带公差约束的数字样板叶型检测方法

Inspection Method of Blade Shape Based on Digitized Template with Design Tolerance Constraints

针对航空发动机叶片三坐标测量机(CMM)测量过程中误差检测与评定的问题,提出了一种带公差约束的数字样板叶型检测方法,以实现叶型误差的快速准确评定。在实物样板检测原理的基础上,分析叶型偏移、扭转与轮廓度之间的耦合关系,建立公差约束条件。根据CAD设计模型构造数字样板,建立带公差约束的样板匹配数学模型,并利用拟牛顿法进行非线性优化求解,在设计公差的约束条件下实现叶片测量点与数字样板的精确匹配。最后通过对某叶片型面测量数据进行仿真分析和实例验证,表明该方法比最小二乘(LSQ)方法的误差评定结果更为精确可靠,且与实物样板检测结果一致。

To deal with the error evaluation and inspection of aero-engine blade airfoils using coordinate measuring machine （GMM）, a new inspection method of digitized template considering design tolerances is proposed for cross-sectional error evaluation with high precision and rapid speed. Based on the principle of certified reference template inspection, the compli- cated relationship among three kinds of tolerances is discussed and the constraints are established. In addition, a digitized template is constructed according to the CAD design model, and then a mathematical matching model with tolerance con- straints is built to accomplish precise matching between the measurement points and digitized template. In order to obtain the solution of the model, an algorithm of quasi-Newton method is applied for precise matching, Simulation test and practical ex- ample prove that the proposed method is more precise and reliable than the least squares （LSQ） method and the result coin- cides with that from the certified reference template inspection well.