带微孔的透平叶片的光学测绘方法

提出了一种获得透平叶片及其微孔CAD模型的光学测绘方法,首先,采用小视场的数字结构光三维扫描仪分块测量并拼接获得叶片点云;然后,在微孔中插入直径合适的高精度圆柱量规,测得量规点云,拼接到叶片轮廓上;最后,分别拟合叶片点云和量规点云为NURBS曲面和圆柱体曲面,圆柱体轴线与NURBS曲面交点即为微孔位置,圆柱体轴线方向即为微孔的法线方向,该方法采用传递测量对象的方式,测量芯棒而不是直接测量微孔;通过增加点云的采样密度,提高重建模型的精度和可靠性,测绘结果表明,叶片和量规的曲面模型的残差均为0.104 mm.

An Optical Mapping Method of Turbine Blade with Tiny Holes

An optical mapping method for acquiring CAD model of turbine blade and its tiny holes is proposed. Firstly, making use of Digital Structure Light (DSL) 3D scanner of small field of view, the multiple profile segments of the blade are measured and integrated into the whole profile through alignment. Secondly, some high accurate cylinder gauges of proper diameter are inserted into tiny holes and point cloud of gauges are measured and integrated into the blade profile. Finally, NURBS surface is fitted by point cloud of the blade and the cylinder surfaces are fitted by point cloud of gauges. The positions of tiny holes are intersections of cylinder axes and NURBS surface, and the normal orientations are cylinder axes. The method measures gauges rather than directly tiny holes through transferring measurement object. The high precision and reliability of the reconstruction model are reached by increasing sample density of measuring point cloud. The mapping result shows, the fitting error of NURBS surface and cylinder surface are both 0.104mm.