機械設(shè)計外文文獻(xiàn)翻譯、中英文翻譯、外文翻譯

外文原文： Mechanical design According to user requirements of special mechanical working principle, structure, movement, power and energy transmission, various parts of the material and shape size, lubrication methods for design, analysis and calculation and mechanical design Translate them into a specific description to be made based on the workingprocess. Mechanical design is an important part of mechanical engineering, machinery is produced in the first step, is to determine the mechanical properties of the main factors. Mechanical design goal is: in various limited conditions (such as materials, processing ability, theory and calculation method of design of the best machinery ), i.e. to make optimization design. Optimization design to consider the many requirements, generally : the best performance, the minimum cost, the minimum size and weight, use the reliability, minimum consumption and the minimum environmental pollution. These requirements are often contradictory, but their relative importance for the mechanical type and use vary. The designers task is to weigh up one thing against another according to the specific circumstance, take all factors into consideration, make the design of the mechanical optimal comprehensive technical and economic effect. In the past, optimization design depends on the designers knowledge, experience and vision. As the base of mechanical engineering theory and the value engineering, systems analysis and other new disciplines in the development, manufacture and use of technical economy the accumulation of data, as well as computer application, optimize gradually abandon the subjective judgment and rely on scientific computing. In the service of different industry different machinery, application of different working principle, requires a different function and characteristic. Industrial machinery design, especially the whole and the entire system of mechanical design, must be attached to the relevant industrial technology to form an independent discipline. So the design of agricultural machinery, mining machinery, textile machinery, automobile design design design, ship design, design of pump, compressor, turbine design, engine design, machine design, professional mechanical design branch. However, many of these professional design and many common technologies, such as the analysis and synthesis of mechanisms, and can analysis and calculation, engineering materials, strength of materials, transmission, lubrication, sealing, and standardization, reliability, process optimization. In addition, there are research design work of the inherent law and the rationality of the design methods and steps of the new design methodology. The mechanical design of the general technology and rational design methodology brings together into an independent, comprehensive mechanical design is mechanical engineering practice and education workers are working hard. A machine quality basically depends on the quality of design. Manufacturing process on the quality of the machine the role, essence is to realize the design required quality. Therefore, the machines design phase is the key decision machine. Mechanical design The discussion of the design process refers only to the narrow sense of technical design process. It is a creative process, but also a try best to use the successful experience of the job. Be well to the inheritance and innovation to combine, in order to design a high quality machine. As a complete machine, it is a complex system. To improve the design quality, must have a scientific design program. Although it is not possible for a list of valid in all cases only program, but, according to the long term experience, a machine design process basically can be as shown in Table 2- 1. 1for each stage are respectively brief description. ( a ) the planning stage in accordance with the production or life presents the need to design new machines, the planning stage is a stage of preparation. At this time, to design the machines only a vague notion. In the planning stages, to deal with the design of the machine needs to do the full investigation and analysis. Through the analysis, to further clarify the machine the function that should have, and for the subsequent decision proposed by the environmental, economic, and processing time and other aspects of the identified constraints. Based on this, clearly written assignments on the overall requirements and design details, finally forms the design task book, as the stage summary. The design