The Thermal-Mechanical Coupling Analysis And Structural Optimization Of Dry Screw Vaccum Pump

In recent years,with the development of the semiconductor industry and the microelectronics industry,the traditional vacuum pump,which cannot meet the clean,oil-free and corrosion-resistant requirements,is gradually being replaced by the cleaner-dry vacuum pump.Dry screw vacuum pump is a kind of common dry vacuum pump,and it has been widely used in many industrial and scientific fields for its remarkable advantages such as its compact structure,producing of oil-free vaccum,large pumping speed,long life,adapting for the mal-condition and discharging directly into atmosphere.But as a result of the domestic research about dry screw vacuum pump started relatively late,the key processing technology of screw rotor is mastered by foreign monopoly,all products are depend on importing and the price is very expensive.Therefore,this dissertation takes the core screw rotor of dry screw vacuum pump as the research object,studies the rotor profile and thermodynamic performance of the single-head and multi-head screw vacuum pump rotor,and optimizes the structure of the vacuum pump in order to make up for the lack of domestic technology shortage,and promote the rapid development of domestic dry vacuum pump.The thesis is divided into four chapters,and the main research contents are summarized as follows:Chapter I briefly introduces the main structural components,working principle and performance characteristics of the dry screw vacuum pump.Then mainly describs the development of the screw rotor profile and the status quo of the rotor thermal deformation analysis,and illustrates first-class enterprise products at home and abroad.At last,summarily states the future direction of dry screw vacuum pumps.Chapter II theoretically analysises several typical screw rotor profiles,including multi-head and single-head profiles.Secondly compares the design elements of various screw rotor profile like leakage triangles,mesh lines,area utilization ratios and so on.Lastly selects two types of the screw rotor profile with better performance and shows the profiles equations.Chapter III establishes the mathematical model of the screw rotor thermal analysis,and gets the temperature field and deformation distribution of the threedimensional screw rotor under the combined effects of the three cooling methods by ANSYS software.Then describes the thermal deformation changes of different screw rotors.In addition,discusses the influence of rotational speed,cooling mode,screwnumber and different materials on rotor deformation for providing a theoretical basis for rationally giving the assembly clearance between the meshing rotors in the next step.In chapter IV,the dry screw vacuum pump is optimized for the sealing,cooling and corrosion problems that found in the actual work.The sealing system of the vacuum pump is improved by the magnetic fluid seal,and the original cooling water direct cooling system is improved to indirect cooling system for further improving the comprehensive performance of the dry screw vacuum pump.