首页 人人文库网 > 图纸下载 > 毕业设计 > CADCAM技术在摩托车护片锻模设计中的应用【6张CAD图纸+毕业论文】
6-设计说明书-19898字-48页.doc

CADCAM技术在摩托车护片锻模设计中的应用【6张CAD图纸+毕业论文】

收藏

压缩包内文档预览：(预览前20页/共49页)
预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图 预览图
编号：435860    类型：共享资源    大小：2.03MB    格式：RAR    上传时间：2015-05-26 上传人：好资料QQ****51605 IP属地：江苏
45
积分
举报
举报 版权申诉
版权申诉 word格式文档无特别注明外均可编辑修改；预览文档经过压缩，下载后原文更清晰！ 立即下载
关 键 词：
cadcam 技术 摩托车 锻模 设计 中的 应用 利用 运用
资源描述：

【温馨提示】 购买原稿文件请充值后自助下载。

[全部文件] 那张截图中的文件为本资料所有内容，下载后即可获得。


预览截图请勿抄袭，原稿文件完整清晰，无水印，可编辑。

有疑问可以咨询QQ：414951605或1304139763


摘要：曲面类零件在制造业中处处可见，尤其是模具制造业。传统的设计制造方法是工程图、模线、样板、标准样件等工作方式，生产准备的周期长，制造精度低，生产效率也是低下。随着计算机技术在模具制造业中应用的不断发展，数控加工能力得到了大大提高，模具的设计与制造技术达到了空前的发展。模具CAD/CAM技术已成为模具行业革命化的标志。适应CAD/CAM技术的发展，改变传统的设计与制造方法是模具制造业的发展的方向.

本设计是CAD/CAM技术在锻模曲面加工中的应用。包括两大部分：一是摩托车护片模具的设计；二是模具型面的造型与数控仿真加工。在Mastercam 8.0环境下利用CAD功能进行摩托车护片模具的实体造型，利用CAM功能进行模具刀具路径的编制、模拟加工，并通过后处理生成NC程序。期望通过此课题的研究，能够提高自己对CAD/CAM技术在模具制造业中应用的重要性的认识。


关键词： CAD/CAM技术  实体造型  仿真加工


Abstract： It is well known that surface parts can be seen everywhere in the  manufacturing , especially in the mould manufacturing . The traditional design and manufacturing processes are the engineering drafting , lofting , template making , standard samples , etc. , which have the shortages of long production preparation period , low processing accuracy and production efficiency . With the developing of the computer technique’ application in the mould manufacturing , NC machining capability has been enhanced greatly ,and, the design and manufacturing technique of the mould has obtained enormous progress at the same time . The CAD/CAM technique has become the revolutionary sign in the mould industry . To be suitable for the tendency of CAD/CAM technique’ development and meet the requirement to change the traditional design /manufacturing modes are the developing direction of the mould industry .

This project is about the application of the CAD/CAM technique in the wrought mould surface processing . It contains two parts : one is about the mould design of the motorcycle jacket and the other is about the numerical control simulate process of the mould surface . Under the environment of Mastercam 8.0 , I will sculpt the mould of the motorcycle jacket using the CAD function , and then , I will weave the tool route , simulate processing and create the NC programme via the back disposing using the CAM function . And at last , I hope I can improve my cognition to the significance of the CAD/CAM technique’ application in the mould industry by the study of the task .


Keyword:  CAD/CAM technique  sculpt  simulate processing  


CAD/CAM技术在摩托车护片锻模设计中的应用

1  序 言

1.1课题研究的目的及意义

1.1.1模具CAD/CAM的研究目的

模具CAD/CAM技术是改造传统模具生产方式的关键技术，它以计算机软件的形式为用户提供一种有效的辅助工具，使工程技术人员能借助计算机对产品、模具、成形工艺、数控加工及成本等进行设计和优化，从而显著缩短模具设计与制造周期，降低生产成本，提高产品质量。模具是工业产品生产用的工艺装备，主要应用于制造业和加工业。它是和冲压、锻造、铸造成形机械，同时和塑料、橡胶、陶瓷等非金属材料制品成型加工用的成形机械相配套，作为成形工具来使用的。模具一般分为两个部分：动模和定模，或凸摸和凹模，它们可分可合。分开时装入坯料或取出制件，合拢时使制件与坯料分离或成形。在冲裁、成形冲压、模锻、冷镦、压制和压塑过程中，分离或成形所需的外力通过模具施加在坯料上；在挤压、压铸和注塑过程中，外力则由气压、柱塞、冲头等施加在坯料上，模具承受的是坯料的胀力。由于其加工效率高，互换性好，节约原材料，所以得到很广泛的应用。

