Monitoring the planarity of metal sheet
AssigneeCentre de Recherches Metallurgiques-Centrum voor Research in de Metallurgie
InventorRobert A. Pirlet
Life of this patent
Estimating the term…
Abstract
Optical beams from lasers are directed towards the middle and edges of a hot rolled steel sheet by fixed mirrors and rotatable mirrors which allow for different sheet widths. The points of incidence of the beams are observed by photodiode cameras whose receiving axes are orientated by fixed mirrors and rotatable mirrors so that the points remain in the respective fields of observation of the cameras. The levels of the points are obtained by triangulation and are used in the calculation of the planarity of the sheet.
Claims18
In a method of monitoring the flatness of a substantially horizontal metal strip running longitudinally on a strip support means having a longitudinal median axis, by transmitting a plurality of optical beams emitted by a plurality of light sources, directing said optical beams toward the strip from above so that they strike the strip at a plurality of points spaced across the width of the strip, receiving the optical beams reflected from the strip on a plurality of corresponding receivers each paired with a light source, and calculating the level of said points and determining therefrom a flatness index of the strip, the improvement comprising:
- locating at least two of said light sources symmetrically to each other with respect to a vertical plane containing said longitudinal median axis;
- locating said receivers paired with said at least two light sources symmetrically to each other, with respect to said vertical plane containing said longitudinal median axis;
- orientating the optical beams emitted by said at least two light sources in such a manner that they form an identical angle with the said vertical plane and strike the strip surface at points that are located symmetrically to each other with respect to said longitudinal median axis;
- orientating the optical axes of said receivers, located symmetrically to each other with respect to said vertical plane, so that the angles formed by each of said optical axes with the axis of the optical beam emitted by the paired light source are all equal;
- and
- intercepting at least two of said optical beams from said light sources by means of a single common deflector orientatable about an axis of rotation and directing said intercepted optical beams to two points both located on the same side of the strip.
In an apparatus for monitoring the flatness of a substantially horizontal metal strip running longitudinally on a strip support means having a longitudinal median axis, wherein said support means defines a substantially horizontal path for the strip, said apparatus comprising transmitters arranged to produce optical beams generally directed towards the strip and receivers for receiving the optical beams reflected by the strip, the improvement comprising:
- at least two transmitters located symmetrically to each other with respect to a vertical plane containing said longitudinal median axis;
- receivers paired with said at least two transmitters located symmetrically to each other with respect to said vertical plane;
- orientatable first deflectors arranged to intercept the optical beams for orientating the optical beams produced by said transmitters, one of said first deflectors being orientatable about an axis of rotation and arranged to intercept more than one of said optical beams produced by said transmitters;
- and
- orientatable second deflectors to direct the optical axes of said receivers for orientating the optical axes of said receivers.
Dependencies are inferred from the claim text.