Geometry of intersecting-axis conical twin-screw rotors

Intersecting-axis conical twin-screw rotors have shown great potential to further improve the performance of twin-screw machinery. To investigate their unique generation method, this paper established a mathematical model for the conical rotor surface generation by decomposing it into the rotor profile on the sphere and conical helix. The meshing model between the two intersecting-axis rotors was presented based on the separate solution of the conjugate rotor profiles on the sphere. Then, several common rotor curves in screw machinery were extended to the sphere by analogy and their mathematical generation equations were given. The results showed that the proposed method could effectively generate several conical twin-screw rotors with intersecting-axis for typical applications. Finally, the conical rotor was geometrically compared with the traditional cylindrical rotor to reveal its advantages as screw machinery. The results showed that the conical rotor has the potential to improve the suction and discharge process while reducing the leakage and the force of the discharge section. At the same time, some disadvantages such as difficulty in machining and reduction of bearing installation space were discussed with some possible solutions.