PURPOSE: To let the thrust force of an electromagnetic pump always balance with the static pressure of molten metal and check the same and make the time required for tapping constant by detecting the molten metal level in a vessel.
CONSTITUTION: When the molten metal level in a vessel 1 is maximum, the output of a load cell 4 becomes maximum as well and the output of a check voltage setting function generator 9 becomes maximum as well. As a result, an electromagnetic pump 3 prevents the effluence of molten metal by overcoming the static pressure of the molten metal level owing to the action of an absolute value circuit 11. Next, when the level of the molten metal decreases, the output of the load cell 4 decreases as well and the output of the foregoing function generator 9 decreases as well. The output of the absolute value circuit 11 then decreases, resulting in the decreased check thrust of the electromagnetic pump 3. Hence, the check thrust of the electromagnetic pump 3 is balanced with the static pressure accompanying the molten metal level, whereby reverse flow is prevented. At the same time the prevention of reverse flowing is also accomplished by keeping the molten metal amount in the electromagnetic pump 3 always constant and therefore the time for the molten metal to begin to come out is made always constant at the pouring.
SHIGIHARA SHIGEYUKI
MAENOU SATORU
II TAKESHI
