SU1420514A2 - Pass-through eddy-current transducer with revolving field - Google Patents

Description

(61) 1027592

(21) 4193671 / 25-28

(22) 11.02.87

(46) 08/30/88. Bul Number 32

(71) Research Institute of Introscopy of the Tomsk Polytechnic Institute. S.M. Kirov

(72) P. A. Ovs Nnikov

(53) 620.179.14 (088.8)

(56) USSR Author's Certificate No. 1027592, cl. G 01 N 27/90, 1983.

(54) PORTABLE VORTEX-THREADED CONVERTER WITH ROTATING FIELD

(57) The invention relates to non-destructive quality control of materials of products. The aim of the invention is to increase the reliability of the control. To achieve the goal, the converter contains an annular frame L placed on a main field winding, made of four 90 ° turned one relative to the other section 2, 3 and 4, 5 field windings, of the measuring winding placed on the holder 6, and consisting of sections 7-10, made in the form of elongated rectangular hinges, spaced coaxially to the frame, and two measuring tubes 11, 12 of the through passage type, four sections 14, 15 and 16, 17 of the compensating winding, according to the design similar sections. 7-10 of the winding placed with Im.metrically with respect to the relevant sections of the measuring winding. The pairs of sections 14, 15, and 16, 17 of the compensating winding are connected according to each other, and the opposite sections 7, 8 and 9, 10 of the measuring and co-compensation of the windings are connected in series with each other. 2 hp f-ly, 2 ill.

i

W

17

15

3

1

one

; The invention relates to the field of non-destructive testing, in particular, to eddy-current transducers for detecting defects in extended products.

The purpose of the invention is to increase the adequacy of the control by increasing the stability of the voltage unbalance and reducing the effect of radial displacements from - products.

: FIG. Figure 1 shows the constructive I scheme of a pass-through eddy current transducer with a rotating field (separate elements are spaced along the axis of the transducer for consistency); in fig. 2 is a wiring diagram for the converter windings. The eddy current transducer through passage contains an annular ferromagnetic frame 1, pairs of sections 2, 3 and 4, 5 of the excitation windings measured on it, shifted one relative to the other by 90 ° and connected to each other in series-counter, the holder 6, on which sections 7- are laid in grooves 10 of the first measuring winding in the form of elongated rectangular loops, the pairs of which are connected according to each other, and each pair - in series with each other, two measuring windings 11 and 12, of through-pass type, connected together in series with each other interchangeable yoke 13, which the frame 1 covers, and the yoke 13, in turn, covers the yoke 6, four according to the included sections 14, 15 and 16, 17 of the compensating winding in the form of elongated rectangular loops, the long sides of which are coaxial to the excitation system, and all sections of the compensating winding are arranged symmetrically with respect to the corresponding sections 7 and I of the first measuring winding and have an outer diameter equal to the internal diameter of sections 2, 3 and 4, 5 of the excitation windings 9.

Opposite bunks of sections 7, 8 and 9, 10 of the first measuring section and sections 14, 15 and 16, 17 of the compensating windings are connected in series with each other, the length of each section 14-17 of the compensating winding is selected from the relation

one

, 7

where Oi is the size of the long side of compensating winding section 1;

g is the diameter of the compensating winding, and the winding length of each section of the field winding is selected from the ratio

1 Qi

where, - the length of the winding r chda section of the excitation winding;

D is the inner diameter of the ring

frame.

The axis of the Converter passes the controlled product 18.

The converter works as follows.

in a way.

The pairs of sections 2, 3 and 4, 5 of the excitation windings, shifted by 90 ° one relative to the other (Fig. 1} are energized

Q of the same frequency and amplitude with a phase shift of 90 ° from the generator (not shown), resulting in a space bounded by frame 1, a rotating magnetic field with a magnetic induction vector perpendicular to the axis of the preformer. The resulting magnetic flux obtained in the control zone in the presence of product 18 can be considered as the sum of the excitation flux formed by the currents of the winding sections of the winding and the eddy current flux induced by the excitation flux in the product. The eddy currents in the product vary not only from the excitation flow, but also from the electrophysical properties of the controlled product.

