Research on fault mechanism of twin-screw pump based on torsional vibration model

The problem of active shaft fracture in twin-screw pumps has existed for a long time, bringing great safety hazards and economic losses. Breaking through the constraints of traditional analysis methods, a precise model of rotor system based on data adjustment was established. An excitation identification method targeting the symmetrical constraint characteristics of twin-screw pumps was proposed, which resolved the long-standing issue of the extreme susceptibility to distortion in the load identification of twin-screw pumps. Based on this method, forced vibration response analysis and fatigue analysis of twin-screw pump were conducted, and significant defects were discovered in the design of the twin-screw pump. To fulfill the optimization demands, a suite of equivalent analysis models for refined screw torsional vibrations including key twist stiffness and keyway section stiffness was established, enhancing the computational efficiency. It was discovered that there exist low-order torsional vibration frequencies within the rated rotational speed range, and this was verified through experiments. The proposed new design method was employed to conduct the structural optimization of the rotor and the comparative analysis of torsional vibration strength. The torsional vibration state of the new structure was remarkably enhanced, and no similar faults recurred in the same series of models within an operation period of over 2900 days.