US4588651A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Accordion expansion process
Assignee: Boeing North American Inc
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Filing: 1983-02-16
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Granted: 1986-05-13
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Expires: 2003-02-16
Abstract
Abstract A novel method of forming complex structures by using an accordion expansion process is disclosed. The process involves a plurality of flat workpieces of predesigned shapes and sizes that are positioned in such a manner, that after the workpieces have been first joined together, they are expanded to form high strength structural members of complex design.
Inventors
- 👤 Leonardo Israeli
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 23:03
CPC Classifications
B; B21; B21D; B21D47/00; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49826; Y10T29/49861; Y10T428/00; Y10T428/12; Y10T428/12347
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
156 words
A method of forming sandwich structures from a plurality of workpieces by accordion expansion, comprising: providing two outer workpieces, each of said outer workpieces having two opposed principal surfaces; providing at least two core workpieces, each of said core workpieces having two opposed principal surfaces; positioning said workpieces in a stack contacting at their principal surfaces, such that said outer workpieces sandwich said core workpieces and at least one core workpiece is superimposed over another core workpiece; joining at selective areas said core workpieces to each other and to said outer workpieces, said joined areas on opposite outer workpieces being out of vertical alignment; and expanding said joined stack by pressure means into a die, such that said core workpieces unfold and form an inclined web relative to said outer workpieces, with said joined core workpieces being substantially in linear alignment, and such that no one of said core workpieces contacts both of said outer workpieces.
Claim 2
Independent Claim
156 words
A method of forming sandwich structures from a plurality of workpieces by accordion expansion, comprising: providing two outer workpieces, each of said outer workpieces having two opposed principal surfaces; providing at least two core workpieces, each of said core workpieces having two opposed principal surfaces; positioning said workpieces in a stack contacting at their principal surfaces, such that said outer workpieces sandwich said core workpieces and at least one core workpiece is superimposed over another core workpiece; joining at selective areas said core workpieces to each other and to said outer workpieces, said joined areas on opposite outer workpieces being out of vertical alignment; and expanding said joined stack by pressure means into a die, such that said core workpieces unfold and form an inclined web relative to said outer workpieces, with said joined core workpieces being substantially in linear alignment, and such that no one of said core workpieces contacts both of said outer workpieces.
Claim 3
Dependent Claim
19 words
The method of forming a sandwich structure as recited in claim 1 wherein said joining is by diffusion bonding.
Claim 4
Dependent Claim
29 words
The method of forming a sandwich structure as recited in claim 1 wherein said core workpieces are sheets having cutout portions therein that form a plurality of parallel strips.
Claim 5
Dependent Claim
37 words
The method of forming a sandwich structure as recited in claim 3 wherein said sheets with cutout portions have slivers of sheet material that extend through said cutout portions, and said slivers rupture during said forming process.
Claim 6
Dependent Claim
28 words
The method of forming a sandwich structure as recited in claim 1 wherein said workpieces have substantially the same outer shape and are positioned evenly in said stack.
Claim 7
Dependent Claim
41 words
The method of forming a sandwich structure as recited in claim 1 also including the step of heating said stack to within an elevated temperature range, and wherein said expanding step is performed while said stack is within said temperature range.
Claim 8
Dependent Claim
31 words
The method of forming a sandwich structure as recited in claim 6 wherein said core workpieces are elongated during the expansion step, with the elongation being no more than 15 percent.
Claim 9
Dependent Claim
13 words
The sandwich structure that is formed by the process recited in claim 1.
Claim 10
Dependent Claim
40 words
The method of forming a sandwich structure as recited in claim 1 wherein at least one of said outer workpieces fit into an oblique surface of said forming chamber and form and outer workpiece, with at least an oblique portion.
Claim 11
Dependent Claim
24 words
The method of forming a sandwich structure as recited in claim 1 wherein said core workpieces joined together in linear alignment have different lengths.
Claim 12
Dependent Claim
61 words
The method of forming a sandwich structure as recited in claim 1 wherein said core workpieces have lengths substantially in accordance with the following relationships: ##EQU2## where L 1 and L 2 are the lengths of said core workpieces, t is the distance between said outer workpieces, and θ is the acute angle between said core workpieces and said outer workpieces.
Claim 13
Independent Claim
153 words
A method of forming stiffened panel structures from a plurality of workpieces by accordion expansion, comprising: providing a plurality of workpieces, each of said workpieces having two opposed principal surfaces, with a bottom workpiece and at least two of said workpieces being core workpieces; positioning said workpieces in a stack contacting at their principal surfaces such that at least one core workpiece is superimposed over another core workpiece; joining at selected locations said core workpieces to each other and to said bottom workpiece; and bringing said workpieces into an elevated temperature range which would allow for stretching deformation of said core workpieces; inflating the joined stack such that the core workpieces unfold in a free form manner and deflect away from said bottom workpiece; and applying pressure within said joined stack while said workpieces are within said temperature range and after said core workpieces have unfolded such that said core workpieces are elongated.
Claim 14
Independent Claim
153 words
A method of forming stiffened panel structures from a plurality of workpieces by accordion expansion, comprising: providing a plurality of workpieces, each of said workpieces having two opposed principal surfaces, with a bottom workpiece and at least two of said workpieces being core workpieces; positioning said workpieces in a stack contacting at their principal surfaces such that at least one core workpiece is superimposed over another core workpiece; joining at selected locations said core workpieces to each other and to said bottom workpiece; and bringing said workpieces into an elevated temperature range which would allow for stretching deformation of said core workpieces; inflating the joined stack such that the core workpieces unfold in a free form manner and deflect away from said bottom workpiece; and applying pressure within said joined stack while said workpieces are within said temperature range and after said core workpieces have unfolded such that said core workpieces are elongated.
Claim 15
Dependent Claim
20 words
The method of forming a stiffened panel structure as recited in claim 12 wherein said joining is by diffusion bonding.
Claim 16
Dependent Claim
29 words
The method of forming a stiffened panel structure as recited in claim 12 wherein said core workpieces are sheets with cutout portions that form a plurality of parallel strips.
Claim 17
Dependent Claim
37 words
The method of forming a stiffened panel structure as recited in claim 14 wherein said sheets with cutout portions have slivers of material that extend through said cutout portions, and said slivers rupture during the forming process.
Claim 18
Dependent Claim
27 words
The method of forming a stiffened panel structure as recited in claim 12 wherein said inflating step is performed while said stack is within said temperature range.
Claim 19
Dependent Claim
20 words
The method of forming a panel structure as recited in claim 12 wherein said core workpieces form a curved surface.
Claim 20
Dependent Claim
14 words
The stiffened panel structure that is formed by the process recited in claim 12.
Claim 21
Dependent Claim
18 words
The method of claim 12 wherein said elongation of said core workpieces is no more than 15 percent.
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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) | 1989-05-12 | 1989-11-11 | 1990-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-12 | 1993-11-11 | 1994-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-12 | 1997-11-11 | 1998-05-13 | $7700.00 | Window Closed / Lapsed |