The self-aligning roller bearing is an important mechanical basic connector, which is widely used in the mechanical industry. It can be said that there are bearings where there is rotation. As the main means of transportation in modern society, automobile industry has become the main pillar industry in China, bearing also plays an important role in it. Many automotive security components, such as steering gear, engine and gearbox, can be seen in the form of bearings. As a branch of bearings, automotive bearings have special performances such as bearing capacity, impact resistance and high speed rotation. Their performances have an important impact on the safety of passengers, drivers and vehicles themselves.
Material quality is the most important factor to determine bearing life. The gap between domestic and foreign automobile bearings, material is the main factor, followed by bearing design, technology level and process equipment. Although we have revised the GB/T 18254 standard and added the standard of "high-quality high-carbon chromium bearing steel", and raised the requirements for carbides, segregation, oxygen content and inclusions, it is still very difficult to implement it completely owing to factors such as smelting technology and cost of domestic steel plants.
With the wide application of vacuum degassing, the oxygen content control of bearing steel in China has been greatly improved, which is close to the level of foreign countries. However, there are still large gaps in carbide uniformity, network carbide control, inclusion control and so on, which results in congenital insufficiency of the quality of domestic automobile bearings, and the service life, reliability and consistency of bearings are inferior to those of foreign bearings.
GCR15 steel and GCR15SIMN steel are widely used in bearing materials in China, and their varieties are single. The research and development of special materials for automotive bearings has not been reported yet. Bearing steel manufacturer seldom cooperates with bearing manufacturer.
Advanced bearing design should adopt individualized and differentiated design according to the service environment of bearings to meet the actual working conditions of bearings. Individualized and differentiated bearing design in China is still insufficient. In addition, bearing heat treatment design is also an important factor affecting bearing life. Bearing includes four parts: outer ring, inner ring, rolling element and cage. Foreign advanced bearing enterprises have different hardness requirements for inner and outer rings and rolling elements. Many top domestic enterprises producing automobile bearings have begun to try this, but it is limited by the hardness requirements in the general bearing industry standard "Technical Conditions for Heat Treatment of Rolling Bearing Parts with High Carbon Chromium Bearing Steel". The hardness of bearing parts is set up. There are limitations. At the same time, the domestic bearing heat treatment technology and equipment level are also factors affecting the realization of individualized and differentiated design. In a word, compared with foreign advanced enterprises, the design of automobile bearings in our country is in the extensive stage, many sub-fields have not been specially studied, imitation design is in the majority, independent design is less, and the technical reserve of bearing design is even more deficient.
The heat treatment quality of bearing parts is an important factor to determine the bearing life. At present, the main domestic automotive bearing manufacturers have basically guaranteed the quality of heat treatment of parts, but they have not paid enough attention to the precise control of heat treatment process parameters, the use of quenching medium and the guarantee ability of heat treatment equipment, which results in a large gap between the quality stability of heat treatment of bearing parts and that of foreign countries. The quality standard of CQI-9, which has been widely implemented by foreign advanced enterprises, is limited to the selective trial of individual enterprises in China, which is also doped with the factors to deal with the audit of foreign enterprises. Therefore, to implement and promote CQI-9 quality standard comprehensively and consciously should be the only way for domestic bearing manufacturers to improve the quality of heat treatment and to reach or surpass the advanced level of foreign countries.
