Study On Rotor Characters Of Dry Vacuum Screw Pump

To satisfy the more and more strict requirement of clear vacuum environment of industry, a new type of vacuum acquiring equipment named dry (oil-free) pump was developed. Especially dry vacuum screw pump has a wide application because of its good pumping performance. There is no internal scale product of dry screw pump owing to the late research starting, so like products are all depend on importing and the price is very expensive. The driving and driven screw rotors are the most important components. The rotor profile and thermodynamic performance determine the pumping performance of pump. The rotor profile determines the pumping speed and working pressure range of pump. The rotor profile and thermodynamic performance determine the ultimate pressure and the working medium of pump. Furthermore, the rotor characters are the first key problem to be studied when you want to design the structure and develop the product.In this paper, Taking screw pump rotors as subject investigated, the rotor characters were discussed deeply including its profile, deforming, running monitoring and fault diagnosis. We hope to do some contribution in order to optimize the pump structure, increase the pump performance and realize the goal that we will make our own pump.Several typical screw rotor profiles were studied by theory investigation and experiment, which were the multithread and single thread profiles. The single thread profile includes variable thread pitch and fixed pitch. The calculation formulas of coefficient of used area and the geometric pumping speed were deduced by the equation of tooth flank and the study of flank interference. Then, the variables of calculation formulas of coefficient of used area and the geometric pumping were analyzed comparably and Taking into account the feasibility of machining and manufacture, the optimal variable range was got.The experiment of single thread and fixed pitch concave tooth flank rotor profile was done and it proofed that the deduction theory and method of rotor profile was valid by the comparison between measuring and calculation value of pitch angle of inclined tooth flank and geometric pumping speed and real pumping speed.