Research On Ring Billet And Feeding Strategy Design For Profile Ring Rolling Of IN718 Super Alloy

Ring rolling is a technology which can reduce the ring's section dimension,expand ring's diameters and shape the section contour using ring rolling mills.Based on the shape of final ring part,the process can be divided into rectangular ring rolling and profile ring rolling.Up to now,forming technology of rectangular ring rolling is relatively mature.However,because of variety of final ring part,complexity of contact boundary and nonlinear of process,quality of rolled profile ring can't satisfy the designed requirements,so there are so many researches need to do to improve the quality and accuracy of profile rolled ring.In this paper,a receiver profile ring of IN718 super alloy was taken as example,the ring billet and feeding strategy of profile ring rolling process were designed systematically.Firstly,based on the similarity of shape between ring billet and final ring part,the feasibility of blocking,the contact situation between ring billet and rolls,four types of ring billet structure were designed.After that,finite element simulation analysis of ring rolling was conducted with different ring billet structures,and the filling rate of ring cross section can be obtained.Based on the results,the best ring billet structure can be chosen considering the filling situation of final ring part.And then,parametric design of ring billet was carried out.Taking some limit conditions into account,the ring billet can be represented by dimension parameters.Using response surface method and finite element method,a response model can be gained,of which the object function was filling rate of ring cross section and the variables were ring billet dimensions.It can be found that with the decrease of ring billet inner radius,the filling rate of ring cross section increases;with the increase of ring billet height,the filling rate will increase at first and then decrease.After the filling situations of different ring cross regions was studied,un under-filling distribution map can be gotten,from which the optimized ring billet can be designed and the forming defects can be predicted and avoided.And then,feeding strategy was designed based on the optimized ring billet.The single-factor experimental method was used to design main roll's rotation speed and mandrel's feeding rate.After that,simulation analyses with different rolls' feeding rates were carried out by finite element method.According to simulation results,the effects of rolls' feeding rate on temperature distribution of forging,filling situation of ring cross section,deformation uniformity of rolled ring,forces of rolls were investigated.In order to improve microstructure properties of final ring part,increase filling rate of ring cross section and reduce the rolls' force,the optimized rolls' feeding rates were chosen.Next,three kinds of rolling curves were designed,and the influence of rolling curve on steady of rolling,quality of end plane of ring were studied,and the optimized rolling curve was determined.At last,the reasonable process plan of ring rolling was determined,including the design of ring billet and feeding strategy.And the practical profile ring rolling process was carried out in a stable manner without macroscopic or microscopic defects,which indicates the design methodology for the profile ring rolling process is reasonable.