外文翻译--机械设计及加工工艺
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毕业设计中英文翻译英文原文Hard gear processing[abstract ]uses in the power drive gear and the gear box, its size request smaller, the gear drive noise is lower, thus causes to the hard gear demand, also gave the gear manufacturer to propose explored the gear to process the new method the request OutlineUses in the power drive gear and the gear box, its size request smaller, the gear drive noise is lower, thus causes to the hard gear demand, also gave the gear manufacturer to propose explored the gear to process the new method the request. The gear in the hard heat treatment process, its material organization and the stress change, usually can cause the gear to have the distortion, namely tooth profile, tooth to and tooth pitch error. This this error will cause the tooth profile not correctly to mesh in the transmission time, thus has enlarged the load, will have the gear noise. Therefore, the hard gear after the heat treatment, should increase together the precision work working procedure generally.The hard gear precision work craft may divide into two kinds: A kind is uses non- formed the cutting edge, like the gear rubs truncates the processing; Another kind then is has formed the cutting edge like hard gear (HRC48 ~ 53) to roll truncates the processing.This article strongly will discuss will use in hardly rolling the hard alloy tools forming cutting edge precision work process which the tooth will process. The now hard alloy material, the cutting tool coating and the gear-hobbing machine technology development, has caused the hard gear to roll cuts the processing technology to have the remarkable enhancement, specially is smaller than in the processing or was equal to when 12DP center small modulus gear, may withstand the enormous cutting force which in the hard cutting process produces.Hard alloy hob selectionThe hard alloy hob has the very big progress in the material variety specification. Superfine, is thin, medium or the big pellet hard alloy now all has the product. In addition, the hard alloy hob semifinished materials formed craft technology also had the remarkable enhancement, like uses static pressure and so on heat (HIP) the craft, this craft under the high-pressured high temperature, increased the hard alloy semifinished materials intrinsic binding force, enhanced the hard alloy anti- curved intensity. According to the ISO stipulation, the entity hard alloy material may differently divide into certain kinds according to the application situation: The gear cutting tool divides into K kind and P kind, K kind of hard alloy has a higherresistance to wear, P kind then has the better high temperature red hardness. In the K trademark and in the P trademark hard alloy, each kind of trademark hard alloy granular structure is different, from medium pellet to superfine pellet. Each kind of trademark all has its application situation, this is and the granular structure is connected. Generally speaking, regarding softly rolls truncates, the K analogy P kind of performance is friends with, K kind of hard alloy can obtain a micron level the granular structure (granularity to be smaller than 0.5 mu m), but P kind then is not good. In abrasion aspect, K kind of toughness better, the life is longer.The hob resharpens and renovatesAfter the hob processing certain quantity work piece, its cutting edge failure, this time must resharpen. Sharpens the after hob to have to maintain the original geometry shape; The cutting edge must be sharp; The cutting tool golden phase structure cannot because rub truncates the heat but to destroy. Thus when sharpens the hard alloy hob should use one kind of oil base refrigerant, it does not get up to the chlorine and the sulfur the response. Regarding scrapes the hob, sharpens after the coating not likely to use in hob such which the entity semifinished materials hardly rolls being important again. After the hard alloy hob sharpens in front of the coating, suggested carries on the pretreatment to its cutting edge.The hob rewill sharpen can except the cutting surface original coating, this will be able to reduce the cutting tool life. The cutting tool is may again spread. Usually regarding the TiN coating, may spread 3 ~ 4; Says regarding TiCN and the TiALN coating, because coating itself has the very big internal stress, therefore on cutting edge with difficulty again again coating. After several spreading TiN coating, can have the height non-uniformity condition, and influentials the tendency which the level falls off, therefore the original coating must remove.At present has two methods to be possible to remove the cutting tool coating: Chemistry draws back spreads draws back with physics spreads. Draws back with chemistry spreads removes on the hard alloy tools the coating is one kind of fine craft, requests the operator to have the suitable level of expertise. The excessively chemistry draws back spreads not only removes the coating, moreover also will dissolve washes the cobalt cement, the damage hard alloy material microscopic structure. The cutting edge microscopic damage will produce the zigzag surface. In addition, when draws back spreads must to the hob pillow block, in the hole and the sign carries on the protection, in order to avoid damages. But physics spreads, then must carry on by the original cutting tool factory, it involves to puts in order rerubs the hob tooth profile truncates. Although draws back chemistry spreads must be much more expensive than, but obtains is a new hob, the quality and the life all can obtain the guarantee.To gear-hobbing machine requestIn order to fully displays the hard alloy and the coating craft merit, the gear-hobbing machine should do correspondingly improves. At present all advanced gear-hobbing machines all press high speed roll the tooth to carry on the design, its gear-hobbing machine hob rotational speed surpasses 3000r/Min, usually is5000r/Min, the work piece main axle rotational speed and the hob rotational speed match. In addition, the engine bed has very high moves the rigidity and the hot rigidity. The advanced gear-hobbing machine some main design characteristics are: Uses the compound epoxy resin lathe bed, by improves the engine bed the tendency and the static characteristic; Has the constant temperature installment the high speed hob headstock; High speed work piece main axle; May use does, the wet two kinds rolls truncates the craft; Belt electro-optical sensor digital actuation system; The straight line rolls the guide rail system; High speed automatic high-quality goods (2 ~ 3 seconds); The occupying a land area of is compact; According to man-machine engineering design; Services conveniently.Uses scrapes the craftRegardless of is the mechanical type the CNC gear-hobbing machine all can carry on scrapes, but the condition is the engine bed must equip has the work piece to the cutting tool selsyn train system. This may cause to scrape the craft economically, to has on the automatic yummy treats system the engine bed very to be also important. The electronic non- contact system depends on a simulation quantity sensor to send out the pulse to survey the cutting tool main axle, the work piece main axle and the gear position. The engine bed CNC controller carries on processing to these pulses, then is opposite to the work piece main axle in the cutting tool position carries on the adjustment, causes a work piece turn of tooth and the hob knife tooth relative position relations is correct.In scrapes in the craft to have very many merits with the refrigerant: In scrapes in the process, the refrigerant has provided the lubricating ability; Because scrapes produces is not the normal scrap, the temperature control is extremely important. Blows the scrap small is thin, does not look like normal knife filings such to be possible to carry off many quantity of heats, therefore scrapes time uses the refrigerant to be possible to control the cutting tool, the work piece and the engine bed system temperature; The refrigerant may washes away the scrap from the cutting tool and the work piece; Improved the work piece surface fine roughness; Enhanced the cutting tool life."Rolls in the green truncates" in the craft, correctly chooses the tooth thick remainder is very important. The recommendation choice down milling rolls the tooth, because it may obtain the thickest scrap, this is helpful to the control cutting process dynamic condition, enhances the cutting tool life. The experience proved that, the cutting speed may surpass 200m/Min, enters for the quantity choice is decided by the superficially attractive fineness which must achieve. The model enters for the scope is 0.5 ~ 1.25mm/R. The cutting tool shifts (flees knife) the method very to be also important, because scrapes time only then the rough machining section partial cutting edges only then undergo the attrition. On the contrary, in "the green cutting" in the process, the cutting tool precision work has partially undertaken the main process load. This meant when scraping flees the knife quantity to be supposed to be bigger, when like the gear is 12 ~ 48DP, each time flees the knife quantity is 0.3 ~ 0.4mm.Scrapes the hob the selectionScrapes the hard alloy hob to divide into two big kinds: Uses in 10DP or the bigger modulus hob, usually all designs has a negative rake front the cutting, when the cutting edge contacts to the hard tooth face, reduced to the hard alloy material impact; Regarding the small modulus gear, does not need to have the negative rake. The negative rake hob shortcoming is sharpens the difficulty. After the hob sharpens the outer diameter to reduce, in order to obtain the correct negative rake to be supposed to change the grinding wheel the bias quantity.When scrapes, the big modulus gear, its addendum, the outer annulus diameter and the tooth root spot all are usually not rolled truncates, and has a smooth transition a request turn of tooth to the tooth root. In order to obtain sinks cuts with the integrity transition circular arc radius, enhances the tooth root the anti- curved intensity, uses in the big modulus gear ideal scraping the hob to be supposed to have the flange. Regarding the small modulus gear processing, should use the standard hob. Uses the standard in front of the radial direction the angle hard alloy hob processing to be called "the hard alloy hob to roll again cuts", but is not "scrapes", latter referred has used a negative rake hob.Hardly rolls the specification which truncates and hardly scrapes the specification which, or the hard alloy hob rolls again truncates nearly same, similarity is uses the strategy which flees the knife to shift to be different. When hardly rolls, the scrap excision must spend the massive energies. This energy finally becomes the quantity of heat. Tries to carry off very important these thermal sending out. After the suggestion processes a work piece every time, the hob flees a position entire tooth pitch. When the hob will flee from beginning to end the position from now on, will be supposed to transfer to the hob to the initial position has a bias quantity the spot. This bias quantity is decided by the hob design and the application, its goal is for be helpful to the hob uniform wear. Another one similarity is the attire which uses clamps the system. As a result of the enormous cutting force, the jig must safely clamp the work piece. The processing result indicated that, the identical helical gear when hardly rolls again with the hard alloy hob, its gear quality is very high, the tooth profile approaches the AGMA10 level, the tooth to surpasses the AGMA12 level with the tooth pitch; The entire hard semifinished materials hardly roll cut the processing the helical gear, its gear precision extremely is also high, the tooth profile precision may reach the AGMA10 level, the tooth to may achieve the AGMA12 level with the tooth pitch. ConclusionAt present has explored many economies the method to process the hard gear, including the material choice, the soft processing method, the heat treatment craft and the hard precision work, enable the hard gear to obtain the popularization, has satisfied the high grade transmission device to the hard gear request.Carries on from entity entire hard work piece semifinished materials hardly rolls cuts the processing is one kind of new processing craft. Because has a rigid better engine bed and the high quality hard alloy tools material and performs coating processing, causes hardly to roll slivers is one effective processing method. Indicatedfrom the factory practical application result that, the hard gear rolls cuts (hardly rolls) the craft to have the broad application prospect.译文:淬硬齿轮的加工【摘要】用于动力传动的齿轮和齿轮箱,其尺寸要求更小,齿轮传动的噪音更低,从而导致对淬硬齿轮的需求,也给齿轮制造厂家提出了探索齿轮加工新方法的要求.概述用于动力传动的齿轮和齿轮箱,其尺寸要求更小,齿轮传动的噪音更低,从而导致对淬硬齿轮的需求,也给齿轮制造厂家提出了探索齿轮加工新方法的要求。
机械加工方式作文英语Mechanical Processing。
Mechanical processing, also known as machining, is a process of removing material from a workpiece to achieve the desired shape and size. It is an important manufacturing process that is widely used in various industries, such as automotive, aerospace, and electronics. In this essay, we will discuss the various aspects of mechanical processing, including its history, techniques, and applications.The history of mechanical processing can be traced back to ancient times when primitive tools were used to shape and cut materials. Over the centuries, the process has evolved significantly, with the development of new techniques and technologies. Today, mechanical processingis a highly advanced and precise method of manufacturing, thanks to the use of computer-aided design (CAD) and computer-aided manufacturing (CAM) software.There are several techniques used in mechanical processing, including turning, milling, drilling, and grinding. Turning is a process in which a workpiece is rotated while a cutting tool is used to remove material from the surface. This technique is commonly used to produce cylindrical parts, such as shafts and bushings. Milling, on the other hand, involves the use of a rotating cutting tool to remove material from a workpiece. This technique is used to create complex shapes and features, such as slots and pockets. Drilling is a process in which a rotating cutting tool is used to create holes in a workpiece, while grinding is a process in which a grinding wheel is used to remove material from the surface of a workpiece.Mechanical processing has a wide range of applications, from the production of small, intricate parts to the manufacturing of large, heavy-duty components. In the automotive industry, for example, mechanical processing is used to produce engine components, such as pistons and crankshafts. In the aerospace industry, it is used tomanufacture aircraft parts, such as landing gear and wing components. In the electronics industry, it is used to produce precision components, such as connectors and housings.In conclusion, mechanical processing is a vital manufacturing process that is used in a wide range of industries. It has a long history of development and has evolved into a highly advanced and precise method of manufacturing. With the use of modern techniques and technologies, mechanical processing continues to play a crucial role in the production of a wide variety of components and parts.。
英文】High-speed machining the development ofHigh-speed machining is oriented to the 21st century a new high-tech, high-efficiency, High-precision and high surface quality as a basic feature, in theautomobile industry, aerospace, Die Manufacturing and instrumentation industries gained increasingly widespread application, and has made significant technical and economic benefits. contemporary advanced manufacturing technology an important component part 。
High-speed machining is to achieve high efficiency of the core technology manufacturers, intensive processes and equipment packaged so that it has a high production efficiency. It can be said that the high-speed machining is an increase in the quantity of equipment significantly improve processing efficiency essential to the technology. High-speed machining is the major advantages : improve production efficiency, improve accuracy and reduce the processing of cutting resistance。
附件1:外文资料翻译译文一个复杂纸盒的包装机器人Venketesh N。
Dubey英国设计学院,工程和计算机,伯恩茅斯大学,普尔Jian S。
Dai伦敦大学国王学院,英国伦敦大学,伦敦摘要目的—为了展示设计一种可以折叠复杂几何形状的纸盒的多功能包装机的可行性。
设计/方法/方式—这项研究对各种几何形状的纸盒进行研究,将纸盒分为适当的类型以及机器可以实现的操作;把能加工这些纸盒,并进行机械建模和仿真,且最终可以设计和开发的包装机概念化。
研究结果-这种多功能包装机已经被证明是可能的。
只需将这种多功能包装机小型化,并对它投资以促进其发展,这种机器可以成为现实。
研究限制因素/问题-本研究的目的是证明这种包装机的原理,但实际应用需要考虑结合传感器给出了一个紧凑的、便携式系统。
创意/价值—这项设计是独一无二的,并已被证明可以折叠各种复杂形状的纸盒。
关键字:机器人技术包装自动化文章类型:研究论文1 简介产品包装是关键的工业领域之一,以自动化为首要权益.任何产品流通到消费者手中需要某种形式的包装,无论是食品、礼品或医疗用品。
因此,对高速的产品包装有持续的需求。
对于周期性消费品和精美礼品,这项需求更是大大增加.它们要求包装设计新颖且有吸引力,以吸引潜在客户。
通常这类产品用外观精美、形状复杂的纸盒递送。
如果采用手工方法进行包装,不仅令工人感到乏味且操作复杂,也费时和单调。
对于简单的纸盒包装,通过使用沿传送带布置的专用机器,已经获得了实现。
这些机器只能处理固定类型的纸盒,任何形状和结构的变化很难纳入到系统之中。
在大多数情况下,它们需要进行超过40种变化以适应同种类型但大小不同的纸盒,这就意味着每一个特定类型的纸盒需要一条包装生产线。
从一种类型到另一种类型的纸盒折叠组装生产线的转换将会使资本支出增加。
因为这些限制因素和转换生产线的相关成本,包装的灵活性将会失去。
因此,作为一种补充,手工生产线被引进以适应不同类型的纸盒的生产,从而解决转换生产线的问题.它们承担了大约10%的工作订单,并被用作生产促销产品的组装生产线.但是,问题仍然存在,手工生产线上的管理员和操作工需要一个长时间的学习过程,而且与机器生产线不同,劳动伤害主要是源于扭手动作.此外,手工生产线通常被认为是一个季节性的生产力,仍然需要专门的机器长年运行,以节约成本和时间。
外文文献原稿和译文原稿Process Planning and Concurrent EngineeringT. Ramayah and Noraini IsmailABSTRACTTh e product design is the plan for the product and its components and subassemblies. To convert the product design into a physical entity, a manufacturing plan is needed. The activity of developing such a plan is called process planning. It is the link between product design and manufacturing. Process planning involves determining the sequence of processing and assembly steps that must be accomplished to make the product. In the present chapter, we examine processing planning and several related topics.Process PlanningPr ocess planning involves determining the most appropriate manufacturing and assembly processes and the sequence in which they should be accomplished to produce a given part or product according to specifications set forth in the product design documentation. The scope and variety of processes that can be planned are generally limited by the available processing equipment and technological capabilities of the company of plant. Parts that cannot be made internally must be purchased from outside vendors. It should be mentioned that the choice of processes is also limited by the details of the product design. This is a point we will return to later.Process planning is usually accomplished by manufacturing engineers. The processplanner must be familiar with the particular manufacturing processes available in the factory and be able to interpret engineering drawings. Based on the planner’s knowledge, skill, and experience, the processing steps are developed in the most logical sequence to make each part. Following is a list of the many decisions and details usually include within the scope of process planning..nterpretation of design drawings.The part of product design must be analyzed (materials, dimensions, tolerances, surface finished, etc.) at the start of the process planning procedure..Process and sequence.The process planner must select which processes are required and their sequence. A brief description of processing steps must be prepared..Equipment selection. In general, process planners must develop plans that utilize existing equipment in the plant. Otherwise, the component must be purchased, or an investment must be made in new equipment..Tools, dies, molds, fixtures, and gages.The process must decide what tooling is required for each processing step. The actual design and fabrication of these tools is usually delegated to a tool design department and tool room, or an outside vendor specializing in that type of tool is contacted..Methods analysis.Workplace layout, small tools, hoists for lifting heavy parts, even in some cases hand and body motions must be specified for manual operations. The industrial engineering department is usually responsible for this area..Work standards.Work measurement techniques are used to set time standards for each operation..Cutting tools and cutting conditions.These must be specified for machining operations, often with reference to standard handbook recommendations.Process planning for partsO r individual parts, the processing sequence is documented on a form called a route sheet. Just as engineering drawings are used to specify the product design, route sheets are used to specify the process plan. They are counterparts, one for product design, the other for manufacturing.Typical processing sequence to fabricate an individual part consists of: (1) a basic process, (2) secondary processes, (3) operations to enhance physical properties, and (4) finishing operations. A basic process determines the starting geometry of the work parts. Metal casting, plastic molding, and rolling of sheet metal are examples of basic processes. The starting geometry must often be refined by secondary processes, operations that transform the starting geometry (or close to final geometry). The secondary geometry processes that might be used are closely correlated to the basic process that provides the starting geometry. When sand casting is the basic processes, machining operations are generally the second processes. When a rolling mill produces sheet metal, stamping operations such as punching and bending are the secondary processes. When plastic injection molding is the basic process, secondary operations are often unnecessary, because most of the geometric features that would otherwise require machining can be created by the molding operation. Plastic molding and other operation that require no subsequent secondary processing are called net shape processes. Operations that require some but not much secondary processing (usually machining) are referred to as near net shape processes. Some impression die forgings are in this category. These parts can often be shaped in the forging operation (basic processes) so that minimal machining (secondary processing) is required.The geometry has been established, the next step for some parts is to improve their mechanical and physical properties. Operations to enhance properties do not alter the geometry of the part; instead, they alter physical properties. Heat treating operations on metal parts are the most common examples. Similar heating treatments are performed on glass to produce tempered glass. For most manufactured parts, these property-enhancing operations are not required in the processing sequence.Finally finish operations usually provide a coat on the work parts (or assembly) surface. Examples included electroplating, thin film deposition techniques, and painting. The purpose of the coating is to enhance appearance, change color, or protect the surface from corrosion, abrasion, and so forth. Finishing operations are not required on many parts; for example, plastic molding rarely require finishing. Whenfinishing is required, it is usually the final step in the processing sequence. Processing Planning for AssembliesTh e type of assembly method used for a given product depends on factors such as: (1) the anticipated production quantities; (2) complexity of the assembled product, for example, the number of distinct components; and (3) assembly processes used, for example, mechanical assembly versus welding. For a product that is to be made in relatively small quantities, assembly is usually performed on manual assembly lines. For simple products of a dozen or so components, to be made in large quantities, automated assembly systems are appropriate. In any case, there is a precedence order in which the work must be accomplished. The precedence requirements are sometimes portrayed graphically on a precedence diagram.Process planning for assembly involves development of assembly instructions, but in more detail .For low production quantities, the entire assembly is completed at a single station. For high production on an assembly line, process planning consists of allocating work elements to the individual stations of the line, a procedure called line balancing. The assembly line routes the work unit to individual stations in the proper order as determined by the line balance solution. As in process planning for individual components, any tools and fixtures required to accomplish an assembly task must be determined, designed, built, and the workstation arrangement must be laid out. Make or Buy DecisionAn important question that arises in process planning is whether a given part should be produced in the company’s own factory or purchased from an outside vendor, and the answer to this question is known as the make or buy decision. If the company does not possess the technological equipment or expertise in the particular manufacturing processes required to make the part, then the answer is obvious: The part must be purchased because there is no internal alternative. However, in many cases, the part could either be made internally using existing equipment, or it could be purchasedexternally from a vendor that process similar manufacturing capability.In our discussion of the make or buy decision, it should be recognized at the outset that nearly all manufactures buy their raw materials from supplies. A machine shop purchases its starting bar stock from a metals distributor and its sand castings from a foundry. A plastic molding plant buys its molding compound from a chemical company. A stamping press factory purchases sheet metal either fro a distributor or direct from a rolling mill. Very few companies are vertically integrated in their production operations all the way from raw materials, it seems reasonable to consider purchasing at least some of the parts that would otherwise be produced in its own plant. It is probably appropriate to ask the make or buy question for every component that is used by the company.Here are a number of factors that enter into the make or buy decision. One would think that cost is the most important factor in determining whether to produce the part or purchase it. If an outside vendor is more proficient than the company’s own plant in the manufacturing processes used to make the part, then the internal production cost is likely to be greater than the purchase price even after the vendor has included a profit. However, if the decision to purchase results in idle equipment and labor in the company’s own plant, then the apparent advantage of purchasing the part may be lost. Consider the following example make or Buy Decision.The quoted price for a certain part is $20.00 per unit for 100 units. The part can be produced in the company’s own plant for $28.00. The components of making the part are as follows:Unit raw material cost = $8.00 per unitDirect labor cost =6.00 per unitLabor overhead at 150%=9.00 per unitEquipment fixed cost =5.00 per unit________________________________Total =28.00 per unitShould the component by bought or made in-house?Solution: Although the vendor’s quote seems to favor a buy decision, let us consider the possible impact on plant operations if the quote is accepted. Equipment fixed cost of $5.00 is an allocated cost based on investment that was already made. If the equipment designed for this job becomes unutilized because of a decision to purchase the part, then the fixed cost continues even if the equipment stands idle. In the same way, the labor overhead cost of $9.00 consists of factory space, utility, and labor costs that remain even if the part is purchased. By this reasoning, a buy decision is not a good decision because it might be cost the company as much as $20.00+$5.0+$9.00=$34.00 per unit if it results in idle time on the machine that would have been used to produce the part. On the other hand, if the equipment in question can be used for the production of other parts for which the in-house costs are less than the corresponding outside quotes, then a buy decision is a good decision.ake or buy decision are not often as straightforward as in this example. A trend in recent years, especially in the automobile industry, is for companies to stress the importance of building close relationships with parts suppliers. We turn to this issue in our later discussion of concurrent engineering.Computer-aided Process PlanningHere is much interest by manufacturing firms in automating the task of process planning using computer-aided process planning (CAPP) systems. The shop-trained people who are familiar with the details of machining and other processes are gradually retiring, and these people will be available in the future to do process planning. An alternative way of accomplishing this function is needed, and CAPPsystems are providing this alternative. CAPP is usually considered to be part of computer-aided manufacturing (CAM). However, this tends to imply that CAM is a stand-along system. In fact, a synergy results when CAM is combined with computer-aided design to create a CAD/CAM system. In such a system, CAPP becomes the direct connection between design and manufacturing. The benefits derived from computer-automated process planning include the following: .Process rationalization and standardization. Automated process planning leads to more logical and consistent process plans than when process is done completely manually. Standard plans tend to result in lower manufacturing costs and higher product quality..Increased productivity of process planner. The systematic approach and the availability of standard process plans in the data files permit more work to be accomplished by the process planners..Reduced lead time for process planning. Process planner working with a CAPP system can provide route sheets in a shorter lead time compared to manual preparation..Improved legibility. Computer-prepared rout sheets are neater and easier to read than manually prepared route sheets..Incorporation of other application programs. The CAPP program can be interfaced with other application programs, such as cost estimating and work standards.Computer-aided process planning systems are designed around two approaches. These approaches are called: (1) retrieval CAPP systems and (2) generative CAPP systems .Some CAPP systems combine the two approaches in what is known as semi-generative CAPP.Concurrent Engineering and Design for ManufacturingOncurrent engineering refers to an approach used in product development in which the functions of design engineering, manufacturing engineering, and other functions are integrated to reduce the elapsed time required to bring a new product to market. Also called simultaneous engineering, it might be thought of as the organizationalProduct design Manufacturing engineering and process planning Production and assembly The “wall” bet ween design and manufacturing Product launch time, traditional design/manufacturing cycle Difference in product launch time (a)Traditional product development cycle Product design Sales and marketing Quality engineering Vendors Manufacturing engineering and process planning Production and assemblyProduct laugh time,concurrent engineering(b) Product development using concurrent engineeringcounterpart to CAD/CAM technology. In the traditional approach to launching a new product, the two functions of design engineering and manufacturing engineering tend to be separated and sequential, as illustrated in Fig.