气膜孔通盲状态的视觉检测方法研究

Study on Vision Inspecting Method of Through or Blind State of Film Cooling Holes

在航空发动机中,气膜孔是决定涡轮叶片服役性能的关键几何特征之一,为实现其通盲状态的高效、准确检测,基于机器视觉与多轴运动控制原理研制了一套非接触式气膜孔五轴视觉检测平台,通过采集被测气膜孔的对焦图像序列并应用景深合成技术获取其全清晰图像,根据通孔和盲孔在光源照明下因底部漫反射状态不同而产生的孔内部区域的成像效果差异,再通过计算全清晰图像上孔内部圆形子区域内像素的平均灰度值,将其作为判据与所设定的阈值进行比对,从而完成被测气膜孔通盲状态的识别和判定。选取某型高压涡轮叶片试验件进行检测实验,验证了本文所提出检测方法的可行性和有效性。

In an aero engine,film cooling hole has become one of the key geometrical features that determine the service performance of turbine blades.To inspect the through or blind state of those film cooling holes in an accurate and rapid manner,a non-contact 5-axis vision inspecting system based on the principle of machine vision and multi-axis motion control is established in the paper.The panoramic image of the measured hole is derived through its focused image sequence by the focus stacking technology.And then,according to the differences in imaging effect due to the different diffuse reflection states of the bottom of hole under the illumination of light source,the average pixel grayscale of a circular sub region in the panoramic image is selected as the criterion to be compared with the threshold,in which the result could be used to recognize and determine the through or blind state of film cooling hole.A test piece of high pressure turbine blade is selected to be tested,which verified the inspecting method proposed in the paper.