犁刀变速齿轮箱体工艺规程及夹具设计（钻孔+铣面）

喜欢就充值下载吧。。资源目录里展示的文件全都有，，请放心下载，，有疑问咨询QQ:1064457796或者1304139763 ==================== 喜欢就充值下载吧。。资源目录里展示的文件全都有，，请放心下载，，有疑问咨询QQ:1064457796或者1304139763 ==================== 机械加工工序卡片 产品型号 零件图号 第 1 张 产品名称 零件名称 犁刀变速齿轮箱体 共 1 张 车间 工序号 工序名称 材料牌号 机加工 30 粗铣Q面 HT200 毛坯种类 毛坯外形尺寸 每坯件数 每台件数 铸件 162×168× 51 1 设备名称 设备型号 设备编号 同时加工件数 立式铣床 X52K 1 夹具编号 夹具名称 切削液 专用夹具 工位器具编号 工位器具名称 工序工时 终准 单件 YG6A硬质合金端铣刀 工步号 工步内容 工艺装备 主轴转速(r/min) 切削速度(m/min) 进给量 (mm/r) 切削深度(mm) 进给 次数 基本工时 min 1 粗铣Q面，保证粗铣后的平面与72mm孔轴线之间尺寸51.5±0.09mm 刀具：YG6A硬质合金端铣刀 量具：游标卡尺 95 59.69 0.31 1.5 1 0.45 设 计（日 期） 校 对（日期） 审 核（日期） 标准化（日期） 会 签（日期） 标记 处数 更改文件号 签字 日期 标记 处数 更改文件号 签字 日期 机械与运载工程学院 毕业设计（论文）开题报告 毕业设计（论文）题目： 犁刀变速齿轮箱体工艺规程及夹具 设计 学 生 姓 名：　 指导教师姓名： 专 业 班 级： 年 月 日 1. 课题名称： 犁刀变速齿轮箱体工艺规程及夹具设计 2. 课题研究背景： 在这里，我从犁刀变速箱和夹具两方面分别介绍。 （1）犁刀变速箱： 梨刀变速箱是手扶拖拉机的一个主要部件，如图1所示，在这里主要讨论国内外拖拉机的发展状况。党的十五大提出了“在下世纪中叶，基本实现现代化”的奋斗目标。我国作为一个发展中的农业大国，实现农业现代化是当务之急，而农业机械化是农业现代化的重要内容和基本标志，拖拉机则是农业机械化的龙头产品。拖拉机的拥有量和年产销量，是评价一个国家农业机械化水平的重要标志。 图 1-犁刀变速齿轮箱体 在这里， 首先，分析一下国内技术现状及存在问题： 　　1）行业现状堪忧。我国拖拉机工业虽有较大发展，但大中型拖拉机的产品技术水平、质量、规模、企业素质和结构与发达国家相比，从整体上分析并没有明显缩短差距，要相差20年以上。特别是新产品品种发展，产品技术水平，机电液一体化，人机工程、电子操纵监控等方面差距更大。 2）产品品种少，新产品开发速度与市场需求变化太快不相适应。拖拉机作为农机产品，属微利企业，企业历来很少有资金投入用于新产品开发及生产装备的更新。大多数产品很少技术储备，生产几十年一贯制，产品水平低，趋同化趋势严重。品种缺挡多，基本型多，运输型多，其它适用对路的变型产品少。 3）产品质量、可靠性及使用寿命满足不了用户日益增长的期望值的要求。产品可靠性差，一次装配合格率低，漏油和螺钉松动等一般性故障普遍存在，突出表现在大型拖拉机上，大型拖拉机的关键零部件由于工艺水平所限，质量达不到设计要求。 4）与拖拉机配套的农机具开发、生产不同步、不协调，影响了拖拉机使用功能的发挥。 其次，谈论一下国外技术现状及发展趋势： 90年代以来，国外拖拉机工业已进入现代化发展的新阶段。产品的更新速度加快，产品系列化进一步完善，大部分产品实现了机电一体化、智能化，达到高效节能，产品外观质量轿车化。 拖拉机系列品种进一步完善，产品技术性能不断提高。国外几家著名的拖拉机制造企业的技术发展，都是以其主导的2－3个拖拉机及配套柴油机的短系列产品为基础，不断改进、扩展或派生出新的系列产品，进行系列化生产。然后开发其主导产品的变型机及其配套作业的机具，来拓宽主导产品的用途和功能。同时使其产品的覆盖面向相关的领域拓宽，以扩大产品的品种和应用范围，在更大范围内占有市场。 全面实现机电液一体化、智能化。国外大中型拖拉机均已利用微电子技术及计算机技术、激光技术、传感等高新技术对产品安全、节能、工作装置操作，工作状态、故障自诊断、不解体检测等进行控制和报警，取得了极佳的经济效益、社会效益。 制造水平进一步提高，计算机数控技术（CNC），新材料、新工艺广泛应用，大大地提高了产品质量、寿命、可靠性。 零部件的标准化、通用化程度进一步提高，最大限度地简化维修是国外先进技术发展的一个重要标志。 液压技术朝着高压、高速、大流量、大功率、静动态特性好的闭式环路发展，且向结构简单，重量轻，成本低，可靠、耐用的高水平方向发展。同时进一步与微电子技术结合，最大限度地提高功率利用率，减少无用功消耗，使拖拉机发动机始终处于最佳工作状态，减少能耗。此外，静液压传动技术开发应用在90年代又有了进一步突破。 纵观世界各国拖拉机最近技术的发展和应用，无不都是广泛采用了计算机及电子监控系统，高精度的机、电、液（气）一体化等高科技产品。不难看出，要缩小我国当前在拖拉机设计及制造方面的差距，其任务是十分艰巨的。它需要我们在相当长的一段时间内，坚持不懈的努力，坚持走技术创新的道路，从基础技术的研究到高新技术的产业化开发，以锲而不舍的精神，一步一步地去跟上当今世界最新拖拉机技术的发展。 （2）夹具： 夹具从产生到现在，大约可以分为三个阶段：第一个阶段主要表现在夹具与人的结合上，这是夹具主要是作为人的单纯的辅助工具，是加工过程加速和趋于完善；第二阶段，夹具成为人与机床之间的桥梁，夹具的机能发生变化，它主要用于工件的定位和夹紧。人们越来越认识到，夹具与操作人员改进工作及机床性能的提高有着密切的关系，所以对夹具引起了重视；第三阶段表现为夹具与机床的结合，夹具作为机床的一部分，成为机械加工中不可缺少的工艺装备。 随着机械工业的迅速发展，对产品的品种和生产率提出了愈来愈高的要求，使多品种，中小批生产作为机械生产的主流，为了适应机械生产的这种发展趋势，必然对机床夹具提出更高的要求。它主要表现在以下几个方面： 1）加强机床夹具的三化工作 为了加速新产品的投产，简化设计工作，加速工艺装备的准备工作，以获得良好的技术经济效果，必须重视机床夹具的标准化，系列化和通用化工作。 2）大力研制推广实用新型机床夹具 在单件，小批生产或新产品试制中，应推广使用组合夹具和半组合夹具。 在多品种，中小批生产中，应大力推广使用可调夹具，尤其是成组夹具。 3）提高夹具的机械化，自动化水平 近十几年来，高效，自动化夹具得到了迅速的发展。由于数控机床，组合机床及其它高效自动化机床的出现，要求夹具能适应机床的要求，才能更好的发挥机床的作用。 3. 课题研究意义： 毕业设计是教学计划的最后一个教学环节,也是最重要的教学环节之一.在教师的指导下，我们通过毕业设计受到一次综合运用所学理论和技能的训练,进一步提高分析问题和解决问题的能力;并且学会阅读参考文献,收集,运用原始资料的方法以及如何使用规范,手册,产品目录,选用标准图的技能,从而提高设计计算及绘图的能力。 本选题与本专业密切相关，能结合社会生产实际或科研实践，工程性强，现实意义明显，具有相当的先进性、深度和难度。可以说是对大学几年学习以来的一个很好的补充，也是对未来工作的一个很好的锻炼。 首先，通过本次毕业设计，使我们能够真正的巩固所学的专业知识。其次，在设计中，我们势必将会运用到许多绘图和分析软件，我们可以加强掌握运用专业软件解决实际问题的能力。再次，通过本课题的研究，培养我们综合运用所学基础理论知识、基本技能和专业知识，联系生产实际以及自我分析和解决问题的能力。 4.文献查阅概况 [1]邱彩云.加工箱体类零件的镗床夹具设计[J].山东工业技术.2013(11): 242~243. 摘要：箱体类零件是机器及其部件的基础件，它将机器及其部件中的轴、轴承、套和齿轮等零件按一定的相互位置关系装配成一个整体，并按预定传动关系细条其运动。因此，箱体的加工质量不仅影响其装配精度及运动精度，而且影响到机器的工作精度，而且影响到机器的工作精度、使用性能和寿命。箱体类零件具有结构复杂、壁薄且不均匀、加工部位多及加工难度大等特点。因此，箱体类零件加工的关键屎加工工艺规程制定和机床夹具的设计，加工工艺规程制定和机床夹具设计合理、可靠易于保证零件加工精度，缩短辅助时间，提高劳动生产率，降低生产成本；并可以减轻工人操作强度，降低对工人的技术要求，同时扩大了机床的工艺范围，实现一机多能；另外还可以减少生产准备时间，缩短新产品试制周期。 [2]陈斌，黎向新.GN31型手拖变速箱体双面45轴钻孔组合机床的设计[J].装备制造技术.2008(7):131~132. 摘要：介绍了多孔密集型箱体组合机床的设计过程，实际上证明该机床设计严谨规范，又有技术创新，使用效果良好。 [3]王秀玲,谷东伟，王志琼.变速器前壳体加工中心专用夹具设计[J].机床与液压.2015,43(2):5~7. 摘要： 为实现变速箱前壳体一次装夹同时进行钻、 铣、 镗加工的要求， 设计了一套加工中心用变速箱前壳体快速装夹的液压自动专用夹具。 针对变速箱前壳体的结构采用 “一面两销” 定位方式， 设计了自定心机构， 并详细阐述了机构原理， 保证定位精准可靠。 夹具采用液压夹紧， 计算了切削力和夹紧力， 选取了夹具油缸并设计了相应的液压系统。 实践证明： 该夹紧结构简单， 操作方便， 避免了基准的转换， 保证了加工精度， 提高了加工效率。 [4]郭安斌.