机械设计毕业论文中英文资料外文翻译文献.doc

中英文资料 机械设计中英文资料外文翻译文献Fundamentals Of Machinery DesignThis introductory chapter is a general survey of machinery designFirst it presentsthe definition and major role of machinery design，the relationship between machineryand its componentsThen it gives an overview of machinery design as a fundamentalcourse and outlines a general procedure of machinery design followed by all theengineersFinally, it lists the contents of the course and the primary goals to beachieved11 The role of machinery designMachinery design is to formulate all engineering planEngineering in essence is toutilize the existing resources and natural law to benefit humanityAs a major segmentof engineerin，machinery design involves a range of disciplines inmaterials，mechanics，heat，flow，control，electronics and productionAlthough many hightechnologies are computerized and automated，and are rapidly merged into Our dailylife，machines are indispensable for various special work that is difficult orimpracticable to be carried out by humanMoreover，machinery can significantlyimprove efficiency and quality of production，which is crucial in current competitiveglobal marketIn the modern industrialized world，the wealth and living standards of a nation areclosely linked with their capabilities to design and manufacture engineeringproductsIt can be claimed that the advancement of machinery design andmanufacturing can remarkable promote the overall level of a countrysindustrializationThose nations，who do not perform well in design and manufacturefields，are not competitive in world marketsIt is evident that several countries thatused to be leaders in the design and manufacturing sectors until the l 960s and the1 970s had，by the l990s，slipped back and lost their leadershipOn the contrary, ourCountry is rapidly picking up her position in manufacturing industry since the l 9 80sand is playing a more and more vital role in the global marketTo accelerate such anindustrializing process of our country, highly skilled design engineers having extensiveknowledge and expertise are neededThat is why the course of machinery design is ofgreat significance for students of engineeringThe course of machinery design is considerable different from those backgroundsubjects in science and mathematicsFor many students，it is perhaps one of theirbasic professional engineering courses concerned with obtaining solutions to practicalproblem sDefinitely these solutions must clearly represent an understanding of theunderlying science，usually such an understanding may not be sufficient，empiricalknowledge or engineering judgement has to be also involvedFurthermore，due to beprofessional nature of this subject，most design problems may not have one rightsolutionNevertheless it is achievable to determine a better design from all feasiblesolutions12 Machinery and componentsA state-of-the-art machine may encompass all or part ofmechanical，electrical，control，sensor，monitoring and lubricating subsystemsIn termsof the functions of those parts，the machine can also be viewed to be comprised ofpower，transmission，execution and controlmanipulation partsRegardless of thecomplexity, however，the major functional part may be still the mechanical systemForconvenience of analysis，the mechanical system can be decomposed int0mechanismsthat are designed to execute some specific tasksAnd the mechanism can be furtherdecomposed into mechanical componentsIn this sense，the mechanical componentsare the fundamental elements of machineryOn the whole，mechanical components can be classified as universal and specialcomponentsBolts，gear and chains are the typical examples of the universalcomponents which can be used extensively in different machines across variousindustrial sectorsTurbine blades，crankshaft and aircraft propeller are the examples ofthe special components，which Can be used extensively in different machines acrossvarious industrial sectorsturbine blades，crankshaft and aircraft propeller arethe examples of the special components，which are designed for some specificpurposesIn addition to this，if a number of components aremanufactured，assembled and even equipped as an individual system，egleaf spring setin a vehicle，it is also termed as a mechanical partA good machine definitely requires quality individual componentsThus，the designof components is very importantWhen designing a machine，on the otherhand，engineers invariably find that requirements and constraints of its components areinterrelatedAs a local portion，the component is expected to play a certain role on themachine and therefore must be appropriately restrained by the whole systemThedesign of a gear drive in a speedreducer，for instance，depends upon not only thestrength and stiffness，but also the space available for the gears in the shaft andrelation with other transmission driveThis means that the design of the mechanicalcomponents inevitably requires a whole view in the whole systemDue to relationship between a machine and its components，the process ofmachinery design usually covers interconnected designs of machine，parts，andcomponentsAny modification and adjustment in one component may considerablyaffect the designs of other components or partsTo present the best possible designsolution，the iteration of evaluation，analysis and optimization across all the processseem indispensable13 Overview of machinery designThis course is primarily concerned with the design of specific components ofmachines or mechanical systemsCompetence in this area is basic to the considerationand synthesis of complete machines and systems in subsequent courses andprofessional practiceIt Can be seen that even the design of a single bolt or springneeds the designers thorough understanding of the principles and methods ofmachinery design together with empirical information，good judgment and even adegre3e of ingenuity in order to produce the best product for the society todayIt is natural that designing engineers give first consideration to the functional andeconomic aspects of new products or devicesMachinery design needs to ensure safetyand reliability in a prescribed lifetimeTo address such a problem conventionally，thetechnical consideration of the mechanical component design is largely centeredaround two main areas of concerns：(1) strength-stiffness-stability criteria involvingthe bulk of a solid member and (2) surface phenomena includingfriction，lubrication，weal7，and environmental deteriorationHowever，in comparisonwith such relatively straightforward computations as stress and deflection，the designdetermination of safety and reliability is likely to be an elusive and indefinitematter，complicated by psychological and sociological factorsIt must be kept in mindthat safety and reliability are inherently relative to each other，and the value judgmentsmust be made with regard to tradeoffs between safety，reliability，cost，weight，and soforthOn the other hand，a practical design needs to reflect clearly manufacturability andeconomy to make sure of the lowest cost as well as the least consumption of energyand materialsOtherwise，the products or devices designed will be of no furtherengineering or commercial interestsNowadays，the simultaneous considerations ofmanufacturing and assembly factors phases including design，manufacturing，inspection，asassembly and other is considered in such a parallel fashion that the quality and cost arebest satisfied concurrentlyIn addition to these traditionally technological and economic considerationsfundamental to the design and development of mechanical components andsystems，the modern engineers have become increasingly concerned with the broaderconsiderations of sustainability，ecology，aesthetics，ergonomics，maintainability，andoverall quality of lifeIt is clear that a greater than ever engineering effort is beingrecently devoted to broader considerations relating to the influences of engineeredproducts on people as well as on the environmentThe following is a list of general factors for engineers to consider in the designprocess，which from a different viewpoint shows us a panoramic picture with regardto the design-related activities and tasks(1) Cost of manufacturingWill the selling price be competitive? Are therecheaper ways of manufacturing the machine? Could other materials be used? Are anyspecial tools，dies, jigs，or fixtures needed? Can it easily be inspected? Can theworkshop produce it? Is heat treatment necessary? Can parts be easily welded?第4页 Cost of operationAre power requirements too large? What type of fuelwill be used? Will operation cost be less expensive?