task book generally should include : the machine function, economy and environmental protection estimates, manufacturing requirements with respect to roughly estimate, basic requirements, and completed the task of design is expected duration. At this point, the requirements and conditions in general can only give a reasonable range, but not the exact number. For example can be used must meet the requirements, minimum requirements, hoping to reach the requirements shall be identified. ( two) scheme design stage the stage of design play a key role. In this one phase is also fully demonstrated the design work have multiple solutions ( solution ) features. The function of the machine analysis, is to design of the proposed machine function must meet the requirements of the minimum requirements, and hope to achieve the requirements of comprehensive analysis, namely, these functions can be realized, a number of features with no contradiction, can substitute each other. Finally determines the functional parameters, as the basis for further design. In this step, want appropriate processing need and possibility, the ideal and the reality, development goals and the goals may arise between the contradictory problem. To determine the functional parameters, then propose possible solutions, which is made possible by the plan. Seek solution, according to the driving part, a transmission part and execution part are respectively discussed. , more commonly used method is to first from the operative portion began to discuss. Discuss machine execution part, the first is about the working principle of selection. For example, the design and manufacture of screw machine, its working principle can be used in the cylindrical blank by turning thread approach, can also be used in the cylindrical blanks with thread rolling die rolling thread approach. It puts forward two kinds of different working principles. Its working principle is different, of course, the design of the machine will fundamentally different. Special is to be stressed, must continue to research and development o f new working principle. It is an important way of the development of design technology. According to the different working principle, can develop a variety of different execution mechanism scheme. For example, only the thread cutting, can use the workpiece can only rotate and tool for linear motion to the cutting thread ( such as in lathe cutting thread ), also can make the workpiece is fixed and the cutter to rotate and move to the cutting thread ( such as die processing thread ). That is to say, even for the same kind of work principle, also may have several different structural schemes. The original motivation scheme also can have multiple choice. Because of the power supply of the universality and the electric drive technology development, it can be said that the vast majority of the fixed mechanical is preferred choice as prime mover part of motor. The original motivation for transport, the main thermal engineering machinery and agricultural machinery. Even with the motor as the motive, there are both AC and DC selection, high speed and low speed selection. The transmission part of the scheme is more complicated and diverse. For the same transmission task, by a variety of institutions and different body combination to complete. Therefore, if the prime mover Part IV, said the number of possible schemes, N2and N3respectively representing the transmission part and the execution part number of possible schemes, then the machine the overall number of possible schemes of Ni x N2x N3. The above is only on the machine is composed of three main parts to discuss the. Sometimes, also considering the configuration assistant system, in this regard, books no longer discuss. In so many programmes, technically feasible only a few. On the several feasible solutions, from technology and economy and environmental protection and other aspects of a comprehensive evaluation. Evaluation of the method are many, now with economic evaluation for example omitted description. According to the economic evaluation, it is necessary to take into account the design and manufacture of economy, should cost taken into account when using economy. If the machine structure is more complex, its design and manufacture cost is relatively increased, but its function will be more complete, productivity is higher, so the use of economy is also good. In turn, the structure is relatively simple, the function is not complete machinery, design and manufacturing cost is less, but the use