Web processing apparatus

Abstract

A web tensioning assembly is configured to exert a tension on a web in a process direction and to balance the tension across a width of the web extending substantially in a direction perpendicular to the process direction. A web processing apparatus includes such a web tensioning assembly.

1 . A web tensioning assembly for tensionably guiding a web in a web processing apparatus, comprising:
 an elongated torsion-resilient element extending in an axial direction having at least two opposing axial end portions;   a suspension that suspends said elongated torsion-resilient element, the suspension comprising a first and second suspension linkage, each linkage being non-rotatably connected to the opposing axial end portions of the elongated torsion-resilient element at a first portion of the first and second suspension linkages, respectively, the first and second suspension linkages being rotatably mountable to a frame at a second portion of the first and second suspension linkages, the second portion being located remotely with respect to said first portion, such that the first and second suspension linkages are independently rotatable about an axis extending substantially parallel to said axial direction; and   a web guide at least partially surrounding the elongated torsion-resilient element for guiding the web over said elongated torsion-resilient element,   wherein the web tensioning assembly is configured to exert a tension on the web in a process direction and to balance the tension across a width of the web extending substantially in a direction perpendicular to the process direction.   
   
   
       2 . The web tensioning assembly according to  claim 1 , wherein the web guide comprises a roller. 
   
   
       3 . The web tensioning assembly according to  claim 2 , further comprising a bearing for moveably mounting the roller on the elongated torsion-resilient element. 
   
   
       4 . The web tensioning assembly according to  claim 2 , wherein the roller is freely rotatable about an axis of rotation extending substantially parallel to the axial direction of the elongated torsion-resilient element. 
   
   
       5 . The web tensioning assembly according to  claim 2 , wherein the roller is rotatable over a limited portion of an axial revolution. 
   
   
       6 . The web tensioning assembly according to  claim 2 , wherein the roller is rotatably fixed in the axial direction with respect to the suspension. 
   
   
       7 . The web tensioning assembly according to  claim 6 , further comprising a drag linkage extending between the frame and an eccentric location at an axial end portion of the roller, such that an axial rotation of the roller is prevented. 
   
   
       8 . The web tensioning assembly according to  claim 1 , wherein the suspension is in operation urged towards a predetermined angular equilibrium position with respect to the frame. 
   
   
       9 . The web tensioning assembly according to  claim 8 , wherein the suspension is spring loaded towards the predetermined angular equilibrium position. 
   
   
       10 . The web tensioning assembly according to  claim 1 , wherein the elongated torsion-resilient element is a torsion bar. 
   
   
       11 . The web tensioning assembly according to  claim 10 , wherein the torsion bar is formed such that it has a substantially star-shaped axial cross-section. 
   
   
       12 . The web tensioning assembly according to  claim 11 , wherein the torsion bar is formed such that it has a substantially cylindrical axial cross-section. 
   
   
       13 . The web tensioning assembly according to  claim 1 , wherein the suspension is functionally connected to an angular position encoder, such that the angular position of the suspension with respect to the frame is measurable. 
   
   
       14 . A web processing apparatus, comprising:
 a web feed station for feeding a web;   a web processing station for processing the web; and   a web tensioning assembly for tensionably guiding the web, said web tensioning assembly comprising:
 an elongated torsion-resilient element extending in an axial direction having at least two opposing axial end portions; 
 a suspension that suspends said elongated torsion-resilient element, the suspension comprising a first and second suspension linkage, each linkage being non-rotatably connected to the opposing axial end portions of the elongated torsion-resilient element at a first portion of the first and second suspension linkages, respectively, the first and second suspension linkages being rotatably mountable to a frame at a second portion of the first and second suspension linkages, the second portion being located remotely with respect to said first portion, such that the first and second suspension linkages are independently rotatable about an axis extending substantially parallel to said axial direction; and 
 a web guide at least partially surrounding the elongated torsion-resilient element for guiding the web over said elongated torsion-resilient element, 
 wherein the web tensioning assembly is configured to exert a tension on the web in a process direction and to balance the tension across a width of the web extending substantially in a direction perpendicular to the process direction. 
   
   
   
       15 . The web processing apparatus according to  claim 14 , wherein the web processing station comprises a printing station for applying marking material to the web. 
   
   
       16 . The web processing apparatus according to  claim 14 , wherein the web processing station comprises a recording station for recording an image from the web.