RU1797043C - Method of ultrasonic defectoscopy of products with simultaneous acoustic contact quality control - Google Patents

Abstract

The invention relates to acoustic non-destructive testing methods. The aim of the invention is to simplify the implementation of the method using a direct transducer by providing the possibility of visual perception of information. For a specific product, the dependence of the amplitude of the transverse vibrations transformed during reflection from the bottom and –th and –th surfaces of the longitudinal vibrations, and the dependence of the amplitude of the longitudinal vibrations reflected on the standard reflector are determined, and this reflector determines the sensitivity of the control from the transverse dimensions of the active element of the direct transducer . The required size of the active element is selected at the intersection point of the dependencies. A direct converter 1 with the required size of the active element 3 is installed on the product 2 and emits longitudinal vibrations from it. The transducer 1 receives both the longitudinal vibrations reflected by the product 2 and the transverse ones resulting from the transformation from the longitudinal vibrations when the latter are reflected from the bottom surface of the product 2, and their amplitudes are measured. The magnitude of the amplitude of the received longitudinal vibrations determines the defectiveness of the product 2, and the magnitude of the amplitude of the received transverse vibrations determines the quality of the acoustic contact of the transducer 1 with the product 2. 2 il. H N B /////////// U (L S h o VJ o Ј b W

Description

Fia. 1

The invention relates to the field of acoustic non-destructive testing methods and can be used for ultrasonic (US) inspection of products with plane-parallel surfaces, for example, plates, forgings, etc.

A known method of ultrasonic inspection of products with quality control of acoustic contact, which consists in orienting the transducer relative to a product of great length and small cross section so that normal waves are excited, excite pulses of ultrasonic vibrations in the product, and accept ultrasonic vibrations propagating in one direction, the presence of defects is determined, and the quality of the acoustic contact is determined by the vibration parameters propagating in the other direction.

The disadvantage of this method is not wide enough because of the possibility of working only with products such as wire, tape, etc.

The closest in technical essence to the claimed is a method of ultrasonic inspection of products with acoustic contact quality control, which consists in the fact that ultrasonic vibrations are introduced into the product, ultrasound vibrations reflected in the product are received, their amplitude is measured, the magnitude of the amplitude of the bottom signal, the quality of the acoustic contact is evaluated and the magnitude of other echo signals determines the presence of defects, the ultrasonic vibrations used for flaw detection are excited and received by one active element, and Longitudinal ultrasonic vibrations, which are needed to control the quality of acoustic contact, are excited and received by another active element.

The disadvantage of this method is the relatively difficult implementation due to the need to use special equipment. Either the transducer must be equipped with a special active element that excites the signals used to assess the quality of the acoustic contact, or, if it is possible to receive this signal directly from the active element used for flaw detection, it is necessary to use special electronic units that ensure that the amplitude of the signals from the defects and the bottom signal are aligned on the screen of the flaw detector signal, because usually these signals vary significantly in amplitude.

The aim of the invention is to simplify the implementation of the method when monitoring with a direct transducer by providing the possibility of visual perception of information due to the use of transverse ultrasonic vibrations, transformed when reflected from the bottom surface of the emitted longitudinal ultrasonic vibrations.

The goal is achieved by preliminary determination of the dependence of the amplitude of transverse vibrations, transformed when reflected from the bottom surface of the longitudinal from the transverse dimensions of the active

0 element of the transducer and the choice according to this dependence of the required transverse size of the active element.

The essence of the invention is that first determine the relationship

5 the amplitude of the transverse vibrations, transformed when reflected from the bottom surface of the longitudinal, from the transverse dimensions of the active element of the transducer and the dependence of the amplitude of the reflected

0 from a standard reflector of longitudinal ultrasonic vibrations for a given sensitivity of the echo method, also from the transverse dimensions of the active element of the transducer. Then, according to the obtained dependences5, the transverse size of the active element of the transducer is selected, which corresponds to the equality of the amplitudes of these dependences. After that proceed directly to the inspection, for which

0, a direct ultrasonic transducer with a selected transverse size of the active element is mounted on the flat surface of the product, and pulses of longitudinal ultrasonic vibrations are introduced into the product with its help. 5 the pulses of ultrasonic vibrations reflected in the product are taken by the same transducer and their amplitude is measured. The presence of defects is judged by the magnitude of the amplitude of the echo signals, the propagation time of which

0 corresponds to the time interval between the time necessary for the longitudinal oscillations to cover the distance from the active element of the transducer to the input surface and vice versa and the time necessary for the longitudinal vibrations to overcome the distance from the active element of the transducer to the bottom surface of the article and vice versa. The quality of the acoustic contact between the transducer and the product is estimated by the magnitude of the amplitude of the transverse vibrations transformed by reflection of longitudinal vibrations from the bottom surface.:

Figure 1 presents a diagram of a method

5 ultrasonic inspection of products with quality control of acoustic contact; figure 2 is a graph of the amplitude AI of the transverse vibrations, transformed during reflections from the bottom surface of the longitudinal vibrations, on the diameter D of the piezoelectric element of the direct transducer (solid curve a) and a graph of the amplitude Az reflected from the standard flat-bottom reflector of longitudinal vibrations on the diameter D of the piezoelectric element pr converter (dashed curve b).