of cost will increase. Evaluation of structural scheme design and manufacturing economy, can also be used to represent the cost of unit efficiency. For example, the unit output power cost, unit cost. Machine evaluation, but also on the machine reliability analysis, the reliability as an evaluation index. From the point of view of reliability, the blind pursuit of complex structure is often not wise. Generally speaking, the system is more complex, then the system reliability is lower. In order to improve the reliability of complex systems, it is necessary to increase the parallel system, which will inevitably increase the cost of the machine. The environmental protection is also design must be carefully considered important aspects. Have a bad effect on the environment of the technical scheme, must detailed analysis, and puts forward the technical maturity of the solution. Through the evaluation, the final decision, according to determine a next step technology design of the schematic diagram or kinematic diagram of mechanism. In the program design phase, to correctly handle the relationship between reference and innovation. Similar machines ought to draw lessons from the successful precedent, originally weak and inconsistent with the current task demands of the part should be improved or changed. We should not only actively innovation, against conservative and copy the original design, but also against a novelty and reasonable original experience abandoned the two wrong tendencies. ( three) the technical design stage design goal was to generate assembly sketches and assembly sketches. The sketch design identified the components and parts of the form and basic size, including connections between components, spare, parts of the form and basic size. The final drawing parts drawing, parts and assembly drawings and assembly drawings. In order to determine the main parts of the basic size, must do the following:1) the kinematic design of machines. According to determine the structure scheme, determine the driver parameters ( power, speed, linear speed etc. ). Then do the kinematics calculation, thereby determining the motion components of movement parameters ( speed, velocity, acceleration ). 2) the machine dynamics calculation. Combined with the structure and motion parameters, calculation of the main part of the load size and characteristics. The calculated load, the part is designed, which is applied to parts of the nominal ( or nominal ) load. 3) parts of the working capability design. The known major parts by the nominal load size and characteristics, can be zero, parts of the preliminary design. The designs are based on the ability to work standards, should be zero, parts of the general failure situation, job characteristics, environmental conditions and reasonably develop, generally have the strength, stiffness, vibration, life criterion. Through calculation and comparison, then decided to spare, parts of the basic size. 4) assembly sketches and general assembly sketch design. According to the main components, the basic size, design a component assembly sketches and assembly sketches. The sketch of all parts of the shape and size of the structured design. In this step, need good coordination among the various parts of the structure and size, to consider a comprehensive design of zero, parts of the process of the structure, so that all the parts have the most reasonable configuration. 5) the main parts of the check. There are some parts, in the above third ) step due to the specific structure of undetermined, difficult to conduct detailed work capacity calculation, we can only do a preliminary calculation and design. In the draw assembly design and assembly sketches, all parts of the structure and size are known, the mutually abutting the relations between components also known as. Only then, can be more accurately determined action on the part of load, decisions affecting parts working ability detail factor. Only on this condition, it can and must be for something important or shape and stress condition of complex parts for accurate calculation of. According to the check results, repeatedly modify parts of the structure and size, until satisfied. In the technical design of the various steps in, nearly thirty or forty years with the development of the optimization design technology, more and more shows it can make the selection of structural parameters to achieve the best capacity. Some new numerical method, such as finite element method, can make previously difficult to quantitative