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重力滚道输送机阻尼装置设计【6张CAD图纸和毕业论文】【矿山输送机械】

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目    录
摘要 …………………………………………………………………1
第1章 绪 论 1
1.1 现代重力辊道输送机的概况 1
1.2 重力辊道输送机阻尼装置现状...............................................................2
1.3 主要内容及技术指标 4
第2章 总体方案的设计 6
2.1重力滚道输送机阻尼装置的工作原理 6
2.2方案的选择 6
2.3主要工作部件的设计 7
第3章 总体配置的确定 8
3.1阻尼辊筒的整体设计 8
3.2传动系统设计 8
3.3传动装置 9
3.4制动块的设计 9
第4章 阻尼辊筒的整体设计 10
  第5章 制动块的设计......................................................................10
5.1制动块的受力分析.............................................................................11

5.2计算摩擦快所受的挤压力Fj............................................................11

5.3求离心力FL.......................................................................................11

5.4计算摆块的有关参数........................................................................12

5.5计算阻尼辊筒内部的传动比i..........................................................13

第6章 传动部分设计 14
6.1初定Vt、D2和i.......................................................................................14
6.2确定齿轮的模数和齿数 14
6.3确定辊子的其他结构参数 15
  第7章 内置式阻尼辊筒的保养、使用、调整及修复 15
7.1每日技术保养 15
7.2传动装置的使用和调整 16
7.3阻尼辊筒的保管 16
7.4工作部件损坏的修复和调整 16
全文总结与展望 17
总结 17
课题展望 17
致谢 18
参考文献 19

摘  要

   重力式滚道输送机因其不需动力，结构简单等优点，在短距离物料输送中得到广泛的应用。重力式滚道输送机是利用输送物自身的重力沿斜面下滑进行输送的。由于重力的作用，输送物会愈滑愈快，产生输送物之间的互相碰撞挤压，使输送物损坏，甚至崩落或损伤人、机。在输送过程中，也可能由于输送机自身的原因，如辊筒变形过大，货物底部或托盘底部的粗糙或不规则，使其在输送过程中停止不动，无法再起动重新下滑，这时需要人力协助推动恢复下滑。
为了达到设计要求，根据较普遍的重力式滚道输送机，本设计阻尼装置主要采用内置装置。这在很大程度上节省了人力，而且在结构上比传统设计方法更为合理。经计算、校核，该装置符合设计要求，适合作为重力辊道输送机阻尼装置。
关键词：重力式滚道输送机；阻尼装置；


Abstract
 Gravity groove conveyor because its does not need to power, simple structure, etc, and in short material conveying widely applied.Gravity groove conveyor belt conveyor is using its own gravity conveying things along the decline in transmission cant.Because the pull of gravity, conveying the slippery thing will soon, produce conveying the each other between things collision extruding, make things conveying damage, even caving man, machine or injury. In the course of transmission for, also may be due to the conveyor their own reasons, such as the rollers deformation is too large, the bottom tray or at the bottom of the rough or irregular, in the conveying process is at a standstill, can't start to decline, at this moment need to promote human help restore to slide.
 In order to meet the design requirements, according to universal gravity groove conveyor, this design damping device is mainly using built-in device. This is largely save manpower, and on the structure more reasonable than the traditional design method.The calculation, checking, this device comply with the design requirements, suitable for as gravity roller conveyor damping device.


Key words: Gravity groove conveyor；Damping device。
第1章 绪 论
输送机的历史悠久，中国古代的高转筒车和提水的翻车，是现代斗式提升机和刮板输送机的雏形。输送机是在一定的线路上连续输送物料的物料搬运机械，又称连续输送机。输送机可进行水平、倾斜输送机，也可组成空间输送线路，输送线路一般是固定的。输送机输送能力大，运距长，还可在输送过程中同时完成若干工艺操作，所以应用十分广泛。
输送机是在一定的线路上连续输送物料的物料搬运机械，又称连续输送机。输送机可进行水平、倾斜 和垂直输送，也可组成空间输送线路，输送线路一般是固定的。输送机输送能力大，运距长，还可在输送过程中同时完成若干工艺操作，所以应用十分广泛。


内容简介：
山东轻工业学院毕业设计（论文）中期进展报告表学院机械与汽车工程学院专业班级机械08-2班学生姓名张淇翔学号200801011074导师姓名范维华设计（论文）题 目重力滚道输送机阻尼装置设计根据设计要求和重力滚道输送机阻尼装置的性能参数，在老师的指导下，前段时间主要完成了开题报告、英文翻译、实习报告的工作，并查阅相关的资料，拟定了设计方案。初步完成了阻尼装置基本机构的设计，传动机构的设计，重力滚道输送机的整体结构图。为了防止输送物下滑过快而造成的不必要的损失，应正确选择辊道倾角。摩擦系数的选择查阅了机械设计。阻尼装置，采用一套齿轮行星轮系传动机构，确定了阻尼型式。传动设计参考了机械设计与机械原理。完成了重力滚道输送机的总体结构图，对各个零件的布置有了初步设计并对阻尼装置进行的设计。根据总体设计图中的输送机参数对阻尼装置的制动力进行计算，然后根据制动力对制动辊进行设计，计算出输送机货物的阻尼，从而确定输送机货物的限速范围。在工作过程中，自己的疑问在老师和同学的帮助下，基本上都得到了解决。在以后的设计中将继续查阅相关资料，参考现有的设备对装配图进行优化。同时绘制零件图。根据设计要求，在老师的指导下，最快最好的完成各项工作。2012年05月28日指导教师评价意见1设计（论文）进展情况评价 （基本完成计划、部分完成计划、没有完成计划）2学生工作态度情况评价 （认真、一般、较差）3已完成设计（论文）质量评价 （较好、一般、较差）4设计（论文）不足之处及改进意见 指导教师签字： 年 月 日注：每名学生填写一份，并由指导教师填写意见、签字后，返还学生归档。本科毕业设计(论文)题目 重力滚到输送机阻尼装置设计 学院名称 机械与汽车工程学院 专业班级 机械08-2班 学生姓名 张淇翔 导师姓名 范维华 2012年 6 月 7 日 1 山东轻工业学院毕业实习报告 院系名称 机械与汽车工程学院 学生姓名 张淇翔 专业班级 机械082班 指导教师 范 维 华 二一二 年 四 月 二十二 日实 习 情 况 一 览 表时间地 点实习内容（讲座、参观、车间工作、总结等）指导教师备注3月中旬济南烟草配送中心参观精准分拣系统厂房和储藏烟草的仓库沈敏德范维华3月中旬将军集团济南卷烟厂参观了卷包车间，里面有数台生产速度为1000支/分钟的卷烟机和400包/分钟的包装机。尽管在卷丝车间有数台规模巨大的生产设备，然而所有设备都可以通过中央控制室来控制沈敏德范维华一、实习目的大学四年即将结束，接踵而来的是找工作，毕业，就业。压力是如此的巨大，因为我们大学四年的学习并没有给我们带来实际的工作能力，也没有丝毫的社会经验。利用毕业前的这一段时间，学校组织我们去参加了这次的集体实习，让我们对社会，对工作有些许的了解，以便毕业之后工作时不至于捉襟见肘。1、将理论与实践相结合通过这次的毕业实习，我们先后接触与本专业相关的一些实际工作，对于工作所要求具备的专业理论知识和基本技能有个大体客观的认识。实习过程中，要求我们通过听取公司产品方面的讲座学会理论和实践有机结合，将我们平日里学的知识有机的结合到实践中，然后更好的理解书本上的理论知识2、找到差距，尽快缩短差距实习时，我们会参观一些有名企业，期间公司负责人会给我们作讲座，带领我们参观他们企业内部的流程，员工工作的环境以及了解员工应该具有的专业技能。通过观察，我看到了他们这些企业所要求员工所具备的那种职业素质，专业技能。而从我们身上体现出来的却只是稚气未退的学生气，我们之间的差距明显很大，我们毕业尽快调整自己使自己成为一名于社会需要，于企业合格的人才。3、让自己尽快转变为社会人我们是即将毕业踏入社会的大学生，学生时代的稚气已不适合于社会。由一个学生到一个职业人员的转变过程，要求我们学会独立、成熟和坚强，踏入社会我们必须学会担负责任，脚踏实地，消除自己原本的担忧，努力工作每一天。这次实习就是为了让我们明白工作人要 拥有该有的素质和能力。 二、实习内容马克思哲学告诉我们，实践是检验真理的唯一标准。在大学里，我们学习了很多的理论知识，不过我们总觉得很空，这正是因为缺乏实践。实习正式将我们理论运用至实际生活中的机会。我们要想成为对社会有用的人才，要想在毕业后就可以找个好工作，实现自己的人生价值，就要重视好在大学里的实习。同时实习是一次不可多得的集体活动。平时在学校，除了上课，大家聚在一起的时间很少，缺乏生活上的专业上的必要交流，通过这次实习首先加强了同学们之间的凝聚力。 （一）将军集团济南卷烟厂将军集团济南卷烟厂是国有大型企业。在特别人员的带领下， 我们首先参观了卷包车间，里面有数台生产速度为1000支/分钟的卷烟机和400包/分钟的包装机。卷烟机主要是将烟丝、滤棒和包装纸卷在一起。在车间里，我们重点参观了卷烟和包装机，一万多个零件组成的机构，高速运转着，卷接、包装设备自动化水平高。当时有台机器出现了问题，由于整套装置有阻塞、夹条、掉条检测控制剔除系统工人师傅们很容易的排除故障。在参观中，我们注意到了卷烟厂高度自动化的流水线和精确的质量控制系统。当烟叶从整包被分离后，就开始进入加工阶段。在经过皮带传输和振动运输到各个加工环节过程中，对流量有着严格的控制，皮带上安装有电子传感器，能通过控制带速来控制流量。尽管在卷丝车间有数台规模巨大的生产设备，然而所有设备都可以通过中央控制室来控制。由于企业引入了现场总线，使得所有生产状况都可以及时在中控室的电脑控制屏上显示，包括动力部门的能源控制。 在现场，我们提出询问了许多感兴趣的问题，有关人员热情细致地给予解释，直到我们把整个工艺、生产流程了解为止。先进的生产设备，有序的生产现场，高素质的操作员工，给我们留下了深刻的印象。卷包车间的卷接包、装封箱、入库全部实现了自动化。经技术人员介绍，整个卷烟的生产流程如下：投料开包切片回槽(提温加水) 储存两个小时左右脱水卷烟包装。 通过实习发现的不足：原机装封箱机速度不高，只能一台装封箱机对应一台套卷包设备；二是离仓库比较远，不利于输送并且在输送过程中易造成破损；设备多并且控制比较复杂，操作和修理维护都需要大量的人力物力。（二） 济南烟草配送中心在本次主要对济南烟草配送中心两家单位进行了详细的实地的参观和了解，着重对这家单位的物流配送体系，物流配送设备，在各个环节中所采用的现代化技术以及整个物流的资源配置系统进行了详尽的认识和学习，因为两家企业的设备与流程大体相近，现主要介绍济南烟草配送中心。