| 摘要 |
PROBLEM TO BE SOLVED: To provide a vacuum cooling device lessening deviation between a tank pressure and a target pressure to increase accuracy of pressure control in the case of performing slow cooling operation and slow returning operation with the vacuum cooling device.SOLUTION: A vacuum cooling device performs slow cooling by vacuumizing the inside of a cooling tank 2. The vacuum cooling device performs slow cooling operation of decreasing a pressure reducing speed by setting slow cooling piping 4 having a slow cooling valve 3 in the middle and introducing slow cooling air through the slow cooling valve 3 when vacuum cooling, and in vacuum cooling operation, compares a detected cooling tank pressure with a target pressure set corresponding to an elapsed time, and adjusts an opening degree of the slow cooling valve so as to make a tank pressure close to a target pressure. When performing slow cooling operation, it is set that an opening degree of the slow cooling valve becomes larger in a period when a cooling tank vacuum degree is lower, and an opening degree of the slow cooling valve becomes smaller as a vacuum degree in the cooling tank increases by progress of vacuum cooling operation. |