(1).(a).The product design department develops the new design, sometimes without much consideration given to the manufacturing capabilities of the company, There is little opportunity for manufacturing engineers to offer advice on how the design might be alerted to make it more manufacturability. It is as if a wall exits between design and manufacturing. When the design engineering department completes the design, it tosses the drawings and specifications over the wall, and only then does process planning begin.g.(1). Comparison: (a) traditional product development cycle and (b) product development using concurrent engineeringContrast, in a company that practices concurrent engineering, the manufacturing engineering department becomes involved in the product development cycle early on, providing advice on how the product and its components can be designed to facilitate manufacture and assembly. It also proceeds with early stages of manufacturing planning for the product. This concurrent engineering approach is pictured in Fig.(1).(b). In addition to manufacturing engineering, other function are also involved in the product development cycle, such as quality engineering, the manufacturing departments, field service, vendors supplying critical components, and in some cases the customer who will use the product. All if these functions can make contributions during product development to improve not only the new product’s function and performance, but also its produceability, inspectability, testability, serviceability, and maintainability. Through early involvement, as opposed to reviewing the final product design after it is too late to conveniently make any changes in the design, the duration of the product development cycle is substantially reduced.On current engineering includes several elements: (1) design for several manufacturing and assembly, (2) design for quality, (3) design for cost, and (4) design for life cycle. In addition, certain enabling technologies such as rapid prototyping, virtual prototyping, and organizational changes are required to facilitate the concurrent engineering approach in a company.Design for Manufacturing and AssemblyIt has been estimated that about 70% of the life cycle cost of a product is determined by basic decisions made during product design. These design decisions include the material of each part, part geometry, tolerances, surface finish, how parts are organized into subassemblies, and the assembly methods to be used. Once these decisions are made, the ability to reduce the manufacturing cost of the product is limited. For example, if the product designer decides that apart is to be made of analuminum sand casting but which processes features that can be achieved only by machining(such as threaded holes and close tolerances), the manufacturing engineer has no alternative expect to plan a process sequence that starts with sand casting followed by the sequence of machining operations needed to achieve the specified features .In this example, a better decision might be to use a plastic molded part that can be made in a single step. It is important for the manufacturing engineer to be given the opportunity to advice the design engineer as the product design is evolving, to favorably influence the manufacturability of the product.Erm used to describe such attempts to favorably influence the manufacturability of a new product are design for manufacturing (DFM) and design for assembly(DFA). Of course, DFM and DFA are inextricably linked, so let us use the term design for manufacturing and assembly (DFM/A). Design for manufacturing and assembly involves the systematic consideration of manufacturability and assimilability in the development of a new product design. This includes: (1) organizational changes and (2) design principle and guidelines..Organizational Changes in DFM/A.Effective implementation of DFM/A involves making changes in a company’s organization structure, either formally or informally, so that closer interaction and better communication occurs between design and manufacturing personnel. This can be accomplished in several ways: (1)by creating project teams consisting of product designers, manufacturing engineers, and other specialties (e.g. quality engineers, material scientists) to develop the new product design; (2) by requiring design engineers to spend some career time in manufacturing to witness first-hand how manufacturability and assembility are impacted by a product’s design; and (3)by assigning manufacturing engineers to the product design department on either a temporary or full-time basis to serve as reducibility consultants..Design Principles and Guidelines.DFM/A also relies on the use of design principles and guidelines for how to design a given product to maximize manucturability and assembility. Some of these are universal design guidelines that can be applied to nearly any product design situation. There are design principles thatapply to specific processes, and for example, the use of drafts or tapers in casted and molded parts to facilitate removal of the part from the mold. We leave these more process-specific guidelines to texts on manufacturing processes.The guidelines sometimes conflict with one another. One of the guidelines is to “simplify part geometry, avoid unnecessary features”. But another guideline in the same table states that “spe cial geometric features must sometimes be added to components” to design the product for foolproof assembly. And it may also be desirable to combine features of several assembled parts into one component to minimize the number of parts in the product. In these instances, design for part manufacture is in conflict with design for assembly, and a suitable compromise must be found between the opposing sides of the conflict.译文工艺规程制订与并行工程T. Ramayah and Noraini Ismail摘要产品设计是用于产品,及它的部件装配的计划。
机械设计外文文献翻译、中英文翻译unavailable。
The first step in the design process is to define the problem and XXX are defined。
the designer can begin toXXX evaluated。
and the best one is XXX。
XXX.Mechanical DesignA XXX machines include engines。
turbines。
vehicles。
hoists。
printing presses。
washing machines。
and XXX and methods of design that apply to XXXXXX。
cams。
valves。
vessels。
and mixers.Design ProcessThe design process begins with a real need。
Existing apparatus may require XXX。
efficiency。
weight。
speed。
or cost。
while new apparatus may be XXX。
To start。
the designer must define the problem and XXX。
ideas and concepts are generated。
evaluated。
and refined until the best one is XXX。
XXX.XXX。
assembly。
XXX.During the preliminary design stage。
it is important to allow design XXX if some ideas may seem impractical。
they can be corrected early on in the design process。
外文资料原文及译文学院:机电工程学院专业:机械设计制造及其自动化班级:学号:姓名:Mechanical engineering1.The porfile of mechanical engineeringEngingeering is a branch of mechanical engineerig,itstudies mechanical and power generation especially power and movement.2.The history of mechanical engineering18th century later periods,the steam engine invention hasprovided a main power fountainhead for the industrialrevolution,enormously impelled each kind of mechznicalbiting.Thus,an important branch of a new Engineering –separated from the civil engineering tools and machines on thebranch-developed together with Birmingham and the establishment of the Associantion of Mechanical Engineers in1847 had been officially recognized.The mechanicalengineering already mainly used in by trial and error methodmechanic application technological development intoprofessional engineer the scientific method of which in theresearch,the design and the realm of production used .From themost broad perspective,the demend continuously to enhance theefficiencey of mechanical engineers improve the quality of work,and asked him to accept the history of the high degreeof education and training.Machine operation to stress not onlyeconomic but also infrastructure costs to an absolute minimun.3.The field of mechanical engineeringThe commodity machinery development in the develop country,in the high level material life very great degree is decided each kind of which can realize in the mechanical engineering.Mechanical engineers unceasingly will invent the machine next life to produce the commodity,unceasingly will develop the accuracy and the complexity more and more high machine tools produces the machine.The main clues of the mechanical development is:In order to enhance the excellent in quality and reasonable in price produce to increase the precision as well as to reduce the production cost.This three requirements promoted the complex control system development.The most successful machine manufacture is its machine and the control system close fusion,whether such control system is essentially mechanical or electronic.The modernized car engin production transmission line(conveyer belt)is a series of complex productions craft mechanization very good example.The people are in the process of development in order to enable further automation of the production machinery ,the use of a computer to store and handle large volumes of data,the data is a multifunctional machine toolsnecessary for the production of spare parts.One of the objectives is to fully automated production workshop,three rotation,but only one officer per day to operate.The development of production for mechanical machinery must have adequate power supply.Steam engine first provided the heat to generate power using practical methods in the old human,wind and hydropower,an increase of engin .New mechanical engineering industry is one of the challenges faced by the initial increase thermal effciency and power,which is as big steam turbine and the development of joint steam boilers basically achieved.20th century,turbine generators to provide impetus has been sustained and rapid growth,while thermal efficiency is steady growth,and large power plants per kW capital consumption is also declining.Finally,mechanical engineers have nuclear energy.This requires the application of nuclear energy particularly high reliability and security, which requires solving many new rge power plants and the nuclear power plant control systems have become highly complex electroonics,fluid,electricity,water and mechanical parts networks All in all areas related to the mechanical engineers.Small internal combustion engine,both to the type (petrol and diesel machines)or rotary-type(gas turbines andMong Kerr machine),as well as their broad application in the field of transport should also due to mechanical enginerrs.Throughout the transport,both in the air and space,or in the terrestrial and marine,mechanial engineers created a variety of equipment and power devices to their increasing cooperation with electrical engineers,especially in the development of appropration control systems.Mechanical engineers in the development of military weapons technology and civil war ,needs a similar,though its purpose is to enhance rather than destroy their productivity.However.War needs a lot of resources to make the area of techonlogy,many have a far-reaching development in peacetime efficiency.Jet aircraft and nuclear reactors are well known examples.The Biological engineering,mechanical engineering biotechnology is a relatively new and different areas,it provides for the replacement of the machine or increase the body functions as well as for medical equipment.Artficial limbs have been developed and have such a strong movement and touch response function of the human body.In the development of artificial organ transplant is rapid,complex cardiac machines and similar equipment to enable increasingly complex surgery,and injuries and ill patients life functions can besustained.Some enviromental control mechanical engineers through the initial efforts to drainage or irrigation pumping to the land and to mine and ventilation to control the human environment.Modern refrigeration and air-conditioning plant commonaly used reverse heat engine,where the heat from the engine from cold places to more external heat.Many mechanical engineering products,as well as other leading technology development city have side effects on the environment,producing noise,water and air pollution caused,destroyed land and landscape.Improve productivity and diver too fast in the commodity,that the renewable natural forces keep pace.For mechanical engineers and others,environmental control is rapidly developing area,which includes a possible development and production of small quantities of pollutants machine sequnce,and the development of new equipment and teachnology has been to reduce and eliminate pollution.4.The role of mechanical engineeringThere are four generic mechanical engineers in common to the above all domains function.The 1st function is the understanding and the research mechanical science foundation.It includes the power and movement of therelationship dynamics For example,in the vibration and movement of the relationship;Automatic control;Study of the various forms of heart,energy,power relations between the thermodynamic;Fluidflows; Heat transfer; Lubricant;And material properties.The 2nd function will be conducts the research,the desing and the development,this function in turn attempts to carry on the essential change to satisfy current and the future needs.This not only calls for a clear understanding of mechanical science,and have to break down into basic elements of a complex system capacity.But also the need for synthetic and innovative inventions.The 3rd function is produces the product and the power,include plan,operation and maintenance.Its goal lies in the maintenance either enhances the enterprise or the organization longer-tern and survivabilaty prestige at the same time,produces the greatest value by the least investments and the consumption.The 4th function is mechanical engineer’s coordinated function,including the management,the consultation,as well as carries on the market marking in certain situation.In all these function,one kind unceasingly to use the science for a long time the method,but is not traditional orthe intuition method tendency,this is a mechanical engineering skill aspect which unceasingly grows.These new rationalization means typical names include:The operations research,the engineering economics,the logical law problem analysis(is called PABLA) However,creativity is not rationalization.As in other areas,in mechanical engineering, to take unexpected and important way to bring about a new capacity,still has a personal,marked characteristice.5.The design of mechanical engineeringThe design of mechanical is the design has the mechanical property the thing or the system,such as:the instrument and the measuring appliance in very many situations,the machine design must use the knowledge of discipline the and so on mathematics,materials science and mechanics.Mechanical engineering desgin includeing all mechanical desgin,but it was a study,because it also includes all the branches of mechsnical engineering,such as thermodynamics all hydrodynamics in the basic disciplines needed,in the mechanical engineering design of the initial stude or mechanical design.Design stages.The entire desgin process from start to finish,in the process,a demand that is designed for it and decided to do the start.After a lot of repetition,thefinal meet this demand by the end of the design procees and the plan.Design considerations.Sometimes in a system is to decide which parts needs intensity parts of geometric shapes and size an important factor in this context that we must consider that the intensity is an important factor in the design.When we use expression design considerations,we design parts that may affect the entire system design features.In the circumstances specified in the design,usually for a series of such functions must be taken into account.Howeever,to correct purposes,we should recognize that,in many cases the design of important design considerations are not calculated or test can determine the components or systems.Especially students,wheen in need to make important decisions in the design and conduct of any operation that can not be the case,they are often confused.These are not special,they occur every day,imagine,for example,a medical laboratory in the mechanical design,from marketing perspective,people have high expectations from the strength and relevance of impression.Thick,and heavy parts installed together:to produce a solid impression machines.And sometimes machinery and spare parts from the design style is the point and not the other point of view.Our purpose is to make those you do notbe misled to believe that every design decision will need reasonable mathematical methods.Manufacturing refers to the raw meterials into finished products in the enterprise.Create three distinct phases.They are:input,processing exprot.The first phase includes the production of all products in line with market needs essential.First there must be the demand for the product,the necessary materials,while also needs such as energy,time,human knowledge and technology resourcess . Finall,the need for funds to obtain all the other resources. Lose one stage after the second phase of the resources of the processes to be distributed.Processing of raw materials into finished products of these processes.To complete the design,based on the design,and then develop plans.Plan implemented through various production processes.Management of resources and processes to ensure efficiency and productivity.For example,we must carefully manage resources to ensure proper use of funds.Finally,people are talking about the product market was cast.Stage is the final stage of exporting finished or stage.Once finished just purchased,it must be delivered to the users.According to product performance,installation and may have to conduct furtherdebugging in addition,some products,especially those very complex products User training is necessary.6.The processes of materials and maunfacturingHere said engineering materials into two main categories:metals and non-ferrous,high-performance alloys and power metals.Non-metallic futher divided into plastice,synthetic rubber,composite materials and ceramics.It said the production proccess is divided into several major process,includingshape,forging,casting/ founding,heat treatment,fixed/connections ,measurement/ quality control and materal cutting.These processes can be further divide into each other’s craft.Various stages of the development of the manufacturing industry Over the years,the manufacturing process has four distinct stages of development, despite the overlap.These stages are:The first phase is artisanal,the second Phase is mechanization.The third phase is automation the forth Phase is integrated.When mankind initial processing of raw materials into finished products will be,they use manual processes.Each with their hands and what are the tools manuslly produced.This is totally integrated production take shape.A person needs indentification,collection materials,the design of a productto meet that demand,the production of such products and use it.From beginning to end,everything is focused on doing the work of the human ter in the industrial revolution introduced mechanized production process,people began to use machines to complete the work accomplished previously manual. This led to the specialization.Specialization in turn reduce the manufacture of integrated factors.In this stage of development,manufacturing workers can see their production as a whole represent a specific piece of the part of the production process.One can not say that their work is how to cope with the entire production process,or how they were loaded onto a production of parts finished.Development of manufacting processes is the next phase of the selection process automation.This is a computer-controlled machinery and processes.At this stage,automation island began to emerge in the workshop lane.Each island represents a clear production process or a group of processes.Although these automated isolated island within the island did raise the productivity of indivdual processes,but the overall productivity are often not change.This is because the island is not caught in other automated production process middle,but not synchronous with them .The ultimate result is the efficient working fast parkedthrough automated processes,but is part of the stagnation in wages down,causing bottlenecks.To better understand this problem,you can imagine the traffic in the peak driving a red light from the red Service Department to the next scene. Occasionally you will find a lot less cars,more than being slow-moving vehicles,but the results can be found by the next red light Brance.In short you real effect was to accelerate the speed of a red Department obstruction offset.If you and other drivers can change your speed and red light simultaneously.Will advance faster.Then,all cars will be consistent,sommth operation,the final everyone forward faster.In the workshop where the demand for stable synchronization of streamlined production,and promoted integration of manufacturing development.This is a still evolving technology.Fully integrated in the circumstances,is a computer-controllrd machinery and processing.integrated is completed through computer.For example in the preceding paragraph simulation problems,the computer will allow all road vehicles compatible with the change in red.So that everyone can steady traffic.Scientific analysis of movement,timing and mechanics of the disciplines is that it is composed of two pater:staticsand dynamics.Statics analyzed static system that is in the system,the time is not taken into account,research and analysis over time and dynamics of the system change.Dynameics from the two componets.Euler in 1775 will be the first time two different branches: Rigid body movement studies can conveniently divided into two parts:geometric and mechanics.The first part is without taking into account the reasons for the downward movement study rigid body from a designated location to another point of the movement,and must use the formula to reflect the actual,the formula would determine the rigid body every point position. Therefore,this study only on the geometry and,more specifically,on the entities from excision.Obviously,the first part of the school and was part of a mechanical separation from the principles of dynamics to study movement,which is more than the two parts together into a lot easier.Dynamics of the two parts are subsequently divided into two separate disciplines,kinematic and dynamics,a study of movement and the movement strength.Therefore,the primary issue is the design of mechanical systems understand its kinematic.Kinematic studies movement,rather than a study of its impact.In a more precise kinematic studies position,displacement,rotation,speed,velocity and acceleration of disciplines,for esample,or planets orbiting research campaing is a paradigm.In the above quotation content should be pay attention that the content of the Euler dynamics into kinematic and rigid body dynamics is based on the assumption that they are based on research.In this very important basis to allow for the treatment of two separate disciplines.For soft body,soft body shape and even their own soft objects in the campaign depends on the role of power in their possession.In such cases,should also study the power and movement,and therefore to a large extent the analysis of the increased complexity.Fortunately, despite the real machine parts may be involved are more or less the design of machines,usually with heavy material designed to bend down to the lowest parts.Therefore,when the kinematic analysis of the performance of machines,it is often assumed that bend is negligible,spare parts are hard,but when the load is known,in the end analysis engine,re-engineering parts to confirm this assnmption.机械工程1.机械工程简介机械工程是工程学的一个分支,它研究机械和动力的产,尤其是力和动力。
外文原文:Mechanical Design and Manufacturing ProcessesMechanical 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 mechanical design are typically called designers, or design engineers. Mechanical 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 ofmaterials and manufacturing processes.As stated previously, the purpose of mechanical 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 berecognized,therefore, that a human need must be identified before a particular product is designed.Mechanical design should be considered to be an opportunity to use innovative talents to envision a design of a product, to analyze the system and then make sound judgments on how the 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 required 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 if 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 sincemany 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 earlystages of design before firm details are required by manufac-turing. 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 is 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. 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. Theseare 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 deal to be learned from a failure,and the greatest gains are obtained by those willing to risk defeat. In the final analysis, the real failure would lie in deciding not to make the presentation at all. 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 will occur during the manufacturing cycle[3]. 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 fails in the category of engineering changes which must be approved by the design engineer so that the product functionwill 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.Designing starts with a need,real or imagined.Existing apparatus may need improvements in durability, efficiently, weight, speed, or cost. New apparatus maybe needed to perform a function previously done by men, such as computation, assembly, or servicing. With the obj ective wholly or partly defined, the next step in design is the conception of mechanisms and their arrangements that will perform the needed functions.For this, freehand sketching is of great value, not only as a record of one's thoughts and as an aid in discussion with others, but particularly for communication with one's own mind, as a stimulant for creative ideas. to fluctuating stress, particular attention is given to a reduction in stress concentration, and to an increase of strength at fillets, threads, holes, and fits. Stress reduction are made by modification in shape, and strengthening may be done by prestressing treatments such as surface rolling and shallow hardening. Hollow shafts and tubing, and box sections give a favorable stress distribution, together with stiffness and minimum weight. Sufficient stiffness to maintain alignment and uniform pressure between contacting surfaces should be provided for crank, cam, and gear shafts, and for enclosures and frames containing bearing supports. The stiffness of shafts and other components must be suitable to avoid resonant vibrations.e &zsic equations to calculate and optimize dimensions.The fundamental equations of mechanics and the other sciences are the accepted bases for calculations. They are sometimes rearranged in special forms to facilitate the determination or optimization of dimensions, such as the beam and surface stress equations for determining gear-tooth size. Factors may be added to a fundamental equation for conditions not analytically determinable, e. g. , on thin steel tubes, an allowance for corrosion added to the thickness based on pressure. When it is necessary to apply a fundamental equation to shapes, materials, or conditions which only approximate the assumptions for its derivation, it is done in a manner which gives results "on the safe side".In situations where data are incomplete, equations of the sciences may be used as proportioning guides to extend a satisfactory design to new capacities.4.Choose materials for a combination of properties.Materials should be chosen fora combination of pertinent properties, not only for strengths, hardness, and weight, but sometimes for resistance to impact, corrosion, and low or high temperatures. Cost and fabrication properties are factors, such as weldability, machinability, sensitivity to variation in heat-treating temperatures, and required coating.5.Select carefully between stock and integral components. A previously developed components is frequently selected by a designer and his company from the stocks of parts manufacturers, if the component meet the performance and reliability requirements and is adaptable without additional development costs to the particular machine being designed.However, its selection should be carefully made wi'th a full knowledge of its propcrties, since the reputation and liability of the company suffer if there is a failure in any one of the machine's parts. In other eases