A plate thickness control device controlling plate thickness of a hot rolling mill that includes a rolling stand. The plate thickness control device includes: a pyrometer disposed on an entry side of the rolling stand; a difference calculation part that outputs a difference temperature between a lock-on temperature of the plate-to-be-rolled measured by the pyrometer and a measurement value of a portion other than a tip portion of the plate-to-be-rolled measured by the pyrometer; a tracking part that transfers the difference temperature from the position of the pyrometer to immediately below the rolling stand based on plate speed of the plate-to-be-rolled; and a computation part that calculates a screw-down amount of the rolling stand based on the difference temperature transmitted from the tracking part.

Methods and apparatus for locally changing a roll gap in the region of the strip edges (10) of a rolled strip (1) in a rolling stand (2). The roll gap can be changed locally in the region of the strip edges (10) of the strip (1) during the hot rolling. Axial displacement of the working rollers (3, 4) in opposite directions is by a displacement distance s, where s is greater than or less than Δr/tan(α) and Δr indicates the wear of the running surface (8) in the radial direction (R) and α indicates the pitch angle of the conical portion (7) of the respective working roller (3, 4).

Methods and apparatus for locally changing a roll gap in the region of the strip edges (10) of a rolled strip (1) in a rolling stand (2). The roll gap can be changed locally in the region of the strip edges (10) of the strip (1) during the hot rolling. Axial displacement of the working rollers (3, 4) in opposite directions is by a displacement distance s, where s is greater than or less than Δr/tan(α) and Δr indicates the wear of the running surface (8) in the radial direction (R) and α indicates the pitch angle of the conical portion (7) of the respective working roller (3, 4).

A method ascertains control variables for active profile and flatness control elements for at least one rolling stand for hot rolling metal strip with a plurality of i=1 . . . I successive passes and for ascertaining profile and center flatness values for the hot-rolled metal strip. The occurrence of fluctuations in the center flatness of the metal strip after the individual passes and the resulting disadvantages for the rolling stability and the product quality are prevented. The method provides that, also for the target center flatness of the metal strip after a predetermined pass k with i=1 . . . <k< . . . I and for the target center flatness after the subsequent passes, pass-specific interval ranges are also specified in each case, and in that the successive calculation of the control variables and profile values is then carried out taking into account such additional specifications as well.

A method ascertains control variables for active profile and flatness control elements for at least one rolling stand for hot rolling metal strip with a plurality of i=1 . . . I successive passes and for ascertaining profile and center flatness values for the hot-rolled metal strip. The occurrence of fluctuations in the center flatness of the metal strip after the individual passes and the resulting disadvantages for the rolling stability and the product quality are prevented. The method provides that, also for the target center flatness of the metal strip after a predetermined pass k with i=1 . . . <k< . . . I and for the target center flatness after the subsequent passes, pass-specific interval ranges are also specified in each case, and in that the successive calculation of the control variables and profile values is then carried out taking into account such additional specifications as well.

A combined continuous casting and endless rolling plant for a metal strip, comprising—a continuous casting line (1) for casting a slab; —a first rolling mill (6) for roughing the slab and for obtaining a transfer bar; —a second rolling mill (11) for finishing the transfer bar and for obtaining a strip; —a third rolling mill (18), comprising at least two rolling stands (17), for further reducing the N thickness of the strip; —accumulation means (20) of the strip comprising at least one first reel (37, 37′) dimensioned to wind and unwind a coil weighing from 80 to 250 metric tons and/or up to 6 meters in diameter, named mega coil; —first cutting means (13), arranged between said third rolling mill (18) and said accumulation means (20), configured to cut the strip after the mega coil has been wound on the at least one first reel (37, 37′); —at least one second reel (48) for winding portions of strip, unwound from said accumulation means (20), up to a predetermined weight limit or coil diameter limit; —second cutting means (47), arranged between said accumulation means (20) and said at least one second reel (48), adapted to cut the strip whenever a portion of strip wound on the at least one second reel (48) reaches said predetermined weight limit or coil diameter limit.

A combined continuous casting and endless rolling plant for a metal strip, comprising—a continuous casting line (1) for casting a slab; —a first rolling mill (6) for roughing the slab and for obtaining a transfer bar; —a second rolling mill (11) for finishing the transfer bar and for obtaining a strip; —a third rolling mill (18), comprising at least two rolling stands (17), for further reducing the N thickness of the strip; —accumulation means (20) of the strip comprising at least one first reel (37, 37′) dimensioned to wind and unwind a coil weighing from 80 to 250 metric tons and/or up to 6 meters in diameter, named mega coil; —first cutting means (13), arranged between said third rolling mill (18) and said accumulation means (20), configured to cut the strip after the mega coil has been wound on the at least one first reel (37, 37′); —at least one second reel (48) for winding portions of strip, unwound from said accumulation means (20), up to a predetermined weight limit or coil diameter limit; —second cutting means (47), arranged between said accumulation means (20) and said at least one second reel (48), adapted to cut the strip whenever a portion of strip wound on the at least one second reel (48) reaches said predetermined weight limit or coil diameter limit.

A method for collecting mill scale from a hot rolling mill is provided. The hot rolling mill includes a flume. The method includes transporting mill scale particles in wastewater, retrieving the wastewater from a flume of the hot rolling mill and separating the mill scale particles from the wastewater using a separator. A hot rolling mill and a method for retrofitting a hot rolling mill are also provided.

A method for collecting mill scale from a hot rolling mill is provided. The hot rolling mill includes a flume. The method includes transporting mill scale particles in wastewater, retrieving the wastewater from a flume of the hot rolling mill and separating the mill scale particles from the wastewater using a separator. A hot rolling mill and a method for retrofitting a hot rolling mill are also provided.

A production equipment line for a hot-rolled steel strip comprises a rough rolling mill comprising rough rolling mills for hot rolling a material, which is heated to a predetermined temperature to a finish rolling start sheet thickness and a finish rolling mill comprising finish rolling mills for controlled-rolling the material to a final sheet thickness. At least one of the rough rolling mills is a reversible rolling mill. The production equipment line is provided on an upstream side of the reversible rolling mill with one of a slow cooling apparatus for slowly cooling at a water volume density of less than 1000 L/min.Math.m.sup.2 and a rapid cooling apparatus for rapidly cooling after the slow-cooling at a water volume density of not less than 1000 L/min.Math.m.sup.2 and the other of the slow cooling apparatus and rapid cooling apparatus on a downstream side of the reversible rolling mill.