US3908733A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for control of alloy in columnar grain castings
Assignee: RTX Corp
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Filing: 1973-10-26
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Granted: 1975-09-30
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Expires: 1993-10-26
Abstract
Abstract A method and a mold for casting high temperature alloys having as an ingredient an element that reacts with the mold and core material and is thereby depleted during alloy solidification. A reservoir which is shaped to minimize depletion of the element is positioned above the article cavity in the mold to supply alloy to the top of the article cavity. As solidification proceeds, the molten alloy in the reservoir serves to enrich the solidifying alloy in the article forming portion of the mold with the depleted reactive ingredient.
Inventors
- 👤 Geoffrey R Brazer
- 👤 Patrick M Curran
- 👤 Bruce E Terkelsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:09
CPC Classifications
B; B22; B22D; B22D27/00; B22D27/04; B22D27/045
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
198 words
In the manufacture of columnar grained cast articles from a high temperature alloy having as an ingredient an element that reacts with the mold material the steps of: making a mold having an article cavity and a large secondary cavity directly above the article cavity and directly communicating therewith with the second cavity acting as a reservoir and having a large volume-to-surface ratio to minimize depletion of the ingredient by the reaction between the alloy in the reservoir and the mold material the connection from the article cavity to the secondary cavity increasing in dimension in all directions from the maximum area of the article cavity at the top to the larger in-area secondary cavity, the connection providing a gradual blending from the top of the article cavity to the secondary cavity; positioning the mold on a chill plate; filling the mold including both cavities with a molten high temperature alloy; solidifying the alloy from the chill plate upward to form one or more columnar grains therein; and causing a convective flow in the molten alloy such that the molten alloy in the secondary cavity replenishes the depleted ingredient in the alloy in the article cavity during solidification.
Claim 2
Dependent Claim
198 words
In the manufacture of columnar grained cast articles from a high temperature alloy having as an ingredient an element that reacts with the mold material the steps of: making a mold having an article cavity and a large secondary cavity directly above the article cavity and directly communicating therewith with the second cavity acting as a reservoir and having a large volume-to-surface ratio to minimize depletion of the ingredient by the reaction between the alloy in the reservoir and the mold material the connection from the article cavity to the secondary cavity increasing in dimension in all directions from the maximum area of the article cavity at the top to the larger in-area secondary cavity, the connection providing a gradual blending from the top of the article cavity to the secondary cavity; positioning the mold on a chill plate; filling the mold including both cavities with a molten high temperature alloy; solidifying the alloy from the chill plate upward to form one or more columnar grains therein; and causing a convective flow in the molten alloy such that the molten alloy in the secondary cavity replenishes the depleted ingredient in the alloy in the article cavity during solidification.
Claim 3
Dependent Claim
11 words
The process of claim 1 in which the ingredient is hafnium.
Claim 4
Dependent Claim
31 words
The process of claim 1 in which the temperature of the mold is reduced from bottom to top of the mold as the alloy solidifies to produce the columnar grained structure.
Claim 5
Dependent Claim
58 words
The process of claim 1 in which the cast article is a turbine blade so that the article cavity of the mold has an airfoil shaped portion and the secondary cavity communicates with the upper end of the airfoil portion and is also airfoil shape and larger in cross section than the upper end of the article cavity.
Claim 6
Dependent Claim
165 words
The mold for casting gas turbine blades from high temperature alloys having as an ingredient an element that reacts with the mold material and is thereby depleted during solidification, said mold including: a base portion having a growth zone cavity therein; a root cavity above and communicating with the growth zone cavity; an airfoil shaped cavity above and communicating with the root cavity; and a large reservoir cavity directly above and communicating directly with the airfoil shaped cavity, the communication gradually increasing in dimension in all lateral directions from bottom to top, said reservoir cavity being shaped to have a large volume-to-surface area ratio, and being large enough to prevent depletion of the reactive element therein below the required amount during solidification of the alloy, said reservoir cavity being greater in all lateral directions from the maximum area of the top of the airfoil cavity and the communication providing a gradual blending of dimension from the top of the airfoil cavity to the reservoir cavity.
Claim 7
Dependent Claim
165 words
The mold for casting gas turbine blades from high temperature alloys having as an ingredient an element that reacts with the mold material and is thereby depleted during solidification, said mold including: a base portion having a growth zone cavity therein; a root cavity above and communicating with the growth zone cavity; an airfoil shaped cavity above and communicating with the root cavity; and a large reservoir cavity directly above and communicating directly with the airfoil shaped cavity, the communication gradually increasing in dimension in all lateral directions from bottom to top, said reservoir cavity being shaped to have a large volume-to-surface area ratio, and being large enough to prevent depletion of the reactive element therein below the required amount during solidification of the alloy, said reservoir cavity being greater in all lateral directions from the maximum area of the top of the airfoil cavity and the communication providing a gradual blending of dimension from the top of the airfoil cavity to the reservoir cavity.
Claim 8
Dependent Claim
47 words
A mold as in claim 5 in which the reservoir cavity is also an airfoil shape and larger in cross sectional area than the end of the blade cavity communicating therewith said secondary cavity extending laterally in all directions beyond the top of the airfoil shaped cavity.
Claim 9
Dependent Claim
21 words
A mold as in claim 5 in which the bottom of the mold is open to rest on a chill plate.
Claim 10
Dependent Claim
31 words
A mold as in claim 5 in which the reservoir is similar in cross section to and communicates with the entire cross section of the tip of the airfoil shaped cavity.
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) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |