Contoured seal facing for seal jaws in vertical form, fill, and seal packaging system

Abstract

In order to handle bag configurations having extra layers in some portions, especially where thicker materials are used, the facings of the sealing jaws are relieved in the area of the extra layers, so that even pressure is applied to the material across the entire seal area. An improved transverse seal is obtained using this method.

What is claimed is:  
     
         1 . A set of heat sealers for installation on a form and fill machine, said set of heat sealers comprising: 
 a first seal facing surface;    a second seal facing surface, wherein a first level of said first facing surface and a first level of said second facing surface generally fit together in a mating fashion;    wherein a second level of said first facing surface is recessed from said first level of said first facing surface by an amount that approximately equalizes the pressure across a seal being formed.    
     
     
         2 . The set of heat sealers of  claim 1  wherein said first and said second facing surfaces have generally corrugated surfaces.  
     
     
         3 . The set of heat sealers of  claim 1  wherein said second level of said first facing surface is recessed by the thickness of a material with which said set of facings are designed to work.  
     
     
         4 . The set of heat sealers of  claim 1  wherein said first seal facing surface is a mirror image of said second seal facing surface.  
     
     
         5 . The set of heat sealers of  claim 1 , wherein said heat sealers are sealing jaws.  
     
     
         6 . The set of heat sealers of  claim 1 , wherein said heat sealers are seal facings.  
     
     
         7 . The set of heat sealers of  claim 1 , wherein said first seal facing surface has relieved areas, but said second seal facing surface does not.  
     
     
         8 . The set of heat sealers of  claim 1 , wherein both said first seal facing surface and said second seal facing surface have relieved areas.  
     
     
         9 . An improvement to a form, fill, and seal machine, said improvement comprising: 
 a first seal facing surface;    a second seal facing surface, wherein a first level of said first seal facing surface and a first level of said second seal facing surface generally fit together in a mating fashion;    wherein a second level of said first facing surface is recessed from said first level of said first facing surface by an amount that approximately equalizes the pressure across a seal being formed.    
     
     
         10 . The improvement to a form, fill, and seal machine of  claim 9 , wherein said first and said second seal facing surfaces have generally corrugated surfaces.  
     
     
         11 . The improvement to a form, fill, and seal machine of  claim 9 , wherein said second level of said first facing surface is recessed by the thickness of a material with which said set of heat sealers are designed to work.  
     
     
         12 . The improvement to a form, fill, and seal machine of  claim 9 , wherein said first seal facing is a mirror image of said second seal facing.  
     
     
         13 . The improvement to a form, fill, and seal machine of  claim 9 , wherein said first seal facing surface is part of a removable seal facing.  
     
     
         14 . The improvement to a form, fill, and seal machine of  claim 9 , further comprising stripping bars.  
     
     
         15 . The improvement to a form, fill, and seal machine of  claim 9 , further comprising heat probes capable of heating said set of heat sealers.  
     
     
         16 . The improvement to a form, fill, and seal machine of  claim 9 , further comprising crumb plates.  
     
     
         17 . The form, fill, and seal machine of  claim 9 , further comprising a knife assembly positioned between a first and a second portion of said first facing surface.  
     
     
         18 . A method for manufacturing a bag with a vertical form, fill, and seal machine, said method comprising the steps of: 
 forming a packaging material into a shape in which a first area to be sealed has a first number of layers of packaging material and a second area to be sealed has a second number of layers of packaging material, wherein said first number is greater than said second number;    relieving sections of a pair of heat sealer facings which contact said first portion of an area to be sealed so that an approximately equal pressure is provided across said first and said second areas    
     
     
         19 . The method of  claim 19 , wherein each of said pair of heat sealer facings are relieved approximately the thickness of one layer of a material with which the set of facings are designed to work.  
     
     
         20 . The method of  claim 19 , wherein said relieving step relieves sections of said pair of heat sealer facings in mirror images of each other.