Cross web tension measurement and control

Abstract

The present disclosure generally relates to systems and methods for transporting a web through a web processing apparatus. In one aspect, a web tension adjustment unit for guiding a web. The web tension adjustment unit includes a first guide roller. The first guide roller includes an adjustment unit. The web tension adjustment unit further includes one or more first non-contact sensors positioned to measure displacement data of the web at a first location. The web tension adjustment unit further includes a system controller for controlling the adjustment unit based on the measured displacement data.

1 . A web tension adjustment unit for guiding a web, the web tension adjustment unit, comprising:
 a first guide roller, wherein the first guide roller, comprises:
 an adjustment unit; 
   one or more first non-contact sensors positioned to measure displacement data of the web at a first location; and   a system controller for controlling the adjustment unit based on the measured displacement data.   
     
     
         2 . The web tension adjustment unit according to  claim 1 , wherein the one or more first non-contact sensors are selected from confocal laser sensors, triangulation based laser sensors, line based laser sensors, capacitance sensors, eddy current sensors, or a combination thereof. 
     
     
         3 . The web tension adjustment unit of  claim 1 , wherein the one or more first non-contact sensors include at least two sensors arranged in a transverse direction across the web perpendicular to a travel direction of the web. 
     
     
         4 . The web tension adjustment unit of  claim 3 , wherein the first location is between the first guide roller and a second roller, where the web is in a free span position. 
     
     
         5 . The web tension adjustment unit of  claim 4 , wherein the one or more first non-contact sensors measure an angle of reflection of the web. 
     
     
         6 . The web tension adjustment unit of  claim 1 , further comprising one or more second non-contact sensors positioned opposite the one or more first non-contact sensors to monitor cross-web tension to monitor a second side of the web at the first location. 
     
     
         7 . The web tension adjustment unit of  claim 1 , wherein:
 the adjustment unit is positioned at a first end of the first guide roller;   the adjustment unit comprises a motor; or   a combination thereof.   
     
     
         8 . The web tension adjustment unit of  claim 1 , wherein the system controller is a closed-loop controller, and the measured displacement data is used as variable feedback signal. 
     
     
         9 . A web processing apparatus, comprising:
 at least one web tension adjustment unit for guiding a web, the web tension adjustment unit, comprising:
 a first guide roller, wherein the first guide roller, comprises:
 an adjustment unit; 
 
 one or more first non-contact sensors positioned to measure displacement data of the web at a first location; and 
 a system controller for controlling the adjustment unit based on the measured displacement data. 
   
     
     
         10 . The web processing apparatus of  claim 9 , further comprising a coating unit for coating the web. 
     
     
         11 . The web processing apparatus of  claim 9 , wherein the one or more first non-contact sensors are selected from confocal laser sensors, triangulation based laser sensors, line based laser sensors, capacitance sensors, eddy current sensors, or a combination thereof. 
     
     
         12 . The web processing apparatus of  claim 9 , wherein:
 the one or more first non-contact sensors include at least a first sensor and a second sensor arranged in a transverse direction across the web perpendicular to a travel direction of the web; and   the first location is between the first guide roller and a second roller, where the web is in a free span position.   
     
     
         13 . The web processing apparatus of  claim 12 , wherein the first sensor is positioned to measure displacement of the web at the first location along the transverse direction and the second sensor is positioned to measure displacement of the web at a second location along the transverse direction. 
     
     
         14 . The web processing apparatus of  claim 9 , wherein:
 the one or more first non-contact sensors measure an angle of reflection of the web; and   the system controller is configured to calculate a signal for adjusting a position of the first guide roller based on the measured angle of reflection of the web such that, after adjustment, the tension of the web on both sides is identical.   
     
     
         15 . A method for processing a web, comprising:
 guiding the web using at least one web tension adjustment unit, wherein the web tension adjustment unit comprises:
 a first guide roller comprising an adjustment unit; and 
 one or more first non-contact sensors positioned to measure displacement of the web at a first location; 
   measuring the displacement of the web at the first location to provide measured displacement data of the web; and   adjusting a position of the first guide roller by moving one end of the first guide roller, wherein adjusting is based on the measured displacement of the web.   
     
     
         16 . The method of  claim 15 , further comprising calculating a signal for adjusting the position of the first guide roller based on the measured displacement data of the web, wherein after adjustment, the tension of the web on both sides is identical. 
     
     
         17 . The method of  claim 15 , further comprising coating the web with a layer of material after adjusting the position of the first guide roller. 
     
     
         18 . The method of  claim 15 , wherein:
 the one or more first non-contact sensors are selected from confocal laser sensors, triangulation based laser sensors, line based laser sensors, capacitance sensors, eddy current sensors, or a combination thereof;   the one or more first non-contact sensors comprises at least a first sensor and a second sensor arranged in the transverse direction across the web perpendicular to a travel direction of the web; or   a combination thereof.   
     
     
         19 . The method of  claim 18 , wherein:
 the first location is between the first guide roller and a second roller, where the web is in a free span position; and   the first sensor is positioned to measure displacement of the web at a first location along the transverse direction and the second sensor is positioned to measure displacement of the web at a second location along the transverse direction.   
     
     
         20 . The method of  claim 15 , wherein:
 the one or more first non-contact sensors measure an angle of reflection of the web; and   the method further comprises calculating a signal for adjusting the position of the first guide roller based on the measured angle of reflection of the web, wherein after adjustment, the tension of the web on both sides is identical.