In Fig. 2, 1 denotes a direct ultrasonic transducer, 2 denotes a monitored article of thickness H, and 3 denotes the active element of the transducer 1.

The method of ultrasonic inspection of products with acoustic contact quality control is implemented as follows.

For a given thickness H of the controlled product 2, the dependence of the amplitude AI of the transverse vibrations, transformed upon reflection from the bottom surface of the longitudinal vibrations, on the transverse dimensions, for example, the diameter D of the active element of the transducer 1, is determined. When installed on a defect-free portion of the product 2 or an identical sample The direct ultrasonic transducer 1 emits longitudinal wave pulses to it. As a result, any direct transducer has a certain radiation pattern, a part of the oscillations emitted by it falls onto the bottom surface at an angle and, when reflected, is transformed into transverse vibrations, which return to the transducer 1 and are received by it. The amplitude of the transformed transverse vibrations it receives depends on the transverse dimensions of the active element 3, for example, the diameter D of the piezoelectric plate, since with a change in the diameter D the range of angles of incidence of the longitudinal vibrations changes, transforming precisely into the transverse vibrations that are received by the transducer 1, and, accordingly , changes due to the function describing the radiation pattern of element 3 and the reflection coefficient must be taken into account. The experimentally obtained results on a 1420 material with a thickness of 30 mm using a set of Krautkramer transducers at a frequency of 2 MHz are presented in Fig. 2 of curve a. Also, for this thickness And, the dependence of the amplitude A2 of the longitudinal vibrations reflected from the standard reflector for a given echo control sensitivity on the diameter D of the active element 3 of the transducer 1 is determined. To do this, the same set of transducers are alternately mounted on a standard sample with a flat-bottom reflector of 0 1.2 mm lying at a depth of 30 mm. which determines the sensitivity of the echo control, and measures the amplitude A2 5 of the echo from the reflector. The results are presented in figure 2 curve b. From the graph it follows that the curves intersect at mm, which corresponds to the type of transducer K2. A K2 type converter 1 is mounted on the surface of the article 2, emits longitudinal ultrasonic vibrations from it, and scans the product 2. Most of the longitudinal vibrations propagate normally on the input surface and if

5 of the article 2, defects are reflected from them and returned to the transducer 1, as well as to the longitudinal wave bottom signal. A part of the longitudinal vibrations falls on the bottom surface at an angle and, reflecting,

0 is transformed into transverse vibrations and also hits the transducer 1. Transducer 1 takes all the vibrations received on it and they are observed in the form of echo pulses on the screen

5 flaw detectors. The presence of defects is judged by the magnitudes of the amplitudes of the longitudinal vibrations received by the transducer 1 and lying on the screen of the ultrasonic flaw detectors between the probe and bottom pulses. In the case of the presence of defects, the amplitude of these pulses exceeds the threshold level. . The quality of acoustic contact is estimated by the magnitude of the amplitude of the transverse vibrations received by the transducer 1 and corresponding to the arrival time by the sum of the propagation time of the longitudinal and transverse vibrations from the active element 3 of the transducer 1 to the bottom surface of the article 2. On the deterioration

0 contact quality indicates the failure to achieve the amplitude of these pulses at the threshold level. Due to the choice of size D in the above manner, the operator is able to simultaneously observe on

5 of the flaw detector screen, with its stationary gain by sweep, the position of the pulses carrying information about the defects and the quality of the acoustic contact relative to the threshold level.

0 We can allow some inequality of the amplitudes AI and Aa when choosing the size D, if the dynamic range of the flaw detector screen allows the operator to simultaneously track the height of the pulses carrying

5 information on defects and quality of acoustic contact.

Claims (1)

The claims The method of ultrasonic flaw detection of products with acoustic contact quality control, which involves introducing ultrasonic vibrations into the product, receiving ultrasonic vibrations reflected in the product, measuring their amplitude, evaluating the quality of the acoustic contact by the magnitude of the amplitude of the bottom echo signal and by the magnitude the amplitudes of other echo signals are judged by the presence of defects, characterized in that, in order to simplify the implementation of the method when using a direct transducer, it is previously determined l dissolved dependence transverse amplitude kole0 5 beating transformed at reflections reflected from the bottom surface of the longitudinal, from the transverse dimensions of the active element of the direct transducer and the dependence of the amplitude reflected from the standard reflector of longitudinal vibrations for a given sensitivity echo control on the transverse dimensions of the active element of the direct transducer, from which the transverse size of the active element of the direct transducer corresponding to the equality of amplitudes, and the quality of the acoustic contact is estimated by the magnitude of the amplitude n transverse oscillations transformed by reflection from the bottom surface of the longitudinal oscillations.  A, 9Ag dv -fifty / 5 S 15 20 Lm Fig. 2