US3751015A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Screw extruder with radially projecting pins
Assignee: Oerlikon Barmag AG
•
Filing: 1971-06-22
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Granted: 1973-08-07
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Expires: 1991-06-22
Abstract
Abstract A screw extruder for the continuous processing of a synthetic thermoplastic material in which one section of the rotatable screw in the metering or discharge zone of a barrel extruder carries a plurality of radially projecting pins of different specific heights in place of the thread flight, this section extending along an axial length of at least two screw diameters. This combination of apparatus is particularly useful in evening or equalizing the temperature of the processed thermoplastic material.
Inventors
- 👤 E Gathmann
- 👤 F Hensen
- 👤 H Siemetzki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:19
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/50; B29C48/505; B29C48/565; B29C48/03
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
106 words
In a screw extruder for the continuous processing of a thermoplastic polymer wherein a barrel housing surrounds a single rotatable screw having a metering zone toward the discharge end thereof, the improvement which comprises at least one section of the screw in said metering zone which is free of thread flights over an axial length of at least two times the screw diameter and which carries a large number of pins projecting radially from the threadless screw core, the individual pins being varied between at least two different free radial heights and the ratio of pin diameter to said free height being from 0.25:1 to 2:1.
Claim 2
Dependent Claim
106 words
In a screw extruder for the continuous processing of a thermoplastic polymer wherein a barrel housing surrounds a single rotatable screw having a metering zone toward the discharge end thereof, the improvement which comprises at least one section of the screw in said metering zone which is free of thread flights over an axial length of at least two times the screw diameter and which carries a large number of pins projecting radially from the threadless screw core, the individual pins being varied between at least two different free radial heights and the ratio of pin diameter to said free height being from 0.25:1 to 2:1.
Claim 3
Dependent Claim
20 words
A screw extruder as claimed in claim 1 wherein said pins of different heights are arranged in an irregular sequence.
Claim 4
Dependent Claim
38 words
A screw extruder as claimed in claim 1 wherein all of said pins have approximately the same diameter and are arranged next to one another to provide a flow gap therebetween of not more than 1.5 pin diameters.
Claim 5
Dependent Claim
37 words
A screw extruder as claimed in claim 1 wherein pins of different free radial heights are arranged in groups along the core surface such that said threadless core section also contains zones which are free of pins.
Claim 6
Dependent Claim
18 words
A screw extruder as claimed in claim 4 wherein said pin groups are arranged in a herringbone pattern.
Claim 7
Dependent Claim
16 words
A screw extruder as claimed in claim 1 wherein said pins are essentially cylindrical in shape.
Claim 8
Dependent Claim
24 words
A screw extruder as claimed in claim 6 wherein the end surfaces of the pins facing the inner wall of the housing are rounded.
Claim 9
Dependent Claim
32 words
A screw extruder as claimed in claim 1 wherein all of said pins are composed of a highly polished metal which is heat- and corrosion-resistant and which has a good heat-conducting capacity.
Claim 10
Dependent Claim
61 words
A screw extruder as claimed in claim 1 wherein the distance from the screw axis to the apex of the longest pins is equal to the screw radius or up to 1 percent less than the screw radius while the corresponding distance of the shorter pins is within a range of about 4 to 12 percent less than the screw radius.
Claim 11
Dependent Claim
37 words
A screw extruder as claimed in claim 1 wherein the radial pins are carried over a length of the screw extending into a screw channel adjacent that section of the screw which is free of thread flights.
References Cited (Backward Citations)
US2838794A
Cited
US3160688A
Cited
US3252182A
Cited
US3595533A
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US3591146A
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US3487503A
Cited
US3652064A
Cited
US3680844A
Cited
US3623254A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |