双柱液压式汽车举升机【含外文翻译+任务书+3A0图纸量】

资源目录里展示的全都有预览可以查看的噢，，下载就有,,请放心下载，原稿可自行编辑修改=【QQ：11970985 可咨询交流】====================喜欢就充值下载吧。。。资源目录里展示的全都有，，下载后全都有,,请放心下载，原稿可自行编辑修改=【QQ：197216396 可咨询交流】==================== 专题 高速切削的概念、和应用技术 高速切削理论是1931年4月德国物理学家Carl.J.Salomon提出的。他指出，在常规切削速度范围内，切削温度随着切削速度的提高而升高，但切削速度提高到一定值后，切削温度不但不升高反会降低，且该切削速度值与工件材料的种类有关。对每一种工件材料都存在一个速度范围，在该速度范围内，由于切削温度过高，刀具材料无法承受，即切削加工不可能进行，称该区为“死谷”。虽然由于实验条件的限制，当时无法付诸实践，但这个思想给后人一个非常重要的启示，即如能越过这个“死谷”，在高速区工作，有可能用现有刀具材料进行高速切削，切削温度与常规切削基本相同，从而可大幅度提高生产效率。 高速切削是个相对的概念，究竟如何定义，目前尚无共识。由于加工方法和工件材料的不同，高速切削的高速范围也很难给出，一般认为应是常规切削速度的5～10倍。 自从Salomon提出高速切削的概念并于同年申请专利以来，高速切削技术的发展经历了高速切削理论的探索、应用探索、初步应用和较成熟应用等四个阶段，现已在生产中得到了一定的推广应用。特别是20世纪80年代以来，各工业发达国家投入了大量的人力和物力，研究开发了高速切削设备及相关技术，20世纪90年代以来发展更迅速。 高速切削技术是在机床结构及材料、机床设计、制造技术、高速主轴系统、快速进给系统、高性能CNC系统、高性能刀夹系统、高性能刀具材料及刀具设计制造技术、高效高精度测量测试技术、高速切削机理、高速切削工艺等诸多相关硬件和软件技术均得到充分发展基础之上综合而成的。因此，高速切削技术是一个复杂的系统工程. 高速与超高速切削的特点 随着高速与超高速机床设备和刀具等关键技术领域的突破性进展，高速与超高速切削技术的工艺和速度范围也在不断扩展。如今在实际生产中超高速切削铝合金的速度范围为1500m/min～5500m/min，铸铁为750m/min～4500m/min，普通钢为600m/min～800m/min，进给速度高达20 m/min～40m/min。而且超高速切削技术还在不断地发展。在实验室里，切削铝合金的速度已达 6000m/min以上，进给系统的加速度可达3g。有人预言，未来的超高速切削将达到音速或超音速。其特点可归纳如下： (1)可提高生产效率 提高生产效率是机动时间和辅助时间大幅度减少、加工自动化程度提高的必然结果。据称，由于主轴转速和进给的高速化，加工时间减少了50%，机床结构也大大简化，其零件的数量减少了25%，而且易于维护。 (2)可获得较高的加工精度 由于切削力可减少30%以上，工件的加工变形减小，切削热还来不及传给工件，因而工件基本保持冷态，热变形小，有利于加工精度的提高。特别对大型的框架件、薄板件、薄壁槽形件的高精度高效率加工，超高速铣削则是目前惟一有效的加工方法。 (3)能获得较好的表面完整性 在保证生产效率的同时，可采用较小的进给量，从而减小了加工表面的粗糙度值；又由于切削力小且变化幅度小，机床的激振频率远大于工艺系统的固有频率，故振动时表面质量的影响很小；切削热传入工件的比率大幅度减少，加工表面的受热时间短，切削温度低，加工表面可保持良好的物理力学性能。 (4)加工能耗低，节省制造资源 超高速切削时，单位功率的金属切除率显著增大。以洛克希德飞机制造公司的铝合金超高速铣削为例，主轴转速从4000m/min提高到20000m/min，切削力减小了30%，金属切除率提高了3倍，单位功率的金属切除率可达130000mm3/(min·kW)160000mm3/(min·kW)。由于单位功率的金属切除率高、能耗低、工件的在制时间短，从而提高了能源和设备的利用率，降低了切削加工在制造系统资源总量中的比例，故超高速切削完全符合可持续发展战略的要求。 高速与超高速切削技术的应用领域 高速切削是当今制造业中一项快速发展的新技术，在工业发达国家，高速切削正成为一种新的切削加工理念。 ①高速切削的应用领域首先在航空工业轻合金的加工。飞机制造业是最早采用高速铣削的行业。飞机上的零件通常采用“整体制造法”，即在整体上“掏空”加工以形成多筋薄壁构件，其金属切除量相当大，这正是高速切削的用武之地。铝合金的切削速度已达1500m/min～5500 m/min，最高达7500m/min(美)。 ②模具制造业也是高速加工应用的重要领域。模具型腔加工过去一直为电加工所垄断，但其加工效率低。而高速加工切削力小，可铣淬硬60HRC的模具钢，加工表面粗糙度值又很小，浅腔大曲率半径的模具完全可用高速铣削来代替电加工；对深腔小曲率的，可用高速铣削加工作为粗加工和半精加工，电加工只作为精加工。这样可使生产效率大大提高，周期缩短。钢的切削速度可达600m/min～800m/min。 ③汽车工业是高速切削的又一应用领域。汽车发动机的箱体、气缸盖多用组合机加工。国外汽车工业及上海大众、上海通用公司，凡技术变化较快的汽车零件，如：气缸盖的气门数目及参数经常变化，现一律用高速加工中心来加工。铸铁的切削速度可达750m/min～4500m/min。 ④ Ni基高温合金(Inconel 718)和Ti合金(Ti-6Al-4V)常用来制造发动机零件，因它们很难加工，一般采用很低的切削速度。如采用高速加工，则可大幅度提高生产效率、减小刀具磨损、提高零件的表面质量。 ⑤纤维增强复合材料切削时对刀具有十分严重的刻划作用，刀具磨损非常快。用聚晶金刚石PCD刀具进行高速加工，收到满意效果。可防止出现“层间剥离”，效率高、质量好。 ⑥干式切削和硬态切削也是高速切削扩展的领域。 ⑦国内的应用举例。国内某专业橡胶模具制造厂，高速铣削在高精度铝质模具型腔加工和轮胎模具型芯加工中取得了很好的效果。所用机床为5轴联动高速铣床DIGIT-218，转速为28000r/min，功率为6kW，进给速度υf=10m/min，进给加速度为0.5g。 高精度铝质模具型腔加工是众多模具制造厂家的一大难题。在传统铣削加工中，由于铝熔点低，铝屑容易粘附在刀具上，虽经后续的铲刮、抛光工序，型腔也很难达到精度要求，在制时间达60小时。用高速铣削n0粗=18000r/min，ap=2mm，υf=5m/min；n0精＝20000r/min，ap=0.2mm，加工周期仅为6小时，完全达到1500mm长度上的尺寸精度为±0.05mm、Ra0.8μm的要求。 塑料的轮胎型芯加工用传统方法(手工)需十几道工序，在制时间20天以上，也很难达到复杂轮胎花纹的技术要求。采用高速铣削，n0＝ 18 000r/min，ap=2 mm，υf=10m/min，在制时间仅24小时就完全达到了工艺要求。 高速与超高速切削对机床的新要求 机床是实现高速与超高速切削的首要条件和关键因素。高速与超高速切削对机床提出了很多新要求，归纳如下： (1)主轴要有高转速、大功率和大扭矩 高速与超高速切削不但要求机床主轴转速高，而且要求传递的扭矩和功率也要大，并且在高速运转中还要保持良好的动态特性和热态特性。 (2)进给速度也要相应提高，以保证刀具每齿进给量基本不变 为了配合主轴10倍于常规的切削速度，进给速度也必须相应提高10倍，由过去的6m/min提高到60m/min～100m/min，以保持刀具的每齿进给量基本不变。 (3)进给系统要有很大的加速度 在切削加工过程中，机床进给系统的工作行程一般只有几十毫米至几百毫米。在这样短的行程中要实现稳定的高速与超高速切削，除了进给速度要高外，进给系统必须有很大的加速度，以尽量缩短启动—变速—停车的过渡过程，以实现平稳切削。