机械毕业设计外文翻译-切割参数对芯片影响形成垂直切割论文.doc

毕业论文（设计）外文翻译题 目： 切割参数对芯片的影响形成垂直切割 切屑的形成机制总所周知，所有的材料在相同的切削条件下并不表现出相同的情形，这是因为不同的材料在经过不同的热处理后有着不同的硬度。事实上，对于范围的切削条件（即切削速度，Vc的变化从50到250米/分钟，并且进给速度中，f变化从0.05至0.2毫米/转），X160CrMoV12钢经过热处理（淬火）的加工与材料经历了退火处理的表明的形式和芯片的形态是完全不同的对于范围的切削条件（即切削速度，Vc的变化从50到250米/分钟，并且进给速度中，f变化从0.05至0.2毫米/转），为显示在图3和4根据加工条件（图3）滑带形成可以很容易观察到。对切屑形成的分析表明，“工具单片”的接触是以防所施加的负荷增加的负载和形成严重变形区域。当电势负载达到一阈值时，裂纹萌生在那里与切割速度的方向形成一个角度0，在基质中相当量的碳化铬的区域很容易出现。这条裂缝出现在工具最先出现放松的地方，裂纹萌生会产生滑落的问题，在哪里易产生段（片）切屑。这种现象是通过给一个新的段再次重复。并且相应地，经过一个循环切屑形成锯齿型。在宏观尺度然而，通过硬车削得到的切屑，根据切割速度（图4）变化他们的形式不同，他们可以根据切割速度（图4）变化。这些形式螺旋状发达，纠缠不清或者在已分离的形式或以连续弧的蓝色和灰色的颜色的形式存在。在这里，正交切割期间切屑形态受切削速度，进给速度，以及切割深度的影响。然而，对硬切削的切屑形态进行更详细的研究，应开展有助于揭示分割切屑形成的机制，表明硬切削是一种实用的专业知识。Secondary carbidePrimary carbide 图1.微观结构AISI D2与化学分析用EDS分析得到硬化状态a)b)c)图2.(a）试样的形式 （B）正交切割 (c）在所述材料的基质中的碳化物的工具创建凹槽损图3.一）芯片形成在VC =100m m/min，F= 0.05，mm /min，AP =2mm;二）切屑形成，在VC= 250m /min，F= 0.2mm /min，AP=2mm图。4.低倍观察的切屑; AP= 2毫米; F =0.1毫米/转; （1） VC =50m /min; （二）VC =150m /min （三）VC =250m /min连续波状切屑（F= 0.02毫米/转）锯齿片（F= 0.1毫米/转）图5.芯片形态以变化的进给速度中进料对切削的影响对切屑的分析表明，进料速率在一定程度上反过来又影响切的形态。当然，钢的“X160铬MoV12”加工硬化（62 HRC）与小进料速率（F= 0.02毫米/转）允许获得一个连续的芯片，该切屑是由于准稳态塑性变形在剪切的区域（图5）。应当指出的是，随着进料速率增加在Vc=100m /分钟的恒定切削速度下，该切屑的锯齿形态愈发明显。 这意味着，由于循环开裂产生非常密集的剪切，将要产生更多的锯齿状切屑切割速度对切屑形式的影响随着切割速度的增加，剪切带变得越来越激烈带有相当大的减少的段到片段（图6）之间的接触的宽度这是归因于在主剪切带局部变形的现象,随着温度的增加更重要。材料的力学性能从而降低切削区塑性变形,减少阻力导致突然的剪切切屑通过创建一个塑料的不稳定。应该注意,加料速度的0.1毫米/转速切屑的出现频率往往是随着切削速度风险较高。白层的研究事实上,这种形态往往是发生在下加工的硬钢和低的热导率。低导热系数和能量耗散产生剪切区域作为绝热剪切的剪切带。这些芯片是由一个本地化的变形和灾难性的剪切,由于材料的硬度和脆性增加。因此系列芯片的机理是基于裂纹的产生。白层的显微结构的换向机构的马氏体结构。一层厚的白色表示严重的热损伤。这个白层的形成是因为由于集中机械和热能量的存在局部很快在一个严格的区域造成冶金转换和自然给了白色区域的SEM照片,图7所示。 定期白层形成在困难时加工表面切削速度高、磨损的工具或工具在加工使用导热系数较低。总体思路提出了文学对减少白层的形成,降低其厚度是它应该使用适当的冷却,工具材料导热系数高,和进给速率的降低,切削速度,刀尖半径的工具,工具侧面磨损等。详细研究芯片形成的机制会导致切削现象的理解和加工零件的表面质量的控制。 4. Study of white layer 在摘要中,芯片的显微分析表明,它们通常在波浪的形状和锯齿波类型有白色层变厚度取决于使用的切割速度总是保持同样的进给速率,f,图8中所示。然而,随着切削速度的增加,白层的厚度增加略低于本研究的实验条件。 众所周知,这部分经历了严重塑性变形。白层的形成本质上是由于密集的热源(即开始时非常高的热梯度)领域的局部切削难加工。4. Study of white layer众说周知这一部分经历了严重的塑性变形 白层的形成本质上是由于密集的热源(即开始时非常高的热梯度)领域的局部切削难加工。 显然,对芯片的热量转移是更重要的比工件。图8 b显示硬度的芯片结构的演变取决于切削速度给定提要的速度f = 0.1毫米/转速。这些结果的平均值从五为每个切割速度测量。根据这些结果,建议有一个几乎全部解散由于高温产生的碳化物塑性变形在非常高的切削速度。矩阵中的更多的碳的数量增加,融化钢的减少。此外,当工具使每个切削阶段后,材料发生了不正常的冷却通过其微观结构条件。大量的奥氏体无法找到足够的时间在高切削速度和转换大量的新鲜的马氏体或保持奥氏体中发现的结构不仅在白层,而且组织内的芯片。至于白色和暗层,进行了大量的实验调查文献以了解白色和黑色层的形成机制和属性在许多材料去除过程,如车削、铰孔、磨削和电火花加工(16 - 20)。准这些论文进行了非常相似的白层的评价结果。白色层而言,三种不同的理论解释白层形成的机制从文学出现了:我)快速加热和淬火,导致突然的相变,2)严重的塑性变形,并产生一种同质微结构表面非常细粒度III)与环境的反应,如在渗氮过程。然而,一些作者指出,似乎暗层形成的热影响区显微结构的变化结果的快速加热和淬火。图7(a,b)。扫描电镜观察白色层芯片的一部分 X160CrMoV1 (Vc = 110 m/min, f = 0.1 mm/rev, ap = 2 mm)切削力的分析事实上,这个工作代表最初试图解释白层的形成。我们这里确认定义和相当大的白层的厚度发生在加工。然而,我们没有发现这里一个暗层在实验条件下形成。曾表示,形成白色和暗层不仅取决于热处理由于操作参数(切削力、切削速度等)。同样的材料参数和一些其他重要的冶金方面,如晶粒尺寸、晶粒伸长等。削减部队由测力的表记录表明,切向力英尺和提要Fa降低切削速度时,风险投资增加(图9),主要是由于“工具和芯片”之间的摩擦。这里,切削力,英国金融时报增加根据进给速率对于一个给定的切削速度Vc(图9)。而且,提要力量,足总对切向切削力的实力相对较弱,英国金融时报。削减部队应该被认为是最重要的加工过程中工艺参数。从本质上讲,削减军队的绝对条件评估芯片形成和冶金方面也形成总伤害的工具和工件。它们影响了变形的工件加工,其尺寸精度和芯片形成总系统的恒常性。更清楚,切削力的主要因素之一,应该在金属切削操作;事实上,削减部队在与材料的力学性能在芯片的过程中形成。由于切向力是主导的垂直切割硬质材料,统计研究的实验条件下进行了现在论文根据统计方法称为“方差分析”,这样你可以知道切削参数对结果的影响这里获得。测试两个因素的加工进行了切割速度Vc、进给速率,f两个层次;风险投资= 50和250米/分钟,f = 0.05和0.2毫米/转速。通过保持恒定的深度削减为美联社= 2毫米,所有的测试已经进行,每个测试被重复使用的平均值的3倍(表3)。和总平均的计算效果,矩阵的构造和计算的方块总数,广场错误(SStotal SSerror)能给我们构建方差分析表和= f和B =风投如表4所示。考虑在目前给出的实验结果工作,文献提出了一个有趣的工作,他们的结果是同意的本研究17。的确定特定切削力来理解在线程芯片发生干涉。与累积增加径向饲料,相应的特定的切削力变得更高。