变速箱两侧面钻孔组合机床夹具设计[J].科技向导，2012（33）：344~346. 摘要：组合机床地夹具设计具有生产效率高、加工精度稳定、制造和维护成本低、配置灵活等特点。由于切削力不是很大，采用手动夹紧装置，降低成本。本次夹具设计运用了Pro/E软件进行了实体的设计，使零件直观，设计简便，与实际更为贴近。 [5]黄艳，胡义华，农胜隆，钟礼君，林祖正.变速箱体双工位钻镗专用夹具设计[J].组合机床与自动化加工技术.2017（11）:150~152. 摘要:针对变速箱体被加工孔系多,同轴度要求高,跨距大,在传统工艺上加工过程中需要多次装夹 和更换刀具,在卧式镗铣加工中心上加工成本高的情况,设计了一种可以在立式加工中心上对变速 箱体进行快速加工的双工位旋转专用夹具。 阐述了该夹具的结构特点及工作原理,通过对变速箱体的加工工艺分析,采用完全定位的方案,并对定位误差进行分析和控制,采用液压夹紧和翻转,并计 算切削力和夹紧力,设计了相应的液压系统。 该夹具可以使工件在立式加工中心上实现一次装夹完成上下两面的加工,满足了企业生产要求,提高了生产效率和经济效益。 [6]于晓文，吴敬.方形端面零件深孔加工车床夹具设计[J].机床与液压，2014,42(20):20. 摘要：针对方形端面零件特点，设计工装夹具，解决了零件装夹问题中的中心架支撑问题，有家具精度保证零件加工精度。 [7]梁伟文,复杂零件斜面斜孔加工的夹具设计[J].中国制造业信息化，2012，41（23）：105~108. 摘要：针对复杂零件的斜面斜孔加工，以四轴卧式加工中心加工的壳体零件为对象，分析了该零件的工艺要求和家居设计要求，设计和制作了一款专用夹具，同时分析和计算了该夹具的定位误差，最后利用该夹具进行了加工分析，证明了该方法简单实用，达到了零件设计所要求的加工精度，降低了加工成本，具有较强的实用性。 [8]刘旭，朱学超，李洪伟.基于典型壳体零件加工工艺规程及钻孔专用夹具设计[J].煤矿机械，2012，33（08）：125~126. 摘要：介绍了典型壳体零件的作用、应用场合，分析了零件的技术要求，为了保证加工质量，提高加工效率，进行了壳体零件的机械加工工艺规程和专用机床夹具的设计，设计的夹具操作方便、加持稳，减轻了劳动强度，具有很好的经济效益。 [9]钟春明.减速箱箱体加工工艺及夹具设计[J].科技向导，2014（12）：140。 摘要：在零件加工产业中心，有关机械减速结构与夹具优化达标状况，将直接影响后续工作流程的交接力度。在相对科学的工艺编制流程之下，设计材质消耗数量与生产均衡条件将得到顺利延展，机床夹具在机械制造工序中具有不可代替的重要疏通地位，其将人工劳动强度有力规避，同时保证产品制备质量。因此，本文具体联合减速箱体加工工艺进行夹具结构匹配，保证高精度的制孔条件，并充分考虑内部结构公差的影响状况。 [10]黄晓东.壳体零件加工车削工艺分析及夹具设计[J].科教导刊，2017（22）. 摘要：为保障壳体零件加工效果，提高加工效率，文章针对某壳体模具零件特点，进行了壳体零件车床夹具工艺的分析和专用机床夹具的设计，达到了零件加工质量以及生产安全要求。 [11]何理瑞.快速加工中心孔的专用夹具设计[J].机床与液压，2014，42（8）. 摘要:简述了专用夹具的作用，设计了在机床上快速加工中心孔的专用夹具。通过夹紧力的验算，该夹具完全可以实现对工件的加紧。介绍了此夹具的结构及使用方法，分析了其加工优势。此夹具结构简单、适用范围广、加紧可靠，可降低劳动强度、提高生产率，具有较强的人性化效果和降低生产成本的 目的。 [12]姜树祥.汽车变速箱壳体的工艺装备设计[J].民誉科技，2016（5）. 摘要：针对汽车变速箱体的零件进行工艺规程设计，为保证平面的加工精度要比保证孔系的加工精度容易，因此遵循先面后孔的原则，并将孔与平面的加工明确划分成粗加工和精加工阶段以保证孔系加工精度。 [13]Abhishek Das, Pasquale Franciosa and Darek Ceglarek.Fixture Design Optimisation Considering Production Batch of Compliant Non-Ideal Sheet Metal Parts.Procedia Manufacturing, 2015,Volume 1: 157~168. Abstract:Fixtures control the position and orientation of parts in an assembly process and thus significantly contribute to process capability that determines production yield and product quality. As a result, a number of approaches were developed to optimise a single- and multi-fixture assembly system with rigid (3-2-1 fixture layout) to deformable parts (N-2-1 fixture layout). These approaches aim at fixture layout optimisation of single ideal parts (as define by CAD model). However, as production yield and product quality are determined based on a production volume of real (non-ideal) parts. Thus, major challenges involving the design of a fixture layout for assembly of sheet metal parts can be enumerated into three categories: (1) non-ideal part consideration to emulate real part; (2) ‘N-2-1’ locating scheme due to compliant nature of sheet metal parts; and, (3) batch of non-ideal parts to consider the production process error at design stage. This paper presents a new approach to improve the probability of joining feasibility index by determining an N-2-1 fixture layout optimised for a production batch of non-ideal sheet metal parts. The proposed methodology is based on: (i) generation of composite parts to model shape variation within given production batch; (ii) selection of composite assembly representing production batch; (iii) parameterisation of fixture locators; and (iv) calculation of analytical surrogate model linking composite assembly model and fixture locators to probability of joining feasibility index. The analytical surrogate model is, then, utilised to maximise the probability of joining feasibility index starting from initial fixture locator layout. An industrial case study involving assembly process of remote laser welded door assembly illustrates and validates the proposed methodology. [14]Chetankumar M. Patel*, Dr.G.D.Acharya.Design and manufacturing of 8 cylinder hydraulic fixture for boring yoke on VMC - 1050.Procedia Technology 2014,Volume 14 : 405 ~ 412 . Abstract:Jigs and fixtures are the special production tools which make the standard machine tool, more versatile to work as specialized machine tools. They