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Lost foam casting of dual alloy engine block

  • US 5,000,244 A
  • Filed: 12/04/1989
  • Issued: 03/19/1991
  • Est. Priority Date: 12/04/1989
  • Status: Expired due to Fees
First Claim
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1. A lost foam casting process for producing a compound alloy engine block casting, said engine block casting comprising a crankcase section, a cylinder wall section extending from the crankcase section and a water jacket wall also extending from the crankcase section about the cylinder wall section but spaced apart therefrom, said cylinder wall section defining at least one cylinder bore and having a piston-travel region adjacent an outer end remote from the crankcase section, said engine block casting being formed of a plurality of metal alloys such that said cylinder wall piston-travel region is composed of a first alloy and said crankcase section and said water jacket wall are composed of a second alloy, said process comprisingembedding in an unbonded particulate mold an expendable pattern comprising a product form substantially sized and shaped to produce the engine block casting and having portions corresponding to the crankcase section, the cylinder wall section and the water jacket wall, said pattern further comprising a first runner system including a melt pour surface and connected to the cylinder wall portion for conveying molten metal from the melt pour surface to the cylinder wall portion, and a second runner system including a melt pour surface distinct from the first runner system melt pour surface and connected to the water jacket wall portion for conveying molten metal from the second runner system melt pour surface to the water jacket wall portion, said pattern being formed of a polymeric material thermally decomposable at metal casting temperatures and embedded in the mold such that the first runner system melt pour surface and the second runner system melt pour surface are exposed and spaced apart for independent contact with cast metal,casting molten first alloy into contact with the first runner system melt pour surface to decompose and replace at least the piston-travel region,concurrently casting molten second alloy into contact with the second runner system melt pour surface to decompose and replace the water jacket wall portion and the crankcase portion, said casting of said alloys continuing so as to decompose and replace the entire pattern, whereupon the alloys flow together,solidifying the cast alloys to form the engine block casting, whereupon the alloys fuse to produce an integral engine block casting, andremoving the engine block casting from the mold, and separating runner replacement metal from the engine block casting.

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