【作者】 陈华；

【导师】 陈蔚芳；

【作者基本信息】 南京航空航天大学 ， 机械电子工程， 2008， 硕士

【摘要】 航空薄壁件结构复杂、刚性差,在夹紧力和切削力作用下容易产生较大的加工变形,难以保证工件较高的加工精度。因此,围绕低刚度零件,采用有限元仿真等方法,研究薄壁件加工过程优化技术,对加工精度的提高有着重要的理论意义和实用价值。本文以航空中小型薄壁件为对象,采用仿真分析与试验研究相结合的方法,从不同优化角度分析了加工精度的提高方法,包括薄壁件加工过程中的装夹优化、切削参数优化以及路径补偿优化方法,具体研究工作如下:研究了中小型薄壁件装夹方案的优化方法。建立了以最小化关键面上装夹变形引起的形位误差为目标函数的装夹优化数学模型,分析了基于有限元分析软件(ABAQUS)的装夹方案优化流程和关键问题,基于优化模型和优化流程完成了装夹方案的优化。在装夹优化的基础上,对薄壁件加工过程切削参数优化进行了研究。建立了薄壁件分层铣削变形预测动态模型,在此基础上,分析和比较了不同切削条件下的工件加工变形的大小与变化趋势,采用遗传算法与有限元仿真相结合的方法优化了薄壁件加工过程中的切削参数。为了进一步减少加工误差,在装夹优化和切削参数优化的基础上,研究了薄壁件路径补偿的优化方法。根据路径补偿的原理提出了完全补偿和优化补偿两种路径补偿方法,并建立了路径补偿优化模型,分析和比较了补偿前后的加工误差。进行了试验加工,经过与有限元仿真结果的比较,验证了有限元分析模型和优化模型的正确性和有效性。为了实现快速优化过程,在深入研究ABAQUS二次开发方法的基础上,完成了用于加工过程优化的快速仿真平台的开发,该平台有效地集成了装夹优化、加工变形预测、切削参数优化和主动路径补偿及优化等功能,为实现参数化分析运算提供了友好的用户交互界面。更多还原

【Abstract】 Because of complex structure and low rigidity, thin-walled parts in aeronautic engineering are easy to be deformed when the clamping forces and cutting forces are employed. As a result, it is difficult to ensure the high machining accuracy of parts. Research on optimization technology of machining process of thin-walled parts by using finite element method (FEM) has important theoretical and practical value in improving machining accuracy.In this paper, optimization methods of improving machining accuracy of pint-sized/medium-sized thin-walled aeronautic parts, which include optimization method of fixturing, optimization method of cutting parameters and optimization method of active compensation path, are analyzed by integrating simulation and experimentation. The main work is as follows:Firstly, an optimization method of fixturing scheme of pint-sized/medium-sized thin-walled parts is researched. Mathematics model of optimizing fixturing aiming at minimizing form and position errors of important faces caused by fixturing deformations is founded. Key points and processes of optimizing fixturing with finite element analysis (FEA) software (ABAQUS) are studied.Secondly, an optimization method of cutting parameters of thin-walled part machining with optimum fixturing is researched. Dynamic simulation model which can predict deformations of thin-walled part in layered milling is established. With this model, the magnitudes and changing trend of machining deformations with different cutting parameters are analyzed and compared. The optimization method integrating genetic algorithm (GA) and finite element method (FEM) is used to optimize cutting parameters of thin-walled part.Thirdly, in order to further reduce machining error, an optimization method of active compensation path of thin-walled part is research based on optimum fixturing and optimum cutting parameters. Methods of full compensation and optimum compensation are presented according to theory of active path compensation. An optimization model of path compensation is established. Machining errors with compensation and without compensation computed by using dynamic simulation model are compared. The validities of FEA model and optimization model are demonstrated by comparing experimentation results and simulation results.Finally, in order to realize quick simulation of optimization machining process, a fast simulation platform integrating functions of fixture optimization, machining deformation prediction, cutting parameters optimization and active compensation path optimization is structured after in-depth studying methodology of further development in ABAQUS. Friendly interactive interface of parametric analysis is offered in the integrated platform.更多还原