SU1467461A1 - Method of ultrasonic check of article - Google Patents

Abstract

This invention relates to acoustic methods of non-destructive testing. The aim of the invention is to improve the accuracy of measurement of the characteristics of the defect by taking into account the individual characteristics of the radiation field - reception by using a set of information parameters of the received echo pulses of ultrasonic (US) oscillations. The surface of the product scan ultrasonic transducer. During the scan emit. and take the pulses of ultrasonic vibrations. Also scan the sample surface with a reflector. The distribution function of the amplitudes of the received echo pulses reflected by the defect of the product and the specimen reflector in time at fixed points of the surface is measured. The measured parameters determine the coordinates and depth of the reflecting points of the defect, beat. i (L

Description

one

The invention relates to acoustic methods of non-destructive ntrol and can be used to determine the configuration, size and position of a defect in ultrasonic (US) inspection.

The aim of the invention is to improve the accuracy of measurement of the characteristics of the defect by taking into account the individual characteristics of the radiation field - the reception of an ultrasonic transducer.

FIG. 1 shows a block diagram of a device that implements the method of ultrasonic control products; in fig. 2 - function) (x, y, s) in the x O, ly V / O region, obtained on a sample with a flat-bottomed square reflector.

in fig. 3 shows a flat-bottom defect configuration in an article; in fig. 4 — the function H (x, y, sd)) obtained by sounding the defect in FIG. 3; in fig. 5 - the function Ф (x, y, u)), calculated from the function i (x, y, oj) taking into account the function h (); in FIG. 6 shows the configuration of the sounded defect in accordance with FIG. 3

The method of ultrasonic inspection of products is carried out as follows.

An ultrasonic transducer is installed on the product and its surface is scanned at points with a given step. Ipulses of ultrasonic vibrations are emitted by a transducer and they receive the same reflected by the product 4 O5 4ib

O5

LIA pulses ultrasonic vibrations. At each time point, the magnitudes of the amplitudes Lf of the received echo pulse are measured at each fixed position x, y of the ultrasound transducer on the surface of the tested product, as a result of which the function if (x, y, t) is formed. The amplitude of the received echo pulse is measured during the time interval associated with the range of the control zone. When a product is tested with a speed C of propagation in it, ultrasonic vibrations in the depth range from to the interval Bpe meni, during which the measurements are carried out, are determined from the expression 2НД, "/ С t 2Н, s / С, and the moment initiation of ultrasonic transducer excitation by an electric pulse. An ultrasonic transducer is installed on the sample with a reflector and the sample surface is scanned at points with the same step cG. The ultrasonic pulses are emitted by the transducer, and the ultrasonic pulses reflected by the specimen reflector are received by the transducer. At each time moment t, the magnitudes of the amplitudes t of the received echo pulse at each fixed position x, y of the ultrasonic transducer on the sample surface are measured, as a result of which the function (, t) is formed. The time interval of reception in this case is similar to the time interval of reception during the sounding of the product. The function I is determined from the expression

l l

I || F (x, Y, s) - g. Z. H

 ftf

-X

j. YY, uJ)) l,

F (x, y, s) {

- 5 G1 + 1

 T -)

at

at (7A,

de p 4,5,6, ..., N;

D is the wavelength of ultrasonic vibrations in

materials of the product and sample;

O) 2ps, 1;

C is the speed of propagation of ultrasonic vibrations in the materials of the product and the sample;

j 1 2, i j

1 - 17 t. 1 i, z, ..., ь,

five; - coefficient characterizing

radiation field-reception ultrasound. converter (x. y, (v) - Fourier transform of the function

d (x, y, s) in time t. Coefficients / {and points x., Y. is chosen in such a way as to minimize the magnitude of the function I. The function is determined. F (x, y, s) of the expression

J L F (x, y, (x)) §: y if

/. one . Pri

-X j, y-Ur,),

where C (x, y, a) is the Fourier transform of the function

q (x, y, t) in time t.

A constant A is determined, depending on the level of noise and interference, for example, A is equal to half the maximum of the modulus of the function f (x, y, i). The coordinates of each of the reflecting points of the defect of the product are determined as the coordinates of points that satisfy the condition

1 t (x, y, ui) l / A

Determine the depth (Zo coordinate) of each of the reflecting points of the product defect from the expression

„.. h, Г I (f (x, y, u) l Л Z, (x ,, y,) arctg)

The set of reflecting points determines the orientation, configuration, and dimensions of the detected product defect.

A device for implementing the method of ultrasonic testing of products (Fig. 1) contains in series connected excitation pulse generator 1, analog-digital converter 2, memory block 3, calculation block 4, and indicator 5. In addition, the device contains a scanning mechanism 6, ultrasonic converter 7 mechanically connected to the mechanism 6 and electrically connected to the output of the generator 1 and the input of the analog-digital converter 2, and the block 8 of the synchronization electrically connected to geV

5 U nerator 1, converter 2, blocks 3 and D and the mechanism 6.

The method of ultrasonic testing of products is implemented as follows.

