机电工程专业英语 教学课件 作者 马佐贤 主编 张雪娟 副主编 Unit2.pptVIP

尚辅网 尚辅网 * * * 尚辅网 Unit 2 Cutting Tools Dialogue 2.1 Cutting Tools 2.2 尚辅网 Dialogue 2.1 尚辅网 What is NC? Job Application Taking part in an interview 尚辅网 磁盘驱动器 Are there any vacancies in your factory? Vacancy n. 空缺；空位 尚辅网 What was your major? major n. 专业 尚辅网 My major was mechanical manufacturing, and I think I am good at operating milling machine. 尚辅网 mechanical manufacturing 机械制造 milling machine 铣床 尚辅网 How to take part in an interview? 尚辅网 The main idea of the dialogue How to take part in interview? Some key words about interview. To know something about milling machine. 尚辅网 Cutting Tools 2.2 Today, I’ll describe the different cutting tools. 尚辅网 Cutting Tools 尚辅网 Metal cutting tools must possess a variety of different properties in order to cut the different metals under varying conditions of severity. hardness at high temperature. 2. wear resistance. 3. impact strength． The properties of cutting tools 尚辅网 All metal cutting tools begin to lose hardness when heated to sufficiently high temperatures． 达到一定高温度时，所有的金属切削刀具便开始软化。 What should we care for when we use the cutting tools? 1.Hardness 2.Degree 3.Selection of a cutting tool material 尚辅网 The various materials from which most metal cutting tools are made 1. Carbon tool steel 2. High-speed steel 3. Cast alloys 4. Cemented carbides 5. Ceramics 6. Diamonds 尚辅网 Tool life，or the number of parts produced by a cutting-tool edge before regrinding is required，is a very important cost factor in manufacturing a part or product. 刀具寿命，即切削刀刃在需要重新打磨之前能加工的零件数，是生产某个零件或产品的重要成本因素 尚辅网 In order to detect the time when a cutting tool should be changed，most modern machines are equipped with indicators that show the horsepower used during the machining operation． detect------ 发现 horsepower-----马力 * *