To surely determine molten metal surface level in a mold, even in the case the characteristics of a mold copper plate and a thermocouple, etc., are not homogeneous.
When the molten metal surface level in the mold is determined with the thermocouple type level indicator 24 setting a plurality of thermocouples to the mold for casting, at the rising time of the molten metal surface, in the case the temperature variation ΔT per unit time exceeds a prescribed threshold value Ha and also, the difference between the temperature variation and an average value μ of the past measured temperatures exceeds an error range σ × Wa, it is determined that the molten metal surface level has reached the setting position of the thermocouple, based on the formulas ΔT≥Ha and T-μ≥σ×Wa (wherein, T: the measured temperature sampled with the attended thermocouple, σ: standard deviation in N samples at the latest casting and Wa: the detecting width for rising).
KIRITANI ATSUSHI
Keisuke Matsuyama
Tsuyoshi Makino