他们表明,特定的切削力的差异结果的改变干扰流动的芯片。特定的切削力减少线程的开始,然后随累积径向饲料。结果表明,芯片流的干扰影响线程力组件在很大程度上(17 - 18)。图8)进化的白层“TWL”和(b)芯片结构的硬度取决于给定的进给速率的切割速度f = 0.1毫米/转速(硬度的矩阵:62)费舍尔表方差分析和测试表明,在5%的显著水平,计算值,Ftcalculated,一,B高于理论值,Fttheoretical。然而,对AB、计算值FtAB-calculated低比理论,FtAB-theoretical。可以得出结论,切削速度和进给速率的影响大大降低力,但他们的交互没有太多对切削力的影响。为参数,英国金融时报是高于B,AB和非常高,一个比我更重要。影响和交互上的切削条件切削力在图10中以图形方式呈现。一可以看出,切削力变形材料可塑性虽然是强制性是依赖于特定的因素。正如我们前一节中提到的,切削力化学成分非常敏感,硬度、微观结构、使用的刀具类型、机器稳定性、热生成和操作参数。31。切向力的数学模型的确定是由实验设计的方法。一个通用的这个模型的方程是:通过对数计算X的值转换曲线的值选择的因素(Vc、f)根据方程(2),bi系数的方程所有必需的计算后，一个简单的切向力的数学模型,提出了在这里作为一个函数的切割速度方程7。验证的数学模型方程(7)如图11所示。根据模型(7),参数方法图(进给速率/切削速度)(图11b)可以绘制这将是一个象征车削加工参数的选择困难。事实上,这个参数图让我们知道提要轮流的价值对于一个给定的切削速度和一个给定的切削力;通过修复两个参数并提供曲线上的点选择第三个。这个参数方法图将其用于工作在钢铁制造商X160 CrMoV12收到或淬火条件。Mechanism of the chip formation3.1 Morphology of the chipMorphology of the chip As well known, all the materials do not show the same behaviour under the same cutting conditions. That is also true for the same material with various hardness that have undergone tothe different heat treatment 4. In fact, Machining of X160CrMoV12 steel undergone to the heat treatment (quench) shows that the form and the morphology of chip are completely different from that of obtained when the material has undergone to the annealing treatment 3,4,8 for the range of cutting conditions (i.e. cutting speed, Vc varies from 50 to 250 m/min, and feed rate, f varies from 0.05 to 0.2 mm/rev) as shown in the Figures 3 and 4.Slip band formation can be easily observed depending on the machining conditions (Figure 3).The analysis of the chips formation shows that the contact of “tool-chip” in case of increased loading and a heavily deformed zone are formed following the applied load.When the potential loading achieves a threshold value, a crack initiation appears easily in the zone where a considerable amount of chromium carbide is found in the matrix by forming an angle 0 with the direction of the cutting speed. This crack appears at the point of the tool leading a short relaxation. The crack initiation will produce the slip of the matter where the formation of a segment (slice). This phenomenon is repeated again by giving a new segment. And accordingly, the chip is formed in saw-tooth type since the process is cyclic.In macroscale however, the chips obtained by hard turning, are relatively in different forms and they can change according to the cutting speed (Figure 4). These forms are developed helicoidally, tangled up either in detached form or in the form of continuous arc in the colour of blue and gray.Here typical chip morphology was identified to realize theeffect of cutting speed, feed rate, and depth of cut, etc. during the orthogonal cutting. However, more detailed research on the chip morphology in hard machining should be carried out to help reveal the segmentation chip formation mechanisms as well as encourage hard machining to be a practical expertise.Secondary carbidePrimary carbide Fig. 1. Microstructure as hardened state of AISI D2 & chemical analysis obtained by EDS analysisa)b)c)Fig. 2. a) Specimen form, (b) orthogonal cutting, and c) the carbides in the matrix of the materials create grooves by wear on the toolFig. 3. a) Chip formation at Vc=100 m/min, f =0.05 mm/rev, ap=2mm; b) Chip formation at Vc=250 m/min, f =0.2 mm/rev, ap=2mmFig. 