【机械类毕业论文中英文对照文献翻译】硬车削加工------以车代磨
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机械类毕业论文中英文对照文献翻译
机械类
毕业论文
中英文
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文献
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车削
加工
车代磨
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【机械类毕业论文中英文对照文献翻译】硬车削加工------以车代磨,机械类毕业论文中英文对照文献翻译,机械类,毕业论文,中英文,对照,文献,翻译,车削,加工,车代磨
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硬车削加工以车代磨作者：克里斯 库帊弗当在车床或车削加工中心加工硬度大于45的工件时，我们把这种车削定义为硬车削加工。由于这种车削能获得.的表面粗擦度，硬车削加工通常被认为是磨削的一种替代工艺，或是磨削加工的预加工。硬车削加工通常是在工件热处理后获得45-68HRC硬度后来进行的。硬车削加工制定工序的原则与传统软车削有很多相似之处。和任何一种新工艺一样，硬车削有它自己的特点，但最基本的原则仍然是我们在车间中进行普通车削时所遵循的原则。这种工艺自产生之初就有了比磨削更多的优势，在磨削加工中往往需要专业的理论知识和丰富的实践经验，并且不是所有加工工人都能否掌握，尽管任何一种加工方法都够为机加工人员学习，但更多工人和工艺员更容易掌握硬切削的方法。正确应用尽管硬车削能达到令人满意的效果，但它不能取代磨削加工，通过磨削完成的镜面抛光，粗糙度可达0.3-0.8，而这在硬车削加工中是不可能达到的。和硬车削相比，磨削尤其特有的优势，比如可以获得更高维度的表面粗擦度和圆柱度。另外由于在一种卡盘装夹下便可完成加工，硬车削和其他工艺相比能使工件获得较高的圆柱度和同轴度。硬车削加工工艺在零件表面平面度要求为0.5-12um，粗糙度要求在0.8-7um时能收到良好的效果，硬车削的工艺范围很广，诸如齿轮，柱塞泵零件，液压元器件，轴承座表面，硬盘驱动轴等。硬车削工艺和磨削相比，生产成本低。最明显的成本优势是支撑部件成本的降低，正像CNC车削中心一般来说要比磨床价格低。另外一般能在车削加工中心中心加工的零件往往需要数台不同类型的磨床才能完成同样的操作，其成本优势更加显著。如上所述，一台车削加工中心使用一个卡盘能完成内空车削，外圆车削，锥面车削，车槽等。除了有利于提高平面度，直线度和同轴度外，还很大程度上减少了装夹和循环操作的次数。高精密螺纹车削同样可以完成，与手工加工螺纹相比有很好的同轴度。硬车削还可以作为圆弧面和自由曲面的精加工，而磨削加工需要定制的砂轮，这种加工方法很耗时，并且专用磨床很昂贵。除了这种能够合并各种加工的天然优势，硬车削加工的循环时间远比具有相同加工能力的普通车削短。在硬车削加工中，金属能很快被车削，如果使用立方氮化硼和陶瓷刀具还能完成高速车削。另外，硬车削加工工件装夹和拆卸时间短，车削加工中心还更容易完成自动化以提高生产效率。除了成本低，硬车削加工还有很多减少对环境的影响的特点。车削加工中心相比磨削耗能较少。硬车削通常在干燥环境下加工，减少了润滑成本和对润滑系统的布置。硬车削加工更容易循环利用切屑，。而磨削中的切屑分离成本很高或直接作为工业废料处理。合理的车床由于表面粗糙度和精度是硬车削加工的基本要求，不是所有的车床和车削加工中都能很好的完成硬车削加工，除了满足刀具的切削速度要求外，用于硬车削的机床必须具备良好的抵抗热变形的能力，刚度和硬度。正确使用刀具硬车削的一个关键效益是在任何硬车削加工中都可以使用的嵌入式硬质刀具，和成本较低的砂轮相比，这些刀具价格昂贵，但是尽管刀具价格昂贵，我们还是会选择硬切削加工，因为加工时间和转换时间的大大减少会弥补刀具的成本。CBN和PCBN是加工硬度大于55HRC的零件的理想材料，CBN是最硬的材料之一，其硬度仅次于天然钻石。并且CBN这种材料的加工工艺较好，在和金刚石材料类似的加工条件下有很好的综合性能。并且CBN刀具在高温下仍有很好的稳定性。CBN也可以制成PCBN，PCBN是CBN粒子烧结而成具有高硬度高热稳定性的表面粗糙的集成物。陶瓷工具割削工具是非常地较不昂贵的比较 CBN 和 PCBN，以及提供一个优良的表面光制由于他们的能力维持一个锐利刃口。他们典型地提供在 CBN 和 PCBN 上的可提高的轫性，让他们变成更好在这 45-55 HRC 范围中为硬旋转材料适合了。然而，类似 CBN 和 PCBN，他们是易碎的而且不很好地为打断的伤口适合，不光滑或半的意思铸件清理。由于这些材料及优良的耐磨性，CBN和刀具比碳质刀具具有很大的持久性。然而，这些材料很脆，因此除了切削量很小的精加工外，这些刀具不适于其他的操作。相比和陶瓷刀具的价格要低很多，并且由于能保持切削刃的锋利使陶瓷刀具很适合于做精加工操作。陶瓷刀具比和刀具有更强的韧性，使这种刀具更适合的硬切削加工。但是和，一样，陶瓷刀具很脆，不适合非连续型加工，粗加工或半精加工。在个别加工操作中，刀具的形状和表面涂料以及嵌入式陶瓷刀具的刀头可以根据不同情况加以选择，不管选择什么样的刀具，都必须有高精度和刚度的刀架，使合模销的长度最小以减小振动，提高局部精度，延长刀具寿命。即使这些刀具能提供的表面粗糙度，车痕仍会留在工件表面，不利于加工有油封要求的表面，加工刀痕会导致油的泄露，或者由于工件表面的突起使做旋转运动的工件卡死。为了更好地完成车削精加工，薄膜类型的磨削单元可以用来作为精加工以达到表面粗糙度为0.8的镜面。薄膜型磨削单元用于塔伦驱动的车削加工中心。通过使用多种抛光薄膜来磨掉表面的突起以达到传统磨削加工类似的表面精度。硬车削加工的效益尽管硬车削加工不能替代所有的磨削加工，这种加工方法由于能够减少装夹时间和循环操作时间以及设备的低成本具有很大的经济性。由于他和传统车削加工遵循很多相同原则，硬车削加工由于能很容易应用于加工车间而具有很多而外的效益。如果选择了正确的加工方法，正确的机床，正确的刀具，硬车削加工能够加强由于很宽的公差范围而带来的收益。附录二 外文文献Hard Turning as an Alternative to GrindingChris Koepfer Hard turning is typically defined as the turning of a part or barstock of harder than 45HRC on a lathe or turning center. Since surface roughness of Rmax/Rz=1.6s can be achieved, hard turning is often considered a replacement for grinding operations or as a pre-grinding process. Hard turning is most often performed on post-heat treated parts with surface hardness ranging from 45HRC to 68HRC or even higher. The process of hard turning shares many fundamentals