Steel bars, steel rods, etc. need to be marked or welded when entering and leaving the warehouse, the steel plant noise, work intensity, high labour costs, the customer introduces the robot marking machine to achieve automation upgrading. Round steel bundles of different shapes, the depth of a single round steel is not the same, in place position is not certain, through the positioning of the 3D vision system, the most prominent or the most central is usually selected for the welding of labels, and at the same time can be realized whether the welding in place of visual re-checking, the overall work efficiency is highly efficient, the reliability of the vision system for continuous production of up to 99.9% or more.