Patent ID: 7074027
Filing Date: 2006-07-11
Classification: B29C,B29K,F16L

Abstract:
1. An extrusion die for forming the inner and outer wall polymer melt parisons for dual wall corrugated plastic pipe, the die providing homogenous melt flow to two axially displaced orifices that form the inner and outer wall polymer melt parisons for the pipe comprising: two individual concentric spiral mandrels operatively interconnected with an extruder source of polymer melt flow in which each spiral mandrel channels the flow of polymer melt from an extruder initially in spiral paths and then to spiral paths having diminishing depths such that the melt from adjacent spiral paths mixes axially to form an annular path of homogenous melt that is directed to flow to two distinct axially displaced die orifices that form the inner and outer wall polymer melt parisons for dual wall plastic pipe, whereby homogenous melt flow to two axially displaced orifices is provided.