with its “soft turning” sibling. As with any new application, there is a learning curve for hard turning, but the fundamental principles follow those of the same turning operations that are commonly performed in shops today. This gives it an inherent advantage over grinding, which requires specific knowledge and experience that not all machinists possess. While any new process can be learned, most machinists and programmers today will have an easier time absorbing the hard turning process compared with grinding. The Right Application While hard turning can achieve impressive results, it is not an alternative for all parts typically finished through grinding. Polished mirror surface finishes of Rz=0.30.8z that can be achieved through grinding are not possible by hard turning alone. Grinding has the additional advantage of being able to achieve higher dimensional roundness and cylindricity accuracies compared with hard turning. However, since parts can typically be finished in a single chucking, hard turned parts often show superior concentricity and perpendicularity characteristics to their ground counterparts. The “sweet spot” for hard turning applications are for parts that have roundness accuracy requirements between 0.5 and 12 microns, and surface roughness requirements between Rz 0.8 micron and Rz 7.0 microns (see chart on page 26). This includes a variety of parts such as gears, injection pump components, hydraulic components, seat surfaces, and hard disk drive shafts. The cost advantages of hard turning compared with grinding are numerous. The immediately apparent cost advantage is the reduced cost in capital equipment, as CNC turning centers are generally less expensive than grinding machines. Additionally, several types of grinding machines may be needed to perform the operations able to be performed on a single turning center, further opening the possibilities for equipment cost savings. As mentioned above, a turning center can complete ID turning, OD turning, taper turning, and grooving in a single chucking. In addition to improving the accuracy of squareness, concentricity and straightness, this drastically reduces cycle and setup times as well. High precision threading operations can also be performed, guaranteeing concentricity with other part features compared with offline threading operations. Hard turning also allows for the finishing of radius and free-curved surfaces. Grinding processes require a custom-dressed wheel, which is time consuming to produce, or highly customized grinding machines that can be expensive. In addition to the inherent cost advantages of combining multiple operations into one, hard turning cycle times are drastically shorter than comparable turning operations. Metal can be removed much faster in hard turning operations, and high speed turning is possible with both CBN and ceramic cutting tools. Changing grinding wheels is also time consuming, whereas switching out inserts on turning centers can be quick. Part loading and unloading times are also shorter for turning centers, and turning centers are typically more easily automated for additional productivity. A number of features of the hard turning process