楕円断面を有する浸漬ノズルによるモールドパウダー巻き込み抑制

抄録

Mold powder descends along the surface of the immersion nozzle due to pressure difference around the nozzle when an uneven molten steel flow suddenly crosses the nozzle. If the descending mold powder arrives at the port of the immersion nozzle, it is torn off to many small particles by the discharging molten steel and carried deep into the mold. This type of mold powder entrapment can be suppressed by decreasing the pressure difference around the nozzle. In this study, an immersion nozzle with elliptic cross section was chosen, and cold model experiments were carried out using salt water and silicone oil as the working fluids. The descending distance of the silicone oil simulating mold powder was smaller along the elliptic cylinder than along a circular cylinder. As the ratio of the minor axis to the major axis of the elliptic cylinder became smaller, the descent of the silicone oil was more effectively suppressed. The effect of the wettability of the elliptic cylinder on the descent of the silicone oil was also investigated. Poor wettability promoted the descent of silicone oil significantly.