| 摘要 |
An apparatus for extruding material is provided which includes a barrel and a screw. The barrel has an axis and an internal operating surface, the internal operating surface defining a barrel interior and a barrel helical thread portion which includes a plurality of grooves reducing in cross-sectional area from a maximum value to a minimum value in a direction axially opposite to the axial direction of flow of material through the barrel. The screw has an external operating surface and extending into the barrel interior, the external operating surface of the screw forming a screw helical thread portion having at least a first and second groove. Each of the first and second grooves has an upstream end, a downstream end, and a body portion extending between the upstream and downstream ends thereof, the first and second grooves being axially co-incident at at least a transition location and being at least partially axially co-extensive. The internal operating surface of the barrel and the external operating surface of the screw together form a passage for the flow of material therethrough in which the material is transferred between the first and second grooves of the screw helical thread portion and the grooves of the barrel helical thread portion with material being advanced in the first groove of the screw helical thread portion being transferred at a different rate to the grooves of the barrel helical thread portion than material being advanced in the second groove of the screw helical thread portion.
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