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As an emerging technology to explore the development prospects of manufacturing industry, additive manufacturing continues to explore and innovate in high-precision and cutting-edge fields such as aerospace, and integrates traditional processing and intelligent technology, which will bring far-reaching impact and major changes to these industries.
In order to reduce the quality, improve the service life and reduce the manufacturing cost, the overall metal components in the aeroengine structure are used more and more, which also makes the key parts of the aeroengine difficult to process and the utilization rate of special materials low.
For a long time, the factors restricting the development of the aeroengine are more prominent.
The technical concept of directly using additive materials to manufacture metal parts was first put forward by the United Technologies Research Center (UTRC) in 1979.
Its application object is mainly aimed at the turbine disk, the core component of aeroengine.
However, due to the limitation of industrial laser power and numerical control technology at that time, this technology did not immediately attract much attention.
Since the 1990s, Ge, RORO, Pratt Whitney and other enterprises and research institutions have carried out a lot of research work on metal additive manufacturing technology and its application in the field of aeroengine, and put forward aeroengine parts that can be produced through additive manufacturing technology, as shown in Figure 1.
Up to now, high-performance metal additive technology has brought many benefits.
For example, it has realized the rapid research and development of new engine models, reduced the mass of parts, significantly saved expensive metal materials, diversified structures, prolonged the service life of parts and reduced the repair cost.
At present, the application requirements and research hotspots of additive manufacturing technology in the field of aeroengine mainly focus on reducing the cost of materials and machining, shortening the development cycle and broadening the design freedom to manufacture integral components with complex structures.
The laser melting deposition additive manufacturing technology of titanium alloy components used in the development of fan / compressor is one of the research focuses.
Fig.
1 Application of additive manufacturing in fan / compressor.
In the mid-1980s, a new configuration called “blisk” appeared in the structural design of aeroengine, as shown in Fig.
2.
The integral blade disc makes the blade and disc of the engine rotor into a whole, eliminating the connecting parts such as tenon, tenon groove and locking device, which greatly simplifies the overall structure of the engine, reduces the structural quality and reduces the number of parts.
For example, after the second and third stage fans and the first three stage high-pressure rotors of f414 engine in the United States are replaced with integral bladed discs, 484 parts are reduced and the thrust weight ratio of the engine is increased from 7.5 ∶ 1 to 9.0 ∶ 1; The air flow loss between the tenon and the tenon groove is eliminated and the pneumatic efficiency is improved; The abrasion caused by improper assembly is avoided, especially the fretting wear between tenon and tenon groove is avoided, and the working life, safety and reliability of the engine are greatly improved.
Blisk technology represents the development direction of the fourth and fifth generation high thrust to weight ratio aeroengine technology.
It has become a necessary structure of high thrust to weight ratio engine and one of the core key technologies that must be adopted in the development of advanced aeroengine.
2.
Compared with the traditional manufacturing process of titanium alloy, the manufacturing process of titanium alloy blade is short, and the integral component and purification ratio of titanium alloy are high.
Compared with the traditional manufacturing process of titanium alloy blade, the manufacturing process of titanium alloy blade is short The utility model has the advantages of low cost, and can realize the low heat effect and low deformation repair of integral blade disk parts.
Titanium alloy blisk additive manufacturing technology has been widely used in military such as ej200, F119, f414 and F110 and civil aviation engine fans and compressor rotors such as GE90, Trent 900, pw300 and br715.
MTU, RORO, Ge, Pratt Whitney and other aero-engine companies have listed the technology related to blisk as the core key technology with high confidentiality since the proposal and application of Blisk additive manufacturing technology, and have accumulated decades of research and development experience.
Fan / compressor casing in 1994, RORO and Cranfield University began to explore the laser solid forming (LSF) manufacturing technology of aeroengine casing.
In 2016, RORO and GKN Aerospace reached an agreement to expand their cooperation in Trent xwb-84 engine project.
GKN aerospace is responsible for providing high-performance intermediate stage compressor casing for Trent XWB engine design, and adopts the latest design methods and manufacturing technologies including additive manufacturing process and new welding technology, as shown in Figure 3.
This kind of thin-walled structural parts made from bushing, shell, rib and other characteristic forms also include Aeroengine Blades and combustion chambers.
If they are made by traditional casting, forging, welding, machining and other processes, they have the disadvantages of long cycle and low material utilization.
In contrast, additive manufacturing can easily realize the preparation of large-scale depth diameter ratio thin-walled structure, which can save more development costs and shorten the development cycle.
Figure 3 wide chord hollow fan blade of intermediate stage compressor casing of Trent xwb-84 engine is one of the core parts of turbofan engine.
RORO began to design and manufacture wide chord fan blades in 1968 and successfully applied them to RB211-535E4 engine.
With the continuous development of aerodynamic design technology, structure technology, material technology and additive manufacturing technology, wide chord hollow fan blades are more widely used in aeroengines.
RORO, Pratt Whitney, Ge, SNECMA and other companies promote their use in their engine products, such as F119, Trent 800 and so on..
