Research On The 3d Thermal-mechanical Coupled Analysis And The Optimal Design Of The Aluminum Hot Extrusion Die

With the characteristics of light weight, high strength, corrosionresistance, and beautiful shape, aluminum profiles are used in many fields,such as building industry, common industry, communication industry,aeronautic and space industry and so on. As one of the most importantforming equipments, hot extrusion dies not only affect the quality ofprofiles, but also affect the extrusion process. The service life of hotextrusion dies is one of the factors that affect practice costs. China is agreat nation that produces and consumes a great amount of extrusionprofiles. But the service life of extrusion dies in the country is lower thanthat in developed countries. So it's very beneficial to research the methodsthat can improve the service life of hot extrusion dies.Amount of practice and theoretical studies showed that the structure ofhot extrusion dies, the temperature and stress distribution of die bodieswhen working, load condition and so on, all of them are contributed to thefailure of the dies. Therefore, analyzing the dies with the method ofthermal mechanical coupled is helpful to find the disadvantages of thedesigned dies before manufacturing them. Then, the optimized parametersof the dies can be obtained with the method optimal design. The traditionaldesign method of engineering comparison and the working procedure of"Die testing"and"Die repairing"can be replaced. The qualities of the diesand the productivity can be improved, and the raw materials and the costscan be saved.A typical hot extrusion die, i.e. the polygon aluminum profile hotextrusion die was taken as a subject in this thesis. The following researcheswere applied to it:1. After the structure of the hot extrusion die was fully analyzed, the3D parametric geometric model of the die was built with the FEM softwareof ANSYS and its APDL, which was the groundwork for thethermal mechanical coupled analysis of the die.2. Based on the Elasticity and Plasticity Theory and the Heat TransferTheory, the elastic and plastic structure equation, the mathematical modelof the temperature field, the thermal stress field, and the thermal mechanical coupled stress field were established.3. Grounded on the theory of FEM, the temperature field, the thermalstress field, and the thermal mechanical coupled stress field werenumerically simulated and analyzed. The reason that caused the die bridgescracked was found. It's because of uneven stress distribution and severelocal stress concentration.4. The main parameters of the die were chosen to analyze therelationships between the maximum von Mises stress and them. Theseparameters were also selected as the optimal design parameters. Afteroptimal computing, the optimized parameters were obtained. Themaximum von Mises stress of the optimized die decreased by 33.5%.5. At last, based on the same theories and methods, another typical hotextrusion die was analyzed with the methods of thermal mechanicalcoupled and optimal design. The computed and analyzed results werecoincident with the real failure type of the die that cracks taken place at theposition of the links between the die bridges and the die core. The validityof the theories and methods used was approved. Then, these methods andtheories can be spread.