Method of and apparatus for magnetically detecting flaws in ferromagnetic objects bysuperimposing magnetic tapes or rollers thereon

Claim 1

A METHOD OF MAGNETICALLY TESTING FERROMAGNETIC OBJECTS FOR FLAWS, COMPRISING PROGRESSIVELY LAYING AN UNMAGNETIZED PORTION OF A MAGNETIZABLE MEDIUM ON A SURFACE AREA OF A MAGNETIZED FERROMAGNETIC OBJECT, SAID MEDIUM BEING CONTINUOUSLY LENGTHWISE LAID ON SAID SUBJECT; REMOVING SAID LAID MAGNETIZABLE MEDIUM PORTION; AND SCANNING SIMULTANEOUSLY ALONG THE TRANSVERSE AND LONGITUDINAL DIMENSIONS OF SAID REMOVED MEDIUM PORTION FOR DEFECTS RECORDED THEREON ALONG THE LONGITUDINAL AND TRANSVERSE DIMENSIONS, BY PASSING SAID REMOVED MAGNETIZABLE MEDIUM PORTION NEAR AT LEAST TWO MOVING MAGNETIC DETECTORS DISPOSED TO SENSE LONGITUDINAL AND TRANSVERSE DEFECTS RECORDED IN SAID MAGNETIZABLE MEDIUM; ONE OF SAID MAGNETIC DETECTORS HAVING A SCANNING SURFACE RELATIVELY MOVING SUBTANTIALLY PARALLEL TO THE LENGTH OF SAID MAGNETIZABLE MEDIUM AND ANOTHER OF SAID DETECTORS HAVING A SCANNING SURFACE RELATIVELY MOVING SUBSTANTIALLY TRANSVERSE TO THE LENGTH OF SAID MAGNETIZABLE MEDIUM.