CAD和CAM.doc

CAD/CAMComputer-aided design (CAD) and computer-aided manufacturing (CAM) use digital computers, with their high speed and accruacy, as the integrating force throughout the entire process from engineering design to product manufacture. CAD/CAM evolves from and brings together such technologies as numeriacal control and computer technology. Tied together by the common usage of digital data, and fed by a continuous stream of electronics developments, numerical control and the digital computer have roached the maturity to permit a level of integration tat brings us to the threshold of the long-envisioned automatic factory.The various computerized functions under CAD/CAM fall into three general areas:1.Design/drafting, or computer-aided engineering2.Planning/scheduling, or management information systems3.Fabrication, or manufacturing automationA conceptuallized or idealized CAD/CAM system shows how the user interacts with the computer via a graphics terminal, designing and controlling the manufacturing process from start to finish with information stored in a shared data base. With the advent of interactive graphics, the problem of the use entering data and instructions into the computer with stacks of coded punched cards or reels of tape went away. No longer was the user required to be experienced in computer programming and operation to use the machine. With interactive graphics, the user communicates with the computer in display-screen pictures.no knowledge of computers is required to operate these systems, and the communication is in real time, which means that the computers response to the users instructions is almost instantaneous. In CAD/CAM, the requirement is for the solution of three-dimensional mechanical design and manufacturing problems. Interacting with the computer via keyboard and lightpen or other pencillike devices,the designer specifics points and lines on the display screen to quickly construct a display-screendrawing or model. This is in reality the representation of the diagram stored in the computer data base.With a stroke of the pen, orby pushing a button, the entire design or any part of it. For example, by pushing a button the designer may issue a flip a command to produce a mirror image of a display for modeling symmetrical parts. A cross section may be defined and then translated linearly to create a surfaced model. In a similar manner, circular parts can be easily modeled with a rotate command in which a cross section is rotated about a central axis to model parts. These operations tha advantage of the computers capability to repeatdetailed operations quickly and flawlessly.After design completion, the resultant geometric data stored in the computer memory may be used to produce numerical control instructions for making the parts on automated machine tools, or to generate the art work and drill tapes for automated printed circuit card fabrication. Many CAD/CAM systems can now produce simulated on the display-screen to validate, verify, and modify the program more rapidly.In summary, CAD/CAM is comprised of distinct functional areas. The experts group CAD functions into four major categories:1.Geometric modeling2.Engineering analysis3.Kinematics4.Automated draftingCAM technology also centers around four major areas or categories:1.Numerical control2.Process planning3.Robotics4.Factory management译文：CAD和CAM计算机辅助设计（CAD）和计算机辅助制造（CAM）是利用速度快、精度高的数字计算机来完成从工程设计到产品制造的整个过程。CAD/CAM是数字控制和计算机技术等的发展并被联合起来的结果。通过公用数字型数据而联合起来，并随着电子技术的不断发展而充实起来，数字控制和数字计算机已经发展成熟，两者综合起来，就可以将我们带到想往已久的自动化工厂的门口。CAD/CAM计算机功能有以下三个方面：1、 设计/制图；即计算机辅助工程；2、 计划/制度进度表；即管理信息系统；3、制造自动化。一个理想化的CAD/CAM表明用户如何经图像终端和计算机相联系，利用公用数据库内所存的信息来设计和控制制造的整个过程。随着交互式式制图的问世，用户使用编码穿孔卡片组或纸带卷将数据和指令输出入计算机的问题就不复存在。用户不需要具有计算机编程和操作的经验也能使用机床。有了交互式制图，用户就可以用屏幕显示图与计算机进行通信。操作这些系统不要求具有计算机知识，而是在实时情况下与计算机进行通信，即计算机几乎可以瞬时对用户的指令作出响应。在CAD/CAM中，要求解决三维机械设计和制造问题。通过键盘和光笔或其他类似铅笔的装置和计算机交互作用，设计人员在显示屏幕上规定点和线，就可以很快构成屏幕显示的图或模型，这是计算机数据库内所存储的图像的真实再现。用笔划一下或按一下钮，设计人员就可以对整个或部分设计图样进行移动、放大、旋转、翻转、拷贝等。例如，通过按一按钮，设计人员可发出一翻转指令而产生一显示的镜象来制造一对称零件，或可以利用一平移指令来建立线性零件的模型，也可规定一横截面，然后进行线性平移以建立一个平面模型。这些均利用了计算机可又快、又好地重复动作的优点。在设计完成后，可利用计算机存储器内所存的最终几