Tower crane large-tonnage support welding project. This welding workstation adopts the method of two-axis position shifter and dual robot welding at the same time for tower crane support welding. The double robot welding form is the sky rail gantry structure (X/Y/Z three-axis) + cantilever structure (X/Z/ rotation axis), all axes are the external axis of the robot, which can be welded with the robot, and the two machines can be independently or jointly linked with the positioner. A two-layer platform is set up in the gantry, which is used to astore items such as welding power supply wire bucket, so as to facilitate personnel inspection and maintenance.