Investigation of non-linear dynamic characteristics of a point-contact spiroid worm drive generated by two-generating-surface method

Abstract

Because of instantaneous multi-tooth contact and line-contact, an Archimedean spiroid worm drive is sensitive to manufacturing and assembly errors. To solve the sensitivity of the spiroid worm drive (SWD), this paper proposes a kind of two-generating-surface method (TGSM) that transforms the contact type of the SWD from line-contact to point-contact. A generating surface is the helical surface of Archimedean spiroid worm, which generates the surface of a spiroid worm wheel. The other one is the arc-curve of a turning tool which degenerates from a spatial arc-surface and the arc-curve forms the surface of the worm that is called arc-worm. The arc-worm and the worm wheel compose a kind of point-contact spiroid worm drive (PCSWD). Furthermore, in order to investigate the non-linear dynamic characteristics of the PCSWD, a 14-degree-of-freedom multi-body dynamic model of the PCSWD considering bending, torsion, and axial is established. For case study, numerical simulation is performed to illustrate the meshing characteristic through tooth contact analysis. A prototype is manufactured and meshing test is performed to verify the correctness of the method. Subsequently, the dynamic response of the PCSWD is analysed by solving dynamic differential equations, The nonlinear characteristics of dynamic transmission error (DTE) under different torques, meshing damping ratio coefficients, and backlashes are analyzed by bifurcation diagrams. The dynamic response of DTE under different excitation frequencies is discussed using time-domain plot, phase portrait, Poincaré map, and frequency domain diagram under constant torque, meshing damping ratio coefficient, and backlash. Finally, the influences of different meshing models, backlashes, helix angles, and tooth profile angles on the root mean square value of dynamic meshing force (DMF) under light and heavy load conditions are discussed. The DTE results show that the PCSWD has sophisticated nonlinear characteristics under different conditions. The DMF results of the PCSWD show that impact and noise problems are more likely to occur under light load. The research provides meaningful theoretical guidance for the design and optimization of high-performance, low-noise PCSWD.