Patent US2691836A successfully refreshed from Google Patents.
Patent US3839223A successfully refreshed from Google Patents.
US4577798A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating expanded sandwich panels having an enclosed core
Assignee: Boeing North American Inc
•
Filing: 1983-11-21
•
Granted: 1986-03-25
•
Expires: 2003-11-21
Abstract
Abstract The invention concerns novel close-outs for sandwich structures and fabrication methods. The sandwich structures are formed by superplastic forming, accordion expansion, or a combination thereof. The close-out structure is formed from a plurality of flat sheets and members of predesigned shapes and sizes that are positioned in such a manner as to form high strength structures after unfolding and expansion. The corners of the close-out structure are either rounded or angled.
Inventors
- 👤 Gilles Rainville
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 05:52
CPC Classifications
B; B21; B21D; B21D47/00; Y; Y10; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T156/1003
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
237 words
A method of forming a sandwich structure with a core close-out, comprising: providing two face sheets, each face sheet having two opposed principal surfaces; providing at least one core sheet, said at least one core sheet having two opposed principal surfaces; providing at least one set of close-out sheets, each sheet of said set having two opposed principal surfaces, and having substantially the same shape, each of said close-out sheets having a pair of elongated lip portions, each of said close-out sheets having a central hole; positioning said sheets in a stack, contacting at said principal surfaces, such that said central holes of said close-out sheets are in alignment and said face sheets sandwich said close-out sheets and said at least one core sheet, said at least one core sheet being positioned within said central holes of said close-out sheets such that said close-out sheets substantially frame said at least one core sheet; joining one of said lip portions from each of said close-out sheets together; joining said other lip portion from each of said close-out sheets to the respective contacting face sheet; joining at selected areas said at least one core sheet to said face sheets; and expanding the joined stack such that the core of said sandwich structure is formed by said at least one core sheet and said close-out sheets unfold into a core close-out that extends continuously around the periphery of the core.
Claim 2
Independent Claim
237 words
A method of forming a sandwich structure with a core close-out, comprising: providing two face sheets, each face sheet having two opposed principal surfaces; providing at least one core sheet, said at least one core sheet having two opposed principal surfaces; providing at least one set of close-out sheets, each sheet of said set having two opposed principal surfaces, and having substantially the same shape, each of said close-out sheets having a pair of elongated lip portions, each of said close-out sheets having a central hole; positioning said sheets in a stack, contacting at said principal surfaces, such that said central holes of said close-out sheets are in alignment and said face sheets sandwich said close-out sheets and said at least one core sheet, said at least one core sheet being positioned within said central holes of said close-out sheets such that said close-out sheets substantially frame said at least one core sheet; joining one of said lip portions from each of said close-out sheets together; joining said other lip portion from each of said close-out sheets to the respective contacting face sheet; joining at selected areas said at least one core sheet to said face sheets; and expanding the joined stack such that the core of said sandwich structure is formed by said at least one core sheet and said close-out sheets unfold into a core close-out that extends continuously around the periphery of the core.
Claim 3
Dependent Claim
12 words
The method of claim 1 wherein said joining is by diffusion bonding.
Claim 4
Dependent Claim
14 words
The method of claim 1 wherein said sandwich structure is formed by accordion expansion.
Claim 5
Dependent Claim
16 words
The method of claim 3 wherein said formed close-out is substantially perpendicular to said face sheets.
Claim 6
Dependent Claim
108 words
The method of claim 1 wherein each of said close-out sheets is comprised of four separate portions with each portion positioned adjacent to and substantially perpendicular to two of the other portions, and also including the steps of: providing a plurality of tie members, said tie members each having two lip portions; positioning said tie members relative to said portions of said close-out sheets; and joining said portions of said close-out sheets by use of said tie members with each of said lip portions of said tie members joined to one of said close-out sheet portions; whereby said vertical core close-out has angled corners after said expanding step.
Claim 7
Dependent Claim
18 words
The method of claim 5 wherein said close-out sheets stretch less than fifteen percent during said expanding step.
Claim 8
Dependent Claim
25 words
The method of claim 1 wherein said close-out sheets have arcuate corners such that said vertical core close-out has arcuate corners after said expanding step.
Claim 9
Dependent Claim
27 words
The method of claim 7 wherein said close-out sheets stretch more than fifteen percent but less than thirty-five percent at the arcuate corners during said expanding step.
Claim 10
Dependent Claim
28 words
The method of claim 8 wherein said close-out sheets other than in the area approximately at said arcuate corners stretch less than fifteen percent during said expanding step.
Claim 11
Dependent Claim
24 words
The method of claim 1 wherein there are two core sheets and also including joining at selected areas said core sheets to each other.
Claim 12
Dependent Claim
16 words
The method of claim 10 wherein said formed close-out is substantially perpendicular to said face sheets.
Claim 13
Dependent Claim
16 words
The method of claim 1 wherein said formed close-out is substantially perpendicular to said face sheets.
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) | 1989-03-24 | 1989-09-23 | 1990-03-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-24 | 1993-09-23 | 1994-03-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-24 | 1997-09-23 | 1998-03-25 | $7700.00 | Window Closed / Lapsed |