Catalytic hardening of sand cores or moulds in metal foundries - where hot air, which removes residual catalyst from hardened core, is reused in next hardening cycle

摘要

The sand is mixed with binders which harden when exposed to a catalyst. A specific amt. or does of the liq. catalyst is vaporised and mixed with compressed air which carries the catalyst vapour through the sand core. Hot compressed air contg. no catalyst is then used to remove the residual catalyst from the core, the air and catalyst entering a sealed chamber in which air expands during the pause between successive core hardening cycles. The next dose of catalyst is then fed into the sealed chamber. and the mixt. of hot air and catalyst is used for the next core hardening cycle. The pref. appts. includes a catalyst vaporisation plant feeding a mixing chamber fed with hot air, a network of valves ensures the recycling of the residual catalyst. Each dose of catalyst is completely vaporised, but the total quantity of heat required by the hardening plant is reduced as compared with an earlier process proposed by the inventor.