vacuum furnace design and maintenance
When the state in the vacuum furnace changes, the actual temperature may deviate from the set value. In this case, the deviation can be corrected by the self-tuning function in the temperature controller, so that the temperature rise is strictly in accordance with the set curve. The heating element is the load of heating power supply. Its material is high temperature molybdenum belt, which can work in high temperature state for a long time. The resistance value of the heating element should match with the magnetic voltage regulator, otherwise the temperature rise will not be up or the magnetic temperature rise will be higher. The main circuit of heating power supply is three-phase AC power supply, which is controlled by AC contactor and controlled by temperature controller.
The control circuit is designed as the input unit. In order to meet the requirements of panel operation of control cabinet, automatic control signal detection and alarm, the input unit includes knob switches such as material inlet and outlet startup, workpiece carriage movement, isolating hot switch, vacuum unit operation, inflation valve, fan start and stop, air release valve, heating, vacuum valve and operation selection, as well as limit switches and alarm signals; the output unit includes heating AC contactor and vacuum unit , workpiece cart, vacuum valve, isolating hot spot, charging and discharging valve, charging valve, partial pressure valve, discharging valve, indicator light and other actuator and audible and visual alarm. Manual operation is mainly used for debugging and maintenance of vacuum furnace. After the input operation, the corresponding component actions are executed, and individual components are interlocked to prevent misoperation. Automatic operation is applied to the normal operation of vacuum furnace, which is automatically controlled according to the application program through the detected automatic control signal.
Vacuum furnace maintenance and repair :
Check whether the sealing ring of furnace door is damaged. If there is dirt on the sealing ring, Juli transformer shall be cleaned in time. It is better to use cotton cloth dipped in alcohol to wipe and then apply vacuum grease. Check whether the heating element bed and molybdenum screen in the furnace are in good condition, and repair and replace the damaged parts in time. When there is pollution in the furnace, use a vacuum cleaner to remove the dust from the Ningbo dust collector, and use a silk cloth dipped in alcohol to wipe the reflection screen and heating elements of the heating chamber; if there is oil on the wall of the furnace, first use a cotton cloth dipped in gasoline to remove the oil, and then use a cotton cloth dipped in alcohol to wipe.
At the end of each work, the furnace should be pumped to a certain degree of vacuum for storage. Check the oil level of the mechanical pump. When the oil level is lower than the mark line, add new oil to the oil mark. When it is found that the mechanical pump oil has emulsified oil-water mixture, which is viscous and white, replace the old oil in time. The method is to unscrew the pressure cap of the oil drain hole of the mechanical pump, drain the old oil, add a little new oil from the oil filler hole, flush the pump cavity, and then tighten the pressure cap of the oil drain hole of the mechanical pump, and then add some new oil from the oil filler hole Add new oil to the standard position, and tighten the pressure cap of the oil filling hole of the mechanical pump. In this process, it is necessary to prevent the sealing ring of oil filling and drain hole from being damaged, and replace it immediately if it is damaged. At the end of each shift, wipe the surface of the furnace with cotton cloth to remove the dust and oil on the mechanical pump and diffusion pump.