Mold assembly for use in packaging machine

A mold assembly for use in a blistered package making machine for forming a plurality of blisters in a web of thermoplastic resin film, said mold assembly comprising a first rigid structure;

• a plurality of preforming molds formed in said first rigid structure;
• heating means for heating the thermoplastic resin web, passing over said preforming molds, to a soft, pliable condition;
• means for causing portions of said thermoplastic resin web, which overhang said preforming molds, to deform to provide preformed blisters seating within said respective preforming molds while the remaining portion of said thermoplastic resin web is substantially elongated;
• a second rigid structure;
• a plurality of finishing molds formed in said second rigid structure, said finishing molds being arranged in the same pattern as said preforming molds;
• heating means for heating the thermoplastic resin web which has been formed with said preformed blisters;
• and means for causing said preformed blisters under heated condition to deform to provide the corresponding finally formed blisters seating within said respective finishing molds in such a way as to elongate the bottom of each of said preformed blisters radially outwardly.