机械设计外文文献7页

1、Mechanical DesignJohn ErnstAbstract：A machine is a combination of mechanisms and other components which transforms transmits. Examples are engines, turbines, vehicles, hoists, printing presses, washing machines, and movie cameras. Many of the principles and methods of design that apply to machines a

2、lso apply to manufactured articles that are not true machines. The term "mechanical design" is used in a broader sense than "machine design" to include their design. The motion and structural aspects and the provisions for retention and enclosure are considerations in mechanical

3、design. Applications occur in the field of mechanical engineering, and in other engineering fields as well, all of which require mechanical devices, such as switches, cams, valves, vessels, and mixers.Keywords: Mechanical Design； Mechanisms Design Process；Application 1. The Design ProgressDesigning

4、starts with a need real. Existing apparatus may need improvements in durability, efficiency, weight, speed, or cost. New apparatus may be needed to perform a function previouslyDone by men, such as computation, assembly, or servicing. With the objective wholly or partlyIn the design preliminary stag

5、e, should allow to design the personnel fully to display the creativity, not each kind of restraint. Even if has had many impractical ideas, also can in the design early time, namely in front of the plan blueprint is corrected. Only then, only then does not send to stops up the innovation the mental

6、ity. Usually, must propose several sets of design proposals, and then perform the comparison. Has the possibility very much in the plan which finally designated, has used certain not in plan some ideas which accepts.When the general shape and a few dimensions of the several components become apparen

7、t, analysis can begin in earnest. The analysis will have as its objective satisfactory or superior performance, plus safety and durability with minimum weight, and a competitive cost. Optimum proportions and dimensions will be sought for each critically loaded section, together with a balance betwee

8、n the strengths of the several components. Materials and their treatment will be chosen. These important objectives can be attained only by analysis based upon the principles of mechanics, such as those of static for reaction forces and for the optimum utilization of friction; of dynamics for inerti

9、a, acceleration, and energy; of elasticity and strength of materials for stress and deflection; of physical behavior of materials; and of fluid mechanics for lubrication and hydrodynamic drives. The analyses may be made by the same engineer who conceived the arrangement of mechanisms, or, in a large

10、 company, they may be made by a separate analysis division or research group. Design is a reiterative and cooperative process, whether done formally or informally, and the analyst can contribute to phases other than his own. Product design requires much research and development. Many Concepts of an

11、idea must be studied, tried, and then either used or discarded. Although the content of each engineering problem is unique, the designers follow the similar process to solve the problems. Product liability suits designers and forced in material selection, using the best program. In the process of ma

12、terial, the most common problems for five (a) don't understand or not use about the latest application materials to the best information, (b) failed to foresee and consider the reasonable use material may (such as possible, designers should further forecast and consider due to improper use produ

13、cts. In recent years, many products liability in litigation, the use of products and hurt the plaintiff accused manufacturer, and won the decision), (c) of the materials used all or some of the data, data, especially when the uncertainty long-term performance data is so, (d) quality control method i

14、s not suitable and unproven, (e) by some completely incompetent persons choose materials.Through to the above five questions analysis, may obtain these questions is does not have the sufficient reason existence the conclusion. May for avoid these questions to these questions research analyses the ap

15、pearance indicating the direction. Although uses the best choice of material method not to be able to avoid having the product responsibility lawsuit, designs the personnel and the industry carries on the choice of material according to the suitable procedure, may greatly reduce the lawsuit the quan

16、tity. May see from the above discussion, the choice material people should to the material nature, the characteristic and the processing method have comprehensive and the basic understanding. Finally, a design based upon function, and a prototype may be built. If its tests are satisfactory, the init

17、ial design will undergo certain modifications that enable it to be manufactured in quantity at a lower cost. During subsequent years of manufacture and service, the design is likely to undergo changes as new ideas are conceived or as further analyses based upon tests and experience indicate alterati

18、ons. Sales appeal.2. Some Rules for DesignIn this section it is suggested that, applied with a creative attitude, analyses can lead to important improvements and to the conception and perfection of alternate, perhaps more functional, economical, and durable products. To stimulate creative thought, t

19、he following rules are suggested for the designer and analyst. The first six rules are particularly applicable for the analyst.（1）A creative use of need of physical properties and control process.(2）Recognize functional loads and their significance.(3) Anticipate unintentional loads.(4) Devise more

20、favorable loading conditions.(5) Provide for favorable stress distribution and stiffness with minimum weight.(6) Use basic equations to proportion and optimize dimensions.（7）Choose materials for a combination of properties.（8）Select carefully, stock and integral components.（9）Modify a functional des

21、ign to fit the manufacturing process and reduce cost.（10）Provide for accurate location and noninterference of parts in assembly.Machinery design covers the following contents.(1).Provides an introduction to the design process, problem formulation, and safety factors.(2).Reviews the material properti

22、es and static and dynamic loading analysis, Including beam, vibration and impact loading.(3) Reviews the fundamentals of stress and defection analysis.(4)Introduces fatigue-failure theory with the emphasis on stress-life approaches to high-cycle fatigue design, which is commonly used in the design o

