Study on multi-degree-of-freedom near-net shape forming method for aviation spur gears

ObjectiveAddressing the requirements for high-quality and efficient manufacturing of aviation spur gears, and targeting issues such as incomplete tooth profile filling and excessive forming loads encountered in traditional single-degree-of-freedom forming methods like die forging and extrusion, this study innovatively proposes a multi-degree-of-freedom forming approach for aviation spur gears. This method enhances material flow capacity and reduces forming loads through continuous local loading via a multi-degree-of-freedom rolling die. Simultaneously, it refines the grain structure of the gear and generates continuously distributed metallic flow lines along the tooth profile, thereby improving the gear's strength and fatigue life. This provides a new technological pathway for manufacturing high-strength, high-toughness, and long-life aviation spur gears.MethodsFinite element simulation technology was first employed to investigate the influence of preform geometry on tooth profile filling effectiveness and forming load. Based on this, an optimized preform design method was proposed. The mechanisms of tooth profile filling, Effective strain distribution and evolution, and metallic flow lines evolution during the forming process were further revealed. Subsequently, a Multi-Degree-of-Freedom Near-Net Shape Forming experiment was conducted based on simulation results. Grain size and metallic flow lines of the test specimens were characterized to validate the finite element model and simulation results.ResultsThe results demonstrate that: Frustum-shaped preforms significantly improve tooth profile filling completeness and reduce forming load, enabling the production of fully-filled aviation spur gears. The Multi-Degree-of-Freedom forming method introduces severe plastic deformation into the tooth profile zone, effectively refining grain size and generating continuously distributed metallic flow lines along the tooth contour. Multi-Degree-of-Freedom Near-Net Shape Forming technology achieves high-performance manufacturing of aviation spur gears.