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目 录目 录1前 言2第一章 定模座板工作零件结构工艺性分析5第一节 熟悉和分析定模座板制定工艺规程的主要依据5第二节 定模座板零件的结构工艺性分析7第二章 设备与工艺装备的选择10第一节 设备的确定10第二节 机床的选用13第三章 确定毛坯的类型及其制造加工方法14第四章 拟定定模座板工艺路线16第五章 确定定模座板工序的加工余量20第一节 确定定模座板加工余量的方法20第二节 确定主要工序的技术要求及检验方法21第三节 检验22第六章 确定定模座板工序的切削用量和时间定额22第七章 定模座板加工的技术文件23第八章 参考文献25前 言本工艺规程主要将学生学到的理论与实际相结合，突出模具设计基础的结合运用，以提供更准确，实用，方便的计算方法，正确掌握并运用塑模工艺参数和模具工作部分的几何形状和尺寸的综合应用，提高自我的模具设计与制造能力的综合应用。在以后的生产生活中，研究和推广新工艺，新技术提高模具在生产生活中的应用，并进一步提高模具技术水平。塑料制件之所以能够在工业生产中得到广泛应用，是由于它们本身具有的一系列特殊优点所决定的。塑料谜底小，质量轻。这就是“以塑代钢”的明显优点所在。塑料的比强度高，绝缘性能好，介电损耗低，所以塑料是现代电工行业和电器行业中不可缺少的原材料。塑料的化学稳定性最高，减磨耐磨性能好。此外，塑料的减振和隔音性能也很好。许多塑料还具有透光性能和绝热性能以及防水，防透气和防辐射等特殊性能。因此，塑料已成为各行各业中不可缺少的一种重要材料。需求量的日益增加，这些产品的更新换代的周期愈来愈短。因此对塑料的品种，产量和质量都提出了越来越高的要求。因此，本工艺规程课程设计说明书具有以下的优点：一、本工艺规程课程设计说明书本课程设计计算说明书结合了塑料模具图册的若干图列，并突出性和实用性的对每一幅模具进行详细的对比分析与学习，然后再结合相应的实践知识进行的设计计算。二、本工艺规程设计说明书本课程设计计算说明书主要阐述了塑料注射模具注射成形的整个设计计算过程，以及每一个组成部的设计计算，同时较为严密合理的进行相应的校核与验证。三、本工艺规程课程设计说明书本课程设计计算说明书同时也结合了模具设计与制造专业所学的所有知识，比如塑料模具设计与制造、机械制图，公差与测量技术、模具工艺与工装等专业课的知识。所有的这知识储备均体现了本课程设计计算说明书依据与合理性。随着现代工业的发展需要塑料制品在工业、农业、以及日常生活等各个领域应用越来越广，质量要求也越来越高。在塑料制品的生产中高质量的模具设计、先进的模具制造设备、合理的加工工艺、优质的模具材料和现代化成形设备等都已成为成形优质塑件的重前提条件。因此，本工艺规程课程设计说明书本课程设计计算说明说书具有以下的不足之处：一、由于初步接触塑料模具设计与制造知识以及共进入机械行业，因此对塑料模成型以及成型工艺了得比较浮浅，设计时困难比较大，设计也够准确。为此本课程设计计算说明说书也有待进一步改进。二、社会实践经验缺乏，在设计时有这方面原因从而忽略了很多因素，为此设计计算中也有许多不严密之处。本课程设计主要将学生学到的理论与实际醒结合，突出模具设计基础的结合运用，以提供更准确，实用，方便的计算方法，正确掌握并运用冲压工艺参数和模具工作部分的几何形状和尺寸的综合应用，提高自我的模具设计与制造能力的综合应用。在以后的生产生活中，研究和推广新工艺，新技术提高模具在生产生活中的应用，并进一步提高模具技术水平。实践证明，理论联系实际的学习才是最有效的学习方法。因此本设计计算说明书结合了塑料模具图册、塑料模具设计与制造、机械制图，公差与测量技术、机械设计基础等专业课知识，再结合实际生产经验而设计的。从而充分体现了所学的专业知识实际生产的应用。第一章 定模座板工作零件结构工艺性分析第一节 熟悉和分析定模座板制定工艺规程的主要依据一 、熟悉和分析定模座板制定工艺规程的主要依据，确定零件的生产纲领和生产类型，进行零件的结构工艺性分析。1、定模座板制订工艺规程的主要依据（既原始资料）。1产品的装配图样和零件图样（见图附页）2产品的生产纲领3产品的生产纲领现有的生产条件和资料，它包括毛坯的生产条件或协作关系，工艺装备及专用设备的制造能力，有关机械加工车间的设备和工艺装备的条件，技术工人的水平以及各 种工艺资料和标准等。 4外国内产品的有关工艺资料等。2原始资料1）零件图样如设计任务书所示的零件图及尺寸。（见下图） 零件图2）生产纲领生产纲领是企业在计划期内应当生产的产品质量和进度计划，计划期常定为一年，所以生产纲领也称年产量。该零件是组成滑轮注塑摸的一个结构零件，一副模具只需要一个此零件即可，所以初步拟订其生产纲领为100件。3）生产类型生产类型是企业（或车间，工段，班组，工作地）生产专业化程度的分类，一般分为大量生产，成批生产和单件生产三种类型。根据生产纲领和产品及零件的特征或工作地每月担负的工序数，查文献1表13生产类型和生产纲领的关系，确定该零件的生产类型为单件小批量生产。4）生产组织形式 生产类型不同，零件和产品的生产组织形式，采用的技术措施和达到的技术经济效果也会不同，因为该零件是单件小批量生产，所以其生产组织形式查文献1表1-5的各种生产类型的二、定模座板的工艺特征有其生产组织形式1零件的互换性：有修配法，钳工修配，缺乏互换性。毛坯的制造方法与加工余量，木模手工造型或自由锻造毛坯精度低，加工余量大。2机床设备及其布置形式：通用机床，按机类别采用机群式布置。3工艺装备：大多采用通用夹具，标准附件，通用刀具和万能量具，标准附件，通用刀具和万能量具，靠划线和试切法达到精度要求。4对工人的技术要求：需技术水平较高的工人。5工艺文件：有工艺路线卡和关链工序工序卡。6成本：较高。结合上述分析对现有条件作出合理的调整使得该零件的加工更能体现“质优价廉”。第二节 定模座板零件的结构工艺性分析一、定模座板零件的结构工艺性分析熟悉定模座板零件图，了解零件的性能，用途，工作条件及其所在模具中的作用。1）定模座板零件的性能：具有较高的强度，硬度和韧性，适用于小型复杂的塑料模具。2）定模座板零件的用途：固定模具零件，并与它发生直接联系用的零件，在模具打开时带动成型零部件向下移动，确保塑件与成型机构的分离，保证模具的顺利打开和合模。3） 定模座板工作条件：安装在滑轮注塑模的定模座板上，与其他零部件结合使用，适合滑轮注塑模的工作条件。4）定模座板零件在模具中的作用：该零件在模具中与导滑板，凹模划块和弯销等配合成滑轮的注塑成型机构，起固定和定位作用。二、了解定模座板零件的材料及其力学性能1定模座板材料该零件材料为45钢，它是碳素结构钢，具有较高的强度和硬度，耐磨性好且热处理变形小，制品一般用于淬，适用于制品批量生产的热塑性塑料的成型模具零件。1材料的力学性能查文献3表7-5优质碳素钢牌号，成分及性能（GB69988）可知45钢的力学性能为：b/MPas/MPas100100Ak/J600 355 1640 39推荐的热处理温度正火：830淬火： 840回火： 600硬度： 未处理：229HBS 退火钢：197HBS 分析：45钢在退火，正火及调质状态下的力学性能为：状态b /MPa5100AK/JHBS 退火65070015203248180 正火70080015204064163220 调质75085020256496210250 正火后钢的强度，硬度，硬度，韧性都比退火后的高，且塑件也好，操作方便，生产周期短，能量耗费少，则在条件允许下，应优先考虑，采用正火处理，可作为零件的预先热处理。调质处理后钢的强度较高，而且塑件与韧性更显著高于正火状态，其硬度较低，便于切削加工，并能获得较低的表面粗造度值，故也可作为表面淬火和化学热处理前改善钢件原始组织状态的预先热处理。三、分析选择该定模座板的热处理为调质。1定模座板结构形状分析该零件从形体上分析其总体结构为六面体，上表面有2-15的型芯孔，并且侧面有4-M30螺钉孔，2-21导柱孔扩孔为30。因此其结构形状较为简单，属于加工成形。故其结构形状工艺性合理。2定模座板尺寸该零件的外形尺寸为180mm300mm25mm，且一部分孔的加工可在与其配合的零件加工时保证，因而该零件的加工尺寸较小，减化了加工工序，降低了加工难度，可保证加工质量。 故其尺寸工艺性较为合理。3定模座板精度为了满足塑件尺寸精度和表面粗造度的要求，根据塑件精度等级（精度等级为IT4IT5级）确定模具制造精度为IT6IT7级。4定模座板热处理为了消除毛坯在加工后的缺陷，改善其工艺性能，且为后续工序作出组织准备和提高工件的使用性能及使用寿命采用调质方式进行热处理。 综合上述分析可知该零件的加工较容易，可采用先进的，高效率的工艺方法进行加工制造，但使其加工成本较高，为了降低其加工成本，可适当调整加工设备采用一般工艺方法进行加工第二章 设备与工艺装备的选择第一节 设备的确定一、设备确定因为该零件采用组织集中工序，所以选择通用设备，即：C41250型空气锤，加热炉，铣床，刨床，磨床，钻床，铰床，坐标磨床等。二、工艺装备的选择1夹具的选择单件小批量生产首先采用各种通用夹具，也可采用组合夹具，结合实际生产条件可知该零件选择四爪卡盘，虎钳，画线平台，平行夹头，火钳和组合夹具等。2刀具的选择一般优先采用标准刀具根据该零件的工艺性及实际条件确定其刀具为：剪板机，平面刨刀，圆柱铣刀；端面铣刀，平行砂轮，划针，样冲，立铣刀，钻头，丝锥，扩刀，砂轮等。3 量具的选择依据量具的精度必须与加工精度相适应，则该零件应优先采用通用量具，即：钢尺、游标卡尺、直角尺、内卡钳、百分表。三、拟订工艺路线综合上述分析最终拟订两条工艺路线如下：工艺路线一：工序号工序名称0备料5锻造10退火15铣（刨）平面20磨平面25钳工划线30铣工35热处理30钳工精修45磨削50检 验55入 库 工艺路线二： 工序号 工序名称0备料5锻造10退火15铣（刨）平面20磨平面加工精基准面25钳工划线30铣工35热处理40钳工精修45磨削50检验四、工艺路线方案的比较与分析以上两种工艺路线方案想比较，第二种方案有以下几个优点：1. 工序内容简单，工序连接紧密，有利于组织流水生产。第一种方案中工序之间相互脱节，造成加工困难，另一面，这样增加时间，生产率降低，不够经济。2. 定位基准的选择定位基准的选择将直接影响加工精度的高低，同样作为定位基准的部位加工质量的好坏也影响的定位的准确性和加工质量，使安装误差和定位误差增大，从而对加工精度有很大影响，零件上的各个表面间的位置精度，是通过一系列工序加工后获得的，这些工序的顺序和原始尺寸的大小，标注方式和零件图上的要求直接有关，第一种方案中，工序45不找正直接加工，易使工件偏斜，位置精度不准确，给下面的工序的位置精度，定位基准带来一定困难。第二方案中工序之间的采用互为基准原则的，其作用是加工时的余量均匀，并使加工后的表面位置度较高，能顺利加工。第二节 机床的选用一、机床的选用机床的选用，主要考虑零件加工的经济性，应该充分运用现有设备，不增加零件的成本。第一套方案中，较多的使用了专用机床，第二套方案中可使用普通机床。降低了加工成本，但是精度不能满足。另外在机床的选择上，也必须考虑以下因素： 机床的工作精度和工序的加工精度相适应 机床的工作尺寸应和工件的轮廓尺寸或夹具的尺寸相适应 机床的功率与刚度的性质相适应，另外，机床的加工用量范围应和工件要求的合理切削用量相适应 刀具的选择刀具的耐用度问题也的批量生产中的重要问题，刀具耐用度的提高，不仅可以节约辅助工作时间，又可降低刀具的费用。合理选择刀具的提高刀具耐用度的关键。第二套方案中，工序30钻，扩20孔深190.2采用两把车刀，分别采用合适的几何角度和材料来完成粗，精加工，这样大大减少了刀具的磨损。二、工艺路线方案确定经过多方面的分析，第二套工艺路线方案从安排工序依据的原则，定位基准的选择，加工经济性和刀具的耐用度等方面均比第一套合理，因此用第二套工艺路线作为加工方案。第三章 确定毛坯的类型及其制造加工方法一、定模座板毛坯的形状和特征毛坯的形状和特征，在很大程度上决定着模具制造过程中工序的多少，机械加工的难易程度，材料的大小及模具的质量与寿命。毛坯类型有铸，锻，压制，冲压，焊接，型材和板材等。二、定模座板毛坯的形状和特征分析锻造后，工件的力学性能比铸件好，使零件材料内部组织细密，碳化物分布和流线分布合理，从而提高模具的质量和使用寿命，铸造能够生产形状复杂的毛坯，适应性广，能节省金属材料和机械加工的工作量且成本较低，但铸造生产存在着工序复杂，铸件的力学性能低于锻件，劳动条件较差；冲压的生产效率高，易于实现机械与自动化生产，制品的尺寸精确，互换性好，节约金属，操作方便，但是模具制造复杂成本较高，适用于大量生产，焊接可节省材料与工时，减轻结构的质量，焊接接头的致密性好，可以制造密封容器，以及双金属结构件，生产效率高，便于机械化，自动化生产，但由于焊接的过程是局部加热与冷却的过程，容易产生焊接应力，变形及焊接缺陷，有些金属的焊接要求比较复杂的工艺措施才能保证焊接质量。经分析并结合该零件工艺分析可确定其毛坯为锻件（即锻坯）。毛坯图第四章 拟定定模座板工艺路线一确定工艺路线原则1.