Track-following-type friction-stir-welding device for pipeline and welding method

The invention discloses a track-following-type friction-stir-welding device for a pipeline and a welding method. The track-following-type friction-stir-welding device comprises a workbench used for supporting the to-be-welded pipeline; the workbench is provided with fixing devices fixing the to-be-welded pipeline; an upper shaft shoulder is arranged on the to-be-welded pipeline in a tightly attached mode; the bottom of the upper shaft shoulder is of a plane shape; a stir needle is arranged on the upper shaft shoulder; a lower shaft shoulder is arranged under a weld joint of the to-be-welded pipeline; the top of the lower shaft shoulder is of an arc shape matched with the to-be-welded pipeline; the lower shaft shoulder is mounted on a restraining sleeve; the restraining sleeve slides along a plane slide table; the stir needle sequentially penetrates through the upper shaft shoulder, the to-be-welded pipeline, the lower shaft shoulder and the restraining sleeve and is connected with the lower shaft shoulder through rotary devices; during welding, the stir needle and the upper shaft shoulder rotate at high speed, while the lower shaft shoulder does not rotate. According to the track-following-type friction-stir-welding device for the pipeline and the welding method, the function of cooling the weld joint is achieved by attaching the top of the lower shaft shoulder to the to-be-welded pipeline tightly, and the welding quality is improved.