机械英语中英对照分析解析.pptx

Lesson 21 CAD/CAM/CAPP1.Words and phrasesn interactive adj.交互式的n wire-frame models 线框模型n surface models表面模型n solid models实体模型n vertex顶点，最高点n stress-strain应力，应变n fabricatev.构成，伪造，虚构n straightforward正直的，简单的，直截了当的n incorporate合并的，一体化的n phenomenon 现象n simultaneous 同时的，同时发生的2.textnCAD计算机辅助设计n Computer aided design(CAD)can be defined as using computers to aid the engineering design process by means of effectively creating,modifying,or documenting the parts geometrical modeling.be defined as 被定义为by means of 通过方法、手段n 计算机辅助设计被定义为通过高效的创建、修改或记录零件的几何建模 等手段，使用计算机来辅助工程设计过程。nCAD is most commonly associated with the use of an interactive computer graphics system.The object of the engineering design is stored and represented in the form of geometric models.n associate with 与联系在一起n in the form of 以的形式存在n 计算机通常与交互式计算机图形系统的使用联系在一起。工程设计的实体以几何模型的形式进行存储和记录。n Geometric modeling is concerned with the use of a CAD system to develop a mathematical description of the geometry of an object.The mathematical description is called a model.There are three types of models(wire-frame models,surface models,and solid models,see Fig.21.1),that are commonly used to represent a physical objects.n be concerned with 干预，参与n CAD系统使用几何建模来进行实体几何上的数学描绘。数学上的这种描绘称为建模。有三种类型的建模（线框模型、表面模型、实体模型，见图21.1），它们通常用来描绘物质实体。n nWire-frame models,also called edge-vertex or stick-figure手工线形画 models,are the simplest method of modeling and are most commonly used to define computer models of parts.Surface models may be constructed using a large variety of surface features.n线框模型也叫网格点或线轮廓模型，是建模最简单的方法，常用来定义零件的计算机建模。表面模型可以应用各种表面特征来构造。nSolid models are recorded in the computer result；1it is possible to calculate mass properties of the parts,which is often required for engineering analysis such as finite element methods,kinematics or dynamic studies,and mass or heat transfer for interference checking.n kinematics 运动学的 dynamic 动力学的，动态的n实体模型记录在计算机的结果里面，它可能会用来计算零件的质量属性，这些质量属性通常是用以工程分析，如有限元方法，运动学和动力学研究，进行干涉校验发生的质量和热传递。n Models in CAD also can be classified as being two-dimensional models,two-and-half dimensional models,or three-dimensional models.A 2-D model represents a flat part and a 3-D model(see Fig.21.2)provides representation of a generalized part shape.A 2.5-D model can be used to represent a part of constant section with no side-wall details.2The major advantage of a 2.5-D model is that it gives a certain amount of 3-D information about a part without the need to create the database of a full 3-D model.n generalized 广义的，无显著特点的，通用的n CAD中的模型也可以分类为二维模型、2.5维模型、三维模型。二维模型描绘平面零件，三维模型描绘广义零件的形状。2.5维模型能用来描绘零件的无侧面细节的连续部分。2.5维模型的主要优势是给出零件的一定数量三维信息，而无需全三维模型的数据库。n After a particular design alternative has been developed,some form of engineering analysis must often be performed as a part of the design process.The analysis may take the form stress-strain calculations,heat transfer analysis,dynamic simulation etc.Some examples of the software typically offered on CAD systems are mass properties and Finite Element Method(FEM)analysis.n particular 特定的，详细的，详尽的，精确的n take the form(of)采取形式n 选择性的详尽的设计形成以后，一些工程分析方式常作为零件设计进程来进行。一些分析也许采取压力应变计算、热传递分析、动态仿真等形式进行。在CAD系统中典型的软件提供的例子就是材质属性和有限元方法分析。