这是高速与超高速切削对机床结构设计的新要求，也是机床设计理论的新发展。 综上所述，沿袭数十年的普通数控机床的传动与结构已远远不能适应要求，必须进行全新设计。因此，有人称高速与超高速机床是21世纪的新机床，其主要特征是实现机床主轴和进给的直接驱动，是机电一体化的新产品。 适用高速与超高速切削的刀具材料 目前适用于高速切削的刀具主要有：涂层刀具、金属陶瓷刀具、陶瓷刀具、立方氯化硼(CBN)刀具及聚晶金刚石(PCD)刀具等。 1.涂层刀具 涂层在刀具基体上涂复硬质耐磨金属化合物薄膜以达到提高刀具表面的硬度和耐磨性的目的。常用的刀具基体材料主要有高速钢、硬质合金、金属陶瓷和陶瓷等。涂层TiN，TiC，Al2O3，TiCN，TiAlN，TiAlCN等；涂层可以是单涂层，也可以是双涂层或多涂层，甚至是几种涂层材料复合而成的复合涂层。复合涂层可以是TiC-Al2O3-TiN，TiCN和 TiAlN多元复合涂层，最新又发展了TiN/NbN，TiN/CN等多元复合薄膜。如商品名为“Fire”的孔加工刀具复合涂层，是用TiN作底层，以保证与基体间的结合强度；由多层薄涂层构成的中间层为缓冲层，以用来吸收断续切削产生的振动；顶层是具有良好耐磨性和耐热性的TiAlN层。还可在“Fire”外层上涂减磨涂层。其中，TiAlN层在高速切削中性能优异，最高切削温度可达800℃。近年开发出的一些PVD硬涂层材料，有CBN、氮化碳(CN)、Al2O3、氮化物(TiN/NbN，TiN/CN)等，在高温下具有良好的热稳定性，很适合高速与超高速切削。金刚石膜涂层刀具主要用于有色金属加工。C-C3N4超硬涂层的硬度有可能超过金刚石。 软涂层刀具，如 MoS2和 WS2作为涂层材料的高速钢刀具主要用于高强度铝合金、钛合金等的加工。此外，最新开发的纳米涂层材料刀具在高速切削中的应用前景也很广阔。如日本住友公司的纳米TiAlN复合涂层铣刀片，共2000层涂层，每层只有2.5nm厚。 2.金属陶瓷刀具 金属陶瓷主要包括高耐磨性能的TiC基硬质合金(TiC+Ni或Mo)、高韧性的TiC基硬质合金( TiC+TaC+WC)、强韧的TiN基硬质合金和高强韧性的TiCN基硬质合金(TiCN＋NbC)等。这些合金做成的刀具可在υc=300m/min～500m/min范围内高速精车钢和铸铁。金属陶瓷可制成钻头、铣刀与滚刀。如日本研制的金属陶瓷滚刀，υc=600m/min，约是硬质合金滚刀的10～20倍，加工表面粗糙度值Rmax为2μm，比HSS滚刀(Rmax15μm)和硬质合金滚刀(Rmax8μm)小的多，耐磨性优于HSS和硬质合金，HSS滚刀后刀面磨损量VB＝0.32mm，硬质合金滚刀VB＝0.18mm，而金属陶瓷滚刀VB＝0.08mm。 3.陶瓷刀具 陶瓷刀具可在υc=200m/min～1000m/min范围内切削软钢、淬硬钢和铸铁等材料。 4.CBN刀具 CBN刀具是高速精加工或半精加工淬硬钢、冷硬铸铁和高温合金等的理想对具材料，可以实现“以车代磨”。国外还研制了CBN含量不同的CBN刀具，以充分发挥CBN刀具的切削性能(见表1)。据报导，CBN300加工灰铸铁的速度可达2000m/min。 表1 不同CBN含量的刀片及用途 CBN含量(%) 用 途 50 连续切削淬硬钢(45HRC～65HRC) 65 半断续切削淬硬钢(45HRC～65HRC) 80 Ni-Cr铸铁 90 连续重载切削淬硬钢(45HRC～65HRC) 80～90 高速切削铸铁(45HRC～65HRC)，粗、半精切削淬硬钢 5.PCD刀具 PCD刀具可实现有色金属、非金属耐磨材料的高速加工。据报导，镶PCD的钻头加工Si-Al则合金的切削速度队达300m/min～400m/min，PCD与硬质合金的复合片钻头加工用Al合金、Mg合金、复合材料FRP、石墨、粉末冶金坯料，与硬质合金刀具相比，刀具寿命提高了65～145倍；采用高强度Al合金刀体的PCD面铣刀加工用合金的速度υc达 3000m/min～4000m/min，有的达到7000m/min。20世纪90年代以后，美、日相继研制开发了金刚石薄膜刀具(车铣刀片、麻花钻、立铣刀、丝锥等)，寿命是硬质合合金刀具的10～140倍。 6.性能优异的高速钢和硬质合金复杂刀具 用高性能钴高速钢、粉末冶金高速钢和硬质合金制造的齿轮刀具，可用于齿轮的高速切削。 用硬质合金粉末和高速钢粉末配制成的新型粉末冶金材料制成的齿轮滚刀，滚切速度可达150m/min～180m/min。进行对TiAlN涂层处理后，可用于高速干切齿轮。 用细颗粒硬质合金制造并涂复耐磨耐热及润滑涂层的麻花钻加冷却液加工碳素结构钢和合金钢时，切削速度可达200m/min，于切时切削速度也可达150m/min。 用细颗粒硬质合金制成的丝锥加工灰铸铁时，切削速度可达100m/min。 意大利SU公司研制的硬质合金滚刀涂复TiCN涂层后加工模数m＝1.5的行星齿轮时，加水基切削液，粗滚速度υc粗=280m/min，精滚υc精＝600m/min。 附录 (外文翻译——原文) Fundamentals of Mechanical Design Mechanical design means the design of things and systems of a mechanical nature—machines, products, structures, devices, and instruments. For the most part mechanical design utilizes mathematics, the materials sciences, and the engineering-mechanics sciences. The total design process is of interest to us. How does it begin? Does the engineer simply sit down at his desk with a blank sheet of paper? And, as he jots down some ideas, what happens next? What factors influence or control the decisions which have to be made? Finally, then, how does this design process end? Sometimes, but not always, design begins when an engineer recognizes a need and decides to do something about it. Recognition of the need and phrasing it in so many words often constitute a highly creative act because the need may be only a vague discontent, a feeling of uneasiness, of a sensing that something is not right. The need is usually not evident at all. For example, the need to do something about a food-packaging machine may be indicated by the noise level, by the variations in package weight, and by slight but perceptible variations