METHOD FOR DETECTING DEFECTS IN A LONG-DIMENSIONAL FERROMAGNETIC OBJECT Russian patent published in 2018 - IPC G01N27/82 

FIELD: defectoscopy.

SUBSTANCE: invention relates to the field of non-destructive magnetic control of long ferromagnetic objects, and is intended primarily for magnetic testing of steel ropes and wire in order to determine their local defects and losses of metal section, and can also be used for defectoscopy of electric cables with ferromagnetic elements in the form of steel conductors, armor coatings, electromagnetic shields, etc. When the method is realized by a physical field consisting of an alternating electric field and a constant magnetic field, act simultaneously on the controlled long ferromagnetic object and the reference ferromagnetic object of finite length, corresponding to the assortment of the object under test without defects. Through this effect, both objects excite the magnetoelectric and magnetic modulation effects, with the help of which they form a measuring signal, respectively, in the controlled object, and in the reference object, a reference signal proportional to the change in the physical field. In this case, the measuring and reference signals are formed in the form of corresponding EMF induction, containing transformer and magnetomodulation components, compare the antiphase overlap with the measuring and reference signals and judge the presence of defects in the object by the parameters of the result of the comparison. To detect defects such as loss of metal section, as a parameter of the comparison result, the difference of the transformer components of the EMF of the measuring and reference signals at the excitation frequency of the vibrator antenna is used, and to detect local defects, as a parameter of the comparison result, the difference of the magnetically modulated components of the EMF of the measuring and reference signals at the double excitation frequency of the vibrator antenna is used. In this case, the alternating electric field in the object is created by means of a capacitor dipole antenna, the impact of the physical field is carried out at the frequency of the electromechanical resonance of the controlled ferromagnetic object, and the intensity of the constant magnetic field is chosen from the condition taking into account the amplitude of the longitudinal component of the magnetic field of the transverse electric TE wave excited by the vibrator antenna.

EFFECT: technical result consists in increasing the accuracy of defect detection and expanding the range of controlled parameters.

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