SU1049798A1 - Process for reflection-transmission ultrasonic inspecting of parts with constant cross-section - Google Patents

Abstract

METHOD OF MIRROR-SHADOW ULTRASONIC CONTROL OF EQUAL SECTION PARTS, which consists in introducing two ultrasonic waves into the product through a common insertion point, moving the insertion point and registering OL signals that are different from the opposite surface of the product, in order to increase the reliability control and noise immunity, input of waves is carried out in one direction, the ratio of the lengths of the trajectory of the movement trajectory points of entry, within which the amplitudes of the signals are reduced, are determined reference value, and in this respect the court so the presence of defect.

Description

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00 The invention relates to non-destructive testing of materials and can be used in the ultrasonic testing of sheet and long products, for example rails. Known mirror-shadow method of ultrasonic flaw detection, which is widely used in the control of various industrial products with equidistant surfaces fj. The disadvantage of the mirror-shadow method is that in the process of moving the amp converter the bottom signal changes not only when a defect is detected, but also when the acoustic contact is disturbed. The closest to the invention according to the technical essence is the method of mirror-shadow ultrasonic testing of parts of an equal cross-section, which consists in that. Two ultrasonic waves are inserted into the product through a common entry point, moving from the entry point, and signals 2 are reflected from the opposite surface of the product. When using this method, defects are detected by the difference in the amplitudes of the voltages perceived by each of the frequency signals. 2 The disadvantage of this method is that the difference in the values of the amplitudes of the voltages perceived by each of the frequency channels depends not only on the presence of defects. .in a controlled object, but also from the presence of local inhomogeneities in one of the areas of the product. In addition, in the presence of a defect whose length exceeds the size of the object's sounding areas, 1 the difference in the amplitude values of the signals at the output of the frequency channels is the same as when the acoustic contact deteriorates, which can cause the defect to pass. The purpose of the invention is to increase the reliability of the control and noise immunity. This goal is achieved by that, according to the method of mirror-shade ultrasound monitoring, an item of equal cross section, consisting in that two ultrasonic waves are inserted into the product through a common insertion point, the insertion point is moved, and the signals reflected from the antipole surface of the product are recorded, , determine the ratio of the distances of the trajectory sections of the entry point, within which the amplitudes of the signals decrease below the onopHofo value, and by this relation a defect is judged. The drawing shows the envelopes of the amplitudes of the bottom, signals corresponding to each of the waves a - monitoring the defect-free product without interference; b - violation of the acoustic contact at the separation of the transducer; in - products in the presence of a defect. The method of mirror-shadow ultrasonic testing of parts of equal cross section is carried out as follows. The receiving paths of the piezotransducer are adjusted so that their sensitivity is different. In the process of defectoscopy: the point of entry of ultrasonic waves is moved along the surface of the controlled product and, in the absence of defects and acoustic contact disturbances, the amplitudes of these signals remain constant (cases). In the case of acoustic contact disturbance, the amplitudes of the bottom signals are monotonously reduced, and the lengths of sections within which the amplitudes of the bottom signals recorded by each transducer decrease are different (case B), which is associated with different sensitivity of the transducer receiving paths. When a defect is detected in the process of decoscopy with a given detection coefficient, the amplitudes of the bottom signals change almost synchronously and the lengths of the sections within which the amplitudes of these signals change are the same, since the point of the ultrasonic wave input for both the transducers are common and both waves overlap at the same time. In relation to the lengths of the sections of the amplitude reduction of the bottom signals for each, the transducer is judged by the presence of interference due to the disturbance of the acoustic contact or the presence of a defect. If this ratio is .. close to 1, then we are talking about the presence of a defect in. controlled product, if the ratio is significantly less than 1, then there is interference due to disturbance of the acoustic contact. For the implementation of the method, a transducer can be used, consisting of two piezoelectric plates, one of which is performed in the video ring and the second in the form of in its disc hole. The presses can be switched on both in combination and in a separate circuit. Thus, the method makes it possible to increase the reliability of the control and improve the noise immunity of the flaw detector to the interference caused by the change in the acoustic contact.

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Claims (1)

METHOD OF MIRROR-SHADOW ULTRASONIC DETAIL CONTROL OF EQUAL SECTION, consisting in the fact that two ultrasonic waves are introduced into the product through a common entry point, move the entry point and register? Signals reflected from the opposite surface of the product, characterized in that, in order to increase the reliability of control and noise immunity, the waves are input in one direction, the ratio of the lengths of the sections of the trajectory of the input point is determined, within which the signal amplitudes decrease below the reference value, and therefore the attitude of judging the presence of a defect. _β S