US3570654A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Conveying screw for extrusion machines and the like
Assignee: PLCV Ltd
•
Filing: 1969-03-18
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Granted: 1971-03-16
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Expires: 1989-03-18
Abstract
Abstract Screw conveyors for extrusion machines, and more particularly a conveying screw of the kind adapted to be rotated in a barrel of circular cross section and comprising a central core having at least two spiral flights thereon to form a multistart thread over at least part of its length, adjacent flights defining channels therebetween down which the material to be extruded is progressed.
Inventors
- 👤 Alan Harvey Hill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:10
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/50; B29C48/505; B29C48/59; B29C48/605; B29C48/03
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
86 words
A conveying screw comprising a central core having at least two spiral flights thereon to form a multistart thread over at least part of its length, adjacent flights defining channels therebetween down which material to be extruded is progressed characterized by the provision of apertures through each of said flights at locations such that there are no apertures opposite one another on adjacent flights in the direction of motion of the screw, whereby said material in each channel is allowed to migrate into an adjacent channel.
Claim 2
Dependent Claim
86 words
A conveying screw comprising a central core having at least two spiral flights thereon to form a multistart thread over at least part of its length, adjacent flights defining channels therebetween down which material to be extruded is progressed characterized by the provision of apertures through each of said flights at locations such that there are no apertures opposite one another on adjacent flights in the direction of motion of the screw, whereby said material in each channel is allowed to migrate into an adjacent channel.
Claim 3
Dependent Claim
26 words
A conveying screw according to claim 1 in which areas of cross section of the channels are varied along their lengths whereby said migration is encouraged.
Claim 4
Dependent Claim
27 words
A conveying screw according to claim 1 in which the cross section of the channels is varied by reducing the depth of the channels along their length.
Claim 5
Dependent Claim
28 words
A conveying screw according to claim 1 in which the apertures are constituted by a relieved area on the outermost face of at least one of the flights.
Claim 6
Dependent Claim
32 words
A screw according to claim 1 wherein the apertures are constituted by a slot in at least one of said flights, said slot extending over substantially the full depth of the flight.
Claim 7
Dependent Claim
21 words
A screw according to claim 1 wherein the apertures are constituted by a hole through at least one of said flights.
References Cited (Backward Citations)
US662173A
Cited
US1521044A
Cited
US2754542A
Cited
US3164375A
Cited
US3169752A
Cited
US3253892A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-15 | 1974-09-14 | 1975-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-15 | 1978-09-14 | 1979-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-15 | 1982-09-14 | 1983-03-16 | $7700.00 | Window Closed / Lapsed |