SU1415166A1 - Superimposed eddy-current converter with rotary field - Google Patents

Abstract

The invention relates to non-destructive testing and can be used for the inspection of electrically conductive objects. Improving the reliability of control is achieved by increasing the stability of the voltage unbalance. Excitation coils placed on the annular magnetic core 1 create a rotating magnetic field. The reaction of the excited eddy currents is measured by the first measuring coil, consisting of sections 7.8. The resulting voltage is summed vectorially with the voltage of the second measuring coil, consisting of sections 10,11 and placed on the second end of the ring frame. 2 hp f-ly, 3 ill. c (L 4 SP Od Od

Description

The invention relates to non-destructive testing and Al quality control of flat electrically conductive products can be used.

The aim of the invention is to increase the reliability of the control, achieved by increasing the stability of the voltage unbalance.

FIG. 1 shows the construction of an overhead eddy current transducer with an impinged field; in fig. 2 - the same, top view; in fig. 3 is a circuit for turning on its b-winding.

i An in-line eddy current transducer with a floating field consists of an annular frame 1 with sections of 2-5 excitation coils arranged on it, 90 ° displaced relative to each other, the coils of each of sections 2-5 lie in planes I passing through the axis of the annular frame 1. The diametrically opposite sections 2,3 | and 4,5 are connected in series to each other. I The transducer also contains a ferrule 6, the IB grooves of which are arranged in sections 7 and 8 of the first measuring coil, and the ferrule 9 with the sections 10 and 11 I of the second measuring coil located in its grooves. The first and second pick-up coils are located; on the first and second ends of the ring; frame 1, respectively. Sections 7.8 and 11.12; The measuring coils are made identical and are shifted relative to the sections of the excitation coil by an angle of 45 °. When this is opposite to the annular frame 1 section 7, 8 and 10, 11 of the measuring coils are connected in series counter.

The yoke 9, on which sections 10 and 11 of the measuring rod are laid in the grooves, is installed symmetrically with the yoke 6 relative to the excitation coils.

In addition, sections 7, 10 and 8, 11, connected in series with each other, are located at an angle of 13 with respect to the centers of the respective pairs of sections of the excitation winding.

The Converter operates as follows.

The excitation coil, wound on the ring frame 1, is made of four sections shifted by 90 ° one relative to the other 2-5, the turns of which cover the ring frame, while the opposite sections are interconnected in pairs, and the resulting pairs of sections are sealed by voltages of the same frequency and amplitude with a phase shift of 90 ° from the generator, (not shown), resulting in a rotating magnetic field in space, the tangential component of the magnetic induction vector of which has the same amplitude at any point of the zone of action the field is perpendicular to the plane of the object of control. The rotation speed of the magnetic field is

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the frequency of the supplied voltage, and the plane of rotation is parallel to the plane of the control object.

The resulting magnetic flux obtained in the control zone with the presence of the control object 12 can be considered as the sum of the excitation flux formed by the currents of the sections of the exciter and the eddy current flux induced by the excitation flux in the product. The eddy currents of the product depend not only on the excitation flow, but also on the electrophysical properties of the controlled product. The change in the transducer's magnetic flux, caused by a change in the electrophysical properties of the product at a constant excitation flow, is equivalent to a change in the emf of sections 7.8 of the first measuring coil, by changing the magnitude of which you can judge the change in the parameters of the control object.

Since sections 7, 10 and 8, 11 of the first and second measuring coils are identical in design, are located on identical frames and are placed in the same rotating uniform magnetic field, when the magnitude of the exciting field is changed, their total signal does not change and remains minimal ( equal to zero), since the sections with each other are included in pairs in opposite directions (Fig. 3). This increases the stability of the voltage unbalance with the instability of the exciting floor.

Since sections 7.8 of the first measuring coil are identical in design, are wound on a common frame, the density of turns of one of them coincides with the plane of turns of the other, and is made in the form of elongated loops orthogonal to one another (Fig. 1 and 2), the area on the surface of the test article associated with each section is common to these windings.

To ensure the same sensitivity of each section of the first measuring coil to the parameters of the product and to its displacements, each section is wound alternately through a coil.

The emf of pairs of sections 7, 10, and 8.11, placed in a rotating stable and uniform magnetic field, are equal if there is a defect-free area of the control object 12 in the control area and are not equal, ei 1 and a control area is located in the control area. The difference between the voltages supplied to the signal processing unit (not shown) determined by the size of the defect is detected by the electronic circuit of the flaw detector.

To increase the voltage stability of the imbalance between pairs of oppositely included sections 7, 10 and 8, 11 and to maintain the same sensitivity of the converter to defects of any orientation when the output voltages of the generator (not shown) are unstable, these sections are at an angle of 13 relative to the centers of the corresponding pairwise switched sections of the excitation winding (Fig. 2).

Since the EMF in a pair of sections 7,10 is determined by the total magnetic induction sector created by two mutually perpendicular pairs of sections 2.3 and 4.5 (Figs. 1 and 2), the EMF in a pair of sections 8.11 is also determined by the total magnetic induction vector, and the pairs of sections 2.3 and 4.5 of the excitation coil are located so that the angle between the axes of symmetry of the pairs of sections of the excitation coil and sections of the measuring coils is the same, then when the amplitude of any component of the magnetic induction vector is changed the pairs of coils of sections 7, 10 and 8.11 vary in the same way, and thus The unbalance voltage remains constant and equal to defects of any orientation.

Claims (3)

1. Surface mounted eddy current transducer with rotating field, containing 0 five 0 a system of excitation coils consisting of an annular skeleton and four identical sections placed on it, shifted one relative to the other by 90 °, the turns of each of the sections lie in planes passing through the axis of the annular skeleton, and the measuring coil consisting of two sections in the form of elongated loops located orthogonal to one another in the plane of the end of the ring frame, characterized in that, in order to increase the reliability of the control, it is equipped with an additional measuring coil, identical to the first one and placed in the sharpness of the second end of the ring frame. 2. A transducer according to claim 1, characterized in that the sections of the measuring coils are shifted relative to the sections of the excitation coil by an angle of 45 °. 3. The Converter in PP. 1 and 2, characterized in that sections of the measuring coil that are opposite to the annular frame are connected in pairs in series-counter. fpli8.2 To generator i.d j ig.Z To f / jOKy offpa- 1 -5 signal bobbings to loku ofpa omffu. signal