Extrusion surge controller and method
AssigneeRandcastle Extrusion Systems, Inc.
InventorKeith Luker
Life of this patent
Estimating the term…
Abstract
An apparatus is provided for extruding a polymer which is subject to periodic surges. The apparatus includes a barrel with an upstream portion for receiving polymer, a downstream portion and a discharge port near the downstream portion. The apparatus also includes a shaft mounted for rotational movement about a longitudinal axis within the barrel as well as drive means connected to rotate the shaft. The apparatus has a surge suppressor for urging polymer upstream toward the discharge port while permitting a portion of polymer to flow downstream into the surge suppressor. A sensor is positioned within the apparatus to detect surges in the polymer and a controller is connected to the sensor and to the drive means for adjusting shaft rotation in response to polymer surges.
Claims4
An apparatus for extruding a polymer which is subject to periodic surges of pressure or flow rate, said apparatus comprising:
- a barrel having an upstream portion for receiving said polymer, a downstream portion and a discharge port proximal said downstream portion;
- a shaft mounted for rotational movement about a longitudinal axis within said barrel, said shaft having a screw flight positioned upstream from said discharge port and arranged for urging said polymer downstream through at least a portion of said barrel;
- drive means connected for rotating said shaft;
- a surge suppressor connected to said shaft including a reverse screw flight on said shaft and located downstream of said discharge port for urging said polymer upstream toward said discharge port while permitting a portion of said polymer to flow in a downstream direction into said surge suppressor, said reverse screw flight of said surge suppressor being capable of generating a pressure less than or substantially equal to a maximum pressure generated in said screw flight;
- sealing means located downstream of said surge suppressor;
- a sensor positioned to detect said surges of said polymer;
- and
- a controller connected to said sensor and to said drive means for adjusting said rotational movement of said shaft in response to said surges of said polymer.
A method for extruding a polymer using an extruder having a barrel, a shall mounted for rotation within said barrel, and a discharge, said method comprising the steps of:
- urging polymer through said barrel and toward said discharge with a screw flight on said shaft;
- generating a polymer pressure and a polymer flow rate;
- suppressing surges in said polymer pressure or said polymer flow rate by generating a suppressing pressure less than or equal to a maximum polymer pressure with a reverse screw flight .positioned on said shaft downstream of said discharge;
- sealing against flow of polymer downstream of said reverse screw flight;
- monitoring said polymer pressure or said polymer flow rate;
- controlling said polymer pressure or said polymer flow rate by adjusting said rotation of said shaft to compensate for said surges in said polymer pressure or said polymer flow rate;
- and
- directing said polymer from said barrel and through said discharge.
Dependencies are inferred from the claim text.