Abstract
In this paper, a nine degree-of-freedom dynamic model of the ball screw feed system considering the contact nonlinearity between balls and raceways is established to analyze the vibration characteristics. The position relationship between raceway centers for the ball screw and bearings is determined by using the homogeneous coordinate transformation, and then the restoring force functions along the axial and lateral directions are derived. The dynamic equations of the feed system are solved by using Newmark method, and the proposed model is verified by the experimental method. Furthermore, the effect of the excitation amplitude on the axial vibration of the feed system is investigated by the frequency-amplitude curve and 3-D frequency spectrum. With the increase of excitation amplitude, the dynamic response of the feed system exits the softening, hardening type nonlinearity and jump phenomenon. Additionally, the effects of the initial contact angle, length of screw shaft and number of loaded balls on the axial vibration of the feed system in the resonance region are discussed. The results show that the dynamic model established in this paper is suitable for improving the machining accuracy and stability of the ball screw feed system.
Highlights
The ball screw is a transmission device that converts linear motion into rotary motion or rotary motion into linear motion, and it has the advantages of high position accuracy, load capacity and fatigue life [1,2,3]
The dynamic characteristic of the feed system is the key factor to determine the machining accuracy of the workpiece and stability of the cutting process [4,5], and the nonlinear contact relationship between balls and raceways leads to the complexity and instability of the worktable vibration [6,7]
The establishment of a dynamic model of the feed system is of great significance to improve the machining accuracy and stability
Summary
The ball screw is a transmission device that converts linear motion into rotary motion or rotary motion into linear motion, and it has the advantages of high position accuracy, load capacity and fatigue life [1,2,3]. The dynamic characteristic of the feed system is the key factor to determine the machining accuracy of the workpiece and stability of the cutting process [4,5], and the nonlinear contact relationship between balls and raceways leads to the complexity and instability of the worktable vibration [6,7]. The feed system contains many kinematic joints, and their contact load distribution is an important factor to determine the static behavior and contributes to the dynamic behaviors of the feed system. Assuming that the contact angles do not vary after loading, Mei et al [8] analyzed the effect of the ball errors on the load distribution of the ball screw. Bertolaso et al [9] studied the contact load of the ball screw by experimental and numerical methods. Considering the axial and lateral deformations of the screw shaft, Lin et al [10]
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