Method of vacuum casting

• US 5,111,871 A
• Filed: 11/01/1990
• Issued: 05/12/1992
• Est. Priority Date: 03/17/1989
• Status: Expired due to Fees

• Current Assignee: PCC Composites, Inc. (ARC Group Worldwide, Inc.)
• Original Assignee: Pcast Equipment Corporation
• Inventors: Cook, Arnold J.
• Primary Examiner(s): BATTEN JR, J REED
• Application Number:
  US07/607,847
• Time in Patent Office: 558 Days
• Field of Search: 164/61, 164/63, 164/254, 164/255, 164/256, 164/337, 164/97, 164/119, 164/66.1, 164/68.1, 164/259, 164/284, 164/306, 164/309, 164/126, 164/127, 164/410, 164/348
• US Class Current: 164/63
• CPC Class Codes: B22D 18/04 Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
• CPC Class Codes: B22D 18/06 Vacuum casting, i.e. making use of vacuum to fill the mould
• CPC Class Codes: B22D 19/14 the objects being filamentary or particulate in form making alloys containing fibres or filaments by contacting the fibres or filaments with molten metal C22C47/08

Abstract

A porous preform is placed within a permanent, nonporous, thin walled mold chamber. The mold chamber is disposed within a pressure vessel. A material is placed in a crucible of the pressure vessel. The pressure vessel is evacuated through a snorkel fluidically connected to the mold chamber. There is means for cooling the snorkel in thermal communication with the snorkel. The material is melted within the crucible. The crucible is placed in fluidic communication with the mold chamber such that the melted material seals the inside of the mold chamber from the pressure vessel to isolate a vacuum within the mold chamber. Finally, the vessel is pressurized at a controlled rate such that the pressure in the mold chamber is able to have time to be driven towards equilibrium with the vessel and therefore allowing differential pressure control while the mold chamber is continually evacuated such that the melted material is drawn into the mold chamber and seals the snorkel by forming a solidification plug and the melted material is forced into the porous preform.

Claims

1. A method for casting comprising the steps of:

placing a porous preform in a permanent, nonporous, thin walled mold chamber of a pressure vessel;

placing a material in a crucible of the pressure vessel;

evacuating the pressure vessel through a snorkel fluidically connected to the mold chamber and extending therefrom out of the pressure vessel;

melting the material in the crucible;

placing the crucible in fluidic communication with the mold chamber such that the melted material fluidically seals the inside of the mold chamber and the snorkel from the interior of the pressure vessel to fluidically isolate the mold chamber from the interior of the pressure vessel so that a pressure differential exists therebetween;

pressurizing the vessel at a controlled rate such that the pressure in the mold chamber is able to have time to be driven towards equilibrium with the vessel and therefore allowing differential pressure control while the mold chamber is continuously evacuated, such that the melted material is drawn into the mold chamber and into the snorkel where solidifying means in thermal communication with the snorkel cools the melted material within the snorkel thereby forming a solidification plug and the material is forced into the porous preform.

2. A method as described in claim 1 including the step of cooling the preform with the melted material forced therein.

3. A method as described in claim 2 including before the cooling step, the step of solidifying directionally the melted material in the preform.