RU1839239C - Eddy-current transducer for non-destructive inspection of non-magnetic material - Google Patents

Description

placed on the working end, the thickness t of which is selected from the condition:

0.1 d t 0.6 d.

where d is the outer diameter of the measuring coil.

The drawing shows an eddy current transducer for non-destructive testing of non-magnetic materials.

The converter comprises a core magnetic core 1 made of a ferrodielectric, on which measuring 2, exciting 3 and compensation 4 coils are placed. Relative to the part of the magnetic circuit 1, where the compensation coil 4 is located, the compensator 5 moves in the form of an additional ferrodielectric magnetic circuit installed in the washer 6, which can move along the threads made on the inner surface of the protective housing 7. Magnetic circuit I, measuring coil 2 and the exciting coil 3 are fastened together with a protective casing 7 and a dielectric protective gasket 8 with a rubber-like compound 9. The thickness t of the protective gasket provides an increase in operational reliability, is selected within 0.1d t 0.6d.

The eddy current transducer is used as follows.

In the manufacture of the outer housing of the ECP, the thickness of the protective strip 8 is selected closer to the upper limit of the specified ratio. By the number of turns and the location of the compensation coil 4 on the magnetic circuit, approximately the required degree of compensation is established. Fine adjustment of the ECP is carried out by moving the compensator 5 relative to the end of the magnetic circuit 1 from the side of the compensation coil 4.

During operation, when the thickness of the protective strip 8 is reduced due to abrasion or it is required to clarify the compensation voltage, the adjustment of the converter to maintain the declared accuracy of the device consists in moving the compensator 5.

The movement of the compensator from the ferrodielectric, in contrast to the electrically conductive compensator, practically does not lead to a change in the phase and magnitude of the resulting magnetic flux of the ETC excitation winding, which interacts with the electrically conductive material of the controlled product. As the compensator 5 moves, the configuration of the magnetic circuit and the magnitude of the magnetic flux interacting with the compensation coil change due to changes in the scattering fields. The change in magnetic flux necessary for compensation due to these reasons is maintained for certain values of the gap between the end face of the main magnetic circuit with the measuring coil and the surface of the product being monitored.

For wider limits exceeding the above ratio, the required level of compensation cannot be reached.

The use of the proposed eddy current transducer with a large thickness of the protective strip allows 3-4 times to increase the operational reliability of the transducer while maintaining the stability of the output characteristics. providing high measurement accuracy with a device using it. The use of a rubber-like compound helps the transmitter maintain stable output characteristics.

possible random collisions with a hard surface. The introduction of a compensator made of ferrodielectric significantly simplifies the setup process in the manufacture and adjustment of the ECP when abrasion of the protective coating, increases the range of detuning from changes in the main interfering factor - the gap between the ECP and the surface of the controlled product.

(56) Dorofeev A.D. et al. Induction thickness gauges. M .: Energy, 1978, p.139-140.

 USSR copyright certificate No. 359504, cl. G 01 B 7/06, 1970.

USSR copyright certificate No. 508735. class G 01 N27 / 90, 1974.

Claims (2)

The claims  V eddy current transducer for non-destructive testing of non-magnetic materials by the phase method, comprising a housing, a magnetic circuit, an exciting coil, measuring and compensation coils located on the magnetic circuit on different sides of the exciting circuit, as well as a compensator installed with the ability to move the compensation circuit relative to the magnetic core end from the side that, in order to improve the control accuracy by detuning from the influence of the gap change, the magnetic circuit is made rod, as a material of the magnetic circuit 5 and the compensator used ferrodielekt- rick. 2. The converter according to claim 1, characterized in that it is provided with a dielectric protective gasket located on the working end face, the thickness t of which is selected from the condition 0.1d t 0.6d. where d is the outer diameter of the measuring coil 15.