济南烟草配送中心隶属于济南烟草专卖局，济南市烟草专卖局资本雄厚，在面对国际间激烈的烟草市场的发展竞争下，积极采用先进技术，提高自己的信息化和自动化建设。尤其是以济南烟草配送中心是作为新型的现代物流来建设，坐落于济南高新区，与齐鲁软件园毗邻，尖端的环境优势使得济南烟草物流在收发配送方面独具优势，同时济南烟草物流中心通过网络营销、仓储系统、分拣系统、线路优化、GPS车辆监控等信息系统技术，使得济南烟草物流中心的快速反应令人吃惊，对济南地区的烟草配送在整个省内行业乃至全国位居前列。在济南烟草配送中心主要参观的是兰剑物流为济南烟草配送中心和烟台烟草配送中心设计的烟草的仓储系统、分拣系统和相关配送系统。在最开始的相关工作人员讲解中我们了解到，烟草行业的竞争已经不再局限于国内烟草企业的竞争，跨国烟草企业的竞争压力，让中国烟草行业面临巨大的挑战。能否全面建立完善的烟草物流配送体系是烟草行业能否取胜的关键环节，如何布局规划配送中心的建设是烟草行业不得不去思考的问题。而此套物流方案解决了配送运营体系中的许多问题，实现了配送网点的合理布局，资源的优化配置及时周转，提高了分拣的效率，大大降低了配送成本，总体上全面提升了烟草配送效率。电话访销、精准分拣、及时配送，提高了服务质量和顾客忠诚度，减少了市场上非正规渠道卷烟的冲击压力，降低了物流成本。根据老师和公司的安排流程，首先我们参观了烟草仓库的存储系统。根据老师解说，此烟草存储所用的仓库是一个自动化立体仓库。从货物进入，分为两种方式，一种是较为传统的传送带运输方式，但是效率仍然比人工快很多，用的比较多的是采取叉车托盘方式，整托盘烟草进入，然后进行仓库保管即入库。入库过程是放到传送带由电脑全程操作，然后经由由堆垛机，然后通过工业计算机的指令发送到由操作人员预先设定相关程序，采用了RFID射频识别技术可以读取货物的一切信息并将其分配到应有的位置，堆垛机按以获取的信息自动将货物准确无误放在应在的位置。这种入库工作流程几乎是全自动化，只需要很少的几个操作人员进行监控和操作，而且效率很高，整个系统设计的全面合理，功能的密切统一和集中以及自动化的程度之高，都给我了很大的震撼。接下来我们又去了分拣区的流水线查看其工作流程，刚开始，还没有运作，只是听讲解，说这套系统属于第三代烟草分拣系统（第四代也已经研制完毕，尚未完善投入），分拣速度很快，以及精确的自动化包装处理，听得我们云里雾里，因为每条线上工作的也就四五个人，到底搞不清到底是怎么分拣这么多烟草满足济南市这么多客户的订单，稍等了几分钟，分拣线开始运作。根据一步步的流程，各种烟从不同的槽口被吐出，快速的经过传送带，然后送到包装台，快速的进行包装，然后电子显示屏显示下一个客户的订单数量，看似很简单的流程，但是能够控制的这么好，而且很精确的控制各类的烟草所要出具的数量，这一系列流程的整合，大大的提高了分拣的效率和精确度。全部自动一体化的完成，让我深深感受到了现代化的信息系统所创造的价值。最后关于烟草的配送系统，由于GPS系统正在更新为3G，所以老师根据历史资料进行解说，经过查资料了解到，从整个烟草配送体系功能来看，本系统的在运输方面，使用采用的电子地图和GPS实时定位系统,地图上面标明了根据各销售点的位置而设计好的最优配送路线以及货车采用的GPS定位系统，可准确地了解每一辆货车所在的位置及每次所消耗的时间，最终可准确的落实每一天的工作效率。同时对济南烟草运输线路的全面优化，重新将济南各个区域布局，减少各区间之间的叠加、冲突，使得交叉覆盖面积最小交叉覆盖率小于15%，路线得到更加合理的配置。物流信息，作为中枢神经系统的物流信息在整个配送系统中起到的作用计划预测、动态分析、及时提供市场动态等相关内容。济南烟草配送信息这一块做的比较到位，从计算机中能及时获得相关的信息，为做出研究分析、制定相关策略提供了有力的保障。 本次实习总结：通过这次实习，我更深刻的认识到物流这个概念的深度和广度，以及在现实生活中，我们对物流的应用的层面，我发现课本的理论知识在实际过程中运用的很巧妙，因地制宜，灵活贯通给我了很大的启示，也发觉了真正的实际操作中，我们对课本知识掌握的不够扎实，也不够全面，更没有系统的思维和考虑。所以，我要学习的东西还很多，要真正领会课本的理论知识以及运用的方法和价值。结论和建议：在济南烟草中心，采用了现代信息化的设施和自动化的整合系统，在很大程度上降低人员的劳动强度，节约生产成本，提高工作效率； 对于在烟草行业推广应用新兴的物流技术，降低物流成本、实现配送现代化管理起了推动作用。然而在实际运作中，完备齐全的自动化系统会花费很大资金，希望在系统的设计方面能加以改善以节约成本，同时注重成本和效能，达到性能最优化，从而可以推广到其他物流企业，真正的做好我国物流行业的领头羊。同时在做烟草的同时，关于实地的配送运输问题上，建议与部分物流相关企业进行合作，实现附带运输，以增加附加值和利润，同时可以降低成本。3、 实习总结 毕业前安排这次毕业实习使我收获很多。老师带领我们参观一些卷烟厂和物流中心公司还有知名企业-张裕公司，深入到各公司的生产车间观看员工的工作环境、产品生产工艺和研发设计产品。每到一个公司，负责人都会很详细地给我们介绍公司产品以及它们利用的基本原理。这次毕业实习让我了解专业有关的工作，对之前的毕业后从事的工作存在的疑惑也解除了。在学校里，我们学习专业基本知识，缺乏专业实践能力的锻炼，离现实社会所需专业人才还有很大的差距，一直抱怨学校里学到的知识没有实际利用价值，其实这都是借口，进入大学，我们首先学会独立自学，然而我们这点没有做好，更没有人限制我们时间，是我们没有利用好它。尽管实验室条件有限，那些都是客观理由。“活到老学到老”这句话永远具有现实意思。就像那位引导员说的，别把自己想象的太优秀，真正踏入社会，你会发现很多问题。毕业实习给我们毕业后的工作打下了一定的基础，让我们懂得了工作跟学习两码事。马上要踏入社会，进入工作岗位了，一个人需要迅速转变角色，适应社会，去创造价值，把专业知识运用出来，并在工作上不断学习，不断创新。毕业实习让我们学到了很多，感谢学校，感谢老师给予我们这次机会。这学期的实习的实习使我对自己的专业有了直接具体的认识，在亲身经历生产过程以前对机械这一行业的了解仅仅限于理论知识，对各种机床和生产设备也没有接触太多。实习之后，可以大致了解到现行的机械行业的运行情况，以及现在的制造业发展的动向。指导教师评语：实习成绩：指导教师： 年 月 日山 东 轻 工 业 学 院毕 业 设 计（论 文）任 务 书机械与汽车工程学院 2008 级 机械设计制造及其自动化专业 姓名 张淇翔题目 重力滚道输送机阻尼装置设计主要内容、基本要求、主要参考资料等：1. 主要内容：本设计任务是根据部分影象资料和网上查阅地资料进行研发工作，这次设计主要根据现代物流的要求，宗合考滤不同地作业项目，不同附件的按装结构，对重力滚道输送机阻尼装置设计进行总体设计。要求制动可靠，能有效的防止输送物下滑过快，配件具有一定的通用性，技术先进，结构紧凑。此设计国内尚无此种类型的定型产品，此设计国内尚无此种类型的定型产品，属开发设计。2. 基本要求：对现代物流系统和重力滚道输送机有基本了解，对阻尼装置的工作原理有全面细致的理解，结合机械与物流等相关知识进行设计。完成重力滚道输送机阻尼装置设计图纸，写出设计论文。3. 主要参考资料：设计手册，部分重力滚道输送机图片资料，现代物流资料及机械相关资料。完成期限：自 2012 年 3 月 15 日至 2012年 6 月 15 日指导教师： 范维 华 教研室主任：学院院长： 年 月 日毕业设计（论文）开题报告课题名称重力滚道输送机阻尼装置设计课题类型导师姓名学生姓名学 号专业班级一、 设计依据与目的 1、 物料搬运现状物料搬运是保证物流系统畅通有效运行的一个重要环节，因此，完成物料搬运的输送机械，也就成为物流系统设计规划人员重点关注的项目。在固定路径的运送中（如生产物流中，制品在各工序间的流动，仓储系统中货物的手法以及配送中心的拣货发货等），大都采用辊筒、皮带或链条等型式的输送机械，即单元负载输送机，其中一滚筒型式较为常见。2、 滚筒式输送机分类辊筒式输送机根据其动力源不同可分为两类。一类是动力式，即辊筒由动力带动旋转。通常以电动机为原动力。另一类为重力式辊筒输送机。这类输送机没有动力，靠将辊道倾斜成一个适当的角度，辊道上被输送的物体在重力作用下自行下滑，因不需动力，结构简单等优点，在短距离物料输送中得到广泛应用。3、 设计目的 由于重力的作用，在重力滚道输送机上，输送物会愈滑愈快，产生输送物之间的相互碰撞挤压，使输送物损坏，甚至崩落或损伤人、机。为了避免此类事故，所以需要设计一个阻尼装置，即制动辊。二、 设计内容根据重力滚道输送机发展的需要，根据客户的实际条件的需求，结合机械技术，参考、计算、分析现有的重力滚道输送机，设计出一套符合设计要求及社会需求的方案。三、 设计方法及及技术路线1、设计方法(1)选择设计题目，仔细听取老师所讲的内容，认真思考一下。 （2）上网 、去图书馆查阅资料，弄明白自己到底需要做什么。 （3）根据所收集的资料作出设计方案。 （4）经过计算设计的数据，画出设计装配图、零件图。 （5）整理资料，写设计说明书，准备答辩。 2、技术路线我所设计的重力滚道输送机阻尼装置是一种制动辊装置，它能根据输送机的速度与给定的速度进行对比，然后进行有效的调整。 3、参考文献 1.濮良贵、纪明刚主编。机械设计（第八版）。高等教育出版社 2.孙恒、陈作模、葛文杰主编。机械原理（第七版）。高等教育出版社 3.申纲领主编。现代物流管理。北京大学出版社 四、 设计安排3月中旬：领取设计题目3月中旬到4月初：查阅相关资料，初步提出设计方案4月6日到10日：进行毕业实习4月下旬：撰写开题报告和实习报告，并提出设计方案4月下旬到5月初：进行结构方案设计，绘制装配草图5月初到六月初：进行设计计算，对方案中涉及到的各零部件进行选择并对其刚度、强度等进行核算，并绘制零件图、装配图6月上旬：整理、编写任务说明书，并打印零件图、装配图、任务说明书，准备毕业答辩五、 设计总结指导教师意见：指导教师： 年 月 日在工程设计研究13(2002)5564工业部10.1007 / s00163 - 001 -0007- 4针对理想的机械工程设计支持系统的研究大卫G.Ullman摘要：本文详细介绍了在开发进展理想的机械设计的支持系统。它试图填补这个工程师的需求和目前市面上的计算机辅助设计(CAD)系统之间的差距。自从强调了计算机辅助设计(CAD) 这个术语，电脑已成为人类设计师的强有力的助手，这篇文章的内容是设计师的的中心任务。它紧紧根据设计师所做的项目和他们开发的信号系统项目的类型。17项关于理想机械设计的支持系统在这里被一一列举出来。这些先进的信号系统直接应用于设计过程和实际应用与发展中，对于这十七项中的任何一项,根据目前他们的发展情况，他们是目前最先进也是有很大未来发展空间的研究项目。关键词：机械工程设计、计算机辅助设计(CAD),支持系统。1介绍本文总结了理想机械工程设计支持系统的发展进程。近30年来,计算机辅助设计系统已经被他们的开发者作为支持系统工程设计,发展产品的系统加以吹捧。这是说计算机辅助设计(CAD)系统在关于怎样在工作场所使设计得以实现方面有重大的影响,令人惊讶的是,很少有关于这个系统的对设计者和最终产品方面影响的正式研究。这篇文章介绍了一种讨论这些效应结构。2000年2月11日收到:/2000年12月9日校稿:2001年9月19日接受: /2001年11月13在线发表2001年Springer-VerlagD.G.Ullman俄勒冈州立大学机械设计方面的荣誉退休教授,机械工程研究所硕士论文。具有较强的权威性性公司的董事长,Corvallis大街800号,美国俄勒冈州97330。电子邮件：ullman:本文由Autodesk资助;但是, 声明这些意见和结论的作者主要是基于他的工作。最近,并被认为是彻底的,全身心投入此项尖端研究的学者只有八个，他们大多集中在二维 1,15,17,18,22,23,24,25。作者没有发现他们关于影响参数系统的研究性文章被出版。在这样做的同时,他们总结了目前已知的和需要的研究东西。最后,探讨了计算机辅助设计(CAD)系统发展来支持增加用于开发的产品活动部分。这个学期的计算机辅助设计(CAD)强调计算机对于人类的设计师是一种援助,所以本文的主旨是中心设计者。它是根据这个活动紧紧依赖这个活动的设计师和他们开发的信息系统执行。在许多方面,这是以前发表的两个文件的一个更新（“绘制图纸在机械设计过程中的重要性”和“设计的发展史存在的问题、设计合理性以及设计意向系统”）。 最近的一些文章提出13个突出的问题需要解决去实现并且提出了一种去改进设计过程和有此引起的设计信息潜在的工程设计的疑问。这第一笔由基金会出资进行研究研究的论文是有五个具有不同的背景和经验的机械设计工程师发表的。他们每个人都会给于关于其中一两项的详细说明书，但是实际的机械设计中的问题的还是在现实的实践中遇到。当工程师们正着手于解决问题时，他们被强烈的要求去思考解决办法。他们的口头报告,图纸,手势被录像和录音大约能够持续6到10 小时。根据被誊写的这些录音资料数据获得一个关于这次设计会议的草案。每一个设计者都在他们解决问题的方法中绘制了几张图纸加以说明。所有的这些都是在图纸上。计算机辅助设计(CAD)系统没有被用于研究,因为没有设计者在他们的日常设计中使用计算机辅助设计(CAD)它的使用对一个已经复杂的实验来说会增加劳动强度。根据长达40多个小时的数据显示,15节关于每门科目的概念、布局、详细的典型设计被精选出来。这个草拟数据中其中的15个章节涵盖了这些数据的174数据单元。通过总结分析观测结果得出结论绘制成图纸并将将之运用于以下几个方面:1、档案的几何形态设计的2、设计师之间和设计师和生产人员之间的思想交流3、作为一种分析工具，通常, 不确定的尺寸和图上的公差进行开发4、模拟的设计5、作为一个完整性检查者，作为草图或者其他正在绘制中的图纸剩下的设计细节，这些对于设计师来说变得清晰。实际上,帮助建立一个完成剩下设计任务的议程6、作为一个设计师的短期记忆的延伸。设计师往往无意识地使用草图帮助他们记得的他们可能忘记的想法。1990年的图纸再次被发现并且是支持证明这些这个说法。此外,虽然受试者不使用计算机辅助设计(CAD)系统,但是结果却表明:1、计算机辅助设计(CAD)系统必须允许草图的输入。2、计算机辅助设计(CAD)系统必须考虑到设计师使用的多种的接口界面。这虽然不意味着更多的方法去定义一个交际圈，但是必须去寻找一个满足设计者需求的接口与计算机辅助设计（CAD）上的图像相交流。3、计算机辅助设计(CAD)必须能够识别域相关的因素及完成他们的实体。4、CAD工具需要能够管理约束(甚至)摘要和功能的限制)并且确保他们的满意,因为这是明显的,人类的设计师在对他的认知能力是有限。因此这篇文章表明,计算机辅助设计(CAD)系统已经成熟了并指出,至少在某种程度上有以上四种结论。然而,即使最新的系统是和理想的机械工程设计支持系统之间仍有很大的差距。这篇文章对最理想的系统被描述并对对其进展进行了讨论。2一个模型设计问题的解决对设计者来说或许在将来的某天能够戴上承载他（她）们理想和发展一种硬件陈述的“理想的帽子”。关于认知过程、计算机辅助设计(CAD),和快速成型的研究正在它的领域进行。这种现状意味这我们可以在我们头上陈述足够好的可担保的硬件将被开发出的概念。我们还可以假想计算机辅助设计(CAD)系统已经足够先进，能够很好的承载我们的想法和处理好零件和总体的发展变化。计算机辅助设计(CAD)系统的发展需要的到设计者认知工作的理解。只有这样想法设想和表达陈述直接的互通才有可能。所以去探究关于这个环节已知的知识，考虑人类问题的解决者和用数字表示的外部环境直接的关系是非常重要的。这组数据是基于纽厄尔和西蒙对模型的研究并被称为数字处理信息系统(IPS)。这些数据图表是关于设计信息的产生和储存的一个简单的“地图”。这些图标同时也展示了一个内部的，人类解决问题的环境(设计者的内心)和外部环境(设计者思想外的客观环境)。对于设计师来说,两个位置对应的是两种不同类型的记忆:短期记忆(STM)和长期记忆(LTM)。设计师外部的记忆方法有很多,有许多“设计存储地点”包括图形表示法、媒体例如：纸张和CAD工具,以及其它媒体，如：文本笔记、手册和各位同仁。每种记忆方式都有它运用于实际设计场合的背景和方法。短期记忆（STM）和长期记忆(LTM)特征细节是基于纽尼尔和西门的思维模型。 它的延伸已经被制成视觉图片以及他的影响已被编码。人们必须认识到这个模型在这所包含的内容虽然不完全同意认知心理学,但是他们足够安全提供为讨论CAD在机械设计中的作用讨论依据。2.1短期记忆短期记忆是非常快并且强大的。短期记忆的内容是我们意识到信息,也就是说,我们的有意识的心智。所有的设计操作(例如,视觉感知和图纸创作)是基于短期记忆（STM）的信息。不幸的是,STM容量能力有限。研究表明,它是限于大约七个认知单位或者大量的信息。在设计中,这些碎片是视觉图像信息的形式能信息、事宜的心理模式以及在CAD中表示想法的步骤，或者其他离散的信息碎片。虽然短期记忆的容量的有限,但它是一种处理时间仅是100毫秒的快速处理器。2.2长期记忆另一方面，长期记忆有本质上的无限容量，但是进入长期记忆的通路也慢了。进入长期记忆的通道也不是直接的。记忆也必须是一些提示或是基于短期记忆的信息检索策略引发。在设计中，有一部分内容被储存在长期记忆中。那些有相对比较简单的线索供引发记忆,因为,在任何时候,目前重要的设计部分都是在STM中并能充当长期记忆中的知识思想的指针。23外部环境,在这个试验（1990年）中,很明显许多绘画行为不习惯于用文字记载设计过程中的结果。但是绘制本省就是设计活动的一部分。如果这个画表可以将他们所做的这些呈现在他们脑海中,他们就可以按他们脑海中呈现的这样做而不用做草图,笔记和在纸上计算。因此,我们可以得出的外部环境常被用作长期记忆和短期记忆的延伸。在外部环境中运用媒体来提高设计者的认识能力是至关重要的。区分开媒体和人类的认知之间的关系密不密切是这篇文章的一个目标。本文所采用的方法首先是描述信息处理的类型,然后讨论设计师由外部环境影响所作出的举动。这些信息的类型和举动对于理想的系统能力来说是成熟的。每节以最理想的工程设计支持系统应该具有怎样的功能为内容开始。其余次要的信息遵循这些内容.其次是关于记事本、二维CAD系统,固体模型系统、参数系统,以及其他支持工具怎样满足理想要求的描述。这样使各分部得到改进的机会。Toward the ideal mechanical engineering design support systemDavid G.UllmanAbstract This paper details the progress toward the development oftheidealmechanical engineering design support system.It attempts to look at the gap between the needs of a mechanicalengineerandwhatis currently available onCAD systems Since the tern：CAD emphasizes that the computer is an aid to the human designer，this paper is designer centric it is based heavion the activities performed by designers and the types ofinformation developed by then：Seventeen goals for the ideal mechanical design support system are listed These are directed at the types ofinfor mation developed during the design process and the activ ities used to develop them For each of the seventeen，background information，the current state of the art，and opportunities for future development are itemized Keywords Mechanical engineering design，CAD，Support system 1 Introduction This paper summarizes the progress made toward the development of the ideal mechanical engineering design support system For nearly 30 years，computer aided de sign(CAD)systems have been touted by their developers as systems that support engineering designers developing products CAD systems have had a major impact on how design is accomplished in the workplace This being said，there is amazingly little ibrmal research on the effects of these systems on the designers and on the final productsThis paper presents a structure for discussing these effectsIn doing so、lt summarizes what is known and what needs co be studied Finally、it discusses how CAD systems have evoh,edto supportincreasingportions ofthe activitiesthat are used to develop products. The term CAD emphasizes that the computer ls an aid to the human designer，so this paper is designer centric it is based heavily on the activities pertbrmed by designers and the types ofintbrmation developed by them in many ways，this is an update of two earlier papers，The importance of drawing in the mechanical design process”29 J and“issues critical to the development of design history，design ratio nale and design intent systems”【311 The latter paper developed 13 outstanding issues that needed to be resolvedto realize the capture and query ofengineering design intormation as a potential lor lmprovmg the design processand the reuse ofdesign Intormation. The tbundation for the first paper was the study of the marks made on paper by nve mechanical design engineers of varying backgrounds and experience They were each given the initial specifications tbr one of two tirly simple， yet realistic，mechanical design problems taken from professional practice The engineers were requested to think aloud as they soh,ed the problems Their verbal reports、drawings，and gestures were video and audio taped for aperiod of6 10 h The taped data were then transcribed to obtain aprotocol”of the design session Each designer made numerous drawings during his or her solution of the problem A11 0fthesewere on paper CAD systemswere not usedinthe studgbecausenone ofthedesigners usedCADln their daily practice，and its use would have added another variable to an already complex experiment. From the more than 40 h ofdata taken，15 sections were selected that represented typical conceptual，layout，detail and selection design for each subject The 15 sections of protocol data consisted of 174 rain of data The data were analyzed to explore the observations that drawings areusedto：1 Archive the geometric torm of the design2 Communicate ldeas between designers and between the designers and manufacturing personnel3 