Precision Casting Technology and Development Trend of Superalloy
Precision Casting Technology and Development Trend of Superalloy
casting technology is a ancient old and traditional technology. In the aviation industry, all kinds of superalloys, titanium alloy the casting technology of aluminum alloy complex thin-walled integral components is widely used and is one of the key manufacturing technologies in the aviation industry.
The distinctive feature of casting is that the size, structure and performance of forming components are controlled by the casting process and the forming process. On the basis of traditional theories and methods, casting technology is combined with automatic control, computer simulation and other technologies to develop in the direction of theoretical guidance, process control and overall net forming.
In the aviation industry, complex thin-walled superalloys, titanium alloy, Aluminum alloy integral castings are key components in aircraft engines and airframes. The shape, size, structure and performance of these components directly affect the performance, structural weight coefficient, life and manufacturing costs and other important indicators. Therefore, casting technology is an important technical basis for the development of aviation equipment and civil aviation products in the direction of lightweight, chemical, long life and low cost.
Research and Application of Casting Technology in Aviation Industry
developed industries in Europe and the United States have comprehensively applied modern new materials, and on the basis of enriching the basic theory of forming, they have continuously studied and new process technologies to control the difficult-to-control forming process of casting, developed a large number of complex and integral components, which are widely used in aviation equipment to improve the overall structural performance and performance of components, reduce structural weight, reduce manufacturing costs, and shorten manufacturing cycles, to meet the needs of the development, production and development of aviation equipment.
1 High Temperature Alloy Casting Technology
high-temperature alloy casting technology is mainly used in the manufacture of key hot-end components of aero engines, such as aero engine blades, integral turbine discs, and, integral receiver etc.1970s, the United States, Britain, the Soviet Union and other developed successful research on high temperature alloy net. Cheng investment casting technology, and applied to industrial production. With the development of hot isostatic pressing technology and high-temperature alloy filtration and purification technology, the metallurgical defects of high-temperature alloy investment castings are reduced and the performance is significantly improved. In recent years, the application of computer technology has improved the yield and performance of investment casting production. The qualified rate of directional hollow blade production has reached more than 90%, and the qualified rate of single crystal hollow blade production has reached 80%. With the continuous upgrading of the engine thrust-to-weight ratio, the structure and materials of its key hot end components have undergone tremendous changes, and the structure has become integral and thin-walled hollow. The direction of development, the materials required to be used have temperature bearing capacity at the same time has the performance, longer life and lower cost.
1) In terms of aero engine blades. Since 1980s, the structure, materials and manufacturing technology of turbine working blades and guide blades, the key hot end components of the engine, have been deeply studied, blade cooling systems, materials and manufacturing technologies with air cooling effects have been developed one after another, and the manufactured components have passed the full assessment of the engine. Luo Luo has been working on the key hot-end components of high thrust-to-weight ratio engines- Lamilloy and wall cold the structure and manufacturing technology of single crystal blades, and real cast blades have been used in engine tests. In the middle and late 1990s, Allision developed a collection of porous laminate cooling. Hole manufacturing technology, casting technology and material technology, casting has the advantages high cooling efficiency single crystal Lamilloy alloy turbine blades. The Cast Cool casting technology is used to Cast the ultra-air-cooled single crystal blades at one time. Russia has studied the casting technology of air-cooled single crystal hollow blades by adding cooling channels to the walls of high-pressure turbine blades of existing engines.
2) In aviation engine blade disc casting aspects. The aero-engine medium disk needs to be cast as a whole, and its blades are in a directional crystalline structure, while the roulette structure for fine crystal structure, this dual performance integral leaf disc(DS/GX) is the development trend of a new generation of aero-engine turbines. Howmet, Luo Luo equals 1980s to start the dual performance overall leaf tray material research on casting technology, and on 20 at the end of the century, a complete set of casting technology and casting equipment technology related to it was successfully cast, and the blades were cast as directional column crystals, roulette discs, etc. Shaft fine crystal the overall blade disc increases the service life of the existing gas turbine engine by 2 one3 times, the engine power increased by 7. 3% 19. 2%.
