Hole punching apparatus for thermoplastic film

Claim 1

Apparatus for punching holes and the like in thermoplastic film comprising a steel rule die having an upwardly facing cutting edge, die heating means for heating said die, a platen above said die for selective engagement with said die, and means for moving said platen towards said die, said die heating means including a die block for carrying said die, and heating means for heating said die block, said die defining an opening therein to receive scrap cut from thermoplastic film, said die block defining an opening therein for allowing said scrap to pass through said die block, said die block and said die being heated to a temperature above the melting temperature of said scrap, a stripper between said die and said platen, said stripper defining an opening therein sufficient to receive said die therethrough, spring means for biasing said stripper to a position above said die block, the arrangement being such that said thermoplastic film normally lies along the upper surface of said stripper and said film is moved into contact with said die by said platen, said stripper defining an air passage therein and a plurality of holes connecting said air passage with said upper surface of said stripper, and air supply means for selectively passing air through said air passage, out said plurality of holes, and against said film for lifting said film from said upper surface of said stripper and for cooling said stripper and said film.