Flatness of a hot-rolled steel sheet in a coil is improved when the hot-rolled steel sheet is wound with a mandrel in a hot-rolling process to manufacture a coil. The mandrel has a protruding shape with a center portion in an axial direction protruding from both end portions when seen from a lateral side in the axial direction. Regarding a peripheral length difference, which is a difference between a peripheral length of the center portion of the mandrel and a peripheral length at a predetermined distance from the center portion, the ratio of the peripheral length difference to the peripheral length of the center portion is preferably 0.0002 to 0.012. The protruding shape may be a trapezoidal shape or a polynomial function shape.

Prior to the rolling of a flat rolling material (2) on a rolling line that includes a number of roll stands (1), a control system (3) receives actual variables (I) and target variables (Z) of the material (2). The control system (3) determines desired values (S*) for the roll stands (1), based on the actual (I) and target variables (Z) in combination with a model (10) of the rolling line, such that expected variables (E1) of the material (2) after its rolling are aligned as far as possible with the target variables (Z) and transfers the desired values (S*) to the roll stands (1) such that the material (2) is rolled according to the desired values (S*). The target variables (Z) comprise at least one freely selectable, discrete characteristic variable (K1 to K5, K2′ to K4′, K2″ to K4″) defining the contour (K) of the flat rolling material (2).

Prior to the rolling of a flat rolling material (2) on a rolling line that includes a number of roll stands (1), a control system (3) receives actual variables (I) and target variables (Z) of the material (2). The control system (3) determines desired values (S*) for the roll stands (1), based on the actual (I) and target variables (Z) in combination with a model (10) of the rolling line, such that expected variables (E1) of the material (2) after its rolling are aligned as far as possible with the target variables (Z) and transfers the desired values (S*) to the roll stands (1) such that the material (2) is rolled according to the desired values (S*). The target variables (Z) comprise at least one freely selectable, discrete characteristic variable (K1 to K5, K2′ to K4′, K2″ to K4″) defining the contour (K) of the flat rolling material (2).

A model (8) is based on mathematical-physical equations. The model models the production of a particular output product (1) from at least one input product (2) supplied in each case to an installation in the raw materials industry on the basis of operation (B) of the installation. During production of the output products (1), the installation is controlled by a control device (5) in such a manner that particular actual operation (B) of the installation corresponds as far as possible to particular desired operation (B*) of the installation. The desired operation (B*) is determined by the control device (5) using the model (8) of the installation. The model (8) is parameterized according to a number of first model parameters (P1) for the purpose of modelling the installation. After a multiplicity of output products (1) have been produced in each case, actual sizes (A) of the output products (1) in the particular multiplicity are compared with expected sizes (A′) of the output products (1) in the particular multiplicity. On the basis of the comparison, the first model parameters (P1) are newly determined and the model (8) in the control device (5) is newly parameterized according to the new values of the first model parameters (P1). After this time, the desired operation (B*) is determined by the control device (5) using the newly parameterized model (8) of the installation in the raw materials industry. The expected sizes (A′) are determined by means of the model (8), wherein the determination of the expected sizes (A′) is based on the actual operation (B) of the installation.

A model (8) is based on mathematical-physical equations. The model models the production of a particular output product (1) from at least one input product (2) supplied in each case to an installation in the raw materials industry on the basis of operation (B) of the installation. During production of the output products (1), the installation is controlled by a control device (5) in such a manner that particular actual operation (B) of the installation corresponds as far as possible to particular desired operation (B*) of the installation. The desired operation (B*) is determined by the control device (5) using the model (8) of the installation. The model (8) is parameterized according to a number of first model parameters (P1) for the purpose of modelling the installation. After a multiplicity of output products (1) have been produced in each case, actual sizes (A) of the output products (1) in the particular multiplicity are compared with expected sizes (A′) of the output products (1) in the particular multiplicity. On the basis of the comparison, the first model parameters (P1) are newly determined and the model (8) in the control device (5) is newly parameterized according to the new values of the first model parameters (P1). After this time, the desired operation (B*) is determined by the control device (5) using the newly parameterized model (8) of the installation in the raw materials industry. The expected sizes (A′) are determined by means of the model (8), wherein the determination of the expected sizes (A′) is based on the actual operation (B) of the installation.

A flatness measuring apparatus for measuring the flatness of a metallic strip, including a measuring roller which has a roller axis and which makes contact with the strip for the measuring the flatness. The measuring roller is connected to a cooling system, using which the measuring roller can be cooled. To ensure that a high degree of measuring accuracy can be maintained even at high temperatures, the cooling system has a nozzle bar that extends parallel to the roller axis. At least one spray nozzle is arranged on the nozzle bar, using which cooling medium can be sprayed on the surface of the measuring roller in a spraying direction. The spraying direction meets a surface section of the measuring roller, and the angle between the spraying direction and the tangent on the measuring roller at the location of the surface section is less than 30°.

A flatness measuring apparatus for measuring the flatness of a metallic strip, including a measuring roller which has a roller axis and which makes contact with the strip for the measuring the flatness. The measuring roller is connected to a cooling system, using which the measuring roller can be cooled. To ensure that a high degree of measuring accuracy can be maintained even at high temperatures, the cooling system has a nozzle bar that extends parallel to the roller axis. At least one spray nozzle is arranged on the nozzle bar, using which cooling medium can be sprayed on the surface of the measuring roller in a spraying direction. The spraying direction meets a surface section of the measuring roller, and the angle between the spraying direction and the tangent on the measuring roller at the location of the surface section is less than 30°.

A method of controlling flatness of a strip of rolled material in a production line including a hot rolling mill and at least one cold rolling mill, downstream of the hot rolling mill, the method including determining flatness data of the strip in one or more of the at least one cold rolling mill and/or following passing of the strip through one or more of the at least one cold rolling mill; determining a thickness profile target of the strip for the hot rolling mill based on the flatness data; and passing the strip through the hot rolling mill and adjusting the thickness of the strip based on the thickness profile target. A control system and a production line are also provided.

Rolling stock (2) composed of metal is rolled in rolling stands (3a to 3f) of a roll train (1) under the control of a control device. The control device, on the basis of a variable (δQ) (which is characteristic of the change in the cross section with which the rolling stock (2) is supposed to run out of a rolling stand (3e) of the roll train (1)), first determines all provisional manipulated variables (Sb to Se) for the rolling stand (3e) and rolling stands (3b to 3d) located upstream of the rolling stand (3e), and uses said provisional manipulated variables to determine final manipulated variables (Sb′ to Se′), which influence the cross section with which the rolling stock (2) runs out of the respective rolling stand (3b to 3e). The control device determines the provisional manipulated variables (Sb to Sd) for the upstream rolling stands (3b to 3d) by frequency filtering.

Rolling stock (2) composed of metal is rolled in rolling stands (3a to 3f) of a roll train (1) under the control of a control device. The control device, on the basis of a variable (δQ) (which is characteristic of the change in the cross section with which the rolling stock (2) is supposed to run out of a rolling stand (3e) of the roll train (1)), first determines all provisional manipulated variables (Sb to Se) for the rolling stand (3e) and rolling stands (3b to 3d) located upstream of the rolling stand (3e), and uses said provisional manipulated variables to determine final manipulated variables (Sb′ to Se′), which influence the cross section with which the rolling stock (2) runs out of the respective rolling stand (3b to 3e). The control device determines the provisional manipulated variables (Sb to Sd) for the upstream rolling stands (3b to 3d) by frequency filtering.