Apparatus And Method For Centering And Spreading A Web

Abstract

A web centering and spreading processing system and related method are used to center a moving web and then spread the web in order to remove wrinkles from the web. The centering mechanism, in one example, has a centering roller that receives the wrinkles web. The outer edges of the web, which tend to be uneven and not centered, are detected and a signal is sent to the centering roller to move the web laterally and thereby center the web. The centered web, which is substantially centered but not necessarily precisely centered, moves to a spreader station that receives the web and spreads it thereby removing any wrinkles in the web. The spreader station may include a roller with a recessed center area and that has at least one set of contoured plates that move across the roller from an inner position to an outer position. The plates have gripping surfaces that grip the edges of the web and spread the web to remove the wrinkles. The plates also have an inner smooth area that, in conjunction with the recessed area, allow the inner area of the web to essentially float and thereby be spread to remove the wrinkles without binding.

1 . A method of processing a web comprising:
 in a web processing system defining a machine center line and a cross-machine direction substantially perpendicular to the machine center line, receiving a moving web defining a first side edge and a second side edge, the web further having one or more wrinkles;   adjusting the web in the cross-machine direction; and   laterally spreading the web to substantially remove the one or more wrinkles.   
     
     
         2 . The method of  claim 1  wherein the adjusting operation further comprises:
 detecting a difference between a first distance and a second distance, the first distance being between the first side edge and the machine center line and the second distance being between the second side edge and the machine center line.   
     
     
         3 . The method of  claim 2  wherein the first distance is between the first side edge and a first target location a set distance from the machine center line and the second distance is between the second side edge and a second target location the set distance from the machine center line. 
     
     
         4 . The method of  claim 2  wherein the operation of detecting occurs between the adjusting and laterally spreading operations. 
     
     
         5 . The method of  claim 2  wherein the adjusting operation further comprises:
 adjusting the web so that the first distance and the second distance are substantially equal.   
     
     
         6 . The method of  claim 1  further comprising the operations of:
 receiving, in association with the adjusting operation, at least one control signal indicative of the difference;   adjusting the web in the cross-machine direction as a function of the at least one signal.   
     
     
         7 . The method of  claim 1  further comprising:
 prior to the adjusting operation, activating at least a portion of the moving web in the cross-machine direction, the operation of activating forming at least some of the one or more wrinkles.   
     
     
         8 . The method of  claim 1  wherein the operation of laterally spreading includes:
 engaging the moving web adjacent the first side edge;   engaging the moving web adjacent the second side edge; and   allowing the moving web to freely move over an area between the first side edge and the second side edge to spread the web and substantially remove the one or more wrinkles.   
     
     
         9 . The method of  claim 1  wherein the moving web comprises a plurality of diapers and the method further comprising:
 following the laterally spreading operation, cutting each of the plurality of diapers from the moving web.   
     
     
         10 . The method of  claim 1  further comprising the operations of:
 detecting an aspect of the web indicative of a distance between the first side edge and the second side edge; and   controlling the laterally spreading of the web to substantially remove the one or more wrinkles as a function of the aspect of the web indicative of the distance between the first side edge and the second side edge.   
     
     
         11 . A web processing system defining a machine center line and a cross-machine direction configured to process a moving web defining a first side edge and a second side edge comprising:
 a web centering assembly comprising a centering mechanism in communication with at least one sensor configured to detect the relationship between the moving web and the machine center line, the centering mechanism configured to receive at least one signal indicative of the relationship between the moving web and the machine center line and adjust the moving web in the cross-machine direction; and   a web spreading assembly including a spreader roller defining a first circumference and a second circumference substantially equal to the first circumference, and a third circumference less than the first and second circumference and positioned between the first and second circumferences, the spreader roller moveably supporting a first plate and a second plate on at least a portion of the first and second circumference, respectively, the first and second plate arranged to engage the web received from the web centering assembly in a region of the first and second edge side edges respectively, and move substantially in the cross-machine direction to spread the web.   
     
     
         12 . The web processing system of  claim 11  wherein:
 the first plate defines an outer area with a surface configured to engage the web in the region of the first side edge; and   the second plate defines a second outer area with a second surface configured to engage the web in the region of the second side edge.   
     
     
         13 . The web processing system of  claim 12  wherein:
 the first plate defines an inner area adjacent the outer area, the inner area having a low coefficient of friction surface configured to allow the web to freely slide of over the inner area; and   the second plate defines a second inner area adjacent the second outer area, the second inner area having a low coefficient of friction surface configured to allow the web to freely slide over the inner area.   
     
     
         14 . The web processing system of  claim 13  wherein:
 the first plate defines an arc with a diameter substantially the same as a diameter of the spreader roller at the first circumference; and   the second plate defines an arc with a diameter substantially the same as a diameter of the spreader roller at the second circumference.   
     
     
         15 . The web processing system of  claim 11  wherein the moving web includes a plurality of diapers, the system further comprising:
 a web activation station configured to intermittently activate the diaper web in the cross-machine direction and subsequently provide the moving web to the web centering assembly and   a web cutting station configured to receive the moving web from the web spreading assembly and cut the individual diapers from the moving web.   
     
     
         16 . The system of  claim 11  wherein the web centering assembly comprises means for centering the web in communication with means for detecting an edge of the web. 
     
     
         17 . The system of  claim 11  wherein the web spreading assembly comprises means for spreading the web. 
     
     
         18 . The system of  claim 11  wherein the web spreading assembly is further configured to receive the at least one signal indicative of the relationship between the moving web and the machine centerline, the web spreading assembly further configured to control an amount of movement of the first plate and second plate substantially in the cross-machine direction to spread the web as a function of the at least one signal. 
     
     
         19 . A web spreading assembly comprising:
 a spreader roller configured to receive a web, the spreader roller having an outer substantially circumferential surface defining a first circumference, a second circumference substantially equal to the first circumference, and a third circumference less than the first and second circumference and positioned between the first and second circumferences;   the spreader roller moveably supporting at least a first plate and second plate on at least a portion of the first and second circumference, respectively, the first and second plates arranged to engage the web and move substantially in the cross-machine direction to spread the web;   the spreader roller including a spreader mechanism coupled with the first plate and the second plate and configured to move the first and second plates substantially in the cross-machine direction, the spreader mechanism receiving at least one control signal indicative of a width of the web, the spreader mechanism configured to control an amount of movement of the first plate and the second plate in the cross-machine direction as a function of the at least one control signal;   the first plate defines an outer area with a surface configured to engage the web in the region of the first side edge, the first plate further defines an inner area adjacent the outer area, the inner area having a low coefficient of friction surface configured to allow the web to freely slide of over the inner area; and   the second plate defines a second outer area with a second surface configured to engage the web in the region of the second side edge, the second plate further defines a second inner area adjacent the second outer area, the second inner area having a low coefficient of friction surface configured to allow the web to freely slide over the inner area.   
     
     
         20 . The web spreading assembly of  claim 19  wherein the spreader mechanism is supported within the spreader roller, the spreader mechanism including a first member at least partially extending through a first lateral channel in the spreader roller and coupled with the first plate, the spreader mechanism including a second member at least partially extending through a second later channel in the spreader roller and coupled with the second plate, the first member operably coupled with a first piston configured to move in the cross-machine direction, the second member operably coupled with a second piston arranged to move in the cross-machine direction opposite the movement of the first piston whereby the first and second plates engage the web in a first relative position and move laterally and away to a second relative position to spread the web.