【作者】 李湖峰；

【导师】 卢险峰；

【作者基本信息】 南昌大学 ， 材料加工工程， 2008， 博士

【摘要】 现今,冲压和冷锻加工的内容已比较丰富,加工形式已经相当繁多,基本工序及派生工序均各有几十种,且仍在不断发展。随着冷压成形工艺技术的迅速发展及其应用范围的不断扩大,许多结构零件都采用板料制备而成。近年来,比较时兴籍板类零件与体积成形的结合加工,即FCF加工法(flow cntrol forming of sheet metal),不仅能保证零件有足够的精度和强度,生产成本低,而且快速高效,制件质量稳定,促生了一些新零件的批量生产。因此,将板料冲压成形和冷锻体积成形工艺相结合的FCF加工法成为冷压加工技术的主要发展方向之一,越来越引人注目。针对某种产品或一项特定指标的需要,研发一种冷压复合新工艺,进而分析其工艺本源内容,对学术理论和生产实际都有重大的意义和价值。论文针对在料厚方向上有台阶形的薄板零件,于导师构想的“金属板料台阶断面冲裁件的制造方法及模具”的前提下,对FCF加工法新工艺、新模具乃至冷压成形技术的研究,是结合有限元数值模拟、工艺实验观察和理论分析计算这三方面来进行的。数值模拟手段已成为评价设计的重要手段,对其仿真结果的解释和说明也需要设计者的理论经验和工艺知识来进行分析和判断。基于金属塑性成形有限元基本原理和关键技术的应用,运用商用有限元分析软件DEFORM,建立了科学而有效的2D和3D模型,在模拟获得的工件材料变形过程、应力应变分布情况、速度场分布及力一行程曲线等仿真结果中,发现和挖掘工艺内涵和技术知识,为试验研究和理论分析打下了良好的基础。本文的主要研究内容和创新点为:(1)利用工艺试验手段,首先针对台阶形内孔薄板件和台阶形外缘薄板件,分别将凸模、凹模设计成台阶形状进行组配,制作了相应的台阶冲孔和台阶落料简易工艺试验模。使用AL-1100铝板,对台阶冲孔工艺和台阶落料工艺进行了简易工艺试验,验证了数值模拟研究结果,并提出了一个台阶冲孔的合理压边条件。(2)在简易工艺试验和数值模拟结果吻合的情况指导下,一种外缘台阶形且内部有台阶孔的薄板零件,设计制造了一副冲压冷锻组合模具,在压机的一次行程中,用铝、铜板材料完成多个冷压工艺基本工序单元的组合,成形出这种外缘和内孔均有台阶形状的薄板零件。并结合数值模拟测量和工艺试验分析,提出了一个此类台阶薄板零件结构设计的定量参考依据,即孔与外缘台阶壁间距δ的合理数值范围,进一步验证分析了本FCF新工艺的可行性和有效性。(3)在理论分析方面,对材料的冷作硬化效应进行了探讨,并分析了台阶高度、台阶内孔径及台阶外缘径等对工件台阶成形性能的影响。参考对比了现有的冷压成形力计算公式,指出材料的成形分析主要以冲裁和挤压为主,且有二次硬化效应,提出了台阶断面FCF加工法成形力的一种计算公式,其计算结果和数值模拟及工艺试验是十分吻合的。研究表明,台阶断面薄板件FCF新工艺是是新颖的、可行的。利用这种数值模拟指导工艺试验、结合理论分析计算的研发手段和路线,能为快速高效地研发冷压成形复合新工艺,拓展板类零件成形的应用范围,提供了很有价值的参考依据。更多还原

【Abstract】 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.更多还原