US3714309A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Manufacture of plastic film
Assignee: General Engineering Co Ltd
•
Filing: 1970-08-11
•
Granted: 1973-01-30
•
Expires: 1990-08-11
Abstract
Abstract A method of forming an extruded tube of plastic material comprising extruding the material in a semimolten state as a tubular film, having a wall of greater thickness than that of the finished tube, locating a former within the tube near the extrusion point, passing the film over the face of the former in close proximity thereto, at least part of the freeze zone of the film being between the plane of the maximum diameter of the former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone to provide a skin sufficient to prevent actual contact between the film and former. The diameter of the tube being extruded can be varied by varying the diameter of the former. In order to obtain still greater speeds of extrusion, external cooling can be applied.
Inventors
- 👤 B Biglano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 14:58
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/88; B29C48/90; B29C48/901; B29C48/902; B29C48/03; B29C48/09; B29C48/10; B29C48/89; B29C48/911; B29C48/9115; B29C48/912; B29C2948/00; B29C2948/92; B29C2948/92504; B29C2948/92514; B29C2948/92609; B29C2948/92619; B29C2948/92647; B29C48/001; B29C48/0018
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
277 words
A method of forming an extruded tube of plastic material which comprises extruding said material while in a semi-molten state as a tubular film having a wall of greater thickness than that of the finished tube, locating a former having a maximum diameter within said tube adjacent to the point of extrusion, said former having an outer face, the diameter of said former being substantially greater than that of said film at the point of extrusion, said extruded film being of smaller diameter than the former below said center line thereof, at least part of the freeze zone of said film being between the plane of maximum diameter of said former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone and at a pressure sufficiently low to prevent the air from substantially expanding the diameter of the extruding tube between the former and the extruder and To provide a skin of air of such thickness that it is sufficient to prevent actual contact between said film and said former, increasing the diameter of said tube by drawing said tube over the former, extracting air out of the downstream side at a rate equal to the rate of supply of said air into said freeze zone, maintaining a controlled pressure at said downstream side of said former to maintain said film in a stabilized tubular form, and cooling said tube by said air at said maximum diameter sufficiently to locate said freeze zone between said diameter and said end.
Claim 2
Independent Claim
277 words
A method of forming an extruded tube of plastic material which comprises extruding said material while in a semi-molten state as a tubular film having a wall of greater thickness than that of the finished tube, locating a former having a maximum diameter within said tube adjacent to the point of extrusion, said former having an outer face, the diameter of said former being substantially greater than that of said film at the point of extrusion, said extruded film being of smaller diameter than the former below said center line thereof, at least part of the freeze zone of said film being between the plane of maximum diameter of said former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone and at a pressure sufficiently low to prevent the air from substantially expanding the diameter of the extruding tube between the former and the extruder and To provide a skin of air of such thickness that it is sufficient to prevent actual contact between said film and said former, increasing the diameter of said tube by drawing said tube over the former, extracting air out of the downstream side at a rate equal to the rate of supply of said air into said freeze zone, maintaining a controlled pressure at said downstream side of said former to maintain said film in a stabilized tubular form, and cooling said tube by said air at said maximum diameter sufficiently to locate said freeze zone between said diameter and said end.
Claim 3
Independent Claim
277 words
A method of forming an extruded tube of plastic material which comprises extruding said material while in a semi-molten state as a tubular film having a wall of greater thickness than that of the finished tube, locating a former having a maximum diameter within said tube adjacent to the point of extrusion, said former having an outer face, the diameter of said former being substantially greater than that of said film at the point of extrusion, said extruded film being of smaller diameter than the former below said center line thereof, at least part of the freeze zone of said film being between the plane of maximum diameter of said former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone and at a pressure sufficiently low to prevent the air from substantially expanding the diameter of the extruding tube between the former and the extruder and To provide a skin of air of such thickness that it is sufficient to prevent actual contact between said film and said former, increasing the diameter of said tube by drawing said tube over the former, extracting air out of the downstream side at a rate equal to the rate of supply of said air into said freeze zone, maintaining a controlled pressure at said downstream side of said former to maintain said film in a stabilized tubular form, and cooling said tube by said air at said maximum diameter sufficiently to locate said freeze zone between said diameter and said end.
Claim 4
Independent Claim
277 words
A method of forming an extruded tube of plastic material which comprises extruding said material while in a semi-molten state as a tubular film having a wall of greater thickness than that of the finished tube, locating a former having a maximum diameter within said tube adjacent to the point of extrusion, said former having an outer face, the diameter of said former being substantially greater than that of said film at the point of extrusion, said extruded film being of smaller diameter than the former below said center line thereof, at least part of the freeze zone of said film being between the plane of maximum diameter of said former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone and at a pressure sufficiently low to prevent the air from substantially expanding the diameter of the extruding tube between the former and the extruder and To provide a skin of air of such thickness that it is sufficient to prevent actual contact between said film and said former, increasing the diameter of said tube by drawing said tube over the former, extracting air out of the downstream side at a rate equal to the rate of supply of said air into said freeze zone, maintaining a controlled pressure at said downstream side of said former to maintain said film in a stabilized tubular form, and cooling said tube by said air at said maximum diameter sufficiently to locate said freeze zone between said diameter and said end.
Claim 5
Dependent Claim
41 words
A method according to claim 1 characterized in that a second stream of air of large volume is directed against the outer surface of said film onto a circumferential area of said tube, said stream providing additional cooling of said tube.
Claim 6
Dependent Claim
24 words
A method according to claim 1 wherein said tube is stretched between said extrusion and said former prior to the setting of said plastic.
