【作者】 张为；

【导师】 郑敏利；

【作者基本信息】 哈尔滨理工大学 ， 机械制造及其自动化， 2011， 博士

【摘要】 航空航天制造业作为制造业最重要的组成部分,代表了一个国家最高制造水平和技术实力。现代飞机、航天器等航空航天产品大量采用轻量化的高强度、薄壁零件来降低自身重量,提高发动机的推重比。可以预见,随着航空航天工业的进一步发展,薄壁零件的应用越来越广泛,质量需求也会进一步提高。钛合金具有耐高温、耐腐蚀性好、比强度高等优点,已成为当代飞机和发动机的主要结构材料之一,并且其用量比重呈逐渐增长的趋势。在美国某些军用飞机中,钛合金材料的用量已达40%以上,其中,又以TC4钛合金(Ti-6A1-4V)为代表的α+β相钛合金的应用最为普遍。为了满足零件的使用性能及可靠性,航空航天钛合金薄壁件对已加工表面质量、加工精度及加工效率要求很高。受钛合金材料小变形系数、低导热率、高化学活性及高表面缺陷敏感性等物理性能,以及薄壁结构导致的刚度低、切削振动大、加工工艺性差等因素影响,目前国内此类零件的整体加工水平不高,其中又以零件表面完整性与面形精度问题最为突出,已成为制约航空航天产品研制开发进程的重要瓶颈。高速切削加工技术正以其高效率、高精度、高表面质量等突出优点,已逐步成为美国波音、休斯公司,欧洲空客公司等大型飞机制造企业中钛合金薄壁件的主流加工技术,表现出蓬勃的生机。为此,本文进行如下研究:通过分析钛合金膜盘切削加工表面形成过程,建立了考虑刀具振动的高速切削钛合金膜盘表面形貌模型,进行了表面形貌仿真研究;通过表面粗糙度、表面形貌测试实验,对表面形貌的仿真结果进行验证;在表面形貌建模与仿真基础上,基于遗传算法,以已加工表面粗糙度和切削效率为目标,进行高速切削钛合金膜盘切削参数优化,建立钛合金膜盘切削参数优化及形貌仿真系统。针对钛合金膜盘不同夹紧方式,依据材料力学、弹塑性力学、计算力学,进行了夹紧力、切削力引起的钛合金膜盘型面扭转变形、弯曲变形的力学解析计算,并与有限元仿真结果进行对比分析,实现了不同夹紧方式、夹紧力和切削力作用下钛合金膜盘型面变形精度预测,同时为钛合金膜盘的夹紧方式优化和工装型面设计提供了力学理论基础。将实验测试与数值模拟相结合,研究了已加工表面残余应力变化规律,重点分析了加工过程中残余应力释放引起的变形;通过钛合金材料表面显微硬度的实验研究,获得了已加工表面硬化的评价指标变化范围;进行了表面变质层深度、金相组织、晶格、硬度及微观结构变化的SEM测试与理论分析。通过对上述表面物理性能参数变化规律的理论与实验研究,获得了切削参数对高速切削钛合金表面物理性能的影响规律,为进一步提高钛合金材料、钛合金薄壁件已加工表面质量提供了理论依据与实验数据支持。更多还原

【Abstract】 As the most important component of manufacturing industry, aerospace manufacturing industry represents national highest manufacturing standard and technical strength. Modern aircraft and spacecraft as well as other aerospace products use a large number of lightweight and high strength thin-walled components to reduce its weight, and increase the thrust weight ratio of engine. It can be predicted that along with the further development of aerospace industry, thin-walled components will be used more and more widely, and the demand of quality will also be further improved. Titanium alloy has many advantages, such as high temperature resistance, good corrosion resistance, and high strength, which has become one of the main structure materials of modern aircraft and engine, and its dosage proportion shows increasing trend. In some military aircraft of U.S, the dosage of titanium alloy material has reached over 40%, among them, TC4 titanium alloy (Ti-6A1-4V) as the representative ofα+βphase titanium alloy is used frequently.In order to meet the performance and reliability of components, aerospace titanium alloy thin-walled component has high demand on machined surface quality and machining precision as well as machining efficiency. Because of the titanium alloy material physical properties such as small deformation coefficient, low thermal conductivity, high chemical activity and high surface imperfection sensitivity and others, as well as the low stiffness and large cutting vibration, poor processing technology and other factors caused by thin-walled structure, the overall processing level of this kind component is not high in China currently; especially the component surface integrity and face shape precision are the most prominent problem which has become the important bottleneck to restrict aerospace product developing. With its high efficiency, high precision, high surface quality and other advantages, high speed machining technology has become the mainstream processing technology of titanium alloy thin-walled components in America Boeing, Hughes Company, the European Airbus Corporation and other large aircraft manufacturing enterprises, which has showed vigorous vitality. Accordingly, the following is researched in this paper:Considering tool vibration, surface topography model of high speed cutting titanium alloy diaphragm disk is established by analyzing the machined surface forming process of titanium alloy diaphragm disk after cutting, and the simulation of surface topography is also researched; by testing experiment of surface roughness and surface topography, the simulation results of the surface topography are validated. On the basis of surface topography modeling and simulating, using genetic algorithm, and taking machined surface roughness and cutting efficiency as the goal, high speed cutting titanium alloy diaphragm disk cutting parameters optimization is made, and the titanium alloy diaphragm disk cutting parameters optimization membrane and morphology simulation system are also established.On account of the titanium alloy diaphragm disk with different clamping means, titanium alloy diaphragm disk surface torsion deformation and bending deformation induced by clamping force and cutting force are calculated according to material mechanics, elastic-plastic mechanics and computational mechanics; meanwhile comparative analysis of the results with finite element simulation is made, which can achieve deformation precision prediction of titanium alloy diaphragm disk surface with different clamping method and clamping force as well as cutting force. At the same time, it offers mechanical theoretical basis for titanium alloy diaphragm disk clamping method optimization and tool profile design.Combined the experiment results with numerical simulation, the change law of surface residual stress is studied, and the deformation caused by the release of residual stress in the process is selective researched. Through researching on titanium alloy material surface micro-hardness experiments, the machined surface hardening evaluation index value changing range is obtained; Surface metamorphic layer depth and metallographic structure as well as lattice and hardness and microstructure changes are theoretical analyzed and tested with SEM; Based on the theoretical and experimental study of surface physical performance parameters change law mentioned above, the influence law of cutting parameters on physical properties of titanium alloy machined surface in high speed cutting is obtained, which has provided the theoretical basis and experimental data support for improving machined surface quality of titanium alloy material and titanium alloy thin-walled component.更多还原