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MJZSW01-029@笔盖注塑模具设计,机械毕业设计全套
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编号： 毕业设计 (论文 )外文翻译 （原文 ） 学 院： 国防生 学院 专 业： 机械设计制造及其自动化 学生姓名： 卢 卫 学 号： 1000110107 指导教师单位： 机电工程学院 姓 名： 曹泰山 职 称： 讲 师 2014 年 3 月 9 日 nts 编号： 毕业设计 (论文 )外文翻译 （译文 ） 学 院： 国防生 学院 专 业： 机械设计制造及其自动化 学生姓名： 卢 卫 学 号： 1000110107 指导教师单位： 机电工程学院 姓 名： 曹泰山 职 称： 讲 师 2014 年 3 月 9 日 nts 编号： 毕业设计 (论文 )开题报告 题 目： 笔盖 注塑模具设计 院 （系）： 国防生 学院 专 业： 机械设计制造及其自动化 学生姓名： 卢卫 学 号： 1000110107 指导教师单位： 机电工程学院 姓 名： 曹 泰 山 职 称： 讲 师 题目类型 ： 理论研究 实验研究 工程设计 工程技术研究 软件开发 2013 年 12 月 23 日 nts 1 毕业设计的主要内容、重点和难点等 毕业设计的主要内容： 近年来，中国塑料模具发展速度相当快。注塑模市场 得到了很 大的 发展 ，市场 竞争 也越发 激烈。 为了做到高质高效低成本来提高市场占有率 ,注塑模具的开发、设计与加工 结合 CAD/CAE/CAM 技术 具有重大意义 。 模具生产技术水平的高低已成为衡量一个国家产品制造水平高低的重要标志 ，其主要内容如下： 1、参观调研，查阅资料。到模具制造相关企业调研，了解模具设计、生产、制造及加工情况。结合本次毕设课题，查阅模具相关资料； 2、 撰写开题报告； 3、通过对产品的性能分析，完成相关的模具结构与零件设计； 4、设计的模具结构要求完整、合理； 5、合理选择尺寸、公差、表面粗糙度和制件材料，绘制的产 品图样完整； 6、认真分析制件图，确定模具型腔、模具结构、分型面和进料口形式，计算含收缩率的相关尺寸和模具的强度和刚度； 7、 翻译专业外语文献。 8、 撰写毕业设计（论文）说明书； 9、 绘制模具总装图、零件图； 毕业设计的重点难点： 1、塑件的合理性设计及结构工艺性分析； 2、材料选择，收缩率计算。模具强度及刚度分析； 3、塑件壁厚成型工艺考虑及保证塑件的外观要求； 4、模具型腔数的确定，模具结构、分型面和进料口形式的选择； 5、保证 塑件成型时无变形，注出的制件表面光滑，无气泡和其它缺陷，无飞边或少飞边。 6、绘制模具总 装图、零件图及尺寸标注。 2 准备情况（查阅的文献资料及调研情况、现有设备、实验条件等） 模具工业是国民经济的重要基础工业之一。模具是工业生产中的基础工艺装备，是一种高附加值的高精密集型产品，也是高新技术产业化的重要领域，其技术水平的高低已经成为衡量一个国家制造业水平的重要标志 专家预测，大型、精密、设计合理的注塑模具将受到市场普遍欢迎。 通过调研及查阅资料 ,对 侧抽芯液压锥螺纹接头三通管注塑模设计 方案有了初步的构nts 思。 调研情况 1.模具技术的现状 20 世纪 80 年代以来，国民经济的高速发展对模具工业提 出了越来越高的要求，同时为模具的发展提供了巨大的动力。这些年来，中国模具发展十分迅速，模具工业一直以 15% 左右的增长速度快速发展。振兴和发展中国的模具工业，日益受到人们的重视和关注。“模具是工业生产的基础工艺装备”已经取得了共识。目前，中国有 17000 多个模具生产厂点，从业人数约 50 多万。在模具工业的总产值中，冲压模具约占 50%，塑料模具约占 33%，压铸模具约占 6%，其他各类模具约占 11%。近年来，中国模具工业企业的所有制成分也发生了变化。除了国有专业厂家外，还有集体企业、合资企业、独资企业和私营企业，他 们都得到了迅速的发展。许多模具企业十分重视技术发展。加大了用于技术进步的投入力度，将技术进步作为企业发展的重要动力。此外，许多研究机构和大专院校也开展了模具技术的研究与开发。 中国塑料模工业从起步到现在，历经半个多世纪，有了很大发展，模具水平有了较大提高。在大型模具方面已能生产 48in（约 122cm）大屏幕彩电塑壳注射模具、 6.5kg 大容量洗衣机全套塑料模具以及汽车保险杠和整体仪表板等塑料模具，精密塑料模具方面，已能生产照相机塑料件模具、多型腔小模数齿轮模具及塑封模具。经过多年的努力，在模具 CAD/ CAE/CAM 技术、模具的电加工和数控加工技术、快速成型与快速制模技术、新型模具材料 1等方面取得了显著进步；在提高模具质量和缩短模具设计制造周期等方面作出了贡献。 进入 21 世纪，在经济全球化的新形势下，随着资本、技术和劳动力市场的重新整合，中国装备制造业在加入 WTO 以后，将成为世界装备制造业的基地。而在现代制造业中，无论哪一行业的工程装备，都越来越多地采用由模具工业提供的产品。为了适应用户对模具制造的高精度、短交货期、低成本的迫切要求，模具工业正广泛应用现代先进制造技术来加速模具工业的技术进步，这是各行各业对 模具这一基础工艺装备的迫切需求。 2.侧抽芯 笔盖注塑模具设计 的流程 ： (1)思考与创新 ：绘 制 草图，确 定 笔盖 外观 形式； (2)实践 操作 ： 通过 Pro-e 软件 画出 其 三维模型； (3)用 Pro-e 做出内部的结构，实现外观 要求； (4)将 Pro-e 做的图导入 AutoCAD 中； (5)修改结构图。 nts 3.注射模具的设计过程 (1)对塑料零件的材料、形状和功能进行分析 (2)确定型腔的数目 确定型腔的数目条件有：最大注射量、锁模力、产品的精度要求和经济性等。 (3)选择分型面 分型面的选择应以模具结构简单、分型容易，且不破 坏已成型的塑件为原则。 (4)型腔的布置方案 型腔的布置应采用平衡式排列，以保证各型腔平衡进料。型腔的布置还要注意与冷却管道、推杆布置的协调问题。 (5)确定浇注系统 浇注系统包括主流道、分流道、浇口和冷料穴。浇注系统的设计应根据模具的类型、型腔的数目及布置方式、塑件的原料及尺寸等确定。 (6)确定脱模方式 脱模方式的设计应根据塑件留在模具的部分而同。由于注射机的推出顶杆在动模部分，所以，脱模推出机构一般都设计在模具的动模部分。因此，应设计成使塑件能留在动模部分。设计中，除了 将较长的型芯安排在动模部分以外，还常设计拉料杆，强制塑件留在动模部分。但也有些塑件的结构要求塑件在分型时，留在定模部分，在定模一侧设计出推出装置。推出机构的设计也应根据塑件的不同结构设计出不同的形式，有推杆、推管和推板等结构。 (7)确定调温系统结构 模具的调温系统主要由塑料种类决定。模具的大小、塑件的物理性能、外观和尺寸精度都对模具的调温系统有影响。 (8)确定凹模和型心的固定方式 当凹模或型心采用镶块结构时，应合理地划分铁块并同时考虑镶块的强度、可加工性及安装固定。 (9)确定排气尺寸 一般注射模的排气 可以利用模具分型面和推杆与模具的间隙；而对于大型和高速成型的注射模，必须设计相应的排气装置。 (10)确定注射模的主要尺寸 根据相应的公式，计算成型零件的工作尺寸，以及决定模具型腔的侧壁厚度、动模板的厚度、拼块式型腔的型腔板的厚度及注射模的闭合高度。 (11)选用标准模架 根据设计、计算的注射模的主要尺寸，来选用注视模的标准模架，并尽量选择标准模具零件。 nts (12)绘制模具的结构草图 在以上工作的基础上，绘制注射模的完整的结构草图，绘制模具结构图是模具设计十分重要的工作，其步骤为先画俯视图（顺序为：画模架、型 腔、冷却管道、支撑柱、推出机构），再画出主视图。 (13)校核模具与注射机有关尺寸 对所使用的注射机的参数进行校核：包括最大注射量、注射压力、锁模力及模具的安装部分的尺寸、开模行程和推出机构的校核。 (14)注射模结构设计的审查 对根据上述有关注视模结构设计的各项要求设计出来的注射模，应进行注射模结构设计的初步审查，同时，也有必要对提出的要求加以确认和修改。 (15)绘制模具的装配图 装配图是模具装配的主要依据，因此应清楚地表明注视模的各个零件的装配关系、必要的尺寸（如外形尺寸、定位圈直径、安装尺寸、活动零 件的极限尺寸等）、序号、明细表、标题栏及技术要求。 (16)绘制模具的零件图 由模具装配图拆绘零件图的顺序为：先内后外，先复杂后简单，先成型零件后结构零件。 (17)复核设计图样 注射模具设计的最后是审核所设计的注射模，应多关注零件的加工、性能。 已查阅的文献资料 1 屈华昌 .塑料成型工艺与模具设计 M.北京：高等教育出版社， 2007. 2 宋长发 .工程制图 M.北京：国防工业出版社， 2011. 3 任仲贵 . CAD/CAM 原理 M. 北京 ： 清华大学出版社 ， 1991. 4 王明强 . 计 算机辅助设计技术 M. 北京 ： 科学出版社 ， 2002. 5 许鹤峰 .注射模具设计要点与图例 M.北京：化学工业出版社， 1999. 6 李名尧 .模具 CAD/CAMM.北京：机械工业出版社， 2004. 7 潘宝权 .模具制造工艺 M.北京 ;机械工业出版社， 2004. 8 张维合 .注塑模具设计实用教程 M.北京 :化学工业出版社 ,2007.9. 9 李学锋 . 塑料模设计及制造 M.北京 :机械工业出版社 ,2002.6 10 Y. Zhang, W. Hu and Y. Rong et al. Graph-based set-up planning and tolerance decomposition for computer-aided fixture design. International Journal of Production Research J, 2001, 39(14): 31093126. nts 现有设备及实验条件：计算机一台，使用软件为 Pro/Engineer5.0 及 Auto CAD2008、 Moldflow insight，以上实验条件可满足本次毕业设 计的要求。 3、 实施方案、进度实施计划及预期提交的毕业设计资料 一、 2013 年 12 月 9 日至 2013 年 12 月 22 日，理解消化毕设任务书要求并收集、分析、消化资料文献，根据毕设内容完成并交开题报告； 二、 2014 年 1 月 6 日至 2014 年 1 月 13 日，开展调研，了解塑件结构，对原材料进行分析，考虑塑件的成型工艺性、模具的总体结构的形式，并完成部分英文摘要翻译。 三、 2014 年 3 月 4 日至 2013 年 3 月 31 日，查阅资料，熟悉注射模的结构及有关计算，拟定模具的方案设计、总体设计及主要零件设计，拟定成型工艺过程，查阅 有关手册确定适宜的工艺参数，注射机的选择及确定注射设备及型号规格； 四、 2014 年 4 月 1 日至 2014 年 4 月 6 日，完成设计计算任务，总体结构的设计和完成总装配图及零件图的设计； 五、 2014 年 4 月 7 日至 2014 年 4 月 21 日，完成设计，图纸绘制任务，工艺规程说明书的编写； 六、 2014 年 4 月 22 日至 2014 年 5 月 4 日，完善设计并完成论文的撰写； 七、 2014 年 5 月 5 日至 2014 年 5 月 9 日，修改并打印毕业论文及整理相关资料，交指导老师评阅，准备论文答辩。 nts 指导教师意见 指 导教师（签字）： 2013 年 12 月 日 开题小组意见 开题小组组长（签字）： 2014 年 1 月 日 院（系、部）意见 主管院长（系、部主任）签字： 2014 年 1 月 日 nts编号： 毕业设计 (论文 )任务书 题 目： 笔盖注塑模具设计 学 院： 国防生 学院 专 业： 机械设计制造及其自动化 学生姓名： 卢 卫 学 号： 1000110107 指导教师单位： 机电 工程学院 姓 名： 曹泰山 职 称： 讲师 题目类型 ： 理论研究 实验研究 工程设计 工程技术研究 软件开发 2013 年 12 月 9 日 nts 一、毕业设计（论文）的内容 毕业设计内容 1、查找相关的资料并阅读消化，明确笔盖注塑模具设计要求，分析该塑料制品成型工艺及其可能性和经济性等因素，对零件图纸进行结构和工艺分析，设计成型工艺； 2、掌握成型设备的技术规范，进行模具结构设计及模具设计的有关计算； 3、模具总体尺寸的设计与结构草图的绘制，模具结构总装图和零件工作图的设计绘制； 4、编制主要零件的制造工艺。 二、毕业设计（论文）的要求与数据 1、笔盖形状特点确定其注塑模的方案设计； 2、该塑料制品的设计难点是抽芯机构的设计； 3、确定其使用的材料为塑料； 4、制品的具体尺寸请测绘出图； 5、塑件成型时无变形，注出的制件表面光滑，无气泡和其它缺陷，无飞边或少飞边。 三 、毕业设计（论文）应完成的工作 1、完成注塑模的总体方案设计，完成 开题报 告。 2、进行模具结构设计并选用标准件，完成零件间的配给选用及相关的设计计算。 3、用 A0 图纸绘制装配图，采用 CAD 软件绘制零件图， 绘图工作量折合 A0 图纸 3张以上，其中必须包含两张 A3 以上的计算机绘图图纸 ，用 PRO/E 软件对塑件和模具进行实体造型。 4、完成二万字左右的毕业设计说明书（论文）；在毕业设计说明书（论文）中必须包括 300-500 个 单词 详细的英文摘要； 5、独立完成与课题相关，不少于四万字符的指定英文资料翻译（附英文原文）； 6、完成导师所指定的其它工作。并附有开题报告一份。 四 、应收集的资料及主要参考文献 1 屈华昌 .塑料成型工艺与模具设计 M.北京 :机械工业出版社， 2002. 2 模具实用技术丛书编委会模具实用技术注塑模具设计制造与应用实例M北京 :机械工业出版社， 2002. 3 颜智伟 .塑料模具设计与机构设计 M.北京：国防工业出版社， 2006. 4 姜明艳 .薄壁外壳注塑模设计 J. 北京：机械工业出版社， 2002. 5 王文广等 .塑料注射模具设计技巧与实例 M.北京：化学工业出版社 .2004. 6 模具实用技术丛书编委会编 .塑料模具设 计制造与应用实例 M.北京：机械工nts业出版社 .2002. 7 李学锋 .塑料模设计及制造 M.北京：机械工业出版社 2002. 8德 G.曼格斯，李玉泉译 .塑料注射成型模具的设计和制造 M.北京轻工 出版社 ,2005. 9谭雪松 , 林晓新 , 温丽编 . 