3) in superalloy square of integral structural parts and. At the end of the 20th century, Carret, PCC companies and others have developed newer bulky items. Finishing casting technology(Second Generation finishing casting technology), that is, thermal control solidification technology, it is achieved by controlling the temperature gradient and cooling rate of the solidification crystallization front of the casting alloy in the equiaxed crystal region to achieve the internal density of large and complex thin wall members. One grain size one the technological breakthrough and innovation of in-situ composite control of the organization have cast a larger size of 1027mm and a smaller wall thickness of 0.8 one 1. 2mm, grain size controlled at 1 one 5 m. The engine casing structure. The highlight of this technology is finishing casting process the compound control of dense filling and grain size refinement is realized, and the utilization rate of alloy materials is increased by more than 50%.
2 Titanium alloy casting technology
the United States1960s began to study applications titanium alloy casting technology, after decades of development, is currently at the world level, with investment mold ceramic mold technology, machine-added graphite mold technology and hot isostatic pressing technology. The whole of the engine titanium alloy the external dimension of the receiver is φ 1300mm X 368mm, which is currently the largest in the world. Titanium alloy castings, representing titanium alloy casting level.
For aviation hot isostatic pressure titanium alloy casting research, after research will titanium alloy castings are applied to military aircraft and have been proved by application. Titanium alloy as an aircraft body component, castings are comparable in performance and performance to plastic deformation components, while manufacturing costs and production cycles are significantly better than plastic deformation components. Compared with the combined structural parts, the cast structural parts have the advantages of mechanical fastening and connection, reducing the number of assemblies, which can reduce the weight of the structural parts, improve the integrity of the structure, and shorten the development cycle, reduce manufacturing costs.
With titanium alloy breakthroughs in casting heat treatment and process control technology, casting titanium alloy the performance has reached the performance of some forgings and can replace some forgings. Through the combination of parts, the use near net shape casting technology improves the overall structural performance, reduces the cost, and is widely used in key parts of aviation equipment. The amount of titanium alloy castings accounts for the weight of the body.7. 1%, there are about 54 on the body chin castings, the front and rear side castings of the wing are larger, 87kg and 58kg respectively. Through the use of solidification process control, inspection technology and product predictability, the quality and performance of the casting are obtained, and it is used in the "critical fracture part" of the wing and the body connection ".
3 Aluminum alloy casting technology
aviation aluminum alloy casting technology mainly includes investment casting, gypsum casting and sand casting, which are widely used in engines, airframes and airborne equipment. Investment casting and gypsum casting are mainly used for casting small and medium parts. In recent years, large-scale sand casting has developed and its dimensional accuracy has been greatly improved. Comprehensive application of the above methods, combined with computer design and control, pouring equipment improvement, can achieve size.1500m. Left and right, wall thickness 3m. The following castings global near net forming the casting performance reaches the performance level of medium deformation alloy, replacing some aluminum alloy forgings, rice gold parts and machine plus assemblies, thus achieving the purpose of weight reduction and manufacturing cost reduction.
Development Trend of Aviation Casting Technology
aviation casting technology continues to develop with the upgrading of aviation equipment and civil aviation products. In the forming accuracy, forming tooling, forming methods, forming process control to the degree of automation of forming equipment, all with the development of aviation equipment, in automation, economy and reliable sex and continuous improvement and improvement. Its general development trend is the complex integration of components, the full process of process design and control, and the digitization of detection technology.
1 Complex integration of components
in order to improve the performance of aviation equipment, the overall structural performance and performance, reduce the weight of the structure, reduce the manufacturing cost, and shorten the manufacturing cycle, the original several parts are combined into one, and the whole casting is formed, its shape and structure show an integral, thin-walled and complications; In addition, in order to realize certain functions, the structure and function are integrated, which also makes its shape and structure complicated; In addition, according to the characteristics and needs of the components in the equipment, some large integral structures require uniform organizational structure, and some large integral structures. Different pieces the tissue structure requirements of the site are different (e. G., dual performance integral leaf disc), some components have requirements for organizational structure control (such as directional or single crystal blades), so complex organizational structure is also one of the development trends of aviation equipment components.
2 forming
in order to reduce manufacturing costs and shorten the manufacturing cycle, the shape and size of the structural parts are required, I .e. no or less processing margin. Requires reduction in machining capacity more than 90%, the cost is reduced 66%, which leads to the overall shape and size of the parts.
3 Process design and control of the whole process.
In order to meet the needs of high performance and high performance of equipment, improve the performance of the casting itself, so that it has no.(Less) Defects and design and control the organizational structure of each part according to the use characteristics and requirements of the components. Shape control and control the complex integral casting is the basis for the development and development of a new generation of equipment. Its extensive research and application have greatly improved the performance of the equipment and played a key role in the development and development of the equipment.
