Howmet Research Corporation

Howmet Corporation

Dennis J Thompson

John R Brinegar

Mark L Soderstrom

Mark J Straszheim

Dale A Grumm

Bradley S Donaldson

Dean L Schmiedeknecht

Brad L Rauguth

Method as well as apparatus for DS casting using a multi-stage thermal baffle disposed proximate a lower end of a DS casting furnace. The thermal baffle comprises a fixed primary baffle disposed at the lower end of the casting furnace and a secondary baffle initially releasably disposed adjacent and below the primary baffle prior to withdrawal of the melt-filled mold from the casting furnace. The primary baffle includes a primary aperture oriented perpendicular to the mold withdrawal direction and having a cross-sectional configuration tailored to accommodate a relatively large exterior region or profile of the melt-filled mold, such as a relatively wide platform region of a mold for making a turbine blade or vane. The secondary baffle includes a secondary aperture also oriented perpendicular to the mold withdrawal direction and having a cross-sectional configuration tailored to accommodate a relatively smaller exterior region or profile of the melt-filled mold, such as a narrower airfoil region of a mold for making a turbine blade or vane. The secondary baffle remains adjacent and immediately below the primary baffle during withdrawal of the mold from the furnace until the relatively larger region of the melt-filled mold passes through the primary aperture in a manner to release or disengage the secondary baffle from a temporary baffle support means to allow the secondary baffle to drop or move downwardly onto the chill plate for continued movement therewith as the melt-filled mold continues to be withdrawn from the furnace.

Directional solidification method and apparatus

A gas permeable ceramic investment mold is disposed in a casting chamber and filled with melt to be solidified via a mold melt inlet, such as for example a mold pour cup adapted to receive the melt from a melting crucible in the casting chamber. After the melt is cast into the hot investment mold in the vacuum casting chamber, a pressure cap is positioned in sealing engagement with the mold melt inlet, and gas pressure is introduced through the pressure cap to provide selective or local gas pressure on the melt in the mold without pressure cracking or other damage to the relatively fragile investment mold, while the casting chamber is maintained under relative vacuum or a different pressure from that in the mold.

Investment casting using pressure cap sealable on gas permeable

A method of making a directionally solidified casting by casting a melt in a mold cavity of an investment mold having a core therein to form an internal casting surface feature involves evacuting the mold cavity while the investment mold is disposed on a chill member with the mold cavity communicating to the chill member, and introducing the melt into the evacuted mold cavity about the core so that the melt contacts the chill member for unidirectional heat removal and directional solidification. Then, gaseous pressure is applied to the melt cast in the mold cavity rapidly enough after introduction in the mold cavity to reduce localized void regions present in the cast melt as a result of surface tension effects between the melt and the core.

Investment casting with improved filling

A thermocouple positioning device is provided for a directional solidification casting apparatus having a furnace for receiving a mold disposed on a chill plate that, in turn, is carried on a movable ram. The thermocouple positioning device comprises a support bracket disposed on the ram for movement therewith. The bracket includes an upstanding slide member and a slideway member disposed on the slide member and having a thermocouple holder thereon. A stop member is disposed in fixed position below the furnace for releasably engaging a stop engaging member on the slideway member as the ram is raised to position the mold in the furnace. Engagement between the stop member and the stop engaging member as the ram is raised positions the thermocouple in a temperature sensing position relative to the mold in the furnace. The thermocouple remains at the temperature sensing position as the mold is withdrawn from the furnace to effect directional solidification of the melt in the mold to form a columnar or single crystal casting in the mold.

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Whitehall, MI, United States of America

Dennis J Thompson