are normally used in large scale production by semi-skilled operators; however they are also used in small scale production by when interchangeability is important. Various areas related to design of fixture are already been very well described by various renowned authors, but there is a need to couple and apply all these research works to an industrial application. This paper on “Design and manufacturing of 8 cylinder hydraulic fixture for boring YOKE on VMC – 1050” which integrates all these aspects and the evolutionary functional approach of designed fixture is proved from the fact that a real industrial component is considered for fixture designing. In addition of the fixture being hydraulic type, it is also collet type and has expanding customized collet as its main fixturing element. The fixture shows great time saving in the production. [15]models for capacity optimization in Industry 4.0: Tra.Development of hydraulic clamping tools for the machining of complex shape mechanical components Procedia Manufacturing ,2018,17: 563~570. Abstract:All markets revolve around quality and, regarding a big portion of the industry, factors such as productivity and profitability are crucial to the growth and sustainability of companies’. Processes need to be well thought to ensure process repeatability and stability, particularly in machining through chipping. In order to allow this, it is necessary to perfectly define the process, machining sequence and to create physical and organizational tools that are less prone to error. Machine setup can encompass several machining errors which, sometimes, are difficult to detect using traditional control tools such as dimensional inspection. There are some cases in which the final product is faulty and it is difficult to trace the real root-causes. To avoid those errors, it is important to create easily tuneable tools which require minimal instruction to use and to creat mechanisms which allow for flaw detection during production and not only during final inspection.This work will bring a chance to improve the machining processes of complex shaped mechanical components that present strong failure risks during the machine setup,through the development of a clamping tool,giving way to easer setup operations. 5.设计（论文）的主要内容 （1）分析零件的工艺性； （2）根据生产纲领决定生产类型； （3）选择毛坯的种类和制造方法； （4）拟订工艺过程； （5）工序设计及计算； （6）编制工艺文件； （7）设计钻、铣夹具。 毕业设计（论文）要求： （1） 生产纲领：中批生产； （2）犁刀变速齿轮箱体零件图； （3） 设计犁刀变速齿轮箱体加工工艺规程； （4） 设计犁刀变速齿轮箱体钻孔夹具； （5）设计犁刀变速齿轮箱体铣面夹具。 （6）在设计方案等环节应考虑和体现社会、健康、安全、环境、法律、文化等因素的影响。 6.设计（论文）提交形式 （1）犁刀变速齿轮箱体的工艺过程综合卡片； （2）机加工工序卡； （3）钻、铣夹具装配图； （4）钻、铣夹具零件图； （5）犁刀变速齿轮箱体零件图和毛坯图； （6）设计说明书一份。 7.进度安排 第四周～第六周：查阅相关资料,写开题报告，进行文献综述。做与题目相关英文资料的中文翻译； 第七周：对零件进行工艺分析，画零件图； 第八周～第九周：选择加工方案，确定毛坯的制造形式，制订工艺路线，选择定位基准，选择机床及工、夹、量、刀具，确定加工余量、工序间尺寸及与公差，确定毛坯尺寸，画毛坯图； 第十周：确定各工序的切削用量及基本工时； 第十一周～第十二周：工艺装备设计，计算夹紧力，进行定位误差分析，画总装图； 第十三周：画夹具零件图； 第十四周～第十五周：编写设计说明书； 第十六周：准备所有答辩资料，准备答辩； 第十七周：进行毕业答辩。 8. 指导教师意见 签名： 年 月 日 ----大学毕业设计（论文）任务书 毕业设计（论文）题目： 犁刀变速齿轮箱体工艺规程及夹具设计 毕业设计（论文）要求及原始数据（资料）： 1. 生产纲领：中批生产； 2. 犁刀变速齿轮箱体零件图； 3. 设计犁刀变速齿轮箱体加工工艺规程； 4. 设计犁刀变速齿轮箱体钻孔夹具； 5. 设计犁刀变速齿轮箱体铣面夹具。 6. 在设计方案等环节应考虑和体现社会、健康、安全、环境、法律、文化等因素的影响。 进度安排： 第四周～第六周：查阅相关资料,写开题报告，进行文献综述。做与题目相关英文资料的中文翻译； 第七周：对零件进行工艺分析，画零件图； 第八周～第九周：选择加工方案，确定毛坯的制造形式，制订工艺路线，选择定位基准，选择机床及工、夹、量、刃具，确定加工余量、工序间尺寸及与公差，确定毛坯尺寸，画毛坯图； 第十周：确定各工序的切削用量及基本工时； 第十一周～第十二周：工艺装备设计，计算夹紧力，进行定位误差分析，画总装图； 第十三周：画夹具零件图； 第十四周～第十五周：编写设计说明书； 第十六周：准备所有答辩资料，准备答辩； 第十七周：进行毕业答辩。 毕业设计（论文）主要内容： 1.分析零件的工艺性； 2.根据生产纲领决定生产类型； 3.选择毛坯的种类和制造方法； 4.拟订工艺过程； 5.工序设计及计算； 6.编制工艺文件； 7.设计钻、铣夹具。 学生应交出的设计文件（论文）： 1. 犁刀变速齿轮箱体的工艺过程综合卡片； 2. 机加工工序卡； 3. 钻、铣夹具装配图； 4. 钻、铣夹具零件图； 5. 犁刀变速齿轮箱体零件图和毛坯图； 6.设计说明书一份。 主要参考文献（资料）： [1] 李洪.机械加工工艺手册[M]. 北京:北京出版社，1900. [2] 李益民. 机械制造工艺设计简明手册 [M]. 北京：机械工业出版社，1994. [3] 孙本续，熊万武. 机械加工余量手册[M]. 北京：国防工业出版社，1999. [4] 艾兴，肖诗纲. 切削用量简明手册 [M].3版. 北京：机械工业出版社，1994. [5] 吕明. 机械制造技术基础 [M].2版. 武汉：武汉理工大学出版社，2010. [6] 廖念钊等. 互换性与技术测量[M].6版. 北京：中国质检出版社，2012 [7] 李大磊，王栋. 机械制造工艺学课程设计指导书[M].2版 北京：机械工业出版社，2014 [8] 马麟等.画法几何与机械制图[M]. 北京：高等教育出版社，2011 [9] 东北重型机械学院等编.机床夹具设计手册[M]. 