PURPOSE: To shorten slow cooling speed of a heat radiating material in a heating chamber and to efficiently execute the heat treatment by introducing the low temp. atmosphere of a quenching chamber into the heating chamber with the back pressure of a stirring fan arranged in the heating chamber of an atmospheric heat treatment furnace.
CONSTITUTION: A metallic product 5 to execute carburizing treatment is charged into the heating chamber 1 in a gas carburizing furnace and the carburizing treatment is executed with carburizing, atmospheric gas of CO base gas, etc., while heating to about 930°C with radiant tube burners 3. Successively, after slowly cooling to 850°C in the heating furnace 1, the carburized product 5 is shifted into the quenching chamber 7 continued from the heating chamber 1, and dipped into a quenching oil vessel 10 at the lower part by acting a cylinder 12. In this case, the heating chamber 1 and the quenching chamber 7 are connected with a duct 13 and the slow cooling time of the metallic product 5 already completing the carburizing treatment in the heating chamber 1 is shortened by utilizing the back pressure generated with the rotation of the stirring machine 4 in the heating chamber 1 to introduce the low temp. atmosphere in the quenching chamber 7 into the heating chamber 1, and then, the operating ratio of the gas carburizing furnace is improved.
KAWATE KENJI
SATO KENJIRO
