Knife sealer for thermoplastic film or sheet

Claim 1

A KNIFE SEALER FOR SIMULTANEOUSLY CUTTING AND SEALING TOGETHER THE CUT EDGES OF A PLURALITY OF LAYERS OF THERMOPLASTIC POLYMERIC FILM AND SHEET WHICH COMPRISES A FRAME; A FIRST DRUM ROTATABLY MOUNTED ON SAID FRAME; A SECOND DRUM ROTATABLY MOUNTED ON SAID FRAME; SPACED FROM SAID FIRST DRUM WITH ITS LONGITUDINAL AXIS PARALLEL TO THE LONGITUDINAL AXIS OF SAID FIRST DRUM; A PLURALITY OF CUTTER BLADES SECURED TO THE PERIPHERY OF SAID SECOND DRUM AND EXTENDING RADIALLY FROM THE PERIPHERY OF SAID DRUM SUBSTANTIALLY PARALLEL TO LONGITUDINAL AXIS OF SAID DRUM, EACH CUTTER BLADE HAVING A THIN, SHARP CUTTING EDGE DIVERGING SHARPLY INTO A THICK BLADE BODY, AND EACH CUTTER BLADE HAVING A THERMAL CONDUCTIVITY VALUE OF ABOUT 1 TO ABOUT 30 TIMES THAT OF THE THERMOPLASTIC MATERIAL; A PLURALITY OF SHEAR BARS, EQUAL IN NUMBER AND SPACING TO SAID CUTTER BLADES, SECURED TO THE PERIPHERY OF SAID FIRST DRUM AND EXTENDING FROM THE PERIPHERY OF SAID FIRST DRUM SO AS TO COINCIDE WITH SAID CUTTER BLADES IN CUTTING CONTACT AS SAID DRUMS ARE ROTATED; MEANS TO MAINTAIN SAID CUTTER BLADES AT A TEMPERATURE AT LEAST ABOUT TWICE THAT OF THE SOFTENING POINT OF THE THERMOPLASTIC MATERIAL; MEANS TO ROTATE SAID FIRST DRUM; AND MEANS TO ROTATE SAID SECOND DRUM IN SYNCHRONOUS OPPOSITION TO SAID FIRST DRUM SO THAT SAID BLADES AND SAID CUTTER BARS CONCIDE.