4. Macrographic observation of the chip; ap = 2 mm; f = 0.1mm/rev; (a) Vc = 50 m/min; (b) Vc = 150 m/min; (c) Vc = 250 m/mindifferent forms and they can change according to the cutting speed (Figure 4). These forms are developed helicoidally, tangled up either in detached form or in the form of continuous arc in the colour of blue and gray.Here typical chip morphology was identified to realize theInfluence of the feed on the form of chip The analysis of the chips shows that the feed rate by turn influences considerably the morphology of the chips. Certainly, the machining of steel “X160 Cr MoV12” hardened (62 HRC) with small feed rates (f = 0.02 mm/rev) allows obtaining a continuous chip, this chip is due to a quasi-stationary plastic deformations in the zones of shearing (Figure 5).It should be noted that, with the increase in the feed rate and at a constant cutting speed of Vc = 100 m/min, the chip isincreasingly scalloped. It means that it takes more and more the shape of the saw-tooth chip due to cyclic cracking by creating very intensive shear bands.Infuence of the cutting speed on the formWith increase of the cutting speed, the shearing bands become more and more intense with a considerable reduction in the width of contact between the segments up to fragment (Figure 6).This is attributed to the phenomenon of localized deformation in the primary shear zone that becomes more important with the increase in the temperature.The mechanical properties of material thus decrease in the cutting zone by reducing resistance to the plastic deformation andthus cause an abrupt shearing of the chip by creating a plastic instability. It should be noted that for a feed rate of 0.1mm/rev, the appearance frequency of the chips is more often as the cutting speed Vc is higher.In fact, this morphology is often observed in the case of the machining of hard steels and of low thermal conductivity. The low thermal conductivity and the rapid dissipation of energy lead to consider the shear zone as an area of adiabatic shear. These chips are formed by a localization of deformation and catastrophic shear, thanks to the increase in hardness and brittleness of material. Thus the mechanism of generation of chip is based on the initiation of a crack followed by a slip.The white layer is the result of the microstructural changement in the martensitic structure. A thicker white layer indicates a severe thermal damage. The formation of this white layer occurs because due the presence of concentrated mechanical and thermal energies localised very fast in a strict zone causing the metallurgical transformation and naturally gives the white area as shown in the SEM picture of Figure 7. White layer is regularly formed in hard machined surfaces when a high cutting speed, a worn tool, or a tool with low thermal conductivity is used during machining. General idea proposed in literature for decreasing the formation of white layer and decrease its thickness is that it should be used appropriate cooling, tool material with high thermal conductivity, and the reductions of feed rate, cutting speed, tool nose radius, tool flank wear, etc. A detail study of the mechanisms of chip formation can lead to the comprehension of cutting phenomenon and the control of the surface integrity of the machined parts. In the present paper, the micrographic analysis of the chips showed that they are generally in the shapes of wavy and