IMPROVEMENT DESIGN OF MAGNETIZER FOR MAGNETIC POWDER FLAW DETECTION WITH A.C. NONLINEAR ANALYSIS.

摘要

Magnetic powder flaw detection of steel products requires strong magnetization to detect the flaws. However, when a square billet in Fig. 1 is magnetized by a high-power magnetizer, the normal components of the magnetic flux density are over-intensified and magnetic powder over-adheres around comers of the billet. A required performance of the magnetizer is magnetizing the test surfaces over 1.4[T] with suppressing the normal components of the flux density to the surfaces under 0.04[T]. To realize the performance, we have investigated magnetic shielding and coil-current optimization to the improvement design with FEM analysis [1].