Increased barrel-stress extruder
AssigneeEastman Kodak Company
InventorStephen J. Derezinski
Life of this patent
Estimating the term…
Abstract
An extrusion apparatus 10 for extruding thermoplastic materials comprises a hollow cylindrical barrel 12 having a preferably smooth inner cylindrical wall 14. An extrusion screw 16 is mounted for rotation about an axis 18 within hollow barrel 12. The extrusion screw 16 has a major diameter, a minor diameter defining a minor circumferential surface (MCS) of the screw 16, and material pushing threads that are spaced axially and have a normal height `h` extending outwardly from the MCS of the screw into rotatable contact with the inner cylindrical wall 14 of the barrel 12.
Claims6
An apparatus for extruding material in a given direction of material flow, the apparatus comprising:
- (a) a hollow barrel having an inner wall;
- (b) an extrusion screw mounted rotatably about an axis within said hollow barrel, said extrusion screw including pushing material threads, each said thread having a crest, a radial height `H` and relative to the direction of material flow;
- a material pushing flank surface on the downstream side of each thread;
- said material pushing flank surface forming a material moving angle .THETA. of greater than 90.degree. with the axis of rotation of said screw such that said material pushing flank surface has a maximum axial spacing `L` along said inner cylindrical wall from the upstream surface of an adjacent downstream thread, and such that a line, normal to said material pushing flank surface at a point `H`/2 , will intersect said inner wall downstream of said pushing flank surface at a point `L`/2 ;
- and
- (c) means for rotating said extrusion screw within said hollow barrel.
Dependencies are inferred from the claim text.