Fretting Fatigue Life Of GCr15 Bearing Steel Based On Strengthened Grinding Processing

Industrial robots are key to "Made in China 2025",Fretting fatigue damage is one of the main failure form of basic parts to industrial robot speed reducer.As a new surface treatment technology,Strengthened grinding can effectively reduce fretting fatigue damage of reducer parts and prolong their service life by introducing surface texture-like layer and strengthening layer.GCr15 bearing steel is the main manufacturing raw material of the basic parts of the reducer.It is of great significance to study the fretting fatigue life of GCr15 bearing steel after Strengthened grinding.In this paper,taking GCr15 bearing steel as the research object,by means of theoretical analysis,simulation exploration and experimental exploration,the effects of different coverage rates of Strengthened grinding on surface integrity and fretting fatigue life were studied,and the anti-fretting fatigue life extension mechanism of Strengthened grinding was explored,and its life prediction and analysis.The main work and conclusions are as follows:(1)Surface integrity analysis of GCr15 bearing steel by Strengthened gringing process was carried out.Based on the secondary development of Abaqus/Python,the simulation model of random uniform distribution of Strengthened grinding steel balls was established to explore the variation rules of residual stress,surface roughness,equivalent plastic deformation and energy of GCr15 bearing steel under different Strengthened grinding coverage;at the same time,experimental verification was carried out.The results show that: The theoretical,simulation and experimental results are consistent.With the increase of Strengthened grinding coverage,surface roughness of up and down first then remain stable,cross-section strengthened layer thickness increase amplitude decreases,cross-section microhardness increased after the first decreases,and the surface residual compressive stress increases after the first decreases,and the residual compressive stress increases after the first stable.(2)Fretting fatigue tests of GCr15 bearing steel on Strengthened Grinding Processing were carried out to observe the wear morphology and fracture morphology of fretting contact area,and explore the influence law and mechanism of surface integrity of GCr15 bearing steel on fretting fatigue life;Meanwhile,a fretting fatigue simulation model was established to predict the crack initiation location and initial propagation Angle.The results show that the fretting fatigue life increases first and then decreases with the increase of enhanced lapping coverage,but it is higher than that of unenhanced lapping specimens.The fretting fatigue life increases the most when the coverage rate is 300%.Meanwhile,the surface wear degree of fretting contact area decreases first and then intensifies,fatigue crack source location,according to the surface depth increases first and then fatigue fracture bands spacing,increase with the decrease of the first toughening nest become smaller,lighter,this is the GCr15 bearing steel surface roughness,microhardness and residual compressive stress;The upper edge of the contact zone is 1.7mm ? 2.0mm away from the center line,and the initial propagation Angle of crack initiation is within 73.5° ? 96.8°.The error is within a reasonable range compared with the simulation results,and the prediction effect is good.When the coverage rate is 300%,the life improvement is the largest.(3)The fretting fatigue life prediction model of GCr15 bearing steel on Strengthened Grinding Processing was established,and the reliability of predicted life value was analyzed by Using Weibull distribution.The results show that the reliability of predicted life values is more than 85%,indicating that the fretting life prediction model and the method considering the main influencing factors established in this paper are effective and feasible.