PURPOSE: To decrease considerably porosity and segregation in a large sized steel ingot by closing the rising runner between upper and lower molding boards after charging a molten steel into a casting mold and lifting the casting mold and spraying water to the bottom of the casting ingot after the solidified shell capable of supporting the static pressure of the molten steel is formed in the bottom of the mold.
CONSTITUTION: A casting mold 2 is set on an upper molding board 4 placed via a spacer 30 on a lower molding board 16, and when the preparation for charging a molten steel 8 is completed, the molten steel 8 in a conveyed ladle 6 is charged into the mold. The steel 8 is charged through a runner 18 embedded in the board 16, a runner hole 34 of the intermediate plate between a rising runner and a device 32 for closing the runner, and a rising runner 20 of the board 4 into the mold 2. A heat insulating material 24 is charged onto the molten metal surface. The intermediate plate of the device 32 is moved to close the runner 20 upon completion of the charging. The steel 8 in the mold 2 begins to solidify from the part in contact with the board 4 and the inside wall of the casting mold thereby forming a solidified shell 42. When the shell 42 grows to the substantial thickness to withstand the static pressure of the unsolidified steel in the mold 2, the mold 2 is moved upward by a jack 28 and cooling water 40 is sprayed from plural holes of a conduit 38 to the exposed bottom of the steel ingot so that the molten steel in the mold 2 is thoroughly solidified.
KATOU TOSHIO
NAKANISHI KIYOUJI
KOJIMA SHINJI
YAO SHIYOU
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