Control method for continuous casting machine, control device for continuous casting machine, and manufacturing method for casting

A control device for a continuous casting machine, comprising a processor comprising hardware, the processor being configured to:

• estimate, by an on-line real-time system, a flow state of molten steel in a mold by using:
• an operation condition of a continuous casting machine, and
• temperature data on the molten steel in the mold;
• calculate, by the on-line real-time system, at least one molten steel flow index based on the estimated flow state of the molten steel, the at least one molten steel flow index being a factor of mixing of an impurity into a casting inside the mold;
• and
• control the operation condition of the continuous casting machine such that the at least one calculated molten steel flow index is within an appropriate range,
• wherein the at least one molten steel flow index includes a maximum value of molten steel surface flow velocities in the mold, an area of a region where a solidification interface flow velocity is equal to or less than a predetermined value, and a maximum value of a molten steel surface turbulence energy, and
• the maximum value of the molten steel surface turbulence energy is calculated according to formulas (I) and (II) below:
• k=(½)·Ui2 (I)
• U=Uave+Ui (II)
• where k is turbulence energy, U is an instantaneous value of a flow velocity of a fluid in a spatial position, Uave is a time average value of the flow velocity of the fluid in the spatial position, and Ui is a deviation from a time average value of the flow velocity of the fluid in the spatial position.

A manufacturing method for a casting, comprising producing a casting while controlling a continuous casting machine by using a control method for the continuous casting machine, including:

• estimating, by an on-line real-time system, a flow state of molten steel in a mold by using:
• an operation condition of a continuous casting machine, and
• temperature data on the molten steel in the mold;
• calculating, by the on-line real-time system, at least one molten steel flow index based on the estimated flow state of the molten steel, the at least one molten steel flow index being a factor of mixing of an impurity into a casting inside the mold;
• and
• controlling the operation condition of the continuous casting machine such that the at least one calculated molten steel flow index is within an appropriate range,
• wherein the at least one molten steel flow index includes a maximum value of molten steel surface flow velocities in the mold, an area of a region where a solidification interface flow velocity is equal to or less than a predetermined value, and a maximum value of a molten steel surface turbulence energy, and
• the maximum value of the molten steel surface turbulence energy is calculated according to formulas (I) and (II) below:
• k=(½)·Ui2 (I)
• U=Uave+Ui (II)
• where k is turbulence energy, U is an instantaneous value of a flow velocity of a fluid in a spatial position, Uave is a time average value of the flow velocity of the fluid in the spatial position, and Ui is a deviation from a time average value of the flow velocity of the fluid in the spatial position.