Lost foam metal casting process for prodn. of e.g. engine blocks

摘要

The process forms a metal casting of specific shape. A plastic foamed part is first formed in this shape, to be embedded in solid heat resistant material. Molten metal is then poured into the plastic part, substituting it, as a casting. Following cooling, the solidified part is extracted. Material, which can be foamed and sintered, is placed into a mould cavity shaped to the form of the required casting. The mould has two or more walls, each with temp. and/or pressure sensors. Steam is applied at the mould walls, together or in alternation, heating, foaming and sintering the charge. The process is controlled in accordance with the sensor signals, varying the steam supply at locations reaching given values of temp. and pressure, until from one sensor a final signal (0, ST4) reaches the controller, and/or a max. time (tmax) has elapsed, and/or a given value has expired. Then the plastic part is cooled, the mould is opened and it is extracted for use in stage 2.