Patent Publication Number: US-2006000190-A1

Title: Apparatus and method for packaging sheet material

Description:
PRIORITY  
      Priority is claimed to U.S. Provisional Patent Application No. 60/524,773, filed Nov. 21, 2003, and to U.S. patent application Ser. No. 10/772,967, filed Feb. 5, 2004, which claims priority to U.S. Provisional Patent Application No. 60/446,293, filed Feb. 10, 2003. The disclosure of each of the aforementioned documents is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The field of the present invention is sheet material packaging equipment and methods. 2. Background  
      Dispensers for sheet material are well known to the art and come in different forms for dispensing a wide variety of sheet materials. In some cases, the packaging in which the sheet material is initially placed by the manufacturer also serves as the dispenser. In other instances, the sheet material is packaged to facilitate placement of the package in the dispenser and to facilitate dispensation therefrom.  
      One common aspect of many of these dispensing methods is that the sheet material is placed into a U-shaped form before being inserted into the packaging. Different methods of forming the sheet material into the U-shaped form are disclosed in U.S. Pat. No. 6,732,492 to Osborne et al. and U.S. Pat. No. 6,202,392 to Greenwell et al. Other methods, such as the one disclosed in U.S. Pat. No. 3,919,827 to Larson et al., which discloses an apparatus for folding a stack of bags into a “W” shape prior to packaging, are adaptable to place sheet material into a U-shaped form. The solutions provided in the aforementioned patents, however, may not be well suited for all types of stacked materials or for all packaging needs.  
     SUMMARY OF THE INVENTION  
      The present invention is directed towards an apparatus and method for packaging sheet material. Referring to the apparatus, a housing defines a cylindrical cavity which is open at both ends. A wall of the housing includes a longitudinal opening which intersects the cylindrical cavity. A first forming guide is affixed to the housing adjacent to the longitudinal opening and extends into the cylindrical cavity. A banding unit is disposed adjacent the downstream end of the cylindrical cavity. The first forming guide may extend longitudinally beyond the upstream end of the cylindrical cavity and may include parallel walls, each wall being disposed on an opposite side of the longitudinal opening. Optional features include a second forming guide which has a radially defined end affixed to the housing at the upstream end of the cylindrical cavity, a shrink-wrap unit disposed downstream of the banding unit, and a perforation unit disposed downstream of the shrink-wrap unit.  
      Turning to the method, a U-shaped form is imparted upon a stack of sheet material by insertion of the stack into a cylindrical cavity which has a diameter that is less than the width of the stack. The U-shaped stack is moved toward and out of the downstream end of the cylindrical cavity. The U-shaped stack is then banded as it emerges from the cylindrical cavity. When in the cylindrical cavity, a support may be inserted into the U-shaped stack, with the support and the U-shaped stack being moved together toward and out of the cylindrical cavity. After banding, heat-shrinkable wrap may be placed on the banded stack, which may also be perforated following application of heat.  
