Extruder die head mandrels for suppressing turbulent flow - to facilitate die design for tubular profiles

摘要

An extrusion die incorporates a static conical mandrel which butts with the end of the screw and channels the melt from the screw through an annular array of passages with outlets which are covered by individual flap valves. The positions of the flaps are controlled by rods which are adjustable from outside the die. The melt passes into the profile lands via a die entry having a profile of optimum form for suppressing local turbulence. Used for producing solid or tubular profiles from material flowing in a non-turbulent manner for which the flow characteristics are relatively predictable for the purpose of die design. The flow pattern can be adjusted and balanced while the machine is running, without involving relative radial shifts of the mandrel and the screw.