【作者】 李宁；

【导师】 陈永洁；

【作者基本信息】 华中科技大学 ， 机械制造及其自动化， 2018， 博士

【摘要】 作为绿色制造战略实施的具体体现,干切削技术目前已成为加工领域的研究热点之一。随着航空航天业的发展对制造业不断提出新的要求,钛合金由于其优良的综合特性被广泛地应用于各种整体复杂结构件中,且其用量越来越大。为了实现这些航空航天钛合金的高效、高性能加工,刀具快速磨损依然是亟待解决的关键问题,而切削区的剧烈摩擦与很高的切削温度是导致钛合金切削过程中刀具快速磨损的主要原因。因具有良好的减摩功能,且能够提高抗黏附以及耐磨性,高性能的表面织构给刀具-工件和刀具-切屑接触表面的减摩、刀具切削性能的提升带来了新的研究方向,对于保护环境、节约能源、降低加工成本具有重要意义。针对钛合金加工过程中刀具快速磨损,钛合金加工效率低以及加工质量不达标等问题,本文提出了深亚毫米尺度的表面织构刀具的设计方案,并对该表面织构刀具用于钛合金切削展开了探索性的研究,具体工作以及取得的成果如下:（1）探究了减摩槽刀具切削钛合金Ti-6Al-4V时的性能,从切削力、刀具-切屑接触面上的平均摩擦系数以及切屑形态等方面研究并获得了减摩槽结构对刀具切削性能的影响规律。与无减摩槽刀具对比,该减摩槽刀具需要在与之匹配的切削条件下才具有减小切削力、改善刀具-切屑接触表面摩擦性能的效果,其结构参数需要改进。（2）提出了深亚毫米尺度的表面织构刀具的设计方案,在无涂层硬质合金平面刀片上设计了不同类型、不同参数的深亚毫米级表面织构,采用仿真模拟的方法对这些织构刀具的性能进行了研究。有限元结构强度的分析表明,前刀面上这些表面织构的置入对刀片结构强度几乎没有影响;通过切削模拟仿真研究了这些织构刀具的切削性能,分析了表面织构参数如沟槽形状、宽度、深度、第一沟槽离刀刃的距离以及沟槽间的间距等对刀具切削性能的影响,并对表面织构刀具的这些结构参数进行了优化。（3）制造了九种深亚毫米尺度表面织构刀片,通过干车削Ti-6Al-4V试验,从切削力、切屑形貌、刀具-切屑接触面上的平均摩擦系数、刀具磨损、加工表面粗糙度等方面,研究了织构参数、织构类型对刀具切削性能的影响。结果表明,深亚毫米尺度表面织构的置入可以改善刀具的切削性能,其机理可以通过刀具-切屑接触面积的减少、切屑陷入织构的程度以及犁切效应之间的相互作用来解释。在所有织构刀片中,平行于主切削刃的沟槽型织构刀片P01在减少切削力、改善前刀面的摩擦性能方面表现出了最佳的性能;同时,前刀面上合理的表面织构的置入有助于提高刀具的抗粘结性能,改善工件已加工表面质量。（4）验证了优化的表面织构刀具性能,基于切削模拟仿真分析的结果,得到了七组优化的表面织构参数,并通过仿真与切削试验验证了优化的表面织构刀具性能;为了进一步改善织构刀具的切削性能,探究了在织构中填充固体润滑脂MoS₂后刀具的切削性能。验证结果显示:相对于织构刀片P01,优化的织构刀片N1^N7在减小切削力、改善前刀面上摩擦磨损性能、增强抗磨损性能方面均表现出了更好的性能。更多还原

【Abstract】 As a concrete embodiment of green manufacturing strategy implementation,dry cutting technology has become one of the research hotspots in the machining field.With the development of aerospace industry,which constantly puts forward new requirements for the manufacturing industry,titanium alloys have been widely used in all kinds of integral complex structural parts with the increasing amount due to their excellent comprehensive properties.In order to realize the high efficiency and high performance machining of these aerospace titanium alloys,rapid tool wear mainly caused by the severe friction and high cutting temperature in the cutting zone is still the key problem to be solved.With good anti-friction,anti-adhesion functions and improved wear resistance,high performance surface texture brings new research directions for reducing the friction at tool-workpiece and tool-chip contact surfaces and improving tool cutting performance,which is of great significance to conserve resources,protect the environment and reduce costs.Aiming at the problems of rapid tool wear,very low efficiency and poor quality of machined surface in titanium alloy processing and the difficulty in mass production of existing micro-/nano-textured tools,the design scheme of deep submillimeter-scaled textured tools was proposed and the exploratory research on the application of these tools in dry cutting of Ti-6Al-4V was carried out in this article.Specific work and the results achieved are summarized as follows:（1）The cutting performance of the tool with friction-reducing grooves was investigated during dry turning of Ti-6Al-4V in terms of cutting forces,average friction coefficient on tool-chip interface and chip morphology.Compared with the non-grooved tool,this kind of friction-reducing grooves can reduce cutting force and improve the friction performance of tool surface only under the matched cutting conditions.Therefore,the structural parameters of these friction-reducing grooves need to be improved.（2）The design scheme of deep submillimeter-scaled textured tools was proposed,with different texturing types and parameters designed on the uncoated cemented carbide flat inserts.By simulation method,the performance of these textured tools was investigated.The analysis of finite element structural strength simulation shows that the implantation of these surface textures on rake faces had almost no effect on the mechanical strength of the inserts.Using cutting simulation,the cutting performances of these textured tools were studied,and the effects of texturing parameters such as groove width,depth,and the distance from the first groove to the cutting edge,and groove spacing,on the tool cutting performance were analyzed,and at last,these structural parameters of surface textured tools were optimized.（3）Nine kinds of deep submillimeter-scaled surface textured inserts were fabricated,and the influence of these textures on cutting performance was investigated during dry turning of Ti-6Al-4V.The cutting performance of these tools was evaluated in terms of cutting forces,chip morphology,coefficient of friction at the tool-chip interface,tool wear and surface roughness.The results show that the implantation of these textures on the rake face can improve the tool cutting performance,and the mechanism can be explained by the interaction between the reduction of tool-chip contact surface and the immersion of chips into grooves or pits and the ploughing effect.Among all the textured inserts,the parallel type P01 shows the best performance in reducing cutting force,improving the friction properties on the rake face and the tool wear resistance.At the same time,the reasonable surface texture on the tool rake face is helpful to improve the anti-adhesion performance of the tool,and thus improve the machined surface quality of the workpiece.（4）Based on the results of cutting simulation analysis,seven groups of optimized surface texture parameters were obtained,and the cutting performance of these optimized tools was verified by simulation and cutting tests.Finally,the cutting performance of these optimized textured tools filled with solid lubricant MoS₂ was investigated for further performance improvements.The verification results show that compared with the insert P01,the optimized textured inserts N1^N7 show better performance in reducing the cutting forces,improving the friction performance on the rake face and enhancing the wear resistance.更多还原