RU2541672C1 - Ultrasound immersion multisection piezoelectric transducer - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: ultrasound immersion multisection piezoelectric transducer comprises hermetic package filled with damping substance, piezoelectric cells installed inside the package and placed symmetrically in regard to the converter acoustic axis and lens placed from the side of radiation surface of piezoelectric cells, acoustic axes of piezoelectric cells are intercrossed at the longitudinal axis of the converter, polarization vector of all piezoelectric cells is directed to the radiation side or to the damping substance side, at that lens is common for all piezoelectric cells or it consists of separate sections. Piezoelectric cells are placed so that they form convex or concave surface in regard to lens, all piezoelectric cells are made with positive and negative electrodes common for them, which cover gaps between piezoelectric cells filled with polymer compound and connected to sealed electric connector. Lens and damping substance with their surfaces are faced to the formed piezoelectric cells and polymer compound and each of them adjoins electrodes at these surfaces tightly; at that lens is glued to the electrode placed at piezoelectric cells or adjoins the electrode tightly through the layer of acoustically conductive fluid.

EFFECT: potential increase of the operating zone length and expansion of direction pattern for the piezoelectric transducer at simultaneous simplification of its design.

6 cl, 3 dwg

Description

The invention relates to ultrasonic measuring equipment, namely to piezoelectric transducers, and can be used for flaw detection and thickness measurement in the study of various kinds of materials, in particular pipes, rolled metal, plastics and heterogeneous materials, such as, for example, welded structures.

Known ultrasonic transducer containing a housing with a protector in the form of a truncated cone, a piezoelectric element and a damper placed in the housing (see application GB No. 2091520, CL G01N 29/00, 07/28/1982).

This transducer creates only a longitudinal wave in the material under study and can be used only in the high-frequency region, which narrows the scope of its use. In addition, wetting fluid is required to install the transducer on the test article.

Known separately-combined Converter, in the housing of which are installed at an angle of 45 degrees the transverse wave emitter and the receiving element (see patent FR No. 2499248, CL G01N 29/00, 08/06/1982).

This transducer operates in the high-frequency region and requires considerable effort to ensure good acoustic contact, which narrows the scope of its use.

In addition, a common disadvantage of the above converters is that they cannot work in immersion mode.

The closest to the invention in technical essence and the achieved result is an ultrasonic immersion multi-element piezoelectric transducer comprising a sealed housing with a damping substance, piezoelectric elements mounted inside the body and located in the body symmetrically with respect to the acoustic axis of the transducer, and a lens paired with piezoelectric elements from the side of the radiating surface of the piezoelectric element , the acoustic axis of the piezoelectric elements intersect each other on the longitudinal axis of the transform In the direction of radiation of the transducer, the polarization vector of all the piezoelectric elements is directed either towards the radiation or towards the damping substance, the lens being made common for all piezoelectric elements or consists of separate sections interconnected at the interface with a binder, for example, glue or a polymer compound ( see utility model patent RU No. 114,786, class G01N 29/00, 04/10/2012).

This converter is made with the possibility of its use for monitoring objects with a rough, unprepared and curved surface. However, this converter has a relatively complex design, which reduces its reliability and limits the range of possible configurations of the radiation pattern.

The problem to which the invention is directed, is to increase the reliability of the integrity control of the controlled material by increasing the length of the working area and expanding the radiation pattern of the piezoelectric transducer while simplifying the design of the transducer.

The technical result consists in the fact that an increase in the reliability of the integrity control of the controlled material is achieved.

, где δ - длина волны ультразвука в жидкости, прилегающие поверхности линзы и демпфирующего вещества повторяют поверхности электродов к которым они прилегают, а линейный размер излучающей поверхности каждого пьезоэлемента равен или меньше h=C/2F, где C - скорость звука в материале пьезоэлемента; F - резонансная частота пьезоэлемента.The problem is solved, and the technical result is achieved due to the fact that the ultrasonic immersion multi-element piezoelectric transducer contains a sealed housing with a damping substance, piezoelectric elements installed inside the body and located in the body symmetrically relative to the acoustic axis of the transducer, and a lens located on the side of the radiating surface of the piezoelectric elements, acoustic the axes of the piezoelectric elements intersect each other on the longitudinal axis of the transducer, the polarization vector of all the piezoelectric elements It is directed either toward the radiation or towards the damping substance, the lens being common for all piezoelectric elements or consisting of separate sections interconnected at the interface with a binder, for example, with adhesive or a polymer compound, the piezoelectric elements are arranged to form concave or convex relative to the lens surfaces, the gaps between the piezoelectric elements are filled with a polymer compound with the formation of smoothly curved surfaces common with the piezoelectric elements, one of which is facing well, the lenses, and the other toward the damping substance, all the piezoelectric elements are made with a common positive and negative electrodes, overlapping the gaps filled with the polymer compound between the piezoelectric elements and connected to the electrical sealed connector, while the lens and the damping substance are the surfaces facing the formed piezoelectric elements and polymer compound surfaces, each for its part, fits snugly to the electrodes located on these surfaces, and the lens is glued to zhennomu electrode for piezoelectric elements or adheres to the electrode through a layer of acoustically conductive liquid is less than the thickness $$\frac{\delta }{\mathrm{four}}$$

