12 Extruder C ircular die Air ring Internal bubble cooling Plastic film bubble C ollapsing fram e U pper nip rolls Slitter D ual roll w inder Blown Film Line With Slitter Fig.10.712 Extruder C ircular die Air ring Internal bubble cooling Plastic film bubble C ollapsing fram e U pper nip rolls Slitter D ual roll w inder Blown Film Line With Slitter Fig.10.7