PURPOSE: To restrain variation of molten steel surface in a mold and development of surface defect in a cast slab by making the prescribed angles of the angles forming lower wall and upper wall with an axial line, respectively in discharging hole of a submerged nozzle so as not to develop reduced speed range in the discharged molten steel.
CONSTITUTION: Angle θ1 formed between the lower wall 26 and the perpendicular line 30 at the right angle to the axial line 28 of the submerged nozzle 18 in the discharging hole of the submerged nozzle 18 is made to 5W45°. Successively, angle θ2 formed between the upper wall 32 and the perpendicular line 30 at the right angle to the axial line 28 is made to 15W45°. By this method, the molten steel discharging flow rate from the discharging hole is made to averaging and the variation of the molten steel surface in the mold is stabilized and the surface defect of cast slab can be prevented.
KOIZUMI TSUGIO
ASAKURA KATSUHIRO
MORI TAKASHI
| JP58107253B |