Deep groove ball bearings mainly bear radial load, but also can bear radial load and axial load. When it is only under radial load, the contact Angle is zero. When the deep groove ball bearing has a larger radial clearance, it has the performance of angular contact bearing and can withstand larger axial load. The friction coefficient of deep groove ball bearing is very small and the limit speed is very high.
But because there is a gap in the deep groove ball bearing, the inner and outer rings will move relative under the action of load, which will reduce the hardness of the bearing, make the axial and radial vibration of the bearing, and the working accuracy and life of the machine will be affected. In order to reduce this vibration, for high precision and high speed mechanical equipment, often in the installation of deep groove ball bearings will be used in the preloading method, that is to say, when the installation of the bearing is given a certain radial or axial load, to eliminate the original clearance, and can make the bearing body and the inner and outer ring elastic deformation, so as to effectively avoid the relative movement between the inner ring.
Generally, bearing structure and preload compensation principle are adopted to control the preload. When the speed is not too high and the speed range is relatively small, the steel preload is used to apply the preload, the preload will change with the heat of the shafting parts. When the speed is high and the speed range is large, the elastic preload device can reduce the influence of temperature and speed on the preload. In this method, the control of preload is very effective and easy to operate, but once the bearing is assembled, its preload cannot be adjusted.
First, the purpose of preloading
Preloading the spindle bearing can make the ball and raceway eliminate the original clearance and form elastic deformation. When the deep groove ball bearing bears the external load, the bearing will have a certain rigidity. When the bearing is installed in the direction opposite to the external load, there will be no clearance between the ball and raceway due to the external load, so as to improve the rotary accuracy of the spindle. The rigidity of the spindle is increased and the service life is prolonged. The noise is also reduced.
Two, the principle of preloading
Generally speaking, the size of the preload is determined according to the spindle rotation accuracy, working load size and speed level.
1, the main shaft load is small, the rotation accuracy is high and the speed is low, can take a larger preload.
2, the working load is large, the speed is high, because it is easy to produce heat expansion, it is appropriate to take a small pre-load.
Deep groove ball bearing structure design is reasonable, but also should have sex, there will be a long bearing life. The rationality, stability and nature of each processing technology of deep groove ball bearing will also affect the life of bearings. The heat treatment and grinding processes which affect the quality of deep groove ball bearings are often directly related to the failure of bearings. The research on the metamorphic layer of the working surface of deep groove ball bearing shows that the manufacturing of bearing generally needs to go through forging, heat treatment, grinding, turning and assembly. The relationship between grinding process and bearing surface quality is very close.
Whether the installation of deep groove ball bearing is correct affects its life, accuracy and performance. Therefore, the design and assembly department should fully study the installation of deep groove ball bearings. Installation must be performed in accordance with operating standards. The installation of thin-wall bearings should be based on the bearing structure, size and matching nature of bearing components. The pressure should be directly applied to the end face of the tight and cool closed ring, and the pressure should not be transferred through the rolling body.