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附录1英文原文英文原文COST STUDY OF HIGH-SPEED CUTTING UNDER DRY AND WET CONDITIONSFOR MACHINING PROCESSES OPTIMIZATION1. IntroductionThe aim of this study is to optimize the machining processes by investigating the relationship between the high speed machining (HSM) and the tool life for the cutting conditions under testing. Furthermore, studying the effect of cutting fluid on the selected wear criterion, and relationship between different wear criteria and machining cost for the cutting inserts under HSM.This investigation showed that wear rate is proportional to cutting speed supported with similar observations 12,18,19. Studying the correlation between high wear rates at high cutting speed and machining costs, provides better understanding on the performance of this policy and the benefit of its adoption. Currently, little or no data have been published relating the life -cycle costs, tool performance, work piece surface roughness and work piece dimensional accuracy when using solid and indexable cutters 10. However, studies have found that tool costs in metal cutting machines are a third of the cost of producing parts. Therefore reducing product cost is the first objective of a tool management system16. The benefits of adopting this research guideline will help determine the optimal machining cost and tool replacement policy based on different wear criterion values. Additionally this study provides insight in process control and helps the managers in the early process planning steps to associate factors such as preventive maintenance, levels of inventory, and machining cost.2. Experimental StudyThe study developed a guideline of choosing the right cutting tool, cutting speed, and selecting the appropriate wear criteria of the cutting tool inserts for the work material under study. In this study variable wear criteria ranging from 0.lmm to 0.6mm (tool life limit) were taken into consideration. This experiment was conducted in accordance with the International Standard Organization ISO 3685 1993 46.The test was done on a (Clausing1300) variable spindle speed machine with a maximum power of 7.5Hp (see Figure 3-1). The tool wear measurements were performed using an optical microscope with a magnification of up to 300 times, and a Scanning Electron Microscope (SEM). The rotational speed of the work piece was measured before every cut by a (HT-5100) handheld digital Tachometer to insure that the work piece was accurately running at the exact cutting speed. On the other hand, the work piece material was replaced when the length/diameter ratio reaches 10, based on ISO 3685 1993 46, to ensure work piece stability and safety. Two precut were carried out with 1.2 mm depth, to clean up the thin layer of rust, and to ensure work piece straightness.Figure 1 The tuning machine used during the test2.1 Workpiece and Cutting InsertsIn this study, hot rolled ASTM 4140 steel was selected as the workpiece material. The work piece properties are listed as follows:Description: Hot rolled alloy steel bars, SAE 4140H (UNS H4140)Dimensions: 15 cm Diameter x 62.25 cm lengthHeat Treatment: Vacuum degassed/processed, Cal-Al treated, annealed and