静电微量润滑气雾特性及其切削加工性能研究

Study on Aerosol Characteristics of Electrostatic Minimum Quantity Lubrication and Its Turning Performance

静电微量润滑(Electrostatic minimum quantity lubrication,EMQL)技术可显著提高荷电润滑液滴在加工区域的润湿、渗透和沉积性能,改善气雾的润滑冷却能力,降低切削环境油雾浓度。在构建静电微量润滑切削加工系统的基础上,分析了EMQL下荷电电压对润滑油液滴粒径、分布、润湿性和沉积性的影响。研究了EMQL的稳态换热能力,加工环境油雾浓度和切削性能。最后通过刀具磨损分析,揭示了EMQL切削加工时的作用机理。结果表明:荷电后润滑油液滴的粒径减小,分布更加均匀,润湿和沉积性提高。与传统MQL比较,EMQL下的切削温度降低了～14%,环境油雾浓度减小了～8%,刀具磨损下降了～37%,工件表面质量提高了～28%。EMQL加工时,润湿渗透性能改善的小粒径润滑油液滴易在刀具-工件接触面吸附,渗透和铺展,利于切削界面的润滑与换热,车削加工性能更好。

The technology of electrostatic minimum quantity lubrication(EMQL)can not only enhance the depositing rate of lubricant droplets on the cutting area,but also increase their wetting and penetration to the contact interface,which thus improve droplet lubrication and cooling,as well as reduce concentration of the oil mist floating in the cutting environment.As a EMQL cutting system is developed,the effect of charging voltages on the diameter and distribution of lubricant droplets are investigated,and droplet wettability and deposition on the cutting interface are analyzed.The heat transfer capacity of EMQL in steady stage and its machining performance and oil-mist concentration after turning are comparatively studied.By use of tool wear analysis,the lubrication mechanism of EMQL in the cutting process is revealed.Results indicate that as lubricant charged,droplet diameter decrease and its distribution improve with an enhancement in the wettability and deposition.The cutting temperature,oil mist concentration,tool wear and workpiece surface roughness of EMQL are 14%,8%,37%and 28%lower than those of the traditional MQL,respectively.When EMQL is used,the improved wettability and reduced droplet diameter allow lubricant droplets to enter and cover the tool-workpiece interface more easily,which would help lubricate and cool the cutting interface,and thus achieve a better cutting performance.