US3799719A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for extruding plastic material
Assignee: Balfour Beatty PLC
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Filing: 1973-05-29
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Granted: 1974-03-26
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Expires: 1993-05-29
Abstract
Abstract The rate of feed of plastic material into a screw extruder is controlled in accordance with the internal pressure at at least one point along the extruder barrel by sampling the pressure measurement at one point in, or at each of several spaced points along, the extruder barrel at intervals under the control of a timing device driven by the extruder screw in such a way that each sample is taken from the same part of the pressure cycle. Pressure samples are compared with a reference signal to produce an error signal when the value of one or more pressure samples deviates from a desired value. These error signals, which may themselves be sampled under the control of the timing device to avoid hunting, are caused to adjust the rate of feed of material to the extruder, e.g., from a second screw extruder, to restore the pressure to the desired value.
Inventors
- 👤 Z Bonikowski
- 👤 B Keen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:26
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/36; B29C48/375; B29C48/38; B29C48/15; B29C48/92; B29C2948/00; B29C2948/92; B29C2948/92009; B29C2948/92019; B29C2948/92066; B29C2948/92085; B29C2948/92095; B29C2948/92323; B29C2948/92361; B29C2948/9238; B29C2948/924; B29C2948/92504; B29C2948/92561; B29C2948/9258; B29C2948/9259; B29C2948/926; B29C2948/92704; B29C2948/92819; B29C2948/92828; B29C2948/92857; B29C2948/92876; B29C2948/92885; B29C2948/92952; B29C48/03; B29C48/05; B29C48/06
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
133 words
Apparatus for controlling the rate of feed of plastic material into a screw extruder in accordance with the internal pressure at at least one point along the barrel of the extruder, which apparatus comprises a timing device driven by the extruder screw, means for measuring the pressure at a point in the extruder barrel, said pressure measuring means being controlled by the timing device in such a way that each sample from the measured point can be taken from the same part of the pressure cycle, means for comparing pressure samples with a reference signal to produce an error signal when the value of at least one pressure sample deviates from a desired value, and means for adjusting the rate of feed of material to the extruder in response to said error signals.
Claim 2
Dependent Claim
133 words
Apparatus for controlling the rate of feed of plastic material into a screw extruder in accordance with the internal pressure at at least one point along the barrel of the extruder, which apparatus comprises a timing device driven by the extruder screw, means for measuring the pressure at a point in the extruder barrel, said pressure measuring means being controlled by the timing device in such a way that each sample from the measured point can be taken from the same part of the pressure cycle, means for comparing pressure samples with a reference signal to produce an error signal when the value of at least one pressure sample deviates from a desired value, and means for adjusting the rate of feed of material to the extruder in response to said error signals.
Claim 3
Dependent Claim
48 words
Apparatus as claimed in claim 1, including means for storing said samples of pressure measurement and a delay circuit which is controlled by said timing device and which itself controls means for sampling error signals derived from the means for comparing pressure measurement samples with a reference signal.
Claim 4
Dependent Claim
21 words
Apparatus as claimed in claim 2, wherein said sampling store includes means for summating a number of samples of pressure measuremEnt.
Claim 5
Dependent Claim
23 words
Apparatus as claimed in claim 3, wherein said sampling store also includes means for taking the mean of a number of pressure samples.
Claim 6
Dependent Claim
81 words
Apparatus as claimed in claim 1, including another screw extruder for feeding plastic material into the screw extruder from which pressure measurements are to be sampled, drive units for driving the extruder screws at relative speeds preset by an extruder speed reference signal, a drive unit fed by the error signals, and adjustable control means adapted to be driven by the drive unit fed by error signal for producing a speed correction signal to the drive unit of the feed extruder.
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) | 1977-03-25 | 1977-09-24 | 1978-03-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-25 | 1981-09-24 | 1982-03-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-25 | 1985-09-24 | 1986-03-26 | $7700.00 | Window Closed / Lapsed |