| 摘要 |
PURPOSE: A method for removing oxide film formed on annealed hot rolled steel sheet for electrical steel sheet using high pressure water, a method for manufacturing the annealed hot rolled steel sheet for electrical steel sheet comprising a process for removing oxide film on the surface of annealed hot rolled steel sheet by the method, and an apparatus for manufacturing the annealed hot rolled steel sheet are provided. CONSTITUTION: In a method for removing oxide film formed on the surface of annealed hot rolled steel sheet by annealing the hot rolled steel sheet in the hot rolled steel sheet annealing process after manufacturing a hot rolled steel sheet by hot rolling a silicon steel slab containing 0.5 to 5 wt.% of silicon (Si), the method comprises a step of rapidly cooling the annealed hot rolled steel sheet to 100 deg.C or less from a temperature of 900 deg.C or more in a cooling rate of 50 deg.C/sec or more; and a step of removing the oxide film formed on the surface of the annealed hot rolled steel sheet by spraying high pressure water having pressure of 1,000 bar or more onto the annealed hot rolled steel sheet. The apparatus(100) comprises an annealing furnace for annealing hot rolled steel sheet(7), a cooler for cooling the annealed hot rolled steel sheet, an oxide film remover for removing an oxide film formed on the surface of the annealed hot rolled steel sheet by spraying ultra-high pressure water onto the surface of the cooled annealed hot rolled steel sheet, and a dryer for drying the oxide film removed annealed hot rolled steel sheet, wherein pickling tank and washing tank are additionally installed in rear of the oxide film remover, and wherein the apparatus comprises at least one set or more of upper and lower bending rolls(131,132) positioned with being spaced apart from the oxide film remover in a certain distance in a proceeding direction of the strip to give tensile stress to the surface of the hot rolled steel sheet; high pressure water nozzle heads(141,142) oppositely directed to each other with the respective upper and lower bending rolls and the strip being positioned between the high pressure water nozzle heads; and a plurality of nozzles(160) installed at the high pressure water nozzle heads to spray high pressure water onto respective bending parts stretched by the upper and lower bending rolls.
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