Flatness measurement system for metal strip

Abstract

The invention relates to a flatness measurement and control system for metal strip, which makes it possible to obtain improved strip or coil quality by a simple and effective measurement of departures from flatness and to control the finishing parameters through the evaluation of a line pattern on the strip surface or on the end face of a coil as it is coiled.

What is claimed is:  
     
         1 . Method for measuring the flatness of metal strip or of the end face of the coil when coiling strip, wherein 
 a line pattern ( 2 ) is produced on the measurement surface ( 4 ) by means of a projector and    is detected directly by a camera ( 5 )    
     
     
         2 . Method as claimed in    claim 1   , wherein the line pattern ( 2 ) is compared by computer with a reference pattern after its detection by the camera ( 5 ).  
     
     
         3 . Method as claimed in    claim 1    or    claim 2   , wherein the measured values are used for control of a finishing train.  
     
     
         4 . Rolling mill train comprising a finishing stand ( 6 ), a strip cooling line ( 8 ), a coiler ( 7 ) and measuring means located before and after the strip cooling line for measuring the strip flatness, which is coupled with the means for controlling the finishing stand ( 6 ), the strip cooling line ( 8 ) and the coiler ( 7 ).  
     
     
         5 . Rolling mill train as claimed in    claim 4   , wherein the flatness of the strip is detected in the run-out from the finishing line ( 6 ) and evaluated for control of the last stands of the finishing rolls, and the measured values of the flatness measurement are used to modify the flatness after the strip cooling stage ( 8 ) and before the coiler ( 7 ).  
     
     
         6 . Rolling mill train as claimed in any one of    claims 1    to    5    wherein, using the measured values detected after the strip cooling line ( 8 ), a first secondary control loop ( 11 ) is produced which permits the intended value for the cooling line ( 8 ) to be adapted.  
     
     
         7 . Rolling mill train as claimed in any one of    claims 1    to    6    wherein, using the measured values detracted after the strip cooling stage ( 8 ), a second secondary control loop ( 12 ) is produced which permits the intended value for the coiler tension ( 7 ) to be adapted.