ELECTROMAGNETIC FLAW DETECTOR TO TEST LONG-LENGTH ARTICLES Russian patent published in 2000 - IPC

FIELD: nondestructive inspection of rolled products and pipes. SUBSTANCE: proposed flaw detector employs bushing eddy-current converter with one current winding and two differential pairs of measurement windings. Differential pairs of measurement windings are connected to corresponding circuits of amplitude-phase processing of signal. Output of first circuit of amplitude-phase processing of signal is linked directly to one of inputs of differential amplifier and output of second circuit - to another input of mentioned amplifier via adjustable amplifier. In this case second ( additional ) pair of measurement windings is located on outer side of current winding. Additional pair of measurement windings has diameter D_m2 = D_m1+(8÷12)l, where D_m1 is diameter of first differential pair of measurement windings and l is distance between windings of differential pair along longitudinal axis of converter. Employment of additional pair of measurement windings makes it feasible to raise reliability of inspection thanks to mutual compensation of noise signals from structural inhomogeneities of material of object of test. EFFECT: raised reliability of inspection of long-length articles. 3 dwg