1.1.2模具CAD/CAM的研究意义

随着功能强大的专业软件和高效集成制造设备的出现，模具CAD/CAM能实现制造和装配的设计、成形过程的模拟和数控加工过程的仿真，还可以对模具可制造性进行评价，使模具设计与制造一体化、智能化。此次设计是锻模的设计及应用。锻模是模锻时使坯料成形而获得锻件的模具。锻模的设计方法和生产实际是紧密相关的。将金属坯料加热使其具有较高的塑性，然后放在锻造设备上，利用通用工具或专用模具对其施加压力，迫使其发生塑性变形并流动，从而获得所需的锻件，这种压力加工生产方法称为锻造工艺。而锻模设计就成了锻造工艺中很重要的组成部分。 模具要承受锻锤的高速冲击或重负载的冲压下，在使用过程中常处于急冷、急热和冷热交变状态，因此模具材料应具有很高的强度、韧性和耐磨性。                                                                                                                                                                                                                                                                                                                                                                            

1.2国内外研究现状

模具CAD/CAM是在模具CAD和模具CAM分别发展的基础上发展起来的，它是计算机技术在模具生产中综合应用的一个新的飞跃。模具CAD/CAM是改造传统模具生产方式的关键技术，是一项高科技、高效益的系统工种。它以计算机软件的形式，为用户提供一种有效的辅助工具，使工种技术人员能借助于计算机对产品、模具结构、成形工艺、数控加工及成本等进行设计和优化。

模具CAD/CAM的发展状况符合通用CAD/CAM 软件的发展进程。目前通用CAD/CAM 软件的发展现状如下:CAD技术经历了二维平面图形设计，交互式图形设计、三维线框模型设计、三维实体造型设计、自由曲面造型设计、参数化设计、特征造型设计等发展过程。近年来又出现了许多先进技术，如变量化技术、虚拟产品建模技术等。随着互联网的普及，智能化、协同化、集成化成为技术新的发展特点，使CAD技术得以更广泛的应用，发展成为支持协同设计、异地设计和信息共享的网络CAD。

我国 CAD/CAM的研究应用与工业发达国家相比还有较大差距，主要表现在：（1）CAD/CAM的应用集成化程度较低，很多企业的应用仍停留在绘图、NC编程等单项技术的应用上。（2）CAD/CAM系统的软、硬件均依靠进口，自主版权的软件较少。（3）缺少设备和技术力量，有些企业尽管引进CAD/CAM系统，但其功能没能充分发挥。

1.3 本课题研究内容

此次设计是Mastercam软件在摩托车护片型面加工中的应用，它包括两部分内容，即：一是摩托车护片模具的设计，二是摩托车护片模具型面的仿真加工。这是CAD/CAM技术在锻模生产中的应用实例。摩托车护片是摩托车前部用于穿接电缆的零件，起保护作用，它的作用决定了它的结构特征，通孔多槽，相应的模具设计虽然简单，但是比较精湛。摩托车护片型面的加工，因为Mastercam软件的应用，大大的提高了模具精确度和生产效率，缩短了生产周期，淋漓尽致地发挥了CAD/CAM技术在模具生产中的作用。

由于本人水平有限，本论文中必然存在许多缺点和不当之处，敬请老师批评指正。



2  摩托车护片模具的设计

2.1零件结构和工艺分析

2.1.1零件结构分析


               图2-1 摩托车护片零件图

如图2-1的零件图，该零件的材料为热轧钢35#钢。其作用是：保障电缆线安全通过，起保护作用，在整个摩托车构造中起着至关重要的作用，所以其中部都是槽，并且穿透整个零件，光从其形状上看，该零件体积小，只是一个有着多个不同形状槽的薄壁零件，而且圆角较多，但是形状不是特别的复杂，精度要求也不是很高，可以通过锻造一次成形，节约原材料和节省加工时间，降低成本。同时，材料通过锻造，可以使其内部组织细密，碳化物分布和流线分布合理，从而能达到改善热处理的性能和提高模具的使用寿命。

2.1.2 零件工艺分析

   锻模的种类很多，按模膛数量可分为单模膛模和多模膛模；按制造方法可分为整体模和组合模；按锻造温度可分为冷锻模、温锻模和热锻模；按成形原理可分开式锻模和闭式锻模；按工序性质可分为制坯模、预锻模、终锻模、弯曲模等。通常锻模是按锻造设备来区分，可分为胎模、锤锻模、机锻模、平锻模、辊锻模等。

模锻件是完全在锻模型槽中进行锻压成形的锻件，各种各样的锻模是为了满足各种各样模锻件的需要。结合本设计中的零件特征和要求及相关标准，该零件为普通模锻件，并且为长形锻件中的一类。

摩托车护片一般为批量生产，根据其结构特点和要求及各种分类标准，本设计采用开式单型槽热模锻，并且选用热锻模曲柄压力机进行模锻。

   根据以上分析，确定该模锻件的模锻形式和模锻条件等，那么，本设计的目标之一即锻模型槽设计(锻模设计)可以进行了。



内容简介：
南昌航空大学科技学院学士学位论文计算机辅助设计与制造CAD/CAM是表示计算机辅助设计和计算机辅助制造的专业术语。它是一种使用计算机完成某些设计和生成功能的技术。在生产企业里，人们通常把设计和制造是为两项有着明显不同职能的分工，而这项技术正朝着设计与制造的更大程度一体化方向发展。最终，CAD/CAM将会为未来的计算机集成工厂提供技术基础。计算机辅助设计（CAD）可定义为运用计算机系统对设计的创意、修改、分析或优化予以辅助。这些由硬件和软件构成的计算机系统，用于完成用户公司要求的特定设计功能。CAD硬件通常包括：一台计算机，一个或多个图形显示终端，键盘和其他外围设备。CAD软件包括各种计算机制图程序，这些程序便于用户公司完成设计职能，如：零部件的应变分析，机构的动态响应，热传输计算和数控零件编程。由于用户的生产流程、制造工艺和销售市场方面的差异，应用程序的配置也将因用户而异。这些因素均导致对CAD系统要求的差异性。计算机辅助制造（CAM）可定义为通过直接或间接与厂家生产资源相适应的计算机界面，使用计算机系统来规划、管理和控制制造工厂的运行。正如定义所表示的那样，CAM应用程序可分为两大类：1. 计算机监控程序；2. 制造程序。二者之间的区别是理解计算机辅助制造的基础。计算机辅助制造的应用程序，除了为监控制造过程而直接使用计算机界面的应用程序之外，还包括在工厂生产运行过程中由计算机提供支持的间接应用程序。在这些应用程序中，计算机并不直接与制造过程相联接。相反，在脱机状态下，计算机可用来提供计划书、进度表、预报、指令和使厂家生产资源管理更加有效的信息资料。计算机和制造过程间的关系如下图所示。图中虚线用来说明交流和控制处于脱即状态下，需要人来完善界面。目前，CAM的应用需要由人来为计算机输入程序，解释计算机的输出，并采取所要求的措施。生产操作 计算机 处理数据 控制信号 CAM用于生产支持Notes:1. CAD(computer-aided design) 计算机辅助设计2. CAM(computer-aided manufacturing) 计算机辅助制造3. computer monitoring and control 计算机监控4. manufacturing support applications 生成支持应用软件5. peripheral equipment 外围设备（外设）6. computer graphics 电脑制图什么是CAD/CAM软件？许多刀具轨迹是简单的但太复杂和昂贵以致于人们很难制造，对于这种情况，我们需要在计算机的帮助下来作数控部分程序。CAD/CAM最基础的概念是，我们可以用计算机辅助设计系统在计算机上画出工件的几何形状。几何形状一旦完成，我们就可以用计算机辅助制造系统根据CAD的几何形状，生成数控机床的刀具轨迹。利用CAD绘制所有路径对数控加工的路径如下：第一步：利用CAD绘制几何图形已被定义这种工件包括型腔加工。对于这种型腔加工很可能将花几个小时去制造代码。然而，我们能够利用CAM程序去创造NC代码在每分钟内。第二步：接着，这个模型就被输入到CAM模块中。然后，我们就选择合适的几何形状并定义要生成的刀具轨迹类型，在这个例子中就是一个型腔。我们一定也能够让CAM系统如刀具的使用，材料的类型，进给量，切屑深度等信息。第三步：CAM模型证实保证刀具轨迹的正确性。如果发现了一些错误，最简单就是在某个位置上加以改正。第四步：CAD/CAM模块最终产生的是NC代码。通过模型的后处理则可以生成适用于特定CNC控制器的NC代码。我们取字体的首字母即CAPP，它代表了计算机辅助程序。CAPP是使用计算机辅助在数控刀具轨迹中的应用。然而，CAPP从来就没有真正获得广泛的流传和接受，而且至今我们很少听到这个项目。取而代之的是在更多的市场上使用CAD/CAM，使用计算机的思维来帮助生产NC程序。不幸的是，因为CAM是一个整体技术与制造技术和自动化技术有着关联的不仅是软件，而且使用CNC机器工具。描述CAD/CAM组成及功能CAD系统包括CAD设备及CAM设备每个都有许多功能元件。它们将在短时间内扫描这些元件目的是为了了解其工作的整个过程。1. CAD模型系统的CAD部分用于生成可作为CAD模型的几何形状。CAD模型是工件几何形状的电子描述，她在数学上是十分精确的。不论是独立的CAD系统还是作为CAD/CAM软件包的一部分的CAD系统，往往都可以在几个不同的层次上混合使用。两维线条图 几何图形被体现出两个方向，就象一张清单，Z轴深度将不得不与CAM相关。三维线框模型通过将代表边界的元素连接早一起，就可以在三维空间中表现几何形状。虽然线框图难以想象,但可以得到CAM所需的所有的Z向信息。三维表面模型 它与线框模型十分相似，所不同的是，在线框模型间覆盖了一层薄薄的外皮，从而使模型更形象。另外，模型型腔是空的，完成表面模型即可。三维实体模型这种当前高科技市场形式被使用必须通过所有的高端科技软件。几何形状被看作是一个实体特征其包括许多方面。实体模型可以被切开以展示内部特征，而不仅仅是拥有一层表皮。2. CAM模型根据CAD模型提供的几何形状，CAM模块用于创建加工工艺模型。例如，CAD模型可能包括一些特征，即凹槽型腔。我们可能应用其加工路线来加工几何图形，然后，所有的刀具路径将是自动的产生凹槽行程。同样，CAD模型也可包括几何图形应该产生钻的操作。我们能够选择简单的几何图形和按照CAM系统的说明在适当的位置上进行钻孔。CAM系统将生成描述加工操作的普通中间代码，这些代码以后可被用来生成G和M代码或会话式程序。在它们合适的环境下，有些系统产生中间代码。而其他使用较标准代码例如APT就是他们的中间文件。CAM模块也有多种类型和层次。首先，通常有些不同模型功能如铣、钻、以及装配，每一步工艺是唯一的，典型的模型有附加软件。每一个模型也可能使用不同的设备。例如，开始用简单的设备，到后来用复杂的、多方向的刀具轨迹路线，CAM模型中铣床加工通常加工的过程如下： 21/2-方向的机床 3个方向的机床 加工表面的机床 5个方向混合的机床每种体现出高精度的设备不可能在所有的坏镜下制造，一个工序很可能只要求三个方向的设备，而一个模型工序很可能需要全部的表面加工设备，而且可能需要五个方向的CAM软件包混合这样就有可能完成其加工表面。这种一流的软件安装很可能需要花费￥5000，但是许多复杂模型将花费￥15000甚至更多。因此，我们没有必要购买这种高水准的软件，因为我们不能完全发挥他们的潜能。3. 几何图形及刀具轨迹我们必须理解一个重要的概念，即CAD所绘制的几何形状并不一定与CNC机床加工出的几何形状完全一致。只要刀具轨迹是直线或圆弧，CNC机车就可以加工出非常精确的刀具轨迹。CAD系统也可能加工高精度几何图形如直线及圆弧，但是也可能加工许多不同层次的曲面，同样许多这种曲面被认为是非均匀有理B样条曲线。事实上，NURBS曲线可以描绘出从直线或圆弧到复杂的表面的任何几何形状。例如，就象几何图形为椭圆形，椭圆有一系列曲线，有着不同的环形弧，椭圆在CAD系统利用鼠标单击很容易产生。然而，一个标准的CNC加工刀具不能够直接使用产生一个椭圆它只能产生直线和圆弧。CAM系统将顺从于这种问题，通过估算用直线段代替曲线。CNC机床刀具通常只能识别圆弧或直线。因此，CAM系统必须估计直线段代替曲线之间的公差带。在这种情况下，就像椭圆刀具轨迹产生包含着用直线段代替曲线之间的公差带。CAM系统会在真正的曲线两侧各生成一个几何边界，从而形成一个公差带。它将生成一道刀具轨迹线包含着少量的公差带，结果这刀具轨迹将在数学理论上不正确CAM系统只能估算表面，使用它最基本的方法是为了估算刀具轨迹包括两维曲线及三维表面曲线。有些CAM系统也有可能直接绘制直线段为圆弧曲线。这可能在程序中产生许多模块导致表面的光滑。这种出现能够控制公差带的大小，其目的是使的刀具轨迹更加精确，这是有必要的。较小的公差带可以生成细致的刀具轨迹以及大量的直线段，而较大的公差带将会产生较少的直线段，刀具轨迹也比较粗糙。每一个直线段将要求在NC程序有模块代码。因此，当使用这种技术时，NC程序能够扩大范围。在加工表面时我们一定要细心，依靠计算机生成正确的刀具很容易，但在用球状端铣刀进行曲面的精加工是须进一步估价。如果我们没能注意到这种技术的局限性，那么精加工后工件的精度就会大打折扣。4. 刀具库和材料库为了创建机械加工工艺，CAM系统需要了解切割刀具的利用以及机械材料。CAM注意的是通过提供可定制的刀具型号及类型。材料库包括的信息是最优化的切削速度以及进给量。CAM使用这种信息聚在一起创建正确的刀具轨迹以及机床参数。这类刀具和材料库的格式经常是独有的，这一点带来了一些兼容问题。专用的工具库及材料库不容易修改或不容易使用其他的系统。进步的CAM开发者趋向于将刀具和材料库生成数据库文件，这样就可以为其他的应用者进行修改和定制提供方便。5. 检验及后置处理CAM系统通常提供检验刀具轨迹是否正确性的功能。这可以通过加工操作的刀具中心线的简单绘制或通过复杂的实体模型来实现。实体验证通常是CAD/CAM软件公司已经获得许可的第三方软件。然而，它可能是作为一个独立的软件包。后置处理器是一个软件程序，他将通过的中间代码格式化为使用于每个特定机床控制器的NC代码。后置处理器通常可以通过模板和变量被定制为需要的样式。6. 便捷性电子数据的便捷性是CAD/CAM系统唯一致命的弱点，这个问题任就是一件十分耗时的事情。CAD文件创建了许多格式以及它们之间有许多步同的组成。利用CAD系统创建一个复杂的模型是比较昂贵的。因此，我们希望使模型的便捷性最大化，而使在不同系统中重新生成几何模型的需求最小化。CAM模型与手提式的CAD模型不同，我们通常不能够发展一个CAM模型以及把它转换成其他格式。唯一被广泛接受的CAM模型交换版本就是自动编程工具（APT）。自动编程工具是一种利用描述机床操作的程序语言工具，自动编程工具是一种标准的、有着好的文件能够通过三个方向软件的发展的促进。许多CAD/CAM系统可以按照这种标准输出文件，而（由此生成的）CAM文件以后也可以被后置处理程序和校验软件使用。有时会有这样的情况，即特定的CAD/CAM系统生成的特有的中间文件不经任何额外的后置处理就可以直接输入到机床之中。这是理想的解决方案，然而目前尚无任何标准管理这种交换。CAD/CAM模型交换的另一种方法是利用逆向后置处理器。逆向后置处理器可以从数控G&M代码程序生成CAD/CAM模型。这种程序确实有些作用，但是，程序员必须花相当多的时间去搞清楚模型的设计意图，而且还要将刀具路径从几何形状中分离出来。总体来说，后置处理器的应用具有一定的局限性。软件的组成及发展趋势在整个工业上，许多软件包利用CAD或CAD/CAM。纯CAD系统被应用于所有的设计领域，实际上今天所有的产品都是用CAD软件设计出来的用纸笔绘的日子已经一去不复返了。另一方面，CAD/CAM软件包有着更多专利。CAD/CAM虽然小，但地位十分重要，它的应用通常限制在加工和装配业，其数量要比CAD小得多。CAD/CAM系统包括CAD软件设计以及CAM软件去创建刀具轨迹和NC代码。然而，普通的CAD模型相比于纯CAD软件比较弱及不精炼。这种不匹配造成了CAD设计者与CAD/CAM程序员之间一直以来的争论，其主题是如何使CAD/CAM能够融合。如果先在业界一流的CAD系统上生成所有几何形状，然后再图形输入到某个CAD/CAM系统中，就会产生很大的争论。工程师创建CAD模型逐步形成一种模式，商业就会更加充裕。几何形状能够输入到CAD/CAM软件包中产生处理模型。因此，工业引导CAD软件包走向不正式的标准。标准的接受度越高，拥有该软件的公司的投资回报率就会越高。反对意见来自于小的组织，他们没有必要或者没有资源同时拥有昂贵的符合工业标准的CAD软件包以及CAD/CAM软件包。他们往往需要根据纸上工程图重画几何图形，或者用并不完善的翻译设备输入模型。任何起源模型将结束走向于更高的正式的CAD/CAM文件。这类模型很可能在将来又被翻译成更为标准的版本。不论选择什么样的方法，各种组织和个人往往都会竭尽保护某种技术。如果他们检查发现有巨大的效果，花时间去学习它以及吸收科学知识。然而，他将转变成一种新的技术是很困难的事，即使它们体现出具有无法抵抗的证据来证实更好的方法。这是一次十分痛苦的转变，当然如果我们能够看见我们的将来，这是不可能发生的事情。但是事实上，我们不可能总是预测支配的科学技术将在几年内走下坡路。结果形成了技术壕沟，要从脚下消除这种壕沟将会十分困难和昂贵。大约只能保证，我们能够发现去选择技术出现最标准，即使不完美也要留住它.然而，如果发现走下坡路，我们将也更加适应这位置。Modern design and manufacturing CAD/CAMCAD/CAM is a term which means computer-aided design and computer-aided manufacturing. It is the technology concerned with the use of digital computers to perform certain functions in design and production. This technology is moving in the direction of greater integration（一体化）of design and manufacturing, two activities which have traditionally been treated as distinct（清楚的）and separate functions in a production firm. Ultimately, CAD/CAM will provide the technology base for the computer-integrated factory of the future.Computer-aided design (CAD) can be defined as the use of computer systems to assist in the creation, modification, analysis, or optimization（最优化）of a design. The computer systems consist of the hardware and software to perform the specialized design functions required by the particular user firm. The CAD hardware typically includes the computer, one or more graphics display terminals, keyboards, and other peripheral equipment. The CAD software consists of the computer programs to implement（实现，执行）computer graphics to facilitate the engineering functions of the user company. Examples of these application programs include stress-strain（压力-应变）analysis of components（部件）, dynamic（动态的）response of mechanisms, heat-transfer calculations, and numerical control part programming. The collection of application programs will vary from one user firm to the next because their product lines, manufacturing processes, and customer markets are different these factors give rise to differences in CAD system requirements.Computer-aided manufacturing (CAM) can be defined as the use of computer systems to plan, manage, and control the operations of a manufacturing plant through either direct or indirect computer interface with the plants production resources. As indicated by the definition, the applications of computer-aided manufacturing fall into two broad categories: 1.computer monitoring and control. 