制定工艺路线的依据应使零件的各尺寸精度，位置精度，表面粗糙度和各向技术要求能得到保证，在一定生产条件下以最快的速度，最少的工作量和最低的成本，安全可靠的加工出符合零件的工作拟定工艺路线一般应遵循工艺过程划分加工阶段的原则。当加工质量要求不高，工件的刚性足够，毛坯质量高，加工余量小时可以不划分加工阶段。在数控机床上加工零件以及某些运输，装夹困难的重型零件，也不划分加工阶段，而在一次装夹下完成全部表面的粗，精加工，对重型零件可在粗加工之后将夹具松开以消除加紧变形，然后再用较小的夹紧力重新夹紧，进行精加工，以利于保证重型零件的加工质量，对于精度要求高的重型零件，仍需划分加工阶段，并适时进行时效处理消除内应力。该零件的表面质量要求较高，且需多次装夹，所以其工艺路线需划分加工阶段完成。2制定定模座板工艺规程时应注意的问题1)技术的先进性2)经济上的合理性3)使用上的安全性由于该零件生产纲领确定了成批生产，因此采用工序集中原则使，用普通3定模座板加工顺序由以下原则确定机床配以专用夹具，可降低生产成本，以获得好的经济效益加工顺序由以下原则确定：先粗加工，后精加工，先加工基准面，后加工其他面，先加工主要面，后加工次要面，后加工孔，并且应遵基准重合原则，基准统一原则，自为基准原则，互为基准原则。1)拟定工艺路线一般应遵循工艺过程划分加工阶段的原则 当加工质量要求不高，工件的刚性足够，毛坯质量高，加工余量小时可以不划分加工阶段。在数控机床上加工零件以及某些运输，装夹困难的重型零件，也不划分加工阶段，而在一次装夹下完成全部表面的粗，精加工，对重型零件可在粗加工之后将夹具松开以消除加紧变形，然后再用较小的夹紧力重新夹紧，进行精加工，以利于保证重型零件的加工质量，对于精度要求高的重型零件，仍需划分加工阶段，并适时进行时效处理消除内应力。该零件的表面质量要求较高，且需多次装夹，所以其工艺路线需划分加工阶段完成。2) 定模座板面加工方法的选择当模具零件的表面加工精度要求较高时，可根据不同工艺方法所能达到的加工经济精度和表面粗糙度等因素。首先确定被加工表面的最终加工方法，然后再选定最终加工方法，然后再选定最终加工方法之前的一系列准备工序的加工方法和顺序，以便通过逐次加工达到设计要求。二、定模座板平面加工方法确定各表面的加工方法选择加工方法时常常根据经验或查表法来确定，在根据实际情况或通过工艺是试验进行修改。依据各表面加工要求和各加工 要求和各个加工方法能达到的经济精度查文献1表111孔的加工方法和表1-12平面加工方法确定各表面的加工方法如下要求和各个加工方法能达到的经济精度查文献1表111孔的加工方法和表1-12平面加工方法确定各表面的加工方法如下：通过零件分析可分为以下几部分。：2个21和2个30的阶梯孔。铣半精铣精铣；：4个M30的螺纹孔，铣半精铣精铣；：2个9和2个15的阶梯孔。铣半精铣精铣；三、零件的外轮廓表面零件的外轮廓表面： 粗铣半精铣磨削。1定模座板工艺阶段的划分工艺路线按工序性质一般分为粗加工阶段，半精加工阶段和精加工阶段。对于那些加工精度和表面质量要求特别高的表面在工艺过程中还应安排光整加工阶段。具体的工艺阶段划分祥见该零件的工艺规程卡片中各工序的介绍。2定模座板工序的划分根据所选定的表面加工方法和各加工阶段中表面的加工要求，可以将同一阶段中各表面的加工组合成不同的工序，在划分工序时可以采用工序集中或分散的原则。由于模具加工精度要求高，且多属于单件或小批量生产，为了简化生产组织工作，则多采用组织集中划分工序3加工顺序的安排四、定模座板加工工序的安排1定模座板切削加工的安排模具零件的被加工表面切削加工应遵循 先粗后精； 先基准后其他 先主要后次要 先平面后内孔内外交叉，具体祥见加工工艺规程路线表卡片。2定模座板热处理工序的安排热处理工序在工艺路线中的安排，主要取决于零件热处理的目的为了改善金属组织和便于加工则必须使该零件在粗加工前安排调质热处理。为了提高零件硬度和耐磨性，则必须在该零件光整的工序前安排淬火热处理。3定模座板辅助工序的安排为了保证该零件质量和及时去除废品，防止工时浪费，并使责任分明，则必须在该零件重要工序加工前后和零件加工结束安排检验工序。 综合上述分析：该零件机械加工的顺序是：加工精基准面粗加工主要面精加工主要面光整加工主要面。第五章 确定定模座板工序的加工余量第一节 确定定模座板加工余量的方法一、常用加工余量的方法确定加工余量的方法有三种：查表法、分析计算法、经验估计法。1查表法是根据个工厂的生产实践和试验研究积累的数据，先制成各种表格，再汇集成手册确定加工余量是查阅这些手册，再结合工厂的实际情况进行适当修改后确定。经验估计法是根据实际经验确定加工余量。一般情况下，为防止因余量过小而产生废品，经验估计的数值总是偏大。因此其法常用于单件小批量生产。2分析计算法是根据确定加工余量的相关公式和一定的试验资料，对影响加工余量的各项因素进行分析，并计算确定加工余量。这种方法比较合理，但必须有比较全面和可靠的试验资料。因此当前只在材料十分贵重以及军工生产或少数大量生产的工厂中采用。3模具加工中常用经验估计法确定加工余量。则该零件的加工余量确定，由查表法和经验估计法结合确定。其相关加工余量查文献6表827有平面第一次粗加工余量为：1.5mm2.5mm; 表828有平面粗刨后精铣加工余量为：0.7mm0.9 mm; 表829有铣平面的加工余量为；1.2mm;表830有磨平面的加工余量为0.3mm;表831有铣及磨平面的厚度公差为：粗铣（IT12IT13），0.21mm0.33mm；半精铣0.13mm（IT11），精磨（IT8IT9），0.033 mm0.062mm；表833有凹模的加工余量及公差为：宽度余量粗铣后半精铣4.0mm；半精铣后磨1.0mm；宽度公差粗铣（IT12IT13）+0.35mm+0.54mm , 半精铣（IT11）+0.22mm；表834研磨平面的加工余量为：0.024mm 0.030mm;表835磨孔和铰孔的加工余量为：磨孔时，粗：0.2mm,精0.1mm, 热处理（粗）0.5mm ,热处理（半精）0.4 mm；铰孔时0.15mm. 二、确定定模座板加工余量综上分析本模具采用经验估计法确定加工余量。第二节 确定主要工序的技术要求及检验方法1零件图中未注公差尺寸的极限偏差按GBT18042000公差与配合 未注公差尺寸的极限偏差。 2零件图中未注形为公差按GBT11841996形状和位置公差 未注公差的规定，其中直线度、平面度、同轴度的公差等级均按C级。3板类零件的棱边均须倒钝。4零件图中螺纹的基本尺寸按GB1961981普通螺纹基本尺寸（直径1600mm）的规定，其偏差按GB1971981普通螺纹公差与配合（直径1355mm）的3级。5零件图中砂轮越程槽的尺寸按JBT31959砂轮越程槽的规定。6零件材料允许代用，但代用材料的机械性能不得低于规定材料的要求。7零件表面经目测不允许有锈斑裂纹，夹杂物、凹坑氧化斑点和影响使用的划痕等缺陷。8零件的材料和热处理硬度按GBT6991999模具设计指导 模具成型零件材料及硬度的规定选取。9模具零件的几何形状、尺寸精度、表面粗糙度等应符合图样要求。10如对零件有其他技术要求，可依据实际条件协调决定。第三节 检验一、 检验方法：1利用卡钳和钢尺配合使用测量零件孔的具体数据，保证零件表面质量。2利用游标卡尺直接测量工件的内表面、外表面和深度，确保其个表面精度。3利用分厘卡尺测量孔外径、内径、深度、螺纹孔的尺寸精度。4利用百分表检验工件的形状误差、位置误差和安装工件与刀具时的精密找正，其测量精度为0.01 mm。第六章 确定定模座板工序的切削用量和时间定额 因为该零件为单件小批量生产，所以在工艺文件上一般不规定切削用量，而由工作者根据实际情况自行决定。一、时间定额时间定额是在一定的生产条件下，规定生产一件产品或完成一道工序所需消耗的时间合理的时间定额能调动生产者的积极性，促进生产者技术水平的提高。制定时间定额应注意调查研究，有效利用生产设备和工具，以提高生产效率和产品质量。二、时间定额计算 时间定额计算公式为： T c=Ta+Tb+Ts+Tr+Ten在大量生产中，由于n的数值很大，即Ten=0,可忽略不计。式中： Tc：该零件的时间定额。 T b ：基本时间 。 Ta : 辅助时间。 Ts: 布置工作地时间。 Tr： 休息与生理需要时间。 Te: 准备与终结时间。N： 生产批量（个）。具体数值可查阅相关资料代入上式计算即可确定出确切时间定额时间。第七章 定模座板加工的技术文件一、进行技术经济分析，选择最佳方案。 因为该零件属单件小批量生产，所以对其可不进行技术分析。依据现有条件及工人工作经验做适当调整即可。 二、填写工艺文件。 因为该零件属单件小批量生产，所以一般只填写机械加工工艺过程卡片。根据设计任务要求该零件还需填写机械加工工序卡片。 机械加工工艺过程卡片以工序为单位简要说明产品活 或零件、部件加工（装配）过程，它以工序为单位列出了零件加工的工艺路线，（包括毛坯，机械加工和热处理等）。机械加工工序卡片具有工艺简图，和该工序的每个工步的加工（或装配）内容，工艺参数，操作要求以及所用设备和工艺装备等具体见该零件的工艺文件。三、定模座板加工工艺规程见下工艺卡片第八章 参考文献 郑修本主编，机械制造工艺学，北京.机械工业出版社.1999-5.2. 张龙勋主编，机械制造工艺学课程设计指导书及习题.北京.机械工业出版社.199911。3. 王运炎. 叶尚川主编，机械工程材料.北京.机械工业出版社.2000-5.2版.4. 王孝达主编，金属工艺学.北京.高等教育出版社.1997.5. 侯维芝.样金风主编.北京高等教育出版社.20057.6. 张耀良主编，机械加工工艺设计手册.北京.航空工业出版社出版.198712第2版.7. 李永增主编，金工实习.北京.高等教育出版社.1995.8. 史铁梁主编，模具设计指导.北京.机械工业出版社.2003-8.26陕 西 航 空 职 业 技 术 学 院工 艺 路 线 表第 1页共 1页产品型号定模座板零（组）件号定模座板零（组）件名称定模座板材 料45钢板毛坯种类型材工序号工 序 名 称机 床夹 具备注机床类别型 号0开 料30 X 325X405锯 床5铣四周轮廓铣床铣床夹具10铣上平面铣床铣床夹具15铣底面铣床铣床夹具20钻上平面各孔钻床钻床夹具25钳工修整30检验354045陕 西 航 空 职 业 技 术 学 院工 艺 路 线 表第 1页共 1页产品型号零（组）件号零（组）件名称材 料45钢板毛坯种类型材工序号工 序 名 称机 床夹 具备注机床类别型 号0开 料30 X 305 X 205锯 床5铣四周轮廓铣床铣床夹具10铣上平面铣床铣床夹具15铣底面铣床铣床夹具20钻上平面各孔钻床钻床夹具25钳工修整30检验354045陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称下 料工序号0第 1 页共7页类别零（组）件号零（组）件名称定模座板材 料45钢板机 床锯 床硬 度夹 具工 步刀 具工步号内 容刀 具量 具1开 料30 X 325X405游标卡尺附注：检验毛坯的牌号学生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称下 料工序号0第 1 页共7页类别零（组）件号零（组）件名称顶杆固定板材 料45钢板机 床锯 床硬 度夹 具工 步刀 具工步号内 容刀 具量 具1开 料30 X 305 X 205游标卡尺附注：检验毛坯的牌号学生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称铣上平面工序号10第 3 页共 7页类别零（组）件号零（组）件名称定模座板材 料45机 床铣床硬 度夹 具工 步刀 具工步号内 容刀 具量 具1粗铣上平面面铣刀游标卡尺2精铣上平面面铣刀游标卡尺附注：学 生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称铣上平面工序号10第 3 页共 7页类别零（组）件号零（组）件名称顶杆固定板材 料45机 床铣床硬 度夹 具工 步刀 具工步号内 容刀 具量 具1粗铣上平面面铣刀游标卡尺2精铣上平面面铣刀游标卡尺附注：学 生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称铣六方工序号15第 4 页共 7页类别零（组）件号零（组）件名称定模座板材 料45钢机 床铣床硬 度夹 具工 步刀 具工步号内 容刀 具量 具1粗铣底面面铣刀角度尺游标卡尺2精铣底面面铣刀角度尺游标卡尺附注：保证各平面的平行度和垂直度学生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称钻上平面各孔工序号20第 5 页共 7页类别零（组）件号零（组）件名称定模座板材 料45钢板机 床铣床硬 度夹 具铣床夹具工 步刀 具工步号内 容刀 具量 具1铣图示台阶孔铣刀游标卡尺3附注：保证各平面的垂直度学 生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称钻上平面各孔工序号20第 5 页共 