新编塑料模具设计手册 M.北京：人民邮电出版社， 2007. 10 Childs Peter R.N Mechanical DesignJ Oxford :Butterworth-Heinemann， 2003 五 、试验、测试、试制加工所需主要仪器设备及条件 计算机一台 CAD 设计软件nts任务下达时间： 2013 年 12 月 9 日 毕业设计开始与完成时间： 2013 年 12 月 17 日至 2014 年 05 月 4 日 组织实施单位： 教研室主任意见： 签字： 2013 年 12 月 14 日 院领导小组意见： 签字： 2013 年 12 月 16 日 nts第 1 页 共 2 页 2014年 机电工程学院 毕业设计 (论文 )进度计划表 学生姓名： 卢卫 学号： 1000110107 序号 起止日期 计划完成内容 实际完成内容 检查日期 检查人签名 1 2013.12.17 12.23 教师填写，下同 教师填写， 下同 2 2013.12.24 12.30 3 2013.12.31-2014.1.6 4 2014.1.7-1.13 5 3.4-3.10 6 3.11-3.17 7 3.18-3.24 8 3.25-3.31 (本表同时作为指导教师对学生的 16次考勤记录 ) nts第 2 页 共 2 页 2014年机电工程学院 毕业设计 进度计划表（续） 学生姓名： 学号： 序号 起止日期 计划完成内容 实际完成内容 检查日期 检查人签名 9 4.01-4.07 教师填写，下同 教师填写，下 同 10 4.08-4.14 11 4.15-4.21 12 4.22-4.28 13 4.29-5.05 14 5.06-5.12 15 5.13-5.19 16 5.20-5.26 完成毕业设计，提交论文 任务下达时间 ： 2013 年 12 月 17 日 (本表同时作为指导教师对学生的 16次考勤记录 ) nts毕业设计（论文）中期检查表（指导教师） 指导教师姓名：曹泰山 填表日期： 2014 年 4 月 20 日 学生学号 1000110107 学生姓名 卢卫 题目名称 笔盖 注塑模具设计 已完成内容 1、完成装配图的绘制； 2、完成大部分论文； 3、完成英文翻译； 4、大部分零件图的绘制； 检查日期： 2014-4-20 完成情况 全部完成 按进度完成 滞后进度安排 存在困难 相关部分的计算比较难进行。 解决办法 查阅相关资料，并且与指导老师和同学们一起讨论解决方案。 预期成绩 优 秀 良 好 中 等 及 格 不及格 建 议 教师签名： 教务处实践教学科制表 说明： 1、 本表由检查毕业设计的指导教师如实填写； 2、 此表要放入毕业设计（论文）档案袋中； 3、 各院 (系 )分类汇总后报教务处实践教学科备案 nts桂林电子科技大学 毕业设计（论文）说明书用纸 1 An Analysis of Draw-Wall Wrinkling in a Stamping Die Design F.-K. Chen and Y.-C. Liao Department of Mechanical Engineering, National Taiwan University, Taipei, Taiwan Wrinkling that occurs in the stamping of tapered square cups and stepped rectangular cups is investigated. A common characteristic of these two types of wrinkling is that the wrinkles are found at the draw wall that is relatively unsupported.In the stamping of a tapered square cup, the effect of process parameters, such as the die gap and blank-holder force, on the occurrence of wrinkling is examined using finiteelement simulations. The simulation results show that the larger the die gap, the more severe is the wrinkling, and such wrinkling cannot be suppressed by increasing the blank-holder force. In the analysis of wrinkling that occurred in the stamping of a stepped rectangular cup, an actual production part that has a similar type of geometry was examined. The wrinkles found at the draw wall are attributed to the unbalanced stretching of the sheet metal between the punch head and the step edge. An optimum die design for the purpose of eliminating the wrinkles is determined using finite-element analysis. The good agreement between the simulation results and those observed in the wrinkle-free production part validates the accuracy of the finite-element analysis, and demonstrates the advantage of using finite-element analysis for stamping die design. Keywords: Draw-wall wrinkle; Stamping die; Stepped rectangular cup; Tapered square cups 1. Introduction Wrinkling is one of the major defects that occur in the sheet metal forming process. For both functional and visual reasons,wrinkles are usually not acceptable in a finished part. There are three types of wrinkle which frequently occur in the sheet metal forming process: flange wrinkling, wall wrinkling, and elastic