The speed of the motor bearing is mainly limited by the temperature rise caused by the internal friction heating of the bearing model. When the speed exceeds a certain limit, the bearing will not continue to rotate due to burns. The limit speed of a bearing is the limit value of the speed at which it can rotate continuously without generating frictional heat that causes burns. Therefore, the limit speed of the bearing depends on various factors such as the type, size and accuracy of the bearing, the lubrication method, the quality and quantity of the lubricant, the material and type of the cage, and the load conditions. The limit speeds of various bearings when grease lubrication and oil lubrication (oil bath lubrication) are used are respectively stated in the bearing size table. The value indicates that the standard design bearing is under general load conditions (C/P≥13, Fa/Fr≤0.25) ) The limit value of the rotation speed when rotating down. Modification of limit speed: load condition C/P＜13 (that is, when the equivalent dynamic load P exceeds about 8% of the basic dynamic load rating C), or when the axial load in the combined load exceeds 25% of the radial load, Use formula (1) to correct the limit speed. nau003df1·f2·n(1) The modified limit, rpm The correction factor related to the load condition (Figure 1) The correction factor related to the composite load (Figure 2) The limit speed under general load conditions, rpm (refer to bearing Size table) Basic dynamic load rating, N{kgf} equivalent dynamic load, N{kgf} radial load, N{kgf} axial load, N{kgf} pole motor and high-speed rotation Note: The bearing is rotating at high speed, especially When the speed is close to or exceeds 70% of the limit speed recorded in the dimension table, the following matters should be paid attention to: (1) Use high-precision bearings (2) Analyze the internal clearance of the bearing (consider the reduction in the internal clearance of the bearing caused by temperature rise ) (3) Analyze the type of cage material (4) Analyze the lubrication method.