7页类别零（组）件号零（组）件名称顶针固定板材 料45钢板机 床钻床硬 度夹 具钻床夹具工 步刀 具工步号内 容刀 具量 具1钻上平面各孔钻床游标卡尺3附注：保证各平面的垂直度学 生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称钻上平面各孔工序号25第 5 页共 7页类别零（组）件号零（组）件名称顶针固定板材 料45钢板机 床钻床硬 度夹 具钻床夹具工 步刀 具工步号内 容刀 具量 具1钻上平面各孔钻床游标卡尺3附注：保证各平面的垂直度学 生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称钳工精修工序号30第 6页共 7页类别零（组）件号零（组）件名称定模座板材 料45钢板机 床硬 度夹 具工 步刀 具工步号内 容刀 具量 具1钳工去毛刺修锐边锉刀附注：学生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称粗铣四周轮廓工序号5第 2 页共7页类别零（组）件号定模座板零（组）件名称定模座板材 料45钢板机 床铣床硬 度夹 具工 步刀 具工步号内 容刀 具量 具1粗铣四周轮廓立铣刀游标卡尺2精铣四周轮廓立铣刀游标卡尺附注：学生指导教师陕 西 航 空 职 业 技 术 学 院工 序 卡 片工序名称粗铣四周轮廓工序号5第 2 页共7页类别零（组）件号零（组）件名称顶杆固定板材 料45钢板机 床铣床硬 度夹 具工 步刀 具工步号内 容刀 具量 具1粗铣四周轮廓立铣刀游标卡尺2精铣四周轮廓立铣刀游标卡尺附注：学生指导教师Int J Adv Manuf Technol (2000) 16:739747 2000 Springer-Verlag London LimitedAutomated Assembly Modelling for Plastic Injection MouldsX. G. Ye, J. Y. H. Fuh and K. S. LeeDepartment of Mechanical and Production Engineering, National University of Singapore, SingaporeAn injection mould is a mechanical assembly that consists ofproduct-dependent parts and product-independent parts. Thispaper addresses the two key issues of assembly modellingfor injection moulds, namely, representing an injection mouldassembly in a computer and determining the position andorientation of a product-independent part in an assembly. Afeature-based and object-oriented representation is proposedto represent the hierarchical assembly of injection moulds.This representation requires and permits a designer to thinkbeyond the mere shape of a part and state explicitly whatportions of a part are important and why. Thus, it providesan opportunity for designers to design for assembly (DFA). Asimplified symbolic geometric approach is also presented toinfer the configurations of assembly objects in an assemblyaccording to the mating conditions. Based on the proposedrepresentation and the simplified symbolic geometric approach,automatic assembly modelling is further discussed.Keywords: Assemblymodelling;Feature-based;Injectionmoulds; Object-oriented1.IntroductionInjection moulding is the most important process for manufac-turing plastic moulded products. The necessary equipment con-sists of two main elements, the injection moulding machineand the injection mould. The injection moulding machines usedtoday are so-called universal machines, onto which variousmoulds for plastic parts with different geometries can bemounted, within certain dimension limits, but the injectionmould design has to change with plastic products. For differentmoulding geometries, different mould configurations are usuallynecessary. The primary task of an injection mould is to shapethe molten material into the final shape of the plastic product.This task is fulfilled by the cavity system that consists of core,cavity, inserts, and slider/lifter heads. The geometrical shapesCorrespondence and offprint requests to: Dr Jerry Y. H. Fuh, Depart-ment of Mechanical and Production Engineering, National Universityof Singapore (NUS), 10 Kent Ridge Crescent, Singapore 119260.E-mail: mpefuhyhK.sgand sizes of a cavity system are determined directly by theplastic moulded product, so all components of a cavity systemare called product-dependent parts. (Hereinafter, product refersto a plastic moulded product, part refers to the component ofan injection mould.) Besides the primary task of shaping theproduct, an injection mould has also to fulfil a number oftasks such as the distribution of melt, cooling the moltenmaterial, ejection of the moulded product, transmitting motion,guiding, and aligning the mould halves. The functional partsto fulfil these tasks are usually similar in structure and geo-metrical shape for different injection moulds. Their structuresand geometrical shapes are independent of the plastic mouldedproducts, but their sizes can be changed according to theplastic products. Therefore, it can be concluded that an injectionmould is actually a mechanical assembly that consists ofproduct-dependent parts and product-independent parts. Figure1 shows the assembly structure of an injection mould.The design of a product-dependent part is based on extractingthegeometryfrom theplasticproduct.Inrecentyears,CAD/CAM technology has been successfully used to helpmould designers to design the product-dependent parts. TheMouldMouldbaseCoolFillLayoutPlugSocketCav_1Cav_2CA-plateGuild-bushTCP-plateBep-plateCb-plateEa-plateEb-plateGuid-pinIp-plateRet-pinSliderbodyguideStop-blkHeel-blkheadCoreCavityProduct-independent partProduct-dependent partMove-halfFixed-halfFig. 1. Assembly structure of an injection mould.740X. G. Ye et al.automatic generation of the geometrical shape for a product-dependent part from the plastic product has also attracted alot of research interest 1,2. However, little work has beencarried out on the assembly modelling of injection moulds,although it is as important as the design of product-dependentparts. The mould industry is facing the following two difficult-ies when use a CAD system to design product-independentparts and the whole assembly of an injection mould. First,there are usually around one hundred product-independent partsin a mould set, and these parts are associated with each otherwith different kinds of constraints. It is time-consuming forthe designer to orient and position the components in anassembly. Secondly, while mould designers, most of the time,think on the level of real-world objects, such as screws, plates,and pins, the CAD system uses a totally different level ofgeometrical objects. As a result, high-level object-oriented