US3927869A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiscrew extruder
Assignee: Mannesmann Demag Krauss Maffei GmbH
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Filing: 1973-09-24
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Granted: 1975-12-23
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Expires: 1993-09-24
Abstract
Abstract The discharge end of the housing of an extruder comprising two or more meshing feed screws, formed with parallel and intercommunicating cylindrical chambers for the several screws, is provided along the chamber walls with axially extending recesses confronting an entrance throat of an interchamber passage in which the entrained plastic mass exerts a maximum lateral thrust upon these screws. The recesses, designed to build up a counterthrust, lie in regions diametrically opposite the entrance throat or are more or less symmetrically distributed about these regions.
Inventors
- 👤 Wilhelm Hanslik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 13:33
CPC Classifications
B; B29; B29B; B29B7/00; B29B7/30; B29B7/34; B29B7/38; B29B7/46; B29B7/48; B29B7/486; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/395; B29C48/40; B29C48/41; B29C48/435; B29C48/44; B29C48/50; B29C48/68; B29C48/685; B29C48/686
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
178 words
In an extruder for thermoplastic materials comprising a housing with a plurality of axially extending cylindrical chambers intercommunicating through a passage of a width less than the chamber diameter, and a like plurality of feed screws rotatable to drive a plastic mass in said chambers toward a discharge end of the housing, said feed screws intermeshing with one another at said passage and defining an entrance side and an exit side for said passage, the improvement wherein said housing is provided in the vicinity of said discharge end with at least one axially extending shallow peripheral recess in each of at least two of said chambers at a location remote from the entrance side of said passage for counteracting a lateral thrust exerted by said mass upon the corresponding feed screw, said recess being a single continuous groove spanning a multiplicity of turns of the threads of said corresponding feed screw and being of such shape and dimension that the thermoplastic material being extruded will flow easily into and out of said recess and will not lodge therein.
Claim 2
Dependent Claim
178 words
In an extruder for thermoplastic materials comprising a housing with a plurality of axially extending cylindrical chambers intercommunicating through a passage of a width less than the chamber diameter, and a like plurality of feed screws rotatable to drive a plastic mass in said chambers toward a discharge end of the housing, said feed screws intermeshing with one another at said passage and defining an entrance side and an exit side for said passage, the improvement wherein said housing is provided in the vicinity of said discharge end with at least one axially extending shallow peripheral recess in each of at least two of said chambers at a location remote from the entrance side of said passage for counteracting a lateral thrust exerted by said mass upon the corresponding feed screw, said recess being a single continuous groove spanning a multiplicity of turns of the threads of said corresponding feed screw and being of such shape and dimension that the thermoplastic material being extruded will flow easily into and out of said recess and will not lodge therein.
Claim 3
Dependent Claim
14 words
The improvement defined in claim 1 wherein said recess is of generally crescent-shaped cross-section.
Claim 4
Dependent Claim
33 words
The improvement defined in claim 1 wherein said feed screws form a counterrotating pair symmetrically disposed in said housing, each of the chambers associated with said feed screws being provided with said recess.
Claim 5
Dependent Claim
16 words
The improvement defined in claim 1 wherein said location is generally diametrically opposite said entrance side.
Claim 6
Dependent Claim
29 words
The improvement defined in claim 2 wherein said recess is one of two recesses extending substantially symmetrically on both sides of an axial plane passing through said entrance side.
Claim 7
Dependent Claim
27 words
The improvement defined in claim 3 wherein the two recesses on opposite sides of said axial plane extend past another axial plane perpendicular to the first-mentioned plane.
Claim 8
Dependent Claim
24 words
The improvement defined in claim 4 wherein each of said recesses terminates on a line peripherally spaced from said first-mentioned plane by substantially 120*.
Claim 9
Dependent Claim
26 words
The improvement defined in claim 7 wherein the recesses of said chambers are located on the same side of a common axial plane of said chambers.
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) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |