Mechanical pump is also called pre-stage pump, and is one of the most widely used low vacuum pumps, which uses oil to maintain the sealing effect and relies on mechanical methods to continuously change the volume of the suction cavity in the pump, so that the volume of the gas in the pumped container is continuously expanded to obtain a vacuum. There are many kinds of mechanical pumps, the common ones are slide valve type, piston reciprocating type, fixed vane type and rotary vane type.
Components of mechanical pumps
Mechanical pump is often used to pump dry air, but can not pump high oxygen content, explosive and corrosive gases, mechanical pumps are generally used to pump permanent gas, but no good effect on water and gas, so it can not pump water and gas. The parts that play the main role in rotary vane pump are stator, rotor, shrapnel, etc. The rotor is inside the stator but has a different axis from the stator, like two inner tangent circles, the rotor slot is equipped with two pieces of shrapnel, the middle of the two pieces of shrapnel is equipped with a spring to ensure that the shrapnel is tightly attached to the inner wall of the stator.
Mechanical pump working principle
Its two shrapnel alternately plays two roles, on the one hand, sucking in gas from the inlet, and on the other hand, compressing the gas already sucked in and deflating the gas out from the pump. Rotor every rotation cycle, the pump completes two suction and two deflation.
When the pump rotates clockwise continuously, the rotary vane pump continuously draws in gas through the inlet and deflates it from the exhaust port to achieve the purpose of pumping the container. In order to improve the ultimate vacuum of the pump, the pump stator will be immersed in oil so that the gaps and harmful space in each place often keep enough oil to fill the gaps, so the oil plays a lubricating role on the one hand, and on the other hand, it plays a role in sealing and blocking the gaps and harmful space to prevent gas molecules from backflowing through various channels to the space with low pressure.
Mechanical pump deflation effect is also related to the motor speed and belt tightness, when the motor belt is relatively loose, the motor speed is very slow, mechanical pump deflation effect will also become worse, so we must often maintain, spot check, mechanical pump oil sealing effect also need to frequently spot check, too little oil, can not reach the sealing effect, the pump will leak, too much oil, the suction hole blocked, can not suck air and exhaust, generally, in the oil level 0.5 cm below the line can be.。
Roots pump with mechanical pump as front stage pump
Roots pump: It is a mechanical pump with a pair of double-lobe or multi-lobe rotors rotating at high speed synchronously. Since its working principle is the same as that of Roots blower, it can also be called Roots vacuum pump, which has a large pumping speed in the pressure range of 100-1 Pa. It makes up for the shortcomings of the mechanical pump’s insufficient deflation capacity in this pressure range. This pump can not start work from the air, and can not directly exhaust the air, its role is only to increase the pressure difference between the inlet and exhaust port, the rest is needed to complete the mechanical pump, therefore, it must be equipped with a mechanical pump as a pre-stage pump.
Precautions and maintenance of mechanical pumps
During the use of mechanical pumps, the following issues must be noted.
1, The mechanical pump should be installed in a clean and dry place.
2, The pump should be kept clean and dry, the oil in the pump has a sealing and lubricating effect, so it should be added in accordance with the specified amount.
3, To regularly replace the pump oil, when replacing the previous waste oil should be discharged first, the cycle is least three months to six months to replace once.
4, Follow the instructions to connect the wire.
5, The mechanical pump need to close the air inlet valve before stopping working, then power off and open the air valve, the air through the air inlet into the pump.
6, When the pump is working, the oil temperature can not over 75℃, otherwise it will be too small due to the viscosity of the oil and lead to poor sealing.
7, Check the belt tightness of the mechanical pump, the speed of the motor, the speed of the Roots pump motor, and the sealing effect of the seal ring from time to time.
–This article is published by Guangdong Zhenhua Technology, a manufacturer of vacuum coating equipment.
Post time: Nov-07-2022