SU903759A1 - Eddy current strap converter matrix - Google Patents

Description

The invention relates to non-destructive testing of complex metal products and can be used for flaw detection in any industry.

Known matrix eddy current overhead transducer containing a flat spiral inductor with a uniform winding pitch, installed layers on a substrate, and coated with a dielectric film [11.

The disadvantage of the Converter is the low reliability of control, due to the fact that the Converter does not create a uniform magnetic field and does not allow the control of complex products.

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

This goal is achieved by the fact that in the matrix of eddy current overhead transducers containing flat spiral inductors mounted on layers on a substrate and covered with a dielectric film, the coils are made with a variable winding pitch increasing toward the center of the spiral, and the substrate is made elastic ⁵ .

In FIG. 1 shows a matrix diagram of eddy current overhead transducers, section; in FIG. 2 - distribution of magnetic strength ^{, 0} field of flat spiral coils with a variable winding pitch along the plane of the spirals, increasing towards the center of the spiral.

The matrix of current-eddy overhead transducers contains an elastic substrate 1 made of a material based on films of lavsan or fluoropolymer mounted on a substrate 1 of a winding 2, made by printing technology in the form of flat, with a given change in pitch, spirals, leads 3 of the windings 2 connected to a flexible circuit board 4 with 903759 wiring. The matrix is coated with a protective coating 5, which is a strong dielectric film that protects the windings 2 and the connecting wiring from shorting to the surface of the controlled products and from mechanical and atmospheric influences.

The matrix of eddy current overhead transducers works as follows.

It is superimposed on the surface of the controlled product (not shown), fitting it and, thereby, ensuring the maximum value of the coupling coefficient.

The windings 2 are included in the power and measurement circuit, for example, as an element of the oscillator circuit. Flat helical inductors induce a magnetic field in the product being monitored. Unlike coils with a constant winding pitch, variable pitch helical inductors create a field that is almost uniform throughout the control zone. Eddy currents are induced in the surface layer of the metal product, the magnitude and distribution of which are determined by a change in the controlled parameter. The active and reactive resistance of the windings change in accordance with the change in eddy currents, and hence the controlled parameter.

The sensitivity of the windings of the matrix of eddy current overhead transducers to changes in the controlled parameter will be almost constant along the plane of the spirals. Changes in the active and reactive resistance of one winding or group of windings carry information about the magnitude of the change in the controlled parameter and the location of this change. In this case, reliable registration of a defect, both point and long, is ensured, regardless of its location relative to the windings.

The matrix of current-eddy overhead transducers allows you to simultaneously control large surfaces of metal products with the most complex profiles, for example, in narrow and deep grooves, etc. In addition, spiral coils of inductance manufactured by printing technology, even without ferromagnetic cores, have large inductances per surface unit (10 μG / cm) due to very narrow conductors and small 20 distances between them (15-25 μm), which ensures their higher relative sensitivity compared to solenoidal inductors.

Claims (1)

The invention relates to the non-destructive testing of thin-profile metal products and can be used for defectoscopy in any branch of mechanical engineering. A matrix of an eddy current in a cladding converter is known, containing flat spiral inductors with a uniform winding pitch, installed in layers on the substrate, and covered with dielectric film ll. The disadvantage of the converter is the low reliability of the control, due to the fact that the converter does not create a uniform magnetic field and does not allow the control of complex profiles. The purpose of the invention is to increase the reliability of the control. The goal is achieved by the fact that in the matrix of over-eddy overhead transducers containing flat spiral inductors. installed by layers on the substrate and covered with a dielectric film, the coils are made with variable winding pitch, increasing towards the center of the helix, and the substrate is elastic. FIG. 1 shows a diagram of a matrix of overhead eddy current transducers, a section; in fig. 2 shows the intensity distribution of the magnetic field of flat spiral coils with variable winding pitch along the plane of the spirals, increasing towards the center of the spiral. The matrix of the eddy-edged overhead transducers contains an elastic substrate 1 made of material based on lavsan or fluoroplastic films fixed on the substrate 1 of the winding 2, made according to printing technology in the form of flat, with a given change of pitch, spirals, conclusions 3 of windings 2 connected to flexible wiring with 3 wiring. The matrix is coated with a protective coating 5, which is a durable dielectric film that protects the windings 2 and the connecting wiring from the closure with the surface of the tested products and from mechanical and atmospheric influences. The matrix of overhead eddy-current converters works as follows. It is superimposed on the surface of the test article (not shown), making it easier, and thus providing the maximum value of the coupling coefficient. The windings 2 are included in the power and measurement circuit, for example, as an element of the oscillator circuit. Flat spiral inductors induce a magnetic field in a controlled product. Unlike coils with a constant step of winding, spiral inductors with variable pitch create a field that is almost uniform throughout the entire control area. In the surface layer of the metal, eddy currents are induced, the magnitude and distribution of which are determined by a change in the parameter being controlled. The active and reactive resistances of the windings vary in accordance with the change in eddy currents, and hence in the controlled parameter. The sensitivity of the windings of the matrix of vortex overhead converters to changes in the monitored parameter will be almost constant along the plane of the spirals. Changes in the active and reactive resistances of one winding or group of windings carry information about the magnitude of the change in the monitored parameter and the location of this change. In this case, it is ensured that the defect is reliably registered, both point and long, regardless of its location relative to the windings. The matrix of overhead eddy current transducers allows you to simultaneously control large metal surfaces with the most complex profiles, for example, in narrow and deep grooves, etc. In addition, spiral inductors made by printing technology, even without ferromagnetic cores, have large inductances per surface unit (10 µG / cm) due to very narrow conductors and small distances between them (15-25 µm), which provides their higher relative sensitivity in comparison with solenoidal inductors. Claims of Invention Matrix of eddy-current-wall overhead converters, contained; Flat spiral inductors installed in layers on the substrate and coated with a dielectric film, characterized in that, in order to increase the reliability of control, the coils are made with variable winding pitch, increasing towards the center of the helix, and the substrate is elastic. Sources of information taken into account during the examination 1. USSR Author's Certificate No. 700830, c. G 01 N 27/86, 1978 (prototype). And zhish D d f. JBlB H BMi KMflLBMniH HL HIB JILBM "jHJBJIf FIG. 2