Method and apparatus for laterally positioning a moving web

Abstract

An apparatus for laterally displacing a moving web without distorting or creasing the web and without need for free lead-in distance beforehand to achieve these results. Key elements in apparatus include two 45° turning bars, one each at entry and exit, which are stationary and laterally-movable, respectively. Position of web is monitored at exit of apparatus by edge sensor(s), and an actuator moves exit turning bar to displace web in direction called for by said sensor(s).

1 . An apparatus for laterally displacing a moving web without distorting the web, which result is achieved without need for free lead-in distance before web enters apparatus, or without creasing said web, the apparatus comprising, sequentially in direction of web flow: entry idler roll and 45° entry turning bar, both mounted on stationary entry framework; vertical idler roll, 45° exit turning bar, and exit idler roll, the three of which are mounted on laterally-movable exit framework; actuator for causing said exit framework and its turning bar to move as directed by signal from web edge sensors, which movement will cause web to be laterally displaced  
     
     
         2 . An apparatus as in  claim 1 . in which vertical idler roll is mounted on stationary entry framework rather than on movable exit framework  
     
     
         3 . An apparatus as in  claim 1 . or  claim 2 . in which turning bars are perforated, or porous, rather than of solid construction, and into which compressed air may be introduced to allow web to float over bars under very low tension  
     
     
         4 . An apparatus as in  claim 1. ,  claim 2 . or  claim 3 . which is oriented horizontally rather than vertically  
     
     
         5 . An apparatus as in  claim 1. ,  claim 2 . or  claim 3 . in which movable exit turning bar is oriented 90° with respect to stationary entry bar, rather than parallel to stationary entry bar, for turning the web over in addition to displacing it.