Patent US3704972A successfully refreshed from Google Patents.
US3704972A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Self-regulating extruder
Assignee: Schweizerische Industrie Gesellschaft
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Filing: 1971-05-03
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Granted: 1972-12-05
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Expires: 1991-05-03
Abstract
Abstract A screw-type extruder for plastic material has a cylindrical housing axially divided into two externally heated compartments provided at their upstream ends with a hopper and a venting aperture, respectively; at its downstream end each compartment terminates in a mobile housing section for adjustment of the back pressure prevailing therein and, consequently, of the flow rate of plastic mass discharged from the compartment. To equalize the two flow rates, a pair of hydraulic jacks serving to shift these mobile sections are controlled by respective regulators which respond to associated function generators and to the corresponding back pressure as measured just ahead of these mobile sections; the first function generator receives at its input the back pressure of the second compartment whereas the second function generator is adjusted to deliver a constant output dependent upon the desired flow rate at the extrusion nozzle and upon the speed of rotation of the screw.
Inventors
- 👤 Klaus Kneller
- 👤 Daniel Poncet-Montange
- 👤 Jean-Louis Prost
- 👤 Jean Trub
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:15
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/50; B29C48/68; B29C48/395; B29C48/505; B29C48/63; B29C48/92; B29C2948/00; B29C2948/92; B29C2948/92009; B29C2948/92019; B29C2948/92323; B29C2948/92361; B29C2948/9238; B29C2948/92504; B29C2948/92514; B29C2948/92571; B29C2948/9258; B29C2948/9259; B29C2948/926; B29C2948/92819; B29C2948/92857; B29C2948/92876; B29C2948/92885; B29C2948/92895; B29C48/03
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
272 words
An extruder for thermoplastic material, comprising: a generally cylindrical housing axially subdivided into a first compartment and a second compartment, said first compartment having an upstream end provided with inlet means for the admission of raw material to be masticated, said second compartment having an upstream end adjacent the downstream end of said first compartment and provided with venting means for evolving gases; heating means for said first and second compartments; an extrusion nozzle adjoining the downstream end of said second compartment; a rotatable feed screw axially traversing said housing from the region of said inlet means to the vicinity of said nozzle; first mobile constriction means at the junction of said compartments for varying a first internal pressure developing at the downstream end of said first compartment upon a feeding of plastic mass by the rotating screw; second mobile constriction means at the downstream end of said second compartment for varying a second internal pressure developing thereat; first and second adjustment means for displacing said first and second mobile constriction means, respectively; first and second sensing means at the downstream ends of said first and second compartments for measuring said first and second internal pressures, respectively; first and second regulating means connected to said first and second sensing means for controlling said first and second adjustment means in response to said first and second internal pressures, respectively; and function-generaTing means with an input connection to one of said sensing means for delivering to one of said regulating means an output variable establishing a predetermined relationship of said internal pressures corresponding to equal flow rates of plastic mass discharged from said compartments.
Claim 2
Dependent Claim
272 words
An extruder for thermoplastic material, comprising: a generally cylindrical housing axially subdivided into a first compartment and a second compartment, said first compartment having an upstream end provided with inlet means for the admission of raw material to be masticated, said second compartment having an upstream end adjacent the downstream end of said first compartment and provided with venting means for evolving gases; heating means for said first and second compartments; an extrusion nozzle adjoining the downstream end of said second compartment; a rotatable feed screw axially traversing said housing from the region of said inlet means to the vicinity of said nozzle; first mobile constriction means at the junction of said compartments for varying a first internal pressure developing at the downstream end of said first compartment upon a feeding of plastic mass by the rotating screw; second mobile constriction means at the downstream end of said second compartment for varying a second internal pressure developing thereat; first and second adjustment means for displacing said first and second mobile constriction means, respectively; first and second sensing means at the downstream ends of said first and second compartments for measuring said first and second internal pressures, respectively; first and second regulating means connected to said first and second sensing means for controlling said first and second adjustment means in response to said first and second internal pressures, respectively; and function-generaTing means with an input connection to one of said sensing means for delivering to one of said regulating means an output variable establishing a predetermined relationship of said internal pressures corresponding to equal flow rates of plastic mass discharged from said compartments.
Claim 3
Dependent Claim
30 words
An extruder as defined in claim 1 wherein the other of said regulating means has a reference input, further comprising a source of reference magnitude connected to said reference input.
Claim 4
Dependent Claim
37 words
An extruder as defined in claim 2 wherein said source of reference magnitude comprises a function generator establishing a pressure analog dependent upon the delivery rate of said nozzle and the speed of rotation of said screw.
Claim 5
Dependent Claim
27 words
An extruder as defined in claim 1 wherein said input connection extends to said sensing means, said one of said regulating means being said first regulating means.
Claim 6
Dependent Claim
35 words
An extruder as defined in claim 1 wherein said screw has a core formed with two peripheral annular shoulders respectively juxtaposed with said first and second mobile constriction means and defining two variable gaps therewith.
Claim 7
Dependent Claim
44 words
An extruder as defined in claim 5 wherein said core has two stepped portions ahead of said annular shoulders, respectively, each stepped portion having a part of relatively small diameter remote from the respective shoulder and a part of relatively large diameter proximal thereto.
Claim 8
Dependent Claim
25 words
An extruder as defined in claim 1 wherein said housing is provided with a restricted outlet leading from said second mobile partition to said nozzle.
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) | 1975-12-05 | 1976-06-05 | 1976-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-05 | 1980-06-05 | 1980-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-05 | 1984-06-05 | 1984-12-05 | $7700.00 | Window Closed / Lapsed |