2.manufacturing support applications.The distinction between the two categories is fundamental to an understanding of computer-aided manufacturing.In addition to the applications involving a direct computer-process interface（界面，接口）for the purpose of process monitoring and control, compute-aided manufacturing also includes indirect applications in which the computer serves a support role in the manufacturing operations of the plant. In these applications, the computer is not linked directly to the manufacturing process. Instead, the computer is used “off-line”（脱机）to provide plans, schedules, forecasts, instructions, and information by which the firms production resources can be managed more effectively. The form of the relationship between the computer and the process is represented symbolically in the figure given below. Dashed lines（虚线）are used to indicate that the communication and control link is an off-line connection, with human beings often required to consummate（使圆满）the interface. However, human beings are presently required in the application either to provide input to the computer programs or to interpret the computer output and implement the required action.Manufacturing operations computer Process data Control signals CAM for manufacturing supportWhat is CAD/CAM software? Many toolpaths are simply too difficult and expensive to program manually. For these situations, we need the help of a computer to write an NC part program.The fundamental concept of CAD/CAM is that we can use a Computer-Aided Drafting (CAD) system to draw the geometry of a workpiece on a computer. Once the geometry is completed, then we can use a computer-Aided Manufacturing (CAM) system to generate an NC toolpath based on the CAD geometry. The progression（行进，级数 ）from a CAD drawing all the way to the working NC code is illustrated as follows:Step 1: The geometry is defined in a CAD drawing. This workpiece contains a pocket to be machined. It might take several hours to manually write the code for this pocket（凹槽，型腔）. However, we can use a CAM program to create the NC code in a matter of minutes. Step 2: The model is next imported into the CAM module. We can then select the proper geometry and define the style of toolpath to create, which in this case is a pocket. We must also tell the CAM system which tools to use, the type of material, feed, and depth of cut information.Step 3: The CAM model is then verified to ensure that the toolpaths are correct. If any mistakes are found, it is simple to make changes at this point. Step 4: The final product of CAD/CAM process is the NC code. The NC code is produced by post-processing（后处理）the model, the code is customized（定制，用户化）to accommodate the particular variety of CNC control. Another acronym that we may run into is CAPP, which stands for Computer-Aided Part Programming. CAPP is the process of using computers to aid in the programming of NC toolpaths. However, the acronym CAPP never really gained widespread acceptance, and today we seldom hear this term. Instead, the more marketable CAD/CAM is used to express the idea of using computers to help generate NC part programs. This is unfortunate because CAM is an entire group of technologies related to manufacturing design and automation-not just the software that is used to program CNC machine tools.Description of CAD/CAM Components and FunctionsCAD/CAM systems contain both CAD and CAM capabilities each of which