| Nowadays, stamping and cold forging have already developed to a relatively high level with a number of processing methods. There have been scores of basic working procedures of stamping and cold forging as well as those procedures which derive from them, which are still developing.Along with the rapid development of cold pressure forming technology, and the expansion of the range of its application, many structural parts are processed with metal plate. In recent years, metal plates are processed with flow control forming of sheet metal (FCF), for FCF process can not only ensure the intension and precision of parts, but also reduce the product charge. As FCF process brings great efficiency and a steady product quality, also leads batch production of new parts. Thus FCF process which combines metal plate stamping with cold forging in bulk forming process has become one of the primary orientations of cold pressure forming, attracting more and more concern now. By focusing on a certain product or requirement, excogitating a new combined process and analyzing its original substance have great significance for academic theory and practical production.Aiming at sheet metal parts with stepped cross-section, based on "Processing Method and Its Mould of Blanked Parts with Stepped Cross-section of Metal Plate " which is proposed by my tutor, the research work on FCF new process and its mould as to cold pressure forming technology are done with combination of three parts, i.e., finite-element-method simulation, technologic experimental observation and theoretical analyzing calculation.Numerical simulation has become a useful tool to estimate design. And the explanation and analysis of simulative results require designer's academic experience and technologic knowledge. With utilization of metal plastic forming FEM principle and its key technology, 2D and 3D simulative models are built by using commercial FEM software DEFORM. The original substance of deformation are discovered and derived from the simulative results such as material deformation process, distribution of effective stress and strain, distribution of material velocity and Force-stroke curve, etc., which provides a foundation for experimental research and theoretical analysis.The main research work and innovations are as follows:(1) With utilization of technologic experiments, aiming at sheet metal parts with stepped-hole and those with stepped-exterior, corresponding experimentation moulds of punching stepped-hole and blanking stepped-exterior were manufactured, in which severally using stepped punch and stepped female die and assembling those parts. Simple technologic experiments for punching stepped-hole and blanking stepped-exterior were carried out using AL-1100 aluminum plate. The results of numerical simulation were validated by technologic experiments. And a preferable blank holder condition for punching stepped-hole process was proposed.(2) On the basis that the results of simple technologic experiments were in accordance with those of numerical simulation, aiming at a kind of sheet metal part which has both stepped-exterior and stepped-hole, an assorted mould for deformation process which combines stamping with cold forging was designed and manufactured. Several cold pressure forming procedures can fulfill within one stroke of press machine by using aluminium plates and copper plates, as a result, this kind of part can be produced. Moreover, based on the numerical simulative measure and experimental analysis, a quantificational reference of this kind of part with stepped-profile was proposed, namely right range of parietal distanceδ. Feasibility and validity of this new process are further analyzed.(3) Material work hardening effect was studied with theoretical analysis, and the influential factors of forming performance are analyzed, which includes step height, step-hole diameter and step- exterior diameter, etc. By contrasting with existing calculation formulas for cold pressure forming force, pointing out that material deformation should consider work hardening effects of both blanking and extrusion, a calculation formula for force of FCF process for stepped-profile was proposed and its calculation results were in accordance with both simulative result and experimental result.The research results show that, the FCF new process of stepped-profile is novel and feasible. The research method of using numerical simulation to guide technologic experiments combined with theoretical analysis can give a valuable reference for researching and exploiting new process of cold pressure forming as well as for expanding of application for metal plate forming.
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