基于IGA理论的薄壁件侧铣加工变形预测关键技术研究
文献类型：学位论文
| 作者 | 普雄鹰 |
| 学位类别 | 博士 |
| 答辩日期 | 2011-04-09 |
| 授予单位 | 中国科学院沈阳自动化研究所 |
| 授予地点 | 中国科学院沈阳自动化研究所 |
| 导师 | 刘伟军 |
| 关键词 | 薄壁件侧铣加工 变形预测 铣削力 等几何分析 有限元分析 |
| 其他题名 | Key Technologies Research on Deformation Prediction of Thin-walled Components in Peripheral Milling Based-on IGA Theory |
| 学位专业 | 机械电子工程 |
| 中文摘要 | 随着材料科学和加工技术的飞速发展，航空航天制造业广泛采用高速铣削加工整体薄壁结构件，如航空发动机整体叶轮、飞机框架、壁板、翼肋等薄壁件。然而，这些薄壁结构件采用比强度高的难加工材料，在加工过程中，随着材料的去除，刚度降低，由切削力和残余应力引起变形、振动、刀具磨损等问题不仅严重影响了工件的加工精度和表面质量，而且增加了制造成本，薄壁件加工已成为制造业所面对的最突出的问题之一。因此，围绕低刚度零件侧铣加工变形开展研究工作，实现薄壁件侧铣加工变形预测和控制具有重大的理论意义和工程应用价值。本文以低刚度零件侧铣加工过程为研究对象，综合运用金属切削基本理论、自由曲线曲面理论、有限元法及新的数值方法——等几何分析 ( Isogeometric Analysis，简称IGA )，着重解决其中的一些关键技术问题，探索和建立低刚度零件侧铣加工变形预测的新方法，为复杂型面薄壁件加工变形控制提供新的技术支持。 一、等几何分析 ( IGA ) 理论框架。IGA理论是Thomas J. R. Hughes教授于2005年提出的使用NURBS单元替代传统Lagrange有限单元，应用等参变换的概念进行分析的新计算方法。通过深入探讨NURBS函数、NURBS几何体、细分方法等基础理论，然后从平面线弹性问题入手，建立了基于IGA理论的分析框架。 二、基于NURBS圆柱螺旋铣刀的铣削力理论模型。通过对经典金属正交切削、斜交切削及铣削力数学模型的深入研究，分析了直线刀具路径和圆弧刀具路径的真实刀刃运动轨迹的切屑厚度，提出了直纹面构建未变形切屑模型思想。首先针对圆柱螺旋铣刀的重要特征曲线——圆柱螺旋曲线，提出了一种满足精度要求的二次NURBS表示及逼近细分算法，然后以刀具-工件接触螺旋曲线以及切屑厚度螺旋曲线构建瞬时未变形切屑的NURBS直纹面模型，并以此为基础，建立了以NURBS切屑直纹面模型为基础的任意加工瞬态铣削力模型，并根据该铣削力模型，提出了铣削力系数标定的新方法。 三、圆柱螺旋铣刀变形预测。首先提出由满足精度要求的二次NURBS圆柱螺旋曲线的表示和构造的铣刀截面NURBS曲面模型，建立圆柱螺旋铣刀的NURBS实体三维模型，然后，根据三维实体线弹性理论，完成基于IGA理论的圆柱螺旋铣刀三维的受力变形预测分析。 四、加工过程中矩形薄板的NURBS实体三维模型。由于铣削加工过程比较复杂，工件几何形状及刚度随着刀具不断铣削而发生改变的特点，建立以矩形薄板加工过程的动态的几何模型是预测薄板加工变形的基础。建立矩形薄板单层铣削加工的单块NURBS三维模型以及需要多层铣削才能完成加工要求的多块NURBS三维模型，并且研究了多块NURBS三维模型刚度矩阵的计算方法。 五、半动态铣削加工过程IGA变形预测模型。研究单次铣削加工单块NURBS薄壁板的加工的过程，通过动态铣削载荷施加、去除材料后工件几何模型更新，建立半动态的铣削加工变形预测模型。通过该预测模型，可以预测薄板加工过程的变形情况，为控制变形提供依据。 |
| 索取号 | TG547/P97/2011 |
| 英文摘要 | With speedy development of the materials science and machining technology in recent years, many monolithic thin-walled structural parts were machining using high-speed cutting from a unique starting raw block in the aeronautic aerospace industries, such as aircraft engine whole impeller, airframe parts and wings. Due to using the good strength-weight ratio material of these work pieces, the rigidity is decreasing while the material is removing during milling process however, deflection and deformation induced by cutting force and residual stress, vibration effect and cutter wear influences significantly the accuracy and the surface quality of these work pieces and increasing cost. So, it has greatly academic and engineering value to predict machining deform of thin-walled work pieces. Targeting peripheral milling process of low rigidity components, this paper focuses on some of the related key techniques issues of machining distortion of thin-walled parts in order to research a new method of the prediction and controlling approaches of the cutting deflection in peripheral milling process, by synthesize using metal cutting principle, free curve and surface theory, the finite element method and a new computational method –Isogeometric analysis. 