Mechanical pump for PVD vacuum coating equipment
For the vacuum of PVD vacuum coating machine, a mechanical pump must be used. The mechanical pump is also called the backing pump. The mechanical pump is the most widely used low vacuum pump oil to maintain the sealing effect and continuously change the volume of the pump suction cavity by mechanical methods. Therefore, the gas in the container is volume expands to obtain a vacuum. There are many kinds of mechanical pumps, commonly used four types: spool valve type, reciprocating piston type, fixed plate type and rotary plate type.
Mechanical pumps are often used to remove dry air, but cannot remove excess oxygen, explosive and corrosive gases. Mechanical pumps are generally used to remove permanent gases, but they are not effective for water gas, so water gas cannot be removed. The components that play an important role in the rotor pump process are stator, rotor, shrapnel, etc. The rotor is different from the stator shaft and stator, like two inner rings, the rotor slot is provided with two shrapnel, and a spring in the middle of the two shrapnel ensures that the shrapnel tightly attached to the inner wall of the stator.
Its two shrapnel alternately play two roles, on the one hand, the gas is sucked in, and on the other hand, the compressed gas has been sucked in and the gas is discharged from the pump. Each time the rotor rotates, the pump completes two suctions and two discharges. When the pump continues to rotate clockwise, the rotary vane pump continuously inhales gas through the air inlet, and continuously discharges it from the exhaust port to achieve the purpose of suctioning the container. In order to improve the limit of vacuum pump, the pump stator is soaked in oil, and the ubiquitous gap in the harmful space is often kept enough oil to fill this gap, oil lubrication, on the one hand, on the other hand, seals and fills the harmful effect of the empty space, preventing Gas molecules flow back into the low-pressure space through various channels.
The mechanical pump starts to work from the atmosphere, and its main parameters are ultimate vacuum degree and pumping speed, which is an important basis for the design and selection of mechanical pumps. The single-stage pump can pump the container from the atmosphere to the ultimate vacuum of 1.0* 10-1Pa, and the two-stage mechanical pump can pump the container from the atmosphere to the ultimate vacuum of 6.7* 10-2Pa or higher.
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