SU1234768A2 - Ultrasonic through-transmission immersion flaw detector - Google Patents

Abstract

The invention relates to the field of non-destructive testing and can be used to control products in the metallurgical, engineering and other industrial sectors. The purpose of the invention is to increase the reliability of control by suppressing the effects of interference caused by changes in the quality of acoustic contact and equal changes in the amplitude of all pulses of all multiple reflections produced in a controlled article. In the situation No defect at the output of the amplifier, there is a sequence of pulses that underwent repeated reflection within the controlled article. These signals are fed to the inputs of the time discriminator and the first and second amplitude-time discriminators. The time discriminator builds an h-transmitted pulse, the amplitude of which of negative polarity is stored in the memory block and fed through a voltage divider to the third input of the amplitude-time discriminator. Invention - supplementary to auth.St.№ 932395. 2 Il. i (L y w O5 00 K)

Description

one

The invention relates to the field of non-destructive testing and can be used to control products in the metallurgical, engineering and other sectors of the industry and is an improvement of the known device according to the author. No. 932395.

The aim of the invention is to increase the reliability of control by suppressing the influence of interference caused by changes in quality and equally varying amplitudes of all pulses of multiple reflections produced in a controlled article.

FIG. 1 is a functional block diagram of the ultrasonic shadow immersion flaw detector of FIG. 2, are timing diagrams explaining the operation of the device.

one

The ultrasonic shadow immersion flaw detector contains a series-connected probe pulse generator 1, acoustically coupled radiating and receiving transducers 2 and 3, amplifiers 4, the first amplitude-time discriminator 5 with a second input connected to the second input of the probe pulse generator 1, the first trigger 6, the differentiating circuit 7 , circuit 8 OR, second trigger 9, and recorder 10, made of series-connected delay circuit 11, driver 12 interrogation pulse, circuit 13 AND, first and second ele tronic keys 14 and 15, the second input of AND circuit 13 is input to the registrar 10, the second input of the second electronic switch 15 and the input of the delay circuit 11 are combined and connected to the output of the generator 1, the probing pulse; the second amplitude-time discriminator 16, the first input of which is connected to the output of the amplifier 4, the second input to the third output of the probe pulses generator 1, the output of the second amplitude-time discriminator 16 is connected to the second input of the first trigger 6 connected in series to the third amplitude-time discriminator 17 and the third trigger 18, the output connected to the second input of the IZH circuit 8, the first input of the third amplitude-time discriminator is connected to the output of the amplifier 4, its second input to the fourth output of the generator Ator 1 probeiruyup; them

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pulses, the third input of the first trigger 6, the second inputs of BTOpoj o and the third trigger 9 and 18 are combined and connected to the fifth output of the probe pulses generator 1, connected in series temporal discriminator 19, memory block 20 and divider 21, Temporary discriminator input 19 connected to the output 0 of the amplifier 4, its second input is connected to the second output of the generator 1 of probe pulses, the second input of the memory block 20 is connected to the fifth output of the generator 1 of probe 15 pulses, the output of the divider 21 is connected to the third input of the second ampl tudno-time discriminator. Position 22 marked the controlled product.

20 Ultrasonic shadow immersion flaw detector works as follows.

The generator I of probe pulses periodically generates probe probes (Fig. 2a), an input to the radiating transducer 2. At the same time, it generates reset pulses (Fig. 2f), which are reset by the triggers 6,

30 9 and 18, recorder 10 and memory block 20. The reset pulses have a duration that overlaps all possible interferences that may occur in the blocks when sending a powerful

5 probe pulse, and thus prohibit the false triggering of triggers after sending. With a certain delay in the time determined by the propagation time of the corresponding signals in the acoustic path, strobe pulses of the hth transmitted pulse (fig.2g), the tth transmitted pulse (fig.2e) and the impulse are generated in the probe pulse generator 1.

45 pulse passed through water in the absence of a controlled sheet (Fig. 2, e). FIG. 2 take 1, t 2, i.e. 1 and P passed pulses.

Ultrasonic pulses excited by the emitting transducer 2 propagate in the immersion liquid 1BO1. Further consideration is advisable for three situations: there is no controlled product between converters 2 and 3 (There is a BoD situation; between converters 2 and 3 there is a defect-free product (No situation between converters 2 and 3 there is a defective product f situation Defect) These three situations correspond to the three columns in FIG. 2.

In the presence of a situation, the Water ultrasonic signal of a large amplitude passes through the acoustic path, hits the receiving transducer 3 and is amplified by the amplifier 4. The large amplitude signal (Fig 2b) coincides in time with the strobe (Fig.2e) and triggers the amplitude-time discriminator 17 ( figm). The signal from the output of the amplitude-time discriminator 17 is fed to the input of the trigger 18 and switches it to state 1 (FIG. 2n). This single signal passes through the OR circuit 8 (Fig. 2, O and is fed to the input of the trigger 9, its transfer to the state O (Fig. 2p). The signal O is fed to the input of the recorder 10, prohibiting the registration of the defect. A reset pulse (Fig. 2b) turns off the key 15 for the duration of its existence, which then breaks the key's current circuit .14 The key 14 is turned off and prepared for the next operation cycle. Simultaneously, a reset pulse (Fig. 2b) starts the delay circuit 11. The output signal of the delay circuit 11 starts driver polling pulse 12. The output pulse of this pho The lighter 1fg.2r) is delayed relative to the reset pulse for a time slightly longer than the maximum propagation time of the analyzed ultrasonic signals (the 1st transmitted pulse and the water pulse). The pulse of the driver 12 polling pulses and the output signal of the trigger 9 are fed to the input of the circuit 13 I. The output signal of circuit 13 And unlocks key 14. In a situation, Water from the output of flip-flop 18 to the input of circuit 13 And a signal O is received, a signal at the output of the circuit .13 And is absent and no recording is done.