buckling of the undeformed area owing to residual elastic compressive stresses. In the forming operation of stamping a complex shape, draw-wall wrinkling means the occurrence of wrinkles in the die cavity. Since the sheet metal in the wall area is relatively unsupported by the tool, the elimination of wall wrinkles is more difficult than the suppression of flange wrinkles. It is well known that additional stretching of the material in the unsupported wall area may prevent wrinkling,and this can be achieved nts桂林电子科技大学 毕业设计（论文）说明书用纸 2 in practice by increasing the blankholder force; but the application of excessive tensile stresses leads to failure by tearing. Hence, the blank-holder force must lie within a narrow range, above that necessary to suppress wrinkles on the one hand, and below that which produces fracture on the other. This narrow range of blank-holder force is difficult to determine. For wrinkles occurring in the central area of a stamped part with a complex shape, a workable range of blank-holder force does not even exist. In order to examine the mechanics of the formation of wrinkles, Yoshida et al. 1 developed a test in which a thin plate was non-uniformly stretched along one of its diagonals.They also proposed an approximate theoretical model in which the onset of wrinkling is due to elastic buckling resulting from the compressive lateral stresses developed in the non-uniform stress field. Yu et al. 2,3 investigated the wrinkling problem both experimentally and analytically. They found that wrinkling could occur having two circumferential waves according to their theoretical analysis, whereas the experimental results indicated four to six wrinkles. Narayanasamy and Sowerby 4 examined the wrinkling of sheet metal when drawing it through a conical die using flat-bottomed and hemispherical-ended punches. They also attempted to rank the properties that appeared to suppress wrinkling. These efforts are focused on the wrinkling problems associated with the forming operations of simple shapes only, such as a circular cup. In the early 1990s, the successful application of the 3D dynamic/explicit finite-element method to the sheetmetal forming process made it possible to analyse the wrinkling problem involved in stamping complex shapes. In the present study, the 3D finite-element method was employed to analyse the effects of the process parameters on the metal flow causing wrinkles at the draw wall in the stamping of a tapered square cup, and of a stepped rectangular part. A tapered square cup, as shown in Fig. 1(a), has an inclined draw wall on each side of the cup, similar to that existing in a conical cup. During the stamping process, the sheet metal on the draw wall is relatively unsupported, and is therefore prone to wrinkling. In the present study, the effect of various process parameters on the wrinkling was investigated. In the case of a stepped rectangular part, as shown in Fig. 1(b),another type of wrinkling is observed. In order to estimate the effectiveness of the analysis, an actual production part with stepped geometry was examined in the present study. The cause of the wrinkling was determined using finite-element analysis, and an optimum die design was proposed to eliminate the wrinkles. The die nts桂林电子科技大学 毕业设计（论文）说明书用纸 3 design obtained from finite-element analysis was validated by observations on an actual production part. Sketches of (a) a tapered square cup. Sketches of(b) a stepped rectangular cup. Fig. 1. 