先进制造技术-中英文翻译

1、外文资料翻译附 件：1、外文原文；2、外文资料翻译译文。主轴是最容易被忽视的一个重要组件之一，主轴必须能够提供较好的灵活性，在较低的 主轴转速的情况下提供较大的扭转力，在一定的主轴转速的范围内使功率最大化。一个合理 的主轴转速的范围是从100RPM到20000RPM范围内或者更高，这取决于主轴的应用程度。 在主轴结构中的混合陶瓷轴承能够增加主轴的刚度，精确度和温度稳定性。图3. 14的数据 说明一个五轴铳床是专为硬切削设计的，这与高速加工有着相似的要求。切削工具是硬铳削成功工作的一个主要因素。对于粗加工的硬化材料，有至少四个凹槽 的端铳刀值得推荐。当以较高的进给速度切削时，它们能够提供负载芯片

2、。刀具的槽长应该较短，还应该有一个接近30度的螺旋角。经验证，一个30度的螺旋角 有利于切屑瘤的产生和切削热的扩散。除此之外，还应该考虑到硬质合金基体。只能使用超细晶体尺寸的硬质合金，大约0.5 微米到0. 6微米。这些工具能够增加边缘的强度并且减少积屑瘤。当铳削硬化的模槽时，应该考虑到有嵌入物的刀具。硬质合金刀片比固体硬质合金端铳 刀要廉价，而且插入刀片后，会延长刀具的使用寿命。然而，这些刀具并不是为高转速主轴 而设计的，如果操作不当，也会有重大的平安风险。硬铳削从高温到磨粒磨损都给切削工具施加了很大的压力，为了承受这些压力，必须要 使用涂层刀具。涂层给刀具增加了一个保护层，这样能够增加工具

3、的使用寿命。涂层的选择应该以其独有的属性为基础。钛基涂层，例如TiCN和TiALN,对于硬铳削 来说是很常见的。耐磨性和高硬度是TiCN最重要的特性，TiALN的耐热性和抗氧化性更强 些。工具制造商可以通过提供特制的多层共混物来进一步增加涂层。在硬铳削中不会经常使用冷却液体。硬铳削会产生大量热能，但是当冷却液接触到外表 时会蒸发。使用涂层同样能够导致刀具的热不稳定性。在切削过程中压缩空气能够代替芯片，除此之外，油雾组合的产品同样是精选出来的。 润滑油能够减少摩擦，因此润滑油能够增加工具的使用寿命和外表抛光度。. CAD/CAM的分析CAD/CAM系统是另一个重要的组成局部，该系统在近年来取得了

4、显著的进步，现在更是 增加了一系列先进的特性和功能。然而并不是所有的系统都能够与之比较，这些系统不能为 硬铳削创立刀具轨迹。尽管CAD/CAM系统不是专门为硬铳削设计的，但是对于硬铳削来说，许多拥有高速加工 能力的系统有同样的功能，因为这两者之间是有一定联系的。这确保了工具持续的用一个一 成不变的切削力进行切割，这是维持理想状态的条件之一。在刀具轨迹应用之前，这局部的完整分析必须完成，不是所有的局部都适用于硬铳削, 加工的特定领域应该清楚的标明，这决定了最小的内半径和最长的工作深度。通常来说，一 个4:1的长径比的工具不会造成任何问题。当长径比增大时，问题就会出现，当长径比过大时，硬磨的经验在

5、决定它有多成功方面 发挥了关键作用。而采用小直径刀具的硬铳削是可行的，只要小心地保持恒定的切屑负荷和 机器以最低的DOCs运行。如果CAD/CAM系统没有直接验证或者模拟数控代码的工具，市场上有很多可以进行这类 操作的软件包可以采用。最后，适当的诀窍对于成功的硬铳削是至关重要的。如果不懂处理程序的知识，那么所 有的必须局部都是没有用的。成功的硬铳削的依据有专业技巧，先进的高速切削HSM知识， 切割工具的合理选择，合模装置以及使用CAD/CAM系统加工能力。对所有的组件有一个清晰的了解，这能使工作人员认识到，对于成功的硬铳削，什么 是必需的。.精密加工精密加工是使用切削工具的过程，无论是车削，硬

6、铳削，磨削，这会形成一个精密的尺 寸，形状和外表光洁度。精密加工必须保证在10微米以下。任何导致不准确的操作通常被 称为传统的机械加工。相比于传统材料的标准加工，成功的精密硬质材料加工对参数更加敏 感。例如：机床精度，刚度，刀架设计，刀具材料，几何图形，夹具，冷却液的介绍，加工 工艺等。1、外文原文（复印件）114114114Advanced Manufacturing Technology114limitations on acceptable feed rates-determined by the ability of the cutting tool to withstand incr

7、eased cutting loads without fracture.Increasing radial cutting depths also could increase removal rates, although cutting depth is often determined by the amount of stock removal required. As in the case of increased feed rates, tool life decreased with increased depth of cut. As expected, a tradeof

8、f exists between tool life and removal rate.s：s： tangentialforce, generated by the part rotation; radial force, generated by the resistance of the workpiece material to depth of cut； and, lastly, longitudinal force, generated by the feed rate applied. These forces are 30% to 80% greater than in “sof

9、t machiningprocesses. For example, when comparing preheat-treated to heat-treated steel with ahardness of 62 HRC, the longitudinal force increases from 30% to 50% , Thetangential force increases 30% to 40%, and the radial force increases from 70% to 100% , Therefore, the machine tool must be able to

10、 handle the increased cutting forces, especially in the radial direction.Cutting coolant can influence the generation of white layer. Because white layer is thought to occur as the result of a phase transformation on the surface, cutting coolant might help eliminate thermal damage by keeping the wor

11、kpiece surface cool. Some reports say cutting coolant eliminates white layer, but other studies show coolant having no effect. Tool condition is also believed to be an important factor, with new tools producing undamaged surfaces, while white layer increases with increasing tool wear.If hard turning

12、 is to replace finish grinding operations, it must be capable of producing surface finishes comparable to those generated by grinding. Unlike grinding, where surface finish is detennined by the size, shape, hardness, and distribution of abrasive grains in the grinding wheel, hard-turned surfaces are

13、 nominally defined by the geometry of the cutting process, primarily by the cutting toofs feed rate and nose radius.For grinding cylindrical applications, both the wheel and the workpiece must rotate. Moreover, the wheel rotates rapidly while the workpiece rotates slowly. If the rotating members are

14、 imperfectly concentric, the combination of imperfections and nnational speed differential produces lobing. A geometric out-of-round patlem on the workpiece is produced, which can affect the end-product performance. With hard turning, on the other hand, either the workpiece or cutting tool is rotate

15、d, not both.Chapter 3Modem Manufacturing Technologyrrherefbre, the machined surface will be as accurate as the machine tool spindle and the longitudinal direction of the machine tool relative to the center line of the machine.Another disadvantage with grinding is the generation of tremendous surface

16、 heat at the point of contact between the grinding wheel and the workpiece. Even when flood coolant is properly applied, workpiece surface stress risers and heat checks can occur, which can lead to premature failure of the ground part in service. With hard turning, less heat is generated, and if pro

17、perly applied* the heat that is generated will be carried away with the brittle material removed. Thus, the finished parts arc produced without stress risers or heat checks.Another major advantage of HPM is that conventional turning machines can be used with workpieces as hard as 65 HRC using commer

18、cially available ceramic inserts. Savings occur in two areas, processing and capital investment. In processing, the machining, setup, and tool changing time are significantly reduced. Grinding wheel changing, on the other hand, is time-consuming. Guards must be removed, along with the spindle lockin

19、g nuts, the wom wheel must be changed, and the new wheel balanced and dressed. Wheel changing can take as much as 100 times longer than changing ceramic inserts, which require only simple indexing or replacement in the holder.Equipment also is less expensive. A turning machine costs significantly le

