To effectively prevent the inside of a furnace from being contaminated by the diffusion of a binder.
A middle room 21b that is closed down on fitting and is opened on departure is provided on the contacting surface of a tight box body 321 that can attach or detach a lid 21, gas is introduced to the middle room 21b via a gas introduction system 4, and at the same time the gas is evacuated via an inner exhaust system 2 for directly evacuating a treatment space S1 inside the tight box 2 and an outer exhaust system 5 for evacuating a space S2 in a furnace outside the tight box 2, thus evacuating paraffin or the like that are diffused and leaked temporarily toward the side of the space S2 in the furnace from the treatment space S1 through the gap between a lid 21 and a body 22 of the tight box 2 without returning it to the treatment space S1 again.
TAKEDA MASAO
YAMAUCHI IPPEI
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