Multistage twisted-blade Roots vacuum pump rotor and design method thereof

The invention discloses a multistage twisted-blade Roots vacuum pump rotor and a design method thereof. The multistage twisted-blade Roots vacuum pump rotor is characterized in that a plurality of Roots rotor stages are arranged on a rotor shaft, and the axial size or the radial size of the rotor is sequentially reduced along with the increase of the number of the rotor stages, so that the inner volume of a rotor cavity is sequentially reduced, and the inter-stage internal compression process is realized; and the rotor adopts a twisted blade form, and an internal compression process in a single rotor stage is formed through the design of air suction and exhaust ports. The design method comprises the following steps that a tooth height radius and a rotor center distance of a first-stage rotor profile are optimized according to an air exhaust rate requirement; according to the requirement of the internal compression degree, the rotor stage number, the axial size of each stage of rotor, the tooth height radius o