The development of sensor detection technology has also greatly improved the dynamic response performance and positioning accuracy of the AC motor speed control system. Commonly used Hall sensors have a response time of less than 1 μs. The AC motor speed control system generally uses a brushless resolver, a hybrid photoelectric encoder and an absolute encoder as position and speed sensors. As their speed and resolution continue to increase, the dynamic response, speed range, and low speed performance of the system increase accordingly. The traditional encoder with A and B (two-phase signal, because it can not balance resolution and high speed, and too many signal lines, thus affecting the realization of high-precision, high-speed servo system. And the new encoder Overcoming the above shortcomings, such as the pulse encoder (absolute type) produced by FANUC Corporation of Japan, because it converts the angle from the sine and cosine signals into digital quantities, it has a high speed of 4000r/min and up to 1000000p/r or 65536p/r. In addition, the servo motor itself is also developing at a high speed, and the high-speed encoder cooperates with the rapid feed of 60m/min or even 100m/min and the acceleration of 1g. The improvement makes the motor rotate more smoothly, and with the high-speed digital servo software, the motor can be smooth and crawl free even when it is rotated less than 1μm. New types such as IGBT (Insulated Gate Bipolar Transistor) and IPM (Intelligent Power Module) The development of a new generation of high-carrier, low-noise inverters based on power electronics, and the introduction of new control software, introduced a new dimension to variable frequency speed regulation. The original inverter used only for open-loop control has evolved into a "universal drive" that can be used for both open-loop control and closed-loop control. It is a Unidrive product from British CT and a German AMK. The company's AMKASYN products represent the new inverter on the stage. The following is a brief introduction of CT's Unidrive products.

In 1996, CT introduced a family of general-purpose drivers. Its control board is mainly composed of Intel80166CPU, flash memory and three dedicated chips designed by CT. The hardware is highly integrated, and the number of control board chips is only 1/4 of the current general-purpose inverters on the market. It can be divided into five grades according to power, of which level 1 (output power is 0.75~4kW) is the basic unit, grade 5 rated power is 120kW (it consists of basic unit plus extended power unit), and up to 8 parallel units can be composed. 1000kW power output.

The universal drive is equipped with a large number of parameters and 20 menu functions, which is convenient for users to set V/F control, speed sensorless open-loop vector control, closed-loop flux vector control, permanent magnet without changing the hardware configuration. Five working modes, such as brushless AC servo motor control and regeneration unit, are suitable for various occasions. The emergence of universal drives will greatly reduce the hardware cost of the machine feed system and spindle system.

(3) High-speed and integrated high-power electric spindle of machine tool

At present, one of the development trends of the world's numerical control technology and its equipment is high speed, high efficiency and high precision. Since the 1980s, due to the breakthrough of the functional components such as the spindle and feed system of CNC machine tools, the spindle speed and feed speed of CNC machine tools have been greatly improved, and the overall advancement of manufacturing technology has enabled metal cutting to enter high-speed cutting. New stage. Since the 1990s, countries in Europe, the United States, and Japan have been competing to develop and apply a new generation of high-speed CNC machine tools, speeding up the pace of development of high-speed machine tools. The number of revolutions of the high-speed electric spindle unit is above 30000r/min (some up to 1×105r/min); the moving speed of the table (feed rate): at a resolution of 1μm, at 100m/min (some to 200m/ Min) or more, at a resolution of 0.1 μs, at 24 m/min or more.

In order to achieve high-speed, high-precision machining, the matching functional components such as high-power high-speed electric spindle, high-plus/deceleration linear motor drive feed components and high-performance control system have been rapidly developed, and the application field is further expanded.

Ultra-high-speed machining is a high-tech that makes the second revolutionary leap in manufacturing technology after CNC technology. Ultra-high-speed machine tools are the material basis for ultra-high-speed machining, while high-speed spindle units are the "core" components of ultra-high-speed machine tools. Its performance directly determines the ultra-high-speed machining performance of the machine. The best form of spindle suitable for high-speed operation is to directly insert the stator and rotor of the spindle motor into the inside of the spindle assembly to form an electric spindle, which realizes the integration of the machine tool spindle system and “zero transmission”. The electric spindle has the advantages of compact structure, light weight, small inertia and good dynamic characteristics. It can improve the dynamic balance of the machine tool and avoid vibration and noise. It has been widely used in ultra-high-speed cutting machine tools.

The operating speed of the electric spindle is extremely high, which imposes very strict requirements on its structural design, manufacture and control, and brings a series of technical problems, such as heat dissipation, dynamic balance, support, lubrication and control of the spindle. In the application, these technical problems must be properly solved to ensure the high-speed operation of the electric spindle and the reliability of precision machining.

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Hex Bolt

HEX BOLT: One type of fastener, consisting of the head and the rod (cylinder with external full/half threads) and usually uesd together with nut.washer.