ideashave to be translated to low-level CAD entities such as lines,surfaces, or solids. Therefore, it is necessary to develop anautomatic assembly modelling system for injection moulds tosolve these two problems. In this paper, we address the follow-ing two key issues for automatic assembly modelling: rep-resenting a product-independent part and a mould assembly ina computer; and determining the position and orientation of acomponent part in an assembly.This paper gives a brief review of related research inassembly modelling, and presents an integrated representationfor the injection mould assembly. A simplified geometric sym-bolic method is proposed to determine the position and orien-tation of a part in the mould assembly. An example of auto-matic assembly modelling of an injection mould is illustrated.2.Related ResearchAssembly modelling has been the subject of research in diversefields, such as, kinematics, AI, and geometric modelling. Lib-ardi et al. 3 compiled a research review of assembly model-ling. They reported that many researchers had used graphstructures to model assembly topology. In this graph scheme,the components are represented by nodes, and transformationmatrices are attached to arcs. However, the transformationmatrices are not coupled together, which seriously affects thetransformation procedure, i.e. if a subassembly is moved, allits constituent parts do not move correspondingly. Lee andGossard 4 developed a system that supported a hierarchicalassembly data structure containing more basic informationabout assemblies such as “mating feature” between the compo-nents. The transformation matrices are derived automaticallyfrom the associations of virtual links, but this hierarchicaltopology model represents only “part-of” relations effectively.Automatically inferring the configuration of components inan assembly means that designers can avoid specifying thetransformation matrices directly. Moreover, the position of acomponent will change whenever the size and position of itsreference component are modified. There exist three techniquesto infer the position and orientation of a component in theassembly: iterative numerical technique, symbolic algebraictechnique, and symbolic geometric technique. Lee and Gossard5 proposed an iterative numerical technique to compute thelocation and orientation of each component from the spatialrelationships. Their method consists of three steps: generationof the constraint equations, reducing the number of equations,and solving the equations. There are 16 equations for “against”condition, 18 equations for “fit” condition, 6 property equationsfor each matrix, and 2 additional equations for a rotationalpart. Usually the number of equations exceeds the number ofvariables, so a method must be devised to remove the redundantequations. The NewtonRaphson iteration algorithm is used tosolve the equations. This technique has two disadvantages:first, the solution is heavily dependent on the initial solution;secondly, the iterative numerical technique cannot distinguishbetween different roots in the solution space. Therefore, itis possible, in a purely spatial relationship problem, that amathematically valid, but physically unfeasible, solution canbe obtained.Ambler and Popplestone 6 suggested a method of comput-ing the required rotation and translation for each componentto satisfy the spatial relationships between the components inanassembly.Sixvariables(threetranslationsandthreerotations) for each component are solved to be consistent withthe spatial relationships. This method requires a vast amountof programming and computation to rewrite related equationsin a solvable format. Also, it does not guarantee a solutionevery time, especially when the equation cannot be rewrittenin solvable forms.Kramer 7 developed a symbolic geometric approach fordetermining the positions and orientations of rigid bodies thatsatisfy a set of geometric constraints. Reasoning about thegeometric bodies is performed symbolically by generating asequence of actions to satisfy each constraint incrementally,which results in the reduction of the objects available degreesof freedom (DOF). The fundamental reference entity used byKramer is called a “marker”, that is a point and two orthogonalaxes. Seven constraints (coincident, in-line, in-plane, parallelFz,offsetFz, offsetFx and helical) between markers are defined.For a problem involving a single object and constraints betweenmarkers on that body, and markers which have invariant attri-butes, action analysis 7 is used to obtain a solution. Actionanalysis decides the final configuration of a geometric object,step by step. At each step in solving the object configuration,degrees of freedom analysis decides what action will satisfyone of the bodys as yet unsatisfied constraints, given theavailable degrees of freedom. It then calculates how that actionfurther reduces the bodys degrees of freedom. At the end ofeach step, one appropriate action is added to the metaphoricalassembly plan. According to Shah and Rogers 8, Kramerswork represents the most significant development for assemblymodelling. This symbolic geometric approach can locate allsolutionsto constraintconditions, andis computationallyattractive compared to an iterative technique, but to implementthis method, a large amount of programming is required.Although many researchers have been actively involved inassembly modelling, little literature has been reported on fea-ture based assembly modelling for injection mould design.Kruth et al. 9 developed a design