the strength, reliability, and cost requirements are better met if the designer of the machine also designs the component, with the particular advantage of compactness if it is designs integral with other components, e. g., gears to be forged in clusters or integral with a shaft.6. Provide for accurate location and non interference of parts in assembly. A good design provides for the correct locating of parts and for easy assembly and repair.Shoulders and pilot surfaces give accurate location without measurement during assembly. Shapes can be designed so that parts cannot be assembled backwards or in the wrong place. Interferences, as between screws in tapped holes, and between linkages must he foreseen and prevended.Inaccurate alignment and positioning between such assemblies must be avoided, or provision must be made to minimize any resulting detrimental displacements and stresses.The human race has distinguished itself from all other forms of life by using tools and intelligence to create items that serve to make life easier and more enjoyable. Through the centuries, both the tools and theenergy sources to power these tools have evolved to meet the increasing sophistication and complexity ofmankind's ideas.In their earliest forms, tools primarily consisted of stone instruments. Considering tile relative simplicity of the items being made and the materials being shaped, stone was adequate. When iron tools were invented, durable metals and more sophisticated articles could be produced. The twentieth century has seen the creation of products made from the most durable and,consequently, the most unmachinable materials in history. In an effort to meet the manufacturing challenges created by these materials, tools have now evolved to include materials such as alloy steel, carbide, diamond, and ceramics.A similar evolution has taken place with the methods used to power our tools. Initially,tools were powered by muscles; either human or animal. However as the powers of water, wind, steam, and electricity were harnessed, mankind was able tofurther extended manufacturing capabilities with new machines, greater accuracy, and faster machining rates.Every time new tools, tool materials, and power sources are utilized, the efficiency and capabilities of manufacturers are greatly enhanced. However as old problems are solved, new problems and challenges arise so that the manufacturers of today are faced with tough questions such as the following: How do you drill a 2 mm diameter hole 670 mm deep without experiencing taper or runout? Is there a way to efficiently deburr passageways inside complex castings and guarantee 100 % that no burrs were missed? Is there a welding process that can eliminate the thermal damage now occurring to my product?Since the 1940s, a revolution in manufacturing has been taking place that once again allows manufacturers to meet the demands imposed by increasingly sophisticated designs and durable, but in many cases nearly unmachinable, materials. This manufacturing revolution is now, as it has been in the past, centered on the use of new tools and new forms of energy.The result has been the introduction of new manufacturing processes used for material removal, forming, and joining, known today as nontraditional manufacturing processes.The conventional manufacturing processes in use today for material removal primarily rely on electric motors and hard tool materials to perform tasks such as sawing, drilling, an broaching. Conventional forming operations are performed with the energy from electric motors, hydraulics, and gravity. Likewise, material joining is conventionally accomplished with thermal energy sources such as burning gases and electric arcs.In contrast, nontraditional manufacturing processes harness energy sources considered unconventional by yesterday's standards. Material removal can now be accomplished with electrochemical reactions, high-temperature plasmas, and high-velocity jets of liquids and abrasives. Materials that in the past have been extremely difficult to form, are now formed with magnetic fields, explosives, and the shock waves from powerful electric sparks. Material-joining capabilities have been expanded with the use of high-frequency sound waves and beams of electrons.In the past 50 years, over 20 different nontraditional manufacturing processes have been invented andsuccessfully implemented into production. The reason there are such a large number of nontraditional processes is the same reason there aresuch a large number of conventional processes; each process has its own characteristic attributes and limitations, hence no one process is best for all manufacturing situations.For example, nontraditional process are sometimes applied to increase productivity either by reducing the number of overall manufacturing operations required to produce a product or by performing operations faster than the previously used method.In other cases, nontraditional processes are used to reduce the number of rejects experienced by the old manufacturing method by increasing repeatability, reducing in-process breakage of fragile workpieces, or by minimizing detrimental effects on workpiece properties.Because of the aforementioned attributes, nontraditional manufacturing processes have experienced steady growth since their introduction. An increasing growth rate for these processes in the future is assured for the following reasons:1.Currently, nontraditional processes possess virtually unlimited capabilities when compared with conventional processes, except for volumetric material removal rates. Great advances have been made in the past few years in increasing the removal rates of some of these processes, and there is no reason to believe that this trend will not continue into the future.2. Approximately one half of the nontraditional manufacturing processes are available with computer control of the process parameters. The use of computers lends simplicity to processes that people may be unfamiliar with, and thereby accelerates acceptance.Additionally, computer control assures reliability and repeatability[s], which also accelerates acceptance and implementation.3.Most nontraditional processes are capable of being adaptively-controlled through the use of vision systems, laser gages, and other in-process inspection techniques. If, for example, the in-process inspection system determines that the size of holes being produced in a product are becoming smaller, the size can be modified without changing hard tools, such as drills.4.The implementation of nontraditional manufacturing processes will continus to increase as manufacturing engineers, product designers, and metallurgical engineers become increasingly aware of the unique capabilties and benefits that nontraditional manufacturing processes provide.The high speed milling processing is more and more high to the numericalcontrol programming system request, the price expensive high speed processing equipment proposed a higher secure and the valid request to the software. The high-speed cutting has compared to the traditional cutting special technological requirement, besides must have the high-speed cutting engine bed and the high-speed cutting cutting tool, has the appropriate CAM programming software also is very important. The numerical control processing numerical control instruction has contained all technological process, outstanding high speed processes the CAM programming system to be supposed to have the very high computation speed, strong inserts makes up the function, the entire journey is automatic has cut the inspection and the handling ability, the automatic hilt and the jig interference inspection, enters for rate the optimized processing function, treats the processing path monitoring function, the cutting tool path edition optimization function and the processing remaining analysis function and so on. The high-speed cutting programming first must pay attention to the processing method the security and the validity; Next, must guarantee with utmost effort the cutting tool path smooth is steady, this can affect components the directly and so on processing quality and engine bed main axle life; Finally, must cause the cutting tool load to be even as far as possible, this can affect the cutting tool directly the life.1. The CAM system should have the very high computation programming speedIn the high speed processing uses extremely small entering and cuts the depth for the quantity, its NC procedure must be much bigger than to the traditional numerical control processing procedure, thus requests the software computation speed to have to be quick, by saves the cutting tool path edition and the optimized programming time.2. The entire journey automatically guards against has cut the handling ability and the automatic hilt interference inspection abilityThe high speed processing processes the nearly 10 time of cuttings speeds by the tradition to carry on the processing, once will occur has cut to the engine bed, the product and the cutting tool has the calamity consequence, therefore will request its CAM system to have to have the entire journey automatically to guard against has cut processing the ability and the automatic hilt and the jig interference inspection, circles evades the function. The system can automatically prompt short supports on both sides the cutting tool length, and automatically carries on the cutting tool interference inspection.3. Rich high-speed cutting cutting tool path strategyThe high speed processing to processes the craft to feed the way to have the special request compared to the traditional way, in order to can guarantee the maximum cutting efficiency, also guaranteed when high-speed cutting processes the security, the CAM system ought to be able to act according to processes the instantaneous remainder the size automatically to enter for rate carries on optimized processing, can automatically carry on the cutting tool path edition to optimize, the processing remaining analysis and the treatment processing path monitoring, by guarantees the high speed processing cutting tool stressful condition the stability, enhances the cutting tool the service life.After uses the high speed processing equipment, will be able to increase to programmers' demand, because high speed will process the technological requirement strictly, has cut the protection to be more important, therefore will have to spend the much time to carry on the simulation examination to the NC instruction. In the ordinary circumstances, high speed processes the programming time the to be ordinary than processing programming time to have to be much longer. In order to guarantee the high speed processing equipment enough utilization ratio, must dispose the more CAM personnel. The existing CAM software, like PowerMILL, MasterCAM, UnigraphicsNX, Cimatron and so on have all provided the correlation function high speed milling cutting tool path strategy.中文译文:机械设计及加工工艺机械设计是一门通过设计新产品或者改进老产品,满足人类需求的应用技术科学。
外文原文Options for micro-holemakingAs in the macroscale-machining world, holemaking is one of the most— if not the most—frequently performed operations for micromachining. Many options exist for how those holes are created. Each has its advantages and limitations, depending on the required hole diameter and depth, workpiece material and equipment requirements. This article covers holemaking with through-coolant drills and those without coolant holes, plunge milling, microdrilling using sinker EDMs and laser drilling.Helpful HolesGetting coolant to the drill tip while the tool is cutting helps reduce the amount of heat at the tool/workpiece interface and evacuate chips regardless of hole diameter. Butthrough-coolant capability is especially helpful when deep-hole microdrilling because the tools are delicate and prone to failure when experiencing recutting of chips, chip packing and too much exposure to carbide’s worst enemy—heat.When applying flood coolant, the drill itself blocks access to the cutting action. “Somewhere about 3 to 5 diameters deep, the coolant has trouble getting down to the tip,” said Jeff Davis, vice president of engineering for Harvey Tool Co., Rowley, Mass. “It becomes wise to use a coolant-fed drill at that point.”In addition, flood coolant can cause more harm than good when microholemaking. “The pressure from the flood coolant can sometimes snap fragile drills as they enter the part,” Davis said.The toolmaker offers a line of through-coolant drills with diameters from 0.039" to 0.125" that are able to produce holes up to 12 diameters deep, as well as microdrills without coolant holes from 0.002" to 0.020".Having through-coolant capacity isn’t enough, though. Coolant needs to flow at a rate that enables it to clear the chips out of the hole. Davis recommends, at a minimum, 600 to 800 psi of coolant pressure. “It works much better if you have higher pressure than that,” he added.To prevent those tiny coolant holes from becoming clogged with debris, Davis also recommends a 5μm or finer coolant filter.Another recommendation is to machine a pilot, or guide, hole to prevent the tool from wandering on top of the workpiece and aid in producing a straight hole. When applying a pilot drill, it’s important to select one with an included angle on its point that’s equal t o or larger than the included angle on the through-coolant drill that follows. The pilot drill’sdiameter should also be slightly larger. For example, if the pilot drill has a 120° included angle and a smaller diameter than a through-coolant drill with a 140° included angle, “then you’re catching the coolant-fed drill’s corners and knocking those corners off,” Davis said, which damages the drill.Although not mandatory, pecking is a good practice when microdrilling deep holes. Davis suggests a pecking cycle that is 30 to 50 percent of the diameter per peck depth, depending on the workpiece material. This clears the chips, preventing them from packing in the flute valleys.Lubricious ChillTo further aid chip evacuation, Davis recommends applying an oil-based metalworking fluid instead of a waterbased coolant because oil provides greater lubricity. But if a shop prefers using coolant, the fluid should include EP (extreme pressure) additives to increase lubricity and minimize foaming. “If you’ve got a lot of foam,” Davis noted, “the chips aren’t being pulled out the way they are supposed to be.”He added that another way to enhance a tool’s slipperiness while extending its life is with a coating, such as titanium aluminum nitride. TiAlN has a high hardness and is an effective coating for reducing heat’s impact when drilling difficult-to-machine materials, like stainless steel.David Burton, general manager of Performance Micro Tool, Janesville, Wis., disagrees with the idea of coating microtools on the smalle r end of the spectrum. “Coatings on tools below 0.020" typically have a negative effect on every machining aspect, from the quality of the initial cut to tool life,” he said. That’s because coatings are not thin enough and negatively alter the rake and relief angles when applied to tiny tools.However, work continues on the development of thinner coatings, and Burton indicated that Performance Micro Tool, which produces microendmills and microrouters and resells microdrills, is working on a project with others to create a submicron-thickness coating. “We’re probably 6 months to 1 year from testing it in the market,” Burton said.The microdrills Performance offers are basically circuit-board drills, which are also effective for cutting metal. All the tools are without through-coolant capability. “I had a customer drill a 0.004"-dia. hole in stainless steel, and he was amazed he could do it with a circuit-board drill,” Burton noted, adding that pecking and running at a high spindle speed increase the drill’s effectiveness.The requirements for how fast microtools should rotate depend on the type of CNC machines a shop uses and the tool diameter, with higher speeds needed as the diameter decreases. (Note: The equation for cutting speed is sfm = tool diameter × 0.26 × spindlespeed.)Although relatively low, 5,000 rpm has been used successfully by Burton’s customers. “We recommend that our customers find the highest rpm at the lowest possible vibration—the sweet spot,” he said.In addition to minimizing vibration, a constant and adequate chip load is required to penetrate the workpiece while exerting low cutting forces and to allow the rake to remove the appropriate amount of material. If the drill takes too light of a chip load, the rake face wears quickly, becoming negative, and tool life suffers. This approach is often tempting when drilling with delicate tools.