Foundry sand mould prodn. - uses compacted mixt. of sand and water which has surface layers frozen by cold air, liquefied gas spray or dry ice

摘要

The shaped and compacted mixt. of sand and water, after removal of the associated pattern has the surface layers frozen to a depth sufficient to withstand the conditions imposed during the subsequent metal pouring operation. The freezing operation is carried out by a stream of cold air, or using a liquified gas such as N2, CO2, or He. Pref. the mould is frozen to -1 degrees C to -269 degrees C. The sand-water mixt. may have a small amt. of another constituent which imparts sufficient green strength to allow undamaged stripping from the pattern. The amt. used does not affect reclamation of the sand. Pref. silica-, zircon-, or olivine sand is used.