20、ss than a production grinder to do comparable work. As already mentioned, setup is easier and quicker. Turning machines also are simpler in construction-there are no reciprocating slides to wear, maintain, or replace-for easier maintenance. However, the strength and rigidity of every component in th

21、e machine must be adequate to handle the additional cutting forces.3.7.2 Hard MillingOne machining advancement that has taken hold over the past few years is hard milling. Typically mold and die makers perform hard milling to cut P-20, H-13 and other tool steels.These materials range in hardness fro

22、m 45 to 64 HRC and are traditionally electrical discharge machined. But new technologies make hard milling a viable alternative. Successful hard milling requires several components to come together- the machine tool, toolholders, cutting tools, CAD/CAM system and process Mknowhow .”Advanced ManuKtur

23、ing TechnologyMachine FactoreThe machine tool is the most significant component. The most fundamental aspect of the machine tool is that it must be designed for hard milling and have the same characteristics found in a high-speed machining center. The machines base construction and individual compon

24、ents, such as the drive train, spindle and CMC, must be capable of handling the demands of hard milling.The base construction must be extremely rigid and have a high degree of damping abilities. These characteristics are found in machine tools with bases constructed from polymer concrete. These mach

25、ines typically have six to 10 times the damping characteristics of machines with cast iron bases. Additionally9 polymer concrete has excellent mechanical and thermal characteristics.The machine tools drive train should incorporate digital drive technology fbr optimal acceleration and deceleration. T

26、his technology allows the CNC to perform a high degree of contouring accuracy and gives it excellent dynamics capabilities.One of the most overlooked components is the spindle. The spindle must be able to provide a great deal of flexibility, offering high torque at low spindle speeds and maximum pow

27、er fbr a large range of spindle speeds. An ideal spindles speed ranges from 100 rpm to 20, 000 rpm or higher, depending on the application. Hybrid ceramic bearings in the construction of the spindle increase spindle stiffness, accuracy and temperature stability. Figure 3.14 shows a 5-axis milling ma

28、chine designed for hard milling, which has a similar requirements as high-speed machining.Figure 3.14 Mikrons HSM 5.axis machine.II7117Chapcer 3Modem Manufacturing Technology7117One of the main contributors to successful hard milling is the cutting tool. For roughing hardened materials, end mills wi

29、th four or more flutes arc recommended. These provide small chip loads while having the capability to cut at higher feed rates.The cutting tools should be short with short flute lengths and have a helix angle of approximately 30. A 30 helix has proven to be optimal for chip flow and dispersal of hea

30、t.The carbide substrate should also be considered. Only cavbide tools with fine or ultra-tine grain sizes, about 0.5 pm to0.6 pm , should be used. These tools provide increased edge strength and reduce built-up edge.For milling larger hardened cavities and cores, cutting tools with inserts should be

31、 considered. Carbide inserts are less expensive than solid*carbide end-milk, and by indexing the insert, tool life can be extended. However, these tools are typically not designed for high spindle speeds. Tliere is also a significant safety risk if improperly handled.Hard milling puts a great amount

32、 of stress on the cutting tool from high heat and abrasive wear. To help overcome these stresses, coated cutting tools must be used. Coatings offer a protective layer on the tool, substantially increasing tool life.Coating selection should be made based on individual properties. Titanium-based coati

33、ngs, such as TiCN and TiAlN, are the most common for hard milling. The wear resistance, or its lianlness, is the most important property of TiCN, while TiAlN resists heat and oxidation better. The toolmaker may further enhance its coatings by offering unique multilayer blends.Flood coolant is not co

34、mmonly used in hanl milling. Hard milling often generates tremendous amount of heat, which is transferred into the chips and causes the coolant to vaporize as it hits the hot chips. The use of coolant can also create thermal instability with the cutting tool.Compressed air is used to help displace c

35、hips during cutting. Additionally, a combination of oil and mist is often selected. Oil helps reduce friction, thereby increasing tool life and improving surface finish. When using oil and mist, an extraction unit should be integrated into the machine tool to help remove the oil from the air.CAD/CAM

