Thermal-mechanical dynamic interaction in high-speed motorized spindle considering nonlinear vibration

Abstract

The neglection of thermal-mechanical interaction of the high-speed motorized spindle system may lead to modeling errors of thermal and dynamic characteristics. In this work, the thermal-mechanical interaction mechanism is analyzed, and a closed-loop iterative modeling method for thermal and dynamical characteristics is proposed to improve the modeling accuracy. The nonlinear dynamic model with thermal effects of the spindle system under unbalanced magnetic pull and unbalanced mass excitation is established to evaluate its transient dynamic behavior. A multi-node thermal resistance network model of the motorized spindle system considering the nonlinear vibration of the spindle system is established to evaluate transient thermal behavior. Based on the load-displacement relationship, the nonlinear stiffness and restoring force model of bearing considering thermal effects and nonlinear vibration is established. The heat generation of the bearing and the built-in motor are calculated by Palmgren's formula and the equivalent circuit model of the induction motor, respectively. The bearing heating is improved considering the comprehensive effects of lubricant viscosity change, bearing thermal expansion, and nonlinear dynamic load. The mechanical power loss of the motorized spindle is analyzed to calculate the electrical parameters required to study the spindle dynamics and motor heat generation. The accuracy and effectiveness of the proposed theoretical method are experimentally verified. Numerical simulations show that the thermal and mechanical effects in the motorized spindle system exhibit a non-negligible dynamic interaction.