where δ is the wavelength of ultrasound in the liquid, the adjacent surfaces of the lens and damping substance repeat the surfaces of the electrodes to which they are adjacent, and the linear size of the radiating surface of each piezoelectric element is equal to or less than h = C / 2F, where C is the speed of sound in the material of the piezoelectric element; F is the resonant frequency of the piezoelectric element.

The piezoelectric elements preferably have the same shape with respect to the longitudinal axis of the transducer.

Piezoelectric elements with the side facing the controlled material can be located at an acute or obtuse angle to the acoustic axis of the piezoelectric transducer, respectively, in the case of the location of the piezoelectric elements with the formation of a concave or convex surface.

The lens, preferably made in the form of a layer of acoustically conductive solid material, has a thickness S opposite to each of the piezoelectric elements equal to

, $$\frac{\lambda }{\mathrm{four}}=\frac{c}{\mathrm{four}f}$$

,

where λ is the ultrasound wavelength in the lens material;

c is the speed of sound in the lens material;

f is the working frequency of the piezoelectric element.

.The lens may have a wedge-shaped shape opposite each piezoelectric element in the plane of the longitudinal section passing through the acoustic axes of the piezoelectric elements, and the thickness of the lens at the point where the acoustic axis of the piezoelectric element passes through it is $$\frac{\lambda }{\mathrm{four}}$$

.

The lens can be made with a cylindrical outer surface facing a concave part toward the material to be controlled and made opposite each of the piezoelectric elements, the generatrix of the cylindrical surface being perpendicular to the plane in which the acoustic axes of the piezoelectric elements lie, the lens has the smallest thickness equal to λ / 4, and the generatrix is cylindrical surface at the point of smallest thickness of the cylindrical surface intersects with the acoustic axis of the corresponding piezoelectric element with an increase in the thickness of the lens in away from this acoustic axis.

The implementation of the piezoelectric elements located with the formation of a concave or convex relative to the lens surface with gaps between the piezoelectric elements filled with a polymer compound with the formation of smoothly curved surfaces common with the piezoelectric elements, one of which faces the lens and the other towards the damping substance in combination with the fact that all piezoelectric elements are made with a common positive and negative electrodes overlapping the gaps between the piezoelectric elements filled with a polymer compound and connected to the electrical sealed connector, wherein the lens and the damping substance are the surfaces facing the surfaces formed by the piezoelectric elements and the polymer compound, each, for its part, is closely adjacent to the electrodes located on these surfaces, and the adjacent surfaces of the lens and damping substance repeat the surfaces of the electrodes to which they are adjacent, and the linear size of the radiating surface of each piezoelectric element is equal to or less than h = C / 2F, where C is the speed of sound in the material of the piezoelectric element; F is the resonant frequency of the piezoelectric element, which makes it possible to simplify the design of the transducer due to the possibility of performing the piezoelectric elements arranged with the electrodes in the form of a separate unit, which can be easily inserted into the transducer during assembly or easily replaced if necessary, for example, during repair. Thus, the transducer can consist of separate structurally simple elements: a block of piezoelectric elements, a lens and a damping substance, from which the transducer of almost any necessary configuration is easily assembled. In addition, it is possible to create blocks of piezoelectric elements with a surface facing the lens, which can be two-dimensional, for example close to cylindrical, or three-dimensional, for example close to spherical, which in turn allows you to create transducers with almost any desired length of the working zone of the piezoelectric transducer, which allows to increase the reliability of the integrity control of the controlled material

позволяет добиться максимальной чувствительности пьезоэлектрического преобразователя за счет эффекта просветления.Making the lens thickness equal $$\frac{\lambda }{\mathrm{four}}$$

allows you to achieve maximum sensitivity of the piezoelectric transducer due to the effect of enlightenment.

The implementation of the lens with the above wedge-shaped surfaces can reduce the duration of the echo pulse and increase the signal-to-noise ratio.

The implementation of the lens with cylindrical surfaces allows, in addition to the above qualities, to ensure the concentration of energy of the acoustic field in a given area.

Figure 1 shows a longitudinal section of an ultrasonic immersion multi-element piezoelectric transducer with two piezoelectric elements and a lens with cylindrical surfaces.

Figure 2 presents a longitudinal section of an ultrasonic immersion multielement piezoelectric transducer with piezoelectric elements and a wedge-shaped lens opposite each piezoelectric element.

