A MANUFACTURING METHOD FOR GENERATING A VARIABLE-PITCH ROTOR OF TWIN-SCREW CACUUM PUMP
The twin-screw dry vacuum pump is widely used in low and medium-low vacuum applications. Its core element consists of a pair of rotors rotating in opposite direction on parallel axes. Screw rotors with uniform pitch are usually finished by the form grinding method, but the rotors with variable pitch are not. The advantage of a variable pitch twin-screw vacuum pump is the high energy efficiency due to high volumetric compression ratio when transporting gas from inlet to outlet. In this paper, a novel manufacturing process for generating the tooth profile of the screw rotor with variable pitch by CNC lathe turning is proposed. The initial position, trajectory of turning tool and profile error of the manufactured screw rotors are derived and verified numerically. A numerical example is presented to validate the proposed method. The simulation results reveal that the proposed CNC turning process is feasible and flexible.
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