EDDY-CURRENT FLAW DETECTION METHOD Russian patent published in 1994 - IPC

FIELD: non-destructive flaw detection. SUBSTANCE: method involves the steps of: exciting a longitudinal magnetic field in a longitudinally moving article, obtaining a voltage caused by a difference in eddy-current fields from two adjacent portions of articles and measured with the aid of two coils of measuring channel the location planes of turns of which are orthogonal to the direction of exciting magnetic field, providing an auxiliary second measuring channel in which a voltage caused by a difference in eddy-current fields from two adjacent portions of the article one of which is located in the middle of the portions analyzed by the first channel is measured with the aid of two coils, switching the voltages and obtaining a signal used for estimating defectiveness of the article by comparing the voltages switched, a switching frequency being determined from the expression given in the invention description, where F is a channel switching frequency in Hz, V is a speed of the article being inspected, H is a base distance between the coils of one of the channels. EFFECT: enhanced accuracy due to reduced influence of article speed. 1 dwg