Towards understanding subsurface integrity alteration of gear fillet formed by gear skiving method

Abstract

The subsurface integrity of the fillet affects the gear service life during high-power-density transmission. To clarify the fillet formation in the gear skiving process, the internal subsurface integrity of gear fillets at the approach and recess sides were investigated by considering the surface texture. Metallurgical and mechanical investigations were conducted to advance the understanding of the fillet formation mechanism. The long-axis angle of the deformed grains and geometrically necessary dislocations (GNDs) of the subsurface revealed the dominant deformation mode and strain hardenability. As a result, the surface texture must be analyzed to elucidate the local cutting feature-induced plastic deformation owing to the high velocity gradient near the skived surface. The long-axis angle difference at the fillet of recess side increased approximately 5 to 10 times compared to that of the approach side, indicating that the refinement and slip-dominated deformation mode prevails at the formation of the leading and trailing fillets, respectively. Greater strain hardenability at the subsurface of the leading fillet was elucidated by the nanoindentation test and grain dislocation density. This work advances the understanding of microstructural alteration at the subsurface of the leading and trailing fillets, contributing to the gear functionality-based assessment of the gear skiving process.

Keywords

• Gear skiving
• Subsurface microstructure
• Subsurface analysis