机械工程导论翻译第三章.doc

3.1 OVERVIEW As introduced in Chapter 1,the primary objective of mechanical engineers is to make machines that work, that are useful, and that improve society in some way. Machines in general,and power transmission equipment in particular, are often constructed of standardized components or building blocks.Just as an electrical engineer might select off-the-shelf resistors,capacitors,and transistors as the elements of a circuit。mechanical engineers have good intuition for specifying the different available types of bearing ,shafts ,gears,belts and other components in their designs.Once the details of a machine have been worked out and the components for it have been selected ,the product then needs to be built.Mechanical engineers also devise manufacturing and assembly processes,and at the conclusion of this chapter we will introduce several common machine tools. A solid appreciation of machine components and tools is valuable at three levels.First,and from our primary standpoint in this textbook,a working knowledge of this hardware is important for you to develop a technical vocabulary!Mechanical engineering has its own precise language,and specialized terms are used to describe the construction and operation of machines.To communicate effectively with other engineers,you will need to learn,adopt,and share that language.Second,having such a background is necessary to select the poper component for an application and to specify the appropriate machine tool for a production process.Of course,it is not possible to list and describe every machine and component that embodies mechanical engineering principles,and that is not our intention in this chapter.However,by examining just a few machine components and tools,you will develop a growing appreciation for practical machinery issues.Finally,this chapter is a good place for you to begin the journey of understanding the inner workings of mechanical hardware.Its intellectually healthy for you to be curious about machines,w