In the situation No defect at the output of the amplifier 4, there is a sequence of pulses that have undergone multiple reflections inside the controlled product 22. These signals are fed to the inputs of the time discriminator 19 and the amplitude-time discriminators 5 and 16. The time discriminator 19 gates the transmitted pulse, the amplitude of which (negative polarity) is stored in memory block 20 and, through voltage divider 21, is applied to the third input of the amplitude-time discriminator 16. At the same time, in the amplitude-time discrimination Ore 5 h-ro amplitude of the transmitted pulse is compared with a constant threshold voltage. When the threshold is exceeded, which must be observed when a defect-free product is sounded, the amplitude-time discriminator 5 generates a pulse (Fig. 2g), which translates trigger 6 from state 1 to state O (fig. 2i). When the transition of the mth transmitted pulse coincides in time with the corresponding strobe (Figure 2EI, the amplitude-time discriminator 16 compares the amplitude hr-ro of the transmitted pulse with the memorized voltage of the 6th transmitted pulse, which is used as the threshold pulse. Thus, The threshold voltage of the discriminator 16 depends on the changes in the amplitude of the transmitted signals caused by the instability of the acoustic contact. If the amplitude of the mth transmitted pulse is greater than the threshold, this should be done when the sound is heard. In this case, the amplitude-time discriminator 16 generates a pulse (Fig. 2h), which translates a trigger from state O to state 1 (Fig. 2i). Thus, a negative pulse is generated at the output of trigger 6 when monitoring a defect-free product (Fig. 2i), the leading edge of which corresponds to the arrival of the first passed and the falling edge of the arrival of the transmitted pulse h. This pulse is differentiated by a differentiating circuit 7 and a positive pulse (Fig. 2k) corresponding to the trailing edge of the trigger pulse passes through schemes 8 OR (fig.2o) and flips trigger 9 from state 1 to state O (fig.2p). As a result, the signal O is received at the input of the circuit 13 AND of the recorder 10, the signal at the output of the circuit 13 And is missing and no recording is made. In a situation, the Defect p-s and Nl-th transmitted pulses are further attenuated in amplitude as compared with the case of sounding a defect-free product, figure 2 shows the situation when the amplitude of the h-th transmitted pulse decreases due to the presence of a defect.

insignificantly, while the p-pulse and the past pulse still exceeds the threshold of the amplitude-time discriminator 5 (Fig. 2g), and the amplitude of the s-th past pulse becomes less than the memorized level of the amplitude of the h-th past pulse (Fig. 2e), and amplitude-time discriminator 16 does not produce a pulse at the time of arrival of the h-th past. As a result, the flip-flop 6 does not reverse from the state O to state 1 (Fig.2i), there are no positive pulses on the output X of the differentiating circuit 7 (Fig.2c and the OR circuit 8 (fig.2o) flip-flop 9 remains in the state 1. A high level is applied to the input of circuit 13A of registrar IO, and when a polling pulse arrives at its second input (FIG, 2p), the output signal of circuit 13A opens key 14, and a recording current flows in registrar 10 (fig.2c). 14 will be turned off by opening the key 15 at the moment of arrival of the reset pulse of the next device operation cycle When testing a product at a point where there is a defect, other situations are possible: the amplitudes of both h-ro and hi-th transmitted pulses are weakened, and there will be no pulses at the output of both amplitude-time discriminators 5 and 16; only the amplitude of the h-th transmitted pulse and there will be no pulse only at the output of amplitude-time discriminator 5, and the pulses at the output of amplitude-time discriminator 16 will exist. However, these situations correspond to one feature common to those considered above: when using trigger 6 with separate inputs, there will be no transfer of it from state O to state I on the time interval for the end of the reset pulse of the given clock cycle until the next pulse is reset. Consequently, there will be no positive pulses at the output of the OR circuit 8, the trigger 9 will remain in state 1 and will occur

defect record.

The occurrence of a positive pulse at the output of the differentiating circuit 7 at the moment when the flip-flop 6 is switched to state 1 by a reset pulse at the beginning of the cycle does not cause a false trigger of the recorder 10, since the flip-flop 9 is kept at that time by the same reset pulse 1.

The invention makes it possible to reduce the level of metal rejection at a given level of control sensitivity, or to increase the sensitivity of a control at a given reliability level.

Claims (1)

Invention Formula Ultrasonic shadow immersion flaw detector according to aut.S.N. 932395, characterized in that, in order to increase the reliability of the control, it is equipped with serially connected time discriminator, memory unit and divider, the time discriminator input is connected to the amplifier output, its second input is connected the second output of the probe pulse generator, the second input of the memory unit is connected to the fifth input of the probe pulse generator, the divider output is connected to the third input of the second amplitude-time discriminator . a 2 defect I f f II r 17 i, 1 FIG 2 Editor L.Avramenko Compiled by K. Leonov Tehred I.Popovnch Order 2979/48 Circulation 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Prog str .;): -cha, 4 Proofreader I. Muska