球面栅网几何要素的精密测量

Precision measurement of spherical grid geometrical features

为了实现球面栅网零件几何要素的精密测量,快速筛选出满足电子光学设计要求的合格零件。对测量设备与附件的特点、零件的设计要求、加工工艺带来的常见超差问题进行研究。根据零件的测量要素,从测量效率和精度的角度考虑,选择了加装激光辅助对焦系统的影像测量仪。编写了自动测量程序,自动将粗定位定向转为精准定位定向,完成了零件全部几何要素的自动测量。针对“大半径、小圆弧”的测量难点,进行了量化分析和计算,得出了曲率半径测量结果不确定度的计算公式。最后,讨论了测量不确定度的来源,提出了抑制各误差源的方法。实际应用时,利用上述影像仪完成了栅网零件的曲率半径SR、栅网球面的面轮廓度、环向栅丝同心度、径向栅丝圆分度α、全部栅丝宽度WR和WC、端面外径及其圆度、端面平面度的自动精密测量。测量时间约为传统方式的2/3,测点数量达2094个,远高于手动测量方式。

This study aimed to achieve precise measurements for spherical grid geometrical features and screen the qualified parts for electron optical design requirements.Thus,the characteristics of the measuring equipment,its accessories,grid size design requirements,and common overproof problems caused by processing were studied.First,the optical measuring machine with a laser-assisted focusing system was selected,owing to its grid measurement features,efficiency,and accuracy.Then,an automatic measurement program was compiled,which automatically turned the coarse zero and orientation to the precise values and completed the automatic measurement of all the spherical grid geometrical features.Subsequently,in view of the‘big radius,small arc’measurement difficulty,quantitative analysis and calculations were performed to obtain the formula for the uncertainty of the curvature radius measurement.Finally,the sources of measurement uncertainty were discussed,and the methods for eliminating error sources were analyzed.In a practical application,the automatic and precise measurements of the spherical grid curvature radius,profile of the grid's spherical surface,circular grating wire concentricity,radial grating wire circle indexing,grating wire widths,outer diameter and its roundness,and the end surface flatness have been achieved.The measurement duration was approximately two thirds of the traditional method,and the number of measuring points was up to 2094,which is considerably larger than the hand-operated method.