SU1633352A1 - Ultrasonic flaw detector - Google Patents

Abstract

The invention relates to the field of measurement technology and can be used in various fields of engineering for ultrasonic quality control of products. The purpose of the invention is to increase the reliability of control due to the compensation of noise of the electro-acoustic path. A 2 frequency divider, an input amplifier 5, a subtraction unit 6 and an analog-to-digital converter 9 are introduced into the device, which makes it possible to compensate the noises of the electroacoustic path of the flaw detector by subtracting in block 6 from a mixture of the useful signal and noise of the noise signal. 2 Il.

Description

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The invention relates to the field of measurement technology and can be used in various fields of engineering for ultrasonic quality control of products.

The aim of the invention is to increase the reliability of control by compensating for the noise of the electro-acoustic path.

FIG. 1 shows a functional diagram of an ultrasonic flaw detector; in fig. 2 - time diagrams that show his work.

The ultrasonic flaw detector (Fig. 1) contains a high-frequency generator 1, a divider 2 frequencies, a generator of 3 probe pulses, an ultrasonic transducer 4, an input amplifier 5, a subtraction unit 6, an adjustable amplifier 7, an indication block 8, an analog-to-digital converter (ADC) 9, a memory unit 10, a digital-to-analog converter (D / A converter) 11, an attenuator 12, and a distributor for 13 pulses.

High-frequency generator 1 is connected by one output to the input of the distributor 13 pulses and another output through serially connected divider 2 frequencies and generator 3 of probing pulses - to the input of ultrasonic converter 4, the output of which is connected through input amplifier 5 to one input of subtractor b. The latter is connected by another input to the output of the attenuator 12 and output via an adjustable amplifier 7 to the input of the display unit 8 and the information input of the A / D converter 9 connected by an output to the information input of the memory block 10, the output of which is connected to the information input of the DAC 11 connected to the attenuator input 12. Distributor 13 pulses are connected by the first, second and third outputs to control inputs of memory block 10, ADC 9 and DAC 11, respectively.

Ultrasonic flaw detector works as follows.

Previously, in order to eliminate the influence of the electroacoustic path of the flaw detector, the flaw detector memory unit 10 records the amplitude-time distribution of the noise fed to the input amplifier 5. To do this, install the ultrasonic transducer 4 on the tested defect-free product (or sample). The memory unit 10 is switched to the information recording mode. High-frequency generator 1 generates pulses fed to the input of the distributor 13 pulses, and also sends pulses through

divider 2 frequencies per generator 3 probe pulses, exciting ultrasonic transducer 4. In this case, from the output of the ultrasonic transducer 4 to

the input amplifier 5 receives the noise of the electro-acoustic path of the flaw detector, due to acoustic reverberation reflections in the ultrasonic transducer 4 and parasitic oscillations in the connecting wires (Fig. 2a). Noise through the input amplifier 5, the subtraction unit 6 and the adjustable amplifier 7 are fed to the input of the display unit 8 and to the information input of the ADC 9. Observe

5, the display of the signal indication unit 8, using the appropriate controller (not shown), sets the maximum gain of the adjustable amplifier 7. At the same time, the amplitude-time distribution of the noise is recorded in the memory unit 10. The operation of the A / D converter 9, memory unit 10, and D / A converter 11 is controlled by a pulse distributor 13, which generates the necessary signals for their operation.

5Before conducting control unit 10

the memory is transferred to the mode of reading information on the signal from the first output of the distributor 13 pulses. Install ultrasonic transducer 4 on

0 monitored item and monitored. In this case, the information in digital form about the amplitude-time distribution of the noise of the electro-acoustic path of the flaw detector from the memory block 10 enters (Fig. 2a) on

5, an information input of a D / A converter 11, which converts the obtained digital code into analog form and, via an attenuator 12, supplies an analog signal to one input of subtractor 6. The other input of the subtraction unit 6 receives the signal (Fig. 26) from the output of the ultrasonic transducer 4. Since the pulses of the component signal arriving at both inputs of the subtraction block b are equal in amplitude (due to the selection of the appropriate 5 attenuation coefficient of the attenuator 12), the noise The component of the output signal of the subtraction unit 6 and, accordingly, the adjustable amplifier 7 is zero. Therefore, only indication signals carrying information about defects are transmitted through the display unit 8 (Fig. 2c).

The use of the invention will significantly eliminate the noise of the electro-acoustic path of the flaw detector,

5 including, for signal-to-noise ratios smaller than one. The proposed flaw detector does not use frequency-dependent electrical circuits that are used in the known flaw detectors for detuning from low and high frequency

interference, as a result of the electroacoustic path of the flaw detector does not distort the shape and spectrum of the echo signal, which significantly increases the reliability and information content of the control.

Claims (1)

The invention Ultrasonic flaw detector containing a high-frequency generator, an ultrasonic transducer, an adjustable amplifier, a memory unit, a digital-to-analog converter, a display unit, an attenuator, a pulse distributor and a probe pulse generator, the output of which is connected to the input of the ultrasonic transducer, the memory unit is connected to the information input of the digital-to-analog converter, and the output of the adjustable amplifier is connected to the input of the display unit, which, in order to To increase the control accuracy, a subtraction block and an analog-to-digital converter are entered into it. an input amplifier and a frequency divider connected by an output to an input of a probe pulse generator, an input to one output of a high-frequency generator, another output of which is connected to an input of a pulse distributor, an output of an ultrasonic converter connected to an input amplifier that is connected to one input of a subtractor, another input connected to the output of the attenuator, and the output to the information input of the adjustable amplifier, the output connected to the display unit and to the information input of the analog-digital th transducer, connected to the data input of the output memory unit, an output digital to analog converter connected to the input of the attenuator, and the pulse distributor connected to the first, second and third outputs to the control inputs respectively analog-to-digital converter, and memory block DAC. j b AM v .s. V / t  ./h. .