Design, Modeling, and Performance Analysis of a 2D Non-Resonant Flexible Vibration-Assisted Polishing Device with a Series Large-Displacement Parallel Mechanism

To address the issues of graphite flaking and interfacial microcrack propagation during conventional polishing of multiphase heterogeneous materials such as ductile cast iron, this study designed and validated a two-dimensional non-resonant flexible vibration-assisted polishing device (RVAPD) based on a series–parallel structure combined with a Scott Russell mechanism. The device decouples spatial motion from mechanical transmission through an irregular flexible hinge network. A theoretical model is established using the flexible matrix method and Lagrange equations, and static and dynamic simulations are conducted using ABAQUS finite element software. The simulation results show that the input and output stiffness values are 19,524 N/mm and 8197 N/mm, respectively. Experimental measurements revealed a natural frequency of 1120 Hz, a maximum output displacement of 12.58 μm, an output stiffness of 7200 N/mm, a static response delay of only 114 ms, and a positioning error below 2.76 μm, confirming the device’s high stiffness, wide bandwidth, and precise motion control capabilities. Polishing experiments indicate that 200 Hz provided the best surface-quality performance among the tested excitation frequencies, at which the surface roughness Sa decreased from 0.049 μm without vibration to 0.036 μm, while the maximum height Sz decreased from 1.927 μm to 0.983 μm. The polishing performance slightly deteriorated at 300 Hz, with Sa increasing to 0.043 μm. These results indicate that the tested excitation conditions can influence the surface-quality characteristics of the polished ductile cast iron. This research provides a basis for non-resonant vibration-assisted polishing of multiphase heterogeneous alloys.