Topology optimization of the cooling-jacket flow channel for a high-speed motorized spindle based on a T-type channel

During high-speed machining, substantial heat is generated in the motorized spindle, and the cooling-jacket configuration plays a critical role in suppressing temperature rise and maintaining spindle accuracy. Existing cooling-channel designs primarily rely on experience-based parameter adjustments, making it difficult to balance temperature control and hydraulic loss. To address this issue, this study performed topology optimization and comparative validation using a T-type channel as the benchmark. First, a two-dimensional unfolded reduced-order model was established, and a normalized multi-objective function was introduced to balance the regional average temperature and total dissipated power. Three representative topology-evolved designs, TP-I, TP-II, and TP-III, were fabricated and experimentally evaluated. Under the same heating-stage temperature and inlet-pressure conditions, the topology-evolved prototypes exhibited lower temperatures and more concentrated temperature distributions, with the maximum axial-profile temperature decreasing from 48.47 °C to 30.92 °C and the ROI-averaged temperature decreasing by 20.9%. To further examine the engineering transferability of the reconstructed topology, T-type and TP-type cylindrical cooling jackets were fabricated and experimentally evaluated under the same continuous heat-input and inlet-pressure conditions. The measured pressure drop decreased from 8.17 kPa to 7.44 kPa, corresponding to a reduction of 8.9%, while the inlet–outlet coolant temperature rise decreased from 2.33 °C to 2.15 °C. Infrared measurements showed lower average and maximum temperatures in the front and rear regions of the TP-type specimen, whereas a slight temperature increase occurred in the middle region. The range among the three regional average temperatures decreased from 0.80 °C to 0.41 °C. Three-dimensional thermo-fluid-solid analysis further showed that the front- and rear-bearing temperatures decreased by 0.45 °C and 1.17 °C, respectively, and the maximum axial thermal displacement decreased by 7.3%. Flow visualization and numerical analysis indicated that persistent vortex-core and low-flow-rate regions weakened local coolant renewal and promoted hotspot formation. These results provide an integrated design and validation framework for topology-optimized motorized-spindle cooling jackets.