Numerical Investigation of Coolant Distribution in Gear Skiving

Epicyclic gear trains are a promising solution for increasing bypass ratios in modern turbofan jet engines. Gear skiving is a highly productive machining process for manufacturing the internal gears used in such gearboxes. It involves a rotating cutting tool and a rotating workpiece whose axes are oriented at a crossing angle, thereby generating gear teeth through continuous relative motion. Optimizing the skiving process enhances accuracy, tool life, and surface quality. However, the three-dimensional kinematics and interrupted cutting pose significant challenges for reliable coolant delivery into the cutting zone. The coolant is injected through a nozzle towards the cutting zone. Due to its interaction with the tool and the workpiece, the coolant jet breaks up and forms intricate flow structures and ligaments. This study presents an implicit incompressible Smoothed Particle Hydrodynamics (SPH) approach to simulate the free surface flow of the coolant distribution in gear skiving. The methodology enables a detailed insight into complex coolant flow structures. The commercial SPH solver PreonLab® is employed. A particle spacing of 50 μm was identified as suitable based on a resolution study. ... mehrThe numerical results are validated using high-speed imaging and subsequently applied in parametric study investigating both nozzle position and coolant flow rate effects on tool wetting. A higher wetted fraction of the tool tip improves cooling performance and may reduce friction during chip formation. The results reveal that a nozzle position not directly aimed at the cutting zone leads to improved tool wetting compared to industry-wide established alignment. Additionally, increased coolant flow rates enhance wetting levels, while reduced flow rates show diminishing effects. These findings highlight the importance of investigating coolant flow in gear skiving and provide guidance for the development of optimized coolant supply strategies.