| 摘要 |
PURPOSE:To decrease considerably the inclusion-type defects of an ingot by packing a packing consisting of a mixture composed of a specific flux and carbon grains or carbon fibers into the tap hole of a vessel prior to receiving of a steel, operating a sliding open/shut device to open the same so as to allow the packing to fall by gravity and tapping the molten steel. CONSTITUTION:The hole of a stationary plate 4a of the sliding open/shut device 4 provided to the bottom of a ladle 1 is made dissident with the holes of a sliding plate 4b and long nozzle 5, then the packing 3 consisting of the mixture composed of the low melting flux particles consisting of 20-70% CaO and 30-80% SiO2 as well as the carbon grains or carbon fibers is packed into the tap hole 2. The plate 4b and long nozzle 5 are slid in an arrow direction after receiving of the molten steel in the ladle 1 so that the position of said holes is made coincident with the hole of the stationary plate 4a. The molten metal falls therefore into a tundish 6 upon falling of the packing 3. The packing falling into the molten metal is melted immediately without being sintered and is separated and floated from the inside of the molten steel and therefore the packing does not intrude into a casting mold 8 by passing through an immersion nozzle 7 as in the conventional practice. The contamination of the molten metal is thereby thoroughly prevented. The inclusion-type defects of the ingot 9 are thus considerably decreased. |
