Pneumatic mfr. of foundry moulds and cores - where sand is drawn by vacuum into core box and is then compacted by compressed air

摘要

The mould- or core- box contains air outlet holes, and is placed in a sealed chmber underneath a sand hopper fitted with an outlet shutter. After opening shutter, the chamber is exposed to a vacuum via an adjacent evacuated chamber so there is a very rapid drop of pressure in the sealed chamber, causing sand to flow rapidly into the core box. The shutter is then pref. closed, and the sand inlet hole in the core box is exposed to compressed air, provided by an adjacent chamber contg. air at high pressure; the sand is thus compressed in the core box, which is still exposed to the vacuum wehn the compressed air enters the sealed chamber. A reaction- or catalyst-gas is pref. then fed into chamber to harden the sand. Used in the mfr. of sand cores with a complicated shape from cold setting sand mixts., the cores being e.g. shell cores, or cores used to make the water jackets in i.c. engines.