Simulation And Research On Micro-multiport Profile Hot Extrusion Process And Pressure-bearing Property

With the development of energy conservation and emission reduction requirements,micro-multiport heat exchangers with excellent properties are paid great attention by engineers.At present,as a new type of heat exchanger,parallel flow heat exchangers with high efficiency and greens environmental protection are applied in automobile air conditioning filed.As the main component of parallel flow heat exchanger,the forming quality of micro-multiport profile,based on the hot extrusion process,has important influence on exchangers' performance and die life.However,the hot extrusion for micro-multiport profile is a complicated high temperature deformation process with multi-variable and strong coupling,it's difficult to design process planning and some key parameters exceed the standard value.Therefore,deeply research is carried out to analysis hot extrusion process and pressure-bearing property for micro-multiport profile.The flow stress behavior of Al alloy 3102 is studied by the high temperature compression tests,and based on the Zener-Hollomon approach,constitutive model is established by the modified Voce hardening model with linear softening term.Furthermore,the constitutive is verified by the comparison of predicted results and experimental results.Based on the Qform-Extrusion software,a finite element model is established to simulate the hot extrusion for micro-multiport profile.Good agreements of extrusion load,billet temperature near die outlet and the head configuration of profile between FEA and testing results are obtained,which verifies the accuracy of the simulation.The virtual orthogonal experiments are executed on the basis of the FEM model,taking the maximum extrusion load and the profile temperature as the objectives.Metal flow behavior in billet for simple profile extrusion is studied by Deform software,and the length of the scrap due to the back-end defect is counted by different measurement approaches.Based on the study of simple profile extrusion,experiment is designed to observe metal flow in micro-multiport profile extrusion.Moreover,the effects of extrusion speed,billet temperature gradient,billet front face temperature and friction between billet and container on the length of the scrap are analyzed.Finally,the variation of mechanical properties of extruded samples in different extrusion stage is studied by uniaxial tensile test,and the damage parameters of GTN model are determined by the finite element inverse method.Micro-multiport profile pressure-bearing process is analyzed and the pressure-bearing value is predicted via FEM.In addition,the effects of profile hole number and deformation on pressure-bearing property are obtained.