High efficiency extruder
AssigneeThe Dow Chemical Company
InventorsForest Busby, Ray A. Herring, Richard O. Kirk, Kathryn S. Jones
Life of this patent
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Abstract
A corotating multiple-screw extruder comprising first and second intermeshing screws of more than one flight. The first screw comprises first and second segments paired with first and second segments of the second screw, respectively. On the first segment of the first screw, the height of the first flight is less than the height of the second flight and on the second segment of the second screw, the height of the first flight is less than the height of the second flight and screws for use in such extruder.
Claims25
A corotating multiple-screw extruder comprising first and second screws which are intermeshed, wherein
- (a) the first screw is comprised of first and second flights;
- (b) within a first segment of the first screw which has a longitudinal distance of at least one-half of a turn, both flights are continuous and the top of the first flight lies a radial distance of k away from the center axis of the first screw, the top of the second flight lies a radial distance of y away from the center axis of the first screw, and k is less than y;
- (c) the first screw further comprises a second segment within which both flights are continuous and the top of the first flight lies a radial distance of w away from the center axis of the first screw, the top of the second flight lies a radial distance of y away from the center axis of the first screw, and w is less than or equal to y;
- (d) the first segment of the first screw is paired with a first segment of the second screw;
- (e) the first segment of the second screw is comprised of first and second continuous flights, and, within said segment, the top of the first flight lies a radial distance of s away from the center axis of the second screw, the top of the second flight lies a radial distance of t away from the center axis of the second screw, and s is equal to t;
- (f) the second segment of the first screw is paired with a second segment of the second screw;
- and
- (g) the second segment of the second screw is comprised of first and second continuous flights, and, within said segment, the top of the first flight lies a radial distance of v away from the center axis of the second screw, the top of the second flight lies a radial distance of t away from the center axis of the second screw, and v is less than t.
A corotating multiple-screw extruder comprising first and second screws which are intermeshed, wherein
- (a) the first screw is comprised of first and second flights;
- (b) within a first segment of the first screw which has a longitudinal distance of at least one-half of a turn, both flights are continuous and the top of the first flight lies a radial distance of k away from the center axis of the first screw, the top of the second flight lies a radial distance of y away from the center axis of the first screw, and k is less than y;
- (c) the first screw further comprises a second segment within which both flights are continuous and the top of the first flight lies a radial distance of p away from the center axis of the first screw, the top of the second flight lies a radial distance of q away from the center axis of the first screw, and p is greater than q;
- (d) the first segment of the first screw is paired with a first segment of the second screw;
- (e) the first segment of the second screw is comprised of first and second continuous flights, and, within said segment, the top of the first flight lies a radial distance of s away from the center axis of the second screw, the top of the second flight lies a radial distance of t away from the center axis of the second screw, and s is equal to t;
- (f) the second segment of the first screw is paired with a second segment of the second screw;
- and
- (g) the second segment of the second screw is comprised of first and second continuous flights, and, within said segment, the top of the first flight lies a radial distance of v away from the center axis of the second screw, the top of the second flight lies a radial distance of t away from the center axis of the second screw, and v is less than t.
An extruder in accordance with 18 wherein the difference between p and q is not equal to the difference between k and y.
Dependencies are inferred from the claim text.