基于CCD图像处理技术的维氏硬度检测

Vickers Hardness Testing Based on CCD Image Processing Technology

设计了一种测量范围宽、精度高、可自动检测的维氏硬度计。该维氏硬度计主要由负荷加载系统、CCD光学成像系统和图像处理系统三个部分组成。其中,负荷加载系统可实现自动施加、保持、卸除试验力;CCD光学成像系统主要是对维氏压痕进行拍照。维氏压痕图像通过CCD光学成像系统进入图像处理系统。在图像处理系统中,对压痕图像采用阈值自适应算法求得最佳阈值,并对图像作二值化处理、边缘检测,最后用最小二乘法拟合压痕边缘的四条直线,由此计算出压痕图像的对角线长和被测材料的维氏硬度值。实验证明,该设计方案准确、可行,性能稳定可靠。

A Vickers hardness tester with wide measuring range, high precision and automatic detection is designed. The Vickers hardness tester mainly by the load loading system, CCD optical imaging system and image processing system composed of three parts. Among them, the load system can automatically apply, maintain, remove the test force; CCD optical imaging system is mainly on the Vickers indentation to take pictures. Vickers indentation image through the CCD optical imaging system into the image processing system. In the image processing system, threshold value adaptive algorithm is used to obtain the optimal threshold value, and the image is binarized and edge detected. Finally, the least squares method is used to fit the four straight lines of the indentation edge. The diagonal length of the indentation image and the Vickers hardness value of the tested material. Experiments show that the design is accurate and feasible, and the performance is stable and reliable.