PURPOSE: To lower the heating temperature of a soaking pit to the lowest temperature region, by installing an electrical induction heater for heating a semifinished produce between a roughing mill and a finishing mill, and by reheating only a temperature lowered part of the semifinished product.
CONSTITUTION: A cast ingot, heated by a soaking pit to ≥1,150°C, is processed successively by a roughing mill, a hot scarfer, and a shearing machine; thus prepared semifinished product 10 is heated by an electrical induction heater 5 to about 950W1,050°C, and is then fed to a finishing mill. In case of manufacturing a square billet, for example, the induction heater 5 comprises a hollow square cylinder- shaped electrical insulating material 13, a spiral coil 12 internally set in the insulating material 13, and a hollow refractory 14 for protecting the insulating material 13 from the external heat; the semifinished product 10 is carried by a table roller 11 and is passed within the hollow refractory 14 while keeping a prescribed clearance 15. By the present method, the scale loss of the material is about 40% reduced from that in the conventional method, and the unit consumption of total energy is about 30% reduced.
KUDOU TAKAYUKI
KITAMURA ETSUO
IWAHASHI TSUKIO
MORIMOTO YOSHIHISA
