为了实现高强钢薄板高温焊接条件下屈曲变形的准确测量, 基于数字图像处理技术、立体视觉原理及数字图像相关法, 提出一种高强钢薄板全场动态焊接变形的视觉测量技术, 并以规则散斑图像的高精度匹配方法研究为基础, 将其应用到焊接图像中。针对焊接高温导致的散斑纹理的变色或脱落, 采用高温漆与高温胶混合涂布的方式, 获得了低成本、高稳定性的散斑纹理。选择薄板背侧进行测量以及在相机镜头前加装滤光片组的方法, 抑制焊接过程中的强光、火花及烟雾的干扰。采用高斯平滑的数字图像处理技术, 寻找最佳滤波参数并应用到焊接图像中, 在保证测量精度的前提下提高了图像匹配的成功率及精度。实验结果表明, 该方法能够有效地降低焊接图像匹配的均值误差、均方根误差及Z向静态均值误差, 均值误差最大降幅为78.6%, 均方误差最大降幅为47.7%, Z向静态均值误差降幅为37.9%。本文的方法和系统可以满足焊接高温条件下薄板屈曲变形的全场应变测量要求, 散斑纹理稳定, 散斑图像匹配成功率高、稳定性好, 是薄板全场动态焊接变形检测的有效途径。

To accurately measure the buckling deformation of high-strength steel sheets under high-temperature welding conditions, a visual measurement technique for the full-field dynamic welding deformation of high-strength steel sheets was proposed based on digital image processing technology, the stereo vision principle, and the digital image correlation method. This process was applied to a welding image based on the study of the high-precision matching method of a plaque image. For the discoloration or shedding of the speckle texture caused by high-temperature welding, high-temperature paint and high-temperature glue were mixed and coated to obtain a low-cost, high-stability speckle texture. The measurement of the back side of the thin plate and the addition of a filter set in front of the camera lens suppressed the interference of glare, sparks, and smoke during the soldering process. Gaussian smooth digital image processing technology was used to find the optimal filtering parameters and apply them to the welding image, which improved the image matching success rate and matching accuracy under the premise of ensuring measurement accuracy. The experimental results show that the proposed method can effectively reduce the mean error, root mean square error, and Z-direction static mean error of the welded image. The maximum value of the mean error is 78.6% and the mean square error is 47.7%. The Z-direction static mean error was 37.9%. The method and system of this study can meet the full-field strain measurement requirements of the buckling deformation of thin plates under high-temperature welding conditions. The speckle texture is stable and the speckle image matching success rate is high, demonstrating adequate stability. This technique is an effective way to detect the whole field dynamic welding deformation of thin plates.