Investigation of non-uniform preload on the static and rotational performances for spindle bearing system

In order to eliminate the deflection of spindle under external loading, a new non-uniform preload for spindle bearing system is proposed in this paper, and the effect of non-uniform preload on the static and rotational performances of the spindle system is explored both theoretically and experimentally. Seeking to reveal the role of non-uniform preload in spindle static and rotational performances under external radial loading, the equivalent transformation model is firstly built to simplify the non-uniform preload applied on the bearing. Then a simulation model is employed to analyze the variable static and rotational performances of spindle under different preload conditions. A test rig is designed to equip with spindle bearing system, inside which the measurement system is arranged to experimentally investigate how the spindle static and rotational accuracy are influenced by non-uniform preload, varying external load and rotating speeds. The results under different preload conditions show that the non-uniform preload with reasonable equivalent magnitude and direction can effectively adjust the spindle rotating center and compensate the spindle rotation error, and thus improves the rotational accuracy of the spindle system under complicated and alternating working conditions. This provides a new compensation method to the spindle deflection and rotational motion error through adjusting the non-uniformly distributed preload on the spindle bearing system.