The project belongs to the science and technology field: materials and advanced manufacturing.  At present, the demand for large-diameter aluminum alloy pipes in my country is growing at an average annual rate of 10-12%. In the civil field, with the proposal of green transmission of national power, gas-insulated metal-enclosed transmission technology (GIL technology) has become a global trend to replace high-altitude towers for erecting high-voltage electricity. The "China's Industrial Structure Adjustment Catalog" and the "ldquo; 12th Five-Year Plan; Major Industrial Technology Development Special Plan" have included GIL in my country's ultra-high voltage power transmission and transformation complete equipment manufacturing projects. The main part of GIL is large-diameter aluminum alloy pipes. In addition, large-diameter aluminum alloy pipes are also used in tank trucks for liquid storage and transportation. In the military field, the demand for rocket tanks and missile tanks is increasing year by year, but cost constraints are imminent. At present, large-diameter aluminum alloy pipes for military and civilian use are obtained through circumferential seam plus longitudinal seam welding or spiral welding processes, which has manufacturing bottlenecks such as low efficiency, poor quality and high cost. For a long time, my country's aluminum alloy pipe manufacturing equipment, process and production model have significantly lagged behind those of European and American powers, seriously restricting the efficient, high-quality and low-cost mass production of my country's large-diameter aluminum alloy pipes.  Under the background of the official establishment of the State Grid Sutong GIL Pipe Corridor Project and the support of the independent research and development project of Shanghai Aerospace Equipment Manufacturing Factory Co., Ltd., our team developed the friction stir welding process and equipment for large-diameter aluminum alloy spiral pipes, effectively solving the problem. The problems of primary aluminum alloy fusion welded spiral pipes are easy to exceed the diameter, high welding defect rate, and low welding efficiency.  1. The country's first double-sided friction stir welding double-sided spiral forming process for large-diameter aluminum alloy pipes, which solves the comprehensive control problems of spiral forming process, friction stir welding process, and weld splicing accuracy in the manufacturing process of aluminum alloy pipes. A complete set of automatic processing equipment for friction stir welding of large-diameter aluminum alloy pipes has realized efficient, high-quality, low-cost green manufacturing technology for large-diameter aluminum alloy pipes, and the manufacturing efficiency has been improved by four times. The weld strength reaches more than 90% of the strength of the base material, the cost is reduced by 40%, and the production process achieves smoke-free, flash-free and noise-free green manufacturing.  2. Develop unconstrained, line-contact, and dynamic rigid support technology, which solves the problem of dynamic back support during the double-sided friction stir welding of large-diameter aluminum alloy pipes, and truly realizes uninterrupted and continuous friction stir welding of the spatial spiral curve.  3. Invented a friction stir welding device with double-sided welding and double-sided forming, which solved the technical problems of small space, high load bearing, multifunctional and high-precision welding of aluminum alloy spiral welds, and realized the continuous welding of phi;600mm aluminum alloy pipes.  4. The equipment has been successfully applied to the manufacturing of GIL pipes. The large-diameter aluminum alloy pipes manufactured by it have passed the UHV Department of the State Grid in terms of aluminum pipe shape and position error, weld quality, pressure bearing capacity, surface roughness, welding efficiency, etc., and determined that various indicators meet the GIL pipe manufacturing technical requirements and production capacity requirements of the Sutong Pipe Corridor Project.  5. Obtained 1 PCT patent for international inventions in the EU; 3 authorized invention patents, 12 disclosed; 6 utility model patents; and 2 published papers.  6. The results were applied to the manufacturing of GIL pipes in the State Grid Sutong Pipe Corridor Project, realizing green, efficient, energy-saving, high-quality and high-reliability manufacturing of large-diameter aluminum alloy pipes, and successfully applied to the State Grid Wuhan UHV Base., in the past three years, the unit's new output value was 36.5 million yuan and the new profit was 9.2 million yuan.