Dynamic design for motorized spindles based on an integrated model

With increasing popularity in high-speed machining for its high efficiency, motorized spindles have been widely utilized in modern production facilities. Due to the combination of tools and built-in motors, the dynamic characteristics of motorized spindles are more complex compared with conventional spindles, and it is becoming necessary for engineers to thoroughly realize the influences of the system parameters to the system dynamics with considering the multi-physics coupling property. This paper presents an integrated model to study the electro-thermo-mechanical dynamic behaviors of motorized spindles. The integrated model consists of four coupled submodels as follows: bearing, built-in motor, thermal, and shaft model. Based on the proposed model, a design flow chart is developed and six design parameters are identified. The integrated model is validated experimentally and a design sensitivity analysis of the six parameters is then conducted based on a 170MD15Y20 type spindle. The results show that the integrated model is capable of accurately predicting the dynamic characteristics of motorized spindles, and the sensitivities of the six design parameters to the nature frequencies of the spindle system are obtained with and without the influence of the multi-physics coupling property. The coupling relationship among the electrical, thermal, and mechanical behaviors of the spindle system becomes clear from the results.