reduce environmental impact as well as cost. Turning centers consume less electricity than grinding machines, reducing both electrical consumption and the monthly electrical bill. Hard turning is often performed dry, eliminating both coolant costs and the need for coolant disposal. Hard turning produces easily recycled chips, whereas grinding produces sludge that must go through a costly separation process or be disposed of as industrial waste. The Right MachineAs accuracy and surface finish are fundamental requirements for hard turned parts, not all lathes and turning centers are ideally suited for hard turning applications. In addition to being able to meet the speed requirements of the cutting tools, machines used for hard turning must maintain thermal stability, rigidity and precision over time. The Right ToolingOne of the key benefits of hard turning is that off the shelf inserts can be used for virtually any hard turning operation. However, the CBN, PCBN and ceramic inserts can be expensive, especially when compared with the relatively low costs of grinding wheels. But dont let the high cost of inserts scare you off from the hard turning process, as the high tooling costs are quickly offset by reductions in processing time and change-over time. CBN and PCBN are ideal cutting tool materials for the hard finishing of parts above 55HRC. CBN is one of the hardest materials, second only to diamond. It is a manufactured material, synthesized under conditions similar to those used for synthetic diamond. However, unlike diamond cutting tools, CBN demonstrates increased stability at higher temperatures. CBN is also used to manufacture PCBN, a composite formed by sintering CBN particles into a hard, tough and thermally stable material. Thanks to their incredible wear resistance, CBN and PCBN cutting tools outlast carbide by a large factor in hard turning applications. However, they are extremely brittle, and therefore, not well suited for anything other than finishing operations with smaller depths of cut. Ceramic cutting tools are considerably less expensive than CBN and PCBN, and also provide an excellent surface finish thanks to their ability to maintain a sharp cutting edge. They typically offer enhanced toughness over CBN and PCBN, making them better suited for hard turning materials in the 45-55 HRC range. However, similar to CBN and PCBN, they are brittle and not well suited for interrupted cuts, roughing or semi-finishing. Geometries and coatings on CBN, PCBN and ceramic inserts can be selected for optimal performance in individual applications. No matter what cutting tool is chosen, an accurate and rigid toolholder is also essential to the process. Maintain a minimal projection length to minimize vibration, enhance part finish and maximize cutting tool life. Even though these cutting tools can provide surface finishes of Rmax/Rz=1.6s, feed turning marks (similar to the peaks and valleys of threading) remain on the surface. This may be an issue for parts such as oil seal contact surfaces, where the valleys may cause oil to leak, or bearing rolling surfaces where the peaks may cause th
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