| As an important component in high power diesel engine,the quality of machining surface of connecting rod bushing directly affects the performance of diesel engine.The surface residual stress of Cu-6Ni-6Sn connecting rod bushing formed by turning is large and unevenly distributed,which will affect the dimensional accuracy,shape error,fatigue strength and other properties of connecting rod bushing,and affect the service life of connecting rod bushing.Therefore,it is of great significance to study the influence law of turning process parameters on the surface residual stress of connecting rod bushing and the influence of aging stress removal method on the surface residual stress to improve the service life of connecting rod bushing and practical production.In this paper,Cu-6Ni-6Sn connecting rod bushing is taken as the research object,and the residual stress field and stress removal methods of the turning surface of Cu-6Ni-6Sn connecting rod bushing are studied and analyzed by means of finite element simulation and test.The main research contents and conclusions are as follows:(1)Based on the stress-strain curves of Cu-6Ni-6Sn alloy at different temperature and different strain rates,a Cu-6Ni-6Sn turning constitutive model was established,combined with the finite element model of Cu-6Ni-6Sn connecting rod bushing,the influence law of turning parameters and tool geometric parameters on surface residual stress was studied,and the process parameters were optimized by orthogonal test and range analysis method.The results show : the surface residual stress of the bushing after turning presents a scoop shape distribution,and the surface residual tensile stress changes into compressive stress along the depth direction.The maximum residual tensile stress and compressive stress of surface surface are positively correlated with the turning speed and depth,and the maximum residual tensile stress decreases with the increase of the tool front Angle.The surface residual tensile stress and maximum residual compressive stress decrease with the increase of the tool back Angle.Orthogonal test method and range analysis method were used to obtain the order of significance of the influence on the surface maximum residual tensile stress: turning speed>tool front angle>tool back angle>depth of turning.(2)The stress removal tests were carried out on the bushing of Cu-6Ni-6Sn connecting rod by thermal aging and vibration aging,and the surface residual stress of the bushing was measured by blind hole method before and after aging,and the effects of the two aging methods on the surface residual stress were compared and analyzed.The results show : the two aging stress removal methods can reduce and equalize the surface residual stress,but from the mean value,range,standard deviation of each residual stress after aging and the standard deviation of internal Angle of radar map,the effect of vibration aging is better than that of thermal aging.(3)Based on ABAQUS free mode analysis and constrained mode analysis,the optimal exciting point and support point of the vibration aging of Cu-6Ni-6Sn connecting rod bushing were obtained and the optimal exciting frequency was determined;The optimal range of excitation force was determined by harmonic response analysis and the influence of different excitation force and time on vibration aging results was studied.The results show : in a certain range of exciting force and time,the exciting force and time are positively correlated with the results of vibration aging. |
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