has a number of functional elements. It will help to take a short look at some of these elements in order to understand the entire process.1. CAD ModuleThe CAD portion of the system is used to create the geometry as a CAD model. The CAD model is an electronic description of the workpiece geometry that is mathematically precise. The CAD system, whether stand alone or as part of a CAD/CAM package, tends to be available in several different levels of sophistication. （强词夺理，混合）2-D line drawings 两维线条图Geometry is represented in two axes, much like drawing on a sheet of paper. Z-level depths will have to be added on the CAM end.3-D wireframe models 三维线框模型Geometry is represented in three-dimensional space by connecting elements that represent edges and boundaries. Wiregrames can be difficult to visualize（想象，形象化，显现）, but all Z axis information is available for the CAM operations. 3-D surface models 三维表面模型These are similar to wireframes except that a thin skin has been stretched over the wireframe model to aid in visualization. Inside, the model is empty. Complex contoured Surfaces are possible with surface models.3-D solid modeling 三维实体模型This is the current state of the market technology that is used by all high-end software. The geometry is represented as a solid feature that contains mass. Solid models can be sliced（切片，部分 ，片段）open to reveal internal features and not just a thin skin. 2. CAM ModuleThe CAM module is used to create the machining process model based upon the geometry supplied in the CAD model. For example, the CAD model may contain a feature that we recognize as a pocket .We could apply a pocketing routine to the geometry, and then all of the toolpaths would be automatically created to produce the pocket. Likewise, the CAD model（模子，铸型）may contain geometry that should be produced with drilling operations. We can simply select the geometry and instruct the CAM system to drill holes at the selected locations.The CAM system will generate a generic（一般的，普通的 ）intermediate（中间的，媒介）code that describes the machining operations, which can later be used to produce G & M code or conversational programs. Some systems create intermediate code in their own proprietary（所有的，私人拥有的 ） language, which others use open standards such as APT for their intermediate files.The CAM modules also come in several classes and levels of sophistication. First, there is usually a different module available for milling, turning, wire EDM, and fabrication（装配）. Each of the processes is unique enough that the modules are typically sold as add-ins（附加软件）. Each module may also be available with different levels of capability. For example, CAM modules for milling are often broken into stages as follows, starting with very simple capabilities and ending with complex, multi-axis toolpaths : 21/2-axis machining Three-axis machining with fourth-axis positioning Surface machining Simultaneous five-axis machiningEach of these represents a higher level of capability that may not be needed in all manufacturing environments. A job shop might only require 3-axis capability. An aerospace contractor might need a sophisticated 5-axis CAM package that is capable of complex machining. This class of software might start at $5,000 per installation, but the most sophisticated modules can cost $15,000 or more. Therefore, there is no need to buy software at such a high level that we will not be able to use it to its full potential.3.Geometry vs. toolpathOne important concept we must understand is that the geometry represented by the CAD drawing may not be exactly the same geometry that is produced on the CNC machine tool. CNC machine tools are equipped