To detect the reaching timing of molten metal surface to a desired prescribed height position of a molten metal tube under the state in which the trouble of maintenance can be reduced and such fear as overflow of the molten metal is avoided.
In the molten surface reaching timing detecting instrument for detecting the reaching timing when the surface K of the molten metal D flowing into the molten metal tube portion 29 arranged along the vertical direction from the lower part reaches the prescribed height position P in the molten metal tube portion, a position corresponding to the prescribed height position of the molten metal tube portion 29 is inserted through the inside of a solenoid coil 31, and impedance change or inductance change or current change or voltage change or power factor change of the solenoid coil according as the molten metal surface reaches the prescribed height position is measured and this instrument is constituted so as to detect the reaching timing based on this measured result.
UMITACHI NOBUAKI
YAMAGUCHI HIROSHI
NAKAGAWA KENICHI
