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United States Patent 5909958
Douris , ê et al.

Screw extruder with independently adjustable groove depth

Rauwendaal June 8, 1999

Abstract

A screw extruder (10), including a barrel assembly (12) having a central bore (36) which defines an inner surface (37). An extruder screw (38) is positioned within the barrel assembly's (12) central bore (36). The barrel assembly (12) has an input end (20) which includes a feed housing portion (25), the feed housing portion (25) having an opening for introduction of material into the central bore (36). There is a shaping die (18) situated at the output end (16) of the barrel assembly (12) to shape the extruded material. The feed housing portion (25) also has one or more groove channels (44) opening into the inner surface (37) of the feed housing portion (25) with a key (48) disposed in each of these groove channels (44). Contacting each key (48) are one or more independently activated actuators (28) which can be used to adjust the radial depths of the keys (48) in the groove channels (44) thus controlling the depth of grooves (46) formed between the keys (48) and the central bore (36) of the barrel (12). A control loop may be established by monitoring a process parameter such as barrel assembly pressure by a sensor (32). This data is fed to a process controller (34), which then adjusts the actuators (28) independently to control the groove (46) depths and thus control the process parameter. Also disclosed is a method for controlling extrusion from a screw extruder (10).