Claim 7
Dependent Claim
18 words
A method according to claim 1 wherein said air is extracted under the influence of a pumping means.
Claim 8
Dependent Claim
31 words
A method according to claim 1 wherein the maximum diameter of said former is varied during operation of said method whereby corresponding variation in the diameter of said tube is obtained.
Claim 9
Independent Claim
254 words
A method of forming an extruded tube of plastic material which comprises extruding said material while in a semi-molten state as a tubular film having a wall of greater thickness than that of the finished tube, locating a former having a maximum diameter within said tube adjacent to the point of extrusion, said former having an outer face, the diameter of said former being substantially greater than that of said film at the point of extrusion, said extruded film being of smaller diameter than the former below said center line thereof, at least part of the freeze zone of said film being between the plane of maximum diameter of said former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone and at a pressure sufficiently low to prevent the air from substantially expanding the diameter of the extruding tube between the former and the extruder and to provide a skin of air of such thickness that it is sufficient to prevent actual contact between said film and said former, increasing the diameter of said tube by drawing said tube over the former, maintaining a controlled pressure at said downstream side of said former to maintain said film in a stabilized tubular form, and cooling said tube by said air at said maximum diameter sufficiently to locate said freeze zone between said diameter and said end.
Claim 10
Independent Claim
254 words
A method of forming an extruded tube of plastic material which comprises extruding said material while in a semi-molten state as a tubular film having a wall of greater thickness than that of the finished tube, locating a former having a maximum diameter within said tube adjacent to the point of extrusion, said former having an outer face, the diameter of said former being substantially greater than that of said film at the point of extrusion, said extruded film being of smaller diameter than the former below said center line thereof, at least part of the freeze zone of said film being between the plane of maximum diameter of said former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone and at a pressure sufficiently low to prevent the air from substantially expanding the diameter of the extruding tube between the former and the extruder and to provide a skin of air of such thickness that it is sufficient to prevent actual contact between said film and said former, increasing the diameter of said tube by drawing said tube over the former, maintaining a controlled pressure at said downstream side of said former to maintain said film in a stabilized tubular form, and cooling said tube by said air at said maximum diameter sufficiently to locate said freeze zone between said diameter and said end.
Claim 11
Dependent Claim
41 words
A method according to claim 6 characterized in that a second stream of air of large volume is directed against the outer surface of said film onto a circumferential area of said tube, said stream providing additional cooling of said tube.
Claim 12
Dependent Claim
24 words
A method according to claim 6 wherein said tube is stretched between said extrusion and said former prior to the setting of said plastic.
Claim 13
Dependent Claim
18 words
A method according to claim 6 wherein said air is extracted under the influence of a pumping means.
Claim 14
Dependent Claim
31 words
A method according to claim 6 wherein the maximum diameter of said former is varied during operation of said method whereby corresponding variation in the diameter of said tube is obtained.
Claim 15
Independent Claim
278 words
A method of forming an extruded tube of plastic material which comprises extruding said material while in a semi-molten state as a tubular film having a wall of greater thickness than that of the finished tube, locating a former having a maximum diameter within said tube adjacent to the point of extrusion, said former having an outer face, the diameter of said former being substantially greater than that of said film at the point of extrusion, said extruded film being of smaller diameter than the former below said center line thereof, at least part of the freeze zone of said film being between the plane of maximUm diameter of said former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone and at a pressure sufficiently low to prevent the air from substantially expanding the diameter of the extruding tube between the former and the extruder and to provide a skin of air of such thickness that it is sufficient to prevent actual contact between said film and said former, increasing the diameter of said tube by drawing said tube over the former, positively extracting air out of the downstream side at a rate equal to the rate of supply of said air into said freeze zone, maintaining a controlled pressure at said downstream side of said former to maintain said film in a stabilized tubular form, and cooling said tube by said air at said maximum diameter sufficiently to locate said freeze zone between said diameter and said end.
Claim 16
Independent Claim
278 words
A method of forming an extruded tube of plastic material which comprises extruding said material while in a semi-molten state as a tubular film having a wall of greater thickness than that of the finished tube, locating a former having a maximum diameter within said tube adjacent to the point of extrusion, said former having an outer face, the diameter of said former being substantially greater than that of said film at the point of extrusion, said extruded film being of smaller diameter than the former below said center line thereof, at least part of the freeze zone of said film being between the plane of maximUm diameter of said former and the downstream end thereof, directing a high velocity stream of air against the inner face of said film at said former at a velocity at least as high as the point of resonance at said freeze zone and at a pressure sufficiently low to prevent the air from substantially expanding the diameter of the extruding tube between the former and the extruder and to provide a skin of air of such thickness that it is sufficient to prevent actual contact between said film and said former, increasing the diameter of said tube by drawing said tube over the former, positively extracting air out of the downstream side at a rate equal to the rate of supply of said air into said freeze zone, maintaining a controlled pressure at said downstream side of said former to maintain said film in a stabilized tubular form, and cooling said tube by said air at said maximum diameter sufficiently to locate said freeze zone between said diameter and said end.
Claim 17
Dependent Claim
41 words
A method according to claim 11 characterized in that a second stream of air of large volume is directed against the outer surface of said film onto a circumferential area of said tube, said stream providing additional cooling of said tube.
Claim 18
Dependent Claim
24 words
A method according to claim 11 wherein said tube is stretched between said extrusion and said former prior to the setting of said plastic.
Claim 19
Dependent Claim
18 words
A method according to claim 11 wherein said air is extracted under the influence of said pumping means.
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) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |