The Structure And Properties Of The Rotors Of Dry Screw Vacuum Pump

Screw vacuum pump is a kind of dry vacuum pump. Its structure is simple, movement components are less and working is stability, in addition to maintenance is simply. It also can pumping gases containing dust or corrosive, it is highly efficient and energy-saving. Therefore, an increasing number of manufacturing and application companies pay attention to it. It occupy an important position in dry vacuum pump market. In order to adapt to high-tech industries and the needs of special applications, the Process Equipment and Environmental Engineering Institute in N.E.U. are developing the screw-type dry vacuum pumps. This paper take screw dry-type vacuum pump as the object of study, taking an in-depth study and discussion for the contents of meshing characteristics, composition and equations of the rotors, as well as problems such as leaking, mainly has completed the following work:This paper give a simple introduction to seeking methods of the screw rotor tooth equation and the conjugate curve equation, and give all of the original tooth profile and the conjugate curve equation, has analyzed the reason of the interference of the Archimedes helical on the skewed tooth surface, use the Matlab software to paint and verify the involute profile match the design requirement of the rotor.This paper gives several space curve equation of the rotor, including:single-end and fixed-pitch trapezium tooth profile, single-end and fixed-pitch concave tooth profile, single-end and fixed-pitch involute tooth profile. This paper gives the calculation method of the geometry characteristics of the rotor, and for the content of how to determine geometric parameters in the equation and the mutual relationship were discussed in detail.This paper introduces the interstage leaking process of the screw rotor and flowing condition of the gas in the leakage paths of the screw pump. It also gives the consistent of the leakage paths of rotor and a detailed calculation of formulas and charts of the leakage area. According to the results, the leakage area between rotor and stator take more than 70 percent of the total leakage area, is the main leakage path in the pump. The leakage between the walls mainly are caused by labyrinth seal, Poiseuille flows between two flat leaf, entrance effect, as well as Couette flows between two flat leaf.