Foreign motorized spindle is first used in internal grinder. In 1980s, with the development and need of CNC machine tools and high-speed cutting technology, motorized spindle technology was gradually applied to high-end CNC machine tools such as machining centers and CNC milling machines, which became one of the major achievements of machine tool technology in recent years. With the development of machine tool technology and high-speed cutting technology and the need of practical application, higher and higher requirements are put forward for the performance of machine tool motorized spindle. At present, foreign enterprises engaged in the research and development and production of motorized spindle of high-speed CNC machine tools mainly include: German GMN, Siemens, Swiss IBAG, American Setco, Italian Omlet, Faemat, Gammfier, Japanese Omlet, etc., among which GMN, IBAG and Omlet are the most important. The motorized spindles produced by these companies have the following characteristics compared with those produced in China: ① High power and high speed. ② High-speed and high-rigidity bearings are adopted. Foreign high-speed precision spindles adopt high-speed and high-stiffness bearings, mainly ceramic bearings and hydrodynamic bearings, and air-lubricated bearings and magnetic bearings are used in special occasions. ③ High level of precision machining and precision assembly technology. ④ The supporting control system has a high level. These control systems include rotor automatic balancing system, bearing oil-gas lubrication and precision control system, stator and rotor cooling temperature precision control system, spindle deformation temperature compensation precision control system and so on. On this basis, foreign manufacturers such as the United States, Japan, Germany, Italy and Switzerland have produced various commercial high-speed machine tools. For example, the Swiss company Myquelau is a world-famous manufacturer of precision machine tools. The machine tools produced by it are equipped with high-speed motorized spindles up to 60000 r/min, which can meet different cutting requirements. All motorized spindles are equipped with constant-temperature cooling water jackets for cooling spindle motors and bearings, and composite ceramic bearings are lubricated by high-pressure oil mist. All motorized spindles adopt vector control technology, which can output large torque at low speed.

The development trend of motorized spindle technology is mainly manifested in the following aspects:

Continue to develop towards high speed and high rigidity.

Due to the need of high-speed cutting and practical application, with the development of spindle bearing and its lubrication technology, precision machining technology, precision dynamic balance technology, high-speed cutter and its interface technology, the high-speed motorized spindle of CNC machine tools has become a major trend at present, such as the motorized spindle for drilling and milling, the rotating speed of HF42 of IBAG in Switzerland reaches 140000 r/min, and the motorized spindle of PCB drilling machine d 10 of Zephyr Company in Britain, and the machining center. The highest speed of Swiss FISCHER reaches 42,000 rpm, and that of Italian CAMFIOR reaches 75,000 rpm. In terms of the rigidity of motorized spindle system, due to the development of bearing and its lubrication technology, the rigidity of motorized spindle system is getting bigger and bigger, which meets the needs of the development of high-speed, high-efficiency and precision machining of CNC machine tools.

Developing in the direction of high speed, high power, low speed and high torque.

According to the needs of practical use, most CNC machine tools need to meet the requirements of heavy cutting in low-speed rough machining and finishing in high-speed cutting at the same time. Therefore, the motorized spindle of machine tool should have the performance of low speed and high torque and high speed and high power. For example, the motorized spindle for machining centers produced by Italian CAMFIOR, Swiss Step—Tec, German GMN and other manufacturers is not difficult to output torque above 200Nm at low speed, and the maximum torque of motorized spindle for CNC milling machines and lathes in Germany CYTEC is 630n·m；; ; In terms of high power at high speed, it is generally between 50kW; The maximum output power of CYTEC motorized spindle is 50kW；; Swiss Step—Tec motorized spindle has a maximum power of 65kW(S 1), which is used for aircraft manufacturing and mold processing. It is even reported that the power of motorized spindle reaches 80kW.

Further develop in the direction of high precision, high reliability and long life.

