RU2265208C1 - Electromagnetic-acoustic transformer - Google Patents

Abstract

FIELD: non-destructive control methods.

SUBSTANCE: device is provided with at least two ring-shaped permanent magnets, tightly pressed to each other, with position of poles on outer and inner side surface, and at least one round permanent magnet, mounted on one side of their end surface and directed to their inner poles by pole of same sign and cylindrical concentrator, made of ferromagnetic material and mounted on same axis with round magnet inside ring-shaped magnets. On the side, directed to inductiveness coils, concentrator is made at least with two shelves, forming magnetic poles of same polarity. Each inductiveness coil is made multilayer by height of separate conductors, connected serially with transfer from higher layer onto lower layer in n coils, separated from each other by a layer of dielectric substance.

EFFECT: decreased sensitivity due to decreased size of bobbins and increased number of coils.

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Description

The present invention relates to the field of ultrasonic non-destructive testing of materials and products and can be used, in particular, for quality control of products of the metallurgical industry (sheet, strips, long products, pipes, etc.).

Known EMAT containing a non-magnetic housing, a cover, a connector and inductors mounted on a protective substrate of a dielectric [1], superimposed on one another, made in separate sections, wound with one wire and connected to a high-frequency generator.

A disadvantage of the known Converter is the need to place it in an external magnetic field to ensure operation.

Known EMAT [2], comprising a housing, permanent magnets and inductors, equipped with at least three inductors, three concentrators located above the coils. A disadvantage of the known converter is its low sensitivity.

The purpose of the invention is a significant increase in the sensitivity of EMAT by reducing the size of the coils while increasing the number of turns.

To do this, the proposed Converter is equipped with at least two annular permanent magnets tightly adjacent to each other with the poles on the outer and inner side surfaces, at least one circular permanent magnet mounted on one side on their end surface and facing their inner poles with the same pole and a cylindrical hub made of ferromagnetic material and mounted on the same axis with a round permanent magnet inside the ring magnets, con the centralizer on the side facing the inductance coils is made with at least two protrusions forming magnetic poles of the same polarity, each inductance coil is multilayer in height from individual conductors connected in series with the transition from the overlying layer to the underlying layer through n turns, separated from each other by a dielectric layer.

The invention is illustrated in the drawings. Figure 1 shows a transverse section of the Converter, figure 2 shows the layout of conductors in a two-layer coil, figure 3 shows a layout of conductors in a three-layer coil, figure 4 shows a layout and connection of conductors in a two-layer coil.

The Converter (figure 1) contains a housing 1 with an internal thread made of non-magnetic material, a nut 2 with an external thread made of non-magnetic material, a sleeve 3 made of magnetic material, a cover 4 made of non-magnetic material, a substrate 5 made of non-magnetic material made of magnetic material, a hub 6 made of at least two protrusions "C" of ferromagnetic material, a permanent round magnet 7 with the location of the poles NS along the end surfaces, constant to face magnets 8 with NS poles located along the outer and inner side surfaces, dielectric pads 9, 10, screws 11, 12, 13, 14, intended for fastening the converter parts, inductors 15 glued to the plates 16, protecting them from damage, connector 17.

Permanent ring magnets 9, connected to each other at the ends, are inserted along the inner diameter d _m onto the sleeve 3 (Fig. 1) and inserted along the outer diameter D into the housing 1. The hub 6 is inserted into the sleeve 3. The permanent magnets 7 and 8 are mounted on relative to each other and to the surface of the concentrator in such a way that all their poles of the same name, for example, S are turned towards the lateral surface of the concentrator 6, the protrusions "C" of which in this case have the same polarity S and are the same poles through which the magnetic flux (not conditionally bonded) penetrating the inductor 15 shorted to the control object with pole N.

Inductors 15 are multi-layer in height in several layers, the number of which can be limited only by the size of the air gap between the substrate 5 and the control object. The conductors 18 in the coil 15 are made of rectangular cross section with a width of d _e and placed in increments of d in layers with the transition from one layer to another (figure 4) through n turns. Each layer in the coil 15 is separated from the other by a dielectric layer 20 of thickness h and has several groups of turns with a different number of conductors.

For example, in the coil shown in FIG. 4, the upper layer 19 consists of two groups of turns. The first group has three turns (pos. 21, 22, 23, n = 3), and the second group has two turns (pos. 28, 29, n = 2). The lower layer 30 has one group of turns (pos. 24, 25, 26, 27, n = 4). According to the winding connection diagram (Fig. 4), the last turn 23 of the first group in the upper layer 19 is connected to the first turn 24 of the turn group in the lower layer 30, and the last turn 27 of the turn group in the lower layer 30 is connected to the first turn 28 of the second turn group of the upper layer 19.

This arrangement of conductors in a multilayer coil with a transition from one layer to another through n turns allows several times the voltage of the probe pulse, and the minimum dimensions of the coil allow, with limited printing technology, to increase the sensitivity of the transducer when receiving ultrasonic waves.

In addition, the above arrangement of conductors in a multilayer coil allows you to provide the minimum possible thickness of the insulating layer h at given values of dielectric strength, potential difference between the conductors and the number of turns.

According to the invention, the coil shown in FIG. 4 can have many different combinations of connections of conductors 18 of n turns 19.

When the poles of the magnets 8 are located relative to the surface of the concentrator of the same polarity, it allows to concentrate most of the magnetic flux in the concentrator 6, to reduce leakage losses, and the protrusions "C" on the end of the concentrator 6 provide the maximum concentration of the magnetic flux in the active zones of the coils 15. In this case, the maximum the density of the magnetic flux crossing the inductor, the magnetic induction in the gap δ increases significantly, and therefore, the sensitivity of the conversion when recording ultrasound waves reflected from defects. Due to the minimum dimensions of the inductor and the concentrator with several protrusions-poles (Fig. 1 shows a concentrator with two protrusions), the proposed converter without increasing its dimensions contains not one but several coils of inductance, which allows to expand the control zone (in Fig. 1 two coils are shown 15).

The converter operates as follows.

The converter is brought to the object of control. The magnetic field closes on the metal. Sensing pulses are supplied to the inductor 15 with a certain frequency, exciting ultrasonic vibrations in the test object, transformed in a constant field of the magnetic system of the transducer into alternating magnetic fields, creating alternating currents in the inductor 15 received in the form of electrical signals by the receiver (not shown conventionally in the drawing ) By the ratio of the pulse reflected from the defect to the reference one judges the coordinates and dimensions of the defect.

Sources of information

1. RF patent No. 2206888, bull. No.17, 06/20/2003

2. RF patent №2219539, bull. No. 35, December 20, 2003

Claims (1)

An electromagnetic acoustic transducer comprising a housing, permanent magnets and inductors, characterized in that it is provided with at least two annular permanent magnets tightly adjacent to each other with poles on the outer and inner side surfaces of at least one round permanent magnet mounted on one side on their end surface and facing their inner poles of the same name pole, and a cylindrical hub made of ferromagnetic material rial and mounted on the same axis with a round permanent magnet inside the ring magnets, the hub on the side facing the inductors is made of at least two protrusions forming magnetic poles of the same polarity, each inductance is made multilayer in height from separate conductors, connected in series with the transition from the overlying layer to the underlying layer through n turns, separated from each other by a dielectric layer.

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