US4117068A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming curved plastic film from a flat film
Assignee: SK Hynix Inc
•
Filing: 1976-10-26
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Granted: 1978-09-26
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Expires: 1996-10-26
Abstract
Abstract A method for forming a flat, thin polyester film into a curved film using heat, peripheral support for the film, and a single die.
Inventors
- 👤 Charles Newell Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:18
CPC Classifications
B; B29; B29C; B29C51/00; B29C51/08; B29C51/26; B29C51/261; B29C51/262
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
121 words
A method of shaping a flat polyester film comprising the workpiece into a predetermined convex contour, comprising: (a) attaching a flat backing film larger than the film and made of substantially the same material, about its periphery to a frame within which the workpiece film can lie; (b) laying the workpiece film unclamped on the backing film; (c) heating the films to above their heat distortion temperature; (d) while the temperature is maintained, slowly forcing a die having substantially the predetermined contour into the films until the predetermined contour of the films are attained; (e) while maintaining the position of the die, cooling the films to substantially below the heat distortion temperature; and then (f) withdrawing the die from the films.
Claim 2
Independent Claim
121 words
A method of shaping a flat polyester film comprising the workpiece into a predetermined convex contour, comprising: (a) attaching a flat backing film larger than the film and made of substantially the same material, about its periphery to a frame within which the workpiece film can lie; (b) laying the workpiece film unclamped on the backing film; (c) heating the films to above their heat distortion temperature; (d) while the temperature is maintained, slowly forcing a die having substantially the predetermined contour into the films until the predetermined contour of the films are attained; (e) while maintaining the position of the die, cooling the films to substantially below the heat distortion temperature; and then (f) withdrawing the die from the films.
Claim 3
Dependent Claim
20 words
The method of claim 1, wherein the film supporting step comprises clamping the film about its periphery to a frame.
Claim 4
Dependent Claim
34 words
The method of claim 1, including the step of laying a plurality of workpiece films, unclamped, on the backing film in a position permitting the die to be forced against all of them simultaneously.
Claim 5
Dependent Claim
34 words
The method of claim 1 including the step of coating at least one of the die and a surface of the workpiece film with a heat-resistant lubricant prior to the heating of the films.
Claim 6
Dependent Claim
18 words
The method of claim 1, wherein the films heating step includes heating the films to about 300° F.
Claim 7
Dependent Claim
22 words
The method of claim 1, wherein die forcing step includes moving the die at a speed approximately 1 inch per 20 minutes.
Claim 8
Dependent Claim
26 words
The method of claim 1 wherein the die forcing step comprises employing a die having a contour with a slightly sharper curvature than the predetermined contour.
Claim 9
Dependent Claim
33 words
The method of claim 7, wherein the predetermined curvature is spherical, and the die forcing step includes employing a die having a radius of curvature 1-10% less than the desired radius of curvature.
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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) | 1981-09-25 | 1982-03-27 | 1982-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-25 | 1986-03-27 | 1986-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-25 | 1990-03-27 | 1990-09-26 | $7700.00 | Window Closed / Lapsed |