US3689345A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making a quasi-isotropic sandwich core
Assignee: United States Department of the Army
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Filing: 1970-05-20
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Granted: 1972-09-05
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Expires: 1990-05-20
Abstract
Abstract A STRUCTURAL CORE CONSISTING OF UPPER AND LOWER SHEETS OF A FIBERGLAS OR LIKE MATERIAL. EACH SHEET DEFINES PARALLEL ROWS OF RAISED, TETRAHEDRONAL SHAPED, HOLLOW KNOBS. THE UPPER SHEET IS INVERTED OVER THE LOWER ONE SO THAT THE EDGES OF THE TETRAHEDRONS ABUT WHEREBY ALL TETRAHEDRONS
Inventors
- 👤 Irving E Figge
- 👤 Bernard L Karp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 06:13
CPC Classifications
B; B31; B31B; B31B50/00; B31D; B31D5/00; B31D5/04; Y; Y10; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T156/1039; Y10T428/00; Y10T428/24; Y10T428/24149; Y10T428/24628; Y10T428/24669
Claims Analysis
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-05 | 1976-03-06 | 1976-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-05 | 1980-03-06 | 1980-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-05 | 1984-03-06 | 1984-09-05 | $7700.00 | Window Closed / Lapsed |