to produce very accurate toolpaths as long as the toolpaths are either straight lines or circular arcs. CAD systems are also capable of producing highly accurate geometry of straight line and circular arcs, but they can also produce a number of other classes of curves. Most often these curves are represented as Non-Uniform（不均匀的，不一致的）Rational Bezier Splines (NURBS) （非均匀有理B样条）. NURBS curves can represent virtually any geometry, ranging from a straight line or circular arc to complex surfaces. Take, for example, the geometric entity that we call an ellipse（椭圆形）. An ellipse is a class of curve that is mathematically different from a circular arc. An ellipse is easily produced on a CAD system with the click of the mouse. However, a standard CNC machine tool cannot be use to directly problem an ellipse it can only create lines and circular arcs. The CAM system will reconcile（使和解，使顺从）this problem by estimating the curve with line segments.CNC machine tools usually only understand circular arcs or straight lines. Therefore, the CAM system must estimate curved surfaces with line segments. The curve in this illustration is that of an ellipse, and the toolpath generated consists of tangent line segments that are contained within a tolerance zone.The CAM system will generate a bounding geometry on either side of the true curve to form a tolerance zone. It will then produce a toolpath from the line segment that stays contained within the tolerance zone. The resulting toolpath will not be mathematically correct the CAM system will only be able to estimate the surface. This basic method is used to produce estimated toolpaths for both 2-D curves and 3-D surface curves.Some CAM programs also have the ability to convert the line segments into arc segments. This can reduce the number of blocks in the program and lead to smoother surfaces.The programmer can control the size of the tolerance zone to create a toolpath that is as accurate as is needed. Smaller tolerance zones will produce finer toolpaths and more numerous line segments, while larger tolerance zones will produce fewer line segments and coarser（粗糙的） toolpaths. Each line segment will require a block of code in the NC program, so the NC part program can grow very large when using this technique.We must use caution when machining surfaces. It is easy to rely on the computer to generate the correct tooolpath, but finished surfaces are further estimated during machining with ball end mills. If we do not pay attention to the limitations of these techniques, then the accuracy of the finished workpiece may be compromised（妥协，折衷）.4.Tool and material librariesTo create the machining operations, the CAM system will need to know which cutting tools are available and what material we are machining. CAM systems take care of this by providing customizable （可定制的 ）libraries of cutting tools and materials. Tool libraries contain information about the shape and style of the tool. Material libraries contain information that is used to optimize（使最优化）the cutting speeds and feeds. The CAM system uses this information together to create the correct toolpaths and machining parameters.（参数）The format of these tool and material libraries is often proprietary（专利的，独占的，私有的）and can present some portability issues. Proprietary（轻便，移动）tool and material files cannot be easily modified or used on another system. More progressive （ 改革论者，进步论者，前进的）CAM developers tend to produce their tool and material libraries as database files that can be easily modified and customized for other applications. 