亲疏复合织构化刀具表面的减摩机理研究

The cutting tool is usually in the state of rapid wear resulting from the poor lubrication condition of the tool-chip interface during the high speed cutting process. In this project, a new idea of fabricating textured wetting contrasted surface on the tool, combined with surface texture and wettability control technology, is proposed to actively control the flow state of lubricating medium on the tool-chip interface. The whole rake surface is super-hydrophobic except the inner surface of the visible microgrooves. Therefore the hydrophilic microgrooves could collect and convey the lubricant to the cutting zone. Due to the low friction of super-hydrophobic surface and high energy of new produced chip surface, the lubricating medium could move fast on the tool surface and easily adhere onto the chip surface, which are in favor of forming a lubrication film on the tool-chip interface. It could improve the interface lubrication condition and offer a new way of anti-friction and anti-wear for the cutting tool. Based on the research of tribological properties of the tool-chip interface, the flowing discipline of lubrication on the tool-chip interface and the anti-friction mechanism of textured wetting contrasted surface will be investigated. And then, combined with numerical simulations, flowing test and cutting experiments, the methods of designing texture parameters and hydrophilic/hydrophobic zone distribution will be developed as well as the fabricating process of robust hydrophobic layer with miro/nano hierarchical structures. By introducing the textured wetting contrasted surface onto the cutting tool, the idea to actively control the lubrication condition to the hydrodynamic lubrication will be realized. The results of this research will provide both theoretical and technical supports for the design of high performance cutting tools.

高速切削过程中刀-屑界面恶劣的润滑条件是导致刀具强摩擦磨损的核心问题，本项目结合表面织构与润湿性控制技术，提出在刀具表面制备亲疏复合织构化表面对切削介质流动状态实现主动调控的研究思路：通过亲液微沟槽收集输送润滑介质，通过疏液表面使润滑液迅速运动并转移至高表面能切屑表面成膜，改善界面润滑状态，为刀具减摩降磨技术提供一条新途径。项目重点研究切削介质在亲疏复合织构化刀-屑界面处的流动规律，以及表面微观结构几何特征及亲疏液区域分布的综合减摩机制等刀-屑界面摩擦学特征科学问题；在此基础上，通过仿真计算、切削介质流动性能测试、切削试验等手段，建立刀具表面微观几何形貌的设计准则和亲疏液区域分布的设计方法；探索刀具表面织构和耐磨稳固疏液层的制备工艺，形成系统的亲疏复合织构化表面设计制造方法；实现亲疏复合织构化表面主动调控刀-屑界面为动力润滑状态的减磨思想；为高性能切削刀具设计技术提供理论和技术支撑。

合理设计的表面织构在刀具切削过程中能够有效降低切削力、切削温度，提高刀具抗粘结能力、发挥减摩作用，从而提高刀具寿命。与此同时，在织构表面引入润湿性调控技术可在一定程度上改善表面的润滑状态，为进一步提高其减摩性能提供了一条新的可行的途径。针对15-5PH固溶处理不锈钢、钛合金等难加工材料加工时出现的刀具磨损快的问题，本项目提出了将润湿性控制和表面微织构相结合的方法，制备了微/纳织构化刀具及亲疏复合织构化刀具并研究了它们的摩擦学特性及切削性能。.(1) 首先对YT15微/纳织构的激光制备工艺及摩擦学特性展开了研究。研究了激光扫描速度、激光能量密度及加工次数等工艺参数对微/纳织构几何拓扑形貌和尺寸的影响规律，通过激光工艺参数的优化，实现了刀具表面微/纳织构尺寸和形貌质量的控制，并通过摩擦磨损试验证明，微/纳织构化刀具表面的润湿性可进一步减小刀具/工件接触界面的摩擦系数。.(2) 进行了15-5PH固溶处理不锈钢切削试验，结果表明微/纳织构化刀具可调控切削液的运动状态，改善刀-屑界面的润滑状态，进一步减缓刀具磨损。.(3) 针对亲疏复合织构化PCD刀具展开了深入研究，研究激光工艺参数对微纳结构的尺寸及形貌的影响规律，并阐明微纳结构形貌的形成机理；分别在PCD刀具原始表面和微纳结构表面上制备微沟槽，探究了激光工艺参数对微沟槽尺寸的影响规律；通过对复合织构刀具进行有限元强度仿真，得出复合织构参数对刀具强度的影响规律，并优选出最佳几何及布局参数。.(4) 进行了车削Ti-6Al-4V钛合金的试验，发现在微量润滑条件下相比于无织构刀具、微沟槽刀具，亲疏复合织构化刀具切削力最大下降14.1%、平均摩擦系数最大下降11.5%，刀具粘附最大减轻22.3%。同时，前刀面磨损和粘结情况也有很大改善。.本项目对高性能刀具的表面设计方法、延长刀具寿命、改善难加工材料的加工质量等方面具有重要意义。

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