Study On Extrusion Forming Law And Process Optimization Of Thin-walled Longitudinal Reinforcement Components With High Strength Aluminum Alloy

In recent years,with the rapid development of industries such as aerospace and missile weapon systems,large and complex aluminum alloy thin-walled parts with ribs have been increasingly reused.It is a typical representative of thin-walled component with I-type longitudinal reinforcements in aluminum alloy.It is applied to key parts of new aerospace and weaponry and is an indispensable high-performance lightweight component in aerospace and national defense equipment.The existing joint forming manufacturing method of the component has many drawbacks,and the extrusion forming process can realize the integral forming of the thin-walled component with reinforcement,which can replace the traditional joint forming,and is of great significance.In this paper,6061 aluminum alloy was used as the matreials firstly,and the extrusion die design was designed for the thin-walled aluminum alloy component with I-type longitudinal ribs.The actual extrusion simulation model was established on the platform of HyperXtrude software.The extrusion process was simulated by setting reasonable extrusion parameters.The forming law of the metal material in the extrusion process was analyzed and discussed,including the deformation of the profile and the flow law of the material in the cavity of the die.Studies have shown that the uneven flow of metal material during extrusion is the main reason for forming defects of profiles.Aiming at the forming defects during extrusion process of 6061 aluminum,the effects of adjusting porthole,adding baffle-blocker and adding secondary welding chamber on extrusion forming were systematically investigated.The results show that the metal flow velocity can be increased by increasing the area of the porthole in the region where the metal flow velocity is slow.The baffle-blocker has a slowing effect on the metal flow near the entrance of the die hole;The secondary welding chamber can play a fine-tune role on metal flow uniformity in the later stage of structural optimization.In addition,the extrusion process parameters such as extrusion speed,billet preheating temperature and die preheating temperature were investigated by using the control variable method.It is found that with the increase of extrusion speed,the average temperature rise of profiles is very significant,and the extrusion force is also greater.The increase of the billet preheating temperature can reduce the deformation of the profile and make the metal flow rate more uniform.Excessive extrusion speed and die preheating temperature will increase the non-uniformity of metal flow.On the basis of the optimization design of the die structure and process parameters in the previous extrusion forming process,7075 aluminum alloy was used as the material to construct a precision extrusion simulation model.The multi-objective optimization design of extrusion process was carried out based on Taguchi method,and the optimum parameters combination of extrusion process was obtained by using S/N ratio and ANOVA,and the extrusion process was predicted and analyzed in combination with the actual production.The research results show that in the process of extrusion molding of 7075 aluminum alloy,the deformation of profile can be reduced and the quality of profile can be improved by using multiple die optimization measures,such as expanding the entrance area of porthole and increasing the baffleblocker in both upper and lower dies.In terms of extrusion parameters,the lower extrusion speed and the higher billet preheating temperature should be selected,while moderate die preheating temperature and extrusion cylinder preheating temperature should be selected.