Foundry moulds and dies - contg. elements which heat the empty die and them provide cooling for directional solidification of a casting

摘要

The rate of heat extn. from foundry moulds or dies is controlled during casting, where the mould contains combined heating and cooling elements (a) which are first used to heat the empty mould to the required working temp. After pouring, elements (a) are used in a desired time sequence to control the rate and direction of heat extn. so the feeder head is the last part of the melt to solidify. During this sequence, each element (a) is cooled to a temp. where solidification is completed in the vicinity of that element. Cooland is pref. sprayed periodically in small amts. and in a desired sequence into a row of elements (a); and the moulds are pref. made of segments with different thermal conductivity (TC), esp. using dies into which elements (a) are cast and are in direct contact with the molten metal. Elements (a) maybe partly surrounded by thermal insulation and contain a coolant feed pipe with low TC. The invention combines chill casting with directional solidification to obtain a fine-grained casting free from piping, segregation, cracks and stresses.