Method and control device for operating a mill train for metal strip

Abstract

The invention relates to a method and a control device for operating a mill train for metal strip, which comprises at least one roll stand, the intrinsic flatness of the metal strip being determined at the discharge point of the mill train. In order to ensure in a reliable and sufficiently accurate manner that a required visible flatness of the rolled metal strip is kept within predefined limits, the bulging behavior of the metal strip is measured at the discharge point of the mill train and is translated into the intrinsic flatness of thermal strip by means of a bulging model. The visible flatness can thus be better regulated online along the entire mill train by using the bulging mode.

1 - 14 . (canceled)  
   
   
       15 . A method for operating a metal strip mill train, comprising: 
 determining a desired flatness of the strip via a material flow model;    measuring an actual flatness of the metal strip near a discharge point of the mill train;    translating the measured metal strip flatness into flatness values;    controlling a roll stand of the mill train via a bulge model that uses the desired and actual flatness values as inputs to reduce the difference between the actual flatness and the desired flatness of the metal strip.    
   
   
       16 . The method as claimed in  claim 15 , wherein the actual flatness of the metal strip is measured at the discharge point of the mill train.  
   
   
       17 . The method as claimed in  claim 15 , wherein the actual flatness is determined as a bulge pattern.  
   
   
       18 . The method as claimed in  claim 17 , wherein the bulge pattern is three-dimensional.  
   
   
       19 . The method as claimed in  claim 18 , wherein a relative length of individual tracks of the metal strip is evaluated to determine the bulge pattern along with a variable of the individual tracks selected from the group consisting of: wavelength, amplitude and phase offset.  
   
   
       20 . The method as claimed in  claim 19 , wherein a laser measuring device is used to determine the desired flatness of the metal strip.  
   
   
       21 . The method as claimed in  claim 20 , wherein the laser measuring device is a multi-track laser measuring device.  
   
   
       22 . The method as claimed in  claim 20 , wherein the actual flatness of the metal strip is measured topometrically.  
   
   
       23 . The method as claimed in  claim 22 , wherein the values for the desired flatness are translated into values for the actual flatness using the bulge model.  
   
   
       24 . The method as claimed in  claim 23 , wherein the flatness values are translated online.  
   
   
       25 . The method as claimed in  claim 24 , wherein, the flatness values are translated online via an approximation function.  
   
   
       26 . The method as claimed in  claim 25 , wherein the metal strip bulge pattern based on the strip flatness is determined via the bulge model by applying an assumed temperature distribution in the transverse direction of the metal strip.  
   
   
       27 . The method as claimed in  claim 26 , wherein the actual flatness of the metal strip is measured by a laser measuring device.  
   
   
       28 . The method as claimed in  claim 27 , wherein the laser measuring device is a multi-track laser measuring device.  
   
   
       29 . The method as claimed in  claim 27 , wherein a flatness limit value is predefined at points to control the mill train.  
   
   
       30 . A metal strip mill train control device, comprising: 
 a device that measures an actual flatness of the metal strip;    a regulating unit coupled to a bulge model, the model using a device that measures the actual flatness of the metal strip and a material flow model to control a roll stand of the mill train to minimize the difference between the actual flatness and the desired flatness of the metal strip.    
   
   
       31 . The control device as claimed in  claim 30 , wherein the actual flatness measuring device is a laser measuring device.  
   
   
       32 . The control device as claimed in  claim 31 , wherein the laser measuring device is a multi-track laser measuring device.  
   
   
       33 . The control device as claimed in  claim 31 , wherein the bulge model is coupled to a topometric measuring system that determines a bulge pattern of the metal strip.