Experimental Research And Numerical Analysis On The Scatter Of Surface Residual Stress Induced By Precision Grinding

It is well known that residual stress induced by precision grinding is a predominant factor influencing the fatigue life and reliability; however, there is few reports in literature of any analysis of residual stress scatter coming out of a production line. In this paper, the impact of manufacturing process on residual stress scatter is experimentally investigated, and samples are selected randomly form a grinding production line. Then, based on finite element method (FEM), the impact of rake angle of abrasive grain on the residual stress distribution is analyzed. The variances of selected samples'fatigue life induced by residual stress scatter are calculated finally.Main contents and conclusions are as follows:16 wheel hub bearing rings of tractor are randomly selected from a production line. The manufacturing process of the rings includes heat treatment, rough grinding, fine grinding and horning. And the circumstantial residual stress and axial residual stress are measured by applied x-ray diffraction technique. Then residual stress scatters of inner bearing rings for the four processes are statistically analyzed. And for the first time the cumulative impact of grinding process on surface residual stresses scatter is researched. The results shows that the standard deviation of residual stress decreased from heat treatment, 59.95MPa, to horning process, 18.27MPa, which indicates grinding impact the surface residual stress scatter of inner bearing rings directly. The scatter is a process of gradually getting smaller, and the surface residual stresses have a higher consistency after horning.A mechanical-thermal model for single abrasive grain cutting process with negative rake angle is built by finite element software Deform-2D. The impact of negative rake angle of abrasive grain on the residual stress distribution is simulated. The results revealed that with the increase of abrasive negative rake angle, the residual stress increases. The standard deviation among three simulated results is 145.76MPa, which indicate the dispersion of negative rake angle of abrasive grain is a significant impact on residual stress. This simulation shows that the geometry randomness of the abrasive is one of the important reasons for the generation of residual stress scatter in grinding process.Under specified rate load, the variance of selected samples'fatigue life induce by residual stress scatter are calculated finally. The results showed that the residual stress standard deviation, 21.95MPa, only 5% of residual stress average, impacts the variance of fatigue life up to 51.42% of that without the consideration of residual stress.The study is the beginning of a scientific understanding of residual stress scatter induced by precision grinding. The research provides foundation for the further study the impact of precision machining process on residual stress scatter, and that impact on the prediction of fatigue life and reliability.