Users put forward higher and higher requirements for the accuracy and reliability of CNC machine tools. As one of the core functional components of CNC machine tools, motorized spindle requires higher and higher accuracy and reliability. If the radial runout of the spindle is within 0.0065438±0mm, the axial positioning is accurate.

The performance and form of the built-in motor of motorized spindle are diversified.

In order to meet the needs of practical application, the performance of motorized spindle motor has been improved. For example, the ratio of constant torque, high speed and constant power (that is, constant power speed regulation range) of Swiss Fischer spindle motor has reached L: 14. In addition, the motorized spindle of permanent magnet synchronous motor appeared. Compared with the electric spindle of asynchronous motor with the same power, the electric spindle of synchronous motor is small in size, which is beneficial to improve power density and realize small size and high power.

Develop in the direction of quick start and quick stop.

In order to shorten the auxiliary time and improve the efficiency, it is required that the start-stop time of the motorized spindle of CNC machine tools be as short as possible, so a higher start-stop acceleration (deceleration) speed is needed. At present, the start-stop acceleration of electric spindle of foreign machine tools can reach above lg, and the full-speed start-stop time is within ls.

Bearings, preload application methods and lubrication methods are diversified.

In addition to traditional steel rolling bearings, ceramic ball bearings have been widely used in recent years. Lubrication methods include grease, oil mist, oil gas, etc. In particular, the oil-gas lubrication method (also known as oil-gas lubrication) which has the characteristics of adapting to high speed, environmental protection and energy saving has been popularized and applied more and more widely. Besides rigid preload (also called positioning preload) and elastic preload (also called constant pressure preload), an intelligent preload method has been developed for rolling bearings, that is, the bearing is preloaded by hydraulic cylinder, and the preload can be controlled according to the specific working conditions such as spindle speed and load, so as to make the bearing have better supporting performance. A series of products of motorized spindle supported by non-contact bearing have been put on the market, such as magnetic bearing and air bearing motorized spindle (IBAG, Switzerland, etc.). ) and liquid bearing motorized spindle (ingersoll, USA, etc.). ).

The tool interface gradually tends to HSK and Capto tool holder technology.

After the spindle of a high-speed machine tool, the traditional CAT (7: 24) tool holder structure can no longer meet the use requirements due to the centrifugal force, so HSK (1: 10) and other tool holder interface forms that meet the high-speed requirements need to be adopted. HSK tool rest has outstanding static and dynamic connection rigidity, large torque transmission capacity, high tool positioning accuracy and reliable connection, which is especially suitable for high-speed and high-precision occasions. Therefore, HSK tool rest interface has been widely used by high-speed motorized spindles (such as IBAG in Switzerland, CYTEC in Germany, CAMFIOR in Italy, etc.). ). In recent years, the Capto tool interface proposed by sandvik Company has also been applied in the machine tool industry. Its basic principle is similar to HSK interface, but its ability to transmit torque is slightly greater. The disadvantage is that the machining of the inner hole at the spindle end is more difficult and the process is more complicated.

Develop in the direction of multi-function and intelligence

Multifunctional aspects, such as accurate positioning of angular stop (quasi-stop), C-axis transmission, tool changing and blowing, filling coolant in the air, gas sealing at the shaft end, low-speed torque amplification, accurate compensation of axial positioning, automatic dynamic balance technology of tool changing, etc. In the aspect of intelligence, it is mainly manifested in various safety protection and fault monitoring and diagnosis measures, such as tool change interlocking protection, bearing temperature monitoring, motor overload and overheating protection, bearing unloading protection when loosening the tool, spindle vibration signal monitoring and fault abnormal diagnosis, automatic compensation for axial position change, grinding wheel dressing process signal monitoring and automatic control, tool wear and damage signal monitoring, etc. For example, the Step-Tec motorized spindle is equipped with a diagnostic module, and maintenance personnel can read data through infrared data correlation, identify overload and count the working condition of the motorized spindle.