Advanced Manufacturing Technology(先进制造技术)

课程名称：Advanced Manufacturing Technology(先
进制造技术)
专业班级：机制091
学号：3090101310
姓名：孙作强
任课老师：钟相强
成绩：
Computer-aided design
专业：机制093 姓名：孙作强
指导老师：钟相强
Abstract: Computer-aided design also known as computer-aided design and drafting (CADD), is the use of computer systems to assist in the creation, modification, analysis, or optimization of a design. Computer Aided Drafting describes the process of creating a technical drawing with the use of computer software. CADD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing. CADD output is often in the form of electronic files for print or machining operations. CADD software uses either vector based graphics to depict the objects of traditional drafting, or may also produce raster graphics showing the overall appearance of designed objects.
Keywords: CAD computer technology
Introduction:The design of geometric models for object shapes, in particular,
is occasionally called computer-aided geometric design (CAGD). In CAD, many commands are available for drawing basic geometric shapes. Examples include CIRCLE, POLYGON, ARC, ELLIPSE, and more.
1.1 Uses
Computer-aided design is one of the many tools used by engineers and designers and is used in many ways depending on the profession of the user and the type of software in question.
CAD is one part of the whole Digital Product Development (DPD) activity within the Product Lifecycle Management (PLM) processes, and as such is used together with other tools, which are either integrated modules or stand-alone products, such as:
∙Computer-aided engineering (CAE) and Finite element analysis (FEA)
∙Computer-aided manufacturing (CAM) including instructions to Computer Numerical Control (CNC) machines
∙Photo realistic rendering
∙Document management and revision control using Product Data Management (PDM).
CAD is also used for the accurate creation of photo simulations that are often required in the preparation of Environmental Impact Reports, in which computer-aided designs of intended buildings are superimposed into photographs of existing environments to represent what that locale will be like were the proposed facilities allowed to be built. Potential blockage of view corridors and shadow studies are also frequently analyzed through the use of CAD.
CAD has also been proven to be useful to engineers as well. Using four properties which are history, features, parameterization, and high level constraints (Zhang). The construction history can be used to look back into the model's personal features and work on the single area rather than the whole model (zhang). Parameters and constraints can be used to determine the size, shape, and the different modeling elements. The features in the CAD system can be used for the variety of tools for measurement such as tensile strength, yield strength, also its stress and strain and how the element gets affected in certain temperatures.
1.2 Types
There are several different types of CAD, each requiring the operator to think differently about how to use them and design their virtual components in a different manner for each.
There are many producers of the lower-end 2D systems, including a number of free and open source programs. These provide an approach to the drawing process without all the fuss over scale and placement on the drawing sheet that accompanied hand drafting, since these can be adjusted as required during the creation of the final draft.
3D wireframe is basically an extension of 2D drafting (not often used today). Each line has to be manually inserted into the drawing. The final product has no mass properties associated with it and cannot have features directly added to it, such as holes. The operator approaches these in a similar fashion to the 2D systems, although many 3D systems allow using the wireframe model to make the final engineering drawing views.
3D "dumb" solids are created in a way analogous to manipulations of real world objects (not often used today). Basic three-dimensional geometric forms (prisms, cylinders, spheres, and so on) have solid volumes added or subtracted from them, as if assembling or cutting real-world objects. Two-dimensional projected views can easily be generated from the models. Basic 3D solids don't usually include tools to easily allow motion of components, set limits to their motion, or identify interference between components.
3D parametric solid modeling requires the operator to use what is referred to as "design intent". The objects and features created are adjustable. Any future modifications will be simple, difficult, or nearly impossible, depending on how the original part was created. One must think of this as being a "perfect world" representation of the component. If a feature was intended to be located from the center of the part, the operator needs to locate it from the center of the model, not, perhaps, from a more convenient edge or an arbitrary point, as he could when using "dumb" solids. Parametric solids require the operator to consider the consequences of his actions carefully.
Some software packages provide the ability to edit parametric and non-parametric geometry without the need to understand or undo the design intent history of the geometry by use of direct modeling functionality. This ability may also include the additional ability to infer the correct relationships between selected geometry (e.g., tangency, concentricity) which makes the editing process less time and labor intensive while still freeing the engineer from the burden of understanding the models. These kind of non-history based systems are called Explicit Modellers or Direct CAD Modelers.
Top end systems offer the capabilities to incorporate more organic, aesthetics and ergonomic features into designs. Freeform surface modeling is often combined with solids to allow the designer to create products that fit the human form and visual requirements as well as they interface with the machine.
1.3 Technology
Originally software for Computer-Aided Design systems was developed with computer languages such as Fortran, but with the advancement of object-oriented programming methods this has radically changed. Typical modern parametric feature based modeler and freeform surface systems are built around a number of key C modules with their own APIs. A CAD system can be seen as built up from the interaction of a graphical user interface (GUI) with NURBS geometry and/or boundary representation (B-rep) data via a geometric modeling kernel. A geometry constraint engine may also be employed to manage the associative relationships between geometry, such as wireframe geometry in a sketch or components in an assembly.
Unexpected capabilities of these associative relationships have led to a new form of prototyping called digital prototyping. In contrast to physical prototypes, which entail manufacturing time in the design. That said, CAD models can be generated by a computer after the physical prototype has been scanned using an industrial CT scanning machine. Depending on the nature of the business, digital or physical prototypes can be initially chosen according to specific needs.
Today, CAD systems exist for all the major platforms (Windows, Linux, UNIX and Mac OS X); some packages even support multiple platforms.
Right now, no special hardware is required for most CAD software. However, some CAD systems can do graphically and computationally intensive tasks, so a modern graphics card, high speed (and possibly multiple) CPUs and large amounts of RAM may be recommended.
The human-machine interface is generally via a computer mouse but can also be via a pen and digitizing graphics tablet. Manipulation of the view of the model
on the screen is also sometimes done with the use of a Spacemouse/SpaceBall. Some systems also support stereoscopic glasses for viewing the 3D model.
References
1. Vijay Duggal. “CADD Primer”. Mailmax Publishing.
2. Narayan, K. Lalit (2008). Computer Aided Design and Manufacturing. New Delhi: Prentice Hall of India. pp.
3.
3. Narayan, K. Lalit (2008). Computer Aided Design and Manufacturing. New Delhi: Prentice Hall of India. pp.
4.
4. H. Pottmann, S. Brell-Cokcan, and J. Wallner:Discrete surfaces for architectural design
计算机辅助设计
摘要:计算机辅助设计也称为计算机辅助设计以及制定(CADD),是利用计算机系统来协助创造、修改、分析、优化设计。

