Method and device for magnetic domain refinement of oriented electrical steel plate

A method for miniaturizing magnetic domains of a directional electric steel plate comprising:

• a steel plate supporting roll position adjusting step that controls a vertical direction position of a steel plate while supporting the steel plate progressing along a production line;
• and
• a laser emitting step that melts the steel plate by emitting a laser beam to form grooves on a surface of the steel plate for miniaturizing magnetic domains of the steel plate,
• wherein the laser emitting step comprises an angle changing step that changes an emitting line angle of the laser beam with respect to a width direction of the steel plate while an optical system emitting the laser beam onto the steel plate is rotated by a driving unit with respect to the steel plate, and a focal distance maintaining step that changes a tilt of the steel plate supporting roll which supports the steel plate according to a change in focal distance of the laser beam in the width direction of the steel plate,
• wherein the focal distance maintaining step comprises a tilt angle calculating step that calculates a tilt of the steel plate supporting roll in accordance with a change in focal distance of the laser beam on the surface of the steel plate due to a rotation of the optical system in the angle changing step, and a tilt adjusting step that changes the tilt of the steel plate supporting roll by moving each end of the steel plate supporting roll up and down, respectively, according to a value calculated in the tilt angle calculating step.