Sand cores or moulds made by shooting and squeezing - where rapid evacuation of core or moulding box provides shooting effect.

摘要

Core or moulding sand is shot from a sand chamber through a wall or base, fitted with sealable openings, into a core- or mould-box, using the sudden, shock-type application of a vacuum to the box. The box and the openings are first sealed and a vacuum is applied to the box; the shutters or valves blocking the openings are then suddenly released so the sand shoots into the box. The shutters may be closed immediately after shotting, or after a time delay, and the sand in the box is pref. subjected to further compaction by using the base of the sand chamber as a press plate, where some of the sand in the box can be pressed back into the sand chamber via the open shutters. The shutters can be closed during compaction when the sand near the press plate reaches a Fischer hardness of 70, further compaction then being applied. The applied vacuum is pref. 0.7 atmos. High speed core or mould shooting is combined with squeezing to form accurate moulds; and sand is not blown into the foundry atmos. to cause pollution.