Detection apparatus and method based on electromagnetic detection signal for distinguishing inner and outer wall defects

Abstract

The invention discloses a detection method based on electromagnetic detection signal for distinguishing inner and outer wall defects, which comprises the following steps: the step 1: a workpiece to be detected and a detecting coil are placed in an external partial magnetic saturation environment; the step 2: a microprocessor generates a square wave excitation signal with a certain frequency, and an excitation amplification circuit carries out a power amplification of the square wave excitation signal for excitation of a first detection coil and a second detection coil; the step 3: the first detection coil and the second detection coil in a difference mode form a differential electromagnetic sensor, and the square wave excitation signal after power amplification by the excitation amplification circuit is loaded; the step 4: signals of the difference electromagnetic sensor are picked by a differential signal amplification circuit for amplification with adaptability; the step 5: the signals after differential amplification by the differential signal amplification circuit are subjected to rectification and integral processing by an integral processing circuit for determining the defects of the workpiece to be detected. The invention is applied to distinguish inner wall / outer wall defects.

Description

technical field [0001] The invention belongs to the technical field of non-destructive detection of material defects, in particular to a detection device and method based on electromagnetic detection signals that can distinguish inner wall / outer wall defects. Background technique [0002] Eddy current testing is one of the methods of non-destructive testing in industry. The basic principle of eddy current testing is to place the coil with alternating current on the metal plate to be tested or put it outside the metal tube to be tested. At this time, an alternating magnetic field will be generated in and around the coil, which will cause a vortex-shaped induced alternating current in the workpiece to be measured, which is called eddy current. The distribution and size of the eddy current is not only related to the shape and size of the coil, the size and frequency of the alternating current, etc., but also depends on the conductivity, magnetic permeability, shape and size of ...

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Problems solved by technology

However, this invention requires unsaturated DC magnetization of the material. In actual detection, the magnetization current needs to be adjusted according to different detection objects, and because the inner / outer wall defects are distinguished by phase, the defect signal needs to be rotated to the required Phase, in the actual detection, need to adjust more parameters, not easy to use

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