In addition to the rolling bearing, the spindle of the grinder also uses the dynamic pressure sliding bearing, which is characterized by stable movement, good vibration resistance and high rotation speed. However, the hydrodynamic sliding bearing can only produce pressure oil film at a constant operating speed to realize pure liquid friction. Therefore, it is not suitable for spindle components with low operating speed, such as workpiece head frame spindle, etc. In addition, because the speed of the main shaft is too low when starting and stopping, the pressure oil film cannot be established, so it is inevitable to have direct contact between the journal and the metal surface of the bearing, resulting in wear; At the same time, the starting torque is large, and the bearing is easy to heat up. During the operation of the main shaft, the offset of the axis will vary with the working conditions such as external load and speed, and there are certain restrictions on the rotation accuracy and stability. The hydrostatic bearing is different. Because it forms a pressure oil film by supplying pressure oil from the external hydraulic system, and the stiffness of the oil film depends on the structural size parameters of the bearing itself and the performance of the restrictor, which is independent of the spindle speed and external load, it can ensure that the bearing is in a stable pure liquid friction state under different working conditions. The bearing wear is very small, which can maintain the working accuracy for a long time. this
In addition, when the variable throttle is adopted, the oil film stiffness of the bearing is very large, and the change of the spindle axis position is very small when the load changes, which can maintain high rotation accuracy. The disadvantage of using hydrostatic bearing is that it must be equipped with a special oil supply system, which has high manufacturing cost, large floor area, strict requirements for lubricating oil filtration and complex maintenance.