Patent Publication Number: US-2005127125-A1

Title: Method and apparatus for laterally positioning a moving web

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application claims the benefit of provisional patent application No. 60/511,897 filed Oct. 16, 2003, by the present inventor, the contents of which are incorporated by reference herein in their entirety. 
    
    
     FIELD OF INVENTION  
      This invention relates to webs of textile fabric, paper, and others, specifically to an improved way of positioning, and controlling the lateral movement of, such webs.  
     BACKGROUND OF THE INVENTION/PRIOR ART  
      Moving webs—textile fabric, paper, film, foil, nonwoven material, and others—are printed, laminated, coated, washed, dyed, etc., in continuous processes.  
      The lateral position of the moving web being processed must be controlled in such a way that the web is either centered or that one of the edges is precisely controlled, without undue distortion and resultant creases in the web.  
      In addition to being presented to the entry of a process machine in a laterally-controlled condition, a moving web which may have wandered from its desired position must be re-entered at intermediate locations in the process, e.g., in continuous textile washing, dyeing and finishing ranges which process hundreds of yards of fabric simultaneously.  
      All of the methods currently available for lateral positioning and control of a moving web—steering rollers, cammed slats, edge nip rollers, among others—involve some degree of distortion of the web as its lateral position is changed. The amount of correction possible without unacceptable distortion and resultant creases is limited by the free length of web ahead of the guiding method (at least 1 to 1½ times the fabric width).  
      45° turning bars, which are well-known and in use for turning over or changing the direction of a web, are essential elements in this invention. In the experience of the present inventor, a turning bar has never been used to precisely control the lateral position of a moving web.  
     SUMMARY OF THE INVENTION  
      The present invention offers advantages over and alternatives to the known art by providing an apparatus and method which laterally positions a web without causing any distortion or introduction of creases and without the need for any free length of fabric beforehand, regardless of web width. The amount of repositioning possible is limited only by the length of the apparatus components. Floor space requirement in the direction of web flow is minimal. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  illustrates the present invention as it would be seen with direction of web flow toward the observer.  
       FIG. 2  illustrates the apparatus as it would be seen from the left side of  FIG. 1 , with web flow to the observer&#39;s left.  
       FIG. 3  illustrates the apparatus as it would be seen from above, with web flow downward.  
       FIG. 4  illustrates path of the web through the apparatus. 
    
    
     DETAILED DESCRIPTION OF DRAWINGS  
      In  FIG. 1 ,  FIG. 2 , and  FIG. 3 , in a preferred arrangement, the apparatus includes: 
          Entry idler roll  10  whose position is fixed and whose width is sufficient to contain entering web over the range of its varying lateral position     Fixed turning bar  12 , oriented at 45° with respect to idler roll  10 , whose length is sufficient to contain entering web over the range of its varying lateral position     Fixed structural framework  14  for support of idler roll  10  and turning bar  12 , supporting members for which must be narrow enough to avoid contact with the moving web     Vertical idler roll  16 , exit turning bar  18  also oriented at 45°, and exit idler roll  20 , the three of which are mounted on structural framework  22 , all of which are laterally movable as a unit with respect to entry idler roll  10 , turning bar  12 , and framework  14      Lengths of idler roll  16  and turning bar  18  are sufficient to contain entering web over the range of varying its lateral position, while length of exit idler roll  20  is sufficient to contain maximum width of web being processed.     Framework  22  is mounted on wheels  24  at each end for easy lateral movement. Unit is stabilized at upper corner via slide  26  attached to movable frame.     Edge sensors  28 , photoelectric or the like, mounted independently, which monitor position of edges of moving web downstream of idler roll  20  for centering the web or for controlling either edge     Actuating system  30  for laterally moving idler roll  16 , turning bar  18 , idler roll  20 , and framework  22  with respect to entry idler roll  10 , turning bar  12 , and framework  14 , on command from a control system  36 , PLC or the like, receiving input from sensor(s)  28 .     A preferred actuating system makes use of motor-reducer and pulley arrangement  30 , or the like, mounted on fixed framework  14  which drives timing belt  32  secured at each end of movable framework  22 , causing turning bar  18  to move in direction required to correct error in web edge position detected by sensor(s)  28 .        

      The path of web  34  through apparatus as moving section maintains position called for by the sensor(s)  28  is shown on  FIG. 4 .  
      By way of example only, and not in such a way as to be limited to the following dimensions, in one preferred embodiment of the invention for handling a flexible web (such as woven textile fabric or paper) up to 100 inches wide, fixed framework  14  and movable framework  22  are made of 3×1×⅛ inch cold-finished rectangular steel tubing, welded construction; entry idler roll  10 , vertical idler roll  16 , and exit idler roll  20  are made of 3 inch diameter×⅛ inch wall stainless steel ground and polished roll quality tubing; and fixed turning bar  12  and movable turning bar  18  are made of 3 inch diameter×{fraction (1/16)} inch wall welded steel tubing.  
      For webs of more or less flexibility and width, component size requirements and their construction will vary accordingly.  
      Turning bars may be covered with low friction abrasion-resistant plastic such as ultra high molecular weight polyethylene to reduce web tension or, for very low tension, may be perforated to allow introduction of compressed air supplied from a regenerative blower or compressor. If web is plastic or contains synthetic fibers, static electricity generated as web slides over turning bars may be neutralized by any one of many well-known means.  
      In another variation, vertical idler roll  16  may be mounted on fixed (entry) section instead of on movable (exit) section.  
      In another variation, assembled unit may be oriented horizontally instead of vertically.