Abstract: Measuring three dimensional(3D) weld pool surface of tungsten inert gas arc welding(TIG) has significance for investigating coupled mechanism between welding arc and weld pool, control of weld formation and weld joint penetration. However, the influence of strong arc light and the specular reflection of weld pool surface make the existed methods hardly applied to 3D measurement. To this end, a new sensing method is proposed, which utilizes the reflected property of weld pool surface. The mapping model between reflected and projected laser dots is analyzed and established. A new 3D reconstructed algorithm is proposed based on the renewed projected laser dots and the 3D TIG weld pool surface is achieved, also its geometry parameters, i.e., width and average height are extracted. Compared the measurement shows that the proposed method can measure the dynamical variation of weld pool surface, but also the reconstructed result coincides with the measurement well. The error of weld pool’s width and height is 1.73% and 2.32%, respectively. To better investigate the evolution rule of TIG weld pool specular surface provides a new method.

Key words: laser dot-matrix, specular reflection, three-dimensional measurement, weld pool free surface