Patent ID: 8282374

Claim:
A plastic extrusion apparatus comprising: an extrusion die having a center axis and an orifice that is operable to produce a tube of plastic extruded from the extrusion die; an air ring that is coaxial with the extrusion die center axis, the air ring having an air outlet that is operable to direct air inwardly to cool plastic extruded from the extrusion die; a hollow, annular evacuation chamber surrounding the extrusion die, the annular evacuation chamber being defined by a pair of parallel annular plates, the annular plates being axially spaced and having radially inward edges that define an annular air intake orifice of the annular evacuation chamber, the annular air intake orifice facing toward the die orifice and being adjacent and radially spaced from the die orifice; a plurality of suction inlets in at least one of the annular plates of the pair of annular plates; and, a plurality of air baffles in the annular evacuation chamber on the at least one annular plate, the plurality of air baffles including an air baffle for each suction inlet whereby each air baffle ensures an even suction pressure distribution and airflow at least in a vicinity of the suction inlet.