nMass properties involve the computation of such features of a solid object as its volume,surface area,weight,and center of gravity.FEM analysis is available on most CAD systems to aid in heat transfer,stress-strain analysis,dynamic characteristics,and other engineering computations.Presently,many CAD systems can automatically generate the 2-D or 3-D FEM meshes which are essential to FEM analysis.Mesh 网状物 v.相合，相配n 材质属性包括实体体积、表面积、重量和重心。有限元方法分析用在多数CAD系统中，用以辅助热传递、应力应变分析、动态特性和其他工程计算。目前，很多CAD系统能自动生成2D或3D有限元网格，有限元网格是有限元方法分析的主要组成要素。CAM 计算机辅助制造nCAM can be defined as computer aided preparation manufacturing including decision-making,process and operational planning,software design techniques,and artificial intelligence,and manufacturing with different types of automation(NC machine,NC machine centers,NC machining cells,NC flexible manufacturing systems),and different types of realization(CNC single unit technology,DNC group technology).Realization 意识，现实，实现，变现，变卖n CAM可以定义为计算机辅助制造，包括制定决策、进程和操作规划，软件设计技术、人工智能、不同类型的数控制造（数控加工、数控加工中心、数控加工单元、数控柔性生产系统）和各种类型的实现方法（计算机数控单元技术、直接数控成组技术）n The CAM covers group technology,manufacturing database,automated and tolerance.Fig.21.3 illustrates the general scope of CAM.n CAM包含了成组技术，生产数据库，自动化和公差检测。图21.3列举了CAM的总体范围。n When a design has frozen冻结，冷冻,manufacturing can begin.Computers have an important role to play in many aspects of production.Numerically controlled machine tools need a part program to define the components being made;computer techniques exist to assist,and in some cases virtually automate the generation of part programs.Modern shipbuilding fabricates structures from welded steel plates that are cut from a large steel sheet.Computer-controlled flame cutters are often used for this task and the computer is used to calculate the optimum layout of the components to minimize waste metal.Numerically controlled pipe-bending machines are able to operate directly from part programs generated by pipe-routing software.n 当一个设计确定以后，生产才能开始。计算机在生产的许多方面扮演着重要的角色。数控机床需要一个零件加工程序来确定加工的部件；计算机技术的出现提供了辅助，在多数情况下，零件加工程序事实上是自动生成的。现代造船业从大型钢板上剪下焊接钢板构造结构。计算机控制火焰切割机常用来完成这项任务，且计算机被用来计算最优的零部件外形使得材料的浪费达到最小。数控弯管机可以通过管道路径软件生产的零件加工程序直接进行操作。n Printed circuit board assembly can also be improved by computer methods.Quality is maintained by computer-controlled automatic test equipment that diagnoses faults in a particular board and rejects拒绝 defective有缺陷的 boards from the assembly line.Computers are used extensively to plot the artwork插图 used to etch蚀刻，凿刻 printed circuit boards and also to produce part programs for NC drilling machines.n 印刷集成的电路板也可以通过计算机方法进行改进。通过计算机控制的自动检测装备诊断特殊电路板的错误可以保证质量，从装配生产线上淘汰有缺陷的电路板。计算机被广泛应用在绘制蚀化印刷电路板模块和生产数控钻床零件加工程序。n One of the most important manufacturing function is stock and production control.If the original design is done on a computer,obtaining lists of material requirements is straightforward.Standard computer data processing methods are employed to organize the work flow and order components when required.n 库存和生产控制是最重要的生产功能之一。如果原始设计在计算机上完成后，就可以直接获得材料需求清单。标准的计算机数据处理方法被用在物流组织和订购所需零部件上。CAPP 计算机辅助工艺设计n Computer aided process planning(CAPP)can be defined as the functions which use computers to assist the work of process planners.The levels of assistance depend on the different strategies employed to implement the system.Lower level strategies only use computers for storage and retrieval of the data for the process plans which will be constructed manually by process planners,as well as for supplying the data which will be used in the planners new work.In comparison with lower level strategies,higher level strategies use computers to automatically generate process plans for some work pieces of simple geometrical shapes.n CAPP被定义为使用计算机辅助工艺员的工作。