      Accordingly, the present invention provides an improved apparatus and method for packaging sheet material. Other advantages of the invention will appear hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      In the drawings, wherein like reference numerals refer to similar components:  
       FIG. 1  is a perspective view of a package of sheet material;  
       FIG. 2  is a perspective view of a package of sheet material within a dispenser;  
       FIG. 3  is a schematic view of an apparatus for use in packaging sheet material;  
       FIG. 4  is a perspective view of a forming unit for use in packaging sheet material;  
       FIG. 5  is a cross-sectional along the line  5 - 5  of  FIG. 4 ;  
       FIG. 6  is a cross-sectional along the line  6 - 6  of  FIG. 4 ;  
       FIG. 7  is a perspective view of the upstream end of the forming unit of  FIG. 4 ;  
       FIG. 8  is a cross-sectional view of the forming unit of  FIG. 4  with a stack of sheet material passing therethrough; and  
       FIG. 9  is a is a perspective view of the downstream end of the forming unit of  FIG. 4  with a stack of sheet material emerging therefrom. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Turning in detail to the drawings,  FIG. 1  illustrates a cartridge  11  of sheet material which is a product which may be generated using the following apparatus and method. The cartridge includes a U-shaped stack of sheet material  13 , a supporting insert  15 , a heat-shrunken wrap  17 , and a band  19 . The heat-shrunken wrap  17  and the band  19  both include perforations  21 ,  23 , respectively, to enable easy access to the sheet material  13  when the cartridge  11  is placed in the dispenser  25  shown in  FIG. 2 . The bottom of supporting insert  15  extends below the ends of the U-shaped stack of sheet material  13  by a small distance  27  to provide stability to the cartridge  11  within the dispenser  25 . The longitudinal ends of the supporting insert  15  also extend beyond the longitudinal ends of the U-shaped stack of sheet material  13  by a small distance  29  to provide further stability to the cartridge  12  within the dispenser  25 . The overall size of the support may vary as desired or as needed to suit a particular dispenser.  
       FIG. 3  schematically illustrates a packaging apparatus  31  in which product flows in the direction indicated, with the forming unit being at the upstream end of the apparatus. A flat stack of sheet material (not shown), preferably interfolded, initially passes into the forming unit  33 . The forming unit  33  imparts a U-shaped form upon the stack of sheet material and allows the support to be inserted into the U-shaped stack. The banding unit  35  is disposed downstream of the forming unit  33  and places a band around the U-shaped stack of sheet material, preferably as the U-shaped stack emerges from the forming unit  33 . The band is preferably perforated prior to being placed around the stack and is preferably constructed from a thin sheet of paperboard material, although other suitable materials may also be used. A shrink wrap unit  37  is disposed downstream of the banding unit  35 . This shrink wrap unit  37  places a heat shrinkable wrap about the banded stack of sheet material and heats the heat shrinkable wrap so that the shrink wrap snuggly fits about the form of the U-shaped stack of sheet material. Lastly, the newly packaged sheet material passes to the perforation unit  39 , where the perforations are made in the shrink-wrap as shown in  FIG. 1 .  
      The banding unit  35 , the shrink wrap unit  37 , and the perforation unit  39  are each of a type that are commonly used throughout the packaging industry and are thus known to those skilled in the packaging arts. As such, the details relating to these downstream units are not discussed further herein.  
      A forming unit  33  is illustrated in  FIGS. 4-6 . Referring to  FIG. 4 , the forming unit  33  has three primary parts: the housing  41 , the first forming guide  43 , and the second forming guide  45 . The housing includes a cylindrical tube  47 , the interior of which forms the cylindrical cavity  49 , and two annular rings  51 ,  53  affixed to the cylindrical tube  47 , one at the upstream end near the second forming guide  45  and the second at the downstream end. The cylindrical cavity  49  has a diameter less than the width of the stack of sheet material that is to be packaged. The annular rings  51 ,  53  facilitate introduction of the forming unit  33  into a production line with other equipment, such as the banding unit, shrink wrap unit, and perforation unit. Specifically, the annular rings  51 ,  53  provide a convenient surface with which to mechanically attach the forming unit to other equipment.  
      As can be seen in  FIGS. 5-6 , an opening extends longitudinally in the wall of the cylindrical tube  47 , spanning from the upstream end to the downstream end. A set of flanges  57   a ,  57   b  are attached to the cylindrical tube  47  at the downstream end thereof, one on either side of the longitudinal opening. The flanges  57   a ,  57   b  are secured together to help maintain the shape of the cylindrical tube  47 . A second set of flanges is similarly attached to the upstream end of the cylindrical tube  47  ( FIG. 6  shows one flange  59   a  of this second set). Two longitudinal flanges  61 ,  63  are also affixed to the exterior of the cylindrical tube  47 , one on either side of the longitudinal opening. These longitudinal flanges  61 ,  63  are angled slightly away from the longitudinal opening to help guide the support into and through the longitudinal opening as discussed below.  
