【作者】 杨晓勇；

【导师】 任成祖；

【作者基本信息】 天津大学 ， 机械制造及其自动化， 2013， 博士

【摘要】 钛合金是二十一世纪最有价值的战略金属材料，是航空、航天领域发展必不可少的“脊柱”之一。钛合金切削过程中刀具磨损严重、加工表面质量差、加工效率低等问题已经成为制约其发展的瓶颈。研究钛合金切削过程中刀具磨损及加工表面质量的形成机理、优化合理的钛合金切削参数对航空、航天等领域的发展具有重要的意义。研究了钛合金侧铣过程中粗、精加工条件下铣削参数对刀具磨损寿命的影响规律，建立了粗、精加工条件下刀具磨损寿命的经验预报模型。分析了钛合金侧铣过程中刀具的破损形式和磨损机理，提出了改善刀具磨损的措施。研究了铣削过程中铣削参数、冷却条件、刀具磨损等因素对铣削力和铣削温度的影响规律，建立了铣削力和铣削温度的经验预报模型。分析了冷却条件、铣削参数和刀具磨损对表面层残余应力的大小、性质及表面层深度的影响规律，建立了残余应力的经验预报模型。基于试验中测得的铣削力和铣削温度，探讨了表面层残余应力的产生机理。分析了冷却条件、铣削参数、刀具磨损对加工表面粗糙度的影响规律，建立了表面粗糙度的经验预报模型，从材料性能和铣削过程两个方面综合探讨了表面粗糙度形成的理论模型。分析了铣削参数及刀具磨损对表面层金相组织和显微硬度分布的影响规律，探讨了表面层显微硬度的产生机理。试验结果表明表面层金相组织会随着铣削速度的增加而发生相变。以本文试验结果为依据，建立了以铣削参数为设计变量，分别以材料去除率、刀具寿命和以材料去除率、表面粗糙度、表面残余应力为目标函数的多目标优化模型，通过遗传算法得到满足目标函数要求的铣削参数，并对优化结果进行了试验验证，验证结果表明优化结果可信度较高。更多还原

【Abstract】 Titanium alloy is one of the most valuable strategic metal material in the21thcentury, and it is the essential material in the aerospace field. Serious tool wear, poormachined surface quality and low machining efficiency have become the mainproblems restricting the development of titanium alloy. Research on the mechanism oftool wear and surface quality in titanium alloy cutting process and optimizing propercutting parameters are of important significance in aerospace field.The laws of tool life influenced by milling parameters were studied in titaniumalloy milling process under rough and finish machining conditions, and predictionmodels of tool life were established under the rough and finish machining conditions.The tool wear mechanism and breakage form were analysed, and the methods wereproposed to improve the tool wear.The laws of cutting force and cutting temperature influenced by cuttingparameters, cooling conditions and tool wear were studied in machining process, andprediction models of cutting force and cutting temperature were established. The size,property and influence depth of residual stress in surface layer influenced by coolingconditions, milling parameters and tool wear were analysed, and residual stressprediction models influenced by milling parameters were established. The mechanismof surface residual stress was discussed based on the milling force and millingtemperature obtained from the experiments.The laws of surface roughness influenced by cooling conditions, cuttingparameters and tool wear were analysed, and the prediction models of surfaceroughness under different machining conditions were established. The theory modelsof surface roughness were established and discussed based on the material propertyand milling process.The change laws of surface layer metallographic structure and microhardnessinfluenced by milling parameters and tool wear were analysed, and the formationmechanism of surface layer microhardness was discussed. The experimental resultsshow that phase transition was taken place with the increase of milling speed.Different multi-objective optimization models were established with the millingparameters as design variables, material removal rate, tool life and material removalrate, surface roughness, surface residual stress as the objective functions, respectively.The milling parameters which meet the different optimization models were obtained by the genetic algorithm and the optimization results were verified by the millingexperiments. Experimental results show that the optimization results are in goodreliability.更多还原