| 摘要 |
PURPOSE:To control the succeeding atmosphere in accordance with the temp. drop curve down to a value for controlled atmosphere treatment by knowing the actual condition of a furnace and an object to be treated from the temp. curve in the furnace from the time when the object is charged into the furnace until the temp. is elevated and calculating the above-described drop curve from said condition. CONSTITUTION:The actual condition of a furnace and an object to be treated is known from the initial change in the furnace from the point of the time when the actual object is charged into the actual furnace until the temp. is elevated, and the amt. of the enriching gas (gaseous HC) to be added thereafter is controlled in accordance with said condition in this invention. Now, the respective temp. curves of the object to be treated (a) having a large carburization area, (b) having a middle carburization area and (c) having a small carburization area, have a specified relation according to the varying sizes of said carburization areas. More specifically, for the case (a) the temp. drop until the equil. point of the furnace temp. is attained is large, the time therefor is short with a less delay in the initiation of the A1 transformation and the so-called heating delay is small. For the case of (c), the situation is reverse to the case (a). These relations are expressed by the equations and the carburization area of the object to be treated can be counted back from the change at the above-mentioned respective points. The actual treatment condition and the actual condition of the object to be treated are thus known and the effective controlled atmosphere treatment is made possible. |