in the quality of the packaging or wrap. There is a distinct difference between the statement of the need and the identification of the problem. which follows this statement. The problem is more specific. If the need is for cleaner air, the problem might be that of reducing the dust discharge from power-plant stacks, or reducing the quantity of irritants from automotive exhausts. Definition of the problem must include all the specifications for the thing that is to be designed. The specifications are the input and output quantities, the characteristics of the space the thing must occupy and all the limitations on these quantities. We can regard the thing to be designed as something in a black box. In this case we must specify the inputs and outputs of the box together with their characteristics and limitations. The specifications define the cost, the number to be manufactured, the expected life, the range, the operating temperature, and the reliability. There are many implied specifications which result either from the designer's particular environment or from the nature of the problem itself. The manufacturing processes which are available, together with the facilities of a certain plant, constitute restrictions on a designer's freedom, and hence are a part of the implied specifications. A small plant, for instance, may not own cold-working machinery. Knowing this, the designer selects other metal-processing methods which can be performed in the plant. The labor skills available and the competitive situation also constitute implied specifications. After the problem has been defined and a set of written and implied specifications has been obtained, the next step in design is the synthesis of an optimum solution. Now synthesis cannot take place without both analysis and optimization because the system under design must be analyzed to determine whether the performance complies with the specifications. The design is an iterative process in which we proceed through several steps, evaluate the results, and then return to an earlier phase of the procedure. Thus we may synthesize several components of a system, analyze and optimize them, and return to synthesis to see what effect this has on the remaining parts of the system. Both analysis and optimization require that we construct or devise abstract models of the system which will admit some form of mathematical analysis. We call these models mathematical models. In creating them it is our hope that we can find one which will simulate the real physical system very well. Evaluation is a significant phase of the total design process. Evaluation is the final proof of a successful design, which usually involves the testing of a prototype in the laboratory. Here we wish to discover if the design really satisfies the need or needs. Is it reliable? Will it compete successfully with similar products? Is it economical to manufacture and to use? Is it easily maintained and adjusted? Can a profit be made from its sale or use? Communicating the design to others is the final, vital step in the design process. Undoubtedly many great designs, inventions, and creative works have been lost to mankind simply because the originators were unable or unwilling to explain their accomplishments to others. Presentation is a selling