The self aligned tank welding roller is a displacement device that utilizes the friction between the active roller and the weldment to drive the workpiece to rotate. The swing angle of the wheel set can be automatically adjusted according to the diameter of the workpiece, and the core can be automatically adjusted. It is mainly used for the assembly or welding of cylindrical workpieces such as pipes, vessels, boilers, oil tanks, etc. When it is matched with welding operation machine and welding power source, it can realize the inner and outer longitudinal joints of the workpiece and the inner and outer circumferential seam welding. This product fully absorbs the advantages of similar products at home and abroad, and has the advantages of advanced technology, reliable quality, simple operation, low transmission noise and stable workpiece rotation. It is an essential equipment for automatic and semi-automatic welding of pressure vessels and cylindrical workpieces. The self-adjusting roller frame roller drive adopts electromagnetic speed-regulating motor, which can be steplessly regulated according to the welding specification. It has the characteristics of wide welding speed regulation range, good rotation smoothness and low-speed characteristics. When the heights of the main and driven rollers are properly adjusted, the assembly and welding of the cone and the segmented unequal-angle rotor can also be performed. For some non-circular long weldments, if they are stuck in a special annular clamp, the welding can be carried out on the welding roller frame. In particular, the self-adjusting and adjustable welding roller frame series adopts a unique digital adjustment and display technology for the selection of the roller speed. The welding speed setting is not only intuitive and accurate, but also reduces the operator's operation difficulty.