Research Of Profile Designing, Processing And Surface Coating On Multi-stages Roots Pump Rotor

During the manufacture processing of products such as chips, optics communication devices and flat displays in newly arising semiconductor industry, oilless molecule pumps and cryopumps are widely used as high or middle vacuum acquiring equipments. However, oil-sealed mechanic vacuum pump is appicated as back pump of these dry vacuum pumps. In order to reduce the oil pollution, cold traps are usually adopted between high and low vacuum pumps, which can not meet severe needs any more nowadays. So we must study and design some new dry vacuum pumps with high cost performance, long life, simple structure and high pumping efficiency in a long period from today. Among several types of dry vacuum pumps, roots type vacuum pump is one kind of volumetric pumps that many high technique industry of semiconductor and optics devices are keen on.Circled on roots type rotor, the main key part of dry roots vacuum pump, we have finished the following jobs.By the computer-simulated generation method which can generate profile. Three commonly used roots rotor were analyzed Based on the involuted profile designing, was designed. Through the analysis and comparison with the volumetric utilization coefficient and the gap distribution, due to improved arc-profile rotor can get better result, choosing the improved arc-profile rotor as a multi-stage Roots dry pumps Rotor.The processing methods of roots rotor were discussed. For the special-profile of the rotor, I drew up the programs through 2.5 axis CNC milling machines, CNC-cutting processing, NC planer and the general lathe. From the economic feasibility and processing, such as the accuracy of several options were analyzed.I finished the exploratory study on surface coating technology of the Roots rotor. With magnetron sputtering deposition we made hard decay resistance coating on samples of the rotor, by regulating the vacuum, argon gas flow, sputtering parameters such as time, we studied the processing of magnetron sputtering Cr. In measurement, by the standard of salt spray test, we finished a comparative study about the corrosion resistance of the rotors before and after the corrosion resistance of, and the hardness micro-structure, roughness of before and after the film deposition were studied.