机电技术专业英语 教学课件 作者 徐起贺 张庆良pata a lesson Twenty two.pptVIP

* 机电技术专业英语 Lesson Twenty-two Text Computeraided 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. Computeraided manufacturing (CAM) means the use of a computer to assist in the manufacture of a part. CAM can be divided in two main classes: ① Online applications, namely, the use of the computer to control manufacturing systems in real time, such as CNC and AC systems of machine tools. ② Offline applications, namely, the use of the computer in production planning and nonreal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 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 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 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 follow 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