If the carburizing heat treatment furnace shell exhibits surface oxidation and peeling, it will cause cracks and semi-cracks, so that the gas leakage of the carburizing furnace is the main form of failure. Casting defects have a great impact on the service life of the furnace tank, and there are often more opportunities for oxidation and cracking at the defects. The furnace tank was slightly cracked and used for repair welding soon, and it was quickly damaged. This was mainly due to the decrease in welding performance after oxidation and carburization.

For normal use, it is necessary to frequently purge the oxide scale under the bottom plate, usually once a week, hoist the furnace bottom plate when purging, and use compressed air to clean the oxide scale in the resistance wire trough, and pay attention to prevent the oxide scale from getting stuck. Causes short in the furnace wire. The furnace door equipment is composed of furnace door, furnace door improvement organization and furnace door pressing equipment. The furnace door shell is welded by section steel and plate to form a strong frame structure, and the interior is made of refractory fiber modules, which require good heat preservation performance and light weight. The furnace door improvement equipment is electric equipment. The pit tempering furnace is mainly composed of the furnace door frame, the furnace door raising beam, the reducer, the sprocket, the transmission shaft and the bearing, etc. The furnace door is lifted by the positive and negative transmission of the reducer. Lifting of the movable furnace door. The furnace door improvement reducer is also equipped with brake equipment, which can effectively avoid the displacement of the furnace door during the lifting process. The furnace door pressing equipment adopts the domestic advanced spring-type pressing structure. When the demand of the furnace increases, the furnace door's own weight will be automatically released by the lever, and the furnace door will rise after moving out a certain distance horizontally. When the high-temperature circulation fan on the side is lowered to the pulley on the trolley and needs to be compressed, the elastic force of the spring and then the lever will move the furnace door horizontally into the compressed and sealed state. The compression equipment of this structure makes the fiber on the furnace door flat. There is no friction between the cotton and the furnace mouth, and it has the characteristics of good safety performance and long use.