At present, the internal structural parameters of deep groove sealed ball bearings in my country are almost the same as those of foreign advanced companies. However, the vibration and noise levels of such products in my country are far from those of foreign products. The main reason is the influence of manufacturing and working conditions. From the perspective of the bearing industry, the working condition factors can be solved by putting forward reasonable requirements for the main engine, and how to reduce the vibration and noise caused by manufacturing factors is a problem that the bearing industry must solve.
A large number of tests at home and abroad have shown that the processing quality of cages, rings, and steel balls have different degrees of influence on bearing vibration. Among them, the processing quality of steel balls has the most obvious impact on bearing vibration, followed by the processing quality of rings. The most important factors are roundness, waviness, surface roughness, surface bumps, etc. of steel balls and rings.
The most prominent problem of my country’s steel ball products is that the vibration value is large and the surface defects are serious (single point, group point, pit, etc.). Although the surface roughness, size, shape, and error are not lower than the level outside the circle, the vibration value of the bearing after assembly is high, and even produces abnormal noise. Mechanical quality problems. For the ring, the channel waviness and surface roughness are the most serious factors that affect the vibration of the bearing. For example, when the roundness of the inner and outer grooves of small and medium-sized deep groove ball bearings is greater than 2 μm, it will have a significant impact on the vibration of the bearing. When the waviness of the inner and outer grooves is greater than 0.7 μm, the vibration value of the bearing will increase with the increase of the waviness. Severe damage to the grooves can increase the vibration by more than 4 dB, and even produce abnormal sounds. Regardless of whether it is a steel ball or a ferrule, the waviness is generated in the grinding process. Although super-finishing can improve the waviness and reduce the roughness, the most fundamental measure is to reduce the waviness during the super-finishing process and avoid random bumps. There are two main measures: Deep groove ball bearings reduce vibration
One is to reduce the vibration of rolling surface grinding and super-finishing to obtain good surface machining shape accuracy and surface texture quality. To reduce vibration, the super-grinding machine tool must have good vibration resistance. In high-speed grinding, the grinding force is small, the grinding deterioration layer is thin, it is not easy to burn, and it can improve the machining accuracy and efficiency, which has a great influence on low-noise ball bearings; the dynamic and static stiffness of the spindle and its speed characteristics have a great influence on the grinding vibration of low-noise ball bearings. The higher the stiffness, the less sensitive the grinding speed is to the change of the grinding force, and the smaller the vibration of the grinding system; the rigidity of the spindle bearing is improved, and the random dynamic balance technology is used to improve the vibration resistance of the grinding spindle. The vibration speed of foreign grinding heads (such as Gamfior) is about one-tenth of that of domestic general spindles; it is very important to improve the cutting performance and dressing quality of grinding wheel oilstone. At present, the main problem of grinding wheel oilstone in my country is the poor uniformity of the structure, which seriously affects the quality of low-noise ball bearing grinding and over-grinding; sufficient cooling to improve the filtration accuracy; increase the feed resolution of the fine-feeding system and reduce the feed inertia; reasonable grinding and super-processing parameters and processing processes are factors that cannot be ignored. The grinding allowance should be small, and the shape and position tolerances should be strict.
Deep groove ball bearings improve precision
The second is to improve the accuracy of the machining datum surface and reduce the error in the grinding process. The outer diameter and end face are the positioning references in the grinding process. The error reflection of the outer diameter to the groove superprecision is indirectly transmitted through the error reflection of the outer diameter to the groove grinding, and the groove grinding to the groove superprecision. If the workpiece is bumped and damaged during the transfer process, it will be directly reflected on the raceway processing surface, which will affect the vibration of the bearing. Therefore, the following measures must be taken: improve the shape accuracy of the positioning reference surface; the transmission is smooth during processing, without bumps; the shape and position error of the blank allowance should not be too large, especially when the allowance is small, the excessive error will cause the shape accuracy at the end of final grinding and superfinishing to not be improved to the final quality requirements, which seriously affects the consistency of processing quality.
From the above analysis, it is not difficult to see that the automatic line mode composed of high-performance and high-stability machine tool system is the most suitable for super-grinding low-noise ball bearings, which can avoid bumps, reduce transmission errors, eliminate artificial factors, improve processing efficiency and quality consistency, reduce production costs, and improve enterprise benefits.
Post time: Jul-24-2023