A flatness roller includes a body having at least one cavity opening onto an outer surface of the body through a plurality of slots, two successive slots defining a lamella between them, each lamella being connected to the body by two connection portions. The flatness roller also includes at least one optical fibre having at least one strain sensor having a measurement axis. Each strain sensor is housed in a cavity and attached at a connection portion of a lamella, the measurement axis forming an angle less than or equal to 20? with a plane orthogonal to the axis of revolution of the body. Each strain sensor is configured to send an optical response wave representative of a strain of the strain sensor according to the measurement axis thereof.

A flatness roller includes a body having at least one cavity opening onto an outer surface of the body through a plurality of slots, two successive slots defining a lamella between them, each lamella being connected to the body by two connection portions. The flatness roller also includes at least one optical fibre having at least one strain sensor having a measurement axis. Each strain sensor is housed in a cavity and attached at a connection portion of a lamella, the measurement axis forming an angle less than or equal to 20? with a plane orthogonal to the axis of revolution of the body. Each strain sensor is configured to send an optical response wave representative of a strain of the strain sensor according to the measurement axis thereof.

A rolling stand for rolling a hot aluminium strip, having at the outlet side, in this order, a trimming device that cuts the metal strip from both sides such that only the remaining central region of the metal strip is fed to the downstream devices; a front deflection roller that deflects the metal strip away from a direct connecting line between the rolling stand and the rear deflection roller; a measuring assembly that has a mechanical excitation device that excites the metal strip to mechanically oscillate in the direction of its thickness and a measuring device that senses, for a plurality of regions of the metal strip lying adjacent to one another in the direction of the width of the metal strip, the amplitude of the excited mechanical oscillation of the respective region; and a coiling device that has a rear deflection roller upstream of a coiler.

A rolling stand for rolling a hot aluminium strip, having at the outlet side, in this order, a trimming device that cuts the metal strip from both sides such that only the remaining central region of the metal strip is fed to the downstream devices; a front deflection roller that deflects the metal strip away from a direct connecting line between the rolling stand and the rear deflection roller; a measuring assembly that has a mechanical excitation device that excites the metal strip to mechanically oscillate in the direction of its thickness and a measuring device that senses, for a plurality of regions of the metal strip lying adjacent to one another in the direction of the width of the metal strip, the amplitude of the excited mechanical oscillation of the respective region; and a coiling device that has a rear deflection roller upstream of a coiler.

A method and apparatus for flatness measuring and measuring of residual stresses in a metallic flat product (1): The method includes bending the flat product (1) in a bending device (3) such that a planar flat product (1) forms an arc (5) with a target bending radius r.sub.0 after bending; measuring the contour and the actual bending radii r(y), in the region of the arc (5) of the bent flat product (1) at a plurality of positions along the width direction of the flat product (1); and determining the flatness of the flat product (1) taking into account the measured contour of the bent flat product (1).

A method and apparatus for flatness measuring and measuring of residual stresses in a metallic flat product (1): The method includes bending the flat product (1) in a bending device (3) such that a planar flat product (1) forms an arc (5) with a target bending radius r.sub.0 after bending; measuring the contour and the actual bending radii r(y), in the region of the arc (5) of the bent flat product (1) at a plurality of positions along the width direction of the flat product (1); and determining the flatness of the flat product (1) taking into account the measured contour of the bent flat product (1).

An arrangement for photographing a hot surface includes a camera arranged to take a number of successive images of the surface, whereby each image includes a part of the surface to be photographed. A light source is arranged to illuminate the surface to be photographed, whereby the camera and the light source are synchronized in such a way that the light source illuminates the surface at the shooting moment of each image, and an image-processing unit is arranged to combine a complete image of the whole surface to be photographed out of the successive images taken by the camera. A server is arranged to determine a coordinate system for the complete image, to receive data on the surface generated by one or more measuring devices, and to combine the received data with the complete image.

An arrangement for photographing a hot surface includes a camera arranged to take a number of successive images of the surface, whereby each image includes a part of the surface to be photographed. A light source is arranged to illuminate the surface to be photographed, whereby the camera and the light source are synchronized in such a way that the light source illuminates the surface at the shooting moment of each image, and an image-processing unit is arranged to combine a complete image of the whole surface to be photographed out of the successive images taken by the camera. A server is arranged to determine a coordinate system for the complete image, to receive data on the surface generated by one or more measuring devices, and to combine the received data with the complete image.

A method for improving the flatness of a rolled sheet or strip includes 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 method for improving the flatness of a rolled sheet or strip includes 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.