2. Finite-Element Model The tooling geometry, including the punch, die and blankholder,were designed using the CAD program PRO/ENGINEER. Both the 3-node and 4-node shell elements were adopted to generate the mesh systems for the above tooling using the same CAD program. For the finite-element simulation,the tooling is considered to be rigid, and the corresponding meshes are used only to define the tooling geometry and are not for stress analysis. The same CAD program using 4-node shell elements was employed to construct the mesh system for the sheet blank. Figure 2 shows the mesh system for the complete set of tooling and the sheet-blank used in the stamping of a tapered square cup. Owing to the symmetric conditions, only a quarter of the square cup is analysed. In the simulation, the sheet blank is put on the blank-holder and the die is moved down to clamp the sheet blank against the blank-holder. The punch is then moved up to draw the sheet metal into the die cavity. In order to perform an accurate finite-element analysis, the actual stressstrain relationship of the sheet metal is required as part of the input data.In the present study, sheet metal with deep-drawing quality is used in the simulations.A tensile test has been conducted for the specimens cut along planes coinciding with the rolling direction (0 ) and at angles of 45 and 90 to the rolling direction.The average flow stress ,calculated from the equation =（ 0+245+90） /4, for each measured nts桂林电子科技大学 毕业设计（论文）说明书用纸 4 true strain,as shown in Fig.3, is used for the simulations for the stampings of the tapered square cup and also for the stepped rectangular cup. All the simulations performed in the present study were run on an SGI Indigo 2 workstation using the finite-element program PAMFSTAMP. To complete the set of input data required for the simulations, the punch speed is set to 10 m s_1 and a coefficient of Coulomb friction equal to 0.1 is assumed. Fig. 2. Finite-element mesh. Fig. 3. The stressstrain relationship for the sheet metal. 3. Wrinkling in a Tapered Square Cup A sketch indicating some relevant dimensions of the tapered square cup is shown in Fig. 1(a). As seen in Fig. 1(a), the length of each side of the square punch head (2Wp), the die cavity opening (2Wd), and the drawing height (H) are considered as the crucial dimensions that affect the wrinkling.Half of the difference between the dimensions of the die cavity opening and the punch head is termed the die gap (G) in the present study, i.e. G = Wd-Wp. The extent of the relatively unsupported sheet nts桂林电子科技大学 毕业设计（论文）说明书用纸 5 metal at the draw wall is presumably due to the die gap, and the wrinkles are supposed to be suppressed by increasing the blank-holder force. The effects of both the die gap and the blank-holder force in relation to the occurrence of wrinkling in the stamping of a tapered square cup are investigated in the following sections. 