“If the customer decides he wants to baby the tool, he takes a lighter chip load,” Burton said, “and, typically, the cutting edge wears much quicker and creates a radius where the land of that radius is wider than the chip being cut. He ends up using it as a grinding tool, trying to bump material away.” For tools larger than 0.001", Burton considers a chip load under0.0001" to be “babying.” If the drill doesn’t snap, premature wear can result in abysmal tool life.Too much runout can also be destructive, but how much is debatable. Burton pointed out that Performance purposely designed a machine to have 0.0003" TIR to conduct in-house, worst-case milling scenarios, adding that the company is still able to mill a 0.004"-wide slot “day in and day out.”He added: “You would think with 0.0003" runout and a chip load a third that, say,0.0001" to 0.00015", the tool would break immediately because one flute would be taking the entire load and then the back end of the flute would be rubbing.When drilling, he indicated that up to 0.0003" TIR should be acceptable because once the drill is inside the hole, the cutting edges on the end of the drill continue cutting while the noncutting lands on the OD guide the tool in the same direction. Minimizing run out becomes more critical as the depth-to-diameter ratio increases. This is because the flutes are not able to absorb as much deflection as they become more engaged in the workpiece. Ultimately, too much runout causes the tool shank to orbit around the tool’s center while the tool tip is held steady, creating a stress point where the tool will eventually break.Taking a PlungeAlt hough standard microdrills aren’t generally available below 0.002", microendmills that can be used to “plunge” a hole are. “When people want to drill smaller than that, they use our endmills and are pretty successful,” Burton said. However, the holes can’t be very deep because the tools don’t have long aspect, or depth-to-diameter, ratios. Therefore, a 0.001"-dia. endmill might be able to only make a hole up to 0.020" deep whereas a drill of the same sizecan go deeper because it’s designed to place the loa d on its tip when drilling. This transfers the pressure into the shank, which absorbs it.Performance offers endmills as small as 5 microns (0.0002") but isn’t keen on increasing that line’s sales. “When people try to buy them, I very seriously try to tal k them out of it because we don’t like making them,” Burton said. Part of the problem with tools that small is the carbide grains not only need to be submicron in size but the size also needs to be consistent, in part because such a tool is comprised of fe wer grains. “The 5-micron endmill probably has 10 grains holding the core together,” Burton noted.He added that he has seen carbide powder containing 0.2-micron grains, which is about half the size of what’s commercially available, but it also contained grains measuring 0.5 and 0.6 microns. “It just doesn’t help to have small grains if they’re not uniform.”MicrovaporizationElectrical discharge machining using a sinker EDM is another micro-holemaking option. Unlike , which create small holes for threading wire through the workpiece when wire EDMing, EDMs for producing microholes are considerably more sophisticated, accurate and, of course, expensive.For producing deep microholes, a tube is applied as the electrode. For EDMing smaller but shallower holes, a solid electrode wire, or rod, is needed. “We try to use tubes as much as possible,” said Jeff Kiszonas, EDM product manager for Makino Inc., Auburn Hills, Mich. “But at some point, nobody can make a tube below a certain diameter.” He added that some suppliers offer tubes down to 0.003" in diameter for making holes as small as 0.0038". The tube’s flushing hole enables creating a hole with a high depth-to-diameter ratio and helps to evacuate debris from the bottom of the hole during machining.One such s inker EDM for producing holes as small as 0.00044" (11μm) is Makino’s Edge2 sinker EDM with fine-hole option. In Japan, the machine tool builder recently produced eight such holes in 2 minutes and 40 seconds through 0.0010"-thick tungsten carbide at the hole locations. The electrode was a silver-tungsten rod 0.00020" smaller than the hole being produced, to account for spark activity in the gap.When producing holes of that size, the rod, while rotating, is dressed with a charged EDM wire. The fine-hole option includes a W-axis attachment, which holds a die that guides the electrode, as well as a middle guide that prevents the electrode from bending or wobbling as it spins. With the option, the machine is appropriate for drilling hole diameters less than 0.005".Another sinker EDM for micro-holemaking is the Mitsubishi VA10 with a fine-hole jig attachment to chuck and guide the fine wire applied to erode the material. “It’s a standardEDM, but with that attachment fixed to the machine, we can do microhole d rilling,” said Dennis Powderly, sinker EDM product manager for MC Machinery Systems Inc., Wood Dale, Ill. He added that the EDM is also able to create holes down to 0.0004" using a wire that rotates at up to 2,000 rpm.Turn to TungstenEDMing is typically a slow process, and that holds true when it is used for microdrilling. “It’s very slow, and the finer the details, the slower it is,” said , president and owner of Optimation Inc. The Midvale, Utah, company builds Profile 24 Piezo EDMs for micromachining and also performs microEDMing on a contract-machining basis.Optimation produces tungsten electrodes using a reverse-polarity process and machines and ring-laps them to as small as 10μm in diameter with 0.000020" roundness. Applying a10μm-dia. electrode produces a hole about 10.5μm to 11μm in diameter, and blind-holes are possible with the company’s EDM. The workpiece thickness for the smallest holes is up to 0.002", and the thickness can be up to 0.04" for 50μm holes.After working with lasers and then with a former EDM builder to find a better way to produce precise microholes, Jorgensen decided the best approach was DIY. “We literally started with a clean sheet of paper and did all the electronics, all the software and the whole machine from scratch,” he said. Including the software, the machine costs in the neighborhood of $180,000 to $200,000.Much of the company’s contract work, which is provided at a shop rate of $100 per hour, involves microEDMing exotic metals, such as gold and platinum for X-ray apertures, stainless steel for optical applications and tantalum and tungsten for the electron-beam industry. Jorgensen said the process is also appropriate for EDMing partially electrically conductive materials, such as PCD.“The customer normally doesn’t care too much about the cost,” he said. “We’ve done parts where there’s $20,000 [in time and material] involved, and you can put the whole job underneath a fingernail. We do everything under a microscope.”Light CuttingBesides carbide and tungsten, light is an appropriate “tool material” formicro-holemaking. Although most laser drilling is performed in the infrared spectrum, the SuperPulse technology from The Ex One Co., Irwin, Pa., uses a green laser beam, said Randy Gilmore, the company’s director of laser technologies. Unlike the femtosecond variety, Super- Pulse is a nanosecond laser, and its green light operates at the 532-nanometer wavelength. The technology provides laser pulses of 4 to 5 nanoseconds in duration, and those pulses are sent in pairs with a delay of 50 to 100 nanoseconds between individual pulses. The benefits of this approach are twofold. “It greatly enhances material removal compared to other nanosecond lasers,” Gilmore said, “and greatly reduces the amount of thermal damagedon e to the workpiece material” because of the pulses’ short duration.The minimum diameter produced with the SuperPulse laser is 45 microns, but one of the most common applications is for producing 90μm to 110μm holes in diesel injector nozzles made of 1mm-t hick H series steel. Gilmore noted that those holes will need to be in the 50μm to 70μm range as emission standards tighten because smaller holes in injector nozzles atomize diesel fuel better for more efficient burning.In addition, the technology can produce negatively tapered holes, with a smaller entrance than exit diameter, to promote better fuel flow.Another common application is drilling holes in aircraft turbine blades for cooling. Although the turbine material might only be 1.5mm to 2mm thick, Gilmore explained that the holes are drilled at a 25° entry angle so the air, as it comes out of the holes, hugs the airfoil surface and drags the heat away. That means the hole traverses up to 5mm of material. “Temperature is everything in a turbine” he said, “because in an aircraft engine, the hotter you can run the turbine, the better the fuel economy and the more thrust you get.”To further enhance the technology’s competitiveness, Ex One developed apatent-pending material that is injected into a hollow-body component to block the laser beam and prevent back-wall strikes after it creates the needed hole. After laser machining, the end user removes the material without leaving remnants.“One of the bugaboos in getting lasers accepted in the diesel inject or community is that light has a nasty habit of continuing to travel until it meets another object,” Gilmore said. “In a diesel injector nozzle, that damages the interior surface of the opposite wall.”Although the $650,000 to $800,000 price for a Super- Pulse laser is higher than amicro-holemaking EDM, Gilmore noted that laser drilling doesn’t require electrodes. “A laser system is using light to make holes,” he said, “so it doesn’t have a consumable.”Depending on the application, mechanical drilling and plunge milling, EDMing and laser machining all have their place in the expanding micromachining universe. “People want more packed into smaller spaces,” said Makino’s Kiszonas.中文翻译微孔的加工方法正如宏观加工一样,在微观加工中孔的加工也许也是最常用的加工之一。
毕业设计论文外文资料原文及译文学院:机电工程学院专业:机械设计制造及其自动化班级:学号:姓名:Mechanical engineering1.The porfile of mechanical engineeringEngingeering is a branch of mechanical engineerig,it studies mechanical and power generation especially power and movement.2.The history of mechanical engineering18th century later periods,the steam engine invention has provided a main power fountainhead for the industrial revolution,enormously impelled each kind of mechznical biting.Thus,an important branch of a new Engineering – separated from the civil engineering tools and machines on the branch-developed together with Birmingham and the establishment of the Associantion of Mechanical Engineers in 1847 had been officially recognized.The mechanical engineering already mainly used in by trial and error method mechanic application technological development into professional engineer the scientific method of which in the research,the design and the realm of production used .From the most broad perspective,the demend continuously to enhance the efficiencey of mechanical engineers improve the quality ofwork,and asked him to accept the history of the high degree of education and training.Machine operation to stress not only economic but also infrastructure costs to an absolute minimun.3.The field of mechanical engineeringThe commodity machinery development in the develop country,in the high level material life very great degree is decided each kind of which can realize in the mechanical engineering.Mechanical engineers unceasingly will invent the machine next life to produce the commodity,unceasingly will develop the accuracy and the complexity more and more high machine tools produces the machine.The main clues of the mechanical development is:In order to enhance the excellent in quality and reasonable in price produce to increase the precision as well as to reduce the production cost.This three requirements promoted the complex control system development.The most successful machine manufacture is its machine and the control system close fusion,whether such control system is essentially mechanical or electronic.The modernized car engin production transmission line(conveyer belt)is a series of complex productions craft mechanizationvery good example.The people are in the process of development in order to enable further automation of the production machinery ,the use of a computer to store and handle large volumes of data,the data is a multifunctional machine tools necessary for the production of spare parts.One of the objectives is to fully automated production workshop,three rotation,but only one officer per day to operate.The development of production for mechanical machinery must have adequate power supply.Steam engine first provided the heat to generate power using practical methods in the old human,wind and hydropower,an increase of engin .New mechanical engineering industry is one of the challenges faced by the initial increase thermal effciency and power,which is as big steam turbine and the development of joint steam boilers basically achieved.20th century,turbine generators to provide impetus has been sustained and rapid growth,while thermal efficiency is steady growth,and large power plants per kW capital consumption is also declining.Finally,mechanical engineers have nuclear energy.This requires the application of nuclear energy particularly high reliability and security,which requires solving many new rge power plants and the nuclear power plant control systems have become highly complex