36、 AnalysisThe CAD/CAM system is another important component. CAD/CAM systems have greatly advanced over the years, and now provide a variety of advanced featuresAdvanced Manufacturing Technologyand capabilities. However, not al) systems are created equal and there are still many that do not have the

37、capabilities to create tool paths fbr hard milling.Although no CAD/CAM system is designed exclusively for hard milling, many of the systems that offer HSMing capabilities have the same strategies fbr hard milling because the two are related. When hard milling, strategies that keep the cutting tool i

38、n motion should be used. This ensures the tool is continuously cutting with a constant chip load, which is one of the more desirable conditions to maintain when hard milling.Before tool paths can be applied, a complete analysis of the part must be performed. Not all parts are suitable fbr hard milli

39、ng. The specific areas to be machined should be clearly identified, determining the smallest internal radius and largest working depth. A tool with a 4： 1 length-to-diameter ratio commonly does not pose any problems.Problems arise when the ratio grows. When ratios are excessive, hard milling experie

40、nce plays an important role in determining how successful one is. Hard milling with small diameter cutting tools are possible as long as care is taken to maintain a constant chip load and machine at minimal DOCs.If a CAD/CAM system does not have the tools to vaify or simulate the NC code directly, t

41、here are numerous software packages on the market that can.Finally, proper know-how is vital to successful hard milling. AU of the necessary components are of no use without knowledge of the processing procediues. Successful hard milling is based on specific know-how, advanced knowledge HSMing, prop

42、er choice of cutting tools and clamping systemst and using a HSM- capable CAD/CAM system.A clear understanding of all the components provides better awareness of what is needed to be successful at hard milling.Precision MachiningPrecision machining is any process using a cutting tool, whether turnin

43、g, milling, or grinding, which forms a precise dimension, form, and finish of surface. The accuracy held must be 10or less. Any operation resulting in less accuracy is generally considered conventional machining.Compared to standard machining of traditional materials (steel, Al), successful precisio

44、n machining of hard materials is more sensitive to parameters such as machine tool accuracy, stiffness, toolholder design, cutting tool material and geometry,Chapter 3Modem Manufactunng Technologyfixturing, coolant presentation, and machining technique.The properties that make hard materials attract

45、ive for commercial use also make them extremely difficult to machine to the tolerances required by advanced applications.Obtaining tighter tolerances on hard materials is a challenge that must be met if manufacturers are to achieve the improved performance； it*s also where the future of manufacturin

46、g lies.A major factor that influences the production of close-tolerance parts from hard materials is the machine tool itself and its parameters, including inherent repeatability, accuracy, stiffness, and the smoothness or uniformity of travel, spindle speed, thermal stability, machine protection, co

47、ntrol capabilitiest etc.Virtually any machine tool can produce some close-tolerance parts if the feed rate is reduced and the cutting tool changed frequently. To successfully produce precision components to meet market demands, however, the machining operation must be cost-effective, as well as accu

48、rate and repeatable.A key design factor in machine tools is the rigidity or stiffness of the cutting tool to the workpiece. Obviously, components and subassemblies must also have high stiffness. Machine stiffness is a major contributing factor to overall machine accuracy and performance. Stiffness i

49、s measured by the deflection of an element of the machine when its subjected to a load.Machine accuracy is another critical design parameter. To have the confidence to cut high-precision parts on a production basis, its necessary that the user know the 3-D accuracy of the machine tool.The same crite

50、ria apply to toolholders. They too must provide precision, rigidity, and repeatability to produce close-tolerance parts, and to do so they must be kinematically correct.Cutting tools are another element that produce a major effect on the production of precision parts from hard materials. Parameters

51、to be considered are： material, design, fabrication, tolerance, cost, and availability.Tool life is an economic issue that must be considered when machining precision parts from hard materials. While it may perform well, a tool that you must change after every 100 mm of cut length is nu an economical solution to machining these materials. Tool life depends upon the material to be machined and the proce