| 摘要 |
<p>PURPOSE:To easily control the temp. of a steel sheet to a desired value and to readily produce a high-quality annealed steel sheet by applying an induction heating system to the high-temp. part of an annealing furnace and a direct-fired reduction heating system to the low-temp. part, and controlling the current of the induction heating system at the time of continuously annealing a steel sheet. CONSTITUTION:When a steel sheet S is continuously annealed, the sheet S is firstly introduced into the direct-fired reduction heating zone through many hearth rolls 4, and directly heated to 600-700 deg.C by the reducing flame from many burners 2a wherein the fuel is burned at the air-to-fuel ratio of <=1.0. The temp. of the sheet S leaving the reduction heating zone is measured by a plate thermometer 3c provided at the inlet of the induction heating zone, the data are inputted to a temp. controller 3e and compared with a heat pattern, and the measured value by a plate thermometer at the outlet of the induction heating zone is also inputted to the temp. controller 3e and compared with the set heat pattern. As a result, a current source 3b to be supplied to an inductor 3a in the induction heating zone is controlled, hence an appropriate current is supplied to the inductor in the induction heating zone, and the sheet S is heated to an appropriate temp. of >=800 deg.C and annealed.</p> |
