SU1569696A1 - Transducer for ultrasonic inspection - Google Patents

Abstract

This invention relates to acoustic methods of non-destructive testing. The aim of the invention is to expand the field of application due to the possibility of controlling thinner products by using transverse ultrasonic vibrations to control the quality of acoustic contact, using a transducer in determining the shape of defects due to the simultaneous emission of various types of vibrations from several angles into the product. The piezoplate 3, inclined at an angle α to the working surface 2 of the prism 1, radiates in one direction the ultrasonic oscillation pulses used for flaw detection of the product 7, and the other, reflected to the reflector 6, ultrasonic vibrations used to obtain additional information. On the reflector 6, the angle of inclination γ to the surface 2 is selected based on the angle α and the ratio of the propagation speeds of ultrasonic longitudinal and transverse oscillations in the material of the prism 1, the radiated ultrasonic vibrations are transformed into transverse, falling perpendicular to surface 2. These transverse ultrasonic vibrations are used, for example, to determine the quality of the acoustic contact or the thickness of the product 7. 1 sludge.

Description

The invention relates to acoustic methods of non-destructive testing and can be used for ultrasonic (US) testing of elements, in particular products with plane-parallel surfaces,

The aim of the invention is to expand the scope of application by allowing the control of products of smaller thickness and the use of a converter in determining the shape of defects.

The drawing shows schematically a transducer for ultrasound control.

The transducer for ultrasound control contains a prism 1 with a working surface 2, a piezoplate 3 with two radiating planes 4 and 5 and a reflector 6 made, for example, in the form of a prism face. Position 7 in the drawing indicates a test article with a bottom surface 8. Piezoplast 3 is installed in prism 1 at an angle oi to its working surface 2 so that its one plane 4 faces the working surface 2 of prism 1, and the other radiating plane 5 - to the reflector 6. The reflector 6 is installed in the prism 1 at an angle y to its working surface 2, which is chosen from the condition / ce / ct) + cosoi

J arcctg | (

where se and ct

ainoi

- propagation speeds of longitudinal and transverse ultrasonic vibrations in the material of prism 1, respectively,

The acoustic axis of the piezoplate 3 in the direction opposite to the working surface 2 of the prism 1 intersects the plane of the reflector 6. The transducer for ultrasonic control works as follows.

A prism 1 is installed with a working surface 2 on the tested product 7. Acoustic contact of prism 1 with product 7 is provided, for example, with the help of a contact liquid applied to the product 7. The piezo plate 3 is excited with an electric signal. The plane 4 of the piezoplates 3 radiates longitudinal vibrations which, spreading in the material of the prism 1, fall on its working surface 2 at an angle about, refract at the interface the material of the prism 1 - the material of the product 7 and propagate in the product 7 at an angle (b, about

Q 5 Q

five

Q

Q bake the optimal detection of defects. Upon contact with a defect (not shown), the ultrasonic vibrations in the same way return to piezoplate 3 and register with it. These vibrations carry information about the flawiness of the product 7. At the same time, the flatness / part 5 of the piezoplate 3 radiates longitudinal ultrasonic vibrations, which, propagating in the material of the prism 1, fall on the reflector 6 at an angle and under reflection transform into longitudinal ultrasonic vibrations. (reflection at an angle of 8) and transverse ultrasonic vibrations (reflection at an angle of Ј).

Due to the choice of angle, the transverse ultrasonic vibrations fall onto the surface 2 of the prism 1 perpendicularly, are reflected from the interface of the prism material 1 - the material of the test article 7, pass into the article 7 and are reflected from its bottom surface 8. The reflected ultrasonic vibrations return to the piezo plate 3 and register with her help. The amplitude of these reflected oscillations carries information about the quality of the acoustic contact of the prism 1 with the product 7, and the time interval between the oscillations reflected by the surface 2 of the prism 1 and the surface 8 of the product 7, carries information about the thickness of the product 7. When making the prism 1 of plexiglass (p 2670 m / s, s. J300 m / s) and the installation of the piezoelectric element 3 at an angle of about 38 the angle V of the installation of the reflector is chosen to be

2 ° 17.

i

Longitudinal ultrasonic vibrations, reflected at an angle of 5, fall on the working surface 2 of the prism 1 at an angle of Ј oi -2Х1. For plexiglass L, 13 ° 2b. These vibrations are then transformed and refracted at the interface of the prism material 1 - the material of the product 7 and propagated in the product 7 in the form of longitudinal and transverse oscillations at an angle J and S, respectively, whose values are determined from

ev,

se

 EGS81P

sin (ct -2) 1

GGH1

 srcsin - sin (ot - 2jf) kj

where Cg and

GJ - propagation rates of longitudinal and transverse

Ultrasonic vibrations in the material of product 7, respectively. These vibrations propagate in product 7 in a direction opposite to the direction in which oscillations propagate at an angle of 5. In the event that a defect is detected by the plane 4 of the piezoplate 3 oscillated, the transducer expands and voices the detected defect by oscillations propagating at angles J and. Using the amplitude of received oscillations, the shape of the detected defect is estimated.

The use of transverse oscillations introduced normally into the monitored product allows, with small dimensions of the converter, to avoid merging on the screen of the electron-beam indicator of the probing signal and the signal reflected by the working surface of the prism. The use of transverse vibrations also avoids the fusion of signals reflected by the working surface of the prism and the bottom surface of the product, i.e. to conduct ultrasonic control of thin products with simultaneous quality control of acoustic contact.

five

ten

15

20

Claims (1)

Invention Formula A transducer for ultrasonic testing, containing a prism with a working surface, a piezoplate installed in the prism at an angle to its working surface, and a reflector mounted in the prism at an angle Y to its working surface so that the acoustic axis of the piezoplate in the direction opposite to the working surface of the prism, passed through the center of the reflector, about t Vt due to the fact that in order to expand the scope of application, the prism is made of solid sound-conducting material, and the angle θ of the reflector to the working is selected from the prism surface conditions U arcctg (cg / ct) + coagL sinoL 25 gdesr and with - propagation speeds of longitudinal and transverse oscillations in the prism material, respectively.