electroonics,fluid,electricity,water and mechanical parts networks All in all areas related to the mechanical engineers.Small internal combustion engine,both to the type (petrol and diesel machines)or rotary-type(gas turbines and Mong Kerr machine),as well as their broad application in the field of transport should also due to mechanical enginerrs.Throughout the transport,both in the air and space,or in the terrestrial and marine,mechanial engineers created a variety of equipment and power devices to their increasing cooperation with electrical engineers,especially in the development of appropration control systems.Mechanical engineers in the development of military weapons technology and civil war ,needs a similar,though its purpose is to enhance rather than destroy their productivity.However.War needs a lot of resources to make the area of techonlogy,many have a far-reaching development in peacetime efficiency.Jet aircraft and nuclear reactors are well known examples.The Biological engineering,mechanical engineering biotechnology is a relatively new and different areas,it provides for the replacement of the machine or increase thebody functions as well as for medical equipment.Artficial limbs have been developed and have such a strong movement and touch response function of the human body.In the development of artificial organ transplant is rapid,complex cardiac machines and similar equipment to enable increasingly complex surgery,and injuries and ill patients life functions can be sustained.Some enviromental control mechanical engineers through the initial efforts to drainage or irrigation pumping to the land and to mine and ventilation to control the human environment.Modern refrigeration and air-conditioning plant commonaly used reverse heat engine,where the heat from the engine from cold places to more external heat.Many mechanical engineering products,as well as other leading technology development city have side effects on the environment,producing noise,water and air pollution caused,destroyed land and landscape.Improve productivity and diver too fast in the commodity,that the renewable naturalforces keep pace.For mechanical engineers and others,environmental control is rapidly developing area,which includes a possible development and production of small quantities of pollutants machine sequnce,and the development of new equipment and teachnology has been to reduce and eliminate pollution.4.The role of mechanical engineeringThere are four generic mechanical engineers in common to the above all domains function.The 1st function is the understanding and the research mechanical science foundation.It includes the power and movement of the relationship dynamics For example,in the vibration and movement of the relationship;Automatic control;Study of the various forms of heart,energy,power relations between the thermodynamic;Fluidflows; Heat transfer; Lubricant;And material properties.The 2nd function will be conducts the research,the desing and the development,this function in turn attempts to carry on the essential change to satisfy current and the future needs.This not only calls for a clear understanding of mechanical science,and have to breakdown into basic elements of a complex system capacity.But also the need for synthetic and innovative inventions.The 3rd function is produces the product and the power,include plan,operation and maintenance.Its goal lies in the maintenance eitherenhances the enterprise or the organization longer-tern and survivabilaty prestige at the same time,produces the greatest value by the least investments and the consumption.The 4th function is mechanical engineer’s coordinated function,including the management,the consultation,as well as carries on the market marking in certain situation.In all these function,one kind unceasingly to use the science for a long time the method,but is not traditional or the intuition method tendency,this is a mechanical engineering skill aspect which unceasingly grows.These new rationalization means typical names include:The operations research,the engineering economics,the logical law problem analysis(is called PABLA) However,creativity is not rationalization.As in other areas,in mechanical engineering,to take unexpected and important way to bring about a new capacity,still has a personal,marked characteristice.5.The design of mechanical engineeringThe design of mechanical is the design has the mechanical property the thing or the system,such as:the instrument and the measuring appliance in very many situations,the machine design must use the knowledge of discipline the and so on mathematics,materials science and mechanics.Mechanical engineering desgin includeing all mechanical desgin,but it was a study,because it also includes all the branches of mechsnical engineering,such as thermodynamics all hydrodynamics in the basic disciplines needed,in the mechanical engineering design of the initial stude or mechanical design.Design stages.The entire desgin process from start to finish,in the process,a demand that is designed for it and decided to do the start.After a lot of repetition,the final meet this demand by the end of the design procees and the plan.Design considerations.Sometimes in a system is to decide which parts needs intensity parts of geometric shapesand size an important factor in this context that we must consider that the intensity is an important factor in the design.When we use expression design considerations,we design parts that may affect the entire system design features.In the circumstances specified in the design,usually for a series of such functions must be taken into account.Howeever,to correct purposes,we should recognize that,in many cases thedesign of important design considerations are not calculated or test can determine the components or systems.Especially students,wheen in need to make important decisions in the design and conduct of any operation that can not be the case,they are often confused.These are not special,they occur every day,imagine,for example,a medical laboratory in the mechanical design,from marketing perspective,people have high expectations from the strength and relevance of impression.Thick,and heavy parts installed together:to produce a solid impression machines.And sometimes machinery and spare parts from the design style is the point and not the other point of view.Our purpose is to make those you do not be misled to believe that every design decision will needreasonable mathematical methods.Manufacturing refers to the raw meterials into finished products in the enterprise.Create three distinct phases.They are:input,processing exprot.The first phase includes the production of all products in line with market needs essential.First there must be the demand for the product,the necessary materials,while also needs such as energy,time,human knowledge and technology resourcess .Finall,the need for funds to obtain all the other resources. Lose one stage after the second phase of the resources of the processes to be distributed.Processing of raw materials into finished products of these processes.To complete the design,based on the design,and then develop plans.Plan implemented through various production processes.Management of resources and processes to ensure efficiency and productivity.For example,we must carefully manage resources to ensure proper use of funds.Finally,people are talking about the product market was cast.Stage is the final stage of exporting finished or stage.Once finished just purchased,it must be delivered to the users.According to product performance,installation and may have to conduct further debugging in addition,some products,especially those very complex products User training is necessary.6.The processes of materials and maunfacturingHere said engineering materials into two main categories:metals and non-ferrous,high-performance alloys and power metals.Non-metallic futher divided into plastice,synthetic rubber,composite materials and ceramics.It said the productionproccess is divided into several major process,includingshape,forging,casting/ founding,heat treatment,fixed/connections ,measurement/ quality control and materal cutting.These processes can be further divide into each other’s craft.Various stages of the development of the manufacturing industry Over the years,the manufacturing process has four distinct stages of development, despite the overlap.These stages are:The first phase is artisanal,the second Phase is mechanization.The third phase is automation the forth Phase is integrated.When mankind initial processing of raw materials into finished products will be,they use manual processes.Each with their hands and what are the tools manuslly produced.This is totally integrated production take shape.A person needs indentification,collection materials,the design of a product to meet that demand,the production of such products and use it.From beginning to end,everything is focused on doing the work of the human ter in the industrial revolution introduced mechanized production process,people began to use machines to complete the work accomplished previously manual. This led to the specialization.Specialization in turn reduce the manufacture of integrated factors.In this stage of development,manufacturing workers can see their production as a whole represent a specific piece of the part of the production process.One can not say that their work is how to cope with the entire production process,or how they were loaded onto a production of parts finished.Development of manufacting processes is the next phase of the selection process automation.This is a computer-controlled machinery and processes.At this stage,automation island began to emerge in the workshop lane.Each island represents a clear production process or a group of processes.Although these automated isolated island within the island did raise the productivity of indivdual processes,but the overall productivity are often not change.This is because the island is not caught in other automated production process middle,but not synchronous with them .The ultimate result is the efficient working fast parked through automated processes,but is part of the stagnation in wages down,causing bottlenecks.To better understand this problem,you can imagine the traffic in the peak driving a red light from the red Service Department to the next scene. Occasionally you will find a lot less cars,more than being slow-moving vehicles,but the results can be found by thenext red light Brance.In short you real effect was to accelerate the speed of a red Department obstruction offset.If you and other drivers can change your speed and red light simultaneously.Will advance faster.Then,all cars will be consistent,sommth operation,the final everyone forward faster.In the workshop where the demand for stable synchronization of streamlined production,and promoted integration of manufacturing development.This is a still evolving technology.Fully integrated in the circumstances,is a computer-controllrd machinery and processing.integrated is completed through computer.For example in the preceding paragraph simulation problems,the computer will allow all road vehicles compatible with the change in red.So that everyone can steady traffic.Scientific analysis of movement,timing and mechanics of the disciplines is that it is composed of two pater:statics and dynamics.Statics analyzed static system that is in the system,the time is not taken into account,research and analysis over time and dynamics of the system change.Dynameics from the two componets.Euler in 1775 will be the first time two different branches: Rigid body movement studies can conveniently divided into two parts:geometric and mechanics.The first part is without taking into account the reasons for the downward movement study rigid body from a designated location to another point of the movement,and must use the formula to reflect the actual,the formula would determine the rigid body every point position. Therefore,this study only on the geometry and,more specifically,on the entities from excision.Obviously,the first part of the school and was part of a mechanical separation from the principles of dynamics to study movement,which is more than the two parts together into a lot easier.Dynamics of the two parts are subsequently divided into two separate disciplines,kinematic and dynamics,a study of movement and the movement strength.Therefore,the primary issue is the design of mechanical systems understand its kinematic.Kinematic studies movement,rather than a study of its impact.In a more precise kinematic studies position,displacement,rotation, speed,velocity and acceleration of disciplines,for esample,or planets orbiting research campaing is a paradigm.In the above quotation content should be pay attention that the content of the Euler dynamics into kinematic and rigid body dynamics is based on the assumptionthat they are based on research.In this very important basis to allow for the treatment of two separate disciplines.For soft body,soft body shape and even their own soft objects in the campaign depends on the role of power in their possession.In such cases,should also study the power and movement,and therefore to a large extent the analysis of the increased complexity.Fortunately, despite the real machine parts may be involved are more or less the design of machines,usually with heavy material designed to bend down to the lowest parts.Therefore,when the kinematic analysis of the performance of machines,it is often assumed that bend is negligible,spare parts are hard,but when the load is known,in the end analysis engine,re-engineering parts to confirm this assnmption.机械工程1.机械工程简介机械工程是工程学的一个分支,它研究机械和动力的产,尤其是力和动力。
