Structure Design And Optimization For 70L/s Screw Vacuum

Screw vacuum pump is widely used in many fields,which has a lot of advantages,such as high vacuum,wide range in pumping speed,oil-free in pump chamber,compact structure,no contact between rotors and it can exhaust the gas containing dust.Screw vacuum pump with the pumping speed of 70L/s is regarded as research object to focus on the geometric characteristics of the rotor,the problem of dynamic balance,the deformation of rotors and the structure design of the vacuum pump.The content of this paper is as follows:Based on the theory of end face profile and the principle of rotor design,the meshing characteristics of the end face profile of the screw rotor are explained and the geometric characteristics of the rotor are analyzed.The relationship between the area utilization coefficient and the size of the end face profile is analyzed.The structure design of a screw vacuum pump is introduced.Based on the mechanical principle and theoretical mechanics,the unbalanced mass radius product of rotor is calculated.The relationship between the unbalanced mass radius product and the length of the rotor and the position of the counterweight plane is analyzed.The equations are established in MATLAB to solve the dynamic balance problem of the rotor.The model is established according to the calculation results and it is proved that counterweight method can effectively realize the dynamic balance of the screw rotor by comparing the mass properties before and after balance.The finite model coupled by the thermal and force is established to study the axial and radial deformation of the rotor.The deformation of the spiral lines in surface of the rotor is analyzed to represented the deformation of the different surface of the rotor.The interval values finally determined according to the characteristics of rotor meshing.The power consumed by the pump is calculated on the basis of analyzing the working process.The design of inlet,outlet and main components of screw vacuum pump is completed.Using counterweight blocks balances the rotors on the basis of calculating the first-order critical speed of two rotors.The mass properties of rotors before and after balance are compared and the dynamic characteristics are analyzed.