Vacuum countergravity casting apparatus and method

摘要

Vacuum countergravity casting apparatus and process employ a container having a peripheral wall defining an open bottom chamber that receives one or more molds or destructible patterns. A first inherently unstable mass of particulates (e.g., binderless sand) is disposed in the chamber about the molds/patterns and a second supportive mass of bonded particulates (e.g., resin-bonded sand) is disposed in the chamber about the molds/patterns beneath the first mass. The second supportive mass is strong enough to support the first mass and preferably the molds/patterns as well as castings ultimately formed as necessary during the casting operation in the event of intentional or unexpected interruption of a negative differential pressure established between the inside and outside of the container.