Vertical form and fill seal method and apparatus using two sheets of web

Abstract

The disclosure relates to various embodiments and alternatives for vertical form fill and seal methods and apparatus. In particular, two sheets of web are fed by forming collars to a fill tube (or in some embodiments, side by side fill tubes) wherein the sheets of web are wrapped approximately 180 degrees around the periphery of the fill tube. Zippers can be provided mounted transversely on the first sheet of web, mounted in the machine direction on the first sheet of web, or fed as a continuous length between the two longitudinal edges of the two sheets of web. Additionally, some embodiments fill side by side bags from a single fill tube. Other embodiments fill side by side bags from side by side fill tubes.

1 . A method for making bags comprising the steps of: 
 providing a first sheet of web with a first longitudinal edge and a second longitudinal edge;    providing a second sheet of web with a first longitudinal edge and a second longitudinal edge;    providing first and second lengths of zipper, said first and second lengths of zipper each including a first interlocking profile and a second interlocking profile;    wrapping said first and second sheets of web around a filling station whereby said first longitudinal edges are proximate to each other and second longitudinal edges are proximate to each other;    guiding said first length of zipper between said first edge of said first sheet of web and said first edge of said second sheet of web;    guiding said second length of zipper between a second edge of said first sheet of web and said second edge of said second sheet of web;    sealing said first interlocking profile of said first zipper to said first longitudinal edge of said first sheet of web;    sealing said second interlocking profile of said first zipper to said first longitudinal edge of said second sheet of web;    sealing said first interlocking profile of said second zipper to said second longitudinal edge of said first sheet of web; and    sealing said second interlocking profile of said second zipper to said second longitudinal edge of said second sheet of web.    
   
   
       2 . The method of  claim 1  further including the step of guiding said first and second sheets of web by first and second forming collars, respectively.  
   
   
       3 . The method of  claim 2  wherein said first and second sheets of web are each guided around substantially 180 degrees thereby forming a generally cylindrical shape.  
   
   
       4 . The method of  claim 3  wherein said filling station is a fill tube and wherein said first and second sheets of web are guided around said fill tube so that each of said first and second sheets of web extends around substantially 180 degrees of a periphery of said fill tube.  
   
   
       5 . The method of  claim 4  wherein said method is a form fill and seal method.  
   
   
       6 . The method of  claim 5  wherein said fill tube is vertical and said method is a vertical form fill and seal method.  
   
   
       7 . The method of  claim 6  wherein said fill tube includes a longitudinal divider.  
   
   
       8 . The method of  claim 1  wherein said first and second zippers include a slider.  
   
   
       9 . The method of  claim 8  further including the step of forming machine direction seals between first longitudinal edges of said first and second sheets of web and between said second longitudinal edges of said first and second sheets of web outwardly of said first and second zippers thereby forming respective shrouds over said first and second zippers.  
   
   
       10 . The method of  claim 6  further including the step of sealing a center line of said first sheet of web to a center line of said second sheet of web thereby forming a central machine direction seal.  
   
   
       11 . The method of  claim 10  wherein said step of forming said central machine direction seal forms the bottom seal of two adjacent bags.  
   
   
       12 . The method of  claim 11  further including the step of cutting said central machine direction seal to form to separate bags.  
   
   
       13 . The method of  claim 8  further including the step of forming peel seals between said first and second sheets of web immediately inwardly adjacent of said zippers.  
   
   
       14 . The method of  claim 1  wherein said interlocking profiles are free of flanges.  
   
   
       15 . The method of  claim 1  wherein said interlocking profiles include flanges.  
   
   
       16 . A method for making bags comprising the steps of: 
 providing a first sheet of web with a first longitudinal edge with a first interlocking profile of a first zipper sealed thereto and a second longitudinal edge with a first interlocking profile of a second zipper sealed thereto;    providing a second sheet of web with a first longitudinal edge and a second longitudinal edge;    wrapping said first and second sheets of web around a filling station whereby said first longitudinal edges are proximate to each other and second longitudinal edges are proximate to each other;    sealing said second interlocking profile of said first zipper to said first longitudinal edge of said second sheet of web; and    sealing said second interlocking profile of said second zipper to said second longitudinal edge of said second sheet of web.    
   
   
       17 . The method of  claim 16  further including the step of guiding said first and second sheets of web by first and second forming collars, respectively.  
   
   
       18 . The method of  claim 17  wherein said first and second sheets of web are each guided around substantially 180 degrees thereby forming a generally cylindrical shape.  
   
   
       19 . The method of  claim 18  wherein said filling station is a fill tube and wherein said first and second sheets of web are guided around said fill tube so that each of said first and second sheets of web extends around substantially 180 degrees of a periphery of said fill tube.  
   
   
       20 . The method of  claim 19  wherein said method is a form fill and seal method.  
   
   
       21 . The method of  claim 20  wherein said fill tube is vertical and said method is a vertical form fill and seal method.  
   
   
       22 . The method of  claim 20  wherein said fill tube includes a divider.  
   
   
       23 . The method of  claim 16  wherein said first and second zippers include a slider.  
   
   
       24 . The method of  claim 23  further including the step of forming machine direction seals between first longitudinal edges of said first and second sheets of web and between said second longitudinal edges of said first and second sheets of web outwardly of said first and second zippers thereby forming respective shrouds over said first and second zippers.  
   
   
       25 . The method of  claim 14  wherein said machine direction seals are peel seals.  
   
   
       26 . The method of  claim 16  further including sealing strips over said first and second zippers thereby forming shrouds over said first and second zippers.  
   
   
       27 . The method of  claim 21  further including the step of sealing a center line of said first sheet of web to a center line of said second sheet of web thereby forming a central machine direction seal.  
   
   
       28 . The method of  claim 27  wherein said step of forming said central machine direction seal forms the bottom seal of two adjacent bags.  
   
   
       29 . The method of  claim 28  further including the step of cutting said central machine direction seal to form to separate bags.  
   
   
       30 . The method of  claim 23  further including the step of forming peel seals between said first and second sheets of web immediately inwardly adjacent of said zippers.  
   
   
       31 . The method of  claim 16  wherein said interlocking profiles are free of flanges.  
   
   
       32 . The method of  claim 16  wherein said interlocking profiles include flanges.