PURPOSE: To smoothly start casting and improve the yield of cast slab by adjusting an inside pressure of immersion nozzle descending in metal pool before start of pouring of a molten steel for inner layer.
CONSTITUTION: The immersion nozzle 4 is filled with an inactive gas of argon, etc., through the hole 13 pierced from stopper's upper end to lower end arranged in the center axis part of the stopper 10b of the tundish 6, successively, the nozzle 4 is descended to be immersed in the molten pool inside the mold 1 without pouring the molten steel 18 into pool. At this time, the molten steel level 19 in the nozzle 4 is adjusted to the same level as that of molten steel in the mold 1. Thus, after the tip of the nozzle 4 for inner layer passes by direct current electromagnetic zone, the stopper 10b is opened and the molten steel 18 is introduced into the nozzle 4. Consequently, gas or air is not shut in the nozzle 4, as soon as the nozzle 4 is arranged at the prescribed position, production can be started.
SEZE AKIFUMI
SAWAI TAKASHI
