JPS57192216A - Heating method of steel material - Google Patents

Abstract

PURPOSE:To save a fuel consumption amount in a heating oven, by heating the detected locally low-temperature part of a steel material, being carried, discharged from the heating oven. CONSTITUTION:A steel material 5, discharged from a heating oven 1 and carried between mills 3 and 4, is heated with a heater A, and a temperature especially at its lower side is detected 9. When a skid mark part S1 having a temperature lower by 50 deg.C or so than that of the other detected part passes through a detector 9, its temperature signal and these temperature difference signal are introduced into a controller 10. At this time, the rolling speed of the steel material 5 is detected 8, and its signal is inputted in company with a roll size signal into the controller 10. In the controller 10, the first triac 151 is driven to actuate a coil 7 on the basis of these signals, when the skid mark part S1 reaches a position above the first heating coil 7. At the same time, an output control signal from a high-frequency generating circuit 14 is outputted by the temperature difference signal. With the movement of the skid mark part S1, the heating position and the heating depth by the heating coils 73, 74... are successively changed, so that the part is controlled at the same temperature as that at the other part. The same control is done to the following skid mark part S2, too.