刀具切削刃钝圆半径的图像测量法

摘要

为提高刀具切削刃钝圆半径的测量精度,提出了改进的边缘检测和刃口曲线计算方法,并用于三角形铣刀片的测量。在方向导数和梯度理论基础上改进现有边缘检测方法。首先定义包含边缘的感兴趣区域( Region of Interest, ROI),再以ROI边界像素的法线方向近似此法线方向上各像素的梯度方向。沿近似的梯度方向拟合灰度曲线并计算一阶导数极大值点,从而精确定位边缘点。参考刀具精确设计理论,以直线段和圆弧段刃口曲线相切作为约束条件,拟合圆弧段刃口曲线。结果表明,不加约束的切削刃钝圆半径测量误差为7%,加入约束的测量误差为0.5%。改进的刀具测量方法能准确定位边缘点,也能显著提高切削刃钝圆半径的测量精度。%For the purpose of improving the measuring accuracy of rounded cutting edge radius of cutting tool, modified edge detection and blade curve calculation methods were proposed and used to measure the triangle milling insert. Existing edge detection method was reformed based on directional derivative and gra-dient theories. Firstly, define the region of interest ( ROI) that contains edge. Then use the normal direction of each ROI boundary pixel as the approximated gradient direction for each pixel on this normal direction. Fit gray curve along the approximate gradient direction, calculate the maxima of first derivative, and accu-rately position the edge point. Reference theory of accurate designing of cutting tool;employ the tangent be-tween straight and arc blade curve as the constraint condition to fit the arc blade curve. The results show that the average measuring error of rounded cutting edge radius without constrain is 7%, and that with constrain is 0. 5%. Improved measuring method of cutting tool not only can accurately locate edge point, but also sig-nificantly improve the measuring accuracy of rounded cutting edge radius.