5.Verification and post-processorCAM systems usually provide the ability to verify that the proposed toolpaths are correct. This can be via a simple backplot（背景绘制） of the tool centerline or via a sophisticated solid model of the machining operations. The solids verifications（确认，查证）is often a third-party software that the CAD/CAM software company has licensed.（得到许可的 ） However, it may be available as a standalone package.The post-processor is a software program that takes a generic intermediate code and formats the NC code for each particular machine tool control. The post-processor（后置处理器） can often be customized through templates（模板）and variables to provide the required customization. （用户化，专用化，定制）6.Portability 轻便，可带的Portability of electronic data is the Achilles heel(唯一致命的弱点)of CAD/CAM systems and continues to be a time-consuming concern. CAD files are created in a number of formats and have to be shared between many organizations. It is very expensive to create a complex model on a CAD system; therefore, we want to maximize the portability of our models and minimize the need for recreating the geometry on another system. DXF, DWG, IGES, SAT, STL and parasolids are a few of the common formats for CAD data exchange.CAM process models are not nearly as portable as CAD models. We cannot usually take a CAM model developed in one system and transfer it to another platform. The only widely accepted standard for CAM model interchange is a version of Automatically Programmed Tool (APT). APT is a programming language used to describe machining operations. APT is an open standard that is well documented and can be accessed by third-party software developers. A number of CAD/CAM systems can export to this standard, and the CAM file can later be used by post-processors and verification software. There are some circumstances when the proprietary intermediate files created by certain CAD/CAM systems can be fed directly into a machine tool without any additional post-processing. This is an ideal solution, but there is not currently any standard governing this exchange.One other option for XAD/CAM model exchange is to use a reverse post-processor. A reverse post-processor can create a CAD/CAM model from a G &M-code of NC part program. These programs do work; however, the programmer must spend a considerable amount of time determining the design intent of the model and to separate the toolpaths from the geometry. Overall, reverse post-processing has very limited applications.Software issues and trendsThroughout industry, numerous software packages are used for CAD and CAD/CAM. Pure CAD systems are used in all areas of design, and virtually any product today is designed With CAD software-gone are the days of pencil and paper drawings.CAD/CAM software, on the other hand, is more specialized. CAD/CAM is a small but important niche（适当的位置）confined to machining and fabrication organizations, and it is found in much smaller numbers than its CAD big brother.CAD/CAM systems contain both the software for CAD d
温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
提示  人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
关于本文
本文标题：CADCAM技术在摩托车护片锻模设计中的应用【6张CAD图纸+毕业论文】
链接地址：https://www.renrendoc.com/p-435860.html

官方联系方式

网站客服网站客服      侵权投诉侵权投诉
1:下载资料失败解决办法   
2:不支持迅雷下载,请使用浏览器下载   
3:不支持QQ浏览器下载,请用其他浏览器   
4:下载后的文档和图纸-无水印   
5:文档经过压缩，下载后原文更清晰   
点击下载此资源
关于我们 - 网站声明 - 网站地图 - 资源地图 - 友情链接 - 网站客服 - 联系我们

网站客服QQ：2881952447     

copyright@ 2020-2025  renrendoc.com 人人文库版权所有   联系电话：400-852-1180

备案号:蜀ICP备2022000484号-2       经营许可证: 川B2-20220663       公网安备川公网安备: 51019002004831号

本站为文档C2C交易模式，即用户上传的文档直接被用户下载，本站只是中间服务平台，本站所有文档下载所得的收益归上传人(含作者)所有。人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私，请立即通知人人文库网，我们立即给予删除！