Research On Forming Process Of 2219 Aluminum Alloy Profile Ring

Transition ring is a key structural part of launch vehicle tank,which is connected with the bottom of the tank,the barrel section and the short shell,and bears complex loads such as axial pressure,bending moment and internal pressure under working state.The typical Y-section transition ring is made of 2219 aluminum alloy by cutting the rectangular section ring.This method has low material utilization,and the transition rings still have obvious anisotropy and low axial elongation.At present,the technology of profile ring rolling has not been broken through in China,and there are some technical bottlenecks such as rolling instability,difficult to control the ring size and uneven structure and properties.The use of profile rings to replace rectangular section rings is the development trend of high-performance manufacturing technology for transition rings.In this paper,a new technology for forming profile transition ring with mandrel forging is proposed,and the finite element simulation and experimental research of it is carried out by taking the typical Y-section transition ring as an example.The main work and achievements of the paper are as follows:(1)The isothermal compression experiment of 2219 aluminum alloy was carried out,and the flow stress constitutive equation of 2219 aluminum alloy was established.The experimental results show that the steady flow stress of 2219 aluminum alloy increases with the decrease of deformation temperature in the range of 160 ℃ to 510 ℃,and the strain rate is proportional to the flow stress.The prediction accuracy of the flow stress constitutive equation is high,and the correlation coefficient between the predicted value and the measured value is 0.989.Based on the constitutive equation,the material model of 2219 aluminum alloy is improved,and the finite element models of the forging,preforming and final forming process of the profile ring are established.(2)Finite element simulation of forming process of profile ring was carried out,the influence of main process parameters on forming quality of profile ring was proved,and the section shape of final preform was optimized.The simulation results show that the billet with large plasticity can be obtained by increasing the deformation and adopting multi-direction forging.The uniform deformation of rectangular cross section ring billet is better when the preforming single down pressure is 15 mm and the mandrel rotation is 30°～40°.The final forming is divided into three times of pressing,and the mandrel angle of the third time is reduced from 20° to 15°,which can improve the deformation uniformity and surface quality of the profile ring.(3)The forming experiment of 2219 aluminum alloy profile ring was carried out,and the Y-section transition ring with good cross-section filling and high surface quality was obtained,which verified the feasibility of the new process.The experimental results show that the temperature drop in the final forming process can be effectively restrained by the annular outer die and the special-shaped mandrel,and the deformation temperature of the ring billet is always in the ideal range.The process of forging,preforming and final forming can effectively refine the grain,and the second-phase particles after breaking is evenly distributed in the profile ring.The crosssection filling rate of the profile ring can reach 99.5%,and the size error is less than 1%.After T8 heat treatment,the strength and elongation difference of the profile ring in all directions are less than 2%.