job. The engineer, when presenting a new solution to administrative, management, or supervisory persons, is attempting to sell or to prove to them that this solution is a better one. Unless this can be done successfully, the time and effort spent on obtaining the solution have been largely wasted. Basically, there are only three means of communication available to us. There are the written, the oral, and the graphical forms. Therefore the successful engineer will be technically competent and versatile in all three forms of communication. A technically competent person who lacks ability in any one of these forms is severely handicapped. If ability in all three forms is lacking, no one will ever know how competent that person is! The competent engineer should not be afraid of the possibility of not succeeding in a presentation. In fact, occasional failure should be expected because failure or criticism seems to accompany every really creative idea. There is a great to be learned from a failure, and the greatest gains are obtained by those willing to risk defeat. In the find analysis, the real failure would lie in deciding not to make the presentation at all. Introduction to Machine Design Machine design is the application of science and technology to devise new or improved products for the purpose of satisfying human needs. It is a vast field of engineering technology which not only concerns itself with the original conception of the product in terms of its size, shape and construction details, but also considers the various factors involved in the manufacture, marketing and use of the product. People who perform the various functions of machine design are typically called designers, or design engineers. Machine design is basically a creative activity. However, in addition to being innovative, a design engineer must also have a solid background in the areas of mechanical drawing, kinematics, dynamics, materials engineering, strength of materials and manufacturing processes. As stated previously, the purpose of machine design is to produce a product which will serve a need for man. Inventions, discoveries and scientific knowledge by themselves do not necessarily benefit people; only if they are incorporated into a designed product will a benefit be derived. It should be recognized, therefore, that a human need must be identified before a particular product is designed. Machine design should be considered to be an opportunity to use innovative talents to envision a design of a product is to be manufactured. It is important to understand the fundamentals of engineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used to provide all the correct decisions to produce a good design. On the other hand, any calculations made must be done with the utmost care and precision. For example, if a decimal point is misplaced, an otherwise acceptable design may not function. Good designs require trying new ideas and being willing to take a certain amount of risk, knowing that is the new idea does not work the existing method can be reinstated. Thus a designer must have patience, since there is no assurance of success for the time and effort expended. Creating a completely new design generally requires that many old and well-established methods be thrust aside. This is not