support system for aninjection mould. Their system supported the assembly designfor injection mouldsthrough high-level functionalmouldobjects (components and features). Because their system wasAutomated Assembly Modelling741based on AutoCAD, it could only accommodate wire-frameand simple solid models.3.Representation of Injection MouldAssembliesThe two key issues of automated assembly modelling forinjection moulds are, representing a mould assembly in com-puters, and determining the position and orientation of a pro-duct-independent part in the assembly. In this section, wepresent an object-oriented and feature-based representation forassemblies of injection moulds.The representation of assemblies in a computer involvesstructural and spatial relationships between individual parts.Such a representation must support the construction of anassembly from all the given parts, changes in the relativepositioning of parts, and manipulation of the assembly as awhole. Moreover, the representations of assemblies must meetthe following requirements from designers:1. It should be possible to have high-level objects ready touse while mould designers think on the level of real-world objects.2. The representation of assemblies should encapsulate oper-ational functions to automate routine processes such aspocketing and interference checks.To meet these requirements, a feature-based and object-orientedhierarchical model is proposed to represent injection moulds.An assembly may be divided into subassemblies, which in turnconsists of subassemblies and/or individual components. Thus,a hierarchical model is most appropriate for representing thestructural relations between components. A hierarchy impliesa definite assembly sequence. In addition, a hierarchical modelcan provide an explicit representation of the dependency ofthe position of one part on another.Feature-based design 10 allows designers to work at asomewhat higher level of abstraction than that possible withthe direct use of solid modellers. Geometric features areinstanced, sized, and located quickly by the user by specifyinga minimum set of parameters, while the feature modeller worksout the details. Also, it is easy to make design changes becauseof the associativities between geometric entities maintained inthe data structure of feature modellers. Without features,designers have to be concerned with all the details of geometricconstruction procedures required by solid modellers, and designchanges have to be strictly specified for every entity affectedby the change. Moreover, the feature-based representation willprovide high-level assembly objects for designers to use. Forexample, while mould designers think on the level of a real-world object, e.g. a counterbore hole, a feature object of acounterbore hole will be ready in the computer for use.Object-oriented modelling 11,12 is a new way of thinkingabout problems using models organised around real-world con-cepts. The fundamental entity is the object, which combinesboth data structures and behaviour in a single entity. Object-oriented models are useful for understanding problems anddesigning programs and databases. In addition, the object-oriented representation of assemblies makes it easy for a“child” object to inherit information from its “parent”.Figure 2 shows the feature-based and object-oriented hier-archical representation of an injection mould. The represen-tation is a hierarchical structure at multiple levels of abstraction,from low-level geometric entities (form feature) to high-levelsubassemblies. The items enclosed in the boxes represent“assembly objects” (SUBFAs, PARTs and FFs); the solid linesrepresent “part-of” relation; and the dashed lines representother relationships. Subassembly (SUBFA) consists of parts(PARTs). A part can be thought of as an “assembly” of formfeatures (FFs). The representation combines the strengths of afeature-based geometric model with those of object-orientedmodels. It not only contains the “part-of” relations betweenthe parent object and the child object, but also includes aricher set of structural relations and a group of operationalfunctions for assembly objects. In Section 3.1, there is furtherdiscussion on the definition of an assembly object, and detailedrelations between assembly objects are presented in Section Definition of Assembly ObjectsIn our work, an assembly object, O, is defined as a unique,identifiable entity in the following form:O = (Oid, A, M, R)(1)Where:Oid is a unique identifier of an assembly object (O).A is a set of three-tuples, (t, a, v). Each a is called anattribute of O, associated with each attribute is a type,t, and a value, v.M is a set of tuples, (m, tc1, tc2, %, tcn, tc). Eachelement of M is a function that uniquely identifies amethod. The symbol m represents a method name; andmethods define operations on objects. The symbol tci(iFig. 2. Feature-based, object-oriented hierarchical representation.742X. G. Ye et al.