About the author: He Yuan, technical consultant of China Machinery Manufacturing Technology Association, former deputy chief engineer of Dongfang Electric, production minister, chief craftsman, and person in charge of the Three Gorges Project, is now engaged in the supervision of hydropower units. The Three Gorges Project has attracted worldwide attention. The completion of the Three Gorges Project not only improved the flood control and navigation capacity of the Yangtze River, but also provided more clean energy for the country. It also promoted the optimization and innovation of process technology and the upgrading of machinery and equipment. As a veteran of the process front, I was fortunate enough to participate in the development and research of the Three Gorges unit. It also witnessed the rapid development of China's power generation equipment research and manufacturing capabilities, and the arduous process of optimization and innovation of mechanical process technology. The Three Gorges Project has improved the research and development capabilities of China's hydropower equipment The Three Gorges hydropower unit is the unit with the largest capacity, size, weight and manufacturing difficulty. In order to build the Three Gorges unit, the State Council Three Gorges Office (including the former State Council Major Office) and the China Machinery Industry Federation (including the former Ministry of Machinery Industry) organized domestic manufacturers, research institutes and institutions of higher learning to design the runners of the Three Gorges. The key technologies such as runner manufacturing and coil insulation have carried out scientific research and research, and have achieved a number of major scientific research achievements, and trained a large number of professional personnel, which laid a solid foundation for the technology transfer and production of the Three Gorges unit. Before the bidding for the Three Gorges unit, the State Council formulated the policy of “Technology and Trade Integration, Technology Transfer, Joint Design, and Cooperative Productionâ€, aiming to improve the research and development capabilities of domestic hydropower equipment by manufacturing the Three Gorges units. Since 2000, Dongfang Motor employees have made the Three Gorges Left Bank and the Three Gorges right bank units after hard work, and have been put into operation one after another. The unit manufacturing and operation quality has reached the international advanced level. Through the development of the Three Gorges unit, Dongfang Electric Co., Ltd. successfully developed a number of key technologies for hydraulic performance calculation, five-axis CNC machining, giant runner welding and machining, spindle narrow gap welding and water-cooled stator coil manufacturing. It also laid a solid foundation for the independent research and development of a million kilowatt giant hydropower unit. Lu Yanzhen, the former deputy director of the Ministry of Machinery Industry, has repeatedly stressed that the craftsmanship of fine products and fine products yields benefits; the core of revitalizing the equipment manufacturing industry is to strengthen the basic technology and adopt advanced manufacturing technologies. The manufacture of the Three Gorges unit has adopted many advanced process technologies, which has further optimized and innovated the process technology of power generation equipment, and advanced technology has promoted the upgrading of mechanical equipment. The old minister’s insights were once again witnessed in the manufacture of the Three Gorges unit. In 2003, Lu Yanxi (middle) went to East TV to inspect and wrote an inscription for "No Regrets Pursuit". The right one is the author of this article. Stainless steel refining technology Before the manufacture of the Three Gorges unit, the domestic castings factory used stainless steel castings such as crowns, lower rings and blades on the runners to be smelted by ordinary electric furnaces. The upper crown, lower ring and blade of the Three Gorges runner began to use the UOD or AOD method for smelting, which greatly improved the quality of these stainless steel castings. At present, China's one heavy, two heavy, Angang, Dazhong, sharing and other casting production enterprises are equipped with UOD or AOD furnaces, mastering the stainless steel refining technology, and the stainless steel refining capacity and technical level of the turbine runner castings are greatly improved. Blade five-axis CNC machining technology The previous rotor blades were sanded and tested using a prototype. The Three Gorges rotor blades are milled using a five-axis CNC bridge milling machine (see Figure 1). The photoelectric theodolite or coordinate measuring machine is used for inspection, which greatly improves the blade processing efficiency and measurement accuracy. At present, domestic hydropower equipment manufacturing enterprises have been equipped with five-axis CNC milling machines, and mastered the blade CNC machining technology. Domestic five-axis CNC milling machines have been manufactured by Shenyang Machine Tool Group, Beijing No. 1 Machine Tool Plant, Qiqihar No. 2 Machine Tool Plant and Guilin Machine Tool Plant. China's high-precision CNC machine tool manufacturing capabilities have been greatly improved. Blade strong grinding technology I remember that more than 20 years ago, Lu Yanxi said that China's large-scale hydropower and thermal power equipment technology has been greatly improved, but China's hydraulic and pneumatic components and other advanced components are still far from each other. In the past, we used bladed air-driven grinders to shovel the blades (see Figure 2). The quality of the shovel is not high and the efficiency is low. The blade of the Three Gorges is shoveled with a foreign advanced turbine-type pneumatic grinding machine. The blade shape is of good quality and the efficiency is greatly improved. After many years of research, Shanghai Jingpu Fengdong Tools Factory has successfully developed this type of turbine type pneumatic grinding machine. Runner welding technology In the past, the upper and lower rings of the runner were made of ordinary steel, and the blades were made of stainless steel, which were welded by austenitic welding rods. The crown, lower ring and blades of the Three Gorges runner are all made of stainless steel and welded with martensitic welding wire (see Figure 3). After the runner is welded, the qualified rate of one-time flaw detection is high, the residual stress of the weld is low, and the repair rate is low, reaching the international advanced level. At present, domestic hydropower equipment has adopted martensitic welding wire welding wheels, and many welding wire factories in China such as Harbin Welding Research Institute have been able to produce such welding wire. Solar Led Light,Led Solar String Lights,Led Solar Garden Lights,Solar Garden Light Top Lighting International (HK) Co., Limited , https://www.topled-group.com