easy since many people cling to familiar ideas, techniques and attitudes. A design engineer should constantly search for ways to improve an existing product and must decide what old, proven concepts should be used and what new, untried ideas should be incorporated. New designs generally have “bugs” or unforeseen problems which must be worked out before the superior characteristics of the new designs can be enjoyed. Thus there is a chance for a superior product, but only at higher risk. It should be emphasized that, if a design does not warrant radical new methods, such methods should not be applied merely for the sake of change. During the beginning stages of design, creativity should be allowed to flourish without a great number of constraints. Even though many impractical ideas may arise, it is usually easy to eliminate them in the early stages of design before firm details are required by manufacturing. In this way, innovative ideas are not inhibited. Quite often, more than one design is developed, up to the point where they can be compared against each other. It is entirely possible that the design which ultimately accepted will use ideas existing in one of the rejected designs that did not show as much overall promise. Psychologists frequently talk about trying to fit people to the machines they operate. It is essentially the responsibility of the design engineer to strive to fit machines to people. This is not an easy task, since there is really no average person for which certain operating dimensions and procedures are optimum. Another important point which should be recognized is that a design engineer must be able to communicate ideas to other people if they are to be incorporated. Initially the designer must communicate a preliminary design to get management approval. This is usually done by verbal discussions in conjunction with drawing layouts and written material. To communicate effectively, the following questions must be answered: (1) Does the design really serve a human need? (2) Will it be competitive with existing products of rival companies? (3) Is it economical to produce? (4) Can it be readily maintained? (5) Will it sell and make a profit? Only time will provide the true answers to the preceding questions, but the product should be designed, manufactured and marketed only with initial affirmative answers. The design engineer also must communicate the finalized design to manufacturing through the use of detail and assembly drawings. Quite often, a problem well occur during the manufacturing cycle. It may be that a change is required in the dimensioning or tolerancing of a part so that it can be more readily produced. This falls in the category of engineering changes which must be approved by the design engineer so that the product function will not be adversely affected. In other cases, a deficiency in the design may appear during assembly or testing just prior to shipping. These realities simply bear out the fact that design is a living process. There is always a better way to do it and the designer should constantly strive towards finding that better way. Machining Turning The engine lathe, one of the oldest metal removal machines, has a number of useful and highly desirable attributes. Today these lathes are used primarily in small