An ultrasonic transducer 7, for example, a direct transducer, is installed at a frequency of f 2.5 MHz with a contact area in the form of a square with a side of 10 mm on the surface of sample 9. The generator 1 excites a piezoelectric transducer 7, which emits ultrasonic pulses of the oscillations into the sample 9. Echo is received - pulses from the reflector 10 of sample 9, convert them by converter 7 into an electrical signal and feed into the input of converter 2, which converts analog information into digital. This information is accumulated in memory block 3. Using the scanning mechanism 6, the piezoelectric transducer 2 is moved along the surface of the sample 9 at points with a given step cf. The synchronization unit 8 synchronizes the operation of all nodes of the device. The accumulated information in block 3 is processed in block 4 of calculations and displayed on indicator 5.

The function t (x, y, u)) was obtained in the process of scanning by the converter 7 of sample 9, made in the form of a steel half-space (C 6 mm / µs) with a square flat-bottomed reflector 10 with dimensions of 1 x X 1 mm at a depth of 40 mm (Fig. 2). ), since t / (- x, y, uj) M (x, Y, s) d (x, y, s), then the region X -7/0, y 7/0 is shown. Based on this function, it obtains a matrix of 9x9 complex coefficients ff: {,

X. -8+ (j-1) X 2, mm

at j -8 + (1-1) X 2, mm

with j 1, ..., 9 and, ..., 9. Then a controlled product, also represented as a steel half-space, with a flat defect, located at a depth of 40 mm (Fig. 3) sounds similarly.

The function g (x, y, LLi) was obtained in the process of scanning by the transducer 7 of the test article (Fig. 4). From the above mathematical relations, the function F (x, y, i)) is determined, the module of which is shown in FIG. 5. According to .x, y, u)) the defect configuration is obtained

five

0

4h

| five

0

five

0

five

0

five

sixteen

A 0.5 max I F (x, y, i) 1 (fng, 6 The depth of the reflecting points of the defect is determined from the phase of the function F (x, y, a). The set of coordinates x, y, z of the reflecting points of the defect determines ultimately, its orientation, configuration, and dimensions.

The method of ultrasonic control of products increases the information content and reliability of the results of ultrasonic control due to a more accurate determination of orientatz and the configuration and size of the defect. When implementing the method of ultrasonic testing of products, the whole set of information parameters of the signals is used: amplitude, arrival time of the echo pulses and their shape, a priori information about the material of the tested product and the ultrasonic parameters of the flaw detector, including the spatial characteristics of the radiation field of the receiving transducer. The method of ultrasonic testing of products can be implemented even if the desired and standard reflectors are located at different depths. However, the lateral resolution (front resolution) increases with an increase in the depth difference between the target and reference reflectors up to 5 L and deteriorates by 1-5%, to 10 D - by 10-20%. For large ranges of the control zone (20A and more), it is advisable to split it into several overlapping subranges with a length of (8-10) and for each subband determine its points Xj, Y {and coefficients

g jt (JJ -T j. L) by measuring (x, y, and;) on a reference reflector that falls into this sub-band, for example, in the middle of its "Pitch" G scan by the transducer of the surface of the product and the sample is chosen from 0.5 A rf 4 A.

When choosing a scanning step less than half the wavelength of ultrasonic vibrations in the product and sample materials, the control labor intensity increases without increasing the accuracy of determining the coordinates and the depth of the reflecting points of the product defect, which is due to the wave structure of the radiation-receiving transducer field. When selecting a scan step greater than the wavelength, the accuracy of determining the characteristics of the defect of a product drops due to

reducing the number of detectable reflecting points of the defect.

Claims (1)

Invention Formula The method of ultrasonic testing of products, including scanning the ultrasound transducer of the product surface at points with a given step, radiation of ultrasound pulses by the transducer, receiving transducer of vibration oscillations reflected by the product defect, measuring parameters of received vibrations and determining the coordinates and depth of reflecting points of the defect of products by measured parameters, distinguished by the fact that, in order to improve the accuracy of measurements of the characteristics of a product defect, the additional O scan the surface of the reference sample with a reflector by points at the same step, take the converter reflected oscillations of the reference sample, measure the g (x, y, t) and (y, t) distributions of amplitudes over time t at fixed points the surfaces of the product and the reference sample, respectively, the coordinates of the reflecting points of the defect are determined by modulo the function l (x, y, w) l, and the depth of the reflecting points of the defect is determined by the function argument f (x, y, i)) 3 L (p (x, y, w) Zl t. SG.R- ( J P: 1 -X,., Yy, and)) where if4x, y, u)) is the Fourier transform of the function qi (x, y, t) with respect to time t; J 1 1.2 ,, .., L; o) 2ii f; f - filling frequency ultrasonic vibration pulses .. х., у - coefficients, which were considered at the decision systems 1Fo (V) x V O max, (FO (X, Y, S) X o min, U o 3 L , J Yoo-Yo.) , y, u)) is the Lurie transform of the function (x, y, u)) with respect to time t. f Rchg.1 BUT ..7Л7М | 7L7M .З 467461 l% 4yw / from FIG. 2  (x.y.t) Fy Fi.V