Annular extrusion die
AssigneeSussex Plastics Engineering, Inc.
InventorLeonard F. Sansone
Life of this patent
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Abstract
An annular extrusion die having a rotating shear ring which provides a pumping and shearing action on the plastic as it passes through the die annulus, and a method of forming annular extrusions.
Claims15
In a screw extruder for melt extrusion of a polymer, comprising at least one screw for advancing the polymer through the extruder under conditions of elevated temperature and pressure and an annular extrusion die at the outlet of the extruder having an annulus formed between an inner mandrel member and a surrounding outer die member, the improvement which comprises polymer pumping and shearing means spaced from the outlet of said extrusion die comprising shear ring means mounted on at least one of said members and rotatable about the common longitudinal axis of said members, said shear ring means having a surface facing said annulus and spaced from and opposed to a surface of the other of said members, and at least one helical groove is provided in at least one of said surfaces, the outer die member and the inner mandrel member being stationary at the outlet of said extrusion die.
Dependencies are inferred from the claim text.