The most prominent problems of China's steel ball products are large dispersion of vibration values and serious surface defects (single points, group points, pits, etc.), although the surface roughness, size, shape, and error are not lower than the level of the circle, but the set The rear bearing has high vibration value and even produces abnormal sound. The main problem is that the waviness is not controlled (no standard, no suitable test and analysis instrument), and the machine tool has poor vibration resistance. There are problems with the grinding wheel, grinding disc, coolant and process parameters. On the other hand, it is necessary to improve the management level and avoid any occasional quality problems such as bruises, scratches and burns.
For the ferrule, the most serious vibration of the bearing is the channel waviness and surface roughness. For example, when the circularity of the inner and outer channels of small and medium-sized deep groove ball bearings is greater than 2μm, the bearing vibration will be significantly affected. When the internal and external channel waviness is greater than 0.7μm, the bearing vibration value increases with the increase of the waviness, and the channel is seriously injured. The vibration can be increased by more than 4dB, and even abnormal sounds can occur.
Whether it is a steel ball or a ferrule, the waviness is generated by grinding. Although ultra-finishing can improve the waviness and reduce the roughness, the most fundamental measure is to reduce the waviness during the grinding process and avoid randomness. There are two main measures for bump injury:
First, reduce the vibration of the rolling surface grinding superfine, obtain good surface processing shape accuracy and surface texture quality to reduce vibration, the grinding super machine tool must have good vibration resistance, and the important structural parts such as the bed have vibration absorption, super The oil stone oscillating system of the precision machine tool has good anti-vibration performance; the grinding speed is improved. The foreign grinding 6202 outer raceway generally adopts 60,000 electric spindles, and the grinding speed is more than 60m/s. The domestic is generally much lower, mainly by the spindle and Main bearing performance limitations. In high-speed grinding, the grinding force is small, the grinding deterioration layer is thin, it is not easy to burn, and the machining accuracy and efficiency can be improved, which has great influence on low-noise ball bearings; the dynamic and static stiffness of the main shaft and its speed characteristics are low-noise ball bearings. Grinding vibration has a great influence. The higher the stiffness, the less sensitive the grinding speed is to the change of grinding force. The smaller the vibration of the grinding system is. The rigidity of the spindle bearing is improved. The random dynamic balance technology is used to improve the vibration resistance of the grinding spindle. Sex. The vibration speed of foreign grinding heads (such as Gamfior) is about one-tenth of that of domestic general spindles; it is important to improve the cutting performance and dressing quality of grinding wheel. The main problem of the current grinding wheel in China is that the uniformity of the structure is poor, which seriously affects the super-processing quality of the low-noise ball bearing; sufficient cooling to improve the filtration accuracy; improve the feed resolution of the precision feeding system, reduce the feed inertia; reasonable grinding and super-processing Process parameters and processing flow are factors that cannot be ignored. The grinding allowance is small, the shape tolerance is strict, the outer diameter of small and medium-sized ball bearings should not be super-finished, and the coarse grinding should not be separated to ensure good surface quality.
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