US4348345A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for the take-away of vertically extruded synthetic resinous tubes
Assignee: Dow Chemical Co
•
Filing: 1981-01-23
•
Granted: 1982-09-07
•
Expires: 2001-01-23
Abstract
Abstract Tetrafluoroethylene polymer is downwardly extruded employing variable counterweight to provide tube of improved physical properties.
Inventors
- 👤 Edward L. Burnett
- 👤 Eugene V. Stack
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 16:24
CPC Classifications
B; B29; B29C; B29C48/00; B29C48/25; B29C48/355; B29C48/022; B29C48/03; B29C48/09; B29C48/06; B29K; B29K2027/00; B29K2027/12; B29K2027/18
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
154 words
In a method for the fabrication of a tetrafluoroethylene polymer tube wherein tetrafluoroethylene polymer resins are downwardly ram extruded in a ram extruder to heat and generally fuse together the polytetrafluoroethylene particles to provide a coherent tetrafluoroethylene polymer tube from the ram extruder, subsequently cooling the tetrafluoroethylene polymer tube to a self supporting condition, the tetrafluoroethylene polymer tube being discharged from the extruder at a temperature above its crystalline melting point, cooling the tube below its crystalline melting point while the tube is radially unsupported and axially supported to provide a tetrafluoroethylene polymer tube of reduced gas permeability, the improvement which comprises supporting the tetrafluoroethylene polymer tube on a movable counterbalanced support means which permits downward motion of the tetrafluoroethylene polymer tube without inducing deformation of the tube either on a continuous or incremental basis to the portion of the tube which is above the crystalline melting point and external to the ram extruder.
Claim 2
Dependent Claim
154 words
In a method for the fabrication of a tetrafluoroethylene polymer tube wherein tetrafluoroethylene polymer resins are downwardly ram extruded in a ram extruder to heat and generally fuse together the polytetrafluoroethylene particles to provide a coherent tetrafluoroethylene polymer tube from the ram extruder, subsequently cooling the tetrafluoroethylene polymer tube to a self supporting condition, the tetrafluoroethylene polymer tube being discharged from the extruder at a temperature above its crystalline melting point, cooling the tube below its crystalline melting point while the tube is radially unsupported and axially supported to provide a tetrafluoroethylene polymer tube of reduced gas permeability, the improvement which comprises supporting the tetrafluoroethylene polymer tube on a movable counterbalanced support means which permits downward motion of the tetrafluoroethylene polymer tube without inducing deformation of the tube either on a continuous or incremental basis to the portion of the tube which is above the crystalline melting point and external to the ram extruder.
Claim 3
Dependent Claim
11 words
The method of claim 1, wherein the tube is extruded intermittently.
Claim 4
Dependent Claim
44 words
The method of claim 1, wherein the movable counterbalance support means comprises an endless flexible member having affixed thereto a tube engaging means and remotely disposed from the tube engaging means a variable weight counterweight to thereby provide a tube of generally constant diameter.
Claim 5
Dependent Claim
22 words
The method of claim 3, wherein the counterweight is a chain whose weight per unit length approximates that of the extruded tube.
References Cited (Backward Citations)
US2456621A
Cited
US2685707A
Cited
US2847711A
Cited
US2945265A
Cited
US3045288A
Cited
US3068513A
Cited
US4203938A
Cited
US4104394A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-09-06 | 1986-03-08 | 1986-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-09-06 | 1990-03-08 | 1990-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-09-06 | 1994-03-08 | 1994-09-07 | $7700.00 | Window Closed / Lapsed |