Patent ID: 6702563
Filing Date: 2004-03-09
Classification: B29C

Abstract:
An extruder die head, comprising a central annular channel defined by an inside wall and an outside wall, which is provided with an annular outlet die slit, and into said inside and outside walls empty internal and external annular slits, respectively, which feed polymer melts and which form smaller diameter openings of truncated channels, formed between internal and external shells of stacked, conical insert members, said annular slits feeding said polymer melts from said truncated channels into said inside and outside walls defining said central annular channel, and said internal and external shells of said conical insert members, respectively, having mating interior and mating exterior conical surfaces which define two counter rotating spiral channels, whose depths taper off in a direction of said annular outlet die slit, said conical insert members including an inside bottom ring and an outside bottom ring, said inside bottom ring having a cylindrical outer wall and a conical inner wall, and said outside bottom ring having a cylindrical inner wall and a conical outer wall, said cylindrical walls being in abutment to define therebetween a feed channel communicating with said central annular channel, and said inside bottom ring and said outside bottom ring having a generally triangular cross-section.