Method and apparatus for hardening of foundry cores

Claim 1

Method of hardening foundry core means made of a mixture which includes sand and curable compounds in which, to harden the core means, the core means is exposed in a core-forming apparatus to a mixture of a gaseous catalyst and a carrier gas, and to compressed air wherein, in order to accurately predetermine the volume, pressure and temperature of the gaseous catalyst-carrier gas mixture being applied to the core means, and of the compressed air being applied to the core means, the method comprises the providing a source (4, 5, 6) of gaseous catalyst-carrier gas mixture; providing a source (12, 13) of compressed air; providing a first temporary storage vessel (8) for gaseous catalyst-carrier gas mixture; supplying said catalyst-carrier gas mixture from said mixture source to said first temporary storage vessel (8); segregating and temporarily storing a predetermined quantity, which corresponds to the desired amount to cure the core means in the core forming apparatus, of the mixture of gaseous catalyst and carrier gas in the first temporary storage vessel (8); providing a second temporary storage vessel (11) of substantially greater volume capacity than said first temporary storage vessel (8); supplying compressed air from said compressed air source to said second temporary storage vessel; segregating and temporarily storing a predetermined quantity, which corresponds to the desired amount to flush the core means in the core forming apparatus, of compressed air in the second temporary storage vessel (11); controlling pressure, and the temperature of the compressed air in said second temporary storage vessel to be higher than the pressure and temperature of the gaseous catalyst-carrier gas mixture in said first temporary storage vessel to thereby segregate a controlled larger quantity of compressed air therein; suddenly and abruptly and rapidly injecting such stored mixture of gaseous catalyst-carrier gas from said first temporary storage vessel into the core means in the core forming apparatus by admitting the segregated, desired quantity of said stored mixture into the core forming apparatus; and then suddenly and abruptly and rapidly injecting said compressed air from said second temporary storage vessel at said elevated temperature and with said higher pressure into the core means in the core forming apparatus by admitting the segregated desired larger quantity of said stored compressed air into the core forming apparatus.