Method and apparatus for film encapsulation of irregularly shaped articles

Abstract

A method and apparatus for shrink-wrapping a heat sealable thermoplastic film about regular and irregular shaped articles is provided, wherein the film is provided above and below the article, one or more heat-sealing blades are generally configured to the article exterior contour to heat seal the film material about the article, the heat-sealing blade having an electrically actuated healing element within insulated material, and the spacing of the heat-sealing blade adjacent the article is intentionally non-uniform in predetermined manner. A contoured heat-sealing blade assembly is provided within split-molds, which may have associated heating ports to control the temperature of the sealing operation within different zones of the mold.

1 . A method of shrink wrapping a heat shrinkable thermoplastic film about regular and irregular shaped articles comprising: 
 providing said film above and below said article with margins of said film extending beyond said article;    providing one or more heat sealing blade generally configured to the article exterior contour to heat seal said film margin about said article and shrinkage of said film about said article wherein the spacing of said blade adjacent said article is intentionally non-uniform, first portions of said blade being closer to said article than second portions; and    heating said blade and contacting said margins to cause film margins contacted by said blade first portions to shrink into contact with and about said article first and film portions contacted by said second portion to shrink into contact and seal about said article second.    
   
   
       2 . The method of  claim 1  wherein said article has one or more inwardly shaped corner to be wrapped; and said blade first portions are spaced from said one or more corners a distance of about one-third the spacing of said blade second portions for said article.  
   
   
       3 . The method of  claim 1  wherein: said film is provided as one piece folded over and under said article.  
   
   
       4 . The method of  claim 1  wherein: said film is provided as a film pouch fitted about said article.  
   
   
       5 . The method of  claim 1  comprising: clamping said film about said article before sealing of said margins.  
   
   
       6 . The method of  claim 1  comprising: 
 positioning said article in a bottom part of a split mold;    mounting said heat seating blade on an upper part of said mold.    
   
   
       7 . The method of  claim 6  comprising: 
 heating interior zones of said mold through heat introducing ports positioned to allow heating of some interior zones of said mold to temperatures which differ from that of other interior zones of said mold.    
   
   
       8 . The method of  claim 1  comprising: heating said heat one or more sealing blade by an electrically activated flexible cable heater provided within said one or more blade.  
   
   
       9 - 19 . (canceled)  
   
   
       20 . A method of shrink wrapping a heat sealable and shrinkable thermoplastic film about an article to be wrapped, said method comprising: 
 staging a sequence of shrinkage of different parts of said film about said article to cause a first tight fit of said film about preselected parts of said article and a second subsequent tight fit of said film about other parts of said article.    
   
   
       21 . The method of  claim 20  wherein said staging comprises: 
 providing a heat sealing blade for sealing and heating of said film to cause shrinkage about said article; and    spacing first portions of said blade closer to said certain pre-selected parts of said article than the spacing of said blade from said other parts of said article.    
   
   
       22 . The method of  claim 21  wherein: 
 said spacing of said blade first portions is about one-third of the spacing of said blade from said other parts of said article.    
   
   
       23 . The method of  claim 20  wherein said article has an irregular shape with angled intersections of adjacent surfaces: 
 presenting corner or sharply curved intersections, said method comprising:    staging the sequence of shrinkage for said pre-selected parts at said intersections.    
   
   
       24 . The method of  claim 20  comprising: heating of aid heat sealing blade by an electrically activated flexible cable heater provided within said blade.  
   
   
       25 . The method of  claim 20  comprising: 
 staging the sequence of shrinkage of different parts of said film about said article to produce a tighter fit of said film about said preselected parts than the fit of said film about said other parts of said article.    
   
   
       26 - 55 . (canceled)