Act as an analysis tool Often，missing dimensions and tolerances are calculated on the drawing as it ls developed4 Simulate the design5 Serve as a completeness checker As sketches or other drawings are being made，the details left to be designed become apparent to the designer This，in ett)ct，helps establish an agenda of design tasks leL to accomplish6 Act as an extension of the designers short term memory Designers often unconsciouslv make sketches to help them remember ldeas that they might otherwise torget The 1990 paper refined and supported these observa tions AdditionalIv，although the subiects did not use CAD systems，the resuhs suggested that：1 CAD systerns nlist allow tbr sketching lnput2 CAD systerns nlust allow for a variety of Interfaces tbr the designer This does not mean more ways to define a circle、but an eftort to match the interface and the im age on the CAD system to that needed by the designer3 CAD systems iiltlSt recognize domain dependent features and treat them as entities4 CAD tools need to be able to manage constraints(even abstract and tkmctional constraints)and ensure their satistaction、as it is evident that human designers are cognitively limited in this abilitySince that paper was written，CAD systerns have matured and have addressed、at least to some degree、all南ur of the conclusions iIowever，even the most recent systems are a ong way tbom the ideal mechanical engineering design support system In this paper，the ideal system will be described and progress toward this ldeal discussed2A model of design problem solvingit may someday be possible for a designer to put on a thinking cap”that can take his or her thoughts and de elop a hardware reDresen【atlon Research on under standing cognitive processes，CAD，and rapid prototyping ls certainly moving ln that direction This ideal implies that we can tbrmtflate concepts Jn our heads that are sumciently well tormed to warrant hardware It also as sumes that CAD systems are suflicientlg developed to take our thoughts and manage the evolution of parts and as semblies CAD system development will require an tin derstanding of the cognitive workings of designers so that the transition tbom thought to representation is possible To explore what ls known about this link、consider the relationship between the human problem soh,er and the external environment shown in Fig 1 This figure ls based on the model developed bv Newell and Simon20l and ls called the information processing system(IPS)The figure is a simplemapofwhere information about the design is developed and stored The figure shows an internal，human problem solving environment(inside the mind of the designer)and an external environment(outside the mind of the designer)Within the designer，two locations correspond to the two different kinds of memory：short term memory(STM)and long term memory(LTM) External to the designer，there are manydesign storage locations”including graphical representation media such as pieces of paper and CAD tools，as well as other media such as textual notes，handbooks，and colleagues Each location has certain properties that affect how it can beused in design Detail on the charac Leris【ics of the STM and the LTM ls based on Newell and Simons model20 J Extensions have been made to it for visual imagery【1 l，12，13 J and effortshave been made to codilit【21 it must be realized that the contents of the model given here are not folly agreed to in the cognitive psychology community，but the),are cer tainly secure enough to provide a basis for discussing the role of CAD in mechanical design21Short-term memory Short tern：memorg ls verv fast and powerful The contents of the STM are the information we are aware of,that is，our conscious mind All design operations(。g，visual perception and drawing creation)arebased oninformation in the STM Unfortunately，the STM has limited capacity Studies show that it is limited to approximately seven cognitive units or chunks of information During design， these chunks are visualimages offorn：s，information about fonction，mentaln：odels offit，stepsto represent anideain a CAD system，or other discrete pieces of information Although limited in capacity，the STM is a fast processor with processing times on the order of 100 nls4122Long。term memory The long term memory，on the other hand，has essentially infinite capacity，but access is slow Access to LTM is also not direct Memories rntlSt be triggered by some cue orretrieval strategy based on intbrmation in STM During design，parts of the design are stored in LTM These are relatively easy to cue because，at any time，currently in： portant parts of the design are in the STM and can act as pointers for the knowledge in the LTM23ExternaI environmentin the experiments run in 1990291，it was clear that many drawing actions were not used to document the results of the design activity but were part of the design process itselg if the subjects could bare performed these activities in their heads they would have done so without making the sketches，notes，and calculations on paper Thus，it is concluded that the external environment ls often used as an extension of the STM and LTM it ls critical that the media used in this environment support the designers cognition Itemizing the match or mismatch between the media and human cognition is one of the objectives of this paper The approach taken in this paper is to first describe the types otinformation managed(Sect 3)and then discuss the activities performed by the external environment support ing the designer(Sect 4)The types of information and activities are developed in terms of the capabilities of an ideal system Each subsection begins with statements about what the ideal engineering design support