special straightened, conforming to ASTM A322 and A304Chemical compositions:The composition of the work piece material is listed in Table 3.1 according to the ASTM standards. The experiment was carried out in accordance with the international standard organization ISO3685-93 46, the experiment was stopped and the work piece was changed when the length /diameter ratio reached 10 to meet the requirements of ISO3685 46. The hardness of each bar was checked across the diameter, and the average hardness measurement was 29HRC. The types of tested cutting tool inserts are listed on Table 3.1 according to the ISO designation. Three types of cutting inserts were used in the experiment as illustrated in Table 3-2; and the coating properties are also listed in Table3-3. The configuration of the investigated three cutting inserts was the same as listed in Table 3.4. The general cutting insert assembled geometry is shown in Figure3-2. The inserts were mounted rigidly on a tool holder are depicted in Figure3-3 with an ISO designation of SVJBR 2525 M16.Table 1 Chemical composition of ASTM4140 steel used in the testCutting insertsISO DesignationSubstrateGradeCompanyUncoatedcementedCarbideVBMT 160408.KC 313KennametalTiAlNVBMT 160408KC313KC5010KennametalTiN-TiCN-TiNVBMT 160408KC313KC732KennametalTable 2 Types of the tested cutting insertsCarbonManganesePhosphorusSulfurSiliconNickelChromium0.40.910.0170.020.240.101.01Tin0.008Aluminum0.030Vanadium0.002Calcium0.0064Molly0.2Copper0.12Table3 Coatings propertiesCoatingThicknessNumber of layersTiALN3.5 1TiN-TiCN-TiN3 -3 t-1 t3(TiCN intermediate)2.2 Coolant PropertiesIt is a common belief that coolant emulsion helps in reducing wear rate and cutting temperature. The coolant used in the test was water based emulsion has commercial nameNovick. It is mixed with water at a concentration of 10%. The coolant composition includes the listed chemicals in Table 5. Previous researchers on the better coolant stream directions made different suggestions. Taylor 17 indicated that to reduce tool wear the cutting fluid is to be directed at the back of the chip (direction A). Pigott and Colwell 47 found that by using high stream jet of coolant aimed in direction B it was able to reduce tool wear. Smart and Trent 48 investigated the direction of coolant in reducing the tool wear and found that the most effective direction between all other suggested options was direction B. Therefore, coolant was applied in direction B as listed in Figure 3.4 from a nozzle with diameter of 1.3 cm and a flow rate of 7.1 liters/minute. However, the current study showed that this is not necessarily true in all cases as coolant extends the tool life. It was found that coolant emulsion helped reduce tool life by activating certain wear mechanism at high speed machining (HSM). Detailed explanations of this type of coolant effect will be discussed in Chapter 5. Further more, a brief summary and explanation of types and usage of coolant will be covered in Chapter 5.Table 4 Assembled cutting tool geometryTool geometryDimensionNose radius0.8 (mm)Bake rake angle0 End relief angle5End cutting-edge angle52Side cutting-edge angle30Side rake angle0Side relief angle5Table5 Coolant chemical