Heat treatment method and heat treatment furnace used therein

A heat treatment furnace, comprising:

• a heat chamber for heating work;
• atmosphere supply means for supplying process gas to this heat chamber;
• a hermetically sealable purge chamber, installed alongside said heat chamber, for isolating the interior of this heat chamber from outside air;
• transporting means for transporting said work;
• a first pressure sensor for detecting the inner pressure of said heat chamber;
• a second pressure sensor for detecting the inner pressure of said purge chamber;
• means for reducing the inner pressure of said purge chamber to a predetermined pressure level;
• purge gas supply means for supplying the gas identical to said atmosphere to the interior of said purge chamber;
• and
• a control section for controlling said transporting means, said means for reducing the inner pressure of said purge chamber to a predetermined pressure level, and said purge gas supply means on the basis of detected values from said first and said second pressure sensors,
• wherein said control section actuates said transporting means such that said work is transported between said purge chamber and said heat chamber in a state in which said atmosphere has been supplied to the interior of said purge chamber, following the pump down thereof to a predetermined pressure level, by said purge gas supply means, thus rendering the inner pressure of the purge chamber substantially equal to the inner pressure of the heat chamber.