Numerical Simulation Of Combined Extruding And Punching Process For A Thick-Plate With Tubular Bulge And Parameters Optimization

Thick-plate parts with tubular bulge are used widely in automobile, machinery and other manufacturing areas. Based on the discussion and analysis of forming process schemes for thick-plate parts with tubular bulge, the backward and forward extrusion and punch process is first proposed to form the thick-plate parts with tubular bulge by one-step process. In this dissertation, the plastic analysis software DEFORM3D is used to simulate the backward and forward extrusion and punch process for the thick-plate with tubular bulge, optimize the process parameters, and establish the preliminary prediction model of bulge height for thick-plate parts with tubular bulge. Six chapters are included in this dissertation, and the main contents of every chapter are as follows:In chapter 1, the background, theoretical and practical significance of this study is introduced first. Then, the state of the art in the study of three-dimensional parts is summarized. Finally, the main contents of this dissertation are described.In chapter 2, Application, characteristic and principle of extrusion process are analyzed. Then, the numerical simulation theory of rigid plastic finite element method is selected to do this work in this paper.In chapter 3, the selection principle of forming process schemes is introduced. Based on discussion of forming process schemes for thick-plate parts with tubular bulge, the backward and forward extrusion and punch process is first proposed to form thick-plate parts with tubular bulge.In chapter 4, the backward and forward extrusion and punch process to form thick-plate parts with tubular bulge is analyzed by the plastic analysis software DEFORM3D, and the effective stress field, effective strain field, effective strain rate field, velocity field and load-stroke curve of the deforming material during the simulation are discussed. The results show it is fine for the quality of thick-plate parts with tubular bulge by the backward and forward extrusion and punch process. Without taking into account the value of load, the thickness of extrusion wad can get below 0.1-0.2mm. But, in the actual production, punching is going on when the thickness of extrusion wad is over 0.5mm.In chapter 5, the extrusion ratio for the solid part and thick-plate parts with tubular bulge is discussed and the best value of extrusion ratio is between 1 and 5. Then, the extruding speed, the friction coefficient are optimized by the two-way experimental design. The results indicate that the extruding speed has an obvious effect on backward extrusion depth while the friction coefficient has not. Furthermore, it is by the one-way optimum seeking method that the best value of extruding speed is 10mm/s.In chapter 6, the conventional experimental modelings of material processing are introduced first. Then, The mathematical equation between the tubular bulge height and process parameters is established by the linear orthogonal regression experimental design. The results point the main factors affecting the bulge height are the thickness of sheet metal and diameter of punch-die within a certain range. However, the inner diameter of tubular bulge and the forward extrusion depth have a little contribute to bulge height.