compositionsSulfate20-30%Aromatic alcohol3-5%Propylene glycol ether3-5%Petroleum oil30-35%Nonionic surfactant3-5%Chlorinated alkene polymer20-30%Angular toolDesignationBack rake0Side rake 0End relief5 Side relief5 End cutting edge 52Side cutting edge 3Nose radius 0.88mmNose radius Cutting Back rake angleSide rake angleFigure 2 Assembled tool geometryFigure 3 Photogradph of the cutting insert fixed on the tool holderA BFigure 4 coolant stream direction3 Cutting ConditionsBased on I803685 46 five cutting speeds were used throughout the testing as listed on Table 6. Cutting speeds corresponding to 410 m/min for the coated carbide tools and180 m/min for the uncoated carbide tools were approximately the upper limit of the application range. Since any further increment resulted in very short cutting tool life or premature tool damage soon after the test was started.The turning experiments were carried out under dry and wet cutting conditions at different cutting speeds, while fixing both feed rate at 0.14 mm/rev and depth of cut at(1mm). Five cutting speeds were selected for the three types of cutting inserts, as listed in Table3-6.4 Experimental Procedure of Tool Life Testing A Clausing 1300 lathe with maximum 7.5HP was used f alloy steel SAE4140H work piece, and the turning process was carried out in the way or the turning of the Hot rolled previously described. A Tachometer was used to measure the rotational speed before each single cut occurred on the work piece in order to ensure that the cutting was performed at the exact speed.An optical microscope was used to measure the flank wear of the cutting inserts. The experiment was terminated if either of the two following conditions occurred1- The maximum flank wear 0.7 mm and/or;2- The average flank wear 0.6 mm.Preliminary experiments were carried out in order to determine the wear limit. It was found that the cutting inserts were worn out regularly on the flank side. Therfore, VBnax =0.7 mm, is chosen to be the wear limit for the tool life. The flank wear was observed and measured at various cutting intervals throughout the experiments. Figure (5) shows flank wear as a function of cutting time for the cemented carbide (KC313) under dry and wet conditions, and includes only three cutting speeds for clarity.Figure 6 presents the flank wear as a function of cutting time for sandwich coated inserts ( KC732) under dry and wet conditions. Figure 7 shows the flank wear as a function of cutting time for TiALN coated cutting inserts (KC5010). Previous figures included three cutting speeds. Clarity of cutting speed curves are presented at the attached appendix for both conditions of machining. The aforementioned figures, present the effect of coolant emulsion in extending the tool life for the KC313, and KC732 cutting inserts; especially after 3 minutes for KC313, and after 7 minutes for KC732 of cutting. However, the usage of coolant emulsion on KC5010 showed negative influence.Figure 5, and Figure 6 show that at any set of turning conditions, the flank wear increased at a higher rate at dry cutting during the gradual wear stage. Figure 7 shows that at any set of turning conditions, the flmk wear increased at a higher rate at