SU868578A1 - Device for automated ultrasonic testing of articles - Google Patents

Description

one

The invention relates to non-destructive ultrasonic testing and can be used in the development of automatic control systems.

An ultrasonic device for the automated control of products is known, comprising a synchronizer, probing generators and pulse gating devices, a converter, an amplifier, a coincidence circuit, a control zone driver, an AND-NI Cl circuit.

The disadvantage of this device is the difficulty of detecting defects in the dead zone.

The closest to the proposed technical essence and the achieved result is the device for automated control of products, containing serially connected synchronizer, probe pulse generator, transceiver transducer with acoustic delay, amplifier, signal gating unit, control zone driver, coincidence circuit, the second input of which is connected to the output of the amplifier, and the fault detector, / afterbirth. coupled converter, t

located on the opposite side of the product coaxially with the transceiver transducer, a shadow signal gating unit, the second input of which is connected to the synchronizer output, an AND-N circuit and the surface signal gating unit, the first input of which is connected to the synchronizer output, and the second to

10 output amplifier f2j.

The disadvantage of this device lies in the low reliability of the control, since the amplitude of the shadow signal varies within large limits,

15 and therefore it is difficult to control the products with a rough surface.

The purpose of the invention is to increase the reliability of the control.

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The goal is achieved by the fact that the device is equipped with a shadow signal amplifier connected between the converter and the shadow signal gating unit, the first input of the NAND circuit is connected to the output of the surface signal gating unit, the second to the shadow gating unit OUTPUT, and the second the entrance to the forma30 of the control zone.

The drawing shows the block-cde ma. The proposed device.

The device contains a sequence. synchronously connected 1, generator 2 probe pulses, receiving and transmitting transducer 3 with acoustic line 4 delays, amplifier 5, block of gating of bottom signals, driver 7 of control zone, coincidence circuit 8, the second input of which is connected to the output of amplifier 5, and a signaling device 9 defects.

In addition, the device comprises a serially connected converter 10, located on the opposite side coaxially with the converter 3 of the product 11, a shadow signal gating unit 12, the second input of which is connected to the output of the synchronizer 1, and the AND-circuit 13, the surface signal gating unit 14 the input of which is connected to the output of the synchronizer 1, the second input to the output of the amplifier 5, and the amplifier 15 of the shadow signal connected between the converter 10 and the block 12 of the gating of the shadow signal.

The first input of the NAND 13 circuit is connected to the output of the surface signal gating unit 14, the second input to the output of the shadow signal gating unit 12, and the output to the second input of the driver 7 of the control zone.

The device works as follows.

The transducers 3 and 10, mounted on the test article 11 from two opposite sides, scan its surface during the inspection. When the trigger pulse is supplied from the synchronizer 1 to the generator 2 of the probe pulses at time t, the converter 3 is excited.

The pulse of ultrasonic vibrations, the passage through the acoustic line 4 delay and reflecting back from the surface of the product 11 ,. appears at the output of amplifier 5 at time t. The time interval t 2 is equal to twice the transit time of ultrasound in the acoustic delay line 4, i.e. Moreover, for normal operation of the device, it is necessary that the ultrasound time in the acoustic line 4 delays coincide with the ultrasound time in the monitored product il, TetTj ,,) Thus, at the output of the amplifier 15 of the shadow signal, a pulse of the shadow signal is also generated t2. the shadow signal allocated by gating unit 12 is fed to the AND-HE circuit 13, to the second {1 input to which the incoming surface echo signal from gating unit 14 of the surface signal.

The circuit IS-NOT 13 generates a signal to start the zone former 7. control only if there is a surface signal (there is an acoustic contact) and no shadow signal. The leading edge of the strobe pulse of the control zone is formed at the time t by the falling edge of the trigger pulse from the i-HE 13 circuit at the time point t reflected from the defect.

The falling edge of the strobe pulse of the control zone is formed at the time t by the leading edge of the pulse from the BOTTOM surface, and if there is no bottom signal due to the presence of an extended defect in item 11, the falling edge of the gate of the bottom pulse of block 6 at time 0 time t.

The strobe pulse of the control zone formed in this way, by the signal reflected from the defect, enters the input of the matching circuit 8, and the echo signals reflected from the defects from the output of the amplifier 5 arrive at its second input.

In the absence of defects in the product (the presence of a shadow signal) and a good acoustic contact (presence of a surface signal), the trigger signal of the former of the control zone 7 from the AND-NE 13 circuit is absent, and therefore, the control pulse of the control zone is not formed, and in the case of incoming pulses of output the amplifier 5 on the circuit 8 of the coincidence pulse trigger of the detector 9 is missing, which eliminates false positives.

If there are extended defects in the product (absence of a shadow signal) or local defects (a decrease in the amplitude of the shadow signal below a certain level), the I-NE 13 logic circuit receives a signal to trigger the sensor 7 of the control zone, while echoes reflected from the defects, The outputs coming from the output of the amplifier 5 to the circuit 8 of coincidence., are distinguished by the circuit triggering the detector 9.

If there is a surface signal and no shadow signal (due to a change in the product structure of the attenuation), the control zone pulse is generated, but by the coincidence circuit 8, the trigger signal of the alarm 9 is not generated, since there are no echo signals from defects, thereby increasing the reliability of the control.

Thus, the proposed device allows to increase the reliability of the control.

Claims (2)

1. USSR author's certificate No. 495602, cl. G 01 N 29/04, 1972. 2. USSR author's certificate on application 2543903/28, cl. G 01 N 29/04, 1978 (prototype).