RU1795368C - Acoustic transducer - Google Patents

Abstract

The invention relates to acoustic non-destructive testing methods. The aim of the invention is to increase the noise immunity due to electrical circuits of radiation and reception. The disk piezoelectric element of the transducer is brought into acoustic contact with a controlled object, such as a non-metallic plain bearing shell. Electrical pulses are applied to the input of the transducer connected to the electrodes of the piezoelectric element, which excite the oscillations of the latter. These vibrations propagate into the object, are reflected in it and return. When receiving vibrations, not only the piezoelectric element oscillates, but also the magnetostrictive material covering it (with the exception of the contact end face), as a result of which an electric signal is induced in the coaxially located piezoelectric element and is fed to the output. Using the received signals, the time of propagation of acoustic vibrations in the object is measured, the speed of their propagation is determined and the modulus of normal elasticity of the material of the object is calculated. 1 ill.

Description

The present invention relates to acoustic transducers and is intended for pulsed sounding in a material of sliding bearings.

Devices for determining the elastic characteristics of a part are known, comprising an ultrasonic generator, a quartz piezocrystal coupled through an amplifier to an electronic oscilloscope. The disadvantage of these devices is the high noise level,

The closest of the considered analogues to the present invention is an acoustic transducer containing a disk piezoelectric element and an electric coil coaxially located thereto.

 : The disadvantage of this acoustic transducer. is a high noise level,

The aim of the invention is to increase the noise immunity of acoustic transducers.

The goal is achieved by coating with the exception of the contact end face by a magnetostrictive material and by connecting the input of the acoustic transducer to the piezoelectric electrodes, and the output to the leads of the coil.

The drawing shows an acoustic transducer and a slipper in a longitudinal section.

The proposed transducer consists of a piezoelectric element 1, covered with the exception of the lower end, by magnetostrictive material 2, the input of the transducer 3 is connected to the electrodes

AND

with

about

09

piezoelectric element 1, and the output with the conclusions of the coil 4.

The invention is illustrated by the following example. To determine the modulus of normal elasticity, the sensor housing 5 is screwed into the bearing housing 6 until the material of the liner 7 is contacted. The electrical pulses are set by the electric pulse setting unit 8 of the transducer 3 when the power supply from the battery 4 to the piezoelectric element 1. During deformation, the piezoelectric element 1 distributes longitudinal in the liner material 7 longitudinal mechanical vibrations with the frequency and amplitude of electrical pulses.

The measurement of the time t of the propagation of ultrasonic vibrations is carried out by a magnetostrictive material 2 with a change in its magnetic properties and by a coil 4. Reception of electrical pulses is carried out with a magnetostrictive material 2

and coils 4 by the excitation signal generating unit 9 to the digital indication indicating unit 10. The normal elastic modulus E is determined by the formula:

E; .. S. -p (+ Y) (1 -2V)

t2- (1-v)

where S is the thickness of the liner; p is the density of the material; V is the Poisson's ratio.

The technical and economic efficiency of the present invention consists in the fact that, as a result of the new principle and its implementation into the design, it is possible to determine the normal elastic modulus of the sliding bearing. The use of a sensor of normal elastic modulus will significantly reduce the noise level, which will increase the sensitivity of receiving ultrasonic vibrations by 4-7 times.

Claims (1)

The claims An acoustic transducer comprising a disk piezoelectric element and a coaxially arranged electric coil, characterized in that, for the purpose of to increase the noise immunity, the piezoelectric element with the exception of the contact end is covered with magnetostrictive material, the inlet of the converter is connected to the electrodes of the piezoelectric element, and the output is connected to the terminals of the coil.