PURPOSE: To prevent the development of thickness deviation of a hollow billet by setting lower end of lower face in an inclined mold so as to become lower than the lower end of upper face by the specific distance and forming solidified shell with the mold and secondary cooling device.
CONSTITUTION: In the inclined mold 4 having inclined angle θ, the lower end part of the lower face in the mold 4 is set so as to become lower than the lower end part of the upper face by the distance (m) (mm) showed in the inequality I. Molten steel 2 is poured into a tundish 3 from a ladle 1 and cast with static pressure of the molten steel from the lower part of the inclined mold 4 through the molten steel introducing part 14. Then, as the lower end of the lower face in inner face of the mold is set to lower than the lower end of the upper face in the mold 4 by the distance (m) to perpendicular direction, the molten steel 2 is cooled with interval of the same length (l) at the upper face together with the lower face. Therefore, the thickness of the solidified billet 5 at the upper end and the lower end are equalized and the development of the thickness deviation in the hollow billet 7 successively formed upward is prevented.
NAGANO YUTAKA
TAKEUCHI EIICHI
