Grinding Induced Changes in Residual Stresses of Carburized Gears

摘要

This paper presents the results of a study performed to measure the change in residual stress that results from the finish grinding of carburized gears. Residual stresses were measured in five gears using the x-ray diffraction equipment in the Large Specimen Residual Stress Facility at Oak Ridge National Laboratory. Two of the gears were hobbed, carburized, quenched and tempered, but not finished. The remaining three gears were processed similarly, but were finish ground. The residual stresses were measured at 64 different locations on a tooth from each gear. Residual stresses were also measured at fewer points on other teeth to determine the tooth-to-tooth variation. Tooth profile measurements were also made of the finished and unfinished gear samples. The results show a fairly uniform and constant compressive residual field in the non-finished gears. There was a significant reduction in the average residual stress measured in the finished gears. Additionally, there was a significant increase in the variability of the residual stress that was introduced by the grinding process. Large variations were observed in both the lateral and longitudinal directions on a tooth surface. Analysis of the data suggests a linear relationship between the change in average residual stress and the amount of material removed by the grinding process.