A determination apparatus of a casting state in continuous casting where there are a solidified shell, a mold flux layer, and a mold being respective thermal conductors between a molten steel and cooling water for the mold, the determination apparatus comprising an estimation unit, a calculation unit, and a determination unit. A computer program for causing a computer to determine a casting state in continuous casting where there are a solidified shell, a mold flux layer, and a mold being respective thermal conductors between a molten steel and cooling water for the mold.

A heat transfer coefficient between a solidified shell (2) and a mold (4) sandwiching a mold flux layer (3), and a heat transfer coefficient between a molten steel (1) and the solidified shell (2) are found by solving an inverse problem by using data from thermocouples (6), and a solidified shell thickness and a solidified shell temperature are estimated (solidified state in mold estimation amounts), and further, solidified state in mold evaluation amounts are obtained. It is determined whether a normal casting state or an abnormal casting state by comparing at least one or more kinds of amounts contained in the solidified state in mold estimation amounts and the solidified state in mold evaluation amounts with allowable limit values which are found based on at least one or more kinds of amounts contained in the solidified state in mold estimation amounts and the solidified state in mold evaluation amounts when the abnormal casting occurred in a past and stored in a data storage part.

This disclosure concerns methods and apparatus for continuously casting thin strip where one or more expansion rings are positioned within at least one of a pair of casting rolls, and automatically measuring a thickness of the cast strip close to the first side edge of the strip using at least one sensor, and if the thickness measured is too thin, automatically decreasing the radial dimension of the expansion ring arranged in close proximity to the first side edge to cause the cylindrical tube to contract and increase the thickness of the cast strip during casting, and if the thickness measured indicates that the thickness of the cast strip is too thick, automatically increasing the radial dimension of the expansion ring arranged in close proximity to the first side edge to cause the cylindrical tube to expand and reduce the thickness of the cast strip during casting.

A twin roll casting system includes a pair of counter-rotating casting rolls having an adjustable nip therebetween, a casting roll controller configured to adjust the nip between the casting rolls in response to control signals; a cast strip sensor measuring a parameter of the cast strip and generating strip measurement signals; and an iterative learning control (ILC) controller receiving the strip measurement signals and providing control signals to the casting roll controller. The ILC controller includes a fault detection algorithm receiving the control signals and the strip measurement signals and generating a fault detection signal indicating when a fault condition is detected and an iterative learning control algorithm to generate the control signals. The fault detection algorithm indicates a fault condition when it detects the control signal exceeding an upper control saturation threshold or the ILC controller operating a state that is not guaranteed as stable.

A pulling-up-type continuous casting apparatus includes a holding furnace that holds molten metal, a shape defining member disposed above a surface of the molten metal held in the holding furnace, and configured to define a cross-sectional shape of a cast-metal article as the molten metal passes through it, an image pickup unit that takes an image of the molten metal that has passed through the shape defining member, an image analysis unit that detects a fluctuation on the molten metal from the image and determines a solidification interface based on presence/absence of the fluctuation, and a casting control unit that changes a casting condition only when the solidification interface determined by the image analysis unit is not within a predetermined reference range. The casting control unit uses a reference range which differs according to the pulling-up angle of the molten metal.

A pulling-up-type continuous casting apparatus according to an aspect of the present invention includes a holding furnace that holds molten metal, and a shape defining member disposed above a molten-metal surface of the molten metal held in the holding furnace, the shape defining member being configured to define a cross-sectional shape of a cast-metal article to be cast as molten metal passes through an opening formed in the shape defining member. The opening is formed in such a manner that a size of the opening on a top surface of the shape defining member is larger than that on a bottom surface of the shape defining member. With this configuration, a cast-metal article having excellent surface quality can be produced even when molten metal is drawn up in an oblique direction.