Structure Design And Analysis For Twin-screw Vacuum Pump

Oil free screw vacuum pump is a kind of positive displacement pump, it appeared in1990’s, in the developed countries in Europe,America and Japan and other developed countries, dry screw vacuum pump has been widely used in various industrial fields. The pumping cavity completely free^of oil, and this type of pump can be directly discharged to atmosphere, there is no screw rotor in the working process, capable of stable operation and can pumping gas which contains corrosive or containing dust. The research work for dry screw vacuum pump started late, and such similar products is mainly imported, and the price is more expensive.The most important component of dry vacuum screw pump is a pair of screw rotor. The screw rotor will produce thermal deformation in the process of operation, so we should ensure the pump cavity has a certain gap between teeth and teeth and between teeth and the pump casing. The performance of screw rotor closely related to the rotor type line, foreign vacuum equipment companies developed a variety of screw rotor profiles, but the rotor profile which has excellent performance is lack, and lack independent intellectual property rights.Based on the dry screw vacuum pump, this paper summarizes the using range of screw vacuum pump, and the research progress both domestic and abroad, with common screw vacuum pump rotor type line we get the profile equations of single thread and fixed pitch screw.Verify the validity of the screw rotor type line equation by the use of SolidWorks. We analyzed and calculated the unbalance situation of the screw rotor, and propose a method to solve the problem. This paper also analysed the change of the presure and temperature of the gas inside the sealed volume, and gave a design method for the exhaust port of the pumps. Based on the overall design of screw vacuum pump and the research of the working process, this paper can provide theoretical support.