Static-dynamic-thermal characteristic analysis and experimental study of motorized spindle

Prolonged uninterrupted running triggers obvious thermal displacement in high-speed motorized spindles. Taking the A01 turning spindle as the research object, this work develops a split double-spiral cooling sleeve with independent flow channels for the stator and front bearing. A fluid–solid multi-field coupling model covering static, dynamic and thermal characteristics is established and partially validated via steady-state temperature tests of stator windings. Static stiffness, modal features and harmonic responses are analyzed, and heat generation of the built-in motor and rolling bearings is quantified. Fluent parametric simulations are conducted at coolant temperatures of 14–22 °C and flow rates of 4–10 L/min, and a matched closed circulating cooling device is fabricated to relieve motor heat accumulation. Results reveal axial thermal deformation dominates machining error: the maximum axial offset reaches 38.54 μm, and total deformation at the tool mounting surface is 43.91 μm. Cooling performance saturates above 7 L/min, and 18 °C serves as the optimal coolant temperature. The relative error between simulated and measured stator temperature is 8.3%. This research offers quantitative references for thermal error suppression and cooling structure optimization of analogous high-speed spindles.