Digital flow regulation of liquid-level control for a continuous casting mold
AssigneeUnited States Steel Corporation
InventorsChester C. Mazur, James H. Wilson
Life of this patent
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Abstract
In a continuous casting apparatus, the level of liquid in the mold is monitored and compared to a desired reference level. A microcomputer examines the resulting error signal and determines the amount of movement of the valve which would be appropriate to correct the detected error. A control pulse is then generated having a duration corresponding to the desired movement distance, and the valve is adjusted accordingly.
Claims7
In a continuous casting apparatus of the type wherein liquid metal is supplied from a liquid reservoir to a mold through a valve mechanism, said valve mechanism having a movable valve member the position of which determines the rate at which said liquid is supplied to said mold, detection means for detecting the level of liquid in said mold, comparison means for comparing the detected liquid level with a desired level to generate an error signal, control signal generating means for generating a control signal in response to said error signal and control means for moving said valve member in response to said control signal, said control signal generating means comprising:
- first means responsive to said error signal for generating a first signal corresponding to a desired change in the position of said valve member, said first means comprising means for receiving a sequence of said error signals and for calculating a value FO according to:
- FO=KG[(E1-E2)+KI(E1)+KD(E1-2E2+E3)]
- where E1, E2 and E3 are consecutive error signals and KG, KI and KD are predetermined constants;
- and
- second means responsive to the value of said first signal for generating said control signal having a duration corresponding to said first signal.
In a device of the type wherein a liquid is supplied from a liquid supply to a liquid container through a valve mechanism having a movable valve member the position of which determines the rate at which said liquid is supplied to said container, a method of controlling the level of liquid in said container, said method comprising the steps of:
- detecting the level of said liquid in said container;
- generating an error signal corresponding to the difference between the detected liquid level and a reference level;
- calculating a first signal corresponding to a desired change in the position of said valve member, including the step of calculating a value FO according to the following equation:
- FO=KG[(E1-E2)+KI(E1)+KD(E1-2E2+E3)]
- where E1, E2 and E3 are consecutive error signals corresponding to the difference between the detected liquid level and said reference level and KG, KI and KD are predetermined constants;
- generating a control signal having a duration corresponding to the value of said first signal;
- and
- moving said valve member by an amount proportional to the duration of said control signal.
Dependencies are inferred from the claim text.