上海:上海科技技术出版社，1990 [10] 孟少农. 机械加工工艺手册[M] 第一卷.北京:机械工业出版社，1991 [11] P.L.Jacobs.Stereolithograghy and Other RP&M Techologies.ASME Press[M],1996 专业班级 学生 要求设计（论文）工作起止日期 指导教师签字 日期 教研室主任审查签字 日期 系主任批准签字 日期 2351-9789 2015 The Authors.Published by Elsevier B.V.This is an open access article under the CC BY-NC-ND license(http:/creativecommons.org/licenses/by-nc-nd/4.0/).Peer-review under responsibility of the NAMRI Scientific Committeedoi:10.1016/j.promfg.2015.09.079 Fixture Design Optimisation Considering Production Batch of Compliant Non-Ideal Sheet Metal Parts Abhishek Das,Pasquale Franciosa and Darek Ceglarek WMG,The University of Warwick,Coventry,U.K.abhishek.daswarwick.ac.uk,pasquale.fraciosawarwick.ac.uk,d.j.ceglarekwarwick.ac.uk Abstract Fixtures control the position and orientation of parts in an assembly process and thus significantly contribute to process capability that determines production yield and product quality.As a result,a number of approaches were developed to optimise a single-and multi-fixture assembly system with rigid(3-2-1 fixture layout)to deformable parts(N-2-1 fixture layout).These approaches aim at fixture layout optimisation of single ideal parts(as define by CAD model).However,as production yield and product quality are determined based on a production volume of real(non-ideal)parts.Thus,major challenges involving the design of a fixture layout for assembly of sheet metal parts can be enumerated into three categories:(1)non-ideal part consideration to emulate real part;(2)N-2-1 locating scheme due to compliant nature of sheet metal parts;and,(3)batch of non-ideal parts to consider the production process error at design stage.This paper presents a new approach to improve the probability of joining feasibility index by determining an N-2-1 fixture layout optimised for a production batch of non-ideal sheet metal parts.The proposed methodology is based on:(i)generation of composite parts to model shape variation within given production batch;(ii)selection of composite assembly representing production batch;(iii)parameterisation of fixture locators;and(iv)calculation of analytical surrogate model linking composite assembly model and fixture locators to probability of joining feasibility index.The analytical surrogate model is,then,utilised to maximise the probability of joining feasibility index starting from initial fixture locator layout.An industrial case study involving assembly process of remote laser welded door assembly illustrates and validates the proposed methodology.Keywords:Shape error modelling,Batch of sheet metal parts,N-2-1 fixture design optimisation,Surrogate model 1 Introduction Assembly fixture plays a significant role to achieve desired dimensional and joining qualities(Key Product Characteristics-KPCs)of assembled product where fixture design parameters act as Key Control Characteristics(KCCs).Fixtures are being used to provide accurate locating scheme to the Procedia ManufacturingVolume 1,2015,Pages 15716843rd Proceedings of the North American Manufacturing ResearchInstitution of SME http:/www.sme.org/namrc parts or subassemblies being assembled as well as to avoid shape variation in the assembly.It has been demonstrated that fixtures have large impact on product dimensional and geometric/shape variation and,subsequently,on product yield(Phoomboplab and Ceglarek,2008;Das et al.,2014).This is especially true for assembly processes of sheet metal parts produced by plastic deformation processes which lead to significant shape variations(also called non-ideal part)due to mainly spring-back,forming process parameters variations,tooling errors.Additionally,due to the compliance of sheet metals,parts can get deformed and cause variation in assembly processes(Li et al.,2001).For example,excessive variations in automotive enclosure panels may cause fundamental problems such as unnecessary closing effort,improper fit causing vibration and noise,air leakage as well as poor aesthetic appearance due to misalignment(Ceglarek et