Metal founding – Process – Shaping liquid metal against a forming surface
Patent
1986-03-21
1987-06-16
Godici, Nicholas P.
Metal founding
Process
Shaping liquid metal against a forming surface
164127, 164129, 164133, 164137, 1643381, 164339, 164353, 164361, B22D 2704
Patent
active
046730214
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention provides a new and improved mold and method of using the mold to cast a plurality of articles.
Heat treatment of single crystal cast articles is facilitated if the articles are solidified with a fine dendritic structure. In an effort to obtain a relatively fine dendritic structure during the casting of the articles, U.S. Pat. Nos. 3,763,926 and 4,108,236 suggest that a large temperature gradient be established as a mold is withdrawn from a furnace. This is done by having the mold immersed in a bath of liquid coolant. To increase the temperature gradient during withdrawal of a mold from a furnace, U.S. Pat. No. 4,108,236 suggests that an insulated baffle be provided between the inside of the furnace and the liquid coolant bath.
The concept of using an annular molten metal distribution system which allows a mold to be completely withdrawn from a furnace past a baffle is disclosed in U.S. Pat. No. 3,810,504. In this patent, an annular array of article molds and the annular molten metal distribution system are supported in the furnace on an annular chill plate. The furnace has a cylindrical outer heater which circumscribes the mold and a cylindrical inner heater which is circumscribed by the mold. During withdrawal of the mold from the furnace, the mold moves downwardly between inner and outer heat sinks. The combination of inner and outer heaters, an annular chill plate, and inner and outer heat sinks results in a relatively complicated apparatus which is difficult to operate and maintain.
SUMMARY OF THE INVENTION
The present invention is directed to a method and apparatus to provide a relatively large temperature gradient between the inside and outside of a furnace as a mold is withdrawn from the furnace. The large temperature gradient is maintained, without a liquid coolant bath, even though article molds are disposed in an annular array having a relatively large diameter. The obtaining of the large temperature gradient is promoted by a baffle which blocks the radiation of heat from a central portion of the annular array of article molds to the outside of the furnace as the article molds are withdrawn from the furnace. The use of the baffle promotes the formation of horizontal isotherms with a relatively high temperature gradient for each unit length of portions of the article molds as they are withdrawn from the furnace.
The improved apparatus includes a plurality of article molds which are disposed in an annular array having an open central portion. Molten metal is distributed to the article molds through a primary distribution system which is separate from the article molds, a secondary distribution system which is connected with the article molds, and a plurality of separable joints which interconnect the primary and secondary distribution systems. The joints conduct molten metal from the primary distribution system to the secondary distribution system and allow the article molds to be moved away from the primary distribution system after the article molds have been filled with molten metal. The baffle is supported by the primary distribution system and blocks the radiation of heat through the open central portion of the annular array of article molds as they are withdrawn from the furnace.
In order to support the primary distribution system and baffle in the furnace during withdrawal of the annular array of article molds from the furnace, the primary distribution system is connected with the furnace. During pouring of molten metal into a pour cup in the primary distribution system, the article molds are supported on a chill plate. Reaction forces are transmitted from the pour cup to the chill plate through a support post and baffle. During withdrawal of the article molds from the furnace, the post supports the baffle in the central portion of the annular array of article molds.
Accordingly, it is an object of the present invention to provide a new and improved method and apparatus for casting a plurality of articles and wherein a relatively large te
REFERENCES:
patent: 3376915 (1968-04-01), Chandley
patent: 3598167 (1971-08-01), Snyderman
patent: 3680625 (1972-08-01), Hein et al.
patent: 3763926 (1973-10-01), Tschinkel et al.
patent: 3810504 (1974-05-01), Piwonka
patent: 4108236 (1978-08-01), Salkeld
patent: 4315537 (1982-02-01), Blazek
patent: 4409451 (1983-10-01), Taylor
patent: 4550764 (1985-11-01), Horton et al.
Ardo Ronald
Fetsko Daniel G.
Graham Lawrence D.
Skelley Richard A.
Godici Nicholas P.
Seidel Richard K.
TRW Inc.
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