3.1 Effect of Die Gap In order to examine the effect of die gap on the wrinkling, the stamping of a tapered square cup with three different die gaps of 20 mm, 30 mm, and 50 mm was simulated. In each simulation, the die cavity opening is fixed at 200 mm, and the cup is drawn to the same height of 100 mm. The sheet metal used in all three simulations is a 380 mm 380 mm square sheet with thickness of 0.7 mm, the stressstrain curve for the material is shown in Fig. 3. Fig. 4. Wrinkling in a tapered square cup (G =50 mm). The simulation results show that wrinkling occurred in all three tapered square cups, and the simulated shape of the drawn cup for a die gap of 50 mm is shown in Fig. 4. It is seen in Fig. 4 that the wrinkling is distributed on the draw wall and is particularly obvious at the corner between adjacent walls. It is suggested that the wrinkling is due to the large unsupported area at the draw wall during the stamping process,also,the side length of the punch head and the die cavity openingare different owing to the die gap. The sheet metal stretched between the punch head and the die cavity shoulder becomes unstable owing to the presence of compressive transverse stresses. The unconstrained stretching of the sheet metal under compression seems to be the main cause for the wrinkling at the draw wall. In order to compare the results for the three different die gaps, the ratio of the two principal strains is introduced, nts桂林电子科技大学 毕业设计（论文）说明书用纸 6 being min/max, where max and min are the major and the minor principal strains, respectively. Hosford and Caddell 5 have shown that if the absolute value of is greater than a critical value, wrinkling is supposed to occur, and the larger the absolute value of , the greater is the possibility of wrinkling. The values along the cross-section MN at the same drawing height for the three simulated shapes with different die gaps, as marked in Fig. 4, are plotted in Fig. 5. It is noted from Fig. 5 that severe wrinkles are located close to the corner and fewer wrinkles occur in the middle of the draw wall for all three different die gaps. It is also noted that the bigger the die gap, the larger is the absolute value of . Consequently,increasing the die gap will increase the possibility of wrinkling occurring at the draw wall of the tapered square cup. 3.2 Effect of the Blank-Holder Force It is well known that increasing the blank-holder force can help to eliminate wrinkling in the stamping process. In order to study the effectiveness of increased blank-holder force, the stamping of a tapered square cup with die gap of 50 mm,which is associated with severe wrinkling as stated above, was simulated with different values of blank-holder force. The blank-holder force was increased from 100 kN to 600 kN,which yielded a blank-holder pressure of 0.33 MPa and 1.98 MPa, respectively. The remaining simulation conditions are maintained the same as those specified in the previous section.