Prediction and experimental verification of time-varying dynamic parameters for milling thin-walled workpieces

The time-varying characteristics of dynamic parameters during the thin-walled part milling process significantly affect the prediction of milling stability regions. To accurately and efficiently acquire these time-varying dynamic parameters, a dynamic cutting force prediction model considering the dynamic variation of cutting thickness is established. The vibration of the workpiece under dynamic cutting forces is equivalently modeled as a thin plate subjected to vertical in-plane excitation forces, and the initial dynamic parameters of the workpiece are calculated using the assumed mode method. Material removal and feed position variations during milling are incorporated, enabling rapid acquisition of time-varying system dynamic parameters through structural dynamic modification methods. Compared with finite element simulations, the proposed method improves computational efficiency by over 90% as it eliminates the need for repetitive modeling. Unlike experimental testing approaches, this method requires only one initial measurement experiment without interrupting the in-process parameter measurements. Experimental results demonstrate significant changes in frequency response function curves and natural frequencies during material removal, with maximum frequency variations reaching 25%. The maximum prediction error between the proposed method and experimental measurements is 4.816%.