A large number of tests at home and abroad have shown that the processing quality of cages, ferrules, and steel balls have varying degrees of impact on bearing vibration. Among them, the processing quality of steel balls has the most obvious impact on bearing vibration, followed by ferrules. The most important factors affecting the processing quality are the roundness, waviness, surface roughness, surface bumps, etc. of the steel balls and ferrules. The most prominent problems of my country's steel ball products are the large discrete vibration values ??and serious surface defects (single points, group points, pits, etc.). Although the surface roughness, size, shape, and error are not lower than those outside the circle, the fit is not The vibration value of the rear bearing is high, and even abnormal noise is produced. The main problem is that the waviness is not controlled (no standards, no suitable testing and analysis instruments). It also shows that the vibration resistance of the machine tool is poor, and there are problems with the grinding wheel, grinding disc, coolant, and process parameters. ; On the other hand, management level must be improved to avoid random quality problems such as bumps, scratches, and burns. For ferrules, the most serious effects on bearing vibration are channel waviness and surface roughness. For example, when the roundness of the inner and outer channels of small and medium-sized deep groove ball bearings is greater than 2?m, it will have a significant impact on the bearing vibration. When the waviness of the inner and outer channels is greater than 0.7?m, the bearing vibration value increases with the increase of the waviness. Severe injuries can increase the vibration by more than 4dB, and even cause abnormal sounds. Whether it is a steel ball or a ferrule, waviness is generated during grinding. Although super-finishing can improve the waviness and reduce roughness, the most fundamental measure is to reduce the waviness during the grinding super-finishing process and avoid randomness. There are two main measures to prevent bumps and bruises: First, reduce the vibration during super-finishing grinding of the rolling surface, and obtain good surface processing shape accuracy and surface texture quality. In order to reduce vibration, the grinding and super-finishing machine tool must have good vibration resistance, and the bed Important structural parts such as these have vibration absorption properties. The oilstone oscillation system of super-precision machine tools has good anti-vibration performance; to increase the grinding speed, foreign countries generally use 60,000 electric spindles for grinding 6202 outer raceways, and the grinding speed is more than 60m/s. Domestic Generally much lower, mainly limited by the performance of the main shaft and main bearing. During high-speed grinding, the grinding force is small, the grinding deterioration layer is thin, and it is not easy to burn. It can also improve the processing accuracy and efficiency, which has a great impact on low-noise ball bearings. The dynamic and static stiffness of the spindle and its speed characteristics have a great impact on low-noise ball bearings. Grinding vibration has a great influence. The higher the stiffness, the less sensitive the grinding speed is to changes in grinding force, and the smaller the vibration of the grinding system. Improve the rigidity of the spindle bearing and use random dynamic balancing technology 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 general domestic spindles; it is crucial to improve the cutting performance and dressing quality of grinding wheel whetstone. The main problem of grinding wheel whetstone in my country at present is the poor uniformity of organizational structure, which seriously affects the quality of grinding and supermachining of low-noise ball bearings; sufficient cooling to improve filtration accuracy; improve the feed resolution of the fine feeding system and reduce the feed inertia; reasonable grinding and supermachining Process parameters and processing procedures are factors that cannot be ignored. The grinding allowance should be small and the geometric tolerance should be strict. The outer diameter of small and medium-sized ball bearings should not be super-finished, and rough and fine grinding should not be separated to ensure good surface quality. The second is to improve the accuracy of the machining datum surface and reduce the error during the grinding and ultra-machining process. The reflected outer diameter and end face are the positioning datum during the grinding and ultra-machining process. The error reflection of the outer diameter to the groove super-precision is indirectly transmitted through the error reflection of the outer diameter to the groove grinding and the groove grinding to the groove super-precision. If the workpiece is bumped during the transfer process, it will be directly reflected on the raceway processing surface and affect the bearing vibration. Therefore, the following measures must be taken: improve the surface shape accuracy of the positioning reference; the transfer is smooth during the processing without bumps; the shape and position error of the blank allowance cannot be too large, especially when the allowance is small, excessive errors will cause final grinding and super-finishing At the end, the shape accuracy has not been improved to the final quality requirements, seriously affecting the consistency of processing quality. It is not difficult to see from the above analysis: automatic line grinding and super-machining of low-noise ball bearings composed of high-performance and high-stability machine tool systems is the most suitable, which can avoid bumps, reduce transmission errors, eliminate manual factors, and improve processing efficiency and quality consistency. , reduce production costs and improve corporate efficiency. (1) Manufacturing process.
Process flow refinement mainly refers to the process flow being as short as possible, process processing merged, production without intermediate inventory, effectively reducing the process factors that affect the performance of low-noise ball bearings; production cleanliness, which is a systematic technology, including grinding fluid, ultrasonic Semen, cleaning fluid, air, high-pressure air, production environment and other technical processes; automation, automation of the entire process from machining to assembly, with few or no people; scale, such bearings, especially silent ball bearings, must form a large-scale Only in this way can we have the ability to compete in the global market. (2) Equipment. High-speed grinding, electric spindle accuracy, stiffness, life and various complete detection and protection properties play a major role in grinding processing accuracy and efficiency; grinding machine technology, foreign internal cylindrical grinders generally have high-speed grinding, AC servo control, feed Resolution 0.25?, fully automatic and simple operation, self-diagnosis function, etc.; ultra-precision technology, mainly centerless support two-station ultra-precision represented by Japan's Osaka Seiki and hydraulic centering four-stage represented by Germany's Thielenhaus There are two methods of position ultra-precision; online detection technology. Since the 1980s, the automatic grinding of ultra-short lines controlled by external feedback of active measuring machines has been the most common application in the Japanese bearing industry. The application of automatic grinding and ultrasonic lines constructed in this way in our country is also relatively mature, and there are currently about 100 lines in the country. With the continuous improvement of host technology in industrially advanced countries, wiring is becoming simpler and simpler, and active measurement and off-machine detection are gradually reduced or eliminated; centerless cylindrical grinders and cylindrical grinders (KOYO, MIKROSA, etc.) generally use rolling bearing grinding wheel spindle units, which have high It has a series of advantages such as stiffness, high precision, long life, convenient loading and unloading, and reliable use; the bed has damping and attenuation characteristics; the feed adopts a high-precision micro-motion AC servo system, a stable transmission AC variable frequency guide wheel adjustment system, and can be equipped with online Random intelligent measurement can realize CBN grinding wheel grinding, etc., and can realize automatic connection. The roundness can reach 0.3?m, and the size dispersion can reach 3?m. Surface grinders and foreign double-end (such as KOYO, Landis Gardner) surface grinder spindles generally use high-precision, high-stiffness rolling bearing spindle unit grinding wheel shaft systems and oil mist lubrication. Take Gardner Technology as an example. The company has been researching and producing system equipment for more than 90 years and can grind bearings, ceramics, glass, rubber, plastics and other materials.
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