Gap design is one of the most important parameters of multistage Roots dry pump design. In multi-stage Roots dry pump operation, the gap by the rotor and pump cavity thermal deformation greater impact. In this paper, the internal heat transfer process of multistage Roots dry pump is analyzed, and the heat transfer model of the working process is established. Through the contact and non-contact temperature measurement methods, the multi-point temperature was measured and the boundary conditions of thermal load were obtained. Based on the ANSYS software, the temperature field of the pump body and the rotor shaft during steady operation is analyzed. The thermal deformation of the pump body and the rotor shaft are calculated by the thermal-mechanical coupling analysis, and the thermal deformation of the rotor shaft and the pump chamber is obtained. Deformation clouds and curves. The thermal deformation data obtained by the above method provide a reference for determining the clearance and provide the basis for further calculation of the leakage of the dry pump during operation. In recent years, by the semiconductor manufacturing, liquid crystal injection, solar cell production, electronic devices and other emerging industries and film preparation, chemical, pharmaceutical and other traditional industries, multi-level Roots dry pump as one of the core equipment, its development and production of more The more attention. Multistage Roots dry pump to meet the IC equipment manufacturing industry high temperature, long-term stable operation, low noise, simple maintenance, clean and oil-free and many other requirements, is a promising development of a dry vacuum pump. However, in addition to the processing and assembly requirements of high precision, difficult processing, one-time expensive investment and other constraints, the design theory and manufacturing processes need to be improved, including the improvement of Roots-type lines, lower processing costs, clearance determination, Leakage calculation, the thermodynamic analysis of the pump, the rotor surface coating, noise and vibration and other difficult issues, restricted the development and production of multistage Roots dry pump. Research on multistage Roots dry pumps at home and abroad still stays in the calculation and experiment of static leakage. For example, RussiaBurmistrov et al. Established the leakage channel conductance coefficient of the complex shape of the Roots pump under the molecular flow state by using the angle coefficient method Model, focusing on the calculation of the amount of leakage taking into account the harmful gas space backflow. The French scholar LCValdes et al. Derived the calculation of the conductance of the transitional flow through a non-constant rectangular cross-section, combined with the KnudsenDong rule, studied the static leakage theory of air-cooled Roots dry pump gap under non-operating conditions and verified by static experiments . Some domestic scholars mainly focus on the dry pump line and leakage theoretical and experimental study. Multistage Roots dry pump In a hybrid compression process, the compressed gas generates heat. As the duty cycle repeats, the heat builds up and is gradually transferred to the rotor and the pump's inner wall, causing the rotor and the inner wall of the pump to rise in temperature. As the temperature increases, the rotor and pump chamber will have some thermal deformation, will affect the size of the gap passage. Gap is one of the most important parameters in dry pump design. Due to the phenomenon of gas reverse flow, the choice of clearance will seriously affect the ultimate vacuum, compression ratio, volumetric efficiency and thermal jam of dry pump. This article focuses on the pump heat transfer process and rotor, pump chamber temperature and heat deformation analysis, on the one hand to provide accurate basis for calculating the amount of leakage, on the other hand, is also involved in the gap size, examine the fever after the rotor and the pump Body wall is an important basis for scraping touch. Conclusion In this paper, the heat transfer process of multistage Roots dry pump is analyzed, and the heat transfer model of multistage Roots dry pump is established, including the natural convection heat transfer model between pump wall and atmosphere, Internal heat conduction model, forced convection heat transfer model between pump body inner wall and gas, forced convection heat transfer model between gas and rotor in pump body, and heat conduction model on rotor shaft. At the same time, through the contact and non-contact temperature measurement methods, the experimental measurements of the inner and outer walls, gas and rotor temperatures at all levels were carried out. The temperature measurement results were taken as the boundary conditions. Using ANSYS software, And the temperature field of the rotor shaft during steady operation are analyzed. The thermal deformation of the rotor shaft and the pump chamber is calculated by using the thermo-structural coupling analysis. In order to further calculate the heat generation of the dry pump during operation Gap gap provides a basis for calculation.
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