薄壁件柔性装夹加工变形研究

发布时间：2017-12-27 01:08

本文关键词：薄壁件柔性装夹加工变形研究　出处：《沈阳航空航天大学》2016年硕士论文　论文类型：学位论文

【摘要】：航空大型薄壁件由于其尺寸大,刚度低,结构复杂,在加工过程中极易产生加工变形,使得其加工成本高、周期长,制约着航空制造业的发展,一直以来都在寻求有效的方法解决这类问题。随着自动化水平的不断提高,多点柔性工装系统成为研究的热点,它能够有效的解决大型薄壁件在铣削加工中的变形问题。国外已经将其应用到实际生产中,国内仍处于研发和工艺试验阶段。本文针对开发柔性工装系统的需求,对其在控制薄壁件加工变形的方法进行研究,对多点柔性工装系统的设计予以借鉴。首先,通过UG软件建立铣刀模型,导入ABAQUS有限元分析软件,采用有限元分析软件ABAQUS对铣削加工过程及多点柔性工装装夹定位过程进行有效建模,准确定义有限元模型的各项材料属性、接触方法、本构模型和分离准则等。并对多点柔性工装系统的基本组成和工作原理进行介绍,对多点定位原理进行分析。通过实验的方法对航空铝合金7050-T7451进行实际铣削加工以建立其铣削力学模型,为多点柔性工装支撑单元数量的确定提供依据。然后,运用有限元方法对比分析多点柔性工装相对传统装夹有着明显的优势,并验证了有限元模型的有效性。接着利用有限元的方法分析在仅有重力和装夹力的作用下夹持力、支撑单元布局和支撑单元间距对薄壁件变形的影响规律;在铣削加工过程中,研究夹持力、支撑单元布局和支撑单元间距对加工变形的影响规律。总结出能够有效节省调配时间和资源占用率的装夹布局方法。最后,结合有限元技术、正交实验理论和多元非线性回归的方法,提出以支撑单元的布局为设计参数,建立以薄壁件的最大变形和平均变形为指标的加工变形预测模型。为了简化计算,采用加权的方法将多目标预测模型转化为单目标预测模型,进一步以该单目标预测模型为目标函数,采用全局寻优能力较强的遗传算法进行优化计算,得到理论最优的装夹布局。
[Abstract]:Because of its large size, low rigidity and complex structure, aviation large thin-walled parts are prone to machining deformation during the processing, making the processing cost high and the cycle long, which restricts the development of aviation manufacturing industry. With the continuous improvement of automation level, multi-point flexible tooling system has become a research hotspot. It can effectively solve the deformation problem of large thin-walled parts in milling. It has been applied to practical production abroad, and it is still in the stage of R & D and process test in China. In view of the demand of developing flexible tooling system, this paper studies the method of controlling the deformation of thin-walled parts, and provides reference for the design of multi-point flexible tooling system. First of all, the establishment of tool model by UG software, using ABAQUS finite element analysis software, using finite element analysis software ABAQUS of milling process and multi point flexible tooling clamping and positioning process of effective modeling, accurate definition of the finite element model of the material properties, contact method, constitutive model and separation criterion. The basic composition and working principle of the multi point flexible tooling system are introduced, and the principle of multi point positioning is analyzed. The milling process of aviation aluminum alloy 7050-T7451 is experimentally established to establish its milling mechanics model, which provides a basis for determining the number of supporting units of multi-point flexible tooling. Then, the finite element method is used to compare the advantages of the multi point flexible tooling to the traditional clamping, and the validity of the finite element model is verified. Then, using the method of finite element analysis of clamping force, supporting unit layout and supporting unit spacing on the deformation of the thin-walled parts with only gravity and clamping force; in the milling process of clamping force, supporting unit layout and supporting unit spacing the influence law of the machining deformation. The packing layout method which can effectively save time and resource occupancy rate is summarized. Finally, combined with the finite element technology, orthogonal experiment theory and multivariate nonlinear regression method, a prediction model for machining deformation based on the maximum deformation and average deformation of thin-walled components is put forward, taking the layout of supporting elements as design parameters. In order to simplify the calculation, the multi-objective prediction model is transformed into a single target prediction model by weighted method. Further, the single objective prediction model is taken as the objective function, and the genetic algorithm with strong global optimization ability is used to optimize the calculation.
【学位授予单位】：沈阳航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V261.23

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