Patent US3110749A successfully refreshed from Google Patents.
Patent US3864797A successfully refreshed from Google Patents.
US3864797A
Expired / Lapsed
US
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Method of making dished ion thruster grids
Assignee: National Aeronautics and Space Administration
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Filing: 1973-04-18
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Granted: 1975-02-11
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Expires: 1993-04-18
Abstract
Abstract A pair of flat grid blanks are clamped together at their edges with an impervious metal sheet on top. All of the blanks and sheets are dished simultaneously by forcing fluid to inflate an elastic sheet which contacts the bottom grid blank. A second impervious metal sheet is inserted between the two grid blanks if the grids have high percentage open areas. The dished grids are stress relieved simultaneously.
Inventors
- 👤 Bruce A Banks
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:51
CPC Classifications
F; F03; F03H; F03H1/00; F03H1/0037; F03H1/0043; H; H01; H01J; H01J19/00; H01J2893/00; H01J2893/0001; H01J2893/0012; H01J2893/0019; H01J2893/0022
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
120 words
A method of forming matched pairs of dished grids to a substantially hemispheroidal configuration for ion thruster accelerator systems comprising the steps of placing an elastic sheet on a rigid base member, aligning a pair of substantially flat grid blanks to form an assembly with said elastic sheet, clamping the marginal peripheral portions of said assembly with a ring to prevent slippage of said assembly and to form an expansible fluid chamber between said elastic sheet and said rigid base member, applying a fluid pressure to said elastic material thereby inflating the same whereby said blanks are dished to the curvature of said inflated elastic material, removing the dished grids from said assembly, and stress relieving said dished grids simultaneously.
Claim 2
Independent Claim
120 words
A method of forming matched pairs of dished grids to a substantially hemispheroidal configuration for ion thruster accelerator systems comprising the steps of placing an elastic sheet on a rigid base member, aligning a pair of substantially flat grid blanks to form an assembly with said elastic sheet, clamping the marginal peripheral portions of said assembly with a ring to prevent slippage of said assembly and to form an expansible fluid chamber between said elastic sheet and said rigid base member, applying a fluid pressure to said elastic material thereby inflating the same whereby said blanks are dished to the curvature of said inflated elastic material, removing the dished grids from said assembly, and stress relieving said dished grids simultaneously.
Claim 3
Dependent Claim
56 words
A method of forming matched pairs of dished grids as claimed in claim 1 including the step of covering the aligned grid blanks with a substantially flat sheet of impervious metal so that said impervious metal is in engagement with the other of said grid blanks opposite the elastic material to prevent catastrophic rupture during dishing.
Claim 4
Dependent Claim
46 words
A method of forming matched pairs of dished grids as claimed in claim 2 including the step of interposing a second substantially flat sheet of impervious metal between the grid metal blanks to prevent distortion caused by slight misalignment of apertures in the grids during dishing.
Claim 5
Dependent Claim
29 words
A method of forming matched pairs of dished grids as claimed in claim 1 wherein at least one of the grid blanks has a thickness less than 0.5 millimeter.
Claim 6
Dependent Claim
20 words
A method of forming matched pairs of dished grids as claimed in claim 4 wherein the grid blank is molybdenum.
Claim 7
Dependent Claim
35 words
A method of forming matched pairs of grids as claimed in claim 1 including stress relieving the grids after dishing by heating the same to a temperature of about 1,750* F for about 1 hour.
Claim 8
Dependent Claim
25 words
A method of forming matched pairs of grids as claimed in claim 1 including the step of forming holes in the grid blanks after dishing.
Claim 9
Dependent Claim
21 words
A method of forming matched pairs of grids as claimed in claim 7 wherein the holes are formed by chemical etching.
References Cited (Backward Citations)
US1329969A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-10 | 1978-08-12 | 1979-02-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-10 | 1982-08-12 | 1983-02-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-10 | 1986-08-12 | 1987-02-11 | $7700.00 | Window Closed / Lapsed |