Abstract: Foundry apparatus for mixing sand with binder ingredients to produce a composite mixture suitable for foundry molds includes a first premixing chamber enclosing a first bladed shaft mounted for rotation about a substantially horizontal first axis operable for conveying and commingling sand with a first binder ingredient to produce a first sand/binder ingredient mixture. A second premixing chamber, separate from the first premixing chamber, encloses a second bladed shaft mounted for counterrotation about a second axis, substantially parallel to the first axis, for conveying and commingling sand with a second binder ingredient to produce a second sand/binder ingredient mixture. A final mixing chamber includes agitators for receiving the sand/binder ingredient mixtures and blending them into a composite mixture while simultaneously transporting the composite mixture to a final discharge station.

Abstract: A pattern holder 12 and a sand tank 14 are rotatably mounted on a frame 16 so that the pattern holder can be inverted over and sealably mounted atop the sand tank. A vented pattern 26 is secured to the pattern holder and forms a first chamber between one side of the pattern and the interior of the pattern holder. A second chamber 90 is formed between the other side of the pattern and the interior of the sand tank when the pattern holder adjoins the sand tank. O-ring seals 32 and 80 isolate the chambers from the atmosphere so that a partial vacuum can be formed therein. A mixture 84 of sand and a gas-curable binder is provided in the sand tank so that the mixture will fall onto the pattern upon inverting the sand tank over the pattern holder. A flexible line 42 is provided for controllably introducing a gas catalyst into the chamber 38 in order to cure a portion of the sand-binder mixture to form a shell mold 94 of a predetermined thickness on a pattern face 36 of the pattern.