GB1256345A - Method of making moulds for sand-casting metal objects - Google Patents

Abstract

1,256,345. Patterns; foundry moulding processes. SWISS ALUMINIUM Ltd. 13 May, 1970 [28 May, 1969], No. 23256/70. Heading B3F. A casting mould for thin aluminium plates is manufactured using a flexible elastic pattern 3 (of rubber/plastics or cork in rubber) held by suction on to a backing 2 conforming in shape to the reverse side of the plate to be cast. The backing 2 (of resin-bonded wood chips, plaster/ fired clay mixture or self-hardening cement) has passages 5 behind porous facing material 7 through which suction is applied to hold the pattern 3. A sprue pattern 9 is provided. A drag flask 6 is lowered on to the backing 2 and the patterns 3, 9 covered with a hardening moulding mixture of either the self-hardening, heathardened, CO 2 -set silicate binder, aminehardened isocyanate binder, or silicic acid ester binder types. Alternatively, a quick-setting slurry is brushed or sprayed on to the patterns 3, 9 to form a shell which is backed with moulding sand. When the drag mould has hardened, the assembly of flask, mould, backing and patterns is inverted and the backing removed. A cope flask 11 (see Fig. 3) is lowered on to the drag and green or wet moulding sand packed about the reverse side of the pattern 3 as well as about sprue patterns 12 and stiffeners 13. The completed cope and drag mould parts are separated and the pattern 3 carefully removed from the drag. The cope mould part can be prepared by lowering the drag with the pattern 3 into an inverted cope flask partially filled with moulding sand to press the pattern contours on to the moulding sand.