Figure 3 shows a longitudinal section of an ultrasonic immersion multielement piezoelectric transducer with a convex surface formed by the piezoelectric elements facing the controlled material.

An ultrasonic immersion multielement piezoelectric transducer comprises a sealed housing 1 with a damping substance 2, piezoelectric elements 3 installed inside the housing 1 and located in the housing 1 symmetrically with respect to the acoustic axis 4 of the transducer, and a lens 5 located on the side of the radiating surface of the piezoelectric elements 3.

Piezoelectric elements 3 can be made in the form of round, segment or rectangular plates and are located on the side facing the controlled material at an acute α or obtuse β angle to the acoustic axis 4 of the piezoelectric transducer, respectively, in the case of the location of the piezoelectric elements 3 with the formation of a concave or convex surface, while the piezoelectric elements 3, preferably, have a pairwise identical shape with respect to the longitudinal axis (coinciding with the acoustic axis 4) of the transducer and are made with electrodes 6 and 7 on their opposite surfaces connected to an electrical sealed connector 8. The acoustic axis 9 of the piezoelectric elements 3 intersect each other on the longitudinal axis of the transducer.

The polarization vector of all piezoelectric elements 3 is directed either to the side of radiation or to the side of the damping substance 2, moreover, the lens 5 is made common to all piezoelectric elements 3 or consists of separate sections 10 connected to each other at the interface with a binder, for example, with glue or a polymer compound.

The piezoelectric elements 3 are arranged with the formation of a concave (figure 1 and 2) or convex (figure 3) relative to the lens 5 of the surface. The gaps between the piezoelectric elements 3 are filled with a polymer compound 11 with the formation of smoothly curved surfaces common with the piezoelectric elements 3, one of which faces the lens 5 and the other toward the damping substance 2.

, где δ - длина волны ультразвука в жидкости, прилегающие поверхности линзы 5 и демпфирующего вещества 2 повторяют поверхности электродов 6 и 7, к которым они прилегают, а линейный размер излучающей поверхности каждого пьезоэлемента 3 равен или меньше h=C/2F, где C - скорость звука в материале пьезоэлемента 3; F - резонансная частота пьезоэлемента 3.All piezoelectric elements 3 are made with a common positive 7 and negative 6 electrodes, overlapping the gaps filled with the polymer compound 11 between the piezoelectric elements 3 and connected to the electrical sealed connector 8, while the lens 5 and the damping substance 2 surfaces facing the formed piezoelectric elements 3 and the polymer compound 11 surfaces, each for its part, fits snugly to the electrodes 6 and 7 located on these surfaces, and the lens 5 is glued to the electrodes located on the piezoelectric elements 3 at 7 or adheres to the electrode 7 through a layer of acoustically conductive fluid (not shown) with a thickness less than $$\frac{\delta }{\mathrm{four}}$$

where δ is the wavelength of ultrasound in the liquid, the adjacent surfaces of the lens 5 and damping substance 2 repeat the surfaces of the electrodes 6 and 7 to which they are adjacent, and the linear size of the radiating surface of each piezoelectric element 3 is equal to or less than h = C / 2F, where C is the speed of sound in the material of the piezoelectric element 3; F is the resonant frequency of the piezoelectric element 3.

Lens 5, preferably made in the form of a layer of acoustically conductive solid material, has a thickness S opposite each of the piezoelectric elements (not shown), equal

, $$\frac{\lambda }{\mathrm{four}}=\frac{c}{\mathrm{four}f}$$

,

where λ is the ultrasound wavelength in the lens material;

c is the speed of sound in the lens material;

f is the working frequency of the piezoelectric element.

.The lens 5 may have a wedge-shaped shape opposite each piezoelectric element 3 in the longitudinal section plane passing through the acoustic axes 9 of the piezoelectric elements, and the thickness of the lens at the point where the acoustic axis 9 of the piezoelectric element passes through it is $$\frac{\lambda }{\mathrm{four}}$$

.

Lens 5 can be made with a cylindrical outer surface facing a concave part toward the material to be controlled and made opposite each of the piezoelectric elements 3 (Fig. 1), and the generatrix of the cylindrical surface is perpendicular to the plane in which the acoustic axes 9 of the piezoelectric elements lie, lens 5 has the smallest thickness equal to λ / 4, and the generatrix of the cylindrical surface at the point of smallest thickness of the cylindrical surface intersects with the acoustic axis 9 of the corresponding piezoelectric element with increasing thickness lenses away from this acoustic axis 9.

Ultrasonic immersion multi-element piezoelectric transducer operates as follows.

