RU2055359C1 - Prismatic ultrasonic piezoelectric converter - Google Patents

Abstract

FIELD: nondestructive control of materials. SUBSTANCE: prismatic ultrasonic piezoelectric converter has piezoelement installed in prism, acoustic lines mounted on external surface of piezoelement at specified angle and cylindrical conical sound conductive extension pieces which number agrees with number of conic waveguides which have conical cavities in end face surfaces with dimensions corresponding to dimensions of conical waveguides. Material of extension pieces provides for propagation of transformed lateral waves in them. Extension pieces have specified length and diameter. EFFECT: enhanced productivity and authenticity of ultrasonic inspection. 2 dwg

Description

 The invention relates to non-destructive testing and can be used in ultrasonic inspection.

Known means for determining the sensitivity of control using artificial control reflectors [1]
The closest in technical essence to the proposed one is a prismatic ultrasonic piezoelectric transducer containing a piezoelectric element mounted on a prism [2]
Lateral cylindrical reflectors are located in a prism along the propagation path of longitudinal and transverse waves, which reflect during the control process into the transducer body, and the distances from the ultrasonic vibrations input point to the reflectors are chosen such that the test pulses from these reflectors are located at the beginning and end of the control zone.

 The disadvantages of this transducer include its limited use, associated with the size of the transducer prism. So, for the control zone, for example. 150 mm along the beam in a material with a speed of sound of 5000 m / s (metal) and a speed of sound in a prism of 2500 m / s (plexiglass, polystyrene) the length of the beam should be approximately 15 mm. This phenomenon is most pronounced when controlling thick-walled products in the first, second, etc. reflection from the lower and upper faces of the controlled object.

 With such a standardization, the reflector is the side surface of the cylinder with a given diameter, which also reduces the range of sensitivity changes under different control modes.

 Such a standardization method is not applicable for transducers with a variable input angle, since when the angle of inclination of the piezoelectric element in the prism changes, the ray paths mismatch at the interface with the direction to the cylindrical reflectors.

 The purpose of the invention is to increase the productivity and reliability of ultrasonic testing.

l_max=

V скорость звука в материале цилиндрической насадки;
t₁ и t₂ заранее определенное время появления импульса на экране соответственно от ближайшего и наиболее отдаленного от преобразователя дефекта, а наружные диаметры насадок соответствуют диаметрам эталонных отражателей.The essence of the invention lies in the fact that a prismatic ultrasonic piezoelectric transducer (ultrasonic probe) containing a piezoelectric element mounted on a prism is additionally equipped with conical sound-conducting waveguides mounted on the external end surface of the piezoelectric element at a given angle to it, and cylindrical removable sound-absorbing nozzles according to the number of conical waveguides in which conical cavities are made from the end surface, the dimensions of the conical cavities correspond to the dimensions of the conical of olnovodov, each of the nozzles in a conical cavity is interfaced with a waveguide, the material of the nozzles is selected from the condition of propagation of transverse waves transformed at the interface, the length of the nozzle is selected from the ratio
l _min ≅ L ≅ l _max . where l _min =

l _max =

V is the speed of sound in the material of the cylindrical nozzle;
t ₁ and t _{2 a} predetermined time of the appearance of the pulse on the screen, respectively, from the nearest and most distant from the transducer defect, and the outer diameters of the nozzles correspond to the diameters of the reference reflectors.

 Figure 1 shows the ultrasonic probe in the control process on the product; figure 2 test pulses on the screen of the flaw detector.

A prismatic ultrasonic probe contains a piezoelectric element 1, a prism 2, conical waveguides 3 and 4 (one cone waveguide shown), a cylindrical removable sound-absorbing nozzle 5 of length L _L and diameter D ₁ , cylindrical nozzles 6 of length L _t and diameter D ₂ (shown one at a time nozzle). Figure 1 shows the controlled product 7 and defects 8 and 9.

 In FIG. 2 shows the probe signal 10, the echo 5 'from the reflector, the echo 6' from the reflector, the echo 8 'from the defect 8, the echo 9' from the defect 9.

The lengths of nozzles 5 and 6 are chosen so that during the monitoring process the echoes 5'and 6 'are located at the edges of the automatic defect alarm (ASD) zone 1 for defect 8, the diameters D ₁ and D ₂ must correspond to the diameter corresponding to the minimum detected defect for zone ASD I, the length and diameter of unspecified nozzles for zone ASD II of defect 9 are indicated by test signals 11 and 12.

 Prismatic ultrasonic probe works as follows.

The converter is placed on the controlled product 7, and defects are searched. Find the minimum detected defect. Set with contact grease nozzles 5 and 6 of length L _L and L _t . Moreover, the diameters of the nozzles D ₁ and D ₂ correspond in reflectivity to reflection from the minimum detectable defect 8 in the near and far zones. By comparing the amplitudes of test signals and signals from defects on the screen of a flaw detector, the sizes of defects and the quality of the product are judged.

 If necessary, using additional nozzles form the corresponding control zone for the defect 9.

Claims (1)

A PRISMATIC ULTRASONIC PIEZOELECTRIC TRANSDUCER containing a piezoelectric element mounted on a prism, characterized in that, in order to increase the performance and reliability of ultrasonic control, it is equipped with conical sound-absorbing waveguides mounted on the outer end surface of the piezoelectric element and having a cylindrical absorption at a given angle the number of conical waveguides in which conical cavities are made from the end surface, the dimensions of the conical cavity correspond to the dimensions of tapered waveguides, each of the nozzles is associated with the conical cavity waveguide metarial nozzles is selected from the propagation conditions are transformed into the interface of transverse waves, and the length of the nozzle is selected from the relation
l _{m i n} ≅ L ≅ l _{m a x} ,
where l _{m i n} = vt _1/2 ,
l _{m a x} = vt _2/2,
where v is the speed of sound in the material of the cylindrical nozzle;
t ₁ and t ₂ - a predetermined time of appearance on the screen, respectively, of the closest and most remote defect from the transducer,
and the outer diameters of the nozzles correspond to the diameters of the reference reflectors.

Images