Automatic molten metal surface level control system for continuous casting machines

In a continuous casting machine for producing ingots having a predetermined sectional area in which molten metal is continuously fed into a molten metal reservoir at a predetermined feed rate and said molten metal in said reservoir is poured into a continuous casting mold through a gate in said reservoir, said reservoir having an aperture that is adjustable under the control of an electric control mechanism, an automatic molten metal surface level control system for the continuous casting machine comprising:

• upper and lower electric level detecting means that detect that the molten metal surface in said casting mold has reached an upper command limit level or a lower command limit level, and a middle command level between said upper and lower limit levels, each of said upper and lower limit levels having a vertical command deviation from said middle command level;
• and, a signal generator, coupled to said level detecting means to generate controlling pulses having a predetermined pattern so arranged that when said molten metal surface has reached said upper command limit level the aperture of said gate is first brought to a substantially fully-closed position for a moment's time so as to bring down said molten metal surface to about said middle command level and then said gate is opened to a position that is closed slightly more from the initial aperture before the foregoing control operation, and, when said molten metal surface has reached said lower command limit level, the aperture of said gate is first brought to almost a fully-opened position so as to bring said molten metal surface up to about said middle command level and then, said gate is partially closed to the extent that it is slightly more closed than before the foregoing controlling operation.