Stiffness Identification of Spindle-Toolholder Joint Based on Finite Difference Technique and Residual Compensation Theory

摘要

The chatter vibration in high-speed machining mostly originates from the flexible connection of spindle and toolholder. Accurate identification of spindle-toolholder joint is crucial to predict machining stability of spindle system. This paper presents an enhanced stiffness identification method for the spindle-toolholder joint, in which the rotational degree of freedom (RDOF) is included. RDOF frequency response functions (FRFs) are formulated based on finite difference technique to construct a completed spatial FRF for the joint, where the measured data can be obtained from the piezoelectric acceleration sensors. In order to depress the influence of "modal truncation" and measurement noises, residual compensation theory is introduced to regenerate the RDOF FRF. Experiments are conducted to demonstrate the efficiency of the proposed model in stiffness identification of spindle-toolholder joint, and the accuracy is significantly improved compared to the traditional model.