| 摘要 |
PURPOSE:To suppress the creation of particles and penetration of the air when the over of a heat treatment furnace after a treatment object is subjected to a heat treatment. CONSTITUTION:A pressure detecting part which generates an output signal when a pressure in a heat treatment furnace reaches a predetermined value, an air release tube 5 which has a valve V1 and a check valve 51, a differential pressure gage 62 which is cut off from the inside of the heat treatment furnace by a valve V2 and a ventiduct 6 having a valve V3 are provided. One side end of an air release tube 5 and the ventiduct 6 are connected to the heat treatment furnace and the other end in opened to the air. After treated gas is evacuated, the inside of the heat treatment furnace is filled with inert gas. When the inside pressure reaches near the atmospheric pressure, the valve V1 is opened by the output signal of the pressure detecting part to make the inside pressure of the heat treatment furnace a little higher than the atmospheric pressure and, for instance, if the detected differential pressure of the differential pressure gage is lower than a predetermined value, the valve V3 is opened to release the inside of the heat treatment furnace to the air through the ventiduct 6 and then a cover 72 is opened. |
