ICHIHOKOSEIDENJIKOTAINOSHORIHOHO

摘要

PURPOSE:To make an iron loss characteristic uniform and stable in a short period by forming many micro film-removed parts to a grain oriented electrical steel strip having an insulating film and spraying a nitric acid soln. thereto to etch the film-removed parts. CONSTITUTION:The grain oriented electrical steel strip S which has the insulating film and high magnetic flux density and is let off from an un-coiler 1 is passed through a laser beam irradiating device 2 where the many micro film- removed parts are formed by a laser beam. The above-mentioned electrical steel strip S is then passed through an acid soln. sprayer 3. The nitric acid soln. in an etching liquid circulation tank 10 is sprayed by a pump 13 from many spray nozzles 8 in said sprayer to efficiently etch the base iron in the micro film-removed parts. The above-mentioned nitric acid soln. having 20-70wt% nitric acid concn. is adequate. The strip S is thereafter passed through rinsing and drying device 4, an insulation recoater 5 and a baking part 6 and is coiled by a coiler 7. The grain oriented electrical steel sheet which has the uniform and stable iron loss characteristic in the longitudinal and transverse direction and obviates the deterioration in the iron loss characteristic even after stress relief annealing is thus obtd. in a short period.