XII). The electric pulse of the generator 5 is supplied to the radiator 13 and excites an acoustic pulse in the moving sheet material. This probing augustic pulse propagates partially over the sheet material, is radiated into the air and is received by the main receiver J4.

FIG. 1 shows the block: the K-circuit of the device, the circuit contains the master oscillator /, the first amplifier 2, the first shaping device 3, the first trigger 4, the generator 5 probe pulses, the generator 6 triangular pulses, voltage divider 7, peak detector 8, the comparison circuit 9, the second amplifier 10, the second forming device 11, the second trigger 12, the emitter 13, the main receiver 14 acoustic oscillations - auxiliary emitter 15, the auxiliary receiver 16 acoustic oscillations.

FIG. Figure 2 shows the Aiuruses of the IMU pulses obtained at different nodes of the measuring tract during the same measurement period.

The device works as follows. Initially, the master oscillator 1 excites the auxiliary emitter 15 simultaneously tilting the trigger 4. The acoustic impulse spreads in the air to the moving sheet material ./7, reflected and received by the auxiliary receiver 16 acoustic oscillations. The received acoustic emulsion is amplified by amplifier 2 (plot II). The time shift between the pulse of the master oscillator and the received reflected pulse is 2to, where t is (I-

the distance between the receiver 16 and the sheet material, au is the speed of acoustic oscillations in the air environment). The signal from the output of amplifier 2 is fed to the forming circuit, which the received signal converts into a short pulse of constant amplitude (plot III). This impulse topples

trigger 4 (plot IV) and starts the probe pulse generator 5 (plot V).

From the output of the receiver, the received signal is fed to amplifier 2. From the output of amplifier

the impulse goes to the forming circuit (plot XI), the output signal of which overturns the trigger 12 (plot XII). The duration of the pulses at the output of the trigger 12 is equal to the time of propagation of the probing acoustic pulses through the sheet material TC. If we compare the diagrams V and X, then it can be seen that the propagation time of the probing signal Trtr + TO, but with the help of an additional electro-acoustic system, is eliminated. With a known measurement base / and

measured t ,, according to the formula v - accurately determined

the ultrasound velocity is made in the moving sheet material. In order for the probing and additional electronic-acoustic systems not to have parasitic connections, they operate at different frequencies.

Since the device provides a measurement of the rate of propagation of acoustic

fluctuations in the sheet material, by removing the signal without the HKTaiKTHoro signal, and automatically eliminates the acoustic signal propagation time in the air gap and between the sheet material and the receiver; reliability and accuracy of measurement is greatly enhanced.

Claims (1)

Invention Formula  An apparatus for measuring the velocity of ultrasound in a moving sheet. Material, e.g. paper, comprising a probe pulse generator, an emitter and a main receiver of acoustic oscillations and a measurement circuit, characterized in that, in order to improve the measurement accuracy, it is equipped with an all-coherent emitter and receiver of acoustic oscillations installed next to the main receiver, and the measurement circuit contains the leading IM generator (yes, Tiparrepa, a rectangular pulse generator and a comparison circuit, and the leading generator a pulse is connected to an auxiliary emitter and an input of the first trigger, the second input of which is connected to a probe pulse generator and by means of a forming circuit with an auxiliary receiver, and the output is connected to a triangular pulse generator, the output of which is connected directly to one of the inputs of the comparison circuit, and the second through a voltage divider and a peak detector, the output of the comparison circuit being connected to one of the inputs of the second trigger, the second input of which is connected to the main through the second forming circuit priemniko.m acoustic oscillations.