机械设计毕业设计翻译.docx

1、机械设计毕业设计翻译Mechanical EngineeringIntroduction to Mechanical Engineering Mechanical engineering is the branch of engineering that deals with machines and the production of power. It is particularly concerned with forces and motion.History of Mechanical EngineeringThe invention of the steam engine in t

2、he latter part of the 18th century, providing a key source of power for the Industrial Revolution, gave an enormous impetus to the development of machinery of all types. As a result a new major classification of engineering, separate from civil engineering and dealing with tools and machines, develo

3、ped, receiving formal recognition in 1847 in the founding of the Institution of Mechanical Engineers in Birmingham, England. Mechanical engineering has evolved from the practice by the mechanic of an art based largely on trial and error to the application by the professional engineer of the scientif

4、ic method in research, design, and production.The demand for increased efficiency, in the widest sense, is continually raising the quality of work expected from a mechanical engineer and requiring of him a higher degree of education and training. Not only must machines run more economically but capi

5、tal Costs also must be minimized.Fields of Mechanical EngineeringDevelopment of machines for the production of goods the high material standard of living in the developed countries owes much to the machinery made possible by mechanical engineering. The mechanical engineer continually invents machine

6、s to produce goods and develops machine tools of increasing accuracy and complexity to build the machines.The principal lines of development of machinery have been an increase in the speed of operation to obtain high rates of production, improvement in accuracy to obtain quality and economy in the p

7、roduct, and minimization of operating costs. These three requirements have led to the evolution of complex control systems.The most successful production machinery is that in which the mechanical design of the machine is closely integrated with the control system, whether the latter is mechanical or

8、 electrical in nature. A modern transfer line (conveyor) for the manufacture of automobile engines is a good example of the mechanization of a complex series of manufacturing processes. Developments are in hand to automate production machinery further, using computers to store and process the vast a

9、mount of data required for manufacturing a variety of components with a small number of versatile machine tools. One aim is a completely automated machine shop for batch production, operating on a three shift basis but attended by a staff for only one shift per day.Development of machines for the pr

10、oduction of power Production machinery presuppose an ample supply of power. The steam engine provided the first practical means of generating power from heat to augment the old sources of power from muscle, wind, and water One of the first challenges to the new profession of mechanical engineering w

11、as to increase thermal efficiencies and power; this was done principally by the development of the steam turbine and associated large steam boilers. The 20th century has witnessed a continued rapid growth in the power output of turbines for driving electric generators, together with a steady increas

12、e in thermal efficiency and reduction in capital cost per kilowatt of large power stations. Finally, mechanical engineers acquired the resource of nuclear energy, whose application has demanded an exceptional standard of reliability and safety involving the solution of entirely new problems- The con

13、trol systems of large power plank and complete nuclear power stations have become highly sophisticated networks of electronic, fluidic. Electric, hydraulic, and mechanical components, ail of these involving me province of the mechanical engineer.The mechanical engineer is also responsible for the mu

14、ch smaller internal combustion engines, both reciprocating (gasoline and diesel) and rotary (gas-turbine and Wankel) engines, with their widespread transport applications- In the transportation field generally, in air and space as well as on land and sea. the mechanical engineer has created the equi

15、pment and the power plant, collaborating increasingly with the electrical engineer, especially in the development of suitable control systems.Development of military weapons The skills applied to war by the mechanical engineer are similar to those required in civilian applications, though the purpos

16、e is to enhance destructive power rather than to raise creative efficiency. The demands of war have channeled huge resources into technical fields, however, and led to developments that have profound benefits in peace. Jet aircraft and nuclear reactors are notable examples.Biaengineering Bioengineer

17、ing is a relatively new and distinct field of mechanical engineering that includes the provision of machines to replace or augment the functions of the human body and of equipment for use in medical treatment. Artificial limbs have been developed incorporating such lifelike functions as powered moti

18、on and touch feedback. Development is rapid in the direction of artificial spare-part surgery. Sophisticated heart-lung machines and similar equipment permit operations of increasing complexity and permit the vital functions in seriously injured or diseased patients to be maintained.Environmental co

19、ntrol Some of the earliest efforts of mechanical engineers were aimed at controlling mans environment by pumping water to drain or irrigate land and by ventilating mines. The ubiquitous refrigerating and air-conditioning plants of the modem age are based on a reversed heat engine, where the supply o

20、f power pumps heat from the cold region to the warmer exterior.Many of the products of mechanical engineering, together with technological developments in other fields, have side effects on the environment and give rise to noise, the pollution of water and air, and the dereliction of land and scener

21、y. The rate of production, both of goods and power, is rising so rapidly that regeneration by natural forces can no longer keep pace. A rapidly growing field for mechanical engineers and others is environmental control, comprising the development of machines and processes that will produce fewer pol

22、lutants and of new equipment and techniques that can reduce or remove the pollution already generated. Functions of Mechanical EngineeringFour functions of the mechanical engineering, common to all the fields mentioned, are cited. The first is the understanding of and dealing with the bases of mecha

23、nical science. These include dynamics, concerning the relation between forces and motion, such as in vibration; automatic control; thermodynamics, dealing with the relations among the various forms of heat, energy, and power; fluid flow; heat transfer; lubrication; and properties of materials.Second

24、 is the sequence of research, design, and development. This function attempts to bring about the changes necessary to meet present and future needs. Such work requires not only a dear understanding of mechanical science and an ability to analyze a complex system into its basic factors, but also the

25、originality to synthesize and invent.Third is production of products and power, which embraces planning, operation, and maintenance. The goal is to produce the maximum value with the minimum investment and cost while maintaining or enhancing longer term viability and reputation of the enterprise or

26、the institution.Fourth is the coordinating functioning of the mechanical engineering, including management, consulting, and, in some cases, marketing.In all of these functions there is a long continuing trend toward the use of scientific instead of traditional or intuitive methods, an aspect of the

27、ever-growing professionalism of mechanical engineering. Operations research, value engineering, and PABLA (problem analysis by logical approach) are typical titles of such new rationalized approaches. Creativity, however, cannot be rationalized. The ability to take the important and unexpected step

28、that opens up new solutions remains in mechanical engineering, as elsewhere, largely a personal and spontaneous characteristic.The Future of Mechanical EngineeringThe number of mechanical engineers continues to grow as rapidly as ever, while the duration and quality of their training increases. Ther

29、e is a growing: awareness, however, among engineers and in the community at large that the exponential increase in population and living standards is raising formidable problems in pollution of the environment and the exhaustion of natural resources; this clearly heightens the need for all of the te

30、chnical professions to consider the long-term social effects of discoveries and developments. -There will be an increasing demand for mechanical engineering skills to provide for mans needs while reducing to a minimum the consumption of scarce raw materials and maintaining a satisfactory environment

31、.Introduction to DesignThe Meaning of DesignTo design is to formulate a plan for the satisfaction of a human need. The particular need to be satisfied may be quite well defined from the beginning. Here are two examples in which needs are well defined:1. How can we obtain large quantities of power cl

32、eanly, safely, and economical/ without using fossil fuels and without damaging the surface of the earth?2. This gear shaft is giving trouble; there have been eight failures in the last six weeks. Do something about it.On the other hand, the statement of a particular need to be satisfied may be so ne

33、bulous and ill defined that a considerable amount of thought and effort is necessary in ( order to state it dearly as a problem requiring a solution. Here are two examples.-1. Lots of people are killed in airplane accidents.2. In big cities there are too many automobiles on the streets and highways.This second type of design s