23、f rotation machinery.(5) Discusses thoroughly the phenomena of wear mechanisms, surface contact stresses, and surface fatigue.(6) Investigates shaft design using the fatigue-analysis techniques.(7) Discusses fluid-film and rolling-element bearing theory and application(8) Gives a thorough introducti

24、on to the kinematics, design and stress analysis of spur gears, and a simple introduction to helical, bevel, and worm gearing.(9) Discusses spring design including compression, extension and torsion springs.(10) Deals with screws and fasteners including power screw and preload fasteners.(11) Introdu

25、ces the design and specification of disk and drum clutches and brakes.The complete design of a machine is a complex process. The machine design is a creative work. Project engineer not only must have the creativity in the work, but also must in aspect and so on mechanical drawing, kinematics, engine

26、ering material, materials mechanics and machine manufacture technology has the deep elementary knowledge.One of the first steps in the design of any product is to select the material from which each part is to be made. Numerous materials are available to today's designers. The function of the pr

27、oduct, its appearance, the cost of the material, and the cost of fabrication are important in making a selection. A careful evaluation of the properties of a. material must be made prior to any calculations.Careful calculations are necessary to ensure the validity of a design. In case of any part fa

28、ilures, it is desirable to know what was done in originally designing the defective components. The checking of calculations (and drawing dimensions) is of utmost importance. The misplacement of one decimal point can ruin an otherwise acceptable project. All aspects of design work should be checked

29、and rechecked. The computer is a tool helpful to mechanical designers to lighten tedious calculations, and provide extended analysis of available data. Interactive systems, based on computer capabilities, have made possible the concepts of computer aided design (CAD) and computer-aided manufacturing

30、 (CAM). How does the psychologist frequently discuss causes the machine which the people adapts them to operate. A design personnels basic responsibility is diligently causes the machine to adapt the people. This certainly is not an easy work, because certainly does not have to all people to say in

31、fact all is the most superior operating area and the operating process. Another important question, project engineer must be able to carry on the exchange and the consultation with other concerned personnel. In the initial stage, designs the personnel to have to carry on the exchange and the consult

32、ation on the preliminary design with the administrative personnel, and is approved. This generally is through the oral discussion, the schematic diagram and the writing material carries on. If front sues, the machine design goal is the production can meet the human need the product. The invention, t

33、he discovery and technical knowledge itself certainly not necessarily can bring the advantage to the humanity, only has when they are applied can produce on the product the benefit. Thus, should realize to carries on before the design in a specific product, must first determine whether the people do

34、 need this kind of productMust regard as the machine design is the machine design personnel carries on using creative ability the product design, the system analysis and a formulation product manufacture technology good opportunity. Grasps the project elementary knowledge to have to memorize some da

35、ta and the formula is more important than. The merely service data and the formula is insufficient to the completely decision which makes in a good design needs. On the other hand, should be earnest precisely carries on all operations. For example, even if places wrong a decimal point position, also

36、 can cause the correct design to turn wrongly.Good design personnel should dare to propose the new idea moreover is willing to undertake the certain risk, when the new method is not suitable, use original method. Therefore, designs the personnel to have to have to have the patience, because spends t

37、he time and the endeavor certainly cannot guarantee brings successfully. A brand-new design, the request screen abandons absolutely many, knows very well the method for the people. Because many person of conservativeness does this certainly is not an easy matter. A mechanical designer should unceasi

38、ngly explore the improvement existing product the method, should earnestly choose originally, the process confirmation principle of design in this process, with has not unified it after the confirmation new idea.Human life can not be separated from the machinery, it is everywhere, but for the mechan

39、ical manufacturing, production, and its development and future, we know little about. After this semester, I have more knowledge and understanding of the profession of the mechanical.From the primitive society of early human use such as axes, knives and other simple tools, to a simple lever, pulley,

40、 human bicycles, animal-Kip Shum car tools, developed to a more complex hydraulic drive, wind-driven Shuinian and windmills morecomplex machinery. After the 18th century British Industrial Revolution, the steam engine, internal combustion engines, electric motors, mechanical power source for the rap

41、id development of manufacturing, transport, human beings began to enter the modern civilized society. The 20th century, the computer issuing automatic control technology, information technology, infectious organic combination of technology, so that the machinery is fully modernized phase. Robotics,

42、CNC machine tools, high-speed delivery vehicles, heavy machinery and the large number of advanced machinery and equipment to accelerate the prosperity and progress of human society, humans can travel into space, landing on the moon, you can explore the vast depths of the sea, to live and pass below

43、the surface all of which can not be separated from the machinery, the development of the machinery into the intelligent stage. Machinery has become one of the five elements of production and services of modern society. The history of the development of the mechanical history of the development of hu

44、man civilization. In ancient Chinese mechanical engineering, invention and creativity is very brilliant, such as grinding technology, metal smelting technology. China's machinery manufacturing industry developed after 1949. After the founding of new China, the tremendous achievements of Chinas economy are inseparable from the progress of the manufacturing sector. After decades of struggle, China's manufacturing components with considerable scale and lev