基于微量纳米流体静电雾化射流强化冷却润滑的难加工材料高效洁净切削工艺基础研究

Aiming at the current situation that minimum quantity lubrication can not meet the challenge of cooling/lubrication and environmental protection for green high efficiency cutting of difficult-to-machine materials, this project presents a technology for high efficiency clean cutting of difficult-to-machine materials based on the enhanced cooling/lubrication of electrostatic spray of micro nanofluid. In this technology, an electrostatic field is established between nozzle and cutting tool, which makes the nanofluid with high cooling/lubrication performance splited into charged droplets. And then, under the influence of electric field force, droplets are transported to cutting zone directionally and controllably, thus cooling and lubricating cutting zone fully, and reducing the drift of droplets with small diameter. The concrete research contents are listed as follows: Firstly, a design model of nanofluid is built based on the requirement of high efficiency cutting of difficult-to-machine materials, and the fundamental principle of nanofluid. Secondly, based upon the basic principle of charged medium and the theory of electrostatic atomization, a cutting experimental setup of electrostatic atomization is optimized and developed, atomization performance of micro nanofluid and transport rule of droplets are explored. Finally, with the support of heat transfer theory and nanotribology, heat transfer enhancement mechanism and tool wear mechanism in high efficiency cutting are revealed under the electrostatic spray of micro nanofluid, by means of systematic heat transfer, tribology and cutting experiments, and in-depth theoretical research. This project is intended to develop a new technology of high efficiency clean cutting of difficult-to-machine materials, and to further increase machining efficiency of difficult-to-machine materials and reduce environmental pollution.

针对微量润滑无法满足难加工材料绿色高效切削对冷却润滑与环保高要求的现状，本项目提出基于微量纳米流体静电雾化射流强化冷却润滑的难加工材料高效洁净切削工艺，在喷嘴与刀具间建立静电场，使具有优异冷却润滑性能的纳米流体破碎成带电雾滴，在电场力的作用下，雾滴向切削区作定向可控输运，从而可充分发挥雾滴对切削区的冷却润滑作用，减少小直径雾滴的飘移散失。具体研究内容包括：基于难加工材料高效切削要求与纳米流体基本原理，建立纳米流体设计模型；基于介质荷电基本原理与静电雾化理论，优化设计与构建微量纳米流体静电雾化切削试验系统，探索微量纳米流体静电雾化性能与雾滴输运规律；在传热学理论和纳米摩擦学理论的支持下，通过系统的传热、摩擦及切削试验和深入的理论研究，揭示微量纳米流体静电雾化射流强化换热机理及其高效切削刀具磨损机理。本项目旨在发展难加工材料高效洁净切削新工艺，进一步提高难加工材料高效加工效率，减少环境污染。

绿色高效切削工艺是21 世纪先进制造技术重点研究开发的关键基础技术之一。现阶段微量润滑技术无法满足难加工材料绿色高效切削工艺对冷却润滑与环保的高要求。有鉴于此，本项目提出基于微量纳米流体静电雾化射流强化冷却润滑的难加工材料高效洁净切削工艺。在喷嘴与刀具间建立静电场，使具有优异冷却润滑性能的纳米流体破碎成带电雾滴，通过改变喷嘴与刀具之间的静电场(场强及分布)可调控雾滴大小、分布及运动轨迹，实现雾滴向切削区作定向可控输运，充分发挥雾滴对切削区的冷却润滑作用，减少小直径雾滴的飘移散失。.主要工作包括：.(1) 通过构建高效切削用量条件、冷却润滑能力与加工性能的关系模型，探明纳米流体热物性对其冷却润滑能力的影响规律及纳米流体特性对其热物性的影响规律，建立了纳米流体设计模型，为纳米流体在高效切削中的应用提供依据。.(2) 基于介质荷电原理和静电雾化理论，设计构建了微量纳米流体静电雾化切削试验系统，研究了荷电电压、流量、电极间距及喷嘴角度对水基和油基纳米流体静电雾化特性的影响，获得了静电雾化性能和雾滴输运规律。.(3) 创新设计构建了微量纳米流体静电雾化瞬态和稳态传热试验装置，评价了其换热性能，揭示了微量纳米流体静电雾化射流的强化换热机理。.(4) 基于静电场仿真对静电雾化切削参数进行了优化，在此基础上，开展了微量润滑、微量纳米流体静电雾化射流等冷却润滑条件下高效切削钛合金的刀具磨损对比试验，确证了微量纳米流体静电雾化射流的切削性能优势，揭示了其减摩抗磨机理。