Surface Improvement and Durability of Case-Carburized Gear - Results of Basic Rollers Running Test -

A surface durability of case-carburized and hardened steel rollers is examined by a highly loaded two rollers contact fatigue testing machine. The surfaces of test rollers are finished to a surface roughness of about 3μmRmax by a cylindrical grinding machine. Thereafter, in order to improve the ground surface, the processes of shot peening, barrelling and hydraulic horning are employed. These processes can be applied to surfaces with complex configuration, such as gears. Each surface roughness of rollers finished by above machining processes is measured before/after running test, and residual stress in the vicinity of the surface of test pieces is also detected by an X-ray diffraction method. It is confirmed that the surface durability of rollers whose surfaces are subjected to the barrelling process after the shot-peening process is appreciably improved.