Thermal-Structural Coupling Analysis of Variable Pitch Screw Rotors

Abstract

The assembly accuracy of the variable pitch screw rotor has a significant control effect on the vacuum performance of the system. The assembly clearance directly affects the stability of the equipment operation, and the temperature load is an important factor in the rotor deformation. Aiming at the problem of rotor clearance balance, this paper accurately describes the heat exchange process between yin and yang rotors by establishing a thermodynamic model. The three-dimensional simulation model is constructed, and the thermal-structural coupling simulation is completed by combining the physical properties of the material and the boundary conditions. The simulation results show that the axial direction of the rotor has a nonlinear temperature gradient, and the suction end increases from 25°C to the exhaust end. The maximum temperatures of the right and left rotors are 125°C and 122°C, respectively. The thermal deformation is consistent with the temperature field distribution, and the deformation of the exhaust end is concentrated. The radial thermal deformation of the right and left rotor addendum circle is 0.011-0.0475mm and 0.0082-0.0418mm, respectively. The research results provide numerical support for the vacuum performance optimization of the pump body, clarify the reasonable assembly clearance range, and provide a theoretical basis for the improvement of the rotor structure, which has important engineering guidance value.