Electric spindleIt is an innovative technology that has emerged in the CNC lathe industry in recent years, combining lathe spindles with spindle motors. Along with linear motor technology and high-speed CNC tool technology, it will push high-speed production and processing into a new era. The electric spindle is a complete set of components, which includes the electric spindle itself and its accessories: electric spindle, high-frequency frequency converter, oil mist lubrication level device, cooler, built-in encoder, and tool changer. The electric spindle itself can directly install the hollow motor rotor on the high-speed electric spindle, and the motor stator is stabilized in the outer box hole of the high-speed electric spindle with the help of a cooling sleeve, becoming a complete high-speed electric spindle module. After conduction, the motor rotor can directly drive the high-speed electric spindle to run.

Unidirectional bearings often operate at high and ultra high speeds in electric spindles, so centrifugal force has a particularly significant impact on the operating state of one-way bearings. When in a stationary state, the contact points between the bearing steel ball and the inner and outer rings are A and B, respectively. When running at high speed, centrifugal force tends to cause the bearing steel ball to deflect outward, that is, A moves to A1 and B0 moves to B1. At this time, the contact angle of the inner ring will expand, and the contact angle of the outer ring will decrease. As a result, the center of mass of the bearing steel ball deviates from the axis of rotation, forming a gyroscopic moment.

The bearing steel ball will slip to a certain extent while rotating, and the sliding friction heat formed by sliding will not only increase the temperature of the one-way bearing, but also cause local annealing of the surface layer of the bearing steel ball in severe cases, increasing the degree of damage and burns. To overcome the influence of centrifugal force, one-way bearings operate with preload in high-speed electric spindles. Appropriate preload can keep the contact angle between the inner and outer rings consistent during operation, which not only increases the service life of one-way bearings, but also enhances the rigidity of one-way bearings and high-speed electric spindles.

If the preload is too large, the lubrication degree and heat dissipation environment of the one-way bearing will be poor. Under the same application environment, the cycle of the one-way bearing is short, which is very easy to burn or get stuck, and the high-speed characteristics will be worse. However, the support rigidity of the one-way bearing and high-speed electric spindle will be greatly increased. If the preload is too small, the overall rigidity and load-bearing capacity of the high-speed electric spindle will be significantly reduced.

If the preload value cannot escape the influence of the axial force and driving force borne by the high-speed electric spindle during operation, the high-speed electric spindle will generate significant vibration during operation, and the surface layer of the processed product workpiece will form significant vibration patterns. If the preload cannot control the gyroscope torque, the spindle bearing will suddenly heat up due to "slipping" during operation, and there will be significant signs of damage to the surface layer of the bearing steel ball.