Film press and method for operating a film press

Abstract

A film press for finishing a fibrous web, in particular a paper or board web, includes a roll and a backing roll forming a nip therebetween, and at least one metering rod for contacting at least one of the rolls for applying a liquid or pasty medium thereto to transfer the medium to the fibrous web. The rolls each have a roll core and a roll cover surrounding the roll core. A sensor system having at least one glass fiber into which Bragg gratings are inscribed is disposed in the roll cover and/or between the roll core and roll cover of at least one of the rolls. The sensor system determines a web separation point of the fibrous web from at least one of the rolls after passage through the nip and transfer of the application medium. The web separation point can be controlled by using determined measured values.

1 - 7  (canceled) 
     
     
         8 . . A film press for finishing a fibrous web or a paper or board web, the film press comprising:
 a roll and a backing roll forming a nip therebetween, said roll and said backing roll each having a respective roll core and a respective roll cover surrounding said respective roll core;   at least one metering rod to be brought into contact with at least one of said rolls for applying a liquid or pasty medium to at least one of said rolls in order to transfer the medium to the fibrous web; and   a sensor system having at least one glass fiber with Bragg gratings inscribed therein, said sensor system being disposed at least in said roll cover of at least one of said rolls or between said roll core and roll cover of at least one of said rolls;   said sensor system being configured to determine a web separation point of the fibrous web from at least one said rolls after a passage through said nip and a transfer of the applied medium and being configured to determine measured values, permitting the web separation point to be controlled by using the determined measured values.   
     
     
         9 . The film press according to  claim 8 , wherein said at least one glass fiber is disposed on at least one of said rolls in a straight, curved, meandering or spiral manner. 
     
     
         10 . The film press according to  claim 8 , wherein said Bragg gratings are formed at regular or irregular intervals relative to one another. 
     
     
         11 . The film press according to  claim 8 , which further comprises an evaluation unit configured to detect and evaluate measured signals from said sensor system. 
     
     
         12 . The film press according to  claim 11 , wherein said evaluation unit is connected to said sensor system. 
     
     
         13 . The film press according to  claim 12 , which further comprises an open-loop and closed-loop control unit communicating with said evaluation unit through a cable connection or without cables. 
     
     
         14 . A method for operating a film press for finishing a fibrous web or a paper or board web, the method comprising the following steps:
 providing a film press including:
 a roll and a backing roll forming a nip therebetween, the roll and the backing roll each having a respective roll core and a respective roll cover surrounding the respective roll core; 
 at least one metering rod to be brought into contact with at least one of the rolls for applying a liquid or pasty medium to at least one of the rolls in order to transfer the medium to the fibrous web; and 
 a sensor system having at least one glass fiber with Bragg gratings inscribed therein, the sensor system being disposed at least in the roll cover of at least one of the rolls or between the roll core and roll cover of at least one of the rolls; 
 the sensor system being configured to determine a web separation point of the fibrous web from at least one the rolls after a passage through the nip and a transfer of the applied medium and being configured to determine measured values, permitting the web separation point to be controlled by using the determined measured values; and 
   using a pressure pulse of the fibrous web leaving the roll or the backing roll as a signal in order to control the web separation point from the roll or the backing roll.