基于CAD模型的自由曲面检测方法

针对自由曲面的设计和加工特点，提出了采用点接触式三坐标测量机对自由曲面进行检测时，数学模型的建立方法，指出检测点数量的确定不仅与加工设备的精度和检测的置信度有关，而且还与自由曲面的面积大小有关，检测点的分布则应综合考虑曲面的曲率变化情况和曲面形状对测量网格的制约关系。由于非均匀有理B样条方法表达曲面的独特性，对复杂自由曲面应采取分片测量和评价的方法，同时在几何量测量中采用优化搜索的方法确定最小不合格区域，便于后续的分析和处理。

CAD-based Inspection of Free-form Surfaces

According to the traits of free-form surfaces designed and machined, a mathematical model is presented to guide the measurement using coordinate measuring machine(CMM). It is pointed that determining the number of the measured points is not only determined by the precision of the machining tool and the confidence of the inspection, but by the area of the free-form surface. The distribution of the measured points on the inspected surface is otherwise relevant to the changes of the curvature and the shape of the surface of interest. On the basis of NURBS model the complex surfaces are inspected and identified respectively, and an optimum method is also presented to search and determine the smallest area with unexpected error, in order to facilitate following procedures.