1、Isogeometric analysis framework. Isogeometric analysis (IGA) using volumetric NURBS elements rather than traditional Lagrange finite elements for analysis is a new computational method proposed by Prof. Thomas J. R. Hughes in 2005. It is investigated that the NURBS functions, NURBS geometry, refinement methods and IGA for linear elasticity firstly in the research, and established an IGA framework. 2、Milling forces model based on NURBS end milling cutter. Through studying orthogonal cutting force model, oblique cutting force model and mathematical model of traditional milling force, and analysis chip thickness of the trochoid and epicycloids trajectories of the cutter tooth, it is proposed that the undeformed chip model is represented by rule surface. It is presented firstly that an algorithm for approximation circular helix with quadratic NURBS for given tolerance. The chip thickness of NURBS ruled surface is represented by the cutter-work piece contact helix curve and thickness helix curve based on NURBS. It is proposed that milling force model of arbitrary instantaneous processing is represented by chip thickness model and the helix curve model based on NURBS and that new method of milling force coefficient calibration is based on the milling force model. 3、Cylindrical helical milling cutter deformation prediction. The end milling cutter entities model based on NURBS is represented by the cutter cross section NURBS surface and the NURBS helix curve. According to the three-dimensional linear elasticity theory, the end milling cutter deformation prediction model is established. 4、Rectangular thin plate NURBS entity model during milling processing. Peripheral milling processing is one of the most complex operations while work pieces geometric shapes change constantly in process. Modeling of process geometry is the basis for prediction machining distortion of thin-walled parts. It is proposed that the model of rectangular thin plate with a single patch and multiple patches NURBS entity are respectively using during the single cutting processing and multilayer milling processing to implement work piece geometric model changing dynamically in the processing. It is deliberated that the computing method of the stiffness matrix for multiple patches NURBS entity. 5、Semi-dynamic milling deformation forecast model based on IGA. It is proposed that the deformation forecast model based on IGA for a single patch NURBS thin-walled model during the single milling processing. The model is established by exerting dynamic milling force and changing dynamically work piece geometric models. Prediction of deformation of thin-walled plate during milling processing using the semi-dynamic forecast model can provide basis for controlling deformation to improve machining quality. |
| 语种 | 中文 |
| 公开日期 | 2012-07-27 |
| 产权排序 | 1 |
| 分类号 | TG547 |
| 源URL | [http://ir.sia.ac.cn/handle/173321/9297]  |
| 专题 | 沈阳自动化研究所_装备制造技术研究室 |
| 推荐引用方式 GB/T 7714 | 普雄鹰. 基于IGA理论的薄壁件侧铣加工变形预测关键技术研究[D]. 中国科学院沈阳自动化研究所. 中国科学院沈阳自动化研究所. 2011. |
入库方式： OAI收割
来源：沈阳自动化研究所
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