Design Of Extrusion Die For Shaped Aluminum Profiles And Optimization Of Extrusion Process

Application of aluminum profiles have been expanded to the industrial areas like aerospace and transportation from the traditional construction industry owing to their light weight,excellent mechanical properties and high overall formation.Now aluminum profiles follow the trends of large-scale and cross-sectional complexity,which requires higher mechanical properties and better extrusion process.Defects like twists,waves,cracks and surface roughness,which are common in aluminum profiles,are mainly related to the ingot quality,mold structure and process parameters.In this paper,the effect of aluminum ingot homogenization on the extrusion process of aluminum profile was explored firstly.Then,design of porthole die was carried out taking a hollow profile as the research object.The die structure and extrusion process were improved and optimized using extrusion simulation software HyperXtrude.The main research contents are as follows:Firstly,the non-homogenized and homogenized 6063 aluminum alloy ingots were subjected to metallographic structure observation and hardness test.The results showed that at the heating temperature of 570?,the longer the holding time,the more homogeneous the alloy composition.Besides,hardness decreased with the prolonging holding time.However,when the holding time was changed from 8h to 12 h,the metallographic structure and hardness did differ significantly.Actual production test revealed that the homogenized aluminum ingots had low deformation resistance,which could be extruded with smaller extrusion force.Long-time heating(480 ?)of non-homogenized aluminum ingots before extrusion could also achieve partial homogenization effect,which was though insignificant.Secondly,extrusion die design was carried out on the structure of selected profile product from the aspects of porthole,bridge,welding chamber,pier and land.The extrusion simulation software HyperXtrude was used to analyze the extrusion process,which found stress concentration at the junction of die bridge and core and large flow rate difference at the discharge area.To address this problem,the bridge,porthole and land were improved to eventually decrease the maximum die stress to 872 MPa from 1183 MPa.Meanwhile,the speed difference between various parts of the discharge area was reduced within 10mm/s,which was a great improvement than before.Thirdly,"three temperatures and one speed" are the most important process parameters during extrusion.The effects of extrusion speed,ingot temperature,mold temperature and extrusion container temperature on the extrusion force and speed uniformity during profile discharge were studied by orthogonal experiment.Range analysis was performed on the orthogonal experimental results with extrusion force and speed variance as the evaluation indices to obtain the optimal combination of process parameters(extrusion speed 2mm/s;mold temperature 470?;billet temperature 500?;and extrusion container temperature 460?).Fourthly,actual production test demonstrated that the use of modified porthole die and extrusion process parameters allowed extrusion of profile products with good surface quality without wave,twist or other defects.In this paper,the finite element simulation technology and mathematical optimization method are applied to the analysis of profile extrusion process and the optimization of process parameters,which can provide some guidance for the die design and the extrusion process development.This is of great significance to improving product quality,production efficiency and to enhancing market competitiveness for companies.