《机械设计外文文献.docx》由会员分享，可在线阅读，更多相关《机械设计外文文献.docx（12页珍藏版）》请在三一文库上搜索。
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 design. Applications occ
3、ur 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 starts with a need real.
4、 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 stage, should allow to desig
5、n 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 mentality. Usually, must propo
6、se 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 apparent, analysis can begin in
7、 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 between the strengths of the s
8、everal 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 dynamics1 / 6for inertia, acceleration, and
9、 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 company, they may b
10、e 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 idea must be studied
11、, 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 material, the most comm
12、on problems for five (a) dont 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 products. In recent years, many
13、 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 is not suitable and unprove
14、n, (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 appearance indicating the di
15、rection. 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 quantity.May see from the abov
16、e 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 initial design will undergo cert
17、ain 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 as2 / 6further analyses based upon tests and experience indicate alterations. Sales appeal.2. Som
18、e 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, the following rules are su
19、ggested 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 favorable loading condit
20、ions.(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 design to fit the manuf
21、acturing 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 properties and static an
22、d dynamic loading analysis, Including beam, vibration and impact loading.(1) Reviews the fundamentals of stress and defection analysis.(1) Introduces fatigue-failure theory with the emphasis on stress-life approaches to high-cycle fatigue design, which is commonly used in the design of rotation mach
23、inery.(1) Discusses thoroughly the phenomena of wear mechanisms, surface contact stresses, and surface fatigue.(2) Investigates shaft design using the fatigue-analysis techniques.(3) Discusses fluid-film and rolling-element bearing theory and application(4) Gives a thorough introduction to the kinem
24、atics, design and stress analysis of spur gears, and a simple introduction to helical, bevel, and worm gearing.(5) Discusses spring design including compression, extension and torsion springs.3 / 6(10) Deals with screws and fasteners including power screw and preload fasteners.(11) Introduces the de
25、sign 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, engineering mate
26、rial, 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 todays designers. The function of the product, its appe
27、arance, 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 failures, it is d
28、esirable 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 and rechecked.T
29、he 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 (CAM). How does
30、 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 fact all is the
31、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 consultation on the pre
32、liminary 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, the discovery and
33、technical knowledge itself certainly not4 / 6necessarily 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 need this ki
34、nd 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 data and the fo
35、rmula 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 can cause th
36、e correct design to turn wrongly.G ood 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 the time and
37、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 unceasingly explore
38、 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.H uman life can not be separated from the machinery, it is everywhere, but for the mechanical manufa
39、cturing, 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, human bicy
40、cles, 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 rapid developm
41、ent 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, so5 / 6that the machinery is fully modernized phase. Robotics, CNC mac
42、hine 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 the sur
43、face 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 human civ
44、ilization.In ancient Chinese mechanical engineering, invention and creativity is verybrilliant, such as grinding technology, metal smelting technology. Chinas machinery manufacturing industry developed after 1949. After the founding of new China, the tremendous achievements of Chinas economy are ins
45、eparable from the progress of the manufacturing sector. After decades of struggle, Chinas manufacturing components with considerable scale and level of manufacturing systems, today China have become a remarkable manufacturing country. Machinery manufacturing industry overall scale of production is c
46、onstantly increasing, machinery manufacturing is more than 100 industry, 8.57 million enterprises (large enterprises accounted for 1%) and 60,000 kinds of products a complete range of industrial system. For six consecutive years in Chinas largest export commodity status, the machinery industry produ
47、ction capacity is 2600 times that of the liberation of the world 5, the machine has a world, vehicle production in the world 4.But we still need to clearly recognize that China is a big manufacturing country, far from being a manufacturing powerhouse. The overall size of the added value of product t
48、echnology and per capita labor efficiency is far better than the United States, Japan and other manufacturing power. Therefore, the task of development of Chinas manufacturing industry a long way to go. With the diversification of the high-tech development and social needs of the industrial producti
49、on rapidly toward large-scale, integrated and complex, so that the modern industrial machinery industry is facing new opportunities and challenges, and more emphasis on the creativity and the efficiency of the workers. Therefore need to continuously enhance the level of Chinas Mechanical Design Manufacturing and Automation, thereby contributing to the development of Chinas machinery