一种复杂曲面的精密测量逆向与误差评定方法

A Method of Precision Measurement,Reverse and Error Evaluation for Complex Curved Surface

目的研究叶片类零件精密测量、逆向与误差评定方法,为该类零件的精密加工提供数字化误差分布模型。方法针对接触式测头存在的空间径向偏置问题,基于四点标定法,建立空间数学模型,完成工具中心点(TCP)的标定;针对叶片点云分布散乱、无序等问题,提出基于多级B样条插值方法,进行叶片三维点云的曲面重建;最后基于迭代法,对叶片误差进行精确评定。结果对测量所得叶片点云,基于多级B样条与控制网格差异化细分的重建算法可以重建出高保真的连续曲面;误差评定算法可以完成测量结果与设计模型之间不小于0.01 mm的误差计算并得到分层分区的误差可视化云图。结论机器人接触式测量系统可以对叶片类复杂曲面完成高精度测量,采用基于B样条的三维重建算法可以快速的重建出叶片三维曲面;笔者提出的误差评定算法可以进行高精度叶片点云的误差计算,其分层分区结果对于叶片抛磨精加工阶段具有指导意义。

To study the precision measurement,reverse engineering,and error evaluation methods of blade-like components,and to provide a digital error distribution model for the precision machining of such components,a space mathematical model was established to address the spatial radial bias issue of contact probes based on the four-point calibration method,which was used to calibrate the tool center point(TCP).For the scattered and unordered distribution of blade point clouds,a multi-level B-spline interpolation method was proposed for the surface reconstruction of the 3D blade point clouds.Finally,an iterative method was employed to accurately evaluate the blade errors.For the measured blade point clouds,the reconstruction algorithm based on multi-level B-splines and control grid differentiated subdivision can create high-fidelity continuous surfaces;the error evaluation algorithm can calculate errors between the measurement results and the design model no less than 0.01 mm and obtain a stratified and zoned error visualization cloud map.The robotic contact measurement system can achieve high-precision measurement of complex blade surfaces.The 3D reconstruction algorithm based on B-splines can quickly reconstruct the 3D blade surfaces.The error evaluation method proposed by the authors can calculate the errors in high-precision blade point clouds,and the stratified and zoned results have clear guiding significance for the polishing and precision machining stages of the blades.The feasibility and effectiveness of the proposed methods are demonstrated through theoretical analysis and final experimental results.