calculation problems in obtaining excellent approximation calculation results. For a few very important, the structure is complex and expensive parts, where necessary, must use the model test method to the design, namely according to the preliminary design drawings to create a model, through the experiment, to find out the weak parts of the structure or the redundant section size, thus enhance or reduce the modification to the original design, finally achieving the perfect degree. Mechanical reliability theory for the technical design stage, according to the viewpoint of reliability design of zero, parts of structure and its parameters to make it meet the requirement of reliability evaluation, put forward the improvement design is proposed, which can further improve the quality of machine design. These new design methods and concepts, shall, should be applied in the design and promotion, make get corresponding development. Sketch design completed, according to the sketch has identified parts of basic size, design parts drawing. At this time, there are still a large number of parts structure details to be examined and determined. Design work plan, full consideration should be given to the processing of parts and assembly process, parts during machining process and processing after completion of the inspection requirements and implementation methods. Some details of the arrangement if the parts work ability was worth considering influence, must go back to check the work ability. Finally draw out in addition to the standard outside of all parts of the map. According to the final shape of the parts of the structure and size, to draw the part and assembly drawings and assembly drawings. Through this work, can check out the detail drawings may be hidden in the size and structural errors. People regard this work popularly called paper assembly. ( four) the preparation of technical documents phase technology file types, commonly used in the machine design brochures, manuals, and other standard parts list. Design calculation specification, should include the scheme selection and technical design all the conclusions of the content. Preparation for users of machine instructions, should introduce the users machine performance parameters, operation methods, daily maintenance and simple repair method, spare parts catalog. Other technical documents, such as inspection single, purchased parts list, acceptance, as needed and not be compiled. ( five) the computer application in mechanical design with the development of computer technology, the computer in the mechanical design has been increasingly widely used, and there have been many efficient design, analysis software. It can be used in the design phase of projects, can be of different includes large and complex project structural strength, stiffness and dynamic characteristics of precision analysis. At the same time, also in the computer to build virtual prototype, using virtual prototype simulation to verify the design, which realizes the design phase fully assess the feasibility of the design. Can say, the computer technology in machinery design promotion has already changed mechanical design process, it enhances the design quality and efficiency advantages is difficult to estimate. The above briefly introduced the machine design program. Broadly speaking, in the machine manufacture process, appear likely at any time due to technical reasons for modifying the design condition. If you want to modify, should follow certain procedures. Machine factory, should have planned to carry out investigation； in addition, users in the use of the process will also give the design or manufacture sector feedback problems. Design department according to these information, through the analysis, it is also possible for the original design was modified, even remodel. These work, although generalized also belong to design program components, but belongs to another level of problems, this book will not discuss its specific content. But as design worker, should have a strong sense of social responsibility, to my vision extends into the manufacture, use and waste utilization of total process, repeated constantly improve the design, in order to make the quality of the machine to continue to improve, to better meet the needs of production and life At the beginning of the design before, must make the design task. When the design task is more complex, using three general stages of design, the preliminary design, technical design and working drawing design； when the task is relatively