【作者】 吴昶；

【导师】 余际星；

【作者基本信息】 武汉理工大学 ， 材料加工工程， 2008， 硕士

【摘要】 板料冲压成形是一种重要的塑性加工方法,是现代工业的基本制造手段之一,随着对冲压件质量的要求越来越高,对冲压生产工艺优化控制的要求也随之提高。随着计算机软硬件技术,有限元技术及计算机图形学等学科的快速发展,基于数值模拟的计算机辅助工程技术(CAE)在板料成形领域得到了广泛应用。本文在有限元理论的基础上,应用动力显示算法,讨论金属板料弹塑性本构模型,在Dynaform软件的帮助下,讨论压边力对弯曲和翻边工艺的影响规律。压边力是影响金属成形的重要工艺参数,对金属板料拉深,弯曲,翻边等成形质量,特别是形状和尺寸精度的保证影响巨大,是各国学者研究的重点。作为冲压成形中控制成形质量的主要手段,实现压边力的优化控制,对充分利用板料成形性能,提高成形极限具有重要意义。本文在推导变压边力数学模型基础上,对“双变”理论进行了探讨,并基于Dynaform对变压边力控制进行了数值模拟,得出了优化的变压边力控制曲线。回弹控制是本文讨论的第二个内容。翻边回弹与压边力控制有较密切的关系。本文系统分析了回弹产生的原因及控制措施。针对易产生回弹的典型大变形纵梁件,借助于有板材成形限元模拟软件Dynaform,提出了不同的控制回弹的设计方案,并在采用变压边力模拟的基础上,通过一组正交试验,优化了变压边力曲线。试验结果表明变压边力冲压工艺比恒压边力冲压工艺有较广的适用范围,能更好地控制回弹和板料成形。本文力图以理论指导实践,故在第一、二章较详细的阐述了板材成形力学原理及数学分析、有限元法及数值模拟等基本理论。在此基础上,用二、三章的篇幅分析了材料冲压成形回弹控制中压边力的作用,并通过试验模拟,优化了有效控制回弹的变压边力曲线。本文的研究方法和研究结果对冲压成形中压边力的调整具有一定的指导意义和借鉴作用。更多还原

【Abstract】 Sheet stamping is the most important plastic working method, and it’s applied to modern industry widely more and more. With the increasingly drastic market competition in modern industry, it requires not only high production efficiency, but also optimized control on the production process. So the continuous improvement of sheet stamping technique and process has been the research hotspot of sheet forming all along. With the swift and violent development of computer hardware and software, finite element method and computer graphics, the computer aided engineering(CAE)technology based on numerical simulation is widely used in sheet forming field.This paper introduced the finite element theory of sheet stamping. Discussed the process of computer simulation about the forming of sheet metal in detail; And introduced some CAE simulation analysis software which wide used in industry and research, then explain the software Dynaform which devised by ETA and LSTC about its function and simulate steps.Blank holder force(BHF)is one of the most important process variables controlling the sheet forming process for a given tool design. Researches have been carried out all over the world because of its crucial status. As a main control parameter to control the quality during sheet stamping, more reasonable BHF controlling is very important for fully using the deforming ability and raising the forming limit. In this paper, we deduce a new mathematics model of mutative BHE, and bring forward the "double-change" theory. then numerically simulate the control of Variable Blank-Holder Force(VBHF) with DYNAFORM software. obtain the optimum control curve of BHE at last.Springback is an essential thing in auto stamping parts, however, it should be controlled exactly for requirements of assemble and use. This thesis systemically analyzed the reason for how springback produced and the ways how to control it. The CAE simulation analysis software Dynaform was used to simulate the process of a typical sheet metal forming. The numerical simulation result indicates that the appropriate Variable Blank-Holder Force (VBHF) can improve the thickness and springback of sheet metal forming.In the paper, we explored the surface parts forming in detail. Including forming mechanism, mechanics model analysis, finite element numerical simulation, Variable Blank-Holder Force(VBHF) controlling, and bring out new formula and theory. The research approach and the result in this paper has some academic value and significance to study Variable Blank-Holder Force(VBHF) for sheet metal forming.更多还原