Abstract: With a view to adding, to an upper nozzle formed with a bore having a shape capable of creating a less energy loss or smooth (constant) molten steel flow to suppress the occurrence of adhesion of inclusions and metals in molten steel, a gas injection function to thereby further suppress the occurrence of the adhesion, the present invention provides a method of using an upper nozzle configured to have a cross-sectional shape of a wall surface defining the bore, taken along an axis of the bore, comprising a curve represented by the following formula: log(r (z))=(1/n)×log((H+L)/(H+z))+log(r (L)) (n=1.5 to 6), where: L is a length of the upper nozzle; H is a calculational hydrostatic head height; and r (z) is an inner radius of the bore at a position downwardly away from an upper edge of the bore by a distance z. The method comprises using the upper nozzle in such a manner as to satisfy the following relationship: RG?4.

Abstract: With a view to adding, to an upper nozzle formed with a bore having a shape capable of creating a less energy loss or smooth (constant) molten steel flow to suppress the occurrence of adhesion of inclusions and metals in molten steel, a gas injection function to thereby further suppress the occurrence of the adhesion, the present invention provides a method of using an upper nozzle configured to have a cross-sectional shape of a wall surface defining the bore, taken along an axis of the bore, comprising a curve represented by the following formula: log(r (z))=(1/n)×log((H+L)/(H+z))+log(r (L)) (n=1.5 to 6), where: L is a length of the upper nozzle; H is a calculational hydrostatic head height; and r (z) is an inner radius of the bore at a position downwardly away from an upper edge of the bore by a distance z. The method comprises using the upper nozzle in such a manner as to satisfy the following relationship: RG?4.

Abstract: Disclosed is a sliding nozzle plate (composite sliding nozzle plate) (2) for use in a sliding nozzle device for adjusting an outflow amount of molten metal from a molten metal vessel. The sliding nozzle plate (2) comprises a sliding nozzle plate body and a tubular member (3) formed with a flange (3a) and attached to a bore (through-hole (1c?)) of the sliding nozzle plate body, and satisfies the following conditional formulas (1) and (2): ?B??I?5??(1); and ?B??R?4??(2), where: ?B is a diameter (mm) of the bore of the sliding nozzle plate body; ?I is an outer diameter (mm) of the flange of the tubular member; and ?R is an outer diameter (mm) of the non-flange portion of the tubular member. The composite sliding nozzle plate is capable of preventing displacement of the tubular member and molten metal penetration into a joint between the tubular member and the sliding nozzle plate body.