wet cutting during the gradual wear stage. The explanation of this material behavior will be covered in detail though-out chapter 5 (wear mechanisms of (KC5010) under wet condition). After gradual wear stage the curves look parallel to each other. This shows that flank wear occurs at the same rate under dry and wet cutting conditions. The previous figures show that flank wear curves went through three stages of wear: running in wear stage, gradual wear stage or steady state wear, and followed by rapid, fatal wear. Similar observations were documented by Chubb and Billingham 11, Haron 12. The following terminologies are used:Initial or running in wear stage: takes place due to the rapid breakdown of the edge, which is shown by the initial high wear rate in the graph of wear against time. Curves 1, 2, and 3 in Figure 6 this stage is decreased as the cutting speed increasedGradual wear stage: the figures of the three types of cutting inserts, after the initial wear has taken place, indicating a steady gradual stage on the insert wear will form. However, it will increase with less dramatic pattern than the initial stage.Rapid, fatal wear: the final stage of wear, which leads to a catastrophic failure of the cutting inserts. Rapid fatal wear revealed both flank and large crater formation that weakened the tool edge and under sustained resistance to the high cutting forces, caused it to fracture. Testing methods indicated rapid breakdown took place during cutting; causing severe damage to take place on the work-piece surface. Therefore, imagining that the catastrophic failure took place during the final cutting pass at the work piece surface, it is highly likely that the work piece has to be scrapped.Table 6 Cutting speeds used in the test for the specific type of insertsCutting InsertCutting Speed (m/min)KC3136090120150180KC5010210260310360410KC732210260310360410 Cemented Carbide (KC313) (wet & dry)Figure 5 Flank wear as a function of cutting time for KC313(dry and wet)TiN-TiCN-TiN(KC732) (wet & dry)Figure 6 Flank wear as a function of cutting time for KC732(dry and wet)TiALN(KC5010)(wet & dry)0.0 o tt 05101520253035404550556065Time (min)Figure 3-7 Flank wear as a function of cutting time for KC5010 (dry and wet).附录2外文翻译在干燥和潮湿的条件下研究高速切削的费用以及便于机械制造过程的优化1介绍这项研究的目的是在已知试验的切削条件下通过对高速加工与刀具间的寿命之间的关系的调查,来优化选择机械加工过程。此外,在具有可选择的磨损标准下研究切削液的影响,以及研究不同的磨损标准与处于高速加工过程中切削用具的加工费用之间的关系。这项调查研究显示:磨损率与切削速度成比例,观察到的12,18,19证明了这一结论。通过研究在高速切削条件下的高磨损率和加工费用之间的彼此关系,可以更好得了解这项方案的执行过程以及采用这种方案所带来的效益。目前,几乎没有或者说没有数据来解释当使用坚固以及带分度的切削机10时,所需的生命周期的费用,刀具性能,工件的表面粗糙度和尺寸精度。但是,这项研究发现金属切削机床中的刀具费用是加工零件所需费用的三分之一。因此降低制造费用是刀具经营系统16的首要目标。采用这项研究的指导方针的好处有:在不同的磨损标准价值的基础上,它将帮助决定最合理的加工费用以及刀具的更换方案。这项研究另外还提供了程序控制的可视性以及帮助经理在早期的处理计划中与某些因素进一步联系起来。比如,这些因素指的是定期检修,存货水平和加工费用。2实验性研究研究形成了选择正确的切削刀具,切削速度以及选择处于研究过程中用来加工工件材料的切削工具的合理磨损标准的指导方针。这项研究还考虑了各种不同的磨损标准范围为0.1mm到0.6mm(刀具寿命的限制)。本实验是根据国际标准ISO3685 199346而进行的。试验是在多主轴高速机床上进行的,该机床型号为Clausing1300,最大动力为7.5HP(图1)刀具磨损量的测量采用放大倍数为300的光学显微镜,并且该显微镜装有电子显微扫描仪(SEM)。为了确保工件是在极其精确的切削速度下进行,工件的旋转速度是在每一次切削之前由数字转速表(HT5100)测量所得。另一方面,根据ISO3685 199346当工件材料的长度与直径比达到10时,该工件材料就的被替换,这是为了确保工件的稳定性与安全性。为了清除灰尘薄膜以及确保工件的直线度,两次试切的深度应为1.2mm。图1 实验所用的车床2.1工件与切削刀具在这次实验中,热轧钢ASTM4140被选择作为工件材料。以下列出了工件属性:描述:热扎合金钢条,SAE 4140H(UNS H4140)。