Rolling Contact Fatigue Life Prediction Based on the Surface Integrity Induced by Grinding Process
|School||Shanghai Jiaotong University|
|Course||Mechanical Manufacturing and Automation|
|Keywords||Grinding Bearing inner ring Surface integrity Rolling contact fatigue Life Prediction|
Grinding is usually as important parts last a precision machining process, grinding process is formed in the surface of the part surface roughness, micro-hardness, residual stress and surface integrity indicators on the service life of the parts has a direct impact on reliability. Engineering applications, usually only detect the geometric characteristics of the surface roughness of the grinding parts, and the physical properties of the micro-hardness of the surface layer of residual stress rarely be detected and controlled, thereby based Part grinding surface integrity grinding parts life prediction has not been reported. Bearing inner race of this article will be the actual industrial applications for the study of the carrier, the surface integrity of the formation process based on the actual grinding process, the parts rolling contact fatigue fatigue life prediction. The main content of this paper include: First of all, the formation of surface integrity indicators of residual stress, microhardness and fracture mechanics theory based parts machining process, establish a rolling contact fatigue initiation life and propagation life prediction model and correct LP model with which contrast. Comparison Authentication life test data show that the life model has high prediction accuracy. Second, a random sample of the actual industrial production line bearing inner ring as a sample, test the residual stress in the surface layer of the inner ring specimen raceway surface after heat treatment, rough grinding, fine grinding, ultra-precision four processes, microhardness, surface roughness and surface integrity indicators, analyzes the changes in the parts of the surface layer of residual stress and its dispersion after each step. The results show that: the parts of the surface layer of residual stress, microhardness with discrete physical performance, and its dispersion accumulated over process was convergence trend. This reveals the traditional grinding process enables the integrity of the surface of the part to gradually achieve better consistency. Finally, based on the life of rolling contact parts model established in this paper, the residual stress of the parts of the surface layer of ultra-precision process, the microhardness its dispersion of parts rolling contact fatigue initiation life and extended the life of law;, and ultra-precision the fatigue life of the grinding parts were predicted indirect authentication of the bearing life test data according to the step-like, on the predicted results. Predict results consistent with the experimental results. The integrity of life prediction based on the grinding surface of the part: The results showed that the maximum peak of residual stress and microhardness along the depth distribution of fatigue on the part contact life have a greater impact, the influence of residual stress on fatigue life greater; standard deviation of the residual stress in parts of the surface layer of ultra-fine grinding process after the maximum peak only 20MPa, that only 16% of the average, but the poor bending fatigue life was as high as 4 times. This article from the perspective of the grinding process reveals parts service life greater dispersion of reason, provides improved process the parts reliability process control pathways, and therefore the extension of the precision parts (such as bearings, gears, etc.) service cycle has very good scientific value, and actual industrial production line improvement and optimization of engineering significance.