| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a control method of a heat treatment furnace, for accurately continuously performing the isothermal heat treatment of a steel product at two stages of temperature i.e. a first temperature and a second temperature lower than that, in a heat treatment furnace having adjustable furnace pressure and including a burner for heating and an air nozzle for introducing cooling air into the furnace.SOLUTION: The control method of a heat treatment furnace performing the heat treatment of a steel product comprises: a first isothermal heat treatment step of maintaining pressure inside the furnace at a first temperature by adjusting the output of a burner for heating; a temperature lowering step of lowering temperature inside the furnace to a second temperature by adjusting the output while at least maintaining combustion by the burner for heating; a second isothermal heat treatment step of maintaining the inside of the furnace at the second temperature by adjusting the output of the burner for heating; a furnace pressure maintaining step of constantly maintaining a furnace pressure during the first isothermal heat treatment step; a first furnace pressure lowering step of lowering the furnace pressure to a predetermined positive pressure during the temperature lowering step; a cooling air introduction step of introducing a cooling air; and a second furnace pressure lowering step of further lowering the furnace pressure to a predetermined negative pressure.</p> |
