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1、,机电技术专业英语,2,Lesson Twenty-two,Text,Computeraided design (CAD) means the use of a computer to assist in the design of an individual part or a system, such as an aircraft. The design process usually involves computer graphics. Computeraided manufacturing (CAM) means the use of a computer to assist in
2、the manufacture of a part. CAM can be divided in two main classes: Online applications, namely, the use of the computer to control manufacturing systems in real time, such as CNC and AC systems of machine tools. Offline applications, namely, the use of the computer in production planning and nonreal
3、time assistance in the manufacturing of parts.,CAD/CAM/CNC,Lesson Twenty-two,CAD/CAM systems can be used to produce CNC data to machine a part. After preparing a tool list and setup plan for the required part, the CNC programmer starts by creating a database. Once this database has been created, the
4、 programmer can recall the part on the CRT screen. After the part is displayed, the programmer describes the tools required from the information in the tool library. This library contains a description and either a name or a tool identification number for each and every tool available or use Assume
5、that the database and tool described are for a milling/drilling operation. The next operation would then be to generate the tool path. In this case, the types of machining that could be performed would fall into three categories.,Lesson Twenty-two,Drilling operations: Using the Z axis perpendicular
6、with the surface of the part. Profile milling operations: Milling the profile of the part. Pocket milling operations: Using the Z axis to plunge and remove the material from the interior of the part. The CRT screen displays a graphic representation of the part and the path the cutting tools will fol
7、low in order to complete the machining of the part. This information must now be converted to a cutter location (CL) file. With a CL file, the information that was created to generate the graphic display is converted into coordinate locations to move the cutting tool around the part.This information
8、 is now in a readable format.,Lesson Twenty-two,New Words and Expressions,Lesson Twenty-two,Notes,1. The future of the automated and unattended factory depends more on the manufacturing information programs (software), which will be available, and how they will be used than on computer hardware. 自动化
9、无人工厂的未来主要取决于未来制造软件及其运行情况，而不是计算机的硬件。 由which引导的定语从句修饰programs；depend more onthan意为“主要取决于而不是”。 2. MCUs will have adaptive control (AC), which can provide feedback information from the cutting tool, work piece, or machine tool so that the best machining conditions can be maintained. MCU将具有自适应控制能力，能够从切削刀
10、具、工件或机床上提供反馈信息，以保持最佳的加工状态。 由which引导的定语从句修饰adaptive control; so that引出目的状语从句。,Lesson Twenty-two,3. The NC data combined with group technology (GT), manufacturing process planning (MPP), MRP, and manufacturing control systems will contain enough information and systems technology for the automated or
11、unattended factory of the future. NC数据与成组技术（GT）、制造工艺规划（MPP）、物料需求计划（MRP）、制造控制系统的有机结合，必将给未来自动化无人工厂提供足够的信息与系统技术支持。 句子主干为：The NC data will contain enough information and systems technology. combined with 是过去分词短语作后置定语，修饰the NC data。,Lesson Twenty-two,Lesson Twenty-two,参考译文,计算机辅助设计（CAD）指的是用计算机来帮助设计单个零件或整个
12、系统，如航空器。设计过程经常包括计算机绘图。 计算机辅助制造（CAM）是指借助计算机来制造零件。CAM可分为两种主要类型：在线应用，即用计算机实时控制加工制造系统，例如计算机数字控制（CNC）以及机床的自适应（AC）；离线应用，即在生产的规划以及非实时辅助零部件加工时使用计算机。 CAD/ CAM 系统可以生成加工零件所需要的CNC数据。当准备好刀具清单和待加工零件的加工工艺之后， CNC编程员便可开始建立数据库。建好数据库之后，编程员可在CRT显示器上调用这个零件。显示零件之后，编程员可从刀库中选取需要的刀具。刀库中的每一把刀具都有相应的描述，并且附加一个刀名或标识码。如果数据库与被选中的刀具是用来进行铣或钻加工的，那么，下一步的工作就是生成刀具轨迹。在这种情形下，执行的加工可以分为以下三类：,计算机辅助设计/计算机辅助制造/计算机数字控制,Lesson Twenty-two,钻加工：使Z轴与零件表面垂直； 轮廓铣削：铣零件轮廓； 沟槽铣削：使Z轴进刀，从零件内部去除材料。,谢谢观赏,,Thank You !,
