The vacuum furnace forms a negative pressure vacuum environment in the closed furnace body, and injects the heat medium water into the furnace body. The heat medium water is heated by incineration or other methods, then evaporated from the heat medium water and condensed to the heat exchanger, and then the water to be heated is heated by the heat exchanger. The vacuum furnace takes advantage of the low boiling point of water at low pressure to quickly heat the heat medium water filled in the sealed furnace body, so that the heat medium water jubilates and evaporates to produce high-temperature water vapor, and the water vapor condenses on the heat exchange tube to change The cold water in the heat pipe is heated to achieve the purpose of supplying hot water.

In order to complete the automatic control of the vacuum furnace process, the automatic control system needs to detect the vacuum degree, temperature parameters, process operation parameters and the working conditions of the degassing chamber, heating chamber and cooling chamber to ensure the control output required by the temperature control of each furnace skill. There are mainly the following aspects:

1. Detection parameters: the temperature values of the three temperature measurement points of the deaeration chamber, heating chamber and cooling chamber, the pressure value of the vacuum furnace, the vacuum degree in the furnace, etc.

2. Detection status: call room, heating room, cooling room over temperature alarm, over pressure alarm, water shortage alarm, etc.;

3. Heating is given: control the temperature to control the operation of the instrument, and then adjust the heating power to change the temperature in the furnace. Use thermocouple to sample the temperature of each furnace, compare the detected furnace temperature with the temperature value required by the skill, and calculate the error. The temperature control table calculates the heating current of the heating power board controlled by the operation amount according to a certain rule, and then controls the temperature.

4. Control output: control the transportation of the material truck between the exhaust room, heating room and cooling room, control the actions of the dispersion pump, roots pump, mechanical pump, main valve, rough pumping valve, front valve, etc. to reach the required Vacuum environment.