Electric spindleIt is a new technology that integrates machine tool spindles and spindle motors in the field of CNC machine tools. Combining linear motor technology and high-speed tool technology, it has pushed high-speed machining into a new era. Electric spindle is a set of components, including the electric spindle itself and its accessories: electric spindle, high-frequency frequency converter, oil mist lubricator, cooling device, built-in encoder, tool changer, etc. The structural form of integrating the spindle motor with the machine tool spindle makes the spindle components relatively independent of the transmission system and overall structure of the machine tool. Therefore, it can be made into a "spindle unit", commonly known as an "electric spindle". Its characteristics are high speed, high precision, low noise, and the inner ring with a locking structure is more suitable for spray lubrication.

The rotor of the motor is directly used as the spindle of the machine tool, and the housing of the spindle unit is the base of the motor, which cooperates with other parts to achieve the integration of the motor and the machine tool spindle. With the rapid development and improvement of electrical transmission technology (frequency conversion speed regulation technology, motor vector control technology, etc.), the mechanical structure of the main transmission system of high-speed CNC machine tools has been greatly simplified, and pulley transmission and gear transmission have been basically eliminated. The spindle of the machine tool is directly driven by the built-in electric motor, which shortens the length of the main transmission chain of the machine tool to zero, thus achieving "zero transmission" of the machine tool.

The transmission structure of combining the spindle motor with the machine tool spindle makes the spindle components relatively independent of the transmission system and overall structure of the machine tool, thus making it possible to create a "spindle unit" as an "electric spindle". Due to the current use of AC high-frequency motors, electric spindles are also known as "High High Spindles". Because there is no intermediate transmission link, it is sometimes referred to as a "DirectDriveSpindle"

In CNC machine tools, the electric spindle usually adopts the method of variable frequency speed regulation. Currently, there are three main control modes: ordinary variable frequency drive and control, vector control drive and control, and direct torque control. Ordinary frequency conversion is scalar drive and control, with constant torque drive as its driving and control characteristics, and output power is proportional to speed. The dynamic performance of ordinary variable frequency control is not ideal, with poor control performance at low speeds, unstable output power, and no C-axis function. But the price is cheap, the structure is simple, and it is usually used for grinding machines and ordinary high-speed milling machines.

Vector control technology imitates the control of DC motors, guided by the rotor magnetic field, and achieves driving and control through vector transformation, with good dynamic performance. At the beginning of startup, the vector control driver has a large torque value. In addition, the electric spindle itself has a simple structure and low inertia, so the starting acceleration is large, and it can instantly reach the allowed maximum speed after starting. This type of driver has two types: open-loop and closed-loop. The latter can achieve position and velocity feedback, not only with better dynamic performance, but also with C-axis functionality. The former has poor dynamic performance and no C-axis function, but it is cheaper.

Direct torque control is another new high-performance AC speed control technology 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, which can meet the requirements of high-speed electric spindles. High speed, wide speed range, dynamic and static characteristics of high speed and instantaneous stop have become popular technologies in the field of AC frequency converters.