机械毕业设计英文外文翻译554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.docx

1、机械毕业设计英文外文翻译554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附录1英文原文英文原文CHAPTER IIICOST STUDY OF HIGH-SPEED CUTTING UNDER DRY AND WET CONDITIONSFOR MACHINING PROCESSES OPTIMIZATION3.1 IntroductionThe aim of this study is to optimize the machining processes by investigating the relationship between the high speed

2、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

3、 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 ha

4、ve 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

5、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 contro

6、l and helps the managers in the early process planning steps to associate factors such as preventive maintenance, levels of inventory, and machining cost.3.2 Experimental StudyThe study developed a guideline of choosing the right cutting tool, cutting speed, and selecting the appropriate wear criter

7、ia 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 d

8、one 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 m

9、easured 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 stab

10、ility 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 3-1 The tuning machine used during the test.3.2.1 Workpiece and Cutting InsertsIn this study, hot rolled ASTM 4140 steel was selected as the workpiece mat

11、erial. 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 com

12、positions: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 ra

13、tio 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

14、 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 rigid

15、ly on a tool holder are depicted in Figure3-3 with an ISO designation of SVJBR 2525 M16.Table 3-1 Chemical composition of ASTM4140 steel used in the testCutting insertsISO DesignationSubstrateGradeCompanyUncoatedcementedCarbideVBMT 160408.KC 313KennametalTiAlNVBMT 160408KC313KC5010KennametalTiN-TiCN

16、-TiNVBMT 160408KC313KC732KennametalTable 3-2 Types of the tested cutting insertsCarbonManganesePhosphorusSulfurSiliconNickelChromium0.40.910.0170.020.240.101.01Tin0.008Aluminum0.030Vanadium0.002Calcium0.0064Molly0.2Copper0.12Table 3-3 Coatings propertiesCoatingThicknessNumber of layersTiALN3.5 1TiN-

17、TiCN-TiN3 -3 t-1 t3(TiCN intermediate)3.2.2 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 coolan

18、t composition includes the listed chemicals in Table 3.5. 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

19、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

20、 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 activat

21、ing 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 3-4 Assembled cutting tool geometryTool geomet

22、ryDimensionNose radius0.8 (mm)Bake rake angle0 End relief angle5End cutting-edge angle52Side cutting-edge angle30Side rake angle0Side relief angle5Table 3-5 Coolant chemical compositionsSulfate20-30%Aromatic alcohol3-5%Propylene glycol ether3-5%Petroleum oil30-35%Nonionic surfactant3-5%Chlorinated a

23、lkene polymer20-30%Angular toolDesignationBack rake 0Side rake 0End relief 5 Side relief 5 End cutting edge 52Side cutting edge 3Nose radius 0.88mm Nose radius Cutting Back rake angleSide rake angleFigure 3-2 Assembled tool geometryFigure 3-3 Photograph of the cutting insert fixed on the tool holder

24、 A BFigure 3-4 coolant stream direction.3.3 Cutting ConditionsBased on I803685 46 five cutting speeds were used throughout the testing as listed on Table 3-6. Cutting speeds corresponding to 410 m/min for the coated carbide tools and180 m/min for the uncoated carbide tools were approximately the upp

25、er 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

26、.14 mm/rev and depth of cut at(1mm). Five cutting speeds were selected for the three types of cutting inserts, as listed in Table3-6.3.4 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 carrie

27、d 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 wea

28、r 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

29、 worn out regularly on the flank side. Therfore, VB,nax =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 (3-5) shows flank wear as a function of cutting time for the cemented carbide (K

30、C313) under dry and wet conditions, and includes only three cutting speeds for clarity.Figure 3-6 presents the flank wear as a function of cutting time for sandwich coated inserts ( KC732) under dry and wet conditions. Figure 3-7 shows the flank wear as a function of cutting time for TiALN coated cu

31、tting 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 3-5, and Figure 3-6 show that at any set of turning conditions, the flank wear increased at a higher rate a