On October 24, 2022, the anti-fatigue life test of key components of aero-engines carried out by the Beijing Institute of Aeronautical Materials exceeded 50,000 hours, marking a new breakthrough in China’s high-end equipment manufacturing technology.
The key component of this fatigue test is the aero-engine main shaft bearing independently developed by China. The fatigue life of the equivalent accelerated test on the tester did not fail for 50,000 hours, setting a new record in China.
Tang, senior engineer of Beijing Institute of Aeronautical Materials: The aircraft has to fly for thousands of hours. If the bearing fails, the engine cannot be used. It is the center of the engine. The test simulates the working conditions of the aero-engine. So far, the accelerated equivalent life has not failed for 50,000 hours, and the test is still in progress.
According to reports, during the operation and service of high-end equipment such as aircraft and high-speed railways, key components will experience fatigue, cracks and fractures, resulting in product failure, which is a major problem in the world’s engineering field.
Through technical research, Chinese researchers have independently developed a number of key technologies for anti-fatigue manufacturing, established an anti-fatigue manufacturing technology system, solved the problem of fatigue failure of key components, and laid a more solid foundation for the comprehensive autonomy of China’s high-end equipment.
Zhao (researcher of Beijing Institute of Aeronautical Materials) Said: Our anti-fatigue manufacturing technology can do almost all key components. The life and reliability of equipment are reflected by key components. With key components, high-end equipment can be made. Therefore, the overall improvement of China’s manufacturing technology has reached three limits: limit life, limit reliability, and limit weight reduction, which means it is at the international leading level.
Fatigue, wear and corrosion are the three major problems in mechanical engineering manufacturing recognized by the world.
The so-called fatigue refers to the process in which the material gradually produces local permanent cumulative damage in one or several places under the action of cyclic stress and strain, and then cracks or suddenly breaks completely after a certain number of cycles. In layman’s terms, it is like an iron wire. After repeated bending, it will become hot until it breaks, which is caused by fatigue.
The development of the “fatigue” problem can be traced back to 1830. Although after nearly two hundred years of research and exploration, today, the “fatigue failure” problem still ranks first among the three major problems. Because wear and tear can be prevented in advance through early warning, corrosion can be extended through trimming and protection, and fatigue is sudden breakage without any warning, which can be said to be impossible to prevent.
“Forming” manufacturing technology is the first generation of engineering manufacturing technology in the world. It has been passed down for a hundred years. It pursues “form and position precision” and aims to develop in the direction of “near defect-free”, but it does not solve the fatigue problem, resulting in the existence of key components. It has prominent problems such as short life, poor reliability and heavy structure.
From 1948 to 1970, the United States, with the strength of the whole country, researched and invented the second-generation manufacturing technology – “Surface Integrity” manufacturing technology, which is an interdisciplinary technology of “Cutting + Fatigue”. The surface of the components is strengthened, and the fatigue strength is improved to be sensitive to stress concentration, so as to prolong the product life. This technology has given the West a monopoly in high-end manufacturing, but the problem of fatigue has not been resolved, and the world’s manufacturing has not been upgraded and transformed.
Key components are the core of high-end manufacturing, mainly including transmission components, such as gears, bearings, etc.; rotating components, such as blades, wheels, etc.; and main load-bearing components, landing gear, butt bolts, etc. Academician Zhao, who has been engaged in aerospace materials research for a long time, believes that the key component is the integration of the three technical systems of design, manufacturing and materials. Primary failure mode.
Bearings are called the “joints” of the industry. High-performance bearings and gears are key components in mechanical systems. They are widely used in helicopters, aero-engines, racing cars and other precision machinery fields. important factor in sexuality.
In the 1960s, the United States introduced the double vacuum melting technology into gear steel, which solved the key problems of the transmission system. The life of the aviation spindle bearings they manufactured was thousands of hours or even tens of thousands of hours. To this end, five companies in the United States and the West have monopolized 80% of the world’s high-end bearing market and 100% of the aviation and high-speed rail market for more than 50 years. At that time, China’s high-performance gear bearing steel technology was very backward, and the life of aviation main bearings was less than 200 hours, which severely restricted the development of aero-engines, helicopters and other weapons and equipment and high-end mechanical products.
In 2009, the relevant national departments deployed the major project “Basic Research on Anti-fatigue Manufacturing of High-strength Anti-fatigue Aeronautical Components”, requiring the study of a verification piece to evaluate whether the anti-fatigue manufacturing theory and method are available. Because the main bearing of the aero-engine is the most important and difficult key component, the team of Academician Zhao selected a main point main shaft bearing, which can not only complete the verification, but also solve the problem.
In the next 13 years, Academician Zhao presided over the purification research of new bearing gear steel M50NiL. Through the process routes of “purifying raw materials, refining outside the furnace, VIM+VAR double vacuum smelting, and pulling the billet out of the pier”, the purity of M50NiL has exceeded the international leading level. He also designed a case-hardened stainless gear bearing steel composition system, bringing gear bearing steel to ultra-high strength, high toughness and ultra-high hardness levels for the first time.
On July 28, 2021, the aviation main bearing using the new bearing gear steel M50NiL and the most advanced products in the world were “competed on the same stage” in the anti-fatigue test. The ball life of China’s main bearing reached one million hours, 15 times higher than that of foreign products; Under the maximum load of 1.6 times the load spectrum, the accelerated test life (conversion) exceeds 30,000 hours without failure, breaking the international record of 20,000 hours without failure of similar products. The relevant national departments have successfully accepted and passed the basic research project of anti-fatigue manufacturing, including five mechanisms of anti-fatigue manufacturing, four methods of anti-fatigue manufacturing, and technical standards such as 100% increase in fatigue strength and 100 times increase in fatigue life have been completed. This is an epoch-making milestone, and another world record in the mechanical engineering manufacturing industry was born!