Transformation of Single-Thread Profile into Twin-Thread Profile of Screw Vacuum Pump: A Simulation and Analytical Study

A novel twin-thread symmetrical profile was developed as a total solution to the dynamic unbalance problem of the single-thread rotor profile of screw vacuum pump.The necessary conditions,required on the transformation from single-thread profile into twin-thread profile,were summarized.The twin-thread profile was mathematically modeled,analytically calculated and numerically simulated by means of Solidworks software with a specific transformation example.The characteristics of both the single-thread and twin-thread profiles,including the correct meshing conditions,area utilization factor,contact-line and leakage triangle,were calculated.The results show that the newly-proposed twin-thread symmetrical profile outperforms the single-thread profile,not only because of the identical contact-line and leakage triangle,but also because of a much better dynamic balance.We suggest that the transformation scheme herein reported be of some technological interest in development of screw vacuum pump.