After the transducer is installed in the liquid with a lens 5 above the surface of the controlled material, exciting voltage is applied to the terminals of the electrical tight connector 8 or, in the case of receiving ultrasonic vibrations, the received signal is removed from these conclusions. In the radiation mode, due to the connection of the electrodes of the piezoelectric elements 3 to the corresponding output of the connector 8, the piezoelectric elements 3 oscillate in phase, emitting longitudinal waves into the liquid. The wave front reaches the surface of the controlled object and, depending on the angle of incidence, forms the front of longitudinal or transverse waves in it. When this front meets a material inhomogeneity or defect, a reflected echo pulse is formed.

In the receiving mode, the reflected waves are received by all of the piezoelectric elements 3 or part thereof and form an output electrical signal at the terminals of the connector 8.

Placing the piezoelectric elements 3 in the manner described above in combination with performing them in pairs with the same shape allows you to increase the length of the working zone of the piezoelectric transducer and expand its radiation pattern, which ultimately allows to increase the reliability of the integrity control of the controlled material.

The immersion type of contact of the converter with the controlled object makes it possible to control materials with a rough surface (for example, castings) and long products, as well as to increase the life of the converter.

The ability to concentrate the energy of the acoustic field in a predetermined working area provides increased reliability of control in bulk products.

The expansion of the radiation pattern provides the ability to detect randomly oriented defects.

The present invention can be used for flaw detection and thickness measurement of the material of structures in mechanical engineering, pipeline and railway transport.

Claims (6)

1. An ultrasonic immersion multielement piezoelectric transducer comprising a sealed housing with a damping substance, piezoelectric elements mounted inside the body and located symmetrically relative to the acoustic axis of the transducer, and a lens located on the side of the radiating surface of the piezoelectric elements, the acoustic axis of the piezoelectric elements intersect each other on the longitudinal axis of the transducer , the polarization vector of all piezoelectric elements is directed either to the side of radiation or to the side of damped its substances, moreover, the lens is made common to all piezoelectric elements or consists of separate sections interconnected at the interface with a binder, for example glue or a polymer compound, characterized in that the piezoelectric elements are arranged to form a concave or convex surface relative to the lens, the gaps between the piezoelectric elements are filled polymer compound with the formation of smoothly curved surfaces common with piezoelectric elements, one of which faces the lens and the other towards the damping surface In addition, all piezoelectric elements are made with a common positive and negative electrodes, overlapping the gaps filled by the polymer compound between the piezoelectric elements and connected to the electrical sealed connector, the lens and the damping substance being facing the surfaces formed by the piezoelectric elements and the polymer compound, each on its own side fits tightly to the electrodes located on these surfaces, the lens being glued to the electrode located on the piezoelectric elements or flat adheres closely to the electrode through a layer of acoustically conductive liquid with a thickness of less than $$\frac{\delta }{\mathrm{four}}$$

where δ is the wavelength of ultrasound in the liquid, the adjacent surfaces of the lens and damping substance repeat the surfaces of the electrodes to which they are adjacent, and the linear size of the radiating surface of each piezoelectric element is equal to or less than h = C / 2F, where
C is the speed of sound in the material of the piezoelectric element;
F is the resonant frequency of the piezoelectric element. 2. The transducer according to claim 1, characterized in that the piezoelectric elements have the same shape in pairs with respect to the longitudinal axis of the transducer. 3. The transducer according to claim 1, characterized in that the piezoelectric elements with the side facing the controlled material are located at an acute or obtuse angle to the acoustic axis of the piezoelectric transducer, respectively, in the case of the location of the piezoelectric elements with the formation of a concave or convex surface. 4. The Converter according to claim 1, characterized in that the lens, made in the form of a layer of acoustically conductive solid material, has a thickness S opposite each of the piezoelectric elements equal to
$$\frac{\lambda }{\mathrm{four}}=\frac{c}{\mathrm{four}f}$$

,
where λ is the ultrasound wavelength in the lens material;
c is the speed of sound in the lens material;
f is the working frequency of the piezoelectric element. 5. The Converter according to claim 1, characterized in that the lens has a wedge-shaped shape in the plane of a longitudinal section passing through the acoustic axis of the piezoelectric elements, and the thickness of the lens at the point where the acoustic axis of the piezoelectric element passes through it is $$\frac{\lambda }{\mathrm{four}}$$

. 6. The transducer according to claim 1, characterized in that the lens is made with a cylindrical outer surface facing the concave part towards the material being controlled and made opposite each of the piezoelectric elements, the generatrix of the cylindrical surface being perpendicular to the plane in which the acoustic axes of the piezoelectric elements lie, the lens has the smallest a thickness equal to λ / 4, and the generatrix of the cylindrical surface at the point of smallest thickness of the lens with the cylindrical surface intersects with the acoustic axis of the corresponding ezoelementa with increasing thickness of the lens in the direction of this acoustic axis.

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