METHOD AND DEVICE FOR DEMAGNETIZING LONG-MEASURING FERROMAGNETIC PARTS Russian patent published in 2005 - IPC

FIELD: demagnetizing ferromagnetic materials and parts.

SUBSTANCE: proposed method that can be used, for instance, after ultrasonic inspection by acousto-electromagnetic method involving part magnetization includes part exposure to variable magnetic field whose amplitude reduces from certain maximal value to zero. Part is demagnetized by means of solenoid-type coil winding excited through ferromagnetic core and connected to capacitor; it is moved along surface of part and the latter is stepwise and locally demagnetized. Part being demagnetized is divided into exposure sections of length l inversely proportional to part thickness or to part wall thickness and to residual flux density B of part material magnetic field; in the process coil is positioned so as to ensure that first-pulse strength vector of demagnetizing magnetic field on exposure length l_x will be perpendicular to part inherent field strength and reverse to strength field on section l_{x - 1}; upon impact onto all local sections l residual magnetization is eliminated by acting on last section; to this end magnetic flux is reduced in antiphase relative to impact onto remaining sections.

EFFECT: reduced demagnetizing time.

4 cl, 2 dwg