尺寸:直径15cm,轴线方向长62.25cm。热处理:真空处理,CalAl处理,退火和调制处理,形成ASTM A322和A304。化学成分:依据ASTM标准,工件的化学成分在表1中已给出。实验的执行是符合国际标准组织ISO 36859346的,当工件的长度与直径比为10时,该实验就停止进行并且替换工件,目的是为了符合ISO368546的规定。每根钢条的硬度通过直径比被测量的,以及平均硬度的测量值为29HRC。依据ISO规定,表1列出了实验期间所用的各种切削刀具。表2列出了实验中所用的三种切削工具,表33给出了涂层种类,表34列出了被检测的三种切削刀具的结构。图2给出了普通切削刀具的几何角度。根据ISO标准SUJBR 2525 M16所规定,图3描绘出了刀具牢固地安装在刀夹上的情况。表1 实验所用的ASTM 4140钢的化学成分切削刀具ISO 标准基 材级 配公 司未涂碳VBMT 160408KC 313KennametalTiAlNVBMT 160408KC 313KC 5010KennametalTiN_TiCN_TiNVBMT 160408KC 313KC 732Kennametal表2:实验所用的各种切削刀具碳0.4锰 0.91磷 0.017硫0.02硅0.24镍0.10铬1.01锡0.008铝0.030钒0.002钙0.0064钼0.2铜0.12表3 :涂层物涂 层厚 度层 数TiALN3.5u1TiTiCNTiN3u-3 t-1 t3(TiCN 中间体)2.2 冷却物普遍认为冷却乳化液能帮助降低磨损率和切削温度。实验所用冷却液是以乳化液为基础的水溶液,商业上称作Novick。其中含水量为10%。冷却液的化学成分在表5已列出。以前的研究人员就更好的冷却液的流向有着不同的意见。Taylor17表明为了减少刀具磨损率切削液的流向应在切屑的背后(A向)。Pigott和Colwell47发现通过使用高喷射流的冷却液对准B向就能减少刀具磨损率。Smart和Trent48调查了降低刀具磨损的冷却液方向并且发现在所有的建议中最有效的方向是B向。因此,图4所用的冷却液以直径为1.3cm的喷嘴流出,流速为7.1L/min方向是B向。但是,目前的研究表明在所有作为冷却液而增加刀具寿命的事例中,这种方案并不是十分正确的。研究发现通过某中磨损机制的作用如高速机床(HSM),冷却乳化液帮助减少了刀具磨损率。这种冷却液的效果的详细解释将在第5章介绍。另外,第5章还覆盖了冷却液的简历种类解释以及使用方法。表4:切削刀具的几何数据刀具几何 Tool geometry尺寸刀尖圆弧半径 Nose radius0.8mm前角 Bake rake angle0后角 End cutting-edge angle5副偏角 End cutting-edge angle52余偏角 Side cutting-edge angle30副前角 Side rake angle0副后角 Side relief angle5表5:冷却剂的化学成分硫2030%芳香酒精35%丙烯甘醇以太35%石油润滑油3035%非离子表面活化剂35%氯化烯烃聚合物2030%DesignationBack rake0Side rake 0End relief5 Side relief5 End cutting edge 52Side cutting edge 3Nose radius 0.88mmNose radiusCutting Back rake angleSide rake angle图2 刀具几何图3 安装在刀夹上的切削刀具照片A B图4 冷却液的流向3.切削条件根据ISO 368546规定,表6列出了整个实验过程所用的五种切削速度。切削速度为410m/min对应的刀具涂层含碳,180m/min对应的刀具涂层不含碳,这两种速度大约达到了应用范围的最高极限。如果速度再增加的话将会导致刀具的寿命再实验开始时很短时间内就耗尽或很快损坏。车削实验是在干燥,潮湿以及不同切削速度的条件下进行的,然而两种实验所需的进给量和切削深度各自为0.14mm/rev,1mm。表6给出了三种切削刀具所用的五种速度。4.刀具寿命过程的实验测试最大动力为7.5HP的车床(Clausing 1300)用于车削热轧钢SAE4140H,并且车削过程是在前面所描述的条件下进行的。为了保证切削是在非常正确的速度下执行的,该实验采用了转速表来测量每次单独切削工件前的旋转速度。光学显微镜用来测量切削刀具的后刀面磨损。如果以下两种条件中有一种发生的话,该实验就停止进行。1. 最大的后刀面磨损为0.7mm2. 平均后刀面磨损为0.6mm起初实验的目的是为了确定磨损极限。然而,实验发现在常规条件下切削刀具也存在磨损破坏。因此,VB=0.7mm就作为刀具寿命的极限。在整个实验过程的不同间隔时期观察并测量到刀具后刀面磨损。图5是在干燥,潮湿条件下,不含碳(KC313)刀具的后刀面磨损量与时间的函数图象,并且只包含了三种切削速度。图6是含有夹层刀具(KC732)的后刀面磨损与切削时间函数图象。图37是含TiALN刀具(KC5010)后刀面磨损与切削时间的函数图象,前面所提到的三张图包含了三种切削速度。附件上的切削速度曲线清晰地表示出机器的两种条件下的磨损状况。以上所提到的图象表现出:乳化液可提高KC313,KC732切削刀具的寿命;尤其是在切削时(KC313)3分钟后使用切削液,(KC732)7分钟后更明显。但是,KC5010使用乳化液则产生负面影响。图5, 6说明了任何所阐述的车削条件下,刀具在正常磨损阶段干燥切削条件下,后刀面磨损率会增高,图7说明了任何所阐述的车削条件下,在正常磨损阶段潮湿切削条件下刀具后刀面磨损率也会增高。这种材料性能行为的原因将在第五章(在潮湿条件下KC5010的磨损机理)进行详细全面的介绍。在正常磨损阶段之后,曲线看起来彼此互相平行。这就说明了在干燥和潮湿切削条件下刀具后刀面的磨损率是相同的。前面的图表说明了后刀面磨损曲线经历了三个阶段:初期磨损阶段,正常磨损阶段或稳定磨损阶段以及急剧磨损阶段。相似的观察结果也记录在Chubb和Billingham11,Haron12。以下介绍这三个阶段的概况:初期磨损阶段:产生的原因是为了快速磨平切削刃,而该时期磨损率较高,它随着时间的增长而减少。图6的曲线1,2,3随着切削速度的增高而下降。正常磨损阶段:图片中的三种切削工具,经过初期磨损阶段之后,就意味着进入正常磨损阶段。但是,该时期的磨损率没有初期阶段那么剧烈,而是比较缓慢均匀。急剧磨损阶段:这个时期是磨损的最后阶段,它将导致刀具的损坏。快速磨损揭示了裂纹的形成,它们将削减切削刃并且持续抵抗高切削力,因此导致刀具出现裂纹。该实验揭示了快速破坏发生在切削过程中;将导致工件表面的损坏。因此,可以想象,到最后切削阶段通过工件时刀具损坏产生,也就使工件产生刮痕的几率增高。表6:实验中特殊刀具的切削速度切削工具切削速度(m/min)KC31390120150180KC5010260310360410KC732260310360410含碳(KC313)(潮湿&干燥)图5 KC313(干燥和潮湿)后刀面磨损与切削TiN-TiCN-TiN(KC732)(潮湿&干燥)图6 KC732(干燥和潮湿)后刀面磨损与切削时间函数TiALN(KC5010)(干燥&潮湿)(wet & dry)0.0 o tt 05101520253035404550556065Time (min)图7 :KC5010(干燥和潮湿)后刀面磨损与切削时间函数
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