Aviation engines are known as the "crown jewel" because of their high industrial technical requirements. Among them, aero-engine fasteners are the link within the "Pearl" body, and because of their high-pressure, high-temperature, and high-strength use environment requirements, their performance and technical requirements are more specific than other fasteners. High security and reliability. Therefore, major scientific and technological countries such as the United States and the United Kingdom have regarded aero-engine fasteners as a basic science and invested a lot of money in research and development. In the domestic aviation field, with the implementation of two major special projects, the path of professional development of aero-engines has been officially opened, creating better development conditions for subsequent professional and technical development and basic subject research.
The main fastener products on aircraft engines include various types of bolts, keyed screw piles, self-locking nuts, thread sleeves, pins, pipe fittings and connectors, etc. Compared with the large fastener family, the types of fasteners used in aero-engines are relatively concentrated. However, due to the limitations of their working environment, the performance requirements of such fasteners, especially hot-end fasteners, are higher.
There are many domestic aero-engine fastener manufacturers, mainly scattered in the aviation and aerospace fields and some private enterprises. Each manufacturer is independent of each other and has overlapping product coverage. They mainly focus on production and manufacturing, and there is no base that combines research and manufacturing. Most domestic aero-engine parts companies are branch companies that are separated from aero-engine main engine factories and engage in the production of fasteners and small and medium-sized parts. The manufacturing level, technical status management level, and testing and testing capabilities of each manufacturer are uneven. Forming a specialized production base that combines research and manufacturing is not conducive to the technical research and development of aviation fasteners.
1. High temperature and high strength bolts and screws
Bolts and screws made of materials such as GH4169 are currently the most widely used high-temperature and high-strength fasteners in aero-engines. After heat treatment, the tensile strength of such parts reaches σb ≥ 1250Mpa, and the threads of this type of high-strength fasteners are processed by warm rolling. Technology is the direction of research and development.
2.Tighten the bolts
Engine turbine bolts and high-precision slender tightening bolts are key and important load-bearing parts of aeroengines. This type of fasteners are generally processed from forging blanks, and the materials are mainly high-temperature alloys and titanium alloys. In addition to high-temperature, high-strength, and high-precision performance requirements, such parts also have structural forms and requirements for slender shaft parts. The processing difficulties of this type of parts mainly lie in high-strength thread rolling and processing deformation control of slender shafts.
3. Keyed locking screw piles and screw sleeves
Keyed locking screw piles and threaded sleeves are a newly developed aviation fastener connection technology in recent years. This connection technology is mainly transformed from the traditional combined connection method of interference threads and locking discs. It is a pin-key locking method, making the assembly locking structure more compact, more reasonable, and more reliable in preventing loosening.
4. High temperature alloy self-locking nut
Self-locking nuts. In the past, the form of this type of fastener was relatively simple, mainly made of alloy steel and stainless steel. With the continuous advancement of aero-engine technology, most of the self-locking nuts of engine fasteners are now mainly made of high-temperature alloy materials. The lock deformation forms include two-point, three-point, four-point, straight groove, inclined groove and other closing forms. The standards implemented include HB, GJB and the special technical standards of each developed model.
5. Special self-locking nut
With the gradual improvement of domestic and foreign advanced aerospace engine technology, more reliable, simpler and lighter spindle rotor fasteners are needed to fasten parts on high-speed rotating spindles. The diameter and thickness ratios of this special self-locking nut on a high-speed rotating spindle are generally 4:1, 6:1, and 10:1. The self-locking deformation zone of this type of special self-locking nut is short, the process is difficult to form, and it affects the material. The requirements for heat treatment control, metallurgical quality, and self-locking stability are very high. Therefore, the technical difficulties of this type of fasteners lie in the manufacturing process, testing technology, inspection technology, etc., and require the assembly of special equipment, test tooling, inspection tooling, etc.
With the rapid development of aero-engine technology, aerospace fastener parts have developed into a huge product system. In order to meet the higher performance requirements of aero-engines, the following trends exist for future aerospace fasteners:
1. The development cycle is getting shorter and shorter
Judging from the current development trend, the development cycle of aero-engines is getting shorter and shorter, and the development cycles of the related parts and components industry are being compressed shorter and shorter, which requires greater investment in research and development, technical transformation equipment, etc. resources invested.
2. Product performance requirements are getting higher and higher
The performance requirements of aerospace engines are getting higher and higher. Similarly, the performance requirements for aerospace fasteners are also gradually increasing to meet the increasingly complex use environment. The technological research and development of new fasteners is also gradually developing.
3. Further lightweighting, application of new materials and new technologies
From the perspective of economic usability, the smaller the weight requirements of modern aero engines and aircraft, the better. The development and use of new materials such as titanium alloys and composite materials will overall improve the technical level of aviation fasteners and reduce the weight of engines. .
4. Application of key manufacturing technologies such as intelligent manufacturing
The development of intelligent manufacturing technology will effectively promote the improvement of aviation fastener manufacturing technology. In future production plants, flexible production lines, robotic arms, intelligent manufacturing centers, etc. will become standard equipment, overall improving the quality of aviation fasteners. Manufacturing level.
Aviation fasteners are an industry with broad market prospects and development potential. As the supporting production cycle of aero-engines is getting shorter and shorter, it has become particularly necessary to build a specialized R&D and production base for fasteners in the aero-engine industry. In the complex distribution environment of domestic aviation fasteners, we must concentrate our superior resources to quickly adapt to the development trends of intelligent manufacturing, manufacturing service-oriented, green manufacturing, etc., carry out intelligent manufacturing technology research, and create a professional "intelligent manufacturing" for aviation fasteners. R&D base" will play a positive role in promoting the overall development of aviation engine technology.