Patent US4684937A successfully refreshed from Google Patents.
US3757735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vacuum holder to conform casting surface
Assignee: BASF Corp
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Filing: 1973-02-02
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Granted: 1973-09-11
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Expires: 1993-02-02
Abstract
Abstract A process and apparatus are provided for flattening a metal sheet having a sinuous cross-section while it is supported from below against buckling by withdrawing air from beneath the sheet until atmospheric pressure above the sheet firmly presses it against the support substantially free from undulations and for casting a film of substantially uniform thickness on the exposed surface of the flattened sheet.
Inventors
- 👤 G Crowe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 05:20
CPC Classifications
B; B29; B29C; B29C33/00; B05; B05C; B05C9/00; B05C9/08; B29D; B29D7/00; B29D7/01
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
105 words
In combination, an apparatus comprising a support having a substantially air impervious surface, a substantially air impervious wall extending upwardly from the support and about a region having an open top, air pervious means within said region providing a plurality of points spaced upwardly above the impervious surface a distance substantially equal to the height of the wall whereby a substantially flat cover over the open top would be supported by the wall and the points, a flexible sheet having a sinuous cross-section covering the open top, and means for withdrawing air from the region until the undulated sheet is substantially flattened against the support.
Claim 2
Dependent Claim
105 words
In combination, an apparatus comprising a support having a substantially air impervious surface, a substantially air impervious wall extending upwardly from the support and about a region having an open top, air pervious means within said region providing a plurality of points spaced upwardly above the impervious surface a distance substantially equal to the height of the wall whereby a substantially flat cover over the open top would be supported by the wall and the points, a flexible sheet having a sinuous cross-section covering the open top, and means for withdrawing air from the region until the undulated sheet is substantially flattened against the support.
Claim 3
Dependent Claim
31 words
The apparatus of claim 1 wherein the wall is a gasket adhered to the under surface of the flexible sheet and the air pervious means is an unflattened, expanded metal sheet.
Claim 4
Dependent Claim
11 words
The apparatus of claim 2 wherein the sinuous sheet is metal.
Claim 5
Dependent Claim
45 words
The apparatus of claim 3 wherein the means fOr withdrawing air is a combination of an exhaust fan adapted to remove large volumes of air rapidly and a vacuum pump adapted to reduce the air pressure to a point where it approaches a complete vacuum.
Claim 6
Dependent Claim
122 words
In combination, an apparatus comprising a support having a substantially air impervious surface, a substantially air impervious wall extending upwardly from the support and about a region having an open top, air pervious means within said region providing a plurality of points spaced upwardly above the impervious surface a distance substantially equal to the height of the wall whereby a substantially flat cover over the open top would be supported by the wall and the points, a flexible sheet having a sinuous cross-section covering the open top, means for withdrawing air from the region until the undulated sheet is substantially flattened against the support, means for heating the sheet and a means for casting a film over the surface of the sheet.
Claim 7
Dependent Claim
122 words
In combination, an apparatus comprising a support having a substantially air impervious surface, a substantially air impervious wall extending upwardly from the support and about a region having an open top, air pervious means within said region providing a plurality of points spaced upwardly above the impervious surface a distance substantially equal to the height of the wall whereby a substantially flat cover over the open top would be supported by the wall and the points, a flexible sheet having a sinuous cross-section covering the open top, means for withdrawing air from the region until the undulated sheet is substantially flattened against the support, means for heating the sheet and a means for casting a film over the surface of the sheet.
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) | 1976-09-10 | 1977-03-12 | 1977-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-10 | 1981-03-12 | 1981-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-10 | 1985-03-12 | 1985-09-11 | $7700.00 | Window Closed / Lapsed |