（ An intermediate blank-holder force of 300 kN was also used in the simulation.） The simulation results show that an increase in the blankholder force does not help to eliminate the wrinkling that occurs at the draw wall.The values along the cross-section compared with one another for the stamping processes with blank-holder force of 100 kN and 600 kN. The simulation results indicate that the _ values along the cross-section MN are almost identical in both cases. In order to examine the difference of the wrinkle shape for the two different blank-holder forces, five cross-sections of the draw wall at different heights from the bottom to the line MN, as marked in Fig. 4, are plotted in Fig. 6 for both cases.It is noted from Fig. 6 that the waviness of the cross-sections for both cases is similar. This indicates that the blank-holder force does not affect the occurrence of wrinkling in the stamping of a tapered square cup, because the formation of wrinkles is mainly due to the large unsupported area at the draw wall where large compressive transverse stresses exist. The blankholder force has no influence on the instability mode of the material nts桂林电子科技大学 毕业设计（论文）说明书用纸 7 between the punch head and the die cavity shoulder. Distance(mm) Fig. 5. -value along the cross-section MN for different die gaps. Fig. 6. Cross-section lines at different heights of the draw wall for different blank-holder forces. (a) 100 kN. (b) 600 kN. 4. Stepped Rectangular Cup In the stamping of a stepped rectangular cup, wrinkling occurs at the draw wall even though the die gaps are not so significant.Figure 1(b) shows a sketch of a punch shape used for stamping a stepped rectangular cup in which the draw wall C is followed by a step DE. An actual production part that has this type of geometry was examined in the present study. The material used for this production part was 0.7 mm thick, and the stressstrain relation obtained from tensile tests is shown in Fig. 3. The procedure in the press shop for the production of this stamping part consists of deep drawing followed by trimming.In the deep drawing process, no draw bead is employed on the die surface to facilitate the metal flow. However, owing to the small punch corner radius and complex geometry, a split occurred at the top edge of the punch and wrinkles were found to occur at the draw wall of the actual production part,as shown in Fig. 7. It is seen from Fig. 7 that wrinkles are distributed on the draw nts桂林电子科技大学 毕业设计（论文）说明书用纸 8 wall, but are more severe at the corner edges of the step, as marked by AD and BE in Fig. 1(b).The metal is torn apart along the whole top edge of the punch,as shown in Fig. 7, to form a split. Fig. 7. Split and wrinkles in the production part. Fig. 8. Simulated shape for the production part with split and wrinkles. In order to provide a further understanding of the deformation of the sheet-blank