Patent ID: 7980841

Claim:
A pipe extrusion die apparatus comprising: a straight mandrel section comprising: an inner flow passageway having a first cross-sectional area; and an outer flow passageway substantially concentric with the inner flow passageway, the outer flow passageway having a second cross-sectional area; an inlet flow passageway disposed in fluid communication with the inner and outer flow passageways; a ratio defining section disposed at an upstream end of the straight mandrel section, the ratio defining section having a ratio adjusting tube substantially concentric with, and configured to translate axially along an inner surface of, the inner flow passageway, the ratio adjusting tube having a tapered face movably disposed between being contiguous with the inner surface and being in blocking engagement between the inlet flow passageway and the inner flow passageway; and an outlet section disposed at a downstream end of the straight mandrel section, the outlet section having an inner flow passageway outlet and an outer flow passageway outlet.