Study On Extrusion Deformation Laws And Technics For The Covering Element

At present, cold extrusion shaping process is among the best process of the net shaping in material forming processes. The process is high accuracy, stable quantity and very suitable for production in bulk. With the development of the automobile, especially the car, it is required that higher performance, lower cost, the less consumes. The adopting cold extrusion shaping process makes net shape the important and complicated car parts are the development trend of the automobile manufacturing industry nowadays. Another advantage of cold extrusion shaping process lies in prodects themselves, especially surface and a subsurface not only can raise the hardness and strengths of the materials, but also can raise fatigue life of the parts.Numerical simulation of the workpiece's cold extrusion process by FEM can get metal flow rule, effective stress and strain distribution in workpiece and load-stroke curve during extrusion deformation. Using numerical simulation method also can reduce the die's trial-and-error cycle, decrease the cost and get the optimized die design.To optimize the process parameters and get a better extrusion process of covering element's cold extrusion process, orthogonal experiment design and numerical simulation method are used in this text. In the orthogonal experiment design, height of outer ring's chamfer, height of inner ring's chamfer and chamfer angle are choosed as influence factors, and score of inner and outer ring's height form and load are evaluation criterion. By FEM simulation, the influence of the each factor to extrusion forming is gotten. Based on above results, the optimized three parameters are determined. It gives the basic knowledge about how to improve the quality of covering element's cold extrusion forming. Finally, a die of the covering element is designed and physics experiments are performed. The experimental results show the metal flow and inner ring and outer ring's fill course are consistent with numerical simulation. Compared the load-stroke curves of numerical simulation with that of experiment, the curve's changing trend are basically same, it verifies the reliability of the numerical simulation result. Based on the above research of the numerical simulation and experiments, some advices about cold extrusion process's design of covering element are presented.