RU1803854C - Electromagnetoacoustic transducer for receiving ultrasonic oscillations - Google Patents

Abstract

The invention relates to measuring and control equipment and can be used for non-destructive testing of the physicochemical properties of products. The purpose of the invention, improving accuracy, is achieved due to the fact that in the electromagnetic-acoustic transducer for receiving ultrasonic vibrations containing a permanent bar magnet, a damping pad and a housing located in the housing, the end face of the magnet is made with an electrically conductive coating, the cavity of the housing is a microwave volumetric -resonator, and the transducer is equipped with two waveguides, respectively fixed by the input and output on the side walls of the housing. 1 silt, WITH

Description

The invention relates to a means of measuring and measuring equipment and can be used for non-destructive testing of physical and chemical properties of products.

The aim of the invention is to increase accuracy.

To achieve this goal, an electromagnetic-acoustic transducer for receiving ultrasonic vibrations, comprising a hollow body and a permanent permanent magnet installed in one of the walls of the body by means of a damping pad, the end face of which is designed to be mounted on the controlled object, is equipped with two waveguides, respectively fixed with an input and an output on the side walls of the housing, the end face of the magnet located in the housing is electrically conductive

the coating, and the body cavity is made in the form of a volumetric microwave resonator.

The use of a volume microwave resonator, whose natural frequency changes with the movement of a permanent bar magnet and is an informative parameter of the electric signal, can significantly improve the accuracy of measurements. This is due to the fact that, firstly, small displacements (of the order of 106) of the magnet end cause significant changes (ten kilohertz) of the natural frequency of the resonator, and secondly, modern electronically counted frequency meters make it possible to measure the frequency with an absolute error of the order of hundreds Hertz, which allows one to obtain a relative measurement error in the range of 0.001%, and, thirdly, standard (reference) equipment for howling

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product of the frequency has a relative standard deviation of 10, which provides high metrological characteristics of the measuring instruments.

The drawing shows an electromagnetic-acoustic transducer for receiving ultrasonic vibrations, sectional view.

The electromagnetic-acoustic transducer for receiving ultrasonic vibrations contains a permanent bar magnet 1, a damping pad 2, a cylindrical hollow body 3, an electrically conductive coating 4 at the end of the magnet 1, a radial-coaxial inductor 5 in the cylindrical body 3, waveguides 6 and 7 for energy transfer the electromagnetic field from the microwave generator (not shown in the drawing) and to the measuring unit (not shown in the drawing), respectively, through input 8 and output 9 on the side walls of the housing 3, 10 — controlled object, 11 — resonance or - cavity of a volume microwave resonator.

The device operates as follows.

The transducer is mounted with the outer end of magnet 1 on the surface of the object being monitored 10. Due to the attractive force of the magnet, the transducer is held on the object and provides reliable mechanical contact. The second end face of magnet 1 with a highly conductive coating 4 together with a cylindrical body 3 form a cavity 11 of a volume microwave resonator. From the microwave generator through the waveguide 6 h through the input 8 in the cavity 11, electromagnetic waves of HOIP type (P 1,2, ...) are excited, the natural frequency of which is determined by the diameter and length of the cavity 11.

When ultrasonic vibrations occur in the controlled object 10, metal particles both inside the object 10 and on its surface begin to move with

frequency of exciting oscillations. The permanent magnet 1 mounted on the surface of the object 10 also begins to oscillate, and the housing 3, in which is fixed

on the damping pad 2, the permanent magnet 1 remains stationary. The damping pad 2 allows the magnet 1 and its end face with a highly conductive coating 4 to oscillate along the axis of the housing 3,

remaining stationary relative to the object 10. Thus, the length of the cavity 11, and therefore the natural frequency of the oscillations of the electromagnetic field in the cavity resonator, which through

the output 9 and the waveguide 7 are fed to the measuring unit, transmitting information about ultrasonic vibrations in the object 10. Although the excitation of HOIP-type vibrations in the cavity 11 does not require an electric

contact between the side walls of the permanent magnet 1 and the housing 3, since in the highly conductive coating 4 there are only ring currents, in order to provide a higher quality factor of the resonator

Claims (1)

and measurement accuracy, a radial-coaxial inductor 5 is made in the housing 3. Claims The invention is an electromagnetic-acoustic transducer for receiving ultrasonic vibrations, comprising a hollow housing and a permanent permanent magnet mounted in one of the walls of the housing by means of a damping gasket, the end of which is located on the outside designed to be mounted on a monitored object, characterized in that, in order to improve accuracy, it is equipped with two waveguides fixed respectively to the input and output on the side walls of the housing, the end face of the magnet in the housing has an electrically conductive coating, and the housing cavity is made in the form of a volumetric microwave - resonator.