Influence of Ranque-Hilsch vortex tube and nitrogen gas assisted MQL in precision turning of Al 6061-T6
Influence of Ranque-Hilsch vortex tube and nitrogen gas assisted MQL in precision turning of Al 6061-T6
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DOI：
10.1016/j.precisioneng.2018.04.011
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发表时间：
2018-07-01
影响因子：
3.6
通讯作者：
Sharma, Vishal S.
中科院分区：
文献类型：
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作者：
Mia, Mozammel;Singh, GurRaj;Sharma, Vishal S.
由于热逆境，特别是对于低熔点材料如Al 6061-T6，干式加工不希望产生精密表面。同样，传统的泛冷既不经济可行，也不环保。在此背景下，三个新的冷却润滑（C/L）技术，即氮气冷却（NGC），氮气辅助的最小量润滑（NGMQL）和朗克-希尔施涡流管（RHVT）NGMQL进行了研究沿着与空气冷却（AC）在车削，试图降低表面粗糙度（R-α）和刀具后刀面磨损（VBmax）。使用未涂覆的WC刀片在两个水平的切削速度和进给速率下进行加工;并且，使用氮气和/或菜籽油作为冷却/润滑介质。分析了加工表面、磨损表面和切屑的SEM和3D形貌图像。结果表明，RHVT-NGMQL显示出最小的表面粗糙度和刀具磨损（与其他C/L相比，改善了75%）。值得注意的磨损模式为：干切削时塑性变形、积屑瘤和粘附; NGC时积屑瘤; NGMQL时摩擦和粘附; RHVT-NGMQL时粘附。在微观层次上，所研究的C/L方法在芯片结构上没有发现显著差异。此外，采用复合期望优化来同时系统地最小化R-a和VBmax。结果表明，在RHVT-NGMQL C/L条件下，最佳加工速度v（c）= 160 m/min，进给速度f = 0.06 mm/rev时，可获得粗糙度< 1.0 μ m的精密表面。
Dry machining is undesirable to produce precision surface due to thermal adversities especially for a low melting point material such as Al 6061-T6. Likewise, the conventional flood cooling is neither economically viable nor eco-friendly. In this context, three novel cooling-lubrication (C/L) technologies namely the nitrogen gas cooling (NGC), nitrogen gas assisted minimum quantity lubrication (NGMQL) and Ranque-Hilsch vortex tube (RHVT) NGMQL are investigated along with the air cooling (AC) in turning with an attempt to reduce surface roughness (R-a) and tool flank wear (VBmax). The machining was conducted using uncoated WC insert at two-levels of cutting speed and feed rate; and, as medium of cooling/lubrication the nitrogen gas and/or canola oil is employed. The SEM and 3D topographic images were analyzed for the machined surfaces, worn tool surfaces and chips. Results showed that the RHVT-NGMQL revealed the least surface roughness and tool wear (similar to 75% improvement compared to other C/Ls). Notable wear modes were: in dry cutting the plastic deformation, BUE and adhesion; in NGC the BUE; in NGMQL the rubbing and adhesion; in RHVT-NGMQL the adhesion. In micro-level, no significant difference in chip structure was found for the studied C/L methods In addition, the Composite Desirability optimization was adopted to systematically minimize R-a and VBmax concurrently. It was found that the optimum speed v(c) = 160 m/min and feed rate f = 0.06 mm/rev under RHVT-NGMQL C/L condition has the potential to generate a precision surface with a roughness value < 1.0 mu m.