system should do Supporting information follows these statements Next， there is a description of how paper and pencil，2 D CAD systems，solid modeling systems，parametric systems，and other support tools meet the ideal Each subsection concludes with 0DD0r【unl Lles for lmprovement3Information managed by an ideal mechanical engineering design supposystemMechanical engineers manage a broad range of informa tion in this section，the X arious types of information will be itemized，beginning with the most basic and progress ing to the most demanding31Form，fit，and funionThe ideal engineering design support system should：1 Allow designers to work I?om desred Junction to the other types oj lnlornlation2 Allow designers to flexibly work on the architecture, shape,f，and function of parts and(zss0川bliesThe mechanical design community has traditionally thought in terms of form，fit，and function Figure 2 shows the interplay among these basic types of information that describe the product being designed Generally，the reason for the obiect being designed is to fulfill some desired functions The form of the parts and assemblies，and the fit between them，depend on the desired function of the product Thus，the ideal system should allow the designer to work ffonl funotion to fornl and fit The termformactually implies both the architecture and the shape of parts and assemblies(Fig 3)The term architecturehas come to mean the skeletal structure that maps the function to the form Architecture is thestick figure”that can be easily manipulated and changed before the shape is refined Shape implies the geometry that adds hodV and detalt to tne arcnltecture utten deslgners il-st develop the general architecture of the object being de sidned then add detaits about shape an(1 fit Where wP n憎today Engineers generdly work from the ftnlction of a systel、to the architecture of an assembly，to the shape of parts iaunction occurs primarily at the con nections or fits between the parts ln an asselnbly ill other wor(1s mnction ls devdopetl ln assembies lhis belng said，CAD systems have primali Ly supported the forln or geometry devetopnlent ot parts Paper and penciattms easy sketching of architecture with stick fiures and their evoution to conlponents Paper and pencil atso supportsimited function nlodeling through sketchinl4 actions that show lnotion or flow ln assemblies9、14Both 2 D CA3 systems and paper and pencil are fimited to simple input of line seglnents to represent the edges of COlnponents Solid naodeing systelns are stilt Colnponent oriented even though they support the representation of edges，surflces，and sotids Parametric systems gl eaflylniprove(1 the lllodeilll4 of fornl with the Iimlted ability to modeI ntd asblles Future systelS need to help the designer visualize fllnction before geometry is fully defined Computer sys tenls are allowing better representation of fllnction，。g， kinelnatic，dynamic，fluid flow，and virtmd reality systems With the continued development 0f COlnputer support tools the ability to work fr0111 fllnction to form will tlnl_e呲v0Lve CA3 systems to date have been part driven Parts are developed and then fittecl toether to make an assembly Ihe contributions oftheIayOtlt dlawinK have not beenwe1 supported Paralnetric systems have begun to lOVe to a nlore natural flow，but parametric nlodeing requires the designer to PIan ahead of time the geometric constraint rekltionships that define the part,Mally parametric sys tells refer to the orderlng of the constraints as the design intent Ihis methodooD，while lnoving toard the ided， does not well support the designer as the pallllillg needed adcls burden and the orderinnlay not be known initiflly and lnay change during the deveoplnent Further，“design intent”as used ill parametric systems is tooimiting(see discusslon of deslfan Intent belowlOpportunI Extend CAD systems todow the designer to develop the architecture of parts and assembies to mliltl neede【l mnotion fhey nltlst atlow the designer to work fr0111 the architecture to the shaDe an(1 fit of the conlpo nents themselves lhis wi1 require workinl4 wlth abstrac tions of parts an(1 asselnbIies as we1 as buildlng the geometry of objects from their architecture and interfaces with other objects32Material and manufacturingThe ideal engineering design support system should： 3 Integratethemanzcturing and assembl),practices and (oltlltl01,1 material usage oy the compan),or its vendorsOne of the cornerstones of concurrent engineering is the integration of the development of the product and the processes that support the product Key among these processes are those used to manufacture the parts and assemble them These activities also depend on the selec tion or development of the best materials for the product Thus，as shown in Fig 4，the basic tbrm(architecture and shape)，fit，and fonction need to be tied to materials，manufacturing，and assemblyWhere we nre todi9,Currently、there are systems that aid in the development of injection molds and sheet metal parts flowever，for most manuthcturing and assembly methods，only text notes have supported this nongeo metric lnformationOpportuMt),Extend CAD systems to provide the designer with intbrmation about anticipated material and manul；acturing methods This needs to be personalized as eachcompany and vendor has certain materials and manutacturing and assembly methods that are standard and wellknown Knowledge about these should be easily availableto the designer to aid in the development of parts andassemblies33CostThe ideal engineering design support system should：4 Support the engineer so she or he is ctlv(re。l the eect。