al.,2004;Camelio et al.,2004a;Huang et al.,2014).Subsequently,the shape variation management is a key issue in current industrial manufacturing and assembly process as it has direct impact on the product quality,cost and time-to-market.To be competitive in the market,proper shape and part management through robust fixture design is inevitable prerequisite to minimize the defects caused by variation during manufacturing and product usage.The locating principle 3-2-1 is widely used in industries to locate rigid body parts quite uniquely without creating locator interferences(Lowell,1982;Shirinzadeh,2002).Variety of research literature exists in field of fixture design considering 3-2-1 part locating scheme which are mainly focused on designing and optimising fixtures for machining operations(Youcef-Toumi et al.,1988;Menassa and DeVries,1991).Further,Rearick et al.(1993)introduced deformable sheet metal parts and they proposed a technique combining the nonlinear programming and FEM for determining the best fixture locations.Beyond the first requirement of part placement and constraining the rigid body motion,the fixture should also be able to limit any part deformation.Unfortunately,compliant sheet metal parts cannot be controlled through 3-2-1 scheme which require increased number of locators to N-2-1 to minimise geometric deviation(N3).For compliant part fixturing,Cai et al.(1996)proposed N-2-1 locating principle which allows to prevent excessive deformation of sheet metal parts by defining N locators on the primary datum.Camelio et al.(2004a)presented a new fixture design methodology for sheet metal assembly processes focusing on the impact of fixture position on the dimensional quality of sheet metal parts after assembly by considering the effect of part variation,tooling variation and assembly spring-back.A number of research focuses on joining process considering resistance spot welding and single part errors(Cai,2008;Li et al.,2008a;Li et al.,2010;Liu and Hu,1997).In case of laser welding,fixture plays a vital role by providing the degree of metal fit-up required to join the mating parts together.Li et al.(2001)proposed a prediction and correction methodology integrated with FEM for fixture design for laser welding where the objective function is to minimise the degree of Metal Fit-up(DMF),which is the maximum distance between mating nodes in weld joints.Few attempts have been made over the years to optimise fixture design considering the metal fit-up problem of compliant sheet metal assembly and the parts shape variation(Li et al.,2001).Undoubtedly,a batch of sheet metal parts produced through metal forming process may be affected by within batch or batch-to-batch variation which leads to quality loss of the final assembly.For example,some assembly joining processes,such as Remote Laser Welding(RLW),part variation strongly affects the final product performance which is imputed to part-to-part gap(Ceglarek,2011).Therefore,a systematic fixture design approach is demanded to mitigate the part-to-part variation as coming from the real manufacturing process.Existing methods(Li et al.,2007;Li et al.,2003;Cai,2006;Cai et al.,2005)for fixture design optimisation are based on single ideal/non-ideal compliant assembly models which are not sufficient to mitigate the error components associated with batch of assemblies.Robust fixture design is to make the output results insensitive to shape variation considering batch of parts to improve the product and process performance.The objective of this paper is to develop a novel robust methodology for fixture design optimisation by addressing a batch of non-ideal compliant assemblies.The proposed methodology is based on the concept of composite part(Das et al.,2015)which mainly quantifies the main shape error patterns/modes into composite parts coming from a Fixture Design OptimisationDas,Franciosa and Ceglarek158 batch of parts.Composite part can be defined as the part composed of all the major significant