Study On The Design Methods Of Multi-stage3-Axis Roots Dry Vacuum Pump

In recent years, generalized semiconductor industry has developed vary fast, which gives a good opportunity to the dry vacuum pump. The field of the dry vacuum pump applied is expanding, and extraction process is also more complex,which lead to increasingly higher and higher demand on vacuum pump. The multi-stage3-axis Roots pump studied in this paper is a kind of dry vacuum pump.The pumping speed of3-axis Roots pump is greater than2-axis Roots pump’s,which can be operated without the backing pump.In this paper we introduced the latest progress of Roots pump,and analyzed the new foreign products of Roots pump. We introduced the pumping principle of the single-stage and multi-stage3-axis Roots pump,derived its theoretical pumping speed calculation formula, and calculated steady state pressure of the Roots pump,the power consumption and other important design parameters. We introduced the structure of multi-stage3-axis Roots pump and analyzed the noise reduction measures of3-axis Roots pump.The rotor profile is very important for designing Roots pump.In this paper we described the profile equation of four lobe rotor used in the3-axis Roots pump, ie, arc and involute profile equation of four lobe rotor. We compared the area utilization coefficient of two kind of rotors, and we also compared with the two lobe rotors used in the2-axis Roots pump.In the process of modeling, because the profile equation is complex and profile parameter calculation and drawing is tedious, we adopt the method of parametric design to create the man-machine communication interface to fast generate the rotors based on SolidWorks software.It greatly saves design time, and the designers do not have to be particularly familiar with the rotor profile equation,who just need to understand the design parameters.The rotational speed of Roots pump is high,and the rotor exhaust based on the gap seal. In order to ensure that the rotors have sufficient strength and appropriate gap value,we analyzed and compared three-axis and two axis Roots pump rotors based on ANSYS software and simulated the rotor thermal expansion and thermal stress by coupling thermal and structure.The work we have done will be instructive to the design of Roots pump.