f each Jblture change 01,1 costit is generatedThe cost to make the object being designed is not a part 0f its description，yet it is a major factor in all design considerations It is shown in Fig 5 as closely tied to the material used and the manufacturing method and through these indirectb to the ftinction and fornl Often there is a disconnection during the design process between drawingwhat is being designed，but the limitations and targets on it As such，it is critical information As shown in Fig 6，there are requirements on atthe other types of infor mation previously discussed Traditionally，engineers have done a poorob at developing requirements tbr products Wherw。(It6tod9,One of the best practices current, used to deveop requirements in industry is quality func tion depoyment(QFD)7，321 Many companies use the results of this method to direct,feed requirements to the development of components and assembies Admittedly， many of the requirements deveoped with the QFD are for funotion；however，there are aways many constraints on both function and geometry that drive the development of parts and assembies To date，this is not we1 integratedwith CAD systems Stauffer【26 J showed that as the design process noves from conceptual throughayout to detail design，the source of constraints moves from those imposed from outside the control of the designer to those based on previous design decisions This impies that not only shoud requirements like those deveoped using QFD type methods be integrated，but the reasoning behind earlier decisions also needs to be supported This witbe furtherdiscussed in the seclion on design intent fSect 3 61Opportunity CAD systems need to integrate requirements and constraints into the deveopment of parts and as semblies35Issues and plansThe ideal engineering design support system should： 6 Support the development，Jbllowing,and updating plans7 Support the lmtrlagemenl issues not phtnned JotWhereas atthe types of information described so ihr represent the artifacts being designed and the require ments on them，the lotowing types of information repre sent the process through which the artifacts are developedThe importance of the process has been a concern ln in dustry since the earh 1980s and an area of research since the mid 1980s The tie between product and process is a maior part of concurrent engineering in the late 1990s， this concern became prominent with the development of interest in integrated product and process development (IPPD)，the successor to concurrent engineering Traditionally，the product design community addresses the design process ln terms of the tasks to be completed in dexeloping a new product These tasks are focused on specific design lssues that can be planned tbr in the de velopment of the product However、many issues arise duringthe design ofa productthat can notbe plannedtbr This ls especially true during the development of newproducts or during the use of new technologies Figure 7 shows that lSStles and plans address all types of require merits and product information issues or tasks in product design require the designer to develop new lnformation 0ne of the first experiments aimed at unders【anding human Intbrmation processing during design tasks【27 J showed that over two thirds ofthe strategies used by the design engineers during the dexelopment of new products were searches through design space Searches imply that there is a range of potential sohltions to every issue and that the designer must look at several of these ahernative solutions to develop one that ls satisfactory Search strategies are well studied by the artificial intelligence community Three types of strategies defined by computer scientists and identified in the cognitive study weregenerate and test”， generate and improve”、andmeans ends analysis”In each search type，the designer develops and refines the alternatives and compares them to the requirements until son2e satisfactory choice has been made ln the time vailable Based on these findings、in order to support designers，systems must not only track the completion of planned work，but must also support the developmentand management of multiple ahernatives for all issues addressedWhere we nre todi9,Project planning and change n2an agement has always been a large part of engineering management Product data management(PDM)systems have made large strides toward integrating the actual de sign work with what was planned These systerns are still maturingOpportunity Computer support tools need to continue to evoh,e to assist the engineer in developing the product and the process in an integrated fashion36IntentThe ideal engineering design support system should manage all the previously defined types ofinformation in a database pit,s：8 Support znfoHnlion about proble ms olisslles addressed t。g?business isslles?planning issues?and artiJact design SSlies)9 Support lHiormation about a1glltllenls jbl01against alternatives f。g，qualitative discussion，quantitative anal),sis,rules,and standards)based 0n requirements10 Support lnibrmation about the de cisions reachedA number of authors have explored the concept of re cording adesign history”Nearly 15 years ago，Mostow stated that there was a growing consensus in the artificial intelligence community that，an idealized design history is a useful abstraction of the design process”【191 In thelate 1980s，this author and his colleagues built an object oriented database that organized information about the design of a simple mechanical system5,6，301 This dat abase could be queried about the evolution of constraints and the eftct ofdecisions on the artit3cts being developed Since Mostow，the artificial intelligence community has been active in developingdesign rationale”systems A workshop held in 1992【16 J defined the term rationale at an explanation