Deep Groove Ball Bearings Forging process specification
Forging process specification steel contains complex carbide (Fe, Cr) 7C3, heated in the austenite when the slow speed, while the thermal conductivity of steel is poor, therefore, forging heating speed should be slow. Heating temperature is too high or stay in the high temperature area is too long, easy to produce twin and damage the performance of steel. But also because of the good hardenability of the steel and poor thermal conductivity, after forging the cooling must also be slow, or easy to produce cracks. If the forging temperature is too high, easy to produce mesh carbide, coarse mesh carbide structure in the subsequent annealing process can not be eliminated. The material at high temperature deformation resistance, low plasticity, forging performance is poor, the mold material and structure have special requirements.
In order to better evaluate the bearing noise level, in the actual measurement, for each set of bearings to measure the front and back of the three points of the uniform vibration value, take a larger test value as the effective vibration value of the bearing.
(1) As can be seen from Table 2, low noise grease can greatly reduce the bearing vibration and noise, 100% after filling grease to meet the requirements of Z2 group (40 dB), 98% to Z3 group requirements (38 dB) The product has a certain reserve accuracy. Due to the stability of the machine, the quality of the grinding wheel during the grinding process and the unevenness of the grinding wheel dressing quality, the unevenness of the oilstone and Whetstone replacement and the quality of the dressing in the channel super-fine process is difficult to avoid the influence of the system. Process processing accuracy requirements of the case, there is a certain degree of volatility, so the vibration data in Table 2 data have a certain degree of dispersion.
(2) in the testing process found that 5 sets of bearing single-sided test of the vibration value is relatively high, wash away the grease, demolition and found that the channel side of the ultra-fine quality is poor, leaving a wheel flower. This shows that the swing center of the Whetstone and the groove of the channel after grinding the center of the curvature of a certain deviation, affecting the surface quality of the channel. By the speaker to enlarge the sound signal to determine the 5 sets of significant abnormal sound, observe the internal grease found foreign body intrusion, the channel of ultra-fine quality is not high.
(1) The final vibration value test was carried out by using the new process for the 6204E. The results of the final vibration test verify the feasibility and effectiveness of the process and accumulate the production experience for the production of low noise bearings.
(2) to improve the end of the outer diameter of the positioning accuracy for the bearing channel grinding, ultra-fine to provide a good process benchmark, is conducive to processing a good channel surface quality. Adjust the channel ultra-fine process parameters, so that the surface to form a uniform, delicate strip lines, can effectively reduce the bearing vibration and noise levels.
(3) to improve the quality of bearing assembly, strict implementation of the specifications, to prevent the bearing surface bumps, but also reduce the bearing vibration and noise effective measures.
Stainless steel bearing fracture failure is mainly due to defects and overload two factors. When the external load exceeds the material strength limit caused by part fracture known as overload fracture. The cause of the overload is mainly the host failure or improper installation. Bearing parts of the micro-cracks, shrinkage, bubbles, large foreign debris, overheating tissue and local burns and other defects in the impact of overload or severe vibration will also cause damage in the defect, known as defective fracture. It should be noted that the bearing in the manufacturing process, the raw materials into the factory re-inspection, forging and heat treatment quality control, processing process control can be correctly analyzed by the instrument whether the existence of defects, the future must still strengthen control. But in general, the failure of the stainless steel bearings usually occurs mostly for overload failure.
