Patent US4512943A successfully refreshed from Google Patents.
US4512943A
Expired / Lapsed
US
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Extrusion process for producing thermoplastic pipe
Assignee: Cosden Technology Inc
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Filing: 1983-05-20
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Granted: 1985-04-23
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Expires: 2003-05-20
Abstract
Abstract A process is disclosed for the formation of pipe comprising one or more layers of thermoplastic resin whereby an annular stream of thermoplastic material is transported through an annular extrusion passageway. The downstream annular portion of the extrusion passageway has a radially movable outer wall. The outer wall is radially moved by heat expansion of a bolt thereagainst to change the thickness of a particular arcuate section of the stream. The thickness of the particular arcuate section of the stream may be further changed through selectively heating by electrical resistive elements an arcuate section of the extrusion passageway to heat the stream of thermoplastic material transported in proximity thereto.
Inventors
- 👤 Granville J. Hahn
- 👤 Raleigh N. Rutledge
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 22:40
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/30; B29C48/32; B29C48/335; B29C48/336; B29C48/3363; B29C48/03; B29C48/09; B29C48/16; B29C48/18; B29C48/21; B29C48/325; B29C48/92; B29C2948/00; B29C2948/92; B29C2948/92009; B29C2948/92114; B29C2948/92152; B29C2948/92323; B29C2948/92428; B29C2948/92504; B29C2948/92514; B29C2948/9258; B29C2948/926; B29C2948/92609; B29C2948/92619; B29C2948/92647; B29C2948/92704; B29C2948/92809; B29C2948/92819; B29C2948/92857; B29C2948/92904; B29C2948/92923; B29C2948/92961; Y; Y10; Y10S; Y10S264/00; Y10S264/46
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
106 words
A process for producing thermoplastic pipe comprising: (a) transporting an annular stream of thermoplastic material through an annular extrusion passageway, a downstream annular portion of the extrusion passageway having a radially movable outer wall; (b) radially moving the outer wall by heat expansion of an element thereagainst to change the thickness of an arcuate section of the stream; (c) selectively heating an arcuate section of the passageway to change the final extruded thickness of the stream of thermoplastic material transported in proximity to the heated section, the selectively heated section positioned diametrically across the annular passageway from the section of the outer wall expanded against; and
Claim 2
Dependent Claim
106 words
A process for producing thermoplastic pipe comprising: (a) transporting an annular stream of thermoplastic material through an annular extrusion passageway, a downstream annular portion of the extrusion passageway having a radially movable outer wall; (b) radially moving the outer wall by heat expansion of an element thereagainst to change the thickness of an arcuate section of the stream; (c) selectively heating an arcuate section of the passageway to change the final extruded thickness of the stream of thermoplastic material transported in proximity to the heated section, the selectively heated section positioned diametrically across the annular passageway from the section of the outer wall expanded against; and
Claim 3
Dependent Claim
27 words
(d) commonly controlling the heating of the expansion element and the heating of the passageway to change the resulting thickness of an arcuate section of the stream.
Claim 4
Dependent Claim
27 words
(d) commonly controlling the heating of the expansion element and the heating of the passageway to change the resulting thickness of an arcuate section of the stream.
Claim 5
Dependent Claim
16 words
The process of claim 1 additionally comprising forming a multi-layer annular stream after the transporting step.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-04-22 | 1988-10-22 | 1989-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-22 | 1992-10-22 | 1993-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-22 | 1996-10-22 | 1997-04-23 | $7700.00 | Window Closed / Lapsed |