Packaging machines using retractile thermoplastic film

Claim 1

A compact heat-shrink packaging machine comprising, a grating; means for supplying longitudinally over the grating an elongate, longitudinally folded plastic, heat-shrinkable film for packaging in lengths of the folded films articles heat-sealed therein; a single unit for sealing successively lengths of the heat-shrinkable film each into a package and shrinking it about articles therein with heat and cutting the film along a seal transverse of the film to sever the sealed package from the film and effect a seal along the leading edge of the film for a next successive length of film to be made into a package with articles therein; said single unit comprising means defining a compartment within which said grating is disposed and having a hinged lid for opening the compartment to allow advancing the film longitudinally and introducing longitudinally a length of said heat-shrinkable film on to said grating and articles in said length of film to be packaged therein and for closing said compartment for heat-sealing and shrinking said length of film; said unit having an electrically energized sealing element having one arm along a side edge of the compartment and over which the length of film is advanced longitudinally and disposed for heat sealing the length of film transversely of the folded film and having another arm along another side edge of the compartment over which an open side of the folded film is advanced for heat sealing along the length of the open side of said length of film to close it; said lid having edges for sealing the compartment closed overlying both arms of said sealing element when the lid is closed for pressing the film overlying said arms of said sealing element and jointly with said sealing element effecting sealing of said length of film into a package and cutting the film along the seals effected; said unit having electrically energized heating elements in said compartment for heating the air therein; driven air-circulating means for circulating air heated by said heating elements through said grating to shrink the length of heat-shrinkable film about the articles therein; whereby in order to make a first package a leading length of said film is first sealed transversely along a leading edge with said one arm and lid and the lid is opened and said length of film is advanced over said grating and sealed with said articles therein and the film is severed from said length while the lid is closed and the leading edge thereof is sealed for insertion of articles into the next successive length of film before advancing it onto the grating.