| 摘要 |
PURPOSE:To shorten the time required to treat a hot rolled steel sheet by placing an electrolytic apparatus in a pickling tank, measuring the temp. of the steel sheet at the inlet of a molten salt tank and controlling the current density in the electrolytic pickling apparatus according to the temp. CONSTITUTION:A hot rolled steel sheet fed from a payoff reel 1 is rapidly cooled from about 600 deg.C to about 200 deg.C in a cooling tank 2. At this time, the sensible heat of the steel sheet is absorbed in a molten salt in the tank 2 and recovered. The rapidly cooled steel sheet having scale is washed in a washing tank 3, mechanically descaled with a bender 4 and pickled by passing through a pickling tank 5. At the time, the current density in an electrolytic apparatus 8 is zero. The steel sheet is then washed in a washing tank 6 and coiled around a tension reel 7. The temp. of the hot rolled steel sheet is measured at a point A near the inlet of the washing tank 2 and an electric current setting unit 10 is operated by a controller according to the temp. signal to determine the quantity of electric current supplied to the electrolytic apparatus 8.
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