公开(公告)号：WO1986000412A1

公开(公告)日：1986-01-16

申请号：PCT/US1985001241

申请日：1985-06-26

Applicant: LTV STEEL COMPANY, INC.

Inventor： LTV STEEL COMPANY, INC. ,  HARRIS, Richard, M. ,  VALEK, David, A. ,  ABRAMCZYK, Richard, F. ,  TOTH, James, M.

IPC: G01N27/82

CPC classification number: G01N27/9013 ,  B21B38/00 ,  G01N27/902

Abstract: Method and apparatus for scanning a generally cylindrical workpiece for flaws. A cylindrical metallic sleeve (30) is rotatably supported about a workpiece path of travel. Two differentially wound energization coils (34a, 34b) surround the sleeve near two apertures (32a, 32b) in the sleeve. The coils are energized with a high frequency signal that induces eddy currents in the workpiece. The apertures periodically disrupt the eddy current inducing magnetic fields which enhances signals from the coils indicative of the presence of flaws in the workpiece.