Simulation Of Ring Upsetting Deformation Law And Research On New Technology Of Retaining Ring Upsetting Strengthening

With the increase of power demand and the development of manufacturing industry,the relevant requirements for large generator sets are increasing.As one of the important components of the generator set,the retaining ring is required to have enough high yield strength,good plasticity and toughness,low permeability and excellent corrosion resistance under special service conditions.However,the retaining ring strengthened by traditional hydroforming process is easy to reach the strengthening limit under the action of tensile stress,and is easy to be damaged by residual stress in the process of subsequent use.So the service life is reduced.In view of the problems existing in the traditional hydroforming strengthening process,this paper creatively proposed a new technology of expanding and upsetting the retaining ring with compression stress as the main deformation.On the basis of the research on the upsetting deformation and instability of the ring,the new technology of expanding and upsetting strengthening of retaining ring was further studied by means of simulation and optimization.And based on the process parameters determined by simulation and optimization,experiment was carried out.Using Abaqus software,the upsetting deformation of rings with different heightdiameter ratio and different diameter ratio was simulated with different reduction.The influence rules of various factors(height-diameter ratio,diameter ratio,reduction)on the shape characteristics(concave single drum shape,outer convex single drum,double drum)of forgings were obtained.Based on the analysis of the stress and strain during the deformation of the ring,the partition model of upsetting deformation of the ring with different shape characteristics was established based on the distribution of the equivalent plastic strain.Based on the analysis of stress state,the upsetting instability law was obtained.The ring with large heightdiameter ratio and small diameter ratio is more likely to lose stability when the reduction is greater.Using Matlab software to fit the relationship between ring shape parameters,reduction and maximum circumferential stress,the upsetting instability model was established.A new technology for expanding and upsetting the retaining ring was proposed.The process was simulated by using Abaqus software,and the changes of equivalent stress,equivalent strain and radial displacement of the retaining ring during the expanding and upsetting process were analyzed.Taking the uniformity of equivalent strain and radial displacement as the optimization object,the optimized die size and reduction were obtained by using Isight software.Under the optimization model,the equivalent strain of the retaining ring was more uniform and the shape was more suitable requirements.Conduct the expanding and upsetting strengthening test of the retaining ring,analyze the shape and size of the retaining ring after expanding and upsetting deformation,and conduct tensile test at room temperature on the strengthened retaining ring.The results showed that the shape error between experiment and simulation was less than 5% and the mechanical properties of retaining ring had been greatly improved.The correctness of the numerical simulation and rationality of the process were verified.