Particle size distribution characteristics of electrostatic minimum quantity lubrication and grinding surface quality evaluation
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摘要: 针对微量润滑(minimum quantity lubrication, MQL)依靠的高压气体雾化微液滴粒径细化程度低、易飞逸飘散,有效利用率低以及对环境和人员健康产生危害的问题,提出气辅式静电微量润滑(electrostatic minimum quantity lubrication, EMQL)雾化新方法。开展多工况雾化性能对比试验,并对镍基合金磨削表面质量进行评价。结果表明:润滑剂荷电后雾化性能得到显著提高,在降低液滴平均体积粒径和分布跨度的同时,降低了悬浮可吸入小液滴(PM10)的质量浓度,且电压越高PM10质量浓度越低。当电压为35 kV时, 润滑剂的雾化效果最理想,平均体积粒径和分布跨度分别降低了27.343%和41.456%,PM10质量浓度降低了5.065个百分点。磨削试验结果表明:相较气动雾化微量润滑,静电雾化微量润滑获得了更为理想的工件表面质量;当电压为35 kV时,工件表面粗糙度Ra和RSm分别为0.377 μm 和0.084 mm; 干磨削工件表面质量极差,出现大量黏附和剥落现象,甚至有大面积的表面材料撕裂,因此干磨削不适用于高温镍基合金加工。Abstract: A new method of gas assisted electrostatic atomization minimum quantity lubrication is proposed to solve the problems of low effective utilization rate and threat to the environment and human health due to the low degree of particle size refinement and easy flying of micro droplets atomized by high pressure gas. The contrast test of atomization performance under different working conditions is carried out, and the surface quality of nickel base alloy grinding is evaluated. The atomization test results show that the atomization performance of charged liquid is significantly improved, and the percentage concentration of suspended inhalable small droplets (PM10) is reduced while the average size and distribution span of droplets are reduced. And the higher the voltage is, the lower the mass concentration of PM10 is. When the voltage reaches 35 kV, the atomization effect is the optimal, the average volume particle size and distribution span are reduced by 27.343% and 41.456% respectively, and the mass concentration of PM10 is reduced by 5.065 percentage points. The results of grinding test show that the surface quality of the electrostatic minimum quantity lubrication is better than that of the minimum quantity lubrication by pneumatic atomization, and when the voltage is 35 kV, the surface roughness Ra and RSm are 0.377 μm and 0.084 mm, the surface quality of dry grinding workpiece is very poor, there are a lot of adhesion and peeling phenomenon, even a large area of surface material tearing, so dry grinding is not suitable for high temperature nickel base alloy processing.
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