At present, CNC lathesElectric spindleThe method of variable frequency speed regulation is usually used, which includes several control methods such as variable frequency drive and control, vector control drive and control, and direct torque control.

Usually, frequency conversion is used for scalar drive and control, and its driving and control characteristics are constant torque drive, with output power proportional to speed. The dynamic characteristics of variable frequency control are usually not ideal, and the control characteristics are poor at low speeds. The output power is not very stable, and it does not have a C-axis function module. But it is affordable and easy to construct, usually used for grinding machines and high-speed milling machines.

CNC lathe electric spindle

The application of vector control technology is modeled after the control of DC motors, using rotor electromagnetic field orientation and vector conversion methods to achieve driving and control, with excellent dynamic characteristics. The vector control driver has a large torque value at the beginning of startup, and coupled with the simple structure of the electric spindle itself and relatively small inertia, the acceleration during startup is large, which can achieve instantaneous speed reaching the allowable limit speed after startup.

This type of driver has two types: open-loop and closed-loop. The latter type can provide feedback on specific position and speed information, not only with better dynamic characteristics, but also with a C-axis functional module; The former type has poor dynamic characteristics and does not have a C-axis functional module, but its price is relatively low.

Direct torque control is another latest high-performance AC transmission technology application developed after vector control technology. Its control concept is novel, the system structure is simple and clear, and it is more suitable for driving high-speed electric spindles. It can better meet the dynamic and static characteristics of high-speed rotation, wide speed range, and high-speed instantaneous stop of high-speed electric spindles. It has become a popular technology application in the field of AC transmission systems.

The electric spindle of a CNC lathe is a high-precision operating component, and the specific reasons that affect the precision of the electric spindle rotation are:

1. The axial unequal bending stiffness and thermal deformation of the electric spindle system. In order to ensure that our electric spindle can operate normally with precision, we need to minimize the wear rate of the corresponding components of the bearings as much as possible. The specific method to reduce damage is lubrication, which involves lubricating the bearings to ensure excellent lubrication and cooling effects. Choosing a reasonable, effective, and appropriate lubrication method is an important condition for ensuring the normal operation of the electric spindle.

2. The deviation of the electric spindle mainly includes the roundness deviation of the electric spindle support journal, coaxiality deviation (causing the axis of the electric spindle to tilt), and the perpendicularity deviation of the axial bearing surface of the electric spindle journal from the axis (affecting the axial displacement of the electric spindle).

3. Bearing deviation. Bearing deviation includes roundness deviation of sliding bearing inner holes or rolling bearing raceways, waviness of sliding bearing inner holes or rolling bearing raceways, shape and specification deviation of rolling bearing rollers, perpendicularity deviation of bearing precise positioning end faces and axis lines, parallelism deviation between bearing end faces, bearing clearances, and force deformation during turning.