A method uses a device to level a metal plate fabricated from high-strength metal material. The method includes providing a serpentine path between a plurality of upper and lower rollers in parallel arrangement to define a longitudinal spacing. The upper and lower rollers are positioned relative to one another such that a plunge depth is defined based upon a difference between a top-dead-center point of the lower rollers and a bottom-dead-center point of contiguous upper rollers, and a longitudinal spacing and the plunge depth are configured such that the upper rollers and the lower rollers are disposed to impart a bend radius on the metal plate as the metal plate is drawn through the serpentine path such that the metal plate bends about the outer peripheral surfaces of the upper and lower rollers. The bend radius is selected to achieve a desired plastification of the metal sheet.

Systems and methods for improving the flatness of a rolled sheet or strip by the application of differential cooling. A cooling agent can be selectively applied along the width of the strip. More cooling can be applied to the edges of the strip, where tension is greatest, to increase tension at the edges. The strip can be allowed to lengthen at these edges, which can improve flatness. In some embodiments, a closed loop flatness control system is used to measure the flatness of a strip and automatically adjust the differential cooling based on the measurement.

A cut-to-length steel coil processing line has an un-coiling reel, a temper mill, a stretcher leveler, a shearer, and a stacking apparatus arranged to sequentially process a continuous length of sheet metal. The line may be configured such that the continuous length of the sheet metal is directed from the uncoiling reel through the temper mill to the stacking apparatus without processing through the stretcher leveler when a determined thickness of the continuous length of sheet metal is at or below a selected measurement criteria. In the alternative, the line may be configured such that the continuous length of the sheet metal is directed from the uncoiling reel through the stretcher leveler to the stacking apparatus without processing through the temper mill when the determined thickness of the continuous length of sheet metal is greater than the selected measurement criteria.

A metal strip is gripped by an upstream set of infeed tension rollers and, downstream therefrom in a strip-travel direction, by a downstream set of outfeed tension rollers. These tension rollers are rotated so as to tension the strip between the upstream and downstream sets and move the strip downstream in the strip-travel direction. Between the sets the strip first passes around individually supported relatively rotatable stretch rollers to increase a plastic stretch ratio of the strip, and then through a plurality of straightening rollers to reduce curvature and residual tension of the strip and also to increase the plastic stretch ratio of the strip.