Application of electron beam welding in turbine manufacturing
In the gas turbine section, the electron beam or friction welded joint of the disc shaft is the simplest non-detachable structure with no connecting parts in the middle and the lightest weight. However, since the turbine part is a bearing rotating part, there is a large torsional load during the working process, and the welding must ensure the concentricity and the runout requirement of the disc shaft, so the quality requirements of the welded joint are very demanding. In China, the electron beam welding process is used in the engine of a certain type of target machine, and the turbine shaft of the 1Cr11Ni2W2MoV material and the precision casting blade of the K418 material are welded together. In the production process of a low-pressure turbine shaft of a certain type of machine, the shaft of GQGH4169 material was also connected by electron beam welding. The use of welded structural parts reduces the machining difficulty compared to the integral parts, while saving materials and economical. Foreign countries have adopted electron beam welding structures in the high-pressure turbine section of engines such as the RB199. For the disc-welded structure, the influence of the welded joints of different materials under various working conditions must be considered. The position of the welded joint should be placed at a position where the stress is small and the wall thickness is thin.
In the manufacturing process of the turbine guide vane, the guide vane is surrounded by high temperature gas, in addition to large aerodynamic force and unstable pulsating load, the temperature is high, the heat and cold change is large, and the temperature unevenness is serious. Thermal shock and thermal fatigue are one of the main causes of blade failure. Therefore, the guide vanes are generally made of a single or two-leaf, three-blade set for easy assembly, positioning and tolerance control, and are easily replaced after damage. The material of the guide vane is cast superalloy, the material is expensive, the material of the material is very hard, and the precision casting is used. In order to enhance the cooling effect of the blade and improve the work quality, the hollow blade is generally made. On the TAY and WS9 engines, the high-pressure turbine guide vanes are all three-leaf group structures that are electron beam welded. The butt welding of the blade edge plate is a typical variable section welding. The thickness of the welding varies from 2 to 12 mm. It is necessary to complete the welding by the same parameters at one time, and the weld is required to be grade III. Crack defects are easily generated in the blade weld, especially After working on the engine for a period of time, the generation of cracks is related to the high content of Al, Ti and impurity elements in the material. In order to further improve the operating temperature of the engine's turbine, modern advanced engines have adopted many new materials that withstand higher temperatures. For example, the Ni3Al-based IC10 material used in a certain machine is a directional crystallized turbine guide vane with an operating temperature of 1100 °C. , by T LP diffusion welding into a two-leaf group. This material is susceptible to weld cracking by fusion welding.
Application of Electron Beam Welding in the Manufacturing of Combustion Chamber
Electron beam welding has gained more applications in the manufacturing process of engine combustion chambers. The combustion chamber components are the components that are subjected to the greatest thermal load in the engine and are light in weight. Combustion chamber components are prone to failure and endanger themselves and other components. Therefore, the manufacturing quality of the components of the combustion chamber is required to be high. In the manufacture of the combustion chamber casing, the mounting edge and the sheet metal part are welded by an electron beam welding process, which greatly saves material. The modern engine mostly adopts the annular combustion chamber structure, and the internal and external casings of the combustion chamber adopt electron beam welding structure, generally GH4169 material, mostly thin-walled parts, and the weld quality ensures the quality of the weld meets the Class I requirements of the acceptance standard. Electron beam welding completes the connection of the combustion unit casing, the pre-diffuser and the internal casing. In the production of a machine casing, electron beam welding of GH141 material is involved, and microcracks are found in the welded joint area after welding. In view of this situation, the analysis determines that it is strain aging crack, aging treatment of GH141 material before welding, and starting from the welding process, tooling and other aspects, control the post-weld stress and solve the welding crack problem. A large number of electron beam welding processes have been used in the manufacture of flame tubes. The welding of the outer wall to the head and the cap is achieved. For structural reasons, electron beam welding should control the welding heat input and prevent the deformation of the parts. According to the specific structure of the parts, in some cases, a non-penetrating welding process must be adopted to prevent the spatter and welding of the welding process from being used on the engine. Make an impact.
Application of electron beam welding in the manufacture of other components
The hydraulic actuator adjusts the size of the nozzle of the tail nozzle on the engine and is a key component on the engine. In the manufacturing process of a hydraulic cylinder of a machine, a rubber sealing ring is arranged on the piston, and the cover and the liner are connected by electron beam welding. Due to the small wall thickness of the hydraulic actuator, the welding deformation must be strictly controlled during the welding process to ensure the free reciprocating motion of the piston in the cylinder; during the welding process, the temperature rise of the part must be small to ensure the welding heat cycle on the piston. The quality of the sealing ring has no effect; in addition, there is no welding spatter in the cylinder in the case of ensuring that the effective welding section is completely penetrated, which must be solved from the design of the welded joint. In the welding process of the hydraulic actuator, it is necessary to select a small welding heat input amount, a partial penetration process and a method of taking away the welding heat by using a copper chilling block.
In the manufacture of engine transmission gears, the electron beam welding method is used to weld the gear ring and the gear shaft, which solves the problem of gear shaping and grinding during the gear shaft machining process. During the welding of the gear shaft, the shaft and the toothed ring are assembled by interference. The air hole is the most easy defect in the weld, the thickness of the welding substrate is increased, and the air groove is opened, and the air hole generated by the welding is as deep as possible. It is introduced into the substrate and removed after welding, which can solve the pore defects well. In addition, the gears on the back of the welded joint should be protected against damage from welding residual electron beams. The transmission gear of a 12Cr2N i4A material welded by this method, the weld quality meets the requirements of the acceptance criteria, and the size and runout of the gear shaft after welding conform to the design drawing.
Conclusion
With the needs of aircraft engine research and production, Xi'an Aero Engine Company has introduced three imported CNC high-pressure vacuum electron beam welding machines in recent years. The vacuum chambers are 1.5m 3 , 5.5m 3 and 36m 3 , and the original one is 0.7. The m 3 German-made electron beam welder was extensively modified. The company is responsible for the heavy-duty aircraft engine research and production and batch production tasks, mainly including the first, second and third stage fan casings, a variety of high and low pressure compressor rotors, high pressure turbines, combustion chambers, flame tube components, etc., about 180 The various parts involve many materials such as stainless steel, high-temperature alloy and titanium alloy. The quality of the welding products is stable, which satisfies the needs of the troops. There is no welding quality problem in the test. It has overcome many technical problems such as the hole problem of electron beam welding of titanium alloy materials and the crack problem after welding of GH14 material. The welding technology is strong, which lays a solid foundation for the development and batch production of large military and civilian aircraft engines in China.
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