计算机辅助制图的过程中创造了一个技术图和计算机软件的使用。

CADD软件是用来提高生产力的设计师,提高设计的质量,提高通信通过文献的海洋里,为了创造一个数据库,为制造。

CADD产品往往是电子文件的形式为出版或加工操作。

软件的使用CADD要么矢量图形来描述物体的传统起草,或者也可以产生光栅图形显示的整体外观设计的东西。

关键词:CAD 计算机技术
引言：几何模型的设计为对象的形状,特别是计算机辅助几何设计有时称为(用CAGD)。

在计算机辅助设计(CAD),许多命令是用于绘图基本几何形状。

例子包括圈,多边形,弧,椭圆,和更多。

1 用途
计算机辅助设计是其中的许多工具用于工程师和设计师,以各种方式依靠专业的用户和
类型的软件问题。

CAD是整体的一部分数码产品开发(公司)内部的活动产品生命周期管理(PLM)的过程,是
配合使用其他工具,要么集成模块或独立的制品,如:
·计算机辅助工程(CAE)和有限元分析(FEA)
·计算机辅助制造(CAM)包括指示计算机数控(CNC)机
·照片真实度的渲染
·文档管理和版本控制使用的产品数据管理(PDM)。

计算机辅助设计(CAD)也可以用于精确创造照片的模拟,通常需要在制备环境影响报告书,在计算机辅助设计故意建筑罩到现有的环境中,照片代表什么,现场就会像被该设施允许建造。

