Study on Nonlinear Dynamic Characteristics of Motorized Spindle Considering Toolholder Connection and Electromagnetism Under EHL Condition

Purpose The nonlinear dynamic characteristics of the motorized spindle have a great influence on the precision of processed products in manufacturing. Aiming at the above issue, a new comprehensive motorized spindle dynamic model considering multiple factors was proposed in this paper to investigate its dynamic performance more seriously. Methods First, the angular contact ball bearing was mainly analyzed, in which the oil film thickness and stiffness were considered, and then a bearing mechanical analysis model was established based on the quasi-static analysis method. Simultaneously, the effect of the centrifugal force and gyroscopic moment of the ball on the contact angle was included in the bearing model. Second, the preload of the bearing was investigated, and the Hertz contact load on the rings was identified and classified. Next, the fit clearance between the outer ring and the bearing housing, the static eccentricity between the stator and rotor, and the static eccentricity angle were added in the spindle model, to study the dynamic performance of the rotor more truly and effectively. In addition, the contact characteristics of the cutter head and the rotor were presented in the model. Results The change of bearing contact angle has an important influence on the dynamic characteristics of the spindle as the contact angle becomes lager. Simultaneously, the clearance value of the bearing affects the unbalanced magnetic force. In addition, static eccentricity has a great effect on the dynamic behavior of the rotor. Under the same length error and length range, the impact of static eccentricity on the rotor dynamic performance is greater than that of fit clearance. Conclusions Various structural and dynamic parameters are coupled with each other in spindle dynamics. Therefore, it is necessary to systematically consider and analyze various factors to establish a comprehensive and effective dynamic model.

Automated summary

In this paper, a comprehensive motorized spindle dynamic model was proposed to investigate its dynamic performance more seriously, considering multiple factors such as bearing, preload, fit clearance, and static eccentricity. The results show that the contact angle of the bearing, the clearance value, and the static eccentricity have significant impacts on the dynamic characteristics of the spindle.