Dynamic stability enhancement of weak stiffness grinding system through microstructure-induced spatial force regulation

Weak-stiffness grinding systems are highly susceptible to force disturbances and prone to dynamic instability, which severely constrains machining accuracy, efficiency, and reliability. To overcome the limitations of conventional approaches that mainly depend on energy-field assistance or external damping compensation and fail to regulate the system intrinsically from the force source, a dynamic stability enhancement method based on microstructure-induced spatial force reconstruction is innovatively proposed. A dynamic stability comprehensive model of grinding system was established, which considered the multi-random characteristics of microstructured grinding wheel, macro–micro multiple regeneration, spatial grinding force, instantaneous grinding vibration, grinding stability boundary and dynamic reliability, thereby elucidating the intrinsic mechanism by which microstructures stabilize weak-stiffness grinding systems through spatial grinding force reconstruction. Comprehensive experiments, including static deflection and modal tests, sub-nanosecond laser fabrication, micro-tooth internal thread grinding, and profile measurements, were conducted to validate the theoretical models. The results demonstrate that the model accurately predicts the dynamic stability of the grinding process, achieving peak simulation accuracies of 94.8 % for spatial grinding force and 97.3 % for vibration. The microstructure angle modifies key cutting conditions such as edge angle, number, radius, and contact length, thereby redistributing grinding forces toward the high-rigidity axial direction. At a microstructure angle of 45°, the axial component proportion reaches the maximum value of 38.1 %, expanding the critical stability width by 47.3 % along the high rotation speed. Furthermore, the microstructured grinding wheel significantly improves the machining quality of large aspect-ratio internal threads, reducing the bottom fillet radius by 90.4 %, while the system reliability reaches 98.87 %.