【正文】 2 The average flank wear 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, VB,nax = 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。 Side cutting edge ________________ 3176。 Side relief 5 176。 Side rake ____ 0176。 Side relief angle 539。 End cuttingedge angle 52176。. It is mixed with water at a concentration of 10%. The coolant position 湘潭大學(xué)興湘學(xué)院 29 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 from a nozzle with diameter of cm and a flow rate of 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 geometry Tool geometry Dimension Nose radius (mm) Bake rake angle 0 176。 1 TiNTiCNTiN 3 181。如果我們?nèi)蝿谌卧埂⒛瞰I(xiàn)的老師們的指導(dǎo)，我們將很可能達(dá)不到預(yù)期的效果 .在此再 次的表示忠心的感謝和誠(chéng)摯的問(wèn)候 . 湘潭大學(xué)興湘學(xué)院 26 附錄 1英 文原文 英文原文 COST STUDY OF HIGHSPEED CUTTING UNDER DRY AND WET CONDITIONS FOR MACHINING PROCESSES OPTIMIZATION 1. Introduction The 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 system[16]. 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 Study The 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 to (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 (see Figure 31). 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 (HT5100) 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 mm depth, to clean up the thin layer of rust, and to ensure work piece straightness. 湘潭大學(xué)興湘學(xué)院 27 Figure 1 The tuning machine used during the test. Workpiece and Cutting Inserts In 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 cm length Heat Treatment: Vacuum degassed/processed, CalAl treated, annealed and special straightened, conforming to ASTM A322 and A304 Chemical positions: The position of the work piece material is listed in Table according to the ASTM standards. The experiment was carried out in accordance with the international standard anization ISO368593 [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 29HR