The Study On The Multi-step Spinning Of Tin Bronze (QSn7-0.2) Connecting Rod Bushing

The connecting rod bushing used in tin bronze(QSn7-0.2)molding materials is an important component used in a high-power diesel engine and is a key component for connecting the small end of the engine connecting rod with the piston pin.During the engine working process,the connecting rod bushing operates in an environment of high temperature and alternating stress,and will continue to be subjected to repeat frictional of the small end of the connecting rod and the piston pin.Therefore,it requires a high demand for the use performance and reliability of the connecting rod bush.The connecting rod bushing is generally manufactured by the strong power spinning technology,which is an advanced plastic reinforced forming process that can make the fatigue strength,carrying capacity and other properties of the connecting rod bushing significantly improved.At present,the main problem encountered is that the dimensional accuracy and mechanical properties of the workpiece after single-pass strong spinning are not ideal.After the completion of the strong spinning process,the workpiece must ensure sufficient machining allowance to complete the subsequent finishing process.Sometimes,due to the unreasonable setting of processing parameters and other reasons,there is a serious inner diameter expansion in the mouth of the workpiece which makes the size of the inner diameter can not meet the requirements of the subsequent process.At the same time,due to the existence of shape error,the cutting depth in the subsequent finish turning process is different,which brings a big variation of the residual stress,the surface hardness,the metallographic structure,resulting in a greatly reduce of the product reliability.In this paper,the ABAQUS finite element analysis software was used to simulate and experimentally study the multi-step strong spinning process.A multi-step strong spinning finite element simulation model of a tin bronze(QSn7-0.2)connecting rod liner wasestablished.The single-factor experimental design method was used to study the influence of the technological parameters such as the feed speed of the rotating roller,the spindle speed and the pass reduction rate on the deformation of the workpiece during the multi-step strong spinning process.Finally,the optimal process parameters combination scheme obtained by numerical simulation was used to guide the experimental production.The connecting rod bushing was manufactured to meet the dimensional accuracy requirements.Then its mechanical properties and microstructure were analyzed.The research results show that the multi-step strong spinning process can greatly improve the forming quality of the work piece,and the dimensional accuracy of the workpiece after strong spin forming.And after testing,it is also found that tensile strength,yield strength,surface hardness etc.of workpiece have been improved greatly.