With the development of science and technology, the spindle speed of the machine tool is getting higher and higher, and the speed change range is getting larger and larger. Therefore, the requirements for the stability of the bearing at high speed are getting higher and higher. Bearing temperature rise is an important factor limiting bearing speed. Under normal circumstances, the correct selection of deep groove ball bearing type, tolerance grade, configuration method, clearance (preload) size, lubricant and lubrication method can improve the high-speed performance of rolling bearings to a certain extent.
For general machine tools, the life of the spindle assembly mainly refers to the service life of the spindle to maintain the accuracy of the spindle. Therefore, the accuracy of the bearing is required to meet the requirements of the life of the spindle assembly. For heavy machine tools or powerful cutting machines, the load carrying capacity of deep groove ball bearings should be considered first.
Deep groove ball bearings are precision parts, so it is required to be cautious when using them. Even if high-performance bearings are used, if they are used improperly, they cannot achieve the expected performance effects. Therefore, the use of bearings should pay attention to the following matters.
(1) Dehydrogenation treatment. Deep groove ball bearings are treated with different heat treatment processes. After carbonitriding, hydrogen embrittlement is serious, and the section shrinkage rate of bearing steel is very low. After dehydrogenation treatment, the performance of the workpiece is restored, and the workpiece no longer has hydrogen embrittlement defects after re-quenching.
(2) Low temperature tempering dehydrogenation of deep groove ball bearings. With the prolongation of tempering time, the area shrinkage rate increases, and the area shrinkage rate returns to the original level after tempering for 8 hours. In addition, the hot-rolled microstructure releases hydrogen slowly, indicating that hydrogen embrittlement is related to the original microstructure.
(3) Natural aging dehydrogenation. When the hydrogen-containing workpiece is placed at room temperature, the supersaturated hydrogen is gradually released and precipitated, and the hazard of hydrogen embrittlement is reduced. From the recovery of section shrinkage after 3 months and 6 months of workpieces treated by two different processes, it can be seen that the normalized state recovers faster, and it has basically recovered after 3 months; the hot-rolled state after 6 months The area shrinkage rate recovered significantly. This method shows that the effect of natural aging to eliminate hydrogen embrittlement is significant.
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