Extrusion Die Optimization Design And Research On Transverse Weld Evolution Of Aluminum Alloy Fin Tube

Aluminum is a kind of material with good performance. It has been widely used for producing various high precision and complex solid or hollow profiles due to its properties such as lightweight, ease of recycling, high strength ratio, good plasticity, good conductivity and thermal conductivity. Nowadays, aluminum alloy has been widely used in building structures, aviation manufacturing, car industrial, ship manufacturing and electronic equipment fields, especially in modern traffic transport field, the demands of car body lightweight design and energy saving are quite urgent, large complex aluminum alloy profiles have entered a rapid development period.Currently, aluminum alloy profiles are produced by extruders. The quality and production efficiency of aluminum extrusion profile are influenced by extrusion process parameters. Aluminum profile forming process is quite complicated, which involves severe material deformation and complex friction and thermal condition, it is difficult to observe the material flow directly in the extrusion process. Mold design depends on the material flow condition. Transverse weld impacts the profile mechanical property severely. However, the study on transverse weld formation and evolution is still not enough.A large, hollow fin tube extrusion profile with small geometry features is analyzed and the extrusion mold is designed in this paper; extrusion process numerical simulation model is established by using HX software; hot compression experiment of AA 7005 aluminum is carried out; in order to describe material of flow behavior accurately, the constitutive equation of AA 7005 is established; the speed field, deformation field and temperature field of bearing export section during extrusion process are analyzed; in order to solve the distortional deformation problem of the extrusion profile, the effect of portholes and the cavity shape on extrusion process are explored. Optimization results show that material flow speed of the profiles export section is balanced; the effect of flow block on metal flow speed is researched; the bearing length is optimized for purpose of adjusting the material flow speed. In addition, the stress, deformation and temperature distribution of extrusion mold are also analyzed.The formation and evolution of transverse weld during billet to billet extrusion process are studied. The effect of extrusion ratio and ram speed on transverse weld extent is analyzed, the relationship between the shape of dead zone and the extent of transverse weld are investigated, the dead zone border line is fitted and welding chamber is optimized. Simulation results show that the dead zone becomes narrow and transverse weld length of extrusion profile is decreased by about 20% after optimization. The results indicate that adjusting the shape of dead zone is an effect way to reduce the transverse weld length.