Cold Forming Process Analysis Of Flange Weld Nut

There are no many symmetric research on molding process of automotive fasteners, due to the small size, wide variety and large quantity. Because of the special application environment, automotive fastener generally has higher performance and quality stability compared with normal commercial used fasteners.The cold heading forming of automotive fasteners covers metal materials science, molding process, heat treatment, surface treatment and many other technologies. Some of the technologies used in the molding process are even considered as significant academic challenges. This paper will use plastic forming theory, finite element numerical simulation and experiment to discuss some problems occurred in automotive fasteners cold heading process and systematically study on the flange faces welding nut cold forging technique.Firstly, overview introduces status of key technology research in domestic and international cold forging technique, starting from the point of view of the actual part of process improvement, lead to main content of this paper. By apply the metal cold heading molding theoretical weld nuts on the flange surface cold heading forming theoretical analysis and calculations, two solution of weld nut flange surface cold heading forming have been brought out.Secondly, the flange forming process is simulated based on DEFORM-3D. The optimum molding solution is established through comparison of two solutions in term of material flow, stress and strain distribution. Systematic study has been done especially on problems of flange round and inner hole folding in molding process, and hence determine the key factors that impacts these problems.Third, verified by experiment, feasibility of the above molding process is confirmed. Key factor that affects flange roundness is determined, the coefficient of friction between the male die and the work piece, while major factor that affects the inner bore folded is male die head dimensions. The general rules for male die dimension design have been concluded.Finally, the research was applied to the actual production process. To solve the problem of the flange roundness by adding curls on male mold surface resulted in higher coefficient of friction of male die and workpiece. To avoid a "U-turn" by material selection on the male die and assembly after individual machining of male die and male die member. To reduce the degree of the inner hole folding effectively by controlling male die size, especially chamfer angle.