shape error components present in the population.In reality,the composite part may not exist but it reduces the efforts required for assembly process simulation as it composed of all the major shape error components.The composite parts and initial fixture locator strategies are taken as input for fixture modelling.The methodology involves selection of composite assemblies and optimisation to obtain the robust layout of the fixturing elements(i.e.,location of clamps).Therefore,it allows to optimise not only single assembly but batch of assemblies which presumably represents the production population and identifies robust fixture design parameters through optimisation to maximize the probability of joining feasibility index.A significant gap in the literature has been identified to optimise fixture design of non-ideal compliant parts.Table 1 reviews the state of art of the existing methods for fixture design optimisation.The paper has been arranged with the following sections:Section 3 describes the methodology which includes the overview of the shape error quantification for batch of parts,composite assembly selection strategy and optimisation formulation.Section 4 demonstrates the applicability through industrial cases with remote laser welding.Further,section 5 summarises the conclusions.Fixturing Scheme 3-2-1 fixture N-2-1 fixture Single part error based assembly Rearick et al.(1993);Ceglarek(1998);Li et al.(2008b)Cai et al.(1996);Cai(2008);Camelio et al.(2004a);Li et al.(2001);Li et al.(2008a);Li et al.(2010);Yu et al.(2008);Franciosa et al.(2011)Batch of parts error based assembly-Proposed in this paper Table 1:Review of fixture design methods with current research gap 2 Fixture Optimisation Methodology Overview The proposed methodology is composed of three stages.Firstly,part shape variation is determined using part measurement data for batch of parts through quantifying the shape errors into few composite parts;and initial process configuration,i.e.,joint locations,initial fixture locations(clamps,support blocks,locators etc.)are as initial process input.Thereafter,the finite element modelling for fixture simulation has been performed considering composite parts,fixture elements and contact pairs using Variation Response Method(VRM)software which is a Matlab based finite element modelling software toolkit with capabilities of fast modelling specific features required by assembly process(Franciosa et al.,2015).VRM is a new comprehensive methodology for dimensional management of assembly processes with compliant non-ideal parts which allows to analytically model the product-to-process interaction.At this stage,fewer composite assemblies have been Figure 1:Overview of fixture design optimisation methodology.Initial Process Information(CAD specs,Locator Strategy)Part Measurement(Batch of Parts)2.1 Batch of Parts Modelling Statistical Geometric Modal Analysis(SGMA)Composite PartsOptimum Layout2.2 Composite Assembly Selection Composite Assemblies with Map Index(MI)Eq.(3)Correlation Criteria Based Clustering Eq.(5)Entropy Based Assembly Selection Eq.(8)2.3 Optimisation Strategy Formulation Analytical Surrogate model development Maximise Joining Feasibility Index Eq.(10)VRM Modelling EnvironmentFixture Design OptimisationDas,Franciosa and Ceglarek159 selected which quantifies the batch errors.Finally,the nonlinear optimisation has been carried out on the defined KPCs to obtain the optimised fixture layout by varying the KCCs(clamp locations).Optimiser updates the variables that are KCCs of the process to maximise the joining feasibility index.Figure 1 illustrates the fixture design optimisation methodology considering batch of parts and initial process information under the VRM modelling environment.2.1 Batch of Parts Modelling Overview To characterise and quantify the part shape variation associated with a batch of parts,Das et al.