Abstract: For the design of complex plastic profile extrusion die with uneven wall thickness, the flow balance at the die exit is a necessary condition, but not sufficient. Due to the anisotropic behavior of extrudate swell, the extrudate still has a certain degree of deformation. Therefore, a mathematical model is established to evaluate the anisotropic behavior based on the geometric accuracy of products,and objective functions and constraints of geometric accuracy optimization design are established. Aiming at the flow balance at the die exit and the geometric accuracy of the extrudate, a high-precision optimization design method of the extrusion die is proposed. Taking the benchmark model as an example, an optimal solution of geometric accuracy of extrusion die channel is obtained. Compared with the benchmark case, the dimension accuracy coefficient of the optimal solution is reduced by 98.2%. The results show that high precision extrusion die design method fully combines high efficiency of the flow balance method and high precision of the geometric precision method. Based on the flow balance at die exit, the geometric precision of the extrusion product is significantly improved.

Key words: extrusion die, die swell, anisotropic behavior, optimization design, response surface method