The Inverse Design And Flow Analysis Of Polymer Profile Extrusion Die

The extrusion die is the main part of the Extrusion products; it affects the shape and the quality of the extrusion products. The designs of the traditional die used the tryout method and repair methods, which needed long period and high cost. To predict the die shapes of required extrusion products by numerical simulation and to optimize the structures of the die by analyzing the flow of melt in the extrusion die is important for the design of Profile Extrusion Die. So far, the scholars at home or abroad have done a little of research on the design of shapes of polymer profile die, they mainly use the viscosity model to design the inverse numerical of die and process the die to do the experimental analysis to verify the rational of the design of the inverse die. But in order to further improve the precise of the profile and to realize the industrialization, we should do further research on the following problems:(1) The effects of the transition die on the balance of flow.(2) The effects of the change of technological requirements on the shape of die.(3) The rational of the simulated method of inverse numerical on the design ofextrusion die.In the thesis, first, use the module of inverse extrusion of polyflow software with Bird-carreau viscosity model and PTT Viscoelastic model to design T-shape of profile extrusion die in inverse and work out the shape of exit section extrusion die. Then analyze the extrusive processes of three different transition dies, compare the area and shape of exit section and analyze the problems about the balance of flow in extrusive processes. In the extrusion simulation. Combine the Generalized Navier's slip law equation which describes the problem about unequal temperature to analyze the change of entrance flow.The research about the effects of the shape of transition die on the balance flow shows that the different transition extrusion dies have no effect on the shape of shaping die. According to the inverse numerical simulation of extrusion die to design the shape of shaping section, it can simplify the process of making die by making it straightly instead of transition section. Three different shapes of transition extrusion dies, the T-shape die with widened structure of transition. Compared with the other two kinds of T-shapes which is the right angle of T-shape die and the partial widened T-shape die, the increase of flow speed of melt is slower in the processes of melt.The flowing speeds of melt are well- distributed in every section of die. The entrance pressure is the lightest and the cost of energy is the lowest in the extrusive process, so it is more rational that compare flowing structure with straight T-shape die and the partial widened T-shape die.The research about the effects of the change of technological requirements on the die shapes is taken from three aspects, which are the state of wall slipping, the condition of extrusive in unequal temperature and different entrance flowing speed. The result shows that: The wall slipping has great effect on the state of extrusive, the wall slip bigger, and the extrusive deformed less, which proves that the wall slipping affect the design of polymer die. The smooth of die interior, the linking of die and melt surface are the important factors to affect the wall slipping. But compare simulating with experiment, the wall slips a little in reality. In the reality calculation, we can suppose that the wall doesn't slip. And taking the influence of the change of temperature on the size of die section into consideration can improve the precise of die design. The extrusive amounts of flow have an effect on the section of die design products. The amount become heavier, the product extrude bigger. In order to keep pace with the high speed and high yield development of extrusion products, it should regulate the section shape of die and reduce the area of section in die design with the increase of flowing speed die design. Having made extrusive experiment on pp versatility and thermoplastic, measured and observed the radial size and pressure of extrusion products in slipping state and slipping less state. And do experimental tests about the result of the numerical simulation in the former chapter. Based on the numerical simulation and experiment outcomes, it proves that the equations which referred in the thesis can be used to predict the radial size of extrusion products and to verify the rational to use inverse numerical simulation to design extrusion die.