during the stamping process, a finiteelement analysis was conducted. The finite-element simulation was first performed for the original design. The simulated shape of the part is shown from Fig. 8. It is noted from Fig.8 that the mesh at the top edge of the part is stretched significantly, and that wrinkles are distributed at the draw wall,similar to those observed in the actual part.The small punch radius, such as the radius along the edge AB, and the radius of the punch corner A, as marked in Fig.1(b), are considered to be the major reasons for the wall breakage. However, nts桂林电子科技大学 毕业设计（论文）说明书用纸 9 according to the results of the finiteelement analysis, splitting can be avoided by increasing the above-mentioned radii. This concept was validated by the actual production part manufactured with larger corner radii. Several attempts were also made to eliminate the wrinkling.First, the blank-holder force was increased to twice the original value. However, just as for the results obtained in the previous section for the drawing of tapered square cup, the effect of blank-holder force on the elimination of wrinkling was not found to be significant. The same results are also obtained by increasing the friction or increasing the blank size. We conclude that this kind of wrinkling cannot be suppressed by increasing the stretching force. Since wrinkles are formed because of excessive metal flow in certain regions, where the sheet is subjected to large compressive stresses, a straightforward method of eliminating the wrinkles is to add drawbars in the wrinkled area to absorb the redundant material. The drawbars should be added parallel to the direction of the wrinkles so that the redundant metal can be absorbed effectively. Based on this concept, two drawbars are added to the adjacent walls, as shown in Fig. 9, to absorb the excessive material. The simulation results show that the wrinkles at the corner of the step are absorbed by the drawbars as expected, however some wrinkles still appear at the remaining wall. This indicates the need to put more drawbars at the draw wall to absorb all the excess material. This is, however,not permissible from considerations of the part design. nts桂林电子科技大学 毕业设计（论文）说明书用纸 10 Fig. 9. Drawbars added to the draw walls. One of the advantages of using finite-element analysis for the stamping process is that the deformed shape of the sheet blank can be monitored throughout the stamping process, which is not possible in the actual production process. A close look at the metal flow during the stamping process reveals that the sheet blank is first drawn into the die cavity by the punch head and the wrinkles are not formed until the sheet blank touches the step edge DE marked in Fig. 1(b). The wrinkled shape is shown in Fig. 10. This provides valuable information for a possible modification of die design. Fig. 10. Wrinkle formed when the sheet blank touches the steppededge. nts桂林电子科技大学 毕业设计（论文）说明书用纸 11 Fig. 11. Cut-off of the stepped corner. Fig. 12. Simu
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