simple, such as the simple mechanical model design, general machinery inherited design or variant design, it will start a design to achieve technical design depth, after review, modification and approval to do working drawing design, and become two stage design. In the three stage design in the preliminary design stage, design of the main steps of : determining the working principle and basic structure, motion design, main spare parts, drawing design, preliminary master plan, the preliminary design review. In the design phase, the main steps are: according to the review comments to modify the design, design of all parts, drawing the new general plan, technical design review. In working drawing design stage, according to the review comments to modify the design, draw all the working drawings and make all technical documents. For the mass or mass production of products, but also shape design. In the design of each step, may be found in the previous step some decided not reasonable, it need to fold back in front of that step, modify the irrational decisions, redo the subsequent design work. 1, making design task it is the preparatory work of the design. Design task is based on the user orders, the market needs and the new research results. Design departments application technology and market information, to be listed options, comparing its advantages and disadvantages, and business departments and users together, formulates the reasonable design target. The new design is particularly important. The goal of the task error will be caused serious damage to the economy, even with the overall failure. 2, determine the working principle and basic structure types such as design task did not make specific provision, designed the first step is to determine the overall program, that is determined by the application of the working principle and the structure types. Such as the design of high power marine diesel engine, the first to determine the two stroke, double action, crosshead, low-speed diesel engine, or by four stroke, single function, medium speed diesel engine. Another example is designed for crushing rock crushing machinery, we must first determine the using extrusion and bending as the main role of the jaw crusher or gyratory crusher, or used to shock as the main role of the single rotor or double rotor impact crusher. 3, exercise design scheme is determined, then the need to apply the mechanism knowledge, choose appropriate institutions in order to obtain the desired motion scheme. The above mentioned jaw crusher on the movable jaw plate to swing into the crushing chamber rock by extrusion, bending and splitting the role and broken, and the swing jaw plate can adopt a double elbow board mechanism of simple swinging, or using a single elbow board mechanism of complex oscillation. In the new design, may need to be integrated with a new mechanism to obtain the required movement, this is often a difficult job. Therefore, designers commonly applied as far as possible the existing and mature mechanism is proposed for sports program. 4, structure design and draw the preliminary general motion design, designers began to carry on the structural design, calculation of the main part of the force, strength, shape, size and weight, and the mapping of the main components, sketch. Then if found out that selection of structure is not feasible, we must adjust or modify structure. At the same time also should be considered a possible cause overheating, excessive wear or vibration part. In this step, the designer through sketching will find each part of the shape, size, such as the proportion of contradiction. In order to enhance or improve certain aspects, may weaken or deterioration on the other hand. Then we must weigh up one thing against another, coordination, in order to achieve the best effect. Sketch by repeatedly revise that initial satisfaction, will be able to draw the preliminary master plan and estimated cost. A preliminary layout strictly according to scale, selection of sufficient view and section. 5, preliminary review of the initial layout drawing, the need to please the type of machinery has experience in the design, manufacture and use of personnel as well as the user or commissioned to design the delegate of the unit to conduct a preliminary examination. A review of results such as that is not designed ( such as weight, volume big, cost is too high, the reliability of structure is the doubt ), shall be to exercise design, and even to other working principle and basic structure. In most cases, to take certain measures to improve design. 