Mechanical Design and Manufacturing ProcessesMechanical design is the application of science and technology todevise new or improved products for the purpose of satisfying humanneeds. It is a vast field of engineering technology which not onlyconcerns itself with the original conception of the product in terms ofits size, shape and construction details, but also considers the variousfactors involved in the manufacture, marketing and use of the product.People who perform the various functions of mechanical design aretypically called designers, or design engineers. Mechanical design isbasically a creative activity. However, in addition to being innovative,a design engineer must also have a solid background in the areas ofmechanical drawing, kinematics, dynamics, materialsengineering, strength ofmaterials the purpose of mechanical design is toserve a need for man. Inventions, knowledge by themselves do not necessarily incorporated into a designed productwill a benefit be derived. It should berecognized, therefore, that a human need must be identified before aparticular product is designed.Mechanical design should be considered to be an opportunity to useinnovative talents to envision a design of a product, to analyze thesystem and then make sound judgments on how the product is to bemanufactured. It is important to understand the fundamentals ofengineering rather than memorize mere facts and equations. There are no facts or equations which alone can be used toprovid all the correct decisions required to produce a good design.On the other hand, any calculations made must be done with theutmost 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英文原文 附录 and manufacturing processes.As stated previously, discoveries andscientific benefit produce a product which willcertain amount of risk, knowing that if 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 manufac-turing. 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 is 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. 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 mankindsimply because the originators were unable or unwilling to explain theiraccomplishments to others. Presentation is a selling job. The engineer,when presenting a new solution to administrative, management, orsupervisory persons, is attempting to sell or to prove to them that thissolution is a better one. Unless this can be done successfully, the timeand effort spent on obtaining the solution have been largely wasted.Basically, there are only three means of communication available tous. These are the written, the oral, and the graphical forms. Thereforethe successful engineer will be technically competent andversatile in all three forms of communication. A technicallycompetent person who lacks ability in any one of these forms is(1) Does the design really serve a human need?(2) Will it be competitive with existing products of rivalcompanies?(3) Is it economical to produce?(4) Can it be readily maintained?(5) Will it sell and makea profit?Only time will provide the true answers to the preceding questions,but the product should be designed, manufactured and marketed only withinitial affirmative answers. The design engineer also must communicatethe finalized design to manufacturing through the use of detail andassembly drawings.Quite often, a problem will occur during the manufacturingcycle[3]. It may be that a change is required in the dimensioning ortolerancing of a part so that it can be more readily produced. This failsin the category of engineering changes which must be approved by the severely handicapped.If ability in all three forms islacking, no one will ever know how competent thatperson The competent of not succeeding should be expectedengineer should not in a presentation. because failure or is! be afraid In fact, criticis of thepossibility seems to accompanyevery really creative idea. There is a great deal to belearned from a failure,and risk defeat.deciding not effectively, the greatest gains are obtained by those willing to In the final analysis, the real failure would lie in to makethe presentation at all.the following questions must be answered:To communicatedesign 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.Designing starts with a need,real or imagined.Existing apparatus may need improvements in durability, efficiently, weight, speed, or cost. New apparatus may be needed to perform a function previously done by men, such as computation, assembly, or servicing. With the objective wholly or partly defined, the next step in design is the conception of mechanisms and their arrangements that will perform the needed functions.For this, freehand sketching is of great value, not only as arecord of one's thoughts and as an aid in discussion with others, but particularly for communication with one's own mind, as a stimulant for creative ideas.When the general shape and a few dimensions of the several components become apparent, 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 east. Optimum proportions and dimensions will be sought for each critically loaded section,together with a balance between the strength 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 statics for reaction forces and for the optimum utilization of friction; of dynamics for inertia, acceleration, and energy;ofelasticity and strength of materials for stress and deflection; andof fluid mechanics for lubrication and hydrodynamic drives.Finally, a design based upon function and reliability will be completed, and a prototype may be built. If its tests are satisfactory, and if the device is to be produced in quantity, theinitial design will undergo certain modifications that enable it to bemanufactured in quantity at a lower cost. During subsequent years ofmanufacture and service, the design is likely to undergo changes as newideas are conceived or as further analysis based upon tests andexperience indicate alterations. Sales appeal, customer satisfaction, andmanufacture cost are all related to design, and ability in design isintimately involved in the success of an engineering venture.To stimulate creative thought, the following rules are suggestedfor the designer.1. Apply ingenuity to utilize desired physical properties and tocontrol undesired ones.The performance requirements of a machine are met by utilizing laws of nature or properties of matter (e. g., flexibility, strength,gravity,inertia,buoyancy,centrifugal for, principles of the lever andinclined plane, friction, viscosity, fluid pressure, and thermal expansion), also the many electrical, optical, thermal, and chemical phenomena.However, what may be useful in one application may be detrimentalin the next. Flexibility is desired in valve springs but not in the valvecamshaft; friction is desired at the clutch face but not in the clutchbearing. Ingenuity in design should be applied to utilize and control thephysical properties that are desired and to minimize those that are notdesired.2. Provide for favorable stress distribute minimum weight. On components subjected particular attention is given to a reduction in stress and to an increase ofstrength at fillets, threads, holes, and fits.modification in shape, and strengtheningmay be done by prestressing treatments such as surface rolling andshallow hardening. Hollow shafts and tubing, and box sections give afavorable stress distribution, together with stiffnessand minimum weight. Sufficient stiffness to maintain alignment and uniformpressure between contacting surfaces should be provided for crank, cam,and gear shafts, and for enclosures and frames containing bearingsupports. The stiffness of shafts and other components mustand stiffness withto fluctuating stress,concentration, Stress reduction are made bybe suitable to avoid resonant vibrations.3. Use &zsic equations to calculate and optimize dimensions.Thefundamental equations of mechanics and the other sciences are the accepted bases for calculations.They are sometimes rearrangedin special forms to facilitate thedetermination or optimization o f dimensions, such as thebeam and surface stress equations for determining gear-tooth size.Factors may be added to a fundamental equation for conditions notanalytically determinable, e. g. , on thin steel tubes, an allowancefor corrosion added to the thickness based on pressure. When it isnecessary to apply a fundamental equation to shapes, materials, orconditions which only approximate the assumptions for its derivation, itis done in a manner which gives results "on the safe side". In situationswhere data are incomplete,equations of the sciences may be used as proportioning guides to extend a satisfactory design to newcapacities.4.Choo se materials for a combination of properties. Materials should be chosen for a combination of pertinent properties, not only for strengths,hardness, and weight, but sometimes for resistanceto impact, corrosion, and low or high temperatures. Cost and fabrication such as weld ability, machine ability, in heat-treating temperatures, and required coating.between stock and integral components.previously developed components is frequently selected and his company from the stocks of parts manufacturers,if the component meet the performance and reliability requirements and isadaptable without additional development costs to the particular machinebeing designed.However, its selection should be carefully made wi'th afull knowledge of its propcrties, since the reputation and liability ofthe company suffer if there is a failure in any one of the machine'sparts. In other eases the strength, reliability, and cost requirementsare better met if the designer of the machine also designs the component,with the particular advantage of compactness if it is designs integralwith other components, e. g., gears to be forged in clusters or integralwith a shaft.6. Provide for accurate location and non interference of parts in properties are factors,sensitivity to variation4. Select carefully by a designerassembly. A good design provides for the correct locating of parts andfor easy assembly and repair. Shoulders and pilot surfaces give accurate location without measurement during assembly. Shapes can be designed so that parts cannot be assembled backwards or in the wrong place. Interferences, as between screws in tapped holes, and between linkages must he foreseen and pretended. Inaccurate alignment and positioning between such assemblies must be avoided, or provision must be made to minimize any resulting detrimental displacements and stresses.The human race has distinguished itself from all other forms oflife by using tools and intelligence to create items that serve to make life easier and more enjoyable. Through the centuries, both the tools and the energy sources to power these tools have evolved to meet the increasing sophistication and complexity of mankind's ideas.In their earliest forms, tools primarily consisted of stone instruments. Considering tile relative simplicity of the items being made and the materials being shaped, stone was adequate. When iron tools were invented, durable metals and more sophisticated articles could be produced. The twentieth century has seen the creation of products made from the most durable and, consequently, the most unmachinable materials in history. In an effort to meet the manufacturing challenges created by these materials, tools have now evolved to include materials such asalloy steel, carbide, diamond, and ceramics.A similar evolution has taken place with the methods used to power our tools. Initially, tools were powered by muscles; either human or animal. However as the powers of water, wind, steam, and electricity were harnessed, mankind was able to further extendedmanufacturing capabilities with new machines, greater accuracy, and faster machining rates.Every time new tools, tool materials, and power sources areutilized, the efficiency and capabilities of manufacturers are greatly enhanced. However as old problems are solved, new problemsand challenges arise so that the manufacturers of today are faced with tough questions such as the following: How do you drill a 2 mmdiameter hole 670 mm deep without experiencing taper or runout? Is there a way to efficiently deburr passageways inside complex castings andguarantee 100 % that no burrs were missed? Is there a welding process that can eliminate the thermal damage now occurring to my product?Since the 1940s, a revolution in manufacturing has been takingplace that once again allows manufacturers to meet the demands imposed by increasingly sophisticated designs and durable, but in many cases nearly unmachinable, materials. This manufacturing revolution is now, as it has been in the past, centered on the use of new tools and new forms ofenergy.The result has been the introduction of new manufacturing processes used for material removal, forming, and joining, known today as nontraditional manufacturing processes.The conventional manufacturing processes in use today for materialremoval primarily rely on electric motors and hard tool materials toperform tasks such as sawing, drilling, an broaching. Conventionalforming operations are performed with the energy fromelectric motors, hydraulics, and gravity. burning gases and electric arcs.In contrast, nontraditional energy sources consideredunconventional by yesterday's standards. Material removal can now beaccomplished with electrochemical reactions, high-temperature plasmas, and high-velocity jets of liquids and abrasives. Materials that in the past have been extremelydifficult to form, are nowelectrons.processes have been invented and successfullyLikewise, material joining is conventionally a ccomplished with thermal energy sources such as manufacturing processes harnessformed with magnetic fields, explosives, and the shock waves from powerful electric sparks. Material-joining capabilities have been expanded with the use of high-frequency sound waves and beams of In the past 50 years, over 20 different nontraditionalmanufacturingimplemented into production. The reason there are such a large number of nontraditional processes is the same reason there are such a large number of conventional processes; eachprocess has its own characteristic attributes and limitations, hence no one process is best for all manufacturing situations. For example, nontraditional process are sometimes applied toincrease productivity either by reducing the number of overall manufacturing operations required to produce a product or by performing operations faster than the previously used method.increasing repeatability, reducing in-process breakage of fragile work pieces, or by minimizing detrimental effects on work piece properties.Because of the aforementioned attributes,some of these processes, and there is no reason to believe that this trend will not continue into the future.2. Approximately one half of the nontraditional manufacturingprocesses are available with computer control of the processparameters. The use of computers lends simplicity to processes that implementation.adaptively-controlled through the use of vision systems, laser gages, and other in-process inspection techniques. If, for example, the in-process inspection system determines that the size of holes beingproduced in a product are becoming smaller, the size can be modified without changing hard tools, such as drills.4.The implementation of nontraditional manufacturing processeswill continus to increase as manufacturing engineers, productIn other cases, nontraditional processes are used to reduce the number of rejects experienced by the old manufacturing method by nontraditional manufacturing processes have experienced steady growth since their introduction. An increasing growth rate for these processes in the future is assured for the following reasons:1. Currently, nontraditional processes possess virtuallyunlimited capabilities when compared with conventional processes, except for volumetric material removal rates. Great advances havebeen made in the past few years in increasing the removal rates of people may be unfamiliar with, and thereby accelerates acceptance. Additionally, computer control assures reliability andrepeatability[s], which also accelerates acceptance and1.Most nontraditional processes are capableof beingdesigners, and metallurgical engineers become increasingly aware of the unique capabilties and benefits that nontraditional manufacturing processes provide.译文机械设计及加工工艺机械设计是一门通过设计新产品或者改进老产品,满足人类需求的应用技术科学。