辅助的程度依赖于执行在此系统上的不同策略。低等级的策略只是通过计算机完成存储和修复工艺流程数据，这些工艺流程可以由工艺员手工构建并为工艺员的新任务提供数据。相比于低等级策略，高等级策略是使用计算机自动为一些简单几何形状的工件生成工艺流程。n Sometimes a process planner is required to input the data needed or to modify plans which do not fit specific production requirements well.The highest level strategy,which is the ultimate goal of CAPP,generates process plans by computer,which may replace process planners,when the knowledge and expertise of process planning and working experience have been incorporated into the computer programs.The database in a CAPP system based on the highest level strategy will be directly integrated with conjunctive systems,e.g.CAD and CAM.CAPP has been recognized as playing a key role in CIMS(Computer integrated manufacturing system).n 有时工艺员需要输入需要的数据或者修改不能很好的适合特殊生产的工艺流程。高级策略的目标是CAPP的最高目标，当工艺知识、专门技术和工作经验被融合进计算机程序中时，计算机也许会取代工艺员去完成生产工艺流程。基于最高等级策略的CAPP系统中的数据库将被直接集成在相关系统。如CAD和CAM。CAPP被认为是CIMS（计算机集成制造系统）的关键角色。nMore than 20 years have elapsed since the use of computers to assist process planning tasks was first proposed.Tremendous efforts have been made in the development of CAPP systems.For the time being,the research interests for development of CAPP systems are focused on intelligent and integrated process planning systems.For increasing the intelligence of CAPP systems,some new concepts,such as neural networks,fuzzy logic,and machine learning have been explored for the new generation of CAPP systems.For increasing the integrability of CAPP system,feature based design,the roles of features,integrating process planning with scheduling,and integrating process planning with manufacturing resources planning have been focused on.This phenomenon is entitled concurrent or simultaneous engineering.n 从首次提出用计算机来辅助工艺流程任务以来已过去了20多年。人们为CAPP的发展作了极大的努力。随着时间的推移，研究CAPP系统的意义集中在智能化和集成工艺流程系统上。为提高CAPP系统的智能化程度，一些新概念，如神经网络，模糊逻辑学和机器示教在新生代CAPP系统中被探索开发。为增加CAPP系统的可积性，设计开发的焦点集中于设计中的典型特征、典型特征的功能、工艺过程和行程安排一体化，并集成了制造原材料计划的工艺流程。该现象能够与工程同时产生。nSince a process plan determines the methods,machines,sequences,fixturing,and tools required in the fabrication and assembly of components,it is easy to see that process planning is one of the basic tasks to be performed in manufacturing systems.The task of carrying out the difficult and detailed process plans has traditionally been done by workers with a vast knowledge and understanding of the manufacturing process.Many of these skilled workers,now considered process planners,are either retired or close to retirement,with no qualified young process planners to take their place.An increasing shortage of process planners has been created.With the high pressure of serious competition in the world market,integrated production has been pursued as a way for companies to survive and succeed.Automated process planning systems have been recognized as playing a key role in CIMS.It is for reasons such as these that many companies look for computer aided process systems.n 因为工艺流程决定了在制造和装配零件时所需的方法、机器、顺序、工装和刀具，容易看出编制工艺流程是制造系统要执行的基本任务之一。传统上的推行任务的困难和详细工艺规程的制定由精通制造工艺的操作工人来解决。许多熟练的工人，现在被认为是工艺员，已经或接近退休，然而却没有年轻有资格的工艺员来接替他们的位置。工艺员的短缺逐渐增加。随着世界市场竞争压力的加大，追求合作化的集成产品将幸存下来并取得成功。自动化的工艺流程系统已被看作是CIMS中至关重要的部分。这就是许多公司关注计算机辅助工艺设计的原因。