SU762539A1 - Device for measuring ultrasoiund propagation rate in moving sheet material - Google Patents

Description

The invention relates to the field of non-destructive testing by the ultrasonic method and can be used to measure the mechanical and other parameters of moving sheet materials.

A device for measuring the velocity of propagation of ultrasonic oscillations, containing emitting and receiving transducers, amplifiers and a pulse generator [1].

A disadvantage of the known device is low noise immunity.

The closest to the invention in technical essence and the achieved result is a device for measuring the propagation speed of ultrasound in a moving sheet material, containing a series-connected probe pulse generator, a radiating transducer, a receiving transducer, an amplifier, a first pulse shaper, a “Forbid” circuit, a second pulse shaper, a time interval meter, the second input of which is connected to the output of the probe pulse generator, and 'also the driver ryamougolnyh pulses, whose output is connected to the second input circuit "ban" [2].

2

A disadvantage of the known device is low noise immunity, since 'with an increase in the propagation time of the acoustic signal ’, the time before the arrival of the input pulse, during which the Inhibit scheme will be opened, increases.

The aim of the invention is to improve the noise immunity.

1 ° The goal is achieved by the fact that the device is equipped with connected between the second pulse shaper and the shaper of rectangular pulses in series., Connected by a trigger,

15 the second input of which is connected to the output of the probe pulse generator, an integrator, an amplitude-storage unit, a key and an inverter amplitude - time, an 'output ^{- of} which''is connected "

20 with the input of the rectangular pulse shaper, and the third pulse shaper connected between the probe pulse generator and the key.

The drawing shows a block diagram

25 devices.

The device contains a series connected probe pulse generator "emitting transducer 2,

‘Receiving transducer 3, amplifier 4, 30 first driver 5 pulses, circuit

762539

3

6 "Prohibition", the second shaper 7 pulses and meter 8 time intervals, the second input of which is connected to the output of the generator 1 probe pulses, the shaper 9 rectangular pulses, the output of which is connected to the second input of the circuit 6 "Prohibition".

In addition, between the second pulse shaper 7 and pulse shaper 9 are connected in series the trigger 10, the second input of which is connected to the output of the probe pulse generator 1, the integrator 11, the amplitude-storage unit 12, the key 13, and the transducer 14 amplitude - time, the output of which 9 rectangular pulses are connected to the shaper input.

Between the probe pulse generator 1 and the key 13, a third driver 15 pulses is turned on.

The device works as follows.

The generator G of probe pulses emits an acoustic pulse into the medium under study, which excites acoustic signals in the receiving transducer. The received signals are amplified by the amplifier 4, are formed by the shaper 5 pulses and are fed to the "Ban" b circuit, which is closed in the initial state. At the same time, the pulse from the output of the generator 1 is fed to one input of the trigger 10 and the input of the driver of the 15 pulses. To the second input of the trigger 10, amplified and formed useful signals and signals from the output of the shaper 9 square pulses are applied. The output pulses from the trigger 10 are fed to the integrator 11, which forms the pulses, the amplitude of which is proportional to the duration of the pulses produced by the trigger. The pulses produced by the integrator are rectified, memorized by the amplitude-storage unit 12 and fed to the key 13, which is controlled by the driver 15 pulses. This pulse shaper is triggered by a probe pulse generator 1. Thus, key 13 is opened for ΙΟΙ 5 μs. During this time, a constant voltage, the magnitude of which is proportional to the propagation time of acoustic pulses in the material under study, is fed to the transducer 14 amplitude — the time that generates rectangular-shaped pulses of constant amplitude, the duration of which is proportional to the amplitude of the input signals. The falling edge of the pulses produced by the transducer 14 triggers the shaper of 9 rectangular pulses, forming pulses with a duration of 20-30 μs, which are fed to

the second input of the ban 6 scheme and open it. The steepness of the linearly varying voltage of the integrator is chosen in such a way that the interdiction circuit 6 opens 2-3 ms before the arrival of the useful signal. With an increase in the propagation time of acoustic signals in the material under study, the duration of the pulses produced by trigger 10 and, consequently, by the transducer '14, the prohibition circuit 6 will open later (and vice versa).

Thus, the time interval with a duration of 20-30 μs, during which the prohibition scheme 6 remains open, will be floating and will monitor the change in the propagation time of acoustic pulses in a moving paper web. Due to this, the probability of the appearance of interference pulses, preceding the arrival of the useful signal, is reduced. Therefore, increases the noise immunity of the device.

Claims (1)

Claim Device for measuring the speed of propagation of ultrasound in a moving sheet material, containing sequentially connected probe pulse generator, radiating transducer, receiving transducer, amplifier, first pulse shaper, “Forbidden” circuit, second pulse shaper and time interval meter, the second input of which is connected to the generator output pulsing pulses, I also have a rectangular pulse shaper, the output of which is connected to the second input of the “Forbid” circuit, Due to the fact that, in order to improve noise immunity, it is provided with serially connected trigger connected between the second pulse shaper and the shaper of rectangular pulses, the second input of which is connected to the output of the probe pulse generator, integrator, amplitude-storage unit, key and converter amplitude - time, output which is connected to the input of the rectangular pulse shaper, and the third pulse shaper connected between the probe pulse generator and the key.