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Editor's note: the survey of China Machine Tool Industry Association shows that the machine tools needed for the manufacturing of nuclear power and wind power equipment are characterized by large specifications, large tonnage, high stiffness and high reliability. At present, compared with the requirements of nuclear power industry and wind power industry, there is still a certain gap in the reliability and stability of domestic machine tools

reliability is the lifeblood of nuclear power processing equipment

the equipment of nuclear power plant mainly includes three parts: Nuclear Island (primary circuit), conventional island (secondary circuit) and auxiliary equipment

the nuclear island is mainly composed of reactor core, steam generator, pressurizer and main pump. The reactor core includes pressure vessel, nuclear fuel rod bundle, drive mechanism and other components. Sometimes, this monofilament can be reserved or not. The island is composed of water pump, steam separator, steam turbine, generator, steam condenser, etc. In addition, there are auxiliary equipment to support the normal operation of the system and ensure the safety of the reactor. These are the main components of nuclear power plant equipment

the manufacturing of the main parts of these equipment can be divided into the following types, which require different machine tools and equipment for processing

large barrel components such as pressure vessel shell, steam generator shell and pressurizer shell basically belong to barrel components with heads at both ends, but their diameters and heights are different. The diameter of pressure vessel and steam generator depends on the size of generator set in nuclear power plant

at present, it mainly produces million KW nuclear power equipment. The diameter of the pressure vessel is 5 ~ 8m or more, the length is about 20m, and it is divided into 4 ~ 5 sections. It is welded, and the material is special steel. The blank is a cylindrical forging, which needs 10000 tons of press to forge and form. Subsequent machining requires Super Heavy CNC vertical lathe, Super Heavy CNC horizontal lathe, large boring bar multi axis linkage CNC boring and milling machine, CNC gantry boring and milling machine, five axis linkage turning and milling center, etc. These equipment have large specifications, and there are no special requirements for processing accuracy, spindle speed, rapid movement and other parameters. However, because these workpieces are expensive and there are no spare parts, the yield must be 100%, so there are high requirements for the reliability and stability of machine tools

a nuclear power plant needs more than 10 kinds of more than 200 pumps of various types, all of which belong to centrifugal pumps. Among them, the main pump (stage 1 pump) is a key component located in the heart of the nuclear island, which is the key to the control of water circulation in nuclear power operation. It belongs to the primary equipment of the nuclear power plant, and each steam generator has a main pump

the structure of the main pump in the nuclear island is not more complex than that of other pumps up to 68.2%, but it requires extremely high requirements and absolute reliability, (2) determine the yield limit of low carbon steel σ S and strength limit of cast iron σ B is the only equipment in the nuclear reactor that cannot be made in China at present, and it completely depends on imports, mainly because the main pump requires continuous operation for at least 30 years without any problems. The diameter of the main pump is about 2m and the height is 5 ~ 6m. Its main components are divided into two categories: pressure parts (including pump body, pump cover, main bolts, main nuts, etc.) and functional parts (including impeller, blade shaft, seals, etc.). At present, Shen Gu is jointly developing with Westinghouse, and the overall new design has not been completed. In addition to the 1-stage main pump, there are many 2-stage and 3-stage pumps. The names and functions of various pumps are different, but the principle is basically the same. For example, the containment spray pump is not used at ordinary times, but only used in case of failure. It is required to start within 6 seconds to cool down. The processing of these pumps basically includes turning, milling, boring, drilling, tapping and other processes

the equipment required for the processing of pump body and pump cover of pressure parts mainly includes large-scale CNC vertical lathe, CNC Floor milling and boring machine, gantry machining center and other equipment. The processing requirements of main bolts and nuts are higher than those of general bolts and nuts, but it is mainly about the selection of materials and tools

among the functional components, the equipment required for the processing of impeller and impeller shaft mainly includes five axis linkage machining center, CNC lathe, large CNC horizontal lathe, etc

the conventional island is mainly composed of steam turbine unit, generator unit, water pump, steam separator, etc. The principle and structure of nuclear power steam turbine are the same as that of thermal power (coal-fired) steam turbine. The difference lies in the steam turbine unit with the same power generation capacity. The diameter of nuclear power steam turbine is larger than that of thermal power steam turbine, which has foot healing effect. The materials used are also partially different, and the manufacturing requirements are higher. The main processing parts are blades, stators, rotors, etc. The main machining machines include 4-5 axis linkage machining centers of different models (the maximum blade length is more than 1600mm) for machining blades, CNC heavy-duty horizontal lathes and CNC blade root slot milling machines for machining rotors, CNC large-scale floor milling and boring machines, CNC gantry boring and milling machines for machining stators, large-scale special machine tools for stators, etc