saw-tooth types having white layers in variable thickness depending on the cutting speed used by always keeping the same feed rate, f, as indicated in the Figure 8a. However, as the cutting speed increases, the thickness of the white layer increases slightly under the experimental conditions of this study. As known well, this part has undergone a heavily plastic deformation. The formation of the white layer is essentially due to an intensive heat sources (i.e. very high thermal gradient at the beginning) localised in the field of cutting during the hard machining. In literature, Surfacecooling rate in hard turning is given at the order of 104-105 C/s and machined surface encounters an extremely short cyclethermo-mechanical process with very high heating rate 106 C/s8. Obviously, the quantity of the heat transferred towards the chip is more important than that of the workpiece.Figure 8b indicates the evolution of the hardness of the chip structure depending on the cutting speed for a given feed rate off = 0.1 mm/rev. These results are the mean values taken from the five measurements for each cutting speed. According to theseresults obtained here, it is suggested that there is a nearly total dissolution of carbides due to the high temperature generated byplastic deformation at very high cutting speeds. The more the amount of carbon in the matrix increases, the more the meltingpoint of the steel decreases. Additionally, when the tool leaves after each cutting stage, the material undergoes abnormal coolingconditions through its microstructure. Large amount of austenite cannot find enough time to transform at high cutting speeds and a considerable amount of fresh martensite or remained austenite arefound in the structure not only in white layer but also within the microstructure of the chip.As for white and dark layers, a large number of experimental investigations have been carried out in the literature in order to understand the formation mechanisms and properties of white and dark layers in many material removal processes, such as turning, reaming, grinding and electrical discharge machining 16-20. Quasi these papers were carried out very similar results the evaluation of white layer. As far as the white layer is concerned, three different theories explaining the mechanism of white layer formation have emerged from the literature: I) rapid heating and quenching, which results in sudden phase transformation, II) severe plastic deformation, which produces a homogenous microstructure with a very fine grain size III) surface reaction with the environment, such as in nitriding processes 20-29.However, some of the authors have indicated that the dark layer formation seems to be a result of microstructural changes in the heat-affected zone as a consequence of the rapid heating and quenchingFig. 7 (a, b). SEM observation of white layer of a part of the chip obtained from steel X160CrMoV1, (Vc = 110 m/min, f = 0.1 mm/rev, ap = 2 mm)In fact, this work represents an initial attempt to explain the white layer formation. We confirmed here that very defined and considerable thickness of the white layer occurs during the hard machining.However, we did not detect here a dark layer formation under the experimental conditions. As formerly indicated, the formationof the white and dark layers depends on not only heat treatmentdue to the