(3) Cost of maintenanceAre all parts easily accessible? Are access panelsneeded? Can common tools be used? Can replacement parts be available?(4) Safety featuresIs a suitable factor of safety used? Does the safety factormeet existing codes? Are fuses，guards，andor safety valves used? Are shear pinsneeded? Is there any radiation hazard? Any overlooked ”stress raiser”? Are there anydangerous fumes?(5) Packaging and transportationCan the machine be readily packaged forshipping without breakage? Is its size suitable to parcel post regulations, freight cardimensions，or trailer truck size? Are shipping bolts necessary? Is its center of gravityin a desirable location?(6) LubricationDoes the system need periodic checking? Is it automatic? Isit a sealed system?(7) MaterialsAre chemical，physical，and mechanical properties suitable toits use? Is corrosion a factor? Will the materials withstand impact? Is thermal orelectrical conductivity important? Will high or low temperatures present any problem?Will design stress keep parts reasonable in size?(8) StrengthHave dimensions of components been carefully calculated? Haveall the load cases be taken into account? Have the stress concentrations been carefullyconsidered? Has the fatigue effect be computed?(9) KinematicsDoes it provide necessary motion for moving parts? Arerotational speeds reasonable? Could linkages replace cams? What will be the bestchoice，the belts，chains or gears? Is intermittent motion needed?(10) StylingDoes the color have eye appeal? Is the sharp desirable? Is themachine well proportioned? Are the calibrations on dials easily read? Are the controlseasy to operate?(11) DrawingsAre standardized parts used? Are the tolerances realistic? Is thesurface finish over-specified? Must the design conform to any standards? (12) ErgonomicsHas the operator of the equipment been considered? Are thecontrols conveniently located to avoid operator fatigue? Are knobs，grab bars，handwheels，levers，and dial calibrations of proper size to fit the average operator?14 A general procedure of machinery designWhatever design tasks the designers are expected to complete，theyalways，consciously or unconsciously，follow the similar process which goes asfollows：(1)Studies of feasibilityAfter understanding the product functions，operational conditions，manufacturingconstraints and key technologies，go on to uncover existing solutions to some similarproblems so as to clarify the design tasks，understand the needs，present the majorfunctional parameters and evaluate design tasks，proposal of design aims，andfeasibility analysis(2) Conceptual design of configurationAccording to the design of tasks and functional parameter，designs need toextensively search for various feasible configurations and alternativesForconvenience，usually，the system can be analyzed comprehensively by decomposing itinto power sources，transmission and work mechanismsA great effort needs to be devoted to the analysis and synthesis of these differentpartsFor example，the power source may be selected from motor，engine andturbineEach power source may have a range of power and kinematicalparameters Similarly, power trains may have numerous optionsavailable，egbelts，chains，gears，worm gears and many otherdrivesObviously selecting an appropriate configuration would guarantee the Successof the whole design and the quality of the productsTo make a best possibledecision，an iterative process is normally required to select，analyze，compare andevaluate different configurationsAt this stage，the goals involve sketching ofconfiguration，determination of kinematical mechanisms，and evaluation offunctional parameter(power and kinematics) (3)Detailed technical designBased on the design of configuration and parameters，a number ofassembly and component drawings will be completed to reflect the detaileddesign including kinematics，power，strength，stiffness，dynamics，stability，fatigue and SO onConsideration should also be given to manufacturingfactors by presenting structural details，materials，and both geometricand dimensional tolerancesThis part of work will also be carried out ina repeated process in drawings，calculation，evaluation and modificationuntil a best possible design is achievedThe goal at this stage is tocomplete assembly and component drawings，structural details，designcalculations and detailed technical documentations(4)Modification