Continuous gas carburizing furnace

A continuous gas carburizing furnace in which a plurality of steps are serially arranged in a line along a conveying direction of a workpiece, comprising:

• a gas carburizing processing chamber in which a gas carburizing process is performed on the workpiece;
• an oil quenching chamber in which oil quenching is performed on the workpiece;
• and
• a gas quenching chamber in which gas quenching is performed on the workpiece,
• wherein:
• the gas carburizing processing chamber includes a temperature decrease chamber that lowers temperature of the workpiece that is heated by a gas carburizing process, and to which a carburizing gas is supplied;
• the temperature decrease chamber, the gas quenching chamber and the oil quenching chamber are arranged sequentially in that order of mention from an upstream side to a downstream side in the conveying direction of the workpiece, and are adjacent to each other;
• a first conveying chamber that covers a side surface portion of the temperature decrease chamber and a side surface portion of the gas quenching chamber which face each other is provided between the temperature decrease chamber and the gas quenching chamber;
• a second conveying chamber that covers a side surface portion of the gas quenching chamber and a side surface portion of the oil quenching chamber which face each other is provided between the gas quenching chamber and the oil quenching chamber;
• inside the first conveying chamber, a first open-close door for thermal insulation, in which a hole portion is provided, is provided for the side surface portion of the temperature decrease chamber which faces the gas quenching chamber;
• inside the first conveying chamber, a second open-close door for pressure resistance is provided for the side surface portion of the gas quenching chamber which faces the temperature decrease chamber;
• inside the second conveying chamber a third open-close door for pressure resistance is provided for the side surface portion of the gas quenching chamber which faces the oil quenching chamber;
• inside the second conveying chamber, a fourth open-close door for oil vapor shield, in which a hole portion is provided, is provided for the side surface portion of the oil quenching chamber which faces the gas quenching chamber;
• a communication pathway that provides communication between the first conveying chamber and the second conveying chamber is provided between the first conveying chamber and the second conveying chamber;
• the carburizing gas supplied to the temperature decrease chamber flows into the first conveying chamber through the hole portion provided in the first open-close door for the side surface portion of the temperature decrease chamber which faces the gas quenching chamber;
• the carburizing gas filling the first conveying chamber is guided into the second conveying chamber through the communication pathway;
• and
• the carburizing gas guided into the second conveying chamber is supplied into the oil quenching chamber through the hole portion provided in the fourth open-close door for the side surface portion of the oil quenching chamber which faces the gas quenching chamber.