US4238435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Plastic extrusion
Assignee: Victroplas Ltd
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Filing: 1978-08-01
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Granted: 1980-12-09
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Expires: 1998-08-01
Abstract
Abstract A method of making elongated members of thermoplastic material which simulate natural bamboo by continuously extruding the material through a die, cooling the extruded material downstream of the die, gripping the cool material and transporting the material away from the die and slowing the speed of transport relative to the speed of extrusion at predetermined lengths of extrusion to produce regions of greater external cross-sectional dimensions to provide axially spaced nodes similar to those of bamboo.
Inventors
- 👤 Wolfgang F. Liebisch
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 13:29
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/88; B29C48/90; B29C48/908; B29C48/03; B29C48/09; B29C48/901; B29C48/919; B29C2948/00; B29C2948/92; B29C2948/92504; B29C2948/9258; B29C2948/926; B29C2948/92609; B29C2948/92647; B29C48/001; B29C48/10; B29C48/12; B29C48/13; B29C48/355; B29L; B29L2023/00; B29L2023/003
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
230 words
A method of producing an elongated member of thermoplastic material simulating over at least part of its periphery a length of natural bamboo having a plurality of anti-node portions of substantially constant cross-section throughout their length and a plurality of axially spaced node portions intermediate said anti-node portions, the node portions being projections having at least one cross-sectional dimension which is greater than the corresponding cross-sectional dimension of the anti-node portions and having a plurality of irregularities in the surface thereof, said method comprising continuously extruding said material through a die while in a hot and fluid state into a region which permits increase in external transverse dimension of the extrudate, cooling the material downstream of the die by means of a water jet directed onto the surface of the extrudate a short distance downstream of the die exit to establish an unstable wave front on the extrudate to cause irregularities to form on the node portions, followed by further rapid cooling of the extrudate, transporting the material away from the die and intermittently slowing the speed of transport relative to the speed of extrusion at predetermined lengths of extrusion thus to produce regions of greater external cross-section dimension than the corresponding cross-sectional dimension of the extrudate in regions not produced by slowing said speed of extrusion thereby providing said axially spaced node portions of irregular shape on the member.
Claim 2
Independent Claim
230 words
A method of producing an elongated member of thermoplastic material simulating over at least part of its periphery a length of natural bamboo having a plurality of anti-node portions of substantially constant cross-section throughout their length and a plurality of axially spaced node portions intermediate said anti-node portions, the node portions being projections having at least one cross-sectional dimension which is greater than the corresponding cross-sectional dimension of the anti-node portions and having a plurality of irregularities in the surface thereof, said method comprising continuously extruding said material through a die while in a hot and fluid state into a region which permits increase in external transverse dimension of the extrudate, cooling the material downstream of the die by means of a water jet directed onto the surface of the extrudate a short distance downstream of the die exit to establish an unstable wave front on the extrudate to cause irregularities to form on the node portions, followed by further rapid cooling of the extrudate, transporting the material away from the die and intermittently slowing the speed of transport relative to the speed of extrusion at predetermined lengths of extrusion thus to produce regions of greater external cross-section dimension than the corresponding cross-sectional dimension of the extrudate in regions not produced by slowing said speed of extrusion thereby providing said axially spaced node portions of irregular shape on the member.
Claim 3
Dependent Claim
24 words
A method according to claim 1 wherein said further rapid cooling is achieved by means of a water bath downstream of the water jet.
Claim 4
Dependent Claim
17 words
A method according to claim 2 wherein the extrudate enters a waterbath through a flexible sealing member.
Claim 5
Dependent Claim
30 words
A method according to claim 3 wherein the flexible sealing member is of a configuration such as to contribute to the formation of irregularities in the surface of the nodes.
Claim 6
Dependent Claim
28 words
A method according to claim 1 wherein the member is tubular and the node-like projections are accompanied by an increase in the cross-sectional bore of the tubular member.
Claim 7
Dependent Claim
39 words
A method according to claim 1 wherein there is no variation in the relative speed of extrusion and transport between said predetermined lengths so that the member is of generally constant cross-section between the projections which simulate the nodes.
Claim 8
Dependent Claim
51 words
A method according to claim 1, or claim 2, or claim 3, or claim 4, or claim 5, or claim 6, wherein the thermoplastic material to be extruded comprises a non-uniform mixture of thermoplastics material and coloring matter whereby the extrudate is provided with longitudinal and circumferential regions of differing color.
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) | 1983-12-09 | 1984-06-09 | 1984-12-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-09 | 1988-06-09 | 1988-12-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-09 | 1992-06-09 | 1992-12-09 | $7700.00 | Window Closed / Lapsed |