As the key part of rolling bearing, steel ball plays the role of carrying and transmitting load and motion in the bearing, which has a great influence on the life of the bearing and the vibration and noise. Any point on the surface of the steel ball is the working surface that bears the load. It bears the variable load with indefinite period. The contact area is small and the contact stress is large. The entire surface of the steel ball is both a processing surface and a supporting surface. Therefore, the processing technology of steel balls is also very unique and specialized in the machinery industry, and has very high requirements for raw materials, process technology, processing equipment, tooling and abrasives, and grinding fluids. At present, the domestic steel ball technology level, equipment level, quality control level and tooling and abrasive level have reached or approached the international advanced level. Quality level of steel balls: mass production tolerance grade G5, complete specifications and materials, single particle vibration reaches 26 dB, and the life K value reaches (the ratio of the basic rated life test value L10t to the basic rated life L10) of more than 12. 1) There are two main processing methods in the processing process: 2) The raw material GCr15 wire is the most widely used due to its moderate price and easy heat treatment, accounting for more than 85%. Others, such as applications where corrosion resistance is more important than durability, use stainless steel balls; aircraft and other special purposes require the use of high-speed tool steel (tungsten series steel) and heat-resistant steel ( M50), etc., steel balls for special purposes usually have higher material costs and higher processing costs due to the implementation of complex heat treatment processes (such as high temperature quenching, multiple tempering, cold treatment, etc.). 3) Process equipment A complete set of main steel ball processing process equipment has been formed in China, including Z32, Z32G series steel ball cold heading machines and high-speed cold heading machines, 3M49, 3M79 series light ball machines, 3M46, 3M76 series ball grinding machines, 3M47, 3M77 series ball grinding machine, protective atmosphere heat treatment furnace, steel ball surface strengthening machine, cleaning machine based on brush cleaning and high strength sponge rotary extrusion cleaning, etc. The inspection equipment mainly includes the appearance inspection instrument for the surface quality of steel balls based on the vision system, and the eddy current photoelectric appearance inspection instrument with optical and vibration channels based on the principle of eddy current flaw detection. The grinding plate diameter of the main processing machine tool for light, grinding and grinding is φ300~950(1000)mm, and the ball loading capacity is 20~1000kg. The machining accuracy of the machine tool can meet the requirements of G5 steel balls. Issues that need attention: 1. The quality of the domestic high-speed cold heading machine is still not stable, the reliability is poor, and the quality of the cold heading mold is low; 2. The polishing, grinding, and grinding equipment are generally general-purpose equipment, and the special-line professional layout design has There are many improvements, and the efficiency still needs to be continuously improved; (3) the automatic control and automation level of the polishing, grinding and grinding equipment needs to be further improved; (4) the cleaning, drying, and quality control connection equipment between the steel ball processing procedures still lacks professional layout and quality control. Production; (5) The applicability and cleaning reliability of the finished steel ball cleaning equipment need to be improved; (6) The appearance inspection equipment for the finished steel ball needs to be improved to improve reliability. 4) Quality control method Domestic steel ball quality control has formed a complete set of methods, the main quality indicators and methods are: raw material quality, size and dimensional accuracy, heat treatment hardness and metallographic structure, surface defects. With the improvement of steel ball processing technology and processing equipment, all steel ball manufacturers can basically meet the standard requirements in terms of size and dimensional accuracy, heat treatment hardness, etc. Issues that need to be paid attention to: 1. Raw material quality control and material selection according to the use of steel balls; 2. Detection and control of dimensional stability of steel balls; 3. Steel ball surface strengthening and surface stress control; 4. Steel ball surface morphology 5. Monitoring and control of steel ball surface waviness; 6. Steel ball delivery quality confirmation; 7. Steel ball contact fatigue life test and control. 5) Contact fatigue failure The mechanism of rolling fatigue is roughly divided into two categories: internal origin spalling and surface originating spalling. Internally-originated spalling is mainly caused by non-metallic inclusions under the rolling contact surface as the origin of spalling, which needs to be dealt with by improving the purity of raw materials. Surface-originated spalling is directly related to the operating environment, lubrication state, and surface state of the rolling contact surface (surface roughness and scars on the rolling surface) of the rolling bearing. than larger. Coping strategies for surface-originated spalling, such as carbonitriding treatment on the surface of GCr15 steel balls, due to the high cost of carbonitriding treatment, the more important technology is to use ordinary overall quenching to improve the surface hardness of steel balls, so that the pressure It is difficult to form marks and improves the durability in the presence of foreign objects. 6) Summary Steel balls still need to further improve the quality as the primary goal, adopt a reasonable material purity evaluation method, and thoroughly conduct quality management from the billet. Instrumentation is essential. In addition, to improve durability,While requiring steel mills to further improve the purity of materials, develop heat treatment technology for steel balls suitable for applications, and endow traditional GCr15 steel balls with various added values. In recent years, as the demand for bearing applications has become more and more diversified, under the application conditions of high speed and high temperature, ceramic balls (such as Si3N4 balls) are used to replace steel balls. , but the issue of high prices remains to be resolved. (Source: Bearing Magazine)