(2015)developed Statistical Geometric Modal Analysis(SGMA)methodology which identifies the main shape error patterns present in the individual parts and merge them together using different criteria to create composite parts.The main objective of SGMA method is statistical characterisation of a batch of parts which are representative of production population.The individual part error modes are parameterised by means of its amplitude.The shape error modes are statistically characterised using non-parametric Kernel Density Estimator(KDE)which provide more accurate depiction of the shape variation.Data dimensional reduction approach,such as,Principal Component Analysis(PCA)has been utilized to extract deformation patterns from production data(Camelio et al.,2004b).However,PCA based decomposition is not suitable for shape error characterisation as it is incapable for detection of process shift in primary data set or presence of different shape errors in the data(Matuszyk et al.,2010).Unfortunately,real process of part stamping clearly exhibit different grouping of shape errors in within-run production and process shift in batch-to-batch production.Therefore,the measured part errors need to be decomposed independently to provide more accurate estimation of underlying shape errors.The SGMA method eliminates the challenges and model batch of parts error more accurately.The proposed SGMA methodology involves significant modes identification from a batch of parts,statistical characterisation of extracted modal signatures.The quantification of shape variation engraved with a batch of parts has been achieved through synthesising composite parts which are composed of major error components from the batch.Relying on the energy compaction criteria,a number of composite parts can be created where the composite parts contain the major shape errors present in the batch of parts.The overview of the SGMA method for composite part creation has been shown in Figure 2.Further,depending upon the type of shape error modes present in the batch of parts,using K-means clustering process,the parts are grouped in few clusters exhibit similar type of errors.Thereafter,energy compaction criteria have been applied to obtain the composite parts for each cluster.Therefore,using maximum,minimum and average energy compaction criteria,three composite parts created for each cluster.These composite parts behave differently in assembly system due to the part-to-part interaction.The proposed SGMA method has been applied to model and quantify part shape variation of a batch of sheet metal parts produced by stamping process and these composite parts are used for fixture design optimisation.Figure 2:Overview of the SGMA method(i)batch of parts measurement,(ii)SGMA method and statistical characterisation,and(iii)synthesis of composite part using SGMA.Original Deviation(Batch of Parts)SGMA Method&Statistical CharacterisationComposite Parts420-2-4Dev mm0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0-2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2-4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4420-2-4Dev mm-4420-2-4Dev mm1.41.00.60.2x 10-2-100 -50 0 50 100 1501.20.80.4x 10-30 1000 2000 30001.00.80.60.40.2x 10-3-2000 -1000 0 500Dev mm3210-1-2-3Main Error PatternsStatistical Distribution of Error Patterns(i)(ii)(iii)Fixture Design OptimisationDas,Franciosa and Ceglarek160 2.2 Composite Assembly Selection Relying on the creation of composite parts and number of parts present in an assembly,several different composite assemblies can be created by considering the exhaustive combination of all composite parts.For example,in an assembly operation M number of parts(?)are to be joined which is consist of?number of KPCs?,where?represents the part id and?represents the ith KPC in the assembly.The assembly consists of L number of KCCs.Therefore,depending upon the types of shape error present in a batch,parts may be grouped into?number of clusters.For each cluster,a total three composite parts can be created depending on maximum,minimum and average energy compaction criteria,i.e.,?.Therefore,the assembly system can be written as?,max,min,max,min,:,1,2,:,1,2,:,1,2,:,:istmlmmm avgMAXmgMINmgKPCsKPCiNPartsPTmMKCCsKCClLCompositePartsCPTCPTCPTMaximumCompositeParts CPTCPTMinimumCompositeParts CPTCPTAverageCompositeParts?,1,2,;1,2,AVGm avg gmCPTCPTwheremM gN?