= 1, 2, %, n) specifies the argument type and tc specifiesthe returned value type.R is a set of relationships among O and other assemblyobjects.Therearesixtypesofbasicrelationshipsbetween assembly objects, i.e. Part-of, SR, SC, DOF,Lts, and Fit.Table 1 shows an assembly object of injection moulds, e.g.ejector. The ejector in Table 1 is formally specified as:(ejector-pinF1, (string, purpose, ejecting moulding),(string, material, nitride steel), (string, catalogFno,THX),(checkFinterference(), boolean), (pocketFplate(), boolean),(part-of ejectionFsys), (SR Align EBFplate), (DOF Tx,Ty).In this example, purpose, material and catalogFno areattributes with a data type of string; checkFinterference andpocketFplate are member functions; and Part-of, SR and DOFare relationships.3.2Assembly RelationshipsThere are six types of basic relationships between assemblyobjects, Part-of, SR, SC, DOF, Lts, and Fit.Part-ofAn assembly object belongs to its ancestor object.SRSpatial relations: explicitly specify the positionsandorientationsofassemblyobjectsinanassembly.Foracomponentpart,itsspatialrelationship is derived from spatial constraints(SC).SCSpatial constraints: implicitly locate a componentpart with respect to the other parts.DOFDegrees of freedom: are allowable translational/rotational directions of motion after assembly, withor without limits.LtsMotion limits: because of obstructions/interferences,the DOF may have unilateral or bilateral limits.FitSize constraint: is applied to dimensions, in orderto maintain a given class of fit.Table 1. Definition of an assembly object-ejector.Object Oidejector-pinF1Instance-ofEjectorFpinDerived from ejector classAPurpose “ejecting moulding” Type stringMaterial “nitrided steel”Type stringCatalogFno “THX”Type stringMCheckFinterferenceCheck interference(coolFobj)between ejectors andcooling linesPocketFplate()Make a hole on plate toaccommodate ejector pinsRPart-ofejectorFsysSRalign with EBplateDOFTx, TyAmong all the elements of an assembly object, the relation-ships are most important for assembly design. The relationshipsbetween assembly objects will not only determine the positionof objects in an assembly, but also maintain the associativitiesbetween assembly objects. In the following sub-sections, wewill illustrate the relationships at the same assembly level withthe help of examples.3.2.1Relationships Between Form FeaturesMould design, in essence, is a mental process; mould designersmost of the time think on the level of real-world objects suchas plates, screws, grooves, chamfers, and counter-bore holes.Therefore, it is necessary to build the geometric models of allproduct-independent parts from form features. The moulddesigner can easily change the size and shape of a part,because of the relations between form features maintained inthe part representation. Figure 3(a) shows a plate with acounter-bore hole. This part is defined by two form features,i.e. a block and a counter-bore hole. The counter-bore hole(FF2) is placed with reference to the block feature FF1, usingtheir local coordinates F2and F1, respectively. Equations (2)(5) show the spatial relationships between the counter-borehole (FF2) and the block feature (FF1). For form features,there is no spatial constraint between them, so the spatialrelationships are specified directly by the designer. The detailedassembly relationships between two form features are definedas follows:SR(FF2, FF1):F2i= F1i(2)F2j= F1j(3)Fig. 3. Assembly relationships.Automated Assembly Modelling743F2k= F1k(4)r2F= r1F+ b22*F1j+ AF1*F1i(5)DOF:ObjFhasF1FRDOF(FF2, F2j)The counter-bore feature can rotate about axis F2j.LTs(FF2, FF1):AF1, b11 0.5*b21(6)Fit (FF2, FF1):b22= b12(7)WhereF and r are the orientation and position vectors of fea-tures.F1= (F1i, F1j, F1k),F2= (F2i, F2j, F2k).bijis the dimension of form features, Subscript i isfeature number, j is dimension number.AF1is the dimension between form features.Equations (2)(7) present the relationships between the formfeature FF1and FF2. These relationships thus determine theposition and orientation of a form feature in the part. Takingthe part as an assembly, the form feature can be consideredas “components” of the assembly.The choice of form features is based on the shape character-istics of product-independent parts. Because the form featuresprovided by the Unigraphics CAD/CAM system 13 can meetthe shape requirements of parts for injection moulds and thespatial relationships between form features are also maintained,we choose them to build the required part models. In additionto the spatial relationships, we must record LTs, Fits relation-ships for form features, which are essential to check thevalidity of form features before updating the models in theCAD system.3.2.2Relationships Between PartsIn an assembly, the position and orientation of a part is usuallyassociated with another part. Figure 3(b) shows a plate (PP1)and a screw (PP2). The relative placement of the screw isconstrained by the counter-bore hole on the plate. The relation-ships between the screw and the plate are defined as follows:SR(PP2, PP1):P2= MpP1(8)r2= Mrr1(9)SC(PP2, PP1):mate(f1,f2) axisFalign(axisF1, axisF2)DOF:ObjFhasF1FRDOF(PP2, P2j)The screw can rotate about P2jof the plate.LTs(PP2, PP1):A22, A12(10)Fits(PP2, PP1):A13= A21+ cc(11)Where:P1and P2are the orientation vectors of the plate andthe screw, and P1= (P1i, P1j, P1k), P2= (P2i, P2j, P2k).Mpand Mrare the transformation matrix between thescrew and the plate. is a Boolean operator.mate and axisFalign are constraints (detailed discussionabout them are given in the next section).r is a position vector.Aijis dimension of parts. Subscript i is part number, andj is dimension number.cc is the clearance between the screw and the plate.As we can see in Eqs. (8) and (9), it is essential to calculatethe matrix Mpand Mrto determine the position and orientationof the screw with reference to the plate. Mpand Mrcan bederived from the spatial constraints (SC). This derivationrequires the task of inferring the configuration of a part in anassembly, which will be discussed in the next section.We have presented a representation of the injection