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

* 机电技术专业英语 Lesson Thirteen Text The importance of machining processes can be emphasized by the fact that every product we use in our daily life has undergone this process either directly or indirectly. (1) In USA, more than ＄100 billions are spent annually on machining and related operations. (2) A large majority (about 80%) of all the machine tools used in the manufacturing industry have undergone metal cutting. These facts show the importance of metal cutting in general manufacturing. It is therefore important to understand the metal cutting process in order to make best use of it. The five basic techniques of machining metal include drilling and boring, turning, planning, milling and grinding. Variations of the five basic techniques are employed to meet special situations. The Basic Machining Techniques Lesson Thirteen New Words and Expressions Lesson Thirteen Lesson Thirteen Notes 1. Boring, on the other hand, involves the finishing of a hole already drilled or cored by means of a rotating, offset, singlepoint tool. 另一方面，镗削则是用一个旋转着的、偏置的单刃刀具对钻削出或铸造出的孔进行精加工。 句中cored意为“型芯铸造”,做后置定语。 2. The essential difference lies in the fact that the cutting tool remains in a fixed position while the work is moved back and forth beneath it. 本质区别在于当工件在刀具下面来回地运动时，刨刀固定在一个位置不动。 句中that引导限定性定语从句，修饰fact。 3. Milling consists of machining a piece of metal by bringing it into contact with a rotating cutting tool which has multiple cuttingedges. 铣削是使工件与旋转的多刃刀具接触来进行加工的。 句中contact with意为“与…接触”；multiple cuttingedges意为“多切削刃，多刃口”。 Lesson Thirteen Notes 4. Other shapes are more complex and may consist of a variety of combinations of flat and curved surfaces depending on the shape given to the cutting–edges of the tool and on the travel path of the tool. 另一些工件的形状就复杂的多，它们是由不同的平面和根据特定刀具切削刃的形状及其运行轨迹而生成的曲面组合而成。 句中depend on…意为“依靠…”, depending on…为现在分词短语作surfaces的非限定性定语。 5. The process is often used for the final finishing to