shops where smaller quantities rather than large production runs are encountered. The engine lathe has been replaced in today's production shops by a wide variety of automatic lathes such as automatic of single-point tooling for maximum metal removal, and the use of form tools for finish and accuracy, are now at the designer's fingertips with production speeds on a par with the fastest processing equipment on the scene today. Tolerances for the engine lathe depend primarily on the skill of the operator. The design engineer must be careful in using tolerances of an experimental part that has been produced on the engine lathe by a skilled operator. In redesigning an experimental part for production, economical tolerances should be used. Turret Lathes Production machining equipment must be evaluated now, more than ever before, in terms of ability to repeat accurately and rapidly. Applying this criterion for establishing the production qualification of a specific method, the turret lathe merits a high rating. In designing for low quantities such as 100 or 200 parts, it is most economical to use the turret lathe. In achieving the optimum tolerances possible on the turret lathe, the designer should strive for a minimum of operations. Automatic Screw Machines Generally, automatic screw machines fall into several categories; single-spindle automatics, multiple-spindle automatics and automatic chucking machines. Originally designed for rapid, automatic production of screws and similar threaded parts, the automatic screw machine has long since exceeded the confines of this narrow field, and today plays a vital role in the mass production of a variety of precision parts. Quantities play an important part in the economy of the parts machined on the automatic to set up on the turret lathe than on the automatic screw machine. Quantities less than 1000 parts may be more economical to set up on the turret lathe than on the automatic screw machine. The cost of the parts machined can be reduced if the minimum economical lot size is calculated and the proper machine is selected for these quantities. Automatic Tracer Lathes Since surface roughness depends greatly upon material turned, tooling ,and fees and speeds employed, minimum tolerances that can be held on automatic tracer lathes are not necessarily the most economical tolerances. Is some case, tolerances of ±0.05mm are held in continuous production using but one cut. Groove width can be held to ±0.125mm on some parts. Bores and single-point finishes can be held to ±0.0125mm. On high-production runs where maximum output is desirable, a minimum tolerance of ±0.125mm is economical on both diameter and length of turn. Milling With the exceptions of turning and drilling, milling is undoubtedly the most widely used method of removing metal. Well suited and readily adapted to the economical production of any quantity of parts, the almost unlimited versatility of the milling process merits the attention and consideration of designers seriously concerned with the manufacture of their product. As in any other process, parts that have to be milled should be designed with economical tolerances that can be achieved in production milling. If the part is designed with tolerances finer than necessary, additional operations will hav