mouldassembly in a computer. At this stage, it might be worthwhileto summarise the benefits of this representation. Assembliesare represented as a collection of subassemblies that in turnmay consist of subassemblies and/or component parts, and acomponent part can further be considered as the assembly ofform features. Such hierarchical relationships imply an orderingon the assembly sequence and a parentchild link. The feature-based representation not only allows designers to work at ahigh-level of abstraction while designing individual parts, butalso extends the feature paradigm to assembly modelling,because this representation allows a component to be changedparametrically with the other components consequently havingtheir positions changed accordingly. The object-oriented rep-resentation can combine both the data structure and operationin an object. The encapsulated operational functions in anassembly object can help to automate the routine processessuch as the pocketing and interference check.4.Inferring Part Configuration in theAssemblyAs we can see from Eqs (8) and (9), the positions andorientations of parts in an assembly are eventually representedby the transformation matrices. For the sake of convenience,the spatial relationships are usually specified by the high-levelmating conditions such as “mate”, “align” and “parallel”. Thus,it is essential to derive automatically the explicit transformationmatrices between parts from implicit constraint relationships.Three techniques to infer the configurations of parts in anassembly have been discussed in Section 2. Because the sym-bolic geometric approach can locate all solutions to constraintequations withpolynomial time complexity, we use thisapproach to determine the positions and orientations of partsin an assembly. To implement this approach in assemblymodelling software, a large amount of programming is required.Therefore, a simplified geometric approach is proposed todetermine the positions and orientations of parts in an assembly.744X. G. Ye et al.In the symbolic geometric approach, determining positionsand orientations of parts is performed symbolically by generat-ing a sequence of actions to satisfy each constraint incremen-tally. The information required to satisfy each constraintincrementally is stored in a table of “plan fragments”. Eachplan fragment is a procedure that specifies a sequence ofmeasurements and actions that move parts in such a way asto satisfy the corresponding constraint. The plan fragment alsorecords the objects new degrees of freedom (DOFs) andassociated geometric invariants. Conceptually, Kramers planfragment table is a 3D dispatch table. We use TDOF torepresent translational degrees of freedom and RDOF to rep-resent rotational degrees of freedom. Then an entry in the planfragment table has the following form:planFfragment: kTDOF, RDOF, constraintFtypelTDOF = 0, 1, 2, 3RDOF = 0, 1, 2, 3constraintFtype=coincident,in-line,in-plane,parallelFz, offsetFz, offsetFx and helicalThe plan fragment table is an exhaustive enumeration of allthe states in the search space for the problem of moving anobject to satisfy a series of constraints between markers onthe object and markers fixed in the global coordinate frame.To enumerate the combination of different values of the abovethree parameters, 82 entries will be generated 7. If the searchspace for the problem can be reduced the number of entriesin a plan fragment table will decrease. To achieve this, thenumber of enumerate values for entry parameters must bedecreased. For example, for a specified constraint type, if theenumeration values of TDOF change from 0,1,2,3 to 0,3,then the search space is reduced.After a careful analysis of the constraints between compo-nents of an injection mould, four basic primitive constraints areintroduced: in-line, parallelFz, parallelFz1 and parallelFoffset.Their definitions and algebraic equations are as follows:in-line(M1, M2): M1lies on the line through M2parallel to theZ-axis of M2.ugmp(M1) gmp(M2)u gmz(M2)u = 0(12)parallelFz(M1, M2): the Z-axes of markers M1and M2areparallel and have the same direction.gmz(M1) gmz(M2) = 1(13)parallelFz1(M1, M2): the Z-axes of markers M1and M2areparallel and have the opposite direction.gmz(M1) gmz(M2) = 1(14)paralleFoffset(M1, M2, d): Applicable only in conjunctionwith parallelFz or parallelFz1, specifies the distancebetween M1position and M2position.gmp(M1) gmp(M2) = d(15)Where:M1and M2are markers.gmp(M) is the global marker position.gmz(M) is the global marker Z-axis.gmx(M) the global marker X-axis.d is the distance between M1and M2.In our simplified symbolic geometric approach, the enumer-ation vales of constraint types are inFline, parallelFz, par-relFz1, paralleFoffset. Compared with Kramers symbolic geo-metric approach, our constraint types are reduced from sevento four. This simplification will reduce the number of entriesin the plan fragment table. Based on these four primitiveconstraints, three high-level constraints were synthesised fortheusersconvenience.Theyaremate(M1,M2,d),planeFalign(M1, M2, d), and axisFalign(M1, M2). Their defi-nitions are given as follows:mate(M1, M2, d):parallelFz1(M1, M2) parallelFoffset(M1, M2, d)planeFalign(M1, M2, d):parallelFz(M1, M2) parallelFoffset(M1, M2, d)axisFalign(M1, M2):parallelFz(M1, M2) inFline(M1, M2)The assembly objects in an injection mould can have one,two or three synthesised constraints. For two and three syn-thesised constraints, the constraint sequence is further restricted.The sequences are as