Abstract:  The rubber coating of rotors with different thickness has great influence on the air tightness of screw air compressor and the friction of rotor,aiming at solving this problem,the equivalent stress and strain of rubber coating rotors with different thickness in normal operation were studied.The male and female rotors of one type of 1 cubic air compressor were taken as an example to research.Firstly, 17male and female rotor models with thickness ranging from 0.5mm to 2.1mm and spacing of 0.1mm were established with SolidWorks software respectively without changing the geometry of the rotors; then, a program was made with MATLAB software to calculate the internal torque of the rotors when the compressor was working normally; finally, finite element analysis of rubber coating rotors with different thicknesses were carried out with Explicit Dynamics of ANSYS software, and those data of equivalent stress and equivalent elastic strain obtained from above were compared and analyzed.The results indicate that when the rubber coating thickness is 0.8mm, it meets the requirements and has excellent air tightness performance, after considering factors such as stress, strain and tooth tip clearance.It provides new ideas and methods for improving the performance, air tightness and efficiency of screw compressors.

Key words: screw air compressor; air tightness; rubber coating;rotor model;male/female rotors; internal torque; equivalent stress and strain