that answers a question about why an artifact is designed as it is”Baxter【31，in his thesis，refines the definition：Design rationale：an information structure that justifies how the implementation(consequences of the design selectionsl satisfies its specification”This defini lion emphasizes the structure of the design inlbrmation and tracking the relation of decisions back to the specifi cations Another community，which is organized around devel opment of the STEP IV standard，uses the termdesign intent”Their use of design intent refers to the cause and effect relationships among produc【data In an unpub lished document，a STEP IV researcher s rates：“Generally， the term intent means the purpose or plan for perlbrming activities During product design，these activities trans form a set of requirements to the final sDecincaflons for production In a basic sense、the intent is the blueprint tbr the evolution of the requirements Into the production sDeclncatlons This blueprint not only has intbrmation about the development of the geometry，but also on the evohltion of the product function and behavior，the rationale underlying design decisions and the lnfluenceof business activities in the CAD comnlunity、the term Intent ls used to de scribe the ordering of geometric constraint equations in a parametric system This ordering defines the geometric dependency needed by the system ln order to make changes and is not necessarily the cognitive ordering that was tollowed by the designer in the development or relinement ol the part or assembly Finally、in some business literature、the term corporate memorg ls used to emphasize the feeling that the inlormation managed is beyond that associated with the traditional artit：act as 1t lncludes business information as well in the resuhs of the first CERC Workshop on Enabling Technologies【21 J，the discussion on corporate memory was in terms 0i design histories and rationales Supporting full design intent intormation may even be more complex than storing what has been generated during design Gruber8 l claims that it ls not sufficient us【to capture、store、and retrieve the same lnformation lie observes：“rationales(intentsl are constructed and lnferred厅onl stored lnformation rather than as cornplete answers”in other words、design intent systems may have to answer questions that reqmre inIormation dillerent than that captured The questions that arise during query may not be answerable with only the lnformation of the original design This implies that the data must be strut tured during capture or storage so that answers can be developed to needed questions Design intent systems must record and manage inlor mation that shows why and how a decision was made about each issue addressed As shown in Fig 8，a design intent system needs to support all the types ofinformation previously developed and store this information in an easily indexed databaseWhere wetl,e tod9,To capture，store，and allow query of the design information is a challenging research area31 J To a limited degree，PDM systems are beginning to man age some of the needed information ttowever，these sys terns tend to be oriented toward lnformation that ls well refined and not evohltionary information Further，these systems do not have a formal mechanism for managing information about argumentation leading to decisions Parametric and variational systems allow for design re use Thus，it is easy to find the answer to queries about the effect of form changes and sensitivities In this manner， these systems have captured some of the intent behind the lnformation modeled One limitation of these systerns isthat they can only be used with geometric decisions and decisions about behavior that can be geometrically mod eled Additionally，these systems do not model the actual decision structure They only record the order initially anticipated to give the system necessary geomemc tea soning If the value of a parameter(ie，the length of a part)is queried，parametric systems will give information about this lengths dependency on other dimensions of the part ilowever，it does not give the rationale for the rela tions or the arguments for the current vahle A number ofCAD companies havebegunto offer design notebooks that allow the designer to keep notes about the exoMng products These notebooks are the first step in supporting needed actMties and information manage ment ilowever，it is believed that additional structure and indexing will be necessary to achieve useful design ratio nale support systems Opportunity There is great potential in this area for im proving the design process and the reuse of information CAD systems have begun to capture and manage the needed information4Ideal mechanical engineering design suppo system activitiesThere are seven activities that the external environment provides to the designer regardless of the information managed and media used These activities serve as dimensions for measuring the external environments ability to aid the designer The activity discussion is based on that presented in Issue s Critical to the Devdopment oy Design History,Design Rationale and Dsign Intent stems【31 J41Suppoinformation developmentThe ideal engineering design support system should sup port the maniptflation of the difl)rent types ofinformation and： 11 Match the speed可the short term 111elliot),during 10rmalion development effect relationships among product data in an unpub lished document、a STEP IV researcher states：“Generally、 the term intent means the purpose or plan ior performing activities During product design，these activities trans torm a set of requirements to the final sDeclncatlons for production in a basic sense、the Intent is the blueprint ibr the evolution