Macro-micro Coupling Simulation Of Radialaxial Rolling Of Large 7050 Aluminum Alloy Coned Ring

Large 7050 high-strength aluminum alloy ring is a large-scale application in key bearing components such as launch vehicles.It has extremely high requirements for its forming quality and performance.The radial and axial rolling forming of rings is the main process method for producing 7050 aluminum alloy seamless rings.At present,the radial and axial rolling process of large special-shaped rings faces many problems and difficulties.The first is the stability control during the rolling process.The cross-sectional material flow of special-shaped rings is complicated,and the stability is difficult to control.Inconsistency can easily lead to large ovality of the ring,poor stability of the rolling process,and scrapping of the ring.The second is the control of the microstructure of the ring.The complex dynamic local deformation and changing forming conditions of the ring radial and axial rolling make it difficult to predict and control the organization of the ring.This article mainly focuses on the control of rolling stability and the prediction of microstructure evolution during the radial and axial rolling of large 7050 aluminum alloy rings.First,generalize the dimensions of the cone ring,and calculate the relationship between the wall thickness and the outer diameter of the tapered ring through the principle of volume invariance,and derive a core roller design suitable for all rings with a uniform growth rate of outer diameter.Give the curve.Based on the Abaqus platform,a closedloop control system for ring rolls has been developed.By setting sensors on the ring,the change in the position of the sensor is obtained in real time,and the outer diameter change of the special-shaped ring is calculated.Feed back to the remaining rolls for the control of guide rolls,cone rolls and core rolls to achieve a closed loop.Among them,for the core roll,the feedback body uses the change in ellipticity during the ring rolling process,which is beneficial to improve the stability of the special-shaped ring rolling process and reduce the ellipticity of the ring.According to the 7050 aluminum alloy hot compression experiment,a high-temperature 7050 rheological model was established.Based on the above results,a three-dimensional finite element model for the radial and axial rolling of7050 aluminum alloy conical ring was established.In order to allow the calculation results to be applied to actual production,a design of constraint conditions for the radial feed of the tapered ring core roller is established.According to the static conditions of the rectangular ring,through the slicing method of the tapered ring,the constraint conditions applicable to the tapered ring are obtained,including the bite condition,the forging condition,the limitation of the rolling force,and the outer diameter of the ring.The maximum growth rate is restricted.According to the results of finite element and actual production experiments,the validity of the constraint condition is verified.Through the isothermal heat preservation experiment of rolled 7050 aluminum alloy,a cellular automata model of the microstructure evolution of 7050 aluminum alloy is established.According to the experimental grain evolution morphology,an initial structure with different rolling dislocation densities is established,and the simulation results are in good agreement with the experimental results.It shows that the finite element model can effectively predict the microstructure evolution of 7050 aluminum alloy recrystallized grain size and volume fraction.And according to the experimental results,the corresponding relationship between the time step of the cellular automaton and the real time is unified,and a bridge that couples the macro and the micro is built.The dislocation density evolution model during the ring rolling process,the topological deformation model of the grains during the deformation process,and the cellular automata model of the 7050 aluminum alloy recrystallization nucleation and growth verified in the previous chapter were established.A cellular automata model that realizes the micro-evolution of the ring rolling process.The macroscopic rolling process is completed by the finite element model of the three-dimensional tapered ring radial and axial stable rolling,and the strain and temperature field are extracted as the input conditions of the micro evolution model,and the macro and micro coupling simulation analysis of the ring rolling process is realized.The results show that the time in the ring rolling process is shorter,and the recrystallized large-angle grain boundary grains have a smaller average grain size.According to the coupled macro and micro model,the influence of the growth rate of the outer diameter of the ring and the temperature of the blank on the rolling stability of the 7050 conical ring and the microstructure are studied.Designed by CCD experiment.The response surface model of ring outer diameter growth rate,billet temperature on rolling stability and microstructure evolution is established.The results show that the ring outer diameter growth rate has a higher impact on the response values within the designed parameter range.temperature.Combining the analysis of 4 sets of response surface models,the optimal solution process parameters are 6.0mm/s of outer diameter growth rate and the initial blank temperature of 430?.