Translated Abstract
Feed system, playing an important role in CNC heavy-duty horizontal lathe, is a typical complex gear rotor system with multi-level and multi-offshoot. The quality of the dynamic performance between feed systems and the whole CNC machine are closely connected. When CNC heavy-duty horizontal lathe feed systems is running at a low velocity, the stick-slip phenomenon will be introduced. The stick-slip phenomenon, which is a problem that must be solved, seriously affects the working accuracy, surface roughness and position accuracy. Under the support of National Science and Technology Major Project, taking feed system of CNC heavy-duty horizontal lathe as research object, the dynamics characteristic of the feed systems is researched. In this paper, structural characteristic of the feed system of CNC heavy-duty horizontal lathe is analyzed and gear rotor systems dynamics is applied to study the stick-slip mechanism of the feed systems. Elastic dynamics model of the feed systems which considers translational degrees of freedom and rotational degree of freedom is set up, at the same time, the influence of the time-varying stiffness excitation, deviation excitation and damping on the dynamics system is also considered. The calculation method of the meshing stiffness and meshing damping are introduced，and the coupling stiffness matrix and coupling damping matrix are derived. Based on dynamic model of the system, natural frequency and the mode of vibration of the feed system, and the influence of bearing stiffness, torsional stiffness, mesh stiffness, mass and equivalent moments of inertia on natural frequency of the system have been studied. Elastic dynamics response of the feed systems excited by time-varying mesh stiffness and error stimulation has been computed using the Newmark numerical method, including the dynamic gear mesh force and vibration displacement of the components. Finally, measure of decreasing the crawl phenomenon of the feed systems is suggested in this paper.
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