      The configuration of the first forming guide  43  is best seen in  FIGS. 5 and 6 . Referring to  FIG. 5 , which shows the cross-sectional view of the forming unit  33 , the first forming guide  43  is constructed of parallel walls  65 ,  67 , each affixed to the cylindrical tube  47  on opposite sides of the longitudinal opening. The combination of the gap in the cylindrical tube  47  and the parallel walls  65 ,  67  of the first forming guide  43  allow insertion of the support into the formed stack of sheet material as the stack passes through the forming unit  33 . As can be seen in  FIG. 6 , the two parallel walls of the first forming guide merge to form an integral extension  69  which protrudes beyond the upstream end of the cylindrical tube  47 . The lower portion  71  of this extension  69  is tapered to facilitate the passage of a stack of sheet material.  
       FIGS. 4 and 6  best illustrate the second forming guide  45 . The second forming guide  45  includes a radially defined end  73  which is affixed to the upstream end of the housing  41 . The inner radius of the radially defined end  73  is approximately equal to the inner radius of the cylindrical tube to allow a stack of sheet material to easily transition from the second forming guide  45  into the cylindrical tube  47 . The opposite end  75  of the second forming guide  45  is linearly defined, having an approximately rectangular shape with three physical sides. The side walls of the second forming guide  45  at the rectangular end  75  are set apart at least as wide as the stack of sheet material. The rectangular end  75  of the second forming guide  45  enables a flat stack of sheet material to be conveyed from standard packaging equipment directly onto the second forming guide  45  without significant, if any, modification to the standard equipment. Between the two opposing ends of the second forming guide  45 , the walls of the second forming guide smoothly transform from the rectangular shape at the rectangular end  75  to the circular shape at radially defined end  73 .  
      With the forming guides configured thusly, when a flat stack of sheet material passes into the rectangular end of the second forming guide and is pushed towards the radially defined end, the outer edges of the flat stack curl about either side of the extension of the first forming guide. The two forming guides thus guide the stack of sheet material into the U-shaped form that allows the stack to pass into the cylindrical cavity and is desired for the final product.  
      Referring to  FIGS. 7-9 , the process of passing a stack of sheet material through the forming unit is illustrated. In  FIG. 7 , a stack of sheet material  81  is shown entering the second forming guide  45 . The stack  81  is moving toward the radially defined end  73  of the second forming guide  45 . At this point, the flat stack of sheet material  81  is beginning to take on the U-shaped form that is desired for the final product. In particular, both sides  83 ,  85  of the stack  81  are being curled upward by the second forming guide  45  to form the legs of the U-shaped form, while as the stack  81  moves forward, the middle portion  87  of the stack  81  will be held down by the lower edge of the first forming guide  43 .  FIG. 8  shows the stack of sheet materials  81  within the cylindrical cavity  49 . The support  89  for the final packaged product is being inserted through the longitudinal opening in the cylindrical tube  47 . The parallel walls  62 ,  65  of the first forming guide allow the support to be inserted into the center of the U-shaped form of the stack of sheet material  81 . Once the support  89  is inserted into the stack of sheet material  81 , the stack  81  and support  89  are pushed or guided out of the downstream end of the cylindrical cavity.  FIG. 9  shows the stack  81  emerging from the forming unit  33  after it has already had a band  91  placed about it by the banding unit. At this point, the stack is ready to be passed to the shrink-wrap unit and then to the perforation unit, thereby forming the cartridge  11  shown in  FIG. 1 .  
      Thus, an apparatus and a method for packaging sheet material are disclosed. While embodiments of this invention have been shown and described, it will be apparent to those skilled in the art that many more modifications are possible without departing from the inventive concepts herein. The invention, therefore, is not to be restricted except in the spirit of the following claims.