Defect detection method for elongated ferromagnetic object, e.g. steel wire cable, uses magnetization and detection of magnetic field parameters at spaced points

摘要

The detection method has the elongated ferromagnetic object (1) magnetized in the longitudinal direction via a magnetization unit with spaced magnetic poles (3,4) and the magnetic field parameters measured at 2 or more points via magneto-sensitive sensors (9,10), positioned in pairs parallel to the center line of the ferromagnetic object. The difference between the sensor signals is used for detecting a localized defect of the ferromagnetic object and the sum of the sensor signals is used for detecting a metalized surface. An Independent claim for a magnetic non-destructive testing device for an elongated ferromagnetic object is also included.