of designAfter the design is completed，a prototype is usually made for a more realisticphysical assessment of the design qualityThis will help correct any drawback or faultthat may be overlooked or neglected during the design processAt this stage，the goalis to correct the design imperfection，test the potential manufacturing or assemblyflaws and refine /improve design15 Contents and tasks of the courseThe course Machinery Design will cover the following contents：(1)Preliminariesthe fundamental principles of machinery andComponents design，design theory，selection of materials，structure，friction，wear and lubrication(2)Connectionsandjointsthreadfasteners，keys，rivets，welds，bondsand adhesive and interference joints(3)Transmissionscrews，chains，belts，gears，worms，bevelgearsAnd helical gears(4)Shaftsystemrollingcontactbearings，slidingbearings，clutches，couplings，shafts，axles and spindles (5)Other part ssprings，housings and frame sThe course centers on engineering design of mechanical components andis in a category of fundamental methodology and procedureIt is notfeasible or realistic for the students to become involved in the detaileddesign considerations associated with all machine componentsInstead，thetextbook has its main focus on some typical components and partsHowever，the methodologies and procedures to be developed in this course can beextended to more design casesFor this reason，an emphasis will be laidon the methods and procedure s over the course so that the student s willgain a certain competence in applying these skills and knowledge todesigning more mechanical componentsAs a professional fundamental course，it will help students to acquirea sol id knowledge of mechanical design and engineering awarenessMorespecifically，the course will help to develop the students competence inthe following facets：Competence of creative design and solving practical problem；Competence of team work as well as professional presentation andcommunications：Competence of apprehending the design principles andregulations，synthesizing the knowledge to develop new designs：Competence of engineering research as well as using designcode s，handbooks，standards and references：Competence of doing experiments to solve problem in the design oftypical components：Competence of understanding newly introduced technological as well aseconomic codes to update the knowledge of machinery designIt is worth noticing that the course will also integrate a number ofpreceding relevant subjects at the universitylevel ，includingmathematics ，physics，electronics，chemistry，solid mechanics，fluidmechanics，heat transfer，thermodynamics，computin9，and so forthIt willcombine the knowledge about science and professional skills to solve somepractical engineering problems，which will significantly advancestudents competence and enlarge their vision to the professionalengineersIt should be pointed out that skills and experience could beacquired only by a great deal of practicehour after monotonous hour ofit It is acknowledged universally that nothing worthwhile in life canbe achieved without hard work，often tedious，dull and monotonous，andengineering is no exception机械设计的基本原则这个导言章节是对机械设计的一个纵览。第一它给出定义并且指出机械设计的重要角色，以及机械与其组成部分之间的关系然后它给出了机械设计的概述作为一基础的课程和列出所有工程师都应该遵循的机械设计的一般程序最后，它列出课程的目录和主要要达成的目标。1.1个机械设计的角色机械设计用来规划述所有的机械示意图。工程学本质上是利用现有的资源河自然法则为人类谋利。作为工程学的一个主要部分，机械设计在材料、力学、热、流量、控制、电子学和生产方面有一系列的原则。虽然许多高技术都采用计算机化和自动化，并且迅速的融入我们的日常生活，机器是各种不同的特殊工作不可缺少的，那些特殊工作对人类来说是非常难执行的或者是不可执行的。此外，机器可以明显的改良改良生产的效率和品质，效率和品质在现在竞争强烈的国际市场上起着决定性作用。在现代的工业化的世界中，一个国家的财富和生活水平是与他们的设计和制造机械产品紧密相连的。可以断言，机械产品的设计和制造的提高能明显的促进一个国家的工业化总体水平。这些在设计和制造领域发展不好的国家，在国际市场中竞争力差。明显的，一些国家曾经是设计和制造业中的领头羊，直到七八十年代，到了九十年代他们后退并且失去了他们的领导地位。相反的，自从八十年代以后，国家正在快速地发展占据她在制造业中的位置并且在国际市场中担任一个越来越重要的角色。为了加速我国的工业化进程，有广泛知识和专长的高技术设计工程师是不可或缺的。那就是机械设计课程对学习机械的学生的重要的原因。机械设计的课程与科学和数学中背景科学有相当多的不同。对许多学生来说，它或许是他们用来解决相关实际问题的基本的专业工程课程。可以明确的是，这些解决办法一定可以明确的描绘对基础科学的一种理解，通常这样的理解可能不够充分，经验得来的知识或工程判断同样也被牵涉在内。此外，由于这么学科的专业性，大多数的设计问题可能没有一个正确的解决方式。然而，从所有可行的解决办法中确定一个更好的设计是可取的。1.2机械和组成部分一个技术发展水平机器可能包含所有的或部分机械、电力有关，控制、感应器，监听和加油子系统。就这些部分的功能来说，机器也可以看作是由动力、传动、实行和控制处理零配件组成的。不管其复杂性，然而，其主要功能部分可以依然是机械系统。为了方便分析，机械系统能够分成运行一些特定任务的机械装置。机械装置可以进一步分成机械构件。在这种情况下，机械构件是机械的基础元素。总的来说，机械构件可以归类为普通构件和特殊构件。螺拴，传动机构和链条是能广泛地用于不同的机械构件横断面的不同的普通构件典型例子。轮机刀刃，曲柄桥和航空器螺旋浆是广泛地用于不同的机械构件横断面的不同的特殊构件典型例子轮机刀刃，曲柄桥和航空器航空器螺旋浆是为特殊目的制造的特殊构件的例子。除此之外，如果许多的构件制