On 2018-08-08 14:48:54
Bearing design and technology
Lack of individualized and differentiated design
In order to improve the bearing design of the predecessors, the individualized and differentiated design should be adopted according to the service environment of the bearing, so as to meet the actual working condition requirements of the bearing. The individualized and differential design of bearings in China is still insufficient. In addition, the design of bearing heat treatment is also an important factor affecting the bearing life. The bearing consists of four parts: outer ring, inner ring, dynamic body and cage. In order to improve the hardness of the inner and outer rings and the dynamic bodies of the previous bearing enterprises in foreign countries, many domestic and overseas enterprises that produce automobile bearings have begun to try to do so. However, restricted by the hardness requirements of the general industry standard of bearings, the hardness design of bearing parts is limited. At the same time, the heat treatment technology and equipment level of the bearings in the sea are also factors that affect the realization of individualized and differentiated design. In a word, compared with the foreign advanced enterprises, the design of automobile bearing in our country is in the extensive stage, many sub fields have not carried out special research, the majority of imitative design, the less independent design, and the lack of technical storage in bearing design.
Cqi-9 quality scale promotion
The quality of heat treatment of bearing parts is an important factor to determine the bearing life. At present, the main domestic automobile bearing manufacturers have basically guaranteed the heat treatment quality of the parts, but they do not pay enough attention to the control of the heat treatment process parameters, the use of quenching medium and the guarantee ability of heat treatment equipment, which leads to a large gap between the quality of heat treatment of bearing parts and that of foreign countries. In order to improve the cqi-9 quality standard that has been widely implemented by the predecessor enterprises in foreign countries, it is only limited to the selective trial of individual enterprises at home, which is also mixed with the factors to deal with the audit of foreign enterprises. Therefore, fully and consciously implementing and promoting cqi-9 quality standard should be the only way for domestic bearing manufacturers to improve the quality of heat treatment and to reach or surpass the level of their predecessors abroad.
Application of new energy saving technology
At present, the traditional heat treatment quenching and tempering processes, such as 820-860 ℃, oil quenching and tempering below 200 ℃, are still widely used in most domestic bearing enterprises. The whole process is about 4.5-5.5h. The process has been used for nearly forty to fifty years. With the increasing call for energy conservation and environmental protection, the bearing heat treatment industry, as a major energy consumer, has also begun to try to study and improve the classical heat treatment process of bearings. The core of the research is to change and improve the quenching and tempering temperature and shorten the process time. At the same time, non oil quenching medium, such as salt bath and water-soluble medium, is tried to be used to enlarge the processing range of heat treatment and make the deformation of heat treatment more regular. Xiangzhou, Wazhou, Luozhou and other enterprises have tried in these aspects and achieved some results.
In addition, the normalizing treatment after casting has been widely used at home and abroad, which saves a lot of energy, but there is no clear process specification. The energy is used, but the normalizing quality is not disorderly. It is necessary to have the necessary special equipment to solve the quality problem.
The resurgence of carburized automobile bearing
The high-quality comprehensive mechanical function of bearing after carburizing can not be replaced by other bearing materials, so carburizing steel becomes the material of automobile bearing. The use of carburizing steel for automobile bearings was very popular in the 1980s, when some domestic enterprises began to import complete sets of bearing heat treatment carburizing equipment. Later, with the improvement of smelting quality of high carbon chromium bearing steel and the early development of domestic automobile industry, a large number of low cost high carbon chromium bearing steel bearings are needed for domestic low-end models, and carburized automobile bearings are temporarily put on hold. In recent years, with the large number of overseas automobile giants in China and the progress of the overall level of the domestic automobile industry, carburized automobile bearings have been proposed again. In the future, carburized automobile bearings will be widely used in military vehicles, passenger vehicles and other hub parts with high safety factor requirements. 20CrMnTi, 20crnimoa and so on are commonly used materials for Automobile Carburized bearing. The carburizing temperature is 900-930 ℃. The high heat treatment cost of carburized automobile bearing limits its wide application. Domestic enterprises have also begun to try new carburizing processes, such as high temperature carburizing, that is, carburizing at 1000 ℃ or 1050 ℃, which can greatly shorten carburizing time and reduce cost. However, due to the restriction of carburizing equipment, it is only in the trial stage at present, and it will take a long time to popularize in large quantities.
In addition, the development of GCr15 bearing steel carburizing process also provides a new idea for the use of high carbon chromium bearing steel.