Constant shear rate extrusion die
OwnerMohamed B. Elgindiinventor
Life of this patent
Estimating the term…
Abstract
An extrusion die for extruding thermoplastic materials to produce a sheet of substantially uniform thickness, the extrusion die having a manifold width that increases from the centerline toward the die exit or lip. The increasing width manifold arms, with the preland portion, provide a constant shear rate at all areas of the die and a constant residence time, so that every fluid particle path through the die has the same residence time. By having the increasing width manifold arms, the preland area of the extrusion die is decreased, usually by about 30%, often about 40-60%, compared to a Winter die, thus decreasing clam-shelling effect and allowing design and extrusion of wider sheets.
Claims22
An extrusion die comprising:
- a first body half and a second mating body half, which when mated together define a die inlet, a die exit, and a cavity in fluid communication with the die inlet and the die outlet, wherein the die cavity comprises:
- a manifold having a width defined by a back line and a preland back line, with no portion of the back line parallel to the die exit, the width of the manifold increasing from the die inlet toward the die exit;
- and
- a preland portion between the preland back line and the die exit.
(canceled)
An extrusion die comprising:
- a first body half and a second mated body half having a die inlet, a die exit, and a cavity in fluid communication with the die inlet and the die outlet, wherein the die cavity comprises:
- a manifold having a centerline, a back line, a preland back line, and first and second arms each extending from the centerline to a terminus end, each manifold arm having a width defined by the back line and the preland back line, with no portion of the back line parallel to the die exit, the width of each manifold arm increasing from the centerline to its terminus end;
- and
- a preland portion between the preland back line and the die exit.
(canceled)
A method of extruding molten material, the method comprising:
- providing an extrusion die comprising a die inlet, a die exit, and a cavity in fluid communication with the die inlet and the die outlet, wherein the die cavity comprises a manifold having a centerline and first and second arms each extending from the centerline to a terminus end, each manifold arm having a width increasing from the centerline to its terminus end, the die cavity further comprising a preland portion between the manifold arms;
- inputting molten material via the inlet to the manifold, the molten material having a constant shear rate through the die;
- and
- obtaining an extrudate from the die exit.
An extrusion die comprising:
- a first body half and a second mating body half, which when mated together define a die inlet, a die exit, and a cavity in fluid communication with the die inlet and the die outlet, wherein the die cavity comprises:
- a manifold having a rectangular cross-section configured to provide a uniform fluid flow rate and a uniform shear rate at each point within the die cavity, the manifold having a width defined by a manifold backline and a preland backline, the width of the manifold increasing from the die inlet toward the die exit;
- and a constant height preland portion between the preland backline and the die exit.
Dependencies are inferred from the claim text.