SU938121A1 - Device for modulation eddy current flow detection - Google Patents

Description

() DEVICE FOR MODULATING VIRTUAL DEFECTOSCOPY

I

The invention relates to non-destructive testing and can be used for the inspection of electrically conductive objects.

Devices for visual current modulation flaw detection are known, comprising a generator connected in series, an eddy current transducer, a compensator, an amplifier, an amplitude defector, a converter high frequency envelope analysis unit and an information presentation unit l and 2.

A disadvantage of the known devices is the insufficient reliability of the control, which is associated with a change in the envelope parameters of the high-frequency signal when the speed of movement of the control object relative to the converter varies.

The closest in technical essence is a device for modulating eddy-current flaw detection, containing a generator, a eddy-current transducer connected to it, a controlled envelope analysis unit of the high-frequency signal and a block representing + 1and information Bj.

However, this device does not have the necessary reliability of control, since the control unit of the analysis of the envelope of the high-frequency signal is carried out using a speed converter into an electrical signal, which requires mechanical contact with the object of control. This creates an additional correction warmer and is not always possible, for example, when monitoring objects that are interleaved through an eddy current transform. The device is vertically under the force of its own body.

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

The goal is achieved in that the device is equipped with a series-connected smoothing filter and a signal measurement unit 393 connected to the input of the controlled analysis unit and a compensator connected to the second input of the signal ratio measurement unit, and the converter is made of an excitation winding coaxially mounted relative to its one measuring winding, connected to the input of the compensator, and two differentially connected measuring windings, placed symmetrically flax exciting coil at a distance no more than half of its radius, are connected to the inputs of a smoothing filter and controllably analysis unit, the drawing presents t avlena block diagram of the proposed device. The device contains an alternating current generator 1, a differential type eddy current transducer 2 of a continuous type, consisting of exciting winding 3 connected to Generator 1, differentially connected two measuring windings 4 and 5i located symmetrically with respect to exciting winding 3 at a distance not exceeding half of its radius and measuring winding 6 coaxially installed with respect to exciting winding 3, controlled block 7 analyzing the envelope of the high-frequency signal, block 8 presenting information, smoothing The second filter 9, signal ratio measurement unit 10, compensation1-t Series high frequency signal envelope analysis unit 7 and information presentation unit 8 are connected to winding output 5; Smoothing filter 9 is connected to winding output and 5 and block 10 input. Winding 6 is connected through the compensator 11 to the unit 10 for measuring the ratio of the signals. The device works as follows. The generator 1 feeds the excitation winding 3 of the inductance of the converter 2. As a result, an alternating magnetic field is created that interacts with the control object 12 moving through the converter 2 at a speed V. The voltage induced on the measuring windings of the converter consists of vortex Ug and speed Up components . The velocity component arises due to the interaction of the 4 magnetic field of a magnetic exciting field with a moving object, which leads to the appearance of a secondary magnetic field Hjj oCVB}, where (7 is the electrical conductivity of the test object; V and B are the velocity vectors and magnetic induction The effect of HC on the exciting magnetic field can be interpreted as pulling the magnetic field in the direction of the magnetic field.This results in a differential EMF f on the external terminals of the differentially included measure The windings and 5. The velocity and vortex components equally depend on the geometry and electrophysical parameters of the object 12 of the control, the ratio of the speed BS and the vortex WB components EMF, where Eg is the EMF induced on the measuring winding 6, interacting with the monitored section depends only from the velocity V of the displacement of the object 12 of the control through the converter 2. The voltage from the differentially connected windings 4 and 5 after compensation of the imbalance by any known method enters the measuring channel of the flaw detector, consisting of a controlled envelope 7 for analyzing the spectrum of the envelope of the high-frequency signal of the converter, information representation block 8. At the same time, the voltage from the differentially connected windings C and 5 is fed through a smoothing filter 9 to the first input of the measurement unit 10 of the signal, the second input of which receives the voltage from the measuring winding 6, through the compensator 11, compensating for the no-load emf. The voltage at the output of the ratio measurement unit 10 depends only on the speed V, since the voltage pulses due to the presence of defects in the control object 12 are destroyed by the smoothing filter 9 A voltage proportional to the speed V is fed to the controlled input of the high-frequency envelope analyzer 7 Regulating its restructuring. Thus, the proposed device allows to reliably determine deL | ) ecty and evaluate their parameters when the speed variation in a wide range.

Claims (3)

1. USSR author's certificate No. 63765, cl. G 01 N 27/86, 1977., 2.Journal of Scientific Dnstniments, vol. 1965, IT 6, p. t06-09. 3. USSR author's certificate No. 605160, class, G 01 N 27/86, 1976 (prototype). l