Bearings are key machine parts that bear load and transmit motion. The challenges brought about by the increasing power density of modern equipment manufacturing industry have put forward higher requirements on the bearing capacity and reliability of bearings. Today, the editor will come to talk with you about methods and measures to improve bearing fatigue life.
Bearings in specific applications will fail prematurely, and their service life only accounts for 5%-10% of the calculated rated life. Many early failure bearings have a typical feature-a large-area subsurface crack network with “white etching morphology”, that is, white etching cracks.
There are many factors affecting white etching cracks, including raw materials, bearing design, lubrication, stress, surface and many other aspects. Among them, the bearing steel as a raw material, its composition design, purity, carbides, internal pores and other improper control will cause white corrosion cracks and cause early failure of the bearing. In order to obtain a high and stable fatigue life, the following aspects of the bearing steel production process must be done:
1. According to the application environment and characteristics of the bearing, select and design suitable bearing steel varieties, establish chemical composition internal control standards, and focus on the control of residual and harmful element content.
2. The oxygen content of the bearing steel, non-metallic inclusions and other purity indicators are improved through measures such as the control of the oxygen content of the steel in the primary furnace, the control of the amount of slag, the control of the slag composition, the control of the refining and pouring process, and so on.
3. According to different carbide quality requirements, choose different smelting processes such as vacuum degassing, electroslag, and self-consumption to obtain the corresponding level of carbide level. At the same time, we will do a good job in the process of temperature injection speed control, high temperature diffusion and other aspects of process optimization, to further improve the size and distribution of carbide particles, and reduce the risk of bearing fatigue life reduction caused by residual stress caused by microstructure changes.
4. For the rolling elements, the control of the microscopic pores in the bearing steel is even more important because there is no longer any thermal deformation treatment in the bearing manufacturing process. In the production process, it is necessary to focus on the control of processing methods, processing ratios, heating systems, etc.
5. Establish a complete bearing steel inspection system. On the one hand, it is necessary to formulate detailed laboratory sample preparation inspection plans, make full use of laboratory testing capabilities, objectively evaluate the physical quality level of each heat, and do a good job of high-frequency water immersion The promotion and application of new methods such as flaw detection and maximum extreme value detection; on the other hand, make full use of on-site surface and internal automatic flaw detection equipment to prevent the outflow of defective steel. Through the implementation of the above measures, the product quality level and quality stability are improved, thereby reducing the bearing white corrosion crack defects caused by raw materials.
Bearing manufacturing is a systematic engineering, and every link and step is very important. Therefore, in the design and production of bearing steel components, bearing manufacturing, heat treatment, processing and assembly, etc., qualified bearing products must be produced in strict accordance with the requirements of the standard.