5 The change in the transducer's magnetic flux, caused by a change in the electrophysical properties of the product, with a constant excitation flow, is equivalent to a change in the EMF of the measuring winding sections, according to

The value of which determines the parameters of the controlled product.

The diametrically opposed sections 7, 8 and 9, 10 of the first measuring and sections 14, 15 and 16, 17 of the compensating windings placed in a rotating magnetic field are included in pairs according to each other, and the opposite pairs of sections 7, 8, 14, 15 and 9, 10, 16, 17 measuring and co-compensation windings are included in pairs-counter (Fig. 2), while induced in the Q pax windings of sections 7, 8 and 14, 15 the EMF is determined by the projection of the magnetic induction vector on the horizontal axis (X axis), and in pairs 9, 10 and 16, 17 - on the vertical axis (Y axis). EMF of four pairs of sections 7, 8, 9, 10, 14, 15 and 16, 17 of the first measuring

5 and the compensation windings and the EMF of the two measuring windings 11 and 12 of the pass-through type, connected in series to each other, are equal if there is no product defect in the transducer zone 18. The values of these EMF are not equal if there is a defective part of the product in the transducer. The difference between the voltages of these measuring windings, iodable in the signal processing unit (not shown) and determined by the size of the defect, is highlighted

5 electronic circuit. When a defective area appears in the control zone, the length of which is greater than the small side of the elongated rectangular loops of sections 7-10 and 14-17 of the first measuring and compensating windings, the maximum variation of the EMF is observed for the first measuring winding, sections 7-10 of which are included in pairs according to At the same time, the change in the emf of the compensating winding is minimal due to the fact that its sections 14-15 are more distant from the product than the first measuring winding. The difference between the measuring and compensating windings is maximum, since they are connected with each other in opposite directions and proportional to the size of the defect. In this case, the difference between the voltages of the second and third measuring windings I, 12 of the pass type is minimal, since a defective area of significant magnitude is simultaneously under both windings connected in opposite directions. In this case, there is a place for comparison of two identical parts of the product.

When a short defect appears in the transducer, the length of which is less than the small side length of the elongated rectangular loops of the first measuring and compensating windings, the maximum variation of the EMF is observed in measuring windings 11 and 12, so when the monitored object moves, the defective section will first appear under the single measuring winding 12, and then under another measuring winding 11, and the difference between the voltages of the pairs of sections of the first measuring and compensating windings is the smaller, the smaller the length defects in the direction of the axis of the transducer.

The stability of the output voltage of each pair of sections 7-10 of the first measuring winding, which carries information only about the test object, is achieved due to the fact that pairwise according to the included sections 7-10 of the first winding are turned on opposite with corresponding pairs 14-17 co-compensation winding remote from the control object for a longer distance. The initial emf of these windings is equal and determined by the same excitation flow, and when the magnetic induction vector of the excitation field voltage is changed

the imbalance remains unchanged. In this case, the compensation of the voltage ho, the stroke of the stroke occurs by switching on these windings. This increases the stability of the imbalance voltage in the control process and reduces the effect of the radial displacements of the product on the control results.

Claims (3)

1. Eddy-current feedthrough with rotating field according to the ed. St. 1027592, characterized in that, in order to increase the reliability of control by increasing the stability of the voltage unbalance and reducing the effect of radial mixing of the product, it is equipped with four according to the included sections of the compensating winding in the form of elongated rectangular loops, the long sides of which are coaxial excitation winding, all sections of the compensating winding are arranged symmetrically with respect to the corresponding sections of the first measuring winding and have an outer diameter equal to the internal diameter of the winding day, and the length of the winding of each section of the field winding is selected from the ratio I,  fa where E, is the winding length of each section of the field winding; inner diameter of the ring frame. 2. The transducer according to claim 1, characterized in that the opposite pair of sections the first measuring and compensating windings are connected in series with each other. 3. The Converter in PP. 1 and 2, characterized in that the length of each section of the compensating winding is selected from the ratio 1 1g- 2 where Ej is the size of the long side of the compensating winding section; D is the diameter of the compensating winding. To 5flOKan signalization processing to block signal processing FIG. 2