【作者】 戚宝运；

【导师】 何宁；

【作者基本信息】 南京航空航天大学 ， 机械制造及其自动化， 2011， 博士

【摘要】 刀具快速磨损依然是制约难加工材料高速高效加工的关键问题，在未彻底实现陶瓷和超硬材料的高硬度和高韧性完美结合的情况下，利用刀具材料革新实现钛合金、高温合金等难加工材料切削速度进一步提高仍难有本质上的突破。目前钛合金切削加工刀具仍以硬质合金刀具为主，通过改善刀/工表面摩擦接触状态以降低切削力、切削温度和抑制刀具磨损是提高钛合金加工效率的一种有效方式。当前仿生摩擦学的研究发现，高性能的表面织构可以实现良好的减摩、抗黏附和提高耐磨性，这给刀工接触表面状态减摩带来了新的研究方向。为此，本文针对钛合金切削摩擦磨损问题，对表面微织构刀具在钛合金切削加工中的应用进行了探索性研究。主要研究工作包括：（1）通过对传统常规表面刀具在冷却润滑条件下的切削试验，研究了干切削、低温冷风、MQL、低温MQL以及静电环境对钛合金高速切削摩擦状况以及刀具磨损的影响，并结合切削物理仿真试验，分析了冷却润滑介质在刀工副摩擦过程中的作用机理。（2）研究刀具表面微织构的设计与制造，利用有限元技术分析表面微坑/微沟槽织构参数对刀具应力、变形的影响，以指导刀具表面微坑或微沟槽的设计。在此基础上，利用激光加工与电解加工技术对刀具表面微织构进行加工，对比分析两种加工技术的优缺点，为刀具表面微织构的加工提供依据。（3）进行硬质合金/钛合金摩擦副的摩擦磨损试验，通过与传统光滑表面试样的对比，研究了表面微织构的减摩性能，试验结果表明，微织构可以有效地降低摩擦副的摩擦因数，相对于微坑深度，微坑直径对摩擦因数影响程度较大，而微沟槽的减摩效果优于微坑。（4）正交切削TC4的试验结果表明，微坑与微沟槽类型的表面微织构均可以有效地降低硬质合金切削钛合金时的切削力与切削温度，有限元仿真结果表明微沟槽的置入可以延长刀屑接触长度，增大切削力的同时扩大了刀具表面热传导面积，降低了切削变形程度，从而降低切削温度。通过对不同织构类型表面织构刀具切削钛合金时形成的切屑形貌的研究，分析了刀具表面微沟槽对切屑变形的影响。（5）通过TC4钛合金车削试验，分析了干切削、MQL以及低温MQL条件下表面微织构硬质合金刀具在高速切削钛合金时的主要磨损形式和刀具耐用度。结果表明表面微织构刀具的刀具寿命明显高于传统光滑无织构刀具，在干切削、MQL和低温MQL条件下，微沟槽织构刀具分别降低刀具后刀面平均磨损5.0%、7.7%、12.3%。通过对表面微沟槽织构刀具的减摩抗粘结机理以及磨损破损机理的分析，表面微沟槽织构的置入可以降低刀具的粘结磨损。微沟槽的强度对沟槽破损有重要影响，在粘结撕裂和切屑冲击的作用下沟槽间的硬质合金会发生破损。更多还原

【Abstract】 Rapid wear of the tool is still the key issues for high speed machining of difficult-to-cut materials.It is difficult to further enhance the cutting speed of difficult-to-cut materials before perfectcombination of high hardness and toughness of circumstances ceramics and superhard materials.Cemented carbide are mainly used for titanium alloy and it is an effective way to increase themachining efficiency of titanium alloy by improving frictional contact state of tool/workpiece toreduce cutting force, cutting temperature and tool wear. Currently biomimetic tribology study arefound that high-performance surface texture has the effects of good anti-friction, anti-adhesion andimproving the wear resistance, which gives a new research direction that surface texture will beapplied to the surface of cutting tool. In this paper, aiming at friction and wear problems in theprocessing of titanium alloy, the exploratory research was conducted on the application of surfacemicro-textured cutting tool for titanium alloy. The major works are included as follows:(1) The cutting tests for the traditional tools were carried out under the cooling and lubricatingconditions, such as dry cutting, cold air, MQL, cryogenic MQL, static environment, and the influenceof cooling/lubricating medium on friction states and tool wear of high-speed machining of titaniumalloy were studied. Combined with cutting physical simulation experiment, the action mechanism ofcooling/lubricating medium in the friction process of tool/workpiece friction pair was analyzed.(2) The design and manufacturing technology of the tool surface micro-texture was studied. Byfinite element analysis the influence of micro-pit/groove parameters on the tool surface stress anddeformation was analyzed, which guided the design of the tool surface micro-pit/groove. The surfacemicro-textures were processed using laser machining and electrochemical machining technology, andadvantages and disadvantages of the two processing techniques were comparative analyzed, whichprovided a reference value for manufacturing technology of the tool surface micro-texture.(3) Friction and wear test of Ti6Al4V/WC-Co were carried out by comparison with traditionalsmooth surface, and anti-friction properties of micro-textured surface were studied. Test resultsshowed that micro-texture could effectively reduce the friction coefficient of friction pair. Theinfluence of micro-pit diameter on the friction coefficient was greater than micro-pit depth, andmicro-groove had better anti-friction effect than the micro-pit.(4) The orthogonal cutting tests were conducted for the surface micro-textured cutting tool, and thecutting forces and cutting temperatures were measured. The results showed that both the micro-pitsand micro-grooves could effectively reduce the cutting force and cutting temperature under lubricantcondition, and texture types had a greater impact on the cutting performace of tools. Finite elementmodel of orthogonal cutting titanium alloy with surface micro-textured cutting tool was created, andsimulation results showed that the micro-grooves could extend the tool/chip contact length, increasecutting force while widen the heat transfer surface area of the tool, decrease the cutting deformation,thus reduce the cutting temperature. The chip morphologies of titanium alloy were observed and theimpact of micro-grooves on the chip formation was analyzed.(5) Turning tests with surface micro-textured cutting tool were carried out and the results showedthat the surface micro-grooved cutting tool had higher tool life than the traditional smooth surfacecutting tool. In dry, MQL and cryogenic MQL conditions, micro-grooved cutting tool decreased theaverage flank wear of5.0%,7.7%,12.3%. Wear and damage mechanism of surface micro-grooved cutting tool was analyzed. It was found that surface micro-grooves could reduce adhesion wear of tooland cemented carbide between micro-grooves would damage in the action of adhesion and impact ofchip.更多还原