(1)Therefore,depending upon the number of clusters modelled for all the parts present in the assembly,the combination of composite assemblies also increases.The number of obtained composite assemblies can be formulated as?:MAXMINAVGCompositeAssembly CACPTCPTCPT?(2)As the each fixture simulation is time expensive,optimisation based on all composite assembly combination becomes computationally inefficient.Therefore,it emphasises on selection of few composite assemblies which are representative of all other assemblies.In order to reduce the assembly number for optimisation,two different criteria have been proposed:(i)Correlation Criteria Based Clustering and(ii)Entropy Based Assembly Selection.2.2.1.Correlation Criteria Based Clustering All combinations of composite parts are determined as per equation(2)to create complete set of composite assemblies.In order to achieve reduced number of composite assemblies for optimisation,a correlation threshold based clustering criteria introduced.It involves clustering of composite assemblies based on similar KPC Map Index(MI).MI depends on the type of KPCs selected such as point deviation,part-to-part gap distribution,surface area deformation etc.Considering the initial locator strategy(KCCs),such as given clamp layout and NC blocks,an initial fixture simulation provide part-to-part KPC map index for all the composite assemblies,?.A map index of a given iih KPC(?)of jth composite assembly can define as a function,(,)i ji jMIf CAKCC?(3)where the function f denotes the fixture simulation process composed of part-to-part interaction,boundary constraints,contact pair detection and part/assembly flexibility.Equation(3)represents the fixture simulation process with map index as an outcome.Subsequently,considering all the defined KPCs in the assembly,a total MI for the jth assembly can be evaluated as,Fixture Design OptimisationDas,Franciosa and Ceglarek161 ,1stNji jiTMIMI?(4)Similar error contained assemblies are expected to exhibit similar MI as all other parameters are kept constant.The correlation coefficient(?)between two assemblies(j and k)can be estimated as,?,22cov,jkj kjkTMITMI?(5)where,?and?,?represent the standard deviations of the total map index of?and?assembly respectively.Therefore,the correlation matrix has been determined for all composite assemblies and a user defined correlation threshold,?,has been applied to group the assemblies having the similar KPC map index.The composite assemblies can be clustered into fewer groups consist of similar type of map index distribution.This implies that one assembly from the specific cluster can be chosen for the optimisation and the obtained result should be optimum for all the assemblies belong to that cluster.2.2.2.Entropy Based Assembly Selection To select one representative assembly from each cluster for optimisation,entropy based selection criteria has been introduced.The analysis of the MIs content can be performed by borrowing tools that have been developed in the field of information theory.In particular,it is proposed to determine the Information(I)contained on MI,calculated for the?MI of?assembly(?)as(Suh,2005),2,logi ji jIp?(6)where?represents the probability of satisfying the joining requirements of?.This can be estimated as the ratio between the numbers of points in a MI satisfying the joining requirements over the total number of points of the MI.The closer?is to zero,the more likely that the parts can be joined in that particular surface.The entropy(?)for a complete assembly having?number of KPCs can be calculated,following Shannons definition involving the quantification of information by measuring the uncertainty in a MI,as(Cover and Thomas,2006),1stNji ji jiHpI?(7)The