PURPOSE: To improve cooling ability of a core, and quality and productivity of a hollow steel ingot by inserting a partition tube between the compulsory cooling core and a mold placed on a bottom plate and ascending the partition tube together with ascending a bottom pouring molten steel surface covered by covering material.
CONSTITUTION: The circular core 14, which is cooled compulsorily by injecting high pressure air or high pressure air with water from nozzles 20, and the mold 12 are placed on the bottom pouring bottom plate 4. The partition tube 30 having larger diameter than the outer diameter of the core 14 is inserted to the surface of the bottom plate 4. The surface covering material 28 is charged on the bottom pouring molten steel surface between the partition tube 30 and the mold 12, to prevent the surface oxidation. By ascending the partition tube 30 together with ascending the molten steel surface, the cooling ability of the core 14 is promoted, because of no contact of the covering material 28 with the outer face of the core 14, and the pouring molten steel 24 is solidified 26 as uniform at the inner and outer faces, and so, the V segregation is decreased and the quality is improved and also the productivity is improved. Further, as a generated vapor is introduced to outside by the partition tube 30, danger vapor explosion does not happen.
MATSUKAWA TOSHITANE
AIZAWA KANJI
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