To restrain the flow-out of slag in a tundish into a mold to the min. limit by judging that the casting of molten steel in the tundish into the mold completes at the time when a value of the ratio of a lowering velocity of molten steel surface level in the mold and a casting velocity satisfies in a specific range.
During continuing the casting of the molten steel into the mold 9 after completing the pouring of the molten steel into the tundish 1 from the ladle, signals from a molten steel surface level meter 10 are sampled in a specified period into a molten steel surface level arithmetic device 11 to obtain the molten steel surface lowering quantity ΔX or the molten steel surface lowering velocity V in the mold. On the other hand, signals from a casting velocity meter 15 are suitably inputted into a casting completion judging arithmetic device 16 to judge the completion of casting. At the time when the ratio of the molten steel surface level lowering velocity V and the casting vecity V satisfies in the range of 0.15 to <1.0, it is judged that the casting of the molten steel in the tundish 1 into the mold 9 completes. Then, a stopper 2 is automatically closed with a stopper driving device 4 while outputting the alarming signal into an alarming device 18 from the casting completion output device 7.
HASHIMOTO YASUHIRO
NAKABASHI AKIRA
NARITA SHIN
TAKAHASHI NOBUHISA
NITTETSU HOKKAIDO CONTROL SYS