Research On A Single-step Spinning Process For Symmetrical Thickening Of Disk-like Parts

Manufacturing technology directly reflects a country’s level of productivity,and its benchmark is automotive industry.The light weight technique which can effectively improve the utilization rate of the fuel and reduce the emission of harmful gas,has attracted more and more attention.So it’s unfit to manufacture disk-like parts with both thin web plates and thick rims via welding and machining.Therefore,using the spinning thickening process which is developed from the sheet metal stamping-forging and spinning technique,is an important development direction to produce this kind of parts.In this process,the blank is a circular plate with a large diameter and uniform thickness,and the rim of the plate is thickened by feeding of a roller with outside groove.In this paper,based on the spinning process for single side thickening of disk-like parts,the spinning process for bilateral symmetrical thickening of parts is put forward.In this paper,the deformation characteristics,forming law and the relationship between the parameters of the process are studied by means of finite element simulation.The least squares method is used for curve fitting,and the formula for calculating the value of each parameter of forming limit is obtained.The reliability and accuracy of the finite element analysis results are verified by the experimental results.The results shows that the forming process can be divided into three stages,the first stage,the blank is being uniformly thickened;and in the second stage,the blank appears to be swinging up and down,and it can be restored under the constraint of the roller groove.In the third stage,the blank is thickened smoothly until the groove is fully filled.The equivalent stress and strain of the billet are symmetrically distributed in the first and third stages;and in the second stage,the stress and strain in the upper part of the arch are relatively low.In the forming process,the radial load is the largest,followed the tangential load,and the axial load is the smallest.There are two kinds of failure forms in the spinning process for symmetrical thickening,which are the extrusion failure and the folding failure.All of them occur in the second stage of the forming process,which can be avoided by decreasing theγvalue or decreasing theαand h values.In this paper,the values of different parameters of forming limit under different values ofαand h are obtained.The study found that whenγ≤4.8,the maximum bending degree₈（6）≤0.1,and the blank can always be uniformly thickened until the process is over.Besides,with the increase of theαand h values,the filling capacity of the roller groove is worse.The limit ratio of thickening,η_max,increase with the increase ofαvalue,and the larger the h value,the slower the growth rate.Moreover,the greater the values ofγand h are,the smaller the value ofη_maxax is.The least square method is used to fit the relation curve between l_max andα,and a dimensionless quantityεis set to merge fitting formulas under different values.Therefore,with the geometrical relationship among the parameters,calculation formulas of parameter values of forming limit are given.