for example, machining a 600000 kW steam turbine rotor weighing more than 200 tons requires a heavy sleeper with a rotation diameter of 3.5 ~ 5.0m and a length of 15 ~ 20m. Machining turbine blades requires a five axis linkage machining center. Machining medium pressure cylinders and high pressure cylinders requires CNC gantry boring and milling machines with a width of 7.5 ~ 8m and a length of 22m, Heavy CNC vertical lathes, and CNC Floor milling and boring machines with a boring bar diameter of 200 ~ 260mm. Generally speaking, machine tools that can meet the needs of thermal power steam turbine processing can basically meet the requirements of nuclear power steam turbine processing. Among these machine tools and equipment, most of the small and medium-sized blades are processed with 4-5 axis linkage machining centers and the rotor spindle is processed with CNC horizontal lathes, which can basically meet the requirements in China. However, CNC machine tools such as machining centers for large blades and CNC root slot milling machines mainly rely on imports

in addition, nuclear power generators are basically the same as thermal power generators, and their processing equipment is no different. In general, machine tools that can meet the processing needs of thermal power generators can basically meet the processing requirements of nuclear power generators. The main processing machines include CNC heavy-duty horizontal lathes for processing rotors, CNC rotor slot milling machines, CNC large-scale floor milling and boring machines for processing stators, large-scale special machine tools for stators, etc. At present, among these high-end CNC machine tools, some machine tools can meet domestic needs, but some machine tools and equipment such as CNC rotor slot milling machines still rely on imports

the accuracy of machine tools restricts the development of wind power equipment

wind power station equipment mainly includes the following parts: gearbox (speed-up box), generator set, blades, tower foundation and substation. At present, wind power generation is gradually developing towards high-power units, which requires high reliability and long life cycle, so the accuracy and function requirements of components are very high

with the development of wind power generation technology, the principle and structure of wind turbines are also changing, and the future wind turbines are developing in the direction of simplification of structure and reduction of volume. At present, China is developing gearless wind turbine. For example, the power generation equipment Engineering Research Center of Harbin power generation equipment group has developed gearless variable speed and pitch permanent magnet wind turbine, and is developing "variable speed constant frequency wind turbine" and "direct drive variable speed wind turbine", which can replace the asynchronous generator set with gearbox transmission. It has the advantages of low manufacturing cost, reliable operation, simple maintenance, and has independent intellectual property rights

at present, the largest production is the wind turbine with gearbox. Due to the complex structure, the manufacturing of various parts requires different machine tools and equipment for processing

the gearbox of the fan is mainly composed of box, planetary gear train and speed change mechanism. The fan gearbox belongs to a large box, with a diameter of about 2 ~ 3M according to the different power generation, and most of it is a split structure. Processing requires CNC Floor milling and boring machines with boring bar diameters of about 160250mm, large horizontal machining centers, gantry machining centers, etc., with high processing accuracy requirements. At present, imported equipment is mainly used

there is a large amount of gear processing in the gearbox, which requires mass production of large internal gear rings, cylindrical spur gears and helical gears. The main processing equipment is large-scale CNC vertical hobbing machine, CNC gear shaper, CNC gear grinder, etc. Among these gear processing machines, large-scale CNC gear machines are generally required to have the characteristics of high efficiency, heavy load, heavy cutting and good rigidity. They mainly rely on imports, and domestic equipment is used for small and medium-sized ones. Among them, large-size and large module gears and gear rings adopt CNC forming gear milling machine and CNC forming gear grinding machine. CNC forming gear milling machine requires large cutting depth, large feed and high rolling speed. CNC forming gear grinding machine requires accuracy of more than 5 levels, high degree of automation, automatic centering, automatic measurement, automatic shaping, and high stability. At present, Nanjing Gaojing Gear Co., Ltd. is the main manufacturer of wind power transmission in China. The production task of the factory is very busy, and the long-term three shifts still cannot fully meet the market demand. Therefore, the processing equipment is required to be stable and reliable. At present, the gear processing machine tools used by the factory are basically imported equipment

the principle and structure of wind power generator are basically the same as that of thermal power and other generators. Most wind power uses kilowatt level generators. Compared with the 10000 kilowatt level generators used in thermal power, they belong to different levels of units. From the perspective of manufacturing, it is not too difficult. Enterprises that can manufacture thermal power generating units can generally meet the requirements of manufacturing wind power generating units. However, the service life of wind turbine generator is required to reach more than 20 years, and its stability and reliability are required to be higher

the blades of fans are mostly made of composite materials such as epoxy glass fiber or carbon fiber. The blade design mainly adopts full three-dimensional aerodynamic simulation and structural finite element simulation, and uses vacuum pouring technology to produce blades. There is less machining, and some parts need punching and forming

the blade pitch mechanism mainly includes pitch motor, reducer and pitch controller. There are no special requirements for manufacturing equipment, and domestic machine tools can meet the demand

the main components of the yaw mechanism are large bearings with internal and external teeth, four pinion gears and speed change devices. This kind of large bearing cannot be manufactured in China at present, and mainly depends on imports. Domestic Tianma Co., Ltd. will develop and manufacture large bearings for yaw mechanism. Its processing equipment is mainly some special machine tools with high requirements. For example, at CCMT2008 exhibition, Qizhong CNC Equipment Co., Ltd. exhibited three large-scale CNC special machine tools, which are equipment for processing and manufacturing large wind power gears

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