6, technology design according to the preliminary examination opinions, to modify the design, and the mapping of all parts and components. On the main parts and components for accurate stress analysis, according to the analysis results of modified parts of the shape, size and other details, and the provisions of material and heat treatment. Determine the machining accuracy of the parts and components and assembly of the assembly conditions. Complete lubrication design, electrical design ( drive and control ). Redraw the map, some important and production machinery can sometimes produce model. Will complete the technical design submitted second review 7, draw working drawings according to second review comments made last modified, can draw formal part drawing, assembly drawing and assembly drawing, writing a parts list, wearing parts list, use the guide and other technical documents. Design responsible person should pay attention to coordinate the parts between the size, check the coupling between tolerance, review some parts of the strength and stiffness. Complete the parts after the start to check the drawings, it is very important work. After careful proofreading to ensure smooth processing assembly drawings. The most reliable method of proofreading is based on drawing good parts drawing heavy draw a general assembly drawing, all contradictions will be shown. In the detail drawing but also the need for two tasks: one is the process of audit, the convenient processing of the parts and the manufacturing cost is reduced the two is the standard audit, so that parts of structure, size, tolerance, heat treatment technology and standard and general parts conform to the standard. 8, trial production and designed for single or small batch production machinery, through the steps to complete the design drawings can be put into production. For batch or lot production machinery, before formal production prototype system to test, function test and identification of, by, then by batch process batch production. In batch production in the problems may also need to design corresponding modification, become available for formal production b y using modular design. The design of mechanical parts with many constraints, design criteria design should meet the constraint condition. 1, technical performance standards technical performance includes the function of products, manufacturing and operation status of all property, refers to the static performance, dynamic performance is also used to refer to. For example, the product can transfer power, efficiency, service life, strength, stiffness, friction resistance, wear resistance, thermal stability, vibration characteristics. Technical performance criterion refers to the relevant technical performance to meet the stipulated requirements. For example, the vibration will generate additional dynamic load and stress, especially when the frequency is close to the mechanical systems or parts of the natural frequency, resonance phenomenon will occur, then the amplitude will increase sharply, may lead to the parts and even whole system rapidly damage. Vibration stability criterion is limiting the mechanical systems or parts of the vibration parameters, such as frequency, amplitude, noise in the provisions of the scope of the permit. And as the machine when the fever may cause thermal stress, thermal strain, even will cause thermal damage. Thermal characteristics of guidelines is to restrict the various related thermal parameters ( such as the thermal stress, thermal strain, temperature rise ) in the specified range. 2, standardization and design of mechanical products related to the main standard generally are: the concept of Standardization: involved in the design process of the terminology, symbols, units of measurement shall be in accordance with the standard； objective form standardization: parts, raw materials, equipment and energy structure, size, performance, should be uniform choice. Methods: standardized operation method, measurement method, test method etc should be according to the relevant provisions. Standardization in the entire design process all behavior, must meet the requirements for standardization. Has been released and the design of mechanical parts related standard, from the scope of application of speaking, can be divided into national standards, industry standards and enterprise standards for three grade. From the use of mandatory, can be divided into must be performed and recommended the use of the