| 摘要 |
PURPOSE:To enable a natural opening by an inexpensive fuming stock by passing the generated gas caused by the roast of a fuming stock through the inside of the sintered layer of a silica sand. CONSTITUTION:The fuming material 4 of a sawdust, wooden piece, etc., formed in a sand packed silica sand 2 is filled into a pouring nozzle hole 1. By doing so a gas is generated with the fuming material 4 being roasted by the heat of a molten steel when the molten steel is received in the ladle. The generated gas comes to a sintered layer 5 by having some pressure, forming a crack or multiple aperture on the sintered layer 5 and discharging it into the molten steel. The sintered layer 5 is easily destroyed by the static pressure of the molten steel because it becomes thin and porous or cracked. Consequently the natural opening is enabled. |
