To perform simultaneous and effective cooling of a vacuum seal and cooling of a furnace body by a method wherein cooling air after the passage of it through the periphery of a seal is introduced in a gap between a heat insulation material and the furnace body to generate an air flow.
When, with various treatment containing degreasing carried out, a blower is operated and gas in a furnace body 1 is exhausted, air is sucked in a gap S3 through an opening 15 formed in an openable cover 6 of the furnace body 1 by a negative pressure. After the air makes effective contact with an openable cover 11 of a retort 2, the air flows through a gap S4 and flows out through a pipe 16. At the same time when a vacuum seal 10 is air-cooled to temperature at which the function thereof is held, heat being about to be propagated from the retort 2 through a heat insulation material 4 to the furnace body 1 is also simultaneously carried out to the outside of the furnace body 1 by an air flow. This constitution effectively prevents the occurrence of a situation that the temperature of the surface of the furnace body 1 is increased and improves working environment.
TAKEDA MASAO
YAMAUCHI IPPEI
