SU932386A1 - Electromagnetic modulation flaw detection method - Google Patents

Description

(5) METHOD OF ELECTROMAGNETIC MODULATING DEFECTOSCOPY

The invention relates to non-destructive electromagnetic control and can be used in instrument-making and machine-building industries for detecting defects, determining the electrophysical parameters of controlled products and recognizing objects of complex geometric shape. The method of electromagnetic non-destructive testing is known, consisting of sensitive elements distributed in space, for example eddy current inductance coils with alternating current Frequency {l The disadvantage of this method is that the scanning electromagnetic field is obtained only at sufficiently high frequencies of the supply current necessary to obtain high waves. This reduces the accuracy of the control, since the formation of several antinodes and nodes is possible the waves are small. The closest to the proposed technical essence is a method of electromagnetic modulation defectoscopy, which implies that the sensitive elements of the eddy current transducer are installed along the control zone, according to the scanning scheme, resonant modes are created sequentially for the corresponding sensitive elements of the eddy current transducer and about the parameters of the controlled object t2. However, this method does not have sufficient reliability of control, since it does not allow creating scanning electromagnetic fields at a constant frequency and a constant maximum intensity, which leads to a change in the sensitivity of the control during the scanning process.

The purpose of the invention is to increase the reliability of the control.

This goal is achieved by the fact that the resonant mode for the corresponding sensitive elements of the eddy current transducer is created by changing the natural resonant frequency and the quality factor of the latter.

The drawing is a control diagram explaining the method.

The circuit contains a series-connected alternator 1 AC, eddy current transducer

2c distributed in space sensitive elements 3 and block

4 processing information, control unit 5, connected to the control inputs of the sensitive elements 3 "Sensitive elements 3 of the eddy current transducer, it is advisable to perform in the form of inductors included in an oscillating circuit with a tunable capacitance, for example, using varicaps.

The method is implemented as follows.

The sensing elements 3 of the eddy current transducer are installed along the control zone and feed the eddy current transducer 2 from the alternating current generator 1. According to the scanning pattern, control unit 5 creates successively resonant modes for the corresponding sensitive elements

The 3-current converter by changing their resonant frequency and quality factor, which leads to a sequential displacement of the maximum of the electromagnetic interaction with the corresponding section of the object being monitored and with a continuous change of the control signal from the output of the control unit 5 to scanning the controlled section. The signals produced by the eddy current transducer 2 are fed to the information processing unit and converted

in the values corresponding to the controlled parameters of the object.

Changing the natural frequency and quality factor of the sensitive elements of eddy current transducers can be done by changing the parameters of the oscillatory circuits in which they are included, for example, when using variable capacitances and variable resistances. In this case, both excitation and measuring inductance coils can be included in the circuit.

The ability to create a scanning electromagnetic field in the specified

directions with fixed sensing elements of the eddy current transducer with constant frequency and constant value of the maximum intensity of the scanning field allows to increase the reliability of control.

Invention formula

A method of electromagnetic modulation flaw detection, which consists in the following

sensing elements of the eddy current transducer are installed; according to the scanning scheme, consistently resonant modes are created for the corresponding sensitive

Elements of the eddy current transducer and pb of the set of signals of the latter judge the parameters of the controlled object, characterized in that, in order to increase the reliability of control, the resonant mode for the corresponding sensitive elements of the eddy current transducer is created by changing the natural resonant frequency and the quality of the latter.

Sources of information taken into account in the examination

1. USSR author's certificate No. 360603, cl. G 01 N 27/86, 1972.

2. USSR author's certificate for application number 2891530/28,

cl. G 01 N 27/90, 1980 (prototype).

Claims (1)

Claim The method of electromagnetic modulation defectoscopy, which consists in installing sensitive elements of the eddy current transducer along the control zone, according to the scanning scheme, creating resonant modes for the corresponding sensitive Elements of the eddy current transducer and judging by the totality of the signals of the latter about the parameters of the object being monitored *, characterized in that , in order to increase the reliability of control, the resonance mode for the corresponding sensitive elements of the eddy currents The second converter is created by changing the natural resonant frequency and the quality factor of the latter.