基于激光测量的航发叶片表面几何缺陷识别技术

Identification of Aero-engine Blade Surface Geometric Defects With Laser Measurement

针对航发叶片修复检测的应用,提出了一种基于截面线一阶导矢法的叶片型面缺陷识别方法.该方法是以等高线法处理测量点云中的截面数据,通过B样条插值函数拟合成光滑曲线;再由B样条曲线的一阶导矢公式求出每个测点的一阶导数,然后以点斜公式求出截面曲线上各个测点的切线;如果曲线光滑,曲线上测点的斜率变化在两端点斜率值之间,否则表明曲线上有缺陷存在;根据k-d树的最近点搜索算法,遍历整个叶盆(叶背)就可以找到叶盆(叶背)上的缺陷区域.通过与三坐标测量实验比对,该技术可以实现3μm精度的缺陷识别.

Aimed at aero-engine blade repair detection,a method of blade surface defect identification based on the first-order cross-sectional guideline method is proposed.In this method,the cross-section data of the measurement point cloud is processed by the contour line method and the smooth curve is fitted by the B-spline interpolation function.The first-order derivative of each measuring point is obtained by the first-order derivative formula of the B-spline curve.If the curve is smooth,the slope of the measuring point on the curve changes between the slope values of the two endpoints,otherwise it indicates that there are defects in the curve.According to the nearest k-d tree point search algorithm,traversing the entire blade pot(blade back)can find the blade pot(blade back)on the defect area.By comparing with the three-coordinate measurement experiment,the technology can realize the defect identification with a 3μm precision.