follows:mate(M1, M2, d) planeFalign(M3, M4, d2)mate(M1, M2, d1) axisFalign(M3, M4)planeFalign(M1, M2, d) axisFalign(M3, M4)mate(M1,M2,d1)axisFalign(M3,M4,d2)axisFalign(M5, M6).Because of these restrictions on the constraint sequences,the number of entries in our plan fragment table is substantiallyreduced. To solve for one, two or three constraints allowed inour system, only nine entries are required. For interactiveaddition of components to the assembly, more constraint typesand free sequences will increase the flexibility for users. How-ever, in automatic assembly modelling for an injection mould,as the spatial relationships are predefined in assembly objects,some of the sequence restrictions do not matter. With theabove-defined synthesised constraints, the structural relation-ships of a component part can be specified in the database ofthe components. When adding a component part to the mouldassembly, the system will first decompose the synthesisedconstraints into primitive constraints, then generate a groupof fragment plans to orient and position the component inthe assembly.5.Automated Assembly Modelling ofInjection MouldsAnyassemblyofinjectionmouldsconsistsofproduct-independent parts and product-dependent parts. The design ofindividual product-dependent parts is based on the geometryof the plastic part 1,2. Usually the product-dependent partshave the same orientation as that of the top-level assembly,and their positions are specified directly by the designer. Asfor the design of product-independent parts, conventionally,mould designers select the structures from the catalogues,Automated Assembly Modelling745build the geometric models for selected structures of product-independent parts, and then add the product-independent partsto the assembly of the injection mould. This design process istime-consuming and error-prone. In our system, a database isbuiltforallproduct-independentpartsaccordingtotheassembly representation and object definition described in Sec-tion 3. This database not only contains the geometric shapesand sizes of the product-independent parts, but also includesthe spatial constraints between them. Moreover, some routinefunctions such as interference check and pocketing are encapsu-lated in the database. Therefore, the mould designer must selectthe structure types of product-independent parts from the userinterfaces, and then the software will automatically calculatethe orientation and position matrices for these parts, and addthem to the assembly.5.1Mould Base SubassemblyAs can be seen from Fig. 1, the product-independent parts canbe further classified as the mould base and standard parts. Amould base is the assembly of a group of plates, pins, guidebushes, etc. Besides shaping the product, a mould has to fulfila number of functions such as clamping the mould, leadingand aligning the mould halves, cooling, ejecting the product,etc. Most moulds have to incorporate the same functionality,which results in a similarity of the structural build-up. Someform of standardisation in mould construction has been adopted.A mould base is the result of this standardisation.According to the feature-based and object-oriented assemblyrepresentation, the feature-based solid models for componentparts of the mould base are first constructed; next, the assemblyobjectsaredefinedbyestablishingrelationshipsbetweencomponents and encapsulating some functions in the componentparts; then, using these assembly objects, a hierarchical subas-sembly object a mould base can be formed. This mouldbase object can be instantiated by a group of data from thecatalogue database. Figure 4 shows the instantiation of themould base object to generate the specified mould base. Thisspecified mould base instance can be added automatically tothe mould assembly. The structural relations between the mouldbase subassembly and top assembly can be expressed by Eqs.(8) and (9), where Mpand Mrare the unit matrices.5.2Automatic Addition of Standard PartsA standard part is an assembly object. It can be definedaccording to Eq. (1) in Section 3.1. In the database, the spatialconstraints are specified by mate, planeFalign and axisFalign,but unlike the mould base, the position and orientation matricesof a standard part are left unknown. During instantiation,the software then automatically infers the explicit structuralrelationshipsbyusingthesimplifiedsymbolicgeometricapproach described in Section 4.5.3Pocketing for Assembly ObjectsOne of the important issues for automatic assembly design isthe automation of the pocketing process. Pocketing is anFig. 4. Instantiation of mould base.operation that makes an empty space in corresponding compo-nents to accommodate the inserted components. When an ejec-tor is added to the assembly, an empty space is required onthe EA plate to accommodate the ejector, as shown in Fig. 5.Since an object-oriented representation is adopted, eachassembly object can be represented by two solids, the realobject and the virtual object. The virtual object is modelledaccording to the space that a real object will occupy. Wheneveran assembly object is added to an assembly, its virtual objectisalsoaddedtotheassembly.TheoperationfunctionpocketFplate() in M of O will subtract the virtual object fromthe corresponding components (see Eq. (1) and Table 1).Moreover, because there are associativities between the virtualobject and real object, the pockets on the corresponding compo-nents will change with the modification of the real object.Fig. 5. Pocketing of assembled objects.746X. G. Ye et al.This automatic pocketing f