Determining the repair width and CNC grinding of screws of triple-screw pump

To improve the machining quality and volumetric efficiency of triple-screw pumps, the screws are ground and processed using a computer numerical control (CNC) grinder. In this paper, we propose a new method to determine the arc repaired width of a driven screw in order to solve the problem of sharp transverse profile corners that cannot be ground due to either no repair or repairs with an inappropriate ratio of screw pitch diameter. Herein, parametric equations for the driven screw transverse profile repair are defined based on a grinding model for triple-screw pump screws. The relationship between the rim radius of the diamond wheel and the repaired width of the driven screw is established. Finally, a law to determine the minimum repaired width of the driven screw is defined and the theoretical basis for triple-screw pump screw CNC grinding is provided.