US4165354A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for producing plastic pipes having oval cross-sectional shape
Assignee: Sekisui Chemical Co Ltd
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Filing: 1977-08-15
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Granted: 1979-08-21
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Expires: 1997-08-15
Abstract
Abstract A process for producing a plastic pipe having an oval cross-sectional shape with a high dimensional precision, which comprises conducting a roughly shaped plastic pipe having an oval cross-sectional shape, which is in the softened state and composed of a large-diameter portion, a small-diameter portion and transitional portions connecting them to each other, to a cooling tank while its shape is adjusted by being passed through a forming tube with its large-diameter portion down; cooling the form-adjusted plastic pipe in the cooling tank by dipping the large-diameter portion or both the large diameter portion and a part of the transitional portions contiguous thereto in a cooling bath; and subjecting that portion of the form-adjusted plastic pipe which is out of the cooling bath to a shower of a cooling liquid. This plastic pipe is useful for a drainage or sewage system.
Inventors
- 👤 Noboru Iida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 07:57
CPC Classifications
B; B29; B29C; B29C67/00; B29C67/0014; B29C35/00; B29C35/16; B29C48/00; B29C48/03; B29C48/09; B29C48/12; B29C48/25; B29C48/88; B29C48/911; B29C48/9115; B29C48/919; B29C2035/1616; B29C48/10; B29L; B29L2023/00; B29L2023/22; B29L2031/00; B29L2031/001; B29L2031/003; B29L2031/772
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
130 words
A process for producing a plastic pipe having an oval cross-sectional shape with a high dimensional precision, which comprises conducting a roughly shaped plastic pipe having an oval cross-sectional shape, which is in the softened state and composed of a large-diameter portion, a small-diameter portion and transitional portions connecting them to each other, to a cooling tank while its shape is adjusted by being passed through a forming tube with its large-diameter portion down; cooling the form-adjusted plastic pipe in the cooling tank by dipping the large-diameter portion or both the large diameter portion and a part of the transitional portions contiguous thereto in a cooling bath; and subjecting that portion of the form-adjusted plastic pipe which is out of the cooling bath to a shower of a cooling liquid.
Claim 2
Dependent Claim
130 words
A process for producing a plastic pipe having an oval cross-sectional shape with a high dimensional precision, which comprises conducting a roughly shaped plastic pipe having an oval cross-sectional shape, which is in the softened state and composed of a large-diameter portion, a small-diameter portion and transitional portions connecting them to each other, to a cooling tank while its shape is adjusted by being passed through a forming tube with its large-diameter portion down; cooling the form-adjusted plastic pipe in the cooling tank by dipping the large-diameter portion or both the large diameter portion and a part of the transitional portions contiguous thereto in a cooling bath; and subjecting that portion of the form-adjusted plastic pipe which is out of the cooling bath to a shower of a cooling liquid.
Claim 3
Dependent Claim
34 words
The process of claim 1 wherein the roughly shaped plastic pipe in the softened state having an oval cross-sectional shape has been extruded from a die having an extrusion slit with an oval contour.
Claim 4
Dependent Claim
52 words
The process of claim 1 wherein the roughly shaped plastic pipe in the softened state having an oval cross-sectional shape is obtained by extruding a pipe having a circular cross-sectional shape from a die having an extrusion slit with a circular contour, and deforming it so that its cross-sectional shape becomes oval.
Claim 5
Dependent Claim
33 words
The process of claim 1 wherein the form-adjusted plastic pipe is dipped in the cooling bath to a depth which is 1.0 to 1.5 times the radius of curvature of its large-diameter portion.
Claim 6
Dependent Claim
33 words
The process of claim 1 wherein the form-adjusted plastic pipe is dipped in the cooling bath to a depth which is 1.2 to 1.3 times the radius of curvature of its large-diameter portion.
Claim 7
Dependent Claim
15 words
The process of claim 1 wherein the plastic pipe is a rigid polyvinyl chloride pipe.
References Cited (Backward Citations)
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US2375827A
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US2451986A
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US3057013A
Cited
US3296661A
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US3679435A
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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) | 1982-08-20 | 1983-02-19 | 1983-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-08-20 | 1987-02-19 | 1987-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-08-20 | 1991-02-19 | 1991-08-21 | $7700.00 | Window Closed / Lapsed |