| 摘要 |
PURPOSE:To make uniform and reduce iron losses in respective positions at a sheet surface by irradiating the surface of a finish-annealed grain-oriented silicon steel sheet with an electron beam having an intensity distribution uniform in a width direction so that the electron beam is scanned across the above sheet surface in a direction across the rolling direction of the sheet. CONSTITUTION:A finish-annealed grain-oriented silicon steel sheet 8 is irradiated with an EB(electron beam) 7 from an EB gun 2 having a high voltage insulator 1 via an anode 3 and a column valve 4, and the electron beam 7 is scanned across the surface in a direction across the rolling direction of the above steel. By the above procedure, local microstrain nearly perpendicular to the rolling direction is introduced into the surface of the above silicon steel sheet 8, by which a grain-oriented silicon steel sheet reduced in iron loss is obtained. At this time, by dynamically controlling the above EB 7 by means of an electric current from an electromagnetic lens 5 and an electric current from a deflection coil 6, respective focal distances toward focuses 7-1, 7-2, 7-3 in the width-direction central part and both edge parts of the above silicon steel sheet 8 can be properly corrected. By this method, the uniformization and reduction of iron loss mentioned above can be attained and, as a result, the low-iron-loss grain-oriented silicon steel sheet in which iron loss is uniformly reduced in respective positions at the sheet surface can be obtained. |
