Passive edge guiding method and apparatus

Abstract

Web handling apparatuses and methods are provided to passively control a lateral position of a moving web. The web wraps around support rollers adjacent opposed web edges. One or more guide rollers are positioned adjacent to the support rollers. The guide rollers are in rolling contact with the web edge to guide the moving, misguided web back into its desired lateral position.

1 . A web handling apparatus comprising:
 first and second support rollers, a web being configured to wrap around the first and second support rollers adjacent first and second web edges thereof, respectively, the first and second support rollers being rotatable to move the web along a length direction thereof; and   first and second guide rollers positioned adjacent the first and second support rollers, respectively, the first and second guide rollers being configured to control a lateral position of the web by contacting the respective first or second web edge along a lateral direction thereof substantially perpendicular to the length direction.   
     
     
         2 . The web handling apparatus of  claim 1 , wherein the web wraps around the first and second support rollers with a wrap angle of about 90° to about 230°. 
     
     
         3 . The web handling apparatus of  claim 1 , wherein a span of the web between the first guide roller and the first support roller has a length of about 1 cm to about 10 cm. 
     
     
         4 . The web handling apparatus of  claim 1 , wherein at least one of the first and second guide rollers includes a groove to receive the first or second edge of the web, the groove has opposite sides configured to contact opposite major surfaces of the web at the first edge. 
     
     
         5 . The web handling apparatus of  claim 1 , wherein the first and second guide rollers are positioned with a distance therebetween substantially the same as the width of the web. 
     
     
         6 . The web handling apparatus of  claim 1 , wherein the web comprises an un-contacted region between the first and the second support rolls comprising at least about 50% of the width of the web. 
     
     
         7 . The web handling apparatus of  claim 1  further comprises a bowed shaft, wherein at least one of the first support roller and the second support roller is supported on the bowed shaft such that at least one of the first and second support rollers is angled outwardly with respect to a direction of web travel. 
     
     
         8 . The web handling apparatus of  claim 1 , wherein the first and second support rollers are respectively angled outwardly with an angle θ. 
     
     
         9 . The web handling apparatus of  claim 8 , wherein the angle θ is adjustable in a range of about 0° to about 6°. 
     
     
         10 . The web handling apparatus of  claim 1 , wherein the first and second guide rollers each are positioned at an upstream position of the respective first and second support rollers. 
     
     
         11 . An apparatus for transporting a web material, the apparatus comprising:
 a first support roller positioned to contact a major surface of a web adjacent a first edge of the web;   a second support roller positioned to contact the major surface of the web adjacent a second edge thereof opposite the first edge; and   a first guide roller positioned adjacent the first support roller,   wherein the web wraps around the first and second support rollers adjacent the first and second edges thereof, respectively, and   wherein the first guide roller is configured to be in rolling contact with the first edge of the web when the web shifts laterally toward the first guide roller.   
     
     
         12 . The apparatus of  claim 11  further comprising a second guide roller positioned adjacent the second support roller, and the second guide roller being configured to contact the second edge of the web. 
     
     
         13 . The apparatus of  claim 11 , wherein the first guide roller is positioned at an upstream position of the first support roller. 
     
     
         14 . A method comprising:
 wrapping a web around first and second support rollers adjacent opposite first and second edges of the web, respectively, the first and second support rollers being rotatable to move the web along a length direction thereof;   providing a first guide roller adjacent the first support roller; and   adjusting the lateral position of the web by contacting the first guide roller to the first edge of the web along a lateral direction of the web substantially perpendicular to the length direction.   
     
     
         15 . The method of  claim 14  further comprising providing a groove to the first guide roller to receive the first edge of the web, the groove has opposite sides configured to contact opposite major surfaces of the web at the first edge. 
     
     
         16 . The method of  claim 14 , wherein a central region of the web between the first support roller and the second support roller comprising at least about 80% of a width of the web is free of support from a roller. 
     
     
         17 . The method of  claim 14 , wherein the web wraps about the first roller and the second roller at an angle of about 90° to about 230°. 
     
     
         18 . The method of  claim 14  further comprising orienting at least one of the first and second support rollers at an angle θ in a plane x-y with respect to the length direction x normal to the width direction y of the web, and wherein the angle θ is adjustable in a range of about 0° to about 6°. 
     
     
         19 . The method of  claim 14  further comprising positioning a second guide roller adjacent the second support roller to contact the second edge of the web. 
     
     
         20 . The method of  claim 14  further comprising applying a coating composition on the web, and processing the coating composition to form a coating layer on the web.