SU1610434A1 - Method of acoustic inspection of quality of articles - Google Patents

Abstract

This invention relates to acoustic methods of non-destructive testing. The aim of the invention is to increase the reliability of control of products with a regular relief surface by providing almost the same sensitivity as in the control of smooth areas, and in the control of areas with a regular relief surface. The step of the surface irregularities is measured. A layer of material with a non-linear acoustic parameter not less than 24 is applied to the surface of the product insertion. An ultrasonic transducer is installed on the layer and vibrations are excited with its help, the wavelength of which is equal to twice the pitch of irregularities and the power is sufficient for the material to show non-linear properties. The oscillations passed through the product are taken, their parameters are measured and the quality of the product is determined with their help.

Description

The invention relates to acoustic methods of non-destructive testing and can be used in ultrasonic inspection of products with a regular embossed input surface.

The purpose of the invention is to increase the reliability of testing products with a regular relief surface by providing almost the same sensitivity when monitoring smooth areas and controlling areas with a regular relief surface.

The essence of the method of acoustic quality control of products is as follows.

A medium with a non-linear acoustic parameter not smaller than 24 is applied to the surface of the product. Acoustic oscillations are introduced into the product through this contact medium, the frequency f and the power M of which satisfy the conditions:

f c / 2t; -M 0.9,

where c is the velocity of oscillations propagation in the contact medium; t is the pitch of the irregularities of the surface relief of the product; Accept the oscillations that have passed through the product; measure the parameters of the received oscillations and use them to determine the quality of the product

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The method of acoustic quality control of products is carried out as follows.

The step t of the surface irregularities of the product is measured. A layer of material with a nonlinear acoustic parameter selected from the condition 65:24, such as OS-51-03 organic silicate material (oligomethylphenylsiloxane unmodified silicate with chromium and titanium oxides, 25), is deposited on this surface with pneumatic dissolution; The optimal coating thickness is determined experimentally. Typically, the thickness is equal to or slightly higher than the height of the irregularities. After the coating has hardened, a layer of water is applied to it and an ultrasonic transducer is installed. The transducer excites pulses of ultrasonic vibrations with frequency f and power M chosen from the conditions:

f c / 2t;

-MB 0.9,

where c is the velocity of oscillation propagation in the material OC-51-03 (from 2245 m / s).

When a plane monochromatic wave is incident on a surface covered by a medium with nonlinear acoustic properties, the wave front of the incident wave is reversed, which is reflected in the fact that during the second interaction with the incident wave, the latter is amplified. surface irregularities, as it were, are not noticed. This effect is observed at an arbitrary angle of incidence of the wave on a rough surface. At the same time, oscillations from surface irregularities occur with a wavelength of 2t. Ultrasonic vibrations transmitted through the product are received, for example, reflected from its bottom surface during mirror-shadow monitoring, their amplitude is measured, and the quality of the product is determined from it. So, when using material OC-51-03, the amplitude of the bottom signal for a product

20 mm in the area with the surface R 2.5 is equal to the amplitude of the bottom signal in the area with the surface R 80-120, while using b as the contact medium of water, the difference in amplitudes in these areas is 10 dB.

OS-51-03 materially exhibits nonlinear properties when a piezoelectric element is excited from PZT-19 (electromechanical coupling coefficient is 0.7) with a probe pulse with an amplitude of 150 V, which corresponds to a wave intensity of about 2, EIT-W / cm.

The variation of the amplitude of the bottom echo signal at a frequency of 2.5 MHz using the material OS-15-03-when monitoring a product with a regular relief surface is 2 dB, while using for the same product as the contact medium of water gives a variation 6 dB.

Claims (1)

Invention Formula The method of acoustic quality control of products, which consists in applying a contact medium to the surface of the product, introducing acoustic oscillations through the contact medium into the product, accepting oscillations passing through the product, measuring the parameters of the received oscillations and determining the quality of the product , characterized in that, in order to increase the reliability of control of products with a regular relief surface, a medium with a value of non-linear acoustic parameter S not less than 24 is used as a contact medium, and often From f and power M introduced into the product of oscillations choose from the conditions: f c / 2t; eM 0.9, where c is the velocity of oscillations propagation in the contact medium; t - step irregularities of the surface relief of the product.