operational parameters (cutting force, cutting speed, etc.) but also the materials parameters and some other important metallurgical aspects, such as the grain size, grain elongation, etc.Analyse of cutting forcesThe cutting forces recorded by the dynamometric table shows that the tangential force Ft and the feed force Fa decrease when the cutting speed Vc increases (Figure 9) that is due to mainly to the reduction in friction between “tool & chip”. Here, the cutting force, Ft increases depending on the feed rate for a given cutting speed Vc (Figure 9). And also, the feed force, Fa is relatively weak with regard to the tangential cutting force, Ft.Cutting forces should be considered as the most importanttechnological parameters in machining processes. Essentially, cutting forces are the absolute conditions to evaluate the chip formation and metallurgical aspects and also formation of the total damage on the tool and work pieces. They influence the deformation of the workpiece machined, its dimensional accuracy and chip formation constancy of the total system. More clearly, the cutting force is one of the principal factors that should be known in the metal cutting operations; indeed, cutting forces are in relation with the mechanical properties of the material in the process of chip formation. Since tangential force is dominant in the orthogonal cutting of the hard materials, a statistical study has been carried out under the experimental conditions of the present paper according to the statistical method called “ANOVA” so that one can know the effect of the cutting parameters on the results obtained here. The tests of machining have been carried out for two factors, cutting speed Vc, and feed rate, f on two levels; Vc = 50 and 250 m/min and f = 0.05 and 0.2 mm/rev.By keeping constant the depth of cut as ap=2mm, all of the tests have been carried out and each test has been repeated 3 times for using as the mean value (Table 3).The calculation of the average and total effects, the construction of the matrix and calculation of the squares totals, squares errors (SStotal, SSerror) can give us to build ANOVA table with A= f and B = Vc as indicated in Table 4. Considering the experimental results given in the present work, an interesting work was presented in the literature that their results are agree with those of the present study 17-20. The specific cutting forces are determined in order to understand the interference of chips that occur during the threading. With the increase in the cumulative radial feed, the corresponding specific cutting forces become higher. They indicated that the difference in the specific cutting forces results from the alteration of the interference of the flowing chips. The specific cutting forces decrease in the beginning of the threading and then increases with the cumulative radial feed. The results show that the interference of the chip flow influences the threading force components to a very large extent Table ANOVA and the test of Fisher show that on a significant level of 5%, the calculated value, Ftcalculated, for A, B are higher than the theoretical value, Fttheoretical.However, for AB, the calculated value, FtAB-calculated, is lower than the theoretical, FtAB-theoretical. It can be concluded that the cutting speed and the feed rate influence considerably the cutting force, but