论文总字数：37703字

摘 要

针对航空发动机叶片这类复杂曲面零件，其毛坯件存在着加工余量差异性大、余量分布不均匀的特点。在成品铣削或磨抛等精加工前需要测量毛坯三维模型，并以此为依据规划刀具路径。传统的接触式测量方法存在着测量设备成本花费高，单次测量耗时长等缺陷，不能达到很好的测量效果。针对以上问题，本文以叶片类复杂曲面零件为主导，采用线激光测量仪为工具的非接触式测量方法，结合点云处理软件，实现了从复杂曲面零件的测量、点云数据处理到加工刀具路径规划的一个完整过程。本文主要研究内容包括:

1. 研究分析了线激光测量仪的测量原理，并借助线激光测量仪和带有编码器的直线导轨与转台搭建了叶片类复杂曲面零件非接触式光学测量平台。通过测量平台，采集了叶片各个面的点云数据，同时完成了点云数据的格式转换。
2. 对线激光测量仪采集到的多片点云数据采用n点注册和迭代最近点算法进行拼接，得到了叶片的三维点云模型。接着利用体素化网格方法和统计分析方法分别对叶片三维点云模型进行降采样和滤波处理。最后基于主成分分析法和贪婪投影三角化算法分别对叶片三维点云模型进行了表面法线估计和曲面重建，同时对重建后的曲面模型进行了修复与优化。
3. 结合最佳拟合对齐与3-2-1对齐的方法拟定叶片类复杂曲面零件的点云配准流程，将叶片点云模型与其对应的设计CAD模型进行配准来获取到叶片的加工余量。接着采用传统境界拟合与截面轮廓拟合相结合的方式，将叶片的曲面模型逆向重构为实体模型。最后利用UG二次开发平台结合叶片实体模型，完成了叶片磨抛加工的刀具路径规划与仿真软件开发。

关键词：叶片类曲面零件；线激光测量仪；三维点云；点云数据处理；刀具路径规划

Abstract

Aiming at complex curved parts like aero engine blades, the rough parts have the characteristics of large difference in machining allowance and uneven distribution of allowance. Before finishing finished products such as milling or grinding and polishing, it is necessary to measure the three-dimensional model of the blank and plan the tool path based on this. The traditional contact measurement method has the defects of high cost of measurement equipment and long time for single measurement, which cannot achieve a good measurement effect. In view of the above problems, this paper takes blade-like complex curved surface parts as the dominant, non-contact measurement method using line laser measuring instrument as the tool, combined with point cloud processing software, to achieve from the measurement of complex curved surface parts, point cloud data processing to processing tools A complete process of path planning. The main research contents of this article include:

(1) Firstly, the research and analysis of the measuring principle of the line laser measuring instrument, and the use of line laser measuring instrument and the linear guide with encoder and turntable to build a non-contact optical measuring platform for blade-like complex curved parts. Through the measurement platform, the point cloud data of each surface of the blade was collected, and the format conversion of the point cloud data was completed.

(2) Multiple point cloud data collected by the line laser measuring instrument are spliced using n-point registration and iterative closest point algorithm to obtain a three-dimensional point cloud model of the blade. Then, the voxel grid method and statistical analysis method are used to down-sample and filter the three-dimensional blade cloud model. Finally, based on the principal component analysis method and the greedy projection triangulation algorithm, the surface normal estimation and surface reconstruction of the blade 3D point cloud model were carried out, and the reconstructed surface model was repaired and optimized.

(3) Combining the method of best-fit alignment and 3-2-1 alignment, a point cloud registration process for blade-like complex curved surface parts is prepared, and the blade point cloud model and its corresponding design CAD model are registered to obtain the machining allowance of the blade . Then, the traditional boundary fitting and section contour fitting are combined to reversely reconstruct the surface model of the blade into a solid model. Finally, using the UG secondary development platform combined with the blade solid model, the tool path planning and simulation software development of blade grinding and polishing processing were completed.

Key Words：blade type curved parts; line laser displacement sensor; 3D point cloud; point cloud data processing; tool path planning

目 录

摘 要 I

Abstract II

第1章 绪论 1

1.1研究背景与选题意义 1

1.2国内外研究现状概况 2

1.2.1复杂曲面零件测量方法 2

1.2.2点云数据处理方法 3

1.2.3叶片磨抛刀路规划及仿真软件开发 3

1.3本文主要研究内容和论述框架 4

第2章 叶片点云数据的采集与转换 6

2.1线激光测量仪 6

2.2测量平台的搭建 7

2.3叶片点云的采集流程与格式的转换 7

2.4本章小结 9

第3章 叶片点云数据处理 10

3.1 叶片点云的拼接 10

3.1.1迭代最近点(ICP)算法 10

3.1.2 叶片点云拼接流程 11

3.1.3叶片点云拼接结果和精度分析 12

3.2 叶片点云数据降采样 12

3.2.1体素化网格方法 13

3.2.2叶片点云降采样结果分析 13

3.3叶片点云数据滤波去噪 14

3.3.1基于统计分析的去噪方法 14

3.3.2叶片点云去噪结果分析 14

3.4叶片点云表面法线估计 15

3.4.1点云法线主成分分析方法 16

3.4.2 叶片点云法线估计结果 17

3.5叶片点云曲面重建 17

3.5.1贪婪投影三角化算法 17

3.5.2叶片点云三角化结果与分析 18

3.5.3叶片三角化曲面修复与优化 19

3.6叶片三维点云模型与CAD模型配准分析 21

3.6.1 Geomagic qualify软件简介 21

3.6.1叶片三维点云模型与CAD模型配准流程 21

3.6.2偏差分析与加工余量的获取 22

3.7本章小结 24

第4章 叶片磨抛刀具路径规划与仿真软件开发 26

4.1叶片点云三维重构 26

4.1.1Geomagic DesignX软件简介 26

4.1.2叶片点云三维重构流程与结果分析 27

4.2叶片砂带磨抛路径规划 29

4.2.1加工步长的计算 29

4.2.2加工行距的计算与转换 30

4.2.3接触轮刀位点计算 32

4.2.4后置处理 33

4.3砂带磨抛路径规划软件设计 34

4.3.1UG二次开发平台 34

4.3.2叶片模型导入 35

4.3.3叶片边界分析 35

4.3.4加工区域分割 36

4.3.5刀具路径规划 37

4.3.6接触轮刀位点与机器人位姿导出 38

4.4本章小结 39

第5章 总结与展望 40

5.1全文总结 40

5.2展望 41

参考文献 42

致谢 44

第1章 绪论

1.1研究背景与选题意义

复杂曲面零件作为许多高精尖装置的零部件之一，由于该类零件空间形状复杂，精度要求高，其加工制造过程面临十分严峻的挑战。叶片是航空发动机的“心脏”，其结构从叶根到叶冠存在着一个渐变的扭转角与弯曲角，从而导致其各型面都为空间自由曲面，是典型的复杂曲面零件之一，如图1-1所示。当航空发动机运转时，叶片在高温高压的气体包围下，工况极为恶劣，会受到各种复杂应力的联合作用^[1]。为了保证叶片工作的可靠性，通常其结构材料主要采用钛合金、高温合金等难加工材料。

(a)单个叶片 (b)装配叶片

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