US3771233A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic enhancement of evaporation
Assignee: Northrop Grumman Space and Mission Systems Corp
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Filing: 1972-01-14
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Granted: 1973-11-13
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Expires: 1992-01-14
Abstract
Abstract By applying high voltage D.C. discharge to a liquid or solid mass containing liquid, the surface of which is in contact with a circulating gaseous atmosphere such as air, evaporation of the liquid is promoted, due to turbulence of the atmosphere brought about by the discharge adjacent the surface of the body from which the liquid is evaporated. This phenomenon is particularly useful in removing moisture from irregular shaped bodies such as investment casting shell molds which require uniform drying in order to improve strength and mitigate cracking. Drying rate is increased without the attendant disadvantages experienced when attempts are made to increase drying rates using conventional drying techniques such as oven and tunnel drying.
Inventors
- 👤 P French
- 👤 Piwonka T Squire
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:08
CPC Classifications
B; B22; B22C; B22C9/00; B22C9/12; B28; B28B; B28B1/00; B28B1/54; B28B7/00; B28B7/40; B28B7/46; F; F26; F26B; F26B3/00; F26B3/32; F26B3/34; F26B3/343; Y; Y10; Y10S; Y10S159/00; Y10S159/26
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
140 words
The method of removing moisture from investment casting ceramic shell molds comprising removing moisture from the mold by subjecting it to air drying at a temperature sufficiently low to avoid cracking and simultaneously applying to the mold a high voltage D.C. electrostatic charge uniformly distributed over the surface of the mold by placing a plurality of needle-like electrodes in uniformly spaced relation about the entire surface of the mold, said electrodes being connected to one pole of a high voltage D.C. current source and the mold being connected to the other pole of said source, said electrodes being spaced from each other a distance sufficient to avoid discharge therebetween and at a sufficient distance from the mold surface to avoid sparking, thereby to dry the mold uniformly and increase the rate of drying of the mold without causing cracking thereof.
Claim 2
Independent Claim
140 words
The method of removing moisture from investment casting ceramic shell molds comprising removing moisture from the mold by subjecting it to air drying at a temperature sufficiently low to avoid cracking and simultaneously applying to the mold a high voltage D.C. electrostatic charge uniformly distributed over the surface of the mold by placing a plurality of needle-like electrodes in uniformly spaced relation about the entire surface of the mold, said electrodes being connected to one pole of a high voltage D.C. current source and the mold being connected to the other pole of said source, said electrodes being spaced from each other a distance sufficient to avoid discharge therebetween and at a sufficient distance from the mold surface to avoid sparking, thereby to dry the mold uniformly and increase the rate of drying of the mold without causing cracking thereof.
Claim 3
Dependent Claim
28 words
The method in accordance with claim 1 in which the current in the circuit is sufficiently small so as not to produce any substantial heating of the mass.
Claim 4
Dependent Claim
18 words
The method in accordance with claim 2 in which the voltage is between approximately 20 and 60 KV.
Claim 5
Dependent Claim
15 words
The method in accordance with claim 3 in which the current is about 2 milliamps.
Claim 6
Dependent Claim
33 words
The method in accordance with claim 2 in which the needle-like electrodes are spaced about the mold with the tips of the needles spaced not less than about 3 inches from the mold.
Claim 7
Dependent Claim
23 words
The method in accordance with claim 1 in which the mold is simultaneously heated to a temperature between about 80* and 108* F.
Claim 8
Dependent Claim
30 words
The method in accordance with claim 2 in which the voltage is of sufficient magnitude to cause turbulence of the gaseous atmosphere in contact with the surface of the mold.
References Cited (Backward Citations)
US3398322A
Cited
US3358378A
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US3448323A
Cited
US3456359A
Cited
US3491456A
Cited
US3703665A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-12 | 1977-05-14 | 1977-11-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-12 | 1981-05-14 | 1981-11-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-12 | 1985-05-14 | 1985-11-13 | $7700.00 | Window Closed / Lapsed |