Method and apparatus for relieving stress in a fabric

Abstract

A method of relieving stress in a window covering or other fabric composite by providing a fabric composite including first and second sheets of sheer material coupled to each other by a plurality of vanes. The fabric composite is fed along a pathway, and tension is applied to the fabric composite in directions both substantially perpendicular and substantially parallel to the pathway. The tensioned fabric composite passes adjacent to a plurality of heating units which apply heat to the window covering, removing creases and imperfections from the fabric composite. The tension is then removed from the fabric composite in the directions both parallel and perpendicular to the pathway.

What is claimed is:  
     
         1 . A method of relieving stress in a fabric, comprising the steps of: 
 providing a fabric having at least three layers;    feeding the fabric along a pathway;    applying a tension to the fabric in a direction substantially perpendicular to the pathway;    heating the fabric; and    removing the tension from the fabric in the direction substantially perpendicular to the pathway.    
     
     
         2 . The method of  claim 1 , wherein a tentering frame is used for applying tension to the fabric in the direction substantially perpendicular to the pathway.  
     
     
         3 . The method of  claim 2 , further comprising the steps of: 
 before heating, applying a tension to the fabric in a direction substantially parallel to the pathway; and    after heating, removing the tension from the fabric in the direction substantially perpendicular to the pathway.    
     
     
         4 . The method of  claim 3 , wherein the fabric comprises a window covering including first and second sheets of material coupled to each other by a plurality of vanes.  
     
     
         5 . The method of  claim 4 , wherein each side of the tentering frame contacts the respective substantially opposite edges of the first and second sheets of sheer material.  
     
     
         6 . The method of  claim 3 , wherein a nip system is used for applying the tension to the window covering in the direction substantially parallel to the pathway.  
     
     
         7 . The method of  claim 6 , wherein the nip system includes a plurality of nips along the pathway for contacting the window covering.  
     
     
         8 . The method of  claim 7 , further comprising the step of carrying the window covering along the pathway with a drive belt assembly.  
     
     
         9 . A system for relieving stress in a three-dimensional window covering, comprising: 
 a tentering frame for applying tension to a three-dimensional window covering in a first direction; and    a plurality of heating elements located along the tentering frame for heating the window covering,    wherein the tentering frame carries the window covering while under tension in the first direction along a pathway adjacent to the heating elements.    
     
     
         10 . The system of  claim 9 , further comprising a plurality of nip units along the pathway for applying tension to the window covering in a second direction.  
     
     
         11 . The system of  claim 10 , wherein the heating elements comprise a first plurality of heating elements on a first side of the pathway and second plurality of heating elements on a second side of the pathway substantially opposite the first side of the pathway.  
     
     
         12 . The system of  claim 11 , wherein the first and second pluralities of heating elements each comprise three heating elements.  
     
     
         13 . The system of  claim 11 , wherein the window covering comprises a first sheer material and a second sheer material coupled to each other by at least one vane, the first and second sheer materials having first and second edges located substantially parallel to the pathway, and wherein the tentering frame applies tension to the window covering in the first direction by contacting the first edge of the first sheer material and the second edge of the second sheer material.  
     
     
         14 . The system of  claim 11 , further comprising a platen located between the first and second pluralities of heating elements, wherein the window covering contacts the platen as the window covering is carried by the tentering frame.  
     
     
         15 . The system of  claim 9 , further comprising a conveyor belt along the pathway adjacent to the heating elements for carrying the window covering across the platen.  
     
     
         16 . A method of relieving stress in a three-dimensional fabric, comprising the steps of: 
 providing a three-dimensional fabric comprises multiple materials;    feeding the fabric along a pathway;    tensioning the fabric in a first direction;    applying heat to the fabric as the fabric travels along the pathway; and    removing the tension from the fabric in the first direction.    
     
     
         17 . The method of  claim 16 , further comprising the steps of: 
 tensioning the fabric in a second direction substantially perpendicular to the first direction; and    removing the tension from the fabric in the second direction.    
     
     
         18 . The method of  claim 16 , wherein a tentering frame along the pathway is used for tensioning the fabric in the first direction.  
     
     
         19 . The method of  claim 17 , wherein a plurality of nip units along the pathway are used for tensioning the fabric in the second direction.  
     
     
         20 . The method of  claim 16 , further comprising the step of carrying the fabric via a conveyor belt along at least a portion of the pathway.