two kind. 3: reliability, reliability standards for products or components within the prescribed conditions, the expected life to finish regulation function of theprobability of Reliability criterion refers to design products, components or parts should be able to meet the requirements of the reliability requirements in 4, the safety criterion for safety of machinery parts including: Security: defined in terms of external load and within a specified period of time, such as fracture parts not excessive deformation, excessive wear and without loss of stability and so on. Machine safety: a machine to ensure that the required conditions of trouble, can normally achieve functional requirements. Work safety: refers to the operation personnel protection guarantee the safety of humanand health of body and mind. Environmental security: refers to the machines to the surrounding environment and people do not cause the pollution and harm Design methodology to design thinking to rational process, so that the design can follow certain logic, so that more designers can make good design. It generally includes the following content: 1, will design the stage finely, so that each stage is rule-based and reasonable thinking activity. In 2,will be successful or good design store design, establishment of database, for future reference in the design or use. In3, design work in the introduction of the concept of value engineering and method of design, the contradiction in the function and cost trade-off, to obtain good results. 4, used in the design of tribology, vibration theory, fracture mechanics, finite element method, optimization design, reliability design system engineering ergonomics and other emerging disciplines of knowledge, improve the scientific design, reduce blindness. In 5, will expand the scope of design work, extended forward to the market forecast, extends to after sale service. The application of computer aided design in order to reduce the amount of labor, improve design speed and quality of design. 譯文： 機械設(shè)計 機械設(shè)計是 機械工程 的重要組成部分，是機械生產(chǎn)的第一步，是決定機械性能 的最主要的因素。機械設(shè)計的努力目標(biāo)是：在各種限定的條件 (如材料、加 工能力、理論知識和計算手段等 )下設(shè)計出最好的機械，即做出 優(yōu)化設(shè)計 。優(yōu)化設(shè)計需要綜合地考慮許多要求，一般有：最好工作性能、最低制造成本、最小尺寸和重量、使用中最可靠性、最低消耗和最少 環(huán)境污染 。這些要求常是互相矛盾的，而且它們之間的相對重要性因機械種 類和用途的不同而異。設(shè)計者的任務(wù)是按具體情況權(quán)衡輕重，統(tǒng)籌兼顧，使設(shè)計的機械有最優(yōu)的綜合 技術(shù)經(jīng)濟(jì)效果 。過去，設(shè)計的優(yōu)化主要依靠設(shè)計者的知識、經(jīng)驗和遠(yuǎn)見。隨著機械工程基礎(chǔ)理論和 價值工程 、 系統(tǒng)分析 等新學(xué)科的發(fā)展，制造和使用的技術(shù)經(jīng)濟(jì)數(shù)據(jù)資料的積累 ,以及 計算機 的推廣應(yīng)用 ,優(yōu)化逐漸舍棄主觀判斷而依靠科學(xué)計算。 服務(wù)于不同產(chǎn)業(yè)的不同機械，應(yīng)用不同的工作原理，要求不同的功能和特性。各產(chǎn)業(yè)機械的設(shè)計，特別是整體和整系統(tǒng)的機械設(shè)計，須依附于各有關(guān)的產(chǎn)業(yè)技術(shù)而難于形成獨立的學(xué)科。因此出現(xiàn)了 農(nóng)業(yè)機械 設(shè)計、 礦山機械 設(shè)計、紡織機械設(shè)計、 汽車 設(shè)計、 船舶 設(shè)計、 泵 設(shè)計、 壓縮機 設(shè)計、汽輪機 設(shè)計、 內(nèi)燃機 設(shè)計、 機床 設(shè)計等專業(yè)性的機械設(shè)計分支學(xué)科。但是，這許多專業(yè)設(shè)計又有許多共性技術(shù)，例如機構(gòu)分析和綜合、力與能的分析和計算、 工程材料學(xué) 、材料強度學(xué)、傳動、潤滑、密封，以及標(biāo)準(zhǔn)化、可靠性、工藝性、優(yōu)化等。此外，還有研究設(shè)計工作的內(nèi)在規(guī)律和設(shè)計的合理步驟和方法的新興的設(shè)計方法學(xué)。將機械設(shè)計的共性技術(shù)與理性化的設(shè)計方法學(xué)匯集成為一門獨立的、綜合性的機械設(shè)計學(xué)科是機械工程實踐和教育工作者正在努力的工作。 機械設(shè)計可分為新型設(shè)計、繼承設(shè)計和變型設(shè)計 3 類。 1、新型設(shè)計應(yīng)用成熟的科學(xué)技術(shù)或經(jīng)過實驗證明是可行的新技術(shù)，設(shè)計過去沒有過的新型機械。 2、繼承設(shè)計根據(jù)使用經(jīng)驗和技術(shù)發(fā)展對已有的機械進(jìn)行設(shè)計更新，以提高其性能、降低其制造成本或減少其運用費 用。 3、 變型設(shè)計 為適應(yīng)新的需要對已有的機械作部分的修改或增刪而發(fā)展出不同于標(biāo)準(zhǔn)型的變型產(chǎn)品。 機械設(shè)計主要過程 1 根據(jù)用戶訂貨、市場需要和新科研成果制定設(shè)計任務(wù)。 2、初步設(shè)計。包括確定機械的工作原理和基本結(jié)構(gòu)形式，進(jìn)行運動設(shè)計、 結(jié)構(gòu)設(shè)計 并繪制初步總圖以及初步審查。 3、技術(shù)設(shè)計。包括修改設(shè)計（根據(jù)初審意見）、繪制全部零部件和新的總圖以及第二次審查。 4、工作圖設(shè)計。包括最后的修改（根據(jù)二審意見）、繪制全部工作圖（如 零件圖 、部件裝配圖和總裝配圖等）、制定全部技術(shù)文件（如零件表、易損件清單、使用說明等）。 5、定型設(shè)計。用于成批或大量生產(chǎn)的機械。對于某些設(shè)計任務(wù)比較簡單（如 簡單機械 的新型設(shè)計、一般機械的繼承設(shè)計或變型設(shè)計等）的機械設(shè)計可省去初步設(shè)計程序。 所討論的設(shè)計過程僅指狹義的技術(shù)性的設(shè)計過程。它是一個創(chuàng)造性的工作過程，同時也是一個盡可能多地利用已有的成功經(jīng)驗的工作。要很好地把繼承與創(chuàng)新結(jié)合起來，才能設(shè)計出高質(zhì)量的機器。作為一部完整的機器，它是一個復(fù)雜的系統(tǒng)。要提高設(shè)計質(zhì)量，必須有一個科學(xué)的設(shè)計程序。雖然不可能列出一個在任何情況下都有效的惟一程序，但是，根據(jù)人們設(shè)計 。 （一）計劃階段 在根據(jù)生產(chǎn)或生活的需要提出所要設(shè)計的新機器后，計劃階段只是一個預(yù)備階段。此時，對所要設(shè)計的機器僅有一個模糊的概念。 在計劃階段中，應(yīng)對所設(shè)計的機器的需求情況做充分的調(diào)查研究和分析。通過分析，進(jìn)一步明確機器所應(yīng)具有的功能，并為以后的決策提出由環(huán)境、經(jīng)濟(jì)、加工以及時限等各方面所確定的約束條件。在此基礎(chǔ)上，明確地寫出設(shè)計任務(wù)的全面要求及細(xì)節(jié)，最后形成設(shè)計任務(wù)書，作為本階段的總結(jié)。設(shè)計任務(wù)書大體上應(yīng)包括：機器的功能，經(jīng)濟(jì)性及環(huán)保性的估計，制造要求方面的大致估計，基本使用要求，以及完成設(shè)計任 務(wù)的預(yù)計期限等。