Research On Die Forging And Cold Pressing Process Of A Main Supporting Joint Forging

The development trend of light weighting aviation structural parts has made more and more aluminum alloy forgings widely used.Among them,large-scale complex aluminum alloy forgings are often designed as ribs for weight loss.Such forgings often result in various defects due to unreasonable forming and heat treatment processes,so the formation and heat treatment of large complex ribs,To ensure the production of components with good performance,has great engineering value.This article takes the7050 aluminum alloy main landing gear support joint of an aircraft as the research object,combined with numerical simulation and data extraction technology,from forging forming,to heat treatment,to reducing residual stress process design analysis to optimize the parameters existing in each stage And defects,and then get a reasonable whole process.The main work and research results of the paper are as follows:(1)First design the final forgings based on the structural characteristics of the parts,design the pre-forgings according to the defects after one-time molding,and optimize the design for many times,forming the groove clamping and stable positioning,using variable speed motion to control the load,without obvious folding The trend results in a streamlined final forging process plan with smooth flow and no flow.Based on the selected pre-forged parts,the pre-forging conditions of the four initial billets were analyzed.After comprehensive comparison,the original square billet of scheme 3 was finally selected for pre-forming process.(2)The influence of different process parameters on the forming process and die stress and life is studied.It was found that properly reducing the forming speed,more lubrication,and raising the preheating temperature all contribute to the reduction of the forming load,while the increase in the friction coefficient and the increase in the pressing speed.Increased,and finally set the mold preheating 420 ?,friction coefficient 0.4,blank preheating 420 ?,using variable speed movement and other parameters.(3)A heat treatment model of forgings was established,namely "heating ? heat preservation ? transfer ? water quenching ? air cooling",the study found that the temperature drop in the first 60 s during the quenching process was very obvious,and the stress field changed from "external tension" before quenching to quench After the "external pressure core pull",the size of the forging also gradually reduced with quenching.At the same time,the study of the parameters in the heat treatment process found that the quenching medium has the most significant impact on the residual stress.As the quenching temperature increases,the residual stress shows a downward trend.The main purpose of considering the heat treatment is to improve the mechanical properties of the forging.The solution temperature is 477 ?,the solution time is 2h,the transfer time is 30 s,and the quenching medium temperature is 65 ?.(4)Researched the reduction of residual stress by unidirectional cold pressing and composite cold pressing,and found that they can not obtain a good effect of reducing the pressure.It is not significant,but under the cold pressure of 1.5%,the reduction situation,especially the large stress concentration area,is better.Based on this pressure,a cold pressure + aging treatment scheme is proposed.The residual stress reduction effect is all 95 More than%,finally proposed a method of variable pressure reduction,found that variable pressure reduction has a very obvious effect on the residual stress reduction of complex components.(5)Combining numerical simulation and production verification,the forming results are good and the physical and chemical testing is qualified.