Patent ID: 7032843

Claim:
A mixing nozzle for mixing extrudate, comprising: (a) a casing having an inlet portion for receiving extrudate, a mixing portion and an outlet portion for discharging extrudate, said casing including a passage extending between the upstream end of said inlet portion and the downstream end of said outlet portion, (b) a generally stationary mixer fitting within said passage of said casing, said mixer including: (i) a body portion, (ii) a tail flange for clamping between said mixing portion and said outlet portion of said casing, said tail flange including radial passages for conducting molten plastic from said mixing portion of said casing to said outlet portion of said casing, (iii) elongated flow directing lands disposed upon said body portion extending from the upstream end of said body portion to the downstream end of said body portion and extending radially to seal against the inside wall of said casing, said flow directing lands having a first helix angle, (iv) elongated barrier lands disposed upon said body portion extending from the upstream end of said body portion to the downstream end of said body portion in a paired alternating relationship with said flow directing lands, said barrier lands offset from the inside wall of said casing, at least one of said barrier lands including at least one notch for transverse flow of molten plastic across said barrier lands, said barrier lands having a second helix angle that is greater than said first helix angle, (v) inlet channels defined by first pairs of flow directing lands and barrier lands, said inlet channels converging in the downstream direction such that said inlet channels are relatively closed in the downstream direction and relatively open in the upstream direction for communication with the upstream end of said casing, (vi) outlet channels defined by second alternating pairs of barrier lands and flow directing lands, said outlet channels diverging in the downstream direction such that said outlet channels are relatively closed in the upstream direction and relatively open in the downstream direction for communication with said downstream end of said casing, whereby said extrudate is received by said inlet end of said casing and is received primarily by said inlet channels, passes over said barrier lands and through said at least one notch of said at least one barrier land and into said outlet channels in a mixing fashion and flows to said downstream end for discharge in an increasingly mixed condition.