| 摘要 |
PROBLEM TO BE SOLVED: To simplify a subsequent acid cleaning process, in descaling a hot rolled strip through high screw-down cold rolling, by maintaining a specific relation between the thickness of hot rolling scale and the draft. SOLUTION: A hot rolled strip 1 with hot rolling scale sticking is unwound from a pay-off reel 2 and, through a bridle roll 3, rolled by high screw-down rolling using a cold rolling mill 4. The hot rolling scale is cracked by the high screw-down rolling, crushed and stripped from the steel strip 1; then, the crushed scale remaining on the surface of the steel strip is removed by a brush 5. In such descaling, if a relation, t×R>=150, is maintained between the thickness t (μm) of the hot rolling scale and the draft R (%), descaling time is shortened in the subsequent acid cleaning. Successively, the hot rolled steel strip 1 is guided to a spray device 6 with the surface of the strip cleaned by spraying high pressure water from a spray nozzle 7, and then brought into an acid cleaning tank so that the scale remaining slightly on the surface is removed through the acid cleaning.
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