此時，對這些要求及條件一般也只能給出一個合理的范圍，而不是準(zhǔn)確的數(shù)字。例如可以用必須達(dá)到的要求、最低要求、希望達(dá)到的要求等方式予以確定。 （二）方案設(shè)計階段 本階段對設(shè)計的成敗起關(guān)鍵的作用。在這一階段中也充分地表現(xiàn)出設(shè)計工作有多個解（方案）的特點。 機器的功能分析，就是要對設(shè)計任務(wù)書提出的機器功能中必須達(dá)到的要求、最低要求及希望達(dá)到的要求進(jìn)行綜合分析，即這些功能能否實現(xiàn)，多項功能間有無矛盾，相互間能否替代等。最后確定出功能參數(shù)，作為進(jìn)一步設(shè)計的依據(jù)。在這一步驟中，要恰當(dāng)處理需要與可能、 理想與現(xiàn)實、發(fā)展目標(biāo)與當(dāng)前目標(biāo)等之間可能產(chǎn)生的矛盾問題。 確定出功能參數(shù)后，即可提出可能的解決辦法，亦即提出可能采用的方案。尋求方案時，可按原動部分、傳動部分及執(zhí)行部分分別進(jìn)行討論。，較為常用的辦法是先從執(zhí)行部分開始討論。 討論機器的執(zhí)行部分時，首先是關(guān)于工作原理的選擇問題。例如，設(shè)計制造 螺釘 的機器時，其工作原理既可采用在圓柱形毛坯上用車刀車削螺紋的辦法，也可采用在圓柱形 毛坯上用滾絲模滾壓螺紋的辦法。這就提出了兩種不同的工作原理。工作原理不同，當(dāng)然所設(shè)計出的機器就會根本不同。特別應(yīng)當(dāng)強調(diào)的是，必須不斷地研究和發(fā)展新的工作原理。這是設(shè)計技術(shù)發(fā)展的重要途徑。 根據(jù)不同的工作原理，可以擬定多種不同的執(zhí)行機構(gòu)的具體方案。例如僅以切削螺紋來說，既可以采用工件只作旋轉(zhuǎn)運動而 刀具 作直線運動來切削螺紋（如在普通 車床 上切削 螺紋 ），也可以使工件不動而刀具作轉(zhuǎn)動和移動來切削螺紋（如用 板牙 加工螺紋）。這就是說，即使對于同一種工作原理，也可能有幾種不同的結(jié)構(gòu)方案。 原動機部分的 方案當(dāng)然也可以有多種選擇。由于電力供應(yīng)的普遍性和電力拖動技術(shù)的發(fā)展，現(xiàn)在可以說絕大多數(shù)的固定機械都優(yōu)先選擇電動機作為原動機部分。熱力原動機主要用于運輸機、工程機械或農(nóng)業(yè)機械。即使是用電動機作為原動機，也還有交流和直流的選擇，高轉(zhuǎn)速和低轉(zhuǎn)速的選擇等。 傳動部分的方案就更為復(fù)雜多樣了。對于同一傳動任務(wù)，可以由多種機構(gòu)及不同機構(gòu)的組合來完成。因此，如果用 ，表示原動機部分的可能方案數(shù)， N2和 N3分別代表傳動部分和執(zhí)行部分的可能方案數(shù)，則機器總體的可能方案數(shù) 為 NiN2N3 個。 以上僅是就組成機器的三個主要 部分討論的。有時，還須考慮到配置輔助系統(tǒng) ，對此，本書不再討論。 在如此眾多的方案中，技術(shù)上可行的僅有幾個。對這幾個可行的方案，要從技術(shù)方面和經(jīng)濟(jì)及環(huán)保等方面進(jìn)行綜合評價。評價的方法很多，現(xiàn)以經(jīng)濟(jì)性評價為例略做說明。根據(jù)經(jīng)濟(jì)性進(jìn)行評價時，既要考慮到設(shè)計及制造時的經(jīng)濟(jì)性，也要費用考慮到使用時的經(jīng)濟(jì)性。如果機器的結(jié)構(gòu)方案比較復(fù)雜，則其設(shè)計制造成本就要相對地增大，可是其功能將更為 齊全，生產(chǎn)率也較高，故使用經(jīng)濟(jì)性也較好。反過來，結(jié)構(gòu)較為簡單、功能不夠齊全的機器，設(shè)計及制造費用雖少，但使用費用卻會增多。評價結(jié)構(gòu)方案的設(shè)計制造經(jīng)濟(jì)性時，還可以用單位功效的成本來表示。例如單位輸出功率的成本、單件產(chǎn)品的成本等。 進(jìn)行機器評價時，還必須對機器的可靠性進(jìn)行分析，把可靠性作為一項評價的指標(biāo)。從可靠性的觀點來看，盲目地追求復(fù)雜的結(jié)構(gòu)往往是不明智的。一般地講，系統(tǒng)越復(fù)雜，則 系統(tǒng)的可靠性 就越低。為了提高復(fù)雜系統(tǒng)的可靠性，就必須增加并聯(lián)備用系統(tǒng)，而這不可避免地會提高機器的成本。 環(huán)境保護(hù)也是設(shè)計中必須認(rèn)真考慮的重要方面。對環(huán)境造成不良影響的技術(shù)方案，必須詳細(xì)地進(jìn)行分析，并提出技術(shù)上成熟的解決辦法。 通過方案評價，最后進(jìn)行決策，確定一個據(jù)以進(jìn)行下步技術(shù)設(shè)計的原理圖或 機構(gòu)運動簡圖 。 在方案設(shè)計階段，要正確地處理好借鑒與創(chuàng)新的關(guān)系。同類機 器成功的先例應(yīng)當(dāng)借鑒，原先薄弱的環(huán)節(jié)及不符合現(xiàn)有任務(wù)要求的部分應(yīng)當(dāng)加以改進(jìn)或者根本改變。既要積極創(chuàng)新，反對保守和照搬原有設(shè)計，也要反對一味求新而把合理的原有經(jīng)驗棄置不用這兩種錯誤傾向。 （三）技術(shù)設(shè)計階段 技術(shù)設(shè)計階段的目標(biāo)是產(chǎn)生總裝配草圖及部件裝配草圖。通過草圖設(shè)計確定出各部件及其零件的外形及基本尺寸，包括各部件之間的連接，零、部件的外形及基本尺寸。最后繪制零件的工作圖、部件 裝配圖 和總裝圖。 為了確定主要零件的基本尺寸，必須做以下工作： 1)機器的 運動學(xué) 設(shè)計。根據(jù)確定的結(jié)構(gòu)方案，確定原動件的參數(shù)（ 功率 、轉(zhuǎn)速、線速度等）。然后做運動學(xué)計算，從而確定各 運動構(gòu)件 的運動參數(shù)（轉(zhuǎn)速、速度、加速度等）。 2)機器的動力學(xué)計算。結(jié)合各部分的結(jié)構(gòu)及運動參數(shù)，計算各主要零件所受載荷的大小及特性。此時求出的載荷，由于零件尚未設(shè)計出來，因而只是作用于零件上的公稱（或名義） 載荷 。 3)零件的工作能力設(shè)計。已知主要零件所受的公稱載荷的大小和特性，即可做零、部件的初步設(shè)計 。設(shè)計所依據(jù)的工作能力準(zhǔn)則，須參照零、部件的一般失效情況、工作特性、環(huán)境條件等合理地擬定，一般有強度、 剛度 、 振動穩(wěn)定性、壽命等準(zhǔn)則。通過計算或類比，即可決定零、部件的基本尺寸。 4)部件裝配草圖及總裝配草圖的設(shè)計。根據(jù)已定出的主要零、部件的基本尺寸，設(shè)計出部件裝配草圖及總裝配草圖。草圖上需對所有零件的外形及尺寸進(jìn)行結(jié)構(gòu)化設(shè)計。在此步驟中，需要很好地協(xié)調(diào)各零件的結(jié)構(gòu)及尺寸，全 面地考慮所設(shè)計的零、部件的結(jié)構(gòu)工藝性，使全部零件有最合理的構(gòu)形。 5)主要零件的校核。有一些零件，在上述第 3）步中由于具體的結(jié)構(gòu)未定，難于進(jìn)行詳細(xì)的工作能力計算，所以只能做初步計算及設(shè)計。在繪出部件裝配草圖及總裝配草圖以后，所有零件的結(jié)構(gòu)及尺寸均為已知，相互鄰接的零件之間的關(guān)系也為已知。只有在這時，才可以較為精確地定出作用在零件上的載荷，決定影響零件工作能力的各個細(xì)節(jié)因素。只有在此條件下，才有可能并且必須對一些重要的或者外形及受力情況復(fù)雜的零件進(jìn)行精確的校核計算。根據(jù)校核的結(jié)果，反復(fù)地修改零件的結(jié)構(gòu)及尺寸 ，直到滿意為止。 在技術(shù)設(shè)計的各個步驟中，近三四十年來發(fā)展起來的優(yōu)化設(shè)計技術(shù)，越來越顯示出它可使結(jié)構(gòu)參數(shù)的選擇達(dá)到最佳的能力。一些新的 數(shù)值計算方法 ，如有限元法等，可使以前難以定量計算的問題獲得極好的近似定量計算的結(jié)果。對于少數(shù)非常重要、結(jié)構(gòu)復(fù)雜且價格昂貴的零件，在必要時還須用模型試驗方法來進(jìn)行設(shè)計，即按初步設(shè)計的圖紙制造出模型，通過試驗，找出結(jié)構(gòu)上的薄弱部位或多余的截面尺 寸，據(jù)此進(jìn)行加強或減小來修改原設(shè)計，最后達(dá)到完善的程度。機械可靠性理論用于技術(shù)設(shè)計階段，可以按可靠性的觀點對所設(shè)計的零、部件結(jié)構(gòu)及其參數(shù)做出是否滿足可靠性要求的評價，提出改進(jìn)設(shè)計的建議，從而進(jìn)一步提高機器的設(shè)計質(zhì)量。上述這些新的設(shè)計方法和概念，應(yīng)當(dāng)在設(shè)計中加以應(yīng)用與推廣，使之得到相應(yīng)的發(fā)展。 草圖設(shè)計完成以后，即可根據(jù)草圖業(yè)已確定的零件基本尺寸，設(shè)計零件的工作圖。此時，仍有大量的零件結(jié)構(gòu)細(xì)節(jié)要加以推敲和確定。設(shè)計工作圖時，要充分考慮到零件的加工和裝配工藝性、零件在加工過程中和加工完成后的檢驗要求和實施方法 等。有些細(xì)節(jié)安排如果對零件的工作能力有值得考慮的影響時，還須返回去重新校核工作能力。最后繪制出除 標(biāo)準(zhǔn)件 以外的全部零件的工作圖。 按最后定型的零件工作圖上的結(jié)構(gòu)及尺寸，重新繪制部件裝配圖及總裝配圖。通過這一工作，可以檢查出零件工作圖中可能隱藏的尺寸和結(jié)構(gòu)上的錯誤。人們把這一工作通俗地稱為紙上裝配。 （四）技術(shù)文件編制階段 技術(shù)文件的種類較多，常用的有機器的設(shè)計計算說明書、使 用說明書、標(biāo)準(zhǔn)件明細(xì)表等。 編制設(shè)計計算說明書時，應(yīng)包括方案選擇及技術(shù)設(shè)計的全部結(jié)論性的內(nèi)容。 編制供用戶使用的機器使用說明書時，應(yīng)向