潜在的角度和阴影阻塞通道研究亦经常进行了分析,利用计算机辅助设计(CAD)。

计算机辅助设计(CAD)也被证明是有用的工程师也。

使用四个属性,这是历史、特点、参数化、高水平约束(张)。

建筑历史可以用来观察回模型的个人特点及工作的一个方面,而不是整个模型(张)。

参数和限制可以被用来确定大小、形状和不同的建模元素。

在CAD系统的特征可用于不同的工具测量如抗拉强度、屈服强度,其应力、应变及单元在一定温度下得到的影响。

1.1 类型
有许多不同种类的计算机辅助设计(CAD),每一个需要操作员会以不同的方式思考一下如何服用药物和设计自己的虚拟元件以一种不同的方式为每个。

有许多生产的低端二维系统,包括一些免费的开源项目。

这些提供一种方法没有大惊小怪的拉拔工艺在规模和放置在图纸伴随手起草,因为这些可随意调节时的创作最后草稿。

三维物体的基本上是一个扩展的二维起草(不常用的今天)。

每一行都必须手动插入图。

最终的产品没有质量特性与之关联的,不能直接叠加特性,如孔。

接线员方法相似,这些在一个二维系统,尽管许多三维系统允许使用在线框模式作出最后的工程图纸的观点。

三维“笨”固体被创造出来的一个假手操控现实世界的对象(不常用的今天)。

基本的三维几何形状(棱镜、缸、球体等)具有雄厚的卷加上或减去整百、好像装配或切割的真实物件。

二维投影视图可以很容易产生的模型。

基本的3 D固体通常不包括工具很容易让运动的组件,尽情发挥他们的运动或识别组件之间的干扰。

三维参数化实体造型要求经营者使用是被称为“设计意图”。

创建对象和特点是可调整的。

任何将来的修改是件简单的事,困难重重,或者几乎是不可能的,这取决于原部分成立。

你必须把这看作是成为一个“完美的世界”的代表组成。

如果一个特征的目的是位于中心部分,运营商需要找到它的从中心模型、没有,或许,从一个更方便的边缘,或一个任意点,因为他可以当使用“笨”固体。

参数化固体要求经营者考虑自己行为的后果认真。

某些软件包提供能够编辑参数和非参数几何,而不需要去理解或还原历史的几何设计意
图利用直接建模功能。

这个技能也可以包括额外的能力来推断正确选定的几何关系(例如,相切,同心度)使编辑流程更少的时间,劳动密集型行业,同时还放走了工程师而造成的负担理解模型。

基于这样的non-history系统被称为显式模型制作者或直接CAD模型。

最高末端系统提供的功能将更多的有机的、美学和人机工程学特点到设计。

自由曲面建模往往是结合固体,让设计师创造产品适合人类形体和视觉要求以及接口的机器。

1.1.1 技术
最初的计算机辅助设计系统软件开发与计算机语言如Fortran语言,而是用面向对象的程序设计方法的进步这已经发生了根本的变化。

典型的现代参数特徵建立建模者和自由曲面系统都是建立在许多关键C模块与自己的api。

通过对CAD系统的二次可以被看作是建立起来的相互作用的一种图形用户接口(GUI)和NURBS几何和/或边界表示(边界表示法)数
据通过几何建模的内核。

一个几何约束引擎也可以用来管理结合的几何关系,如物体的几
何中的一个素描或零部件装配。

意想不到的能力这些联想的人际关系有了一个新的形式的原型称作数字样机。

与物理样机,产生在设计制造周期。

说,CAD模型可以由一个电脑后物理样机已扫描使用一个工业CT 机。

根据业务的特性、数字或物理原型可以初步选择根据具体的需求。

今天,CAD系统中存在的所有重要的平台(窗户,UNIX,Linux和Mac OS X);有的包甚至支持多个平台。

现在,没有特殊的硬件要求大多数CAD软件。

然而,一些CAD系统可以做图和计算密集型的任务,所以一个现代的图形卡、高速度(也有可能是多个)cpu和大量的内存可以推荐。

人机界面的一般是通过电脑鼠标,还可以通过一个钢笔和数字化图形片剂。

操纵的景观模型在屏幕上有时也完成了使用Spacemouse / SpaceBall。

一些系统也支持立体眼镜观看的三维分析模型。

参考文献
1.Vijay Duggal。

“CADD底漆”。

Mailmax出版。

2.纳拉亚,k . Lalit(2008)。

电脑辅助设计及制造。

新德里:智胜印度。

第3页。

3.纳拉亚,k . Lalit(2008)。

电脑辅助设计及制造。

新德里:智胜印度。

第4页。

4.Pottmann h . Brell-Cokcan,机械Wallner:离散面的建筑设计。