Numerical Simulation Of Aluminum Profile Extrusion Process And Die Design

Aluminum and aluminum alloys have been widely applied in aircrafts,rolling stock,civil decoration material and so on because of the unique characteristics such as easy processing, corrosion resistance,no low temperature brittleness,good conductivity and thermal conductivity.Air-conditioner aluminum profiles are produced by extrusion techniques,which have high production efficiency and can save materials.Extrusion technology of small-diameter and thin-walled aluminum tubes is investigated and developed in this thesis for air-conditioners,through experiment and finite element simulation.Internal thread die of one-pass extrusion forming was designed and manufactured,and extrusion experiments were conducted.Experimental results showed that thermal expansion coefficient and viscous are great for aluminum under high temperature,so there are some differences between thread angle and tooth height of aluminum tubes extruded and tongue of die.Meanwhile,the relation between thread angle and extrusion performance,extrusion technology should be considered.The more the extrusion speed and rotational speed of tongue of die,the more the thread angle,but thread cogging cannot be filled of deformation metal.Extrusion process of small-diameter and thin-wailed aluminum tubes by the porthole die is simulated using DEFORM-3D,influencing rules of welding chamber height and bearing length to load,the stress-strain and die stress are obtained,thus die structure parameters are optimized.Simulation results showed that stress of upper die is concentrated at porthole bridge and die mandrel,and stress of bottom die is concentrated at bearing and fillet transition region of welding chamber.Welding chamber height and bearing length have influence greatly on product quality.Experimental results show that welding strength and product quality are improved after increasing welding chamber height and bearing length.Extrusion process of small-diameter and thin-walled aluminum tubes by the porthole die is simulated using thermal-mechanical coupling finite element method,influence laws of preheating temperature on load,metal deformation temperature and welding properties of the products are obtained.Through microstructure observation of extrusion products,some conclusions are obtained that the mechanical properties of products can be improved by lowering temperature reasonably.Therefore,the reasonable preheating temperature is proposed,which improves the quality of the extrusion products.