LEAKAGE FLUX FLAW DETECTING-APPARATUS AND METHOD FOR JUDGING DEFECT

摘要

PROBLEM TO BE SOLVED: To highly accurately detect minute flaws. SOLUTION: A leakage flux flaw-detecting apparatus 10 is comprised of an exciting yoke 14 for magnetizing a long work 12 and four detect coils 16 arranged along a running line via a predetermined interval. Magnetic poles 14a and 14a of the exciting yoke 14 are disposed via a yoke gap G1 to an outer circumferential face of the long work 12. The exciting yoke 14 is formed of a silicon steel containing Si by 6.0-7.0%. The yoke gap G1 is set to be 2 mm or smaller. The detect coils 16 are wound to leg parts of a core. The coils 16 are connected to a flaw detect control panel 24 and output flaw detect signals. The core is formed of Permalloy superior in magnetic permeability. A wire diameter of a wiring constituting the detect coils 16 is set to be 0.05 mm or smaller.