US3897937A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Extruder screw
Assignee: Individual
•
Filing: 1973-08-30
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Granted: 1975-08-05
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Expires: 1993-08-30
Abstract
Abstract For use in plastic extrusion apparatus, an extrusion screw having a central root. The central root has a cylindrical surface of a predetermined radius and about which surface a helical thread is disposed to form a plurality of flights. The radius of the surface of the flights is slightly greater than the radius of the central root. The root of at least one flight includes plural depressed portions, each of which is in the form of a planar surface, whose maximum distance from the central axis of the root is less than the radius of the central root. Adjacent depressed portions in the flight are separated from one another by the cylindrical surface of the root.
Inventors
- 👤 A Paul Limbach
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:57
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/50; B29C48/505; B29C48/62; B29C48/03
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
119 words
An elongated extrusion screw having a central axis and comprising a central root having a round cylindrical surface of a first predetermined radius and having a helical thread disposed about said surface along a length thereof to form at least one flight, said flight having a land of a second predetermined radius, said root including at least one portion in at least one flight lying adjacent said land and defing a planar depressed surface whose maximum distance from the central axis in the radial direction is less than the dimension of the first radius, the remaining portion of the root of said flight also lying adjacent said land and having said round cylindrical surface of said first predetermined radius.
Claim 2
Dependent Claim
119 words
An elongated extrusion screw having a central axis and comprising a central root having a round cylindrical surface of a first predetermined radius and having a helical thread disposed about said surface along a length thereof to form at least one flight, said flight having a land of a second predetermined radius, said root including at least one portion in at least one flight lying adjacent said land and defing a planar depressed surface whose maximum distance from the central axis in the radial direction is less than the dimension of the first radius, the remaining portion of the root of said flight also lying adjacent said land and having said round cylindrical surface of said first predetermined radius.
Claim 3
Dependent Claim
52 words
The extrusion screw of claim 1 wherein said flight includes plural portions, each one defining a planar depressed surface whose maximum distance from the central axis in the radial direction is less than the dimension of the first radius, with a portion of said cylindrical surface interposed between adjacent depressed surface portions.
Claim 4
Dependent Claim
37 words
The extrusion screw of claim 2 wherein each flight includes three depressed portions such that the cross section of the root is of generally triangular shape with the corners thereof rounded and having said first predetermined radius.
Claim 5
Dependent Claim
37 words
The extrusion screw of claim 2 wherein each flight includes four depressed portions such that the cross section of the root is of generally square shape with the corners thereof rounded and having said first predetermined radius.
Claim 6
Dependent Claim
38 words
The extrusion screw of claim 2 wherein each flight includes five depressed portions such that the cross section of the root is of generally pentagon shape and with the corners thereof rounded and having said first predetermined radius.
Claim 7
Dependent Claim
38 words
The extrusion screw of claim 2 wherein each flight includes six depressed portions such that the cross section of the root is of generally hexagon shape and with the corners thereof rounded and having said first predetermined radius.
Claim 8
Dependent Claim
18 words
The extrusion screw of claim 2 wherein said screw includes plural flights, each flight including plural depressed portions.
Claim 9
Dependent Claim
37 words
The extrusion screw of claim 2 wherein said screw includes a feed section, a transition section and a metering section and with at least one flight of the metering section including at least one depressed surface portion.
Claim 10
Dependent Claim
22 words
The extrusion screw of claim 8 wherein said transition section also includes at least one flight having at least one depressed surface.
Claim 11
Dependent Claim
22 words
The extrusion screw of claim 9 wherein said feed section also includes at least one flight having at least one depressed suRface.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |