A motorized spindle is a set of components that includes the spindle itself and its accessories: the motorized spindle, the high-frequency inverter, the oil mist lubricator, the cooling unit, the built-in encoder, and the tool changer.

1. High-speed bearing technology

Electrospindles usually use dynamic and static pressure bearings, composite ceramic bearings or electromagnetic levitation bearings. Hydrostatic bearings have high stiffness and damping, can greatly improve machining efficiency, machining quality, extend tool life, reduce machining costs. Composite ceramic bearings are currently widely used in electric spindle units. The rolling elements of this type of bearings use hot-pressed Si3N4 ceramic balls, and the bearing rings are still steel rings. They have a high degree of standardization, require little change to the machine tool structure, and are easy to maintain. Electromagnetic suspension bearings have good high-speed performance, high precision, and are easy to diagnose and monitor online. However, due to the complexity of the electromagnetic measurement and control system, the price of this type of bearing is very expensive and has remained high for a long time, and has not yet been widely used.

2. High-speed motor technology

The electric spindle is a product of the fusion of the motor and the spindle. The rotor of the motor is the rotating part of the spindle. In theory, the electric spindle can be regarded as a high-speed motor. The key technology is dynamic balancing at high speed.

3. Lubrication

The lubrication of the electric spindle generally adopts timed and quantitative oil-gas lubrication; grease lubrication can also be used. The so-called timing means injecting oil at a certain time interval. The so-called quantitative means that the amount of lubricating oil each time is accurately controlled through a device called a quantitative valve. Oil-gas lubrication refers to the lubricating oil being blown into the ceramic bearing under the influence of compressed air. The oil quantity control is very important. Too little will not play a lubricating role; too much will cause heat due to the resistance of the oil when the bearing rotates at high speed.

4. Cooling device

In order to dissipate the heat of the high-speed electric spindle as quickly as possible, a circulating coolant is usually passed through the outer body of the electric spindle. The function of the cooling device is to maintain the temperature of the coolant.

5. Built-in pulse encoder

In order to realize automatic tool change and rigid tapping, the electric spindle has a built-in pulse encoder to achieve accurate phase angle control and coordination with feed.

6. Automatic tool changer

In order to be used in machining centers, the electric spindle is equipped with an automatic tool changer, including disc springs, broaching cylinders, etc.

7. High-frequency frequency conversion device

To achieve a speed of tens of thousands or even hundreds of thousands of revolutions per minute for the electric spindle, a high-frequency frequency conversion device must be used to drive the built-in high-speed motor of the electric spindle. The output frequency of the frequency converter must reach thousands or several kilohertz.