of the requirements into the production sDecinca【ions This blueprint not only has lnformation about the development of the geometry，but also on the evohltion of the product funotion and behavior，the rationale underlying design decisions and the influence of business activities In the CAD community、the term Intent 1s used to de scribe the ordering of geometric constraint equations in a parametric system This ordering defines the geometricdependency needed by the system ln order to make changes and is not necessarily the cognitive ordering that was followed by the designer ln the development or refinement of the part or assembly Finally、ln some business literamre、the term corporate memory is used to emphasize the feeling that the information managed ls beyond that associated with the traditional artifact as it includes business intbrmation as well In the results of the first CERC Workshop on Enabling Technologies21】，the discussion on corporate memory was in terms of design histories and rationalesSupporting扎11 design intent infbrmation may even be more complex than storing what has been generated during design Gruber81 claims that lt ls not suincient He observes：“rationales fintents)are constructed and lnferred厅Onl stored Intormation rather than as complete answers”In other words、design intent systems may have to answer questmns that reqmre inlormation dillerent than that captured The questions that arise during query may not be answerable with only the lnformation of the original design This implies that the data must be strut tured during capture or storage so that answers can be developed to needed questions Design mtent systems must record and manage inlor mation that shows why and how a decision was made using the CAD system forces the subiects to concentrate on the use of the CAD dialog and to neglect the design taskThis resuh held regardless of lncreased CAD experience Although this research is dated、the result is not During the use 0f CAD systems、icon and menu selecting add unneeded steps to creating an image A current best selling parametric system has Fflenus Lp to five levels deep that are needed to do many operations These steps add an extreme cognitive burden to both the novice and expert user One part of the cognitive research discussed ln the in troduction of this paper291 tocused on the marks on paper designers make during the design process In the protocol sections studied，the average length of time to make a mark on paper was 7 3 s with a standard deviation of 7 8 s The 363 iflarks on paper studied were divided into“draw”marks and“support”marks These are fur ther refined into“sketch”and“draft”marks and“text”、 dimension”、andcalculate”marks respectivelv Thus、 there are five types of marksonpaper：Sketch：Drawings 0f如atures made疳eehand Accounts tbr 48of marks on paper Sketching on paper is not the same as sketching on the computer using a CAD sVsremDraft：Drawings made with mechanical devices 24Text：Letters，words，or numbers that are not part ofa dimension on a drawing and not part ofa calculation 9Dimension：Dimensions or dimension lines on a draw lng feither a sketch or a draft)14Caleulate：Equations and answers to calculations Combines constraints or design proposals to derive new lnformation 5There was some debate as to how to difl)rentiate between sketch and dran marks There are nv0 measures Lo con sider：(a)the use ofinstruments and(b)whether or not the drawing was to scale Consistency with traditional college graphics texts suggests that the criteria should only be theuse ofinstruments as defined above A11 ofthe subjects had instruments at hand iIowever、some subiects chose to make their scale drawing厅eehand it would seem that they that it was easiest not to use the instruments The differentiation between sketch and draft is made even clearer by considering when in the design process the drawing was made When the subjects were trying to conceptualize the design，100of the drawings were sketches Later in the design process，during the layout and detail phases、this drops to 52as softie of the sub 1ects used instruments to draw their refined design while others continued to sketch Over 67of the drawings were sketches Many of these sketches could have been made using drafting equipment or on a CAD system But、with the average length of these sketching actions less than 8 s、the use of instruments or CAD could have slowed the drawing action to the point that the cognitive problem soh,ing would be impaired Thus，even the use of simple drafting lnstruments added sumcient cognitive burden that they were not used during conceptual designOpportunity,A goal of CAD vendors shotfld be to develop systems that work at the rate of cognition Such systems would have virtually no mentls A research project with this goal was undertaken in 198910 J The resuhing sys tern could int)r complex geometry solids from simplesketching motions Although this may not be viable for a commercial system，five layers of menis are not viable for a system that matches human abilities42Capture，archive，and query informationThe ideal engineering design support system should：1 3 Capture all types。f inoformation with n singlentry1 4 A rchive all the 9pes on 30rmation so that design intent c(1n be readiO,recowred1 5 Support designer query,about the design intent jbr all types oinlormationThe three activities necessary for a design history or de sign intent systern are the capture，archiving，and query ot design information Thus，these three are discussed to gether Design information is captured in the external environment This lnformation may be discarded as with traditional paper layout drawings，white boar
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